Project description:Adult hematopoietic stem cells (HSCs) are predominantly quiescent and can be activated in response to acute stress such as infection or cytotoxic insults. STAT1 is a pivotal mediator of interferon (IFN) signaling and is required for IFN-induced HSC proliferation, but the downstream mechanisms remain unclear and in particular little is known about the role of STAT1 in regulating hematopoietic stem/progenitor cells during homeostasis. Here we show that loss of STAT1 alters the steady state hematopoietic stem and progenitor (HSPC) landscape, impairs HSC function in transplantation assays and delays blood cell regeneration following myeloablation. Under steady state conditions STAT1 was essential for several HSC transcriptional programs including expression of genes involved in virus life cycle, a subset of interferon-stimulated genes, MHC class I genes and genes involved in cell cycle arrest. In addition Stat-1 deficient mice lacked a previously unrecognized quiescent subset of homeostatic HSCs with high levels of MHC II expression (MHC IIhi HSCs). This subset was refractory to 5’-FU induced myeloablation and displayed reduced megakaryocytic potential. Mutant calreticulin, which causes increased megakaryopoiesis in human myeloproliferative neoplasms, gave rise to preferential expansion of MHC IIlo HSCs. These data reveal a STAT1 dependent MHC IIhi quiescent HSC subset and show that STAT1 protects HSCs from proliferative exhaustion.
Project description:Adult hematopoietic stem cells (HSCs) are predominantly quiescent and can be activated in response to acute stress such as infection or cytotoxic insults. STAT1 is a pivotal mediator of interferon (IFN) signaling and is required for IFN-induced HSC proliferation, but the downstream mechanisms remain unclear and in particular little is known about the role of STAT1 in regulating hematopoietic stem/progenitor cells during homeostasis. Here we show that loss of STAT1 alters the steady state hematopoietic stem and progenitor (HSPC) landscape, impairs HSC function in transplantation assays and delays blood cell regeneration following myeloablation. Under steady state conditions STAT1 was essential for several HSC transcriptional programs including expression of genes involved in virus life cycle, a subset of interferon-stimulated genes, MHC class I genes and genes involved in cell cycle arrest. In addition Stat-1 deficient mice lacked a previously unrecognized quiescent subset of homeostatic HSCs with high levels of MHC II expression (MHC IIhi HSCs). This subset was refractory to 5’-FU induced myeloablation and displayed reduced megakaryocytic potential. Mutant calreticulin, which causes increased megakaryopoiesis in human myeloproliferative neoplasms, gave rise to preferential expansion of MHC IIlo HSCs. These data reveal a STAT1 dependent MHC IIhi quiescent HSC subset and show that STAT1 protects HSCs from proliferative exhaustion.
Project description:Begitt2014 - STAT1 cooperative DNA binding - double GAS polymer model
The importance of STAT1-cooperative DNA binding in type 1 and type 2 interferon signalling has been studies using experimental and modelling approaches. The authors have developed two ODE models to describe STAT1 binding to short promoter regions of DNA, namely "single GAS polymer model" and "double GAS polymer model" considering binding to single or double GAS sites, respectively. The length of DNA in the single GAS model was three sites and four sites in double GAS model. This model correspond to the "double GAS polymer model".
This model is described in the article:
STAT1-cooperative DNA binding distinguishes type 1 from type 2 interferon signaling.
Begitt A, Droescher M, Meyer T, Schmid CD, Baker M, Antunes F, Owen MR, Naumann R, Decker T, Vinkemeier U
Nat Immunol. 2014 Feb;15(2):168-76.
Abstract:
STAT1 is an indispensable component of a heterotrimer (ISGF3) and a STAT1 homodimer (GAF) that function as transcription regulators in type 1 and type 2 interferon signaling, respectively. To investigate the importance of STAT1-cooperative DNA binding, we generated gene-targeted mice expressing cooperativity-deficient STAT1 with alanine substituted for Phe77. Neither ISGF3 nor GAF bound DNA cooperatively in the STAT1F77A mouse strain, but type 1 and type 2 interferon responses were affected differently. Type 2 interferon-mediated transcription and antibacterial immunity essentially disappeared owing to defective promoter recruitment of GAF. In contrast, STAT1 recruitment to ISGF3 binding sites and type 1 interferon-dependent responses, including antiviral protection, remained intact. We conclude that STAT1 cooperativity is essential for its biological activity and underlies the cellular responses to type 2, but not type 1 interferon.
This model is hosted on BioModels Database
and identified
by: BIOMD0000000501
.
To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource
for published quantitative kinetic models
.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to the public
domain worldwide. Please refer to CC0 Public Domain
Dedication
for more information.
Project description:Begitt2014 - STAT1 cooperative DNA binding - single GAS polymer model
The importance of STAT1-cooperative DNA binding in type 1 and type 2 interferon signalling has been studies using experimental and modelling approaches. The authors have developed two ODE models to describe STAT1 binding to short promoter regions of DNA, namely "single GAS polymer model" and "double GAS polymer model" considering binding to single or double GAS sites, respectively. The length of DNA in the single GAS model was three sites and four sites in double GAS model. This model correspond to the "single GAS polymer model".
This model is described in the article:
STAT1-cooperative DNA binding distinguishes type 1 from type 2 interferon signaling.
Begitt A, Droescher M, Meyer T, Schmid CD, Baker M, Antunes F, Owen MR, Naumann R, Decker T, Vinkemeier U
Nat Immunol. 2014 Feb;15(2):168-76.
Abstract:
STAT1 is an indispensable component of a heterotrimer (ISGF3) and a STAT1 homodimer (GAF) that function as transcription regulators in type 1 and type 2 interferon signaling, respectively. To investigate the importance of STAT1-cooperative DNA binding, we generated gene-targeted mice expressing cooperativity-deficient STAT1 with alanine substituted for Phe77. Neither ISGF3 nor GAF bound DNA cooperatively in the STAT1F77A mouse strain, but type 1 and type 2 interferon responses were affected differently. Type 2 interferon-mediated transcription and antibacterial immunity essentially disappeared owing to defective promoter recruitment of GAF. In contrast, STAT1 recruitment to ISGF3 binding sites and type 1 interferon-dependent responses, including antiviral protection, remained intact. We conclude that STAT1 cooperativity is essential for its biological activity and underlies the cellular responses to type 2, but not type 1 interferon.
This model is hosted on BioModels Database
and identified
by: BIOMD0000000500
.
To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource
for published quantitative kinetic models
.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to the public
domain worldwide. Please refer to CC0 Public Domain
Dedication
for more information.
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:The objective of this study was to compare the ability of mice that lack STAT1 to resolve a neurotropic viral challenge, and to assess the ability of neurons obtained from these mice to be effectively cleared of virus by interferon gamma For the array, primary neurons were isolated from embryonic mice, grown as pure cultures, exposed to recombinant interferon gamma for 3, 6 or 24 hours and harvested for microarray analysis to identify and compare the gene profiles between wild type and STAT1 knockout neurons.
Project description:The role of the human type I interferon (IFN-I) system in restricting Zika virus (ZIKV) is uncertain. Here, genetic and pharmacological ablation of IFN-I signalling enhanced ZIKV replication and cytopathicity in macrophages and microglia, key cells in ZIKV transmission and pathogenesis. Thus, despite the extensive IFN-I countermeasures employed by ZIKV, IFN-I dictates the outcome of infection in macrophages. Therapeutic manipulation of the IFN-I system may bring clinical benefit in ZIKV.
Project description:The overall goal of the study was to use in vivo data combined with functional genomics to define gene expression signatures representative of a spectrum of HSV CNS infections. Innate immune deficiencies result in a spectrum of severe clinical outcomes following infection. In particular, there is a strong association between loss of the signal transducer and activator of transcription (Stat) pathway, breach of the blood-brain barrier (BBB), and virus-induced neuropathology. The gene signatures that characterize resistance, disease, and mortality in the virus-infected nervous system have not been defined. Herpes simplex virus type 1 (HSV-1) is commonly associated with encephalitis in humans, and humans and mice lacking Stat1 display increased susceptibility to HSV central nervous system (CNS) infections. In this study, two HSV-1 strains were used, KOS (wild type [WT]), and Δvhs, an avirulent recombinant lacking the virion host shutoff (vhs) function. In addition, two mouse strains were used: strain 129 (control) and a Stat1-deficient (Stat1(-/-)) strain. Using combinations of these virus and mouse strains, we established a model of infection resulting in three different outcomes: viral clearance without neurological disease (Δvhs infection of control mice), neurological disease followed by viral clearance (Δvhs infection of Stat1(-/-) mice and WT infection of control mice), or neurological disease followed by death (WT infection of Stat1(-/-) mice). Through the use of functional genomics on the infected brain stem and liver, we determined gene signatures that were representative of the three infection outcomes. Gender matched, 6- to 8- week old immunocompetent, control 129S6 and 129S6 Stat1 knockout mice were infected corneally with 2x10^6 PFU of either wild type HSV-1, a vhs-null HSV virus, or mock-infected. Brain stems and liver of individual mice were isolated at days 1, 3, 5 and 7 post-inoculation for microarray analysis. For microarray analysis, samples were collected from n=2 animals (1 male, 1 female) per mouse strain and virus strain for each time point. Equal masses of tissue were pooled from two mock-infected mice per time point and run on microarray.
Project description:U3A cells stably expressing wild-type STAT1 or STAT1-CC were treated with interferon beta (10U/ml) or control for 24 hours to assess effects of stat1 modifications, interferon, and the interaction on gene expression. Keywords: interferon, STAT1, STAT1-CC, STAT1CC, STAT-1C, antiviral RNA was isolated from stable U3A-STAT1 lines stably expressing wild-type STAT1 or STAT1CC, after 24 hour treatment with interferon beta (10U/ml) or control.