# Developmental regulation of cranial tendon fibroblast diversity and ECM interactions

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA-IRVINE · 2022 · $377,714

## Abstract

Project Summary/Abstract
Tendons and ligaments are fundamental components of a functional musculoskeletal system. Tendons
attach muscles to bone and interact with these tissues at distinct attachment sites called entheses
(bone) and myotendinous junctions (MTJs, muscle). These interactions cause unique changes in gene
expression and extracellular matrix (ECM) production that allow tendons to bear the forces exerted by
muscle contraction. Transcription factors such as Scleraxis (Scx) specify early tendon progenitor cells
(TPCs) and regulate ECM production. We previously discovered a critical ECM scaffolding protein
called Thrombospondin-4b (Tsp4b) in zebrafish that is regulated by Scx, required for tendon
maintenance and conserved in human tendons. How different types of tendon fibroblasts (tenocytes)
are specified and influence ECM assembly at entheses or MTJs remains unclear. The current proposal
addresses these issues using the advantages of the zebrafish for single cell RNA sequencing, in vivo
imaging and genetic manipulation. The long-term goal of the proposed research is to understand the
spatial dynamics of gene regulation and ECM assembly in tendons/ligaments and their regulation by
mechanical force. Three primary hypotheses guide the research: 1) distinct subtypes of TPCs develop
at entheses and MTJs in response to force, 2) ECM secreted by tenocytes regulates force-dependent
signals that alter these distinct modes of gene expression in tenocytes and 3) retinoic acid is a novel
force-dependent signal controlling tendon development. Aim 1 will perform scRNA-seq in tenocytes and
see how force alters gene expression profiles. Aim 2 will study roles for Tsp4b, ECM, and TGF-beta
signaling in force-dependent gene expression in tendons. Aim 3 will study the roles of RA signaling in
tendons, and its responses to mechanical load. Each aim combines novel single cell approaches,
genetic manipulation, live imaging and quantitative methods for physiological stimulation of muscles to
get at mechanisms of tendon cell specification and ECM assembly in response to force.

## Key facts

- **NIH application ID:** 10446059
- **Project number:** 2R01AR067797-06
- **Recipient organization:** UNIVERSITY OF CALIFORNIA-IRVINE
- **Principal Investigator:** Thomas F Schilling
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $377,714
- **Award type:** 2
- **Project period:** 2016-03-01 → 2026-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10446059

## Citation

> US National Institutes of Health, RePORTER application 10446059, Developmental regulation of cranial tendon fibroblast diversity and ECM interactions (2R01AR067797-06). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10446059. Licensed CC0.

---

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