# Dissecting molecular pathways underlying Human Overgrowth Syndrome

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2020 · $385,000

## Abstract

Abstract
Human overgrowth syndrome is a class of diseases characterized by systemic or regional excess growth
compared to peers of the same age. Recent human genetic studies have revealed a series of missense
mutations in epigenetic regulators including a de novo DNA methyltransferase enzyme DNMT3A. It is
suggested that cells derived from affected patients would exhibit defects in epigenetic modifications such as
DNA methylation and histone modifications, leading to the alteration of specific gene expression. However, the
molecular mechanism underlying pathogenesis of overgrowth syndrome is largely unknown. We therefore
propose to develop stem cell models that are better suited to understand the molecular basis of DNMT3A
mutations in overgrowth syndrome with intellectual disability (coined Tatton-Brown-Rahman Syndrome in
OMIM). In Specific Aim 1, we will generate isogenic human and mouse ESCs (hESCs and mESCs) carrying
either wild-type DNMT3 allele or a spectrum of specific DNMT3A point mutations via CRISPR/Cas9 mediated
gene editing technology. DNMT3A mutant hESCs and mESCs will be extensively characterized for potential
defects in cell cycle regulation, DNA methylation, H3K27me3 and RNA transcriptome in order to determine
convergent molecular pathways associated different types of DNMT3A mutations. To directly examine the
defects in cell lineages involved in craniofacial development, in Specific Aim 2, we will examine the impact of
DNMT3A mutations on sequential differentiation of mutant ESCs into neural precursor cells (NPCs), cortical-
like neurons, glial cells, as well as neural crest derivatives. By performing analysis of DNA methylation,
H3K27me3, and RNA transcriptome at different stage of cell differentiation, we will define shared molecular
changes and regulatory pathways in RNA transcriptome and DNA methylation that underlie pathogenesis of
craniofacial and brain development in vitro. In Aim 3, we will generate transgenic mice carrying DNMT3A
mutations, and examine mouse mutant phenotypes relevant to overgrowth. Molecular characterization of brain
neurogenesis and craniofacial development in vivo in mutant mice will lead to the identification of either novel
or known signaling pathways (such as PTEN/mTOR/IGF signaling) associated with overgrowth phenotype.
Moreover, we will determine whether the defects of cell growth, proliferation, and differentiation in vivo will be
consistent with what we observed in vitro in both human and mouse stem cell differentiation model in Aim 2.
Finally, we will also perform learning and memory behavioral tests to determine the association of DNMT3A
mutations with potential learning and memory deficits. Our proposed research will provide a novel approach to
understanding the molecular pathogenesis of human DNMT3A overgrowth syndrome, potentially leading to the
development of a therapeutic approach to prevent or cure human overgrowth disorders.

## Key facts

- **NIH application ID:** 9960493
- **Project number:** 5R01DE025474-05
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** Guoping Fan
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $385,000
- **Award type:** 5
- **Project period:** 2016-07-05 → 2021-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9960493

## Citation

> US National Institutes of Health, RePORTER application 9960493, Dissecting molecular pathways underlying Human Overgrowth Syndrome (5R01DE025474-05). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/9960493. Licensed CC0.

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