Characterization of Potassium Channels in the Human Parasite Trypanosoma Cruzi

人类寄生虫克氏锥虫钾通道的表征

• 批准号: 8665023
• 负责人: Veronica Jimenez
• 金额: $ 24.66万
• 依托单位: CALIFORNIA STATE UNIVERSITY FULLERTON
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-18 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8665023
• 关键词: Ablation; Benznidazole; Blood Circulation; Calcium-Activated Potassium Channel; Cell Proliferation Regulation; Cell membrane; Cell physiology; Cells; Chagas Disease; Complement; Complex; Congestive Heart Failure; Disease; Electrodes; Environment; Epidemiology; FDA approved; Feces; Financial compensation; Heart Diseases; Homologous Gene; Human; Immigration; Immunofluorescence Immunologic; Insect Vectors; Insecta; Ion Channel; Ions; Kidney; Knock-out; Laboratories; Latin America; Life; Life Cycle Stages; Light; Lipids; Liposomes; Maintenance; Membrane; Membrane Potentials; Modification; Molecular; Molecular Profiling; Nifurtimox; Oocytes; Osmolar Concentration; Osmoregulation; Parasites; Pathology; Pharmaceutical Preparations; Physiological; Play; Potassium Channel; Poverty; Process; Property; Proteins; Regulation; Role; Site; Site-Directed Mutagenesis; Staging; Stress; Trypanosoma cruzi; Urine; Work; Xenopus laevis; abstracting; cellular imaging; coping; environmental change; extracellular; genetic manipulation; gutted vector; in vivo; inward rectifier potassium channel; mitochondrial membrane; new therapeutic target; overexpression; patch clamp; reconstitution; response; rural area; success; therapeutic target; vector; voltage clamp

Abstract Chagas disease is a zoonotic tropical pathology, caused by the protozoan parasite Trypanosoma cruzi. Endemic en Latin America, it is one of the leading causes of congestive heart failure in the world. Historically associated with poverty in rural areas, immigration and relocation of the vectors are changing the epidemiology of the disease, as evidenced by a substantial increase in the number of cases in the US. Treatment is restricted to nifurtimox and benznidazole, both of which are relatively toxic, have limited efficacy and are not approved by the FDA. Our laboratory has been working on the rational search for chemotherapeutic treatments for Chagas disease that can selectively target the parasite without compromising human cells. Ion channels are potential targets for selective drugs against a broad range of diseases because they are responsible for essential cellular functions like plasma membrane and mitochondrial membrane potential maintenance, pH regulation, cell proliferation, and adaptation to environmental changes including osmoregulation. During its life cycle, the parasite encounters extreme fluctuations in ionic concentrations, osmolarities and pHs. Previous studies in our laboratory suggested that in T. cruzi, K+ channels are important components of the regulatory mechanisms that maintain the plasma membrane potential, intracellular pH and osmolarity. It has also been demonstrated that trypomastigotes, the infective forms of the parasite, are particularly sensitive to changes in extracellular K+ concentration while epimastigotes and amastigotes are less responsive to this ion. In T. cruzi, we have identified sequences encoding for putative inward rectifier (TcKir) and calcium-activated K+ channels (TcCAKC). They have conserved functional domains, but limited identity with human homologs (<15%) making them potential selective pharmacological targets against the parasite. We propose that ion channels play an important role in sensing and adaptation to environmental conditions in T. cruzi. We propose that different types of K+ channels integrate a homeostatic network that allows the parasite to detect and respond to changes in osmotic and ionic conditions. Fundamental processes like differentiation and invasion can be regulated by modification of the ionic concentrations determining the success of the parasite in infecting new hosts. Analysis of T. cruzi potassium channels expression profiles and localization, complemented with electrophysiological studies will shed light about how these proteins work. Genetic manipulation of the level of expression and phenotypic analysis in vivo will demonstrate the physiological role of potassium channels in the parasite and will help to establish their potential as therapeutic targets.

摘要 恰加斯病是一种人畜共患的热带病理学，由原生动物寄生虫克氏锥虫引起。 它是拉丁美洲的地方病，是世界上充血性心力衰竭的主要原因之一。历史上 与农村地区的贫困有关，病媒的移民和迁移正在改变流行病学， 这种疾病的发病率，美国的病例数量大幅增加就是证明。治疗是 仅限于硝呋替莫和苄硝哒唑，这两种药物都相对有毒，疗效有限， 经FDA批准。我们的实验室一直致力于寻找合理的化学治疗方法 可以选择性地针对寄生虫而不损害人体细胞。离子通道 是针对广泛疾病的选择性药物的潜在靶点，因为它们负责 基本的细胞功能，如质膜和线粒体膜电位维持，pH 调节、细胞增殖和对环境变化的适应，包括细胞增殖调节。于计划有效期内 在循环中，寄生虫遇到离子浓度、渗透压和pH的极端波动。 本实验室以前的研究表明，在T。cruzi，K+通道是重要的组成部分， 维持质膜电位、细胞内pH和渗透压的调节机制。它有 也被证明，锥鞭毛体，寄生虫的感染形式，特别敏感， 细胞外K+浓度的变化，而上鞭毛体和无鞭毛体对该离子的反应较低。 于T. cruzi，我们已经确定了编码推定的内向整流（TcKir）和钙激活K+的序列 通道（TcCAKC）。它们具有保守的功能结构域，但与人类同源物的同一性有限 （<15%），使它们成为对抗寄生虫的潜在选择性药理学靶标。我们建议离子 通道在T.克鲁兹我们提出 不同类型的K+通道整合了一个稳态网络，使寄生虫能够检测和 对渗透压和离子条件的变化作出反应。分化和侵入等基本过程 可以通过改变决定寄生虫感染成功的离子浓度来调节 新的宿主分析了T. cruzi钾通道表达谱和定位，补充 电生理学研究将揭示这些蛋白质的工作原理。基因操纵的水平 在体内的表达和表型分析将证明钾通道在细胞内的生理作用。 寄生虫，并将有助于建立其作为治疗靶点的潜力。