Rac1 is a downstream effector of PKC\u03b1 in structural synaptic plasticity

Xun Tu,Ryohei Yasuda,Lesley A Colgan

doi:10.1038/s41598-020-58610-6

Abstract

Structural and functional plasticity of dendritic spines is the basis of animal learning. The rapid remodeling of actin cytoskeleton is associated with spine enlargement and shrinkage, which are essential for structural plasticity. The calcium-dependent protein kinase C isoform, PKCα, has been suggested to be critical for this actin-dependent plasticity. However, mechanisms linking PKCα and structural plasticity of spines are unknown. Here, we examine the spatiotemporal activation of actin regulators, including small GTPases Rac1, Cdc42 and Ras, in the presence or absence of PKCα during single-spine structural plasticity. Removal of PKCα expression in the postsynapse attenuated Rac1 activation during structural plasticity without affecting Ras or Cdc42 activity. Moreover, disruption of a PDZ binding domain within PKCα led to impaired Rac1 activation and deficits in structural spine remodeling. These results demonstrate that PKCα positively regulates the activation of Rac1 during structural plasticity.

Highlights

Structural and functional plasticity of dendritic spines is the basis of animal learning
Application of phorbol esters, which activate Protein kinase C (PKC), can induce structural changes including growth cone retraction or collapse and the formation of lamellae in dendrites[22,23]. These data suggest that PKC can regulate actin through modulating small GTPase function, whether these pathways are involved during structural plasticity of spines and which small GTPases might be regulated are unknown[24]
In order to study signaling in single spines during structural plasticity, we combined two-photon release of caged glutamate[25], fluorescence resonance energy transfer (FRET)-based sensors, and two-photon fluorescence lifetime imaging microscopy (2pFLIM)[26] to monitor the dynamics of intracellular signaling events with high spatiotemporal resolution

Summary

Introduction

Structural and functional plasticity of dendritic spines is the basis of animal learning. The expression of structural plasticity, through spine enlargement and insertion of additional glutamate receptors, requires actin remodeling through the regulated activity of small GTPases including Rac[1], Cdc[42] and Ras[15,16,17,18,19]. Application of phorbol esters, which activate PKC, can induce structural changes including growth cone retraction or collapse and the formation of lamellae in dendrites[22,23] These data suggest that PKC can regulate actin through modulating small GTPase function, whether these pathways are involved during structural plasticity of spines and which small GTPases might be regulated are unknown[24]

Methods

Results

Conclusion