Department of Microbiology and Immunology, Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, CA 94158, USA.
Cell. 2012 Aug 17;150(4):803-15. doi: 10.1016/j.cell.2012.06.040.
Eukaryotic cells sterilize the cytosol by using autophagy to route invading bacterial pathogens to the lysosome. During macrophage infection with Mycobacterium tuberculosis, a vacuolar pathogen, exogenous induction of autophagy can limit replication, but the mechanism of autophagy targeting and its role in natural infection remain unclear. Here we show that phagosomal permeabilization mediated by the bacterial ESX-1 secretion system allows cytosolic components of the ubiquitin-mediated autophagy pathway access to phagosomal M. tuberculosis. Recognition of extracelluar bacterial DNA by the STING-dependent cytosolic pathway is required for marking bacteria with ubiquitin, and delivery of bacilli to autophagosomes requires the ubiquitin-autophagy receptors p62 and NDP52 and the DNA-responsive kinase TBK1. Remarkably, mice with monocytes incapable of delivering bacilli to the autophagy pathway are extremely susceptible to infection. Our results reveal an unexpected link between DNA sensing, innate immunity, and autophagy and indicate a major role for this autophagy pathway in resistance to M. tuberculosis infection.
真核细胞通过自噬将入侵的细菌病原体运送到溶酶体来使细胞质无菌化。在巨噬细胞感染结核分枝杆菌(一种液泡病原体)时,外源性诱导自噬可以限制其复制,但自噬靶向的机制及其在自然感染中的作用仍不清楚。在这里,我们发现细菌 ESX-1 分泌系统介导的吞噬体通透性允许泛素介导的自噬途径的细胞质成分进入吞噬体中的结核分枝杆菌。依赖 STING 的细胞质途径识别细胞外细菌 DNA 是将细菌标记上泛素所必需的,而将细菌递送至自噬体需要泛素自噬受体 p62 和 NDP52 以及 DNA 反应性激酶 TBK1。值得注意的是,不能将细菌递送至自噬途径的单核细胞的小鼠对感染极其敏感。我们的研究结果揭示了 DNA 感应、先天免疫和自噬之间的意外联系,并表明该自噬途径在抵抗结核分枝杆菌感染中起主要作用。