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Protein kinase Cdelta binds TIRAP/Mal to participate in TLR signaling

Miho Kubo-Murai1, Kaoru Hazeki, Naoe Sukenobu

  • 1The Division of Molecular Medical Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 734-8551, Japan.

Molecular Immunology
|December 13, 2006
PubMed

Insights

Protein kinase Cdelta (PKCdelta) binds TIRAP/Mal, an adaptor for Toll-like receptors (TLRs). This interaction is crucial for TLR2 and TLR4 signaling pathways, impacting immune responses.

Area of Science:

  • Immunology
  • Cell Signaling
  • Molecular Biology

Background:

  • Toll-like receptors (TLRs) are key components of the innate immune system, recognizing pathogen-associated molecular patterns.
  • TLR signaling involves adaptor proteins that bridge receptors to downstream signaling molecules.
  • TIRAP/Mal is a known adaptor protein for TLR2 and TLR4.

Purpose of the Study:

  • To investigate the interaction between TIRAP/Mal and protein kinase Cdelta (PKCdelta).
  • To determine the role of PKCdelta in TLR2 and TLR4 signaling pathways.

Main Methods:

  • Co-immunoprecipitation assays using TIRAP/Mal GST-fusion protein and a TIRAP/Mal antibody.
  • Analysis of truncation mutants of TIRAP/Mal to identify the binding domain.
  • Assessment of TLR2- and TLR4-mediated phosphorylation of p38 MAPK, IKK, and IkappaB in RAW264.7 cells following PKCdelta depletion.

Main Results:

  • TIRAP/Mal was found to bind to PKCdelta in macrophage and THP1 cell lysates.
  • The Toll-interleukin-1 receptor (TIR) domain of TIRAP/Mal was identified as the binding site for PKCdelta.
  • Depletion of PKCdelta abolished TLR2- and TLR4-induced phosphorylation of key signaling molecules including p38 MAPK, IKK, and IkappaB.

Conclusions:

  • PKCdelta directly binds to the TIR domain of TIRAP/Mal.
  • PKCdelta plays a critical role in facilitating TLR2 and TLR4 signaling pathways.
  • This interaction is essential for downstream inflammatory responses mediated by TLRs.

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