# Setting the Stage for Replacement of Mitochondrial Genes

> **NIH NIH R01** · UNIVERSITY OF MIAMI SCHOOL OF MEDICINE · 2021 · $403,232

## Abstract

Project Summary
 We propose to develop a monomeric DNA editing platform to eliminated mutant mtDNA (mitoARCUS).
In collaboration with Precision Biosciences, we will develop and characterize a new class of mitochondrial editing
enzymes that are smaller and simpler than TALENs, while still highly specific for the mutant mtDNA. This
platform is based on the I-CreI homing endonuclease, which was modified to work as a monomer, becoming
more amenable to viral packaging and delivery in a clinical setting. We plan to characterize mitoArcus for three
pathogenic mtDNA mutations, including: a) Human 4.9kbp Common deletion; b) Human MELAS tRNALeu(UUR)
m.3243G, d) the mouse tRNAAla m.5024T. Once the mitoArcus enzymes are characterized in established cell
lines, we will test their ability to change mtDNA heteroplasmy and restore function to clinically-relevant models.
These will include human motor neuron organoids ex vivo and and the mouse retina in vivo. Finally, we will test
a newly described base editing tool (DdCBE) in an in vivo model. This new base editor architecture (DdCBE),
specifically edit thymidines on mtDNA. This was possible, because this architecture is not based on the CRISPR,
thereby not requiring a gRNA component that cannot be easily imported into mitochondria. In collaboration
with David Liu's lab at Harvard/Broad, we will test whether mtDNA base editing works in a mouse model
harboring a pathogenic mtDNA mutation in the tRNAAla gene.

## Key facts

- **NIH application ID:** 10295547
- **Project number:** 2R01EY010804-26
- **Recipient organization:** UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
- **Principal Investigator:** Carlos Torres Moraes
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $403,232
- **Award type:** 2
- **Project period:** 1994-12-01 → 2026-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10295547

## Citation

> US National Institutes of Health, RePORTER application 10295547, Setting the Stage for Replacement of Mitochondrial Genes (2R01EY010804-26). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10295547. Licensed CC0.

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