Toll-like receptor 9 modulators
TLR9 is localized to endoplasmic reticulum and upon stimulation with a TLR9 ligand, is transported to a tubular lysosomal compartment as is CpG-DNA. Furthermore, it is shown that TLR9 and CpG-DNA directly bind. It was also found that the MyD88 translocates in response to activation of TLR9-mediated signaling. Methods of identifying compounds that affect translocation and activity of TLR9 and MyD88 are described.
1. A method of identifying a compound that modulates Toll-Like Receptor 9 (TLR9) signaling, the method comprising:
(a) providing a living cell that expresses a fluorescently-tagged TLR9 polypeptide;
(b) contacting the cell with a test compound, thereby providing a test sample;
(c) incubating the test sample under conditions and for a period of time, which conditions and period of time are sufficient for TLR9 polypeptide localization, translocation, and/or aggregation to occur in a reference sample that lacks the test compound; and
(d) detecting in said living cell one or more TLR9 polypeptide characteristics selected from the group consisting of: rate of TLR9 polypeptide localization, rate of TLR9 polypeptide translocation, and combinations thereof,
wherein a difference in the one or more TLR9 polypeptide characteristic characteristics in the test sample compared to the one or more TLR9 characteristic characteristics in the reference sample indicates that the test compound is a compound that modulates TLR9 signaling.
2. The method of claim 1 , wherein the test sample and reference sample further comprise a TLR9 ligand.
3. The method of claim 2 , wherein the TLR9 ligand is a CpG-DNA.
4. The method of claim 1 , wherein the TLR9 polypeptide is a fusion protein.
5. The method of claim 1 , wherein the TLR9 polypeptide is a fusion protein comprising a Yellow Fluorescent Protein (YFP), a Cyan Fluorescent Protein (CFP), Green Fluorescent Protein (GFP), Red Fluorescent Protein (RFP), or a fluorescent variant thereof.
6. The method of claim 1 , wherein said difference in one or more TLR9 polypeptide characteristics is a difference in the rate of TLR9 polypeptide localization.
7. The method of claim 1 , said difference in the one or more TLR9 polypeptide characteristics is a difference in the rate of TLR9 polypeptide translocation.
8. The method of claim 1 , wherein following step (c), the cell is fractionated and fractions are tested for the presence of TLR9 polypeptide.
9. The method of claim 1 , wherein the TLR9 polypeptide comprises a full-length TLR9 protein.
10. The method of claim 1 , wherein the TLR9 polypeptide comprises a fragment of TLR9 comprising one or more regions selected from the group consisting of: LRR region 1, LRR region 2; transmembrane domain; Toll/IL-1 Resistance (TIR) domain; a ligand binding domain; and a localization signal domain.
11. The method of claim 10 , wherein the ligand binding domain comprises one or more CXXC motifs.
12. The method of claim 11 , wherein the CXXC motif is CRRC (amino acids 255-258 of SEQ ID NO:1) or CMEC (amino acids 265-268 of SEQ ID NO:1).
13. The method of claim 1 , wherein the test compound is a modified CpG-DNA.