Ca2+/calmodulin-dependent protein kinase II delta2 regulates gene expression of insulin in INS-1 rat insulinoma cells.
Ca(2+)/calmodulin-dependent protein kinase II is a member of a broad family of ubiquitously expressed Ca(2+) sensing serine/threonine-kinases. Ca(2+)/calmodulin-dependent protein kinase II is highly expressed in insulin secreting cells and is associated with insulin secretory granules and has been proposed to play an important role in exocytosis or in insulin granule transport to release sites. To elucidate its function the antisense sequence of the major beta-cell subtype, Ca(2+)/calmodulin-dependent protein kinase II delta(2), was stably expressed in INS-1 rat insulinoma cells. This caused a loss of Ca(2+)/calmodulin-dependent protein kinase II delta(2) expression at the mRNA and protein level, while the expression of the 95% homologous Ca(2+)/calmodulin-dependent protein kinase II gamma and of beta-cell specific proteins such as the homeodomain factor pancreatic-duodenal homeobox factor-1 (PDX-1, also referred to as islet/duodenum homeobox-1, IDX-1, insulin promoter factor-1, IPF-1 and somatostatin transactivating factor-1, STF-1), the glucagon-like peptide-1 (GLP-1) receptor and K(ATP)-channels K(IR)6.2/SUR-1 (sulfonylurea receptor-1) was not altered. Unexpectedly, the cells showed a large reduction of insulin gene expression, which was due to reduced insulin gene transcription. Electrophoretic mobility shift assays of PDX-1 binding to the insulin promoter A1 and E2/A3A4 elements showed additional bands indicating alterations of PDX-1 complex formation. Stable over expression of Ca(2+)/calmodulin-dependent protein kinase II delta(2), by contrast, was associated with elevated expression of insulin mRNA. Therefore, we conclude that Ca(2+)/calmodulin-dependent protein kinase II delta(2) links fuel-dependent increases in intracellular Ca(2+) concentrations to transcriptional regulation of genes related to the metabolic control of insulin secretion.
Osterhoff
M
M
Deutsches Institut für Ernährungsforschung (DIfE), D-14558, Bergholz-Rehbrücke, Germany. martino@mail.dife.de
Möhlig
M
M
Schwanstecher
M
M
Seufert
J
J
Ortmann
J
J
Schatz
H
H
Pfeiffer
A F H
AF
D018528:ATP-Binding Cassette Transporters; D000818:Animals; D016375:Antisense Elements (Genetics); D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000235:genetics; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D005809:Genes, Regulator / Q000235:genetics; D000067757:Glucagon-Like Peptide-1 Receptor; D018398:Homeodomain Proteins; D007328:Insulin / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000201:enzymology* / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011955:Receptors, Drug / Q000378:metabolism; D018027:Receptors, Glucagon / Q000378:metabolism; D064233:Sulfonylurea Receptors; D015534:Trans-Activators / Q000378:metabolism; D014407:Tumor Cells, Cultured
D018528:ATP-Binding Cassette Transporters; C577509:Abcc8 protein, rat; D016375:Antisense Elements (Genetics); C000593835:Glp1r protein, rat; D000067757:Glucagon-Like Peptide-1 Receptor; D018398:Homeodomain Proteins; D007328:Insulin; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger; D011955:Receptors, Drug; D018027:Receptors, Glucagon; D064233:Sulfonylurea Receptors; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517677:Camk2d protein, rat; C517678:Camk2g protein, rat; D002118:Calcium