Splicing-related single nucleotide polymorphism of RAB, member of RAS oncogene family like 2B (RABL2B) jeopardises semen quality in Chinese Holstein bulls

Reprod Fertil Dev. 2017 Nov;29(12):2411-2418. doi: 10.1071/RD17111.

Abstract

RAB, member of RAS oncogene family like 2B (RABL2B) is a member of a poorly characterised clade of the RAS GTPase superfamily, which plays an essential role in male fertility, sperm intraflagellar transport and tail assembly. In the present study, we identified a novel RABL2B splice variant in bovine testis and spermatozoa. This splice variant, designated RABL2B-TV, is characterised by exon 2 skipping. Moreover, a single nucleotide polymorphism (SNP), namely c.125G>A, was found within the exonic splicing enhancer (ESE) motif, indicating that the SNP caused the production of the RABL2B-TV aberrant splice variant. This was demonstrated by constructing a pSPL3 exon capturing vector with different genotypes and transfecting these vectors into murine Leydig tumour cell line (MLTC-1) cells. Expression of the RABL2B-TV transcript was lower in semen from high- versus low-performance bulls. Association analysis showed that sperm deformity rate was significantly lower in Chinese Holstein bulls with the GG or GA genotype than in bulls with the AA genotype (P<0.05). In addition, initial sperm motility was significantly higher in individuals with the GG or GA genotype than in individuals with the AA genotype (P<0.05). The findings of the present study suggest that the difference in semen quality in bulls with different RABL2B genotypes is generated via an alternative splicing mechanism caused by a functional SNP within the ESE motif.

MeSH terms

  • Alternative Splicing
  • Animals
  • Cattle
  • Cell Line, Tumor
  • Exons
  • Genotype*
  • Male
  • Polymorphism, Single Nucleotide*
  • Promoter Regions, Genetic
  • Semen Analysis
  • Sperm Motility / genetics*
  • Testis / metabolism
  • rab GTP-Binding Proteins / genetics*
  • rab GTP-Binding Proteins / metabolism

Substances

  • rab GTP-Binding Proteins