Listeriolysin O secreted by Listeria monocytogenes induces NF-kappaB signalling by activating the IkappaB kinase complex.
Listeriolysin O (LLO) is a pore-forming cytolysin secreted by the pathogen Listeria monocytogenes and is required for its intracellular survival. We recently demonstrated that in endothelial cells, LLO activates the NF-kappaB signalling pathway. In this work, we studied the LLO-induced molecular cascade of NF-kappaB activation with a cellular model extensively used to analyse the signalling pathway of NF-kappaB activation, i.e. the human embryonic kidney HEK-293 cell line and its derivatives (transfectants or mutants). When the stably transfected derivative HEK-293 cells expressing IL-1RI were exposed to LLO, a strong NF-kappaB activation was detected, contrasting with other cell lines (HEK-293 wild type, HEK-293.T and COS) expressing a very low level of IL-1RI. Although a delayed kinetics of LLO-dependent NF-kappaB activation suggests an autocrine or paracrine IL-1-dependent pathway, we found that LLO-dependent NF-kappaB activation did not require the IL-1 protein synthesis nor the interaction with the IL-1RI specific receptor. Herein, we demonstrated that LLO-dependent NF-kappaB activation requires the activation of the IkappaB kinase beta (IKKbeta) subunit of IKK complex to phosphorylate and degrade cytoplasmic IkappaBalpha, a natural inhibitor of NF-kappaB. The activation induced by LLO does not require the adapters MyD88 and IL-1R-associated kinase (IRAK). We suggested that LLO induces a distinct signalling pathway from that of IL-1 and its receptor.
Kayal
Samer
S
Laboratoire de Microbiologie, INSERM U-411, Faculté de Médecine Necker, 75730 Paris Cedex 15, France. kayal@necker.fr
Lilienbaum
Alain
A
Join-Lambert
Olivier
O
Li
Xiaoxia
X
Israël
Alain
A
Berche
Patrick
P
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D001427:Bacterial Toxins / Q000378:metabolism; D002460:Cell Line; D003513:Cycloheximide / Q000378:metabolism; D005434:Flow Cytometry; D017930:Genes, Reporter; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006460:Hemolysin Proteins / Q000378:metabolism; D006801:Humans; D051550:I-kappa B Kinase; D007375:Interleukin-1 / Q000378:metabolism; D008089:Listeria monocytogenes / Q000378:metabolism*; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D007375:Interleukin-1; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D011500:Protein Synthesis Inhibitors; D011971:Receptors, Immunologic; D003513:Cycloheximide; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C038705:hlyA protein, Listeria monocytogenes