Wnt5a signaling controls cytokinesis by correctly positioning ESCRT-III at the midbody
Wnt5a signaling controls cytokinesis by correctly positioning ESCRT-III at the midbody
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DOI：
10.1242/jcs.108142
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发表时间：
2012-10-15
影响因子：
4
通讯作者：
Kikuchi, Akira
中科院分区：
文献类型：
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作者：
Fumoto, Katsumi;Kikuchi, Koji;Kikuchi, Akira
WNTs至少激活两条信号通路，即β-连环蛋白依赖通路和非依赖通路。虽然已知b-连环蛋白依赖的途径有助于G1-S的转变，但β-连环蛋白非依赖途径在细胞周期调控中的作用尚不清楚。在这里，我们证明了Wnt5a信号是胞质分裂所必需的，它激活了β-连环蛋白非依赖性途径。Wnt信号通路的中介体Dishevelled2(Dvl2)定位于胞质分裂的中体。除了Dvl2的定位外，Wnt受体Fz2还与转运III(ESCRT-III)亚单位所需的内体分选复合体CHMP4B一起在中体中被检测到。Wnt5a及其受体的缺失和DVL的缺失增加了多核。在Wnt5a缺失的细胞中观察到的表型可以通过添加纯化的Wnt5a而不是Wnt3a来拯救，Wnt3a是β-连环蛋白依赖途径的配体。此外，Wnt5a信号的缺失导致稳定的微管丢失和CHMP4B在中体的错误定位，从而影响脱落。抑制微管在中体的稳定导致CHMP4B定位错误，而CHMP4B的耗尽不影响微管的稳定，提示CHMP4B的正确定位依赖于微管。Fz2以Rab11依赖的方式定位于中体，可能沿着稳定的微管。在Wnt5a刺激下，Fz2与CHMP4B形成复合体，CHMP4B在中体正确定位是必需的，而CHMP4B对Fz2的定位不是必需的。这些结果表明，WNT5a信号通过稳定中体微管，将ESCRT-III正确地定位在中体，以便于脱落。
Wnts activate at least two signaling pathways, the beta-catenin-dependent and -independent pathways. Although the b-catenin-dependent pathway is known to contribute to G1-S transition, involvement of the beta-catenin-independent pathway in cell cycle regulation remains unclear. Here, we show that Wnt5a signaling, which activates the beta-catenin-independent pathway, is required for cytokinesis. Dishevelled 2 (Dvl2), a mediator of Wnt signaling pathways, was localized to the midbody during cytokinesis. Beside the localization of Dvl2, Fz2, a Wnt receptor, was detected in the midbody with the endosomal sorting complex required for transport III (ESCRT-III) subunit, CHMP4B. Depletion of Wnt5a, its receptors, and Dvl increased multinucleation. The phenotype observed in Wnt5a-depleted cells was rescued by the addition of purified Wnt5a but not Wnt3a, which is a ligand for the beta-catenin-dependent pathway. Moreover, depletion of Wnt5a signaling caused loss of stabilized microtubules and mislocalization of CHMP4B at the midbody, which affected abscission. Inhibition of the stabilization of microtubules at the midbody led to the mislocalization of CHMP4B, while depletion of CHMP4B did not affect the stabilization of microtubules, suggesting that the correct localization of CHMP4B depends on microtubules. Fz2 was localized to the midbody in a Rab11-dependent manner, probably along stabilized microtubules. Fz2 formed a complex with CHMP4B upon Wnt5a stimulation and was required for proper localization of CHMP4B at the midbody, while CHMP4B was not necessary for the localization of Fz2. These results suggest that Wnt5a signaling positions ESCRT-III in the midbody properly for abscission by stabilizing midbody microtubules.