Sankar Devanarayanan Siva, Dengjel Joern
Department of Biology, University of Fribourg, Fribourg, Switzerland.
Global Health Institute, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
Autophagy. 2025 Jan;21(1):243-245. doi: 10.1080/15548627.2024.2414386. Epub 2024 Oct 14.
The ULK1 kinase complex plays a crucial role in autophagosome biogenesis. To identify interactors or regulators of ULK1 complex assembly influencing autophagosome biogenesis, we performed an interaction proteomics screen. Employing both affinity purification and proximity labeling of - and -terminal tagged fusion proteins coupled to quantitative mass spectrometry, we identified 317 high-confidence interactors or neighbors of the four ULK1 complex members, including both member-specific and common interactors. Interactions with selective macroautophagy/autophagy receptors indicate the activation of selective autophagy pathways by 90 min of nutrient starvation. Focusing on the ULK1 effector protein BAG2, a common interactor identified by both approaches, we highlight that ULK1 phosphorylates BAG2, supporting the localization of the scaffold and autophagy inducer AMBRA1 to the ER, thereby positively regulating autophagy initiation.: AMBRA1: autophagy and beclin 1 regulator 1; ATG: autophagy related; ER: endoplasmic reticulum; HA: hemagglutinin; KD: knockdown; KO: knockout; MS: mass spectrometry; PTM: posttranslational modification; RB1CC1/FIP200: RB1 inducible coiled-coil 1; SQSTM1/p62: sequestosome 1; ULK1: unc-51 like autophagy activating kinase 1; WIPI2: WD repeat domain, phosphoinositide interacting 2.
ULK1激酶复合物在自噬体生物发生过程中起着关键作用。为了鉴定影响自噬体生物发生的ULK1复合物组装的相互作用蛋白或调节因子，我们进行了一项相互作用蛋白质组学筛选。通过结合定量质谱的亲和纯化和对C端和N端标记融合蛋白的邻近标记，我们鉴定出了317个与ULK1复合物四个成员具有高可信度的相互作用蛋白或邻近蛋白，包括成员特异性和共同的相互作用蛋白。与选择性巨自噬/自噬受体的相互作用表明，在营养饥饿90分钟后选择性自噬途径被激活。聚焦于ULK1效应蛋白BAG2（一种通过两种方法均鉴定出的共同相互作用蛋白），我们强调ULK1使BAG2磷酸化，支持支架蛋白和自噬诱导剂AMBRA1定位于内质网，从而正向调节自噬起始。：AMBRA1：自噬和Beclin 1调节因子1；ATG：自噬相关；ER：内质网；HA：血凝素；KD：敲低；KO：敲除；MS：质谱；PTM：翻译后修饰；RB1CC1/FIP200：RB1诱导卷曲螺旋1；SQSTM1/p62：聚集体蛋白1；ULK1：unc-51样自噬激活激酶1；WIPI2：WD重复结构域，磷酸肌醇相互作用蛋白2 。
