Ruprecht-Karls-Universit├Ąt Heidelberg
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Dalpke0118 - Scientist (f/m) / PhD position
Project no:
Dalpke0118

Project leader:

Project supervisor:
Dalpke, Alexander
Application deadline:
19. Aug 2018
Start of PhD project:
1. Oct 2018

Project description:

Title:
Identification and characterization of RNA modifications with immune-modulatory properties acting on Toll-like receptors
Summary:
Self/foreign discrimination by the innate immune system depends on receptors which identify molecular patterns. Among others, this group includes TLR7, 8 and 13 that discriminate mammalian from microbial RNA. One of the discriminatory principles is the recognition of endogenous RNA modifications. Our previous work has identified Gm, a naturally occurring ribose-methylation within tRNA that not only avoided TLR7 recognition but acted as antagonist thus suppressing TLR7-mediated interferon responses. The present project aims at the identification of further modifications that affect TLR-mediated immune responses. Sub-fractionated tRNA preparations showing differential activity in an immune-stimulation assay serve as starting point for the isolation of single, non-stimulatory tRNA species. Within such tRNAs, the relevant modifications will be identified via synthesis (this is done by a cooperation partner) and testing of so-called modivariants, which are tRNAs carrying only a single or a subset of the naturally occurring modifications. We will also vary systematically the nucleobase structure of a ribose-methylated nucleoside within oligoribonucleotides, in order to delineate which atomic details govern the dampening effect on TLR7-mediated interferon response to RNA. To approach physiological effects, we will analyze expression levels of relevant methyltransferases, and stimuli changing the latter. To study innate immune responses in different biological systems, including immune-evasion during infection and induction of autoimmunity, we will use and generate knock-outs that lack ribose-methylating enzymatic activity.
References:
1. Schmitt, F.C.F., Freund, I., Weigand, M.A., Helm, M., Dalpke, A.H., Eigenbrod, T. (2017). Identification of an optimized 2'-O-methylated tri-nucleotide RNA motif inhibiting Toll-like receptor 7 and 8, RNA 23(9):1344-1351

2. Rimbach, K., Kaiser, S., Helm, M., Dalpke, A.H., Eigenbrod, T. (2015). 2'-O-Methylation within Bacterial RNA Acts as Suppressor of TLR7/TLR8 Activation in Human Innate Immune Cells. Journal of Innate Immunity. 7(5):482-93

3. Kaiser, S.*, Rimbach, K.*, Eigenbrod, T., Dalpke, A.H. & Helm, M. (2014). A modified dinucleotide motif specifies tRNA recognition by TLR7. RNA 20(9):1351-5

4. Dalpke A, and Helm M (2012): RNA mediated Toll-like receptor stimulation in health and disease. RNA Biol. 9(6): 828-43

5. Gehrig, S., Eberle, M.-E., Botschen, F., Rimbach, K., Eberle, F., Eigenbrod, T., Kaiser, S., Holmes, W.M., Erdmann, V.A., Sprinzl, V.A., Bec, G., Keith, G., Dalpke, A.H. * &Helm, M.* (2012). Identification of modifications in microbial, native tRNA that suppress immunostimulatory activity. J. Exp. Med. 209(2):225-33; *equal contribution
Methods that will be used:
CRISPR/Cas9, in vitro and in vivo infection, cultivation of primary immune cells, magnetic cell sorting, cytokine measurement, confocal microscopy
Cooperation partners:
Prof. Mark Helm, Mainz University
Personal qualifications:
background in immunology, sense of biological chemistry, self-reliance, willingness to work in a close cooperation
Keywords:
Innate immunity, RNA immunostimulation, biological chemistry, infection&immunity