Project description:RNA sequencing of wild-type or Interferon Alpha receptor 1 Knockout MEF cells treated with DMSO or the Caspase Inhibitor Q-VD-OPh. The mechanism by which cells undergo death determines whether dying cells trigger inflammatory responses or remain immunologically silent. Mitochondria play a central role in the induction of cell death, as well as in immune signaling pathways. Here, we identify of a mechanism by which mitochondria and downstream pro-apoptotic caspases regulate the activation of antiviral immunity. In the absence of active caspases, mitochondrial outer membrane permeabilization by Bax and Bak results in the expression of type I interferons (IFNs). This induction is mediated by mitochondrial DNA-dependent activation of the cGAS/STING pathway and results in the establishment of a potent state of viral resistance. Our results show that mitochondria have the capacity to simultaneously expose a cell-intrinsic inducer of the IFN response, and to inactivate this response in a caspase-dependent manner. This mechanism provides a dual control, which determines whether mitochondria initiate an immunologically silent or a pro-inflammatory type of cell death. In order to determine whether the pharmacological inhibition of caspases could activate the type I interferon response, we treated WT MEFs with the caspase inhibitor Q-VD-OPH. The inhibitor induced an increased expression of ISGs, which was dependent on type I IFN receptor (IFNAR1) signaling.
Project description:RNA sequencing of wild-type or Interferon Alpha receptor 1 Knockout MEF cells treated with DMSO or the Broad-spectrum Caspase Inhibitor Q-VD-OPh The mechanism by which cells undergo death determines whether dying cells trigger inflammatory responses or remain immunologically silent. Mitochondria play a central role in the induction of cell death, as well as in immune signaling pathways. Here, we identify of a mechanism by which mitochondria and downstream pro-apoptotic caspases regulate the activation of antiviral immunity. In the absence of active caspases, mitochondrial outer membrane permeabilization by Bax and Bak results in the expression of type I interferons (IFNs). This induction is mediated by mitochondrial DNA-dependent activation of the cGAS/STING pathway and results in the establishment of a potent state of viral resistance. Our results show that mitochondria have the capacity to simultaneously expose a cell-intrinsic inducer of the IFN response, and to inactivate this response in a caspase-dependent manner. This mechanism provides a dual control, which determines whether mitochondria initiate an immunologically silent or a pro-inflammatory type of cell death. To determine whether the pharmacological inhibition of caspases could recapitulate the phenotype caused by genetic deficiencies, we treated WT MEFs with broad-spectrum inhibitors of caspases (Q-VD-OPH). The inhibitor induced an increased expression of ISGs, similar to the effect of caspase or Apaf-1 deficiency. Next, we compared the transcriptional changes induced by caspase inhibition in WT and IFNAR1 KO cells, which lack a critical subunit of the receptor for IFNα/β (Muller et al., 1994). We observed that the absence of the IFNAR receptor abrogated the transcriptional response of the cells to caspase inhibition by Q-VD-OPH, demonstrating the role of type I IFNs in this response. RNA was extracted from duplicate samples and libraries generated for sequencing using the directional RNA-Seq library prep at the Yale Center for Genome Analysis. Libraries were sequenced using a Hiseq2500 sequencer to generate 76bp single-end reads. Duplicate samples were analyzed for each condition.
Project description:We created mice, which are deficient for Myc specifically in cardiac myocytes by crossing crossed Myc-floxed mice (Mycfl/fl) and MLC-2VCre/+ mice. Serial analysis of earlier stages of gestation revealed that Myc-deficient mice died prematurely at E13.5-14.5. Morphological analyses of E13.5 Myc-null embryos showed normal ventricular size and structure; however, decreased cardiac myocyte proliferation and increased apoptosis was observed. BrdU incorporation rates were also decreased significantly in Myc-null myocardium. Myc-null mice displayed a 3.67-fold increase in apoptotic cardiomyocytes by TUNEL assay. We examined global gene expression using oligonucleotide microarrays. Numerous genes involved in mitochondrial death pathways were dysregulated including Bnip3L and Birc2. Hearts were taken from wide type and Myc-null Mouse embryos at E13.5 under the dissecting scope. Cardiac myocyte RNA was isolated using TRIZOL®Reagent Total RNA (100 ng) was hybridized to the Sentrix® MouseRef-8 Expression BeadChip that contains probes for ~24,000 transcripts. GeneChips were scanned using the Hewlett-Packard GeneArray Scanner G2500A. The data were analyzed with Illumina Inc. BeadStudio version 1.5.0.34 and normalized by rank invariant method.
Project description:We created mice, which are deficient for Myc specifically in cardiac myocytes by crossing crossed Myc-floxed mice (Mycfl/fl) and MLC-2VCre/+ mice. Serial analysis of earlier stages of gestation revealed that Myc-deficient mice died prematurely at E13.5-14.5. Morphological analyses of E13.5 Myc-null embryos showed normal ventricular size and structure; however, decreased cardiac myocyte proliferation and increased apoptosis was observed. BrdU incorporation rates were also decreased significantly in Myc-null myocardium. Myc-null mice displayed a 3.67-fold increase in apoptotic cardiomyocytes by TUNEL assay. We examined global gene expression using oligonucleotide microarrays. Numerous genes involved in mitochondrial death pathways were dysregulated including Bnip3L and Birc2. Keywords: wildtype vs Myc-null