Stability of dendritic spines and synaptic contacts is controlled by αN-catenin

Morphological plasticity of dendritic spines and synapses is thought to be crucial for their physiological functions. Here we show that alphaN-catenin, a linker between cadherin adhesion receptors and the actin cytoskeleton, is essential for stabilizing dendritic spines in rodent hippocampal neurons in culture. In the absence of alphaN-catenin, spine heads were abnormally motile, actively protruding filopodia from their synaptic contact sites. Conversely, alphaN-catenin overexpression in dendrites reduced spine turnover, causing an increase in spine and synapse density. Tetrodotoxin (TTX), a neural activity blocker, suppressed the synaptic accumulation of alphaN-catenin, whereas bicuculline, a GABA antagonist, promoted it. Furthermore, excess alphaN-catenin rendered spines resistant to the TTX treatment. These results suggest that alphaN-catenin is a key regulator for the stability of synaptic contacts.