Developing bioanalytical methods to study proteins damaged by spontaneous chemical reactions in age-related diseases
Associate Professor and Director of Proteomics Core of Bioscience Research Centre
School of Biological Sciences
Nanyang Technological University
C2-361 (Reading Room)
Abstract: Age is the biggest known risk factor for many human diseases including cardiovascular diseases, dementia and diabetes. The pathogenesis of these diseases can be triggered by accumulation of age damaged critical host proteins, leading to progressive loss of essential functions in cells, tissues and organs. Degenerative protein modifications (DPMs) caused by spontaneous chemical reactions such as oxidation, deamidation, racemerization, glycation, cambamylation, and many others can radically alter protein structure and function. Despite the clear clinical importance of understanding DPMs biology in human diseases, the DPMs-induced disease mechanisms remain poorly understood, largely due to the analytical challenges associated with their study. Therefore, the development of novel bioanalytical method is vital to dissecting the complex molecular pathophysiology of these major human diseases.
In order to better define the role of DPMs in the age-related diseases, we have developed novel bioanalytical methods that can; 1) avoid artificial chemical modifications during sample preparation; 2) improve the sensitivity and confidence of identifying low-abundance DPMs by coupling mix-mode chromatographic separation to mass spectrometry detection; 3) in-vivo sampling vascular bed proteins in animal disease models by differential systemic decellularization in vivo (DISDIVO) method. Using these advanced bioanalytical methods to study animal diseases models and clinical samples from patients with heart diseases, stroke, vascular dementia and diabetes, we have revealed that ‘protein aging’ not only results in ‘loss-of-function’ of essential proteins by triggering protein misfolding and aggregation, but can also confer paradoxical ‘gain-of-function’ changes in certain proteins that actively enhance CVD development. Specifically, we identified that age-related protein damage in CVD can generate integrin-binding isoDGR motifs that promote leukocyte recruitment to vascular beds, which stimulates expression of pro-inflammatory cytokines and chemokines in blood vessel walls, leading to progression of disease, rupture of atherosclerotic plaque and heart attack/stroke. The age-damaged proteins are novel biomarkers for age-related diseases, and are being developed into new diagnostic kits that can be used to detect asymptomatic CVD patients at high risk of heart attack, stroke, vascular dementia and diabetic vascular complications.