Small Intestinal Proteomics Coupled With Serum Metabolomics Reveal The Molecular Biological Characteristics Of Chinese Hamster With Type 2 Diabetes Mellitus

Objective:A stable population of spontaneous type 2 diabetes(T2DM)in Chinese hamsters was established by monitoring blood glucose in the animal model of spontaneous T2 DM in Chinese hamsters.Then the differentially expressed proteins in the small intestine of diabetic hamsters and the differential metabolites in serum samples were screened by proteomics and metabonomics analysis,respectively.The molecular biological characteristics of T2 DM in Chinese hamsters were analyzed from the aspects of proteomics and metabolism,so as to provide scientific basis for the application of Chinese hamster model in the study of T2 DM mechanism.Methods:On the basis of the preliminary establishment of the animal model of spontaneous T2 DM in Chinese hamsters,the inbreeding of the hamsters used for population expansion was continued,and the fasting blood glucose(FBG)value of their offspring was monitored from the age of 3 months.Hamsters with FBG ? 6 mmol/L or FBG ? 4.5 mmol/L were selected as diabetes or normal control group,respectively.The differentially expressed proteins and differential metabolic profiles of diabetic Chinese hamsters were constructed by proteomics and metabonomics analysis.The functions of the selected differentially expressed proteins were analyzed by GO and KEGG enrichment analysis,and the selected differential metabolites were visually explained by MPEA analysis at the system level,and then the results of proteomics and metabonomics were analyzed jointly.Finally,Western Blotting experiment was used to verify the protein expression level of candidate differentially expressed proteins PGAM1,PHGDH,CBS,CTH,and GATM in the small intestine of diabetic hamsters and normal intestinal tissues.Results:The results showed that in the diabetic population of Chinese hamsters,the blood glucose value of diabetic hamsters was significantly higher than that of the normal control group from the age of 3 months.At the age of 12 months,the hyperglycemia value of diabetic hamsters tended to be stable and glucose tolerance was impaired.However,there was no difference in body weight between the diabetic group and the normal control group.A total of 213 differentially expressed proteins were identified in the small intestine(P-value < 0.05;FC >1.2),of which 117 proteins were up-regulated and 96 down-regulated.A total of 14 differential metabolites were identified in the serum samples,including 10 amino acids,3 organic acids and 1 fatty acid.Except for 4-Hydroxybenzoic acid,which was down-regulated in the diabetic group,the metabolic levels of other differential substances in the samples were up-regulated.The functional enrichment of GO and KEGG of differentially expressed proteins showed that the metabolic abnormalities of diabetic hamsters were mainly concentrated in glucose and lipid metabolism,insulin resistance(IR),amino acid metabolism disorder and inflammation.MPEA analysis of differential metabolites showed that almost all of the pathways were amino acid metabolism,and the amino acid metabolites in these pathways were related to IR.Based on the joint analysis of the two omics data,it was found that eight differentially expressed proteins(PGAM1,PHGDH,PSAT1,CTH,CBS,GATM,GAMT,and GCAT)and three differentially expressed metabolites(Glycine,Homoserine,and Tryptophan)were enriched in the glycine,serine and threonine metabolism pathway.It was found that the amino acid metabolites identified in diabetic hamster serum samples could be used as biomarkers of IR,and the above differentially expressed proteins could regulate the metabolism of these amino acids.In addition,the expression levels of candidate proteins PGAM1,PHGDH,CBS,CTH,and GATM were significantly up-regulated in the small intestine of diabetic hamsters,which were verified by Western Blotting experiment.Conclusion:In this study,proteomics and metabonomics were used to analyze the animal model of spontaneous T2 DM in Chinese hamsters.It was found that the molecular biological characteristics of diabetic hamsters were mainly concentrated in glucose and lipid metabolism,IR,amino acid metabolism disorder and inflammatory.More importantly,we made a joint analysis of the results of these two omics,and with amino acid metabolism as a clue,we have identified some candidate proteins in the small intestine that may be potentially associated with IR.These findings are of great significance for understanding IR in diabetic hamsters from a molecular point of view,and lays a foundation for the further study of diabetic IR in the hamster model.At the same time,it also provides a new idea for the study of the pathogenesis of T2DM.