Localization of the type 3 inositol 1,4,5-trisphosphate receptor in the Ca2+ wave trigger zone of pancreatic acinar cells

• Published in: The Journal of biological chemistry Vol. 269; no. 7; pp. 4693 - 4696
• Main Authors: NATHANSON, M. H, FALLON, M. B, PADFIELD, P. J, MARANTO, A. R
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 18.02.1994
• Subjects: Amylases - metabolism; Animals; Antibodies; Biological and medical sciences; Blotting, Western; Calcium - metabolism; Calcium Channels - analysis; Calcium Channels - metabolism; Cell receptors; Cell structures and functions; Cytosol - metabolism; Fundamental and applied biological sciences. Psychology; Immunohistochemistry; Inositol 1,4,5-Trisphosphate - metabolism; Inositol 1,4,5-Trisphosphate Receptors; Male; Miscellaneous; Molecular and cellular biology; Pancreas - cytology; Pancreas - metabolism; Rats; Rats, Sprague-Dawley; Receptors, Cytoplasmic and Nuclear - analysis; Receptors, Cytoplasmic and Nuclear - metabolism; Signal Transduction; Amylase; Calcium; Rat; Enzyme; Rodentia; Acinus; Inositol phosphate; Signal transduction; Membrane receptor; Vertebrata; Mammalia; Localization; Pancreas
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(17)37597-x

Agonist-induced cytosolic Ca2+ (Ca2+i) signals begin as apical-to-basal Ca2+i waves in pancreatic acinar cells and in other polarized epithelia. However, the basis of this polarized Ca2+i signaling pattern is unknown. Here we use immunocytochemistry to demonstrate that the type 3 inositol trisphosphate receptor is localized to the extreme apex of pancreatic acinar cells, the region which corresponds to the trigger zone from which Ca2+i signals originate in this cell type (Kasai, H., Li, Y.X., and Miyashita, Y. (1993) Cell 74, 669-677). We also show that inositol trisphosphate-mediated Ca2+ release induces amylase release from permeabilized pancreatic acini. Since Ca2+i signals begin by inositol trisphosphate-mediated Ca2+ release, these findings suggest that localization of the type 3 inositol trisphosphate receptor to the trigger zone is responsible for the generation of apical-to-basal Ca2+i waves, and that this organization may be important for regulating apical exocytosis in pancreatic acinar cells.