title: src family kinases regulate renal epithelial paracellular permeability barrier through an occludin-independent mechanism.
abstract: Paracellular permeability is mediated by the epithelial cell tight junction. Studies in intestinal and other epithelia have suggested that the activity of src family kinases (SFKs) increases epithelial paracellular permeability through its action on the tight junction protein, occludin, but the involvement of SFKs and occludin in regulation of renal epithelial paracellular permeability is unclear. In this study, the role of SFKs in regulation of renal epithelial paracellular permeability and the involvement of occludin protein in this regulatory event was examined in two renal epithelial cell lines, LLC-PK(1) (proximal tubule-like) and MDCK (distal tubule-like). The effect of broad spectrum SFK inhibitors on paracellular permeability of calcein and fluorescein-dextran3000 were examined. SFK inhibitor treatment increased paracellular movement of both compounds in both renal epithelial cell lines. The SFK inhibitor effect was concentration-dependent and, at low concentrations, was not associated with cell damage/death. Response to SFK inhibitors was acquired progressively after cell populations attained confluence suggesting maturation of the regulatory mechanism. Increased paracellular permeability was not associated with dramatic changes in total cell content of occludin protein, its partitioning between detergent-soluble and -insoluble fractions, or its subcellular localization. Further, the SFK-induced increase in paracellular permeability was unaffected by either occludin protein overexpression or occludin protein knockdown. These results demonstrate that SFK activity decreases paracellular permeability of renal epithelial cells, as opposed to its effect in intestinal epithelial cells, and that this regulation is not mediated by occludin protein.
authors.affiliation: Department of Biomedical Sciences, New York College of Osteopathic Medicine of New York Institute of Technology, Old Westbury, NY, USA.
authors.forename: Devin
authors.initials: D
authors.lastname: Caswell
authors.forename: Shuchie
authors.initials: S
authors.lastname: Jaggi
authors.forename: Josephine
authors.initials: J
authors.lastname: Axis
authors.forename: Kurt
authors.initials: K
authors.lastname: Amsler
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D003911:Dextrans / Q000378:metabolism; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology*; D005452:Fluoresceins / Q000378:metabolism; D007684:Kidney Tubules / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D018374:LLC-PK1 Cells; D061985:Madin Darby Canine Kidney Cells; D062793:Occludin / Q000235:genetics / Q000378:metabolism*; D010539:Permeability; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D013552:Swine; D019108:Tight Junctions / Q000187:drug effects / Q000201:enzymology*; D013997:Time Factors; D014162:Transfection; D062826:Zonula Occludens-1 Protein / Q000378:metabolism; D062827:Zonula Occludens-2 Protein / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000199:Actins; D003911:Dextrans; D005452:Fluoresceins; D062793:Occludin; D047428:Protein Kinase Inhibitors; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein; C052526:fluorescein-dextran; D019061:src-Family Kinases; C007740:fluorexon