Project description:Life-threatening pulmonary influenza can be caused by inborn errors of type I and III IFN immunity. We report a 5 year-old child with severe pulmonary influenza at 2 years. She is homozygous for a loss-of-function IRF9 allele. Her cells activate gamma-activated factor (GAF) STAT1 homodimers but not interferon-stimulated gene factor 3 (ISGF3) trimers (STAT1/STAT2/IRF9) in response to IFN-α2b. The transcriptome induced by IFN-α2b in the patient’s cells is much narrower than that of control cells; however, induction of a subset of interferon-stimulated gene transcripts remains detectable. In vitro, the patient’s cells do not control three respiratory viruses, influenza A virus (IAV), parainfluenza virus, and respiratory syncytial virus. These phenotypes are rescued by wild-type IRF9, whereas silencing IRF9 expression in control cells increases viral replication. However, the child has controlled various common viruses in vivo, including respiratory viruses other than IAV. Our findings show that human IRF9- and ISGF3-dependent type I and III IFN responsive pathways are essential for controlling IAV.
Project description:Host defense by the innate immune system requires the establishment of antimicrobial states allowing cells to cope with microorganisms before the onset of the adaptive immune response. Interferons (IFN) are of vital importance in the establishment of cell-autonomous antimicrobial immunity. Speed is therefore an important attribute of the cellular response to IFN. With much of the antimicrobial response being installed de novo, this pertains foremost to gene expression, the rapid switch between resting-state and active-state transcription of host defense genes. Mechanisms to meet this demand on the relevant molecular machinery include remodeling of chromatin but also changes in transcription factor interaction prior and during the IFN response. Our results show how transcription factors STAT1, STAT2 and IRF9 change binding patterns upon IFNb or IFNg treatment in wild type and Irf9-/- bone marrow derived macrophages.
Project description:Host defense by the innate immune system requires the establishment of antimicrobial states allowing cells to cope with microorganisms before the onset of the adaptive immune response. Interferons (IFN) are of vital importance in the establishment of cell-autonomous antimicrobial immunity. Speed is therefore an important attribute of the cellular response to IFN. With much of the antimicrobial response being installed de novo, this pertains foremost to gene expression, the rapid switch between resting-state and active-state transcription of host defense genes. Our results show how mRNA expression changes upon IFNb treatment in wild type and Irf9-/- mouse embryonic fibroblasts.
Project description:IRF9 is ubiquitously expressed and mediates the effects of IFNs, previous study showed that IRF9 played an important role in immunity and cell fate decision. Our recent study revealed that IRF9 involved in cardiac hypertrophy, hepatic steatosis and insulin resistance. However, the function of IRF9 in VSMC and neointima formation was largely unknown. We found that IRF9 expression was significantly increased in the VSMCs of mouse carotid artery. More importantly, we generated SMC-specific IRF9 overexpression transgenic mice (IRF9 TG) and found that IRF9 TG significantly increased VSMC proliferation, migration and neointima formation compared with NTG mice in response to injury. To evaluate the underlying mechanism by which IRF9 promotes VSMC proliferation and migration after vascular injury, IRF9 TG and NTG mice were subjected to wire-injury and the carotid arteries were collected at 14 days post-injury. We combined 3-5 vessels for one sample, and 3 samples for each phenotype. Subsequently, a total of 400ng RNA was used following Affymetrix instruction and 10 ug of cRNA were hybridized for 16 hr at 45°. GeneChips were scanned using the Scanner 7G and the data was analyzed with Expression Console using Affymetrix default analysis settings and global scaling as normalization method. RMA analysis was employed to evaluate the gene expression. We used microarrays to detect the global gene expression in the carotid arteries of smooth muscle cell specific IRF9 transgenic mice(IRF9 TG) compared with non transgenic control mice (NTG) at 14 days post-injury and identified distinct classes of altered genes. non-transgenic controls mice (NTG) and smooth muscle specific IRF9 transgenic mice (IRF9 TG) were subjected to wire-injury and the carotid ateries were collected at 14 days post-injury. We combine 3-5 vessels in one tube and for a single Affymetrix microarray. Total RNA was extracted and a total of 400ng RNA was used following Affymetrix instruction. 3 biological samples for each genotype.
Project description:Host defense by the innate immune system requires the establishment of antimicrobial states allowing cells to cope with microorganisms before the onset of the adaptive immune response. Interferons (IFN) are of vital importance in the establishment of cell-autonomous antimicrobial immunity. Speed is therefore an important attribute of the cellular response to IFN. With much of the antimicrobial response being installed de novo, this pertains foremost to gene expression, the rapid switch between resting-state and active-state transcription of host defense genes. Mechanisms to meet this demand on the relevant molecular machinery include remodeling of chromatin but also changes in transcription factor interaction prior and during the IFN response. Our results show how transcription factors STAT1, STAT2 and IRF9 change binding patterns upon IFNb treatment in wild type mouse embryonic fibroblasts.
Project description:To investigate the role of IRF9 in the transcriptional regulation of interferon stimulated genes in sgScd2 Th1 cells, we assessed the genome-wide binding pattern of IRF9 by chromatin immunoprecipitation DNA-sequencing (ChIP-seq).
Project description:IRF9 is ubiquitously expressed and mediates the effects of IFNs, previous study showed that IRF9 played an important role in immunity and cell fate decision. Our recent study revealed that IRF9 involved in cardiac hypertrophy, hepatic steatosis and insulin resistance. However, the function of IRF9 in VSMC and neointima formation was largely unknown. We found that IRF9 expression was significantly increased in the VSMCs of mouse carotid artery. More importantly, we generated SMC-specific IRF9 overexpression transgenic mice (IRF9 TG) and found that IRF9 TG significantly increased VSMC proliferation, migration and neointima formation compared with NTG mice in response to injury. To evaluate the underlying mechanism by which IRF9 promotes VSMC proliferation and migration after vascular injury, IRF9 TG and NTG mice were subjected to wire-injury and the carotid arteries were collected at 14 days post-injury. We combined 3-5 vessels for one sample, and 3 samples for each phenotype. Subsequently, a total of 400ng RNA was used following Affymetrix instruction and 10 ug of cRNA were hybridized for 16 hr at 45°. GeneChips were scanned using the Scanner 7G and the data was analyzed with Expression Console using Affymetrix default analysis settings and global scaling as normalization method. RMA analysis was employed to evaluate the gene expression. We used microarrays to detect the global gene expression in the carotid arteries of smooth muscle cell specific IRF9 transgenic mice(IRF9 TG) compared with non transgenic control mice (NTG) at 14 days post-injury and identified distinct classes of altered genes.
Project description:Type I Interferons (IFN-I) mediate cellular responses to virus infection. IFN-I induces IFN-stimulated gene (ISG) expression by phosphorylating STAT1 and STAT2, and together with interferon regulatory factor (IRF9), form the transcription complex ISGF3 that binds to the interferon-stimulated response element (ISRE) in ISG promoters. As a component of ISGF3, it is clear that STAT2 plays an essential role in the transcriptional responses to IFN-I with a strong dependence on STAT1. Previously, we showed that STAT2 also forms homodimers that interact with IRF9 (STAT2-IRF9) to activate transcription of ISRE-containing ISGs in response to IFN-I. Indeed, evidence is accumulating for the existence of a STAT1-independent IFN-I signaling pathway, where STAT2-IRF9 can substitute the role of ISGF3. Here, we provide further insight in the transcriptional regulation and the biological implications of STAT2-IRF9 dependent IFN-I signaling. In human STAT1 KO cells overexpressing human STAT2 (U3C-STAT2), we observed that in response to IFN-I, STAT2 homodimers interact with IRF9 to regulate ISG transcription. The IFN-I-induced phosphorylation profile of STAT2 in U3C-STAT2 was prolonged as compared to WT cells (2fTGH), which corresponded with the expression pattern of OAS2 that also depended on IRF9. Subsequent microarray analysis of IFN-I treated 2fTGH and U3C-STAT2 extended our initial observations and identified more than 60 known antiviral ISGs commonly up-regulated in both cell types. The expression profile of these ISGs was delayed and prolonged in U3C-STAT2 as opposed to the early and transient response in 2fTGH. Moreover, U3C-STAT2 were able to restore an antiviral response upon EMCV and VSV infection that was comparable to the response in 2fTGH. Together, our results strongly suggest that an alternative IFN-I-mediated, STAT2-IRF9 dependent signaling pathway exists that can generate an antiviral response without STAT1 and could be beneficial for example against viruses that directly block STAT1 and impair the formation of ISGF3.