title: Analysis of the myosin-II-responsive focal adhesion proteome reveals a role for β-Pix in negative regulation of focal adhesion maturation.
abstract: Focal adhesions undergo myosin-II-mediated maturation wherein they grow and change composition to modulate integrin signalling for cell migration, growth and differentiation. To determine how focal adhesion composition is affected by myosin II activity, we performed proteomic analysis of isolated focal adhesions and compared protein abundance in focal adhesions from cells with and without myosin II inhibition. We identified 905 focal adhesion proteins, 459 of which changed in abundance with myosin II inhibition, defining the myosin-II-responsive focal adhesion proteome. The abundance of 73% of the proteins in the myosin-II-responsive focal adhesion proteome was enhanced by contractility, including proteins involved in Rho-mediated focal adhesion maturation and endocytosis- and calpain-dependent focal adhesion disassembly. During myosin II inhibition, 27% of proteins in the myosin-II-responsive focal adhesion proteome, including proteins involved in Rac-mediated lamellipodial protrusion, were enriched in focal adhesions, establishing that focal adhesion protein recruitment is also negatively regulated by contractility. We focused on the Rac guanine nucleotide exchange factor β-Pix, documenting its role in the negative regulation of focal adhesion maturation and the promotion of lamellipodial protrusion and focal adhesion turnover to drive cell migration.
authors.affiliation: Cell Biology and Physiology Centre, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland 20892, USA.
authors.forename: Jean-Cheng
authors.initials: JC
authors.lastname: Kuo
authors.forename: Xuemei
authors.initials: X
authors.lastname: Han
authors.forename: Cheng-Te
authors.initials: CT
authors.lastname: Hsiao
authors.forename: John R
authors.initials: JR
authors.lastname: Yates
authors.forename: Clare M
authors.initials: CM
authors.lastname: Waterman
mesh_terms: D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D022001:Focal Adhesions / Q000737:chemistry* / Q000502:physiology*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D024462:Myosin Type II / Q000378:metabolism*; D020543:Proteome / Q000032:analysis*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015203:Reproducibility of Results; D064067:Rho Guanine Nucleotide Exchange Factors
chemical_list: C576606:ARHGEF7 protein, human; D003598:Cytoskeletal Proteins; D020662:Guanine Nucleotide Exchange Factors; D020543:Proteome; D011993:Recombinant Fusion Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; D024462:Myosin Type II