Overexpression of Gs proteins and adenylyl cyclase in normal and diabetic islets.
BACKGROUND
Knowledge about the relation between G proteins and adenylyl cyclases (ACs) is important for the construction of signaling paradigms to increase our understanding of signal transduction in the normal state and its alterations in pathologic states, such as type-2 diabetes.


OBJECTIVE
The immunocytochemical expression patterns of the stimulatory Gs proteins (G alpha-s and G alpha-olf) and the in vitro Ca2+-stimulated ACs (AC1, 3, and 8) were studied in normal and spontaneously diabetic Goto-Kakizaki (GK) rat pancreatic islets with use of well-characterized antibodies. The expressions of G alpha-11 and AC2, abundant in pancreatic islets, were also studied.


RESULTS
G alpha-s and G alpha-olf were mainly expressed in insulin cells, and G alpha-11 in glucagon cells. The immunoreactivity to G alpha-s and G alpha-olf and to AC1 and AC3 was higher in the GK islets than in the controls, whereas AC8 was found only in the diabetic islets. Strong G alpha-11 and AC2 immunoreactivity was seen equally in both animal groups. G alpha-s was colocalized with all ACs, whereas G alpha-olf was mainly colocalized with AC3, and G alpha-11 with AC1.


CONCLUSIONS
The current findings may help in drawing a more specific signaling paradigm coupling Gs proteins to ACs.
Portela-Gomes
Guida M
GM
Gastroenterology Center, Lisbon University, Lisbon, Portugal. portela_gomes@yahoo.com
Abdel-Halim
Samy M
SM
D000262:Adenylyl Cyclases / Q000096:biosynthesis*; D000818:Animals; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000096:biosynthesis*; D007150:Immunohistochemistry; D007515:Islets of Langerhans / Q000378:metabolism*; D008297:Male; D051381:Rats
D019205:GTP-Binding Protein alpha Subunits, Gs; D000262:Adenylyl Cyclases