Bezawork-Geleta Ayenachew, Devereux Camille J, Keenan Stacey N, Lou Jieqiong, Cho Ellie, Nie Shuai, De Souza David P, Narayana Vinod K, Siddall Nicole A, Rodrigues Carlos H M, Portelli Stephanie, Zheng Tenghao, Nim Hieu T, Ramialison Mirana, Hime Gary R, Dodd Garron T, Hinde Elizabeth, Ascher David B, Stroud David A, Watt Matthew J
Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, 3010, Australia.
School of Physics, The University of Melbourne, Melbourne, VIC, 3010, Australia.
Nat Commun. 2025 Mar 3;16(1):2135. doi: 10.1038/s41467-025-57405-5.
Membrane contact sites between organelles are critical for the transfer of biomolecules. Lipid droplets store fatty acids and form contacts with mitochondria, which regulate fatty acid oxidation and adenosine triphosphate production. Protein compartmentalization at lipid droplet-mitochondria contact sites and their effects on biological processes are poorly described. Using proximity-dependent biotinylation methods, we identify 71 proteins at lipid droplet-mitochondria contact sites, including a multimeric complex containing extended synaptotagmin (ESYT) 1, ESYT2, and VAMP Associated Protein B and C (VAPB). High resolution imaging confirms localization of this complex at the interface of lipid droplet-mitochondria-endoplasmic reticulum where it likely transfers fatty acids to enable β-oxidation. Deletion of ESYT1, ESYT2 or VAPB limits lipid droplet-derived fatty acid oxidation, resulting in depletion of tricarboxylic acid cycle metabolites, remodeling of the cellular lipidome, and induction of lipotoxic stress. These findings were recapitulated in Esyt1 and Esyt2 deficient mice. Our study uncovers a fundamental mechanism that is required for lipid droplet-derived fatty acid oxidation and cellular lipid homeostasis, with implications for metabolic diseases and survival.
细胞器之间的膜接触位点对于生物分子的转移至关重要。脂滴储存脂肪酸并与线粒体形成接触，线粒体可调节脂肪酸氧化和三磷酸腺苷的产生。脂滴 - 线粒体接触位点处的蛋白质分隔及其对生物过程的影响鲜有描述。利用邻近依赖性生物素化方法，我们在脂滴 - 线粒体接触位点鉴定出71种蛋白质，其中包括一种含有延伸突触结合蛋白（ESYT）1、ESYT2以及VAMP相关蛋白B和C（VAPB）的多聚体复合物。高分辨率成像证实该复合物定位于脂滴 - 线粒体 - 内质网的界面处，在此处它可能转移脂肪酸以促进β - 氧化。删除ESYT1、ESYT2或VAPB会限制脂滴衍生的脂肪酸氧化，导致三羧酸循环代谢物耗竭、细胞脂质组重塑以及脂毒性应激的诱导。这些发现也在Esyt1和Esyt2基因敲除小鼠中得到了验证。我们的研究揭示了脂滴衍生的脂肪酸氧化和细胞脂质稳态所需的一种基本机制，这对代谢性疾病和生存具有重要意义。
