Interferon-inducible guanylate-binding proteins (GBPs) promote cell-intrinsic defense through host cell death. GBPs target pathogens and pathogen-containing vacuoles and promote membrane disruption for release of microbial molecules that activate inflammasomes. GBP1 mediates pyroptosis or atypical apoptosis of Salmonella Typhimurium (STm)- or Toxoplasma gondii (Tg)- infected human macrophages, respectively. The pathogen-proximal detection-mechanisms of GBP1 remain poorly understood, as humans lack functional immunity-related GTPases (IRGs) that assist murine Gbps. Here, we establish that GBP1 promotes the lysis of Tg-containing vacuoles and parasite plasma membranes, releasing Tg-DNA. In contrast, we show GBP1 targets cytosolic STm and recruits caspase-4 to the bacterial surface for its activation by lipopolysaccharide (LPS), but does not contribute to bacterial vacuole escape. Caspase-1 cleaves and inactivates GBP1, and a cleavage-deficient GBP1D192E mutant increases caspase-4-driven pyroptosis due to the absence of feedback inhibition. Our studies elucidate microbe-specific roles of GBP1 in infection detection and its triggering of the assembly of divergent caspase signaling platforms.
Bibliographical noteFunding Information:
We thank Matt Renshaw from the Crick Advanced Light Microscopy (CALM) STP for help with super-resolution SIM imaging, Julia Sanchez-Garrido for help in optimizing immunoblots and advice on reagents, Michael Howell from the Crick High-throughput screening (HTS) STP for help in performing automated imaging experiments, the Crick Genomics and Equipment Park STP for performing Sanger sequencing and DNA minipreps for cloning, Debipriya Das from the Crick Flow Cytometry STP for sorting Tg parasites, and Caia Dominicus, Jeanette Wagener, and Joanna Young from Moritz Treeck’s lab for help with creation of new transgenic Tg lines. We thank all members of the Frickel and the Shenoy labs for productive discussion and assistance in the project. This work was supported by the Francis Crick Institute, which receives its core funding from Cancer Research UK ( FC001076 to E.-M.F. and FC001999 to L.M.C. and A.P.S.), the UK Medical Research Council ( FC001076 to E.-M.F. and FC001999 to L.M.C. and A.P.S.), and the Wellcome Trust ( FC001076 to E.-M.F. and FC001999 to L.M.C. and A.P.S.). E.-M.F. was supported by a Wellcome Trust Career Development Fellowship ( 091664/B/10/Z ) and a Wellcome Trust Senior Fellowship (217202/Z/19/Z). D.F. was supported by a Boehringer Ingelheim Fonds PhD fellowship. A.R.S. acknowledges support from the MRC ( MR/P022138/1 ) and Wellcome Trust ( 108246/Z/15/Z ). M.Y. was supported by the Research Program on Emerging and Re-emerging Infectious Diseases ( JP18fk0108047 ) and the Japanese Initiative for Progress of Research on Infectious Diseases for Global Epidemic ( JP18fk0108046 ) from the Agency for Medical Research and Development (AMED). H.B. was supported by a Grant-in-Aid for Scientific Research on Innovative Areas ( 17K15677 ) from the Ministry of Education, Culture, Sports, Science and Technology .
© 2020 The Author(s)
Copyright 2020 Elsevier B.V., All rights reserved.
- Salmonella enterica
- Toxoplasma gondii
- Salmonella enterica Typhimurium
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)