Tyrosine phosphorylation regulates the endocytosis and surface expression of GluN3A-containing NMDA receptors.
Tyrosine phosphorylation regulates the endocytosis and surface expression of GluN3A-containing NMDA receptors.
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DOI：
10.1523/jneurosci.2721-12.2013
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发表时间：
2013-02-27
期刊：
影响因子：
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通讯作者：
Pérez-Otaño I
中科院分区：
文献类型：
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作者：
Chowdhury D;Marco S;Brooks IM;Zandueta A;Rao Y;Haucke V;Wesseling JF;Tavalin SJ;Pérez-Otaño I
受体运输的选择性控制提供了重塑兴奋性突触受体组成的机制，从而支持突触传递、可塑性和发育。GluN3A（以前称为NR3A）是NMDA受体（NMDAR）亚基家族的非常规成员，与仅包含GluN1和GluN2亚基的NMDAR相比，其赋予NMDAR通道低钙渗透性和降低的镁敏感性。由于这些特殊的性质，GluN3A亚基作为一个分子制动器，限制兴奋性突触的可塑性和成熟，指出GluN3A的去除是神经元回路发育的关键步骤。然而，介导GluN3A内吞去除的分子信号仍不清楚。在这里，我们定义了一个新的内吞基序（YWL），位于胞质内的羧基末端尾的GluN3A和介导其结合网格蛋白适配器AP2。GluN3A内吞基序中的丙氨酸突变抑制网格蛋白依赖性内化，并导致含GluN3A的NMDAR在细胞表面的积累，而模拟酪氨酸残基的磷酸化促进内化并降低细胞表面表达，如重组系统和原代培养的大鼠神经元中的免疫细胞化学和电生理方法所示。我们进一步证明，酪氨酸残基被磷酸化的Src家族激酶，Src激活限制表面GluN3A在神经元中的表达。总之，我们的研究结果确定了一个新的分子信号的GluN3A内化，耦合功能表面表达的GluN3A受体的GluN3A亚基的磷酸化状态，并提供了一个分子框架的调节NMDAR亚基的组成与突触可塑性和神经发育的影响。
Selective control of receptor trafficking provides a mechanism for remodeling the receptor composition of excitatory synapses, and thus supports synaptic transmission, plasticity and development. GluN3A (formerly NR3A) is a non-conventional member of the NMDA receptor (NMDAR) subunit family which endows NMDAR channels with low calcium permeability and reduced magnesium sensitivity compared to NMDARs comprising only GluN1 and GluN2 subunits. Because of these special properties, GluN3A subunits act as a molecular brake to limit the plasticity and maturation of excitatory synapses, pointing towards GluN3A removal as a critical step in the development of neuronal circuitry. However, the molecular signals mediating GluN3A endocytic removal remain unclear. Here we define a novel endocytic motif (YWL) that is located within the cytoplasmic carboxy-terminal tail of GluN3A and mediates its binding to the clathrin adaptor AP2. Alanine mutations within the GluN3A endocytic motif inhibited clathrin-dependent internalization and led to accumulation of GluN3A-containing NMDARs at the cell surface, whereas mimicking phosphorylation of the tyrosine residue promoted internalization and reduced cell-surface expression as shown by immunocytochemical and electrophysiological approaches in recombinant systems and rat neurons in primary culture. We further demonstrate that the tyrosine residue is phosphorylated by Src family kinases, and that Src-activation limits surface GluN3A expression in neurons. Together, our results identify a new molecular signal for GluN3A internalization that couples the functional surface expression of GluN3A-containing receptors to the phosphorylation state of GluN3A subunits, and provide a molecular framework for the regulation of NMDAR subunit composition with implications for synaptic plasticity and neurodevelopment.