Peptidome analysis reveals the involvement of endogenous peptides in mouse pancreatic dysfunction with aging

Type 2 diabetes (T2D) is a glucose regulation disorder that has significantly enhanced mortality and the global disease burden. The prevalence of T2D has increased worldwide and is higher in the elderly. The function of pancreatic islets decreases with age, which is one important reason for the occurrence of diabetes in the elderly. Recently, peptidome analysis has attracted attention. However, the role of age-related peptides in pancreatic dysfunction has not been investigated extensively. Here, we conducted a comparison of endogenous peptides between pancreas from adult and aging mice by liquid chromatography tandem mass spectrometry (LC-MS/MS). A total of 2,089 peptides originating from 1,280 protein precursors were identified, of which 232 were upregulated and 183 were downregulated in the aging mice (fold change ≥ 2 and p < 0.05), suggesting that the expression of pancreatic peptides in mice varied with age. The molecular weight of most peptides was <3.0 kDa, and the isoelectric point distribution had a bimodal characteristic. Further analysis of cleavage site patterns indicated that proteases cleaved pancreatic proteins according to their rules. Moreover, Gene Ontology and pathway analyses showed that the differentially expressed peptides potentially had specific effects on pancreatic dysfunction. Some differential peptides were located within the domains of precursor proteins that were closely associated with the development of diabetes. We believe that our research may advance the current understanding of pancreas-derived peptides and that certain peptides may be involved in the etiology of diabetes.