Hyperglycaemia impairs mineralisation by disrupting coordination of bone and mTOR pathways during osteocyte differentiation

Hyperglycaemia impairs mineralisation by disrupting coordination of bone and mTOR pathways during osteocyte differentiation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (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],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Hyperglycaemia impairs mineralisation by disrupting coordination of bone and mTOR pathways during osteocyte differentiation Thibault Teissier, Rivka Dresner-Pollak, Lynne Cox This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8998079/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Diabetic patients exhibit increased bone fragility despite variable bone mineral density, yet hyperglycaemia has shown discordant effects on mineralisation in different studies. Notably, its impact on the differentiation and function of osteocytes, the most abundant bone cell type, remains poorly understood. We examined osteoblast-to-osteocyte differentiation by exposing murine IDG-SW3 cells to normoglycaemic or hyperglycaemic conditions. Hyperglycaemia initially enhanced matrix production but later proved detrimental. Whole-cell proteomics revealed that under normoglycaemia, differentially expressed proteins (DEPS) converged towards bone differentiation and mTOR signalling pathways; this was disrupted under hyperglycaemia, with DEPs dispersed across unrelated processes, indicating loss of programme coordination and specialisation. Both proteomics and functional analyses convergently identified a critical transition at week 3-4, where high glucose drives premature osteogenesis arrest. Hyperglycaemia also induced mitochondrial and lysosomal dysfunction, senescence-associated β-galactosidase activity and proliferation arrest; however, nuclear shrinkage rather than enlargement differentiates this state from classical senescence. mTOR inhibitor studies revealed temporal complexity in mTOR's role. Pan-mTOR inhibition during the first week alone was sufficient to impair mineralisation at week 4, establishing an early mTOR-dependent sensitivity window. While pan-mTOR inhibitors and rapamycin inhibited mineralisation at week 3, only rapamycin rescued hyperglycaemia-impaired mineralisation by week 4, indicating that mTORC1 shifts from supporting to inhibiting mineralisation during this transition. These findings establish pathway coordination as a key determinant of successful osteocyte differentiation and explain contradictory reports of glucose effects on mineralisation through timing-dependent mechanisms. They also highlight the need for caution in choice, dose and timing of mTOR inhibitors as senotherapeutics in diabetic patients. Biological sciences/Physiology/Bone Biological sciences/Physiology/Metabolism/Metabolic diseases/Diabetes Health sciences/Pathogenesis Health sciences/Endocrinology/Endocrine system and metabolic diseases/Diabetes diabetes bone fragility osteocyte differentiation mTOR senescence Full Text Additional Declarations There is no conflict of interest Supplementary Files SupplementaryFigure1.pdf Supplementary Figure 1 SupplementaryFigure2.pdf Supplementary Figure 2 SupplementaryFigure3.pdf Supplementary Figure 3 SupplementaryFigure4.pdf Supplementary Figure 4 SupplementaryFigure5.pdf Supplementary Figure 5 SupplementaryFigure6.pdf Supplementary Figure 6 SupplementaryFigure7.pdf Supplementary Figure 7 SupplementaryFigure8.pdf Supplementary Figure 8 SupplementaryFigure9.pdf Supplementary Figure 9 SupplementaryFigure10.pdf Supplementary Figure 10 SupplementaryFigure11.pdf Supplementary Figure 11 SupplementaryFigure12.pdf Supplementary Figure 12 Supplementarymethods.pdf Supplementary methods Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8998079","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":607284714,"identity":"7f00d583-a051-4415-a025-a8b2959ae5d9","order_by":0,"name":"Thibault 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