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:ATRX is one of the most frequently altered genes in sarcoma and encodes an ATP-dependent chromatin remodeler implicated in maintaining heterochromatin. However, ATRX alterations have not been leveraged for sarcoma treatment. We observed loss of ATRX protein in 14% of soft tissue leiomyosarcoma (STLMS, n =127), 53% of uterine leiomyosarcoma (ULMS, n = 95), 37% of undifferentiated pleomorphic sarcoma (UPS, n = 82), and 8% of dedifferentiated liposarcoma (DDLPS, n = 84). ATRX loss was associated with significantly worse outcomes in ULMS, UPS, and DDLPS. ATRX knockout in sarcoma cells increased proliferation in cooperation with TP53 deletion. ATRX knockout led to chromatin de-repression and enrichment of PRDM4 and NFIX transcription factor (TF) motifs. PRDM4 and NFIX knockdown in ATRX-mutant sarcoma lines resulted in reduced proliferation and invasion suggesting epistatic relationship. Consistent with the known functional relationship between PRMD4 and YAP1, we observed that ATRX/TP53 KO cells were more sensitive to the TEAD inhibitor VT103 compared to TP53 KO and ATRX WT controls. Overall, our results identify ATRX loss as a prognostic factor of worse outcomes, implicate the ATRX-PRDM4-YAP1 axis as a novel underlying mechanism, and suggest use of TEAD inhibition as a potential therapeutic strategy for ATRX-deficient sarcomas.
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:The X-linked α-thalassaemia intellectual disability syndrome (ATRX) protein is a chromatin remodeller involved in transcriptional regulation and genome stability. While the importance of ATRX in development and malignancy is well recognised, its role in innate immunity is less well defined. Here we describe three unrelated patients with ATR-X syndrome carrying missense mutations in the ATPase domain of ATRX, each manifesting features of severe inflammation accompanied by persistent upregulation of interferon-stimulated gene expression in whole blood. Studies in patient-derived cells, CRISPR-engineered fibroblasts and neuronal models demonstrate that ATRX loss-of-function mutations drive enhanced type I interferon signalling through a cGAS-dependent mechanism uncoupled from the DNA sensing activity of cGAS. Mechanistically, ATRX deficiency disrupts the chromatin distribution of DAXX and H3.3, with cGAS essential for the changes in nucleosome composition and gene expression mediated by loss of ATRX. Thus, our study highlights a previously unrecognized link between ATRX dysfunction and inflammation involving a non-canonical role of cGAS.