ClC-2 chloride channels contribute to HTC cell volume homeostasis

Richard M. Roman, Roderic L. Smith, Andrew P. Feranchak, Gerald H. Clayton, R. Brian Doctor, J. Gregory Fitz

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

Membrane Cl- channels play an important role in cell volume homeostasis and regulation of volume-sensitive cell transport and metabolism. Heterologous expression of ClC-2 channel cDNA leads to the appearance of swelling-activated Cl- currents, consistent with a role in cell volume regulation. Since channel properties in heterologous models are potentially modified by cellular background, we evaluated whether endogenous ClC-2 proteins are functionally important in cell volume regulation. As shown by whole cell patch clamp techniques in rat HTC hepatoma cells, cell volume increases stimulated inwardly rectifying Cl- currents when non-ClC-2 currents were blocked by DIDS (100 μM). A cDNA closely homologous with rat brain ClC-2 was isolated from HTC cells; identical sequence was demonstrated for ClC-2 cDNAs in primary rat hepatocytes and cholangiocytes. ClC-2 mRNA and membrane protein expression was demonstrated by in situ hybridization, immunocytochemistry, and Western blot. Intracellular delivery of antibodies to an essential regulatory domain of ClC-2 decreased ClC-2-dependent currents expressed in HEK-293 cells. In HTC cells, the same antibodies prevented activation of endogenous Cl- currents by cell volume increases or exposure to the purinergic receptor agonist ATP and delayed HTC cell volume recovery from swelling. These studies provide further evidence that mammalian ClC-2 channel proteins are functional and suggest that in HTC cells they contribute to physiological changes in membrane Cl- permeability and cell volume homeostasis.

Original languageEnglish (US)
Pages (from-to)G344-G353
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume280
Issue number3 43-3
DOIs
StatePublished - Mar 2001

Keywords

  • Hepatocyte
  • Liver
  • Purinergic receptors

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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