Role of microRNAs in mammalian spermatogenesis and testicular germ cell tumors

Abstract

microRNAs (miRNAs) are a class of small endogenous RNAs, 19-25 nucleotides in size, which play a role in the regulation of gene expression at transcriptional and post-transcriptional levels. Spermatogenesis is a complex process through which spermatogonial stem cells (SSCs) proliferate and differentiate into mature spermatozoa. A large number of miRNAs are abundantly expressed in spermatogenic cells. Growing evidence supports the essential role of miRNA regulation in normal spermatogenesis and male fertility and cumulative research has shown that this form of regulation contributes to the etiology of testicular germ cell tumors (TGCTs). In this review, we addressed recent advancements of miRNA expression profiles in testis and focused on the regulatory functions of miRNA in the process of SSC renewal, spermatogonial mitosis, spermatocyte meiosis, spermiogenesis, and the occurrence of TGCTs.

Cell-secreted vesicles containing microRNAs as regulators of gamete maturation

“…Absence of Dicer early on in development only mildly affects PGC proliferation in ovaries, but significantly decreased germ cell number in fetal testes by the time gonadal differentiation has completed (Hayashi et al 2008). Furthermore, it now is evident that Dicer, and as such microRNAs, in germ cells are necessary for meiosis (Luense et al 2011, Wang & Xu 2015 and absence of microRNAs in oocytes leads to meiotic I and II spindle defects, suggesting a potential role during chromosome segregation. Contrary to oocytes, effects of microRNA absence on male germ cell maturation appear more widespread, and include apoptosis, chromosomal misalignment, acrosome defects, morphological defects and impaired motility.…”

Paternal contribution to development: Sperm genetic damage and repair in fish

“…They are initially processed by two endonucleases: Drosha and Dicer, resulting in a 21-22 nucleotides RNA. Then a RNA-induced complex (RISC) is formed with one strand of the miRNA, guiding to specific sequences to degrade it, repressing its translation (Meister 2013;Wang and Xu 2015). Some evidences point to a great variety of biological processes in which miRNAs are involved, including among others embryo development, cell proliferation or apoptosis (Wang and Xu 2015).…”

“…Then a RNA-induced complex (RISC) is formed with one strand of the miRNA, guiding to specific sequences to degrade it, repressing its translation (Meister 2013;Wang and Xu 2015). Some evidences point to a great variety of biological processes in which miRNAs are involved, including among others embryo development, cell proliferation or apoptosis (Wang and Xu 2015). Dicer1 or Drosha knockout mouse models, in which miRNA processing is compromised, resulted also in impaired spermatogenesis and fertility after birth due to faulty germ cell proliferation (Maatouk et al 2008;Wu et al 2012).The essential and multiple functions played by miRNAs during spermatogenesis have been largely evaluated (Jodar et al 2013;Kotaja 2014;Luo et al 2015).…”

Origine développementale et environnementale de l’infertilité masculine

“…Certains miARN sont exclusivement ou préférentiellement exprimés au niveau du testicule. À ce niveau, ils jouent un rôle crucial dans la maturation de la lignée germinale et le contrôle de la fertilité masculine, l'expression d'au moins 7 miARN (miR-34c-5p, miR-122, miR-146b-5p, miR-181a, miR-374b, miR-509-5p, miR-513a-5p) étant en effet altérée dans l'infertilité masculine [30,31] …”