Cholesterol Uptake by Cryptosporidium

隐孢子虫摄取胆固醇

• 批准号: 7878850
• 负责人: Isabelle Coppens
• 金额: $ 24.35万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-25 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7878850
• 关键词: 3-hydroxy-3-methylglutaryl-coenzyme A; AIDS/HIV problem; ATP-Binding Cassette Transporters; Abbreviations; Acquired Immunodeficiency Syndrome; Amino Acids; Binding; Biological Models; Brush Border; Cell membrane; Cells; Cholesterol; Cholesterol Esters; Cholesterol Homeostasis; Collection; Complement component C1s; Complex; Cryptosporidiosis; Cryptosporidium; Cytoplasm; Data; Development; Disease; Drug Delivery Systems; Drug resistance; Endocytosis; Endoplasmic Reticulum; Ensure; Enterocytes; Environment; Epithelial; Epithelial Cells; Excision; Exhibits; Gastrointestinal tract structure; Genes; Goals; Growth; Homologous Gene; Immunocompromised Host; Individual; Infection; Intake; Intercept; Intestines; Invaded; Life; Light; Lipids; Lipoproteins; Location; Low Density Lipoprotein Receptor; Low-Density Lipoproteins; Mammalian Cell; Mammals; Membrane; Modification; Molecular; Movement; Nature; Nuclear Pore Complex; Nucleotides; Nutrient; Oocysts; Opportunistic Infections; Organelles; Organism; Parasites; Pathogenicity; Pathway interactions; Patients; Plasma; Plasmodium; Proteins; Relative (related person); Reliance; Reproduction; Resources; Role; Serum; Site; Small Intestines; Source; Sporozoites; Staging; Starvation; Steroids; Sterol O-Acyltransferase; Sterols; Surface; Thin Layer Chromatography; Toxoplasma gondii; Vacuole; Water; base; chemotherapy; cholesterol absorption; cholesterol biosynthesis; cholesterol trafficking; citrate carrier; dehydroergosterol; drug standard; experience; extracellular; inter-alpha-inhibitor; intraepithelial; meetings; microbial; novel; novel strategies; oxysterol binding protein; parasite genome; pathogen; permease; public health relevance; receptor mediated endocytosis; stem; uptake

DESCRIPTION (provided by applicant): Cryptosporidiosis is universally recognized as one of the most serious opportunistic infections that complicates AIDS. Cryptosporidium infection begins with microbial invasion of small intestinal epithelial cells (enterocytes), in which the parasite creates a peculiar niche that sequesters itself from the intestinal lumen and the host cell's cytoplasm. After amplification, endogenous parasites escape from the parasitophorous vacuole and spread throughout the epithelial surfaces of the gastrointestinal tract. No consistently reliable chemotherapy is available for the treatment of cryptosporidiosis. The need for identifying novel drug targets is imperative. Interactions of Cryptosporidium with enterocytes remain poorly characterized. Undeniably, this parasite must depend on various host cell resources since it has lost the ability to synthesize most basic metabolites. We demonstrated that Cryptosporidium developing in enterocytes contains significant amounts of cholesterol though it lacks the genes for cholesterol biosynthesis and modification. The parasite critically relies on host cholesterol for normal development since removal of cholesterol either from the medium or host cell intracellular pools, arrests its reproduction. Our overall goal is to decipher the mechanism/s for host cholesterol acquisition by Cryptosporidium. We hypothesize that the choice of enterocytes as the major sites for parasite replication may stem from the unique cholesterol transport and synthesis activities of these cells. Cryptosporidium must be equipped to intercept host cholesterol, either provided exogenously by the plasma and/or the gut, or synthesized in enterocytes. Specific Aim 1 will define the preferential source of host derived-cholesterol for Cryptosporidium and analyze the mechanisms of cholesterol delivery from the host enterocyte to the PV. We will investigate the contribution of i) the plasma low-density lipoprotein receptor-mediated endocytosis, ii) the micellar cholesterol absorption by the permease Niemann-Pick C1-like 1, and iii) the cholesterol biosynthetic pathway, to parasite growth. We documented the presence of sterols on the parasite's plasma membrane and organelles indicating that Cryptosporidium is able to internalize host cholesterol to its cell interior. Specific Aim 2 will decipher the molecular machinery developed by Cryptosporidium to transport cholesterol from the parasite surface to organelles. We will focus on the characterization of two classes of surface-exposed sterol transporters, the ATP-binding cassette G1 transporter and Niemann-Pick C1 protein present in the parasite, for cholesterol trafficking. Our long-term objective is to provide novel approaches to treat cryptosporidiosis, based on blocking the parasite's intracellular development through cholesterol starvation. Exploration of the peculiarities of cholesterol uptake by Cryptosporidium will expose new vulnerabilities. Cryptosporidium may also provide a useful model system for throwing light on cholesterol homeostatic and dysregulatory pathways in mammalian enterocytes. PUBLIC HEALTH RELEVANCE: Cryptosporidium is one of the most troublesome agents of water-borne disease that cause life-threatening disease in HIV/AIDS patients. This parasite develops inside intestinal epithelial cells where it remains protected from the hostile gut environment and is supplied with host nutrients. We will study the mechanisms by which the parasite scavenges host cholesterol, in order to specifically interfere with the pathogen's supply of this essential lipid, thereby causing its growth arrest through starvation.

描述（由申请人提供）：隐孢子虫病被普遍认为是使AIDS复杂化的最严重的机会性感染之一。隐孢子虫感染始于小肠上皮细胞（肠上皮细胞）的微生物侵袭，其中寄生虫会产生一个特殊的壁ne，从肠道和宿主细胞的细胞质中隔离。放大后，内源性寄生虫从寄生虫液泡中逸出，并散布在胃肠道的整个上皮表面。没有一贯可靠的化学疗法可用于治疗隐孢子虫病。必须确定新型药物靶标的需求。隐孢子虫与肠上皮细胞的相互作用仍然很差。不可否认，该寄生虫必须取决于各种宿主细胞资源，因为它失去了合成大多数基本代谢物的能力。我们证明，肠上皮细胞中发育的隐孢子虫含有大量胆固醇，尽管它缺乏胆固醇生物合成和修饰的基因。自从培养基或宿主细胞内池去除胆固醇以来，寄生虫依靠宿主胆固醇来正常发育，使其繁殖。我们的总体目标是解读Cryptosporidium宿主胆固醇的机制。我们假设选择肠细胞作为寄生虫复制的主要部位可能源于这些细胞的独特胆固醇转运和合成活性。隐孢子虫必须配备以拦截宿主胆固醇，要么由血浆和/或肠外源提供，要么在肠上皮细胞中合成。特定的目标1将定义用于隐孢子虫的宿主衍生胆固醇的优先来源，并分析从宿主肠肠细胞到PV的胆固醇递送的机制。我们将研究I）i）血浆低密度脂蛋白受体介导的内吞作用，ii）粘酶niemann-pick niemann-pick c1 like 1，以及iii）胆固醇生物合成途径，以寄生虫生长。我们记录了寄生虫的质膜上存在固醇，并表明隐孢子虫能够将宿主胆固醇内化到其细胞内部。特定的目标2将破译由隐孢子虫开发的分子机制，可将胆固醇从寄生虫表面运输到细胞器。我们将重点介绍两类暴露于表面暴露的固醇转运蛋白，即寄生虫中存在的ATP结合盒G1转运蛋白和Niemann-Pick C1蛋白，用于胆固醇运输。我们的长期目标是基于通过胆固醇饥饿来阻止寄生虫的细胞内发育，提供新颖的方法来治疗隐孢子虫病。探索隐孢子虫的胆固醇吸收特征将暴露新脆弱性。隐孢子虫还可以提供一个有用的模型系统，以阐明哺乳动物肠细胞中的胆固醇稳态和失调途径。公共卫生相关性：隐孢子虫是最麻烦的水传播疾病药物之一，引起艾滋病毒/艾滋病患者的威胁生命的疾病。该寄生虫在肠道上皮细胞内发展，并在其中保护侵害肠道环境，并提供宿主营养素。我们将研究寄生虫清除宿主胆固醇的机制，以特别干扰病原体的这种必需脂质的供应，从而通过饥饿引起其生长停滞。