A Conserved Tyrosine Residue in Slitrk3 Carboxyl-Terminus Is Critical for GABAergic Synapse Development
A Conserved Tyrosine Residue in Slitrk3 Carboxyl-Terminus Is Critical for GABAergic Synapse Development
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DOI：
10.3389/fnmol.2019.00213
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发表时间：
2019-09-10
影响因子：
4.8
通讯作者：
Lu, Wei
中科院分区：
文献类型：
--
作者：
Li, Jun;Han, Wenyan;Lu, Wei
单通道跨膜蛋白Slitrk3(Sit and Trk-like家族成员3，ST3)是一种突触细胞黏附分子，在抑制性突触中高度表达。最近的研究表明，ST3通过其胞外区，通过与突触前细胞黏附分子、受体蛋白酪氨酸磷酸酶三角洲(PTP Delta)的跨突触相互作用和与突触后细胞黏附分子神经连接蛋白2(NL2)的顺式相互作用，选择性地调节抑制性突触的发育。然而，人们对ST3胞内羧基(C)末端的生理功能知之甚少。在这里，我们报告了在异源细胞中，ST3的C末端不是ST3同源二聚化和运输到细胞表面所必需的。相反，在海马神经元中，ST3C末端，更具体地说，保守的酪氨酸Y969(在小鼠中)，对GABA能突触的发育至关重要。事实上，ST3 Y969A突变体的过表达显著降低了海马神经元中Gh点密度和GABA能传递。此外，单细胞ST3基因缺失严重损害了GABA能传递。重要的是，野生型(WT)ST3，而不是ST3 Y969A突变体，可以完全修复内源性ST3缺失神经元的GABA能传递缺陷，证实了Y969在抑制性突触调节中的关键作用。综上所述，我们的数据确定了ST3 C末端的一个关键残基，它对GABA能突触的发育和功能是重要的。
Single-passing transmembrane protein, Slitrk3 (Slit and Trk-like family member 3, ST3), is a synaptic cell adhesion molecule highly expressed at inhibitory synapses. Recent studies have shown that ST3, through its extracellular domain, selectively regulates inhibitory synapse development via the trans-synaptic interaction with presynaptic cell adhesion molecule, receptor protein tyrosine phosphatase delta (PTP delta) and the cisinteraction with postsynaptic cell adhesion molecule, Neuroligin 2 (NL2). However, little is known about the physiological function of ST3 intracellular, carboxyl (C)-terminal region. Here we report that in heterologous cells, ST3 C-terminus is not required for ST3 homo-dimerization and trafficking to the cell surface. In contrast, in hippocampal neurons, ST3 C-terminus, more specifically, the conserved tyrosine Y969 (in mice), is critical for GABAergic synapse development. Indeed, overexpression of ST3 Y969A mutant markedly reduced the gephyrin puncta density and GABAergic transmission in hippocampal neurons. In addition, single-cell genetic deletion of ST3 strongly impaired GABAergic transmission. Importantly, wild-type (WT) ST3, but not the ST3 Y969A mutant, could fully rescue GABAergic transmission deficits in neurons lacking endogenous ST3, confirming a critical role of Y969 in the regulation of inhibitory synapses. Taken together, our data identify a single critical residue in ST3 C-terminus that is important for GABAergic synapse development and function.