Downregulation by lipopolysaccharide of Notch signaling, via nitric oxide.
The Notch signaling pathway appears to perform an important function in inflammation. Here, we present evidence to suggest that lipopolysaccharide (LPS) suppresses Notch signaling via the direct modification of Notch by the nitration of tyrosine residues in macrophages. In the RAW264.7 macrophage cell line and in rat primary alveolar macrophages, LPS was found to inhibit Notch1 intracellular domain (Notch1-IC) transcription activity, which could then be rescued by treatment with N(G)-nitro-l-arginine, a nitric oxide synthase (NOS) inhibitor. Nitric oxide (NO), which was produced in cells that stably express endothelial NOS (eNOS) and brain NOS (bNOS), also induced the inhibition of Notch1 signaling. The NO-induced inhibition of Notch1 signaling remained unchanged after treatment with 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one (ODQ), a guanylyl-cyclase inhibitor, and was not found to be mimicked by 8-bromo-cyclic GMP in the primary alveolar macrophages. With regards to the control of Notch signaling, NO appears to have a significant negative influence, via the nitration of Notch1-IC, on the binding that occurs between Notch1-IC and RBP-Jk, both in vitro and in vivo. By intrinsic fluorescence, we also determined that nitration could mediate conformational changes of Notch1-IC. The substitution of phenylalanine for tyrosine at residue 1905 in Notch1-IC abolished the nitration of Notch1-IC by LPS. Overall, our data suggest that an important relationship exists between LPS-mediated inflammation and the Notch1 signaling pathway, and that this relationship intimately involves the nitration of Notch1-IC tyrosine residues.
Kim
Mi-Yeon
MY
Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Buk-Ku, Gwangju, Republic of Korea.
Park
Ji-Hye
JH
Mo
Jung-Soon
JS
Ann
Eun-Jung
EJ
Han
Seung-Ok
SO
Baek
Sang-Hyun
SH
Kim
Kyoung-Jin
KJ
Im
Suhn-Young
SY
Park
Jeen-Woo
JW
Choi
Eui-Ju
EJ
Park
Hee-Sae
HS
D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects*; D006801:Humans; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D009569:Nitric Oxide / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D051881:Receptor, Notch1 / Q000737:chemistry / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects*; D013347:Subcellular Fractions / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D008070:Lipopolysaccharides; D051881:Receptor, Notch1; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D006152:Cyclic GMP