# Identification of the factors underlying tooth field size and competency

> **NIH NIH K99** · UNIVERSITY OF CALIFORNIA BERKELEY · 2022 · $152,712

## Abstract

Project Summary/Abstract
The overall dental morphology of an adult vertebrate is set in motion by the initiation of tooth fields at specific
regions in the body plan during early development. Thereafter, primary teeth form sequentially, expanding each
tooth field as new teeth are added at the tooth field margin. Basic research into the genes and signaling pathways
underlying these processes will reveal which cell types and genetic signatures are associated with tooth field
initiation and expansion, thus informing future attempts to create and successfully implant live teeth. By
determining which cell types are capable of undergoing transformation to a dental fate, new avenues for the
creation of lab-made tooth organs will be revealed. Additionally, identifying the genetic signatures associated
with tooth field expansion and arrest will provide information about the greater context under which dental arcade
expansion is facilitated. The present study will use a newly developed set of stable transgenic stickleback fish
and zebrafish to identify the cell types, transcript profiles, and signaling events that underlie the processes of
tooth field initiation, expansion, and arrest. These model fishes present a unique opportunity to understand tooth
field morphogenesis, because tooth field position and size can be manipulated using genetic tools. In response
to Eda overexpression, both species form ectopic tooth fields in highly consistent locations in or on the head,
while also expanding endogenous tooth fields. By contrast, Dkk2 overexpression in stickleback reduces tooth
field size by inhibiting tooth field expansion. Aim 1 seeks to understand the gene expression dynamics of the
switch to a tooth organ fate by assessing the fine spatial expression patterns of genes encoding Tumor Necrosis
Factor Receptors (TNFRs), candidate receptors that may confer the response to Eda, and performing single-cell
RNA sequencing on tooth-competent regions microdissected from Eda overexpressing and WT sticklebacks.
Aim 2 of this project will longitudinally observe the process of ectopic tooth formation by repeatedly imaging fish
as they grow ectopic facial teeth, utilizing lineage tracing techniques, reporter gene expression, and vital dye
labeling to understand which cells contribute to ectopic teeth. Aim 3 will elucidate which developmental pathways
are associated with tooth field size and tooth row number by comparing the gene expression profiles of the
dissected tooth field margins derived from expanded (Eda overexpression), arrested (Dkk2 overexpression), and
normal stickleback tooth fields. Overall, these experiments will yield information on how teeth can be specified
in development (Aims 1 and 2), and which gene expression responses are concomitant with favorable or
unfavorable conditions for tooth field expansion (Aim 3). The first portion of this work will occur at UC-Berkeley
(K99 phase), facilitated by Dr. Square’s advisory committee, institution, and curre...

## Key facts

- **NIH application ID:** 10456199
- **Project number:** 5K99DE031017-02
- **Recipient organization:** UNIVERSITY OF CALIFORNIA BERKELEY
- **Principal Investigator:** Tyler Square
- **Activity code:** K99 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $152,712
- **Award type:** 5
- **Project period:** 2021-08-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10456199

## Citation

> US National Institutes of Health, RePORTER application 10456199, Identification of the factors underlying tooth field size and competency (5K99DE031017-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10456199. Licensed CC0.

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