The alarmin IL-33 is a notch target in quiescent endothelial cells.
The molecular mechanisms that drive expression of the alarmin interleukin-33 (IL-33) in endothelial cells are unknown. Because nuclear IL-33 is a marker of endothelial cell quiescence (corroborated in this study by coexpression of cyclin-dependent kinase inhibitor p27(Kip1)), we hypothesized that Notch signaling might be involved in regulating IL-33 expression. Activation of Notch1 by immobilized Notch ligands was sufficient to induce nuclear IL-33 expression in cultured endothelial cells. Conversely, IL-33 expression was inhibited by the γ-secretase inhibitor DAPT or by inhibiting the function of Dll4, Jagged1, Notch1, or the canonical Notch transcription factor RBP-Jκ. Insensitivity to cycloheximide indicated that IL-33 was a direct target of Notch signaling, well in line with the identification of several conserved RBP-Jκ binding sites in the IL33 gene. The in vivo expression of Dll4 but not of Jagged1 was well correlated with expression of IL-33 in quiescent vessels, and subcutaneous injection of DAPT in healthy skin reduced IL-33 expression, indicating that Notch signaling was involved. On the other hand, loss of IL-33 during angiogenesis occurred despite sustained Dll4 and Notch1 expression, suggesting that other signals may override the IL-33-driving signal in this context. Taken together, our data demonstrate that endothelial nuclear IL-33 is induced by Notch and that Dll4 may be the dominant ligand responsible for this signaling in vivo.
Laboratory for Immunohistochemistry and Immunopathology, Department of Pathology, Oslo University Hospital, Norway.
Eirik
E
Sundlisaeter
Reidunn J
RJ
Edelmann
Johanna
J
Hol
Jon
J
Sponheim
Axel M
AM
Küchler
Miriam
M
Weiss
Irina A
IA
Udalova
Kim S
KS
Midwood
Monika
M
Kasprzycka
Guttorm
G
Haraldsen
D048868:Adaptor Proteins, Signal Transducing; D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D015415:Biomarkers / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004151:Dipeptides / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D056426:Genetic Loci / Q000235:genetics; D015894:Genome, Human / Q000235:genetics; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism; D006801:Humans; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D000067596:Interleukin-33; D007378:Interleukins / Q000235:genetics / Q000378:metabolism*; D000072100:Jagged-1 Protein; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D051881:Receptor, Notch1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000072099:Serrate-Jagged Proteins; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014945:Wound Healing / Q000187:drug effects
D048868:Adaptor Proteins, Signal Transducing; D015415:Biomarkers; D002135:Calcium-Binding Proteins; C424126:DLL4 protein, human; D004151:Dipeptides; C506536:IL33 protein, human; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D036341:Intercellular Signaling Peptides and Proteins; D000067596:Interleukin-33; D007378:Interleukins; C000606273:JAG1 protein, human; C000606275:Jag1 protein, rat; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; C419410:N-(N-(3,5-difluorophenacetyl)alanyl)phenylglycine tert-butyl ester; D051881:Receptor, Notch1; D000072099:Serrate-Jagged Proteins; D053829:Amyloid Precursor Protein Secretases