title: TAK-242 (resatorvid), a small-molecule inhibitor of Toll-like receptor (TLR) 4 signaling, binds selectively to TLR4 and interferes with interactions between TLR4 and its adaptor molecules.
abstract: TAK-242 (resatorvid), a small-molecule-specific inhibitor of Toll-like receptor (TLR) 4 signaling, inhibits the production of lipopolysaccharide-induced inflammatory mediators by binding to the intracellular domain of TLR4. Cys747 in TLR4 has been identified previously as the binding site of TAK-242. However, the mechanism by which TAK-242 inhibits TLR4 signaling after binding to TLR4 remains unknown. The present study demonstrated, using coimmunoprecipitation, that TAK-242 interferes with protein-protein interactions between TLR4 and its adaptor molecules. Among 10 different human TLRs, TAK-242 selectively bound to TLR4. The time course of the inhibitory effect of TAK-242 on inflammatory mediator production corresponded to that of the binding of TAK-242 to TLR4. TAK-242 inhibited the association of TLR4 with Toll/interleukin-1 receptor domain-containing adaptor protein (TIRAP) or Toll/interleukin-1 receptor domain-containing adaptor protein inducing interferon-β-related adaptor molecule (TRAM) in human embryonic kidney (HEK) 293 cells overexpressing TLR4, MD-2, and TIRAP or TRAM, respectively. TAK-242 inhibited the TIRAP-mediated activation of nuclear factor κB (NF-κB) and the TRAM-mediated activation of NF-κB and interferon-sensitive response element in HEK293 cells stably expressing TLR4, MD-2, and CD14. The activation of endogenous interleukin-1 receptor-associated kinase in RAW264.7 cells was also inhibited by TAK-242 treatment. These findings suggest that TAK-242 binds selectively to TLR4 and subsequently disrupts the interaction of TLR4 with adaptor molecules, thereby inhibiting TLR4 signal transduction and its downstream signaling events. This work proposes a novel paradigm of a small molecule capable of disrupting protein-protein interactions.
authors.affiliation: Pharmacology Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Osaka, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Matsunaga
authors.forename: Noboru
authors.initials: N
authors.lastname: Tsuchimori
authors.forename: Tatsumi
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ii
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013449:Sulfonamides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D013449:Sulfonamides; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; C507035:ethyl 6-(N-(2-chloro-4-fluorophenyl)sulfamoyl)cyclohex-1-ene-1-carboxylate