The Effect Of ACSL6 On Milk Fat Synthesis In Mammary Gland Of Dairy Cow

Milk is an indispensable source of food because it is rich in a lot of nutrients we need.The milk fat in milk is more and more concerned because it can provide the nutrients we need and can be converted into a lot of energy in the body.Nowadays,whether high-quality milk can be produced to meet people's needs has become an important issue in the development of high-quality food,but the current milk production of dairy cows in China is not high enough,and the quality of milk needs to be improved.Therefore,improving the quality of milk and producing high-quality milk with sufficient milk fat is a problem that we urgently need to solve.Long-chain acyl-Co A synthetase 6(ACSL6)is an enzyme present in the plasma membrane of the cell and is mainly expressed in the brain and skeletal muscle.It activates fatty acids by connecting Co A with fatty acids.ACSL6 has the same effect on saturated fatty acids and polyunsaturated fatty acids with C16-C20 skeleton,and it can participate in the regulation of lipid droplet development and the formation of triglycerides and cholesterol esters.However,in the mammary glands of dairy cows,the expression of ACSL6 and its role in the synthesis of milk fat are unclear.In order to study the relationship between ACSL6 and milk fat synthesis,this experiment first used q PCR to detect the expression of each gene of the ACSL family in the milk mammary glands of cows at different lactation stages,and at the level of milk mammary gland tissues,using Western blot to detect ACSL6 protein in lactation and dry milk.The results showed that compared with the dry period,the m RNA expression of ACSL1 and ACSL6 in the mammary gland of lactating cows increased significantly,and the protein expression of ACSL6 also increased significantly,indicating that the expression of ACSL6 is related to the lactation process.BHBA is the main precursor of milk fat synthesis in ruminants.It can affect the milk fat synthesis of cow mammary epithelial cells.Acetate is the main energy source and substrate for cow milk synthesis.In order to study the relationship between ACSL6 and milk fat synthesis in dairy mammary glands,we used a fat-free and serum-free cell culture system as a control group.The treatment group added 8 mmol / L sodium acetate and 1 mmol / L BHBA to establish a high milk fat synthesis model of mammary epithelial cells.The results showed that in this cell model,compared with the control group,the content of TAG and the fat droplets were significantly increased.At the same time,m RNA expression of FASN and ACC also increased significantly under this model.They are important genes in the process of milk fat synthesis.These results indicate that the cell model of high milk fat synthesis capacity established by adding sodium acetate and BHBA can significantly promote milk fat synthesis.Under this model,we first used q PCR to detect the expression of various genes in the ACSL family.The results showed that the m RNA expression of ACSL1,ACSL3,and ACSL6 in the cell model were increased significantly.The protein expression level of ACSL6 was also significantly increased in the cell model.We have adopted gene overexpression and suppression techniques to study the relationship between ACSL6 and milk fat synthesis in mammary gland.The effect of ACSL6 gene overexpression and inhibition on the content of TAG in cells was examined.The results showed that after overexpression of ACSL6 gene,the level of TAG in the cells increased significantly;and after ACSL6 gene was suppressed,the content of TAG in cells decreased significantly.The above results indicate that ACSL6 plays a positive role in the synthesis of milk fat in the mammary glands of dairy cows.In order to further study the signal pathway that regulates the expression of ACSL6 in the mammary gland of dairy cows,and thus the synthesis of milk fat,we detected by Western blot in the high-fat synthetic cell model that m TOR and its downstream signaling molecules 4E-BP1 and P70S6 K protein phosphorylation levels were significantly increased,indicating that the m TOR signaling pathway is activated in this cell model.Subsequently,rapamycin,a specific inhibitor of the m TOR signaling pathway,was added to a cell model with high milk fat synthesis capacity.The results showed that after adding rapamycin,the protein phosphorylation level of m TOR and its downstream signaling molecules 4E-BP1 and P70S6 K was significantly reduced,and the intracellular TAG level was significantly reduced,indicating that the m TOR signaling pathway was inhibited.At this time,the protein expression level of ACSL6 also decreased significantly,indicating that the expression of ACSL6 was regulated by the m TOR signaling pathway.The above results indicate that in the mammary glands of dairy cows,the addition of a substrate synthesized by milk fat can cause the m TOR signaling pathway to regulate the expression of ACSL6,thereby regulating milk fat synthesis.The research results provide more basis for scientifically regulating milk quality of cows through molecular technology,and provide experimental and theoretical basis for clarifying the regulation system of milk fat synthesis.