Acid-sensing ion channels (ASICs), the main H⁺ receptors in the central nervous system, sense extracellular pH fluctuations and mediate cation influx. ASIC1a, the major subunit responsible for acid-activated current, is widely expressed in brain neurons, where it plays pivotal roles in diverse functions including synaptic transmission and plasticity. However, the underlying molecular mechanisms for these functions remain mysterious. Using extracellular epitope tagging and a novel antibody recognizing the hASIC1a ectodomain, we examined the membrane targeting and dynamic trafficking of hASIC1a in cultured cortical neurons. Surface hASIC1a was distributed throughout somata and dendrites, clustered in spine heads, and co-localized with postsynaptic markers. By extracellular pHluorin tagging and fluorescence recovery after photobleaching, we detected movement of hASIC1a in synaptic spine heads. Single-particle tracking along with use of the anti-hASIC1a ectodomain antibody revealed long-distance migration and local movement of surface hASIC1a puncta on dendrites. Importantly, enhancing synaptic activity with brain-derived neurotrophic factor accelerated the trafficking and lateral mobility of hASIC1a. With this newly-developed toolbox, our data demonstrate the synaptic location and high dynamics of functionally-relevant hASIC1a on the surface of excitatory synapses, supporting its involvement in synaptic functions.

酸敏感离子通道 (ASIC) 是中枢神经系统中的主要 H ^{+受体，可感知细胞外 pH 波动并介导阳离子流入。}ASIC1a 是负责酸激活电流的主要亚基，在大脑神经元中广泛表达，在突触传递和可塑性等多种功能中发挥着关键作用。然而，这些功能的潜在分子机制仍然神秘。使用细胞外表位标记和识别 hASIC1a 胞外域的新型抗体，我们检查了培养的皮层神经元中 hASIC1a 的膜靶向和动态运输。表面hASIC1a分布在整个体细胞和树突中，聚集在脊柱头部，并与突触后标记共定位。通过细胞外 pHluorin 标记和光漂白后的荧光恢复，我们检测到了突触棘头中 hASIC1a 的运动。单粒子追踪以及抗 hASIC1a 胞外域抗体的使用揭示了树突上表面 hASIC1a 斑点的长距离迁移和局部运动。重要的是，用脑源性神经营养因子增强突触活动加速了 hASIC1a 的运输和横向移动。通过这个新开发的工具箱，我们的数据展示了兴奋性突触表面上功能相关的 hASIC1a 的突触位置和高动态性，支持其参与突触功能。