Overexpression Of SCD1 Gene Promotes Lipogenesis In Bovine Preadipocytes

Stearoyl coenzyme A desaturase 1(SCD1)is a rate limiting enzyme that catalyzes the formation of monounsaturated fatty acid(MUFA)from saturated fatty acid(SFA).It is positively correlated with intramuscular fat content of cattle.However,the mechanism of SCD1 gene in lipogenesis is still unclear.In addition,a variety of free fatty acids are natural ligands of peroxisome proliferator activated receptor gamma(PPARγ),which is the main regulator of preadipocyte differentiation.However,it is also unclear whether SCD1 gene promotes lipogenesis by changing PPARγ receptor activity.In this study,SCD1 gene was used as the research object and adenovirus mediated overexpression technology was used to study the effect of SCD1 gene on lipid production of bovine preadipocytes at molecular and cellular levels.The main results are as follows(1)Spatiotemporal expression profile of bovine SCD1 geneReal time quantitative PCR(qRT-PCR)was used to detect the expression of SCD1 gene in tissues of 24-month-old Qinchuan beef cattle.The results showed that the expression levels of SCD1 gene in subcutaneous fat and perirenal fat were significantly higher than those in other tissues;the expression levels of SCD1 gene were up-regulated continuously from 4-day-old to 24-month-old in Qinchuan beef cattle longissimus dorsi and perirenal fat In addition,qRT-PCR was used to detect the sequential expression of SCD1 gene during the differentiation of bovine preadipocytes.The results showed that the expression of SCD1 gene peaked at the second day(day,d)after differentiation of bovine preadipocytes,and then decreased gradually.(2)Overexpression of SCD1 gene promotes lipogenesis of bovine preadipocytesThe recombinant adenovirus overexpressing SCD1 gene successfully infected bovine preadipocytes,and the optimal multiplicity of infection(MOI)value was 30,and the optimal MOI value of control empty adenovirus was 25.The results of qRT-PCR and Western blot showed that SCD1 gene was successfully expressed in bovine preadipocytes.After overexpression of SCD1 gene,oil red O staining showed that the lipid droplets of bovine preadipocytes increased.Further quantitative detection showed that the expression of PPARγand C/EBPα did not change significantly,but the expression levels of lipid synthesis genes FABP4,FASN and ACCα were significantly increased.(3)Overexpression of bovine SCD1 gene can enhance PPARγ receptor activityIn order to verify whether SCD1 gene has effect on PPARγ receptor activity,PPRE-X3-TK luc plasmid was transfected into bovine preadipocytes.The results of dual-luciferase reporter system showed that overexpression of SCD1 gene could significantly enhance the activity of PPARγ receptor.(4)Overexpression of SCD1 gene increased the content of MUFA in bovine adipocytesThe results of GC-MS showed that overexpression of SCD1 gene significantly increased the contents of MUFA: palmitoleic acid(cis-9-C16:1)and oleic acid(cis-9-C18:1)and the desaturation index of C16:1 and C18:1 in bovine adipocytes.In conclusion,in this study,we used SCD1 gene as the research object and bovine preadipocytes as the cell model,and found that overexpression of SCD1 gene could enhance PPARγ receptor activity and promote lipogenesis of bovine preadipocytes.The results of this study provide a theoretical basis for further study of SCD1 gene on intramuscular fat formation and increase the proportion of unsaturated fatty acids,and also provide a new direction for beef cattle breeding.