# Autophagic Clearance of Proteasomes and CDC48 as Models for Amyloidogenic Protein Quality Control.

> **NIH NIH R01** · WASHINGTON UNIVERSITY · 2022 · $308,228

## Abstract

PROJECT SUMMARY/ABSTRACT
Background − Maintenance of proteostasis is central to cellular fitness and is achieved through
sophisticated protein quality control (PQC) pathways that remove dysfunctional and unwanted proteins and
protein complexes that become cytotoxic if allowed to accumulate and condense. In fact, protein
aggregation encouraged by PQC defects is a hallmark of aging, cancer, and numerous human ‘aggregation-
prone’ pathologies, including amyotrophic lateral sclerosis, Alzheimer’s, Parkinson’s and Huntington’s
diseases, and related multisystem proteinopathies. Consequently, full understandings of PQC could offer
new strategies to mitigate protein aggregation and subsequent proteotoxic stress. Previous Work − We
discovered mechanistically conserved PQC routes that direct the autophagic elimination of inactive
proteasomes and the CDC48 segregase (p97/VCP in humans), which offer experimentally robust models
for describing defective protein clearance. Notably, turnover of both protein complexes shares features
with amyloidogenic protein removal, including sequestration, ubiquitylation, and subsequent recognition
by dedicated autophagic receptors, which for proteasomes also requires a trio of ubiquitin ligases that likely
work in concert to assemble appropriate poly-Ub chain topologies. Project Aims − This project proposes
to describe in detail the autophagic clearance of proteasomes and CDC48 in both yeast and Arabidopsis,
with the goal of discovering aspects central to autophagic PQC. For proteasomes, we will: (i) examine,
using genetics, fluorescence microscopy, interaction studies and ubiquitin linkage mapping, where, when,
and how the ligases San1, Rsp5 and Hul5 coordinately contribute to dysfunctional proteasome
ubiquitylation; (ii) identify ubiquitylation linkages needed to generate autophagy competent substrates; and
(iii) deduce how Hsp42-mediated sequestration into cytoplasmic membrane-less aggresomes, versus
condensation into proteasome storage granules, contributes to the process. Likewise, studies on CDC48
turnover will confirm that ubiquitylation is a key signal, followed by the identification of relevant ubiquitin
ligases and understanding of how CDC48 sequestration contributes to its turnover. Moreover, we will test
our hypothesis that the autophagic routes used to clear dysfunctional proteasomes and CDC48 also
eliminate amyloidogenic proteins that are at the heart of numerous aggregation-prone pathologies. Finally,
we will further define and expand upon a new class of autophagic receptors/adaptors that use a novel
interface to dock with ATG8 (LC3 in humans) lining autophagic vesicles, thus helping to increase the
known reach of selective autophagy. Outcomes − Through this cumulative research, we hope to define
autophagic routes relevant to aggregation-associated PQC, which will shed light on the roles of
ubiquitylation, biomolecular condensation, and autophagy in mitigating proteotoxic stress and ultimately
inform upon new...

## Key facts

- **NIH application ID:** 10366935
- **Project number:** 2R01GM124452-05
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** RICHARD DAVID VIERSTRA
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $308,228
- **Award type:** 2
- **Project period:** 2017-12-11 → 2026-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10366935

## Citation

> US National Institutes of Health, RePORTER application 10366935, Autophagic Clearance of Proteasomes and CDC48 as Models for Amyloidogenic Protein Quality Control. (2R01GM124452-05). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10366935. Licensed CC0.

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