Fungal Ras-mediated invasive growth mechanisms

真菌 Ras 介导的侵袭性生长机制

• 批准号: 8696215
• 负责人: Jarrod R. Fortwendel
• 金额: $ 30.2万
• 依托单位: UNIVERSITY OF SOUTH ALABAMA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-02-14 至 2019-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8696215
• 关键词: Address; Affect; Antifungal Agents; Antifungal Therapy; Area; Arginine; Aspergillosis; Aspergillus fumigatus; Biochemical; Biology; Cell Wall; Cellular Stress Response; Complement; Complementarity Determining Regions; Data; Disease; Environment; Fungal Genome; Future; Growth; Guanosine Triphosphate Phosphohydrolases; HRAS gene; Homologous Gene; Human; Immune system; Immunocompromised Host; Individual; Infection; Invaded; Knowledge; Life; Lung; Mediating; Modeling; Molds; Molecular; Morphogenesis; Mutation; Nature; Pathogenesis; Pathway interactions; Patients; Play; Post-Translational Protein Processing; Process; Property; Proteins; Proteomics; Ras Signaling Pathway; Regulation; Research; Resistance; Role; Signal Pathway; Signal Transduction; Signaling Protein; Stress; Tertiary Protein Structure; Tissues; Virulence; Work; antimicrobial; biological adaptation to stress; defined contribution; design; fungus; insight; mortality; mutant; new therapeutic target; novel; pathogen; public health relevance; ras Proteins; tool; trafficking

DESCRIPTION (provided by applicant): Aspergillus fumigatus is the major causative agent of invasive aspergillosis, a severe and life-threatening disease of immunocompromised patients. A. fumigatus is a ubiquitous and adept pathogen, able to adapt quickly to the mammalian lung environment and to effectively handle the stresses encountered while growing within the human host. Because of the multi-factorial nature of fungal growth, attempts to identify individual A. fumigatus virulence determinants are often unsuccessful. However, previous studies have consistently proven that filamentous fungal pathogens must be able to coordinate proper hyphal morphogenesis in order to invade tissue and cause high mortality rates. Unfortunately, our knowledge of the molecular mechanisms supporting sustained polarized growth and the establishment and progression of invasive disease is incomplete. To elucidate these mechanisms, better models of the signaling pathways and protein interactions that regulate fungal morphogenesis must be developed. Ras proteins orchestrate multiple fungal morphogenetic processes in pathogenic fungi. Regulation of these processes by Ras plays an essential role in fungal virulence, making fungal Ras signaling an invaluable tool for probing fungal pathogenesis and identifying new targets for novel therapeutics. Although many aspects of Ras signaling pathways are often considered too highly conserved to serve as antimicrobial targets in eukaryotic pathogens, we have identified novel, fungal-specific protein domains that define fundamental differences between fungal and human Ras proteins. These include two areas of significant divergence between fungal Ras proteins and their human counterpart, H-ras: 1) the Invariant Arginine Domain (IRD), a novel domain conserved in the RasA homologs of every available fungal genome but not present in H-ras, and 2) an extended hypervariable region (HVR) in filamentous fungi. Our preliminary data show that the IRD and HVR are required for Ras function during hyphal growth and morphogenesis, revealing fungal-specific aspects of Ras signaling. The overall objectives of this proposal are to fully define the impact of these fungal-specific protein domains to Ras biology, using mutations of these domains to identify novel Ras pathway interactions critical for polarized morphogenesis and virulence. Using mutational and biochemical analyses, Aim 1 or this proposal will define the contribution of the IRD and HVR to A. fumigatus Ras biology. These studies will address how mutation of the IRD and HVR affect RasA GTPase activity, activation, localization and interaction downstream effectors. Complementing our Aim 1 studies, Aim 2 utilizes an unbiased proteomics screen to identify novel, fungal-specific Ras interactions contributing to Ras-mediated growth and virulence. Because Ras signaling is essential for fungal virulence, identification and characterization of fundamental differences between human and Ras pathways carries the long-term potential of uncovering novel antifungal therapies.

描述（由申请人提供）：烟曲霉是侵袭性曲霉病的主要病原体，侵袭性曲霉病是免疫功能低下患者的一种严重且危及生命的疾病。烟曲霉是一种普遍存在且熟练的病原体，能够快速适应哺乳动物肺部环境，并有效应对在人类宿主体内生长时遇到的压力。由于真菌生长的多因素性质，确定单个烟曲霉毒力决定因素的尝试常常不成功。然而，先前的研究一致证明，丝状真菌病原体必须能够协调适当的菌丝形态发生才能侵入组织并导致高死亡率。不幸的是，我们对支持持续极化生长以及侵袭性疾病的建立和进展的分子机制的了解并不完整。为了阐明这些机制，必须开发调节真菌形态发生的信号通路和蛋白质相互作用的更好模型。 Ras 蛋白协调病原真菌中的多种真菌形态发生过程。 Ras 对这些过程的调节在真菌毒力中发挥着重要作用，使真菌 Ras 信号成为探索真菌发病机制和确定新疗法新靶点的宝贵工具。尽管 Ras 信号通路的许多方面通常被认为过于保守，无法作为真核病原体的抗菌靶点，但我们已经确定了新的真菌特异性蛋白结构域，这些结构域定义了真菌和人类 Ras 蛋白之间的根本差异。其中包括真菌 Ras 蛋白与其人类对应物 H-ras 之间存在显着差异的两个领域：1) 不变精氨酸结构域 (IRD)，这是每个可用真菌基因组的 RasA 同源物中保守的新结构域，但在 H-ras 中不存在，和2）丝状真菌中的扩展高变区（HVR）。我们的初步数据表明，IRD 和 HVR 在菌丝生长和形态发生过程中是 Ras 功能所必需的，揭示了 Ras 信号传导的真菌特异性方面。该提案的总体目标是充分定义 这些真菌特异性蛋白结构域与 Ras 生物学的关系，利用这些结构域的突变来识别对极化形态发生和毒力至关重要的新型 Ras 通路相互作用。使用突变和生化分析，目标 1 或本提案将定义 IRD 和 HVR 对烟曲霉 Ras 生物学的贡献。这些研究将解决 IRD 和 HVR 突变如何影响 RasA GTPase 活性、激活、定位和下游效应器的相互作用。为了补充我们的 Aim 1 研究，Aim 2 利用无偏见的蛋白质组学筛选来识别有助于 Ras 介导的生长和毒力的新型真菌特异性 Ras 相互作用。由于 Ras 信号传导对于真菌毒力至关重要，因此识别和表征人类和 Ras 通路之间的根本差异具有发现新型抗真菌疗法的长期潜力。