# Mechanisms of glial detection of axonal injury and facilitation of axonal regeneration

> **NIH NIH F32** · CHILDREN'S HOSP OF PHILADELPHIA · 2024 · $74,284

## Abstract

PROJECT SUMMARY
 300,000 Americans suffer paralysis from spinal cord axon injury. Glia permit axon regeneration by
clearing debris, partly through autophagy. Inappropriate release of glial debris can inhibit axon regeneration. To
treat axon injuries, it is essential to understand mechanisms of glial recovery after axon injury, permitting glia to
facilitate axon regeneration. Larval fly sensory neurons are a genetically-tractable model for axon regeneration
in the mammalian peripheral nervous system, with regrowth dependent on wrapping glia. In my postdoctoral
experiments, I have discovered that fly sensory glia release large exopher-like vesicles (ELVs) (~3 µm) at the
injury site, a phenomenon previously undescribed in glia. Glia also display membrane damage and subsequent
repair at the injury site, and loss of wound healing pathway components results in diminished axon regeneration.
These data suggest that glia may adapt to the stress of axon injury through ELV release and membrane repair.
Exophers, large (~3 µm) vesicles so far documented in C. elegans neurons and mouse cardiomyocytes,
sequester oxidatively-stressed mitochondria for release. In mice, the autophagic pathway is required to produce
exophers. My preliminary experiments in fly larvae showed loss of an essential autophagy regulator results in
smaller glial ELVs and reduced axon regeneration. Together, these data suggest that the wound healing and
autophagic pathways are important for glial ELV production and axon regeneration. As previous work in exophers
revealed modes of stress recovery, understanding the origins of fly glial ELVs could uncover novel mechanisms
of glial recovery from the stress of axotomy, likely necessary for glia to facilitate axon regeneration. This
proposal aims to define the origins of this novel glial ELV response and its effects on axon regeneration.
 Aim1 of this proposal will identify the cell responsible for autophagy-mediated glial ELV release and axon
regeneration by utilizing glial- and neuronal-specific RNAi knock-downs. Furthermore, Aim1 will use electron
microscopy and fluorescent reporters to determine if ELVs isolate stressed mitochondria, akin to exophers, in an
autophagy-dependent manner. Aim 2 of this proposal will identify the cell-responsible for wound-healing
mediated axon regeneration, interactions between wound-healing and autophagic pathways, and effects of the
wound-healing pathway and extrinsic signals on glial ELV release. This will be achieved via glial- and neuronal-
specific RNAi knock-down constructs for components of the wound healing pathway, antibody staining for wound
healing components, and a genetic system to simulate axotomy without physical injury. This proposal will uncover
novel mechanisms of glial recovery and glial facilitation of axon regeneration. These studies may help inform
and improve methods to drive human axon regeneration in the CNS and PNS, aligning with the mission of
NINDS. With the expertise of the Song lab...

## Key facts

- **NIH application ID:** 10861416
- **Project number:** 1F32NS136191-01
- **Recipient organization:** CHILDREN'S HOSP OF PHILADELPHIA
- **Principal Investigator:** Alina Rashid
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $74,284
- **Award type:** 1
- **Project period:** 2024-07-01 → 2026-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10861416

## Citation

> US National Institutes of Health, RePORTER application 10861416, Mechanisms of glial detection of axonal injury and facilitation of axonal regeneration (1F32NS136191-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10861416. Licensed CC0.

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