TY - JOUR
T1 - Somatostatin selectively couples to Goα in HIT-T15 cells
AU - Seaquist, Elizabeth R.
AU - Armstrong, Michael B.
AU - Gettys, Thomas W.
AU - Walseth, Timothy F.
PY - 1995/1
Y1 - 1995/1
N2 - Previously, we have demonstrated that somatostatin mediates all of its inhibitory effects on glucose-induced insulin secretion from the HIT-T15 cell through pertussis toxin-sensitive G-proteins and that the membrane fraction of this clonal line of pancreatic β-cells contains six such proteins: Giα1, Giα2, Giα3, and three forms of Goα. To determine the specificity of somatostatin receptor-G-protein coupling in HIT-T15 cells, we examined the ability of antisera specific for the COOH-terminus of Gα subtypes to inhibit somatostatin-induced augmentation of membrane GTPase activity. GTPase activity increased in membranes as a function of GTP. At all concentrations of GTP studied, 1 μmol/l somatostatin stimulated GTPase activity. Pertussis-toxin pretreatment prevented the effects of somatostatin. Antisera selective for Goα subtypes reduced the effects of somatostatin on GTPase activity (GTPase activity in absence of antisera, 125 ± 3% of control; in the presence of antisera 976, 110 ±2% of control; n = 13, P < 0.001), whereas antisera directed against Giα1, Giα2, Giα3, and Gsα were without effect. Somatostatin also significantly prevented cyclic AMP accumulation during perifusion with 11.1 mmol/l glucose through a pertussis toxin-sensitive mechanism. These data indicate that the somatostatin receptor couples to Goα in the HIT-T15 cell and suggest that Goα may link somatostatin to cyclic AMP metabolism in pancreatic β-cells.
AB - Previously, we have demonstrated that somatostatin mediates all of its inhibitory effects on glucose-induced insulin secretion from the HIT-T15 cell through pertussis toxin-sensitive G-proteins and that the membrane fraction of this clonal line of pancreatic β-cells contains six such proteins: Giα1, Giα2, Giα3, and three forms of Goα. To determine the specificity of somatostatin receptor-G-protein coupling in HIT-T15 cells, we examined the ability of antisera specific for the COOH-terminus of Gα subtypes to inhibit somatostatin-induced augmentation of membrane GTPase activity. GTPase activity increased in membranes as a function of GTP. At all concentrations of GTP studied, 1 μmol/l somatostatin stimulated GTPase activity. Pertussis-toxin pretreatment prevented the effects of somatostatin. Antisera selective for Goα subtypes reduced the effects of somatostatin on GTPase activity (GTPase activity in absence of antisera, 125 ± 3% of control; in the presence of antisera 976, 110 ±2% of control; n = 13, P < 0.001), whereas antisera directed against Giα1, Giα2, Giα3, and Gsα were without effect. Somatostatin also significantly prevented cyclic AMP accumulation during perifusion with 11.1 mmol/l glucose through a pertussis toxin-sensitive mechanism. These data indicate that the somatostatin receptor couples to Goα in the HIT-T15 cell and suggest that Goα may link somatostatin to cyclic AMP metabolism in pancreatic β-cells.
UR - http://www.scopus.com/inward/record.url?scp=0028890394&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0028890394&partnerID=8YFLogxK
M3 - Article
C2 - 7813819
AN - SCOPUS:0028890394
SN - 0012-1797
VL - 44
SP - 85
EP - 89
JO - Diabetes
JF - Diabetes
IS - 1
ER -