Developmental genetic analysis of mouse dysmyelination mutant, quaking.

小鼠髓鞘发育不良突变体的发育遗传分析，颤抖。

• 批准号: 09672311
• 负责人: ABE Kuniya
• 金额: $ 1.92万
• 依托单位: KUMAMOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09672311/
• 关键词: MYELIN FORMATION; ATAXIA; OLIGODENDROCYTE; KNOCKOUT MOUSE; BAC; TRANSGENIC MOUSE; RNA結合蛋白質; 胚発生

A responsible gene for mouse mutation showing ataxic phenotype was sought and analyzed in order to understand the etiology of the ataxia. [Results] It was found that qkl gene was spanning about 70 kb of genomic region, and consists of at least 10 exons. It gives rise to six distinct transcripts encoding, theoretically, five different protein isoforms. Exons 1 through 4 are shared by all the transcripts, whereas coding exons and two distinct 3'-UTRs downstream to the exon 4 are differentially utilized. One isoform has a truncated KH domain and may act as an antagonist to the others. These mRNA appear to encode a putative RNA binding protein containing one KH motif required for RNA binding activity. We have made three lines of qkl knockout mouse, of which two were analyzed in detail. Mice heterozygous for the KO allele behave normally. However, double heterozygotes in combination with the original qk allele (=qkv) showed rapid tremor, clearly demonstrating that qkl gene is the responsibl … More e gene for the quaking mutation. Furthermore, this double heterozygote compound mice showed even more severe phenotype compared to the qkv/qkv mice ; early onset of convulsion, gait abnormality, or growth retardation. In many ways this phenotype resembles that of some of the human leukodystrophies. This severe phenotype is probably due to premature arrest of myelination : the oligodendrocyte processes fail to properly interact with the axons to form compacted myelin. qkl expression was found to be significantly reduced in qkv homozygotes and was even less in the compound, qkv/qklO.Thus myelination appears to be sensitive to the dosage of qkl. In fact, when qkl level is increased by introduction of BAG clone containing the whole qkl gene, the tremor phenotype was completely recovered. mRNA expression of other myelin genes including PLP, MBP were reduced in the qk mutants, and there were almost no protein products for these genes. Furthermore, mRNA splicing of MAG, PLP and probably MBP is altered by the reduced qkl expression. These results sugegst that qkl is an essential regulator of myelination in CNS, and probably plays important role in post-transcriptional regulation of the myelin genes. Less

为了了解共济失调的病因，寻找并分析了表现出共济失调表型的小鼠突变的负责基因。【结果】qk 1基因全长约70 kb，由至少10个外显子组成。它产生六种不同的转录本，理论上编码五种不同的蛋白质亚型。外显子1至4由所有转录物共享，而编码外显子和外显子4下游的两个不同的3 '-UTR被差异地利用。一种亚型具有截短的KH结构域，并可作为其他亚型的拮抗剂。这些mRNA似乎编码一个假定的RNA结合蛋白，含有一个RNA结合活性所需的KH基序。我们建立了三个品系的qkl基因敲除小鼠，并对其中两个品系进行了详细的分析。KO等位基因杂合子小鼠行为正常。然而，双杂合子与原始qk等位基因（= qk）结合显示快速震颤，清楚地表明qkl基因是导致震颤的原因。 ...更多信息 震动突变的基因。此外，该双杂合子复合小鼠显示出比qv-grafik/qv-grafik小鼠更严重的表型;早期惊厥发作、步态异常或生长迟缓。在许多方面，这种表型类似于某些人类脑白质营养不良。这种严重的表型可能是由于髓鞘形成的过早停滞：少突胶质细胞过程未能正确地与轴突相互作用以形成致密的髓鞘。发现qkl表达在qkl纯合子中显著降低，并且在化合物qkl/qklO中甚至更低。事实上，当通过引入含有完整qkl基因的BAG克隆来增加qkl水平时，震颤表型完全恢复。其他髓鞘基因包括PLP、MBP在qk突变体中的mRNA表达降低，几乎没有蛋白产物。此外，MAG、PLP和可能的MBP的mRNA剪接被减少的qkl表达改变。这些结果提示qkl是中枢神经系统髓鞘形成的重要调控因子，可能在髓鞘基因的转录后调控中起重要作用。少

项目成果

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