|Title||A mechanism for Ca2+/calmodulin-dependent protein kinase II clustering at synaptic and nonsynaptic sites based on self-association.|
|Publication Type||Journal Article|
|Year of Publication||2005|
|Authors||Hudmon A, Lebel E, Roy H, Sik A, Schulman H, M Waxham N, De Koninck P|
|Date Published||2005 Jul 27|
|Keywords||Animals, Calcium, Calcium-Calmodulin-Dependent Protein Kinase Type 2, Calcium-Calmodulin-Dependent Protein Kinases, Cell Membrane, Cells, Cultured, Green Fluorescent Proteins, Hippocampus, Humans, Hydrogen-Ion Concentration, Kidney, Neurons, Phosphorylation, Protein Structure, Tertiary, Rats, Receptors, Glutamate, Synapses, Threonine, Transfection|
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.
|Alternate Journal||J. Neurosci.|