γ-Secretase modulators show selectivity for γ-secretase-mediated amyloid precursor protein intramembrane processing

Area of Science:

• Neuroscience
• Biochemistry
• Molecular Biology

Background:

• Alzheimer's disease (AD) pathogenesis involves the aggregation of beta-amyloid peptide 42 (Aβ42).
• Gamma-secretase enzyme cleaves amyloid precursor protein (APP) to produce various Aβ peptides.
• Gamma-secretase modulators (GSMs) are investigated as potential AD therapeutics by lowering Aβ42 levels.

Purpose of the Study:

• To investigate the selectivity of GSMs on gamma-secretase substrates.
• To determine how GSMs affect the processing of E-cadherin, EphA4, and EphB2 by gamma-secretase.
• To elucidate the impact of GSMs on Aβ-like peptide production from non-APP substrates.

Main Methods:

• Utilized a reporter gene assay to assess gamma-secretase activity.
• Analyzed the cleavage of three specific gamma-secretase substrates: E-cadherin, EphA4, and EphB2.
• Quantified the production of intracellular domains and Aβ-like peptides.

Main Results:

• GSMs did not affect the gamma-secretase-dependent generation of EphA4 and EphB2 intracellular domains.
• Gamma-secretase processing of EphA4 and EphB2 yielded Aβ-like peptides.
• GSMs modulated Aβ-like peptide production from EphA4, but with significantly lower potency than Aβ modulation.

Conclusions:

• GSMs demonstrate selectivity for gamma-secretase-mediated Aβ production.
• The findings support the targeted therapeutic potential of GSMs in Alzheimer's disease.
• GSMs spare the processing of other critical gamma-secretase substrates involved in cell signaling.