Type I interferon remodels lysosome function and modifies intestinal epithelial defense.

Abstract

Organelle remodeling is critical for cellular homeostasis, but host factors that control organelle function during microbial infection remain largely uncharacterized. Here, a genome-scale CRISPR/Cas9 screen in intestinal epithelial cells with the prototypical intracellular bacterial pathogen <i>Salmonella</i> led us to discover that type I IFN (IFN-I) remodels lysosomes. Even in the absence of infection, IFN-I signaling modified the localization, acidification, protease activity, and proteomic profile of lysosomes. Proteomic and genetic analyses revealed that multiple IFN-I-stimulated genes including <i>IFITM3</i>, <i>SLC15A3</i>, and <i>CNP</i> contribute to lysosome acidification. IFN-I-dependent lysosome acidification was associated with elevated intracellular <i>Salmonella</i> virulence gene expression, rupture of the <i>Salmonella</i>-containing vacuole, and host cell death. Moreover, IFN-I signaling promoted in vivo <i>Salmonella</i> pathogenesis in the intestinal epithelium where <i>Salmonella</i> initiates infection, indicating that IFN-I signaling can modify innate defense in the epithelial compartment. We propose that IFN-I control of lysosome function broadly impacts host defense against diverse viral and microbial pathogens.