Ontogeny of CLCN3 chloride channel gene expression in human pulmonary epithelium

Am J Respir Cell Mol Biol. 2001 Apr;24(4):376-81. doi: 10.1165/ajrcmb.24.4.4114.

Abstract

Human fetal bronchopulmonary epithelia secrete liquid, and this chloride (Cl)-dependent process is important for normal lung growth. At the time of birth there is a maturational transition from a secretory to an absorptive phenotype. The pathways for Cl exit from the apical membrane which are required for fetal lung liquid secretion are unknown but are thought to be independent of the cystic fibrosis transmembrane conductance regulator. We determined the ontogeny of expression of the CLCN family of voltage-dependent Cl channel genes (CLCN2 through 6, K(a) and K(b)) in the human lung to identify potential pathways for pulmonary liquid secretion. Only CLCN3 and CLCN6 messenger RNA were detected by Northern analysis of fetal whole lung tissue. Ribonuclease protection assays confirmed the expression of CLCN3 and also revealed expression of CLCN2. The ontogeny of expression of these two channels was similar, peaking in midgestation and declining postnatally. In situ hybridization localized the CLCN2 and CLCN3 messages to airway and distal pulmonary epithelia and to pulmonary blood vessels. We conclude that CLCN3 is expressed in human airway epithelia and expression is developmentally regulated. The contribution of these channels to pulmonary epithelial liquid transport and lung development remains to be determined.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Blotting, Northern
  • Chloride Channels / genetics*
  • Cystic Fibrosis / physiopathology
  • Epithelial Cells / physiology*
  • Fetus / physiology
  • Gene Expression Regulation, Developmental
  • Humans
  • In Situ Hybridization
  • Lung / embryology
  • Lung / physiology*
  • RNA, Messenger / analysis

Substances

  • CLC-5 chloride channel
  • CLCA2 protein, human
  • CLCN4 protein, human
  • CLCN6 protein, human
  • Chloride Channels
  • ClC-3 channel
  • Clca2 protein, mouse
  • Clcn6 protein, mouse
  • RNA, Messenger