Mycobacterium tuberculosis PE_PGRS20 and PE_PGRS47 Proteins Inhibit Autophagy by Interaction with Rab1A.
Mycobacterium tuberculosis PE_PGRS20 and PE_PGRS47 Proteins Inhibit Autophagy by Interaction with Rab1A.
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DOI：
10.1128/msphere.00549-21
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发表时间：
2021-08-25
期刊：
影响因子：
4.8
通讯作者：
Lee S
中科院分区：
文献类型：
--
作者：
Strong EJ;Ng TW;Porcelli SA;Lee S
自噬是一种基本的细胞过程，在针对多种微生物的先天免疫和获得性免疫中具有重要作用。许多致病微生物已经进化出逃避或利用自噬的机制。已有研究表明，诱导自噬可以抑制分枝杆菌的细胞内存活，而结核分枝杆菌的几种PE_PGRs家族蛋白被认为是自噬的抑制因子，以促进分枝杆菌的存活。然而，这些效应器抑制自噬的机制还没有确定。在这里，我们报告了对结核分枝杆菌两个基因pe_pgrs20和pe_pgrs47缺失突变体的详细研究，我们以前报道过这两个基因在防止受感染宿主细胞自噬方面起到了作用。这些突变导致巨噬细胞中结核分枝杆菌自噬增加，细胞内存活率降低。这种表型伴随着感染细胞产生的细胞因子和抗原提呈的增加。我们进一步证明了PE_PGRS20和PE_PGRS47对自噬的抑制是典型的自噬而不是自噬通量的抑制。利用表达PE_PGRS20或PE_PGRS47的巨噬细胞，我们发现这些蛋白通过与RAS相关蛋白Rab1A相互作用而直接抑制自噬的启动。在哺乳动物细胞中沉默Rab1a可以挽救pe_pgrs20和pe_pgrs47缺失突变株的存活缺陷，并减少细胞因子的分泌。据我们所知，这是第一次确定分枝杆菌效应器直接与负责自噬启动的宿主蛋白相互作用的研究。重要：结核病是一种重要的全球性传染病，由结核分枝杆菌感染肺部引起，然后结核分枝杆菌主要在宿主吞噬细胞内驻留和复制。自噬是一个复杂的宿主细胞过程，有助于控制细胞内感染，增强先天和适应性免疫反应。在与人类共同进化的过程中，结核分枝杆菌获得了抑制宿主细胞过程的各种机制，包括自噬。我们鉴定了两个相关的结核分枝杆菌蛋白，PE_PGRS20和PE_PGRS47，这是首次报道的干扰自噬起始阶段的特定分枝杆菌效应物的例子。这些PE_PGRs蛋白的自噬调节导致细菌在吞噬细胞中的存活率增加，并增加分枝杆菌抗原的自噬降解，以刺激适应性免疫反应。更好地了解结核分枝杆菌如何调节宿主细胞中的自噬，有助于设计新的、更有效的结核病治疗方法或疫苗。
Autophagy is a fundamental cellular process that has important roles in innate and adaptive immunity against a broad range of microbes. Many pathogenic microbes have evolved mechanisms to evade or exploit autophagy. It has been previously demonstrated that induction of autophagy can suppress the intracellular survival of mycobacteria, and several PE_PGRS family proteins of Mycobacterium tuberculosis have been proposed to act as inhibitors of autophagy to promote mycobacterial survival. However, the mechanisms by which these effectors inhibit autophagy have not been defined. Here, we report detailed studies of M. tuberculosis deletion mutants of two genes, pe_pgrs20 and pe_pgrs47, that we previously reported as having a role in preventing autophagy of infected host cells. These mutants resulted in increased autophagy and reduced intracellular survival of M. tuberculosis in macrophages. This phenotype was accompanied by increased cytokine production and antigen presentation by infected cells. We further demonstrated that autophagy inhibition by PE_PGRS20 and PE_PGRS47 resulted from canonical autophagy rather than autophagy flux inhibition. Using macrophages transfected to express PE_PGRS20 or PE_PGRS47, we showed that these proteins inhibited autophagy initiation directly by interacting with Ras-related protein Rab1A. Silencing of Rab1A in mammalian cells rescued the survival defects of the pe_pgrs20 and pe_pgrs47 deletion mutant strains and reduced cytokine secretion. To our knowledge, this is the first study to identify mycobacterial effectors that directly interact with host proteins responsible for autophagy initiation. IMPORTANCE Tuberculosis is a significant global infectious disease caused by infection of the lungs with Mycobacterium tuberculosis, which then resides and replicates mainly within host phagocytic cells. Autophagy is a complex host cellular process that helps control intracellular infections and enhance innate and adaptive immune responses. During coevolution with humans, M. tuberculosis has acquired various mechanisms to inhibit host cellular processes, including autophagy. We identified two related M. tuberculosis proteins, PE_PGRS20 and PE_PGRS47, as the first reported examples of specific mycobacterial effectors interfering with the initiation stage of autophagy. Autophagy regulation by these PE_PGRS proteins leads to increased bacterial survival in phagocytic cells and increased autophagic degradation of mycobacterial antigens to stimulate adaptive immune responses. A better understanding of how M. tuberculosis regulates autophagy in host cells could facilitate the design of new and more effective therapeutics or vaccines against tuberculosis.