Immunorecognition of viral nucleic acids in the cytosol
Final Report Abstract
Detection of viruses by the innate immune system, and the subsequent antiviral type I interferon (IFN) response hinge on the recognition of viral nucleic acids by germline encoded receptors at specific cellular locations. In endosomes, sensing of RNA and DNA structures is mediated by members of the toll-like receptor (TLR) family, TLR3, 7, 8 and 9. In the cytosol, the helicases RIG-I and MDA-5 recognize RNA structures, while viral DNA is detected by cGAMP synthase (cGAS). Based on our previous finding that sensing of double stranded RNA mimetic poly (I:C), as well as of picornaviruses was mediated by MDA-5, the Emmy Noether proposal aimed at studying the immune biology of MDA-5. We recently contributed to establishing a role for MDA-5 dependent RNA detection of MERS virus. We unexpectedly observed that also the immune sensing of non-viral pathogens including candida and liver stage plasmodial infection were mediated by MDA-5. Accordingly we found that MDA-5 stimulatory structures resided also in non-viral and non-replicative single stranded RNAs. However, despite our and other groups continued efforts, the minimal RNA structure able to activate MDA-5 still remains undefined. This limitation made it necessary to widen the focus of the group to also include work on the cytosolic nucleic acid receptors RIG-I and cGAS. We therefore studied the contribution of RIG-I to the recognition of bacterial RNA, and of RNA from viruses containing 5’ diphosphate instead of 5’ triphosphate termini. While cGAS senses cytosolic DNA independent of the sequence via cooperative interactions with the phosphate backbone, we uncovered an immunological role for oxidative DNA modifications. Oxidative DNA damage enhanced the response to cytosolic DNA by preventing its degradation by the cytosolic exonuclease TREX1. In addition, we helped define the non-canonically linked 2’3’-cGAMP as the second messenger synthetized by cGAS, and established the structure-functional basis why human STING alleles in contrast to mouse STING are largely unresponsive to both bacterial cyclic dinucleotides (CDN), as well as to the experimental antiviral drug DMXAA. In the process, and with the notable exception of MDA-5, we established a portfolio of defined and selective small molecule and/or nucleic acid agonists for the nucleic acid receptors of the innate immune system. These lead compounds form the basis for our future translational development of their use in the immunotherapy of cancer and chronic infections.
Publications
- (2010). Targeted activation of RNA helicase retinoic acid-inducible gene-I induces proimmunogenic apoptosis of human ovarian cancer cells. Cancer Research 70, 5293–5304
Kübler, K., Gehrke, N., Riemann, S., Böhnert, V., Zillinger, T., Hartmann, E., Pölcher, M., Rudlowski, C., Kuhn, W., Hartmann, G., and Barchet, W.
- (2011). Delivery with polycations extends the immunostimulant Ribomunyl into a potent antiviral Tolllike receptor 7/8 agonist. Antiviral Therapy 16, 751–758
Herberhold, S., Coch, C., Zillinger, T., Hommertgen, B., Busch, N., Schuberth, C., Hartmann, E., Wimmenauer, V., Hagmann, C.A., Lüdenbach, B., Schlee, M., Bootz, F., Hartmann, G., and Barchet, W.
- (2011). Immunogenic cell death of human ovarian cancer cells induced by cytosolic poly(I:C) leads to myeloid cell maturation and activates NK cells. Eur J Immunology 41, 3028–3039
Kübler, K., tho Pesch, C., Gehrke, N., Riemann, S., Daßler, J., Coch, C., Landsberg, J., Wimmenauer, V., Pölcher, M., Rudlowski, C., Tüting, T., Kuhn, W., Hartmann, G., and Barchet, W.
- (2011). Ribose 2'-O-methylation provides a molecular signature for the distinction of self and non-self mRNA dependent on the RNA sensor Mda5. Nature Immunology 12, 137–143
Züst, R., Cervantes-Barragan, L., Habjan, M., Maier, R., Neuman, B.W., Ziebuhr, J., Szretter, K.J., Baker, S.C., Barchet, W., Diamond, M.S., Siddell, S.G., Ludewig, B., and Thiel, V.
(See online at https://doi.org/10.1038/ni.1979) - (2013). Cyclic [G(2′,5′)pA(3′,5′)p] Is the Metazoan Second Messenger Produced by DNA-Activated Cyclic GMP-AMP Synthase. Cell 153, 1094–1107
Gao, P., Ascano, M., Wu, Y., Barchet, W., Gaffney, B.L., Zillinger, T., Serganov, A.A., Liu, Y., Jones, R.A., Hartmann, G., Tuschl, T., and Patel, D.J.
(See online at https://doi.org/10.1016/j.cell.2013.04.046) - (2013). Oxidative Damage of DNA Confers Resistance to Cytosolic Nuclease TREX1 Degradation and Potentiates STING-Dependent Immune Sensing. Immunity 39
Gehrke, N., Mertens, C., Zillinger, T., Wenzel, J., Bald, T., Zahn, S., Tüting, T., Hartmann, G., and Barchet, W.
(See online at https://doi.org/10.1016/j.immuni.2013.08.004) - (2014) Antiviral immunity via RIG-I-mediated recognition of RNA bearing 5'-diphosphates. Nature 514: 372–375 (JIF: 38.597)
Goubau D, Schlee M, Deddouche S, Pruijssers AJ, Zillinger T, Goldeck M, Schuberth C, Van der Veen AG, Fujimura T, Rehwinkel J, Iskarpatyoti JA, Barchet W, Ludwig J, Dermody TS, Hartmann G & Reis E Sousa C
(See online at https://doi.org/10.1038/nature13590) - (2014) Binding-Pocket and Lid-Region Substitutions Render Human STING Sensitive to the Species-Specific Drug DMXAA. Cell Reports 8: 1668–1676
Gao P, Zillinger T, Wang W, Ascano M, Dai P, Hartmann G, Tuschl T, Deng L, Barchet W & Patel DJ
(See online at https://doi.org/10.1016/j.celrep.2014.08.010) - (2014) Host-cell sensors for Plasmodium activate innate immunity against liver-stage infection. Nature Medicine 20: 47–53
Liehl P, Zuzarte-Luís V, Chan J, Zillinger T, Baptista F, Carapau D, Konert M, Hanson KK, Carret C, Lassnig C, Müller M, Kalinke U, Saeed M, Chora AF, Golenbock DT, Strobl B, Prudêncio M, Coelho LP, Kappe SH, Superti-Furga G, Pichlmair A, Vigário AM, Rice CM, Fitzgerald KA, Barchet W, and Mota MM
(See online at https://doi.org/10.1038/nm.3424) - (2013). Structure-Function Analysis of STING Activation by c[G(2',5')pA(3“,5”)p] and Targeting by Antiviral DMXAA. Cell 154, 748–762
Gao, P., Ascano, M., Zillinger, T., Wang, W., Dai, P., Serganov, A.A., Gaffney, B.L., Shuman, S., Jones, R.A., Deng, L., Hartmann, G., Barchet, W., Tuschl, T, and Patel, D.J.
(See online at https://doi.org/10.1016/j.cell.2013.07.023)
