Park Mikyoung, Salgado Jennifer M, Ostroff Linnaea, Helton Thomas D, Robinson Camenzind G, Harris Kristen M, Ehlers Michael D
Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Neuron. 2006 Dec 7;52(5):817-30. doi: 10.1016/j.neuron.2006.09.040.
Dendritic spines are micron-sized membrane protrusions receiving most excitatory synaptic inputs in the mammalian brain. Spines form and grow during long-term potentiation (LTP) of synaptic strength. However, the source of membrane for spine formation and enlargement is unknown. Here we report that membrane trafficking from recycling endosomes is required for the growth and maintenance of spines. Using live-cell imaging and serial section electron microscopy, we demonstrate that LTP-inducing stimuli promote the mobilization of recycling endosomes and vesicles into spines. Preventing recycling endosomal transport abolishes LTP-induced spine formation. Using a pH-sensitive recycling cargo, we show that exocytosis from recycling endosomes occurs locally in spines, is triggered by activation of synaptic NMDA receptors, and occurs concurrently with spine enlargement. Thus, recycling endosomes provide membrane for activity-dependent spine growth and remodeling, defining a novel membrane trafficking mechanism for spine morphological plasticity and providing a mechanistic link between structural and functional plasticity during LTP.
树突棘是微米大小的膜突起，在哺乳动物大脑中接收大多数兴奋性突触输入。在突触强度的长时程增强（LTP）过程中，树突棘形成并生长。然而，树突棘形成和增大的膜来源尚不清楚。在此，我们报告回收型内体的膜运输是树突棘生长和维持所必需的。利用活细胞成像和连续切片电子显微镜，我们证明LTP诱导刺激促进回收型内体和囊泡向树突棘的转运。阻止回收型内体运输可消除LTP诱导的树突棘形成。利用一种对pH敏感的回收货物，我们表明回收型内体的胞吐作用在树突棘局部发生，由突触NMDA受体的激活触发，并与树突棘增大同时发生。因此，回收型内体为依赖活动的树突棘生长和重塑提供膜，定义了一种用于树突棘形态可塑性的新型膜运输机制，并在LTP期间提供了结构和功能可塑性之间的机制联系。
