Cutting edge: direct interaction of TLR4 with NAD(P)H oxidase 4 isozyme is essential for lipopolysaccharide-induced production of reactive oxygen species and activation of NF-kappa B.
LPS, the primary constituent of the outer membrane of Gram-negative bacteria, is recognized by TLR4. Binding of TLR4 to LPS triggers various cell signaling pathways including NF-kappaB activation and reactive oxygen species (ROS) production. In this study, we present the data that LPS-induced ROS generation and NF-kappaB activation are mediated by a direct interaction of TLR4 with (NAD(P)H oxidase 4 (Nox) 4), a protein related to gp91phox (Nox2) of phagocytic cells, in HEK293T cells. Yeast two hybrid and GST pull-down assays indicated that the COOH-terminal region of Nox4 interacted with the cytoplasmic tail of TLR4. Knockdown of Nox4 by transfection of small interference RNA specific to the Nox4 isozyme in HEK293T cells expressing TLR4 along with MD2 and CD14 resulted in inhibition of LPS-induced ROS generation and NF-kappaB activation. Taken together, these results indicate that direct interaction of TLR4 with Nox4 is involved in LPS-mediated ROS generation and NF-kappaB activation.
Park
Hye Sun
HS
Division of Molecular Life Sciences, Center for Cell Signaling Research, Ewha Womans University, Seoul, Korea.
Jung
Hye Young
HY
Park
Eun Young
EY
Kim
Jaesang
J
Lee
Won Jae
WJ
Bae
Yun Soo
YS
D002460:Cell Line; D006801:Humans; D007527:Isoenzymes / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014162:Transfection; D020298:U937 Cells
D007527:Isoenzymes; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D011956:Receptors, Cell Surface; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human