Disabled-2 is a negative immune regulator of lipopolysaccharide-stimulated Toll-like receptor 4 internalization and signaling

Sci Rep. 2016 Oct 17:6:35343. doi: 10.1038/srep35343.

Abstract

Toll-like receptor 4 (TLR4) plays a pivotal role in the host response to lipopolysaccharide (LPS), a major cell wall component of Gram-negative bacteria. Here, we elucidated whether the endocytic adaptor protein Disabled-2 (Dab2), which is abundantly expressed in macrophages, plays a role in LPS-stimulated TLR4 signaling and trafficking. Molecular analysis and transcriptome profiling of RAW264.7 macrophage-like cells expressing short-hairpin RNA of Dab2 revealed that Dab2 regulated the TLR4/TRIF pathway upon LPS stimulation. Knockdown of Dab2 augmented TRIF-dependent interferon regulatory factor 3 activation and the expression of subsets of inflammatory cytokines and interferon-inducible genes. Dab2 acted as a clathrin sponge and sequestered clathrin from TLR4 in the resting stage of macrophages. Upon LPS stimulation, clathrin was released from Dab2 to facilitate endocytosis of TLR4 for triggering the TRIF-mediated pathway. Dab2 functions as a negative immune regulator of TLR4 endocytosis and signaling, supporting a novel role for a Dab2-associated regulatory circuit in controlling the inflammatory response of macrophages to endotoxin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Adaptor Proteins, Vesicular Transport / metabolism*
  • Animals
  • Apoptosis Regulatory Proteins
  • Biotinylation
  • Clathrin / metabolism
  • Endotoxins
  • Inflammation
  • Lipopolysaccharides
  • Macrophages / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • RAW 264.7 Cells
  • RNA, Small Interfering / metabolism
  • Sepsis / microbiology
  • Signal Transduction
  • Toll-Like Receptor 4 / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • Adaptor Proteins, Vesicular Transport
  • Apoptosis Regulatory Proteins
  • Clathrin
  • Dab2 protein, mouse
  • Endotoxins
  • Lipopolysaccharides
  • RNA, Small Interfering
  • TICAM-1 protein, mouse
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4