TNFRSF21

细胞焦亡（Pyroptosis）是由Gasdermin（GSDM） 家族蛋白介导的程序性细胞坏死。近年来，大量的研究表明细胞焦亡与多种疾病相关，包括败血症、细菌感染、慢性炎症、自身免疫病、神经退行性疾病以及肿瘤等。前期研究表明，GSDM蛋白的C端对N端的抑制作用使得全长Gasdermin蛋白处于自抑制状态，阻碍其诱导细胞焦亡。因此，在细胞焦亡过程中，Gasdermin蛋白需要被蛋白酶剪切释放其具备打孔活性的N端结构域，再转运至细胞膜形成孔道，导致细胞膜通透性改变，细胞不断吸水胀大，最终引起细胞焦亡。 前期，吴乔课题组在细胞焦亡领域取得了多项研究成果，包括阐明了Tom20感知铁激活的ROS信号促进细胞焦亡抑制黑色素瘤生长的机制（Cell Research，2018，封面文章）；揭示了代谢产物α-KG通过死亡受体DR6激活caspase-8诱导GSDMC依赖的细胞焦亡机制（Cell Research，2021，highlighted in the cover）；发现甘露糖可以通过激活 AMPK，磷酸化GSDME的第6位苏氨酸，阻断caspase-3剪切GSDME，进而抑制细胞焦亡。这一新发现进一步应用于临床，证实了甘露糖可以减轻化疗药物引起的正常组织焦亡所导致的毒副作用（Cell Research，2023，封面文章）。系列研究成果丰富了细胞焦亡的调控网络，为细胞焦亡的临床应用提供了理论依据。 在细胞应激状态下，全长Gasdermin能否直接诱导细胞焦亡以及如何解除自抑制状态并不清楚。邵峰院士课题组早期发现在GSDM-C端和GSDM-N端结合的界面引入氨基酸突变，可以解除Gasdermin的自抑制状态，全长Gasdermin则具备了自主诱导细胞焦亡的能力，首次提示Gasdermin蛋白可以通过不依赖于蛋白酶剪切的方式诱导细胞焦亡（Nature，2016）。 近期，美国吴皓院士课题组在Nature发文，报道了ROS通过诱导全长GSDMD发生棕榈酰化修饰，使其具备了成孔和诱导细胞焦亡的能力（Nature, 2024）。与此同时，邵峰院士团队也在Science 发表文章，揭示了在低等真核生物中两类只含有膜打孔结构域的GSDM蛋白可以分别通过氧化还原调控或配对的分子间相互作用释放其膜打孔活性，从而诱导焦亡（Science, 2024）。这两篇文章进一步证明全长Gasdermin蛋白（如GSDMD）可以通过不依赖于蛋白酶剪切的方式诱导细胞焦亡。 2024年7月12日，吴乔课题组在Nature Cell Biology在线发表文章"Fulllength GSDME mediates pyroptosis independent from cleavage"，从机制上阐释了全长GSDME通过剪切非依赖的方式诱导细胞焦亡的新通路。 研究发现，当细胞被UVC照射后，线粒体发生断裂（mitochondrial fission），导致线粒体ROS（mitoROS）提高，进而触发细胞色素c的过氧化物酶活性，氧化线粒体心磷脂，促进lipid ROS的产生。 Lipid ROS信号被GSDME直接感知，导致GSDME氧化多聚。与此同时，UVC照射导致的DNA损伤激活PARP1产生大量的PAR（Poly(ADP-ribose)）并释放到胞浆，胞浆中的PAR则与PARP5结合，激活 PARP5活性，以此促进其与GSDME结合，诱导GSDME发生PARylation修饰，导致GSDME构象发生改变，解除GSDME-C端对其N端的自抑制状态，进而促进GSDME感知lipid-ROS信号。这两种不同的蛋白修饰协同作用导致了全长GSDME靶向质膜定位并打孔，从而诱导细胞焦亡。 基于这一新发现，作者进一步确定了全长GSDME介导的细胞焦亡不仅仅局限于UVC照射。同时激活PARP的活性和提高lipid ROS水平的药物或者DNA损伤诱导剂和lipid ROS诱导剂联合处理同样能够诱导全长 GSDME 依赖的细胞焦亡。该研究挑战了焦亡诱导需要蛋白酶剪切的传统概念，阐明了全长GSDME不依赖蛋白酶剪切诱导细胞焦亡的新机制及其调控模式，进一步证实了全长GSDME与GSDMD一样可以直接诱导细胞焦亡，为研究细胞焦亡的新范式奠定了理论基础。 全长GSDME通过非剪切方式诱导细胞焦亡的信号网络和调控机制模式图 生命科学学院吴乔教授和陈航姿教授为论文的共同通讯作者，博士后周波、博士生江志洪和硕士生戴梦燃为论文的共同第一作者。 文章链接： https://www.nature.com/articles/s41556-024-01463-2 原文链接： https://life.xmu.edu.cn/info/1045/27831.htm 本文仅用于学术分享，转载请注明出处。若有侵权，请联系微信：bioonSir 删除或修改！

引言 细胞焦亡 (Pyroptosis) 是由Gasdermin（GSDM）家族蛋白介导的程序性细胞坏死。GSDM蛋白的C端对N端的抑制作用使得全长Gasdermin蛋白处于自抑制状态，阻碍其诱导细胞焦亡。因此，既往研究都认为在细胞焦亡过程中，Gasdermin蛋白需要被蛋白酶剪切释放其具备打孔活性的N端结构域，再转运至细胞膜打孔，导致细胞膜通透性改变，细胞不断吸水胀大，最终引起细胞焦亡。 全长Gasdermin能否直接诱导细胞焦亡并不清楚。邵峰课题组早期发现在GSDM-C端和GSDM-N端结合的界面引入氨基酸突变，可以解除Gasdermin的自抑制状态，全长Gasdermin则具备了自主诱导细胞焦亡的能力，首次提示Gasdermin蛋白可以通过不依赖于蛋白酶剪切的方式诱导细胞焦亡（Nature, 2016）。近期，哈佛大学吴皓课题组在Nature发文，报道了ROS通过诱导全长GSDMD发生棕榈酰化修饰，使其具备了成孔和诱导细胞焦亡的能力（Nature, 2024）。与此同时，邵峰团队也在Science发表文章，揭示了在低等真核生物中两类只含有膜打孔结构域的GSDM蛋白可以分别通过氧化还原调控或配对的分子间相互作用释放其膜打孔活性，从而诱导焦亡（Science, 2024，Science丨丁璟珒/邵峰合作揭示真核生物焦亡蛋白GSDM非酶切依赖的全新激活机制）。这两篇文章证明了全长Gasdermin蛋白（如GSDMD）可以通过不依赖于蛋白酶剪切的方式诱导细胞焦亡。 2024年7月31日，吴皓教授受邀在Nature Cell Biology杂志的News & Views专栏撰写题为Cleavage-independent GSDME activation by UVC的亮点文章，介绍厦大生科院吴乔教授和陈航姿教授合作在细胞焦亡研究领域取得的最新重要进展。 吴皓教授通过长篇幅系统总结了该研究的创新发现。当细胞被高强度的UVC照射后，线粒体发生断裂（mitochondrial fission），导致线粒体ROS（mito-ROS）提高，进而触发细胞色素c的过氧化物酶活性，氧化线粒体心磷脂，促进lipid ROS的产生。Lipid ROS信号被GSDME直接感知，导致GSDME氧化多聚。与此同时，UVC照射导致的DNA损伤激活PARP1产生大量的PAR（Poly(ADP-ribose)）并释放到胞浆，胞浆中的PAR则与PARP5结合，激活PARP5活性，以此促进其与GSDME结合，诱导GSDME发生PARylation修饰，导致GSDME构象发生改变，解除GSDME-C端对其N端的自抑制状态，进而促进GSDME感知lipid-ROS信号。这两种不同的蛋白修饰协同作用导致了全长GSDME靶向质膜定位并打孔，从而诱导细胞焦亡。基于这一新发现，作者进一步确定了全长GSDME介导的细胞焦亡不仅仅局限于UVC照射。同时激活PARP的活性和提高lipid ROS水平的药物或者DNA损伤诱导剂和lipid ROS诱导剂联合处理同样能够诱导全长GSDME依赖的细胞焦亡。最后，吴皓教授总结指出该项研究揭示了全长GSDME通过非经典的方式诱导细胞焦亡的新机制，不仅增强了对GSDMs如何非典型激活的见解，而且可能会启发研究者发现更多促进甚至抑制细胞死亡的生理靶标。 同时，吴皓教授在文中还指出几个值得进一步探究的方向，包括：鉴于GSDME结构模型预测发生氧化修饰的半胱氨酸残基（Cys156/Cys180）之间的分子间距离太远，不利于二硫键的形成，需要通过GSDME结构分析进一步阐明GSDME中分子间二硫键是如何形成的；其他信号机制是否可以通过其他形式的蛋白修饰而汇聚到这条通路；此外，该通路如何与其他类型的细胞死亡和宿主免疫防御发生交互调控仍是一个悬而未决的问题；该通路在其他gasdermin蛋白、细胞类型和生物体中的有效性也需进一步探究。 吴皓教授绘制的全长GSDME通过剪切非依赖的方式诱导细胞焦亡的模式图（Credit: Nature Cell Biology） 据悉，该研究成果已于2024年7月12以Full-length GSDME mediates pyroptosis independent from cleavage 为题发表在Nature Cell Biology。 吴乔课题组在细胞焦亡领域取得了多项研究成果，包括阐明了Tom20感知铁激活的ROS信号促进细胞焦亡抑制黑色素瘤生长的机制  (Cell Research，2018，封面文章)；揭示了代谢产物α-KG通过死亡受体DR6激活caspase-8诱导GSDMC依赖的细胞焦亡机制 (Cell Research，2021，highlighted in the cover)；发现甘露糖可以通过激活AMPK，磷酸化GSDME的第6位苏氨酸，阻断caspase-3剪切GSDME，进而抑制细胞焦亡。这一新发现进一步应用于临床，证实了甘露糖可以减轻化疗药物引起的正常组织焦亡所导致的毒副作用 (Cell Research，2023，封面文章)。系列研究成果丰富了细胞焦亡的调控网络，为细胞焦亡的临床应用提供了理论依据。近日他们在Nature Cell Biology在线发表文章，从机制上阐释了全长GSDME通过剪切非依赖的方式诱导细胞焦亡的新通路。该研究阐明了全长GSDME不依赖蛋白酶剪切诱导细胞焦亡的新机制及其调控模式，进一步证实了全长GSDME与GSDMD一样可以直接诱导细胞焦亡，为研究细胞焦亡的新范式奠定了理论基础。 参考文献 https://www.nature.com/articles/s41556-024-01463-2 https://www. nature.com/articles/s41556-024-01470-3 责编|探索君 排版|探索君 文章来源|“BioArt” End 往期精选 围观 一文读透细胞死亡(Cell Death) | 24年Cell重磅综述（长文收藏版） 热文 Cell | 是什么决定了细胞的大小？ 热文 Nature | 2024年值得关注的七项技术 热文 Nature | 自身免疫性疾病能被治愈吗？科学家们终于看到了希望 热文 CRISPR技术进化史 | 24年Cell综述

A review did uncover a complaint “alleging scientific misconduct by another postdoc." Genentech has published the findings of its investigation into an alleged fraud and cover-up involving a 2009 Nature paper co-authored by Marc Tessier-Lavigne. None of the 35 current and former employees interviewed for the probe reported knowing of fraud, but the process did leave unanswered questions about image “anomalies” and brought an unrelated misconduct issue to public attention. In February, The Stanford Daily reported that an internal review “discovered falsification of data in the research” into the potential role of death receptor six (DR6) and amyloid precursor protein (APP) in Alzheimer’s disease, and claimed Tessier-Lavigne, Genentech’s former chief scientific officer, “kept the finding from becoming public.” The student-run newspaper ran a follow-up article last month after obtaining an email from a Stanford professor that said “there was discussion of fraud/fakery and MTL knew.” Genentech responded to the reports by conducting its own investigation. The findings (PDF) largely exonerate Tessier-Lavigne, now the president of Stanford, while still leaving loose ends that may simply reflect the challenges of investigating events that began around 15 years ago.  Here’s the top-line positive finding for the accused: “None of the current or former employees who were interviewed reported observing or knowing of any fraud, fabrication, or other intentional wrongdoing in the research leading to and reported in the 2009 Nature paper.” Genentech was also unable to find any evidence that its Research Review Committee investigated fraud, fabrication or misconduct related to the work at the time, as was claimed in the original article. Other aspects of the review are less clear-cut. Genentech tasked “an independent, outside expert who specializes in detecting image manipulations in scientific publications” with looking at the paper. The expert found two sets of figures that include duplicate images and a Western blot panel that “appears to include a composite of two images.” “We have not determined how these anomalies occurred,” the report states. One challenge is that some of the original data and images are missing. Noting that the research took place nearly 15 years ago. Genentech said “some data and images were saved on electronic storage media that may no longer exist.” The report states “Genentech scientists and research associates had difficulty reproducing certain results reported in the 2009 Nature paper, in particular, the binding interaction between DR6 and N-APP.” Genentech researchers not involved in the 2009 paper achieved inconsistent results when they tried to replicate the study, an issue that some of them attributed to “the purity and quality of the reagents used.” The inconsistency was evident prior to publication and persisted across three years of research. “Senior leaders at Genentech including Dr. Tessier-Lavigne knew of the inconsistent binding results, and there was uncertainty and speculation within the Genentech Research organization about why the binding interaction between DR6 and N-APP could not be reliably reproduced or confirmed,” the report states. After Tessier-Lavigne left Genentech, a senior leader in gRED, the biotech’s research unit, urged that the paper should be retracted or corrected in light of the inconsistent binding results. Only Tessier-Lavigne or another co-author could take such an action.  Genentech decided to perform other experiments to evaluate binding and determine whether DR6 was a viable Alzheimer’s target. Ultimately, genetic experiments in two mouse models killed off the program. The experiments found amyloid plaques and other features of Alzheimer’s weren’t dependent on DR6, leading Genentech to stop work on the target in 2012. “Many scientists who worked on the project were disheartened by having devoted substantial time and energy to a program whose underlying biology was ultimately proven wrong. That sentiment gave rise to rumors about why the DR6 program failed,” the report states. The review did uncover a complaint “alleging scientific misconduct by another postdoc working in Dr. Tessier-Lavigne’s laboratory.” The complaint was dealt with at the time, leading to the termination of the postdoc’s employment and withdrawal of a manuscript. The complaint was unrelated to DR6.