Leibniz Institute for Neurobiology, Magdeburg, Germany.
Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile.
Cell Calcium. 2022 Sep;106:102623. doi: 10.1016/j.ceca.2022.102623. Epub 2022 Jul 6.
Upon postsynaptic glutamate receptor activation, the cytosolic Ca concentration rises and initiates signaling and plasticity in spines. The plasma membrane Ca ATPase (PMCA) is a major player to limit the duration of cytosolic Ca signals. It forms complexes with the glycoprotein neuroplastin (Np) isoforms Np55 and Np65 and functionally interplays with N-methyl-D-aspartate (NMDA)-type ionotropic glutamate receptors (iGluNRs). Moreover, binding of the Np65-specific extracellular domain to Ca-permeable GluA1-containing α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type ionotropic glutamate receptors (iGluA1Rs) was found to be required for long-term potentiation (LTP). However, the link between PMCA and iGluRs function to regulate cytosolic Ca signals remained unclear. Here, we report that Np65 coordinates PMCA and iGluRs' functions to modulate the duration and amplitude of cytosolic Ca transients in dendrites and spines of hippocampal neurons. Using live-cell Ca imaging, acute pharmacological treatments, and GCaMP5G-expressing hippocampal neurons, we discovered that endogenous or Np65-promoted PMCA activity contributes to the restoration of basal Ca levels and that this effect is dependent on iGluR activation. Super-resolution STED and confocal microscopy revealed that electrical stimulation increases the abundance of synaptic neuroplastin-PMCA complexes depending on iGluR activation and that low-rate overexpression of Np65 doubled PMCA levels and decreased cell surface levels of GluN2A and GluA1 in dendrites and Shank2-positive glutamatergic synapses. In neuroplastin-deficient hippocampi, we observed reduced PMCA and unchanged GluN2B levels, while GluN2A and GluA1 levels were imbalanced. Our electrophysiological data from hippocampal slices argues for an essential interplay of PMCA with GluN2A- but not with GluN2B-containing receptors upon induction of synaptic plasticity. Accordingly, we conclude that Np65 may interconnect PMCA with core players of glutamatergic neurotransmission to fine-tune the Ca signal regulation in basal synaptic function and plasticity.
在突触后谷氨酸受体激活后，细胞溶质 Ca 浓度上升，启动信号转导和棘突可塑性。质膜 Ca-ATP 酶（PMCA）是限制细胞溶质 Ca 信号持续时间的主要因素。它与糖蛋白神经可塑性蛋白（Np）同种型 Np55 和 Np65 形成复合物，并与 N-甲基-D-天冬氨酸（NMDA）型离子型谷氨酸受体（iGluNRs）进行功能相互作用。此外，发现 Np65 特异性细胞外结构域与 Ca 通透性含有 GluA1 的 α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）型离子型谷氨酸受体（iGluA1Rs）结合对于长时程增强（LTP）是必需的。然而，PMCA 和 iGluRs 功能之间的联系以调节细胞溶质 Ca 信号仍然不清楚。在这里，我们报告 Np65 协调 PMCA 和 iGluRs 的功能，以调节海马神经元树突和棘突中细胞溶质 Ca 瞬变的持续时间和幅度。使用活细胞 Ca 成像、急性药理学处理和表达 GCaMP5G 的海马神经元，我们发现内源性或 Np65 促进的 PMCA 活性有助于恢复基础 Ca 水平，并且这种作用依赖于 iGluR 激活。超分辨率 STED 和共聚焦显微镜显示，电刺激增加突触神经可塑性-PMCA 复合物的丰度取决于 iGluR 激活，并且低速率过表达 Np65 使 PMCA 水平增加一倍，并降低树突和 Shank2 阳性谷氨酸能突触中 GluN2A 和 GluA1 的细胞表面水平。在神经可塑性蛋白缺陷型海马中，我们观察到 PMCA 减少而 GluN2B 水平不变，而 GluN2A 和 GluA1 水平失衡。我们从海马切片的电生理数据表明，在诱导突触可塑性时，PMCA 与包含 GluN2A 的受体而非包含 GluN2B 的受体之间存在重要的相互作用。因此，我们得出结论，Np65 可能将 PMCA 与谷氨酸能神经传递的核心分子连接起来，以微调基础突触功能和可塑性中的 Ca 信号调节。
