Covalent fragment inhibits intramembrane proteolysis

Area of Science:

• Neuroscience
• Biochemistry
• Drug Discovery

Background:

• Alzheimer's disease (AD) presents a significant public health challenge with limited treatment options.
• Targeting gamma-secretase (GS) to reduce amyloid load is a primary strategy in AD drug development.
• Previous GS inhibitors (GSIs) have shown limited success due to side effects from inhibiting normal GS function.

Purpose of the Study:

• To discover a novel therapeutic approach for AD that circumvents the side effects of traditional GSIs.
• To identify a compound that targets the amyloid precursor protein (APP) substrate of GS.
• To explore a new mechanism for inhibiting GS activity.

Main Methods:

• Utilized Nuclear Magnetic Resonance (NMR) Spectroscopy and MALDI-TOF-MS to confirm covalent binding of fragment 6H8 to APPTM.
• Characterized 6H8 as a Michael acceptor that covalently links to lysine residues (K53-K55) on APPTM.
• Assessed the inhibition of intramembrane proteolysis using a gel-based cleavage assay.

Main Results:

• Fragment 6H8 was confirmed to covalently bind to the transmembrane domain of APP (APPTM).
• 6H8 inhibits GS activity via substrate binding with an IC50 of 2-4 μM.
• This covalent binding targets specific lysine residues on the APP substrate.

Conclusions:

• Fragment 6H8 represents a novel covalent warhead for targeted covalent inhibitors (TCIs) in AD drug discovery.
• This approach avoids the off-target effects associated with traditional GSIs.
• Developing TCIs based on 6H8 offers a promising new avenue for AD therapeutic development.