Loss of Function of C9orf72 Causes Motor Deficits in a Zebrafish Model of Amyotrophic Lateral Sclerosis
Loss of Function of C9orf72 Causes Motor Deficits in a Zebrafish Model of Amyotrophic Lateral Sclerosis
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DOI：
10.1002/ana.23946
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发表时间：
2013-08-01
影响因子：
11.2
通讯作者：
Kabashi, Edor
中科院分区：
文献类型：
--
作者：
Ciura, Sorana;Lattante, Serena;Kabashi, Edor
目的探讨C9orf72基因GGGGCC六核苷酸重复扩增在肌萎缩侧索硬化症(ALS)和额颞叶变性(FTLD)发病机制中的作用。为了确定斑马鱼C9orf72同源基因(ZC9orf72)的功能丧失是否会导致神经元发育异常，建立了ALS的遗传模型。方法定量检测FTLD和ALS/FTLD患者脑组织和淋巴母细胞中C9orf72基因的表达水平。用2个特异的反义吗啉寡核苷酸阻断转录，敲除zC9orf72。结果六核苷酸重复序列正常或扩增的散发性FTLD和ALS/FTLD患者脑组织和淋巴母细胞中C9orf72转录本的表达显著降低。ZC9orf72在发育阶段的神经系统中选择性表达。ZC9orf72转录本的功能丧失会导致与运动相关的行为和细胞缺陷，而不会出现重大的形态异常。我们的结果表明，C9orf72单倍体不足可能是ALS/FTLD神经退行性疾病谱系中的一个促成因素。在斑马鱼中表达zC9orf72的同源基因zC9orf72的功能丧失与运动神经元轴突变性有关，表达人C9orf72基因可以挽救运动神经元的轴突变性，突出了诱导表型的特异性。这些结果揭示了C9orf72水平降低的致病后果，支持了疾病的功能丧失机制。
ObjectiveTo define the role that repeat expansions of a GGGGCC hexanucleotide sequence of the C9orf72 gene play in the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). A genetic model for ALS was developed to determine whether loss of function of the zebrafish orthologue of C9orf72 (zC9orf72) leads to abnormalities in neuronal development.MethodsC9orf72 mRNA levels were quantified in brain and lymphoblasts derived from FTLD and ALS/FTLD patients and in zebrafish. Knockdown of the zC9orf72 was performed using 2 specific antisense morpholino oligonucleotides to block transcription. Quantifications of spontaneous swimming and tactile escape response, as well as measurements of axonal projections from the spinal cord, were performed.ResultsSignificantly decreased expression of C9orf72 transcripts in brain and lymphoblasts was found in sporadic FTLD and ALS/FTLD patients with normal-size or expanded hexanucleotide repeats. The zC9orf72 is selectively expressed in the developing nervous system at developmental stages. Loss of function of the zC9orf72 transcripts causes both behavioral and cellular deficits related to locomotion without major morphological abnormalities. These deficits were rescued upon overexpression of human C9orf72 mRNA transcripts.InterpretationOur results indicate C9orf72 haploinsufficiency could be a contributing factor in the spectrum of ALS/FTLD neurodegenerative disorders. Loss of function of the zebrafish orthologue of zC9orf72 expression in zebrafish is associated with axonal degeneration of motor neurons that can be rescued by expressing human C9orf72 mRNA, highlighting the specificity of the induced phenotype. These results reveal a pathogenic consequence of decreased C9orf72 levels, supporting a loss of function mechanism of disease.