Varea Olga, Martin-de-Saavedra Maria Dolores, Kopeikina Katherine J, Schürmann Britta, Fleming Hunter J, Fawcett-Patel Jessica M, Bach Anthony, Jang Seil, Peles Elior, Kim Eunjoon, Penzes Peter
Departments of Physiology and.
Department of Neuroscience, Korea Advanced Institute of Science and Technology, 305-701 Daejeon, South Korea;
Proc Natl Acad Sci U S A. 2015 May 12;112(19):6176-81. doi: 10.1073/pnas.1423205112. Epub 2015 Apr 27.
Central glutamatergic synapses and the molecular pathways that control them are emerging as common substrates in the pathogenesis of mental disorders. Genetic variation in the contactin associated protein-like 2 (CNTNAP2) gene, including copy number variations, exon deletions, truncations, single nucleotide variants, and polymorphisms have been associated with intellectual disability, epilepsy, schizophrenia, language disorders, and autism. CNTNAP2, encoded by Cntnap2, is required for dendritic spine development and its absence causes disease-related phenotypes in mice. However, the mechanisms whereby CNTNAP2 regulates glutamatergic synapses are not known, and cellular phenotypes have not been investigated in Cntnap2 knockout neurons. Here we show that CNTNAP2 is present in dendritic spines, as well as axons and soma. Structured illumination superresolution microscopy reveals closer proximity to excitatory, rather than inhibitory synaptic markers. CNTNAP2 does not promote the formation of synapses and cultured neurons from Cntnap2 knockout mice do not show early defects in axon and dendrite outgrowth, suggesting that CNTNAP2 is not required at this stage. However, mature neurons from knockout mice show reduced spine density and levels of GluA1 subunits of AMPA receptors in spines. Unexpectedly, knockout neurons show large cytoplasmic aggregates of GluA1. Here we characterize, for the first time to our knowledge, synaptic phenotypes in Cntnap2 knockout neurons and reveal a novel role for CNTNAP2 in GluA1 trafficking. Taken together, our findings provide insight into the biological roles of CNTNAP2 and into the pathogenesis of CNTNAP2-associated neuropsychiatric disorders.
中枢谷氨酸能突触及其调控分子通路正逐渐成为精神障碍发病机制中的共同底物。接触蛋白相关蛋白样2（CNTNAP2）基因的遗传变异，包括拷贝数变异、外显子缺失、截短、单核苷酸变异和多态性，已与智力障碍、癫痫、精神分裂症、语言障碍和自闭症相关联。由Cntnap2编码的CNTNAP2是树突棘发育所必需的，其缺失会在小鼠中导致疾病相关表型。然而，CNTNAP2调节谷氨酸能突触的机制尚不清楚，且尚未在Cntnap2基因敲除神经元中研究细胞表型。在此我们表明，CNTNAP2存在于树突棘、轴突和胞体中。结构光照超分辨率显微镜显示其与兴奋性而非抑制性突触标记物的距离更近。CNTNAP2不促进突触形成，且来自Cntnap2基因敲除小鼠的培养神经元在轴突和树突生长方面未显示早期缺陷，这表明在此阶段不需要CNTNAP2。然而，来自基因敲除小鼠的成熟神经元显示树突棘密度降低以及树突棘中AMPA受体GluA1亚基的水平降低。出乎意料的是，基因敲除神经元显示出GluA1的大量胞质聚集体。在此我们首次描述了Cntnap2基因敲除神经元中的突触表型，并揭示了CNTNAP2在GluA1转运中的新作用。综上所述，我们的研究结果为CNTNAP2的生物学作用以及与CNTNAP2相关的神经精神疾病的发病机制提供了见解。
