# Investigating the Molecular Mechanisms that Drive Electrical Synapse Development

> **NIH NIH F31** · UNIVERSITY OF OREGON · 2024 · $48,068

## Abstract

PROJECT SUMMARY
Electrical synapses are complex cellular and biochemical structures with important roles in health and disease.
They are composed of neuronal gap junctions that link the cytoplasm of synapsing neurons through channels
composed of transmembrane Connexin proteins (Cx). However, there are striking gaps in knowledge
surrounding the identification of non-Connexin electrical synapse proteins and the characterization of
molecular mechanisms driving electrical synapse formation. Electron micrograph images first revealed the now
well-characterized molecular assemblies of the chemical synapse, showing large electron dense regions
beneath pre- and postsynaptic membranes now known as the Active Zone (AZ) and the Postsynaptic Density
(PSD). Similar cytoplasmic electron dense regions have been observed at neuronal gap junctions, suggesting
the presence of additional machinery regulating electrical synapses. The Miller lab recently identified ZO1b as
being necessary and sufficient for Cx localization and electrical synapse function in the zebrafish Mauthner
neural circuit. ZO1b is a multidomain molecular scaffold known for organizing cytosolic and transmembrane
proteins at epithelial tight junctions. Interestingly, ZO proteins at tight junctions display the fascinating
biochemical property known as liquid-liquid phase separation (LLPS) allowing them to create a non-
membrane-bound compartments within the cell and concentrate binding partners to build fluid molecular
assemblies. Indeed, ZO1b’s chemical synapse analog PSD95, as well as other synaptic scaffolds of the AZ
and PSD, have also been suggested to organize chemical synapse architecture through LLPS. However,
functional characterization for LLPS in vivo has been difficult due to the absence of an assessable model
system. This proposal uses a combination of protein dynamics, binding assays, and structure/function mutants
in cell culture to first determine the functional domains involved in Cx-scaffolding and LLPS of ZO1b and then
translates those findings in vivo to the optically transparent, genetically tractable Mauthner cell circuit. Together
the results will provide a foundational model for the molecules required for electrical synapse development and
the biochemical interactions that drive it, as well as accelerated training for the applicant in neurodevelopment,
protein biochemistry, and zebrafish genetics.

## Key facts

- **NIH application ID:** 10906651
- **Project number:** 5F31NS132555-02
- **Recipient organization:** UNIVERSITY OF OREGON
- **Principal Investigator:** Lila E Kaye
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $48,068
- **Award type:** 5
- **Project period:** 2023-09-01 → 2026-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10906651

## Citation

> US National Institutes of Health, RePORTER application 10906651, Investigating the Molecular Mechanisms that Drive Electrical Synapse Development (5F31NS132555-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10906651. Licensed CC0.

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