Deciphering the Candida albicans Hsp90 Kinase Interactome and Elucidating its Role in Fungal Virulence

该项目旨在为人类主要真菌病原体白色念珠菌提供新的治疗方法。除了常见的非致命性感染外，英国每年还有数百人死于由这种酵母菌引起的血液和器官感染。它威胁到那些免疫防御已经因癌症化疗、艾滋病、手术或出生体重过低而减弱的患者。一旦念珠菌通过血液传播，就极难治疗，因为它会迅速对现有药物产生耐药性。耐药的出现是由热休克蛋白90 （Hsp90）促进的，它稳定了其他蛋白质，从而促进了它们的激活。Hsp90与Cdc37合作。它们一起瞄准信号传递蛋白，也就是所谓的激酶。Hsp90/Cdc37复合物及其靶激酶在所有细胞的正常生理中起重要作用。但有时，Hsp90会误入歧途。例如，它稳定了人类的癌症蛋白，促进了酵母的耐药性。这两个例子都表明，降低Hsp90可能有助于对抗癌症和酵母菌感染。事实上，降低Hsp90功能的药物目前正在作为抗癌药物进行测试。不幸的是，人类和酵母的Hsp90非常相似。这意味着，仅降低酵母菌Hsp90而不是人类Hsp90来治愈危及生命的酵母菌感染是非常困难的。动物模型表明，降低酵母菌Hsp90与治疗酵母菌感染本身的药物联合使用会产生严重的副作用。我们将通过研究Hsp90/Cdc37及其相关激酶在酵母中的作用来解决这个问题，以了解它们如何促进酵母引起危及生命的感染的能力。具体来说，我们的目标是进一步提高我们对酵母特有的激酶的理解，这些激酶依赖于Hsp90作为未来的药物靶点。用药物靶向酵母的特定成分应该可以预防或至少大大减少患者的副作用。我们之前的研究表明，在酵母细胞中减少Hsp90也会导致酵母细胞死亡。这可能是开发新药和治疗策略的一个有希望的方法。特别是降低Hsp90的药物已经作为抗癌药物进入临床试验。我们进一步证明了一些激酶调节Hsp90和Cdc37，而许多其他激酶依赖于Hsp90/Cdc37的稳定性和激活。然而，对白色念珠菌中Hsp90/Cdc37激酶信号传导模块的了解很少。本项目将通过三组实验研究调节Hsp90/Cdc37复合物的激酶和依赖于Hsp90/Cdc37的激酶。首先，我们将确定特定的激酶如何调节Hsp90和Cdc37，以及Hsp90/Cdc37的哪些部分确实是酵母引起疾病所必需的。其次，我们将重点关注酵母特异性激酶，研究它们在酵母菌感染中的作用，以了解哪些激酶是最重要的，可以成为最佳的药物靶点。第三，我们将在酵母基因组中寻找更多依赖于Hsp90的激酶，以扩大潜在药物靶点的范围。科学家和病人将从我们的研究中受益。在短期内，生物学家将能够将我们对Hsp90/Cdc37激酶回路的了解转化为他们在其他真菌或微生物中研究的致病机制。结构生物学家可以结晶有希望的激酶来阐明其结构，这是药理学家开发药物的先决条件。由于Hsp90在许多生物过程中起着重要作用，我们的结果可以用于研究遗传学，癌症生物学和微生物学的科学家。我们研究的长期受益者将是英国和全世界患有酵母菌感染的患者，因为我们的研究可能会导致新药的开发，以征服危及生命的酵母菌感染。

This project aims to inform new treatments for Candida albicans, the leading fungal pathogen of humans. Aside from the common nonlethal infections, several hundred people die in the UK every year of bloodstream and organ infections caused by this yeast. It threatens patients whose immune defenses are already weakened from cancer chemotherapy, HIV/AIDS, surgery or by extremely low birth weight. Once Candida has spread through the bloodstream, it is extremely difficult to treat because it quickly develops resistance to currently available drugs. The emergence of drug resistances is facilitated by the heat shock protein 90 (Hsp90), which stabilizes other proteins, thus contributing to their activation.Hsp90 collaborates with Cdc37. Together they target signal transmitting proteins, so called kinases. The Hsp90/Cdc37 complex and its target kinases play an important role in the normal physiology of all cells. Sometimes though, Hsp90 goes astray. For example when it stabilizes cancer proteins in humans and promotes drug resistance in yeast. Both examples suggest that reducing Hsp90 may help fight cancer and yeast infections. Indeed, drugs reducing Hsp90 function are currently tested as anti-cancer drugs. Unfortunately though, human and yeast Hsp90 are very similar. This means, it is very difficult to reduce only yeast Hsp90 but not human Hsp90 to cure a life-threatening yeast infection. Animal models showed that reducing yeast Hsp90 in combination with drugs treating the yeast infection itself caused severe side effects.We will address this problem by investigating the role of Hsp90/Cdc37 and their associated kinases in yeast to understand how they contribute to the yeast's ability to cause life-threatening infections. Specifically, we aim to further advance our understanding of those kinases that are unique to yeast and that depend on Hsp90 as future drug targets. Targeting yeast specific components with a drug should prevent or at least drastically reduce side effects in patients.We previously showed that reducing Hsp90 in yeast cells that also lack one kinase causes yeast cell death. This could be a promising approach for the development of new drugs and treatment strategies. Especially since Hsp90 reducing drugs are already in clinical trial as anti-cancer drugs. We furthermore demonstrated that some kinases regulate Hsp90 and Cdc37, while many others depend on the Hsp90/Cdc37 for stability and activation. Yet, knowledge of the Hsp90/Cdc37 kinase signaling module is sparse in C. albicans.This project will examine the kinases that regulate the Hsp90/Cdc37 complex and the kinases that depend on Hsp90/Cdc37 by conducting three sets of experiments. First, we will determine how specific kinases regulate Hsp90 and Cdc37 and which parts of Hsp90/Cdc37 are indeed necessary for yeasts to cause disease. Second, we will focus on yeast specific kinases and study their role in yeast infections to understand, which is the most important kinase that would make the best drug target. Third, we will search the yeast genome for more kinases that depend on Hsp90 to widen the field of potential drug targets.Scientists and patients will benefit from our research. In the short-term, biologists will be able to translate our knowledge of the Hsp90/Cdc37 kinase circuitry to the disease-causing mechanisms they study in other fungi or microbes. Structural biologists could crystallize promising kinases to elucidate their structure, which is a prerequisite for drug development by pharmacologists. Since Hsp90 plays an important role in a number of biological processes, our results could be used by scientists investigating genetics, cancer biology, and microbiology. The long-term beneficiaries of our research will be patients in the UK and world-wide that suffer from yeast infections as our research could potentially lead to the development of new drugs to conquer life-threatening yeast infections.