Identification of Functional Single Nucleotide Polymorphisms in Porcine Gene Associated with Estrus Behavior Difference Between Large White and Mi Gilts

Steroid hormone levels are associated with estrous behavior, which affects timely mating and reproductive efficiency in pigs. 17β-hydroxysteroid dehydrogenase type 14 ( modulates steroid synthesis and metabolism. To identify the functional single nucleotide polymorphisms (SNPs) in the porcine gene, ear tissues from Large White and Mi gilts were collected to extract genomic DNA. Variable lengths of truncated promoter of gene were used to determine the promoter activity by a dual luciferase reporter system. The vector HSD17B14 or HSD17B14 was transfected into porcine granulosa cells (GCs). The core promoter region was identified between -72bp and -218bp. Six of seven SNPs had significant differences of allele frequency between Large White and Mi gilts. The plasmids with the wild genotype AA of rs329427898 maintained a smaller fraction of promoter activity compared with the plasmids with the mutant genotype GG, while the plasmids with wild the genotype TT of rs319864566 had a greater promoter activity than the plasmids with the mutant genotype CC. A missense mutation (Phe73Val) caused changes in the structural dynamics and function of the HSD17B14 protein. The highly expressed HSD17B14 degraded less estradiol into estrone, while the relatively lowly expressed HSD17B14 degraded more estradiol into estrone, suggesting the protein activity of HSD17B14 was greater than that of HSD17B14. Moreover, the HSD17B14 group has a greater apoptosis rate of porcine GCs. The gene could been used as a candidate molecular marker for estrus behavior in pigs.