Cellular localization of calmodulin-dependent protein kinases I and II to A-cells and D-cells of the endocrine pancreas.
Ca2+/calmodulin-dependent protein kinases I and II, initially identified in brain on the basis of their ability to phosphorylate synapsin I, have been implicated in the regulation of Ca2+-dependent synaptic neurosecretion. Specific recombinant and synthetic peptide antibodies were used to examine the distribution of CaM kinases I and II in the rat pancreas and other tissues. The CaM kinase I antibodies detected a doublet of cytosolic proteins of approximately 38 and approximately 42 kD by immunoblot. CaM kinase I was observed in glucagon-containing A-cells at the periphery of the islet of Langerhans but had little or no overlap with pancreatic polypeptide or somatostatin cells. In contrast, CaM kinase II was localized to somatostatin-containing D-cells. CaM kinase I co-localized with glucagon secretory granules. CaM kinase II was not associated with the somatostatin granule but rather was enriched in areas of the cells that contained relatively little somatostatin. Because glucagon secretion is Ca2+-dependent, it is attractive to speculate that CaM kinase I may play a regulatory role in glucagon secretion. Glucagon and somatostatin cells both utilize intracellular Ca2+ for signaling. Therefore, specific CaM kinases may act as effectors of Ca2+ in these different cell types.
Matovcik
L M
LM
Departments of Surgery and Cell Biology, VA CT Healthcare System, New Haven, Connecticut 06516, USA.
Nairn
A C
AC
Gorelick
F S
FS
D000818:Animals; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D004064:Digestive System / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005934:Glucagon / Q000378:metabolism; D015151:Immunoblotting; D007515:Islets of Langerhans / Q000378:metabolism*; D018613:Microscopy, Confocal; D010179:Pancreas / Q000378:metabolism; D051381:Rats; D013004:Somatostatin / Q000378:metabolism; D019864:Somatostatin-Secreting Cells / Q000378:metabolism*; D014018:Tissue Distribution
D017362:Cyclic AMP Response Element-Binding Protein; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D013004:Somatostatin; D005934:Glucagon; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517599:Camk1 protein, rat; C517682:Pnck protein, rat