title: Association of Grb7 with phosphoinositides and its role in the regulation of cell migration.
abstract: Grb7 is the prototype of a family of adaptor molecules that also include Grb10 and Grb14 that share a conserved molecular architecture including Src homology 2 (SH2) and pleckstrin homology (PH) domains. Grb7 has been implicated as a downstream mediator of integrin-FAK signal pathways in the regulation of cell migration, although the molecular mechanisms are still not well understood. In this paper, we investigated the potential role and mechanisms of PH domain in Grb7 in the regulation of cell migration. We found that the PH domain mediated Grb7 binding to phospholipids both in vitro and in intact cells. Furthermore, both Grb7 and its PH domain preferentially interacted with phosphatidylinositol phosphates showing strongest affinity to the D3- and D5-phosphoinositides. The PH domain interaction with phosphoinositides was shown to play a role in the stimulation of cell migration by Grb7. It was also shown to be necessary for Grb7 phosphorylation by FAK, although it was not required for Grb7 interaction with FAK or recruitment to the focal contacts. Last, we found that PI 3-kinase activity played a role in both Grb7 association with phosphoinositides and its stimulation of cell migration. In addition, both FAK binding to PI 3-kinase via its autophosphorylated Tyr(397) and integrin-mediated cell adhesion increased Grb7 association with phosphoinositides. Together, these results identified the Grb7 PH domain interaction with phosphoinositides and suggested a potential mechanism by which several signaling molecules including Grb7, FAK, and PI 3-kinase and their interactions cooperate to mediate signal transduction pathways in integrin-mediated cell migration.
authors.affiliation: Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Tang-Long
authors.initials: TL
authors.lastname: Shen
authors.forename: Dong Cho
authors.initials: DC
authors.lastname: Han
authors.forename: Jun-Lin
authors.initials: JL
authors.lastname: Guan
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D006224:Cricetinae; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D051383:GRB10 Adaptor Protein; D051382:GRB7 Adaptor Protein; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D016023:Integrins / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008954:Models, Biological; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C099655:GRB14 protein, human; C495955:GRB7 protein, human; D016023:Integrins; D010716:Phosphatidylinositols; D010743:Phospholipids; D011506:Proteins; D011993:Recombinant Fusion Proteins; D051382:GRB7 Adaptor Protein; D051383:GRB10 Adaptor Protein; D005982:Glutathione Transferase; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human