Dr. Liang, Department of Chemistry
Alzheimer's disease (AD) is a relentless neurodegenerative condition characterized by a progressive decline in cognitive function, with no current cure. Extensive research has linked AD to the accumulation of misfolded proteins in the brain, particularly amyloid beta (Aβ) peptides, derived from the cleavage of larger membrane proteins. Notably, the familial mutant of amyloid beta E22G (Aβ E22G; Glutamate has mutated to Glycine at position 22) is associated with aggressive early-onset AD and rapid plaque formation in the brain, yet the precise pathological mechanisms remain elusive. The amyloid hypothesis posits that the accumulation of misfolded Aβ is a primary driver of AD pathology. Targeting and eliminating these aggregates hold promise for disease stabilization and potential cure. Understanding the chemical environment of the brain and its impact on Aβ aggregation is crucial for developing effective intervention strategies. Recent studies suggest a correlation between a high-salt diet and cognitive decline in humans and mice. Our project aims to investigate the effects of increased Sodium Chloride (NaCl) concentration on the aggregation kinetics of Aβ E22G.
Aim: Investigate NaCl Effects on Protein Aggregation Kinetics.
Objective: Determine how NaCl concentration influences the aggregation kinetics and morphology of amyloid beta, with a focus on the familial mutant Aβ E22G.
Hypothesis Tested: Salt concentration significantly affects the aggregation kinetics of amyloid beta, particularly the familial mutant Aβ E22G.
Activities: Previous data indicates that elevated NaCl concentration accelerates the aggregation rate of wild-type Aβ, as evidenced by a shorter time frame for the observed Thioflavin T (ThT) fluorescence signal. Additionally, the aggregation lag decreases with increasing NaCl concentration, suggesting a heightened propensity for Aβ aggregation in a high-salt environment. Our hypothesis posits that salt concentration will distinctly impact the aggregation kinetics of the familial mutant Aβ E22G. To test this, we will overexpress the Aβ E22G from bacteria and purify the protein through affinity and size exclusion column chromatography. Finally, we will employ ThT fluorescence to monitor the aggregation kinetics of Aβ E22G.
Anticipated outcomes include the propagation of larger aggregates in a high-salt environment compared to smaller aggregates in a low-salt environment. Given the heightened aggregation tendency of Aβ E22G compared to the wild type, we expect the salt effect to be more pronounced in Aβ E22G, offering insights into potential therapeutic interventions for familial AD mutations.