title: Up-regulation of the active form of small GTPase Rab13 promotes macroautophagy in vascular endothelial cells.
abstract: The importance of macroautophagy (hereafter referred to as autophagy) in vascular endothelial cell (VEC) biology and dysfunction is increasingly recognized, but the molecular mechanisms of autophagy in VECs in the presence of serum are still poorly understood. Previously, we identified pterostilbene as a potent autophagy inducer of VECs in the presence of serum. In this study, we used pterostilbene as a tool to induce VEC autophagy and identified the differentially expressed genes using high-throughput DAN microarray. The small GTPase Ras-related protein in brain 13 (Rab13) was found to be the most significantly up-regulated gene in pterostilbene-treated human umbilical VECs (HUVECs). Knockdown of Rab13 blocked pterostilbene-induced mTOR inhibition and autophagy, whereas overexpression of the GTP-containing active form of Rab13 induced mTOR inhibition and autophagy in HUVECs. Using a combination of immunofluorescence and co-immunoprecipitation (co-IP) assays, we demonstrated that pterostilbene or up-regulation of the active form of Rab13 promoted the interaction between Rab13 and growth factor receptor-bound protein 2 (Grb2). Knockdown of Grb2 suppressed pterostilbene or up-regulation of the active form of Rab13-induced autophagy. Further mechanistic studies revealed that Rab13 activated the downstream AMP-activated protein kinase (AMPK) and blocked mammalian target of rapamycin (mTOR) signaling by its functional interaction with Grb2 to regulate autophagy in HUVECs. Our study firmly establishes Rab13 as a novel regulator of autophagy in VECs under nutrient-enriched conditions.
authors.affiliation: College of Bioengineering, Henan University of Technology, Lianhua Street, Zhengzhou 450001, China. Electronic address: chaperones@163.com.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Dai
authors.affiliation: College of Bioengineering, Henan University of Technology, Lianhua Street, Zhengzhou 450001, China.
authors.forename: LiuQing
authors.initials: L
authors.lastname: Cui
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
authors.affiliation: Henan Provincial People's Hospital, Zhengzhou 450003, China.
authors.forename: YuQi
authors.initials: Y
authors.lastname: Guo
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects / Q000235:genetics*; D051380:GRB2 Adaptor Protein / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013267:Stilbenes / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D034741:RNA, Small Interfering; D013267:Stilbenes; C107773:pterostilbene; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; C085485:RAB13 protein, human; D020691:rab GTP-Binding Proteins
keywords: AMP-activated protein kinase; Growth factor receptor-bound protein 2; Macroautophagy; Pterostilbene; Small GTPase Rab13; Vascular endothelial cell