Role of the cardiac neural crest in development and regeneration

The neural crest is a versatile cell population that holds great promise for the purposes of regenerative
medicine due to its ability to form a multitude of diverse progeny ranging from the peripheral nervous system to
the craniofacial skeleton and portions of the heart. The “cardiac neural crest” arises from the dorsal hindbrain
and has the unique potential to form ectomesenchymal derivatives of the heart like the outflow tract septum
and a subpopulation of ventricular cardiomyocytes Our preliminary data have uncovered a cardiac crest
specific gene regulatory circuit that can reprogram other neural crest populations to cardiac crest fates and
have revealed a requirement for cardiac crest-derived cells in adult heart regeneration in zebrafish. Here, we
propose to elucidate the role of cardiac-specific subcircuit genes and their targets in acquisition of
particular cell fates in the embryonic heart. To extend this to adult stages, we will examine gene
regulatory changes that accompany loss of regenerative in mammals and examine the possible role of
TGFβ and downstream genes in cardiac neural crest-derived cells therein. As the cardiac crest is a
critically important embryonic cell population for normal formation and function of the heart, these studies hold
the promise of uncovering novel potential target genes involved in cardiovascular birth defects and repair.
Aim 1: Effects of “reprogramming” trunk neural crest identity to a cardiac crest fate. We will use single
cell RNA-seq and single cell (sc) ATAC-seq to characterize transcriptional and epigenetic changes that occur
in reprogrammed embryonic trunk crest cells over time and trace the fates of reprogrammed cells compared to
endogenous cardiac neural crest cells.
Aim 2: Role of Tgif1 and co-expressed putative downstream genes in outflow tract development. By
coupling loss of function analysis with single cell RNA-seq, we will examine gene expression differences after
depletion of Tgif1 as well as other co-expressed genes, including Twist1, FoxC2, and FoxP1. We will test their
order of expression and whether they are downstream effectors of Tgif1 by testing the regulatory relationships
between these genes. Finally, we will examine the long term effects of their loss of function on development of
the cardiovascular system to identify key genes involved in cardiac neural crest fate acquisition.
Aim 3: Exploring the role of cardiac neural crest-derived cells in mammalian heart regeneration.
Newborn mice can regenerate their hearts after damage from post-natal (P) days 1 – 7. Our preliminary RNA-
seq data suggest that there are profound gene regulatory changes that occur in cardiac neural crest derived
cells between P1 and P7/8, including an upregulation of genes associated with the TGFβ pathway. Using
scRNA-seq coupled with scATAC-seq, we will prepare a careful time course of changes in postnatal cardiac
neural crest-derived heart cells under control and cryo-damage conditions and test whether genetic ablation of
the neural crest blocks regenerative ability and if inhibition of the TGFβ pathway promotes heart regeneration.

Grant Number: 5R01HL169287-02
NIH Institute/Center: NIH
Principal Investigator: Marianne Bronner