Activity-dependent regulation of Cdc42 by Ephexin5 drives synapse growth and stabilization

Synaptic RhoGEFs play vital roles in regulating the activity-dependent neuronal plasticity critical for learning. Ephexin5, a RhoGEF implicated in the etiology of Alzheimer’s disease and Angelman Syndrome, was originally reported in neurons as a RhoA-specific GEF that negatively regulates spine synapse density. Here, we show that Ephexin5 activates both RhoA and Cdc42 in brain. Furthermore, using live imaging of GTPase biosensors, we demonstrate that Ephexin5 regulates activity-dependent Cdc42, but not RhoA, signaling at single synapses. The selectivity of Ephexin5 for Cdc42 activation is regulated by tyrosine phosphorylation, which is regulated by euronal activity. Finally, in contrast to Ephexin5’s role in negatively regulating synapse density, we show that downstream of neuronal activity Ephexin5 positively regulates synaptic growth and stabilization. Our results support a model in which plasticity-inducing neuronal activity regulates Ephexin5 tyrosine phosphorylation, driving Ephexi..., , , # Data from: Activity-dependent regulation of Cdc42 by Ephexin5 drives synapse growth and stabilization

[Access Dataset on Dryad](https://doi.org/10.5061/dryad.dr7sqvb8b)

# Overview

This dataset contains 4 types of data: two-photon imaging (2-photon) fluorescence data, Forster Resonance Energy Transfer-Fluorescence Lifetime Imaging Microscopy (FRET-FLIM) data, Western blot data, and immunohistochemistry (IHC) fluorescence data.

2-photon fluorescence data was collected using a custom 2-photon microscope. Green fluorescence was acquired in channel 1 and red was acquired in channel 2. Analysis was performed using custom MATLAB software.

FRET-FLIM data was collected using a custom-built 2-photon microscope with time correlated single photon counting. Lifetime data is stored in channel 1 and the fluorescence intensity from a red cell fill is stored in channel 2. Data was analyzed using custom MATLAB software.

IHC fluorescence data was collected using a Zeiss Apotome 3 structured illumi...,