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Functional Assessment of Intestinal Tight Junction Barrier and Ion Permeability in Native Tissue by Ussing Chamber Technique
Published on: May 26, 2021
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Water channels and barriers formed by claudins
Rita Rosenthal1, Dorothee Günzel1, Dian Theune1
1Institute of Clinical Physiology, Department of Gastroenterology, Rheumatology and Infectious Diseases, Charité - Universitätsmedizin Berlin, Berlin, Germany.
Annals of the New York Academy of Sciences
|June 22, 2017
Summary
Claudin-2, a protein in tight junctions, facilitates water transport through paracellular pathways in leaky epithelia. This finding clarifies the long-debated role of paracellular routes in physiological water movement.
Area of Science:
- Physiology
- Molecular Biology
- Biophysics
Background:
- Water transport across epithelia occurs via transcellular and paracellular routes.
- Aquaporins explain transcellular water movement, but paracellular water passage remained debated.
- Claudin-2, a tight junction protein, was identified as a water-permeable paracellular channel.
Purpose of the Study:
- To investigate the role of claudin-2 in paracellular water transport.
- To explore the water permeability of other claudin family members.
- To understand the regulation of paracellular water permeation.
Main Methods:
- Genetic analysis
- Molecular biology techniques
- Computational modeling
- Physiological measurements
Main Results:
- Claudin-2 facilitates paracellular water transport in kidney proximal tubules, accounting for 23-30% of total water movement.
- Other claudins (claudin-10a, -10b, -17) are ion channels but not water channels.
- Barrier-forming claudins (claudin-1, -3) do not affect water permeability.
Conclusions:
- Claudin-2 is a key determinant of paracellular water permeability in leaky epithelia.
- The claudin family exhibits diverse roles in paracellular transport, with specific members mediating water passage.
- Further research is needed to elucidate the mechanisms and regulation of paracellular water transport.
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