Raymond and Beverly Sacker Laboratory of Genetics and Molecular Medicine, Department of Genetics and Developmental Biology and Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT 06030, USA.
Mol Cell. 2009 Nov 13;36(3):525-35. doi: 10.1016/j.molcel.2009.10.025.
Modulation of actin dynamics through the N-WASp/Arp2/3 pathway is important in cell locomotion, membrane trafficking, and pathogen infection. Here, we demonstrate that Nck is essential for actin remodeling stimulated by phosphatidylinositol 4,5 bisphosphate (PI(4,5)P(2)) and, conversely, that PI(4,5)P(2) is necessary for localized actin polymerization induced by Nck in vivo. Nck knockdown or knockout suppressed actin comets induced by phosphatidylinositol 5-kinase (PIP5K), and PIP5K stimulated tyrosine phosphorylation of an Nck SH2 domain binding partner, suggesting that Nck couples phosphotyrosine- and phosphoinositide-dependent signals. We show that PI(4,5)P(2) and PIP5K are both enriched at actin comets induced by Nck aggregates and that formation of actin comets was strongly inhibited by coclustering with an inositol 5-phosphatase domain to decrease local PI(4,5)P(2) levels. The extent of Nck-induced actin polymerization was also modulated by PI(4,5)P(2)-sensitive N-WASp mutants. This study uncovers a strong reciprocal interdependence between Nck and PI(4,5)P(2) in promoting localized N-WASp-mediated actin polymerization in cells.
通过 N-WASp/Arp2/3 途径调节肌动蛋白动力学对于细胞运动、膜运输和病原体感染非常重要。在这里，我们证明 Nck 对于由磷脂酰肌醇 4,5 二磷酸（PI(4,5)P(2)）刺激的肌动蛋白重塑是必不可少的，相反，PI(4,5)P(2)对于 Nck 在体内诱导的局部肌动蛋白聚合是必需的。Nck 敲低或敲除抑制了由磷脂酰肌醇 5-激酶（PIP5K）诱导的肌动蛋白彗星，并且 PIP5K 刺激 Nck SH2 结构域结合伙伴的酪氨酸磷酸化，表明 Nck 偶联了磷酸酪氨酸和磷脂酰肌醇依赖性信号。我们表明，PI(4,5)P(2)和 PIP5K 都在 Nck 聚集诱导的肌动蛋白彗星中富集，并且肌动蛋白彗星的形成强烈受到与肌醇 5-磷酸酶结构域共聚类的抑制，以降低局部 PI(4,5)P(2)水平。肌动蛋白聚合的程度也受到 PI(4,5)P(2)敏感的 N-WASp 突变体的调节。这项研究揭示了 Nck 和 PI(4,5)P(2)在促进细胞中局部 N-WASp 介导的肌动蛋白聚合方面的强烈相互依存关系。
