Effects of profilin and profilactin on actin structure and function in living cells.
Effects of profilin and profilactin on actin structure and function in living cells.
复制标题
DOI：
10.1083/jcb.117.5.1023
复制
发表时间：
1992-06
期刊：
影响因子：
--
通讯作者：
Wang YL
中科院分区：
文献类型：
--
作者：
Cao LG;Babcock GG;Rubenstein PA;Wang YL
以前的研究已经产生了相互矛盾的结果，关于profilin，一个12-15-kD肌动蛋白和磷酸肌醇结合蛋白，作为肌动蛋白聚合的调节剂的生理作用。我们已经通过直接显微注射哺乳动物profilins解决了这个问题，这些profilins是从E. coli表达系统或从牛脑中，转化到活的正常大鼠肾（NRK）细胞中。荧光鬼笔环肽染色表明，显微注射导致F-肌动蛋白含量呈剂量依赖性降低，沿应力纤维的肌动蛋白和α-辅肌动蛋白沿着显著减少。此外，它对板状伪足的延伸有很强的抑制作用。然而，profilin的注射导致没有可检测的扰动的细胞-基质的焦点接触，并没有明显的解聚的丝在nonlamellipodial环带或收缩环的分裂细胞。此外，注射细胞的胞质分裂与对照细胞一样正常发生。与纯的profilin相反，来自脑的高亲和力profilin-肌动蛋白复合物诱导总细胞F-肌动蛋白含量的增加和增强的皱褶活性，表明复合物可以在细胞中容易地解离，并且可能存在多种状态的profilin，其结合或释放肌动蛋白分子的能力不同。我们的研究结果表明，profilin和profilactin可以作为有效的监管机构至少在活细胞中的肌动蛋白丝的子集。
Previous studies have yielded conflicting results concerning the physiological role of profilin, a 12-15-kD actin- and phosphoinositide- binding protein, as a regulator of actin polymerization. We have addressed this question by directly microinjecting mammalian profilins, prepared either from an E. coli expression system or from bovine brain, into living normal rat kidney (NRK) cells. The microinjection causes a dose-dependent decrease in F-actin content, as indicated by staining with fluorescent phalloidin, and a dramatic reduction of actin and alpha-actinin along stress fibers. In addition, it has a strong inhibitory effect toward the extension of lamellipodia. However, the injection of profilin causes no detectable perturbation to the cell- substrate focal contact and no apparent depolymerization of filaments in either the nonlamellipodial circumferential band or the contractile ring of dividing cells. Furthermore, cytokinesis of injected cells occurs normally as in control cells. In contrast to pure profilin, high- affinity profilin-actin complexes from brain induce an increase in total cellular F-actin content and an enhanced ruffling activity, suggesting that the complex may dissociate readily in the cell and that there may be multiple states of profilin that differ in their ability to bind or release actin molecules. Our results indicate that profilin and profilactin can function as effective regulators for at least a subset of actin filaments in living cells.