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首页> 外文期刊>Cell motility and the cytoskeleton >Intracellular pH modulation of ADF/cofilin proteins.
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Intracellular pH modulation of ADF/cofilin proteins.

机译：ADF / cofilin蛋白的细胞内pH调节。

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The ADF/cofilin (AC) proteins are necessary for the high rates of actin filament turnover seen in vivo. Their regulation is complex enough to underlie the precision in filament dynamics needed by stimulated cells. Disassembly of actin by AC proteins is inhibited in vitro by phosphorylation of ser3 and pH<7.1. This study of Swiss 3T3 cells demonstrates that pH also affects AC behavior in vivo: (1) Wounded cells show pH-dependent AC translocation to alkaline-induced ruffling membrane; (2) The Triton extractable (soluble) ADF from Swiss 3T3 cells decreases from 42+/-4% to 23+/-4% when the intracellular pH (pH(i)) is reduced from 7.4 to 6.6; (3) Covariance and colocalization analyses of immunostained endogenous proteins show that ADF partitions more with monomeric actin and less with polymeric actin when pH(i) increases. However, the distribution of cofilin, a less pH-sensitive AC in vitro, does not change with pH; (4) Only the unphosphorylatable AC mutant (A3), when overexpressed as a GFP chimera, uniquely produces aberrant cellular phenotypes and only if the pH is shifted from 7.1 to 6.6 or 7.4. A mechanism is proposed that explains why AC(A3)-GFP and AC(wt)-GFP chimeras generate different phenotypes in response to pH changes. Phospho-AC levels increase with cell density, and in motile cells, phospho-AC increases with alkalization, suggesting a homeostatic mechanism that compensates for increased AC activity and filament turnover. These results show that the behavior of AC proteins with pH-sensitivity in vitro is affected by pH in vivo. Copyright 2000 Wiley-Liss, Inc.
机译：ADF / cofilin（AC）蛋白对于体内可见的肌动蛋白丝更新率很高是必需的。它们的调节非常复杂，足以支撑受刺激细胞所需的细丝动力学精度。在体外，AC3蛋白的磷酸化和pH <7.1抑制了AC蛋白对肌动蛋白的分解。对Swiss 3T3细胞的这项研究表明，pH值还会影响体内的AC行为：（1）受伤的细胞显示出pH依赖性的AC易位至碱性诱导的波纹膜; （2）当细胞内pH（pH（i））从7.4降低到6.6时，来自Swiss 3T3细胞的Triton可提取（可溶性）ADF从42 +/- 4％降低到23 +/- 4％; （3）免疫染色的内源蛋白的协方差和共定位分析表明，当pH（i）增加时，ADF与单体肌动蛋白的分配更多，而与高分子肌动蛋白的分配更少。但是，cofilin（一种对pH不太敏感的体外AC）的分布不会随着pH的变化而变化。 （4）仅当不可磷酸化的AC突变体（A3）作为GFP嵌合体过度表达时，且仅当pH从7.1变为6.6或7.4时，才会独特地产生异常的细胞表型。提出了一种机制，解释了为什么AC（A3）-GFP和AC（wt）-GFP嵌合体会响应pH值变化而产生不同的表型。磷酸-AC水平随细胞密度增加而增加，而在运动细胞中，磷酸-AC随着碱化而增加，这表明体内平衡机制可以补偿增加的AC活性和细丝周转。这些结果表明，体外具有pH敏感性的AC蛋白的行为受到体内pH的影响。版权所有2000 Wiley-Liss，Inc.

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