# Mechanisms regulating neuronal axon branching

> **NIH NIH R21** · UNIVERSITY OF WISCONSIN-MADISON · 2020 · $413,573

## Abstract

Precise control over axon branching is critical not only for the development of complex neuronal morphology
and formation of neural circuits, but also for plasticity and regeneration after injury. Axon branching relies on
tightly regulated dynamic cytoskeletal rearrangements, as well as trafficking and transport of cellular cargos
such as membrane vesicles, proteins and organelles. How all these processes are orchestrated to ensure
accurate neuronal branching patterns is still not well understood. The long-term goal of this project is to
determine critical components of the axon transport machinery, and cargos such as guidance receptors,
signaling mediators or cytoskeletal regulators that must coordinate to control axon branching. We established a
model in which we can image dynamics of axon branching, neuronal cargo transport, and microtubule behavior
in the intact zebrafish embryo. We previously found that a kinesin-cargo adaptor, Calsyntenin1 (Clstn1), is
required for axon branching in sensory axons. Clstn1 is required for vesicular transport into developing axons
and to branch points, and for organization of correct microtubule polarity during branching. We hypothesize
that Clstn1 is a component of a coordinated cargo transport and microtubule organizing system that drives
axon branching and controls where branches form. In Aim 1 we will combine CRISPR/Cas G0 phenotypic
screening with rapid imaging using a unique light sheet microscope (Flamingo SPIM), and automated axon
branch analysis to screen a set of candidate genes. Our goal is to identify genes required for axon branching
and cargo transport, and genes that may interact with Clstn1. In Aim 2 we will use time-lapse imaging to
determine effects of candidate gene mutation on motile axon behaviors, cargo transport and microtubule
dynamics. Our goal is to further define molecular mechanism of action of genes important for branching.
Elucidation of the molecular signals regulating sensory axon growth, branching, and protein trafficking is critical
for understanding neurodegenerative disorders, neuropathic pain disorders and the conditions under which
regeneration after axon injury can occur. Our experiments will uncover such mechanisms and thus may help
to identify molecular targets for disease treatment.

## Key facts

- **NIH application ID:** 9954886
- **Project number:** 1R21NS116326-01
- **Recipient organization:** UNIVERSITY OF WISCONSIN-MADISON
- **Principal Investigator:** MARY C HALLORAN
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $413,573
- **Award type:** 1
- **Project period:** 2020-05-01 → 2022-10-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9954886

## Citation

> US National Institutes of Health, RePORTER application 9954886, Mechanisms regulating neuronal axon branching (1R21NS116326-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9954886. Licensed CC0.

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