MiRNA content of sperm depends on the efficiency of spermatogenesis

Genetic information from parent to offspring is transmitted by specialized cells, very adapted to its function: the spermatozoa. The development of these cells in testis (spermatogenesis) is a highly regulated process. Production of sperm depends on precise, developmental stage- and germ-cell type-specific expression of about 2,500 different genes.

MicroRNAs (miRNAs) act as regulatory molecules of gene expression and actively participate in diverse aspects of vertebrate differentiation and development. The role of miRNAs in the development of male germ cell is also relevant: specifically, they are involved in the testis differentiation in the embryo, male germline development and sperm production. Researchers from the Human Molecular Genetics group at the Bellvitge Biomedical Research Institute (IDIBELL), specifically from the research line of Molecular Genetics of Male Fertility led by Dr. Sara Larriba, in collaboration with the Andrology Service of the Puigvert Foundation, have identified an altered miRNA profile in developing germ cells (which persists in spermatozoa) in infertile individuals with low sperm production. The finding was published in the prestigious international open access journal Scientific Reports.

"In previous publications we have shown that the low efficiency of spermatogenesis in infertile individuals is associated with altered gene expression patterns in the developing germ cells, which in turn contribute to a reduction in sperm production. In this context, it is reasonable to study the cellular miRNA expression behavior, as a likely mechanism of gene expression regulation, in spermatogenic disorders ", said Dr. Larriba. In this study it has been evaluated the levels of 623 mature miRNAs in histologically well defined testicular samples with impaired spermatogenesis at different stages of the germ line. The results suggest that the cellular content of miRNAs in sperm depends on the efficiency of spermatogenesis. The most notable differences are identified the earlier the stage of germ-cell differentiation was affected by maturation failure. What is more, spermatozoa that have fulfilled the differentiation process still retain the dysregulated miRNA pattern observed in the developing SpF germ-cells. This molecular signature of altered miRNA has, most likely, functional implications for the male gamete, and may define the fertilizing capacity of the sperm. These results provide new insight into the molecular mechanisms that regulate and control male fertility, and provide elements for the development of new therapeutic tools.

Reference of the paper:

Altered miRNA Signature of Developing Germ-cells in Infertile Patients Relates to the Severity of Spermatogenic Failure and Persists in Spermatozoa.

Muñoz X, Mata A, Bassas L, Larriba S.

Sci Rep. 2015 Dec 9;5:17991. doi: 10.1038/srep17991.

PMID:26648257