# Protein-based Therapeutics to treat  nucleotide expansion disorders associated with aberrant gene expression

> **NIH NIH R43** · ENZERNA BIOSCIENCES, LLC · 2020 · $231,045

## Abstract

Nucleotide expansion disorders are comprised of a group of genetic diseases that are classified in two
groups depending on whether the repeats (e.g., CCG, CCCCGG, GAA, CTG, and CAG) are located within a
coding or non-coding region of the genome. There are no curative therapies for nucleotide expansion disorders;
it is only possible to provide palliative measures to manage the clinical symptoms. Over 25 nucleotide disorders,
mainly associated with neurodegenerative diseases have been identified, including Huntington’s disease,
myotonic dystrophy and Friedreich’s ataxia. Friedreich’s Ataxia (FA), associated with an expanded GAA repeat
array (up to 1700 repeats; normal alleles have 10-66 repeats) in the first intron of the frataxin gene, is the only
nucleotide expansion disorder that is a recessive mutation. The expanded GAA repeat leads to silencing of
frataxin (FXN) expression, presumably due to the formation of a RNA:DNA triplex that halts transcription.
 FA affects 1:50,000 individuals, making it the most common form of hereditary ataxia. FA is associated
with impaired mitochondrial iron handling and makes cells highly susceptible to ROS-mediated bioenergetic
dysfunction. Clinical manifestations of Friedreich’s Ataxia occur across organ systems, and include muscle
weakness, movement disorders, poor neurological development and function, diabetes, and cardiac
complications. There are no FDA approved disease modifying drugs for FA. Therapeutic strategies directly
targeting expanded repeats in FXN mRNA, such as antisense oligonucleotides (ASO), have produced promising
results. However, difficulties in ASO delivery and need for lifelong administration of the ASO therapeutic remain
limiting factors for ASO-based therapies. We seek to develop a protein-based therapeutic approach for FA by
designing RNA binding proteins, based on the PUF domain family of RNA binding protein, that recognize
GAA repeats [PUF(GAA)] in mutated FXN mRNA and assess the ability of PUF(GAA) to reverse the
transcriptional silencing of FXN expression. Sucess will be indicated by restoration of FXN expression to
35-50% of normal levels of FXN expression and rescue of two mitochondrial defects associated with FA:
resistance to metabolic stress when propagated in galactose; and resistance to H2O2-induced inhibition of
mitochondrial respiration.
 Once feasibility is demonstrated, Phase II will focus on the development of research grade adenoviral
associated vectors (AAV) that constitutively express nuclear targeted PUF(GAA) to develop gene delivery
protocols and for initial efficacy and safety studies in animal models of FA before progressing to production of
clinical grade AAV for IND enabling safety and efficacy studies of this innovative curative gene therapeutic for
FA. In the long term, combined with gene delivery vectors, our innovative gene therapeutic approach may
provide a new route for targeted therapy for nucleotide expansion disorders that disrupt gene expression.

## Key facts

- **NIH application ID:** 10086917
- **Project number:** 1R43GM139666-01
- **Recipient organization:** ENZERNA BIOSCIENCES, LLC
- **Principal Investigator:** JOSEPH C. RUIZ
- **Activity code:** R43 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $231,045
- **Award type:** 1
- **Project period:** 2020-08-01 → 2022-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10086917

## Citation

> US National Institutes of Health, RePORTER application 10086917, Protein-based Therapeutics to treat  nucleotide expansion disorders associated with aberrant gene expression (1R43GM139666-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10086917. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*