OSIB: African lungfish CtxA, a toxin for skin defense during estivation

OSIB：非洲肺鱼 CtxA，一种夏眠期间皮肤防御毒素

• 批准号: 2212077
• 负责人: Irene Salinas
• 金额: $ 80.95万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-15 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2212077&HistoricalAwards=false
• 关键词: OSIB; African; lungfish; CtxA; toxin

Organismal adaptations to extreme environmental changes often involve drastic changes at mucosal barrier tissues. African lungfish can survive long drought periods via a physiological process called estivation. Estivation involves drastic remodeling of the skin and shedding of epidermal layers to form a cocoon. Previous work by our group demonstrated that the lungfish cocoon is a living tissue that contains many immune cells that trap bacteria, defending the lungfish body from pathogen invasion during a vulnerable, dormant state. Forming the cocoon, therefore involves self-inflicting mucosal inflammation but the molecular mechanisms underlaying cocoon formation are not understood. This proposal investigates a novel molecule called Protop-CtxA which is a toxin encoded in the lungfish genome. This toxin appears to have been acquired via horizontal gene transfer from bacteria or viruses. Protop-CtxA expression is highly up-regulated in the lungfish skin and cocoon upon estivation. We hypothesize that this molecule is sufficient to break down skin integrity in estivating lungfish and form in this way the cocoon. The goal of this work is to investigate which cells produce Protop-CtxA in free-swimming and estivating lungfish and to determine the inflammatory, antimicrobial and insecticidal functions of Protop-CtxA. The proposed work will advance our knowledge on extreme physiological adaptations of vertebrate animals and may result in many pharmaceutical and agricultural applications due to the bioactivity of this toxin. Broader impacts include outreach activities such as a lungfish exhibit in the Albuquerque Natural History Museum in Spanish and English and a radio podcast for the Children Hour at KUNM.The African lungfish (Protopterus sp.) lives in both water and land. Under unfavorable environmental conditions, lungfish enter estivation, a dormant state that can last for months or years and that involves the formation of a mucus cocoon that surrounds the animal body. We recently discovered that the lungfish cocoon is not just a dry mucus layer but is formed by many living cells including large numbers of granulocytes that transmigrate from the skin when layer after layer of epidermis is shed during the induction of estivation. Cocoon formation is associated with an extreme pro-inflammatory state with high expression levels of canonical pro-inflammatory cytokines and antimicrobial peptides and a large influx of granulocytes from circulation. How the cocoon is formed and mucosal inflammation instigated is not well understood. This proposal focuses on a novel toxin-like molecule discovered in the recently sequenced lungfish genome. This toxin, similar to Vibrio cholera toxin (CtxA), is phylogenetically related to box jellies and other invertebrate toxins. We hypothesize that Protop-CtxA was acquired via horizontal gene transfer from prokaryotes to lungfish during evolutionary history. Preliminary results indicate that Protop-CtxA, is very important during lungfish estivation and that dermal stem cells express it at the steady state. Using microscopy, transcriptomics, flow cytometry, in vitro antimicrobial and insecticidal assays and in vivo estivation experiments, the biological function of this toxin will be determined. This project is jointly funded by Symbiosis, Infection, and Immunity, and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

机体对极端环境变化的适应通常涉及粘膜屏障组织的剧烈变化。非洲肺鱼可以通过一种叫做夏眠的生理过程在长时间的干旱中生存下来。去活化涉及皮肤的剧烈重塑和表皮层脱落形成茧。我们小组以前的工作表明，肺鱼茧是一种活组织，含有许多捕获细菌的免疫细胞，在脆弱的休眠状态下保护肺鱼身体免受病原体入侵。因此，形成茧涉及自我造成的粘膜炎症，但茧形成的分子机制尚不清楚。该提案研究了一种名为Protop-CtxA的新型分子，这是肺鱼基因组中编码的毒素。这种毒素似乎是通过细菌或病毒的水平基因转移获得的。原CtxA的表达是高度上调肺鱼皮肤和茧夏眠后。我们假设这种分子足以破坏夏眠肺鱼的皮肤完整性，并以这种方式形成茧。这项工作的目的是调查哪些细胞产生Protop-CtxA在自由游泳和夏眠肺鱼，并确定炎症，抗菌和杀虫功能的Protop-CtxA。拟议的工作将推进我们对脊椎动物极端生理适应的认识，并可能导致许多药物和农业应用，由于这种毒素的生物活性。更广泛的影响包括外联活动，如在阿尔伯克基自然历史博物馆以西班牙语和英语举办的肺鱼展览，以及在KUNM为儿童时间举办的广播播客。生活在水中和陆地上。在不利的环境条件下，肺鱼进入夏眠，这是一种休眠状态，可以持续数月或数年，并在动物身体周围形成粘液茧。我们最近发现，肺鱼茧不只是一层干燥的粘液层，而是由许多活细胞形成的，包括大量的粒细胞，这些细胞是在夏眠诱导过程中，当一层又一层表皮脱落时，从皮肤中迁移出来的。茧形成与极端促炎状态相关，具有高表达水平的典型促炎细胞因子和抗微生物肽以及来自循环的大量粒细胞流入。茧是如何形成的，粘膜炎症是如何引起的还不清楚。这项提议的重点是在最近测序的肺鱼基因组中发现的一种新型毒素样分子。这种毒素类似于霍乱弧菌毒素（CtxA），与箱形水母和其他无脊椎动物毒素在遗传学上相关。我们推测，原CtxA获得通过水平基因转移从原核生物的肺鱼在进化史上。初步结果表明，Protop-CtxA，是非常重要的，在肺鱼夏眠和真皮干细胞表达它在稳定状态。利用显微镜，转录组学，流式细胞术，体外抗菌和杀虫试验和体内夏眠实验，这种毒素的生物学功能将被确定。该项目由共生、感染和免疫以及刺激竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。