Ongoing analyses from our laboratory and others have identified novel properties of self proteins, namely
posttranslational protein modifications (PTMs) that may be identified as early proteomic and immunologic
biomarkers of Type 1 diabetes as well as alter metabolic pathways. An emerging number of self proteins
acquire PTMs and become targets of B and T cell autoimmune responses leading to inflammation and
pathology in the pancreas. Some examples of critical modifications to self proteins include citrullination,
oxidation, deamidation reactions, and isoaspartyl modification, all responses of self proteins within cells that
undergo inflammatory stress. Key PTM candidates have already been identified from human beta cells and
other key candidates will be identified from beta cell derived exosomes, recently identified as a peripheral
marker of beta cell health. As importantly, these PTMs within cells may alter the biological properties of
proteins within beta cells. In the present proposal, we will define how modified self-proteins may alter
enzymatic pathways of glucose sensing and insulin secretion in the pancreatic beta cell. The proposal will
utilize MultiOrdinate Spectral Analysis (MIMOSA), a technology pioneered at Yale University. MIMOSA is a
major innovation that provides an internally cross-validated as well as NMR-validated, direct, rigorous,
comprehensive integrated analysis of metabolic fluxes. The “multi-ordinate” aspect of MIMOSA incorporates
the flow of stable isotope from metabolite to metabolite along intersecting metabolic pathways. The “mass
isotopomer” aspect uses MS/MS-based ion fragmentation analysis of stable-isotope-labeled metabolites to
identify the carbon-specific position of label. The significance and innovation of the present studies is in
identifying pathways that may restore beta cell functions, via pharmaceutical correction of the aberrant
modification, as well as link autoimmune biomarkers with pathways of beta cell dysfunction.