The Gastric Biology of Helicobacter Pylori

描述（由申请人提供）：目的是研究胃病原体幽门螺杆菌的胃生理学。具体目标：(A)；鉴定细胞质pH传感器的酸响应调控和信号系统。HP0244是一种之前未被发现的细胞质pH传感器。在pH 2.5孵育后，通过转录组分析，将鉴定出HP0244， HP0703独立的调节子，以分离周质（HP0165）和细胞质pH调节，并通过qPCR证实；(B)通过对比转录组分析感染沙鼠的幽门螺杆菌，鉴定定植依赖基因表达，并评估pH值对其表达的控制。与体外培养的幽门螺杆菌相比，体外培养的幽门螺杆菌感染沙鼠胃的转录组分析显示，与pH 4.5相比，体外培养的幽门螺杆菌对酸驯化相关蛋白编码基因的上调更大，这可能反映了定植生物的生态位pH <4.5。细胞分裂、细胞壁和蛋白质生物合成基因也有所增加。初步数据显示，PPI的酸抑制作用将前一组的表达降低到体外pH值为4.5时的水平，但增加了后三组生长相关基因的表达，这可能解释了PPI与生长依赖性抗生素联合治疗三联疗法的必要性。这些数据可能导致长效PPI +阿莫西林的双重治疗；(C)研究ph诱导的内膜上脲酶复合物和其他蛋白质的激活和运输，并确定这是否由HP0165或HP0244调节。幽门螺杆菌表达脲酶（约占总蛋白的10%）是胃感染所必需的。然而，在中性pH下，只有1/3的脲酶具有活性，2/3以失活的脱酶形式存在。ph依赖性的脱酶激活将提供比从头合成更快速的酸反应。初步结果表明，在酸性pH下，脲酶的活化和易位依赖于HP0165。UreI作为膜锚，用于pH依赖性的脲酶向内膜的重新定位，这是激活脲酶所必需的。本研究可能为改善根除治疗提供新的线索，从而降低消化性溃疡疾病和胃癌的风险。公共卫生相关性：幽门螺杆菌可导致消化性溃疡，并使胃癌风险增加40倍。我们将通过研究胃pH调节基因的信号系统以及脲酶转运和激活在感染中的作用来分析胃中幽门螺杆菌的生理学。更好地了解酸对幽门螺杆菌的抑制作用可以改进或替代三联疗法。

DESCRIPTION (provided by applicant): The aims are to investigate the gastric physiology of the gastric pathogen Helicobacter pylori. Specific Aims: (A). Identify the acid response regulon and signaling system of the cytoplasmic pH sensor. HP0244 is a previously unsuspected sensor of cytoplasmic pH. Using transcriptome analysis after pH 2.5 incubation, the HP0244, HP0703 independent, regulon will be identified to separate periplasmic (HP0165) from cytoplasmic pH) regulation and confirmed by qPCR; (B) Identify colonization dependent gene expression and evaluate pH control of their expression by comparative transcriptome analysis of H. pylori from infected gerbils with and without acid suppression. Transcriptome analysis of H. pylori infecting the gerbil stomach compared to in vitro cultured H. pylori showed a greater up-regulation of genes encoding proteins involved in acid acclimation than at pH 4.5 in vitro, likely reflecting a pH <4.5 in the niche of the colonizing organisms. Cell division, wall and protein biosynthesis genes were also increased. Preliminary data show that acid inhibition by a PPI reduces expression of the former group to the level found at pH 4.5 in vitro but augments expression of the latter three groups of growth-related genes, this may explain the need for a combination of a PPI with growth-dependent antibiotics for triple therapy. These data may lead to dual therapy with a long acting PPI + amoxicillin; (C) Investigate pH-induced activation and trafficking of a urease complex and other proteins to UreI on the inner membrane and determine whether this is regulated by HP0165 or HP0244 The expression of urease by H. pylori (~10% of total protein) is essential for gastric infections. However, at neutral pH, only 1/3rd of urease is active, 2/3rd is present as inactive apoenzyme. pH-dependent activation of the apoenzyme would provide a more rapid response to acid than de novo synthesis. Preliminary results suggest that there is activation and translocation of urease at acidic pH that is dependent on HP0165. UreI serves as the membrane anchor for the pH- dependent relocation of urease to the inner membrane and this is required for activation of apourease. This research may provide new leads for improvement eradication therapy thereby decreasing the risk of peptic ulcer disease and gastric cancer. PUBLIC HEALTH RELEVANCE: Helicobacter pylori is responsible for peptic ulcers and a fortyfold increased risk of gastric cancer. We shall analyze the physiology of H. pylori in the stomach by investigating signaling systems for genes regulated by gastric pH and the role of urease trafficking and activation in infection. A better understanding of effects of acid inhibition on H. pylori may allow improvement or replacement of triple therapy for eradication.