# Isolation and interrogation of the transcriptional profile of pioneer neurons

> **NIH NIH R21** · OREGON HEALTH & SCIENCE UNIVERSITY · 2020 · $432,400

## Abstract

Pioneer neurons are the first to extend axons to a particular region or target, acting as a guide and scaffold for
“follower” axons. In most cases, pioneer neurons are essential in the developing central and peripheral
nervous systems for the initial navigation to appropriate targets, proper follower axon pathfinding, and
promoting follower axon outgrowth. Many studies have noted that pioneer neurons differ from followers in
growth cone morphology and actin dynamics in multiple invertebrate and vertebrate model systems. These
observations strongly argue that pioneer neurons possess a specific genetic program that controls distinct
aspects of their growth cone morphology and behavior. Despite these critical roles and the unique axonal
behavior of pioneer neurons, we still know little about 1) which genes are differentially expressed in pioneer
versus follower neurons; and 2) how these transcriptional differences in turn promote specific pioneer neuron
behaviors, such as enhanced axon outgrowth and protrusive activity in the growth cone. Our study will address
this knowledge gap by identifying pioneer neuron-specific genes and testing their roles in axon growth. Our
preliminary work has found that expression of a neurotrophin receptor Ret is highly elevated in a population of
pioneering peripheral sensory neurons and is required for pioneer axon outgrowth. Furthermore, ret mutant
pioneer axons display altered growth cone morphology, including reduced growth cone size and fewer
filopodia. Thus, ret represents a unique marker of sensory pioneer axons. We will capitalize on this finding to
isolate and interrogate a transcriptional profile of pioneer neurons. In Aim 1, we will use a single cell RNA-sequencing (scRNA-seq) to build a transcriptional profile of ret-positive pioneer neurons and identify genes that
are enriched in the pioneer versus follower neuron subpopulations. In Aim 2, we will screen a list of genes from
our scRNA-seq to identify candidates that play a role in growth cone dynamics and axon extension. In
summary, our work will provide significant advancement by 1) generating a transcriptional profile of pioneer
neurons during axon outgrowth to provide specific markers for studying pioneer neuron biology; and 2) testing
the function of pioneer neuron-specific genes to identify new factors that promote pioneer axon growth in
development.

## Key facts

- **NIH application ID:** 9978397
- **Project number:** 1R21NS112795-01A1
- **Recipient organization:** OREGON HEALTH & SCIENCE UNIVERSITY
- **Principal Investigator:** Alex Nechiporuk
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $432,400
- **Award type:** 1
- **Project period:** 2020-04-01 → 2022-09-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9978397

## Citation

> US National Institutes of Health, RePORTER application 9978397, Isolation and interrogation of the transcriptional profile of pioneer neurons (1R21NS112795-01A1). Retrieved via AI Analytics 2026-06-14 from https://api.ai-analytics.org/grant/nih/9978397. Licensed CC0.

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