A mechanism for Ca2+/calmodulin-dependent protein kinase II clustering at synaptic and nonsynaptic sites based on self-association.
The activity of Ca2+/calmodulin-dependent protein kinase II (CaMKII) plays an integral role in regulating synaptic development and plasticity. We designed a live-cell-imaging approach to monitor an activity-dependent clustering of green fluorescent protein (GFP)-CaMKII holoenzymes, termed self-association, a process that we hypothesize contributes to the translocation of CaMKII to synaptic and nonsynaptic sites in activated neurons. We show that GFP-CaMKII self-association in human embryonic kidney 293 (HEK293) cells requires a catalytic domain and multimeric structure, requires Ca2+ stimulation and a functional Ca2+/CaM-binding domain, is regulated by cellular pH and Thr286 autophosphorylation, and has variable rates of dissociation depending on Ca2+ levels. Furthermore, we show that the same rules that govern CaMKII self-association in HEK293 cells apply for extrasynaptic and postsynaptic translocation of GFP-CaMKII in hippocampal neurons. Our data support a novel mechanism for targeting CaMKII to postsynaptic sites after neuronal activation. As such, CaMKII may form a scaffold that, in combination with other synaptic proteins, recruits and localizes additional proteins to the postsynaptic density. We discuss the potential function of CaMKII self-association as a tag of synaptic activity.
Hudmon
Andy
A
Department of Neurobiology, Stanford University, Stanford, California 94305, USA.
Lebel
Eric
E
Roy
Hugo
H
Sik
Attila
A
Schulman
Howard
H
Waxham
M Neal
MN
De Koninck
Paul
P
D000818:Animals; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D049452:Green Fluorescent Proteins / Q000235:genetics; D006624:Hippocampus / Q000166:cytology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000166:cytology; D009474:Neurons / Q000201:enzymology*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D051381:Rats; D017470:Receptors, Glutamate / Q000502:physiology; D013569:Synapses / Q000201:enzymology*; D013912:Threonine / Q000378:metabolism; D014162:Transfection
D017470:Receptors, Glutamate; D049452:Green Fluorescent Proteins; D013912:Threonine; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium