Vav2 is required for cell spreading.
Vav2 is required for cell spreading.
复制标题
VAV2是细胞扩散所必需的。
DOI：
10.1083/jcb.200103134
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发表时间：
2001-07-09
影响因子：
7.8
通讯作者：
Carpenter, C L
中科院分区：
文献类型：
--
作者：
Marignani, P A;Carpenter, C L
Vav2是广泛表达的Rho家族鸟嘌呤核苷酸交换因子，与Vav1和Vav3高度同源。 Vav2 的激活版本正在发生转变，但 Vav2 的正常功能及其调节方式尚不清楚。我们研究了体内调节 Vav2 交换活性的途径并表征了其功能。通过直接测量 Rac-GTP 和细胞形态来评估，Vav2 的过度表达会激活 Rac。 Vav2 还催化 RhoA 的交换，但不会引起表明 RhoA 激活的形态变化。 Vav2 核苷酸交换在体内是 Src 依赖性的，因为 Vav2 和显性失活 Src 的共表达，或用 Src 抑制剂 PP2 处理，会阻断 Vav2 依赖性 Rac 激活和片状伪足形成。 pleckstrin 同源 (PH) 结构域的突变消除了交换活性，并且该构建体不会诱导板状伪足，表明 PH 结构域对于催化核苷酸交换是必需的。为了进一步研究 Vav2 的功能，我们对 dbl 同源 (DH) 结构域进行了突变，并询问该突变体是否会作为显性失活来阻断 Rac 依赖性事件。使用该突变体的研究表明，Vav2 对于血小板衍生生长因子或表皮生长因子依赖性 Rac 激活不是必需的。 Vav2 DH 突变体确实作为显性失活抑制 NIH3T3 细胞在纤连蛋白上的扩散，特别是通过阻断片状伪足的形成。这些发现表明，在成纤维细胞中，Vav2 对于整合素是必需的，但不是生长因子依赖性 Rac 激活导致板状伪足所必需的。
Vav2 is a widely expressed Rho family guanine nucleotide exchange factor highly homologous to Vav1 and Vav3. Activated versions of Vav2 are transforming, but the normal function of Vav2 and how it is regulated are not known. We investigated the pathways that regulate Vav2 exchange activity in vivo and characterized its function. Overexpression of Vav2 activates Rac as assessed by both direct measurement of Rac-GTP and cell morphology. Vav2 also catalyzes exchange for RhoA, but does not cause morphologic changes indicative of RhoA activation. Vav2 nucleotide exchange is Src-dependent in vivo, since the coexpression of Vav2 and dominant negative Src, or treatment with the Src inhibitor PP2, blocks both Vav2-dependent Rac activation and lamellipodia formation. A mutation in the pleckstrin homology (PH) domain eliminates exchange activity and this construct does not induce lamellipodia, indicating the PH domain is necessary to catalyze nucleotide exchange. To further investigate the function of Vav2, we mutated the dbl homology (DH) domain and asked whether this mutant would function as a dominant negative to block Rac-dependent events. Studies using this mutant indicate that Vav2 is not necessary for platelet-derived growth factor– or epidermal growth factor–dependent activation of Rac. The Vav2 DH mutant did act as a dominant negative to inhibit spreading of NIH3T3 cells on fibronectin, specifically by blocking lamellipodia formation. These findings indicate that in fibroblasts Vav2 is necessary for integrin, but not growth factor–dependent activation of Rac leading to lamellipodia.