塩見研公開ラボセミナー
Noncoding transcription and genotoxic stress
野島 孝之 博士（オックスフォード大学サーウイリアムダン病理研究所）
2019年08月23日(金) 16:30-17:30 理学部3号館 303号室
RNA polymerase II (Pol II) transcription regulates gene expression in eukaryotes. Notably, the C-terminal domain (CTD) of Pol II largest subunit is dynamically phosphorylated during transcription to connect RNA processing and chromatin remodeling (so-called “the CTD code”). However, precise Pol II activity together with the CTD modifications remains largely unknown due to technical limitation. I have recently developed native elongating transcript-sequencing technique for mammalian cells (mNET-seq) that allows to map Pol II active site and co-transcriptional RNA cleavage at a single nucleotide resolution genome-wide1. Importantly, a series of CTD phosphorylation specific Pol II antibodies have been employed to directly profile nascent RNAs and to reveal the Pol II CTD code. Using my own mNET-seq technology, we have determined distinctive patterns of transcription for protein-coding and long noncoding RNA (lncRNA) in terms of Pol II CTD isoforms, RNA stability and RNA processing efficiency2.
I have applied this sequencing strategy to proteomics analysis, named mNET-mass spectrometry (MS) that has revealed co-transcriptional recruitment of catalytic spliceosome in CTD S5P specific manner3. The mNET-MS methodology also has identified an elongation factor, SPT6, as universal Pol II interacting protein. Unexpectedly depletion of SPT6 protein switched transcriptional directionality from mRNA to lncRNA genes with relocation of active transcription histone mark H3K36me3. We then determined that deregulated lncRNA transcription induces Transcription-Replication Conflict (TRC), leading to cell cycle arrest associated with cellular senescence4. This suggests that noncoding transcription should be restricted to prevent genotoxic stress such as TRC in proliferating cells.
References
1. Nojima et al., Cell, 2015
2. Schlakow, Nojima et al., Molecular Cell, 2017
3. Nojima et al., Molecular Cell, 2018a
4. Nojima et al., Molecular Cell, 2018b
