ABSTRACT

PDPK1 (3-phosphoinositide dependent protein kinase 1) is a phosphorylation-regulated kinase that plays a central role in activating multiple signaling pathways and cellular processes. Here, this study shows that PDPK1 turns on macroautophagy/autophagy as a SUMOylation-regulated kinase. In vivo data demonstrate that the SUMO modification of PDPK1 is a physiological feature in the brain and that it can be induced by viral infections. The SUMOylated PDPK1 regulates its own phosphorylation and subsequent activation of the AKT1 (AKT serine/threonine kinase 1)-MTOR (mechanistic target of rapamycin kinase) pathway. However, SUMOylation of PDPK1 is inhibited by binding to PIK3C3 (phosphatidylinositol 3-kinase catalytic subunit type 3). The nonSUMOylated PDPK1 then tethers LC3 to the endoplasmic reticulum to initiate autophagy, and it acts as a key component in forming the autophagic vacuole. Collectively, this study reveals the intricate molecular regulation of PDPK1 by post-translational modification in controlling autophagosome biogenesis, and it highlights the role of PDPK1 as a sensor of cellular stress and regulator of autophagosome biogenesis.

Abbreviations: AKT1: AKT serine/threonine kinase 1; ATG14: autophagy related 14; Co-IP: co-immunoprecipitation; ER: endoplasmic reticulum; hpi: hours post-infection; mAb: monoclonal antibody; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MOI: multiplicity of infection; MTOR: mechanistic target of rapamycin kinase; pAb: polyclonal antibody; PDPK1: 3-phosphoinositide dependent protein kinase 1; PI3K: phosphoinositide 3-kinase; PIK3C3: phosphatidylinositol 3-kinase catalytic, subunit type 3; RPS6KB1: ribosomal protein S6 kinase B1; SGK: serum/glucocorticoid regulated kinase; SQSTM1: sequestosome 1; SUMO: small ubiquitin like modifier; UBE2I/UBC9: ubiquitin conjugating enzyme E2 I; UVRAG: UV radiation resistance associated

摘要

PDPK1（3-磷酸肌醇依赖性蛋白激酶 1）是一种磷酸化调节激酶，在激活多种信号通路和细胞过程中起核心作用。在这里，这项研究表明 PDPK1 作为一种 SUMO 化调节激酶打开了巨自噬/自噬。体内数据表明，PDPK1 的 SUMO 修饰是大脑中的一种生理特征，它可以由病毒感染诱导。SUMOylated PDPK1 调节其自身的磷酸化和随后激活 AKT1（AKT 丝氨酸/苏氨酸激酶 1）-MTOR（雷帕霉素激酶的机械靶标）途径。然而，PDPK1 的 SUMO 化通过与 PIK3C3（磷脂酰肌醇 3-激酶催化亚基 3 型）结合而受到抑制。非 SUMO 化的 PDPK1 然后将 LC3 连接到内质网以启动自噬，它是形成自噬泡的关键成分。总的来说，这项研究揭示了 PDPK1 通过翻译后修饰在控制自噬体生物发生中的复杂分子调控，

缩写： AKT1：AKT丝氨酸/苏氨酸激酶1；ATG14：自噬相关14；Co-IP：免疫共沉淀；ER：内质网；hpi：感染后的小时数；mAb：单克隆抗体；MAP1LC3/LC3：微管相关蛋白1轻链3；MOI：感染复数；MTOR：雷帕霉素激酶的机制靶点；pAb：多克隆抗体；PDPK1：3-磷酸肌醇依赖性蛋白激酶 1；PI3K：磷酸肌醇 3-激酶；PIK3C3：磷脂酰肌醇 3-激酶催化，亚基 3 型；RPS6KB1：核糖体蛋白 S6 激酶 B1；SGK：血清/糖皮质激素调节激酶；SQSTM1：隔离体 1；SUMO：小泛素样修饰剂；UBE2I/UBC9：泛素结合酶 E2 I；UVRAG：相关的抗紫外线辐射