Role And Mechanism Of Adipose Triglyceride Lipase ATGL In Adipocytes Triacylglycerol Accumulation

The quality of beef including tenderness and flavor can be improved by inducingintramuscular fat composition. From the cellular level point of view, body fat content is amacro expression of TG accumulation in adipocytes. Previous studies in vivo and in vitro onvarious kinds of animals elucidated that adipocytes proliferation and differentiation andmetabolism at cellular level were regulated by some important transcription factors. Adiposetriglyceride lipase (ATGL) is a key enzyme in adipocytes，with roles in degradation oftriacylglycerols stored in lipid droplets (LDs). However, there is little information concerningthe function of bovine ATGLgenes. Herein, we designed and selected an effective shRNA(small hairpin RNA) against bovine ATGL, constructed a corresponding adenovirus(AD-ATGL) and we also constructed recombinant adenovirus plasmids of ATGLgene(PAD-ATGL), then we found the potential specific effects of ATGL during TG accumulationin bovine adipocytes. Furthermore, we also investigated their effects on several other fat celldifferentiation related and metabolism related genes. The main results were as follows:(1) The complete CDS sequences of bovine ATGLgenes were successfully obtained. Wefound the expression way of ATGL mRNA during bovine adipocytes differentiation.(2) Recombinant adenovirus carrying bovine ATGL complete CDS fragments weresuccessfully constructed, and further packaged and amplified in HEK293A cell lines.(3) Four pairs of ATGL shRNA were designed. Recombinant adenovirus carrying bovineATGL shRNA fragments were successfully constructed, and further packaged and amplifiedin HEK293A cell lines.(4) We found a positive correlation between TG accumulation in adipocytes and ATGLmRNA expression. Oil O staining results demonstrated that over-expression of ATGLinhibited adipose differentiation and reduced the number of lipid drops for30%. However,adenovirus–mediated interference of ATGL promoted adipose differentiation and increasedthe number of lipid drops for20%.(5) Real-time PCR results indicated over-expression ATGL downregulated the mRNAexpression level of genes related to adipocytes such as PPAR L ipoprotein lipase (LPL),LXR, Stearoyl-CoA desaturase (SCD), Fatty acid transporter member1(FATP1),Complement Factor D（Adipsin/CFD）and SREBP1gene. It had no significant influence on C/EBP α gene. While, over-expression ATGL upregulated the mRNA expressionlevel of genes related to adipocytes such as Fatty acid synthase (FAS), LEPR, ADI, HSL,CGI-58and PERILIPIN1gene.(6) Real-time PCR results indicated interference of ATGL downregulated the mRNAexpression level of genes related to adipocytes such as ADI, HSL, LEPR and SREBP1gene.It had no significant influence on C/EBP α and LPL gene. While, over-expression ATGLupregulated the mRNA expression level of genes related to adipocytes such as Fatty acidsynthase (FAS), PPARα, LXR, SCD, FATP1, CGI-58and PERILIPIN1gene.In conclusion, we found the potential specific effects of ATGL during TG accumulationin bovine adipocytes and their effects on other related genes was obtained based on thepresent results.