Sperm miRNAs— potential mediators of bull age and early embryo development

Abstract

Background Sperm miRNAs were reported to regulate spermatogenesis and early embryonic development in some mammals including bovine. The dairy cattle breeding industry now tends to collect semen from younger bulls under high selection pressure at a time when semen quality may be suboptimal compared to adult bulls. Whether the patterns of spermatic miRNAs are affected by paternal age and/or impact early embryogenesis is not clear. Hence, we generated small non-coding RNA libraries of sperm collected from same bulls at 10, 12, and 16 months of age, using 16 months as control for differential expression and functional analysis. Results We firstly excluded all miRNAs present in measurable quantity in oocytes according to the literature. Of the remaining miRNAs, ten sperm-borne miRNAs were significantly differentially expressed in younger bulls (four in the 10 vs 16 months contrast and six in the 12 vs 16 months contrast). Targets of miRNAs were identified and compared to the transcriptomic database of two-cell embryos, to genes related to two-cell competence, and to the transcriptomic database of blastocysts. Ingenuity pathway analysis of the targets of these miRNAs suggested potential influence on the developmental competence of two-cell embryos and on metabolism and protein synthesis in blastocysts. Conclusions The results showed that miRNA patterns in sperm are affected by the age of the bull and may mediate the effects of paternal age on early embryonic development.

miR-301a-5p Regulates TGFB2 during Chicken Spermatogenesis

“…Our previous studies also showed that miR-202-5p expressed and regulated LIMK2 during the early spermatogonial stage in chickens [15]. Meanwhile, many miRNAs have been found in spermatozoa and have been shown to be expressed differently in high and poor fertility bulls [19][20][21][22]. Besides, a previous study showed that miRNA also regulates spermatogenesis in humans, mice, etc.…”

The Epigenetics of Gametes and Early Embryos and Potential Long-Range Consequences in Livestock Species—Filling in the Picture With Epigenomic Analyses

“…These sperm RNA modifications could alter RNA structure and thus the interactions between RNA, DNA and proteins, leading to potentially greater consequences and wide-ranging effects (Zhang et al, 2018 ). Wu et al ( 2020b ) identified distinct differences in sperm-borne miRNAs from bulls of different ages, several of which targeted genes expressed in early embryos. This newly appreciated role of the sperm as RNA-based carriers of hereditary information provides a promising angle with which to understand aging and the etiology of environmentally induced disease beyond the initial exposure.…”

Effect of Sperm Cryopreservation on miRNA Expression and Early Embryonic Development

“…We examined the expression level of potential genes which enriched in these significant terms. Considering that miRNA negatively regulates gene expression by degrading target mRNA (Wu et al, 2020), we found that the expression level of Pten was significantly increased at all developmental stages (Figure 4B); other genes, such as Jmy, were only upregulated on Day2, while Bbc3 and Cdk19 were downregulated firstly and upregulated on Day3.5 (Figures 4C-F). We also detected some downregulated target genes of miR-148b-3p on Day1 and Day2, including Esr1, Robo1, and Ino80, and on Day3.5 including Robo1, Ino80, and Arpp19 (Figures 4G-Y).…”