Rodent pancreatic islet cells contain the calcium-binding proteins calcineurin and calretinin.
Calcium is known to be of critical importance for hormone secretion in the insulin-producing B-cells of the endocrine, pancreas. Calcium-mediated intracellular signal transduction and the regulation of the concentration of free calcium in B-cells probably involve calcium-binding proteins. In the present study, we have investigated the expression of the calcium/calmodulin-dependent phosphatase, calcineurin, and the EF-hand calcium-binding protein, calretinin, in pancreata of hamsters, gerbils, and rats by immunocytochemistry. Immunocytochemical investigations of serial semithin sections of plastic-embedded pancreata revealed that calcineurin and calretinin were constantly present in islet cells of all three species. In addition to B-cells, these proteins could also be detected in glucagon (A-), somatostatin (D-), and pancreatic polypeptide (PP-) cells. Non-B-cells, especially glucagon-producing A-cells, often exhibited a significantly higher degree of immunoreactivity for both calcium-binding proteins than B-cells. Thus, calcineurin and calretinin may play distinct roles in the regulation of calcium-dependent secretory activities of the different pancreatic endocrine cell types.
Redecker
P
P
Department of Anatomy I, Hannover Medical School, Germany.
Cetin
Y
Y
D000818:Animals; D064032:Calbindin 2; D019703:Calcineurin / Q000032:analysis*; D002135:Calcium-Binding Proteins / Q000032:analysis*; D006224:Cricetinae; D005260:Female; D005849:Gerbillinae; D007150:Immunohistochemistry; D007515:Islets of Langerhans / Q000737:chemistry*; D008297:Male; D008647:Mesocricetus; D051381:Rats; D011917:Rats, Inbred Lew; D017208:Rats, Wistar; D064030:S100 Calcium Binding Protein G / Q000032:analysis*
C576512:Calb2 protein, rat; D064032:Calbindin 2; D002135:Calcium-Binding Proteins; D064030:S100 Calcium Binding Protein G; D019703:Calcineurin