小柯机器人

近日，美国哈佛医学院刘如谦等研究人员合作发现，体内碱基编辑可挽救小鼠的Hutchinson-Gilford早衰综合征。2021年1月6日，《自然》杂志在线发表了这项成果。

研究人员表示，Hutchinson-Gilford早衰综合症（HGPS或早衰症）通常是由LMNA（编码核纤层蛋白A的基因）中显性阴性C•G到T•A突变（c.1824 C> T； p.G608G）引起的。这种突变会导致RNA错误剪接，从而产生早老蛋白，这是一种有毒蛋白，可引起快速衰老，并将早衰儿童的寿命缩短至大约14岁。腺嘌呤碱基编辑器（ABE）将目标化的A•T碱基对转化为G•C碱基对，且副产物最少、无需双链DNA断裂或供体DNA模板。

研究人员使用了ABE来直接纠正源自早衰症儿童的成纤维细胞和HGPS小鼠模型中的致病性HGPS突变。从患有HGPS的儿童向成纤维细胞进行慢病毒ABE递送可导致病原体等位基因校正87??％至91％，从而减少RNA错剪接，降低早老素水平并校正核异常。无偏脱靶DNA和RNA编辑分析未检测到治疗后的患者来源成纤维细胞中的脱靶编辑。

在人类LMNA c.1824 C> T等位基因纯合子的转基因小鼠中，一次眶后注射编码ABE的腺相关病毒9（AAV9）可以对病原性突变进行实质性、持久的校正（注射后六个月内各器官中约20–60％），从而恢复正常的RNA剪接并降低早老蛋白的水平。体内碱基编辑挽救了小鼠的血管病理，保留了血管平滑肌细胞计数并防止了外膜纤维化。在产后第14天单次注射表达ABE的AAV9可以改善活力，并将小鼠的平均寿命从215天延长至510天。

这些发现表明，通过直接纠正其根本原因，体内碱基编辑具有作为HGPS和其他遗传疾病的治疗潜力。

附：英文原文

Title: In vivo base editing rescues Hutchinson–Gilford progeria syndrome in mice

Author: Luke W. Koblan, Michael R. Erdos, Christopher Wilson, Wayne A. Cabral, Jonathan M. Levy, Zheng-Mei Xiong, Urraca L. Tavarez, Lindsay M. Davison, Yantenew G. Gete, Xiaojing Mao, Gregory A. Newby, Sean P. Doherty, Narisu Narisu, Quanhu Sheng, Chad Krilow, Charles Y. Lin, Leslie B. Gordon, Kan Cao, Francis S. Collins, Jonathan D. Brown, David R. Liu

Issue&Volume: 2021-01-06

Abstract: Hutchinson–Gilford progeria syndrome (HGPS or progeria) is typically caused by a dominant-negative CG-to-TA mutation (c.1824 C>T; p.G608G) in LMNA, the gene that encodes nuclear lamin A. This mutation causes RNA mis-splicing that produces progerin, a toxic protein that induces rapid ageing and shortens the lifespan of children with progeria to approximately 14 years1,2,3,4. Adenine base editors (ABEs) convert targeted AT base pairs to GC base pairs with minimal by-products and without requiring double-strand DNA breaks or donor DNA templates5,6. Here we describe the use of an ABE to directly correct the pathogenic HGPS mutation in cultured fibroblasts derived from children with progeria and in a mouse model of HGPS. Lentiviral delivery of the ABE to fibroblasts from children with HGPS resulted in 87–91% correction of the pathogenic allele, mitigation of RNA mis-splicing, reduced levels of progerin and correction of nuclear abnormalities. Unbiased off-target DNA and RNA editing analysis did not detect off-target editing in treated patient-derived fibroblasts. In transgenic mice that are homozygous for the human LMNA c.1824 C>T allele, a single retro-orbital injection of adeno-associated virus 9 (AAV9) encoding the ABE resulted in substantial, durable correction of the pathogenic mutation (around 20–60% across various organs six months after injection), restoration of normal RNA splicing and reduction of progerin protein levels. In vivo base editing rescued the vascular pathology of the mice, preserving vascular smooth muscle cell counts and preventing adventitial fibrosis. A single injection of ABE-expressing AAV9 at postnatal day 14 improved vitality and greatly extended the median lifespan of the mice from 215 to 510 days. These findings demonstrate the potential of in vivo base editing as a possible treatment for HGPS and other genetic diseases by directly correcting their root cause.

DOI: 10.1038/s41586-020-03086-7

Source: https://www.nature.com/articles/s41586-020-03086-7

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