Table of Contents
Journal of Signal Transduction
Volume 2011, Article ID 376543, 10 pages
http://dx.doi.org/10.1155/2011/376543
Research Article

Podocyte Protein, Nephrin, Is a Substrate of Protein Tyrosine Phosphatase 1B

1Division of Nephrology, Department of Medicine, McGill University, Montreal, QC, Canada H3A 2B4
2Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada NIG 2W1

Received 5 April 2011; Revised 15 June 2011; Accepted 14 August 2011

Academic Editor: Céline M. DerMardirossian

Copyright © 2011 Lamine Aoudjit et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Glomerular podocytes are critical for the barrier function of the glomerulus in the kidney and their dysfunction causes protein leakage into the urine (proteinuria). Nephrin is a key podocyte protein, which regulates the actin cytoskeleton via tyrosine phosphorylation of its cytoplasmic domain. Here we report that two protein tyrosine phosphatases, PTP1B and PTP-PEST negatively regulate nephrin tyrosine phosphorylation. PTP1B directly binds to and dephosphorylates nephrin, while the action of PTP-PEST is indirect. The two phosphatases are also upregulated in the glomerulus in the rat model of puromycin aminonucleoside nephrosis. Both overexpression and inhibition of PTP1B deranged the actin cytoskeleton in cultured mouse podocytes. Thus, protein tyrosine phosphatases may affect podocyte function via regulating nephrin tyrosine phosphorylation.