TRIM28/TIF1β and Fli-1 negatively regulate peroxynitrite generation via DUOX2 to decrease the shedding of membrane-bound fractalkine in human macrophages after exposure to substance P.
Abstract
The chemokine fractalkine is synthesized as a membrane-bound protein, but studies have shown that serum levels of soluble fractalkine are elevated in inflammatory and autoimmune diseases. Patients with autoimmune diseases also have increased serum levels of neuropeptide substance P (SP). The shedding activity of the ADAM family is induced by peroxynitrite, but that of SP is unclear. Treatment of human macrophages with SP upregulated levels of membrane-bound fractalkine. Interestingly, small interfering RNA (siRNA) for DUOX2 further increased membrane-bound fractalkine but decreased soluble fractalkine compared with cells treated with SP alone. SP induced nitric oxide 2/inducible nitric oxide synthase (NOS2/iNOS) mRNA and increased levels of nitrotyrosine, a biomarker of peroxynitrite, whereas transfection with DUOX2 siRNA blunted upregulation of nitrotyrosine. Most importantly, N(ω)-nitro-L-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor) decreased protein levels of nitrotyrosine and concomitantly increased expression of membrane-bound fractalkine after exposure to SP. As for the signaling pathway of TGFβ1 (an inhibitor of iNOS mRNA expression), silencing of RNA for TAK-1 upregulated membrane-bound fractalkine,...Continue Reading
References
TRIM28 Is an E3 Ligase for ARF-Mediated NPM1/B23 SUMOylation That Represses Centrosome Amplification
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