TIR (Toll/IL-1 receptor) domains mediate interactions between TLR (Toll-like) or IL-1 family receptors and signaling adapters. While homotypic TIR domain interactions mediate receptor activation they are also usurped by microbial TIR-domain containing proteins for immunosuppression. Here we show the role of a dimerized TIR domain platform for the suppression as well as for the activation of MyD88 signaling pathway. Coiled-coil dimerization domain, present in many bacterial TCPs, potently augments suppression of TLR/IL-1R signaling. The addition of a strong coiled-coil dimerization domain conferred the superior inhibition against the wide spectrum of TLRs and prevented the constitutive activation by a dimeric TIR platform. We propose a molecular model of MyD88-mediated signaling based on the dimerization of TIR domains as the limiting step.
COBISS.SI-ID: 5026586
In this article in the respected journal in the field of immunology, we reported the discovery of the mechanism of action antimalarials that are similar to quinacrin. In contrast to the prevailing opinion in literature we discovered that these inhibitors at therapeutic concentrations do not prevent endosomal acidification but directly bind to the nucleic acid. In this way they prevent the nucleic acid to activate endosomal TLRs such as TLR3, TLR7 and TLR9. The result is a significant particularly for the improvement of treatment of diseases characterized by activation of TLR9, 7, 8 and 3. The work was also presented as lecture: JERALA, Roman. Molecular mechanism of activation of Tool-like receptors in infection and chronic inflammation. Annual meeting of the Austrian society for allergology and immunology (ÖGAI), 2010. Vienna, 2010. [4577562]. Complementary publications: (1) PANTER, Gabriela, et al. Therapeutic applications of nucleic acids as ligands for toll-like receptors. Curr. opin. mol. ther. (Print), 2009, vol. 11, 133-145. [4121114]. (2) KUŽNIK, Alenka, et al. Recognition of nucleic acids by toll-like receptors and development of immunomodulatory drugs. Curr. med. chem., 2010, vol. 17, 16 [4351258].
COBISS.SI-ID: 2971761
Translocation of nucleic acid sensing Toll-like receptors (NAS TLRs) to endosomes is essential for response to microbial nucleic acids as well as for prevention of the autoimmune response. The accessory protein UNC93B1 is indispensable for activation of NAS TLRs since it regulates their response through trafficking to endosomes. We observed that poly(I:C) upregulates transcription of UNC93B1 and promotes trafficking of TLR3 to the plasma membrane in human epithelial cell line. Upregulation of UNC93B1 is triggered through TLR3 activation by poly(I:C). Further studies revealed that expression of UNC93B1 promotes trafficking of differentially glycosylated TLR3, but not other NAS TLRs, to the plasma membrane. Our findings identified TLR3 as the important regulator of UNC93B1 that in turn governs the responsiveness of all NAS TLRs.
COBISS.SI-ID: 5143066
Myristoylated alanine-rich C kinase substrate (MARCKS) is an intrinsically unfolded protein with a conserved cationic effector domain, which mediates the cross-talk between several signal transduction pathways. Transcription of MARCKS is increased by stimulation with bacterial LPS. We determined that MARCKS and MARCKS-related protein specifically bind to LPS and that the addition of the MARCKS effector heptapeptide inhibited LPS-induced production of TNF-a in mononuclear cells. After LPS stimulation, MARCKS moved from the plasma membrane to FYVE-positive endosomes, where it colocalized with LPS. MARCKS-deficient mouse embryonic fibroblasts (MEFs) responded to LPS with increased IL-6 production compared with the matched wild-type MEFs. TLR4 signalling was enhanced by the ablation of MARCKS, which had no effect on stimulation by TLR2, TLR3, and TLR5 agonists.
COBISS.SI-ID: 4930586
Synthetic scaffolds that permit spatial and temporal organization of enzymes in living cells are a promising post-translational strategy for controlling the flow of information in both metabolic and signaling pathways. Here, we describe the use of plasmid DNA as a stable, robust and configurable scaffold for arranging biosynthetic enzymes in the cytoplasm of Escherichia coli. This involved conversion of individual enzymes into custom DNA-binding proteins by genetic fusion to zinc-finger domains that specifically bind unique DNA sequences. When expressed in cells that carried a rationally designed DNA scaffold comprising corresponding zinc finger binding sites, the titers of diverse metabolic products, including resveratrol, 1,2-propanediol and mevalonate were increased as a function of the scaffold architecture. These results highlight the utility of DNA scaffolds for assembling biosynthetic enzymes into functional metabolic structures.
COBISS.SI-ID: 4824602