# Roles of TET2-dependent DNA demethylation intermediates in hematological malignancies

> **NIH NIH R01** · UNIVERSITY OF TEXAS HLTH SCIENCE CENTER · 2022 · $561,228

## Abstract

Abstract
TET2 is one of the most commonly mutated/deleted genes in adult hematological malignancies. TET2
mutations are also prevalent in healthy elderly individuals with clonal hematopoiesis. Thus, TET2 mutations are
an ancestral mutational event that drives non-malignant clonal outgrowth and facilitates hematological
malignancy transformation. Indeed, Tet2 loss in mice leads to increased HSC self-renewal and the
development of various hematological malignancies. However, the underlying molecular mechanisms remain
largely unknown. TET2 is a dioxygenase that catalyzes the stepwise conversion of 5mC to 5hmC, 5fC and
5caC, initial steps of active DNA demethylation. The oxidation and demethylation of 5mC in the genome are
regulated in a sophisticated manner. It has been shown that 5hmC and 5fC are present as relatively stable
cytosine modifications in genomic DNA of both dividing and nondividing cells. TET2 likely requires its catalytic
activity to exert tumor suppressive function in HSC/HPCs. We recently showed that Tet2 loss leads to
hypermutagenicity in HSC/HPCs, preferentially at genomic sites that gained 5hmC and TET2 normally
binds to. TET2 loss would naturally remove part of, but also creates a new set of, stable 5hmC and 5fC marks
in genomic DNA for an extended period in HSC/HPCs. However, the physiological significance of the TET2
loss-mediated stalling of 5hmC/5fC formation in HSC/HPC regulation and pathogenesis of hematological
malignancies remains to be elucidated. We have created two novel Tet2 5hmC stalling (T1285E, Tet2E/+) and
Tet2 catalytic-inactive (H1295Y/D1297A, Tet2YA/+) mutant knock-in mouse models, which provide us unique
tools to elucidate the specific biological role of TET2 catalytic activity and TET2-dependent 5hmC5fC
conversion in HSC/HPC regulation and hematological malignancies. In Aim 1, we will elucidate the biological
role of Tet2 loss-associated stalling of 5hmC and 5fC/5caC formation in HSC/HPC regulation and
hematological malignancies using the catalytic-inactive and 5hmC stalling Tet2 mutant mouse models. In Aim
2, we will determine the effects of TET2 enzymatic activity and specific TET2-dependent DNA demethylation
intermediates on gene expression regulation and genomic mutagenicity in HSC/HPCs. Using WT, Tet2-/-,
Tet2YA/YA and Tet2E/E HSC/HPCs, we will: (1) perform RNA-seq to identify the differentially expressed genes
(DEGs); (2) map genome-wide 5mC/5hmC/5fC/5caC marks; and (3) perform whole-exome sequencing to
identify spontaneous mutations. Integrational analysis of these data sets will allow us to determine whether the
DEGs and mutations caused by loss of TET2 catalytic activity or 5hmC5fC conversion correlate with specific
5mC/5hmC/5fC/5caC alterations in HSC/HPCs upon Tet2 loss. These studies could unveil potential roles of
specific TET2-dependent cytosine species in: (1) gene regulation and genomic mutagenicity in HSC/HPCs; (2)
TET2 loss-mediated HSC/HPC dysregulation and hematological malignancies. Th...

## Key facts

- **NIH application ID:** 10320391
- **Project number:** 5R01HL145883-04
- **Recipient organization:** UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
- **Principal Investigator:** Mingjiang Xu
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $561,228
- **Award type:** 5
- **Project period:** 2019-01-15 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10320391

## Citation

> US National Institutes of Health, RePORTER application 10320391, Roles of TET2-dependent DNA demethylation intermediates in hematological malignancies (5R01HL145883-04). Retrieved via AI Analytics 2026-06-11 from https://api.ai-analytics.org/grant/nih/10320391. Licensed CC0.

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