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）：曲霉烟曲霉是侵入性曲霉菌病的主要病因，这是一种免疫功能低下患者的严重且威胁生命的疾病。 A. fumigatus是一种无处不在且熟练的病原体，能够迅速适应哺乳动物的肺部环境，并有效处理在人类宿主内生长时遇到的应力。由于真菌生长的多因素性质，试图鉴定单个烟曲霉的毒力决定因素通常失败。但是，以前的研究一直证明，丝状真菌病原体必须能够协调适当的菌丝形态发生，以侵入组织并引起高死亡率。不幸的是，我们对支持持续极化生长的分子机制的了解以及侵入性疾​​病的建立和发展是不完整的。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蛋白质在致病真菌中策划多种真菌形态发生过程。通过RAS对这些过程的调节在真菌毒力中起着至关重要的作用，使真菌RAS信号成为探测真菌发病机理并识别新疗法的新目标的宝贵工具。尽管通常认为RAS信号通路的许多方面被认为是太高度保守，无法用作真核病原体中的抗菌靶标，但我们已经确定了定义真菌和人类RAS蛋白质之间基本差异的新型真菌特异性蛋白结构域。这些领域包括真菌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）不变的精氨酸结构域（IRD），这是每个可用真菌基因组的RASA同源物中保守的新型域，但在H-RAS中不存在，但不存在于H-RAS和2）在filement filements filements filegi fungi中存在的。我们的初步数据表明，在菌丝生长和形态发生过程中，IRD和HVR是RAS功能所必需的，揭示了RAS信号的真菌特异性方面。该提案的总体目标是完全定义 这些真菌特异性蛋白质结构域对RAS生物学，使用这些结构域的突变来鉴定新型的RAS途径相互作用对于极化形态发生和毒力至关重要。使用突变和生化分析，AIM 1或该提案将定义IRD和HVR对A. fumigatus ras生物学的贡献。这些研究将解决IRD和HVR的突变如何影响RASA GTPase活性，激活，定位和下游效应子的相互作用。与我们的目标1研究相辅相成，AIM 2利用无偏的蛋白质组学筛选来识别新型的真菌特异性RAS相互作用，这有助于RAS介导的生长和毒力。由于RAS信号对于真菌毒力至关重要，因此人与RAS途径之间基本差异的鉴定和表征具有发现新型抗真菌疗法的长期潜力。