Continuous adhesion formation and disassembly (adhesion turnover) in the protrusions of migrating cells is regulated by unclear mechanisms. We show that p21-activated kinase (PAK)–induced phosphorylation of serine 273 in paxillin is a critical regulator of this turnover. Paxillin-S273 phosphorylation dramatically increases migration, protrusion, and adhesion turnover by increasing paxillin–GIT1 binding and promoting the localization of a GIT1–PIX–PAK signaling module near the leading edge. Mutants that interfere with the formation of this ternary module abrogate the effects of paxillin-S273 phosphorylation. PAK-dependent paxillin-S273 phosphorylation functions in a positive-feedback loop, as active PAK, active Rac, and myosin II activity are all downstream effectors of this turnover pathway. Finally, our studies led us to identify in highly motile cells a class of small adhesions that reside near the leading edge, turnover in 20–30 s, and resemble those seen with paxillin-S273 phosphorylation. These adhesions appear to be regulated by the GIT1–PIX–PAK module near the leading edge.
Paxillin phosphorylation at Ser273 localizes a GIT1–PIX–PAK complex and regulates adhesion and protrusion dynamics
Abbreviations used in this paper: CA, constitutively active; DIC, differential interference contrast; IRM, interference reflection microscopy; GEF, guanine nucleotide exchange factor; GIT, G protein–coupled receptor kinase–interacting protein; KD, kinase-dead; MEF, mouse embryonic fibroblast; MLC, myosin light chain; PAK, p21-activated kinase; PBD, p21 binding domain; PIX, PAK-interactive exchange factor; seCFP, super-enhanced cyan fluorescent protein; SHD, Spa2 homology domain; TIRF, total internal reflection fluorescence; WT, wild-type.
Anjana Nayal, Donna J. Webb, Claire M. Brown, Erik M. Schaefer, Miguel Vicente-Manzanares, Alan Rick Horwitz; Paxillin phosphorylation at Ser273 localizes a GIT1–PIX–PAK complex and regulates adhesion and protrusion dynamics . J Cell Biol 22 May 2006; 173 (4): 587–589. doi: https://doi.org/10.1083/jcb.200509075
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