CYCS

04月03日的《热心肠日报》，我们解读了 15 篇文献，关注：心血管，IBD，昼夜节律，紧密连接蛋白，肠神经，肠道运动，肠道生理，Gritstone bio，爱荷华州立大学，乐普医疗，济群医疗，Get Joy。 该篇日报由R·AI辅助创作生成，人工审核校对。 Cell：肠道菌群+代谢组分析，揭示出代谢胆固醇的肠菌 Cell——[64.5] ① 本研究对弗雷明汉心脏研究队列的1429人进行了粪便宏基因组学和非靶向代谢组学分析，探索肠道菌群对心血管疾病（CVD）的影响和机制；② 多组学分析揭示了与CVD指标相关的微生物和代谢物，并分析了与CVD相关的微生物途径（如类黄酮、γ-丁基甜菜碱和胆固醇代谢）；③ Oscillibacter 菌属物种与粪便和血液胆固醇水平降低相关；④ 结合分子网络和蛋白质语言模型进行功能预测，鉴定出 Oscillibacter 物种编码的保守的胆固醇代谢基因（如 IsmA 和 CgT 的同系物）和衍生产物（如胆甾烯酮和糖基化胆固醇）；⑤ 体外实验证实，源自人肠道的 Oscillibacter 分离株能有效摄取胆固醇并将其转化为胆甾烯酮、糖基化胆固醇和羟基胆固醇等代谢物；⑥ 这些发现为靶向肠道菌群以改善心血管健康提供了新的科学依据。 【原文信息】 Gut microbiome and metabolome profiling in Framingham heart study reveals cholesterol-metabolizing bacteria 2024-04-02 , doi: 10.1016/j.cell.2024.03.014 Cell：结肠炎中的细胞生物地理学研究 Cell——[64.5] ① 本研究利用MERFISH技术分析了小鼠结肠中的135万个细胞、940个基因的表达谱，揭示了结肠炎和恢复过程中的细胞和空间重塑；② 确定了健康细胞群和炎症相关细胞群的多样性，绘制了它们的空间组织，并揭示了它们在炎症中的极化或招募，炎症相关成纤维细胞（IAF）反应比预期更加多样化；③ 基于细胞群的空间组织特点，定义了25个细胞邻域（neighborhood），并揭示了这些邻域在肠道炎症不同阶段的进展性演变，这种组织重塑一定程度上是由多种IAF定义的，它们具有独特的表达谱、空间定位、细胞间互作和健康成纤维细胞起源；④ 在人类溃疡性结肠炎中发现了类似的特征，表明这些过程在人类中可能是保守的。 【原文信息】 Charting the cellular biogeography in colitis reveals fibroblast trajectories and coordinated spatial remodeling 2024-04-02 , doi: 10.1016/j.cell.2024.03.013 Nature子刊：发育过程中，肠道昼夜节律如何形成？ Nature Communications——[16.6] ① 本研究揭示了在果蝇成体肠道中昼夜节律时钟的突然出现及其与环境逐渐同步的过程，为理解昼夜节律在发育和干细胞系中的作用提供了新视角；② 生物钟在成体果蝇肠道中突然开始，并在肠道发育完成后逐渐与环境同步，这种延迟是因为早期阶段的个别细胞缺乏完整的生物钟基因网络；③ 随着肠道的发育，生物钟首先在肠道干细胞中形成，Ecdysone和Hnf4信号的变化影响Clk/cyc的转录活性，从而驱动tim、Pdp1和vri的表达；④ 在成熟肠道中，干细胞谱系的分化暂时中断了不同分化后代中的生物钟活性，类似于早期发育中没有生物的现象。 【原文信息】 The emergence of circadian timekeeping in the intestine 2024-02-27 , doi: 10.1038/s41467-024-45942-4 北肿团队Nature Reviews：紧密连接蛋白claudin 18.2——治疗胃癌新靶点 Nature Reviews Clinical Oncology——[78.8] ① 日本国立癌症研究中心东医院研究学者与北京大学肿瘤医院沈琳教授团队合作，围绕紧密连接蛋白claudin 18.2在胃癌治疗中的潜力进行综述性总结；② Claudin 18.2特异性地表达于非恶性胃黏膜上皮细胞，但在消化系统恶性肿瘤中会异位至肿瘤细胞表面并高表达；③ 两项关键的III期临床试验证明，针对claudin 18.2的抗体zolbetuximab显著提高了晚期胃癌患者的无进展生存期和总生存期，标志着claudin 18.2成为胃癌治疗的一个有效靶点；④ 除了单克隆抗体外，双特异性抗体、抗体药物偶联物、嵌合抗原受体T细胞和基于mRNA的方法等新型治疗手段在针对claudin 18.2表达的胃癌患者中展现出巨大潜力；⑤ 针对claudin 18.2的治疗策略有望扩展到其他claudin 18.2阳性的实体瘤疾病中。 【原文信息】 Claudin 18.2 as a novel therapeutic target 2024-03-19 , doi: 10.1038/s41571-024-00874-2 肠道紧密连接蛋白Claudin-2或是脓毒症的潜在治疗靶点 PNAS——[11.1] ① 本研究揭示了在脓毒症中，claudin-2的上调和孔径通道通透性的增加是导致菌群失调、肠道损伤、炎症、病原体控制无效和败血症患者死亡率增加的关键中间体；② 脓毒症患者和模型小鼠中，小肠上皮细胞的claudin-2表达被选择性上调，同时细胞间孔径通道的通透性增加；③ 在脓毒症模型中，claudin-2敲除（KO）可阻止孔径通道通透性的增加，减少IL-17的产生、T细胞活化，并限制肠道损伤，这些效应与KO小鼠腹腔液的中性粒细胞、巨噬细胞、树突状细胞和细菌数量的减少相关；④ claudin-2敲除显著提高了脓毒症小鼠的存活率，且将claudin-2敲除且诱导脓毒症小鼠的盲肠菌群移植给WT健康小鼠的致病性显著低于野生型小鼠；⑤ claudin-2的表达对败血症期间激活的致命级联反应的进展具有显著影响，表明claudin-2可能是败血症患者中非常具有潜力的治疗靶点。 【原文信息】 Claudin-2 upregulation enhances intestinal permeability, immune activation, dysbiosis, and mortality in sepsis 2024-02-27 , doi: 10.1073/pnas.2217877121 浙大团队：小鼠肠神经系统完全源自迷走神经嵴细胞 Gastroenterology——[29.4] ① 浙江大学医学院的王良与国外团队合作发表文章，通过遗传工程鼠胚和细胞迁移实验，揭示了哺乳动物肠神经系统（ENS）完全源自迷走神经嵴细胞（vNCCs），推翻了先前关于骶部神经嵴细胞（sNCCs）也有贡献的观点；② 构建基因改造小鼠，对包括vNCCs的pan-NCCs或不包括vNCCs的骶/躯干部神经嵴细胞（s/tNCCs）进行谱系追踪，发现pan-NCCs和s/tNCCs对已经建立的神经嵴细胞（NCCs）有贡献，但只有pan-NCCs对ENS有贡献；③ 双谱系追踪结合三维重建显示，s/tNCCs以复杂的模式定居在骨盆神经丛和直肠周围组织中，解释了以往对其贡献的混淆；④ 共培养实验显示，自主神经、感觉和神经管外植物向直肠的细胞迁移是非特异性的；⑤ 对ENS前体进行谱系追踪，证明小鼠ENS的起源是独家由vNCCs提供。 【原文信息】 Sacral neural crest-independent origin of the enteric nervous system in mouse 2024-03-05 , doi: 10.1053/j.gastro.2024.02.034 新方法更有效对肠神经进行计数 Gastroenterology——[29.4] ① 这项研究发现相比于传统的组织切片技术，组织透明化和三维成像技术能更好地分析肠神经系统（ENS）的结构信息，揭示了ENS结构在儿童期间会发生变化，这种三维ENS解剖学可能为人类肠道运动障碍，包括赫什朋病（Hirschsprung disease, HD），提供新的视角；② 对11个人类结肠和1个回肠样本以及已知无肠道问题的远端结肠标本进行清晰、染色和共聚焦显微成像；③ 从新生儿到60岁的人类结肠中，肠神经系统的结构随年龄变化，包括肌间丛面积、ENS神经节面积、肌间丛中神经节所占比例、每平方毫米神经元数量和神经元Feret直径等指标；④ 三维成像的神经元计数显示高度可重复性，新生儿结肠的高ENS密度使得在较小区域内（500 x 500 μm2）也能进行可靠的神经元计数；⑤ HD病的远端肠道缺乏ENS，其样本在近端边缘肠神经元密度上变化了8倍，并在切除的肠道中具有多样的ENS结构。 【原文信息】 Three-dimensional imaging of the enteric nervous system in human pediatric colon reveals new features of Hirschsprung disease 2024-03-15 , doi: 10.1053/j.gastro.2024.02.045 Cell子刊：肠神经系统如何影响肠道微生物和肠道生理? Cell Reports——[8.8] ① 本研究揭示了特定的外周神经元激活对小鼠肠道微生物群落及其代谢产物和宿主生理的影响，为理解肠道神经系统与微生物之间的相互作用提供了新见解；② 通过激活表达乙酰胆碱转移酶（ChAT）或酪氨酸羟化酶（TH）的肠道相关神经元，发现这些神经元的不同亚型在塑造微生物群落结构（包括调节胆汁酸谱和真菌定植方面）发挥着广泛作用；③ 激活ChAT+或TH+神经元均可增加粪便排泄量，但只有ChAT+激活才会导致结肠收缩增加和类似腹泻的液体分泌；④ 这些结果表明，特定的外周神经元亚型激活在不涉及大脑信号的情况下，以不同方式调节小鼠的肠道微生物群落和胃肠生理。 【原文信息】 Peripheral neuronal activation shapes the microbiome and alters gut physiology 2024-03-21 , doi: 10.1016/j.celrep.2024.113953 外周5-羟色胺神经元或调节肠道蠕动和焦虑样行为 Current Biology——[9.2] ① 本研究揭示了外周5-羟色胺神经元在调节肠道蠕动和焦虑样行为中的作用，为开发新型治疗方法提供了参考；② 通构建一种外周神经元中缺乏产生5-羟色胺酶Tph2、但中枢神经元中的Tph2保持完整的小鼠，发现全身敲除Tph2的小鼠会表现出领土攻击性的增加，而仅在外周神经元中敲除Tph2没有这种现象；③ 与全身Tph2敲除小鼠相似，这些条件性敲除Tph2的小鼠展现处肠道蠕动减少和焦虑样行为降低；④ 这些结果表明，外周5-羟色胺神经元对肠道蠕动和焦虑样行为的控制有重要作用。 【原文信息】 Peripheral serotonergic neurons regulate gut motility and anxiety-like behavior 2024-02-26 , doi: 10.1016/j.cub.2023.12.072 果蝇前肠通过感官信息协调消化和免疫反应 PNAS——[11.1] ① 本研究分析了果蝇前肠如何通过感官信息协调消化和免疫反应，发现在动物进化过程中，前肠以一种保守的方式协调饮食感知、激素调节和免疫；② 通过GFP标记和Gal4报告基因系列验证了不同细胞类型，发现与前肠相关的神经内分泌细胞通过协调肠道活动与营养、菌群和昼夜周期发挥重要的整合作用；③ 前胃（PV）由多种上皮细胞构成，PV分泌沿肠道排列的围食膜基质，控制消化和肠道菌群的相互作用，在靠近肠细胞的地方会产生大量黏液，类似于哺乳动物的肠黏膜；④ 食道和唾液腺表达的分泌蛋白排列在食道表面，其中一些可能产生前肠共生生态位，容纳特定的肠道菌群。 【原文信息】 Cellular and molecular organization of the Drosophila foregut 2024-03-05 , doi: 10.1073/pnas.2318760121 Gritstone bio公布癌症疫苗GRANITE治疗结直肠癌积极结果 ① 4月2日，Gritstone bio公司宣布，其个体化癌症疫苗GRANITE在结直肠癌临床2/3期试验中显示出积极结果；② GRANITE联合免疫检查点抑制剂及氟嘧啶/贝伐珠单抗作为一线维持治疗，可改善微卫星稳定性结直肠癌（MSS-CRC）患者的疾病无进展生存期（PFS）；③ MSS-CRC患者占结直肠癌患者的80-85%，其肿瘤通常对免疫疗法不敏感；④ 临床试验共104位患者入组，初步分析67位患者数据显示，GRANITE组患者PFS有早期获益趋势；⑤ GRANITE疫苗已获得FDA的快速通道资格，研究预计2024年第三季度获得成熟的PFS数据，2025年上半年获得总生存期数据。 【原文信息】 速递 | 改善结直肠癌患者PFS！有效治疗“冷”肿瘤的mRNA疫苗结果出炉 2024-04-02 , 药明康德 爱荷华州立大学获250万美元NIH资助研究肠-心脏轴 ① 近日，美国爱荷华州立大学科研人员Ajit Vikram博士获得美国国立卫生研究院（NIH）250万美元（约合人民币1808万元）资助，用以研究肠-心脏轴；② 该项目旨在揭示肠道微生物如何影响心脏健康，特别是在心脏超负荷工作条件下的健康问题；③ Vikram的实验室自2017年以来一直在研究肠道微生物如何能够保护心脏免受疾病影响，其近期研究发现，肠道微生物调节的microRNA（miR-204）在应对心脏压力中起着关键作用；④ 未来，研究将结合微生物组学、宏基因组学、代谢组学、免疫学以及microRNA相关知识，以期能发现治疗心力衰竭的潜在治疗靶点。 【原文信息】 Vikram receives $2.5M R01 to examine the heart-gut connection 2024-04-01 , University of Iowa 乐普医疗MWN101两项2期临床完成首例患者给药 ① 3月29日，乐普医疗宣布，旗下上海民为生物自主研发的MWN101注射液两项2期临床试验完成首例受试者给药；② MWN101是国内首个GLP-1/GCGR/GIP-Fc融合蛋白药物，用于治疗2型糖尿病和肥胖或超重；③ 该药物通过血糖依赖性刺激胰岛素分泌、延缓胃排空等机制调节人体代谢和控制血糖；④ 两项2期临床研究旨在评价MWN101治疗2型糖尿病和超重或肥胖患者的有效性、安全性及药代动力学特征。 【原文信息】 乐普医疗:关于自愿披露GLP-1/GCGR/GIP-Fc融合蛋白MWN101完成Ⅱ期临床试验首例受试者给药的提示性公告 2024-03-29 , 股吧 济群医药IBD新药GP-033临床获批 ① 近日，济群医药新药GP-033软胶囊获得国家药监局药品审评中心审评通过和临床批件；② GP-033拟定适应证为：治疗炎症性肠病（IBD），包括溃疡性结肠炎和克罗恩病等；③ GP-033是一种新一代钙调磷酸酶抑制剂，与现有药物相比，GP-033活性强3倍以上，安全性更高，治疗窗更宽；④ 鉴于GP-033的活性和安全性，其在较低剂量下可用于中重度溃疡性结肠的缓解和维持治疗，临床有效性和安全性明显优于经典药物环孢素。 【原文信息】 再下一城！济群医药IBD新药GP-033喜获临床批件 2024-03-30 , 济群医药科技 Get Joy宣布与Phillips Pet Food and Supplies建立合作 ① 3月28日，Get Joy宣布与宠物食品分销商Phillips Pet Food and Supplies建立合作伙伴关系；② 本次合作旨在将Get Joy的犬类健康产品通过直销和零售渠道覆盖全美国；③ Get Joy成立于2019年，专注于研发营养健康产品来提升犬类及其家庭的生活质量；④ 其产品线包括冻干餐、新鲜餐食、冻干食品零食、咀嚼片以及即将推出的补充剂；⑤ 其产品将通过Phillips Pet Food and Supplies在美国的6000多家独立宠物零售商进行销售。 【原文信息】 Get Joy partners with Phillips Pet Food and Supplies 2024-03-28 , Pet Food Industry 感谢本期日报的审核者：mildbreeze，章台柳，RZN，Richard，lxx 点击阅读过去10天的日报： 0402 | 保肠护关节：高分研究揭示抵御关节炎的肠道因子 0401 | 3月，最值得关注的35篇肠道健康要闻！ 0331 | 聚焦特殊人群：老年人和孕妈妈的饮食新知 0330 | Akk菌或是免疫性肾病帮凶？Science子刊揭示机制 0329 | 33页综述纵论：超加工食品健康转型的新策略 0328 | Science子刊：锁定肠道中让病毒逃脱免疫的"避风港" 0327 | 10文聚焦菌群-肠-脑轴研究新进展 0326 | 100分综述详解：IBD细胞因子疗法最前沿 0325 | 大肠癌患病为何年轻化？遗传与生活方式的双重影响 0324 | 大型临床试验：补钙补D如何影响老年女性长期健康？

A newly evolved enzyme could one day make silicone compounds biodegradable. For the first time, scientists have engineered an enzyme that can break stubborn human-made bonds between silicon and carbon that exist in widely used chemicals known as siloxanes, or silicones. The discovery is a first step toward rendering the chemicals, which can linger in the environment, biodegradable. "Nature is an amazing chemist, and her repertoire now includes breaking bonds in siloxanes previously thought to evade attack by living organisms," says Frances Arnold, the Linus Pauling Professor of Chemical Engineering, Bioengineering and Biochemistry at Caltech and winner of the 2018 Nobel Prize in Chemistry for her pioneering work in directed evolution, a method for engineering enzymes and other proteins using the principles of artificial selection. Arnold and her colleagues, including Dimitris (Dimi) Katsoulis of Michigan-based Dow Inc. used directed evolution to create the new silicon-carbon bond-cleaving enzyme. The results are published in the January 26 issue of the journal Science. The researchers say that while practical uses for their engineered enzyme could still be a decade away or more, its development opens the possibility that siloxanes could one day be degraded biologically. "For example, natural organisms could evolve in siloxane-rich environments to catalyze a similar reaction, or further improved versions of laboratory-evolved enzymes such as this one could possibly be used to treat siloxane contaminants in wastewater," Arnold says. Katsoulis explains that nature doesn't use silicon-carbon bonds, "but we do and have been for about 80 years. The volatile nature of some of these compounds warrants health and environmental research to properly understand the degradation mechanisms of these materials in the environment." Siloxane chemicals can be found in countless products, including those used in household cleaning, personal care, and the automotive, construction, electronics, and aerospace industries. The compounds' chemical backbone is made of silicon-oxygen bonds, while carbon-containing groups, often methyl, are attached to the silicon atoms. "The silicon-oxygen backbone gives the polymer an inorganic-like character while the silicon-methyl groups give the polymer organic-like characteristics. Thus, these polymers have unique material properties, such as high thermal and oxidative stability, low surface tension, and high backbone flexibility among others," Katsoulis says. Siloxanes are believed to persist in the environment for days to months, and, therefore, ongoing research aims to provide greater scientific understanding of the health and environmental safety of silicone materials. The chemicals naturally start to fragment into smaller pieces, especially in soil or aquatic environments, and those fragments become volatile or escape into the air, where they undergo degradation by reacting with free radicals in the atmosphere. Of all the bonds in siloxanes, the silicon-carbon bonds are the slowest to break down. Katsoulis approached Arnold to collaborate on efforts to speed up siloxane degradation after he read about her lab's work in coaxing nature to produce silicon-carbon bonds. In 2016, Arnold and her colleagues used directed evolution to engineer a bacterial protein called cytochrome c to form silicon-carbon bonds, a process that does not occur in nature. "We decided to get nature to do what only chemists could do -- only better," Arnold said in a Caltech news release. The research demonstrated that biology could make these bonds in ways that are more environmentally friendly than those traditionally used by chemists. In the new study, the researchers wanted to find ways to break the bonds rather than create them. The scientists used directed evolution to evolve a bacterial enzyme called cytochrome P450. Directed evolution is similar to breeding dogs or horses in that the process is designed to bring out desired traits. The researchers first identified a variant of cytochrome P450 in their collection of enzymes that had a very weak ability to break silicon-carbon bonds in so-called linear and cyclic volatile methylsiloxanes, a common subgroup of the siloxane family. They mutated the DNA of the cytochrome P450 and tested the new variant enzymes. The best performers were then mutated again, and the testing was repeated until the enzyme was active enough to enable the researchers to identify the products of the reaction and study the mechanism by which the enzyme works. "Evolving enzymes to break these bonds in siloxanes presented unique hurdles. With directed evolution, we must evaluate hundreds of new enzymes in parallel to identify a few enzyme variants with improved activity," says Tyler Fulton (PhD '22), co-lead author of the study and a postdoctoral scholar at Caltech in Arnold's lab. One challenge involved the siloxane molecules leaching plastic components from the 96-well plates used to screen the variants. To solve the problem, the team created new plates made from common lab supplies. "Another challenge was finding the starting enzyme for the directed evolution process, one with even just a tiny amount of the desired activity," Arnold says. "We found it in our unique collection of cytochrome P450s evolved in the laboratory for other types of new-to-nature silicon chemistry." The final improved enzyme does not directly cleave the silicon-carbon bond but rather oxidizes a methyl group in the siloxanes in two sequential steps. Basically, this means that two carbon-hydrogen bonds are replaced with carbon-oxygen bonds, and this change allows the silicon-carbon bond to break more readily. The research draws parallels to studies involving a plastic-eating enzyme, explains Fulton, referring to a polyethylene terephthalate (PET)-degrading enzyme discovered in the bacteria Ideonella sakaiensis in 2016 by a different group of researchers. "While the PET-degrading enzyme was discovered by nature rather than by engineers, that enzyme inspired other innovations that are finally coming to fruition for plastic degradation. We hope this demonstration will similarly inspire further work to help break down siloxane compounds," he says.

Scientists have discovered how some cancer cells survive treatment and cause cancer to recur, along with a potential way to stop the process. Scientists at St. Jude Children's Research Hospital have identified how some cancer cells cheat treatment-induced cell death. In doing so, they persist and lead to cancer recurrence. The findings may serve as the basis for drugs that prevent relapses by inhibiting cancer cells from gaining these persistence traits. The research was published today in Cell. After treatment, sometimes the cancer returns, called a recurrence. Researchers knew that a small population of cancer cells sometimes become drug resistant and persist after treatment. These "persister" cells can then reconstitute a more aggressive form of the same cancer. Until now it was unclear how these cells initially change to become persistent. "When it comes to cancer cells, what doesn't kill them makes them stronger," said corresponding author Doug Green, Ph.D., Department of Immunology chair. "The field has begun to recognize that just because a cell engages apoptosis [a cell death pathway] doesn't mean it will die. Our conceptual leap was that such 'near death experiences' could be responsible for the generation of persister cells. This was unexpected -- it was like finding a piece of a treasure map that you never knew was missing -- new paths to discovery have opened up." A near-death experience Many drugs to treat cancer trigger apoptosis. St. Jude researchers found that a key event that leads to apoptosis, the release of the protein cytochrome c from mitochondria, occurs in persister cells. Historically, researchers believed that once cytochrome c was released into the cell, apoptosis could not be stopped. The evidence that some cells survive the process has grown, but it was unclear how, or why survival would lead to more aggressive cancer. The St. Jude group showed in the lab that these persistor cells do start apoptosis and that this near-death experience is key to their survival. Investigators showed that cytochrome c release kickstarts another process that can override the cell death pathway. In this study, the scientists found that when cytochrome c is released, persister cells activate a pathway called the integrated stress response in addition to apoptosis. The stress response pathway is normally used by cells to detect a problem and fix it. In persister cells, the stress response pathway stops apoptosis and promotes the expression of genes that prolong survival. "The phenomenon of persistence is caused by the 'near death experience' of engaging the mitochondrial pathway of apoptosis without dying," Green said. "We found that the generation of persister cells requires the process that leads to cytochrome c release, but instead of undergoing apoptosis, the cells survive and become persisters. In effect, these are cells that have undergone 'failed apoptosis.'" The simultaneous promotion of survival and inhibition of apoptosis also may explain why persister cells become resistant to other treatments in addition to the original drug used to treat the cancer. Though such treatments do have different mechanisms of action, most drugs ultimately induce apoptosis. Because apoptosis is inhibited, these persister cell have a general resistance to cancer therapies. Potential drug targets The research can serve as a basis for drugs that may prevent cancer recurrence by interfering with the key protein in the stress response. In persister cells, the stress response results in an increase of the protein activating transcription factor 4 (ATF4) within the cell. ATF4 is a master regulator of the stress response, resulting in the elimination of proteins that promote cell death and the upregulation of genes that promote survival. The change in gene expression due to ATF4 appears to be critical to persister cells. If ATF4 is knocked out or inhibited, the cancer cells are unable to resist the initial cancer treatment. The same happens when the protein that activates ATF4, Heme-regulated Inhibitor (HRI), is removed or inhibited. The team discovered that genes that are regulated by ATF4 in their persister cells were similarly regulated in cancer cells from patients that had survived chemotherapy, suggesting that the process occurs during cancer treatment. A model of persister formation The authors propose a model of how persisters form. When a cancer is subjected to a pro-apoptotic drug, cytochrome c is released into the cell. This begins the process of apoptosis. Simultaneously, the protein HRI is activated by cytochrome c, as part of the stress response pathway. HRI in turn causes more ATF4 to be expressed. ATF4 then changes the cells state from dying to survival. The researchers were able to show that their artificially induced persister cells were more aggressive and formed more colonies in mouse models than the original cancer cells, matching the metastatic nature of recurrent tumors. The study was supported by grants from by the National Cancer Institute (R50CA211481, P30CA021765, R35CA231620), German Research Foundation (DFG, KA 4830/1-1), and ALSAC, the fundraising and awareness organization of St. Jude.