Src kinase participates in LPS-induced activation of NADPH oxidase.
The production of superoxide from NADPH oxidase by macrophages in response to endotoxin (LPS) is an important innate immune response, yet it is not clear how LPS signals the activation of NADPH oxidase. The hypothesis is that LPS-induced src kinase and PI3 kinase (PI3K) facilitates the activation of p47(phox), the regulatory subunit of NADPH oxidase. In mouse macrophage RAW264.7 cells, inhibition of src tyrosine family kinases inhibited LPS-induced activation of NADPH oxidase, phosphorylation of p47(phox), activation of PI3K and phosphorylation of the TLR4. Moreover, inhibition of LPS-induced increases in intracellular calcium blunted src kinase activation, PI3K association with TLR4, as well as PI3 kinase activation. These data suggest that both src kinase and PI3 kinase are involved in LPS-induced NADPH oxidase activation. Importantly, these data suggest that LPS-induced src kinase activation is critical for PI3 kinase activation as well as TLR4 phosphorylation and is dependent upon LPS-induced increase in intracellular calcium. These signaling events fill critical gaps in our understanding of LPS-induced free radical production as well as may potentially responsible for the mechanism of innate immune tolerance or desensitization caused by steroids or ethanol.
Check
Jennifer
J
Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
Byrd
Christy L
CL
Menio
Jade
J
Rippe
Richard A
RA
Hines
Ian N
IN
Wheeler
Michael D
MD
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002614:Chelating Agents / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology; D051379:Mice; D019255:NADPH Oxidases / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D002118:Calcium; D002614:Chelating Agents; D008070:Lipopolysaccharides; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D013481:Superoxides; D051197:Toll-Like Receptor 4; D019061:src-Family Kinases; C060505:neutrophil cytosolic factor 1