The Roles Of ELOVL6 In The Regulation Of Preadipocyte Proliferation And Lipid Metabolism In Qinchuan Beef Cattle

Fatty acid composition is an important phenotypic trait that affects nutrition,quality and flavor of beef.How to balance fatty acid composition and improve meat quality and nutrition has become a new research direction in breeding.Fatty Acid Elongase 6(ELOVL6)is a key gene that regulates the overall balance of fatty acid composition in the body and plays an important role in fatty acid extension.It has been reported that the expression of ELOVL6 promotes the proliferation of vascular smooth muscle cells,but there is no clear report on whether ELOVL6 can regulate the proliferation of preadipocytes.ELOVL6 is involved in lipid metabolism,but the downstream genes and signaling pathways of ELOVL6 involved in lipid metabolism are not completely clear,and the upstream regulatory factors of ELOVL6 need to be further studied.Therefore,in the current study,the role of ELOVL6 gene in beef quality was investigated in the in the new Qinchuan beef strain(hereinafter referred to as "Qinchuan beef cattle")bred by Northwest Agriculture and Forestry University.The purpose of regulation is to provide theoretical basis for genetic improvement and molecular breeding of Qinchuan beef.The main findings are as follows:1.ELOVL6 gene is widely expressed in different tissues of Qinchuan beef cattle,with the highest expression in the small intestine,followed by tissues with higher expression levels in the stomach and fat,and lower expression in the heart,muscle,and spleen.The results of immunofluorescence showed that ELOVL6 protein was mainly expressed in the cytoplasm.2.ELOVL6 gene is positively correlated with the proliferation of bovine preadipocytes.Interfering with ELOVL6 inhibited cell proliferation and blocked cells from G2 to M phase.ELOVL6 interference significantly down-regulated the m RNA expression levels of cell proliferation-related genes such as CCNA2,CCNB1,and CCND2,and the protein expression levels of CDK1 and PCNA;Ed U staining results showed that overexpression of ELOVL6 can significantly increase the proportion of Ed U-positive cells and up-regulate the m RNA and protein expression of CDK1 Level,significantly downregulated the m RNA expression of P21 and P27.Further research found that ELOVL6 activates the m TOR / p70S6 k signaling pathway.The m TOR specific inhibitor rapamycin can attenuate the activation of phosphorylation of m TOR / p70S6 k pathway caused by overexpression of ELOVL6 and can attenuate the down-regulation of p21 and p27 caused by overexpression of ELOVL6 effect.3.Interfering with ELOVL6 significantly increased the proportion of bovine preadipocytes in the late stage of apoptosis,and at the same time promoted the up-regulation of m RNA expression levels of genes related to apoptosis,Bad and Bak.4.ELOVL6 overexpression affects fatty acid composition in bovine adipocytes.Among them,the ratio of myristic acid(C14: 0)and palmitic acid(C16: 0)was significantly decreased,and the ratio of stearic acid(C18: 0)and arachidonic acid(C20: 4n6)was significantly increased.5.Compared with the control group,overexpression of ELOVL6 significantly changed the expression of 2170 genes,which was mainly related to the regulation of fat cell lipolysis,Wnt signaling pathway,c AMP signaling pathway,Fox O signaling pathway and PI3K-Akt signaling pathway.ELOVL6 overexpression significantly down-regulated the expression of FABP4,CEBP?,SCD5,FOXO4,and WNT2 genes.ACSL4,FABP3,SCD1,PIK3R3,ADRB1,ADRB2,and PPARGC1 A were significantly up-regulated in ELOVL6 overexpressed samples.6.The core promoter region of ELOVL6 gene is located at-168 ? + 69 bp.EMSA and Ch IP experiments confirmed that SREBP1,KLF6 and PU.1 are the key transcription factors of the ELOVL6 gene,and can directly affect the transcription of the ELOVL6 gene by directly binding to the promoter region.In summary,ELOVL6 is an important gene in lipid metabolism of adipocytes.ELOVL6 can not only promote the proliferation of bovine preadipocytes,but also the precise regulation of ELOVL6 expression level affects the overall balance of fatty acid composition of adipocytes.In addition,this study revealed the molecular mechanism by which ELOVL6 can regulate the proliferation of bovine preadipocytes through the m TOR / p70S6 k signaling pathway.At the same time,SREBP1,KLF6,and PU.1 were screened as upstream transcription factors that can directly bind to the promoter region and affect ELOVL6 transcription.The above studies laid the foundation for further revealing the genetic improvement and molecular breeding of Qinchuan cattle.