Up-regulation of the active form of small GTPase Rabl3 promotes macroautophagy in vascular endothelial cells
Up-regulation of the active form of small GTPase Rabl3 promotes macroautophagy in vascular endothelial cells
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小 GTP 酶 Rab13 活性形式的上调可促进血管内皮细胞的巨自噬。
DOI：
10.1016/j.bbamcr.2017.01.003
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发表时间：
2017
影响因子：
5.1
通讯作者：
Guo Yuqi
中科院分区：
文献类型：
--
作者：
Zhang Lu;Dai Fang;Cui LiuQing;Zhou Bo;Guo Yuqi
巨噬（以下简称自噬）在血管内皮细胞（VEC）生物学和功能障碍中的重要性日益被认识到，但在血清存在的情况下，VEC中自噬的分子机制仍然知之甚少。先前，我们发现紫檀芪在血清存在下是一种有效的VECs自噬诱导剂。在本研究中，我们以紫檀芪为工具诱导VEC自噬，并使用高通量DAN芯片鉴定差异表达基因。研究发现，在紫菜芪处理的人脐带VECs （HUVECs）中，脑13小GTPase ras相关蛋白（Rab13）表达上调最为显著。在HUVECs中，敲低Rab13可阻断紫檀芪诱导的mTOR抑制和自噬，而过表达含有gtp的Rab13活性形式可诱导mTOR抑制和自噬。通过联合免疫荧光和共免疫沉淀（co-IP）实验，我们证明了紫菀芪或上调Rab13活性形式促进了Rab13与生长因子受体结合蛋白2 （Grb2）的相互作用。Grb2的下调抑制了紫檀芪或上调了rab13诱导的自噬活性形式。进一步的机制研究表明，Rab13通过与Grb2的功能相互作用，激活下游amp活化蛋白激酶（AMPK），阻断哺乳动物雷帕霉素靶蛋白（mTOR）信号通路，调节HUVECs的自噬。我们的研究明确了Rab13在营养丰富的条件下是VECs自噬的一种新的调节因子。
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.