RHO FAMILY GTPASE-ACTIVATING PROTEINS P190, BCR AND RHOGAP SHOW DISTINCT SPECIFICITIES IN-VITRO AND IN-VIVO
RHO FAMILY GTPASE-ACTIVATING PROTEINS P190, BCR AND RHOGAP SHOW DISTINCT SPECIFICITIES IN-VITRO AND IN-VIVO
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DOI：
10.1002/j.1460-2075.1993.tb06210.x
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发表时间：
1993-12-15
期刊：
影响因子：
11.4
通讯作者：
ELLIS, C
中科院分区：
文献类型：
--
作者：
RIDLEY, AJ;SELF, AJ;ELLIS, C
rho 家族 GTP 酶将细胞外信号与细胞骨架肌动蛋白组织的变化联系起来。静止的 Swiss 3T3 成纤维细胞的血清刺激导致 rho 依赖性肌动蛋白应力纤维形成和粘着斑，同时多种生长因子启动信号通路，导致质膜上 rac 依赖性肌动蛋白聚合和膜皱褶。断点簇区基因bcr、rho GTP酶加速蛋白(rhoGAP)和rasGAP相关p190的产物共享结构相关的rho GAP结构域，并且在体外对rho家族成员具有GAP活性。我们通过体外测定和显微注射直接比较了这三种蛋白的分离的 GAP 结构域在调节不同 rho 家族 GTP 酶方面的活性，以解决它们可能的生理功能。我们发现，在体外，bcr 会加速 rac 的 GTP 酶活性，但不会促进 rho 的活性，并且在显微注射到 Swiss 3T3 成纤维细胞中后，会抑制 rac 介导的膜褶皱，但不会抑制 rho 介导的应力纤维形成。在体外，rhoGAP 对 G25K 作为底物有显着的偏好，而 p190GAP 对 rho 有显着的优先活性。此外，p190 优先抑制体内 rho 介导的应力纤维形成。我们的数据表明，p190、rhoGAP 和 bcr 在不同 rho 家族 GTPases 介导的信号通路中发挥着不同的作用。
rho family GTPases link extracellular signals to changes in the organization of cytoskeletal actin. Serum stimulation of quiescent Swiss 3T3 fibroblasts leads to rho-dependent actin stress fibre formation and focal adhesions, whilst several growth factors initiate signalling pathways leading to rac-dependent actin polymerization at the plasma membrane, and membrane ruffling. The product of the breakpoint cluster region gene bcr, rho GTPase accelerating protein (rhoGAP) and rasGAP-associated p190 share structurally related rho GAP domains, and possess GAP activity for rho family members in vitro. We have directly compared the activities of the isolated GAP domains of these three proteins in regulating different rho family GTPases, both by in vitro assays and by microinjection, to address their possible physiologic functions. We show that bcr accelerates the GTPase activity of rac, but not rho in vitro, and inhibits rac-mediated membrane ruffling, but not rho-mediated stress fibre formation, after microinjection into Swiss 3T3 fibroblasts. In vitro, rhoGAP has a striking preference for G25K as a substrate, whilst p190GAP has marked preferential activity for rho. Furthermore, p190 preferentially inhibits rho-mediated stress fibre formation in vivo. Our data suggest that p190, rhoGAP and bcr play distinct roles in signalling pathways mediated through different rho family GTPases.