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Immuno and functional characterization of CFTR in submandibular and pancreatic acinar and duct cells. Am J Physiol 1997 Aug;273(2 Pt 1):C442-55

Date

08/01/1997

Pubmed ID

9277342

DOI

10.1152/ajpcell.1997.273.2.C442

Scopus ID

2-s2.0-0000903375   114 Citations

Abstract

Cystic fibrosis results from defective Cl- channel activity mediated by the cystic fibrosis transmembrane conductance regulator (CFTR) gene product. In the gastrointestinal tract this is manifested in abnormal salivary secretion and pancreatic insufficiency. This is generally attributed to defective Cl- transport by the ductal system of the glands. We provide the first immunocytochemical and functional evidence for expression of CFTR protein and Cl- current in rat and mouse submandibular gland (SMG) and pancreatic acinar cells, a site proximal to the ductal system of these secretory glands. Monoclonal and polyclonal antibodies recognizing COOH-terminal epitopes of CFTR show that duct and acinar cells from the two glands express CFTR in the luminal membrane. Specificity of the polyclonal antibody was verified by absence of staining in duct and acinar cells of the SMG of cf-/cf- and delta F/delta F mice. Identification of CFTR in acinar cells was aided by demonstrating coexpression of CFTR and type 3 inositol 1,4,5-trisphosphate receptors in the luminal pole of acini and absence of type 3 inositol 1,4,5-trisphosphate receptors in ducts. Electrophysiological characterization in single SMG duct and acinar cells shows the presence of a protein kinase A-activated, voltage- and time-independent, ohmic Cl- current and absence of repolarization-dependent tail currents, all of which are kinetic properties of the CFTR-dependent Cl- channel. In addition, the channel was activated by the nonhydrolyzable ATP analog 5'-adenylylimidodiphosphate and the benzimidazalone NS-004. Channels activated by all activators were inhibited by glibenclamide and a known inhibitory antiserum [anti-CFTR-(505-511)]. Combined immunologic, functional, and pharmacological evidence allows us to conclude that acinar cells of the SMG and pancreas express functional CFTR-dependent Cl- channels. Because this site is proximal to the duct, modification of activity of this channel in acinar cells is likely to contribute to abnormal salivary secretion and pancreatic insufficiency typical of cystic fibrosis.

Author List

Zeng W, Lee MG, Yan M, Diaz J, Benjamin I, Marino CR, Kopito R, Freedman S, Cotton C, Muallem S, Thomas P

Author

Ivor J. Benjamin MD Center Director, Professor in the Medicine department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
Chlorides
Cystic Fibrosis Transmembrane Conductance Regulator
Electric Conductivity
Immunohistochemistry
Mice
Pancreas
Pancreatic Ducts
Polymerase Chain Reaction
Rats
Submandibular Gland
Transcription, Genetic
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a