Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms
Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms
复制标题
DOI：
10.1074/jbc.m601097200
复制
发表时间：
2006-06-09
影响因子：
4.8
通讯作者：
Greenberg, Andrew S.
中科院分区：
文献类型：
--
作者：
Miyoshi, Hideaki;Souza, Sandra C.;Greenberg, Andrew S.
激素敏感脂肪酶（HSL）是脂肪细胞中儿茶酚胺刺激的脂解的主要脂肪酶效应子。响应于儿茶酚胺的HSL依赖性脂解是由围脂蛋白A（Peri A）的蛋白激酶A（PKA）依赖性磷酸化介导的，所述围脂蛋白A是一种必需的脂滴（LD）相关蛋白。据信，周脂蛋白磷酸化对于HSL从细胞质到LD的易位是必需的，这是刺激的脂解中的关键事件。使用从小鼠胚胎成纤维细胞的围脂蛋白基因敲除小鼠（围（-/-）MEF）的逆转录病毒工程脂肪细胞，我们证明了细胞分级和共聚焦显微镜，高达50%的细胞HSL是LD相关的基础状态和PKA刺激的HSL易位是完全支持的腺病毒表达的突变体围脂蛋白缺乏所有六个PKA位点（围A德尔塔1-6）。PKA刺激的HSL易位在来自表达脂肪特异性Peri A Delta 1-6转基因的周脂蛋白缺失小鼠的分化的棕色脂肪细胞中得到证实。因此，PKA诱导的HSL易位是独立的perilipin磷酸化。然而，Peri A Delta 1-6未能增强MEF脂肪细胞或分化的棕色脂肪细胞中PKA刺激的脂解作用。因此，HSL在LD表面的脂解作用需要PKA依赖性周脂蛋白磷酸化。在Peri（-/-）MEF脂肪细胞中，PKA活化显著增加了HSL的量，HSL可以与异位Peri A交联并共免疫沉淀。值得注意的是，这种增强的交联在表达Peri A Delta 1-6的Peri（-/-）MEF脂肪细胞中是钝化的。这表明PKA依赖性周脂蛋白磷酸化促进（直接或间接）周脂蛋白与LD相关HSL的相互作用。这些结果重新定义并扩展了我们对perilipin如何调节脂肪细胞中HSL介导的脂解的理解。
Hormone-sensitive lipase (HSL) is the predominant lipase effector of catecholamine-stimulated lipolysis in adipocytes. HSL-dependent lipolysis in response to catecholamines is mediated by protein kinase A (PKA)-dependent phosphorylation of perilipin A (Peri A), an essential lipid droplet (LD)-associated protein. It is believed that perilipin phosphorylation is essential for the translocation of HSL from the cytosol to the LD, a key event in stimulated lipolysis. Using adipocytes retrovirally engineered from murine embryonic fibroblasts of perilipin null mice (Peri(-/-) MEF), we demonstrate by cell fractionation and confocal microscopy that up to 50% of cellular HSL is LD-associated in the basal state and that PKA-stimulated HSL translocation is fully supported by adenoviral expression of a mutant perilipin lacking all six PKA sites (Peri A Delta 1-6). PKA-stimulated HSL translocation was confirmed in differentiated brown adipocytes from perilipin null mice expressing an adipose-specific Peri A Delta 1-6 transgene. Thus, PKA-induced HSL translocation was independent of perilipin phosphorylation. However, Peri A Delta 1-6 failed to enhance PKA-stimulated lipolysis in either MEF adipocytes or differentiated brown adipocytes. Thus, the lipolytic action(s) of HSL at the LD surface requires PKA-dependent perilipin phosphorylation. In Peri(-/-) MEF adipocytes, PKA activation significantly enhanced the amount of HSL that could be cross-linked to and co-immunoprecipitated with ectopic Peri A. Notably, this enhanced cross-linking was blunted in Peri(-/-) MEF adipocytes expressing Peri A Delta 1-6. This suggests that PKA-dependent perilipin phosphorylation facilitates (either direct or indirect) perilipin interaction with LD-associated HSL. These results redefine and expand our understanding of how perilipin regulates HSL-mediated lipolysis in adipocytes.