# Project 2: The impact of TRiC reagents on mHTT-induced neuronal degeneration in vitro

> **NIH NIH P01** · UNIVERSITY OF CALIFORNIA-IRVINE · 2020 · $230,286

## Abstract

Project Summary/Abstract
Huntington disease (HD) is caused by a mutation in exon 1 of the gene for Huntingtin (HTT). The mutant
protein (mHTT), which contains an expanded stretch of glutamine residues (polyQ), is responsible for all HD
manifestations, including dysfunction and degeneration of neurons. The overall goal of this Project is the
discovery and development of effective treatments for HD. The Project is informed by evidence that mHTT is a
client protein of the cytosolic chaperonin TRiC and that TRiC overexpression prevents or rescues mHTT-
induced phenotypes in model systems. In particular, we have shown that individual TRiC subunits (CCTs), as
well as the soluble apical portion of CCT1 (ApiCCT1), reverse deficits in BDNF trafficking and signaling in
BACHD neurons in vitro. Project 2 will decipher whether or not TRiC and TRiC-derived proteins (hereafter,
TRiC reagents) act in vitro to prevent dysfunction and degeneration of cortical and striatal neurons from the
BACHD model. Our hypothesis is that that increasing the levels of TRiC or TRiC-derived reagents will
abrogate and/or reverse mHTT- linked pathogenesis. We propose four Aims to examine in vitro
quantitative and temporal features of HD pathogenesis. In Aim 1 we will further define deficits in axonal
trafficking and signaling of BDNF in the BACHD model in vitro; we will confirm and further explore the ability of
TRiC-derived reagents to prevent or reverse deficits. We will begin with reagents proven effective (CCT3, 5
and Apical CCT1) and test reagents coming from Project 1. In Aim 2, we will define deficits in BACHD neuron
phenotypes: synapse formation, synaptic connectivity, gene expression, structure of neuronal somas and
processes, mitochondrial function and calcium homeostasis. The timing of and possible progression of deficits
will be defined and the impact of TRiC reagents explored. In Aim 3, we will define deficits in proteostasis in
BACHD neurons examining clearance of mHTT that may involve protein folding, ER stress, and the UPS and
autophagy/lysosome pathways. Whether introduction of TRiC reagents prevent and/or reverse changes will be
examined. In Aim 4, we will examine iPSC-differentiated neurons from HD patients to determine whether
deficits defined in Aim1-3 are detected and, if so, determine whether they are TRiC reagent-responsive.
Project 2 is expected to enhance considerably understanding of HD pathogenesis and to define a novel
approach to potential treatment. It is possible that TRiC and TRiC-inspired approaches may elucidate
pathogenesis and treatment of other neurodegenerative disorders, including Alzheimer disease, Parkinson
disease and ALS.

## Key facts

- **NIH application ID:** 9936262
- **Project number:** 5P01NS092525-05
- **Recipient organization:** UNIVERSITY OF CALIFORNIA-IRVINE
- **Principal Investigator:** William C Mobley
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $230,286
- **Award type:** 5
- **Project period:** — → 2022-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9936262

## Citation

> US National Institutes of Health, RePORTER application 9936262, Project 2: The impact of TRiC reagents on mHTT-induced neuronal degeneration in vitro (5P01NS092525-05). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9936262. Licensed CC0.

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