Cellular mechanisms of γ-secretase substrate selection, processing and toxicity

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Presenilins (PSs) are central to gamma-secretase complexes, cleaving transmembrane proteins to produce amyloid-beta (Aβ) and signaling peptides.
• Gamma-secretase substrate processing is modulated by substrate recruiting factors (γSSRFs), which link substrates to the enzyme complex.
• Familial Alzheimer's disease (FAD) mutations in PSs impair epsilon-site cleavage, reducing signaling peptide production and increasing toxic substrate accumulation.

Purpose of the Study:

• To review novel mechanisms controlling gamma-secretase substrate selection and cleavage.
• To examine the relevance of these mechanisms and γSSRFs in Alzheimer's disease (AD) pathogenesis.
• To highlight γSSRFs as potential pharmacological targets for modulating specific gamma-secretase products.

Main Methods:

• Review of recent scientific literature on presenilins, gamma-secretase, and substrate regulation.
• Analysis of the functional consequences of PS mutations and gamma-secretase inhibition.
• Discussion of the role of substrate recruiting factors in enzyme activity and substrate specificity.

Main Results:

• Gamma-secretase substrate processing is actively regulated by specific substrate recruiting factors (γSSRFs).
• PS FAD mutants exhibit loss-of-function at epsilon sites, impacting signaling peptide production.
• Gamma-secretase inhibitors may share toxicity mechanisms with FAD mutations by disrupting substrate processing.

Conclusions:

• Understanding substrate selection mechanisms is crucial for developing targeted therapies for Alzheimer's disease.
• Gamma-secretase substrate recruiting factors represent promising targets for pharmacologically controlling Aβ and signaling peptide production.
• Novel therapeutic strategies could modulate gamma-secretase activity to mitigate AD pathology and associated toxicities.