title: An extracellular-matrix-specific GEF-GAP interaction regulates Rho GTPase crosstalk for 3D collagen migration.
abstract: Rho-family GTPases govern distinct types of cell migration on different extracellular matrix proteins in tissue culture or three-dimensional (3D) matrices. We searched for mechanisms selectively regulating 3D cell migration in different matrix environments and discovered a form of Cdc42-RhoA crosstalk governing cell migration through a specific pair of GTPase activator and inhibitor molecules. We first identified βPix, a guanine nucleotide exchange factor (GEF), as a specific regulator of migration in 3D collagen using an affinity-precipitation-based GEF screen. Knockdown of βPix specifically blocks cell migration in fibrillar collagen microenvironments, leading to hyperactive cellular protrusion accompanied by increased collagen matrix contraction. Live FRET imaging and RNAi knockdown linked this βPix knockdown phenotype to loss of polarized Cdc42 but not Rac1 activity, accompanied by enhanced, de-localized RhoA activity. Mechanistically, collagen phospho-regulates βPix, leading to its association with srGAP1, a GTPase-activating protein (GAP), needed to suppress RhoA activity. Our results reveal a matrix-specific pathway controlling migration involving a GEF-GAP interaction of βPix with srGAP1 that is critical for maintaining suppressive crosstalk between Cdc42 and RhoA during 3D collagen migration.
authors.affiliation: Laboratory of Cell and Developmental Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892-4370, USA.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Kutys
authors.affiliation: Laboratory of Cell and Developmental Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892-4370, USA.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Yamada
mesh_terms: D045744:Cell Line, Tumor; D002465:Cell Movement; D048430:Cell Shape; D003094:Collagen / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D057809:HEK293 Cells; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D038982:Integrin alpha2beta1 / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D064067:Rho Guanine Nucleotide Exchange Factors / Q000502:physiology*; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D020690:GTPase-Activating Proteins; D038982:Integrin alpha2beta1; C107953:RAC1 protein, human; D064067:Rho Guanine Nucleotide Exchange Factors; C582067:SRGAP1 protein, human; C066737:RHOA protein, human; D003094:Collagen; D054648:Protein Phosphatase 2; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein