Dataset Information

Multidrug resistance protein 1 reduces the aggregation of mutant huntingtin in neuronal cells derived from the Huntington's disease R6/2 model.

ABSTRACT: Mutant huntingtin (mHtt) aggregation in the nucleus is the most readily apparent phenotype and cause of neuronal death in Huntington's disease (HD). Inhibiting mHtt aggregation reduces cell death in the brain and is thus a promising therapeutic approach. The results of the present study demonstrated that mHtt aggregation in the nucleus was altered by the activity of multidrug resistance protein 1 (MDR1), which was experimentally modulated by verapamil, siRNA and an expression vector. MDR1 detoxifies drugs and metabolites through its excretory functions in the membrane compartment, thereby protecting cells against death or senescence. When they were treated with verapamil, R6/2 mice showed a progressive decline in rotarod performance and increased mHtt aggregation in the brain. Using neuronal stem cells from R6/2 mice, we developed an in vitro HD model to test mHtt accumulation in the nuclei of neurons. When MDR1 activity in cells was decreased by verapamil or siRNA, mHtt aggregation in the nuclei increased, whereas the induction of MDR1 resulted in a decrease in mHtt aggregation. Thus, our data provide evidence that MDR1 plays an important role in the clearance of mHtt aggregation and may thus be a potential target for improving the survival of neurons in Huntington's disease.

SUBMITTER: Im W

PROVIDER: S-EPMC4653614 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Multidrug resistance protein 1 reduces the aggregation of mutant huntingtin in neuronal cells derived from the Huntington's disease R6/2 model.

Im Wooseok W Ban Jae-Jun JJ Chung Jin-Young JY Lee Soon-Tae ST Chu Kon K Kim Manho M

Scientific reports 20151120

Mutant huntingtin (mHtt) aggregation in the nucleus is the most readily apparent phenotype and cause of neuronal death in Huntington's disease (HD). Inhibiting mHtt aggregation reduces cell death in the brain and is thus a promising therapeutic approach. The results of the present study demonstrated that mHtt aggregation in the nucleus was altered by the activity of multidrug resistance protein 1 (MDR1), which was experimentally modulated by verapamil, siRNA and an expression vector. MDR1 detoxi ...[more]

PMID: 26586297

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Project description:The purpose of our study was to determine the relationship between mutant huntingtin (Htt) and mitochondrial dynamics in the progression of Huntington's disease (HD). We measured the mRNA levels of electron transport chain genes, and mitochondrial structural genes, Drp1 (dynamin-related protein 1), Fis1 (fission 1), Mfn1 (mitofusin 1), Mfn2 (mitofusin 2), Opa1 (optric atrophy 1), Tomm40 (translocase of outermembrane 40) and CypD (cyclophilin D) in grade III and grade IV HD patients and controls. The mutant Htt oligomers and the mitochondrial structural proteins were quantified in the striatum and frontal cortex of HD patients. Changes in expressions of the electron transport chain genes were found in HD patients and may represent a compensatory response to mitochondrial damage caused by mutant Htt. Increased expression of Drp1 and Fis1 and decreased expression of Mfn1, Mfn2, Opa1 and Tomm40 were found in HD patients relative to the controls. CypD was upregulated in HD patients, and this upregulation increased as HD progressed. Significantly increased immunoreactivity of 8-hydroxy-guanosine was found in the cortical specimens from stage III and IV HD patients relative to controls, suggesting increased oxidative DNA damage in HD patients. In contrast, significantly decreased immunoreactivities of cytochrome oxidase 1 and cytochrome b were found in HD patients relative to controls, indicating a loss of mitochondrial function in HD patients. Immunoblotting analysis revealed 15, 25 and 50 kDa mutant Htt oligomers in the brain specimens of HD patients. All oligomeric forms of mutant Htt were significantly increased in the cortical tissues of HD patients, and mutant Htt oligomers were found in the nucleus and in mitochondria. The increase in Drp1, Fis1 and CypD and the decrease in Mfn1 and Mfn2 may be responsible for abnormal mitochondrial dynamics that we found in the cortex of HD patients, and may contribute to neuronal damage in HD patients. The presence of mutant Htt oligomers in the nucleus of HD neurons and in mitochondria may disrupt neuronal functions. Based on these findings, we propose that mutant Htt in association with mitochondria imbalance and mitochondrial dynamics impairs axonal transport of mitochondria, decreases mitochondrial function and damages neurons in affected brain regions of HD patients.

Dataset Information

Multidrug resistance protein 1 reduces the aggregation of mutant huntingtin in neuronal cells derived from the Huntington's disease R6/2 model.

Publications

Multidrug resistance protein 1 reduces the aggregation of mutant huntingtin in neuronal cells derived from the Huntington's disease R6/2 model.

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