Omics Study On The Characteristics Of Adipose Tissue In Skeletal Muscle Of Grazing And Housed Cattle

In this study,we used three generations of crossbred Simmental and Mongolian cattle as the research subject.The skeletal muscle deposited adipose tissue of naturally grazing crossbred Mongolian cattle(referred to as: grazing cattle)and housed crossbred Mongolian cattle(referred to as: housed cattle)was used as the material for the determination of relevant physicochemical indexes.Next,we used high-throughput sequencing to determine the mRNA and miRNA expression The differentially expressed mRNAs and miRNAs in adipose tissue-related processes and signaling pathways were chosen,and the sequencing data were co-analyzed to create maps of the interactions between miRNAs and their targets.Finally,metabolomics was carried out to examine the relationship between the differentially expressed genes and metabolites.The main results are as follows:Samples of skeletal muscle-deposited adipose tissue from grazing cattle and housed cattle were analyzed to determine their colour differences,melting points,peroxide values,and fatty acid composition.The oleic acid(C18:1n9c)content in the fatty tissue of the loin of grazing cattle was higher than that in the fatty tissue of the loin of housed cattle in terms of fatty acid composition and content.The PUFAs in the waist and groin adipose tissue of grazing cattle were significantly different(p<0.05).The mRNAs of cattle fed using either of the two feeding methods were sequenced using high-throughput sequencing technology.Using |log2foldchange|1,p<0.05 as the screening threshold,the sequencing results revealed that we screened a total of 543 DEGs in the adipose tissue of grazing and housing cattle,277 of which were up-regulated and266 of which were down-regulated;The biological process ontology’s protein hydrolysis,redox,and lipid metabolism processes had the highest DEGs,according to GO enrichment analysis;the cell Membrane components,extracellular exosomes,and extracellular space were found to be the three terms in the ontology of components that contained the most DEGs.In the ontology of molecular functions,the three terms that contained the most DEGs were hydrolase activity,immobilized protein binding,and protein homodimerization activity.According to a thorough analysis of the enriched pathways,the pathways that are most closely related to the lipid metabolism pathway are the ones that contain 8 DEGs for fatty acid metabolism,6 DEGs for fatty acid degradation,7 DEGs for adipocytokine signaling,5 DEGs for steroid synthesis,and 4DEGs for adipocyte lipolysis regulation.The AMPK signaling pathway,PPAR signaling pathway,p53 signaling pathway,and renin-angiotensin system are the four regulatory mechanisms that are indirectly involved in lipid metabolism.In order to deeply analyze the molecular mechanism of up-regulated DEGs expression in grazing cattle adipose tissue,follow-up miRNAs sequencing was carried out to construct the miRNA-target gene interaction network diagram and relevant experimental verification.The results showed that 719 miRNAs were identified and 75 miRNAs were differentially expressed in grazing cattle.676 miRNAs were identified and32 miRNAs were differentially expressed in breeding cattle.The |log2foldchange|≥1、p< 0.01 were used as the threshold for screening,two up-regulated miRNAs(pma-miR-192-5p＿R-1 and hsa-miR-143-5p)and 10 down-regulated miRNAs(bta-miR-223＿R+1 、 mdo-miR-204＿R+2 、 bta-miR-19 a 、 bta-miR-497＿R-1 、bta-miR-146a＿R-2、bta-miR-19b、oan-miR-16b-5p＿R+2、pma-miR-23b＿R+1＿1ss23CT、bta-miR-193b＿R-2 、 hsa-miR-532-3p)were screened from grazing cattle.When|log2foldchange|≥1,p<0.05 was selected as the screening threshold,a total of 66 differently significant miRNA molecules were discovered in the skeletal muscle deposited adipose tissues of grazing and housed cattle.In the adipose tissues of grazing cattle,32 miRNAs were considerably up-regulated and 34 miRNAs were significantly down-regulated.Differential expression of genes will eventually manifest as changes in the type and quantity of intracellular metabolites.To reveal the intrinsic association between DEGs and metabolites in skeletal muscle-deposited adipose tissue of grazing and housed cattle,finally,we performed metabolomic analysis.A total of 135 metabolites were identified from the adipose tissue of grazing and housed cattle;78 glycerolipids were identified by removing duplicate components;15 glycerolipids were significantly up-regulated in the adipose tissue of grazing cattle and 11 glycerolipids were significantly up-regulated in the adipose tissue of housed cattle,respectively.,screened at a threshold of p < 0.05;among them,linoleic acid,myristic acid,oleic acid,and(2E,6Z)-dodecadienoic acid methyl ester were upregulated in the adipose tissue of grazing cattle,which The metabolic group data and the results of physicochemical property test and mRNA differential expression were consistent with each other.The analysis of differential metabolite pathways revealed that the glycerophospholipid metabolic pathway was the main pathway of metabolism,and the analysis of differential fatty acid metabolic pathway revealed that the linoleic acid metabolic pathway was the main pathway of fatty acid metabolism.By correlation analysis of differentially expressed metabolites with related differentially expressed genes,five fatty acids in differential metabolites were negatively correlated with class I genes(HACD4,ACAT2,ELOVL6,SLC2A4,CPT1 C,PORCN;EBP,MSMO1,ENSBTAG00000017567,LSS,SLC2A1,ACSBG1 FDFT1)were negatively correlated and positively correlated with class II genes(CPT1A,ACADL,CREB1,ECI2,ENSBTAG00000015248,FBP1,IRS2,LIPE,PPP2R1 B,PTGER3,RXRG).