# Direct Oxidative Nucleic Acids Demethylation

> **NIH NIH R01** · UNIVERSITY OF CHICAGO · 2022 · $387,610

## Abstract

Project Summary/Abstract
Reversible chemical modifications on DNA and histones are known to significantly impact
mammalian gene expression regulation. Prior to our work, no example of reversible chemical
modifications on RNA that could affect gene expression had been shown. We previously
discovered the first two RNA demethylases: FTO, a protein associated with human fat mass
obesity, and ALKBH5, a protein that affects spermatogenesis in a mouse model. These two
proteins belong to the AlkB family iron- and 2-ketoglutarate (2-KG)-dependent dioxygenases
and catalyze oxidative demethylation of the most prevalent internal modifications of mammalian
messenger RNA (mRNA) and other nuclear RNA, N6-methyladenosine (m6A). These studies
provided the first demonstration of reversible RNA modification, and stimulated the emergence
of a new area of biological studies on RNA modifications in gene expression regulation. In the
past funding period, we have demonstrated oncogenic roles of both FTO and ALKBH5 in human
cancers. We have also discovered the first tRNA demethylase, ALKBH1, which reverses the N1-
methyladenosine (m1A) in tRNA to significantly affect translation initiation and elongation.
In the current application, we plan to thoroughly characterize the cytoplasmic versus nuclear
RNA demethylation by FTO. Our preliminary studies revealed that RNA substrates of FTO can
vary dramatically in different cellular compartments. While FTO is generally regarded as a
nuclear protein, it can localize to cytoplasm and mediates functionally significant cytoplasmic
RNA demethylation. Previous studies have also uncovered intriguing roles of FTO in UV DNA
damage response. Its nuclear demethylation activity may alter the chromatin state and affect
recruitment of various factors in damage response. We plan to investigate the extent of nuclear
versus cytoplasmic demethylation and understand factors that dictate the cytoplasmic location
and demethylation of FTO. These new information will be critical in evaluating small molecule
inhibitors that target FTO to suppress tumor progression. In addition to mRNA m6A
demethylation, we have recently discovered that ALKBH7, a protein significantly affects
mammalian energy homeostasis, is a mitochondrial tRNA demethylase that mediates
demethylation of mitochondrial tRNA N2,N2-dimethylguanine (m22G) and affects cellular
response to oxidizing agents. We will perform detailed biochemical, structural, and functional
characterization of this new tRNA demethylation activity, and reveal its potential impacts on
mitochondrial activity.

## Key facts

- **NIH application ID:** 10330547
- **Project number:** 5R01ES030546-17
- **Recipient organization:** UNIVERSITY OF CHICAGO
- **Principal Investigator:** CHUAN HE
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $387,610
- **Award type:** 5
- **Project period:** 2005-08-01 → 2024-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10330547

## Citation

> US National Institutes of Health, RePORTER application 10330547, Direct Oxidative Nucleic Acids Demethylation (5R01ES030546-17). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10330547. Licensed CC0.

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