Bacterial internalization is required to trigger NIK-dependent NF-κB activation in response to the bacterial type three secretion system.
Infection of human cells with Yersinia pseudotuberculosis expressing a functional type III secretion system (T3SS) leads to activation of host NF-κB. We show that the Yersinia T3SS activates distinct NF-κB pathways dependent upon bacterial subcellular localization. We found that wildtype Yersinia able to remain extracellular triggered NF-κB activation independently of the non-canonical NF-κB kinase NIK in HEK293T cells. In contrast, Yersinia lacking the actin-targeting effectors YopEHO, which become internalized into host cells, induce a NIK-dependent response and nuclear entry of the non-canonical NF-κB subunit p52. Blocking actin polymerization and uptake of effector mutant bacteria using cytochalasin D shifted the host NF-κB response from NIK-independent to primarily NIK-dependent. We observed similar results using Pseudomonas aeruginosa, which expresses a related T3SS and the actin-targeting effector ExoT. As the NF-κB response of HEK293T cells to effectorless Yersinia has been used both as a screening tool for chemical inhibitors of the T3SS and for bacterial forward genetic screens, a better understanding of this response is important for tool optimization and interpretation.
Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, United States of America.
Miles C
MC
Duncan
Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, United States of America.
Natalia G
NG
Herrera
Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, United States of America.
Kevin S
KS
Johnson
Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America.|Department of Medicine, University of California San Francisco, San Francisco, California, United States of America.
Joanne N
JN
Engel
Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, United States of America.
Victoria
V
Auerbuch
D000199:Actins / Q000378:metabolism; D018407:Bacterial Physiological Phenomena; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D004789:Enzyme Activation; D057809:HEK293 Cells; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D000069296:Type III Secretion Systems; D000097782:NF-kappaB-Inducing Kinase
D000199:Actins; D016328:NF-kappa B; D017346:Protein Serine-Threonine Kinases; D000069296:Type III Secretion Systems; D000097782:NF-kappaB-Inducing Kinase