Effects of polymorphism of the GPAM gene on milk quality traits and its relation to triglyceride metabolism in bovine mammary epithelial cells of dairy cattle

Mitochondrial glycerol-3-phosphate acyltransferase (GPAM) catalyses the initial and rate-regulated first-stage pathway of glycerol lipid synthesis and helps to allocate acyl-CoA (acyl-coenzyme A) to triglyceride (TG) synthesis and away from degradation pathways in animal lipometabolism-related pathways. In this study, RNA interference (RNAi) and GPAM gene overexpression were used to examine the correlation between the expression of GPAM and adipogenesis in bovine mammary epithelial cells (bMECs). Additionally, three novel polymorphisms were identified within the bovine key functional domain of GPAM with Sanger sequencing. The relationship between variants of the GPAM gene and milk quality traits of Chinese Holstein cows was then analysed using statistical methods. The results showed that knockdown of the GPAM gene significantly reduced the synthesis of triglycerides in the bMECs ([Formula: see text] [Formula: see text] 0.05), whereas the overexpression of the GPAM gene significantly increased the synthesis of TG ([Formula: see text] [Formula: see text] 0.05). In Chinese Holstein dairy cattle, the polymorphic locus of the GPAM gene E20-3386G [Formula: see text] A was significantly correlated with fat, protein and somatic cell count ([Formula: see text] [Formula: see text] 0.05); I18-652A [Formula: see text] G was significantly correlated with fat, total fat content, protein, dry matter and somatic cell count ([Formula: see text] [Formula: see text] 0.05); and I18-726A [Formula: see text] G was significantly correlated with protein, milk yield, dry matter and somatic cell count ([Formula: see text] [Formula: see text] 0.05). Specifically, individuals with the AA genotype of the I18-652A [Formula: see text] G and E20-3386G [Formula: see text] A polymorphic loci had a higher milk fat percentage ([Formula: see text] [Formula: see text] 0.05). In summary, GPAM plays a pivotal role in the intracellular regulation of triglyceride, and its mutations could work as a competent molecular marker for selective breeding in dairy cattle.