Significance of microRNA targeted estrogen receptor in male fertility

Estrogen receptor-alpha (ERα) mediates estrogen action in regulation of different levels of the hypothalamic-pituitary-testis axis. It has a key role in spermatogenesis. Estrogen receptor alpha knock-out (ER koα) male mice were infertile and severe impairment in spermatogenesis and seminiferous tubules was observed. Recently, it has been reported that microRNA (miRNA) mir-100 and let-7b were predicted to target ERα gene. MiRNA are small, endogenous, single stranded RNA molecules that regulate gene expression and have been implicated in various disease states. It has been proved that some miRNAs expression is tissue- and disease-specific, giving potential for identifying miRNAs as a diagnostic tool. In this study, the change in the expression levels of mir-100, let-7b and ERα expression levels were evaluated in oligospermic infertile patients (n=43) compared to control fertile subjects (n=43). After washing and separating sperms, total RNA was isolated and then cDNA was synthesized. The expression levels of mir-100 and let-7b and ERα were evaluated by real time PCR. Mir-100, let-7b levels were significantly higher than those in control group (P=0.008 and P=0.009, respectively). We have found that, ERα level was significantly decreased in comparison with normal group (P< 0.0001). Changes in mir-100, let-7b and ERα expression levels in oligospermic patients may be associated with the susceptibility and progression of infertility. The results of this study indicate that miRNA can have a key role in spermatogenesis and might have a diagnostic and prognostic value in men infertility.