Expression of the Novel Epithelial Ca2+ Channel ECaC1 in Rat Pancreatic Islets

• Published in: The journal of histochemistry and cytochemistry 2002-06, Vol.50 (6), p.789-798
• Main Authors: Janssen, Susan W.J, Hoenderop, Joost G.J, Hermus, Ad R.M.M, Sweep, Fred C.G.J, Martens, Gerard J.M, Bindels, Rene J.M
• Format: Article
• Language: English
• Subjects: Animals; Calcitriol - blood; Calcium Channels - genetics; Calcium Channels - metabolism; Diabetes Mellitus, Type 2 - metabolism; Fluorescent Antibody Technique; Islets of Langerhans - metabolism; Islets of Langerhans - ultrastructure; Male; Rats; Rats, Zucker; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; TRPV Cation Channels
• ISSN: 0022-1554; 1551-5044
• DOI: 10.1177/002215540205000605

The epithelial Ca2+ channel, ECaC1, is primarily expressed in the apical membrane of vitamin D-responsive tissues. This study characterizes for the first time the presence of this novel channel in pancreatic tissue by reverse transcriptase-polymerase chain reaction and immunohistochemistry. In addition, the expression of ECaC1 was investigated in an animal model for Type 2 diabetes mellitus, the Zucker diabetic fatty (ZDF) rat. Identical staining patterns for ECaC1 and insulin were observed, whereas no co-localization of ECaC1 with glucagon was found. ECaC1, insulin, and prohormone convertase 1 (a neuroendocrine endoprotease expressed in secretory granules) showed a similar punctate staining. ECaC1 co-localized with the Ca2+ binding protein calbindin-D28K in the β-cells. Furthermore, in contrast to wild-type rats, in ZDF rats aging led to a progressive decrease in both insulin and ECaC1 staining. Plasma 1,25-dihydroxyvitamin D3 levels were similar in both control and ZDF rats and decreased with aging. Taken together, our findings indicate that this novel Ca2+ channel may play a role in the regulation of endocrine Ca2+ homeostasis.