Shin Baehyun, Jung Roy, Oh Hyejin, Owens Gwen E, Lee Hyeongseok, Kwak Seung, Lee Ramee, Cotman Susan L, Lee Jong-Min, MacDonald Marcy E, Song Ji-Joon, Vijayvargia Ravi, Seong Ihn Sik
Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Neurology, Harvard Medical School, Boston, MA 02114, USA.
Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Mol Ther Nucleic Acids. 2018 Jun 1;11:416-428. doi: 10.1016/j.omtn.2018.03.008. Epub 2018 Mar 16.
The CAG repeat expansion that elongates the polyglutamine tract in huntingtin is the root genetic cause of Huntington's disease (HD), a debilitating neurodegenerative disorder. This seemingly slight change to the primary amino acid sequence alters the physical structure of the mutant protein and alters its activity. We have identified a set of G-quadruplex-forming DNA aptamers (MS1, MS2, MS3, MS4) that bind mutant huntingtin proximal to lysines K2932/K2934 in the C-terminal CTD-II domain. Aptamer binding to mutant huntingtin abrogated the enhanced polycomb repressive complex 2 (PRC2) stimulatory activity conferred by the expanded polyglutamine tract. In HD, but not normal, neuronal progenitor cells (NPCs), MS3 aptamer co-localized with endogenous mutant huntingtin and was associated with significantly decreased PRC2 activity. Furthermore, MS3 transfection protected HD NPCs against starvation-dependent stress with increased ATP. Therefore, DNA aptamers can preferentially target mutant huntingtin and modulate a gain of function endowed by the elongated polyglutamine segment. These mutant huntingtin binding aptamers provide novel molecular tools for delineating the effects of the HD mutation and encourage mutant huntingtin structure-based approaches to therapeutic development.
导致亨廷顿蛋白中多聚谷氨酰胺序列延长的CAG重复序列扩增是亨廷顿舞蹈病（HD）的根本遗传病因，HD是一种使人衰弱的神经退行性疾病。这种对一级氨基酸序列看似微小的改变会改变突变蛋白的物理结构并改变其活性。我们已经鉴定出一组能与C端CTD-II结构域中赖氨酸K2932/K2934附近的突变型亨廷顿蛋白结合的G-四链体形成DNA适配体（MS1、MS2、MS3、MS4）。适配体与突变型亨廷顿蛋白的结合消除了由扩增的多聚谷氨酰胺序列赋予的增强的多梳抑制复合物2（PRC2）刺激活性。在HD而非正常神经元祖细胞（NPC）中，MS3适配体与内源性突变型亨廷顿蛋白共定位，并与PRC2活性显著降低相关。此外，MS3转染可通过增加ATP保护HD NPC免受饥饿依赖性应激。因此，DNA适配体可以优先靶向突变型亨廷顿蛋白，并调节由延长的多聚谷氨酰胺片段赋予的功能获得。这些与突变型亨廷顿蛋白结合的适配体为阐明HD突变的影响提供了新的分子工具，并鼓励基于突变型亨廷顿蛋白结构的治疗开发方法。
