Non-ionotropic NMDA receptor signaling gates bidirectional structural plasticity of dendritic spines
Ivar S. Stein, Deborah K. Park, Nicole Claiborne, Karen Zito
Abstract
Experience-dependent refinement of neuronal connections is critically important for brain development and learning. Here, we show that ion-flow-independent NMDA receptor (NMDAR) signaling is required for the long-term dendritic spine growth that is a vital component of brain circuit plasticity. We find that inhibition of p38 mitogen-activated protein kinase (p38 MAPK), which is downstream of non-ionotropic NMDAR signaling in long-term depression (LTD) and spine shrinkage, blocks long-term potentiation (LTP)-induced spine growth but not LTP. We hypothesize that non-ionotropic NMDAR signaling drives the cytoskeletal changes that support bidirectional spine structural plasticity. Indeed, we find that key signaling components downstream of non-ionotropic NMDAR function in LTD-induced spine shrinkage are also necessary for LTPinduced spine growth. Furthermore, NMDAR conformational signaling with coincident Ca 2+ influx is sufficient to drive CaMKII-dependent long-term spine growth, even when Ca 2+ is artificially driven through voltage-gated Ca 2+ channels. Our results support a model in which nonionotropic NMDAR signaling gates the bidirectional spine structural changes vital for brain plasticity.