title: Somatostatin, acting at receptor subtype 1, inhibits Rho activity, the assembly of actin stress fibers, and cell migration.
abstract: Somatostatin regulates multiple biological functions by acting through a family of five G protein-coupled receptors, somatostatin receptors (SSTRs) 1-5. Although all five receptor subtypes inhibit adenylate cyclase activity and decrease intracellular cAMP levels, specific receptor subtypes also couple to additional signaling pathways. In CCL39 fibroblasts expressing either human SSTR1 or SSTR2, we demonstrate that activation of SSTR1 (but not SSTR2) attenuated both thrombin- and integrin-stimulated Rho-GTP complex formation. The reduction in Rho-GTP formation in the presence of somatostatin was associated with decreased translocation of Rho and LIM kinase to the plasma membrane and fewer focal contacts. Activation of Rho resulted in the formation of intracellular actin stress fibers and cell migration. In CCL39-R1 cells, somatostatin treatment prevented actin stress fiber assembly and attenuated thrombin-stimulated cell migration through Transwell membranes to basal levels. To show that native SSTR1 shares the ability to inhibit Rho activation, we demonstrated that somatostatin treatment of human umbilical vein endothelial cells attenuated thrombin-stimulated Rho-GTP accumulation. These data show for the first time that a G protein-coupled receptor, SSTR1, inhibits the activation of Rho, the assembly of focal adhesions and actin stress fibers, and cell migration.
authors.affiliation: Department of Physiology, University of British Columbia, Vancouver V6T 1Z3, Canada. ambuchan@interchange.ubc.ca
authors.forename: Alison M J
authors.initials: AM
authors.lastname: Buchan
authors.forename: Chin-Yu
authors.initials: CY
authors.lastname: Lin
authors.forename: Jimmy
authors.initials: J
authors.lastname: Choi
authors.forename: Diane L
authors.initials: DL
authors.lastname: Barber
mesh_terms: D000199:Actins / Q000378:metabolism*; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology; D005347:Fibroblasts / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D008168:Lung / Q000166:cytology; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D021381:Protein Transport; D017481:Receptors, Somatostatin / Q000378:metabolism*; D015398:Signal Transduction; D013004:Somatostatin / Q000378:metabolism*; D022502:Stress Fibers / Q000378:metabolism*; D013917:Thrombin / Q000378:metabolism; D013997:Time Factors; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D054460:rho-Associated Kinases
chemical_list: D000199:Actins; D047908:Intracellular Signaling Peptides and Proteins; D017481:Receptors, Somatostatin; C101130:somatostatin receptor type 1; D013004:Somatostatin; D006160:Guanosine Triphosphate; D000242:Cyclic AMP; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D013917:Thrombin; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; D000262:Adenylyl Cyclases