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Hum Mol Genet. 2012 Jan 15;21(2):406-20. doi: 10.1093/hmg/ddr475. Epub 2011 Oct 13.

Mutant huntingtin's interaction with mitochondrial protein Drp1 impairs mitochondrial biogenesis and causes defective axonal transport and synaptic degeneration in Huntington's disease.

Author information

1
Neurogenetics Laboratory, Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA.

Abstract

The purpose of this study was to investigate the link between mutant huntingtin (Htt) and neuronal damage in relation to mitochondria in Huntington's disease (HD). In an earlier study, we determined the relationship between mutant Htt and mitochondrial dynamics/synaptic viability in HD patients. We found mitochondrial loss, abnormal mitochondrial dynamics and mutant Htt association with mitochondria in HD patients. In the current study, we sought to expand on our previous findings and further elucidate the relationship between mutant Htt and mitochondrial and synaptic deficiencies. We hypothesized that mutant Htt, in association with mitochondria, alters mitochondrial dynamics, leading to mitochondrial fragmentation and defective axonal transport of mitochondria in HD neurons. In this study, using postmortem HD brains and primary neurons from transgenic BACHD mice, we identified mutant Htt interaction with the mitochondrial protein Drp1 and factors that cause abnormal mitochondrial dynamics, including GTPase Drp1 enzymatic activity. Further, using primary neurons from BACHD mice, for the first time, we studied axonal transport of mitochondria and synaptic degeneration. We also investigated the effect of mutant Htt aggregates and oligomers in synaptic and mitochondrial deficiencies in postmortem HD brains and primary neurons from BACHD mice. We found that mutant Htt interacts with Drp1, elevates GTPase Drp1 enzymatic activity, increases abnormal mitochondrial dynamics and results in defective anterograde mitochondrial movement and synaptic deficiencies. These observations support our hypothesis and provide data that can be utilized to develop therapeutic targets that are capable of inhibiting mutant Htt interaction with Drp1, decreasing mitochondrial fragmentation, enhancing axonal transport of mitochondria and protecting synapses from toxic insults caused by mutant Htt.

PMID:
21997870
PMCID:
PMC3276281
DOI:
10.1093/hmg/ddr475
[Indexed for MEDLINE]
Free PMC Article

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