Spatial and isoform specific p63 expression in the male human urogenital tract

Purpose: A homologue of the p53 gene, p63 is considered to be essential for the normal development of stratified epithelium, including epithelium of the urinary tract and prostate. To determine the possible roles of p63 in the male human urogenital tract its expression was systematically examined. Materials and Methods: Expression of p63 protein was evaluated by immunofluorescence and immunohistochemistry in normal male human urogenital tract tissues. Differential expression of p63 mRNA isoforms was assessed by reverse transcriptase-polymerase chain reaction. Results: Basal cells in the stratified epithelium of the urinary and reproductive tracts, including the urothelium, prostate, seminal vesicle, ductus deferens and ductus epididymidis, showed intense nuclear immunostaining for p63. In the urinary tract p63 expression disappeared at the epithelium in the mid portion of renal papillae, at which the stratified structure of the epithelium changed to a monolayer structure. In the reproductive tract p63 expression disappeared at the ductuli efferentes. The stratified epithelium of the reproductive tract also changed at this portion. In the testis weak p63 expression was noted in spermatocytes but not in spermatogonia. At the mRNA level Delta Np63 was predominant in the urothelium, prostate, seminal vesicle, ductus deferens, and cauda and corpus epididymis, while TAp63 was predominant in testicular tissues. In addition, distribution of the TAp63 isoform was clearly distinguishable from c-kit expression, which is a biochemical marker of spermatogonia. Conclusions: Differential expression of p63 transcripts seems to characterize the developmental origin and differential biological function in the male human urogenital tract.