Actin depolymerizing factor and cofilin phosphorylation dynamics: Response to signals that regulate neurite extension
Actin depolymerizing factor and cofilin phosphorylation dynamics: Response to signals that regulate neurite extension
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DOI：
10.1002/(sici)1097-0169(1998)39:2
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发表时间：
1998-01-01
影响因子：
--
通讯作者：
Bamburg, JR
中科院分区：
文献类型：
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作者：
Meberg, PJ;Ono, S;Bamburg, JR
肌动蛋白解聚因子（ADF）/ cofilin的肌动蛋白组装调节活性被磷酸化抑制。进行了研究，以表征参与激活磷酸化ADF（pADF）的信号通路和磷酸酶，强调与神经元突起延伸相关的信号。蛋白质印迹使用抗体ADF和cofilin，以及ADF/cofilin磷酸化表位特异性抗体的特点，在本文中，被用来测量ADF/cofilin的磷酸化状态和磷酸营业额的变化，在响应抑制剂和已知的影响生长锥运动剂。[Ca 2 +]（i）和cAMP水平的增加诱导HT 4和皮质神经元中的快速pADF去磷酸化。钙依赖性去磷酸化依赖于蛋白磷酸酶2B（PP 2B）的激活，而cAMP依赖性去磷酸化可能是通过激活PPI。生长因子如NGF和胰岛素也诱导快速pADF/pcofilin去磷酸化，在PC 12细胞中NGF刺激的去磷酸化与ADF/cofilin易位到皱褶膜相关。特别令人感兴趣的是发现pADF和pcofilin上的磷酸盐周转率可以通过生长因子增强而不改变净pADF水平，这表明生长因子可以激活促进ADF/cofilin的磷酸化和去磷酸化的分叉途径。所有实验结果表明ADF和cofilin的磷酸化动力学是协同调节的。降低的pADF水平的信号与增加的过程延伸相关，而增加pADF水平的试剂，如溶血磷脂酸，抑制过程延伸。这些数据表明，pADF的去磷酸化/激活是对调节肌动蛋白动力学并改变细胞形态和神经元生长的信号通路的激活的显著响应。(C)1998 Wiley-Liss，Inc.
The actin assembly-regulating activity of actin depolymerizing factor (ADF)/ cofilin is inhibited by phosphorylation. Studies were undertaken to characterize the signaling pathways and phosphatases involved in activating phosphorylated ADF (pADF), emphasizing signals related to neuronal process extension. Western blots using antibodies to ADF and cofilin, as well as an ADF/cofilin phosphoepitope specific antibody characterized in this paper, were used to measure changes in the phosphorylation state and phosphate turnover of ADF/cofilin in response to inhibitors and agents known to influence growth cone motility. Increases in both [Ca2+](i) and cAMP levels induced rapid pADF dephosphorylation in HT4 and cortical neurons. Calcium-dependent dephosphorylation depended on the activation of protein phosphatase 2B (PP2B), while cAMP-dependent dephosphorylation was likely through activation of PPI. Growth factors such as NGF and insulin also induced rapid pADF/pcofilin dephosphorylation, with NGF-stimulated dephosphorylation in PC12 cells correlated with the translocation of ADF/cofilin to ruffling membranes. Of special interest was the finding that the rate of phosphate turnover on both pADF and pcofilin could be enhanced by growth factors without changing net pADF levels, demonstrating that growth factors can activate bifurcating pathways that promote both phosphorylation and dephosphorylation of ADF/cofilin. All experimental results indicated that dynamics of phosphorylation on ADF and cofilin are coordinately regulated. Signals that decreased pADF levels are associated with increased process extension, while agents that increased pADF levels, such as lysophosphatidic acid, inhibit process extension. These data indicate that dephosphorylation/activation of pADF is a significant response to the activation of signal pathways that regulate actin dynamics and alter cell morphology and neuronal outgrowth. (C) 1998 Wiley-Liss, Inc.