Related Experiment Video
Updated: Aug 11, 2025
Author Spotlight: Decoding Mitochondrial Aging
Published on: June 30, 2023
Apolipoprotein E4 targets mitochondria and the mitochondria-associated membrane complex in neuropathology, including
1Gladstone Institute of Neurological Disease, 1650 Owens Street, San Francisco, CA 94158, USA; Departments of Pathology and Medicine, University of California, San Francisco, CA 94143, USA.
Abstract:
Apolipoprotein (apo) E4 sets the stage for neuropathology in Alzheimer's disease (AD) by causing mitochondrial dysfunction and altering mitochondria-associated membranes. Contact and apposition of mitochondrial-endoplasmic reticulum membranes are enhanced in brain cells in AD and associated with increases in tethering and spacing proteins that modulate many cellular processes. Contact site protein levels are higher in apoE4 cells. In apoE4 neurons, the NAD+/NADH ratio is lowered, reactive oxygen species are increased, and NAD/NADH pathway components and redox proteins are decreased. Oxidative phosphorylation is impaired and reserve ATP generation capacity is lacking. ApoE4 neurons have ∼50% fewer respiratory complex subunits (e.g., ATP synthase) and may increase translocase levels of the outer and inner mitochondrial membranes to facilitate delivery of nucleus-encoded complex subunits. Respiratory complex assembly relies on mitochondrial cristae organizing system subunits that are altered in apoE4 cells, and apoE4 increases mitochondrial proteases that control respiratory subunit composition for complex assembly.
Insights
Apolipoprotein E4 (apoE4) impairs brain cell mitochondria, leading to Alzheimer's disease (AD) neuropathology by disrupting energy production and cellular repair mechanisms.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Apolipoprotein E4 (apoE4) is a major genetic risk factor for Alzheimer's disease (AD).
- Mitochondrial dysfunction and altered mitochondria-associated membranes are implicated in AD pathogenesis.
- Aberrant contact between mitochondrial and endoplasmic reticulum membranes is observed in AD brain cells.
Purpose of the Study:
- To investigate the impact of apoE4 on mitochondrial function and mitochondria-associated membranes in neurons.
- To elucidate the molecular mechanisms by which apoE4 contributes to neuropathology.
Main Methods:
- Comparative analysis of apoE4-expressing neurons versus controls.
- Assessment of NAD+/NADH ratio, reactive oxygen species (ROS) levels, and redox protein expression.
- Evaluation of mitochondrial respiratory complex subunit levels and assembly.
- Analysis of mitochondrial proteases and translocase levels.
Main Results:
- ApoE4 expression in neurons leads to increased contact and apposition of mitochondria-endoplasmic reticulum membranes.
- ApoE4 neurons exhibit a lowered NAD+/NADH ratio, increased ROS, and decreased NAD/NADH pathway components.
- Impaired oxidative phosphorylation, reduced ATP generation capacity, and decreased respiratory complex subunits were observed in apoE4 neurons.
- Alterations in mitochondrial cristae organizing system subunits and increased mitochondrial proteases were associated with apoE4.
Conclusions:
- ApoE4 initiates neuropathology in Alzheimer's disease by causing significant mitochondrial dysfunction.
- Altered mitochondria-associated membranes and impaired respiratory complex assembly are key mechanisms driven by apoE4.
- Targeting apoE4-mediated mitochondrial defects may offer therapeutic strategies for Alzheimer's disease.
More Related Videos
15:04Interactions with and Membrane Permeabilization of Brain Mitochondria by Amyloid Fibrils
Published on: September 28, 2019
06:41Quantitative Analysis of Mitochondria-Associated Endoplasmic Reticulum Membrane (MAM) Stabilization in a Neural Model of Alzheimer's Disease (AD)
Published on: January 10, 2025
Related Concept Videos
01:26Alzheimer's Disease: Overview
The clinical diagnosis of AD hinges on the presence of memory and other cognitive impairments. Biomarkers, such as changes in Aβ...
03:03Amyloid Fibrils
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining,...
01:22Alzheimer's Disease: Treatment
01:19Translocation of Proteins into the Mitochondria
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...