miR-142-5p/DAX1-dependent regulation of P450c17 contributes to triclosan-mediated testosterone suppression.

Triclosan (TCS) is a potent antibacterial and antifungal compound that is extensively used in various daily products. TCS is also considered as an underlying endocrine disruptor and has anti-androgenic effects. In our previous work, we found that TCS suppressed testicular steroidogenesis via the miR-6321/JNK/Nur77 cascade, but roles of the abnormal expression of miR-142-5p and P450c17 in this molecular event were still unknown. Therefore, to verify the hypothesis that miR-142-5p and P450c17 might significantly function in other manner in testosterone decline after TCS exposure, Sprague-Dawley rats and the rat Leydig cell line were used in this study. Results showed that after TCS exposure, testicular histomorphology was abnormally changed and testosterone level was declined. Overexpressed miR-142-5p by TCS directly targeted the JAK1/STAT1 pathway. Bidirectional Co-IP assays and the use of STAT1 activator demonstrated that STAT1 could interact with and regulate Sp1. The activity, mRNA level, and protein expression of DNMT1 and DNMT3β were all decreased after TCS treatment. Sp1 silencing, ChIP, and qPCR assays showed that Sp1 regulated DNMT1 expressions by directly binding to the promoter region of DNMT1. Though the DNA methylation status of the DAX1 promoter was not affected, TCS induced the transcription and translation of DAX1 by DNMT1, in turn leading to the inhibition of steroidogenic P450c17. Taken together, TCS-induced miR-142-5p inhibits P450c17 by the JAK1/STAT1 pathway and downstream Sp1/DNMT1/DAX1 cascade, finally facilitating the decrease in testosterone levels.