Natural small molecule FMHM inhibits lipopolysaccharide-induced inflammatory response by promoting TRAF6 degradation via K48-linked polyubiquitination

Sci Rep. 2015 Oct 1:5:14715. doi: 10.1038/srep14715.

Abstract

TNF receptor-associated factor 6 (TRAF6) is a key hub protein involved in Toll-like receptor-dependent inflammatory signaling pathway, and it recruits additional proteins to form multiprotein complexes capable of activating downstream NF-κB inflammatory signaling pathway. Ubiquitin-proteasome system (UPS) plays a crucial role in various protein degradations, such as TRAF6, leading to inhibitory effects on inflammatory response and immunologic function. However, whether ubiquitination-dependent TRAF6 degradation can be used as a novel anti-inflammatory drug target still remains to be explored. FMHM, a bioactive natural small molecule compound extracted from Chinese herbal medicine Radix Polygalae, suppressed acute inflammatory response by targeting ubiquitin protein and inducing UPS-dependent TRAF6 degradation mechanism. It was found that FMHM targeted ubiquitin protein via Lys48 site directly induced Lys48 residue-linked polyubiquitination. This promoted Lys48 residue-linked polyubiquitin chain formation on TRAF6, resulting in increased TRAF6 degradation via UPS and inactivation of downstream NF-κB inflammatory pathway. Consequently, FMHM down-regulated inflammatory mediator levels in circulation, protected multiple organs against inflammatory injury in vivo, and prolong the survival of endotoxemia mouse models. Therefore, FMHM can serve as a novel lead compound for the development of TRAF6 scavenging agent via ubiquitination-dependent mode, which represents a promising strategy for treating inflammatory diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / pharmacology*
  • Biological Products / pharmacology*
  • Cell Line
  • Cytokines / metabolism
  • Disease Models, Animal
  • Drugs, Chinese Herbal / pharmacology*
  • Endotoxemia / drug therapy
  • Endotoxemia / etiology
  • Endotoxemia / metabolism
  • Inflammation / drug therapy
  • Inflammation / etiology
  • Inflammation / metabolism*
  • Inflammation Mediators / metabolism
  • Lipopolysaccharides / adverse effects
  • Lipopolysaccharides / immunology
  • Mice
  • Myeloid Differentiation Factor 88 / metabolism
  • NF-kappa B
  • Nitric Oxide / metabolism
  • Protein Binding
  • Proteolysis
  • Signal Transduction / drug effects
  • TNF Receptor-Associated Factor 6 / metabolism*
  • Toll-Like Receptor 4 / metabolism
  • Ubiquitin / metabolism
  • Ubiquitin-Conjugating Enzymes / metabolism
  • Ubiquitination / drug effects*

Substances

  • Anti-Inflammatory Agents
  • Biological Products
  • Cytokines
  • Drugs, Chinese Herbal
  • Inflammation Mediators
  • Lipopolysaccharides
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • TNF Receptor-Associated Factor 6
  • Toll-Like Receptor 4
  • Ubiquitin
  • Nitric Oxide
  • Ubiquitin-Conjugating Enzymes