Analysis of the mRNA 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 mRNA 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). Total RNA was isolated and used for the preparation of RNA-seq libraries. RNA-sequencing was performed on an Illumina HiSeq 2500. The obtained sequence reads that passed quality filters were mapped to the bovine genome sequence using Hisat 2. Read counts were calculated with QuasR Qcount and statistical analysis with EdgeR to identify differential mRNA abundance across the different stages of the estrous cycle. Results: RNA-sequencing identified 903 differentially expressed transcripts (FDR<0.001) in bovine oviductal EVs across the estrous cycle. Major differences were found between post-ovulatory and the rest of the stages analyzed.Functional annotation of the differentially abundant mRNAs identified functions related to cilia expression, exosome/vesicles, and many transcripts encoding ribosomal proteins. Conclusions: Our findings represent the first extensive oviductal signature of bovine oviductal EVs mRNA content and contribute to a better understanding of the role of EVs as modulators of gamete/embryo-maternal interactions. Overall design: Messenger RNA profiles of bovine oviductal extracellular vesicles during the estrous cycle were generated by RNA-sequencing of samples collected from 4 stages with 5 replicates per stage, using Illumina HiSeq 2500

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Almiñana C, Tsikis G, Labas V, Uzbekov R, da Silveira JC, Bauersachs S, Mermillod P