Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia.
School of Physics, University of Melbourne, Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia.
J Lipid Res. 2021;62:100016. doi: 10.1194/jlr.RA120001126. Epub 2021 Jan 5.
Perilipin 5 (PLIN5) 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 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. FLIM-FRET analysis of protein-protein interactions showed that PLIN5 S155 phosphorylation regulates PLIN5 interaction with adipose triglyceride lipase at the lipid droplet, but not with α-β hydrolase domain-containing 5. Re-expression of PLIN5 S155A in the liver of Plin5 liver-specific null mice reduced lipolysis compared with wild-type PLIN5 re-expression, but was not associated with other changes in hepatic lipid metabolism. 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.
perilipin 5 (PLIN5) 是一种与脂滴相关的蛋白，它协调高度氧化组织中的细胞内脂肪分解，并被认为可以通过蛋白激酶 A (PKA) 的磷酸化来调节脂质代谢。我们试图确定 PLIN5 中的 PKA 磷酸化位点，并评估它们在培养细胞和小鼠肝脏中的功能相关性。我们检测到 S155 上的磷酸化，并确定 S155 是脂质代谢的一个功能重要位点。在 Plin5 缺失细胞中表达磷酸化缺陷的 PLIN5 S155A 导致脂肪分解和甘油三酯衍生脂肪酸氧化的速率降低。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 与脂肪甘油三酯脂肪酶在脂滴上的相互作用，但不与含 α-β 水解酶结构域 5 的蛋白相互作用。PLIN5 S155A 在 Plin5 肝特异性缺失小鼠肝脏中的重新表达与野生型 PLIN5 重新表达相比，降低了脂肪分解，但与肝脏脂质代谢的其他变化无关。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，并且为 PLIN5 在协调脂质和葡萄糖代谢中的关键作用提供了更多证据。
