Neuronal cell death caused by inhibition of intracellular cholesterol trafficking is caspase dependent and associated with activation of the mitochondrial apoptosis pathway.
An elevated level of cholesterol in mitochondrial membranes of Niemann-Pick disease type C1 (NPC1) mouse brains and neural cells has been found to cause mitochondrial dysfunction. In this study, we demonstrate that inhibition of intracellular cholesterol trafficking in primary neurons by class 2 amphiphiles, which mimics the major biochemical and cellular feature of NPC1, led to not only impaired mitochondrial function but also activation of the mitochondrial apoptosis pathway. In activation of this pathway both cytochrome c and Smac/Diablo were released but apoptosis-inducing factor (AIF) was not involved. Treatment of the neurons with taurine, a caspase 9-specific inhibitor, could prevent the amphiphile-induced apoptotic cell death, suggesting that formation of apoptosome, followed by caspase 9 and caspase 3 activation, might play a critical role in the neuronal death pathway. Taken together, the mitochondria-dependent death cascade induced by blocking intracellular cholesterol trafficking was caspase dependent. The findings provide clues for both understanding the molecular basis of neurodegeneration in NPC1 disease and developing therapeutic strategies for treatment of this disorder.
Huang
Zhili
Z
Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Hou
Qingsong
Q
Cheung
Nam Sang
NS
Li
Qiu-Tian
QT
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D002784:Cholesterol / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D009410:Nerve Degeneration / Q000378:metabolism* / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009542:Niemann-Pick Diseases / Q000378:metabolism / Q000503:physiopathology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013501:Surface-Active Agents / Q000494:pharmacology
D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; D061945:Caspase Inhibitors; C499605:Diablo protein, mouse; D024101:Mitochondrial Proteins; D013501:Surface-Active Agents; D045304:Cytochromes c; D002784:Cholesterol; C505409:Casp3 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases