Post-translational modifications clustering within proteolytic domains decrease mutant huntingtin toxicity
Post-translational modifications clustering within proteolytic domains decrease mutant huntingtin toxicity
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DOI：
10.1074/jbc.m117.782300
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发表时间：
2017-11-24
影响因子：
4.8
通讯作者：
Ross, Christopher A.
中科院分区：
文献类型：
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作者：
Arbez, Nicolas;Ratovitski, Tamara;Ross, Christopher A.
亨廷顿病(HD)在很大程度上是由亨廷顿蛋白(Htt)内的聚谷氨酰胺扩张引起的。翻译后修饰(PTMS)控制和调节许多蛋白质功能和细胞通路，突变Htt的翻译后修饰可能是HD发病的重要调节因子。Htt片段的选定数目的PTM的改变已被证明调节Htt细胞的定位和毒性。在这项研究中，我们系统地介绍了全长Htt结构中个别磷酸化和乙酰化位点的定点改变。使用我们的核浓缩实验测试了这些PTM改变构建体中的每一个对细胞毒性的影响，并通过测量线粒体的潜力和大小来测试对线粒体活性的影响。利用这些原代神经元的功能分析，我们发现了几个PTM，它们的改变可以阻断神经元的毒性，防止突变Htt引起的线粒体潜在的丢失和肿胀。这些PTM包括先前描述的位点，如丝氨酸116和新发现的贯穿整个蛋白质的位点，如丝氨酸2652。我们发现，这些功能相关的位点聚集在整个Htt全长的蛋白酶敏感区域中。这些发现促进了我们对Htt PTM编码及其在HD发病机制中的作用的理解。因为PTM是由酶催化的，所以这里发现的毒性调节的Htt PTMS可能是治疗HD的有希望的治疗靶点。
Huntington's disease (HD) is caused in large part by a polyglutamine expansion within the huntingtin (Htt) protein. Post-translational modifications (PTMs) control and regulate many protein functions and cellular pathways, and PTMs of mutant Htt are likely important modulators of HD pathogenesis. Alterations of selected numbers of PTMs of Htt fragments have been shown to modulate Htt cellular localization and toxicity. In this study, we systematically introduced site-directed alterations in individual phosphorylation and acetylation sites in full-length Htt constructs. The effects of each of these PTM alteration constructs were tested on cell toxicity using our nuclear condensation assay and on mitochondrial viability by measuring mitochondrial potential and size. Using these functional assays in primary neurons, we identified several PTMs whose alteration can block neuronal toxicity and prevent potential loss and swelling of the mitochondria caused by mutant Htt. These PTMs included previously described sites such as serine 116 and newly found sites such as serine 2652 throughout the protein. We found that these functionally relevant sites are clustered in protease-sensitive domains throughout full-length Htt. These findings advance our understanding of the Htt PTM code and its role in HD pathogenesis. Because PTMs are catalyzed by enzymes, the toxicity-modulating Htt PTMs identified here may be promising therapeutic targets for managing HD.