Rapid and persistent modulation of actin dynamics regulates postsynaptic reorganization underlying bidirectional plasticity

Yasunori Hayashi

Abstract

The synapse is a highly organized cellular specialization, that reorganizes structure and composition according to input strength both positively and negatively. But the mechanisms orchestrating these changes remain elusive. Actin serves as both cytoskeleton and scaffold for various postsynaptic proteins and exists in a dynamic equilibrium between F-actin and G-actin, which is bidirectionally modulated by various cellular signals. This makes actin a plausible locus for bidirectional reorganization of structure and molecules. A newly innovated FRET-based live imaging technique that monitors F-actin/G-actin equilibrium revealed that a tetanic stimulation causes a rapid and persistent shift of actin equilibrium towards F-actin. This enlarges dendritic spines and increases the postsynaptic binding capacity. In contrast, prolonged low frequency stimulation shifts the equilibrium towards G-actin, resulting in a loss of postsynaptic actin and spine structure. This bidirectional regulation of actin is actively involved in postsynaptic assembly-disassembly and serves as a substrate for bidirectional synaptic plasticity.

Return to the Workshop Main Page