title: BPGAP1 interacts with cortactin and facilitates its translocation to cell periphery for enhanced cell migration.
abstract: Rho GTPases control cell dynamics during growth and development. They are activated by guanine nucleotide exchange factors and inactivated by GTPase-activating proteins (GAPs). Many GAPs exist with various protein modules, the functions of which largely remain unknown. We recently cloned and identified BPGAP1 as a novel RhoGAP that coordinately regulates pseudopodia and cell migration via the interplay of its BNIP-2 and Cdc42GAP homology, RhoGAP, and the proline-rich domains. To further elucidate the molecular mechanism underlying cell dynamics control by BPGAP1, we used protein precipitations and matrix-assisted laser desorption/ionization mass spectrometry and identified cortactin, a cortical actin binding protein as a novel partner of BPGAP1 both in vitro and in vivo. Progressive deletion studies confirmed that cortactin interacted directly and constitutively with the proline-rich motif 182-PPPRPPLP-189 of BPGAP1 via its Src homology 3 domain. Together, they colocalized to periphery and enhanced cell migration. Furthermore, substitution of prolines at 184 and 186 with alanines abolished their interaction. Consequently, this BPGAP1 mutant failed to facilitate translocation of cortactin to the periphery, and no enhanced cell migration was observed. These results provide the first evidence that a RhoGAP functionally interacts with cortactin and represents a novel determinant in the regulation of cell dynamics.
authors.affiliation: Cell Signaling and Developmental Biology Laboratory, Department of Biological Sciences, The National University of Singapore, Singapore 117543, The Republic of Singapore.
authors.forename: Bee Leng
authors.initials: BL
authors.lastname: Lua
authors.forename: Boon Chuan
authors.initials: BC
authors.lastname: Low
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D002465:Cell Movement; D016384:Consensus Sequence; D051356:Cortactin; D003593:Cytoplasm / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011392:Proline / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D017384:Sequence Deletion / Q000235:genetics; D018909:src Homology Domains
chemical_list: C479829:ARHGAP8 protein, human; C495868:CTTN protein, human; D051356:Cortactin; D020690:GTPase-Activating Proteins; D008840:Microfilament Proteins; D011392:Proline