Funiculosin variants and phosphorylated derivatives promote innate immune responses via the Toll-like receptor 4/myeloid differentiation factor-2 complex

Naoki Okamoto, Keisuke Mizote, Hiroe Honda, Akinori Saeki, Yasuharu Watanabe, Tomomi Yamaguchi-Miyamoto, Ryutaro Fukui, Natsuko Tanimura, Yuji Motoi, Sachiko Akashi-Takamura, Tatsuhisa Kato, Shigeto Fujishita, Takahito Kimura, B. Umeharu Ohto, Toshiyuki Shimizu, Takatsugu Hirokawa, Kensuke Miyake, Koichi Fukase, Yukari Fujimoto, Yoshinori NagaiKiyoshi Takatsu

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


The Toll-like receptor 4 (TLR4)/myeloid differentiation factor- 2 (MD-2) complex is essential for LPS recognition and induces innate immune responses against Gram-negative bacteria. As activation of TLR4/MD-2 is also critical for the induction of adaptive immune responses, TLR4/MD-2 agonists have been developed as vaccine adjuvants, but their efficacy has not yet been ascertained. Here, we demonstrate that a funiculosin (FNC) variant, FNC-RED, and FNC-RED and FNC derivatives are agonists for both murine and human TLR4/MD-2. FNCRED induced nuclear factor-B (NF-B) activation via murine TLR4/MD-2, whereas FNC had no TLR4/MD-2 stimulatory activity. Biacore analysis revealed that FNC-RED binds to murine TLR4/MD-2 but not murine radioprotective 105 (RP105)/myeloid differentiation factor-1 (MD-1), another LPS sensor. FNC-RED induced CD14-independent expressions of pro-inflammatory cytokines and co-stimulatory molecules in murine macrophages and dendritic cells. In contrast, FNC-RED stimulation was reduced in CD14-dependent LPS responses, including dimerization and internalization of TLR4/MD-2 and IFN-κ expression. FNC-RED-induced IL-12p40 production from murine dendritic cells was dependent on NF-κ B but not MAPK pathway. In addition, fetal bovine serum augmented lipid A-induced NF-κ B activation but blocked FNC-RED-mediated responses. Two synthetic phosphate group-containing FNC-RED and FNC derivatives, FNC-RED-P01 and FNC-P01, respectively, activated human TLR4/MD-2, unlike FNC-RED. Finally, computational analysis revealed that this species-specific activation by FNC-REDandFNC-RED-P01resulted from differences in electrostatic surface potentials between murine and human TLR4/MD-2. We conclude that FNC-RED and its synthetic derivative represent a novel category of murine and human TLR4/MD-2 agonist.

Original languageEnglish
Pages (from-to)15378-15394
Number of pages17
JournalJournal of Biological Chemistry
Issue number37
Publication statusPublished - 2017 Sept 15

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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