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Proc Natl Acad Sci U S A. 2016 Sep 20;113(38):E5655-64. doi: 10.1073/pnas.1603020113. Epub 2016 Sep 6.

TRiC subunits enhance BDNF axonal transport and rescue striatal atrophy in Huntington's disease.

Author information

1
Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093;
2
The University of Texas M. D. Anderson Cancer Center, Houston, TX 77054;
3
Department of Neurobiology and Behavior, University of California, Irvine, CA 92697;
4
National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030;
5
Department of Neurobiology and Behavior, University of California, Irvine, CA 92697; Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92697.
6
Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093; chw049@ucsd.edu wmobley@ucsd.edu.

Abstract

Corticostriatal atrophy is a cardinal manifestation of Huntington's disease (HD). However, the mechanism(s) by which mutant huntingtin (mHTT) protein contributes to the degeneration of the corticostriatal circuit is not well understood. We recreated the corticostriatal circuit in microfluidic chambers, pairing cortical and striatal neurons from the BACHD model of HD and its WT control. There were reduced synaptic connectivity and atrophy of striatal neurons in cultures in which BACHD cortical and striatal neurons were paired. However, these changes were prevented if WT cortical neurons were paired with BACHD striatal neurons; synthesis and release of brain-derived neurotrophic factor (BDNF) from WT cortical axons were responsible. Consistent with these findings, there was a marked reduction in anterograde transport of BDNF in BACHD cortical neurons. Subunits of the cytosolic chaperonin T-complex 1 (TCP-1) ring complex (TRiC or CCT for chaperonin containing TCP-1) have been shown to reduce mHTT levels. Both CCT3 and the apical domain of CCT1 (ApiCCT1) decreased the level of mHTT in BACHD cortical neurons. In cortical axons, they normalized anterograde BDNF transport, restored retrograde BDNF transport, and normalized lysosomal transport. Importantly, treating BACHD cortical neurons with ApiCCT1 prevented BACHD striatal neuronal atrophy by enhancing release of BDNF that subsequently acts through tyrosine receptor kinase B (TrkB) receptor on striatal neurons. Our findings are evidence that TRiC reagent-mediated reductions in mHTT enhanced BDNF delivery to restore the trophic status of BACHD striatal neurons.

KEYWORDS:

BACHD mouse model; BDNF transport; Huntington’s disease; TRiC chaperonin; striatal atrophy

PMID:
27601642
PMCID:
PMC5035849
DOI:
10.1073/pnas.1603020113
[Indexed for MEDLINE]
Free PMC Article

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