Jiří František Potužník, Ondřej Nešuta, Anton Škríba, Barbora Voleníková, Maria-Bianca Mititelu, Flaminia Mancini, Valentina Serianni, Henri Fernandez, Kristína Spustová, Jana Trylčová, Pavel Vopalensky, Hana Cahová
Angewandte Chemie (International ed. in English) 2024 Feb 05The recent expansion of the field of RNA chemical modifications has changed our understanding of post-transcriptional gene regulation. Apart from internal nucleobase modifications, 7-methylguanosine was long thought to be the only eukaryotic RNA cap. However, the discovery of non-canonical RNA caps in eukaryotes revealed a new niche of previously undetected RNA chemical modifications. We are the first to report the existence of a new non-canonical RNA cap, diadenosine tetraphosphate (Ap4 A), in human and rat cell lines. Ap4 A is the most abundant dinucleoside polyphosphate in eukaryotic cells and can be incorporated into RNA by RNA polymerases as a non-canonical initiating nucleotide (NCIN). Using liquid chromatography-mass spectrometry (LC-MS), we show that the amount of capped Ap4 A-RNA is independent of the cellular concentration of Ap4 A. A decapping enzyme screen identifies two enzymes cleaving Ap4 A-RNA,NUDT2 and DXO, both of which also cleave other substrate RNAs in vitro. We further assess the translatability and immunogenicity of Ap4 A-RNA and show that although it is not translated, Ap4 A-RNA is recognized as self by the cell and does not elicit an immune response, making it a natural component of the transcriptome. Our findings open a previously unexplored area of eukaryotic RNA regulation. © 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.
Jiří František Potužník, Ondřej Nešuta, Anton Škríba, Barbora Voleníková, Maria-Bianca Mititelu, Flaminia Mancini, Valentina Serianni, Henri Fernandez, Kristína Spustová, Jana Trylčová, Pavel Vopalensky, Hana Cahová. Diadenosine Tetraphosphate (Ap4 A) Serves as a 5' RNA Cap in Mammalian Cells. Angewandte Chemie (International ed. in English). 2024 Feb 05;63(6):e202314951
PMID: 37934413
View Full Text