Small GTPases Rac and Rho in the Maintenance of Dendritic Spines and Branches in Hippocampal Pyramidal Neurons

TLDR

The shape of dendritic trees and the density of dendritic spines can undergo significant changes during the life of a neuron. The study investigates the role of the small GTPases Rac and Rho in maintaining dendritic structures. Mature rat hippocampal pyramidal neurons were biolistically transfected with dominant GTPase mutants in slice culture. Dominant‑negative Rac1 expression progressively eliminated dendritic spines, while hyperactivation of RhoA drastically simplified dendritic branching via ROCK, indicating Rac and Rho have distinct, essential roles in dendritic spine and branch maintenance and reorganization.

Abstract

The shape of dendritic trees and the density of dendritic spines can undergo significant changes during the life of a neuron. We report here the function of the small GTPases Rac and Rho in the maintenance of dendritic structures. Maturing pyramidal neurons in rat hippocampal slice culture were biolistically transfected with dominant GTPase mutants. We found that expression of dominant-negative Rac1 results in a progressive elimination of dendritic spines, whereas hyperactivation of RhoA causes a drastic simplification of dendritic branch patterns that is dependent on the activity of a downstream kinase ROCK. Our results suggest that Rac and Rho play distinct functions in regulating dendritic spines and branches and are vital for the maintenance and reorganization of dendritic structures in maturing neurons.