# Proteomics of the Proteasome Interacting Networks

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA-IRVINE · 2020 · $353,250

## Abstract

Huntington’s disease (HD) is one of the most devastating neurodegenerative disorders (NDs) that currently
lacks effective therapies. Caused by toxic aggregation of mutant Huntingtin (Htt) proteins carrying abnormally
long polyglutamine (polyQ) repeats, their timely removal through proteasomal degradation is critical for
delaying onset of the disease. Given its crucial role as the central machine responsible for degradation of
damaged and misfolded proteins such as Htt and other aggregation-prone proteins, 26S proteasome
impairment has been recognized as one of the hallmarks of NDs associated with neuropathology. While it has
been suggested that protein aggregates can induce conformational changes in the 26S to reduce its function,
activation of proteasomes through phosphorylation appears to enhance the removal of Htt mutants. However,
the molecular details underlying proteasome inhibition and activation in HD remain unclear. To address these
unknowns, it is essential to quantitatively assess Htt aggregation and phosphorylation-dependent
conformations of the 26S in cells to obtain a mechanistic understanding of the structure-function relationship of
HD-associated proteasomes. Such investigations have remained previously unexplored due to lack of proper
strategies. During the current funding cycle, we have demonstrated that cross-linking mass spectrometry (XL-
MS) is effective for studying in vivo structural dynamics of proteasome complexes. While the development of
specific residue-targeting MS-cleavable cross-linkers has further improved our capability to map protein-protein
interactions (PPIs), interactions at hydrophobic regions remain difficult to characterize due to lack of targetable
residues. Therefore, it is necessary to explore alternative chemistries for capturing structural details in those
regions in order to comprehensively dissect proteasome conformational dynamics in cells. Here, we aim to
develop photochemistry-based XL-MS platforms to enable their application for complex PPI mapping in vivo
and in vitro. In addition, we intend to develop integrated QXL-MS platforms to define the temporal dynamics of
the 26S proteasome upon Htt aggregation and phosphorylation, yielding molecular details to delineate the
structure-function relationship of HD-impaired proteasomes. This project not only represents a great leap in
XL-MS technology, but also helps address important yet unresolved biological questions associated with HD
that have great potential for future therapeutic exploitation.

## Key facts

- **NIH application ID:** 9986760
- **Project number:** 5R01GM074830-15
- **Recipient organization:** UNIVERSITY OF CALIFORNIA-IRVINE
- **Principal Investigator:** Lan Huang
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $353,250
- **Award type:** 5
- **Project period:** 2005-08-01 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9986760

## Citation

> US National Institutes of Health, RePORTER application 9986760, Proteomics of the Proteasome Interacting Networks (5R01GM074830-15). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9986760. Licensed CC0.

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