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Functional Assessment of Intestinal Tight Junction Barrier and Ion Permeability in Native Tissue by Ussing Chamber Technique
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Tricellulin Effect on Paracellular Water Transport
Carlos Ayala-Torres1, Susanne M Krug1, Jörg D Schulzke1
1Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology and Rheumatology, Charité-Universitätsmedizin Berlin, 12203 Berlin, Germany.
International Journal of Molecular Sciences
|November 20, 2019
Summary
Tricellulin, a tight junction protein, regulates water transport in epithelia. Reduced tricellulin expression increases water permeability, impacting epithelial barrier function.
Area of Science:
- Cell Biology
- Epithelial Physiology
- Membrane Transport
Background:
- Epithelial cells utilize transcellular and paracellular pathways for water transport, driven by osmotic gradients.
- While aquaporins facilitate transcellular water flow, the paracellular water pathway through tight junctions (TJ) was less understood.
- Claudin-2 and claudin-15 were identified as paracellular water transport components, but the role of tricellulin in the tricellular TJ (tTJ) remained unclear.
Purpose of the Study:
- To investigate the role of tricellulin in regulating water transport across a tight epithelial barrier.
- To determine if tricellulin influences paracellular water permeability.
Main Methods:
- Stable transfection of Madin-Darby canine kidney clone 7 (MDCK C7) cells with small hairpin RNA (shRNA) to create tricellulin knockdown (KD) models.
- Induction of water flux using osmotic gradients with mannitol and varying molecular weight dextrans (4 and 40 kDa).
- Measurement and comparison of water flux between tricellulin KD cells and vector control cells.
Main Results:
- Tricellulin knockdown (KD) cells exhibited significantly higher water flux compared to vector controls.
- This indicates that tricellulin normally restricts water passage through the paracellular pathway.
- The results suggest a direct role for tricellulin in controlling water permeability in tight epithelia.
Conclusions:
- Tricellulin plays a crucial role in regulating water permeability in tight epithelial cell lines.
- Downregulation of tricellulin leads to increased paracellular water transport.
- Tricellulin functions to maintain epithelial barrier integrity by controlling water flux.
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