Small RNA expression patterns in seminal plasma exosomes isolated from semen containing spermatozoa with cytoplasmic droplets versus regular exosomes in boar semen.

Multiple physiological pathways are controlled by exosomes. Exosomes may be found in seminal plasma where they carry functional molecules to the sperm, such as microRNAs (miRNAs). Sperm cytoplasmic droplets (CDs) are remnants of cytoplasm, and their migration is a morphological characteristic of epididymal maturation. However, miRNA expression patterns in seminal plasma exosomes found in semen containing spermatozoa with CDs versus regular exosomes in boar semen have not been examined. In this study, seminal plasma exosomes were isolated from semen containing spermatozoa with CDs and miRNA expression profiles were analyzed. A total of 348 known and 206 new miRNAs were identified. Sixteen miRNAs were significantly differentially expressed. Of these, 13 miRNAs (ssc-miR-101, ssc-miR-148a-5p, ssc-miR-184, ssc-miR-202-3p, ssc-miR-221-5p, ssc-miR-2483, ssc-miR-29a-3p, ssc-miR-29c, ssc-miR-31, ssc-miR-362, ssc-miR-500-5p, ssc-miR-542-3p, and ssc-miR-769-5p) were significantly upregulated, whereas three miRNAs (ssc-miR-1249, ssc-miR-155-5p, and ssc-miR-296-5p) were significantly downregulated. GO and KEGG pathway analyses showed that these targeted genes were enriched for functions such as metabolic process, reproductive process, proteasome, ubiquitin mediated proteolysis, and oxidative phosphorylation. Therefore, seminal plasma exosomes are predicted to play a key role in the regulation of sperm CDs.