Functional Phenotypic Rescue of Caenorhabditis elegans Neuroligin-Deficient Mutants by the Human and Rat NLGN1 Genes
Functional Phenotypic Rescue of Caenorhabditis elegans Neuroligin-Deficient Mutants by the Human and Rat NLGN1 Genes
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DOI：
10.1371/journal.pone.0039277
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发表时间：
2012-06-18
期刊：
影响因子：
3.7
通讯作者：
Ruiz-Rubio, Manuel
中科院分区：
文献类型：
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作者：
Calahorro, Fernando;Ruiz-Rubio, Manuel
Neuroligins 是与突触神经毒素相互作用的细胞粘附蛋白。这种相互作用可能有助于突触的分化、可塑性和特异性。在人类中，神经肽编码基因的单一突变会导致自闭症谱系障碍和/或精神发育迟滞。缺乏 nlg-1（人类神经连接素基因的直系同源物）的秀丽隐杆线虫突变体在不同的行为中存在缺陷。在这里，我们表明，在线虫 nlg-1 突变体中人类 NLGN1 或大鼠 Nlgn1 cDNA 的表达可以挽救果糖渗透强度回避和温和的触摸反应表型。 NLGN3 和 NLGN4 基因中与自闭症谱系障碍有关的两个特定点突变在该实验系统中得到了进一步表征。使用人类 NLGN1 (R453C) 和蠕虫 NLG-1 (R437C) 蛋白对 NLGN3 中描述的 R451C 等位基因进行分析，发现两者都无法挽救渗透回避行为和温和触摸反应表型。 NLGN4 中描述的 D396X 等位基因产生截短的蛋白质，用人类 NLGN1 (D432X) 进行了研究，但他们没有挽救任何分析的行为表型。此外，RNAi喂养实验测量了神经元中表达SID-1的野生型菌株和蠕虫的轻柔触摸反应（这增加了对dsRNA的反应），这两种菌株都用表达nlg-1的dsRNA的细菌喂养，为神经胶质素在肌肉细胞和神经元中的突触后体内功能提供了证据，相当于在哺乳动物中提出的功能。这一发现得到进一步证实，产生了在泛神经元 (nrx-1) 或泛肌肉 (myo-3) 特异性启动子下表达 NLG-1 的转基因 nlg-1 缺陷突变体。所有这些结果表明，线虫可以用作体内模型，用于研究与人类广泛性发育障碍相关的蛋白质直系同源物的特定突触机制。
Neuroligins are cell adhesion proteins that interact with neurexins at the synapse. This interaction may contribute to differentiation, plasticity and specificity of synapses. In humans, single mutations in neuroligin encoding genes lead to autism spectrum disorder and/or mental retardation. Caenorhabditis elegans mutants deficient in nlg-1, an orthologue of human neuroligin genes, have defects in different behaviors. Here we show that the expression of human NLGN1 or rat Nlgn1 cDNAs in C. elegans nlg-1 mutants rescues the fructose osmotic strength avoidance and gentle touch response phenotypes. Two specific point mutations in NLGN3 and NLGN4 genes, involved in autistic spectrum disorder, were further characterized in this experimental system. The R451C allele described in NLGN3, was analyzed with both human NLGN1 (R453C) and worm NLG-1 (R437C) proteins, and both were not functional in rescuing the osmotic avoidance behavior and the gentle touch response phenotype. The D396X allele described in NLGN4, which produces a truncated protein, was studied with human NLGN1 (D432X) and they did not rescue any of the behavioral phenotypes analyzed. In addition, RNAi feeding experiments measuring gentle touch response in wild type strain and worms expressing SID-1 in neurons (which increases the response to dsRNA), both fed with bacteria expressing dsRNA for nlg-1, provided evidence for a postsynaptic in vivo function of neuroligins both in muscle cells and neurons, equivalent to that proposed in mammals. This finding was further confirmed generating transgenic nlg-1 deficient mutants expressing NLG-1 under pan-neuronal (nrx-1) or pan-muscular (myo-3) specific promoters. All these results suggest that the nematode could be used as an in vivo model for studying particular synaptic mechanisms with proteins orthologues of humans involved in pervasive developmental disorders.