Moonlighting Cytosolic Function of ACAD9: Suppression of TRAF6-Mediated Osteoclastogenesis and Protection Against Osteoporosis

Moonlighting Cytosolic Function of ACAD9: Suppression of TRAF6-Mediated Osteoclastogenesis and Protection Against Osteoporosis | 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 Moonlighting Cytosolic Function of ACAD9: Suppression of TRAF6-Mediated Osteoclastogenesis and Protection Against Osteoporosis Ying Cheng, Mimi Wang, Chao Yuan, Yi Zhang, Mengmeng Peng, Yundie Liu, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6626293/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 26 Mar, 2026 Read the published version in Cell Death & Disease → Version 1 posted 10 You are reading this latest preprint version Abstract Acyl-CoA dehydrogenase-9 (ACAD9) is classically known for its role in mitochondrial fatty acid β-oxidation and complex I assembly. Here, we identify ACAD9 deficiency as a clinically relevant risk factor for fragility fractures and reveal a previously unrecognized cytosolic function of ACAD9 in suppressing osteoclast differentiation, thereby protecting against osteoporosis. Mechanistically, while preserving its canonical mitochondrial role in complex I assembly, we find that ACAD9 also facilitates the formation of respiratory supercomplexes (I+III+IV). Notably, in the cytosol, ACAD9 competitively binds to TRAF6, preventing its interaction with the E2 ubiquitin-conjugating complex UBC13/UEV1A, and thereby blocking K63-linked polyubiquitination and downstream activation of the RANK/TRAF6/TAK1/NFATc1 signaling cascade. Additionally, ACAD9 promotes K48-linked polyubiquitination of TRAF6, leading to its proteasomal degradation. Osteoclast-specific Acad9 knockout mice exhibit increased osteoclast numbers and decreased bone mass. These findings uncover a novel extramitochondrial function of ACAD9 in regulating osteoclast differentiation and maturation, and offer potential therapeutic insights for targeting osteoclast hyperactivity in osteoporosis. Biological sciences/Cell biology Biological sciences/Molecular biology/Proteolysis ACAD9 TRAF6 Mitochondrial supercomplex osteoclastogenesis Full Text Additional Declarations There is no duality of interest Supplementary Files SupplementaryMaterials.pdf Moonlighting Cytosolic Function of ACAD9: Suppression of TRAF6-Mediated Osteoclastogenesis and Protection Against Osteoporosis Cite Share Download PDF Status: Published Journal Publication published 26 Mar, 2026 Read the published version in Cell Death & Disease → Version 1 posted Unknown event 25 Nov, 2025 Editorial decision: Reject after peer review 24 Nov, 2025 Review # 1 received at journal 21 Nov, 2025 Review # 2 received at journal 14 Nov, 2025 Reviewer # 2 agreed at journal 11 Nov, 2025 Reviewer # 1 agreed at journal 10 Nov, 2025 Reviewers invited by journal 04 Aug, 2025 Submission checks completed at journal 09 May, 2025 First submitted to journal 09 May, 2025 Editor assigned by journal 09 May, 2025 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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