Sulfide metabolism at the host microbiome interface

项目摘要 硫化氢（H2S）是一种具有氧化还原活性的信号分子，可调节电子传递和能量 代谢，并通过很大程度上未知的机制，介导神经和心脏保护，血管舒张， 缺氧反应、蛋白质翻译、表观遗传学、衰老以及结肠中的病理和生理反应。 由于H2S在高剂量下也是一种呼吸道毒物，细胞会主动氧化它产生过硫化物、亚硫酸盐， 硫代硫酸盐（统称为反应性硫物质）和硫酸盐。蛋白质氧化修饰 半胱氨酸硫醇转化为过硫化物被假定为H2S信号的主要机制。的潜在 然而，其它活性硫物质在信号传导中的参与是未知的。我们实验室的研究 表明H2S通过其对线粒体能量学的双重作用影响细胞氧化还原代谢，即 在低浓度下增加电子通量，在高浓度下抑制电子通量。暴露于外源性H2S的最高水平 存在于结肠中（0.2-2.4 mM），并且来源于肠驻留微生物群，其合成硫化物。初步 我们实验室的数据显示，结肠上皮细胞定量地将外源性H2S氧化成硫代硫酸盐， 小鼠结肠细胞中硫化物氧化酶的定位和表达水平强烈地 受肠道中硫酸盐还原菌存在与否的影响。我假设 宿主和微生物硫代谢物之间的相互作用影响宿主的新陈代谢并影响寿命。使用 秀丽隐杆线虫是一种模式生物，它具有完整的正向同源基因， H2S生物生成和氧化在人类中发现，并且容易受到遗传和饮食操纵， 对于寿命分析，我将通过以下两个目标来检验我的假设。(i)我会描述 H2S水平和活性硫物质的改变会影响生物体的氧化还原和组蛋白修饰， 与C.优雅H2S水平及其氧化副产物将被调节 通过外源H2S，RNA干扰敲低宿主硫化物氧化酶，以及通过饮食，使用 硫代谢相关基因缺失的大肠杆菌。我将评估 与饮食H2S调制影响有机体氧化还原使用遗传编码的还原-氧化 敏感的GRX 1-roGFP 2传感器，并跟踪组蛋白甲基化和乙酰化状态的变化， 与氧化还原、H2S可用性、饮食和衰老有关。(ii)我将研究外源性H2S暴露的差异 从空气与肠道微生物影响宿主硫化物氧化酶的表达和定位， 活性硫物质的丰度和类型，以及它们对寿命的影响。我将补充这些研究， 代谢组学和转录组学分析，以确定受H2S暴露影响的途径。的 这些研究的成功完成将是我们理解硫的相互作用的基础 在宿主-微生物界面的代谢。

Project Summary Hydrogen sulfide (H2S) is a redox-active signaling molecule that modulates electron transport and energy metabolism, and by largely unknown mechanisms, mediates neuro- and cardioprotection, vasodilation, the hypoxic response, protein translation, epigenetics, aging, and both patho- and physiological responses in colon. As H2S is also a respiratory poison at high doses, cells actively oxidize it to produce persulfides, sulfite, thiosulfate, (collectively referred to as reactive sulfur species), and sulfate. Oxidative modification of protein cysteine thiols to persulfides is postulated to be a primary mechanism by which H2S signals. The potential involvement of other reactive sulfur species in signaling is however, unknown. Studies in our laboratory have demonstrated that H2S impacts cellular redox metabolism via its dual effects on mitochondrial energetics, i.e. increasing electron flux at low, and inhibiting it at high concentrations. The highest exposure to exogenous H2S occurs in colon (0.2–2.4 mM) and is derived from gut resident microbiota, which synthesize sulfide. Preliminary data in our laboratory reveal that colonic epithelial cells quantitatively oxidize exogenous H2S to thiosulfate, and that the localization and expression levels of sulfide oxidation enzymes in murine colonocytes are strongly influenced by the presence or absence of sulfate reducing bacteria in the gut. I hypothesize that the dynamic interplay between host and microbial sulfur metabolites influences host metabolism and impacts longevity. Using Caenorhabditis elegans as a model organism, which has the full complement of orthologous genes involved in H2S biogenesis and oxidation found in humans and is readily amenable to genetic and dietary manipulation and to life-span analyses, I will test my hypothesis by addressing the following two aims. (i) I will characterize how alterations in H2S levels and reactive sulfur species impact organismal redox and histone modifications that are linked to longevity and stress response in C. elegans. H2S levels and its oxidative byproducts will be modulated by exogenous H2S, RNA interference knockdowns of host sulfide oxidation enzymes, and by diet, using Escherichia coli with deletions in specific genes involved in sulfur metabolism. I will assess how exogenous versus dietary H2S modulation affects organismal redox using the genetically encoded reduction-oxidation sensitive GRX1-roGFP2 sensor and track changes in histone methylation and acetylation status with reported links to redox, H2S availability, diet, and aging. (ii) I will investigate how differences in exogenous H2S exposure from air versus gut microbes affects the expression and localization of host sulfide oxidation enzymes, the abundance and type of reactive sulfur species, and their effect on lifespan. I will complement these studies with metabolomic and transcriptomic analyses to identify pathways that are impacted by H2S exposure. The successful completion of these studies will be foundational to our understanding of the interplay of sulfur metabolism at the host-microbe interface.