# Hedgehog signaling controls a gene regulatory network necessary for directing early cardiovasculogenesis

> **NIH NIH F30** · UNIVERSITY OF CHICAGO · 2020 · $48,410

## Abstract

ABSTRACT
Congenital heart disease (CHD) is the most common birth defect—occurring in as many as 3 in every 100 live
births. Despite its frequency, the genetic etiologies of CHD remain elusive due to prevalent contribution of
noncoding variation and genetic modifiers. As a lab we attempt to distill this complexity though understanding
the underlying gene regulatory networks involved in CHD. In this study, we uncover a gene regulatory network
essential for the proper development of cardiovascular lineages downstream of the hedgehog (hh) signaling, a
master regulator of cell fate determination. Our previous work has shown that Hedgehog signaling is required
for second heart field-derived cardiac structures. Using Genetic Inducible Fate Mapping, we observed that late
labeling of cardiac progenitors (E8.5 and later) labeled only second heart field structures while early labeling of
cardiac progenitors (E6.5) additionally labeled first heart field derived structures. Germline removal of all hh
signaling, through ablation of a key membrane-bound receptor, smoothened (smo), caused hypoplasia of the
linear heart tube, a failure of chamber expansion, and early embryonic lethality. Conditional smo removal
using Mesp1-Cre recapitulated the germline phenotype whereas smo removal using Nxk2-5-Cre supported
chamber formation, restricting the requirement for hh signaling to early mesoderm. RNA-seq of Mesp1+ cells
overexpressing Gli3R, the primary hh-signaling transcriptional repressor revealed upregulation of lineage-
determining transcriptional programs for differentiating cardiovascular lineages at embryonic day 7.5 but down-
regulation of factors involved with maintenance of progenitor identity. We hypothesize that hedgehog signaling
controls a gene regulatory network required for the proper establishment of cardiovascular lineages by
controlling the differentiation timing of mesodermal progenitors. As a means to accomplish this, we propose to
1) Validate and study the developmental mechanisms of transcriptional disruption of cell fate decisions in the
cardiogenic mesoderm 2) Study the cellular and mechanistic basis for the severe hypoplastic cardiac defects
caused by disruption in early hh singaling. These data will be integrated as a means to understand not only the
mechanism by which hh controls early mesodermal patterning, but to contribute foundational knowledge
towards the elucidation of CHD etiology by providing a novel mechanism for hypoplastic cardiac phenotypes.

## Key facts

- **NIH application ID:** 10005442
- **Project number:** 5F30HL136200-04
- **Recipient organization:** UNIVERSITY OF CHICAGO
- **Principal Investigator:** Alexander Guzzetta
- **Activity code:** F30 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $48,410
- **Award type:** 5
- **Project period:** 2017-09-30 → 2021-09-29

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10005442

## Citation

> US National Institutes of Health, RePORTER application 10005442, Hedgehog signaling controls a gene regulatory network necessary for directing early cardiovasculogenesis (5F30HL136200-04). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10005442. Licensed CC0.

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