Investigating Scavenger Efficacy on Methylglyoxal-Induced Glycation in the Cell Nucleus Using Atomic Force Microscopy

Details

Supervisors

Dumitru, Andra-Cristina ; Alcaraz Hurtado, Mar

Faculty

Faculté des sciences

Degree label

Master [120] en biochimie et biologie moléculaire et cellulaire, à finalité didactique

Abstract

enDiabetes mellitus is a chronic metabolic disorder characterized by hyperglycemia, which drives the non-enzymatic formation of advanced glycation end products (AGEs) via the Maillard reaction. A major contributor to this pathology is methylglyoxal (MGO), a highly reactive α,β dicarbonyl byproduct of glycolysis that increases significantly under diabetic conditions and reacts with proteins and DNA. While the effects of glycation on the extracellular matrix are well documented, the intracellular glycation and especially its impact on the cell nucleus are less understood. To counteract the damaging effects of MGO, various agents have been investigated, such as AGE scavengers, that prevent the formation of new AGEs by reacting with MGO, and AGE breakers, that break the covalent cross-links of proteins. Among the compounds classified as AGE scavengers are aminoguanidine and thiamine, also known as vitamin B1. Aminoguanidine is a pharmaceutical nucleophilic reagent that acts as a potent scavenger by reacting with MGO to form inactive triazine isomers. Thiamine is a natural compound that serves as an essential cofactor for the glyoxalase system that detoxifies MGO and has also been suggested to possess direct chemical quenching potential against dicarbonyl systems. This Master’s thesis evaluates the efficacy of these two scavengers in preserving the mechanical properties of isolated HeLa nuclei. Using Atomic Force Microscopy (AFM) in force spectroscopy mode combined with a power-law rheology model, we studied and quantified nuclear mechanics through two parameters: the scaling modulus (E0), representing stiffness, and the viscoelastic coefficient (γ), representing fluidity. We show that exposure to MGO induces an increase in nuclear stiffness and a simultaneous loss of viscous behavior, likely due to the formation of irreversible crosslinks between MGO and intranuclear components such as histones, lamins, and DNA. Aminoguanidine effectively scavenges MGO, which preserves nuclear mechanical homeostasis. In contrast, thiamine shows a low scavenging potential towards MGO ex-cellulo, failing to prevent the observed increase in stiffness and decrease in viscosity upon glycation. In conclusion, this research identifies nuclear mechanics as a sensitive target of metabolic stress with potential consequences for essential functions such as mechanosensing and gene expression. Aminoguanidine effectively scavenges MGO and preserves nuclear mechanical integrity, whereas thiamin shows no protective effect under ex-cellulo conditions. These findings demonstrate that direct dicarbonyl scavenging can prevent glycation-induced nuclear dysfunction, thereby supporting the development of future therapeutic strategies to mitigate cellular impairment in diabetes. Moreover, this work establishes quantitative nuclear mechanics as a novel and sensitive functional readout for screening and mechanistically benchmarking anti-glycation compounds, linking biochemical modification to emergent biomechanical behavior.