Amyloid β-peptides interfere with mitochondrial preprotein import competence by a coaggregation process

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Amyloid-beta (Aβ) peptides are implicated in Alzheimer disease (AD) pathogenesis, with known cellular toxicity linked to aggregate formation.
• Intraneuronal Aβ accumulation and mitochondrial dysfunction are observed in AD, but the precise role of intracellular Aβ remains debated.

Purpose of the Study:

• To investigate the impact of Aβ peptides on mitochondrial biogenesis and protein import.
• To elucidate the mechanism by which Aβ peptides interfere with mitochondrial function in the context of AD.

Main Methods:

• Assessing the effect of Aβ peptides on preprotein import into isolated mitochondria.
• Analyzing Aβ peptide interaction with mitochondria and their components.
• Investigating the role of Aβ aggregation in import inhibition using different Aβ species.

Main Results:

• Aβ peptides, especially Aβ42, significantly inhibited preprotein import necessary for mitochondrial biogenesis.
• Aβ peptides showed weak interaction with mitochondria and did not disrupt inner membrane potential or translocase complexes.
• Import inhibition occurred via an extramitochondrial coaggregation mechanism, with Aβ42 showing stronger effects.

Conclusions:

• Aβ peptide-induced inhibition of mitochondrial protein import is a significant pathobiochemical mechanism in AD.
• Extramitochondrial coaggregation of Aβ peptides disrupts mitochondrial biogenesis, contributing to cellular damage.
• The stronger inhibitory effect of Aβ42 correlates with its established role in AD pathology.