# Mechanisms of Hydra Development and Regeneration

> **NIH NIH R35** · UNIVERSITY OF CALIFORNIA AT DAVIS · 2020 · $375,606

## Abstract

PROJECT SUMMARY/ABSTRACT
In regenerative animals, catastrophic injury in the adult, such as loss of a limb, activates developmental
pathways to grow a new body part. In contrast, catastrophic injuries lead to scarring and loss of function in
humans. The molecular response to injury is conserved in animals regardless of their regenerative abilities, so
a critical open question is to understand why the injury response activates developmental pathways in some
animals, but not others. Our long-term goal is to answer this question, which requires that we decipher the
regulatory connections between injury-induced transcription factors and developmental programs in
regenerative animals. This should be done with cellular resolution because cell types respond differently to
injury and have different roles during regeneration. To achieve our goals, we study the simple cnidarian Hydra
vulgaris because the adult displays both continually active homeostatic development and regenerative
development in response to catastrophic injury; this allows us to dissect both homeostatic and regenerative
development in parallel and make direct comparisons and connections between the two. Thus our laboratory
has two major research directions: 1) Elucidating the signaling pathways and transcriptional networks that drive
homeostatic development and 2) Determining how injury signals trigger these developmental programs during
regeneration. To understand homeostatic development, we use single-cell RNA-seq (scRNA-seq) to capture all
cell states in the adult, including cells in the process of differentiation. We place cells into developmental
trajectories to identify transcription factors expressed at key developmental decision points, which we will test
with functional experiments. In addition, we will repeat scRNA-seq experiments after signaling pathway
perturbations to determine how these pathways control cell type specification in a homeostatic animal. To
understand regenerative development, we have identified injury-induced transcription factors and their putative
regulatory targets. We will test the function of these transcription factors with the aim of making regulatory
connections between the injury response and developmental programs. In addition, we will perform scRNA-seq
and trajectory analysis over a regeneration time course to obtain a global understanding of cell specification
events during regenerative development. Our research program will improve understanding of fundamental
developmental biology processes and this will have a positive impact on human health because: 1) Errors in
cell type specification ultimately lead to disease, thus understanding how normal development occurs informs
our understanding of disease, 2) Engineering stem cell differentiation in a dish for therapeutic medicine relies
on fundamental discoveries about cell specification made in developmental model systems to help guide
experimentation, and 3) Understanding how the link between injur...

## Key facts

- **NIH application ID:** 10001575
- **Project number:** 5R35GM133689-02
- **Recipient organization:** UNIVERSITY OF CALIFORNIA AT DAVIS
- **Principal Investigator:** Celina Juliano
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $375,606
- **Award type:** 5
- **Project period:** 2019-09-01 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10001575

## Citation

> US National Institutes of Health, RePORTER application 10001575, Mechanisms of Hydra Development and Regeneration (5R35GM133689-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10001575. Licensed CC0.

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