背景:Neuroligin-3是一种参与突触发育和功能的突触后粘附分子。它牵涉到罕见的,单基因形式的自闭症,其脱落对胶质瘤的肿瘤微环境至关重要。虽然Neuroligin家族的其他成员通过与突触后支架蛋白的不同相互作用在定位和功能上表现出突触型特异性,Neuroligin-3突触定位的特异性仍然未知.
方法:我们在敲除动物中验证抗体特异性后,研究了Neuroligin-3在小鼠和人脑样品中跨区域的突触定位。我们提出了一种磷酸特异性Neuroligin抗体,并使用磷酸蛋白质组学,基于细胞的检测,以及子宫内CRISPR/Cas9敲除和基因置换,以鉴定调节Neuroligin-3定位为不同突触类型的机制。
结果:Neuroligin-3表现出区域依赖性突触特异性,在小鼠和人类中,主要定位在皮质区域的兴奋性突触和大脑皮质下区域的抑制性突触。我们确定了皮质Neuroligin-3在募集到抑制性突触的关键结合位点的特异性磷酸化,而皮质下Neuroligin-3仍未磷酸化。体外,该位点的磷模拟突变破坏了Neuroligin-3与抑制性突触后支架蛋白的关联,卟啉。在体内,位于兴奋性突触后的Neuroligin-3的磷模拟突变体,而磷酸化无效突变体定位于抑制性突触后。
结论:这些数据揭示了Neuroligin-3突触特异性的一个意想不到的区域特异性模式,以及调节其募集到兴奋性或抑制性突触的磷酸化依赖性机制。这些发现增加了我们对Neuroligin-3如何参与可能影响兴奋和抑制平衡的条件的理解。
BACKGROUND: Neuroligin-3 is a postsynaptic adhesion molecule involved in synapse development and function. It is implicated in rare, monogenic forms of autism, and its shedding is critical to the tumor microenvironment of gliomas. While other members of the
neuroligin family exhibit synapse-type specificity in localization and function through distinct interactions with postsynaptic scaffold proteins, the specificity of neuroligin-3 synaptic localization remains largely unknown.
METHODS: We investigated the synaptic localization of
neuroligin-3 across regions in mouse and human brain samples after validating antibody specificity in knockout animals. We raised a phospho-specific
neuroligin antibody and used phosphoproteomics, cell-based assays, and in utero CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/Cas9) knockout and gene replacement to identify mechanisms that regulate neuroligin-3 localization to distinct synapse types.
RESULTS: Neuroligin-3 exhibits region-dependent synapse specificity, largely localizing to excitatory synapses in cortical regions and inhibitory synapses in subcortical regions of the brain in both mice and humans. We identified specific phosphorylation of cortical neuroligin-3 at a key binding site for recruitment to inhibitory synapses, while subcortical
neuroligin-3 remained unphosphorylated. In vitro, phosphomimetic mutation of that site disrupted neuroligin-3 association with the inhibitory postsynaptic scaffolding protein gephyrin. In vivo, phosphomimetic mutants of neuroligin-3 localized to excitatory postsynapses, while phospho-null mutants localized to inhibitory postsynapses.
CONCLUSIONS: These data reveal an unexpected region-specific pattern of neuroligin-3 synapse specificity, as well as a phosphorylation-dependent mechanism that regulates its recruitment to either excitatory or inhibitory synapses. These findings add to our understanding of how neuroligin-3 is involved in conditions that may affect the balance of excitation and inhibition.