Dram1 confers resistance toSalmonellainfection

Abstract

Dram1 is a stress and infection inducible autophagy modulator that functions downstream of transcription factors p53 and NFκB. Using a zebrafish embryo infection model, we have previously shown that Dram1 provides protection against the intracellular pathogen Mycobacterium marinum by promoting the p62-dependent xenophagy of bacteria that have escaped into the cytosol. However, the possible interplay between Dram1 and other anti-bacterial autophagic mechanisms remains unknown. Recently, LC3-associated phagocytosis (LAP) has emerged as an important host defense mechanism that requires components of the autophagy machinery and targets bacteria directly in phagosomes. Our previous work established LAP as the main autophagic mechanism by which macrophages restrict growth of Salmonella Typhimurium in a systemically infected zebrafish host. We therefore employed this infection model to investigate the possible role of Dram1 in LAP. Morpholino knockdown or CRISPR/Cas9-mediated mutation of Dram1 led to reduced host survival and increased bacterial burden during S. Typhimurium infections. In contrast, overexpression of dram1 by mRNA injection curtailed Salmonella replication and reduced mortality of the infected host. During the early response to infection, GFP-Lc3 levels in transgenic zebrafish larvae correlated with the dram1 expression level, showing over two-fold reduction of GFP-Lc3-Salmonella association in dram1 knockdown or mutant embryos and an approximately 30% increase by dram1 overexpression. Since LAP is known to require the activity of the phagosomal NADPH oxidase, we used a Salmonella biosensor strain to detect bacterial exposure to reactive oxygen species (ROS) and found that the ROS response was largely abolished in the absence of dram1. Together, these results demonstrate the host protective role of Dram1 during S. Typhimurium infection and suggest a functional link between Dram1 and the induction of LAP.

Stimulating the autophagic-lysosomal axis enhances host defense against fungal infection in a zebrafish model of invasive Aspergillosis

“…In addition to the drug treatment, we used a genetic strategy to enhance autophagy. We previously characterized dram1 /Dram1 (DNA-damage regulated autophagy modulator 1) as an enhancer of (auto)phagosome-lysosome fusion that is effective in host defense against infections of intracellular bacterial pathogens, including Mycobacterium and Salmonella [ 47 , 48 ]. While, similarly to sqstm1, dram1 was not a requirement for efficient fungal defense ( Figure 5(d )), its overexpression led to a significantly improved infection outcome ( Figure 5(e )).…”

DRAM1 Promotes Lysosomal Delivery of Mycobacterium marinum in Macrophages

“…Therefore, DRAM1 represents a putative target for host-directed anti-mycobacterial therapy that could help overcome current challenges posed by anti-microbial resistance. Therapeutic strategies targeting DRAM1 might be more broadly applicable against other intracellular pathogens, considering our recent results that DRAM1 also protects against infections with Salmonella enterica serovar Typhimurium and Aspergillus fumigatus [ 47 , 48 ]. Further elucidating its mechanism of action will facilitate the development of therapeutic strategies that exploit the role of DRAM1 in vesicle trafficking and fusion in the (auto)phagolysosomal pathway.…”

DRAM1 promotes antibacterial autophagy and lysosomal delivery of Mycobacterium marinum in macrophages

“…Therefore, DRAM1 represents a putative target for host-directed anti-mycobacterial therapy that could help overcome current challenges posed by anti-microbial resistance. Targeting DRAM1 may find wider applicability against intracellular pathogens, considering our recent results that DRAM1 also protects against infections with Salmonella enterica serovar Typhimurium and Aspergillus fumigatus [41,42]. Further elucidating its mechanism of action will facilitate the development of therapeutic strategies that exploit the role of DRAM1 in vesicle trafficking and fusion in the (auto)phagolysosomal pathway.…”