RNA-binding ability of FUS regulates neurodegeneration, cytoplasmic mislocalization and incorporation into stress granules associated with FUS carrying ALS-linked mutations
RNA-binding ability of FUS regulates neurodegeneration, cytoplasmic mislocalization and incorporation into stress granules associated with FUS carrying ALS-linked mutations
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DOI：
10.1093/hmg/dds526
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发表时间：
2013-03-15
影响因子：
3.5
通讯作者：
Pandey, Udai Bhan
中科院分区：
文献类型：
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作者：
Daigle, J. Gavin;Lanson, Nicholas A., Jr.;Pandey, Udai Bhan
肌萎缩侧索硬化症（ALS）是一种罕见的神经退行性疾病，由上下运动神经元变性引起。几个基因，包括SOD 1，TDP-43，FUS，Ubiquilin 2，C9 orf 72和Profilin 1，与ALS的散发和熟悉形式有关。FUS是一种DNA/RNA结合蛋白（RBP），在ALS和额颞叶变性（FTLD）患者的大脑和脊髓中形成细胞质内含物。然而，目前尚不清楚FUS的RNA结合能力是否是导致ALS发病所必需的。在这里，我们利用果蝇模型ALS和神经元细胞系来阐明FUS的RNA结合能力在调节FUS介导的毒性、细胞质错误定位和并入应激颗粒（SGs）中的作用。为了确定FUS的RNA结合能力在ALS中的作用，我们突变FUS RNA结合位点（F305 L、F341 L、F359 L、F368 L），并产生具有和不具有ALS引起突变（R518 K或R521 C）的RNA结合缺陷的FUS突变体。我们发现，将上述四种苯丙氨酸（F）氨基酸突变为亮氨酸（L）（4F-L）消除了FUS RNA结合。我们观察到，与携带ALS引起突变的RNA结合活性FUS的表达相比，这些RNA结合突变阻断了在果蝇大脑、眼睛和运动神经元中观察到的神经退行性表型。有趣的是，RNA结合缺陷的FUS强烈定位于果蝇运动神经元和哺乳动物神经元细胞的细胞核，而携带ALS连锁突变的FUS分布于细胞核和细胞质。重要的是，我们确定突变FUS掺入SG隔室依赖于FUS的RNA结合能力。总之，我们证明了FUS的RNA结合能力对于突变FUS体内的神经退行性表型是必不可少的（通过与RNA直接接触或通过与其他RBP相互作用）。
Amyotrophic lateral sclerosis (ALS) is an uncommon neurodegenerative disease caused by degeneration of upper and lower motor neurons. Several genes, including SOD1, TDP-43, FUS, Ubiquilin 2, C9orf72 and Profilin 1, have been linked with the sporadic and familiar forms of ALS. FUS is a DNA/RNA-binding protein (RBP) that forms cytoplasmic inclusions in ALS and frontotemporal lobular degeneration (FTLD) patients' brains and spinal cords. However, it is unknown whether the RNA-binding ability of FUS is required for causing ALS pathogenesis. Here, we exploited a Drosophila model of ALS and neuronal cell lines to elucidate the role of the RNA-binding ability of FUS in regulating FUS-mediated toxicity, cytoplasmic mislocalization and incorporation into stress granules (SGs). To determine the role of the RNA-binding ability of FUS in ALS, we mutated FUS RNA-binding sites (F305L, F341L, F359L, F368L) and generated RNA-binding-incompetent FUS mutants with and without ALS-causing mutations (R518K or R521C). We found that mutating the aforementioned four phenylalanine (F) amino acids to leucines (L) (4F-L) eliminates FUS RNA binding. We observed that these RNA-binding mutations block neurodegenerative phenotypes seen in the fly brains, eyes and motor neurons compared with the expression of RNA-binding-competent FUS carrying ALS-causing mutations. Interestingly, RNA-binding-deficient FUS strongly localized to the nucleus of Drosophila motor neurons and mammalian neuronal cells, whereas FUS carrying ALS-linked mutations was distributed to the nucleus and cytoplasm. Importantly, we determined that incorporation of mutant FUS into the SG compartment is dependent on the RNA-binding ability of FUS. In summary, we demonstrate that the RNA-binding ability of FUS is essential for the neurodegenerative phenotype in vivo of mutant FUS (either through direct contact with RNA or through interactions with other RBPs).