Modulation of actin microfilament dynamics and fluid phase pinocytosis by phosphorylation of heat shock protein 27.
Modulation of actin microfilament dynamics and fluid phase pinocytosis by phosphorylation of heat shock protein 27.
复制标题
DOI：
10.1016/s0021-9258(20)80512-2
复制
发表时间：
1993-11
期刊：
影响因子：
--
通讯作者：
J. Lavoie;E. Hickey;L. Weber;J. Landry
中科院分区：
文献类型：
--
作者：
J. Lavoie;E. Hickey;L. Weber;J. Landry
我们最近报道，啮齿动物成纤维细胞中热休克蛋白 27 (HSP27) 的过度表达增加了热疗过程中应力纤维的稳定性，并部分阻止了暴露于细胞松弛素 D 期间肌动蛋白的解聚（Lavoie, J.N.、Gingras-Breton, G.、Tanguay, R. M. 和 Landry, J. (1993) J. Biol. Chem. 268， 3420-3429）。由于 HSP27 是细胞受到各种生长因子和影响细胞分化的试剂刺激后磷酸化的普遍靶标，因此我们研究了 HSP27 磷酸化在调节肌动蛋白丝动力学中的作用。在这里，我们表明 HSP27 在极化成纤维细胞的前缘富集。 HSP27 定位于片状伪足和膜褶皱中，大多数肌动蛋白聚合发生在此处。我们开发了中国仓鼠细胞系，该细胞系持续过表达人类 HSP27 或该蛋白的不可磷酸化突变形式。 HSP27 的过度表达导致细胞皮层丝状肌动蛋白 (F-肌动蛋白) 浓度增加并提高胞饮活性。相反，相对于对照细胞，HSP27的不可磷酸化突变体的过度表达降低了皮质F-肌动蛋白浓度并降低了胞饮活性。成纤维细胞的有丝分裂刺激导致膜下肌动蛋白丝的快速聚合。 HSP27 增强生长因子诱导的 F-肌动蛋白积累，而突变体 HSP27 则发挥显性负作用并抑制这种对生长因子的反应。因此，HSP27 是可以调节微丝动力学的信号转导途径的一个组成部分。
We recently reported that overexpression of heat shock protein 27 (HSP27) in rodent fibroblasts increases the stability of stress fibers during hyperthermia and partially prevents actin depolymerization during exposure to cytochalasin D (Lavoie, J.N., Gingras-Breton, G., Tanguay, R. M., and Landry, J. (1993) J. Biol. Chem. 268, 3420-3429). Because HSP27 is a ubiquitous target of phosphorylation upon cell stimulation with a variety of growth factors and agents that affect cellular differentiation, we examined the role of HSP27 phosphorylation in regulating actin filament dynamics. Here we show that HSP27 is enriched at the leading edge of polarized fibroblasts. HSP27 is localized in lamellipodia and membrane ruffles where most actin polymerization occurs. We developed Chinese hamster cell lines that constitutively overexpressed either human HSP27 or a nonphosphorylatable mutant form of the protein. Overexpression of HSP27 caused an increased concentration of filamentous actin (F-actin) at the cell cortex and elevated pinocytotic activity. In contrast, overexpression of the non-phosphorylatable mutant form of HSP27 reduced cortical F-actin concentration and decreased pinocytosis activity relative to control cells. Mitogenic stimulation of fibroblasts resulted in a rapid polymerization of submembranous actin filaments. HSP27 enhanced growth factor-induced F-actin accumulation, whereas mutant HSP27 exerted a dominant negative effect and inhibited this response to growth factors. Thus, HSP27 is a component of a signal transduction pathway that can regulate microfilament dynamics.