GENOME-WIDE ANALYSIS OF SEMEN MICRORNAS AS POTENTIAL BIOMARKERS FOR BULL FERTILITY
Loading...
Date
2022
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ICAR-SRS-NDRI, BENGALURU
Abstract
The bull fertility has been choreographed by the physical, endocrinological, genetic and epigenetic factors, among which the last two factors are quite intriguing as well as intricate to comprehend. Due to the failure of semen evaluation assays in fertility prediction, the omics technologies emerged to evaluate molecules i.e., DNA, RNA and protein in semen. Though miRNAs were studied extensively as a biomarker for various diseases, their ability in fertility prediction is barely addressed. Therefore, the present study analyzed the genome-wide miRNAs using small RNA next gen seq in semen of bulls with contrasting fertility, with the aim to find out fertility associated miRNAs. We detected 2628 miRNAs (Known-534, Novel-2094) in bull semen. A total of 1002 miRNAs were detected in sperm (Known-349, Novel-653) while 2005 miRNAs were detected in seminal plasma (Known-511, Novel-1494). The 250 known miRNAs were detected common between high- and low-fertile bull sperm, in which 77 were upregulated and 54 were downregulated. The 237 known miRNAs were detected common between high- and low-fertile bull seminal plasma, in which 100 were upregulated and 94 were downregulated in low-fertile bulls. The miRNAs involved in spermatogenesis (miR-135a, -197), sperm motility (miR-151-5p, -874), embryonic development (miR-34c, -451) and epigenetic inheritance (miR-1) were among the top 20 differentially expressed miRNAs in sperm and seminal plasma. The target genes of 10 abundantly expressed known miRNAs in sperm and seminal plasma of low-fertile bulls were predicted to be involved in MAPK signaling pathway and PI3K-Akt signaling pathway which are related to male fertility. Among the 2094 miRNAs novel to Bos taurus genome, 2071 miRNAs were novel to whole miRbase 22.1 database. Validation of ten select miRNAs in sperm and seminal plasma samples revealed that miR-2285bu and bull-miR-291 were significantly upregulated in low-fertile than high-fertile bulls. Bull-miR-291 and bull-miR-772 were not reported earlier in any organism but our study confirmed their expression in both bull sperm and seminal plasma using sequencing and qPCR. Moreover, we found bull-miR-291 to be related to bull fertility. The altered MAPK and PI3K-Akt signaling pathway were reported earlier as the reason for infertility, but this study points out miRNAs might be the major player in the background for bull infertility by targeted repression of mRNAs involved in these pathways.