# Impeding transcription of expanded microsatellite repeats using deactivated Cas9

> **NIH NIH R01** · UNIVERSITY OF FLORIDA · 2020 · $378,133

## Abstract

Transcription of expanded microsatellite repeats is associated with a number of human diseases, including
myotonic dystrophy (DM), Fuch's endothelial corneal dystrophy, and C9orf72 ALS/FTD (C9ALS/FTD), among
others. Eliminating or reducing production of RNA and proteins arising from these expanded loci holds
therapeutic benefit. Here, we will test the hypothesis that a deactivated form of the Cas9 enzyme impedes
transcription across expanded microsatellite repeats, in cell and animal models of DM and C9ALS/FTD. We
have previously observed a repeat length-, PAM-, and strand-dependent reduction in the abundance of repeat-
containing RNAs upon targeting dCas9 directly to repeat sequences. Aberrant Muscleblind-dependent splicing
patterns were rescued in DM1 cells, and production of RAN peptides characteristic of C9orf72 ALS/FTD cells
was drastically decreased. Pathological CUG-containing RNA foci in DM1 mouse model muscle fibers was
reduced by dCas9/gRNA delivered by adeno-associated virus. These observations suggest that transcription
of microsatellite repeat-containing RNAs is more sensitive to perturbation than transcription of other RNAs,
indicating potentially viable strategies for therapeutic intervention. In this proposal, we will assess the extent to
which virally delivered dCas9/gRNA complexes can rescue molecular, cellular, and phenotypic features in to
established models of DM1 and C9ALS/FTD. The HSALR model, which exhibits myotonia, centralized nuclei,
and altered transcriptomes characteristic of human DM1, will be used to study DM. The C9-500 BAC
transgenic model, which exhibits upper and lower motor neuron degeneration, altered gait, paralysis, and
premature death, will be used to study C9ALS/FTD. Our proposed experiments will establish whether inhibition
of toxic repeat transcription can rescue disease phenotypes, and define a window around which reduction of
toxic RNA abundance is therapeutic.

## Key facts

- **NIH application ID:** 9863982
- **Project number:** 5R01AG058636-02
- **Recipient organization:** UNIVERSITY OF FLORIDA
- **Principal Investigator:** Eric T Wang
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $378,133
- **Award type:** 5
- **Project period:** 2019-02-15 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9863982

## Citation

> US National Institutes of Health, RePORTER application 9863982, Impeding transcription of expanded microsatellite repeats using deactivated Cas9 (5R01AG058636-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9863982. Licensed CC0.

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