Rho-kinase phosphorylates PAR-3 and disrupts PAR complex formation
Rho-kinase phosphorylates PAR-3 and disrupts PAR complex formation
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DOI：
10.1016/j.devcel.2007.11.021
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发表时间：
2008-02-01
影响因子：
11.8
通讯作者：
Kaibuchi, Kozo
中科院分区：
文献类型：
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作者：
Nakayama, Masanori;Goto, Takaaki M.;Kaibuchi, Kozo
PAR-3、PAR-6和非典型蛋白激酶C（aPKC）的极性复合物在各种细胞极化事件中起作用。PAR-3直接与Tiam 1/Taim 2（STEF），Rac 1特异性鸟嘌呤核苷酸交换因子相互作用，并与aPKC-PAR-6-Cdc42.GTP形成复合物，导致Rac 1活化。RhoA在某些类型的细胞中拮抗Rac 1。然而，RhoA和PAR复合物之间的关系仍然难以捉摸。我们发现RhoA的效应子Rho-激酶/ROCK/ROK在Thr 833磷酸化PAR-3，从而破坏其与aPKC和PAR-6的相互作用，但不与Tiam 2相互作用。磷酸化的PAR-3中观察到的前沿，并在迁移细胞的中心和后部具有前后极性。小干扰RNA（siRNA）敲低PAR-3会损害细胞迁移、前后极化和PAR-3介导的Rac 1激活，这些都可以在siRNA抗性PAR-3中恢复，但在磷酸化模拟PAR-3突变体中没有恢复。我们建议RhoA/Rho激酶通过PAR-3磷酸化抑制PAR复合物的形成，导致Rac 1失活。
A polarity complex of PAR-3, PAR-6, and atypical protein kinase C (aPKC) functions in various cell polarization events. PAR-3 directly interacts with Tiam1/Taim2 (STEF), Rac1-specific guanine nucleotide exchange factors, and forms a complex with aPKC-PAR-6-Cdc42.GTP, leading to Rac1 activation. RhoA antagonizes Rac1 in certain types of cells. However, the relationship between RhoA and the PAR complex remains elusive. We found here that Rho-kinase/ROCK/ROK, the effector of RhoA, phosphorylated PAR-3 at Thr833 and thereby disrupted its interaction with aPKC and PAR-6, but not with Tiam2. Phosphorylated PAR-3 was observed in the leading edge, and in central and rear portions of migrating cells having front-rear polarity. Knockdown of PAR-3 by small interfering RNA (siRNA) impaired cell migration, front-rear polarization, and PAR-3-mediated Rac1 activation, which were recovered with siRNA-resistant PAR-3, but not with the phospho-mimic PAR-3 mutant. We propose that RhoA/ Rho-kinase inhibits PAR complex formation through PAR-3 phosphorylation, resulting in Rac1 inactivation.