Synaptic activity and F-actin coordinately regulate CaMKIIalpha localization to dendritic postsynaptic sites in developing hippocampal slices.
We examined the timing and mechanisms of CaMKIIalpha recruitment to nascent synapses of developing rat hippocampal pyramidal neurons in slice culture. Time-lapse confocal imaging shows that GFP-CaMKIIalpha in transfected neurons accumulates in spines as they are forming, and loss of CaMKIIalpha coincides with spine destabilization. Immunolabeling shows that endogenous CaMKIIalpha is concentrated at postsynaptic sites in spines under ambient slice culture conditions, and this is not disrupted by short-term (3 h) synaptic activity blockade or Latrunculin-induced F-actin depolymerization. However, the combination of activity blockade and F-actin depolymerization significantly reduces synaptic CaMKIIalpha. Conversely, postsynaptic activation induces synaptic recruitment of CaMKIIalpha even in the presence of F-actin depolymerizing drugs. Thus, synaptic-activity-dependent mechanisms and (synaptic activity-independent) F-actin-based mechanisms are individually sufficient and act in parallel to localize CaMKIIalpha to the dendritic spine compartment. Moreover, the timing of CaMKIIalpha recruitment to developing spines suggests a role for CaMKIIalpha in spine assembly and maintenance.
Ahmed
Raheel
R
Department of Biological Sciences, 369 Biology Building, University of Iowa, Iowa City, IA 52242-1324, USA.
Zha
Xiang-ming
XM
Green
Steven H
SH
Dailey
Michael E
ME
D000199:Actins / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D003712:Dendrites / Q000201:enzymology*; D006624:Hippocampus / Q000254:growth & development / Q000502:physiology*; D066298:In Vitro Techniques; D018613:Microscopy, Confocal; D017966:Pyramidal Cells / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013569:Synapses / Q000378:metabolism*; D014162:Transfection
D000199:Actins; D018076:DNA, Complementary; D011993:Recombinant Fusion Proteins; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases