Phosphorylation of PLIN3 by AMPK promotes dispersion of lipid droplets during starvation.
Phosphorylation of PLIN3 by AMPK promotes dispersion of lipid droplets during starvation.
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AMPK 磷酸化 PLIN3 可促进饥饿期间脂滴的分散。
DOI：
10.1007/s13238-018-0593-9
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发表时间：
2019
期刊：
影响因子：
21.1
通讯作者：
Songyang Zhou
中科院分区：
文献类型：
--
作者：
Zhu Jianxi;Xu Mingyang;Liu Yi;Zhuang Lisha;Ying Kejun;Liu Feng;Liu Dan;Ma Wenbin;Songyang Zhou
脂滴（LD）是储存库的动态脂质储存细胞器，是无数细胞过程的必需底物来源，并保护细胞免受脂毒性（Ohsaki 等，2006）。 LD 和脂肪储存稳态的破坏与动脉粥样硬化、肥胖和 II 型糖尿病等代谢疾病有关（Levin 等，2001）。从结构上看，LD 中的中性脂质核心被磷脂单层包围，并涂有特定蛋白质（Storey 等，2011）。 Perilipin 家族蛋白是主要的 LD 相关蛋白。在哺乳动物中，Perilipin 1 (PLIN1) 主要在脂肪组织中表达，是脂肪细胞脂肪分解的主要调节因子 (Kuo et al., 2017)。 PLIN2 和 PLIN3 有助于在大多数其他细胞类型中包被 LD（Bulankina 等，2009）。与 PLIN1/2 不同，PLIN3 主要针对新生 LD，并且在与 LD 不相关时在细胞质中保持稳定（Hocsak 等人，2010）。它已成为 LD 生物合成和降解的调节剂（Bulankina 等，2009）。 AMP 激活蛋白激酶 (AMPK) 由 α、β 和 γ 亚基组成，调节细胞能量稳态 (Carling et al., 1994)。 AMPK 在葡萄糖剥夺等应激条件下通过 AMP-γ 亚基结合或 Thr172 磷酸化而激活。激活的 AMPK 作用于多种途径的靶标，从碳水化合物、蛋白质和脂质代谢到线粒体生物合成、自噬和细胞生长（Fraser et al., 2013）。尽管 AMPK 是脂质代谢的主要细胞调节因子（Dyck 等，1999），但 LD 稳态中 AMPK 的直接靶标仍然难以捉摸。我们在此报告，PLIN3 是一种新型生理 AMPK 底物，其中 AMPK 的磷酸化可能有助于暴露 PLIN3 C 末端以促进 LD 分散。AMPK 激活可以在饥饿期间或添加 AMPK 激活剂后促进 LD 分散（Herms 等，2015）。为了确定 AMPK 调节的 perilipin 家族蛋白的激活是否可能是 LD 分散的关键，我们进行了双分子荧光互补 (BiFC) 测定，以使用 YFPn 标记的 AMPKα1 和 YFPc 标记的 perilipin 检测 AMPK-perilipin 相互作用（图 1 A 和 S1）。有趣的是，AMPKα1 可以与 PLIN3 相互作用，但不能与 PLIN2/4/5 相互作用（图 1 B）。此次互动进一步
Lipid droplets (LDs) are dynamic lipid-storage organelles of storage depots and sources of essential substrates for myriad cellular processes and protect cells from lipotoxicity (Ohsaki et al., 2006). Disrupted LD and fat storage homeostasis has been linked to metabolic diseases such as atherosclerosis, obesity, and type II diabetes (Levin et al., 2001). Structurally, the core of neutral lipids in LDs is surrounded by a phospholipid monolayer and coated with specific proteins (Storey et al., 2011). Perilipin family of proteins are the predominant LD-associated proteins. In mammals, Perilipin 1 (PLIN1) is primarily expressed in adipose tissues and a major regulator of lipolysis in adipocytes (Kuo et al., 2017). PLIN2 and PLIN3 help coat LDs in most other cell types (Bulankina et al., 2009). Unlike PLIN1/2, PLIN3 targets primarily to nascent LDs and remains stable in the cytoplasm when not associated with LDs (Hocsak et al., 2010). It has emerged as a regulator of LD biogenesis and degradation (Bulankina et al., 2009). The AMP-activated protein kinase (AMPK) is comprised of α, β and γ subunits and regulates cellular energy homeostasis (Carling et al., 1994). Activation of AMPK upon stress conditions such as glucose deprivation, occurs through AMP-γ subunit binding or Thr172 phosphorylation. Activated AMPK acts on targets in diverse pathways, from carbohydrate, protein and lipid metabolism to mitochondrial biogenesis, autophagy and cell growth (Fraser et al., 2013). Despite being a major cellular regulator of lipid metabolism (Dyck et al., 1999), direct targets of AMPK in LD homeostasis remain elusive. We report here that PLIN3 is a novel physiological AMPK substrate where phosphorylation by AMPK may help expose PLIN3 C-terminus to promote LD dispersion.AMPK activation can promote LD dispersion during starvation or following addition of AMPK activators (Herms et al., 2015). To determine whether AMPK-regulated activation of perilipin family proteins might be key to LD dispersion, we performed Bi-molecular Fluorescence Complementation (BiFC) assays to detect AMPK-perilipin interaction using YFPn-tagged AMPKα1 and YFPc-tagged perilipins (Figs. 1 A and S1). Interestingly, AMPKα1 could interact with PLIN3, but not PLIN2/4/5 (Fig. 1 B). This interaction was further