Study On The Role And Mechanism Of MC5R In Overfeeding And Fasting/Refeeding Models

Nutrition and energy levels have an important impact on the growth and development,the performance of production,and the occurrence of disease and health recovery of animals.Previous studies have shown that MC5R is involved in the nutrition/energy metabolism of animals,especially in lipid metabolism.However,how MC5R is involved in the nutrition/energy metabolism of animals is not well understood.The overfeeding model and the fasting/re-feeding model of animal are commonly used for studies related to nutrition/energy metabolism.In this study,we first determined the expression of MC5R in different tissues of goose,and then determined the expression level of MC5R in goose pectoral muscle and liver in the above two models.Secondly,goose primary myocytes and hepatocytes were treated with nutrient/energy metabolism-related factors(glucose,oleic acid and thyroxine),and the expression of MC5R was determined thise cells,which as followed by overexpression of MC5R in goose primary myocytes.Thirdly,MC5R was overexpressed in goose primary myocytes,transcriptome sequencing analysis was then performed to reveal the downstream genes and pathways of MC5R,and finally,the genes that might be regulated by MC5R in vivo and cell models.The main findings are as follows:(1)The mRNA expression of MC5R in tissues related to energy metabolism in geese.The data showed that MC5R expression was highest in goose adipose tissue,followed by skin and liver,and muscle tissues(pectoral and leg muscles),while the expressionin the intestine and heart was the lowest.(2)Effect of nutrition/energy levels on MC5R expression in muscle and liver in the overfeeding model and the fasting/refeeding model.In the overfeeding model,overfeeding significantly inhibited MC5R mRNA and protein expressions in the liver,while MC5R expression in the pectoral muscle was not significantly different compared to the control group;in the fasting/refeeding model,fasting significantly induced MC5R mRNA expression in the pectoral muscle and liver,while refeeding significantly inhibited this induction.This suggests that MC5R expression in muscle and liver tissues is influenced by changes in nutrition/energy levels.(3)Regulation of MC5R expression in goose pectoral myocytes and hepatocytes by factors related to nutrition/energy metabolism.Glucose at the concentrations of 50 mM and 100 mM significantly induced MC5R expression in pectoral myocytes and hepatocytes;0.25 mM oleic acid significantly induced MC5R expression in pectoral myocytes and hepatocytes;0.1 μM and 0.3 μM thyroxine significantly inhibited the expression of MC5R in pectoral myocytes and hepatocytes.This suggests that MC5R expression in pectoral myocytes and hepatocytes is influenced by a variety of factors related to nutritional/energy metabolism.(4)The differentially expressed genes(DEGs)and signaling pathways affected by MC5R overexpression in pectoral myocytes.Transcriptome sequencing analysis after overexpression of MC5R gene in goose primary myocytes showed that there were 4106 DEGs between the control group and MC5R-overexpressing cell group,of which 1897 were up-regulated and 2209 were down-regulated in the overexpression group vs the control group.The GO terms and KEGG pathways enriched with DEGs were mainly related to nutrition/energy metabolism and immune/inflammatory response.(5)Association of MC5R expression in myocytes and hepatocytes with the expression of some downstream genes in vivo and vitro models.By determining the expression levels of differentially expressed genes downstream of MC5R related to glycolipid metabolism and inflammatory response,data showed that the expression of genes such as PLA2G4A,PTGS2,TRAF2,IL6 and PLPP4 in myocytes and ACSL1,PSPH,HMGCS1,CPT1A,PACSIN2,IGFBP3,NMRK1,GYS2,ECI2,NDRG1,CDK9,FBXO25,SLC25A25,USP25 and AHCY in hepatocytes may be mainly regulated by MC5R in the models.In summary,in the living geese,MC5R expression in myoblasts and hepatocytes was regulated by nutrition/energy metabolism;at the cellular level,MC5R expression in goose myocytes and hepatocytes was regulated by nutrition/energy metabolism-related factors(glucose,oleic acid,and thyroxine),but changes in vivo could not be attributed to changes in these factors,suggesting the existence of other unidentified nutrition/energy metabolismrelated factors that could have significant regulatory effects on the expression of MC5R.MC5R can mediate the response of goose hepatocytes and myocytes to changes in nutrition/energy levels through various pathways,particularly glucolipid metabolism and immune/inflammation-related pathways.These findings provide a good foundation for understanding the novel biological functions of MC5R,and elucidating the molecular mechanisms by which nutrition/energy levels regulate animal growth,production performance and health.