Identification of BCAP-L as a negative regulator of the TLR signaling-induced production of IL-6 and IL-10 in macrophages by tyrosine phosphoproteomics

Takayuki Matsumura, Masaaki Oyama, Hiroko Kozuka-Hata, Kosuke Ishikawa, Takafumi Inoue, Tatsushi Muta, Kentaro Semba, Jun ichiro Inoue

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


Toll-like receptor (TLR) signaling in macrophages is essential for anti-pathogen responses such as cytokine production and antigen presentation. Although numerous reports suggest that protein tyrosine kinases (PTKs) are involved in cytokine induction in response to lipopolysaccharides (LPS; TLR4 ligand) in macrophages, the PTK-mediated signal transduction pathway has yet to be analyzed in detail. Here, we carried out a comprehensive and quantitative dynamic tyrosine phosphoproteomic analysis on the TLR4-mediated host defense system in RAW264.7 macrophages using stable isotope labeling by amino acids in cell culture (SILAC). We determined the temporal profiles of 25 proteins based on SILAC-encoded peptide(s). Of these, we focused on the tyrosine phosphorylation of B-cell adaptor for phosphatidylinositol 3-kinase (BCAP) because the function of BCAP remains unknown in TLR signaling in macrophages. Furthermore, Bcap has two distinct transcripts, a full-length (Bcap-L) and an alternatively initiated or spliced (Bcap-S) mRNA, and little is known about the differential functions of the BCAP-L and BCAP-S proteins. Our study showed, for the first time, that RNAi-mediated selective depletion of BCAP-L enhanced IL-6 and IL-10 production but not TNF-α production in TLR ligand-stimulated macrophages. We propose that BCAP-L (but not BCAP-S) is a negative regulator of the TLR-mediated host defense system in macrophages.

Original languageEnglish
Pages (from-to)265-270
Number of pages6
JournalBiochemical and biophysical research communications
Issue number2
Publication statusPublished - 2010 Sep


  • BCAP
  • Cytokine
  • LPS
  • Macrophage
  • TLR

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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