DESIGNING SELECTIVE INHIBITORS OF CALCIUM-DEPENDENT KINASES IN PARASITES

描述(申请人提供)：弓形虫和微小隐孢子虫是重要的机会性病原体，在免疫功能低下的人类中会导致毁灭性的疾病。这两种病毒都能引起食物或水传播的感染，因此也对健康的人构成威胁。弓形虫的严重感染通常发生在免疫功能低下的患者中，包括艾滋病毒感染、癌症化疗、器官移植或在宫内感染的婴儿。此外，新的研究表明，严重的眼病也可能发生在健康的成年人身上。隐孢子虫还会在免疫功能低下的患者中引起严重的腹泻疾病，由于缺乏有效的治疗方法，治疗受到阻碍。众所周知，隐孢子虫还会由于受污染的家庭供水而在健康人中引起广泛的衰弱疾病暴发。这些寄生虫引起的感染的治疗因缺乏有效药物和/或对现有药物不耐受而变得复杂。因此，有必要开发新的治疗药物来治疗这些寄生虫的感染。我们项目的目标是开发属于钙依赖蛋白激酶(CDPK)家族的寄生虫特异性蛋白激酶的小分子抑制剂。CDPKs是一种类似植物的蛋白激酶，在动物细胞中没有发现，但它们可以在顶端复合体寄生虫中扩展。我们最近利用分子遗传学和化学生物学方法进行的研究表明，CDPK1对寄生虫的生长是必不可少的。我们还证明了CDPK1可以被体积庞大的ATP类似物特异性和有效地抑制，这些类似物对宿主激酶的活性有限。我们将利用生化、分子遗传学、化学生物学和药物化学相结合的方法，寻找具有更强选择性抑制弓形虫和微小弧菌CDPK1活性的改进的抑制剂。我们还将设计、合成和测试具有更好药理特性的新抑制剂，用于体内治疗。在弓形虫病的啮齿动物模型中，将评估选择性抑制剂预防急性和慢性感染的能力。

DESCRIPTION (provided by applicant): Toxoplasma gondii and Cryptosporidium parvum are important opportunistic pathogens that cause devastating disease in immunocompromised humans. Both are capable of causing food or waterborne infections and hence are also a threat to healthy individuals. Severe infections with T. gondii typically occur in immunocompromised patients, including HIV infection, cancer chemotherapy, organ transplant, or infants infected in utero. Additionally, new studies indicate that severe ocular disease can also occur in healthy adults. Cryptosporidium also causes severe diarrheal disease in immunocompromised patients and treatment is hampered by the lack of effective therapy. Cryptosporidium has also been known to cause widespread outbreaks of debilitating illness in healthy individuals due to contaminated domestic water supplies. Treatment of infections caused by these parasites is complicated by lack of effective medicines and/or intolerance to currently available drugs. Hence, there is a need to develop new therapeutic agents to treat infections with these parasites. The goal of our project is to develop small molecule inhibitors of parasite-specific kinases belonging to the calcium-dependent protein kinase (CDPK) family. CDPKs are plant-like protein kinases that are not found in animal cells, yet they are expanded in apicomplexan parasites. Our recent studies using molecular genetic and chemical biology approaches reveal that CDPK1 is essential for parasite growth. We have also demonstrated that CDPK1 is specifically and potently inhibited by bulky ATP analogs, which have limited activity against host kinases. We will pursue identification of improved inhibitors with greater potency for selective inhibition of CDPK1 from T. gondii and C. parvum using a combination of biochemical, molecular genetic, chemical biology and medicinal chemistry approaches. We will also design, synthesize, and test new inhibitors with improved pharmacological properties for in vivo treatment. Selective inhibitors will be evaluated for their ability to prevent acute and chronic infection in a rodent model for toxoplasmosis.