Negative regulation of mitosis in fission yeast by the Shk1-interacting protein Skb1 and its human homolog, Skb1Hs
Negative regulation of mitosis in fission yeast by the Shk1-interacting protein Skb1 and its human homolog, Skb1Hs
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DOI：
10.1073/pnas.95.25.14781
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发表时间：
1998-12-08
影响因子：
11.1
通讯作者：
Marcus, S
中科院分区：
文献类型：
--
作者：
Gilbreth, M;Yang, PR;Marcus, S
我们先前提供的证据表明，高度保守的skb1基因编码的蛋白是裂殖酵母裂殖酵母中p21(CDC42/RAC)激活的激酶(PAR)同源物Shk1的潜在调节因子。Skb1缺失突变体具有交配能力，但与野生型S.pombe细胞相比伸长较小，而过度表达skb1的细胞则超长。这些表型表明Skb1可能作为有丝分裂抑制物发挥作用。在这里，我们展示了在S.pombe中skb1和shk1与编码关键有丝分裂调节因子的基因的遗传相互作用。我们的结果表明，Skb1负性调节有丝分裂的机制不依赖于CDc2激活的磷酸酶CDC25，但至少部分依赖于Shk1和CDc2抑制激酶Wee1。我们为S.pombe中Skb1和Shk1与CDc2的关联提供了生化证据，表明Skb1和Shk1通过与CDc2复合体相互作用而不是通过间接机制抑制有丝分裂。这些结果提供了PAR相关蛋白激酶作为有丝分裂抑制物以前未被描述的作用的证据。我们还克隆了一个skb1的人类同源物SKB1Hs，并表明它可以在功能上取代S.pombe中的skb1。因此，Skb1相关蛋白的分子功能可能在进化过程中基本上是保守的。
We previously provided evidence that the protein encoded by the highly conserved skb1 gene is a putative regulator of Shk1, a p21(Cdc42/Rac)-activated kinase (PAR) homolog in the fission yeast Schizosaccharomyces pombe. skb1 null mutants are viable and competent for mating but less elongate than wild-type S. pombe cells, whereas cells that overexpress skb1 are hyperelongated. These phenotypes suggest a possible role for Skb1 as a mitotic inhibitor. Here we show genetic interactions of both skb1 and shk1 with genes encoding key mitotic regulators in S. pombe. Our results indicate that Skb1 negatively regulates mitosis by a mechanism that is independent of the Cdc2-activating phosphatase Cdc25 but that is at least partially dependent on Shk1 and the Cdc2 inhibitory kinase Wee1. We provide biochemical evidence for association of Skb1 and Shk1 with Cdc2 in S. pombe, suggesting that Skb1 and Shk1 inhibit mitosis through interaction with the Cdc2 complex, rather than by an indirect mechanism. These results provide evidence of a previously undescribed role for PAR-related protein kinases as mitotic inhibitors. We also describe the cloning of a human homolog of skb1, SKB1Hs, and show that it can functionally replace skb1 in S. pombe. Thus, the molecular functions of Skb1-related proteins have likely been substantially conserved through evolution.