The Schizophrenia Susceptibility Gene Dysbindin Regulates Dendritic Spine Dynamics

Dysbindin is a schizophrenia susceptibility gene required for the development of dendritic spines. The expression of dysbindin proteins is decreased in the brains of schizophrenia patients, and neurons in mice carrying a deletion in the dysbindin gene have fewer dendritic spines. Hence, dysbindin might contribute to the spine pathology of schizophrenia, which manifests as a decrease in the number of dendritic spines. The development of dendritic spines is a dynamic process involving formation, retraction, and transformation of dendritic protrusions. It has yet to be determined whether dysbindin regulates the dynamics of dendritic protrusions. Here we address this question using time-lapse imaging in hippocampal neurons. Our results show that dysbindin is required to stabilize dendritic protrusions. In dysbindin-null neurons, dendritic protrusions are hyperactive in formation, retraction, and conversion between different types of protrusions. We further show that CaMKII alpha is required for the stabilization of mushroom/thin spines, and that the hyperactivity of dendritic protrusions in dysbindin-null neurons is attributed in part to decreased CaMKII alpha activity resulting from increased inhibition of CaMKII alpha by Abi1. These findings elucidate the function of dysbindin in the dynamic morphogenesis of dendritic protrusions, and reveal the essential roles of dysbindin and CaMKII alpha in the stabilization of dendritic protrusions during neuronal development.