Sperm abnormality: Differential expression of microRNAs.

Adult male fertility requires continuous production of sperm through the spermatogenesis process involving the correct timing of regulatory signals to spermatogonial stem cells (SSCs) to support continuous gamete generation. MicroRNAs (miRNAs) modulate gene expression post-transcriptionally and are shown to regulate various biological pathways in both humans and animal models. miRNAs in Sertoli cells and germ cells respond to regulatory signals and downregulate or upregulate required mRNAs and proteins that function in different pathways to support successful spermatogenesis. In addition, differential expression of miRNAs in sperm and seminal plasma of men with sperm disorders and normozoospermia is reported. However, the role of miRNAs in the pathogenesis of patients with sperm disorders and its mechanisms have not been comprehensively studied. The aim of this review is to describe the mechanisms through which the dysregulation of miRNAs can lead to male infertility. Further, the possibility of using miRNAs as diagnostic and therapeutic targets is discussed.