Thiol-linked alkylation for the metabolic sequencing of RNA [SLAM-seq in wildtype and Mettl3 knockout mES cells]

Gene expression profiling by high-throughput sequencing reveals qualitative and quantitative changes in RNA species at steady-state but obscures the intracellular dynamics of RNA transcription, processing and decay. We developed thiol(SH)-linked alkylation for the metabolic sequencing of RNA (SLAM-seq), an orthogonal chemistry-based epitranscriptomics-sequencing technology that uncovers 4-thiouridine (s4U)-incorporation in RNA species at single-nucleotide resolution. In combination with well-established metabolic RNA labeling protocols and coupled to standard, low-input, high-throughput RNA sequencing methods, SLAM-seq enables rapid access to RNA polymerase II-dependent gene expression dynamics in the context of total RNA. When applied to mouse embryonic stem cells, SLAM-seq provides global and transcript-specific insights into pluripotency-associated gene expression. We validated the method by showing that the RNA-polymerase II-dependent transcriptional output scales with Oct4/Sox2/Nanog-defined enhancer activity; and provides quantitative and mechanistic evidence for transcript-specific RNA turnover mediated by post-transcriptional gene regulatory pathways initiated by microRNAs and N6-methyladenosine. SLAM-seq facilitates the dissection of fundamental mechanisms that control gene expression in an accessible, cost-effective, and scalable manner. Overall design: Wildtype (wt) mouse embryonic stem (mES) cells, clonal mES cells that had been transfected with non-targeting control guide RNAs (ctr), or Mettl3 depleted (Mettl3KO) mES cells were subjected to 3h and 12h s4U-pulse labeling followed by total RNA extraction, alkylation, mRNA 3´ end library preparation (QuantSeq, Lexogen) and high throughput sequencing.

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Neumann T, Herzog VA, Muhar M, von Haeseler A, Zuber J, Ameres SL, Rescheneder P