Cell type-specific regulation of RhoA activity during cytokinesis
Cell type-specific regulation of RhoA activity during cytokinesis
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DOI：
10.1074/jbc.m402292200
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发表时间：
2004-10-22
影响因子：
4.8
通讯作者：
Matsuda, M
中科院分区：
文献类型：
--
作者：
Yoshizaki, H;Ohba, Y;Matsuda, M
Rho家族gtpase在细胞分裂中起关键作用。利用基于荧光共振能量转移（FRET）原理的探针，我们发现在HeLa细胞中，RhoA活性随着细胞分裂的进展而增加。在Rat1A细胞中，RhoA活性在大部分细胞质分裂过程中仍然被抑制。与这一观察结果一致的是，C3毒素的表达在HeLa细胞中抑制了细胞分裂，而在Rat1A细胞中没有。此外，Ect2显性负突变体（Rho GEF）或Y-27632 （Rho依赖性激酶ROCK的抑制剂）的表达抑制了HeLa细胞的细胞分裂，但在Rat1A细胞中没有。与RhoA活性相反，在HeLa和Rat1A细胞中，Rac1活性在细胞分裂过程中被抑制，在子细胞脱落前在极性侧质膜上开始增加。这种类型的Rac1抑制被证明是细胞分裂所必需的，因为Rac1的组成型活性突变在HeLa和Rat1A细胞中诱导了多核表型。此外，MgcRacGAP/CYK-4参与了细胞分裂过程中Rac1的抑制，这通过使用显性阴性突变体得到了证实。由于肌球蛋白轻链激酶抑制剂ML-7延缓了Rat1A细胞的胞质分裂，而已知Rac1效应物Pak可抑制肌球蛋白轻链激酶，因此MgcRacGAP对Rac1-Pak通路的抑制可能在Rat1A细胞的胞质分裂中起关键作用。
Rho family GTPases play pivotal roles in cytokinesis. By using probes based on the principle of fluorescence resonance energy transfer (FRET), we have shown that in HeLa cells RhoA activity increases with the progression of cytokinesis. Here we show that in Rat1A cells RhoA activity remained suppressed during most of the cytokinesis. Consistent with this observation, the expression of C3 toxin inhibited cytokinesis in HeLa cells but not in Rat1A cells. Furthermore, the expression of a dominant negative mutant of Ect2, a Rho GEF, or Y-27632, an inhibitor of the Rho-dependent kinase ROCK, inhibited cytokinesis in HeLa cells but not in Rat1A cells. In contrast to the activity of RhoA, the activity of Rac1 was suppressed during cytokinesis and started increasing at the plasma membrane of polar sides before the abscission of the daughter cells in both HeLa and Rat1A cells. This type of Rac1 suppression was shown to be essential for cytokinesis because a constitutively active mutant of Rac1 induced a multinucleated phenotype in both HeLa and Rat1A cells. Moreover, the involvement of MgcRacGAP/CYK-4 in this suppression of Rac1 during cytokinesis was shown by the use of a dominant negative mutant. Because ML-7, an inhibitor of myosin light chain kinase, delayed the cytokinesis of Rat1A cells and because Pak, a Rac1 effector, is known to suppress myosin light chain kinase, the suppression of the Rac1-Pak pathway by MgcRacGAP may play a pivotal role in the cytokinesis of Rat1A cells.