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A combinatorial F box protein directed pathway controls TRAF adaptor stability to regulate inflammation

Nature Immunology volume 14, pages 470479 (2013) | Download Citation


Uncontrolled activation of tumor necrosis factor receptor–associated factor (TRAF) proteins may result in profound tissue injury by linking surface signals to cytokine release. Here we show that a ubiquitin E3 ligase component, Fbxo3, potently stimulates cytokine secretion from human inflammatory cells by destabilizing a sentinel TRAF inhibitor, Fbxl2. Fbxo3 and TRAF protein in circulation positively correlated with cytokine responses in subjects with sepsis, and we identified a polymorphism in human Fbxo3, with one variant being hypofunctional. A small-molecule inhibitor targeting Fbxo3 was sufficient to lessen severity of cytokine-driven inflammation in several mouse disease models. These studies identified a pathway of innate immunity that may be useful to detect subjects with altered immune responses during critical illness or provide a basis for therapeutic intervention targeting TRAF protein abundance.

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We thank A. Lagneaux and S. Barge for assistance with studies. This material is based upon work supported, in part, by the US Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Biomedical Laboratory Research and Development. This work was supported by a Merit Review Award from the US Department of Veterans Affairs and National Institutes of Health R01 grants HL096376, HL097376, HL081784, HL068135 and HL098174 (to R.K.M.), HL116472 (to B.B.C.), HL01916 (to Y.Z.) and P50HL084948 (F.C.S.), American Heart Association awards 12SDG9050005 (to J.Z.) and 12SDG12040330 (to C.Z.), and American Heart Association Grant-in-Aid 12GRNT11820019 (B.J.M.). The contents presented do not represent the views of the Department of Veterans Affairs or the United States Government.

Author information


  1. Department of Medicine, Acute Lung Injury Center of Excellence, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.

    • Bill B Chen
    • , Tiffany A Coon
    • , Jennifer R Glasser
    • , Bryan J McVerry
    • , Jing Zhao
    • , Yutong Zhao
    • , Chunbin Zou
    • , Bryon Ellis
    • , Frank C Sciurba
    • , Yingze Zhang
    •  & Rama K Mallampalli
  2. Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.

    • Rama K Mallampalli
  3. Medical Specialty Service Line, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, Pennsylvania, USA.

    • Rama K Mallampalli


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R.K.M. and B.B.C. jointly oversaw the studies. B.B.C. designed the study, performed experiments, analyzed the data and wrote the manuscript; T.A.C., J.R.G., J.Z, Y.Z. and C.Z. performed experiments and assisted with animal experiments; B.J.M., B.E., F.C.S. and Y.Z. assisted with human studies. R.K.M. revised the manuscript and directed the study.

Competing interests

A provisional patent application (US 61/657,423) covering Fbxo3 inhibitors and additional modifications was filed jointly through the United States Department of Veterans Affairs and the University of Pittsburgh.

Corresponding authors

Correspondence to Bill B Chen or Rama K Mallampalli.

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