Project description:RNA homeostasis, a process maintained through a balance between transcription and decay, plays a critical role for most cellular functions. The conserved XRN and DIS3 families are major exoribucleases involved in this RNA turnover. Very little information is currently available about their physiological and physiopathological functions in humans. The aim of this study was to identify the possible advantage and the subsequent modification changes associated with XRN1 invalidation (siXRN1).
Project description:The goal of the project was to study the effects on transcription and mRNA stability of the Xrn1 sudden depletion. We analyzed the effect of Xrn1 depletion caused by protein degradation of an Auxin-degron fusion on the transcription rates, mRNA stabilities and mRNA levels by doing Genomic Run-On (GRO) experiments at 30 min after Auxin addition with a control at 0 min.
Project description:To determine the effects of inactivation of both the nosense-mediated mRNA decay pathway and the general 5' to 3' decay pathway on yeast mRNA decay, we compared the expression profiles of the wild-type, xrn1, xrn1 upf1, xrn1 nmd2, and xrn1 upf3 strains.
Project description:During the last decade several examples of coordination between gene transcription and mRNA degradation have been reported. mRNA imprinting by Rpb4 and 7 subunits of RNA polymerase II (RNAPII) and by the Ccr4-Not complex allows controlling its fate during transcription. Transcription regulation by mRNA degradation factors like Xrn1 constitutes a feedback loop that contributes to mRNA homeostasis. Mechanistic details of these phenomena are unclear. Most studies involve measurement of mRNA decay rates, usually by stressing procedures such as transcriptional shut-off or incorporation of modified nucleotides that can lead to biased results. In this work we have used the easily repressible yeast GAL1 gene to perform a genetic analysis of mRNA synthesis and degradation under physiological conditions. We combined this experimental approach with computational multi-agent modelling, testing different possibilities of Xrn1 and Ccr4-Not action in gene transcription. This double strategy brought us to conclude that Xrn1 regulates RNAPII backtracking in a Ccr4-independent manner. We validated this conclusion measuring TFIIS genome-wide recruitment to elongating RNAPII molecules. We found that xrn1∆ and ccr4∆ exhibited very different patterns of TFIIS/RNPAII which confirmed their differential role in controlling transcription elongation.
Project description:Despite the remarkable achievement of immune checkpoint blockade (ICB) therapy, the response rate is relatively low and only a subset of patients can benefit from the treatment. We hypothesize that targeting RNA decay machinery may lead to accumulation of aberrantRNA, triggering interferon (IFN) signaling and sensitizing tumor cells to immunotherapy. With this in mind, we identified an RNA exoribonuclease, XRN1 as a potential target. Silencing of XRN1 suppressed tumor growth in syngeneic immunocompetent mice and potentiated immunotherapy, while silencing of XRN1 alone did not affect tumor growth in immune deficient mice. Mechanistically, XRN1 depletion activated interferon signaling and viral defense pathway; both pathways play determinant roles in regulating immune evasion. In murine tumors engrafted on immmunocompetent mice, XRN1 depletion significantly enhanced immune cell infiltration in solid tumors especially in combinatory with PD-1 blockade. We identified aberrant-RNA sensing signaling proteins (RIG-I/MAVS and PKR) in mediating the expression of IFN genes, as depletion of each of them blunted the elevation of anti-viral/IFN signaling in Xrn1 silenced cells. Analysis of pan-cancer CRISPR screening data indicated that IFN signaling triggered by Xrn1 silencing is a common phenomenon, suggesting that the effect of Xrn1 silencing may be extend to multiple types of cancers.
Project description:Despite the remarkable achievement of immune checkpoint blockade (ICB) therapy, the response rate is relatively low and only a subset of patients can benefit from the treatment. We hypothesize that targeting RNA decay machinery may lead to accumulation of aberrantRNA, triggering interferon (IFN) signaling and sensitizing tumor cells to immunotherapy. With this in mind, we identified an RNA exoribonuclease, XRN1 as a potential target. Silencing of XRN1 suppressed tumor growth in syngeneic immunocompetent mice and potentiated immunotherapy, while silencing of XRN1 alone did not affect tumor growth in immune deficient mice. Mechanistically, XRN1 depletion activated interferon signaling and viral defense pathway; both pathways play determinant roles in regulating immune evasion. We identified aberrant-RNA sensing signaling proteins (RIG-I/MAVS and PKR) in mediating the expression of IFN genes, as depletion of each of them blunted the elevation of anti-viral/IFN signaling in Xrn1 silenced cells. Analysis of pan-cancer CRISPR screening data indicated that IFN signaling triggered by Xrn1 silencing is a common phenomenon, suggesting that the effect of Xrn1 silencing may be extend to multiple types of cancers.
Project description:To study the role of the exonuclease Xrn1 in translational control, we performed ribosome profiling and RNA-seq in Xrn1-depleted cells. By using an auxin-inducible degron, we were able to study immediate effects of Xrn1 depletion in translational control. Therefore, we could overcome experimental limitations associated to stable deletion mutants.
Project description:Analysis of HeLa cells following depletion of BRCA1 tumor supressor using RNAi against BRCA1. Results provide insight into the molecular mechanisms underlying loss of the BRCA1 function.