Project description:Characterized by lethal iron accumulation and lipid peroxidation, ferroptosis plays critical roles in liver injury, especially caused by ischemia/reperfusion (I/R) of hepatic inflow occlusion during liver operation. However, the lack of effective and safe clinical precautionary measure is still the main problem in preventing hepatic ferroptosis. Here, we found that the excessive production of reactive oxygen species could decrease the expression of Interferon (IFN)-stimulated gene DExH-box helicase 58 (DHX58) in hepatocytes, and then promote hepatic ferroptosis, while pre-treatment using IFN-α increased DHX58 expression and prevented ferroptosis during I/R injury. Mechanistically, DHX58 with RNA-binding activity could constitutively associate the mRNA of glutathione peroxidase 4 (GPX4), a crucial ferroptosis suppressor, and then recruit the m6A reader YT521-B homology domain containing 2 (YTHDC2) to promote the translation of Gpx4 mRNA in m6A-dependent manner, thus enhancing GPX4 protein level and preventing hepatic ferroptosis. Therefore, we provide mechanistic evidence for the IFN-stimulated DHX58 in promoting the translation of m6A-modified Gpx4 mRNA, and suggest the promising clinical potential of IFN-α pre-treatment in the prevention of hepatic ferroptosis.
Project description:DHX9 is a DExH-box RNA helicase with versatile functions in transcription, translation, RNA processing and regulation of DNA replication. DHX9 has recently emerged as a promising target for oncology, but to date no mammalian structures have been published. Here, crystal structures of human, dog and cat DHX9 bound to ADP are reported. The three mammalian DHX9 structures share identical structural folds. Additionally, the overall architecture and the individual domain structures of DHX9 are highly conserved with those of MLE, the Drosophila orthologue of DHX9 previously solved in complex with RNA and a transition-state analogue of ATP. Due to differences in the bound substrates and global domain orientations, the localized loop conformations and occupancy of dsRNA-binding domain 2 (dsRBD2) differ between the mammalian DHX9 and MLE structures. The combined effects of the structural changes considerably alter the RNA-binding channel, providing an opportunity to compare active and inactive states of the helicase. Finally, the mammalian DHX9 structures provide a potential tool for structure-based drug-design efforts.
Project description:Characterized by lethal iron accumulation and lipid peroxidation, ferroptosis plays critical roles in liver injury, especially caused by ischemia/reperfusion (I/R) of hepatic inflow occlusion during liver operation. Here, we found that the excessive production of reactive oxygen species could decrease the expression of Interferon (IFN)-stimulated gene DExH-box helicase 58 (DHX58) in hepatocytes, and then promote hepatic ferroptosis, while pre-treatment using IFN-α increased DHX58 expression and prevented ferroptosis during I/R injury. Mechanistically, DHX58 with RNA-binding activity could constitutively associate the mRNA of glutathione peroxidase 4 (GPX4), a crucial ferroptosis suppressor, and then recruit the m6A reader YT521-B homology domain containing 2 (YTHDC2) to promote the translation of Gpx4 mRNA in m6A-dependent manner, thus enhancing GPX4 protein level and preventing hepatic ferroptosis.
Project description:Characterized by lethal iron accumulation and lipid peroxidation, ferroptosis plays critical roles in liver injury, especially caused by ischemia/reperfusion (I/R) of hepatic inflow occlusion during liver operation. Here, we found that the excessive production of reactive oxygen species could decrease the expression of Interferon (IFN)-stimulated gene DExH-box helicase 58 (DHX58) in hepatocytes, and then promote hepatic ferroptosis, while pre-treatment using IFN-α increased DHX58 expression and prevented ferroptosis during I/R injury. Mechanistically, DHX58 with RNA-binding activity could constitutively associate the mRNA of glutathione peroxidase 4 (GPX4), a crucial ferroptosis suppressor, and then recruit the m6A reader YT521-B homology domain containing 2 (YTHDC2) to promote the translation of Gpx4 mRNA in m6A-dependent manner, thus enhancing GPX4 protein level and preventing hepatic ferroptosis.
Project description:The NTP-dependent DExH/D-box helicase DHX9 is a key participant in a number of gene regulatory steps, including transcriptional, translational, and microRNA-mediated control, DNA replication and maintenance of genomic stability. DHX9 has also been implicated in tumor cell maintenance and drug response. Here we report that inhibition of DHX9 expression is lethal to human cancer cell lines and murine Eμ-Myc lymphomas. Using a novel conditional shDHX9 mouse model, we demonstrate that sustained and prolonged (6 months) suppression of DHX9 does not result in any deleterious effects at the organismal level. Body weight, blood biochemistry and histology of various tissues were comparable to control mice. Global gene expression profiling revealed that, although reduction of DHX9 expression resulted in multiple transcriptome changes, these were relatively benign and did not lead to any discernible phenotype. Our results demonstrate a robust tolerance for systemic DHX9 suppression in vivo and support the targeting of DHX9 as an effective and specific chemotherapeutic approach.
Project description:Characterized by lethal iron accumulation and lipid peroxidation, ferroptosis plays critical roles in liver injury, especially caused by ischemia/reperfusion (I/R) of hepatic inflow occlusion during liver operation. Here, we found that the excessive production of reactive oxygen species could decrease the expression of Interferon (IFN)-stimulated gene DExH-box helicase 58 (DHX58) in hepatocytes, and then promote hepatic ferroptosis, while pre-treatment using IFN-α increased DHX58 expression and prevented ferroptosis during I/R injury. Mechanistically, DHX58 with RNA-binding activity could constitutively associate the mRNA of glutathione peroxidase 4 (GPX4), a crucial ferroptosis suppressor, and then recruit the m6A reader YT521-B homology domain containing 2 (YTHDC2) to promote the translation of Gpx4 mRNA in m6A-dependent manner, thus enhancing GPX4 protein level and preventing hepatic ferroptosis.
Project description:DHX9 is a DExH-box helicase family member with key regulatory roles in a broad range of cellular processes. It participates at multiple levels of gene regulation, including DNA replication, transcription, translation, RNA transport, and microRNA processing. It has been implicated in tumorigenesis and recent evidence suggests that it may be a promising chemotherapeutic target. Previous studies have determined that DHX9 suppression elicits an apoptotic or senescence response by activating p53 signaling. Here, we show that DHX9 inhibition can also have deleterious effects in cells lacking functional p53. Loss of DHX9 led to increased cell death in p53-deficient mouse lymphomas and HCT116 human colon cancer cells, and G0/G1 cell cycle arrest in p53-deficient mouse embryonic fibroblasts. Analysis of mRNA levels for p53 transcriptional targets showed that a subset of p53 targets in the p53-null lymphomas and HCT116 cells were activated despite the absence of functional p53. This implies an alternative pathway of DHX9-mediated activation of cell death and cell cycle arrest in p53-deficient cells and supports the feasibility of targeting DHX9 in p53-deficient tumors.
Project description:The ATP-dependent DExH/D-box helicase DHX9 is a key participant in a number of gene regulatory steps, including transcriptional, translational, microRNA-mediated control, DNA replication, and maintenance of genomic stability. DHX9 has also been implicated in maintenance of the tumorigenic process and in drug response. Here, we report that inhibition of DHX9 expression is lethal to multiple human and mouse cancer cell lines. In contrast, using a novel conditional shDHX9 mouse model, we demonstrate that sustained and prolonged suppression of DHX9 is well tolerated at the organismal level. Our results demonstrate a robust tolerance for DHX9 knockdown in non-transformed cells and supports the targeting of DHX9 as an effective and specific chemotherapeutic approach.
Project description:The ATP-dependent DExH/D-box helicase DHX9 is a key participant in a number of gene regulatory steps, including transcriptional, translational, microRNA-mediated control, DNA replication, and maintenance of genomic stability. DHX9 has also been implicated in maintenance of the tumorigenic process and in drug response. Here, we report that inhibition of DHX9 expression is lethal to multiple human and mouse cancer cell lines. In contrast, using a novel conditional shDHX9 mouse model, we demonstrate that sustained and prolonged suppression of DHX9 is well tolerated at the organismal level. Our results demonstrate a robust tolerance for DHX9 knockdown in non-transformed cells and supports the targeting of DHX9 as an effective and specific chemotherapeutic approach. Comparison of gene expression in large intestine of mice with or without reduced expression of DHX9.