F-BAR Cdc15 Promotes Cdc42 Activation During Cytokinesis and Cell Polarization in Schizosaccharomyces pombe
F-BAR Cdc15 Promotes Cdc42 Activation During Cytokinesis and Cell Polarization in Schizosaccharomyces pombe
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DOI：
10.1534/genetics.119.302649
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发表时间：
2019-12-01
期刊：
影响因子：
3.3
通讯作者：
Das, Maitreyi E.
中科院分区：
文献类型：
--
作者：
Hercyk, Brian S.;Das, Maitreyi E.
Cdc42 是一种 Rho 家族 GTP 酶，是细胞极性的主要调节因子。最近，研究表明，Cdc42 还可以促进裂殖酵母裂殖酵母中正确的胞质分裂。 Cdc42 由两个部分冗余的 GEF（Gef1 和 Scd1）激活。尽管两种 GEF 都会激活 Cdc42，但它们的缺失突变体表现出不同的表型，表明它们受到未知机制的差异调节。在胞质分裂期间，Gef1 定位于分裂位点并激活 Cdc42 以启动环收缩和隔膜进入。在这里，我们报告 F-BAR 蛋白 Cdc15 促进 Gef1 定位到其功能位点。我们发现 cdc15 促进 Gef1 与皮质点在初始分裂位点的结合，从而在环组装过程中激活 Cdc42。此外，cdc15 磷酸化突变体的表型与 gef1 突变体的极性表型相似。在超形态 cdc15 突变体中，Gef1 提前定位到分裂位点，并且很容易在皮质斑块和细胞皮质处检测到。相应地，超态 cdc15 突变体在分裂间期显示出双极性增加，并在胞质分裂期间在分裂位点显示出早熟的 Cdc42 激活。最后，超态 cdc15 突变体中 gef1 的缺失消除了增加的双极性和早熟的 Cdc42 激活表型。我们没有看到其他 GEF Scd1 以 Cdc15 依赖方式的定位发生任何变化。我们的数据表明，Cdc15 促进细胞皮质胞质分裂期间分裂位点的 Cdc42 激活，从而促进双极性，这是通过促进 Gef1 定位到这些位点来介导的。
Cdc42, a Rho-family GTPase, is a master regulator of cell polarity. Recently, it has been shown that Cdc42 also facilitates proper cytokinesis in the fission yeast Schizosaccharomyces pombe. Cdc42 is activated by two partially redundant GEFs, Gef1 and Scd1. Although both GEFs activate Cdc42, their deletion mutants display distinct phenotypes, indicating that they are differentially regulated by an unknown mechanism. During cytokinesis, Gef1 localizes to the division site and activates Cdc42 to initiate ring constriction and septum ingression. Here, we report that the F-BAR protein Cdc15 promotes Gef1 localization to its functional sites. We show that cdc15 promotes Gef1 association with cortical puncta at the incipient division site to activate Cdc42 during ring assembly. Moreover, cdc15 phospho-mutants phenocopy the polarity phenotypes of gef1 mutants. In a hypermorphic cdc15 mutant, Gef1 localizes precociously to the division site and is readily detected at the cortical patches and the cell cortex. Correspondingly, the hypermorphic cdc15 mutant shows increased bipolarity during interphase and precocious Cdc42 activation at the division site during cytokinesis. Finally, loss of gef1 in hypermorphic cdc15 mutants abrogates the increased bipolarity and precocious Cdc42 activation phenotype. We did not see any change in the localization of the other GEF Scd1 in a Cdc15-dependent manner. Our data indicate that Cdc15 facilitates Cdc42 activation at the division site during cytokinesis at the cell cortex to promote bipolarity and this is mediated by promoting Gef1 localization to these sites.