菲拉明
波形蛋白
细胞生物学
生物
中间灯丝
整合素
中间丝蛋白
细胞粘附
细胞骨架
磷酸化
焦点粘着
蛋白激酶A
细胞
生物化学
免疫学
免疫组织化学
作者
Hugh Kim,Fumihiko Nakamura,Lionel Wilson,Claire Hong,Dolores Pérez‐Sala,Christopher A. McCulloch
标识
DOI:10.1016/j.yexcr.2010.02.007
摘要
Cell adhesion and spreading on collagen, which are essential processes for development and wound healing in mammals, are mediated by beta1 integrins and the actin and intermediate filament cytoskeletons. The mechanisms by which these separate cytoskeletal systems interact to regulate beta1 integrins and cell spreading are poorly defined. We previously reported that the actin cross-linking protein filamin A binds the intermediate filament protein vimentin and that these two proteins co-regulate cell spreading. Here we used deletional mutants of filamin A to define filamin A-vimentin interactions and the subsequent phosphorylation and re-distribution of vimentin during cell spreading on collagen. Imaging of fixed and live cell preparations showed that phosphorylated vimentin is translocated to the cell membrane during spreading. Knockdown of filamin A inhibited cell spreading and the phosphorylation and re-distribution of vimentin. Knockdown of filamin A and/or vimentin reduced the cell surface expression and activation of beta1 integrins, as indicated by immunoblotting of plasma membrane-associated proteins and shear force assays. In vitro pull-down assays using filamin A mutants showed that both vimentin and protein kinase Cvarepsilon bind to repeats 1-8 of filamin A. Reconstitution of filamin-A-deficient cells with full-length filamin A or filamin A repeats 1-8 restored cell spreading, vimentin phosphorylation, and the cell surface expression of beta1 integrins. We conclude that the binding of filamin A to vimentin and protein kinase Cepsilon is an essential regulatory step for the trafficking and activation of beta1 integrins and cell spreading on collagen.
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