Brefeldin A-inhibited guanine nucleotide-exchange protein (BIG) 2 regulates cell migration via effects on integrin β1 cycling and actin cytoskeleton remodeling

Wednesday, October 10, 2012 — Poster Session II
Noon – 2:00 p.m	Natcher Conference Center, Building 45	NHLBI	CELLBIO-14

Authors

• X. Shen
• C. Li
• A. Aponte
• R. Shen
• E.M. Billings
• J. Moss
• M. Vaughan

Abstract

Brefeldin A-inhibited guanine nucleotide-exchange protein (BIG)2 activates ADP-ribosylation factors (Arfs), ~20-kDa GTPase proteins critical for continuity of intracellular vesicular trafficking by accelerating the replacement of ARF-bound GDP with GTP. Mechanisms of additional BIG2 function(s) are less clear. Here, the participation of BIG2 in integrin β1-cycling through actin dynamics during cell migration was identified using small interfering RNA (siRNA) and Difference Gel Electrophoresis (DIGE) analyses. After BIG2 depletion, cytosolic levels of Arp2, Arp3, cofilin-1, phosphocofilin, vinculin, and Grb2, known to be involved in effects of integrin β1-extracellular matrix interactions on actin function and cell translocation, were increased. Treatment of HeLa cells with BIG2 siRNA specifically resulted in perinuclear accumulation of integrin β1 and its delayed return to the cell surface. Motility of BIG2-depleted cells was simultaneously decreased, as were actin-based membrane protrusions and accumulations of Arp2, Arp3, cofilin, and phosphocofilin at the leading edges of migrating cells, in wound-healing assays. Taken together, these data reveal a novel mechanism(s) through which BIG2 may coordinate actin cytoskeleton mechanics and membrane traffic in cell migration via integrin β1 action and actin functions.

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