Guegan Fabien, Tatin Florence, Leste-Lasserre Thierry, Drutel Guillaume, Genot Elisabeth, Moreau Violaine
Institut Européen de Chimie-Biologie, Pessac, France.
J Cell Sci. 2008 Jun 15;121(Pt 12):2054-61. doi: 10.1242/jcs.025817. Epub 2008 May 27.
The two isoforms of p190 RhoGAP (p190A and p190B) are important regulators of RhoGTPase activity in mammalian cells. Both proteins are ubiquitously expressed, are involved in the same signalling pathways and interact with the same identified binding partners. In search of isoform functional specificity, we knocked down the expression of each p190 protein using siRNA and examined the resulting phenotypic changes in human umbilical vein endothelial cells (HUVECs). We provide evidence that p190B plays a crucial role in the regulation of MT1-MMP expression and cell-surface presentation, as well as subsequent MMP2 activation. p190B is involved in both local extracellular matrix degradation at podosomes and endothelial cell assembly into tube-like structures in Matrigel. In addition, whereas p190B knockdown does not affect podosome formation, p190A knockdown increases the number of cells showing podosome structures in HUVECs. We conclude that the two p190 RhoGAP isoforms play distinct roles in endothelial cells. In addition, our data reveal an unsuspected role for p190B in the expression of the two collaborative proteases MT1-MMP and MMP2, thereby affecting matrix remodelling and angiogenesis.
p190 RhoGAP的两种同工型（p190A和p190B）是哺乳动物细胞中RhoGTPase活性的重要调节因子。这两种蛋白质均广泛表达，参与相同的信号通路，并与相同的已鉴定结合伴侣相互作用。为了寻找同工型功能特异性，我们使用小干扰RNA（siRNA）敲低了每种p190蛋白的表达，并检测了人脐静脉内皮细胞（HUVECs）中由此产生的表型变化。我们提供的证据表明，p190B在调节MT1-MMP表达和细胞表面呈现以及随后的MMP2激活中起关键作用。p190B参与了足体处局部细胞外基质的降解以及内皮细胞在基质胶中组装成管状结构的过程。此外，虽然敲低p190B不影响足体形成，但敲低p190A会增加HUVECs中显示足体结构的细胞数量。我们得出结论，p190 RhoGAP的两种同工型在内皮细胞中发挥着不同的作用。此外，我们的数据揭示了p190B在两种协同蛋白酶MT1-MMP和MMP2表达中的意外作用，从而影响基质重塑和血管生成。
