Nakano Kentaro, Imai Jun, Arai Ritsuko, Toh-E Akio, Matsui Yasushi, Mabuchi Issei
Division of Biology, Department of Life Sciences, Graduate Program of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan.
J Cell Sci. 2002 Dec 1;115(Pt 23):4629-39. doi: 10.1242/jcs.00150.
We identified a novel Rho gene rho3(+) and studied its interaction with diaphanous/formin for3(+) in the fission yeast Schizosaccharomyces pombe. Both rho3 null cells and for3 null cells showed defects in organization of not only actin cytoskeleton but also cytoplasmic microtubules (MTs). rho3 for3 double null cells had defects that were more severe than each single null cell: polarized growth was deficient in the double null cells. Function of For3 needed the highly conserved FH1 and FH2 domains, an N-terminal region containing a Rho-binding domain, and the C-terminal region. For3 bound to active forms of both Rho3 and Cdc42 but not to that of Rho1. For3 was localized as dots to the ends of interphase cells and to the mid-region in dividing cells. This localization was probably dependent on its interaction with Rho proteins. Overexpression of For3 produced huge swollen cells containing depolarized F-actin patches and thick cytoplasmic MT bundles. In addition, overexpression of a constitutively active Rho3Q71L induced a strong defect in cytokinesis. In conclusion, we propose that the Rho3-For3 signaling system functions in the polarized cell growth of fission yeast by controlling both actin cytoskeleton and MTs.
我们鉴定出一个新的Rho基因rho3(+)，并研究了其在裂殖酵母粟酒裂殖酵母中与diaphanous/formin for3(+)的相互作用。rho3基因敲除细胞和for3基因敲除细胞不仅在肌动蛋白细胞骨架的组织上存在缺陷，在细胞质微管（MTs）的组织上也存在缺陷。rho3 for3双基因敲除细胞的缺陷比每个单基因敲除细胞更严重：双基因敲除细胞的极性生长存在缺陷。For3的功能需要高度保守的FH1和FH2结构域、一个包含Rho结合结构域的N端区域以及C端区域。For3与Rho3和Cdc42的活性形式结合，但不与Rho1的活性形式结合。For3定位于间期细胞的末端以及分裂细胞的中间区域，呈点状分布。这种定位可能依赖于其与Rho蛋白的相互作用。For3的过表达产生了巨大的肿胀细胞，其中含有去极化的F-肌动蛋白斑块和粗大的细胞质微管束。此外，组成型活性Rho3Q71L的过表达在胞质分裂中诱导了严重缺陷。总之，我们提出Rho3-For3信号系统通过控制肌动蛋白细胞骨架和微管在裂殖酵母的极性细胞生长中发挥作用。
