Biology subjects

Stetson, D. B.

Publications and source records attributed to Stetson, D. B..

7 recordsLinked to original sources

bioRxiv2026

MDA5 and the integrated stress response control sex-specific type 1 diabetes onset in NOD mice

Type I diabetes (T1D) is an autoimmune disorder in which the insulin producing cells of the pancreas are attacked and destroyed by autoreactive T cells. The innate immune mechanisms that contribute to T1D remain incompletely defined. Genome-wide association studies in humans have identified alleles of the IFIH1 gene, which encodes the intracellular RNA sensor MDA5, that are strongly associated with development of T1D. We previously found that MDA5 signaling drives disease and mortality in a mouse model of Aicardi-Goutieres Syndrome (AGS) caused by mutations in the ADAR1 RNA editing enzyme. Genetic dissection of disease in this ADAR1 mutant mouse model revealed that the double stranded RNA-activated kinase PKR and the RNA sensor ZBP1 are also essential for disease. To test the role of intracellular RNA detection in T1D in the nonobese diabetic (NOD) mouse model, we used CRISPR targeting to generate NOD mice targeted for Ifih1, Eif2ak2 (PKR) and Zbp1. We found that haploinsufficiency for Ifih1 resulted in modest but significant protection from T1D only in male NOD mice, but neither PKR nor ZBP1 contributed to T1D onset or incidence. Moreover, treatment of NOD mice with a pharmacological inhibitor of the integrated stress response (ISR) had no effect on T1D incidence in female NOD mice, but accelerated and exacerbated disease in male NOD mice. Together, our findings demonstrate that MDA5 and the ISR contribute to sex-specific disease incidence in NOD mice.

immunology↗

bioRxiv2022

Cellular sources and targets of type I interferons that drive susceptibility to tuberculosis

Mycobacterium tuberculosis (Mtb) causes 1.6 million deaths annually. Active tuberculosis correlates with a neutrophil-driven type I interferon (IFN) signature, but the cellular mechanisms underlying tuberculosis pathogenesis remain poorly understood. We found interstitial macrophages (IMs) and plasmacytoid dendritic cells (pDCs) are dominant producers of type I IFN during Mtb infection in mice and non-human primates, and pDCs localize near human Mtb granulomas. Depletion of pDCs reduces Mtb burdens, implicating pDCs in tuberculosis pathogenesis. During IFN-driven disease, we observe abundant DNA-containing neutrophil extracellular traps (NETs) known to activate pDCs. Cell type-specific disruption of the type I IFN receptor suggests IFNs act on IMs to inhibit Mtb control. Single cell RNA-seq indicates type I IFN-responsive cells are defective in their response to IFN{gamma}, a cytokine critical for Mtb control. We propose pDC-derived type I IFNs act on IMs to drive bacterial replication, further neutrophil recruitment, and active tuberculosis disease.

immunology↗

bioRxiv2021

ABCC1/MRP1 exports cGAMP and modulates cGAS-dependent immunity

The DNA sensor cyclic GMP-AMP synthase (cGAS) is important for antiviral and anti-tumor immunity. cGAS generates cyclic GMP-AMP (cGAMP), a diffusible cyclic dinucleotide that activates the antiviral response through the adapter protein Stimulator of Interferon Genes (STING). cGAMP is negatively charged and cannot passively cross cell membranes, but recent advances have established a role for extracellular cGAMP as an "immunotransmitter" that can be imported into cells. However, the mechanism by which cGAMP exits cells remains unknown. Here, we identify ABCC1/MRP1 as an ATP-dependent cGAMP exporter that influences STING signaling and type I interferon production. We demonstrate that ABCC1 deficiency exacerbates cGAS-dependent autoimmunity in the Trex1-/- mouse model of Aicardi-Goutieres syndrome. These studies identify ABCC1-mediated cGAMP export as a key regulatory mechanism of the cGAS-STING pathway.

immunology↗

bioRxiv2021

Endomembrane targeting of human OAS1 p46 augments antiviral activity

Many host RNA sensors are positioned in the cytosol to detect viral RNA during infection. However, most positive-strand RNA viruses replicate within a modified organelle co-opted from intracellular membranes of the endomembrane system, which shields viral products from host cell innate immune sensors. Targeting innate RNA sensors to the endomembrane system may enhance their ability to sense viral RNA generated by viruses that use these compartments for replication. Here, we reveal that an isoform of oligoadenylate synthetase 1, OAS1 p46, is prenylated and targeted to the endomembrane system. Membrane localization of OAS1 p46 confers enhanced access to viral replication sites and results in increased antiviral activity against a subset of RNA viruses including flavivirus, picornavirus, and SARS-CoV-2. Finally, our human genetic analysis shows that the OAS1 splice-site SNP responsible for production of the OAS1 p46 isoform strongly associates with COVID-19 severity. This study highlights the importance of endomembrane targeting for the antiviral specificity of OAS1 and suggests early control of SARS-CoV-2 replication through OAS1-p46 is an important determinant of COVID-19 severity.

immunology↗

bioRxiv2020

PKR and the Integrated Stress Response drive immunopathology caused by ADAR1 mutation

Mutations in ADAR, the gene that encodes the ADAR1 RNA deaminase, cause numerous human diseases, including Aicardi-Goutieres Syndrome (AGS). ADAR1 is an essential negative regulator of the RNA sensor MDA5, and loss of ADAR1 function triggers inappropriate activation of MDA5 by self-RNAs. However, the mechanisms of MDA5-dependent disease pathogenesis in vivo remain unknown. Here, we introduce a knockin mouse that models the most common ADAR AGS mutation in humans. These Adar-mutant mice develop lethal disease that requires MDA5, the RIG-I-like receptor LGP2, type I interferons, and the eIF2 kinase PKR. We show that a small molecule inhibitor of the integrated stress response (ISR) that acts downstream of eIF2 phosphorylation prevents immunopathology and rescues the mice from mortality. These findings place PKR and the ISR as central components of immunopathology in vivo and identify new therapeutic targets for treatment of human diseases associated with the ADAR1-MDA5 axis.

immunology↗

bioRxiv2019

Human DNA-PK activates a STING-independent DNA sensing pathway

Detection of intracellular DNA by the cGAS-STING pathway activates a type I interferon-mediated innate immune response that protects from virus infection and can be harnessed to promote anti-tumor immunity. Whether there are additional DNA sensing pathways, and how such pathways might function, remains controversial. We show here that humans - but not mice - have a second, potent, STING-independent DNA sensing pathway that is blocked by the E1A viral oncogene of human adenovirus 5. We identify human DNA-PK as the sensor of this pathway and demonstrate that DNA-PK kinase activity drives a robust and broad antiviral response. We discover that the heat shock protein HSPA8/HSC70 is a unique target of DNA-PK. Finally, we demonstrate that detection of foreign DNA and DNA damage trigger distinct modalities of DNA-PK activity. These findings reveal the existence, sensor, unique target, and viral antagonists of a STING-independent DNA sensing pathway (SIDSP) in human cells.

immunology↗

bioRxiv2018

cGAS is predominantly a nuclear protein

cGAS is an intracellular innate immune sensor that detects double-stranded DNA. The presence of billions of base pairs of genomic DNA in all nucleated cells raises the question of how cGAS is not constitutively activated. A widely accepted explanation for this is the sequestration of cGAS in the cytosol, which is thought to prevent cGAS from accessing nuclear DNA. Here, we demonstrate that cGAS is predominantly a nuclear protein, regardless of cell cycle phase or cGAS activation status. We show that nuclear cGAS is tethered tightly by a salt-resistant interaction. This tight tethering is independent of the domains required for cGAS activation, and it requires intact nuclear chromatin. We propose that tethering prevents activation of cGAS by genomic DNA, and that it might enable cGAS to distinguish between self DNA and foreign DNA within the nucleus.

immunology↗