DDX3X and specific initiation factors modulate FMR1 repeat-associated non-AUG-initiated translation
DDX3X and specific initiation factors modulate FMR1 repeat-associated non-AUG-initiated translation
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DOI：
10.15252/embr.201847498
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发表时间：
2019-07-25
期刊：
影响因子：
7.7
通讯作者：
Todd, Peter K.
中科院分区：
文献类型：
--
作者：
Linsalata, Alexander E.;He, Fang;Todd, Peter K.
FMR1的5 ' UTR中的CGG三核苷酸重复扩增导致神经退行性疾病脆性x相关震颤/共济失调综合征（FXTAS）。该重复序列支持一种非规范的蛋白质合成模式，称为重复序列相关的非aug （RAN）翻译。在CGG重复序列上RAN翻译的机制尚不清楚。为了确定RAN翻译的修饰因子和潜在的治疗靶点，我们在基于细胞的检测和果蝇FXTAS模型中进行了真核起始因子和RNA解旋酶的候选筛选。在fmr15 ' UTR的背景下，我们从扩展的CGG重复序列中鉴定出了多种毒性修饰因子和RAN翻译。这些包括DEAD-box RNA解旋酶belle/DDX3X、解旋酶辅助因子EIF4B/4H和起始密码子选择性因子EIF1和EIF5。破坏belle/DDX3X选择性地抑制了果蝇体内和培养的人细胞中FMR1 RAN的翻译，减轻了重复诱导的果蝇和啮齿动物初级神经元的毒性。这些发现暗示RNA二级结构和起始密码子保真度是介导FMR1 RAN翻译的关键因素，并确定了治疗重复相关神经变性的潜在靶点。
A CGG trinucleotide repeat expansion in the 5 ' UTR of FMR1 causes the neurodegenerative disorder Fragile X-associated tremor/ataxia syndrome (FXTAS). This repeat supports a non-canonical mode of protein synthesis known as repeat-associated, non-AUG (RAN) translation. The mechanism underlying RAN translation at CGG repeats remains unclear. To identify modifiers of RAN translation and potential therapeutic targets, we performed a candidate-based screen of eukaryotic initiation factors and RNA helicases in cell-based assays and a Drosophila melanogaster model of FXTAS. We identified multiple modifiers of toxicity and RAN translation from an expanded CGG repeat in the context of the FMR1 5 ' UTR. These include the DEAD-box RNA helicase belle/DDX3X, the helicase accessory factors EIF4B/4H, and the start codon selectivity factors EIF1 and EIF5. Disrupting belle/DDX3X selectively inhibited FMR1 RAN translation in Drosophila in vivo and cultured human cells, and mitigated repeat-induced toxicity in Drosophila and primary rodent neurons. These findings implicate RNA secondary structure and start codon fidelity as critical elements mediating FMR1 RAN translation and identify potential targets for treating repeat-associated neurodegeneration.