Bovine lipid metabolism related gene GPAM: Molecular characterization, function identification, and association analysis with fat deposition traits

Glycerol-3-phosphate acyltransferase mitochondrial (GPAM) is the enzyme that catalyzes the initial and committed step of glycerolipid synthesis in animal lipometabolism related pathway. In the present study, the correlation of GPAM expression level with adipogenesis was examined in vitro by RNAi and gene expression to silencing and over-expression of GPAM gene in BEF cells. And then, 2 novel polymorphisms were identified within key functional domain of bovine GPAM gene by sequencing and the relationship between variants of GPAM gene with fat deposition traits of Chinese Simmental-cross steers was analyzed using statistical methods. The result showed that the knockdown of GPAM expression significantly reduced the synthesis of triglycerides and expression of lipid metabolism-related gene in BEF cells (p<0.05), and the over-expression of GPAM could significantly increased the levels of triglyceride and expression of lipid metabolism-related gene (p<0.05). The results of the correlation analysis also showed that cattle with TC genotype of GPAM E20-2823C>T was significantly associated with fatty acid composition of intramuscular fat (had higher content of arachidic acid, eicosenoic acid, and arachidonic acid), individuals with A-allele homozygotes and AG-allele heterozygotes of E20-3386G>A both had higher content of myristic acid, α-linolenic acid, and linoleic acid in intramuscular fat than those with G-allele homozygotes (p<0.05). The individuals with AA genotype of E20-3386G>A was significantly associated with higher marbling score, and the individuals with CC homozygotes of E20-2823C>T had higher GFW and omasum fat weight in beef cattle population. GPAM play a pivotal role in the regulation of cellular triacylglycerol and phospholipid levels, and its mutations could serve as a useful molecular marker used for marker assisted selection in beef cattle breeding process.