Research ArticlePHARMACOLOGY

Specific activation of the TLR1-TLR2 heterodimer by small-molecule agonists

Science Advances  10 Apr 2015:
Vol. 1, no. 3, e1400139
DOI: 10.1126/sciadv.1400139

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Abstract

Toll-like receptor (TLR) agonists activate both the innate and the adaptive immune systems. These TLR agonists have been exploited as potent vaccine adjuvants and antitumor agents. We describe the identification and characterization of a small molecule, N-methyl-4-nitro-2-(4-(4-(trifluoromethyl)phenyl)-1H-imidazol-1-yl)aniline (CU-T12-9), that directly targets TLR1/2 to initiate downstream signaling. CU-T12-9 specifically induces TLR1/2 activation, which can be blocked by either the anti-hTLR1 or the anti-hTLR2 antibody, but not the anti-hTLR6 antibody. Using a variety of different biophysical assays, we have demonstrated the binding mode of CU-T12-9. By binding to both TLR1 and TLR2, CU-T12-9 facilitates the TLR1/2 heterodimeric complex formation, which in turn activates the downstream signaling. Fluorescence anisotropy assays revealed competitive binding to the TLR1/2 complex between CU-T12-9 and Pam3CSK4 with a half-maximal inhibitory concentration (IC50) of 54.4 nM. Finally, we showed that CU-T12-9 signals through nuclear factor κB (NF-κB) and invokes an elevation of the downstream effectors tumor necrosis factor–α (TNF-α), interleukin-10 (IL-10), and inducible nitric oxide synthase (iNOS). Thus, our studies not only provide compelling new insights into the regulation of TLR1/2 signaling transduction but also may facilitate future therapeutic developments.

Keywords
  • toll-like receptors
  • drug discovery
  • vaccine adjuvant
  • chemical probes

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

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