Ligand-Stimulated VEGFR2 Signaling is Regulated by Co-Ordinated Trafficking and Proteolysis
Ligand-Stimulated VEGFR2 Signaling is Regulated by Co-Ordinated Trafficking and Proteolysis
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DOI：
10.1111/j.1600-0854.2009.01001.x
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发表时间：
2010-01-01
期刊：
影响因子：
4.5
通讯作者：
Ponnambalam, Sreenivasan
中科院分区：
文献类型：
--
作者：
Bruns, Alexander F.;Herbert, Shane P.;Ponnambalam, Sreenivasan
血管内皮生长因子A （VEGF-A）通过VEGF受体2 （VEGFR2）诱导的信号传导调节哺乳动物生理性和病理性血管生成。然而，vegfr2介导的细胞内信号传导的时空机制尚不清楚。在这里，我们定义了VEGFR2运输和蛋白水解的途径，该途径调节vegf - a刺激的信号传导和内皮细胞迁移。配体刺激的VEGFR2激活和泛素化先于与核内体相关的蛋白水解和细胞质结构域去除。可溶性的VEGFR2细胞质结构域片段显示酪氨酸磷酸化和下游细胞内信号的激活。网格蛋白重链或ESCRT-0亚基的缺失对内吞作用的扰动会对配体刺激的VEGFR2蛋白水解和信号传导产生不同的影响。这种新的VEGFR2蛋白水解被26S蛋白酶体活性抑制剂阻断。蛋白酶体活性的抑制延长了vegf - a诱导的细胞内c-Akt和内皮一氧化氮合酶（eNOS）的信号传导。vegf - a刺激的内皮细胞迁移依赖于VEGFR2和VEGFR酪氨酸激酶活性。蛋白酶体活性的抑制刺激了vegf - a介导的内皮细胞迁移。VEGFR2的内吞作用、泛素化和蛋白水解也可以通过蛋白激酶c依赖途径刺激。因此，去除与磷酸化、泛素化和运输相关的VEGFR2羧基末端对于VEGF刺激的内皮信号传导和细胞迁移是必要的。
Vascular endothelial growth factor A (VEGF-A)-induced signaling through VEGF receptor 2 (VEGFR2) regulates both physiological and pathological angiogenesis in mammals. However, the temporal and spatial mechanism underlying VEGFR2-mediated intracellular signaling is not clear. Here, we define a pathway for VEGFR2 trafficking and proteolysis that regulates VEGF-A-stimulated signaling and endothelial cell migration. Ligand-stimulated VEGFR2 activation and ubiquitination preceded proteolysis and cytoplasmic domain removal associated with endosomes. A soluble VEGFR2 cytoplasmic domain fragment displayed tyrosine phosphorylation and activation of downstream intracellular signaling. Perturbation of endocytosis by the depletion of either clathrin heavy chain or an ESCRT-0 subunit caused differential effects on ligand-stimulated VEGFR2 proteolysis and signaling. This novel VEGFR2 proteolysis was blocked by the inhibitors of 26S proteasome activity. Inhibition of proteasome activity prolonged VEGF-A-induced intracellular signaling to c-Akt and endothelial nitric oxide synthase (eNOS). VEGF-A-stimulated endothelial cell migration was dependent on VEGFR2 and VEGFR tyrosine kinase activity. Inhibition of proteasome activity in this assay stimulated VEGF-A-mediated endothelial cell migration. VEGFR2 endocytosis, ubiquitination and proteolysis could also be stimulated by a protein kinase C-dependent pathway. Thus, removal of the VEGFR2 carboxyl terminus linked to phosphorylation, ubiquitination and trafficking is necessary for VEGF- stimulated endothelial signaling and cell migration.