Widagdo Jocelyn, Fang Huaqiang, Jang Se Eun, Anggono Victor
Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Sci Rep. 2016 Aug 4;6:31070. doi: 10.1038/srep31070.
Dynamic trafficking of AMPA receptors (AMPARs) into and out of synapses plays an important role in synaptic plasticity. We previously reported that the protein kinase C and casein kinase II substrate in neurons (PACSIN) forms a complex with AMPARs through its interaction with the protein interacting with C-kinase 1 (PICK1) to regulate NMDA receptor (NMDAR)-induced AMPAR endocytosis and cerebellar long-term depression. However, the molecular mechanism by which PACSIN regulates the dynamics of AMPAR trafficking remains unclear. Using a pH-sensitive green fluorescent protein, pHluorin, tagged to the extracellular domain of the GluA2 subunit of AMPARs, we demonstrate dual roles for PACSIN1 in controlling the internalization and recycling of GluA2 after NMDAR activation. Structure and function analysis reveals a requirement for the PACSIN1 F-BAR and SH3 domains in controlling these NMDAR-dependent processes. Interestingly, the variable region, which binds to PICK1, is not essential for NMDAR-dependent GluA2 internalization and is required only for the correct recycling of AMPARs. These results indicate that PACSIN is a versatile membrane deformation protein that links the endocytic and recycling machineries essential for dynamic AMPAR trafficking in neurons.
AMPA受体（AMPARs）在突触内外的动态运输在突触可塑性中起着重要作用。我们之前报道过，神经元中的蛋白激酶C和酪蛋白激酶II底物（PACSIN）通过与C激酶相互作用蛋白1（PICK1）相互作用，与AMPARs形成复合物，以调节NMDA受体（NMDAR）诱导的AMPAR内吞作用和小脑长时程抑制。然而，PACSIN调节AMPAR运输动力学的分子机制仍不清楚。利用一种pH敏感的绿色荧光蛋白pHluorin，其标记在AMPARs的GluA2亚基的胞外结构域上，我们证明了PACSIN1在NMDAR激活后控制GluA2的内化和再循环中具有双重作用。结构和功能分析揭示了PACSIN1的F-BAR和SH3结构域在控制这些NMDAR依赖性过程中的必要性。有趣的是，与PICK1结合的可变区对于NMDAR依赖性GluA2内化不是必需的，仅对AMPARs的正确再循环是必需的。这些结果表明，PACSIN是一种多功能的膜变形蛋白，它连接了神经元中动态AMPAR运输所必需的内吞和再循环机制。
