Effects of SNPs and alternative splicing within HGF gene on its expression patterns in Qinchuan cattle

Background: Identification of genetic variants, including SNPs (Single Nucleotide Polymorphisms), CNVs (Copy Number Variations) and alternative splicing, within functional genes has received increasing attention in animal science research. HGF (Hepatocyte Growth Factor) is a very important growth factor that works as a mitogen or a morphogen during tissue growth, development and regeneration. However, to date, the functions of genetic variants within the bovine HGF gene, particularly their effects on mRNA expression, have not been determined well. Results: The present study aimed to perform association analysis between genetic variants and mRNA expression for the bovine HGF gene in Qinchuan cattle using various strategies, including PCR-RFLP (Restriction Fragment Length Polymorphism), qPCR (Quantitative Real-time quantitative PCR), TA cloning, DNA sequencing and bioinformatics analysis. A total of five SNPs were identified and only SV1 locus significantly affected HGF mRNA expression in fetal skeletal muscle (P < 0.05). Heterozygous genotype individuals showed significantly higher HGF expression (P < 0.05), which was significantly greater in the CTCCAGGGTT combined genotype than that in the CCCCGGGGTT combined genotype (P < 0.05). In addition, two alternative splicing variations, HGF-W and HGF-M, were identified, which resulted from alternative 3' splice sites of exon 5, and HGF-W showed higher mRNA levels than HGF-M in all tissues. Conclusion: In summary, genetic variations within the HGF gene affected mRNA expression. These findings provide new insight into the molecular characteristics and functions of bovine HGF.