The micro-RNA content of unsorted cryopreserved bovine sperm and its relation to the fertility of sperm after sex-sorting

Abstract

Background The use of sex-sorted sperm in cattle assisted reproduction is constantly increasing. However, sperm fertility can substantially differ between unsorted (conventional) and sex-sorted semen batches of the same sire. Sperm microRNAs (miRNA) have been suggested as promising biomarkers of bull fertility the last years. In this study, we hypothesized that the miRNA profile of cryopreserved conventional sperm is related to bull fertility after artificial insemination with X-bearing sperm. For this purpose, we analyzed the miRNA profile of 18 conventional sperm samples obtained from nine high- (HF) and nine low-fertility (LF) bulls that were contemporaneously used to produce conventional and sex-sorted semen batches. The annual 56-day non-return rate for each semen type (NRRconv and NRRss, respectively) was recorded for each bull. Results In total, 85 miRNAs were detected. MiR-34b-3p and miR-100-5p were the two most highly expressed miRNAs with their relative abundance reaching 30% in total. MiR-10a-5p and miR-9-5p were differentially expressed in LF and HF samples (false discovery rate < 10%). The expression levels of miR-9-5p, miR-34c, miR-423-5p, miR-449a, miR-5193-5p, miR-1246, miR-2483-5p, miR-92a, miR-21–5p were significantly correlated to NRRss but not to NRRconv. Based on robust regression analysis, miR-34c, miR-7859 and miR-342 showed the highest contribution to the prediction of NRRss. Conclusions A set of miRNAs detected in conventionally produced semen batches were linked to the fertilizing potential of bovine sperm after sex-sorting. These miRNAs should be further evaluated as potential biomarkers of a sire’s suitability for the production of sex-sorted sperm.

Significance and Relevance of Spermatozoal RNAs to Male Fertility in Livestock

“…The miR-378 targets mRNAs involved in metabolism and sperm motility (Liu et al, 2019). Differential expression of spermatozoal miRNAs was also observed upon microarray analysis of spermatozoal miRNA in low vs. high motility spermatozoal and low vs. high fertility bull (Sellem et al, 2020;Keles et al, 2021).…”

“…The miR-26a also participates in PTEN and PI3K/AKT signaling pathways, affecting sperm viability and motility (Dai et al, 2019). In another study, miR-34b-3p and miR-100-5p were also significantly over-expressed in spermatozoa of high fertility bull compared to those of low fertility bull (Keles et al, 2021). The miRNAs, previously known to be expressed testis, were also detected in bull spermatozoa and included miR-34b/c miRNA cluster, which plays vital roles in chromatin condensation during spermiogenesis (Capra et al, 2017).…”

Sperm-borne sncRNAs: potential biomarkers for semen fertility?

“…Many miRNAs differentially expressed between fertile and sub-fertile bulls have also been identified, such as bta-miR-9-5p, bta-miR-10a-5p, bta-miR 19b-3p, bta-miR-27a-5p, bta-miR-34c, bta-miR-98, bta miR126-5p, bta-miR-142-5p, bta-miR-148b-3p, bta-miR-182, bta-miR-320a, bta-miR-329a, bta-miR-449a, bta-miR-502-5p, bta-miR-1249bta-miR 19b-3p, bta-miR-27a-5p, bta-miR-34c, bta-miR-98, bta miR126-5p, bta-miR-142-5p, bta-miR-148b-3p, bta-miR-182, bta-miR-320a, bta-miR-329a, bta-miR-449a, bta-miR-502-5p, bta-miR- -3p, bta-miR-1839bta-miR 19b-3p, bta-miR-27a-5p, bta-miR-34c, bta-miR-98, bta miR126-5p, bta-miR-142-5p, bta-miR-148b-3p, bta-miR-182, bta-miR-320a, bta-miR-329a, bta-miR-449a, bta-miR-502-5p, bta-miR- , bta-miR-2284y (Fagerlind et al 2015Perkins et al 2020). The expression level of nine miRNAs (miR-9-5p, miR-34c, miR-423-5p, miR-449a, miR-5193-5p, miR-1246, miR-2483-5p, miR-92a, miR-21-5p) were significantly correlated to non-return rate after insemination with sexed semen (Keles et al 2021). Differential expression of 11 miRNAs was observed between high and low fertility bulls, including miR-33b, miR-126-5p, miR-205, miR-505, miR-532, miR-500 and miR-542-5p which were overexpressed in high fertility bulls and miR-15a, miR 29, miR-216b and miR-339a which were downregulated in high fertility bulls (Alves et al 2019;Menezes et al 2020).…”

The epigenome of male germ cells and the programming of phenotypes in cattle

“…These inconsistencies may be related to both technical issues (e.g., because of the different approaches used to generate DNA methylation data and parameters used to detect differential methylation) and biological issues (different scores used to assess bull fertility, different breeds, high interindividual variability, and small numbers of samples involved in each study). Likewise, several studies have focused on the association between interindividual variations in the sperm sncRNA content and semen quality or bull fertility, highlighting several miRNAs ( Capra et al, 2017 ; Alves et al, 2020 ; Keles et al, 2021 ). In addition, other sncRNAs such as tRF-Gly or tRF-Glu may represent another source of fertility biomarkers, as suggested by their differential expression according to in vitro fertilization outcomes in humans ( Hua et al, 2019 ).…”