Effects of CapG overexpression on agonist-induced motility and second messenger generation.
Effects of CapG overexpression on agonist-induced motility and second messenger generation.
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DOI：
10.1083/jcb.129.1.147
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发表时间：
1995-04
期刊：
影响因子：
--
通讯作者：
Yin HL
中科院分区：
文献类型：
--
作者：
Sun HQ;Kwiatkowska K;Wooten DC;Yin HL
肌动蛋白调节蛋白与多聚磷脂酰肌醇结合，如磷脂酰肌醇4，5-二磷酸(PIP2)，可以通过重构膜细胞骨架和通过磷脂酰肌醇循环调节第二信使的产生来潜在地参与受体信号转导。我们通过过度表达明胶蛋白家族的肌动蛋白细丝末端封端蛋白CAPG、钙(2+)和多磷肌醇结合蛋白来研究这些可能性。高水平的瞬时过表达减少了细胞中心的肌动蛋白细丝染色，而不是细胞外围的肌动蛋白细丝染色。在克隆选择的细胞系中适度过表达对肌动蛋白细丝的含量或组织没有明显的影响。然而，它促进了伤口愈合率和趋化性的剂量依赖性增加。运动表型类似于明胶蛋白的过度表达，除了封端外，还切断和核化肌动蛋白细丝。与对照组相比，CAPG高表达克隆对血小板衍生生长因子的反应更强。它们形成更多的圆形背膜褶皱，具有更高的磷脂酰肌醇转换率、1，4，5-三磷酸肌醇的生成和钙信号转导。这些反应与增强的PLC伽马活性是一致的。对PIP2质量的直接测量表明，CAPG对PLC伽马的影响主要不是由于PIP2底物浓度的增加。观察到的细胞运动和膜信号的变化与PIP(2)结合的肌动蛋白调节蛋白在体内调节肌醇磷脂周转和第二信使生成的假说一致。我们推测，在细胞刺激后，CAPG和相关蛋白能够协调膜信号和肌动蛋白细丝的动态变化。
Actin modulating proteins that bind polyphosphoinositides, such as phosphatidylinositol 4, 5-bisphosphate (PIP2), can potentially participate in receptor signaling by restructuring the membrane cytoskeleton and modulating second messenger generation through the phosphoinositide cycle. We examined these possibilities by overexpressing CapG, an actin filament end capping, Ca(2+)- and polyphosphoinositide-binding protein of the gelsolin family. High level transient overexpression decreased actin filament staining in the center of the cells but not in the cell periphery. Moderate overexpression in clonally selected cell lines did not have a detectible effect on actin filament content or organization. Nevertheless, it promoted a dose-dependent increase in rates of wound healing and chemotaxis. The motile phenotype was similar to that observed with gelsolin overexpression, which in addition to capping, also severs and nucleates actin filaments. CapG overexpressing clones are more responsive to platelet-derived growth factor than control- transfected clones. They form more circular dorsal membrane ruffles, have higher phosphoinositide turnover, inositol 1,4,5-trisphosphate generation and Ca2+ signaling. These responses are consistent with enhanced PLC gamma activity. Direct measurements of PIP2 mass showed that the CapG effect on PLC gamma was not due primarily to an increase in the PIP2 substrate concentration. The observed changes in cell motility and membrane signaling are consistent with the hypothesis that PIP(2)-binding actin regulatory proteins modulate phosphoinositide turnover and second messenger generation in vivo. We infer that CapG and related proteins are poised to coordinate membrane signaling with actin filament dynamics following cell stimulation.