Project description:P53 inactivation occurs in about 50% of human cancers, where p53-driven p21 activity is devoid and p27 becomes essential for the establishment of the G1/S checkpoint upon DNA damage. Here, we show that the E2F1-responsive lncRNA LIMp27 selectively represses p27 expression and contributes to proliferation, tumorigenicity, and treatment resistance in p53-defective colon adenocarcinoma (COAD) cells. LIMp27 competes with p27 mRNA for binding to cytoplasmically localized hnRNA0, which otherwise stabilizes p27 mRNA leading to cell cycle arrest at the G0/G1 phase. In response to DNA damage, LIMp27 is upregulated in both wild-type and p53-mutant COAD cells, whereas cytoplasmic hnRNPA0 is only increased in p53-mutant COAD cells due to translocation from the nucleus. Moreover, high LIMp27 expression is associated with poor survival of p53-mutant but not wild-type p53 COAD patients. These results uncover a lncRNA mechanism that promotes p53-defective cancer pathogenesis and suggest that LIMp27 may constitute a target for the treatment of such cancers.
Project description:The hereditary information encoded in DNA sequence is intrinsically susceptible to alterations, being continually threatened by a variety of genotoxic perturbations. To safeguard the stability of the genome, eukaryotic cells have evolved a set of sophisticated surveillance system that controls several aspects of the cellular response, including the detection of DNA lesions, a temporary cell cycle arrest, regulation of transcription, and the repair of the damaged DNA. However, it is still poorly understood how the DNA damage checkpoints and stalled RNAPII molecules convert a very limited amount of molecular-level information (even a single DNA lesion) in the context of an otherwise genome into regulation that halts and resumes the cell-cycle engine in a coordinated way. In this study, we reveal a map of extensive lncRNA transcription during DDR by using synchronized cells, leading to the unexpected identification of a poorly characterized mammalian lncRNA-ZFAS1. We describe that ZFAS1 functions as a key player of cellular response to DNA damage in both human and rodent cells by fine tuning RNAPII kinetics, suggesting a lncRNA-dependent transcriptional regulatory axis that maintains genomic stability upon DNA damage in mammalian cells.
Project description:Transcriptional profiling of human fibroblast cells after DNA damage with Camptothecin or Etoposide or Neocarzinostatin Upon DNA damage, the DNA damage response (DDR) elicits a complex signaling cascade, which includes the induction of multiple non-coding RNA species. Recently long non-coding RNAs (lncRNAs) have been shown to contribute to DDR by regulating gene expression. However, very little is known about the role that lncRNAs play in regulating DNA Repair. Using a genome-wide microarray screen we identified a novel ubiquitously expressed lncRNA, DDSR1 (DNA damage-sensitive RNA 1), which is induced upon DNA damage by several DNA double-strand break (DSB) agents. Two-condition experiment, Control vs. DNA damage human fibroblast cells. No Replicates, DNA damage was induced with either Camptothecin or Etoposide or Neocarzinostatin, Total RNA or Nuclear RNA was profiled.
Project description:Senescent cells are a major cause of organismal aging and a key target for anti-aging therapies. Persistent DNA damage signaling is a primary driver of the induction and maintenance of cellular senescence. However, many DNA damaging stimuli that induce senescence, such as irradiation or transient exposure to genotoxic drugs, are transient. The mechanisms underlying persistent damage signaling in senescent cells, and why senescent cells fail to repair damaged DNA, remain unknown. Here, we were able to assess the mechanisms underlying persistence of DNA damage and senescence maintenance by designing a precisely controllable senescence system that does not require potent stressors to induce senescence. We demonstrate that sustained mTORC1 signaling in senescent cells causes gradually accumulating DNA damage and an inflammatory response that maintains cell-cycle arrest. Markedly, activation of E2F transcription, which promotes expression of DNA repair proteins, can reverse accumulated DNA damage. Thus, persistent DNA damage signaling arises in senescent cells by uncoupling of mTORC1 and E2F signaling, whereby prolonged mTORC1 activity causes gradually increasing DNA damage that cannot be sufficiently repaired without induction of protective E2F target genes.
Project description:This SuperSeries is composed of the following subset Series: GSE28006: The pioneer factor PBX1 guides a distinct ERa signaling in breast cancer [mRNA profiling] GSE28007: The pioneer factor PBX1 guides a distinct ERa signaling in breast cancer [ChIP-seq] Refer to individual Series
Project description:Long noncoding RNAs (lncRNAs) are prevalent genes with frequently exquisite regulation but mostly unknown functions. Here we demonstrate a role of lncRNAs in guiding signal transduction. DNA damage activates transcription of DINO (Damage Induced NOncoding) via p53. DINO knockdown blocks DNA damage-induced gene expression and cell cycle arrest. Conversely, enforced expression of DINO activates damage signaling without DNA damage. DINO binds p53 and selectively promotes SET7 methylation of p53 at lysine 372 over other substrates, which stabilizes p53 in an auto-amplification loop. Our results suggest that inducible lncRNA can achieve catalysis-like effects to rewire cellular signaling networks. RNA was isolated from human fetal lung fibroblasts, HCT116 p53+/+, or HCT116 p53-/- cells treated with doxorubicin or sham for 26 hours. Human fetal lung fibroblasts were transfected with siRNAs targeting DINO or non-targeting control and subsequently treated with doxorubicin for 26 hours.