ClC-2 regulates mucosal barrier function associated with structural changes to the villus and epithelial tight junction

Prashant Nighot, Anthony T. Blikslager

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33 Citations (Scopus)

Abstract

We have previously shown an important role of the chloride channel ClC-2 in orchestrating repair of tight junctions in ischemia-injured mucosa. In this study, we examined the role of ClC-2 in regulating barrier function of normal murine intestinal mucosa. Ex vivo, ClC-2-/-ileal mucosa mounted in Ussing chambers had significantly higher transepithelial electrical resistance (TER) and reduced [3H]mannitol mucosal-to-serosal flux compared with wild-type (WT) mouse mucosa. We also noted that ileum from ClC-2-/- mice had a significantly reduced in vivo [3H]mannitol blood-to-lumen clearance compared with WT animals. By scanning electron microscopy, flat leaf-like villi were found to have tapering, rounded apical tips in ClC-2-/-mucosa. By transmission electron microscopy, the apical intercellular tight junctions in ClC-2-/- intestine revealed lateral membranes that were less well defined but closely aligned compared with electron-dense and closely apposed tight junctions in WT mucosa. The width of apical tight junctions was significantly reduced in ClC-2-/-intestine. Such an alteration in tight junction ultrastructure was also noted in the testicular tissue from ClC-2-/- mice. The ClC-2-/-intestinal mucosa had reduced expression of phospho-myosin light chain (MLC), and inhibition of myosin light chain kinase (MLCK) in WT mucosa partially increased TER toward the TER in ClC-2-/-intestine. Contrary to our prior work on the reparative role of ClC-2 in injured mucosa, this study indicates that ClC-2 reduces barrier function in normal mucosa. The mechanisms underlying these differing roles are not entirely clear, although ultrastructural morphology of tight junctions and MLCK appear to be important to the function of ClC-2 in normal mucosa.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume299
Issue number2
DOIs
StatePublished - Aug 1 2010

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Tight Junctions
Mucous Membrane
Electric Impedance
Intestines
Myosin-Light-Chain Kinase
Mannitol
Intestinal Mucosa
Myosin Light Chains
Wild Animals
Intercellular Junctions
Transmission Electron Microscopy
Ileum
Electron Scanning Microscopy
Ischemia
Electrons
Membranes

All Science Journal Classification (ASJC) codes

  • Gastroenterology
  • Physiology (medical)
  • Physiology
  • Hepatology

Cite this

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abstract = "We have previously shown an important role of the chloride channel ClC-2 in orchestrating repair of tight junctions in ischemia-injured mucosa. In this study, we examined the role of ClC-2 in regulating barrier function of normal murine intestinal mucosa. Ex vivo, ClC-2-/-ileal mucosa mounted in Ussing chambers had significantly higher transepithelial electrical resistance (TER) and reduced [3H]mannitol mucosal-to-serosal flux compared with wild-type (WT) mouse mucosa. We also noted that ileum from ClC-2-/- mice had a significantly reduced in vivo [3H]mannitol blood-to-lumen clearance compared with WT animals. By scanning electron microscopy, flat leaf-like villi were found to have tapering, rounded apical tips in ClC-2-/-mucosa. By transmission electron microscopy, the apical intercellular tight junctions in ClC-2-/- intestine revealed lateral membranes that were less well defined but closely aligned compared with electron-dense and closely apposed tight junctions in WT mucosa. The width of apical tight junctions was significantly reduced in ClC-2-/-intestine. Such an alteration in tight junction ultrastructure was also noted in the testicular tissue from ClC-2-/- mice. The ClC-2-/-intestinal mucosa had reduced expression of phospho-myosin light chain (MLC), and inhibition of myosin light chain kinase (MLCK) in WT mucosa partially increased TER toward the TER in ClC-2-/-intestine. Contrary to our prior work on the reparative role of ClC-2 in injured mucosa, this study indicates that ClC-2 reduces barrier function in normal mucosa. The mechanisms underlying these differing roles are not entirely clear, although ultrastructural morphology of tight junctions and MLCK appear to be important to the function of ClC-2 in normal mucosa.",
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