# Non-apoptotic functions of caspase-3 in neural development

> **NIH NIH R56** · UNIVERSITY OF CALIFORNIA-IRVINE · 2023 · $473,267

## Abstract

PROJECT SUMMARY
Auditory function relies on highly specialized and precise neuronal connectivity. A significant
challenge for the field of auditory neuroscience is to understand how these neural circuits form during
development. Our previous work suggests an important function for caspase-3, a protease best
known for its role in apoptosis. Cleaved (active) caspase-3 is present in the developing auditory
brainstem prior to the period of programmed cell death. During embryonic development, it is first
seen in auditory nerve axons, then in the synaptic target of these axons in nucleus magnocellularis
(NM), then in the synaptic target of NM, in nucleus laminaris (NL) dendrites. Caspase-3 inhibition
during development results in substantial errors in NM axon targeting and in structural abnormalities
in NL. We propose to investigate the regulation of caspase-3 activation during development. We will
examine the basis for the progression of caspase-3 activation through the auditory pathway and test
the hypothesis that cleaved caspase-3 is necessary in auditory axons for activation of caspase-3 in
their synaptic targets. Caspase-3 activation during apoptosis is activated by cell death signals and
mitochondrial permeabilization. We hypothesize that during auditory development, caspase-3 is
activated through a non-canonical pathway that is protective for cells with cleaved caspase-3 in their
axons. We will test the function of upstream molecules and determine whether they influence
development of the NM-NL pathway. We have begun to investigate the molecules through which
caspase-3 influences auditory development. Our proteomics study revealed hundreds of proteins that
are cleaved by caspase-3 in the developing auditory brainstem. We have identified several substrates
that mediate axon growth. We will use caspase-uncleavable forms of these proteins to test their
caspase-dependent functions in development. Gene ontology analysis revealed that the most
abundant cellular localization category for caspase-3 substrates was exosomes/extracellular vesicles
(EVs). This finding suggests an overarching model in which caspase-3 influences the composition of
EVs, which in turn provide an effective means of local communication between cells during
development. We will examine enriched EV samples using tandem mass spectrometry to determine
which caspase-3 substrates are present in EVs. We will use an EV grafting strategy to investigate
whether EVs can rescue developmental deficits in caspase-3 inhibited host embryos. Together, these
studies will advance our understanding of neural circuit assembly in the developing auditory
brainstem.

## Key facts

- **NIH application ID:** 10862033
- **Project number:** 1R56DC020246-01A1
- **Recipient organization:** UNIVERSITY OF CALIFORNIA-IRVINE
- **Principal Investigator:** Karina S Cramer
- **Activity code:** R56 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $473,267
- **Award type:** 1
- **Project period:** 2023-08-01 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10862033

## Citation

> US National Institutes of Health, RePORTER application 10862033, Non-apoptotic functions of caspase-3 in neural development (1R56DC020246-01A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10862033. Licensed CC0.

---

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