src family kinases regulate renal epithelial paracellular permeability barrier through an occludin-independent mechanism§

Authors

  • Devin Caswell,

    1. Department of Biomedical Sciences, New York College of Osteopathic Medicine of New York Institute of Technology, Old Westbury, New York
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  • Shuchie Jaggi,

    1. Department of Biomedical Sciences, New York College of Osteopathic Medicine of New York Institute of Technology, Old Westbury, New York
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  • Josephine Axis,

    1. Department of Biomedical Sciences, New York College of Osteopathic Medicine of New York Institute of Technology, Old Westbury, New York
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  • Kurt Amsler

    Corresponding author
    1. Department of Biomedical Sciences, New York College of Osteopathic Medicine of New York Institute of Technology, Old Westbury, New York
    • Professor, NYCOM, Northern Boulevard, Old Westbury, NY 11568-8000.
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  • Devin Caswell and Shuchie Jaggi contributed equally to this study.

  • The authors have no conflict of interest with regard to any information contained in this manuscript.

  • §

    Author contributions: D.C., S.J., and J.A. contributed to conception and design of experiments as well as data collection, analysis, and interpretation. K.A. contributed to conception and design of experiments, collection, analysis and interpretation of data, and drafting/revising manuscript.

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-PK1 (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. J. Cell. Physiol. 228: 1210–1220, 2013. © 2012 Wiley Periodicals, Inc.

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