M. tuberculosis infection of human iPSC-derived macrophages reveals complex membrane dynamics during xenophagy evasion
Summary
Xenophagy is an important cellular defence mechanism against cytosol-invading pathogens, such as Mycobacterium tuberculosis (Mtb). Activation of xenophagy in macrophages targets Mtb to autophagosomes; however, how Mtb is targeted to autophagosomes in human macrophages at a high spatial and temporal resolution is unknown. Here, we use human induced pluripotent stem cell-derived macrophages (iPSDMs) to study the human macrophage response to Mtb infection and the role of the ESX-1 type VII secretion system. Using RNA-seq, we identify ESX-1-dependent transcriptional responses in iPSDMs after infection with Mtb. This analysis revealed differential inflammatory responses and dysregulated pathways such as eukaryotic initiation factor 2 (eIF2) signalling and protein ubiquitylation. Moreover, live-cell imaging revealed that Mtb infection in human macrophages induces dynamic ESX-1-dependent, LC3B-positive tubulovesicular autophagosomes (LC3-TVS). Through a correlative live-cell and focused ion beam scanning electron microscopy (FIB SEM) approach, we show that upon phagosomal rupture, Mtb induces the formation of LC3-TVS, from which the bacterium is able to escape to reside in the cytosol. Thus, iPSDMs represent a valuable model for studying spatiotemporal dynamics of human macrophage-Mtb interactions, and Mtb is able to evade capture by autophagic compartments. © 2020. Published by The Company of Biologists Ltd.
| Authors | Bernard EM, Fearns A, Bussi C, Santucci P, Peddie CJ, Lai RJ, Collinson LM, Gutierrez MG |
|---|---|
| Journal | Journal of cell science |
| Publication Date | 2020 Nov 25;134(5) |
| PubMed | 32938685 |
| PubMed Central | PMC7710011 |
| DOI | 10.1242/jcs.252973 |