title: Local, persistent activation of Rho GTPases during plasticity of single dendritic spines.
abstract: The Rho family of GTPases have important roles in the morphogenesis of the dendritic spines of neurons in the brain and synaptic plasticity by modulating the organization of the actin cytoskeleton. Here we used two-photon fluorescence lifetime imaging microscopy to monitor the activity of two Rho GTPases-RhoA and Cdc42-in single dendritic spines undergoing structural plasticity associated with long-term potentiation in CA1 pyramidal neurons in cultured slices of rat hippocampus. When long-term volume increase was induced in a single spine using two-photon glutamate uncaging, RhoA and Cdc42 were rapidly activated in the stimulated spine. These activities decayed over about five minutes, and were then followed by a phase of persistent activation lasting more than half an hour. Although active RhoA and Cdc42 were similarly mobile, their activity patterns were different. RhoA activation diffused out of the stimulated spine and spread over about 5 µm along the dendrite. In contrast, Cdc42 activation was restricted to the stimulated spine, and exhibited a steep gradient at the spine necks. Inhibition of the Rho-Rock pathway preferentially inhibited the initial spine growth, whereas the inhibition of the Cdc42-Pak pathway blocked the maintenance of sustained structural plasticity. RhoA and Cdc42 activation depended on Ca(2+)/calmodulin-dependent kinase (CaMKII). Thus, RhoA and Cdc42 relay transient CaMKII activation to synapse-specific, long-term signalling required for spine structural plasticity.
authors.affiliation: Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Hideji
authors.initials: H
authors.lastname: Murakoshi
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Ryohei
authors.initials: R
authors.lastname: Yasuda
mesh_terms: D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D049229:Dendritic Spines / Q000201:enzymology* / Q000502:physiology*; D004789:Enzyme Activation; D020690:GTPase-Activating Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D007858:Learning / Q000502:physiology; D017774:Long-Term Potentiation / Q000502:physiology; D008856:Microscopy, Fluorescence; D009473:Neuronal Plasticity / Q000502:physiology*; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D017966:Pyramidal Cells / Q000502:physiology; D051381:Rats; D015398:Signal Transduction; D013997:Time Factors; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C514543:ARHGAP31 protein, human; D020690:GTPase-Activating Proteins; D010750:Phosphoproteins; C066737:RHOA protein, human; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein