Project Details
Projekt
Identification and characterization of RNA modifications with immune-modulatory properties acting on Toll-like receptors
Subject Area
Biological and Biomimetic Chemistry
Immunology
Immunology
Term
from 2018 to 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 404931941
Self/foreign discrimination by the innate immune system depends on recognition receptors which identify molecular patterns as associated to pathogens. Among others, this group includes endosomal toll-like receptors, among which TLR7, 8 and 13 recognize and discriminate mammalian from microbial, potentially pathogen-associated, 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 within a defined sequence context acted as antagonist thus suppressing TLR7-mediated interferon responses even in the presence of otherwise stimulatory RNA. The present project aims at the identification of further modifications that affect TLR-mediated immune responses. Subfractionated tRNA preparations showing differential activity in an ELISA based immunostimulation assay serve as starting point for the isolation of single, non-stimulatory tRNA species. Within such tRNAs, the relevant modifications can be identified via synthesis and testing of so-called modivariants, which are tRNAs carrying only a single or a subset of the naturally occurring modifications. This approach recently yielded a new non-stimulatory modification. This modification, namely Tm, displays a ribose methylation but, despite this similarity, is significantly less active than Gm. We therefore propose to 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. With an eye to aspects of innate immune responses in different biological systems, including immune-evasion during infection and induction of autoimmunity, we also propose to use and generate knock-outs that lack ribose-methylating enzymatic activity in order to study the biological impact of RNA modifications in vivo.
DFG Programme
Priority Programmes
