# Mechanistic analysis of axonal transport defects in neurodegenerative disease

> **NIH NIH R37** · UNIVERSITY OF PENNSYLVANIA · 2020 · $458,300

## Abstract

Project Summary
Mutations in cytoplasmic dynein or its activator dynactin are causative for neuronal diseases including heritable
forms of motor neuron degeneration and Charcot­Marie­Tooth disease. More broadly, we know that defects in
dynein­driven functions such as retrograde axonal transport are involved in the pathogenic mechanisms of
neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), Huntington’s, and Alzheimer’s.
However, the specific mechanisms involved remain unclear. Dynein is a pleiotropic cellular motor with multiple
distinct roles in the neuron. Here we will focus on the hypothesis that defects in the dynein­driven retrograde
transport of degradative organelles including lysosomes and autophagosomes are major contributors to the
axonal degeneration that characterize these diseases. The goal of this proposal is to understand the specific
mechanisms linking defects in dynein function to neurodegeneration, focusing on the following three aims: (1)
How is retrograde axonal transport altered during neurodegeneration? We hypothesize that pathological
alterations in the JNK and Cdk5 pathways lead to the dysregulation of opposing microtubule motors during
axonal transport. We will test this hypothesis using quantitative live cell imaging of vesicular transport in
primary neurons from multiple models of ALS. Then, we will mechanistically dissect how kinase mis­regulation
affects motor function using in vitro reconstitution approaches with single molecule resolution. These studies
will test the model that a disruption in the coordination of oppositely­oriented motors is the primary defect
leading to altered transport along the axon. (2) What are the pathways for autophagosome biogenesis and
cargo­loading in the neuron? We hypothesize that autophagy in the neuron follows a stereotypical and
spatially regulated pathway that is required to maintain cellular homeostasis. We will examine autophagosome
biogenesis and cargo­loading in primary sensory and motor neurons using quantitative live cell imaging,
focusing on the roles of dynein and optineurin. Then we will determine how this pathway responds to cellular
stressors, to address the hypothesis that this pathway has a limited ability to up­regulate in response to cellular
stress. (3) How do defects in dynein­driven autophagy lead to degeneration of the axon? We
hypothesize that the active, dynein­driven transport of autophagosomes is tightly linked to function, and that
defects in transport will lead to defective degradation of aging organelles and aggregated proteins. We will use
live imaging and biochemical and cellular assays to determine how defects in autophagosome transport along
the axon contribute to neurodegeneration and how distinct dynein mutations differentially perturb cellular
functions, leading to disparate clinical manifestations. Mutations in cytoplasmic dynein are sufficient to cause
human neurodegenerative diseases including spinal muscular atrophy (SMA­LE...

## Key facts

- **NIH application ID:** 9896888
- **Project number:** 5R37NS060698-12
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Erika L Holzbaur
- **Activity code:** R37 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $458,300
- **Award type:** 5
- **Project period:** 2018-04-01 → 2021-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9896888

## Citation

> US National Institutes of Health, RePORTER application 9896888, Mechanistic analysis of axonal transport defects in neurodegenerative disease (5R37NS060698-12). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9896888. Licensed CC0.

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