δ-Catenin Regulates Spine and Synapse Morphogenesis and Function in Hippocampal Neurons during Development

The maintenance of spine and synapse number during development is critical for neuronal circuit formation and function. Here we show that delta-catenin, a component of the cadherin-catenin cell adhesion complex, regulates spine and synapse morphogenesis during development. Genetic ablation or acute knockdown of delta-catenin leads to increases in spine and synapse density, accompanied by a decrease in tetrodotoxin induced spine plasticity. Our results indicate that delta-catenin may mediate conversion of activity-dependent signals to morphological spine plasticity. The functional role of delta-catenin in regulating spine density does not require binding to cadherins, but does require interactions with PDZ domain-containing proteins. We propose that the perturbations in spine and synaptic structure and function observed after depletion of delta-catenin during development may contribute to functional alterations in neural circuitry, the cognitive deficits observed in mutant mice, and the mental retardation pathology of Cri-du-chat syndrome.