Targeting Hsp90 in cryptococcal fungal pathogenesis

项目摘要/摘要 医学相关微生物的内在和获得性耐药性对人类构成严重威胁 并在世界范围内产生巨大的经济后果。真菌病原体呈现出一种特殊的 挑战，因为它们是真核生物，与人类宿主分享许多相同的生物学过程 他们会传染。最普遍的真菌病原体是隐球菌，它会引起 每年有60万人死亡。隐球菌性脑膜炎是该病的主要临床表现，其发病率为100%。 如果不治疗，死亡率。即使有最好的治疗方法，死亡率仍高达35-40%。 因为在真菌中具有不同靶点的药物类别的数量非常有限，而 目前的抗真菌药物要么受到剂量限制的寄主毒性的影响，要么经常出现高... 等级电阻。迫切需要用于治疗干预的新的、无交叉反应的靶点。 在以前的工作中，我们发现分子伴侣Hsp90调节耐药性和 真菌念珠菌和曲霉的致病力。在这些病原体中靶向Hsp90有望 为提高抗真菌药物的疗效和消除耐药性提供了一个强有力的战略，但 Hsp90在致病隐球菌种中的作用尚不清楚。热休克蛋白90的“可药性”一直是 被许多小分子靶向这种蛋白质用于治疗人类癌症而建立起来的。这个 然而，在真菌感染的背景下，目前可用的药物的抗真菌活性较差并且可能具有毒性， 要求开发对真菌具有选择性的Hsp90抑制剂。 为了追求真菌选择性的目标，我们的跨学科团队解决了N-末端结构域的结构 发现白色念珠菌Hsp90的核苷酸结合区有一个口袋比它的 与人类相似，并在隐球菌中保守。在这种洞察的指导下，我们设计、合成和 表征了两种真菌Hsp90的先导抑制剂，其选择性是人类蛋白质的10倍。现在, 利用我们开发的基于化学和结构的新设计方法，我们将使用我们的 真菌生物学(考恩)、化学(布朗)和药理学/实验专业的互补专业知识 Treateutics(Whitesell)将对更多类似物库进行结构活性关系(SAR)研究 并产生选择性的类药物探针。这些基因将被用于基因和基因的强大组合 Hsp90‘S在隐球菌耐药性和毒力中作用的药理学研究在……里面 除了将获得的重要的基本见解外，我们的结果可能会影响对 在不久的将来侵袭性真菌感染为药物开发提供了有希望的线索 在一个完全未被开发的目标空间工作的候选人。

Project Summary/Abstract Intrinsic and acquired drug resistance of medically relevant microorganisms poses a grave threat to human health and has enormous economic consequences worldwide. Fungal pathogens present a particular challenge because they are eukaryotes and share many of the same biological processes as the human hosts they infect. Among the most pervasive fungal pathogens are species of Cryptococcus, which cause over 600,000 deaths per year. Cryptococcal meningitis, the major clinical manifestation of the disease, has a 100% mortality rate if left untreated. Even with the best available therapies, mortality rates remain high at 35-40% because the number of drug classes that have distinct targets in fungi is very limited and the usefulness of current antifungal drugs is compromised by either dose-limiting host toxicity or the frequent emergence of high- grade resistance. New, non-cross-reactive targets for therapeutic intervention are urgently needed. In previous work, we discovered that that the molecular chaperone Hsp90 regulates drug resistance and virulence in species of the fungi Candida and Aspergillus. Targeting Hsp90 in these pathogens promises to provide a powerful strategy to enhance the efficacy of antifungal drugs and abrogate drug resistance, but the role of Hsp90 in pathogenic cryptococcal species remains unexplored. The “druggability” of Hsp90 has been well established by the many small molecules targeting this protein for the treatment of human cancers. The poor antifungal activity and likely toxicity of currently available drugs in the setting of fungal infection, however, demand the development of fungal-selective Hsp90 inhibitors. To pursue the goal of fungal selectivity, our interdisciplinary team solved the structure of the N-terminal domain of Candida albicans Hsp90, and identified a pocket in the nucleotide-binding region that is larger than its human counterpart and is conserved in Cryptococcus. Guided by this insight, we designed, synthesized and characterized two lead inhibitors of fungal Hsp90 with >10-fold selectivity relative to the human protein. Now, leveraging the novel chemistry and structure-based design approach we have developed, we will use our complementary expertise in fungal biology (Cowen), chemistry (Brown), and pharmacology/experimental therapeutics (Whitesell) to pursue structure activity relationship (SAR) studies on libraries of additional analogs and generate selective drug-like probes. These will be used in a powerful combination of genetic and pharmacological approaches to dissect Hsp90's role in the drug resistance and virulence of Cryptococcus. In addition to the important basic insights that will be obtained, our results are likely to impact the treatment of invasive fungal infections in the near future by providing promising leads for the development of drug candidates that operate in a completely unexploited target space.