The cell wall sensor Wsc1p is involved in reorganization of actin cytoskeleton in response to hypo-osmotic shock in Saccharomyces cerevisiae
The cell wall sensor Wsc1p is involved in reorganization of actin cytoskeleton in response to hypo-osmotic shock in Saccharomyces cerevisiae
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作者：
Gualtieri, T;Ragni, E;Popolo, L
细胞壁对于保持酵母细胞的渗透完整性是必不可少的。细胞壁突变体的一些表型性状表明，作为细胞壁弱化的结果，产生了低渗胁迫样条件。细胞壁的连续扩张和质膜的拉伸触发复杂的反应以防止细胞裂解。在这项工作中，我们研究了两个条件，产生细胞壁和膜应力：一个是由细胞壁突变体gas 1Delta和其他低渗休克。我们研究了肌动蛋白细胞骨架和细胞壁传感器Wsc 1 p和Mid 2 p在这些应力条件下的作用。在缺乏β（1，3）-葡糖基转移酶活性的gas 1无效突变细胞中，肌动蛋白细胞骨架出现明显的去极化，而在低渗休克中，野生型细胞的肌动蛋白细胞骨架出现短暂的去极化。去极化细胞的百分比在移位后30分钟达到最大，然后逐渐下降，直到细胞达到一个新的稳态条件。最大响应与给定渗透压范围内偏移前后外部渗透压的差异大小成比例。Wsc 1 p的缺失特异性地延迟了肌动蛋白细胞骨架的复极化，而Wsc 1 p和Mid 2 p对于维持gas 1 Delta细胞的细胞完整性至关重要。肌动蛋白细胞骨架的控制是对细胞壁弱化的补偿反应的重要因素。在细胞壁扩张和膜拉伸的条件下，Wsc 1 p似乎是肌动蛋白网络重排的重要调节因子。版权所有（C）2004约翰威利父子有限公司。
The cell wall is essential to preserve osmotic integrity of yeast cells. Some phenotypic traits of cell wall mutants suggest that, as a result of a weakening of the cell wall, hypo-osmotic stress-like conditions are created. Consequent expansion of the cell wall and stretching of the plasma membrane trigger a complex response to prevent cell lysis. In this work we examined two conditions that generate a cell wall and membrane stress: one is represented by the cell wall mutant gas1Delta and the other by a hypo-osmotic shock. We examined the actin cytoskeleton and the role of the cell wall sensors Wsc1p and Mid2p in these stress conditions. In the gas1 null mutant cells, which lack a beta(1,3)-glucanosyltransferase activity required for cell wall assembly, a constitutive marked depolarization of actin cytoskeleton was found. In a hypo-osmotic shock wild-type cells showed a transient depolarization of actin cytoskeleton. The percentage of depolarized cells was maximal at 30 min after the shift and then progressively decreased until cells reached a new steady-state condition. The maximal response was proportional to the magnitude of the difference in the external osmolarity before and after the shift within a given range of osmolarities. Loss of Wsc1p specifically delayed the repolarization of the actin cytoskeleton, whereas Wsc1p and Mid2p were essential for the maintenance of cell integrity in gas1Delta cells. The control of actin cytoskeleton is an important element in the context of the compensatory response to cell wall weakening. Wsc1p appears to be an important regulator of the actin network rearrangements in conditions of cell wall expansion and membrane stretching. Copyright (C) 2004 John Wiley Sons, Ltd.