Expression and subcellular localization of the ryanodine receptor in rat pancreatic acinar cells.
The ryanodine receptor (RyR) is the principal Ca2+-release channel in excitable cells, whereas the inositol 1,4,5-trisphosphate (InsP3) receptor (InsP3R) is primarily responsible for Ca2+ release in non-excitable cells, including epithelia. RyR also is expressed in a number of non-excitable cell types, but is thought to serve as an auxiliary or alternative Ca2+-release pathway in those cells. Here we use reverse transcription PCR to show that a polarized epithelium, the pancreatic acinar cell, expresses the type 2, but not the type 1 or 3, isoform of RyR. We furthermore use immunochemistry to demonstrate that the type 2 RyR is distributed throughout the basolateral and, to a lesser extent, the apical region of the acinar cell, but is excluded from the trigger zone, where cytosolic Ca2+ signals originate in this cell type. Since propagation of Ca2+ waves in acinar cells is sensitive to ryanodine, caffeine and Ca2+, these findings suggest that Ca2+ waves in this cell type result from the co-ordinated release of Ca2+, first from InsP3Rs in the trigger zone, then from RyRs elsewhere in the cell. RyR may play a fundamental role in Ca2+ signalling in polarized epithelia, including for Ca2+ signals initiated by InsP3.
Leite
M F
MF
Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA.
Dranoff
J A
JA
Gao
L
L
Nathanson
M H
MH
D000818:Animals; D001483:Base Sequence; D002451:Cell Compartmentation; D003001:Cloning, Molecular; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010179:Pancreas / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019837:Ryanodine Receptor Calcium Release Channel / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D017422:Sequence Analysis, DNA
D019837:Ryanodine Receptor Calcium Release Channel