Amyloid β-induced ER stress is enhanced under mitochondrial dysfunction conditions

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Endoplasmic reticulum (ER)-mitochondria crosstalk is implicated in amyloid-beta (Aβ)-induced apoptosis.
• Platelets from Alzheimer's disease (AD) patients exhibit defects in mitochondrial cytochrome c oxidase (COX) activity.

Purpose of the Study:

• To investigate how mitochondrial dysfunction influences the ER stress response triggered by Aβ in AD.
• To explore the role of ER calcium (Ca2+) release in Aβ-induced ER stress-mediated apoptosis.

Main Methods:

• Utilized cybrid cell lines mimicking COX deficiency found in AD platelets.
• Treated AD and control cybrids with Aβ or ER stressors.
• Assessed ER stress markers (GRP78, caspase-4), apoptosis markers (caspase-3, PARP, TUNEL), and cell survival.
• Investigated the effect of dantrolene on Aβ-induced caspase-3 activation.

Main Results:

• AD cybrids showed more pronounced increases in ER stress markers (GRP78, caspase-4) upon Aβ or ER stressor treatment.
• AD cybrids exhibited reduced cell survival and elevated apoptosis markers (caspase-3, PARP, TUNEL).
• Dantrolene prevented Aβ-induced caspase-3 activation, indicating ER Ca2+ release involvement.

Conclusions:

• Mitochondrial dysfunction due to COX inhibition in AD potentiates susceptibility to Aβ-induced ER stress.
• This study reinforces the critical role of ER-mitochondria communication in AD apoptosis.
• ER Ca2+ release is a key mediator in the apoptotic pathway.