Filamin A regulates cell spreading and survival via beta1 integrins

Cell spreading and exploration of topographically complex substrates require tightly-regulated interactions between extracellular matrix receptors and the cytoskeleton, but the molecular determinants of these interactions are not defined. We examined whether the actin-binding proteins cortactin, vin...

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Bibliographic Details
Published in:Experimental cell research 2008-02, Vol.314 (4), p.834-846
Main Authors: Kim, Hugh, Sengupta, Anita, Glogauer, Michael, McCulloch, Christopher A
Format: Article
Language:English
Subjects:
Calcium - metabolism
Cell Adhesion
Cell Line
Cell Surface Extensions - chemistry
Cell Survival
Collagen - chemistry
Contractile Proteins - analysis
Contractile Proteins - metabolism
Fibroblasts - chemistry
Fibroblasts - metabolism
Filamins
Gingiva - cytology
Humans
Integrin beta1 - metabolism
Microfilament Proteins - analysis
Microfilament Proteins - metabolism
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Summary:Cell spreading and exploration of topographically complex substrates require tightly-regulated interactions between extracellular matrix receptors and the cytoskeleton, but the molecular determinants of these interactions are not defined. We examined whether the actin-binding proteins cortactin, vinculin and filamin A are involved in the formation of the earliest extensions of cells spreading over collagen or poly-L-lysine-coated smooth and beaded substrates. Spreading of human gingival fibroblasts was substantially reduced on beaded or poly-L-lysine-coated substrates. Filamin A, vinculin and cortactin were found in cell extensions on smooth collagen. HEK-293 cells also spread rapidly on smooth collagen and formed numerous cell extensions enriched with filamin A. Knockdown of filamin A in HEK-293 cells by short hairpin RNA reduced spreading and the number of cell extensions. Blocking beta1 integrin function significantly reduced cell spreading and localization of filamin A to cell extensions. Conversely, filamin A-knockdown reduced beta1 integrin-collagen binding as measured by 12G10 antibody, suggesting co-dependence between filamin A and beta1 integrin functions. TUNEL staining showed higher percentages of apoptosis after filamin A-knockdown in spreading cells. Chelation of [Ca2+]i with BAPTA/AM reduced spreading of wild-type and filamin A-knockdown cells, however wild-type cells showed recruitment of filamin A to the subcortex, indicating independent roles of filamin A and [Ca2+]i in cell spreading. We conclude that filamin A integrates with beta1 integrins to mediate cell spreading and prevent apoptosis.
ISSN:0014-4827
DOI:10.1016/j.yexcr.2007.11.022