ER-phagy in the functional conversion of the Brucella-containing vacuole

内质网吞噬在含布鲁氏菌液泡功能转换中的作用

• 批准号: 10793320
• 负责人: JEAN A CELLI
• 金额: $ 19.5万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-20 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10793320
• 关键词: Automobile Driving; Autophagocytosis; Autophagosome; Bacteria; Binding; Biogenesis; Brucella; Brucella abortus; Cell Compartmentation; Cell physiology; Communicable Diseases; Data; Dedications; Endoplasmic Reticulum; Evolution; Immune; Immunologic Receptors; Infection; Knowledge; Label; Life Style; Mammalian Cell; Mediating; Membrane; Microbe; Modeling; Molecular; Nature; Organelles; Pathway interactions; Phagocytes; Phagosomes; Process; Proliferating; Proteins; Regulation; Role; Signal Transduction; Testing; Type IV Secretion System Pathway; Vacuole; Virulence; Zoonoses; biological adaptation to stress; experimental study; immune function; improved; innate immune function; microbial; novel; pathogen; pathogenic bacteria; pathogenic microbe; permissiveness; receptor; recruit; response; sensor

Project Summary Intracellular microbes with a vacuolar lifestyle share an ability to remodel host cell compartments and functions to support specific stages of their infectious cycle. The cellular and molecular details of how microbial vacuoles functionally evolve during a pathogen’s intracellular cycle to promote their virulence are not well understood. Here we aim to define cellular processes driving the functional evolution of the intracellular vacuole of the zoonotic bacterium Brucella abortus, which transitions from a replicative niche to an egress organelle. B. abortus primarily infects phagocytes and remodels its original phagosome into the replicative Brucella-containing vacuole (rBCV), an organelle derived from the host endoplasmic reticulum (ER) that supports intracellular proliferation. rBCVs subsequently convert into autophagosome- like vacuoles (aBCVs) that mediate post-replication bacterial egress. Autophagy is a conserved eukaryotic process of selective or non-selective capture of cellular content within membrane-bound autophagosomes for lysosomal degradation, including the selective degradation of organelles such as the ER via dedicated autophagy receptors. We have shown that aBCV biogenesis from rBCVs requires a subset of conventional autophagic machineries and an active bacterial VirB Type IV secretion system, but the process, selectivity and regulation of this vacuolar conversion remain enigmatic. Brucella infection triggers the Unfolded Protein Response (UPR) during the rBCV stage via the innate immune sensor STING, provoking an ER- centered stress response that promotes bacterial replication within rBCVs. Whether the UPR also contributes to aBCV biogenesis is unknown. STING-dependent UPR induces ER-phagy, whose selectivity could mechanistically drive the capture of ER-derived rBCVs by autophagosomes to form aBCVs. Based on preliminary evidence that i) Brucella infection influences ER-phagy; ii) rBCVs recruit distinct ER-phagy receptors and iii) STING is required for aBCV biogenesis, here we will test the overall hypothesis that aBCV biogenesis is mediated by selective ER-phagy of rBCVs via a STING-dependent process. Aim1 will determine i) whether Brucella modulates ER-phagy, ii) whether specific ER-phagy receptors are required for aBCV biogenesis and iii) the autophagic cascade engaged during aBCV biogenesis. Aim 2 will determine whether the role of STING in aBCV biogenesis is via induction of the UPR or its activity as an ER-phagy receptor. The successful completion of these aims will establish new concepts of functional evolution of bacterial vacuoles, a common feature of the infectious cycle of many microbial pathogens that is poorly understood.

项目概要 具有液泡生活方式的细胞内微生物具有重塑宿主细胞区室和 支持感染周期特定阶段的细胞和分子细节。 微生物液泡在病原体的细胞内循环过程中功能性地进化以提高其毒力 在这里，我们的目标是定义驱动功能进化的细胞过程。 人畜共患病细菌流产布鲁氏菌的细胞内液泡，从复制生态位转变 流产芽孢杆菌主要感染吞噬细胞并将其原始吞噬体重塑为出口细胞器。 含有复制性布鲁氏菌的真空（rBCV），一种源自宿主内质的细胞器 支持细胞内增殖的网状结构（ER）随后转化为自噬体。 像介导复制后细菌排出的液泡（aBCV）一样，自噬是一种保守的真核生物。 膜结合自噬体内选择性或非选择性捕获细胞内容物的过程 用于溶酶体降解，包括通过专用的细胞器选择性降解内质网 我们已经证明，rBCV 的 aBCV 生物发生需要传统的子集。 自噬机制和活性细菌 VirB IV 型分泌系统，但过程、选择性 这种液泡转换的调节仍然是个谜。 rBCV 阶段的蛋白质反应 (UPR) 通过先天免疫传感器 STING，引发 ER- UPR 是否也促进 rBCV 内细菌复制的集中应激反应。 STING 依赖性 UPR 诱导 ER 吞噬的作用尚不清楚，其选择性。 可以通过自噬体机械驱动内质网衍生的 rBCV 形成 aBCV。 初步证据表明 i) 布鲁氏菌感染影响 ER 吞噬 ii) rBCV 招募不同的 ER 吞噬； 受体和 iii) STING 是 aBCV 生物发生所必需的，在这里我们将检验总体假设： aBCV 生物发生是由 rBCV 的选择性 ER 吞噬通过 Aim1 依赖性过程介导的。 确定 i) 布鲁氏菌是否调节 ER 吞噬，ii) 是否需要特定的 ER 吞噬受体 aBCV 生物发生和 iii) aBCV 生物发生过程中参与的自噬级联将。 确定 STING 在 aBCV 生物合成中的作用是否是通过诱导 UPR 或其作为 ER-吞噬受体的成功完成将建立功能性的新概念。 细菌液泡的进化是许多微生物病原体感染周期的共同特征 人们对此知之甚少。