# Decoding regulatory nodes controlling growth and proportion of the skull

> **NIH NIH F32** · BOSTON CHILDREN'S HOSPITAL · 2021 · $69,362

## Abstract

PROJECT SUMMARY
The skull is comprised of bones of different embryonic origins that articulate to encase the brain, to protect the
sense organs, and to enable mastication. Well-orchestrated signaling and morphological events generate the
seamless morphology of the craniofacial complex. Of central importance are the cranial neural crest cells
(CNCCs) that migrate from the anterior neural folds to populate the oropharyngeal arches. CNCCs acquire
axial identity from midbrain and hindbrain segmentation. Modifications to gene expression of CNCCs, their
precursors, their derivatives, or even interacting tissues may underlie both normal variation and common
craniofacial malformations. Although the gene regulatory networks that govern early specification of CNCCs
are well known, we still lack detailed knowledge of later developmental events involving CNCC derivatives and
how this relates to fundamental mechanisms of disease. The experiments outlined in this proposal will tease
apart the morphological consequences of genotype. We expect that loci modifying the relative proportions of
the skull and face will have commonalities amongst jawed vertebrates, as the head is an ancestral trait. Our
prior phylogenomic comparisons identified fixed loci correlated with differential developmental prognathism.
One of the regions identified encompasses a locus containing a large, cis-regulatory region highly conserved in
all jawed vertebrates. This locus rests in an intron of agap1, and has retained directional synteny with the
nearest neighbor, homeobox gene gbx2, over all of vertebrate evolution. This 343 base pair (bp) region is
defined as having over 90% identity among vertebrates. A core of over 190bp is retained with 100% identity
among primates, suggesting deep conservation preserved by strong selective pressure and a potential role in
human development. Preliminary analyses suggest the region may participate in a broader regulatory hub that
modulates expression of gbx2. As gbx2 is essential for patterning CNCCs, and is expressed in the
oropharyngeal arches, my hypothesis is that the conserved non-coding region we identified acts as a
specific enhancer for gbx2, mediating patterning of the forming arches and leading to proportional
changes in outgrowth of the jaws. I will test this hypothesis by determining the function of components of the
regulatory hub and their contributions to proper growth and form of the jaws. I will analyze necessity and
function of orthologous sequences from zebrafish, chimp, and human, as well as determine the role of gbx2 in
craniofacial morphology. Outcome measures include long-term assessment of CNCC migration and
differentiation in vivo, and evaluating changes to spatiotemporal expression of gbx2 and related homeobox dlx
genes in CNCCs and their derivatives. Findings from these experiments will lead to improved clinical strategies
addressing disorders with disruptions to growth and form of the jaws as well as shed light on the cont...

## Key facts

- **NIH application ID:** 10125809
- **Project number:** 5F32DE029362-02
- **Recipient organization:** BOSTON CHILDREN'S HOSPITAL
- **Principal Investigator:** Katherine Christine Woronowicz
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $69,362
- **Award type:** 5
- **Project period:** 2020-03-01 → 2023-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10125809

## Citation

> US National Institutes of Health, RePORTER application 10125809, Decoding regulatory nodes controlling growth and proportion of the skull (5F32DE029362-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10125809. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*