Perilipin (PLIN) 5 is a lipid droplet-associated protein that coordinates intracellular lipolysis in highly oxidative tissues and is thought to regulate lipid metabolism in response to phosphorylation by protein kinase A (PKA). We sought to identify PKA phosphorylation sites in PLIN5 and assess their functional relevance in cultured cells and the livers of mice. We detected phosphorylation on S155, S161 and S163 of recombinant PLIN5 by PKA in vitro and identified S155 as a functionally important site for lipid metabolism. Expression of phosphorylation-defective PLIN5 S155A in Plin5 null cells resulted in decreased rates of lipolysis and triglyceride-derived fatty acid oxidation compared with cells expressing wildtype PLIN5. These differences in lipid metabolism were not associated with differences in the cellular distribution of PLIN5. Rather, FLIM-FRET analysis of protein-protein interactions showed that PLIN5 S155 phosphorylation regulates PLIN5 interaction with adipose triglyceride lipase (ATGL) at the lipid droplet, but not with the co-activator of ATGL, α-β hydrolase domain-containing 5 (ABHD5). Re-expression of PLIN5 S155A in the liver of Plin5 liver-specific null mice reduced lipolysis when compared to mice with wildtype PLIN5 re-expression, but was not associated with other changes in hepatic lipid metabolism, such as fatty acid oxidation, de novo lipogenesis and triglyceride secretion. Furthermore, glycemic control was impaired in mice with expression of PLIN5 S155A compared with mice expressing PLIN5. Together, these studies demonstrate that PLIN5 S155 is required for PKA-mediated lipolysis and builds on the body of evidence demonstrating a critical role for PLIN5 in coordinating lipid and glucose metabolism.

中文翻译：

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PKA 磷酸化 Perilipin 5 S155 是控制肝脂质代谢和血糖控制所必需的。


Perilipin (PLIN) 5 是一种脂滴相关蛋白，可协调高度氧化组织中的细胞内脂肪分解，并被认为可响应蛋白激酶 A (PKA) 的磷酸化来调节脂质代谢。我们试图鉴定 PLIN5 中的 PKA 磷酸化位点，并评估其在培养细胞和小鼠肝脏中的功能相关性。我们在体外通过 PKA 检测了重组 PLIN5 S155、S161 和 S163 的磷酸化，并确定 S155 是脂质代谢的功能重要位点。与表达野生型 PLIN5 的细胞相比， Plin5缺失细胞中磷酸化缺陷型 PLIN5 S155A 的表达导致脂肪分解和甘油三酯衍生的脂肪酸氧化速率降低。脂质代谢的这些差异与 PLIN5 细胞分布的差异无关。相反，蛋白质-蛋白质相互作用的 FLIM-FRET 分析表明，PLIN5 S155 磷酸化调节 PLIN5 与脂滴处的脂肪甘油三酯脂肪酶 (ATGL) 的相互作用，但不调节与 ATGL 的共激活剂（包含 α-β 水解酶结构域的 5）的相互作用。 ABHD5）。与野生型 PLIN5 重新表达的小鼠相比，Plin5 肝脏特异性无效小鼠肝脏中 PLIN5 S155A 的重新表达减少了脂肪分解，但与肝脏脂质代谢的其他变化（例如脂肪酸氧化、从头脂肪生成）无关。和甘油三酯的分泌。此外，与表达 PLIN5 的小鼠相比，表达 PLIN5 S155A 的小鼠的血糖控制受损。总之，这些研究表明 PLIN5 S155 是 PKA 介导的脂肪分解所必需的，并以大量证据为基础，证明 PLIN5 在协调脂质和葡萄糖代谢中发挥着关键作用。