Multiple isoforms of the ryanodine receptor are expressed in rat pancreatic acinar cells.
Regulation of cytosolic Ca(2+) is important for a variety of cell functions. The ryanodine receptor (RyR) is a Ca(2+) channel that conducts Ca(2+) from internal pools to the cytoplasm. To demonstrate the presence of the RyR in the pancreatic acinar cell, we performed reverse transcriptase (RT)-PCR, Western blot, immunocytochemistry and microscopic Ca(2+)-release measurements on these cells. RT-PCR showed the presence of mRNA for RyR isoforms 1, 2 and 3 in both rat pancreas and dispersed pancreatic acini. Furthermore, mRNA expression for RyR isoforms 1 and 2 was demonstrated by RT-PCR in individual pancreatic acinar cells selected under the microscope. Western-blot analysis of acinar cell immunoprecipitates, using antibodies against RyR1 and RyR2, showed a high-molecular-mass (>250 kDa) protein band that was much less intense when immunoprecipitated in the presence of RyR peptide. Functionally, permeablized acinar cells stimulated with the RyR activator, palmitoyl-CoA, released Ca(2+) from both basolateral and apical regions. These data show that pancreatic acinar cells express multiple isoforms of the RyR and that there are functional receptors throughout the cell.
Fitzsimmons
T J
TJ
Department of Medicine, University of California, Los Angeles, Veterans Affairs Greater Los Angeles Healthcare System, West Los Angeles, CA 90073, USA.
Gukovsky
I
I
McRoberts
J A
JA
Rodriguez
E
E
Lai
F A
FA
Pandol
S J
SJ
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability; D016764:Cell Polarity; D002478:Cells, Cultured; D007150:Immunohistochemistry; D008970:Molecular Weight; D010171:Palmitoyl Coenzyme A / Q000494:pharmacology; D010179:Pancreas / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011233:Precipitin Tests; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D020033:Protein Isoforms; D012333:RNA, Messenger; D019837:Ryanodine Receptor Calcium Release Channel; D010171:Palmitoyl Coenzyme A; D002118:Calcium