Investigating the Cytsolic Heme Pool in P. falciparum

研究恶性疟原虫胞质血红素池

• 批准号: 6915712
• 负责人: JACQUIN C NILES
• 金额: $ 5.15万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6915712
• 关键词: Plasmodium falciparum; SDS polyacrylamide gel electrophoresis; chloroquine; cytoplasm; drug resistance; heme; host organism interaction; malaria; oligonucleotides; pathologic process; peptide library; polymerase chain reaction; postdoctoral investigator; protein binding; protein degradation; protein structure function

DESCRIPTION (provided by applicant): During malarial infection by Plasmodium falciparum, significant, amounts of hemoglobin are degraded by the intraerythrocytic parasite in a specialized food vacuole. The released amino acids are utilized to support growth, but heme is mostly detoxified to hemozoin in the food vacuole. However, it is unclear how much heme partitions to the parasite's cytosol, and the role it plays in parasite physiology. Furthermore, chloroquine, a commonly used anti-malarial drug has been suggested to increase cytosolic heme flux, but this has not been proven. We will address these issues by using a functional approach rather than mass balance measurements that are prone to large errors in biological systems. Our goals are to (1) develop high affinity RNA aptamers to heme using SELEX, and, (2) introduce them into P. falciparum, and determine their impact on parasite survival in the presence and absence of chloroquine. The aptamers are expected to be cytosolic given their negative charge, and should not interfere with heme polymerization in the food vacuole, thus providing a tool to selectively investigate the heme pool in the cytosol. These studies are important to advance our understanding of how P. falciparum disposes and/or utilizes host-derived heme, and to specifically investigate a potential mechanism by which the commonly used anti-malarial drugs exert their toxicity. Resistance to chloroquine is becoming increasingly widespread, and occurs via efflux mechanisms that prevent drug accumulation within the parasite. If parasite survival is intricately associated with the status of a physiologic cytosolic heme pool, this may represent another drug development target that circumvents the known resistance mechanism.

描述（由申请人提供）：在恶性疟原虫感染疟疾期间，特殊食物泡中的红细胞内寄生虫会降解大量血红蛋白。释放的氨基酸用于支持生长，但血红素大部分在食物泡中被解毒成疟原虫色素。然而，尚不清楚有多少血红素分配到寄生虫的细胞质中，以及它在寄生虫生理学中发挥的作用。此外，常用的抗疟疾药物氯喹被认为可以增加细胞质血红素通量，但这尚未得到证实。我们将通过使用功能方法而不是生物系统中容易出现较大误差的质量平衡测量来解决这些问题。我们的目标是 (1) 使用 SELEX 开发血红素高亲和力 RNA 适体，以及 (2) 将它们引入恶性疟原虫中，并确定它们在存在和不存在氯喹的情况下对寄生虫生存的影响。考虑到其带负电荷，适配体预计位于细胞质中，并且不应干扰食物液泡中的血红素聚合，从而提供选择性研究细胞质中血红素池的工具。这些研究对于增进我们对恶性疟原虫如何处理和/或利用宿主来源的血红素的理解，以及专门研究常用抗疟疾药物发挥毒性的潜在机制非常重要。对氯喹的耐药性正变得越来越普遍，这种耐药性是通过防止寄生虫体内药物积累的外排机制而发生的。如果寄生虫的存活与生理胞质血红素库的状态错综复杂地相关，那么这可能代表绕开已知耐药机制的另一个药物开发目标。