Drug discovery and molecular mechanisms in alzheimer's disease and hedgehog signaling
Authors
Faris, Shannon, Jean
Issue Date
2024-06
Type
Electronic thesis
Thesis
Thesis
Language
en_US
Keywords
Chemistry
Alternative Title
Abstract
The first half of this dissertation focuses on Alzheimer's disease (AD), a neurodegenerative disease that was the 7th leading cause of death in the US in 2021. Characterized by intracellular abnormal tau deposits in the brain, tau aggregates can propagate from one neuron to another in a prion-like manner, mediated by interactions with heparan sulfate (HS) proteoglycans and low-density lipoprotein 1 (LRP1). Here I report the development of two novel AlphaScreen assays, that target the tau-HS and tau-LRP1 interface. From tau-HS AlphaScreen, a small-molecule compound was discovered to disrupt the tau-heparin interaction by binding to heparin with micromolar affinity; and further characterization showed that this compound can disrupt the tau-glycan interface in both in vitro molecular and cellular environments. In our tau-LRP1 AlphaScreen assay, we identified a low micromolar inhibitor, which binds to tau in vitro and inhibits tau uptake in cellular studies.
The second half of this dissertation focuses on Hh autoprocessing and cholesterol binding. The Hedgehog (Hh) signaling pathway plays fundamental roles in embryonic development while abnormal activation of Hh signaling in adults is associated with many types of cancer. Hh signaling is initiated by the Hh ligand, generated from the autoprocessing of Hh precursor protein that undergoes a unique cholesterol autoprocessing reaction called cholesterylation.
Here I report the novel catalytic role of a highly conserved cysteine residue C143 in Hh autoprocessing which mediates the formation of a branched intermediate (BI) thioester which unifies the catalytic mechanisms of Hh autoprocessing with intein splicing, its likely evolutionary predecessor. A novel surface plasmon resonance (SPR) method was developed to study protein-cholesterol binding with biotinylated cholesterol immobilized onto a SPR sensor chip. 6-CF3 modified cholesterol and a non-steroidal Hh inhibitor, PAPP was utilized in 19F NMR to characterize the C-terminal autoprocessing domain of Hh (HhC) binding to cholesterol and that also revealed a surprising ternary interaction among HhC, PAPP and cholesterol.
Description
June 2024
School of Science
School of Science
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY