The Expression Difference Of Genes Related To Brown Adipose Tissue Of Yak And Comparison Of Fatty Acid Composition In Different Seasons

Brown adipose tissue?BAT?intakes fatty acids as metabolic substrates to generate heat and burn fat in mitochondrial through the?uncoupling oxidation and uncoupling of UCP1.It was mainly focus on people and small mammals,while few reports have been reported on larger animals.Living in the plateau environment for a long time of yak has a unique cold-resistant constitution,which makes yak the best research object to explore the mechanism of animal body's adaptation to the cold environment.Therefore,this study aimed at the question whether there was a relationship between the differential expression of genes related.Therefore,in this study,randomly selected from the cold season?January?and warm?October?adult yak spinal fat,interscapular fat,subcutaneous fat,kidney fat,abdominal fat around five fat tissue as experimental materials.A series of studies on immunohistochemistry,Western blotting,Real-time PCR,RNA-seq technology and determination of fatty acid composition were carried out to reveal the brown fat of yak from the molecular perspective and provide basic data for the mechanism of yak'survival in cold environment.The research results are as follows:?1?Expression of UCP1 protein and relative expression of UCP1 gene:Immunohistochemistry and Western blotting were used to detect the expression of UCP1 protein in five adipose tissues of yak in different seasons,and the expression of UCP1 protein was higher in subcutaneous adipose tissues,interscapular adipose tissues and kidney adipose tissues,with significant differences?P<0.05?.UCP1protein expression in various adipose tissues of yak in cold season was significantly higher than that in warm season?P<0.05?.The expression of UCP1 gene was detected by Real-time PCR in various adipose tissues of yak in different seasons,and the expression of UCP1 gene was higher in subcutaneous adipose tissues,interscapular adipose tissues and kidney adipose tissues,which was basically consistent with the trend of protein expression.Therefore,the relative expression levels of UCP1 protein and gene in yak under cold conditions were higher than those in warm seasons.?2?Analysis of differentially expressed genes by RNA-seq technique:2305up-regulated genes and 2364 down-regulated genes were found in the spinal adipose tissue of yak in different seasons,and 13,236 differentially expressed genes were found in the two groups.In warm season,UCP1,COX1,CEBPA,FABP4,PPARG and other genes were significantly up-regulated,while PRDM16,ATP2A2,BMP7,FADS1 and other genes were significantly down-regulated.There were 1158up-regulated genes,731 down-regulated genes and 13,696 differentially expressed genes in fattening yak.Compared with grazing yak,SPP1,UCP2,CEBPA and other genes were significantly up-regulated,while UCP1,BMP7,ELOVL6,FASN and other genes were significantly down-regulated.Therefore,more genes were highly expressed in the spinal adipose tissue of yak in cold season than in warm season,and the cold climate would affect the gene expression in the spinal adipose tissue of yak.The gene expression patterns of fattening yak and grazing yak were similar,and only a few genes were changed.Compared with fattening yak,the cold environment was more likely to affect gene expression in yak.?3?GO enrichment analysis:In different seasons,there were 943 GO enrichment entries of differential genes in yak spinal adipose tissue,mainly in cell composition,and extremely significant in mitochondrial inner membrane,ribosome and mitochondria.The spinal adipose tissue of fattening yak genes enriched in 1104GO categories,which were mainly significantly enriched in phosphoprotein phosphatase activity,hydrolytic enzyme activity,acting on ester bond,protein tyrosine phosphatase activity and other molecular functions,and the least enriched in cell composition.Therefore,the composition of fat cells in yak is affected by cold season,but fattening mainly regulates the cell activity of yak through molecular function.?4?KEGG enrichment analysis:A total of 304 pathways were involved among the samples in different seasons,23 pathways were significantly enriched,including adhesion kinase,oxidative phosphorylation,PI3K-Akt signaling pathway,ECM-receptor interaction and fatty acid degradation.A total of 294 pathways were involved in fattening samples,including 27 pathways including lysosome,phagocytosis and rheumatoid arthritis.UCP1 gene is involved in three pathways:Huntington's disease,PPAR signaling pathway and Apelin signaling pathway.The UCP1 gene of yak samples in different seasons is mainly involved in the enrichment of the Huntington's disease metabolic pathway of 74 genes,while the PPAR signaling pathway is involved in the significant enrichment of yak samples in fattening,with a total of 19genes.Therefore,cold environment and fattening will affect the metabolic pathways of yak.?5?Analysis of fatty acid composition in yak adipose tissue:The saturated fatty acid was the main fatty acid in yak adipose tissue in different seasons.Compared with the warm season,the content of PUFA,C_16:0,MUFA,C_18:0 and C_18:1n9changes with the relative expression of UCP1 gene in various adipose tissues of yaks in the cold season.BCFA was detected in different adipose tissues of yak.Except the interscapular,BCFA content in other tissues was lower in cold season than in warm season,and the content of BCFA in tissues with higher relative UCP1 gene expression was lower.Therefore,the changes of fatty acid content of C_16:0,BCFA,C_18:0 and C18:1n9 in yak adipose tissue in cold season will affect the relative expression of UCP1gene,and the specific mechanism needs to be further studied.