# Causal variant association mechanisms in TCF21 binding coronary disease loci

> **NIH NIH R01** · STANFORD UNIVERSITY · 2024 · $553,417

## Abstract

We have identified TCF21 as the coronary artery disease (CAD) associated gene mapped by genome-wide
association studies at 6q23.2. By combining conditional deletion of Tcf21, smooth muscle cell (SMC) lineage
tracing, single cell RNA sequencing (scRNAseq), and anatomical cellular lesion analysis in the ApoE null
model, we have shown that it is upregulated in SMC to promote de-differentiation, proliferation, and migration
of medial SMC into the plaque where they contribute to the protective fibrous cap. This work profiled at a single
cell level the transition of SMC to a fibroblast like phenotype, creating cells that we term “fibromyocytes”
(FMC). Genomic studies conducted as part of this funded work have suggested that TCF21 binds and
regulates expression of a number of cooperating transcription factors (TFs) in other CAD loci to govern the
SMC-FMC transition. Further, TCF21 targeted TFs in other CAD loci modulate an SMC transition to a
chondrocyte-like phenotype, which is characterized by gene expression patterns typical of endochondral bone
formation, producing cells we term “chondromyocytes” (CMC). These findings point to two interrelated complex
gene networks that regulate SMC cell state transition as a mechanism of disease causality. Our hypothesis for
this renewal application thus proposes that: disease risk associated with SMC phenotypic transition is
mediated by TCF21 and related transcription factors that regulate interactive transcriptional networks
constituted in large part by CAD associated genes. The primary goal of work proposed here is to further
characterize these networks and define the epigenetic and transcriptional mechanisms of TF interactions that
determine the CAD risk engendered by the SMC phenotypic response to vascular stress. Specifically, in Aim 1
we will conduct single cell ATAC sequencing (scATACseq) with wildtype and Tcf21 null atherosclerotic mice,
as well as human coronary artery tissues, to map enhancers genome-wide that are differentially regulated in
SMC phenotypic transitions, and identify TFs that bind these enhancers. In Aim 2 we will perform scATACseq
and scRNAseq following CRISPR/Cas9 perturbation of identified transition TFs in a human coronary artery
smooth muscle cell de-differentiation model to examine the impact of TF knockdown on transcriptional profiles
and interactions of TFs linked to the FMC and CMC phenotypes. To investigate the relationship of SMC
phenotype to CAD risk, we will determine how perturbation of SMC transition TFs alters accessibility at
promoter regions and linked enhancer regions at CAD associated loci. In Aim 3 we will examine with molecular
methods the mechanisms of epistasis and functional interactions between the TFs that primarily define the
SMC transition phenotypes and identify transcriptional links to CAD. This work will thus characterize
fundamental processes by which SMC TFs activate phenotypic transitions through epigenetic and
transcriptional mechanisms, extending our un...

## Key facts

- **NIH application ID:** 10756972
- **Project number:** 5R01HL134817-08
- **Recipient organization:** STANFORD UNIVERSITY
- **Principal Investigator:** THOMAS QUERTERMOUS
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $553,417
- **Award type:** 5
- **Project period:** 2017-01-01 → 2024-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10756972

## Citation

> US National Institutes of Health, RePORTER application 10756972, Causal variant association mechanisms in TCF21 binding coronary disease loci (5R01HL134817-08). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10756972. Licensed CC0.

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