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© The Rockefeller University Press,
0021-9525/2000//1141 $5.00
The Journal of Cell Biology, Volume 151, Number 6,
, 2000 1141-1154
Original Article |
Nischarin, a Novel Protein That Interacts with the Integrin
5 Subunit and Inhibits Cell Migration
alahari{at}med.unc.edu
Integrins have been implicated in key cellular functions, including cytoskeletal organization, motility, growth, survival, and control of gene expression. The plethora of integrin
and β subunits suggests that individual integrins have unique biological roles, implying specific molecular connections between integrins and intracellular signaling or regulatory pathways. Here, we have used a yeast two-hybrid screen to identify a novel protein, termed Nischarin, that binds preferentially to the cytoplasmic domain of the integrin
5 subunit, inhibits cell motility, and alters actin filament organization. Nischarin is primarily a cytosolic protein, but clearly associates with
5β1, as demonstrated by coimmunoprecipitation. Overexpression of Nischarin markedly reduces
5β1-dependent cell migration in several cell types. Rat embryo fibroblasts transfected with Nischarin constructs have "basket-like" networks of peripheral actin filaments, rather than typical stress fibers. These observations suggest that Nischarin might affect signaling to the cytoskeleton regulated by Rho-family GTPases. In support of this, Nischarin expression reverses the effect of Rac on lamellipodia formation and selectively inhibits Rac-mediated activation of the c-fos promoter. Thus, Nischarin may play a negative role in cell migration by antagonizing the actions of Rac on cytoskeletal organization and cell movement.
Key Words: integrin Rac cell migration cytoskeleton two hybrid
© 2000 The Rockefeller University Press
Abbreviations used in this paper: FAK, focal adhesion kinase; GFP, green fluorescent protein; ORF, open reading frame; REF, rat embryonic fibroblast; RIE, rat intestinal epithelial.
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