Project description:To examine effects of COPI depletion on senescence transcriptional signatures we generated cell lines (IMR90 or IMR90 ER:RAS cells) with inducible 2 COPI shRNAs or control shRNAs and induced to senesce with either treatment with Bleomycin or 4OHT treatment. Transcriptional analysis was performed 3 days after induction of doxycycline inducible harpins and 10 days after senescence induction.
Project description:We utilised our in vitro model of cervical neoplastic progression, W12, to investigate the effect of HPV16 viral oncogene depletion on well-defined integrant- and episome- associated series. To target HPV16 viral oncogenes we used our previously published E7-targeting siRNA sequence that caused substantial depletion of both E7 and E6 in CaSki cells. We found all E7-siRNA treated W12 series underwent widespread autophagy and senescence, with up-regulation of an innate immune response.
Project description:To examine effects of NMT inhibition on senescence transcriptional signatures we treated IMR90 ER:RAS cells with either IMP1088 (300nM) or DDD86481 (1.5uM) for 72h 7 days after induction with 4-OHT treatment. Transcriptional analysis was performed 3 days after drug treatment and 10 days after senescence induction.
Project description:XAB2 is a multi-functional protein participating processes including transcription, splicing, DNA repair and mRNA export. Here we report POLR2A as a major target gene down-regulated after XAB2 depletion. XAB2 depletion led to severe splicing defects of POLR2A with significant intron retention. Such defects resulted in substantial loss of POLR2A at RNA and protein levels, which further impaired global transcription. Treatment of splicing inhibitor madrasin induced similar reduction of POLR2A. Screen using TMT identified several proteins involved in mRNA surveillance including Dom34 with elevated expression. Inhibition of translation or depletion of Dom34 rescued the expression of POLR2A by stabilizing its mRNA. Immuno-precipitation further confirmed that XAB2 associated with spliceosome components important to POLR2A expression. Domain mapping revealed that TPR motifs 2-4 and 11-12 of XAB2 were critical for POLR2A expression. Finally we showed POLR2A mediated cell senescence caused by XAB2 deficiency. Depletion of XAB2 or POLR2A induced cell senescence by up-regulation of p53 and p21, re-expression of POLR2A after XAB2 depletion alleviated cellular senescence. These data together support that XAB2 serves as a guardian of POLR2A expression to ensure global gene expression and antagonize cell senescence.
Project description:Understanding cellular coordination remains a challenge despite knowledge of individual pathways. The RNA exosome, targeting a wide range of RNA substrates, is often downregulated in cellular senescence. Utilizing an auxin-inducible system, we observed that RNA exosome depletion in embryonic stem cells significantly affects the transcriptome and proteome, causing pluripotency loss and pre-senescence onset. Mechanistically, exosome depletion triggers acute nuclear RNA aggregation, disrupting nuclear RNA-protein equilibrium. This disturbance limits nuclear protein availability and hinders polymerase initiation and engagement, reducing gene transcription. Concurrently, it promptly disrupts nucleolar transcription, ribosomal processes, and nuclear exporting, resulting in translational shutdown. Prolonged exosome depletion induces nuclear structural changes resembling senescent cells, including aberrant chromatin compaction, chromocenter disassembly, and intensified heterochromatic foci. These effects suggest that dynamic turnover of nuclear RNA orchestrates crosstalk between essential processes to optimize cellular function. Disruptions in nuclear RNA homeostasis result in systemic functional decline, altering the cell state and promoting senescence.