Sperm-borne miR-216b modulates cell proliferation during early embryo development via K-RAS

Abstract

Semen fertilizing potential is dependent upon the morphological, functional and molecular attributes of sperm. Sperm microRNAs (miRNAs) were recently shown to hold promise regarding their association with different fertility phenotypes. However, their role in fertility regulation remains to be determined. We postulated that sperm miRNAs might regulate early embryonic development. From this perspective, sperm quality and 380 sperm miRNAs were investigated in frozen–thawed semen from high (HF; 54.3 ± 1.0% pregnancy rate) and low (LF; 41.5 ± 2.3%) fertility bulls. Out of nine miRNAs that showed different levels in sperm cells, miR-216b was present at lower levels in HF sperm cells and zygotes. Among miR-216b target genes ( K-RAS , BECN1 and JUN ), K-RAS , related to cell proliferation, revealed a higher level in HF two-cell embryos. First cleavage rate, blastocyst cell number and division number were also higher in HF. In addition, by using a model based on polyspermy embryos, we demonstrated an increase in miR-216b levels in zygotes associated with sperm cell entry. Our results shed light on a possible mechanism of paternal contribution involving sperm-borne miR-216b that modulates levels of miR-216b in zygotes and K-RAS in two-cell embryos. This modulation might regulate early development by interfering with the first cleavage and blastocyst quality.

A Combined Flow Cytometric Semen Analysis and miRNA Profiling as a Tool to Discriminate Between High- and Low-Fertility Bulls

“…In cattle, different studies reported miRNA profile alteration associated with different sperm quality levels and fertility phenotypes. A previous study by qPCR miRNA profiling with a customized panel of bovine-specific miRNAs reported several miRNAs altered in HF and LF bulls isolated directly from cryopreserved semen ( 1 , 10 ) or after purification with Percoll separation ( 8 ). Small-RNA sequencing of high and low motile fractions isolated from cryopreserved sperm using Percoll gradient, together showed variation of quality parameters and significant changes in miRNA expression ( 7 ).…”

“…Mature spermatozoa contain coding and non-coding RNAs, some of which are involved in the regulation of many physiological pathways related to spermatogenesis, sperm maturation, and early embryonic development with the potential to modulate sperm morpho-functional features as well as male reproductive ability ( 8 ). Among small RNA species, miRNAs are associated with sperm cell fertility status and embryo development ( 9 ).…”

“…Among small RNA species, miRNAs are associated with sperm cell fertility status and embryo development ( 9 ). In bulls, different profiles of sperm miRNA were investigated and associated with different sperm quality and fertility levels ( 1 , 4 , 7 , 8 , 10 ).…”

From Sperm Motility to Sperm-Borne microRNA Signatures: New Approaches to Predict Male Fertility Potential

“…Sperm-borne miR−449b overexpression in cloned embryos is associated with enhanced cleavage rates at the 8-cell stage and lower rates of apoptosis in the blastocyst (Wang et al, 2017). Sperm-borne miR−216b was recently shown to be present at higher abundance in spermatozoa from low fertility bulls and is associated with a reduced first cleavage rate as well as a reduced number of cells in blastocysts (Alves et al, 2019). In parallel, the RNAs that are acquired by spermatozoa during epididymal transit were shown to be essential for embryo implantation and development in mice (Conine et al, 2018(Conine et al, , 2019.…”

“…Within livestock animals, bulls that presented satisfactory sperm quality and history of distinct fertility (high vs. low fertility) displayed different profiles of sperm miRNAs that are summarized in Table 2 (Fagerlind et al, 2015;Alves et al, 2019;Menezes et al, 2019). Similarly, spermatozoa from boar featuring low motility and a high percentage of abnormalities, displayed a higher abundance of the miRNAs: let−7a, let−7d, let−7e, and miR−22; and lower abundance of miR−15b (Curry et al, 2011) compared with spermatozoa presenting with normal features.…”