Mapping the Hsp90 Genetic Network Reveals Ergosterol Biosynthesis and Phosphatidylinositol-4-Kinase Signaling as Core Circuitry Governing Cellular Stress.
Mapping the Hsp90 Genetic Network Reveals Ergosterol Biosynthesis and Phosphatidylinositol-4-Kinase Signaling as Core Circuitry Governing Cellular Stress.
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DOI：
10.1371/journal.pgen.1006142
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发表时间：
2016-06
期刊：
影响因子：
4.5
通讯作者：
Cowen LE
中科院分区：
文献类型：
--
作者：
O'Meara TR;Veri AO;Polvi EJ;Li X;Valaei SF;Diezmann S;Cowen LE
白色念珠菌是一种主要的人类真菌病原体，会导致危及生命的系统性感染。白念珠菌应激反应、耐药性、形态发生和毒力的关键调节因子是分子伴侣Hsp90。靶向Hsp90为治疗真菌感染提供了一种强有力的策略，然而，由于抑制宿主Hsp90，目前的抑制剂的治疗作用受到毒性的影响。为了确定控制毒力和耐药性的Hsp90依赖电路的成分，这些成分足够不同，可以在病原体中选择性靶向，我们率先在白色念珠菌中建立了Hsp90遗传网络的化学基因组图谱。在这里，我们筛选覆盖约10%的基因组的突变集合，以在多种环境条件下对Hsp90抑制超敏。我们确定了158个HSP90化学遗传相互作用因子，其中大多数只有在特定环境中才对生长重要。我们发现，固醇C-22去饱和酶基因ERG5和磷脂酰肌醇-4-激酶(PI4K)基因STT4在多种条件下是HSP90的遗传交互作用，提示HSP90的上游有功能。通过对麦角甾醇生物合成级联反应的系统分析，我们证明了麦角甾醇生物合成缺陷引起的细胞应激超过了热休克蛋白90的S的功能能力。通过对磷脂酰肌醇途径的分析，我们证明了PI4K Stt4和Hsp90之间存在遗传相互作用。我们还通过对Wal1的调节建立了正常的肌动蛋白极化所必需的Stt4，并提出了一个模型，在该模型中，肌动蛋白重塑的缺陷引发了压力，从而产生了超过其功能能力的细胞对Hsp90的需求。与这一模型一致，肌动蛋白抑制剂与Hsp90抑制剂具有协同作用。我们强调了Hsp90和毒力特征之间的新联系，证明了Erg5和Stt4能够激活巨噬细胞下垂。这项工作揭示了调控Hsp90功能容量的新电路和调控耐药性、形态发生和毒力的新效应器，揭示了抗真菌药物开发的新靶点。HSP90是一种必需的和保守的分子伴侣，在许多客户蛋白的折叠和功能中都是必需的，特别是那些参与信号和应激反应的蛋白。在人类真菌病原体白色念珠菌中，Hsp90控制着耐药性、形态发生和毒力。在我们之前的分析中，我们开发了一种化学基因组方法来定位白色念珠菌的HSP90化学遗传网络，这种生物的传统遗传方法由于缺乏完整的性循环而受到阻碍。在这里，我们确认了白色念珠菌中Hsp90遗传网络的环境偶然性，确定了新的遗传相互作用，并展示了调节细胞中Hsp90功能容量的新电路。在传染病治疗的背景下，避免宿主毒性和实现特异性的挑战在于开发病原体选择性Hsp90抑制剂或识别Hsp90控制毒力的回路的病原体特定成分。这项工作为人类的主要真菌病原体提供了对这种电路的洞察。
Candida albicans is a leading human fungal pathogen that causes life-threatening systemic infections. A key regulator of C. albicans stress response, drug resistance, morphogenesis, and virulence is the molecular chaperone Hsp90. Targeting Hsp90 provides a powerful strategy to treat fungal infections, however, the therapeutic utility of current inhibitors is compromised by toxicity due to inhibition of host Hsp90. To identify components of the Hsp90-dependent circuitry governing virulence and drug resistance that are sufficiently divergent for selective targeting in the pathogen, we pioneered chemical genomic profiling of the Hsp90 genetic network in C. albicans. Here, we screen mutant collections covering ~10% of the genome for hypersensitivity to Hsp90 inhibition in multiple environmental conditions. We identify 158 HSP90 chemical genetic interactors, most of which are important for growth only in specific environments. We discovered that the sterol C-22 desaturase gene ERG5 and the phosphatidylinositol-4-kinase (PI4K) gene STT4 are HSP90 genetic interactors under multiple conditions, suggesting a function upstream of Hsp90. By systematic analysis of the ergosterol biosynthetic cascade, we demonstrate that defects in ergosterol biosynthesis induce cellular stress that overwhelms Hsp90’s functional capacity. By analysis of the phosphatidylinositol pathway, we demonstrate that there is a genetic interaction between the PI4K Stt4 and Hsp90. We also establish that Stt4 is required for normal actin polarization through regulation of Wal1, and suggest a model in which defects in actin remodeling induces stress that creates a cellular demand for Hsp90 that exceeds its functional capacity. Consistent with this model, actin inhibitors are synergistic with Hsp90 inhibitors. We highlight new connections between Hsp90 and virulence traits, demonstrating that Erg5 and Stt4 enable activation of macrophage pyroptosis. This work uncovers novel circuitry regulating Hsp90 functional capacity and new effectors governing drug resistance, morphogenesis and virulence, revealing new targets for antifungal drug development. Hsp90 is an essential and conserved molecular chaperone that is required for the folding and function of a wide range of client proteins, especially those involved in signaling and stress responses. In the human fungal pathogen Candida albicans, Hsp90 governs drug resistance, morphogenesis, and virulence. In our previous analysis, we developed a chemical genomic approach to map the HSP90 chemical genetic network in C. albicans, an organism for which classical genetic approaches are hampered by the lack of a complete sexual cycle. Here, we confirm the environmental contingency of the Hsp90 genetic network in C. albicans, identify novel genetic interactions, and demonstrate new circuitry that regulates Hsp90 functional capacity in the cell. In the context of treatment of infectious disease, the challenge in avoiding host toxicity and achieving specificity lies in either the development of pathogen-selective Hsp90 inhibitors or identifying pathogen-specific components of the circuitry through which Hsp90 governs virulence. This work provides insight into such circuitry in the leading fungal pathogen of humans.