A01: Transcript quality effects of RNAPII speed variation

The fidelity of RNA polymerase II (RNAPII) transcription declines with age, leading to noisier transcript levels and to the expression of aberrant splice isoforms. Recently, we have shown that an age-associated increase in average RNAPII elongation speed at least partially contributes to these phenomena (Debès…Müller…Papantonis, Beyer, 2023). However, we lack understanding about the molecular factors contributing to specific splicing changes and other mRNA sequence errors. Why are some transcripts strongly affected by RNAPII speed changes, while others seem to be robust against them? How can cells cope with the formation of erroneous transcripts? Do complex Project tissues show cell-type specific alterations of splicing fidelity? We will address these questions through the analysis of genetic models of increasing and decreasing RNAPII elongation speed in mammalian cell culture. Comparing nuclear and cytoplasmic mRNA fractions will inform us on the effect of post-transcriptional processes such as mRNA nuclear export, nonsense mediated RNA decay (NMD) (Huth…Beyer, Leeb, 2022) and ribosome-associated quality control (RQC) on the quality of the mature transcriptome. This approach will be accompanied by analyses in a complex tissue (kidney) to address cell-type specificity using both murine and human samples. Taken together, the overarching goal of this project will be to better resolve physiological consequences of RNAPII speed changes and to gain a first insight regarding their relevance in human health.