A Small Molecule Ubiquitination Inhibitor Blocks NF-κB-dependent Cytokine Expression in Cells and Rats
A small molecule inhibitor of NF-κB-dependent cytokine expression was discovered that blocked tumor necrosis factor (TNF) α-induced IκBα degradation in MM6 cells but not the degradation of β-catenin in Jurkat cells. Ro106-9920 blocked lipopolysaccharide (LPS)-dependent expression of TNFα, inte...
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Veröffentlicht in: | The Journal of biological chemistry 2002-06, Vol.277 (26), p.23573 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | A small molecule inhibitor of NF-κB-dependent cytokine expression was discovered that blocked tumor necrosis factor (TNF)
α-induced IκBα degradation in MM6 cells but not the degradation of β-catenin in Jurkat cells. Ro106-9920 blocked lipopolysaccharide
(LPS)-dependent expression of TNFα, interleukin-1β, and interleukin-6 in fresh human peripheral blood mononuclear cells with
IC 50 values below 1 μ m . Ro106-9920 also blocked TNFα production in a dose-dependent manner following oral administration in two acute models of
inflammation (air pouch and LPS challenge). Ro106-9920 was observed to inhibit an ubiquitination activity that does not require
βTRCP but associates with IκBα and will ubiquitinate IκBα S32E,S36E (IκBαee) specifically at lysine 21 or 22. Ro106-9920 was
identified in a cell-free system as a time-dependent inhibitor of IκBαee ubiquitination with an IC 50 value of 2.3 ± 0.09 μ m . The ubiquitin E3 ligase activity is inhibited by cysteine-alkylating reagents, supported by E2UBCH7, and requires cIAP2
or a cIAP2-associated protein for activity. These activities are inconsistent with what has been reported for SCF βTRCP , the putative E3 for IκBα ubiquitination. Ro106-9920 was observed to be selective for IκBαee ubiquitination over the ubiquitin-activating
enzyme (E1), E2UBCH7, nonspecific ubiquitination of cellular proteins, and 97 other molecular targets. We propose that Ro106-9920
selectively inhibits an uncharacterized but essential ubiquitination activity associated with LPS- and TNFα-induced IκBα degradation
and NF-κB activation. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M200842200 |