Mechanical strain in actin networks regulates FilGAP and integrin binding to filamin A

Mechanical stresses elicit cellular reactions mediated by chemical signals. Defective responses to forces underlie human medical disorders such as cardiac failure and pulmonary injury. The actin cytoskeleton's connectivity enables it to transmit forces rapidly over large distances, implicating...

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Bibliographic Details
Published in:Nature (London) 2011-09, Vol.478 (7368), p.260-263
Main Authors: EHRLICHER, A. J, NAKAMURA, F, HARTWIG, J. H, WEITZ, D. A, STOSSEL, T. P
Format: Article
Language:English
Subjects:
Actin Cytoskeleton - chemistry
Actin Cytoskeleton - metabolism
Actins - chemistry
Actins - metabolism
Analytical, structural and metabolic biochemistry
Animals
Binding Sites
Biological and medical sciences
Confidence intervals
Contractile proteins
Contractile Proteins - metabolism
Cytoskeleton
Filamins
Fluorescence
Fundamental and applied biological sciences. Psychology
GTPase-Activating Proteins - metabolism
Holoproteins
Humans
Integrin beta Chains - metabolism
Ligands
Mechanotransduction, Cellular - physiology
Microfilament Proteins - metabolism
Myosin Type II - metabolism
Protein Binding
Proteins
Rabbits
Shear strain
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Summary:Mechanical stresses elicit cellular reactions mediated by chemical signals. Defective responses to forces underlie human medical disorders such as cardiac failure and pulmonary injury. The actin cytoskeleton's connectivity enables it to transmit forces rapidly over large distances, implicating it in these physiological and pathological responses. Despite detailed knowledge of the cytoskeletal structure, the specific molecular switches that convert mechanical stimuli into chemical signals have remained elusive. Here we identify the actin-binding protein filamin A (FLNA) as a central mechanotransduction element of the cytoskeleton. We reconstituted a minimal system consisting of actin filaments, FLNA and two FLNA-binding partners: the cytoplasmic tail of β-integrin, and FilGAP. Integrins form an essential mechanical linkage between extracellular and intracellular environments, with β-integrin tails connecting to the actin cytoskeleton by binding directly to filamin. FilGAP is an FLNA-binding GTPase-activating protein specific for RAC, which in vivo regulates cell spreading and bleb formation. Using fluorescence loss after photoconversion, a novel, high-speed alternative to fluorescence recovery after photobleaching, we demonstrate that both externally imposed bulk shear and myosin-II-driven forces differentially regulate the binding of these partners to FLNA. Consistent with structural predictions, strain increases β-integrin binding to FLNA, whereas it causes FilGAP to dissociate from FLNA, providing a direct and specific molecular basis for cellular mechanotransduction. These results identify a molecular mechanotransduction element within the actin cytoskeleton, revealing that mechanical strain of key proteins regulates the binding of signalling molecules.
ISSN:0028-0836
1476-4687
DOI:10.1038/nature10430