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Developmental changes in proximal tubule tight junction proteins.
Maha Haddad1, Fangming Lin, Vangipuram Dwarakanath
1Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, TX 75235, USA.
Pediatric Research
|December 9, 2004
Summary
Neonatal proximal tubules show different tight junction protein levels than adult tubules. Thyroid hormone does not appear to solely regulate these developmental changes in chloride permeability.
Area of Science:
- Nephrology
- Developmental Biology
- Molecular Biology
Background:
- Neonatal proximal tubules exhibit lower chloride ion permeability and higher resistance compared to adult tubules.
- Thyroid hormone administration to neonates can prematurely increase chloride permeability to adult levels.
Purpose of the Study:
- To investigate maturational changes in tight junction proteins (occludin and claudin 2) in proximal tubules.
- To determine if thyroid hormone mediates these developmental changes in tight junction proteins.
Main Methods:
- Immunoblot and immunohistochemistry were used to quantify occludin and claudin 2 expression.
- Transepithelial resistance was measured in rat proximal tubule cells in vitro.
Main Results:
- Claudin 2 abundance was 4-fold greater in neonatal proximal tubules than in adult tubules.
- Occludin expression was 4-fold greater in adult tubules compared to neonatal tubules.
- Thyroid hormone administration did not alter claudin 2 or occludin expression or transepithelial resistance in vitro.
Conclusions:
- Postnatal maturation involves significant changes in proximal tubule tight junction proteins.
- The maturational changes in tight junction proteins are not solely mediated by the increase in thyroid hormone.