刷屏了！韩春雨NgAgo论文被自然子刊撤稿

最近，国家科技部、教育部、中国科协等多部门通报了《肿瘤生物学》集中撤稿事件彻查处理情况。紧接着，2017年8月2日，自然生物技术编辑部发表题为《Time for the data to speak，是该数据说话的时候了》的评论。宣称通过Argonaute酶实现基因编辑的研究（即韩春雨NgAgo论文研究）被撤回，这显示了论文发表后的同行评议在全天候媒体时代的重要性。

全文如下：

Retraction of a study claiming gene editing via an Argonaute enzyme illustrates the importance of post-publication peer review in the age of 24/7 media.

NATURE BIOTECHNOLOGY | EDITORIAL

• Nature Biotechnology (2017)

•  doi:10.1038/nbt.3938

• Published online  02 August 2017

Retraction of a study claiming gene editing via an Argonaute enzyme illustrates the importance of post-publication peer review in the age of 24/7 media.

In this issue, Chunyu Han and colleagues retract a paper published in May 2016 claiming that an Argonaute protein (NgAgo) from the archaea Natronobacterium gregoryi can be guided by short 5′ phosphorylated single-stranded DNAs to generate double-strand breaks and edit the human genome (Nat. Biotechnol. 34, 768–773, 2016). Although the paper was initially greeted with enthusiasm from researchers and intense media interest, speculation as to its reproducibility quickly grew, fueled by Twitter, blogs and other social media. Last November, this journal issued an Editorial Expression of Concern to alert the community to these reproducibility questions. Final resolution of the controversy necessitated the generation of additional experimental data from several groups over many months. That a retraction is now issued is testament to the considerable time, effort and funds invested by many laboratories around the globe that have sought to clarify NgAgo's function.

It is hard to overstate the impact of the Han paper following its publication last year, especially in China, where the paper originated. Coverage in the Chinese media was extensive, with headlines heralding the discovery of an entirely new gene editing system. The NgAgo report was easily the most widely covered paper in China last year; according to media monitor Meltwater, nearly 4,000 Chinese news stories cited the Han paper in just the first two months after publication.

The excitement generated by NgAgo centered on its potential to complement, or perhaps even supersede, the CRISPR–Cas9 gene editing system. NgAgo promised gene editing that required only a single target sequence (Cas9 needs both the target sequence and an additional adjacent recognition (PAM) sequence). What's more, initial data suggested advantages in terms of enhanced stability of the guide (DNA compared with RNA for Cas9), improved specificity, reduced off-target editing of the genome and improved activity in GC-rich regions of the genome; and the reagents used were easier to synthesize and handle.

If all this sounded too good to be true, the failure last summer of an increasing number of laboratories to reproduce the genome editing activity reported in the Han paper started to raise doubts. The paper became a hotly discussed topic at genome editing conferences, news groups and e-mail lists. It didn't take long before the press took notice. Claims and counterclaims regarding the validity of the initial report were exchanged. Nature Biotechnology's internal image integrity screening process found no obvious anomalies in the Han paper, a finding echoed by three external reviewers who reexamined the data.

Meanwhile, Nature Biotechnology kept in contact with the community about ongoing efforts to replicate the paper. Ultimately, the editors were able to coordinate the work of three independent groups into a single peer-reviewed refutation paper (Nat. Biotechnol. 35, 17–18, 2017). With these data in hand, we then had sufficient cause to alert our readers to potential problems with the paper by publishing the Editorial Expression of Concern, which now appears alongside the original paper online—a step that was supported by two of the authors, including Han.

We also asked the authors if they could shed light on why the community was having difficulties reproducing their results. Accordingly, last December, Han and colleagues and several additional independent groups who contacted the journal provided new data claiming to have reproduced NgAgo gene editing activity. At the time, these data were judged too preliminary by the editors and an external reviewer to warrant publication. We decided to give the original authors and new groups more time to gather additional experimental evidence to bolster their claims.

Now, more than a year after the publication of the original report, we have learned that the independent groups that reported initial success in reproducing the results have not been able to bolster their preliminary data to a publishable level. Similarly, after seeking feedback from expert reviewers, we have concluded that the latest data from Han and his colleagues are insufficient to counter the substantial body of evidence that contradicts their initial findings. We are now convinced that the decision of Han and colleagues to retract the paper is the best course of action to support the integrity of the published record.

Publication of the NgAgo paper was not the end of the scientific process, it was the start. Like any other report that appears in the literature, it is the wider research community that tests methods, identifies potential sources of error, validates reagents and optimizes assays. In this case, it took dozens of dedicated individuals to work through the details of the published protocol and produce well-documented and controlled refutation studies (Protein Cell 7, 913–915, 2016; Nat. Biotechnol.35, 17–18, 2017; Cell Res. 26, 1349–1352, 2016; PLoS One 12, e0177444, 2017).

The NgAgo controversy also illustrates the pros and cons of social media. Clearly, these platforms were valuable for rapidly alerting the wider scientific community to problems with the paper. But they also raised expectations that issues with this paper were straightforward and could be solved quickly. Unraveling all the problems with the NgAgo editing claim didn't happen in weeks or a few months for a reason. Even simple experiments take weeks to prepare, perform, analyze and troubleshoot. It does not help that the efforts of those carrying out replication studies often go unrewarded—it is unglamorous, unfunded and thankless work.

Little wonder then that to a 24/7 media and public that desire quick, definitive answers, the process of post-publication peer review can seem frustratingly slow. But when it comes to biology, answers are often not definitive. And when it comes to replication studies, the one thing we know is that it takes time. In the case of NgAgo, the time has come and the data have spoken.

全文中文翻译：

标题：是该数据说话的时候了

doi:10.1038/nbt.3938

一项宣称通过Argonaute酶实现基因编辑的研究被撤回，这显示了论文发表后的同行评议在全天候媒体时代的重要性。

本期，韩春雨及同事撤回了发表于去年5月的一篇论文。该论文称，短5′磷酸化单链DNA可引导格氏嗜盐碱杆菌核酸内切酶（NgAgo）产生双链断裂，实现对人类基因组的编辑。论文一发表，便引起科研人员的极大兴趣和媒体的竞相报道。但是很快，在推特、博客和其它社交媒体的助燃之下，有关该研究可重复性的质疑开始迅速增多。去年11月，本刊发表了“编辑部关注”（Editorial Expression of Concern），提醒科研界留意这些可重复性方面的担忧。为了最终解决这个争议，多个研究小组在数月里生成了更多的实验数据。如今尘埃落定，这也是世界各地的许多实验室为澄清NgAgo的功能而付出的大量时间、精力和资金的证明。

韩春雨的这篇论文自去年发表后所产生的影响力，再怎么夸张地说也不为过，尤其是在论文的来源地中国。中国媒体纷纷进行报道，以大标题宣告一项全新基因编辑系统的发现。这无疑是一篇中国去年被报道最多的论文；媒体监测公司融文（Meltwater）的数据显示，仅在论文发表后的最初两个月，就有将近4000篇相关的中文新闻报道。

NgAgo的轰动之处集中在它有可能补充，甚至取代CRISPR/Cas9基因编辑系统之一点上。NgAgo有望以一个目标序列进行基因编辑（Cas9不仅需要目标序列，还需要另外一个附近的识别（PAM）序列）。而且，初始数据还显示了它在其它方面的优势，如引物的稳定性更强（DNA相对于Cas9采用的RNA），增强特异性，减少基因组编辑脱靶，改善在基因组富含GC区域的活性，以及使所用的试剂更易于合成和处理。

如果说这一切都听上去太过美好而令人难以置信，那么去年夏天以来，随着越来越多的实验室无法重复该论文所报告的基因组编辑功能，质疑声便开始出现了。在各种基因组编辑会议上，在新闻讨论组和电子邮件中，这篇论文成为最热话题之一。这很快便引起媒体注意，有关该初始报告有效性的正反两方面的声音开始交锋。我们内部的图像完整性筛查没有发现韩春雨论文的明显异常，复查数据的三位外部评审人也持相同观点。

在此期间，《自然-生物技术》一直与科研界保持联络，关注各种为重复论文所做的持续努力。最终，在编辑们的协调下，三个独立小组的成果形成了一篇单独的反驳性论文，并通过了同行评议(Nat. Biotechnol.34, 768–773, 2016)。有了这些数据，我们就有充分的理由去提醒读者留意该论文可能存在问题，我们将正式的“编辑部关注”发表在该篇论文所在的网址上，此举得到包括韩春雨在内的两位论文作者的支持。

我们也询问了论文作者是否可以解答科研界为何难以重复他们的结果。于是，去年12月，韩春雨及同事，还有另外几个与本刊联系的独立研究小组，提供了新的数据，称已经重复了NgAgo基因编辑活性。当时，本刊编辑和一位外部评审人都判定这些数据太过初级，不满足发表标准。因此，我们决定给这些原始论文作者和新的研究小组更多时间来收集更多的能支持其论点的实验证据。

现在，距原论文发表已过去了一年多，我们了解到当初曾报告说初步成功重复出实验结果的独立研究小组，无法强化初始数据，使其达到可发表的水平。类似的，在征求专家评审人的反馈意见后，我们判定韩春雨及同事提供的最新数据不足以反驳大量与其初始发现相悖的证据。我们现在确信韩春雨的撤稿决定是维护已发表科研记录完整性的最好做法。

这篇有关NgAgo的论文发表出来，并不是科研过程的结束，而是开始。与任何其它发表出来的报告一样，正是广大的科研共同体对相关方法进行了检验，识别潜在的错误来源，验证试剂并优化试验。在本例中，有多位敬业的研究者个人对已发表实验方法的各种细节进行检验，并完成记录翔实和有对照组的反驳性研究 (Protein Cell 7, 913, 2016; Cell Res. 26, 1349–1352, 2016;PLoS One, 12, e0177444, 2017)。 

这篇NgAgo论文也显示了社交媒体的利与弊。显然，这些平台对于迅速提醒广大科学界留意该论文可能存在的问题发挥了重要作用。但是，它们也抬高了人们的预期，以为有关这篇论文的问题是直截了当，可以快速解决的。然而，关于NgAgo的各种问题是无法在几个星期或几个月内就能澄清的，这是有原因的。即使是简单的实验也需要花费数周来准备、实施、分析和解决出现的问题。另外于事无益的是，那些进行可重复性研究的人，其付出的努力往往得不到回报——这样的工作单调乏味，没有资金支持，还吃力不讨好。

难怪在希望得到快速、明确答案的全天候媒体和公众眼中，论文发表后的同行评议流程似乎慢得让人沮丧。但是，当涉及生物学时，往往没有明确的答案。当研究重复性时，有一点我们是知道的，那就是这需要花时间来做。就这篇有关NgAgo的论文而言，现在是时候了，数据已经说话了。

作者的撤稿声明：

Retraction: DNA-guided genome editing using the Natronobacterium gregoryi Argonaute

Feng Gao, Xiao Z Shen, Feng Jiang, Yongqiang Wu & Chunyu Han

Nat. Biotechnol. 34, 768–773 (2016); published online 2 May 2016; addendum published after print 28 November 2016; retracted 2 August 2017; doi:10.1038/nbt.3547

We are retracting our study because of the continued inability of the research community to replicate the key results in Figure 4, using the protocols provided in our paper. In this figure we report that the Natronobacterium gregoryi Argonaute can efficiently create double-strand breaks and edit the genome of human cells using 5ʹ phosphorylated single-stranded DNA as a guide. Despite the efforts of many laboratories (Protein Cell 7, 913–915, 2016; Nat. Biotechnol. 35, 17–18, 2017; Cell Res. 26, 1349–1352, 2016; PLOS One12, e0177444, 2017), an independent replication of these results has not been reported. We are therefore retracting our initial report at this time to maintain the integrity of the scientific record. We nevertheless continue to investigate the reasons for this lack of reproducibility with the aim of providing an optimized protocol.

撤稿声明链接：

http://www.nature.com/nbt/journal/v34/n7/full/nbt.3547.html

中文翻译：

撤稿：利用NgAgo进行DNA引导的基因组编辑

高峰，沈啸，姜峰，武永强和韩春雨

Nat. Biotechnol.34, 768-773 (2016); 2016年5月2日在线发表，论文进入印刷版后2016年11月28日在线发表补编；2017年8月2日撤稿；doi:10.1038/nbt.3547

由于科研界一直无法根据我们论文提供的实验方案重复出论文图4所示的关键结果，我们决定撤回这项研究。在该图中，我们报告说，利用5′磷酸化单链DNA作为引导，NgAgo（Natronobacterium gregoryi Argonaute）能够有效引起双链断裂，并对人体细胞基因组进行编辑。虽然许多实验室都进行了努力（Protein Cell 7, 913-915, 2016; Nat. Biotechnol.35, 17-18, 2017; Cell Res.26, 1349-1352, 2016; PLOS One 12, e0177444, 2017) ，但是没有独立重复出这些结果的报告。因此，我们现在撤回我们的最初报告，以维护科学记录的完整性。不过，我们会继续调查该研究缺乏可重复性的原因，以提供一个优化的实验方案。

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