myo-Inositol 3,4,5,6-tetrakisphosphate inhibits an apical calcium-activated chloride conductance in polarized monolayers of a cystic fibrosis cell line

Mark A. Carew, Xiaonian Yang, Carsten Schultz, Stephen B. Shears

Research output: Contribution to journalArticle

49 Scopus citations

Abstract

Does inositol 3,4,5,6-tetrakisphosphate (Ins(3,4,5,6)P4) inhibit apical Ca2+-activated Cl- conductance (CaCC)? We studied this question using human CFPAC-1 pancreatoma cells grown in polarized monolayers. Cellular Ins(3,4,5,6)P4 levels were acutely sensitive to purinergic receptor activation, rising 3-fold within 1 min of agonist addition. Intracellular Ins(3,4,5,6)P4 levels were therefore specifically elevated, independently of receptor activation, by incubating cells with a cell-permeant bioactivable analogue, 1,2-di-O-butyl-myo-inositol 3,4,5,6-tetrakisphosphate octakis(acetoxymethyl)ester (Bt2Ins (3,4,5,6)P4/AM). The latter inhibited Ca2+-activated Cl- secretion by 60%. We next used nystatin to selectively permeabilize the basolateral membrane to monovalent anions and cations, thereby preventing this membrane from electrochemically dominating ion movements through the apical membrane. Thus, we studied autonomous regulation of apical Cl- channels in situ. The properties of Cl- flux across the apical membrane were those expected of CaCC: niflumic acid sensitivity, outward rectification, and 2-fold greater permeability of I- over Cl-. Following nystatin-treatment, we elevated intracellular levels of Ins(3,4,5,6)P4 with either purinergic agonists or with Bt2Ins(3,4,5,6)P4/AM. Both protocols inhibited Ca2+-activated Cl- secretion (up to 70%). These studies provide the first demonstration that, in a physiologically relevant context of a polarized monolayer, there is an apical, Ins(3,4,5,6)P4-inhibited CaCC.

Original languageEnglish (US)
Pages (from-to)26906-26913
Number of pages8
JournalJournal of Biological Chemistry
Volume275
Issue number35
DOIs
StatePublished - Sep 1 2000

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'myo-Inositol 3,4,5,6-tetrakisphosphate inhibits an apical calcium-activated chloride conductance in polarized monolayers of a cystic fibrosis cell line'. Together they form a unique fingerprint.

  • Cite this