Understand Glycation: The Sweet Side of Protein Regulation

PROJECT SUMMARY My central vision is to understand how glycation functions as an early nutrient sensing mechanism that links cellular metabolic state to protein function. Glycation is an evolutionarily conserved non-enzymatic protein modification but its biological significance has not been established. Broadly, it describes the covalent addition of glucose and related sugar-derived metabolites on to proteins. Moreover, while the forward reaction is free of enzymes, distinct de-glycating enzymes FN3K and DJ-1 catalyze the removal of these so-called “sugar adducts”. Glycation is an under-served area in physiology and medicine and until recently it was perceived as a passive marker and non-specific protein damage associated with hyperglycemia. Conversely, my recent findings together with other studies allude to a more dynamic role of glycation in nutrient signaling and gene regulation. I have been building upon these to develop a research program focused on understanding the biological implications of this new protein mark, particularly in the context of normal and aberrant sugar metabolism. I hypothesize that glycation is an ancient mechanism that adjusts protein function and cell behavior in response to nutrient availability. The main challenge in addressing this hypothesis is the lack of sensitive proteomics approaches to study this protein modification. Here, we will implement a high-resolution isotope labeling and affinity enrichment based advanced proteomics strategy to first gain mechanistic insights into glycation and deglycation, including their target preference, stoichiometry, and reaction kinetics. Next, we will apply this to understand the role of glycation in differentially regulating proteins under distinct metabolic conditions. In particular, we will focus on highly “glycatable” proteins within our pre-ranked “high priority pathways” that emerged from my recent low-resolution glycation profiling and includes translation initiation and elongation factors, metabolic proteins, and histones. Upon successful completion, we anticipate to have i) identified similarities and differences in key protein targets of FN3K and DJ-1 sensitive glycation, ii) distinguished early, intermediate, and late glycation and corresponding deglycation targets, both proteins and specific amino acids within, iii) established relationship between glycation, glucose influx, and metabolism, and iv) interrogated its role in affirmative metabolic adaptation by regulating our “high priority pathways”. This will have significant medical implications because the de-glycating enzymes are highly amenable to small molecule inhibition. To that end, our findings will lay a strong foundation and provide the necessary scientific impetus to develop new inhibitors of deglycation. Importantly, beyond having clinical applications for metabolic and age-related disorders like diabetes, de-glycation therapies may also have a place in cancer treatment. In summary, my lab is uniquely equipped to undertake this challenge that will have break new grounds in our understanding of metabolic protein regulation and generate metadata that will drive future hypothesis-driven and clinically important glycation research.