UC San Diego

Alzheimer’s Disease is the most prevalent and devastating age-related neurodegenerative disease. Symptoms such as decline in memory and learning typically precede neuronal loss. The small molecules BTA-EG4/6 have been shown to promote memory and learning, a phenomenon attributed to increased dendritic spine density. The mechanism behind this phenomenon, however, is not well understood. The work in this thesis is motivated by this gap in knowledge.

Previous studies in the Yang lab have identified Fascin as a cellular target of BTA-EG4. Chapters 1 & 2 provide a summary of Alzheimer’s disease, the spinogenic molecule BTA-EG4 and the structure and function of fascin. In chapter 3, an in silico model of the binding mode of BTA-EG6, an analog of BTA-EG4, to fascin is reported. In chapter 4, site-directed mutagenesis studies and other biochemical assays to characterize the residues involved in the binding site of the fascin-BTA-EG6 complex are presented. Results from circular dichroism spectroscopy and slow sedimentation actin bundling assay showed that fascin and fascin mutant proteins were functional and properly folded. Isothermal titration calorimetry results (ITC) confirmed the physical binding between fascin and BTA-EG6 in the micromolar range. ITC data for mutant proteins revealed that mutation in the protein affected its binding affinity with BTA-EG6. The data obtained points towards a possible mechanism of binding between BTA-EG6 and fascin. The in silico model together with the biochemical data supports the participation of residues Ala137, Gly393, Ile45 and Arg389 in the binding mode of BTA-EG6 to fascin.