Mechanisms of Ca²⁺/calmodulin-dependent kinase II activation in single dendritic spines.

ABSTRACT: CaMKIIα plays an essential role in decoding Ca²⁺ signaling in spines by acting as a leaky Ca²⁺ integrator with the time constant of several seconds. However, the mechanism by which CaMKIIα integrates Ca²⁺ signals remains elusive. Here, we imaged CaMKIIα-CaM association in single dendritic spines using a new FRET sensor and two-photon fluorescence lifetime imaging. In response to a glutamate uncaging pulse, CaMKIIα-CaM association increases in ~0.1 s and decays over ~3 s. During repetitive glutamate uncaging, which induces spine structural plasticity, CaMKIIα-CaM association did not show further increase but sustained at a constant level. Since CaMKIIα activity integrates Ca²⁺ signals over ~10 s under this condition, the integration of Ca²⁺ signal by CaMKIIα during spine structural plasticity is largely due to Ca²⁺/CaM-independent, autonomous activity. Based on these results, we propose a simple kinetic model of CaMKIIα activation in dendritic spines.

SUBMITTER: Chang JY 

PROVIDER: S-EPMC6592955 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature