GSE110443
Analysis of the small non-coding RNA content of bovine oviductal extracellular vesicles during the estrous cycle
The success of the early reproductive events depends on an appropriate communication between gametes/embryos and the oviduct. Extracellular vesicles (EVs) contained in oviductal secretions have been suggested as new players in mediating this crucial cross-talk by transferring their cargo (e.g. proteins, mRNA and small ncRNA) from cell to cell. However, little is known about the oviduct EVs composition and their implications in reproductive success. The objective of our study was to determine the changes of oviductal EVs small ncRNA content under the hormonal influence during the estrous cycle. Methods: EVs, exosomes and microvesicles, were isolated from bovine oviductal fluid at different stages of the estrous cycle (postovulatory-stage, early luteal phase, late luteal phase and pre-ovulatory stage). RNA enriched for short molecules was isolated and used for the preparation of small RNA-seq libraries. RNA-sequencing was performed on an Illumina HiSeq 2500. The obtained sequence reads that passed quality filters were annotated by BLAST alignment to various sets of non-coding and coding RNAs. Read counts were calculated based on the frequency of unique sequences after removal of PCR duplicates. Statistical analysis was done with EdgeR to identify differential small ncRNA abundance across the different stages of the estrous cycle. Results: Small RNA-Seq identified the presence of different types of ncRNAs (miRNAs, rRNA fragments, tRNA fragments, snRNA, snoRNA, and other ncRNAs), which were partially also under hormonal influence. Major differences were found between post-ovulatory and early luteal and the rest of the stages for small ncRNAs. Interesting miRNAs identified in oviductal EVs, miR-34b and miR-449a, showed differential abundance among stages. Dysregulation of these miRNAs has been associated with defective cilia in the oviduct and infertility. Conclusions: Our findings represent the first extensive oviductal signature of bovine oviductal EVs miRNA content and contribute to a better understanding of the role of EVs as modulators of gamete/embryo-maternal interactions. Overall design: Small ncRNA profiles of bovine oviductal extracellular vesicles during the estrous cycle were generated by small RNA-sequencing of samples collected from 4 stages with 5 replicates per stage, using Illumina HiSeq 2500.