1. ¹Clinical Genetics Unit, Weatherall Institute of Molecular Medicine, University of Oxford, UK
2. ²UCL Institute of Child Health, University College of London, London, UK

Correspondence: AS Woolf, Nephro-Urology Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK. E-mail: A.Woolf@ich.ucl.ac.uk

Received 3 November 2006; Accepted 9 November 2006; Published online 20 December 2006.

Abstract

The uroplakins (UPs) are a family of proteins which associate with each other and form plaques on the apical surface of the urothelium. These plaques contribute to a permeability barrier, preventing the influx of urine from the urinary tract lumen. Urinary tract malformations associated with human and mouse UP mutations, the human fetal expression patterns of UPs and experiments in Xenopus oocytes are collectively revealing new functions for the UPs, forcing us to view these proteins in a new light. Rather than simply being products of the urothelial differentiation program, they may be a group of proteins central to the process of urinary tract differentiation itself.