The Roles of MicroRNAs in Male Infertility

Abstract

MicroRNAs applications were vastly studied throughout the years, spanning from potential cancer biomarkers to targeted therapies for various diseases. Out of these utilizations, this paper focuses on their role in male infertility. Approximately 10-15% of worldwide couples are affected by infertility. Out of these, 50% are due to male determinants. The majority of cases still have an undetermined cause. Previous studies have found that the aberrant expression of microRNAs could be linked to certain reproductive dysfunctions in males. Further on, this study looked into the most recent literature published on this subject in order to assess the connection between the up-/down-regulation of various microRNAs and the roles they play in male infertility. MicroRNAs were found to be abundant and stable in the seminal liquid, which led to a facile identification using regular RNA detection methods. It was observed that the concentration of microRNAs in semen was modified in the case of patients suffering from asthenozoospermia and azoospermia. Moreover, idiopathic male infertility was associated with a single nucleotide polymorphism of the microRNA binding site. Future studies should focus their attention on discovering future treatments against male infertility targeting specific microRNAs and also on developing new and improved contraceptive methods.

Keywords: azoospermia; male infertility; microRNAs; reproductive dysfunctions.

Figure 1

Exemplification of microRNA biogenesis. MicroRNA genes hold the genetic information necessary for the transcription of the pri-microRNA, via RNA polymerase II and III. This is further cleaved by Drosha enzyme to pre-microRNA, which is transported to the cytosol by Exportin-5. Dicer enzyme cleaves the molecule one more time, forming a microRNA duplex from which will emerge two separate strands—the passenger strand, often degraded, and the guide strand, which will form the RNA-induced silencing complex (miRISC). This will exert its role on mRNA, repressing its translation.