Apolipoprotein E4 Domain Interaction Mediates Detrimental Effects on Mitochondria and Is a Potential Therapeutic Target for Alzheimer Disease

• Published in: The Journal of biological chemistry Vol. 286; no. 7; pp. 5215 - 5221
• Main Authors: Chen, Hung-Kai, Ji, Zhong-Sheng, Dodson, Sara E., Miranda, Rene D., Rosenblum, Charles I., Reynolds, Ian J., Freedman, Stephen B., Weisgraber, Karl H., Huang, Yadong, Mahley, Robert W.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18.02.2011; American Society for Biochemistry and Molecular Biology
• Subjects: Alzheimer Disease; Alzheimer Disease - genetics; Alzheimer Disease - metabolism; Alzheimer Disease - pathology; Animals; Apolipoprotein E; Apolipoprotein E4 - genetics; Apolipoprotein E4 - metabolism; Apolipoproteins; Cell Biology; Cell Line, Tumor; Electron Transport - genetics; Electron Transport Chain Complex Proteins - genetics; Electron Transport Chain Complex Proteins - metabolism; Humans; Mice; Mice, Knockout; Mitochondria; Mitochondria - genetics; Mitochondria - metabolism; Mitochondria - pathology; Neurodegeneration; Neurons - metabolism; Neurons - pathology; Protein Structure; Protein Structure, Tertiary; Risk Factors; Mitochondria; Protein Structure; Alzheimer Disease; Apolipoproteins; Neurodegeneration; Apolipoprotein E
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1074/jbc.M110.151084

Apolipoprotein (apo) E4 is the major genetic risk factor for late-onset Alzheimer disease (AD). ApoE4 assumes a pathological conformation through an intramolecular interaction mediated by Arg-61 in the amino-terminal domain and Glu-255 in the carboxyl-terminal domain, referred to as apoE4 domain interaction. Because AD is associated with mitochondrial dysfunction, we examined the effect of apoE4 domain interaction on mitochondrial respiratory function. Steady-state amounts of mitochondrial respiratory complexes were examined in neurons cultured from brain cortices of neuron-specific enolase promoter-driven apoE3 (NSE-apoE3) or apoE4 (NSE-apoE4) transgenic mice. All subunits of mitochondrial respiratory complexes assessed were significantly lower in NSE-apoE4 neurons compared with NSE-apoE3 neurons. However, no significant differences in levels of mitochondrial complexes were detected between astrocytes expressing different apoE isoforms driven by the glial fibrillary acidic protein promoter, leading to our conclusion that the effect of apoE4 is neuron specific. In neuroblastoma Neuro-2A (N2A) cells, apoE4 expression reduced the levels of mitochondrial respiratory complexes I, IV, and V. Complex IV enzymatic activity was also decreased, lowering mitochondrial respiratory capacity. Mutant apoE4 (apoE4-Thr-61) lacking domain interaction did not induce mitochondrial dysfunction in N2A cells, indicating that the effect is specific to apoE4-expressing cells and dependent on domain interaction. Consistent with this finding, treatment of apoE4-expressing N2A cells with a small molecule that disrupts apoE4 domain interaction restored mitochondrial respiratory complex IV levels. These results suggest that pharmacological intervention with small molecules that disrupt apoE4 domain interaction is a potential therapeutic approach for apoE4-carrying AD subjects.