Cytokine control of systemic hypoxia tolerance in Drosophila

Cytokine control of systemic hypoxia tolerance in Drosophila | bioRxiv /* */ /* */ <!-- <!-- /*! * yepnope1.5.4 * (c) WTFPL, GPLv2 */ (function(a,b,c){function d(a){return"[object Function]"==o.call(a)}function e(a){return"string"==typeof a}function f(){}function g(a){return!a||"loaded"==a||"complete"==a||"uninitialized"==a}function h(){var a=p.shift();q=1,a?a.t?m(function(){("c"==a.t?B.injectCss:B.injectJs)(a.s,0,a.a,a.x,a.e,1)},0):(a(),h()):q=0}function i(a,c,d,e,f,i,j){function k(b){if(!o&&g(l.readyState)&&(u.r=o=1,!q&&h(),l.onload=l.onreadystatechange=null,b)){"img"!=a&&m(function(){t.removeChild(l)},50);for(var d in y[c])y[c].hasOwnProperty(d)&&y[c][d].onload()}}var j=j||B.errorTimeout,l=b.createElement(a),o=0,r=0,u={t:d,s:c,e:f,a:i,x:j};1===y[c]&&(r=1,y[c]=[]),"object"==a?l.data=c:(l.src=c,l.type=a),l.width=l.height="0",l.onerror=l.onload=l.onreadystatechange=function(){k.call(this,r)},p.splice(e,0,u),"img"!=a&&(r||2===y[c]?(t.insertBefore(l,s?null:n),m(k,j)):y[c].push(l))}function j(a,b,c,d,f){return q=0,b=b||"j",e(a)?i("c"==b?v:u,a,b,this.i++,c,d,f):(p.splice(this.i++,0,a),1==p.length&&h()),this}function k(){var a=B;return a.loader={load:j,i:0},a}var l=b.documentElement,m=a.setTimeout,n=b.getElementsByTagName("script")[0],o={}.toString,p=[],q=0,r="MozAppearance"in l.style,s=r&&!!b.createRange().compareNode,t=s?l:n.parentNode,l=a.opera&&"[object Opera]"==o.call(a.opera),l=!!b.attachEvent&&!l,u=r?"object":l?"script":"img",v=l?"script":u,w=Array.isArray||function(a){return"[object Array]"==o.call(a)},x=[],y={},z={timeout:function(a,b){return b.length&&(a.timeout=b[0]),a}},A,B;B=function(a){function b(a){var a=a.split("!"),b=x.length,c=a.pop(),d=a.length,c={url:c,origUrl:c,prefixes:a},e,f,g;for(f=0;f<d;f++)g=a[f].split("="),(e=z[g.shift()])&&(c=e(c,g));for(f=0;f<b;f++)c=x[f](c);return c}function g(a,e,f,g,h){var i=b(a),j=i.autoCallback;i.url.split(".").pop().split("?").shift(),i.bypass||(e&&(e=d(e)?e:e[a]||e[g]||e[a.split("/").pop().split("?")[0]]),i.instead?i.instead(a,e,f,g,h):(y[i.url]?i.noexec=!0:y[i.url]=1,f.load(i.url,i.forceCSS||!i.forceJS&&"css"==i.url.split(".").pop().split("?").shift()?"c":c,i.noexec,i.attrs,i.timeout),(d(e)||d(j))&&f.load(function(){k(),e&&e(i.origUrl,h,g),j&&j(i.origUrl,h,g),y[i.url]=2})))}function h(a,b){function c(a,c){if(a){if(e(a))c||(j=function(){var a=[].slice.call(arguments);k.apply(this,a),l()}),g(a,j,b,0,h);else if(Object(a)===a)for(n in m=function(){var b=0,c;for(c in a)a.hasOwnProperty(c)&&b++;return b}(),a)a.hasOwnProperty(n)&&(!c&&!--m&&(d(j)?j=function(){var a=[].slice.call(arguments);k.apply(this,a),l()}:j[n]=function(a){return function(){var b=[].slice.call(arguments);a&&a.apply(this,b),l()}}(k[n])),g(a[n],j,b,n,h))}else!c&&l()}var h=!!a.test,i=a.load||a.both,j=a.callback||f,k=j,l=a.complete||f,m,n;c(h?a.yep:a.nope,!!i),i&&c(i)}var i,j,l=this.yepnope.loader;if(e(a))g(a,0,l,0);else if(w(a))for(i=0;i (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0];var j=d.createElement(s);var dl=l!='dataLayer'?'&l='+l:'';j.src='//www.googletagmanager.com/gtm.js?id='+i+dl;j.type='text/javascript';j.async=true;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-M677548'); Skip to main content Home About Submit ALERTS / RSS Search for this keyword Advanced Search New Results Cytokine control of systemic hypoxia tolerance in Drosophila Kate Ding , Prajakta Bodkhe , Byoungchun Lee , Danielle Polan , Amy Wycislik , Tiffany Cheung , Sophie Wu , Savraj S Grewal doi: https://doi.org/10.1101/2025.06.30.661614 Kate Ding Arnie Charbonneau Cancer Institute, Alberta Children’s Hospital Research Institute, and Department of Biochemistry and Molecular Biology Calgary, University of Calgary , Alberta T2N 4N1, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Prajakta Bodkhe Arnie Charbonneau Cancer Institute, Alberta Children’s Hospital Research Institute, and Department of Biochemistry and Molecular Biology Calgary, University of Calgary , Alberta T2N 4N1, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Byoungchun Lee Arnie Charbonneau Cancer Institute, Alberta Children’s Hospital Research Institute, and Department of Biochemistry and Molecular Biology Calgary, University of Calgary , Alberta T2N 4N1, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Danielle Polan Arnie Charbonneau Cancer Institute, Alberta Children’s Hospital Research Institute, and Department of Biochemistry and Molecular Biology Calgary, University of Calgary , Alberta T2N 4N1, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Amy Wycislik Arnie Charbonneau Cancer Institute, Alberta Children’s Hospital Research Institute, and Department of Biochemistry and Molecular Biology Calgary, University of Calgary , Alberta T2N 4N1, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Tiffany Cheung Arnie Charbonneau Cancer Institute, Alberta Children’s Hospital Research Institute, and Department of Biochemistry and Molecular Biology Calgary, University of Calgary , Alberta T2N 4N1, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Sophie Wu Arnie Charbonneau Cancer Institute, Alberta Children’s Hospital Research Institute, and Department of Biochemistry and Molecular Biology Calgary, University of Calgary , Alberta T2N 4N1, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site Savraj S Grewal Arnie Charbonneau Cancer Institute, Alberta Children’s Hospital Research Institute, and Department of Biochemistry and Molecular Biology Calgary, University of Calgary , Alberta T2N 4N1, Canada Find this author on Google Scholar Find this author on PubMed Search for this author on this site For correspondence: grewalss{at}ucalgary.ca Abstract Full Text Info/History Metrics Preview PDF Summary Systemic hypoxia—reduction in oxygen supply to all tissues and organs—occurs in both physiological and pathological conditions in animals. Under these conditions, organisms must adapt their physiology to ensure proper functioning and survival. While extensive research has characterized how individual cells sense and adapt to low oxygen conditions, the mechanisms that coordinate whole-body responses to systemic hypoxia remain poorly understood. In this study, we uncover an interorgan signaling response mediated by the cytokine Unpaired-3 (upd3) that is important for systemic hypoxia tolerance in Drosophila . We demonstrate that hypoxia rapidly induces upd3 expression and activates JAK/STAT signaling in both larvae and adults. Interestingly, we discovered a sex-specific requirement for this pathway, with females requiring upd3 for hypoxia survival while males do not. We also identify the intestine as a critical source of hypoxia-induced upd3 and show that gut-derived upd3 signals to the fat body and oenocytes to mediate hypoxia tolerance by promoting nitric oxide synthase expression. Furthermore, we reveal an unexpected role for the canonical hypoxia response transcription factor HIF-1α/sima as a molecular brake, preventing lethal upd3 overproduction, revealing that hypoxia survival requires precise cytokine dosage control. Our findings define a gut-to-fat/oenocyte signaling axis that coordinates systemic hypoxia adaptation, highlighting the complex interplay between classic hypoxia response pathways and cytokine signaling in maintaining organismal homeostasis during oxygen limitation. This work provides important insights into how organisms adapt to systemic hypoxia, with potential implications for understanding systemic hypoxia-related human pathologies such as respiratory disorders and sleep apnea. Introduction Oxygen is essential for aerobic life, serving as the terminal electron acceptor in cellular respiration that powers energy production across the animal kingdom. When oxygen availability becomes limited—a condition known as hypoxia—organisms must rapidly adapt their physiology and metabolism to maintain homeostasis ( Semenza, 2011 ). These adaptations are critical not only during normal animal development and in specific ecological niches but also in numerous pathological conditions that result in oxygen deprivation such as stroke and lung disorders ( Bickler and Buck, 2007 ; Jahani et al., 2020 ; Ramirez et al., 2007 ; Samanta et al., 2017 ; Semenza, 2014b ; Stupnikov and Cardoso, 2017 ). Although atmospheric air contains ∼20% oxygen, cells and tissues typically experience significantly lower oxygen levels under physiological conditions. For example, the early fetus develops in an environment where oxygen levels can be as low as 1% ( Dunwoodie, 2009 ), while oxygen levels in adult tissues can vary from 1 to 10% depending on the organ ( McKeown, 2014 ). In many diseases, oxygen supply becomes further restricted, either locally (as in tumors, ischemia, and stroke) or systemically (as in respiratory disorders, COVID-19, and sleep apnea) ( May and Mehra, 2014 ; Semenza, 2011 ; 2014a ; b; Xie and Simon, 2017 ). Systemic hypoxia results from insufficient oxygen reaching all of the body’s tissues and organs, potentially leading to multi-organ failure and life-threatening complications. Extensive work in cell culture has established how individual cells sense and respond to low oxygen, particularly how they modulate gene expression and reprogram metabolism to survive hypoxic conditions ( Holdsworth and Gibbs, 2020 ; Nakazawa et al., 2016 ; Schito and Rey, 2018 ; Xie and Simon, 2017 ). In contrast, responses to systemic hypoxia in whole animals represents a fundamentally different challenge that requires systems-level coordination ( Baik and Jain, 2020 ; Midha et al., 2023 ; Samanta et al ., 2017 ). These responses likely rely on inter-organ communication networks to integrate oxygen sensing across multiple organs, but the nature of these networks and how they operate remain largely unexplored. Drosophila melanogaster provides an excellent model system for investigating organismal adaptive responses to hypoxia ( Callier et al., 2015 ; Callier et al., 2013 ; Farzin et al., 2014 ; Harrison et al., 2018 ; Harrison and Haddad, 2011 ). In their natural ecology, Drosophila larvae grow in rotting, fermenting food rich in microorganisms—an environment characterized by low ambient oxygen ( Callier et al ., 2015 ; Markow, 2015 ). They have therefore evolved multiple sophisticated mechanisms to tolerate hypoxia. One key pathway involves the conserved hypoxia-sensing transcription factor HIF-1α (known as sima in Drosophila ), which is stabilized under low oxygen conditions and subsequently activates genes involved in metabolic adaptation and oxygen delivery ( Centanin et al., 2008 ; Centanin et al., 2005 ; Gorr et al., 2006 ; Lavista-Llanos et al., 2002 ; Romero et al., 2007 ; Texada et al., 2019 ). Drosophila research has also pioneered our understanding of inter-organ communication networks, revealing how specific tissues can detect environmental changes and signal to other organs to coordinate whole-body physiological responses ( Alvarez-Ochoa et al., 2021 ; Boulan et al., 2015 ; Kannangara et al., 2021 ; Kim et al., 2021b ; Leopold and Perrimon, 2007 ; Malita and Rewitz, 2021 ; Medina et al., 2022 ; Meschi and Delanoue, 2021 ; Okamoto and Watanabe, 2022 ; Owusu-Ansah and Perrimon, 2015 ; Rajan and Perrimon, 2011 ; Texada et al., 2020 ; Yoon et al., 2023 ). Thus, while all cells can adjust their metabolism in response to changes within their local environment, these tissue-level sensors ensure that physiological adaptations to environmental conditions are coordinated across multiple organs according to the organism’s overall needs. This has been best exemplified in the context of how flies adapt to fluctuations in dietary nutrient availability. Extensive work has shown how tissues such as the gut, fat body, and brain couple sensing of nutrients to behavioral, physiological, and metabolic adaptations through a complex inter-organ signaling network ( Droujinine and Perrimon, 2016 ; Koyama et al., 2020 ; Medina et al ., 2022 ; Meschi and Delanoue, 2021 ; Tennessen and Thummel, 2011 ). A few reports have indicated that similar tissue-tissue signaling responses may also underlie organismal adaptation to hypoxia. For example, sima activation in the larval fat body triggers fat-to-brain signals that suppress insulin-like peptide production, reducing growth under oxygen-limited conditions ( Texada et al ., 2019 ), while sima induction in specialized neurons modifies neuroendocrine signaling to stimulate blood cell production in hypoxia ( Cho et al., 2018 ). Nevertheless, the inter-organ networks coordinating systemic hypoxia adaptation remain poorly understood. The Unpaired (upd) family of cytokines are key regulators of interorgan communication in Drosophila ( Zandawala and Gera, 2024 ). These secreted signaling molecules activate the conserved JAK/STAT pathway by binding to their cell surface receptor, Domeless ( Agaisse and Perrimon, 2004 ). Upds play an important role in mediating communication between tissues to maintain metabolic and physiological homeostasis, especially in response to fluctuations in nutrient availability ( Ingaramo et al., 2020 ; Rajan et al., 2017 ; Rajan and Perrimon, 2012 ; Zhao and Karpac, 2017 ). Additionally, upds can be induced by a variety of stressors including pathogenic infection, oxidative stress, nutrient stress, and tissue damage ( Hersperger et al., 2024 ; Srinivasan et al., 2016 ; Yang et al., 2015 ). Importantly, the source of upd production varies with the specific stress context, as does the target tissue and the resulting physiological effects. This context-dependent signaling allows upds to orchestrate complex, multi-tissue responses that coordinate activities across the gut, fat body, brain, cardiac tissue, and immune cells to control tissue repair, metabolism, endocrine signaling, and growth ( Brent and Rajan, 2020 ; Cai et al., 2021 ; Chakrabarti et al., 2016 ; Ding et al., 2021 ; Gera et al., 2022 ; Hersperger et al ., 2024 ; Houtz et al., 2017 ; Huang et al., 2020 ; Ingaramo et al ., 2020 ; Jiang et al., 2009 ; Kierdorf et al., 2020 ; Liu et al., 2025 ; Liu et al., 2024 ; Nagai et al., 2023 ; Obata et al., 2018 ; Osman et al., 2012 ; Rai et al., 2025 ; Rajan et al ., 2017 ; Rajan and Perrimon, 2012 ; Romao et al., 2021 ; Shin et al., 2020 ; Sodders et al., 2025 ; Srinivasan et al ., 2016 ; von Frieling et al., 2020 ; Wang et al., 2014 ; Woodcock et al., 2015 ; Yang et al ., 2015 ; Zhao and Karpac, 2017 ; Zhou et al., 2013 ). A critical aspect of upd signaling is its context-dependent role in stress responses, which can be either adaptive or detrimental to organismal fitness. In acute stress conditions, upd induction often promotes beneficial protective mechanisms. For instance, transient activation of the upds in gut epithelial cells following injury or infection stimulates stem cell-mediated tissue regeneration ( Buchon et al., 2009 ; Jiang et al ., 2009 ; Obata et al ., 2018 ; Osman et al ., 2012 ; von Frieling et al ., 2020 ; Zhou et al ., 2013 ). Similarly, injury-induced upd3 from hemocytes supports tissue repair and survival ( Chakrabarti et al ., 2016 ). Additionally, in normal physiology, upd3 production from pericardial cells maintains ECM protein expression essential for cardiac function ( Gera et al ., 2022 ). However, these same signaling pathways become harmful when chronically activated or in pathological contexts. For example, persistent upd activation in the aging intestine leads to epithelial dysplasia and shortened lifespan ( Li et al., 2016 ). Upon high-fat diet consumption hemocyte-derived upd3 disrupts glucose homeostasis and reduces longevity ( Woodcock et al ., 2015 ), while fat body-derived upd2 causes nephrocyte dysfunction ( Zhao et al., 2025 ). Additionally, age-related upd3 upregulation in oenocytes contributes to cardiac dysfunction ( Huang et al ., 2020 ). Perhaps most strikingly, in tumor models, upd3 secretion triggers systemic pathologies including blood-brain barrier compromise and metabolic dysregulation that accelerate mortality ( Ding et al ., 2021 ; Kim et al., 2021a ; Liu et al ., 2025 ). This dual nature—beneficial in physiological contexts but potentially harmful when dysregulated— underscores the importance of investigating upd signaling in specific physiological and pathological conditions to understand its precise roles in stress adaptation. Here, we investigate how upd3 signaling mediates whole-body hypoxia tolerance in Drosophila , revealing an interorgan communication network that coordinates systemic hypoxia adaptation through the interplay of cytokine and classic hypoxia response pathways. RESULTS Hypoxia induces upd3/JAK/STAT signaling We first examined whether hypoxia induces the cytokine/JAK/STAT signaling pathway. To do this, we subjected w 1118 adult flies and larvae to different durations of either hypoxia (1% oxygen) or normoxia (ambient air) and then collected samples for gene expression analysis by qRT-PCR. We found that hypoxia exposure led to a strong upregulation of upd3 mRNA levels in both male and female adult flies ( Figure 1A, B ), an effect that was apparent within 4hrs of hypoxia exposure. To explore whether this upregulation led to functional induction of cytokine signaling we also measured the mRNA levels of well-described STAT target genes as a functional readout of JAK/STAT pathway activation. This analysis revealed strong upregulation of the STAT target gene SOCS36E in males and females with a similar timecourse ( Figure 1C, D ). We also saw that another class of STAT regulated genes, the Turandot genes, TotA, TotC, TotM, were also induced upon hypoxia exposure in adults ( Figure S1A, B ). Previous studies have shown that flies become immobilized and cease feeding during exposure to 1% oxygen. However, nutrient starvation for a 16-hour period failed to induce upd3 mRNA in both male ( Figure S1C ) and female ( Figure S1D ) animals suggesting that cessation of feeding is not responsible for upd3 induction in hypoxia. Finally, we examined whether the hypoxia induction of upd/JAK/STAT signaling also occurred in larvae. We exposed larvae to 2, 4, and 8 hours of normoxia or hypoxia and collected them for gene expression analysis. Similar to our observations in adults, we detected induction of both upd3 and SOCS36E mRNA in hypoxic larvae ( Figure 1E, F ). Together, these results indicate that induction of upd3 cytokine signaling is a robust response to hypoxia exposure in Drosophila . Download figure Open in new tab Figure S1: Starvation does not induce upd3 expression. A-B) w 1118 adult male and female flies were maintained in normoxia or exposed to 8 hours of hypoxia, then STAT-dependent Turandot genes were profiled. TotA, TotC and TotM were induced in both A) male and B) female adults. Data represents mean + SEM, N=4 independent groups of samples (5 animals per group) per experimental condition. Data points represent independent samples. C-D) w 1118 adult male and female flies were maintained in normoxia, exposed to 16 hours of hypoxia or 16 hours starvation. U pd3 expression in whole animals was measured by qRT-PCR. Upon starvation, there is no significant change in upd3 mRNA levels in either C) male or D) female adults. Data represents mean + SEM, N=4 independent groups of samples (5 animals per group) per experimental condition. *p < 0.05, ns not significant, unpaired t -test. Data points represent independent samples. Download figure Open in new tab Figure 1: Hypoxia induces upd3/Jak/STAT signaling in larvae and adults. (A-D) Age-matched flies ( w 1118 ) were maintained in normoxia or hypoxia (1% oxygen), then collected for gene expression analysis. qRT-PCR measurement of upd3 in A) males and B) females following 4, 8, and 16 hours of hypoxia. STAT-target gene SOCS36E measured in C) males and D) females were measured following 4, 8 and 16 hours of hypoxia. Data represents mean + SEM, N=5 independent groups of samples (5 animals per group) per experimental condition. Data points represent independent samples. E, F) qRT-PCR measurements of E) upd3 mRNA and F) SOCS36E mRNA in larvae exposed to 2, 4 and 8 hours of hypoxia (1% oxygen). Data represents mean + SEM, N=3-8 independent groups of animals (10 animals per group) per experimental condition. Data points represent independent samples. Sex-specific requirement for upd3 in hypoxia tolerance We next investigated the functional relevance of increased upd3 signaling in hypoxia tolerance. To test this, we examined survival under hypoxic conditions in a upd3 -null mutant line ( upd3Δ) ( Osman et al ., 2012 ). We exposed age-matched 7-day-old control ( w 1118 ) and upd3 mutant adult flies to an acute bout of hypoxia that resulted in 50-80% survival of control flies. Our survival analysis revealed that female upd3 -null mutants exhibited significantly reduced survival compared to their control counterparts ( Figure 2B ). In contrast, upd3 -null mutant males showed no decrease in hypoxia survival compared to control males and even displayed a small but significant increase in survival ( Figure 2A ). Given that female metabolism is altered by mating status ( Ahmed et al., 2020 ; Hadjieconomou et al., 2020 ; Hudry et al., 2016 ; Reiff et al., 2015 ; Zipper et al., 2020 ), we asked whether mating status affected the requirement for upd3 in hypoxia tolerance. Both mated and virgin female upd3 -null animals showed decreased survival in hypoxia compared to controls ( Figure S2B, C ). Download figure Open in new tab Figure S2: Female gut upd3 knockdown reduces hypoxia survival. Age-matched mated and virgin control ( w 1118 ) and upd3-null ( upd3Δ ) female flies were exposed to hypoxia and survival was measured. The requirement for upd3 in hypoxia survival was not dependent on mating status in female flies – upd3-null ( upd3Δ ) A) mated and B) virgin females both showed reduced survival compared to mated or virgin controls ( w 1118 ). C) Hypoxia survival of control ( Myo1A ts > + ) vs gut upd3 RNAi ( Myo1A ts > upd3-RNAi ) adult female flies. Data represents mean ± SEM, N=4 independent groups of animals (15-25 per group) per experimental condition. *p < 0.05, unpaired t -test. Data points represent individual samples. Download figure Open in new tab Figure 2: upd3 is required for hypoxia tolerance in females but not males. Hypoxia survival measured in control ( w 1118 ) vs upd3-null ( upd3Δ ) A) males and B) females. Data represents mean ± SEM, N≥5 independent groups of animals (15-25 per group) per experimental condition. *p < 0.05, unpaired t -test. Data points represent independent samples. These results suggest a sexually dimorphic requirement for upd3 in mediating hypoxia tolerance. While upd3 is necessary for hypoxia tolerance in females regardless of mating status, it appears dispensable or even detrimental in males. Further studies will be needed to determine if this sex difference occurs through the sex determination pathway, which is emerging as an important mediator of fly physiology. However, for the remainder of this study, we focused on exploring how upd3 mediates hypoxia tolerance in mated females. Intestinal upd3 coordinates systemic hypoxia responses The upds facilitate tissue-to-tissue communication to control adaptive responses to stress. They are expressed in different tissues and can act in an autocrine or paracrine manner. Therefore, we wanted to investigate what key tissue(s) produce upd3 to promote hypoxia tolerance. One key tissue known to produce upd3 in response to stress is the adult midgut. Previous studies have shown how a variety of different stresses including infection, tissue damage and nutrient stress can upregulate intestinal upd3 to mediate both local and systemic adaptive response ( Buchon et al ., 2009 ; Cai et al ., 2021 ; Houtz et al ., 2017 ; Jiang et al ., 2009 ; Nagai et al ., 2023 ; Obata et al ., 2018 ; Takeishi et al., 2013 ; von Frieling et al ., 2020 ; Zhou et al ., 2013 ). When we exposed control ( w 1118 ) females to 16 hours of normoxia or hypoxia and dissected guts for qRT-PCR analysis, we found a strong upregulation of upd3 mRNA levels in hypoxia ( Figure 3A ). We also analyzed flies carrying an upd3 GFP transcriptional reporter ( upd3Gal4, UAS-GFP ) that were exposed to either normoxia or hypoxia. Microscopic visualization of the intestines from these flies showed that hypoxia-exposed animals had stronger GFP expression in their guts compared to normoxia controls, which was especially evident in the R2 region of the intestine ( Figure 3B ). Moreover, this increased GFP expression was mostly seen in the large epithelial enterocytes. To interrogate this finding further, we knocked down upd3 using an enterocyte-specific driver ( mex>upd3-RNAi ) and measured intestinal upd3 mRNA levels using qPCR. We found that enterocyte upd3 knockdown resulted in significant reduction (∼80%) of upd3 mRNA ( Figure 3C ), suggesting that the enterocytes are the main intestinal cell type upregulating upd3 in hypoxia. Furthermore, when we repeated this experiment but now measured whole-body upd3 mRNA levels, we saw that enterocyte upd3 knockdown led to a significant ∼40% decrease in the hypoxia-mediated upregulation of whole-body upd3 levels ( Figure 3D ). These results suggest that, although upd3 is likely upregulated in several tissues, the intestinal enterocytes contribute a large proportion of the systemic upregulation of upd3 in hypoxia-exposed flies. Download figure Open in new tab Figure 3: Gut-derived upd3 promotes hypoxia tolerance. A) qRT-PCR analysis of upd3 mRNA of guts from w 1118 adult females maintained in normoxia or exposed to 16 hours of hypoxia (1% oxygen). RNA was isolated from whole guts. Data represents mean + SEM, N=4 independent groups of samples (5 intestines per group) per experimental condition. Data points represent independent samples. B) Female flies expressing GFP under control of an upd3 promoter ( upd3-gal4, UAS-GFP ) were exposed to hypoxia (1% oxygen) or maintained in normoxia for 16 hours. Whole guts were dissected, stained with Hoechst to visualize nuclei, and mounted for visualization of GFP expression. Representative images of R2 region shown. Scale bar = 50µm. C) qRT-PCR measurement of upd3 mRNA in whole intestines with control ( mex > + ) vs enterocyte upd3 knockdown flies ( mex > upd3-RNAi) in hypoxia. Data represents mean + SEM, N=4 independent groups of samples (5 intestines per group) per experimental condition. *p < 0.05, Student’s t -test following 2-way ANOVA. Data points represent independent samples D) upd3 mRNA also measured in whole-body. Data represents mean + SEM, N=4 independent groups of samples (5 animals per group) per experimental condition. *p upd3-RNAi, Myo1A > upd3-RNAi ) compared to their respective control genotypes ( mex > +, Myo1A > + ). Data represents mean ± SEM, N≥6 independent groups of animals (15-25 per group) per experimental condition. *p + ) and flies with gut-specific upd3 knockdown ( mex>upd3-RNAi ) to hypoxia and measured their survival. We saw that suppressing intestinal upd3 expression significantly reduced fly survival compared to controls ( Figure 3E ). We repeated this experiment using another enterocyte-specific driver, Myo1A-Gal4 , to knock down upd3 and observed similar results with the Myo1A>upd3-RNAi flies showing significantly reduced survival compared to controls ( Myo1A>+ ) ( Figure 3F ). To rule out potential developmental effects of upd3 knockdown, we employed a temperature-sensitive enterocyte driver to induce RNAi knockdown of upd3 specifically during adulthood. These adult-specific upd3 knockdown flies ( Myo1A ts >upd3-RNAi ) also showed reduced survival under hypoxic conditions compared to controls ( Myo1A ts >+ ) ( Figure S2C ). Collectively, these results demonstrate that the gut serves as an important source of hypoxia-induced upd3 expression essential for hypoxia tolerance. Gut-derived upd3 signals to fat and oenocytes to promote hypoxia tolerance Having established the intestine as an important source of expression for upd3 in mediating hypoxia tolerance, we next investigated which tissue(s) gut-derived upd3 might be communicating with to stimulate JAK/STAT signaling and mediate this hypoxia tolerance response. We performed qRT-PCR on tissue from isolated heads, thoraces, abdomens (with guts removed), and ovaries from female w 1118 flies exposed to either normoxia or hypoxia to examine expression of the STAT target gene, SOCS36E . We saw that SOCS36E was upregulated in all tissues in hypoxia-exposed flies suggesting widespread stimulation of JAK/STAT signaling in low oxygen. However, the hypoxia induction of SOCS36E was most pronounced in isolated abdominal tissues ( Figure 4A ). We also saw strong induction of two other STAT targets genes, TotA and TotM, in abdominal tissues of hypoxia-exposed flies ( Figure S3A ). We then examined whether gut-derived upd3 can signal to abdominal tissues, by inducing acute upd3 expression from intestinal enterocytes ( mex ts >UAS-upd3 ) and measuring expression of STAT target genes in isolated abdominal tissues. Compared to controls ( mex ts >+ ), we observed induction of both TotA and TotM mRNA in the abdomens of mex ts >UAS-upd3 ( Figure 4B ) indicating that gut-derived upd3 can stimulate JAK/STAT signaling in abdominal tissues. Download figure Open in new tab Figure S3: NOS regulation in hypoxia A, B) Female flies ( w 1118 ) were exposed to 16 hours of hypoxia and abdomens isolated for gene expression analysis. A) Turandot genes TotA and TotM and B) NOS mRNA are induced in hypoxia. C-E) Intestinal upd3 knockdown ( mex > upd3-RNAi ) and control ( mex > + ) female flies were maintained in normoxia or exposed to 16h hypoxia, then tissues were collected for NOS mRNA gene expression analysis. Intestinal upd3 knockdown did not significantly affect NOS mRNA in the C) heads, D) thorax or E) ovaries in hypoxia. Data represents mean + SEM, N=2-4 independent groups of samples (5-10 tissues per group) per experimental condition. *p < 0.05, ns not significant, Student’s t -test following 2-way ANOVA. Data points represent independent samples. Download figure Open in new tab Figure 4: Gut-derived upd3 controls adipose expression of hypoxia regulators. A) Adult females ( w 1118 ) were maintained in normoxia or exposed to 16 hours of hypoxia. Different tissues including the head, ovary, thorax and abdomen were dissected for SOCS36E mRNA expression analysis. Data represents mean + SEM, N=4 independent groups of samples (5-10 tissues per group) per experimental condition. *p < 0.05, unpaired t -test. Data points represent independent samples. B) qRT-PCR analysis of STAT target genes ( Tot A and Tot M) in the adult female abdominal tissue with intestinal upd3 overexpression ( mex ts > upd3 ) vs control ( mex ts > + ). Data represents mean + SEM, N=4 independent groups of samples (5 abdomens with intestines and ovaries removed per group) per experimental condition. *p < 0.05, ns not significant, Student’s t -test following 2-way ANOVA. Data points represent independent samples. C) Survival measured in animals with RNAi knockdown of STAT92E in the two main abdominal tissue types – oenocytes and fat body – ( desat;r4 > STAT92E-RNAi ) vs control ( desat;r4 > + ). Data represents mean ± SEM, N≥8 independent groups of animals (15-25 per group) per experimental condition. *p upd3-RNAi ) vs control ( mex > + ). N=4 independent groups of samples (5 abdomens with intestines and ovaries removed per group) per experimental condition. *p NOS RNAi ) vs control ( r4 > + ), or F) oenocytes alone ( desat > NOS RNAi ) vs control ( desat > + ). Data represents mean ± SEM, N≥4 independent groups of animals (15-25 per group) per experimental condition. *p < 0.05, unpaired t -test. Data points represent individual samples. Adult abdominal tissue is composed mostly of fat body and oenocytes ( Ghosh et al., 2020 ). These tissues are functionally equivalent to mammalian adipose and liver and play important roles in lipid and sugar storage, mobilization and metabolism, as well as functioning as endocrine tissues ( Arrese and Soulages, 2010 ; Bland, 2022 ; Ghosh et al ., 2020 ; Huang et al., 2022 ; Kuhnlein, 2011 ; Martinez et al., 2020 ; Meschi and Delanoue, 2021 ; Sriskanthadevan-Pirahas et al., 2022 ; Stefana et al., 2017 ; Yamada et al., 2018 ). Through these effects both the fat body and oenocytes have well-established roles in coordinating whole-body physiological responses to changes in environmental stimuli such as food, pathogens and toxins. In particular, previous studies have shown that the fat body is a key target of endocrine upd3 signaling involved in the regulation of systemic physiology and stress responses ( Gera et al ., 2022 ; Liu et al ., 2025 ). We therefore assessed the functional importance of abdominal STAT signaling in hypoxia tolerance. We generated a line carrying two independent gal4 drivers, desat-Gal4 and r4-Gal4 that drive expression specifically in oenocytes and fat body respectively. We used this line to express dsRNA against STAT92E ( desat;r4>STAT92E-RNAi ) simultaneously in both oenocytes and fat body and measured hypoxia survival. We found that oenocyte/fat body-specific STAT92E knockdown significantly reduced survival under hypoxic conditions compared to control animals ( Figure 4C ). Together these results suggest that one way that gut-derived upd3 can promote hypoxia tolerance is through signaling to the fat body and oenocytes. Gut-derived upd3 controls abdominal expression of nitric oxide synthase, a regulator of hypoxia survival Nitric oxide (NO), which is synthesized by the enzyme nitric oxide synthase (Nos), is a conserved mediator of hypoxic responses and in Drosophila has been shown to be required for several aspects of hypoxia adaptation including cell cycle arrest, altered behaviour and survival ( DiGregorio et al., 2001 ; Dijkers and O’Farrell, 2009 ; Teodoro and O’Farrell, 2003 ; Wingrove and O’Farrell, 1999 ). Interestingly, we found that Nos mRNA expression levels were strongly elevated in isolated abdominal tissues from hypoxia-exposed flies suggesting a potential hypoxic role for Nos in these tissues. We therefore examined whether Nos might be a downstream effector of gut-to-oenocyte/fat body upd3 signaling. We knocked down upd3 specifically in intestinal enterocytes ( mex>upd3-RNAi ) and then analyzed Nos expression in abdominal tissues from normoxic versus hypoxic flies. We saw that gut-specific upd3 knockdown significantly reduced the hypoxia-induced increase in abdominal Nos expression ( Figure 4D ). This regulation appeared to be tissue-specific, as we did not observe gut upd3 -dependent regulation of Nos expression in other tissues including the head, thorax, and ovaries ( Figure S3A-C ). To determine whether abdominal Nos was functionally important for hypoxia tolerance, we used RNAi to knock down Nos in either the fat body or oenocytes. In both cases, Nos knockdown significantly reduced survival under hypoxic conditions compared to controls ( Figure 4E, F ). These results demonstrate that gut-derived upd3 promotes hypoxia tolerance by regulating Nos expression specifically in abdominal tissues, identifying Nos as a key downstream effector of the gut-to-fat/oenocyte signaling axis. HIF-1α limits upd3 signaling to promote hypoxia tolerance We next explored how hypoxia regulates upd3 expression. Hypoxia-inducible factor 1 (HIF-1) is one of the best-characterized transcriptional regulators of hypoxia response and in mammalian cells has been shown to be pro-inflammatory in part through expression of cytokines ( Nizet and Johnson, 2009 ; Palazon et al., 2014 ; Palsson-McDermott et al., 2015 ; Tannahill et al., 2013 ). We therefore investigated whether HIF-1α (known as sima in Drosophila ) was required for upd3 induction during hypoxia. We used RNAi to knock down sima ubiquitously using the da-gal4 driver ( da>sima-RNAi ) and compared upd3 mRNA levels under hypoxic conditions to controls ( da>+ ). Interestingly, we found that sima knockdown augmented the hypoxia-induced increase in upd3 mRNA levels ( Figure 5A ) and led to a strong amplification of the hypoxia-induced increased in expression of the STAT target gene, TotM ( Figure 5B ). These results suggest that, rather than being required for upd3 induction, sima is needed to limit upd3/JAK/STAT signaling during hypoxia. This finding aligns with a prevailing theme in immunology: the necessity of fine-tuning cytokine signaling. While effective immune responses rely on rapid induction of cytokine signaling, it is equally important to limit excess cytokine signaling to avoid ‘cytokine-storm’ responses, whereby unchecked cytokine signaling can cause unwanted tissue damage and immunopathology ( Cron et al., 2023 ; Fajgenbaum and June, 2020 ; Jahani et al ., 2020 ; Medzhitov, 2021 ; Meizlish et al., 2021 ; Ye and Medzhitov, 2019 ). Based on our results, we hypothesized that one role of sima during hypoxia might be to limit the potentially deleterious effects of excessive upd3 levels to ensure proper adaptation to hypoxia. This hypothesis made two testable predictions: first, that overexpression of upd3 to create excess cytokine signaling would be detrimental in hypoxia; and second, that if sima’s role is to dampen excessive upd3 signaling, then lowering upd3 levels might partially protect against the lethality seen with sima knockdown. We tested both predictions. Download figure Open in new tab Figure 5: HIF-1 alpha/sima limits excess upd3/Jak/STAT signaling. Control ( da > + ) or sima knockdown ( da > sima-RNAi ) females were maintained in normoxia or exposed to hypoxia (1% oxygen) for 16 hours. Whole flies were then collected for qRT-PCR analysis. Whole body A) upd3 mRNA and B) TotM mRNA were measured. Data represents mean + SEM, N=8 independent groups of samples (5 animals per group) per experimental condition. *p upd3 , -RU486) vs ubiquitous upd3 OE ( da-GS > upd3 , +RU486) adult flies. Data represents mean ± SEM, N=10 independent groups of animals (15-25 per group) per experimental condition. *p +) , upd3Δ heterozygote ( da > upd3Δ /+), sima knockdown ( da > sima-RNAi ) and upd3Δ heterozygote sima knockdown ( da > upd3Δ /+ ;sima-RNAi ) adult females were maintained in normoxia or exposed to hypoxia (1% oxygen) and survival measured. Data represents mean ± SEM, N≥8 independent groups of animals (15-25 per group) per experimental condition. *p < 0.05, unpaired t -test. Data points represent individual samples. To test whether excess upd3 is detrimental in low oxygen, we used the GeneSwitch-Gal4 system to acutely overexpress upd3 ubiquitously in adult female flies. Upd3 -overexpressing flies ( daGS>upd3 , fed RU486) showed significantly reduced hypoxia survival compared to control flies ( daGS>upd3 , fed vehicle control) ( Figure 5C ). We confirmed this result using another ubiquitous inducible driver ( actGS-Gal4 ) and observed the same outcome—excess upd3 reduced hypoxia tolerance ( Figure S4A ) Download figure Open in new tab Figure S4: sima-dependent control of upd3 A) Hypoxia survival of control ( act-GS > upd3 , -RU486) vs upd3 OE ( act-GS > upd3 , +RU486) adult flies. Data represents mean ± SEM, N=12 independent groups of animals (15-25 per group) per experimental condition. *p +) , upd3Δ heterozygote ( da > upd3Δ/+ ), sima knockdown ( da>sima-RNAi ) and upd3Δ heterozygote sima knockdown ( da > upd3Δ/+;sima-RNAi ) adult females were maintained in normoxia or exposed to 16h hypoxia. A) Hyper-induction of upd3 mRNA levels seen in sima knockdown animals is abrogated in an upd3 heterozygote ( upd3Δ/+ ) background. Data represents mean + SEM, N=4 independent groups of samples (5 animals per group) per experimental condition. *p sima-RNAi ) did not affect intestinal upd3 levels compared to controls ( r4 > + ) when animals were fed oxidative stress inducing chemical paraquat. Data represents mean + SEM, N=4 independent groups of samples (5 intestines per group) per experimental condition. *p CatA ) failed to block intestinal induction of upd3 compared to controls ( + > CatA ) in hypoxia. Data represents mean + SEM, N=4 independent groups of samples (5 intestines per group) per experimental condition. *p < 0.05, ns not significant, Student’s t -test following 2-way ANOVA. Data points represent independent samples. We next tested whether reducing upd3 gene dosage could rescue the lethality of sima knockdown flies. To lower upd3 signaling, we carried out experiments in flies heterozygous for upd3 . Using qRT-PCR, we first confirmed that the augmented upd3 levels seen in hypoxic sima knockdown flies were reduced back to control hypoxic levels in upd3 heterozygotes, confirming the effectiveness of reducing gene dosage of upd3 in dampening the excess upd3 expression ( Figure S4B ). We then tested hypoxia survival and found that sima knockdown flies heterozygous for the upd3 deletion ( upd3Δ /+ ; da> sima-RNAi ) showed a small but significant improvement in survival under hypoxic conditions compared to sima knockdown flies with normal upd3 levels ( da>sima-RNAi ) ( Figure 5D ). These results demonstrate that part of the lethality observed in sima -deficient flies is attributable to exaggerated upd3 induction during hypoxia, supporting our hypothesis that sima functions to prevent harmful levels of cytokine signaling during hypoxia. Adipose HIF-1α regulates gut upd3 expression Our experiments on sima focused on whole-body regulation of upd3, so we next turned to how sima might regulate intestinal upd3 production specifically. We repeated the experiment with ubiquitous sima knockdown but measured gut upd3 mRNA levels directly. As with whole-body upd3, we observed augmented upd3 production in the gut under hypoxic conditions ( Figure 6A ), suggesting that sima’s modulation of whole-body upd3 levels may largely reflect augmentation of upd3 in the gut. Download figure Open in new tab Figure 6: Adipose HIF-1 alpha/sima limits intestinal upd3 expression. Adult female flies of control and sima knockdown in A) the whole fly ( da > +, da > sima-RNAi ), B) gut ( mex > +, mex > sima-RNAi ) or C) fat body ( r4 > +, r4 > sima-RNAi ) were maintained in normoxia or hypoxia (1% oxygen) for 16 hours. Whole guts were immediately dissected for qRT-PCR analysis. Data represents mean + SEM, N=4 independent groups of samples (5 intestines per group) per experimental condition. *p < 0.05, ns not significant, Student’s t -test following 2-way ANOVA. Data points represent independent samples. We initially hypothesized that sima in the gut might directly antagonize gut upd3 expression. To test this hypothesis, we generated enterocyte-specific sima knockdown flies and isolated their intestines after exposure to normoxia or hypoxia to measure upd3 mRNA levels. Contrary to our expectation, gut-specific sima knockdown ( mex>sima-RNAi ) did not significantly alter intestinal upd3 mRNA levels compared to controls ( mex>+ ) under hypoxic conditions ( Figure 6C ). This finding suggested that gut sima does not directly regulate gut upd3 expression and that the effect of sima on upd3 is non-autonomous. Previous work has shown that sima activity in the fat body during hypoxia plays an important non-autonomous role in controlling whole-body physiology, with effects thought to rely on sima modulation of fat-dependent endocrine signaling ( Texada et al ., 2019 ). The Drosophila fat body also serves as a central integration hub for signals to and from other tissues. Based on these observations, we examined the fat body as a potential source of sima-dependent regulation of intestinal upd3. We generated fat body-specific sima knockdown flies ( r4>sima-RNAi ), exposed them to hypoxia, and measured gut upd3 mRNA levels. Strikingly, intestines from fat body sima knockdown flies showed significantly greater induction of upd3 under hypoxic conditions compared to control ( r4>+ ) intestines ( Figure 6C ). These results suggest that sima in the fat body acts as a hypoxia sensor that regulates upd3 expression in the gut, implying the existence of a sima-dependent signal mediating this tissue-to-tissue communication We investigated whether reactive oxygen species (ROS) might mediate this interorgan communication. Since ROS are well-established inducers of upd3, we tested whether sima knockdown affects ROS-induced upd3 by exposing fat body-specific sima knockdown flies ( r4>sima-RNAi ) to paraquat, a ROS-generating chemical. We observed no significant difference in intestinal upd3 expression compared to controls ( Figure S4C ). Additionally, overexpressing the antioxidant enzyme Catalase A in the gut ( mex>CatA ) did not affect hypoxia-induced intestinal upd3 levels ( Figure S4D ). These results suggest that the hypoxia- and sima-dependent modulation of upd3 is independent of ROS signaling. DISCUSSION Organisms must coordinate whole-body responses to environmental stresses through inter-organ communication networks. Our results reveal how cytokine signaling mediates such coordination during systemic hypoxia, identifying a gut-to-fat body axis that is essential for organismal survival under low oxygen conditions. Upd3 has been shown to mediate adaptive responses to numerous environmental stresses including nutrient stress, infection, and toxins, and our work extends its role to the regulation of adaptation to low oxygen. We demonstrate that gut-derived upd3 is needed for survival in low oxygen, and our results suggest this occurs in part through signaling to two main tissues in the fly abdomen—the oenocytes and the fat body. Both cell types play important roles in energy metabolism, particularly in coordinating whole-body metabolic and physiological adaptations to changes in environmental conditions through their adipose- and liver-like roles in fat and sugar storage and mobilization, as well as their endocrine functions in sensing nutrient changes and signaling to other tissues ( Arrese and Soulages, 2010 ; Bland, 2022 ; Ghosh et al ., 2020 ; Huang et al ., 2022 ; Kuhnlein, 2011 ; Martinez et al ., 2020 ; Meschi and Delanoue, 2021 ; Sriskanthadevan-Pirahas et al ., 2022 ; Stefana et al ., 2017 ; Yamada et al ., 2018 ). Our work demonstrates that upd3 signaling promotes hypoxia tolerance through regulation of Nos in these target tissues. Nitric oxide functions as a second messenger through activation of cGMP and PKG signaling. Previous studies have shown that NO/cGMP/PKG signaling mediates many of the physiological and behavioral adaptive responses to hypoxia in Drosophila embryos and larvae, including modulating gene expression, tracheogenesis, and the cell cycle ( DiGregorio et al ., 2001 ; Dijkers and O’Farrell, 2009 ; Teodoro and O’Farrell, 2003 ; Wingrove and O’Farrell, 1999 ). Nitric oxide can also mediate post-translational protein modifications through nitrosylation. Interestingly, a recent study in the Drosophila hematopoietic system showed that nitrosylation can enhance the unfolded protein response ( Cho et al., 2024 ), which is a known conserved pathway induced by hypoxia ( Wouters and Koritzinsky, 2008 ). Further studies are needed to explore whether these or other roles of nitric oxide might be important in mediating the hypoxia tolerance effects that we describe here. Our findings support a model in which systemic responses to hypoxia, like other environmental stresses such as starvation and infection, rely on tissue-specific stress sensors and tissue-to-tissue coordination. In Drosophila , previous examples include sima activation in the larval fat body triggering fat-to-brain signals that suppress insulin-like peptide production under oxygen-limited conditions ( Texada et al ., 2019 ), and sima induction in specialized neurons modifying neuroendocrine signaling to stimulate blood cell production ( Cho et al ., 2018 ). Similar principles operate in mammals, where specialized tissues detect oxygen levels and trigger systemic responses—for example, oxygen sensing in keratinocytes of the epidermal layer of the skin through HIF-1α and mitochondrial metabolism triggers EPO production from the kidney to promote red blood cell production in the bone marrow ( Boutin et al., 2008 ; Hamanaka et al., 2016 ), while carotid body sensing triggers neural and endocrine responses that modify respiration and circulation ( Stupnikov and Cardoso, 2017 ). The physiology and anatomy of the fly intestine make it an ideal oxygen sensor. It is extensively innervated by a dense network of trachea that provide oxygen to support its functions and maintain its structure ( Blackie et al., 2024 ; Li et al., 2013 ; Perochon et al., 2021 ; Tamamouna et al., 2021 ). This extensive tracheal network might also enable the gut to sense changes in environmental oxygen and coordinate whole-body responses via its central role as an endocrine organ. Our findings expand the view of the gut as a multipurpose environmental sensor that can detect diverse stimuli including pathogens, nutrients, and oxygen availability to coordinate systemic adaptations. We observed a striking sexual dimorphism in this cytokine hypoxia response—although both sexes show upregulated upd3/JAK/STAT signaling in hypoxia, females require upd3 for hypoxia tolerance while males do not. Notably, sex-specific effects of upd cytokines have been reported in other contexts, including tumor growth and intestinal metabolism ( Hudry et al., 2019 ; Wang et al., 2024 ), suggesting that sexual dimorphism in upd signaling may be a broader phenomenon. The effects we observe are independent of mating status, as both virgin and mated females require upd3. Studies have established that the sex determination pathway in flies can drive male-female differences in many aspects of physiology and metabolism, with whole-body metabolic differences often conferred by the sexual identity of specific cells and tissues that control and establish organismal metabolic state ( Belmonte et al., 2019 ; Hudry et al ., 2019 ; Hudry et al ., 2016 ; Mank and Rideout, 2021 ; Millington et al., 2021a ; Millington et al., 2021b ; Pomatto et al., 2017 ; Regan et al., 2016 ; Regan et al., 2022 ; Rideout et al., 2015 ; Sawala and Gould, 2017 ; Wat et al., 2020 ; Wat et al., 2021 ). Moreover, these male-female differences in physiology confer sex dimorphic sensitivity to environmental stresses such as oxidative stress and starvation ( Pomatto et al ., 2017 ; Wat et al ., 2020 ). Understanding how sex determination pathways might regulate upd3 signaling would be an interesting avenue to explore. An intriguing aspect of our findings is the unexpected role of HIF-1α in restraining cytokine signaling during hypoxia. Mammalian HIF-1α is typically pro-inflammatory through control of interleukin production in mammalian immune cells ( Nizet and Johnson, 2009 ; Palazon et al ., 2014 ; Palsson-McDermott et al ., 2015 ; Tannahill et al ., 2013 ). However, our results suggest a more nuanced model where sima/HIF-1α can serve dual roles: activating essential hypoxia-response genes while simultaneously preventing excessive cytokine responses that could prove deleterious. The concept of restraining cytokine signaling is well-established in immunology, where unchecked cytokine production can lead to cytokine storm and tissue damage. Our work suggests that HIF-1α may function as part of this regulatory network, ensuring that hypoxia-induced cytokine responses remain within beneficial ranges. The tissue-specific nature of this regulation—with fat body sima controlling intestinal cytokine production—indicates that sima operates within a distributed regulatory system that coordinates appropriate stress responses across different organs. The molecular mechanisms underlying this inter-tissue communication remain to be determined but may involve sima-dependent regulation of secreted factors that signal from fat body to gut. Interestingly, sima has previously been shown to antagonize innate immune signaling through other pathways ( Bandarra et al., 2015 ), suggesting that restraining inflammatory responses may be a broader function of HIF-1α depending on the specific stress conditions. Our work also points to what might be an important feature of upd biology: upd3 levels must be carefully balanced to support hypoxia tolerance. Our results show that too little upd3 compromises female survival, while excessive levels are equally detrimental. Extensive work has shown that upds can be beneficial or harmful depending on context, and our work suggests that the strength of the signaling response may be a critical factor in determining whether outcomes are adaptive or pathological. One open question is how hypoxia controls upd3 expression in the gut—both the direct induction by hypoxia and the non-autonomous modulation by fat body sima. We found that the induction is independent of reactive oxygen species (ROS), a well-established pathway for upd3 induction under stress conditions. The induction is also independent of gut sima, contrasting with mammalian systems where HIF-1α increases similar cytokines like IL-6. The upd3 locus can integrate an array of different signaling inputs to induce gene expression in response to enteric pathogen infection ( Houtz et al ., 2017 ), and the hypoxia response may rely on one or more of these pathways. Metabolic changes in enterocytes could also be important. For example, dietary methionine has been shown to control upd expression through modulation of S-adenylmethionine metabolism ( Obata et al ., 2018 ). Interestingly, recent work has shown that in larvae, disruption of glycolysis leads to defects in larval growth and development mediated through upregulation of upd3 ( Rai et al ., 2025 ). Given sima’s critical role in maintaining glycolysis, the elevated gut upd3 we observe when blocking sima in the fat body may arise due to disrupted glycolysis and potentially metabolic signaling from fat body to gut. Our findings may have important implications for understanding systemic hypoxia responses in mammals. The upd3 homolog in mammals is IL-6, a classic stress-induced inflammatory cytokine ( Qing et al., 2020 ). Heightened IL-6 responses are observed in many disorders associated with systemic hypoxia in humans—such as sleep apnea, COPD, and COVID-19—and are thought to mediate inflammatory responses and contribute to pathology ( Ayres, 2020 ; de Lima et al., 2016 ; Nadeem et al., 2013 ). However, our work raises the possibility that IL-6 could also be beneficial in mediating adaptive responses under physiological hypoxia. Just as we find that upd3 is essential for adaptive hypoxia tolerance in flies, IL-6 may serve important adaptive and homeostatic functions in mammals under conditions of systemic hypoxia. METHODS Fly Husbandry Drosophila stocks were maintained at 25°C or 18°C. All stocks were maintained on media comprised of 100g Drosophila Type II agar, 1200g cornmeal, 490mg Torula yeast, 450g sugar, 1240g D-glucose, 160mL acid mixture (propionic and phosphoric acid) in 20L water. Genetic crosses were established by mating virgin females with males. All crosses and progeny were maintained at 25°C. See Table S1 for complete list of lines used. View this table: View inline View popup Download powerpoint Table S1. Drosophila stocks used in this work. Hypoxia Exposure For all hypoxia experiments, Drosophila were placed into an airtight chamber with a constant flow of 1% oxygen (1% oxygen/99% nitrogen) at room temperature. The flow rate was controlled using an Aalborg model P gas flow meter. Adult Hypoxia Survival The duration of hypoxia exposure was tailored to each experiment to produce 50-80% survival in control animals. Males show reduced hypoxia tolerance compared to females. Accordingly, females were exposed for 24-28 hours and males for 16-18 hours (in groups of 15-25 per vial) depending on the specific experiment. The number of flies that recovered from the hypoxia exposure period were then counted. RU486 Treatment Mated females were placed in vials (15-25 per vial) containing standard Drosophila media supplemented with 100µM RU486 in ethanol or equal volume of ethanol alone as vehicle control for 5-7 days. Starvation 7-day-old adult flies were placed in vials (25 per vial) containing either 0.4% agar/PBS (starved) or standard Drosophila media (control). Tissue Dissection and Microscopy Adult female flies were surface-sterilized by rinsing with 75% ethanol in a Petri dish. Flies were then transferred to a watch glass containing ice-cold 1×PBS for dissection under a light microscope, where specific adult tissues were isolated using fine forceps. Dissected tissues were fixed in 4% paraformaldehyde (Electron Microscopy Sciences) in 1×PBS for 20 minutes at room temperature. Tissues were then stained with Hoechst 33342 dye (1:1000 dilution) for 10 minutes, followed by three 15-minute washes in 1×PBS. For mounting, tissues were placed on glass slides with coverslips using Vectashield mounting medium (Vector Laboratories Inc.). Slides were visualized using a Zeiss LSM 880 laser confocal microscope with 10× and 20× objectives and Axiovision software qRT-PCR For whole-body samples, flies were transferred into 1.5mL microtubes in groups of 5 before snap freezing on dry ice. For tissue samples, groups of 5-10 female tissues were dissected in ice-cold 1xPBS and tissues immediately transferred to 1.5mL microtubes containing 500mL TRIzol reagent (Invitrogen) before snap freezing on dry ice. Total RNA was extracted from either whole flies, whole larvae, or isolated adult tissues according to manufacturer’s instructions (Invitrogen; 15596-018). RNA samples were DNase treated following manufacturer’s instructions (Ambion; 2238 G). Reverse transcription was achieved using SuperScript III (Invitrogen; 18080044). The generated cDNA was used as a template for qRT-PCR reactions (QuantStudio 6 RT-PCR system, Applied Biosystems) using the primer pairs defined in Table S2 and SYBR Green reagents. qRT-PCR amplification protocol followed a protocol for standard curve, standard ramp speed, and SYBR Green reagents. Data analysis for qRT-PCR was completed using the comparative C T method (2 -ΔΔCT ). PCR data were normalized to reference genes whose expression levels were unaffected by the experimental conditions. View this table: View inline View popup Download powerpoint Table S2. Primers used for qRT-PCR. All primers listed in 5’-3’ direction. Reference genes used in this study are indicated by an asterisk (*). Statistics For all experiments, error bars represent Standard Error of the Mean (SEM), and p-values are the result of unpaired t -test or two-way Analysis of Variance (ANOVA) followed by Student’s t -test using GraphPad Prism (v.9). p<0.05 was considered significantly significant and indicated by an asterisk (*). ACKKNOWLEDGEMENTS We thank Bruce Edgar, Erika Bach, and Bruno Lemaitre for the gift of fly stocks. Stocks obtained from the VDRC, the NIG-Fly Stock Centre, Kyoto, Japan, and the Bloomington Drosophila Stock Center (NIH P40OD018537) were used in this study. This work was supported by CIHR Project Grants (PJT-173517, PJT-195892) and NSERC DG grants to S.S.G. Funder Information Declared CIHR , PJT-173517 , PJT- 195892 NSERC REFERENCES ↵ Agaisse , H. , and Perrimon , N . ( 2004 ). The roles of JAK/STAT signaling in Drosophila immune responses . Immunol Rev 198 , 72 – 82 . doi: 10.1111/j.0105-2896.2004.0133.x OpenUrl CrossRef PubMed Web of Science ↵ Ahmed , S.M.H. , Maldera , J.A. , Krunic , D. , Paiva-Silva , G.O. , Penalva , C. , Teleman , A.A. , and Edgar , B.A . ( 2020 ). Fitness trade-offs incurred by ovary-to-gut steroid signalling in Drosophila . Nature 584 , 415 – 419 . doi: 10.1038/s41586-020-2462-y OpenUrl CrossRef PubMed ↵ Alvarez-Ochoa , E. , Froldi , F. , and Cheng , L.Y . ( 2021 ). Interorgan communication in development and cancer . Wiley Interdiscip Rev Dev Biol 10 , e394 . doi: 10.1002/wdev.394 OpenUrl CrossRef PubMed ↵ Arrese , E.L. , and Soulages , J.L . ( 2010 ). Insect fat body: energy, metabolism, and regulation . Annu Rev Entomol 55 , 207 – 225 . doi: 10.1146/annurev-ento-112408-085356 OpenUrl CrossRef PubMed Web of Science ↵ Ayres , J.S . ( 2020 ). A metabolic handbook for the COVID-19 pandemic . Nat Metab 2 , 572 – 585 . doi: 10.1038/s42255-020-0237-2 OpenUrl CrossRef PubMed ↵ Baik , A.H. , and Jain , I.H . ( 2020 ). Turning the Oxygen Dial: Balancing the Highs and Lows . Trends Cell Biol 30 , 516 – 536 . doi: 10.1016/j.tcb.2020.04.005 OpenUrl CrossRef PubMed ↵ Bandarra , D. , Biddlestone , J. , Mudie , S. , Muller , H.A. , and Rocha , S . ( 2015 ). HIF-1alpha restricts NF-kappaB-dependent gene expression to control innate immunity signals . Dis Model Mech 8 , 169 – 181 . doi: 10.1242/dmm.017285 OpenUrl Abstract / FREE Full Text ↵ Belmonte , R.L. , Corbally , M.K. , Duneau , D.F. , and Regan , J.C . ( 2019 ). Sexual Dimorphisms in Innate Immunity and Responses to Infection in Drosophila melanogaster . Front Immunol 10 , 3075 . doi: 10.3389/fimmu.2019.03075 OpenUrl CrossRef PubMed ↵ Bickler , P.E. , and Buck , L.T . ( 2007 ). Hypoxia tolerance in reptiles, amphibians, and fishes: life with variable oxygen availability . Annu Rev Physiol 69 , 145 – 170 . doi: 10.1146/annurev.physiol.69.031905.162529 OpenUrl CrossRef PubMed Web of Science ↵ Blackie , L. , Gaspar , P. , Mosleh , S. , Lushchak , O. , Kong , L. , Jin , Y. , Zielinska , A.P. , Cao , B. , Mineo , A. , Silva , B. , et al. ( 2024 ). The sex of organ geometry . Nature 630 , 392 – 400 . doi: 10.1038/s41586-024-07463-4 OpenUrl CrossRef PubMed ↵ Bland , M.L . ( 2022 ). Regulating metabolism to shape immune function: Lessons from Drosophila . Semin Cell Dev Biol . doi: 10.1016/j.semcdb.2022.04.002 OpenUrl CrossRef ↵ Boulan , L. , Milan , M. , and Leopold , P . ( 2015 ). The Systemic Control of Growth . Cold Spring Harb Perspect Biol 7 . doi: 10.1101/cshperspect.a019117 OpenUrl Abstract / FREE Full Text ↵ Boutin , A.T. , Weidemann , A. , Fu , Z. , Mesropian , L. , Gradin , K. , Jamora , C. , Wiesener , M. , Eckardt , K.U. , Koch , C.J. , Ellies , L.G. , et al. ( 2008 ). Epidermal sensing of oxygen is essential for systemic hypoxic response . Cell 133 , 223 – 234 . doi: 10.1016/j.cell.2008.02.038 OpenUrl CrossRef PubMed Web of Science ↵ Brent , A.E. , and Rajan , A . ( 2020 ). Insulin and Leptin/Upd2 Exert Opposing Influences on Synapse Number in Fat-Sensing Neurons . Cell Metab 32 , 786 – 800 e787. doi: 10.1016/j.cmet.2020.08.017 OpenUrl CrossRef PubMed ↵ Buchon , N. , Broderick , N.A. , Poidevin , M. , Pradervand , S. , and Lemaitre , B . ( 2009 ). Drosophila intestinal response to bacterial infection: activation of host defense and stem cell proliferation . Cell Host Microbe 5 , 200 – 211 . doi: 10.1016/j.chom.2009.01.003 OpenUrl CrossRef PubMed Web of Science ↵ Cai , X.T. , Li , H. , Borch Jensen , M. , Maksoud , E. , Borneo , J. , Liang , Y. , Quake , S.R. , Luo , L. , Haghighi , P. , and Jasper , H . ( 2021 ). Gut cytokines modulate olfaction through metabolic reprogramming of glia . Nature 596 , 97 – 102 . doi: 10.1038/s41586-021-03756-0 OpenUrl CrossRef PubMed ↵ Callier , V. , Hand , S.C. , Campbell , J.B. , Biddulph , T. , and Harrison , J.F . ( 2015 ). Developmental changes in hypoxic exposure and responses to anoxia in Drosophila melanogaster . J Exp Biol 218 , 2927 – 2934 . doi: 10.1242/jeb.125849 OpenUrl Abstract / FREE Full Text ↵ Callier , V. , Shingleton , A.W. , Brent , C.S. , Ghosh , S.M. , Kim , J. , and Harrison , J.F . ( 2013 ). The role of reduced oxygen in the developmental physiology of growth and metamorphosis initiation in Drosophila melanogaster . J Exp Biol 216 , 4334 – 4340 . doi: 10.1242/jeb.093120 OpenUrl Abstract / FREE Full Text ↵ Centanin , L. , Dekanty , A. , Romero , N. , Irisarri , M. , Gorr , T.A. , and Wappner , P . ( 2008 ). Cell autonomy of HIF effects in Drosophila: tracheal cells sense hypoxia and induce terminal branch sprouting . Dev Cell 14 , 547 – 558 . doi: 10.1016/j.devcel.2008.01.020 OpenUrl CrossRef PubMed Web of Science ↵ Centanin , L. , Ratcliffe , P.J. , and Wappner , P . ( 2005 ). Reversion of lethality and growth defects in Fatiga oxygen-sensor mutant flies by loss of hypoxia-inducible factor-alpha/Sima . EMBO Rep 6 , 1070 – 1075 . doi: 10.1038/sj.embor.7400528 OpenUrl Abstract / FREE Full Text ↵ Chakrabarti , S. , Dudzic , J.P. , Li , X. , Collas , E.J. , Boquete , J.P. , and Lemaitre , B . ( 2016 ). Remote Control of Intestinal Stem Cell Activity by Haemocytes in Drosophila . PLoS Genet 12 , e1006089 . doi: 10.1371/journal.pgen.1006089 OpenUrl CrossRef PubMed ↵ Cho , B. , Shin , M. , Chang , E. , Son , S. , Shin , I. , and Shim , J . ( 2024 ). S-nitrosylation-triggered unfolded protein response maintains hematopoietic progenitors in Drosophila . Dev Cell 59 , 1075 – 1090 e1076. doi: 10.1016/j.devcel.2024.02.013 OpenUrl CrossRef PubMed ↵ Cho , B. , Spratford , C.M. , Yoon , S. , Cha , N. , Banerjee , U. , and Shim , J . ( 2018 ). Systemic control of immune cell development by integrated carbon dioxide and hypoxia chemosensation in Drosophila . Nat Commun 9 , 2679 . doi: 10.1038/s41467-018-04990-3 OpenUrl CrossRef PubMed ↵ Cron , R.Q. , Goyal , G. , and Chatham , W.W . ( 2023 ). Cytokine Storm Syndrome . Annu Rev Med 74 , 321 – 337 . doi: 10.1146/annurev-med-042921-112837 OpenUrl CrossRef PubMed ↵ de Lima , F.F. , Mazzotti , D.R. , Tufik , S. , and Bittencourt , L. ( 2016 ). The role inflammatory response genes in obstructive sleep apnea syndrome: a review . Sleep Breath 20 , 331 – 338 . doi: 10.1007/s11325-015-1226-7 OpenUrl CrossRef PubMed ↵ DiGregorio , P.J. , Ubersax , J.A. , and O’Farrell , P.H . ( 2001 ). Hypoxia and nitric oxide induce a rapid, reversible cell cycle arrest of the Drosophila syncytial divisions . J Biol Chem 276 , 1930 – 1937 . doi: 10.1074/jbc.M003911200 OpenUrl Abstract / FREE Full Text ↵ Dijkers , P.F. , and O’Farrell , P.H . ( 2009 ). Dissection of a hypoxia-induced, nitric oxide-mediated signaling cascade . Mol Biol Cell 20 , 4083 – 4090 . doi: 10.1091/mbc.E09-05-0362 OpenUrl Abstract / FREE Full Text ↵ Ding , G. , Xiang , X. , Hu , Y. , Xiao , G. , Chen , Y. , Binari , R. , Comjean , A. , Li , J. , Rushworth , E. , Fu , Z. , et al. ( 2021 ). Coordination of tumor growth and host wasting by tumor-derived Upd3 . Cell Rep 36 , 109553 . doi: 10.1016/j.celrep.2021.109553 OpenUrl CrossRef PubMed ↵ Droujinine , I.A. , and Perrimon , N . ( 2016 ). Interorgan Communication Pathways in Physiology: Focus on Drosophila . Annu Rev Genet 50 , 539 – 570 . doi: 10.1146/annurev-genet-121415-122024 OpenUrl CrossRef PubMed ↵ Dunwoodie , S.L . ( 2009 ). The role of hypoxia in development of the Mammalian embryo . Dev Cell 17 , 755 – 773 . doi: 10.1016/j.devcel.2009.11.008 OpenUrl CrossRef PubMed Web of Science ↵ Fajgenbaum , D.C. , and June , C.H . ( 2020 ). Cytokine Storm . N Engl J Med 383 , 2255 – 2273 . doi: 10.1056/NEJMra2026131 OpenUrl CrossRef PubMed ↵ Farzin , M. , Albert , T. , Pierce , N. , VandenBrooks , J.M. , Dodge , T. , and Harrison , J.F . ( 2014 ). Acute and chronic effects of atmospheric oxygen on the feeding behavior of Drosophila melanogaster larvae . J Insect Physiol 68 , 23 – 29 . doi: 10.1016/j.jinsphys.2014.06.017 OpenUrl CrossRef PubMed ↵ Gera , J. , Budakoti , P. , Suhag , M. , Mandal , L. , and Mandal , S . ( 2022 ). Physiological ROS controls Upd3-dependent modeling of ECM to support cardiac function in Drosophila . Sci Adv 8 , eabj4991. doi: 10.1126/sciadv.abj4991 OpenUrl CrossRef PubMed ↵ Ghosh , A.C. , Tattikota , S.G. , Liu , Y. , Comjean , A. , Hu , Y. , Barrera , V. , Ho Sui , S.J. , and Perrimon , N . ( 2020 ). Drosophila PDGF/VEGF signaling from muscles to hepatocyte-like cells protects against obesity . eLife 9 . doi: 10.7554/eLife.56969 OpenUrl CrossRef PubMed ↵ Gorr , T.A. , Gassmann , M. , and Wappner , P . ( 2006 ). Sensing and responding to hypoxia via HIF in model invertebrates . J Insect Physiol 52 , 349 – 364 . doi: 10.1016/j.jinsphys.2006.01.002 OpenUrl CrossRef PubMed Web of Science ↵ Hadjieconomou , D. , King , G. , Gaspar , P. , Mineo , A. , Blackie , L. , Ameku , T. , Studd , C. , de Mendoza , A. , Diao , F. , White , B.H. , et al. ( 2020 ). Enteric neurons increase maternal food intake during reproduction . Nature 587 , 455 – 459 . doi: 10.1038/s41586-020-2866-8 OpenUrl CrossRef PubMed ↵ Hamanaka , R.B. , Weinberg , S.E. , Reczek , C.R. , and Chandel , N.S . ( 2016 ). The Mitochondrial Respiratory Chain Is Required for Organismal Adaptation to Hypoxia . Cell Rep 15 , 451 – 459 . doi: 10.1016/j.celrep.2016.03.044 OpenUrl CrossRef PubMed ↵ Harrison , J.F. , Greenlee , K.J. , and Verberk , W . ( 2018 ). Functional Hypoxia in Insects: Definition, Assessment, and Consequences for Physiology, Ecology, and Evolution . Annu Rev Entomol 63 , 303 – 325 . doi: 10.1146/annurev-ento-020117-043145 OpenUrl CrossRef PubMed ↵ Harrison , J.F. , and Haddad , G.G . ( 2011 ). Effects of oxygen on growth and size: synthesis of molecular, organismal, and evolutionary studies with Drosophila melanogaster . Annu Rev Physiol 73 , 95 – 113 . doi: 10.1146/annurev-physiol-012110-142155 OpenUrl CrossRef PubMed ↵ Hersperger , F. , Meyring , T. , Weber , P. , Chhatbar , C. , Monaco , G. , Dionne , M.S. , Paeschke , K. , Prinz , M. , Gross , O. , Classen , A.K. , and Kierdorf , K . ( 2024 ). DNA damage signaling in Drosophila macrophages modulates systemic cytokine levels in response to oxidative stress . eLife 12 . doi: 10.7554/eLife.86700 OpenUrl CrossRef ↵ Holdsworth , M.J. , and Gibbs , D.J . ( 2020 ). Comparative Biology of Oxygen Sensing in Plants and Animals . Curr Biol 30 , R362 – R369 . doi: 10.1016/j.cub.2020.03.021 OpenUrl CrossRef ↵ Houtz , P. , Bonfini , A. , Liu , X. , Revah , J. , Guillou , A. , Poidevin , M. , Hens , K. , Huang , H.Y. , Deplancke , B. , Tsai , Y.C. , and Buchon , N . ( 2017 ). Hippo, TGF-beta, and Src-MAPK pathways regulate transcription of the upd3 cytokine in Drosophila enterocytes upon bacterial infection . PLoS Genet 13 , e1007091 . doi: 10.1371/journal.pgen.1007091 OpenUrl CrossRef PubMed ↵ Huang , K. , Liu , Y. , and Perrimon , N . ( 2022 ). Roles of Insect Oenocytes in Physiology and Their Relevance to Human Metabolic Diseases . Front Insect Sci 2 , 859847 . doi: 10.3389/finsc.2022.859847 OpenUrl CrossRef ↵ Huang , K. , Miao , T. , Chang , K. , Kim , J. , Kang , P. , Jiang , Q. , Simmonds , A.J. , Di Cara , F. , and Bai , H. ( 2020 ). Impaired peroxisomal import in Drosophila oenocytes causes cardiac dysfunction by inducing upd3 as a peroxikine . Nat Commun 11 , 2943 . doi: 10.1038/s41467-020-16781-w OpenUrl CrossRef PubMed ↵ Hudry , B. , de Goeij , E. , Mineo , A. , Gaspar , P. , Hadjieconomou , D. , Studd , C. , Mokochinski , J.B. , Kramer , H.B. , Placais , P.Y. , Preat , T. , and Miguel-Aliaga , I. ( 2019 ). Sex Differences in Intestinal Carbohydrate Metabolism Promote Food Intake and Sperm Maturation . Cell 178 , 901 – 918 e916. doi: 10.1016/j.cell.2019.07.029 OpenUrl CrossRef PubMed ↵ Hudry , B. , Khadayate , S. , and Miguel-Aliaga , I . ( 2016 ). The sexual identity of adult intestinal stem cells controls organ size and plasticity . Nature 530 , 344 – 348 . doi: 10.1038/nature16953 OpenUrl CrossRef PubMed ↵ Ingaramo , M.C. , Sanchez , J.A. , Perrimon , N. , and Dekanty , A . ( 2020 ). Fat Body p53 Regulates Systemic Insulin Signaling and Autophagy under Nutrient Stress via Drosophila Upd2 Repression . Cell Rep 33 , 108321 . doi: 10.1016/j.celrep.2020.108321 OpenUrl CrossRef ↵ Jahani , M. , Dokaneheifard , S. , and Mansouri , K . ( 2020 ). Hypoxia: A key feature of COVID-19 launching activation of HIF-1 and cytokine storm . J Inflamm (Lond ) 17 , 33 . doi: 10.1186/s12950-020-00263-3 OpenUrl CrossRef PubMed ↵ Jiang , H. , Patel , P.H. , Kohlmaier , A. , Grenley , M.O. , McEwen , D.G. , and Edgar , B.A . ( 2009 ). Cytokine/Jak/Stat signaling mediates regeneration and homeostasis in the Drosophila midgut . Cell 137 , 1343 – 1355 . doi: 10.1016/j.cell.2009.05.014 OpenUrl CrossRef PubMed Web of Science ↵ Kannangara , J.R. , Mirth , C.K. , and Warr , C.G . ( 2021 ). Regulation of ecdysone production in Drosophila by neuropeptides and peptide hormones . Open Biol 11 , 200373 . doi: 10.1098/rsob.200373 OpenUrl CrossRef PubMed ↵ Kierdorf , K. , Hersperger , F. , Sharrock , J. , Vincent , C.M. , Ustaoglu , P. , Dou , J. , Gyoergy , A. , Gross , O. , Siekhaus , D.E. , and Dionne , M.S . ( 2020 ). Muscle function and homeostasis require cytokine inhibition of AKT activity in Drosophila . eLife 9 . doi: 10.7554/eLife.51595 OpenUrl CrossRef ↵ Kim , J. , Chuang , H.C. , Wolf , N.K. , Nicolai , C.J. , Raulet , D.H. , Saijo , K. , and Bilder , D . ( 2021a ). Tumor-induced disruption of the blood-brain barrier promotes host death . Dev Cell 56 , 2712 – 2721 e2714. doi: 10.1016/j.devcel.2021.08.010 OpenUrl CrossRef PubMed ↵ Kim , S.K. , Tsao , D.D. , Suh , G.S.B. , and Miguel-Aliaga , I . ( 2021b ). Discovering signaling mechanisms governing metabolism and metabolic diseases with Drosophila . Cell Metab . doi: 10.1016/j.cmet.2021.05.018 OpenUrl CrossRef PubMed ↵ Koyama , T. , Texada , M.J. , Halberg , K.A. , and Rewitz , K . ( 2020 ). Metabolism and growth adaptation to environmental conditions in Drosophila . Cell Mol Life Sci 77 , 4523 – 4551 . doi: 10.1007/s00018-020-03547-2 OpenUrl CrossRef PubMed ↵ Kuhnlein , R.P . ( 2011 ). The contribution of the Drosophila model to lipid droplet research . Prog Lipid Res 50 , 348 – 356 . doi: 10.1016/j.plipres.2011.04.001 OpenUrl CrossRef PubMed Web of Science ↵ Lavista-Llanos , S. , Centanin , L. , Irisarri , M. , Russo , D.M. , Gleadle , J.M. , Bocca , S.N. , Muzzopappa , M. , Ratcliffe , P.J. , and Wappner , P . ( 2002 ). Control of the hypoxic response in Drosophila melanogaster by the basic helix-loop-helix PAS protein similar . Mol Cell Biol 22 , 6842 – 6853 . OpenUrl Abstract / FREE Full Text ↵ Leopold , P. , and Perrimon , N . ( 2007 ). Drosophila and the genetics of the internal milieu . Nature 450 , 186 – 188 . doi: 10.1038/nature06286 OpenUrl CrossRef PubMed Web of Science ↵ Li , H. , Qi , Y. , and Jasper , H . ( 2016 ). Preventing Age-Related Decline of Gut Compartmentalization Limits Microbiota Dysbiosis and Extends Lifespan . Cell Host Microbe 19 , 240 – 253 . doi: 10.1016/j.chom.2016.01.008 OpenUrl CrossRef PubMed ↵ Li , Z. , Zhang , Y. , Han , L. , Shi , L. , and Lin , X . ( 2013 ). Trachea-derived dpp controls adult midgut homeostasis in Drosophila . Dev Cell 24 , 133 – 143 . doi: 10.1016/j.devcel.2012.12.010 OpenUrl CrossRef PubMed ↵ Liu , Y. , Dantas , E. , Ferrer , M. , Miao , T. , Qadiri , M. , Liu , Y. , Comjean , A. , Davidson , E.E. , Perrier , T. , Ahmed , T. , et al. ( 2025 ). Hepatic gluconeogenesis and PDK3 upregulation drive cancer cachexia in flies and mice . Nat Metab 7 , 823 – 841 . doi: 10.1038/s42255-025-01265-2 OpenUrl CrossRef PubMed ↵ Liu , Z. , Zhang , H. , Lemaitre , B. , and Li , X . ( 2024 ). Duox activation in Drosophila Malpighian tubules stimulates intestinal epithelial renewal through a countercurrent flow . Cell Rep 43 , 114109 . doi: 10.1016/j.celrep.2024.114109 OpenUrl CrossRef PubMed ↵ Malita , A. , and Rewitz , K . ( 2021 ). Interorgan communication in the control of metamorphosis . Curr Opin Insect Sci 43 , 54 – 62 . doi: 10.1016/j.cois.2020.10.005 OpenUrl CrossRef PubMed ↵ Mank , J.E. , and Rideout , E.J . ( 2021 ). Developmental mechanisms of sex differences: from cells to organisms . Development 148 . doi: 10.1242/dev.199750 OpenUrl CrossRef ↵ Markow , T.A . ( 2015 ). The secret lives of Drosophila flies . eLife 4 . doi: 10.7554/eLife.06793 OpenUrl CrossRef PubMed ↵ Martinez , B.A. , Hoyle , R.G. , Yeudall , S. , Granade , M.E. , Harris , T.E. , Castle , J.D. , Leitinger , N. , and Bland , M.L . ( 2020 ). Innate immune signaling in Drosophila shifts anabolic lipid metabolism from triglyceride storage to phospholipid synthesis to support immune function . PLoS Genet 16 , e1009192 . doi: 10.1371/journal.pgen.1009192 OpenUrl CrossRef ↵ May , A.M. , and Mehra , R . ( 2014 ). Obstructive sleep apnea: role of intermittent hypoxia and inflammation . Semin Respir Crit Care Med 35 , 531 – 544 . doi: 10.1055/s-0034-1390023 OpenUrl CrossRef PubMed ↵ McKeown , S.R . ( 2014 ). Defining normoxia, physoxia and hypoxia in tumours-implications for treatment response . The British journal of radiology 87 , 20130676 . doi: 10.1259/bjr.20130676 OpenUrl Abstract / FREE Full Text ↵ Medina , A. , Bellec , K. , Polcownuk , S. , and Cordero , J.B . ( 2022 ). Investigating local and systemic intestinal signalling in health and disease with Drosophila . Dis Model Mech 15 . doi: 10.1242/dmm.049332 OpenUrl CrossRef PubMed ↵ Medzhitov , R . ( 2021 ). The spectrum of inflammatory responses . Science 374 , 1070 – 1075 . doi: 10.1126/science.abi5200 OpenUrl CrossRef PubMed ↵ Meizlish , M.L. , Franklin , R.A. , Zhou , X. , and Medzhitov , R . ( 2021 ). Tissue Homeostasis and Inflammation . Annu Rev Immunol 39 , 557 – 581 . doi: 10.1146/annurev-immunol-061020-053734 OpenUrl CrossRef PubMed ↵ Meschi , E. , and Delanoue , R . ( 2021 ). Adipokine and fat body in flies: Connecting organs . Mol Cell Endocrinol 533 , 111339 . doi: 10.1016/j.mce.2021.111339 OpenUrl CrossRef PubMed ↵ Midha , A.D. , Zhou , Y. , Queliconi , B.B. , Barrios , A.M. , Haribowo , A.G. , Chew , B.T.L. , Fong , C.O.Y. , Blecha , J.E. , VanBrocklin , H. , Seo , Y. , and Jain , I.H . ( 2023 ). Organ-specific fuel rewiring in acute and chronic hypoxia redistributes glucose and fatty acid metabolism . Cell Metab 35 , 504 – 516 e505. doi: 10.1016/j.cmet.2023.02.007 OpenUrl CrossRef PubMed ↵ Millington , J.W. , Brownrigg , G.P. , Basner-Collins , P.J. , Sun , Z. , and Rideout , E.J . ( 2021a ). Genetic manipulation of insulin/insulin-like growth factor signaling pathway activity has sex-biased effects on Drosophila body size . G3 (Bethesda) 11 . doi: 10.1093/g3journal/jkaa067 OpenUrl CrossRef ↵ Millington , J.W. , Brownrigg , G.P. , Chao , C. , Sun , Z. , Basner-Collins , P.J. , Wat , L.W. , Hudry , B. , Miguel-Aliaga , I. , and Rideout , E.J . ( 2021b ). Female-biased upregulation of insulin pathway activity mediates the sex difference in Drosophila body size plasticity . eLife 10 . doi: 10.7554/eLife.58341 OpenUrl CrossRef ↵ Nadeem , R. , Molnar , J. , Madbouly , E.M. , Nida , M. , Aggarwal , S. , Sajid , H. , Naseem , J. , and Loomba , R . ( 2013 ). Serum inflammatory markers in obstructive sleep apnea: a meta-analysis . J Clin Sleep Med 9 , 1003 – 1012 . doi: 10.5664/jcsm.3070 OpenUrl CrossRef PubMed ↵ Nagai , H. , Nagai , L.A.E. , Tasaki , S. , Nakato , R. , Umetsu , D. , Kuranaga , E. , Miura , M. , and Nakajima , Y . ( 2023 ). Nutrient-driven dedifferentiation of enteroendocrine cells promotes adaptive intestinal growth in Drosophila . Dev Cell 58 , 1764 – 1781 e1710. doi: 10.1016/j.devcel.2023.08.022 OpenUrl CrossRef PubMed ↵ Nakazawa , M.S. , Keith , B. , and Simon , M.C . ( 2016 ). Oxygen availability and metabolic adaptations . Nat Rev Cancer 16 , 663 – 673 . doi: 10.1038/nrc.2016.84 OpenUrl CrossRef PubMed ↵ Nizet , V. , and Johnson , R.S . ( 2009 ). Interdependence of hypoxic and innate immune responses . Nat Rev Immunol 9 , 609 – 617 . doi: 10.1038/nri2607 OpenUrl CrossRef PubMed Web of Science ↵ Obata , F. , Tsuda-Sakurai , K. , Yamazaki , T. , Nishio , R. , Nishimura , K. , Kimura , M. , Funakoshi , M. , and Miura , M . ( 2018 ). Nutritional Control of Stem Cell Division through S-Adenosylmethionine in Drosophila Intestine . Dev Cell 44 , 741 – 751 e743. doi: 10.1016/j.devcel.2018.02.017 OpenUrl CrossRef PubMed ↵ Okamoto , N. , and Watanabe , A . ( 2022 ). Interorgan communication through peripherally derived peptide hormones in Drosophila . Fly (Austin ) 16 , 152 – 176 . doi: 10.1080/19336934.2022.2061834 OpenUrl CrossRef PubMed ↵ Osman , D. , Buchon , N. , Chakrabarti , S. , Huang , Y.T. , Su , W.C. , Poidevin , M. , Tsai , Y.C. , and Lemaitre , B . ( 2012 ). Autocrine and paracrine unpaired signaling regulate intestinal stem cell maintenance and division . J Cell Sci 125 , 5944 – 5949 . doi: 10.1242/jcs.113100 OpenUrl Abstract / FREE Full Text ↵ Owusu-Ansah , E. , and Perrimon , N . ( 2015 ). Stress Signaling Between Organs in Metazoa . Annu Rev Cell Dev Biol . doi: 10.1146/annurev-cellbio-100814-125523 OpenUrl CrossRef PubMed ↵ Palazon , A. , Goldrath , A.W. , Nizet , V. , and Johnson , R.S . ( 2014 ). HIF transcription factors, inflammation, and immunity . Immunity 41 , 518 – 528 . doi: 10.1016/j.immuni.2014.09.008 OpenUrl CrossRef PubMed Web of Science ↵ Palsson-McDermott , E.M. , Curtis , A.M. , Goel , G. , Lauterbach , M.A. , Sheedy , F.J. , Gleeson , L.E. , van den Bosch, M.W., Quinn, S.R., Domingo-Fernandez, R., Johnston, D.G., et al. ( 2015 ). Pyruvate kinase M2 regulates Hif-1alpha activity and IL-1beta induction and is a critical determinant of the warburg effect in LPS-activated macrophages . Cell Metab 21 , 65 – 80 . doi: 10.1016/j.cmet.2014.12.005 OpenUrl CrossRef PubMed ↵ Perochon , J. , Yu , Y. , Aughey , G.N. , Medina , A.B. , Southall , T.D. , and Cordero , J.B . ( 2021 ). Dynamic adult tracheal plasticity drives stem cell adaptation to changes in intestinal homeostasis in Drosophila . Nat Cell Biol 23 , 485 – 496 . doi: 10.1038/s41556-021-00676-z OpenUrl CrossRef PubMed ↵ Pomatto , L.C.D. , Carney , C. , Shen , B. , Wong , S. , Halaszynski , K. , Salomon , M.P. , Davies , K.J.A. , and Tower , J . ( 2017 ). The Mitochondrial Lon Protease Is Required for Age-Specific and Sex-Specific Adaptation to Oxidative Stress . Curr Biol 27 , 1 – 15 . doi: 10.1016/j.cub.2016.10.044 OpenUrl CrossRef PubMed ↵ Qing , H. , Desrouleaux , R. , Israni-Winger , K. , Mineur , Y.S. , Fogelman , N. , Zhang , C. , Rashed , S. , Palm , N.W. , Sinha , R. , Picciotto , M.R. , et al. ( 2020 ). Origin and Function of Stress-Induced IL-6 in Murine Models . Cell 182 , 372 – 387 e314. doi: 10.1016/j.cell.2020.05.054 OpenUrl CrossRef PubMed ↵ Rai , M. , Li , H. , Policastro , R.A. , Pepin , R. , Zentner , G.E. , Nemkov , T. , D’Alessandro , A. , and Tennessen , J.M . ( 2025 ). Glycolytic disruption restricts Drosophila melanogaster larval growth via the cytokine Upd3 . PLoS Genet 21 , e1011690 . doi: 10.1371/journal.pgen.1011690 OpenUrl CrossRef PubMed ↵ Rajan , A. , Housden , B.E. , Wirtz-Peitz , F. , Holderbaum , L. , and Perrimon , N . ( 2017 ). A Mechanism Coupling Systemic Energy Sensing to Adipokine Secretion . Dev Cell 43 , 83 – 98 e86. doi: 10.1016/j.devcel.2017.09.007 OpenUrl CrossRef PubMed ↵ Rajan , A. , and Perrimon , N . ( 2011 ). Drosophila as a model for interorgan communication: lessons from studies on energy homeostasis . Dev Cell 21 , 29 – 31 . doi: 10.1016/j.devcel.2011.06.034 OpenUrl CrossRef PubMed Web of Science ↵ Rajan , A. , and Perrimon , N . ( 2012 ). Drosophila cytokine unpaired 2 regulates physiological homeostasis by remotely controlling insulin secretion . Cell 151 , 123 – 137 . doi: 10.1016/j.cell.2012.08.019 OpenUrl CrossRef PubMed Web of Science ↵ Ramirez , J.M. , Folkow , L.P. , and Blix , A.S . ( 2007 ). Hypoxia tolerance in mammals and birds: from the wilderness to the clinic . Annu Rev Physiol 69 , 113 – 143 . doi: 10.1146/annurev.physiol.69.031905.163111 OpenUrl CrossRef PubMed Web of Science ↵ Regan , J.C. , Khericha , M. , Dobson , A.J. , Bolukbasi , E. , Rattanavirotkul , N. , and Partridge , L . ( 2016 ). Sex difference in pathology of the ageing gut mediates the greater response of female lifespan to dietary restriction . eLife 5 , e10956 . doi: 10.7554/eLife.10956 OpenUrl CrossRef PubMed ↵ Regan , J.C. , Lu , Y.X. , Urena , E. , Meilenbrock , R.L. , Catterson , J.H. , Kissler , D. , Frohlich , J. , Funk , E. , and Partridge , L . ( 2022 ). Sexual identity of enterocytes regulates autophagy to determine intestinal health, lifespan and responses to rapamycin . Nat Aging 2 , 1145 – 1158 . doi: 10.1038/s43587-022-00308-7 OpenUrl CrossRef PubMed ↵ Reiff , T. , Jacobson , J. , Cognigni , P. , Antonello , Z. , Ballesta , E. , Tan , K.J. , Yew , J.Y. , Dominguez , M. , and Miguel-Aliaga , I . ( 2015 ). Endocrine remodelling of the adult intestine sustains reproduction in Drosophila . eLife 4 , e06930 . doi: 10.7554/eLife.06930 OpenUrl CrossRef PubMed ↵ Rideout , E.J. , Narsaiya , M.S. , and Grewal , S.S . ( 2015 ). The Sex Determination Gene transformer Regulates Male-Female Differences in Drosophila Body Size . PLoS Genet 11 , e1005683 . doi: 10.1371/journal.pgen.1005683 OpenUrl CrossRef ↵ Romao , D. , Muzzopappa , M. , Barrio , L. , and Milan , M . ( 2021 ). The Upd3 cytokine couples inflammation to maturation defects in Drosophila . Curr Biol 31 , 1780 – 1787 e1786. doi: 10.1016/j.cub.2021.01.080 OpenUrl CrossRef PubMed ↵ Romero , N.M. , Dekanty , A. , and Wappner , P . ( 2007 ). Cellular and developmental adaptations to hypoxia: a Drosophila perspective . Methods Enzymol 435 , 123 – 144 . doi: 10.1016/S0076-6879(07)35007-6 OpenUrl CrossRef PubMed ↵ Samanta , D. , Prabhakar , N.R. , and Semenza , G.L . ( 2017 ). Systems biology of oxygen homeostasis . Wiley Interdiscip Rev Syst Biol Med 9 . doi: 10.1002/wsbm.1382 OpenUrl CrossRef ↵ Sawala , A. , and Gould , A.P . ( 2017 ). The sex of specific neurons controls female body growth in Drosophila . PLoS Biol 15 , e2002252 . doi: 10.1371/journal.pbio.2002252 OpenUrl CrossRef PubMed ↵ Schito , L. , and Rey , S . ( 2018 ). Cell-Autonomous Metabolic Reprogramming in Hypoxia . Trends Cell Biol 28 , 128 – 142 . doi: 10.1016/j.tcb.2017.10.006 OpenUrl CrossRef PubMed ↵ Semenza , G.L . ( 2011 ). Oxygen sensing, homeostasis, and disease . N Engl J Med 365 , 537 – 547 . doi: 10.1056/NEJMra1011165 OpenUrl CrossRef PubMed Web of Science ↵ Semenza , G.L . ( 2014a ). Hypoxia-inducible factor 1 and cardiovascular disease . Annu Rev Physiol 76 , 39 – 56 . doi: 10.1146/annurev-physiol-021113-170322 OpenUrl CrossRef PubMed ↵ Semenza , G.L . ( 2014b ). Oxygen sensing, hypoxia-inducible factors, and disease pathophysiology . Annu Rev Pathol 9 , 47 – 71 . doi: 10.1146/annurev-pathol-012513-104720 OpenUrl CrossRef PubMed ↵ Shin , M. , Cha , N. , Koranteng , F. , Cho , B. , and Shim , J . ( 2020 ). Subpopulation of Macrophage-Like Plasmatocytes Attenuates Systemic Growth via JAK/STAT in the Drosophila Fat Body . Front Immunol 11 , 63 . doi: 10.3389/fimmu.2020.00063 OpenUrl CrossRef PubMed ↵ Sodders , M. , Das , A. , and Bai , H . ( 2025 ). Glial peroxisome dysfunction induces axonal swelling and neuroinflammation in Drosophila . G3 (Bethesda) 15 . doi: 10.1093/g3journal/jkae243 OpenUrl CrossRef ↵ Srinivasan , N. , Gordon , O. , Ahrens , S. , Franz , A. , Deddouche , S. , Chakravarty , P. , Phillips , D. , Yunus , A.A. , Rosen , M.K. , Valente , R.S. , et al. ( 2016 ). Actin is an evolutionarily-conserved damage-associated molecular pattern that signals tissue injury in Drosophila melanogaster . eLife 5 . doi: 10.7554/eLife.19662 OpenUrl CrossRef PubMed ↵ Sriskanthadevan-Pirahas , S. , Turingan , M.J. , Chahal , J.S. , Thorson , E. , Khan , S. , Tinwala , A.Q. , and Grewal , S.S . ( 2022 ). Adipose mitochondrial metabolism controls body growth by modulating systemic cytokine and insulin signaling . Cell Rep 39 , 110802 . doi: 10.1016/j.celrep.2022.110802 OpenUrl CrossRef PubMed ↵ Stefana , M.I. , Driscoll , P.C. , Obata , F. , Pengelly , A.R. , Newell , C.L. , MacRae , J.I. , and Gould , A.P . ( 2017 ). Developmental diet regulates Drosophila lifespan via lipid autotoxins . Nat Commun 8 , 1384 . doi: 10.1038/s41467-017-01740-9 OpenUrl CrossRef PubMed ↵ Stupnikov , M.R. , and Cardoso , W.V . ( 2017 ). Sensing oxygen inside and out . eLife 6 . doi: 10.7554/eLife.27467 OpenUrl CrossRef ↵ Takeishi , A. , Kuranaga , E. , Tonoki , A. , Misaki , K. , Yonemura , S. , Kanuka , H. , and Miura , M . ( 2013 ). Homeostatic epithelial renewal in the gut is required for dampening a fatal systemic wound response in Drosophila . Cell Rep 3 , 919 – 930 . doi: 10.1016/j.celrep.2013.02.022 OpenUrl CrossRef PubMed Web of Science ↵ Tamamouna , V. , Rahman , M.M. , Petersson , M. , Charalambous , I. , Kux , K. , Mainor , H. , Bolender , V. , Isbilir , B. , Edgar , B.A. , and Pitsouli , C . ( 2021 ). Remodelling of oxygen-transporting tracheoles drives intestinal regeneration and tumorigenesis in Drosophila . Nat Cell Biol 23 , 497 – 510 . doi: 10.1038/s41556-021-00674-1 OpenUrl CrossRef PubMed ↵ Tannahill , G.M. , Curtis , A.M. , Adamik , J. , Palsson-McDermott , E.M. , McGettrick , A.F. , Goel , G. , Frezza , C. , Bernard , N.J. , Kelly , B. , Foley , N.H. , et al. ( 2013 ). Succinate is an inflammatory signal that induces IL-1beta through HIF-1alpha . Nature 496 , 238 – 242 . doi: 10.1038/nature11986 OpenUrl CrossRef PubMed Web of Science ↵ Tennessen , J.M. , and Thummel , C.S . ( 2011 ). Coordinating growth and maturation - insights from Drosophila . Curr Biol 21 , R750 – 757 . doi: 10.1016/j.cub.2011.06.033 OpenUrl CrossRef PubMed ↵ Teodoro , R.O. , and O’Farrell , P.H . ( 2003 ). Nitric oxide-induced suspended animation promotes survival during hypoxia . EMBO J 22 , 580 – 587 . doi: 10.1093/emboj/cdg070 OpenUrl Abstract / FREE Full Text ↵ Texada , M.J. , Jorgensen , A.F. , Christensen , C.F. , Koyama , T. , Malita , A. , Smith , D.K. , Marple , D.F.M. , Danielsen , E.T. , Petersen , S.K. , Hansen , J.L. , et al. ( 2019 ). A fat-tissue sensor couples growth to oxygen availability by remotely controlling insulin secretion . Nat Commun 10 , 1955 . doi: 10.1038/s41467-019-09943-y OpenUrl CrossRef PubMed ↵ Texada , M.J. , Koyama , T. , and Rewitz , K . ( 2020 ). Regulation of Body Size and Growth Control . Genetics 216 , 269 – 313 . doi: 10.1534/genetics.120.303095 OpenUrl Abstract / FREE Full Text ↵ von Frieling , J. , Faisal , M.N. , Sporn , F. , Pfefferkorn , R. , Nolte , S.S. , Sommer , F. , Rosenstiel , P. , and Roeder , T. ( 2020 ). A high-fat diet induces a microbiota-dependent increase in stem cell activity in the Drosophila intestine . PLoS Genet 16 , e1008789 . doi: 10.1371/journal.pgen.1008789 OpenUrl CrossRef PubMed ↵ Wang , L. , Sexton , T.R. , Venard , C. , Giedt , M. , Guo , Q. , Chen , Q. , and Harrison , D.A . ( 2014 ). Pleiotropy of the Drosophila JAK pathway cytokine Unpaired 3 in development and aging . Dev Biol 395 , 218 – 231 . doi: 10.1016/j.ydbio.2014.09.015 OpenUrl CrossRef PubMed ↵ Wang , X. , Bao , H. , Huang , Y.C. , Barua , A. , Lai , C.M. , Sun , J. , Zhou , Y. , Cong , F. , Gong , S. , Chang , C.H. , and Deng , W.M . ( 2024 ). Sex-dimorphic tumor growth is regulated by tumor microenvironmental and systemic signals . Sci Adv 10 , eads4229 . doi: 10.1126/sciadv.ads4229 OpenUrl CrossRef PubMed ↵ Wat , L.W. , Chao , C. , Bartlett , R. , Buchanan , J.L. , Millington , J.W. , Chih , H.J. , Chowdhury , Z.S. , Biswas , P. , Huang , V. , Shin , L.J. , et al. ( 2020 ). A role for triglyceride lipase brummer in the regulation of sex differences in Drosophila fat storage and breakdown . PLoS Biol 18 , e3000595 . doi: 10.1371/journal.pbio.3000595 OpenUrl CrossRef PubMed ↵ Wat , L.W. , Chowdhury , Z.S. , Millington , J.W. , Biswas , P. , and Rideout , E.J . ( 2021 ). Sex determination gene transformer regulates the male-female difference in Drosophila fat storage via the adipokinetic hormone pathway . eLife 10 . doi: 10.7554/eLife.72350 OpenUrl CrossRef ↵ Wingrove , J.A. , and O’Farrell , P.H . ( 1999 ). Nitric oxide contributes to behavioral, cellular, and developmental responses to low oxygen in Drosophila . Cell 98 , 105 – 114 . doi: 10.1016/S0092-8674(00)80610-8 OpenUrl CrossRef PubMed Web of Science ↵ Woodcock , K.J. , Kierdorf , K. , Pouchelon , C.A. , Vivancos , V. , Dionne , M.S. , and Geissmann , F . ( 2015 ). Macrophage-derived upd3 cytokine causes impaired glucose homeostasis and reduced lifespan in Drosophila fed a lipid-rich diet . Immunity 42 , 133 – 144 . doi: 10.1016/j.immuni.2014.12.023 OpenUrl CrossRef PubMed ↵ Wouters , B.G. , and Koritzinsky , M . ( 2008 ). Hypoxia signalling through mTOR and the unfolded protein response in cancer . Nat Rev Cancer 8 , 851 – 864 . doi: 10.1038/nrc2501 OpenUrl CrossRef PubMed Web of Science ↵ Xie , H. , and Simon , M.C . ( 2017 ). Oxygen availability and metabolic reprogramming in cancer . J Biol Chem 292 , 16825 – 16832 . doi: 10.1074/jbc.R117.799973 OpenUrl Abstract / FREE Full Text ↵ Yamada , T. , Habara , O. , Kubo , H. , and Nishimura , T . ( 2018 ). Fat body glycogen serves as a metabolic safeguard for the maintenance of sugar levels in Drosophila . Development 145 . doi: 10.1242/dev.158865 OpenUrl Abstract / FREE Full Text ↵ Yang , H. , Kronhamn , J. , Ekstrom , J.O. , Korkut , G.G. , and Hultmark , D . ( 2015 ). JAK/STAT signaling in Drosophila muscles controls the cellular immune response against parasitoid infection . EMBO Rep 16 , 1664 – 1672 . doi: 10.15252/embr.201540277 OpenUrl CrossRef PubMed ↵ Ye , J. , and Medzhitov , R . ( 2019 ). Control strategies in systemic metabolism . Nat Metab 1 , 947 – 957 . doi: 10.1038/s42255-019-0118-8 OpenUrl CrossRef PubMed ↵ Yoon , S. , Shin , M. , and Shim , J . ( 2023 ). Inter-organ regulation by the brain in Drosophila development and physiology . J Neurogenet 37 , 57 – 69 . doi: 10.1080/01677063.2022.2137162 OpenUrl CrossRef ↵ Zandawala , M. , and Gera , J . ( 2024 ). Leptin- and cytokine-like unpaired signaling in Drosophila . Mol Cell Endocrinol 584 , 112165 . doi: 10.1016/j.mce.2024.112165 OpenUrl CrossRef PubMed ↵ Zhao , X. , and Karpac , J . ( 2017 ). Muscle Directs Diurnal Energy Homeostasis through a Myokine-Dependent Hormone Module in Drosophila . Curr Biol 27 , 1941 – 1955 e1946. doi: 10.1016/j.cub.2017.06.004 OpenUrl CrossRef PubMed ↵ Zhao , Y. , Duan , J. , Seah , H. , van de Leemput , J. , and Han , Z. ( 2025 ). JAK-STAT pathway activation compromises nephrocyte function in a Drosophila high-fat diet model of chronic kidney disease . bioRxiv , 2024.2003.2007.583967. doi: 10.1101/2024.03.07.583967 OpenUrl Abstract / FREE Full Text ↵ Zhou , F. , Rasmussen , A. , Lee , S. , and Agaisse , H . ( 2013 ). The UPD3 cytokine couples environmental challenge and intestinal stem cell division through modulation of JAK/STAT signaling in the stem cell microenvironment . Dev Biol 373 , 383 – 393 . doi: 10.1016/j.ydbio.2012.10.023 OpenUrl CrossRef PubMed ↵ Zipper , L. , Jassmann , D. , Burgmer , S. , Gorlich , B. , and Reiff , T . ( 2020 ). Ecdysone steroid hormone remote controls intestinal stem cell fate decisions via the PPARgamma-homolog Eip75B in Drosophila . eLife 9 . doi: 10.7554/eLife.55795 OpenUrl CrossRef View the discussion thread. Back to top Previous Next Posted July 02, 2025. Download PDF Email Thank you for your interest in spreading the word about bioRxiv. NOTE: Your email address is requested solely to identify you as the sender of this article. Your Email * Your Name * Send To * Enter multiple addresses on separate lines or separate them with commas. You are going to email the following Cytokine control of systemic hypoxia tolerance in Drosophila Message Subject (Your Name) has forwarded a page to you from bioRxiv Message Body (Your Name) thought you would like to see this page from the bioRxiv website. Your Personal Message CAPTCHA This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. Share Cytokine control of systemic hypoxia tolerance in Drosophila Kate Ding , Prajakta Bodkhe , Byoungchun Lee , Danielle Polan , Amy Wycislik , Tiffany Cheung , Sophie Wu , Savraj S Grewal bioRxiv 2025.06.30.661614; doi: https://doi.org/10.1101/2025.06.30.661614 Share This Article: Copy Citation Tools Cytokine control of systemic hypoxia tolerance in Drosophila Kate Ding , Prajakta Bodkhe , Byoungchun Lee , Danielle Polan , Amy Wycislik , Tiffany Cheung , Sophie Wu , Savraj S Grewal bioRxiv 2025.06.30.661614; doi: https://doi.org/10.1101/2025.06.30.661614 Citation Manager Formats BibTeX Bookends EasyBib EndNote (tagged) EndNote 8 (xml) Medlars Mendeley Papers RefWorks Tagged Ref Manager RIS Zotero Tweet Widget Facebook Like Google Plus One Subject Area Physiology Subject Areas All Articles Animal Behavior and Cognition (7643) Biochemistry (17717) Bioengineering (13910) Bioinformatics (42017) Biophysics (21480) Cancer Biology (18628) Cell Biology (25537) Clinical Trials (138) Developmental Biology (13392) Ecology (19935) Epidemiology (2067) Evolutionary Biology (24356) Genetics (15617) Genomics (22530) Immunology (17755) Microbiology (40438) Molecular Biology (17200) Neuroscience (88705) Paleontology (667) Pathology (2840) Pharmacology and Toxicology (4832) Physiology (7657) Plant Biology (15171) Scientific Communication and Education (2046) Synthetic Biology (4304) Systems Biology (9828) Zoology (2272)