Extracellular M. tuberculosis DNA Targets Bacteria for Autophagy by Activating the Host DNA-Sensing Pathway

Abstract

SUMMARY 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.

Lysosomal capturing of cytoplasmic injected nanoparticles by autophagy: An additional barrier to non viral gene delivery

“…6 indeed confirms that less nanoparticles are colocalized with GFP-LC3 when compared to GFP-LAMP1. nanoparticles induce autophagy more when compared to polystyrene beads, which could be attributed to the presence of foreign pDNA in these complexes (27). The fact that PEI/DNA nanoparticles are taken up significantly more than polystyrene beads in GFP-LC3 positive vesicles, both after injection or when delivered through endocytosis can also be seen from the colocalization analysis presented in Fig.…”

“…For free plasmid DNA it has been suggested that autophagy can be induced when the pDNA is delivered to the cell's cytoplasm by microinjection (27). As autophagy is considered as an innate intracellular defense mechanism to clear the cells from incoming pathogens such as viruses and bacteria, it seems logic that also foreign DNA sequences could be recognized in the cytoplasm of the cells by the cellular DNA sensors.…”

Species‐specific impact of the autophagy machinery on Chikungunya virus infection

“…Together, these results show that, in contrast to human cells, autophagy is antiviral in mouse cells and indicates that CHIKV species specificity is linked, at least in part, to the ability of NDP52 to bind both nsP2 and LC3-C, leading to a proviral effect. Recently, it has been shown that mNDP52 targets Mycobacterium tuberculosis to autophagic degradation, showing that mNDP52 might act as a canonical autophagy receptor in mouse cells [35]. These data indicate that the ability of hNDP52 to bind both hLC3-C and nsP2 is implicated in its species-specific proviral effect on CHIKV.…”

The ubiquitin system: a critical regulator of innate immunity and pathogen–host interactions

“…Recent research partially sheds light on the underlying mechanism: the bacterial ESX-1 T7SS-mediated phagosomal permeabilization allows the cGAS-STING-dependent cytosolic DNA sensor pathway to access extracellular bacterial DNA and then triggers parkinmediated K63-linked ubiquitination surrounding the Mtbcontaining phagosome, which is required for the delivery of bacilli to autophagosomes. [65][66][67] Despite these observations, it is still poorly understood how parkin is recruited and activated at the bacterial niche and which bona fide protein(s) are targeted by parkin, as well as the identity of other E3s responsible for K48-linked ubiquitination. Another well-defined example involves the LRR-harboring RING family E3 ligase LRSAM1, which targets Sa.…”