Chemical modulation of SQSTM1/p62-mediated xenophagy that targets a broad range of pathogenic bacteria.

ABSTRACT

The N-degron pathway is a proteolytic system in which the N-terminal degrons (N-degrons) of proteins, such as arginine (Nt-Arg), induce the degradation of proteins and subcellular organelles via the ubiquitin-proteasome system (UPS) or macroautophagy/autophagy-lysosome system (hereafter autophagy). Here, we developed the chemical mimics of the N-degron Nt-Arg as a pharmaceutical means to induce targeted degradation of intracellular bacteria via autophagy, such as Salmonella enterica serovar Typhimurium (S. Typhimurium), Escherichia coli, and Streptococcus pyogenes as well as Mycobacterium tuberculosis (Mtb). Upon binding the ZZ domain of the autophagic cargo receptor SQSTM1/p62 (sequestosome 1), these chemicals induced the biogenesis and recruitment of autophagic membranes to intracellular bacteria via SQSTM1, leading to lysosomal degradation. The antimicrobial efficacy was independent of rapamycin-modulated core autophagic pathways and synergistic with the reduced production of inflammatory cytokines. In mice, these drugs exhibited antimicrobial efficacy for S. Typhimurium, Bacillus Calmette-Guérin (BCG), and Mtb as well as multidrug-resistant Mtb and inhibited the production of inflammatory cytokines. This dual mode of action in xenophagy and inflammation significantly protected mice from inflammatory lesions in the lungs and other tissues caused by all the tested bacterial strains. Our results suggest that the N-degron pathway provides a therapeutic target in host-directed therapeutics for a broad range of drug-resistant intracellular pathogens.Abbreviations ATG autophagy-related gene; BCG Bacillus Calmette-Guérin; BMDMs bone marrow-derived macrophages; CALCOCO2/NDP52 calcium binding and coiled-coil domain 2; CFUs colony-forming units; CXCL C-X-C motif chemokine ligand; EGFP enhanced green fluorescent protein; IL1B/IL-1ß interleukin 1 beta; IL6 interleukin 6; LIR MAP1LC3/LC3-interacting region; MAP1LC3/LC3 microtubule associated protein 1 light chain 3; Mtb Mycobacterium tuberculosis; MTOR mechanistic target of rapamycin kinase; NBR1 NBR1 autophagy cargo receptor; OPTN optineurin; PB1 Phox and Bem1; SQSTM1/p62 sequestosome 1; S. Typhimurium Salmonella enterica serovar Typhimurium; TAX1BP1 Tax1 binding protein 1; TNF tumor necrosis factor; UBA ubiquitin-associated.