Effect Of Myostatin Gene Mutaiton On Bovine Bile Acids And Lipid Metabolism

Myostatin(MSTN)is a negative regulator of skeletal muscle development.The lack of MSTN will lead to the decrease of fat deposition and the increase of muscle content,resulting in "double muscle" phenomenon.Bile acid is synthesized by cholesterol in the liver and is the final product of cholesterol metabolism.Bile acid and bile acid receptor play an important role in lipid metabolism.Bile acid metabolism and lipid metabolism are potentially associated with MSTN.In this experiment,the serum and liver tissues of first filial generation of MSTN gene knockout Luxi double muscle cattle were used as experimental materials,to research the effects of MSTN gene mutation on bile acid metabolism and lipid metabolism.Firstly,the physiological and biochemical indexes of serum and the expression of MSTN in serum and liver of 18 month old cattle were detected to compare the physiological and metabolic differences between double muscle Luxi cattle and wild-type Luxi cattle after MSTN mutation;Secondly,the liver non targeted lipid metabolism group and liver bile acid targeted metabolism group were analyzed to compare the physiological and metabolic differences between double muscle Luxi cattle and wild-type Luxi cattle after MSTN mutation;Finally,we detected the expression of genes related to bile acid metabolism and lipid metabolism to research the effect of MSTN gene mutation on bile acid metabolism and lipid metabolism.The results showed that:(1)MSTN gene mutation F1 cattle were in good health,most of the blood physiological and biochemical indexes had no significant difference with wild-type Luxi cattle,but some indexes related to lipid metabolism such as cholesterol,high-density lipoprotein and bile acid content were significantly higher than wild-type cattle;(2)After MSTN gene mutation,the expressions of bile acid receptor FXR were significantly decreased,and the expressions of CYP7A1,CYP27A1,LRH-1,BAAT,SLUT2A1,BSEP and ABCB4 genes related to primary bile acid and conjugated bile acid synthesis and bile acid efflux were significantly increased,which induced the increase of bile acid level in cattle;(3)After MSTN gene mutation,the expressions of lipid metabolism-related genes regulated by bile acid and its receptor FXR,such as PPARγ,SREBP,and ACACA,were significantly down-regulated;the expressions of genes involved in lipolysis,such as PPARα and CREB1,were significantly up-regulated.The contents of some saturated fatty acids and polyunsaturated fatty acids increased significantly.It is speculated that the MSTN mutation affects the metabolism of bile acids,which in turn affects the changes in the composition of liver free fatty acids,especially polyunsaturated fatty acids,promotes the transport and decomposition of fat in the body,and improves energy utilization efficiency.