Transcriptome-wide m6A profiling reveals mRNA post-transcriptional modification of boar sperm during cryopreservation.

Background Cryopreservation induces transcriptomic and epigenetic modifications that strongly impairs sperm quality and function, and thus decrease reproductive performance. N6-methyladenosine (m6A) RNA methylation varies in response to stress and has been implicated in multiple important biological processes, including post-transcriptional fate of mRNA, metabolism, and apoptosis. This study aimed to explore whether cryopreservation induces m6A modification of mRNAs associated with sperm energy metabolism, cryoinjuries, and freezability. Results The mRNA and protein expression of m6A modification enzymes were significantly dysregulated in sperm after cryopreservation. Furthermore, m6A peaks were mainly enriched in coding regions and near stop codons with classical RRACH motifs. The mRNAs containing highly methylated m6A peaks (fts vs. fs) were significantly associated with metabolism and gene expression, while the genes with less methylated m6A peaks were primarily involved in processes regulating RNA metabolism and transcription. Furthermore, the joint analysis of DMMGs and differentially expressed genes indicated that both of these play a vital role in sperm energy metabolism and apoptosis. Conclusions Our study is the first to reveal the dynamic m6A modification of mRNAs in boar sperm during cryopreservation. These epigenetic modifications may affect mRNA expression and are closely related to sperm motility, apoptosis, and metabolism, which will provide novel insights into understanding of the cryoinjuries or freezability of boar sperm during cryopreservation.