Characteristics of miRNAs Present in Bovine Sperm and Associations With Differences in Fertility

Abstract

Small non-coding RNAs have been linked to different phenotypes in bovine sperm, however attempts to identify sperm-borne molecular biomarkers of male fertility have thus far failed to identify a robust profile of expressed miRNAs related to fertility. We hypothesized that some differences in bull fertility may be reflected in the levels of different miRNAs in sperm. To explore such differences in fertility that are not due to differences in visible metrics of sperm quality, we employed Next Generation Sequencing to compare the miRNA populations in Bos taurus sperm from bulls with comparable motility and morphology but varying Sire Conception Rates. We identified the most abundant miRNAs in both populations (miRs -34b-3p; -100-5p; -191-5p; -30d-4p; -21-5p) and evaluated differences in the overall levels and specific patterns of isomiR expression. We also explored correlations between specific pairs of miRNAs in each population and identified 10 distinct pairs of miRNAs that were positively correlated in bulls with higher fertility and negatively correlated in comparatively less fertile individuals. Furthermore, 8 additional miRNA pairs demonstrated the opposite trend; negatively correlated in high fertility animals and positively correlated in less fertile bulls. Finally, we performed pathway analysis to identify potential roles of miRNAs present in bull sperm in the regulation of specific genes that impact spermatogenesis and embryo development. Together, these results present a comprehensive picture of the bovine sperm miRNAome that suggests multiple potential roles in fertility.

BPA Decreases PDCD4 in Bovine Granulosa Cells Independently of miR-21 Inhibition

“…For example, miR-483 is a self-regulating miRNA that indirectly upregulates its own activating transcription factor, USF1, which subsequently enhances its own transcription [ 54 ]. Hill & Tran [ 55 ] extensively discuss known miRNA-miRNA interactions and their potential roles in various cancers, and recent work has identified miRNA-miRNA correlations associated with male fertility [ 56 ]. Although there is no documented interaction between miR-21 and miR-155, our findings suggest that miR-21 is capable of regulating miR-155 through direct or indirect interactions.…”

MicroRNAs in Ruminants and Their Potential Role in Nutrition and Physiology

“…The most abundant miRNAs in both populations were identified (miRs -34b-3p, -100-5p, -191-5p, -30d-4p, and -21-5p), and variations in both the total levels and particular patterns of isomiR expression were assessed. The findings offer a thorough description of the bovine sperm miRNAome and point to numerous potential roles in fertility [ 40 ]. To support the use of milk fat globules as a source of small non-coding RNAs to diagnose mastitis, their abundance from five cows before and after lipopolysaccharide (LPS) challenge was compared.…”