Nové typy nekanonických RNA čepiček a jejich degradace pomocí NudiX enzymů

Abstract

(English) Currently, more than 170 RNA modifications are known in both prokaryotes and eukaryotes, but the role of many of them is not well understood. The 5' termini of eukaryotic mRNAs and certain viral RNAs are distinguished by a specific structure known as the 7-methylguanosine (m7 G) cap. This cap plays a crucial role in transcription, stability, and translation of mRNAs. The recent discovery of various non-canonical RNA caps, such as Nicotinamide adenine dinucleotide (NAD), Coenzyme A (CoA), Flavin adenine dinucleotide (FAD), and Dinucleoside polyphosphates (NpnNs)indifferentorganisms, has prompted areassessment of our understanding of RNA cap function and metabolism. My PhD project aimed to discover new dinucleoside polyphosphates (NpnNs) acting as 5' cap in mammalian cells and to investigate their degradation by certain mouse, human and plant NudiX enzymes. Using Liquid Chromatography-Mass Spectrometry (LC-MS) techniques, we identified four different Ap2Ns acting as 5' cap in mammalian cells: Ap2A, Ap2C, Ap2G and Ap2U. Moreover, we observed an increase in the concentration of Ap2A-RNA after exposing Expi293F cells to menadione, a molecule known to generate ROS-based cellular stress. Furthermore, considering the similarity between Ap2A-RNA and NAD-RNA, we identified two RNA decapping enzymes...