Sulfide metabolism at the host microbiome interface

项目摘要 硫化氢(H2S)是一种氧化还原活性信号分子，调节电子传递和能量 新陈代谢，以及大部分未知的机制，介导神经和心脏保护，血管扩张， 低氧反应，蛋白质翻译，表观遗传学，衰老，以及结肠的病理和生理反应。 由于硫化氢在高剂量下也是一种呼吸道毒物，细胞会主动氧化它以产生过硫化物、亚硫酸盐、 硫代硫酸盐(统称为活性硫物种)和硫酸盐。蛋白质的氧化修饰 半胱氨酸硫醇转化为过硫化物被认为是硫化氢信号的主要机制。潜力 然而，其他活性硫物种是否参与信号转导尚不清楚。我们实验室的研究表明 研究表明，硫化氢通过对线粒体能量学的双重作用影响细胞的氧化还原代谢。 在低浓度时增加电子通量，在高浓度时抑制电子通量。接触外源硫化氢的最高水平 发生在结肠(0.2-2.4毫米)，来自肠道驻留的微生物区系，合成硫化物。初步 我们实验室的数据显示，结肠上皮细胞将外源H_2S定量氧化为硫代硫酸盐，并 硫化物氧化酶在小鼠结肠细胞中的定位和表达水平很高 受肠道中硫酸盐还原细菌的存在或不存在的影响。我假设这个动态 宿主和微生物硫代谢产物之间的相互作用影响宿主的新陈代谢，影响寿命。vbl.使用 秀丽隐杆线虫作为模式生物，它具有完整的同源基因参与 在人类中发现的硫化氢的生物发生和氧化，很容易受到遗传和饮食操作的影响 对于寿命分析，我将通过以下两个目标来检验我的假设。(I)我将描述如何 硫化氢水平和活性硫物种的变化影响有机体氧化还原和组蛋白修饰 与线虫的长寿和应激反应有关。硫化氢水平及其氧化副产物将受到调节 通过外源H2S、RNA干扰敲除宿主硫化物氧化酶，并通过饮食，使用 与硫代谢有关的特定基因缺失的大肠杆菌。我会评估外生性 与饮食相比，硫化氢的调节通过基因编码的还原-氧化作用影响生物的氧化还原 灵敏的GRX1-roGFP2传感器和跟踪组蛋白甲基化和乙酰化状态的变化 与氧化还原、硫化氢可获得性、饮食和衰老有关。(二)我将调查外源硫化氢暴露的差异 来自空气和肠道的微生物影响宿主硫化物氧化酶的表达和定位， 活性硫物种的丰度和类型，以及它们对寿命的影响。我将用以下内容补充这些研究 代谢学和转录组分析，以确定受硫化氢暴露影响的途径。这个 这些研究的成功完成将为我们理解硫的相互作用奠定基础 宿主-微生物界面的新陈代谢。

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.