Isolation of a fission yeast mutant that is sensitive to valproic acid and defective in the gene encoding Ric1, a putative component of Ypt/Rab-specific GEF for Ryh1 GTPase
Isolation of a fission yeast mutant that is sensitive to valproic acid and defective in the gene encoding Ric1, a putative component of Ypt/Rab-specific GEF for Ryh1 GTPase
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DOI：
10.1007/s00438-010-0550-7
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发表时间：
2010-09-01
影响因子：
3.1
通讯作者：
Kuno, Takayoshi
中科院分区：
文献类型：
--
作者：
Ma, Yan;Sugiura, Reiko;Kuno, Takayoshi
丙戊酸（VPA）引起各种治疗和生物学作用，但这些作用的确切机制仍然是难以捉摸的。为了深入了解VPA作用的分子机制，我们在裂殖酵母中进行了突变体的遗传筛选，这些突变体表现出VPA超敏反应，并确定了几种膜运输突变体，包括vas 1 -1/vps 45和vas 2 -1/aps 1。在这里，我们描述了vas 3 -1/ric 1-v3的分离和表征，ric 1（+）基因的突变等位基因编码的裂殖酵母同系物的芽殖酵母Ric 1 p，一个组成部分的Ypt/Rab-specific鸟苷酸交换因子（GEF）。Rab GTCRyh 1敲除（Delta ryh 1）细胞和Delta ric 1细胞表现出相似的表型。双敲除Delta ric 1 Delta ryh 1细胞未显示合成生长缺陷。这些结果是一致的概念，Ric 1可能是一个组成部分的全球环境基金复杂的Ryh 1。野生型Ryh 1和组成型活性Ryh 1 Q70 L的过表达仅部分抑制ric 1-v3和Delta ric 1细胞的表型，并且它们未能定位于ric 1-v3和Delta ric 1细胞中的高尔基体/内体。此外，我们分离的vps 15（+）基因，编码丝氨酸/苏氨酸蛋白激酶，作为一个剂量依赖性抑制剂的温度敏感表型的ric 1-v3突变体，但不是三角洲ric 1细胞。我们的研究结果表明，ric 1-v3突变等位基因有一些残余的功能活性，并建议Vps 15在Ric 1功能的调节中发挥作用。综上所述，Ric 1是Ryh 1的GEF的一个假定组分，并且可能受Vps 15调节。需要进一步的研究来揭示这种调节的机制。
Valproic acid (VPA) causes various therapeutic and biological effects, but the exact mechanisms underlying these effects, however, remain elusive. To gain insights into the molecular mechanisms of VPA action, we performed in fission yeast a genetic screen for mutants that show VPA hypersensitivity and have identified several membrane-trafficking mutants including vas1-1/vps45 and vas2-1/aps1. Here, we describe the isolation and characterization of vas3-1/ric1-v3, a mutant allele of the ric1 (+) gene encoding a fission yeast homolog of the budding yeast Ric1p, a component of Ypt/Rab-specific guanyl-nucleotide exchange factor (GEF). The Rab GTPase Ryh1 knockout (Delta ryh1) cells and Delta ric1 cells exhibited similar phenotypes. The double knockout Delta ric1 Delta ryh1 cells did not display synthetic growth defects. These results are consistent with the notion that Ric1 may be a component of the GEF complex for Ryh1. Overexpression of wild-type Ryh1 and the constitutively active Ryh1Q70L only partially suppressed the phenotypes of ric1-v3 and Delta ric1 cells, and they failed to localize to the Golgi/endosomes in ric1-v3 and Delta ric1 cells. Furthermore, we isolated vps15 (+) gene, encoding a serine/threonine protein kinase, as a dosage-dependent suppressor of the temperature-sensitive phenotype of ric1-v3 mutant, but not that of Delta ric1 cells. Our results showed that the ric1-v3 mutant allele has some residual functional activity and suggest that Vps15 plays a role in the regulation of Ric1 function. In conclusion, Ric1 is a putative component of GEF for Ryh1 and might be regulated by Vps15. Further studies are needed to reveal the mechanism underlying the regulation.