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J. Biol. Chem., Vol. 283, Issue 34, 23419-23428, August 22, 2008

This Article Full Text Full Text (PDF) All Versions of this Article: 283/34/23419    most recent M802967200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Ozsoy, H. Z. Articles by Mann, D. L. PubMed PubMed Citation Articles by Ozsoy, H. Z. Articles by Mann, D. L. Social Bookmarking                      What's this?

Oxidative Stress Promotes Ligand-independent and Enhanced Ligand-dependent Tumor Necrosis Factor Receptor Signaling^*

Hatice Z. Ozsoy, Natarajan Sivasubramanian, Eric D. Wieder, Steen Pedersen^¶, and Douglas L. Mann^¶1

From the Departments of Medicine and ^¶Molecular Physiology and Biophysics, Winters Center for Heart Failure Research, Section of Cardiology, Baylor College of Medicine, Houston, Texas 77030 and the Departments of Stem Cell Transplantation and Cellular Therapy and Pathology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030

Tumor necrosis factor (TNF) receptor 1 (TNFR1, p55) and 2 (TNFR2, p75) are characterized by several cysteine-rich modules in the extracellular domain, raising the possibility that redox-induced modifications of these cysteine residues might alter TNFR function. To test this possibility, we examined fluorescence resonance energy transfer (FRET) in 293T cells transfected with CFP- and YFP-tagged TNFRs exposed to the thiol oxidant diamide. Treatment with high concentrations of diamide (1 mM) resulted in an increase in the FRET signal that was sensitive to inhibition with the reducing agent dithiothreitol, suggesting that oxidative stress resulted in TNFR self-association. Treatment of cells with low concentrations of diamide (1 µM) that was not sufficient to provoke TNFR self-association resulted in increased TNF-induced FRET signals relative to the untreated cells, suggesting that oxidative stress enhanced ligand-dependent TNFR signaling. Similar findings were obtained when the TNFR1- and TNFR2-transfected cells were pretreated with a cell-impermeable oxidase, DsbA, that catalyzes disulfide bond formation between thiol groups on cysteine residues. The changes in TNFR self-association were functionally significant, because pretreating the HeLa cells and 293T cells resulted in increased TNF-induced NF-B activation and TNF-induced expression of IB and syndecan-4 mRNA levels. Although pretreatment with DsbA did not result in an increase in TNF binding to TNFRs, it resulted in increased TNF-induced activation of NF-B, consistent with an allosteric modification of the TNFRs. Taken together, these results suggest that oxidative stress promotes TNFR receptor self-interaction and ligand-independent and enhanced ligand-dependent TNF signaling.

Received for publication, April 17, 2008 , and in revised form, June 2, 2008.

^* This work was supported, in whole or in part, by National Institutes of Health Grants P50 HL-O6H, R01 HL58081, R01 HL61543, and HL42250. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: Faculty Center, 1709 Dryden Rd., BCM620, F.C. 9.83, Houston, TX 77030. E-mail: dmann{at}bcm.tmc.edu.

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