Department of Chemistry, Institute of Biochemistry.
Department of Chemistry, Institute of Biochemistry, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, and Center for Molecular Medicine, University of Cologne, 50674 Cologne, Germany
J Neurosci. 2014 Jun 4;34(23):7763-8. doi: 10.1523/JNEUROSCI.0531-14.2014.
Gephyrin, the principal scaffolding protein at inhibitory synapses, is essential for postsynaptic clustering of glycine and GABA type A receptors (GABA(A)Rs). Gephyrin cluster formation, which determines the strength of GABAergic transmission, is modulated by interaction with signaling proteins and post-translational modifications. Here, we show that gephyrin was found to be associated with neuronal nitric oxide synthase (nNOS), the major source of the ubiquitous and important signaling molecule NO in brain. Furthermore, we identified that gephyrin is S-nitrosylated in vivo. Overexpression of nNOS decreased the size of postsynaptic gephyrin clusters in primary hippocampal neurons. Conversely, inhibition of nNOS resulted in a loss of S-nitrosylation of gephyrin and the formation of larger gephyrin clusters at synaptic sites, ultimately increasing the number of cell surface expressed synaptic GABA(A)Rs. In conclusion, S-nitrosylation of gephyrin is important for homeostatic assembly and plasticity of GABAergic synapses.
Gephyrin 是抑制性突触的主要支架蛋白，对于甘氨酸和 GABA 型 A 受体 (GABA(A)Rs) 的突触后簇集至关重要。Gephyrin 簇的形成决定了 GABA 能传递的强度，其受到与信号蛋白的相互作用和翻译后修饰的调节。在这里，我们发现 gephyrin 与神经元型一氧化氮合酶 (nNOS) 有关，nNOS 是大脑中普遍存在且重要的信号分子 NO 的主要来源。此外，我们鉴定出 gephyrin 在体内发生 S-亚硝化。nNOS 的过表达减少了原代海马神经元中突触后 gephyrin 簇的大小。相反，nNOS 的抑制导致 gephyrin 的 S-亚硝化丢失和突触部位更大的 gephyrin 簇形成，最终增加了细胞表面表达的突触 GABA(A)Rs 的数量。总之，Gephyrin 的 S-亚硝化对于 GABA 能突触的稳态组装和可塑性很重要。
