Regulation of ubiquitin-proteasome in Cryptococcus pathogenesis

泛素蛋白酶体在隐球菌发病机制中的调控

• 批准号: 8969923
• 负责人: Chaoyang Xue
• 金额: $ 23.85万
• 依托单位: RBHS-NEW JERSEY MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-08 至 2017-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8969923
• 关键词: Alveolar Macrophages; Anabolism; Animal Model; Antifungal Agents; Communicable Diseases; Cryptococcus; Cryptococcus neoformans; Cryptococcus neoformans infection; Development; Disease; Disease Progression; Drug Targeting; Drug resistance; Enzymes; Eukaryota; F-Box Proteins; Foundations; Fungal Meningitis; Fungal Proteins; Fungal Vaccines; Goals; Growth; Host Defense; Human; Immune; Immune System Diseases; Immune response; Immunity; Immunosuppression; Infection; Inflammatory Response; Inositol; Investigation; Lead; Life; Link; Lung; Mediating; Meningitis; Metabolism; Mission; Modeling; Molecular; Mus; Mycoses; Neuraxis; Pathogenesis; Pathogenicity; Pharmaceutical Preparations; Phospholipase; Post-Translational Regulation; Process; Proliferating; Proteins; Public Health; Regulation; Reporting; Research; Research Personnel; Role; Signal Transduction; Sphingolipids; System; Therapeutic; Therapeutic Agents; Ubiquitin; Ubiquitination; United States National Institutes of Health; Vaccines; Virulence; Virulence Factors; base; design; fungus; immunoregulation; innovation; interest; killings; macrophage; multicatalytic endopeptidase complex; mutant; novel; novel therapeutic intervention; novel therapeutics; pathogen; protein degradation; public health relevance; research study; response; success; ubiquitin-protein ligase

 DESCRIPTION (provided by applicant): Cryptococcus neoformans is a fungal pathogen that infects the lungs and can disseminate to the central nervous system to cause life-threatening meningitis. There is a lack of effective anti-cryptococcal therapeutics, including vaccines and drugs, due in part to an incomplete understanding of cryptococcal disease mechanisms and host-pathogen interactions. My group has recently shown that a subunit of the SCFFbp1 E3 ubiquitin ligase, Fbp1, is essential for fungal pathogenicity in a manner independent of known virulence factors, suggesting that ubiquitin-mediated protein turnover is involved in a novel virulence control mechanism. We found that Cryptococcus mutants lacking Fbp1 had significantly reduced fungal survival in the lung in murine models and were strongly impaired for survival within macrophages. Interestingly, the fbp1Δ mutant also elicited a superior host protective immune response compared to the wild type strain, suggesting that Fbp1 may function as or may regulate an immune suppressor. Together, these discoveries led to our central hypothesis that SCFFbp1 E3 ligase regulates fungal pathogenesis by controlling the ubiquitination and degradation of specific proteins - a process required for immune suppression and disease establishment in the lung. In support of this hypothesis, we have already identified one Fbp1 substrate, sphingolipid metabolism enzyme Isc1, and confirmed its role in cryptococcal virulence. Our long-term goal is to understand the molecular mechanism of SCFFbp1 E3 ligase-mediated Cryptococcus-host interaction during lung infection. We propose two Specific Aims. In Aim 1 we will determine how Fbp1 modulates host immunity during lung infection by: (a) deciphering the distinct inflammatory responses triggered in macrophages in response to fbp1Δ as compared to the parental strain, and (b) evaluating the potential of employing fbp1Δ as a vaccine strain to promote protection against cryptococcis. In Aim 2 we will characterize the molecular basis of SCFFbp1 E3 ligase-mediated regulation of fungal pathogenesis by (a) characterizing the role of Isc1-dependent sphingolipid biosynthesis in Cryptococcus virulence, and (b) identifying additional Fbp1 substrates that are required for pathogenesis. This project is innovative because it investigates a novel virulence determining mechanism by focusing on a heretofore unknown link between cryptococcal protein turnover and virulence. The proposed research is significant because it will enhance our understanding of E3 ligase-mediated fungal virulence, facilitating efforts to design new therapeutic agents that interact with Fbp1 and its downstream effectors, and may provide a potential vaccine strategy.

 描述（由申请人提供）：新型隐球菌是一种真菌病原体，可感染肺部并可传播至中枢神经系统，导致危及生命的脑膜炎，由于缺乏有效的抗隐球菌疗法，包括疫苗和药物。我的研究小组最近发现 SCFFbp1 E3 泛素的一个亚基。连接酶 Fbp1 以独立于已知毒力因子的方式对真菌致病性至关重要，这表明泛素介导的蛋白质周转参与了一种新的毒力控制机制，我们发现缺乏 Fbp1 的隐球菌突变体显着降低了肺部真菌的存活率。在小鼠模型中，fbp1Δ突变体在巨噬细胞内的生存受到严重损害，与野生型菌株相比，fbp1Δ突变体也引发了宿主更好的保护性免疫反应，这表明Fbp1可能总之，这些发现得出了我们的中心假设：SCFFbp1 E3 连接酶通过控制特定蛋白质的泛素化和降解来调节真菌发病机制，这是免疫抑制和疾病在肺部建立所需的过程。根据这一假设，我们已经鉴定了一种 Fbp1 底物——鞘脂代谢酶 Isc1，并证实了它在隐球菌毒力中的作用。我们的长期目标是了解其分子机制。 SCFFbp1 E3 连接酶介导的肺部感染期间的隐球菌-宿主相互作用在目标 1 中，我们将通过以下方式确定 Fbp1 在肺部感染期间如何调节宿主免疫：(a) 破译巨噬细胞响应 fbp1Δ 引发的不同炎症反应。与亲本菌株相比，以及（b）评估使用 fbp1Δ 作为疫苗菌株以促进对隐球菌的保护的潜力。通过 (a) 表征 Isc1 依赖性鞘脂生物合成在隐球菌毒力中的作用，以及 (b) 鉴定发病机制所需的其他 Fbp1 底物，来表征 SCFFbp1 E3 连接酶介导的真菌发病机制调节的分子基础。它通过关注隐球菌蛋白质周转和毒力之间迄今为止未知的联系来研究一种新的毒力决定机制。意义重大，因为它将增强我们对 E3 连接酶介导的真菌毒力的理解，促进设计与 Fbp1 及其下游效应子相互作用的新治疗剂，并可能提供潜在的疫苗策略。