Project description:RNA sequencing of isogenic ATRX wild-type (WT) and ATRX knockout (KO) paired isogenic cell lines treated with either 1.)interferon stimulatory DNA (ISD) and harvested 24 hours after treatment, 2)4 Gy ionizing radiation and harvested 36 hours after treatment, or 3) untreated control. These experiments help determine the differential impact of ATRX mutational status on cGAS-STING and type-I interferon signaling in soft tissue sarcoma.
Project description:RNA sequencing of a primary tumors from a sarcoma genetically engineerted mouse model with activation of oncogenic Kras, deletion of p53 and deletion of Atrx, as compared to control sarcomas with identical genetic alterations but with wild-type Atrx. Tumors were either untreated or recieved 20 Gy of ionizing radiation and were harvested at 4 hrs, 3 day, or 6 day timepoints post treatment. For cell lines, isogenic ATRX wild-type (WT) and ATRX knockout (KO) paired isogenic cell lines treated with either 1.)interferon stimulatory DNA (ISD) and harvested 24 hours after treatment, 2)4 Gy ionizing radiation and harvested 36 hours after treatment, or 3) untreated control. These experiments help determine the differential impact of ATRX mutational status on cGAS-STING and type-I interferon signaling in soft tissue sarcoma.
Project description:Gammaherpesviruses, including Kaposi’s sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are DNA viruses that are globally associated with human cancers and establish lifelong latency in the human population. Detection of gammaherpesviral infection by the cGAS-STING innate immune DNA-sensing pathway is critical for suppressing viral reactivation from latency, a process that promotes viral pathogenesis and transmission. We report that Barrier-to-autointegration factor 1 (BAF)-mediated suppression of the cGAS-STING signaling pathway is necessary for reactivation of KSHV and EBV. We demonstrate a novel role for BAF in destabilizing cGAS expression and show that BAF expression in latently infected, reactivating, or uninfected cells leads to suppression of type I interferon-mediated antiviral responses and inhibition of viral replication. Furthermore, BAF overexpression resulted in decreased cGAS expression at the protein level. These results establish BAF as a key regulator of the lifecycle of gammaherpesviruses and a potential target for treating viral infections and malignancies.
Project description:The DNA exonuclease TREX1 degrades endogenous cytosolic DNA. Cytosolic DNA triggers the cGAS/STING pathway which increases type I interferon. To investigate the physiological significance of TREX1 loss on in vivo tumor growth, we implanted control and TREX1-deficient CT26 tumor cells into immunocompetent BALB/c hosts.Tumor cells were collected 7 days after tumors reached around 200mm3.
Project description:Whole genome and transcriptome sequencing of a cohort of 67 leiomyosarcomas revealed ATRX to be one of the most frequently mutated genes in LMS after TP53 and RB1. While its function is well described in the ALT mechanism, we wondered whether its alteration could have complementary effects on sarcoma oncogenesis. ATRX alteration is associated with the down-expression of genes linked to differentiation in LMS, and to immunity in an additional cohort of 60 poorly differentiated sarcomas. In vitro and in vivo models showed that ATRX loss increases tumor growth rate and immune escape by decreasing the immunity load of active mast cells in sarcoma tumors. These data indicate that an alternative to unsuccessful targeting of the adaptive immune system in sarcoma could be to target the innate system. This might lead to a better outcome for sarcoma patients in terms of ATRX status.
Project description:Type I interferon (IFN) signalling is tightly controlled. Upon recognition of DNA by cyclic GMP-AMP synthase (cGAS), stimulator of interferon genes (STING) translocates along the endoplasmic reticulum (ER)-Golgi axis to induce IFN signalling. Afterwards, signal termination is achieved through autophagic degradation of STING, or STING recycling by retrograde COPI-mediated transport. Here we identify the GTPase ARF1 as a negative regulator of cGAS-STING signaling. Heterozygous ARF1 missense mutations cause a novel type I interferonopathy associated with enhanced IFN stimulated gene production. Expression of patient-derived, GTPase-defective, ARF1 in cell lines and primary cells results in increased cGAS-STING dependent type I IFN signalling. Mechanistically, mutated ARF1 both induces activation of cGAS by aberrant mitochondrial DNA, and promotes accumulation of active STING at the Golgi/ERGIC due to defective COPI retrograde transport. Our data establish ARF1 as a key factor in cGAS-STING homeostasis, which is required to maintain mitochondrial integrity and promote STING recycling.
Project description:The cGAS-cGAMP-STING pathway is crucial for antiviral immunity. While cytosolic cGAS detects viral DNA, most DNA viruses shield their genome and invade the nucleus, where chromatin restricts cGAS activation. How viruses may activate nuclear cGAS is not well understood. Here, we show that several herpesvirus proteins trigger nuclear cGAS activation by perturbing centromeres, where cGAS is enriched. The herpes simplex virus type 1 (HSV-1) ubiquitin ligase ICP0, which degrades centromeric proteins, promotes centromeric DNA amplification through the translesion DNA synthesis (TLS) pathway in quiescent monocyte-derived cells, thereby activating nuclear cGAS. During infection, HSV-1 evades this detection by also expressing UL36USP, a suppressor of TLS. Similarly to ICP0, the cytomegalovirus IE1 protein causes centromeric DNA amplification and cGAS activation. We define this mechanism as Viral-Induced Centromeric DNA Amplification and Recognition (VICAR), uncovering a non-mitotic, immune-activating role of centromeres.
Project description:Histone deacetylase 6 (HDAC6), a member of the class IIB HDAC family, has distinct biological functions through primarily deacetylating cytoplasmic non-histone proteins. However, its regulatory role in response to DNA virus infection remains elusive. Herein, we find that HDAC6 is a negative regulator of the cGAS-STING signaling pathway. HDAC6 deacetylase activity is increased in the early stage of Herpes simplex virus 1 (HSV-1) infection, and HDAC6 deficiency or inhibition of its deacetylase activity markedly promotes the activation of the cGAS-STING axis, resulting in increased expression of type I interferon (IFN) and a decrease in HSV-1 infection. Consistently, the Hdac6-/- mice exhibit increased resistance to HSV-1 infection and HSV-1 induced encephalitis (HSE). The HDAC6-interactome and Acetylome proteomics assays reveal that HDAC6 interacts with and deacetylates Tripartite motif protein 56 (TRIM56) at K110 within the B-box1 domain, leading to the reduced monoubiquitination and DNA binding of cGAS by TRIM56. In addition, acetylation of TRIM56 K110 is key to its binding to HDAC6 and regulating the IFN response, as evidenced by the opposing outcomes observed upon overexpressing TRIM56 K110Q and K110R on the cGAS-STING axis. Overexpression of TRIM56 K110Q further enhances protection against HSV-1 infection and HSE pathogenesis in mice, alongside increased activation of the cGAS-STING-IFN axis. Interestingly, TRIM56 displays species-specific K110, which differentially regulates the IFN response in humans and mice. Furthermore, HDAC6 accumulates in the cytoplasm and is phosphorylated by the viral protein US3, which increases its deacetylase activity and interaction with TRIM56 in the early infection stage. Together, our findings disclose that HDAC6 negatively regulates cGAS activation through TRIM56 deacetylation, suggesting a potential antiviral strategy by inhibiting HDAC6 activity.
Project description:The cGAS-STING pathway plays a central role in controlling tumor progression through nucleic acid sensing and type I Interferon production. Here, we identify Poly(rC) Binding Protein 1 (PCBP1) as a tumor suppressor that amplifies cGAS-STING signaling in breast cancer. Using patient datasets and a transgenic mouse model with conditional PCBP1 knockout in mammary epithelial cells, we show that PCBP1 expression correlates with improved survival, reduced tumor burden, increased type I IFN and ISG expression, and elevated cytotoxic T cell infiltration. Mechanistically, PCBP1 binds cytosine-rich single-stranded motifs via its KH domains and increases cGAS affinity to these nucleic acids. Disruption of the conserved GXXG motif impairs PCBP1's nucleic acid binding and cGAS activation. Although cGAS is a double-stranded DNA sensor with no intrinsic sequence specificity, we uncover that the single-stranded nucleic-acid binding protein PCBP1 enhances cGAS sensing by engaging sequence-specific motifs, acting as an important nucleic acid co-sensor that impairs tumorigenesis.