# Intermediate Filament Proteostasis and RNA regulation in Giant Axonal Neuropathy

> **NIH NIH R21** · UNIV OF NORTH CAROLINA CHAPEL HILL · 2022 · $194,375

## Abstract

ABSTRACT
Intermediate filaments (IFs) are critical structural components of the cell cytoskeleton. Neurofilaments (NFs), the
principal IFs of neurons, regulate axon size and caliber and are dysregulated in many neurodegenerative
diseases. Abnormal NF inclusions within ‘giant’ axon swellings are hallmark features of the rare and fatal disease
Giant Axonal Neuropathy (GAN), which is caused by mutations in the gene KLHL16. The origin and function of
NF inclusions in GAN are poorly understood. We have made the first observation that TDP-43, an essential
RNA-binding protein, co-localizes with NFs within large axonal inclusions of human GAN induced pluripotent
stem cell-derived motor neurons (iPSC-MNs). These findings reveal shared mechanisms between GAN and
other TDP-43 proteinopathies, most notably amyotrophic lateral sclerosis (ALS). The objective in this application
is to examine if GAN neurons are affected by abnormal RNA metabolism. The following observations and
feasibility studies form the basis of the proposal: (i) “dense granular bodies” that resemble RNA stress granules
are prominent features of IF inclusions in GAN patient neurons in vivo; (ii) The human KLHL16 mRNA associates
with TDP-43 and accumulates in stress granules; (iii) The novel, patient-derived iPSC-MN microfluidic system
we developed mirrors the axonal IF pathology of GAN and is amenable to rigorous quantitative image analysis
of the inclusions; (iv) Axonal inclusions in GAN iPSC-MNs contain TDP-43, and they can be pharmacologically
disrupted. The two main questions we aim to address here, are: 1. Do the axonal NF/TDP-43 inclusions
sequester other stress granule components and KLHL16 mRNA (Aim1), and 2. Is the presence of axonal
NF/TDP-43 inclusions associated with altered global and KLHL16-specific mRNA translation in GAN neurons?
(Aim2). We anticipate that answers to these basic questions will ultimately lead us to the origin of IF inclusions
in giant GAN axons and to the functional consequences of this striking pathology in GAN disease progression.

## Key facts

- **NIH application ID:** 10415093
- **Project number:** 5R21NS121578-02
- **Recipient organization:** UNIV OF NORTH CAROLINA CHAPEL HILL
- **Principal Investigator:** Diane Armao
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $194,375
- **Award type:** 5
- **Project period:** 2021-06-01 → 2024-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10415093

## Citation

> US National Institutes of Health, RePORTER application 10415093, Intermediate Filament Proteostasis and RNA regulation in Giant Axonal Neuropathy (5R21NS121578-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10415093. Licensed CC0.

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