Coordinated alternation of DNA methylation and alternative splicing of PBRM1 affect bovine sperm structure and motility

DNA methylation and gene alternative splicing drive spermatogenesis. In screening DNA methylation markers and transcripts related to sperm motility, semen from three pairs of full-sibling Holstein bulls with high and low motility was subjected to reduced representation bisulphite sequencing. A total of 948 DMRs were found in 874 genes (gDMRs). Approximately 89% of gDMR-related genes harboured alternative splicing events, including <i>SMAD2, KIF17</i>, and <i>PBRM1</i>. One DMR in exon 29 of <i>PBRM1</i> with the highest 5mC ratio was found, and hypermethylation in this region was related to bull sperm motility. Furthermore, alternative splicing events at exon 29 of <i>PBRM1</i> were found in bull testis, including <i>PBRM1-complete, PBRM1-SV1</i> (exon 28 deletion), and <i>PBRM1-SV2</i> (exons 28–29 deletion). <i>PBRM1-SV2</i> exhibited significantly higher expression in adult bull testes than in newborn bull testes. In addition, <i>PBRM1</i> was localized to the redundant nuclear membrane of bull sperm, which might be related to sperm motility caused by sperm tail breakage. Therefore, the hypermethylation of exon 29 may be associated with the production of <i>PBRM1-SV2</i> in spermatogenesis. These findings indicated that DNA methylation alteration at specific loci could regulate gene splicing and expression and synergistically alter sperm structure and motility.