Flutamide alters the distribution of c-Src and affects the N-cadherin-β-catenin complex in the seminiferous epithelium of adult rat

Abstract

This study was undertaken to explore interactions between c-Src kinase and the N-cadherin-β-catenin complex in seminiferous tubules of flutamide-treated rats. An anti-androgen flutamide (50 mg/kg bw) was injected daily into adult rats from postnatal days 82 to 88. Testes from 90-day-old control and flutamide-treated rats were used for experiments. Flutamide did not affect testis morphology, but impaired connexin43 immunoexpression between Sertoli cells at the blood-testis barrier (BTB) region, indicating the BTB as a sensitive target for flutamide. Real-time RT-PCR and western blot analyses revealed upregulation of N-cadherin at the mRNA and protein level after flutamide exposure (p < 0.05), whereas no changes in β-catenin and c-Src expression were observed. Notably, membranous β-catenin immunolocalization indicated its involvement in the cell adhesion complex rather than its contribution to the Wnt signaling pathway. As we used an exposure regime which avoided germ cell loss, it is likely that changes in the N-cadherin-β-catenin complex are a primary effect of androgen signaling disruption by flutamide. Immunohistochemistry revealed a diffusion of N-cadherin and β-catenin signals away from the BTB with concomitant disruption of c-Src staining pattern. As detected by immunofluorescence and coimmunoprecipitation, flutamide promoted disassembly of the N-cadherin-ß-catenin complex, induced N-cadherin to dissociate from c-Src at the BTB site, and altered interactions between the cell junction proteins and/or c-Src. Equally important, increased levels of p-N-cadherin-Tyr860 and p-β-catenin-Tyr654 (p < 0.05) pointed to a mechanism related to adhesion complex disassembly and suggested a potential role of c-Src in the control of the protein-protein dynamics. Overall, for the first time we have shown that flutamide alters the distribution of c-Src and affects N-cadherin-β-catenin interactions at the BTB. Understanding mechanism(s) by which anti-androgens can affect intercellular adhesion within the testis is relevant for predicting and preventing reproductive disorders affecting male fertility.