Project description:Analysis of the transcriptome of cardiac tissue from mice trangenically engineered with a doxycycline inducible Tafazzin shRNA knockdown to mimic the loss of function of Tafazzin in Barth syndrome. ShRNA induced knockdown mice were compared to wildtype littermates also fed the doxycyline diet. The hypothesis was to investigate adaptive metabolic and compensatory gene transcriptional changes in myocardium of the mouse model of Barth syndrome Total RNA obtained from 2 month old cardiac tissue from the doxycycline inducible shRNA Tafazzin knockdown mouse model of Barth syndrome compared to wildtype littermates also fed 625 mg/Kg doxycycline diet
Project description:Analysis of the transcriptome of cardiac tissue from mice trangenically engineered with a doxycycline inducible Tafazzin shRNA knockdown to mimic the loss of function of Tafazzin in Barth syndrome. ShRNA induced knockdown mice were compared to wildtype littermates also fed the doxycyline diet. The hypothesis was to investigate adaptive metabolic and compensatory gene transcriptional changes in myocardium of the mouse model of Barth syndrome
Project description:To identify novel, cell-specific, pathological pathways that mediate heart dysfunction in Barth Syndrome, we performed single-nucleus RNA-sequencing (snRNA-seq) on wild type and Tafazzin-knockout mouse hearts.
Project description:Mitochondria fulfill vital metabolic functions and act as crucial cellular signaling hubs integrating their metabolic status into the cellular context. Here, we show that defective cardiolipin-remodeling, upon loss of the cardiolipin acyl transferase Tafazzin, mutes HIF-1a signaling in hypoxia. Tafazzin-deficiency does not affect posttranslational HIF-1a regulation but rather HIF-1a gene-expression, a dysfunction recapitulated in iPSCs-derived cardiomyocytes from Barth Syndrome patients with Tafazzin-deficiency. RNAseq analyses confirmed drastically altered signaling in Tafazzin mutant cells. In hypoxia, Tafazzin-deficient cells display reduced production of reactive oxygen species (ROS) perturbing NF-kB activation and concomitantly HIF-1a gene-expression. In agreement, Tafazzin-deficient mice hearts display reduced HIF-1a levels and undergo maladaptive hypertrophy with heart failure in response to pressure overload challenge. We conclude that defective mitochondrial cardiolipin-remodeling dampens HIF-1a signaling through inactivation of a non-canonical signaling pathway: Lack of NF-kB activation through reduced mitochondrial ROS production diminishes HIF-1a transcription.
Project description:Barth Syndrome (BTHS) is an inherited cardiomyopathy caused by defects in the mitochondrial transacylase TAFAZZIN (Taz), required for the synthesis of the phospholipid cardiolipin. BTHS is characterized by heart failure, increased propensity for arrhythmias and a blunted inotropic reserve. Defects in Ca2+-induced Krebs cycle activation contribute to these functional defects, but despite oxidation of pyridine nucleotides, no oxidative stress developed in the heart. Here, we investigated how retrograde signaling pathways orchestrate metabolic rewiring to compensate for mitochondrial defects. In mice with an inducible knockdown (KD) of TAFAZZIN, mitochondrial uptake and oxidation of fatty acids was strongly decreased, while glucose uptake was increased. Unbiased transcriptomic analyses revealed that the activation of the eIF2/ATF4 axis of the integrated stress response upregulates one-carbon metabolism, which diverts glycolytic intermediates towards the biosynthesis of serine and fuels the biosynthesis of glutathione. In addition, strong upregulation of the glutamate/cystine antiporter xCT increases cardiac cystine import required for glutathione synthesis. Increased glutamate uptake facilitates anaplerotic replenishment of the Krebs cycle, sustaining energy production and antioxidative pathways. These data indicate that ATF4-driven rewiring of metabolism compensates for defects in mitochondrial uptake of fatty acids to sustain energy production and antioxidation.
Project description:Mitochondria are central for cellular metabolism and energy supply. Barth Syndrome (BTHS) is a severe disorder due to dysfunction of the mitochondrial cardiolipin acyl transferase tafazzin. Altered cardiolipin remodeling affects mitochondrial inner membrane organization and function of membrane proteins such as transporters and the oxidative phosphorylation (OXPHOS) system. Here, we describe a mouse model that carries a G197V exchange in tafazzin, corresponding to BTHS patient. TAZG197V mice recapitulate disease-specific pathology including cardiac dysfunction and reduced oxidative phosphorylation. We show that mutant mitochondria display defective fatty acid driven oxidative phosphorylation due to reduced levels of carnitine palmitoyl transferases. A metabolic switch in ATP production from OXPHOS to glycolysis is apparent in mouse heart and patient iPS cell-derived cardiomyocytes. An increase in glycolytic ATP production inactivates AMPK causing altered metabolic signaling in TAZG197V. Treatment of mutant cells with AMPK activator reestablishes fatty acid driven OXPHOS and protects mice against cardiac failure.
Project description:Mitochondria are central for cellular metabolism and energy supply. Barth Syndrome (BTHS) is a severe disorder due to dysfunction of the mitochondrial cardiolipin acyl transferase tafazzin. Altered cardiolipin remodeling affects mitochondrial inner membrane organization and function of membrane proteins such as transporters and the oxidative phosphorylation (OXPHOS) system. Here, we describe a mouse model that carries a G197V exchange in tafazzin, corresponding to BTHS patient. TAZG197V mice recapitulate disease-specific pathology including cardiac dysfunction and reduced oxidative phosphorylation. We show that mutant mitochondria display defective fatty acid driven oxidative phosphorylation due to reduced levels of carnitine palmitoyl transferases. A metabolic switch in ATP production from OXPHOS to glycolysis is apparent in mouse heart and patient iPS cell-derived cardiomyocytes. An increase in glycolytic ATP production inactivates AMPK causing altered metabolic signaling in TAZG197V. Treatment of mutant cells with AMPK activator reestablishes fatty acid driven OXPHOS and protects mice against cardiac failure.
Project description:VCaP cells expressing inducible shRNAs for either ERG or a non-targeting control were treated with Doxycycline for 1, 3, 7 and 10 days prior to collection This experiment is designed to see which genes and pathways are modulated by ERG knockdown VCaP cells stably expressing a Doxycycline (dox)-inducible control nontargeting shRNA (Pak4) or an ERG shRNA (2217) were exposed to 100ng/ml Dox for the noted days.
Project description:The goal of this study is to derive a mouse model of human Down Syndrome (DS) megakaryocytic leukemia involving mutations in the hematopoietic transcription factor, GATA1 (called GATA1s mutation). We achieved this through transduction of Gata1s mutant fetal progenitors by MSCV-based retrovirus expressing a GFP marker, followed by in vitro selection (for immortalized cell lines), and then in vivo selection (for transformed cell lines) through transplantation. Here we report one such cell line [T6(6)] that gives rise to megakaryocytic leukemia (M7 leukemia) upon transplantation. We show knockdown of IGF1R in these cells leads to their reduced proliferation. IGF1R was knocked down in these cells using a tet-regulatable shRNA-based lentiviral system. Cells infected with the empty vector or those infected with shRNA construct against IGF1R but in the absence of Doxycycline were used as controls. The latter cells in the presence of Doxycycline exhibited reduced IGF1R at the RNA level.
Project description:To determine the impact of ΔNp63α knockdown on steady-state mRNA levels, we performed poly(A)-enriched RNA-seq analysis of lung squamous cell carcinoma line H226 (inducible shControl and shp63) in the presence of 1µg/mL doxycycline to induce shRNA expression.
