Mittar Shweta, Ulyatt Clare, Howell Gareth J, Bruns Alexander F, Zachary Ian, Walker John H, Ponnambalam Sreenivasan
Endothelial Cell Biology Unit, Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Clarendon Way, Leeds LS29JT, UK.
Exp Cell Res. 2009 Mar 10;315(5):877-89. doi: 10.1016/j.yexcr.2008.12.020. Epub 2009 Jan 6.
Vascular endothelial growth factor receptor 1 (VEGFR1) is an essential receptor tyrosine kinase that regulates mammalian vascular development and embryogenesis but its function is not well understood. Herein, we present evidence whereby endothelial VEGFR1 is largely resident within the Golgi apparatus but translocates to the plasma membrane via a calcium-regulated process. Primary human endothelial cells reveal differing VEGFR1 and VEGFR2 intracellular distribution and dynamics. The major proportion of the full-length VEGFR1 membrane protein was resident within the Golgi apparatus in primary endothelial cells. Whereas VEGFR2 displayed down-regulation in response to VEGF-A, VEGFR1 was not significantly affected arguing for a significant intracellular pool that was inaccessible to extracellular VEGF-A. This intracellular VEGFR1 pool showed significant co-distribution with key Golgi residents. Brefeldin A caused VEGFR1 Golgi fragmentation consistent with redistribution to the endoplasmic reticulum. Metabolic labeling experiments and microscopy using domain-specific VEGFR1 antibodies indicated that the mature processed VEGFR1 species and an integral membrane protein was resident within Golgi apparatus. Cytosolic calcium ions play a key role in VEGFR1 trafficking as treatment with either VEGF-A, histamine, thrombin, thapsigargin or A23187 ionophore caused VEGFR1 redistribution from the Golgi apparatus to small punctate vesicles and plasma membrane. We thus propose a model whereby the balance of VEGFR1 and VEGFR2 plasma membrane levels dictate either negative or positive endothelial signaling to influence vascular physiology.
血管内皮生长因子受体1（VEGFR1）是一种重要的受体酪氨酸激酶，它调节哺乳动物的血管发育和胚胎发生，但其功能尚未完全明确。在此，我们提供证据表明，内皮细胞中的VEGFR1主要定位于高尔基体，但通过钙调节过程转运至质膜。原代人内皮细胞显示出不同的VEGFR1和VEGFR2细胞内分布及动态变化。在原代内皮细胞中，全长VEGFR1膜蛋白的主要部分定位于高尔基体。VEGFR2在VEGF - A刺激下表现出下调，而VEGFR1未受显著影响，这表明存在一个细胞内池，细胞外的VEGF - A无法作用于此。这个细胞内VEGFR1池与高尔基体的关键驻留蛋白有显著的共分布。布雷菲德菌素A导致VEGFR1高尔基体碎片化，这与重新分布到内质网一致。代谢标记实验和使用结构域特异性VEGFR1抗体的显微镜观察表明，成熟加工后的VEGFR1物种和一种整合膜蛋白定位于高尔基体。胞质钙离子在VEGFR1的转运中起关键作用，因为用VEGF - A、组胺、凝血酶、毒胡萝卜素或A23187离子载体处理会导致VEGFR1从高尔基体重新分布到小的点状囊泡和质膜。因此，我们提出一个模型，即VEGFR1和VEGFR2质膜水平的平衡决定了内皮细胞的负向或正向信号传导，从而影响血管生理功能。
