Gestational and tissue-specific regulation of clc-2 chloride
channel expression.
Murray, Carol B., Shijian Chu, and Pamela L. Zeitlin.
Johns Hopkins Medical Institutions, Eudowood Division of
Respiratory Sciences, Baltimore, MD 21287
APStracts 3:0125L, 1996.
Chloride channels supply critical functions in epithelial cells
throughout the body. While function of the volume- and voltage-gated
ClC-2 is uncertain, its wide tissue distribution of mRNA suggests
ClC-2 has important housekeeping functions. This study's objective
was to identify the extent of not only ClC-2 mRNA expression, but
also protein expression as a measure of the capacity for ClC-2
chloride secretion in epithelial tissues. Using quantitative
ribonuclease protection assay, we found that ClC-2 mRNA transcripts
were abundant in fetal and postnatal brain, fetal kidney, liver,
intestine, and lung. In contrast to brain, ClC-2 mRNA transcripts
were downregulated during late gestation in lung, kidney, and
intestine. The lung expressed the least ClC-2 mRNA. Immunoblotting
demonstrated similar tissue- and gestation-dependent variations in
ClC-2 protein expression. To determine if there is a correlation
between the sites of ClC-2 protein expression and CFTR, another
epithelial chloride channel, a polyclonal C-terminal ClC-2 antibody
and an anti-R domain CFTR antibody were used. ClC-2 and CFTR were
expressed in different sites in lung and kidney.
Received 4 January 1996; accepted in final form 24 June 1996.
APS Manuscript Number L6-6.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 4 August 1996