Activation of adenylyl cyclases, regulation of insulin status, and cell survival by G(alpha)olf in pancreatic beta-cells.
Because we recently identified the G(alpha)olf subunit in rat pancreatic beta-cells, we investigated the downstream effectors and the biological functions of this G protein in HEK-293T cells and the insulin-secreting mouse betaTC-3 cell line. With the use of transient transfection of HEK-293T cells with constitutively activated G(alpha)olf (G(alpha)olfQ214L, i.e., AG(alpha)olf), together with expression vectors encoding the adenylyl cyclase (AC) isoforms (AC-I to -VIII and soluble AC), compared with cotransfections using AG(alphas) (G(alphas)R201C), we observed that AG(alpha)olf preferentially activates AC-I and -VIII, which are also expressed in beta-cells. Stable overexpression of wild-type or AG(alpha)olf in betaTC-3 cells resulted in partial attenuation of insulin secretion and biosynthesis, suggesting that chronic activation of the G(alpha)olf-signaling pathway is associated with beta-cell desensitization. In agreement, transfected betaTC-3 cells present a decreased insulin content with respect to parental cells, whereas the proinsulin convertases PC-1 and PC-2 were unaffected. Furthermore, betaTC-3-AG(alpha)olf cells are resistant to serum starvation-induced apoptosis. Our findings suggest that G(alpha)olf is involved in insulin status, cell survival, and regeneration of the insulin-secreting beta-cells during development and diabetes.
Régnauld
Karine L
KL
Institut National de la Santé et de la Recherche Médicale U482, Signal Transduction and Cellular Function in Diabetes and Digestive Cancers, Saint-Antoine Hospital, 75571 Paris Cedex 12, France.
Leteurtre
Emmanuelle
E
Gutkind
Silvio J
SJ
Gespach
Christian P
CP
Emami
Shahin
S
D000262:Adenylyl Cyclases / Q000378:metabolism*; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000378:metabolism; D044385:GTP-Binding Protein alpha Subunits; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000494:pharmacology; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007340:Insulinoma / Q000378:metabolism; D007515:Islets of Langerhans / Q000502:physiology*; D007527:Isoenzymes / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008297:Male; D010179:Pancreas / Q000378:metabolism; D045706:Proprotein Convertase 2; D043484:Proprotein Convertases; D012313:RNA / Q000378:metabolism; D012016:Reference Values; D013381:Subtilisins / Q000378:metabolism; D013737:Testis / Q000378:metabolism; D014018:Tissue Distribution
D044385:GTP-Binding Protein alpha Subunits; D007328:Insulin; D007527:Isoenzymes; C084618:olfactory G protein subunit alpha olf; D012313:RNA; D000242:Cyclic AMP; D043484:Proprotein Convertases; D013381:Subtilisins; D045706:Proprotein Convertase 2; D016282:Aspartic Acid Endopeptidases; D019205:GTP-Binding Protein alpha Subunits, Gs; D020962:Heterotrimeric GTP-Binding Proteins; D000262:Adenylyl Cyclases