Multiple Spatial and Kinetic Subpopulations of CaMKII in Spines and Dendrites as Resolved by Single-Molecule Tracking PALM

摘要: Calcium/calmodulin-dependent protein kinase II (CaMKII) is essential for synaptic plasticity underlying memory formation. Some functions of CaMKII are mediated by interactions with proteins, and activity-triggered translocation to synapses has been heavily studied. However, actions away from the postsynaptic density (PSD) remain poorly understood, in part because difficulty discerning where binds live cells. We used photoactivated localization microscopy (PALM) rat hippocampal neurons track single molecules CaMKIIα, mapping its spatial kinetic heterogeneity at high resolution. found that CaMKIIα exhibits least three subpopulations, even within individual spines. Latrunculin application or coexpression CaMKIIβ carrying actin-binding domain strongly modulated diffusion, indicating a major subpopulation regulated actin cytoskeleton. spines was typically more slowly mobile than dendrites, consistent presence higher binding partners obstacles. Importantly, NMDA receptor stimulation triggered activation prompted immobilization presumed not only PSDs but also other points up several hundred nanometers away, suggesting activated does target PSD. Consistent this, endogenous detected via STORM immunocytochemistry were concentrated both PSD quite distant synapse. Together, these results indicate mobility determined association multiple interacting outside PSD, diverse mechanisms which may regulate transmission.