蛋白棕榈酰化酶DHHC5在脂肪细胞分化发育中的作用及分子机制

蛋白质的棕榈酰化广泛参与了机体的多种生理功能，但其对脂肪细胞分化发育的影响尚不清楚。我们前期研究发现有6个蛋白质棕榈酰化酶（DHHCs）家族成员在脂肪组织中表达量较高。在3T3-L1细胞中敲低DHHC5能够显著抑制脂肪细胞的分化，证明DHHC5对脂肪细胞分化是必需的。进一步的研究发现DHHC5在油酸处理时可以从细胞质膜到脂滴表面转移，而且DHHC5介导了3T3-L1细胞对脂肪酸的吸收。此外，我们对DHHC5的底物进行了鉴定，发现Caveolin 1是其底物之一，并有其它一些潜在的底物需要验证。未来的工作是进一步完善DHHC5的作用机制，鉴定并验证DHHC5介导脂肪细胞分化的底物，明确棕榈酰化对底物蛋白功能的影响，揭示DHHC5的作用机制，并最终利用动物模型阐明DHHC5的生理功能。本课题的顺利进行将揭示蛋白质棕榈酰化在脂肪细胞分化发育中的作用及其分子机制，有助于揭示肥胖症的发生机制。

Protein palmitoylation is crucial for multiple protein functions, such as intracellular trafficking, protein-protein interaction and subcellular localization. However, little has been know about its function in adipogenesis. Our preliminary studies showed that 6 out of the 24 palmitoyl acyltransferases (DHHC family) are expressed in adipose tissue, among which knockdown of DHHC5 dramatically inhibited cell differentiation of 3T3-L1 cells, indicating that protein palmitoylation is crucial for adipogenesis. Further studies on DHHC5 subcellular localization showed that it can relocate from plasma membrane to lipid droplet upon oleate treatment. We have also showed that DHHC5 is essential for fatty acid uptake in 3T3-L1 cells. We have also made some progress in the identification of DHHC5 substrates from lipid droplet proteins. We found Caveolin 1 is one of the substrates of DHHC5, and there are some other potential ones to be confirmed. The current proposal will focus on the following aspects using a combined approaches of biochemistry, molecular biology and cell biology: to further identify and confirm the substrates of DHHC5; to figure out the effect of palmitoylation on the functions of the substrates; and to elucidate the physiological function of DHHC5 through animal models.