Project description:Metabolic reprogramming is an active regulator of stem cell fate choices, and successful stem cell differentiation in different compartments requires the induction of oxidative phosphorylation. However, the mechanisms that promote mitochondrial respiration during stem cell differentiation are poorly understood. Here we demonstrate that Stat3 promotes muscle stem cell myogenic lineage progression by stimulating mitochondrial respiration. We identify Fam3a, a cytokine-like protein, as a major Stat3 downstream effector in muscle stem cells. We demonstrate that Fam3a is required for muscle stem cell commitment and skeletal muscle development. We show that myogenic cells secrete Fam3a, and exposure of Stat3-ablated muscle stem cells to recombinant Fam3a in vitro and in vivo rescues their defects in mitochondrial respiration and myogenic commitment. Together, these findings indicate that Fam3a is a Stat3-regulated secreted factor that promotes muscle stem cell oxidative metabolism and differentiation, and suggests that Fam3a is a potential tool to modulate cell fate choices.
Project description:Metabolic stress and changes in nutrient levels modulate many aspects of skeletal muscle function during aging and disease. Growth factors and cytokines secreted by skeletal muscle, known as myokines, are important signaling factors but it is largely unknown whether they modulate muscle growth and differentiation in response to nutrients. Here, we find that changes in glucose levels increase the activity of the glucose-responsive transcription factor MLX, which promotes and is necessary for myoblast fusion. MLX promotes myogenesis not via an adjustment of glucose metabolism but rather by inducing the expression of several myokines, including insulin like-growth factor-2 (IGF2), whereas RNAi and dominant-negative MLX reduce IGF2 expression and block myogenesis. This phenotype is rescued by conditioned media from control muscle cells and by recombinant IGF2, which activates the myogenic kinase Akt. Importantly, MLX null mice display decreased IGF2 induction and diminished muscle regeneration in response to injury, indicating that the myogenic function of MLX is conserved in vivo. Thus, glucose is a signaling molecule that regulates myogenesis and muscle regeneration via MLX/IGF2/Akt signaling.â??The data pproided are histome H4 acetlation data for MLX DN and MLX wt samples; 3 MLX DN H4 Ac Chip seq samples , 3 Inputs, 3 MLX WT H4 Ac samples and 3 WT inputs
Project description:This study is to identify downstream genes regulated by STAT3 in response cytosolic acidification. Dysregulated intracellular pH is emerging as a hallmark of cancer. In spite of their acidic environment, cancer cells maintain alkaline intracellular pH (≥7.4) that promotes cancer progression by inhibiting apoptosis and increasing glycolysis, cell growth, migration and invasion. Here, we identify signal transducer and activator of transcription 3 (STAT3) as a key player in the maintenance of alkaline cytosolic pH. STAT3 associates with the vacuolar H+-ATPase on lysosomal membranes in a coiled coil domain-dependent manner and increases its activity in living cells and in vitro. Accordingly, STAT3 depletion disrupts intracellular proton equilibrium by decreasing and increasing cytosolic and lysosomal pH, respectively. This dysregulation can be reverted by reconstitution with wild type STAT3 as well as STAT3 mutants unable to activate target genes (Tyr-705-Phe and DNA binding mutant) or to regulate mitochondrial respiration (Ser-727-Ala). Upon cytosolic acidification, phospho-Tyr-705-STAT3 is rapidly dephosphorylated, transcriptionally inactivated and further recruited to lysosomal membranes to reestablish intracellular proton equilibrium and to enhance cell survival. These data reveal STAT3 as a regulator of intracellular pH, and vice versa intracellular pH as a regulator of STAT3 localization and activity.
Project description:Myeloid derived suppressor cells (MDSCs) are key regulators of immune responses and correlated with poor outcomes in hematologic malignancies. Here, we identify the mitochondrial fitness in MDSCs controlling the efficacy of doxorubicin chemotherapy for lymphoma. Mechanistically, we show that triggering STAT3 signaling via β2-adrenergic receptor (β2-AR) activation leads to metabolic reprograming of MDSCs, marked by sustained mitochondrial respiration (OX/PHOS) and higher ATP generation which reduces the AMPK signaling. Furthermore, induced STAT3 signaling in MDSCs enhanced glutamine consumption via the tricarboxylic acid (TCA) cycle. Metabolized glutamine generates itaconate which downregulates mitochondrial reactive oxygen species (mROS) via regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and the antioxidant machinery. We found that targeting the STAT3 pathway or ATP/Itaconate metabolites by blocking β2-AR signaling, the electron transport chain and ATP generation, or itaconate generation, results in disrupted MDSC mitochondrial fitness. This disruption increases the in vivo response to doxorubicin, delaying lymphoma progression.
Project description:While skeletal myogenesis is tightly coordinated by myogenic regulatory factors including MyoD and myogenin, chromatin modifications have emerged as vital mechanisms of myogenic regulation. We have previously established that bexarotene, a clinically approved agonist of retinoid X receptor, promotes the specification and differentiation of skeletal muscle lineage. Here, we examine a genome-wide impact of rexinoids on myogenic differentiation through integral RNA-seq and ChIP-seq analyses. We found that bexarotene promotes myoblast differentiation through the coordination of exit from the cell cycle and the activation of muscle-related genes. We uncovered a new mechanism of rexinoid action which is mediated by the nuclear receptor and largely reconciled through a direct regulation of MyoD gene expression. In addition, we determined a rexinoid-responsive residue-specific histone acetylation at a distinct chromatin state associated to MyoD and myogenin. Thus, we provide novel molecular insights into the interplay between retinoid X receptor signaling and chromatin states pertinent to myogenic programs in early myoblast differentiation.
Project description:While skeletal myogenesis is tightly coordinated by myogenic regulatory factors including MyoD and myogenin, chromatin modifications have emerged as vital mechanisms of myogenic regulation. We have previously established that bexarotene, a clinically approved agonist of retinoid X receptor, promotes the specification and differentiation of skeletal muscle lineage. Here, we examine a genome-wide impact of rexinoids on myogenic differentiation through integral RNA-seq and ChIP-seq analyses. We found that bexarotene promotes myoblast differentiation through the coordination of exit from the cell cycle and the activation of muscle-related genes. We uncovered a new mechanism of rexinoid action which is mediated by the nuclear receptor and largely reconciled through a direct regulation of MyoD gene expression. In addition, we determined a rexinoid-responsive residue-specific histone acetylation at a distinct chromatin state associated to MyoD and myogenin. Thus, we provide novel molecular insights into the interplay between retinoid X receptor signaling and chromatin states pertinent to myogenic programs in early myoblast differentiation.
Project description:We identified four major temporal patterns of Calcineurin (Cn)-dependent gene expression in differentiating myoblasts and determined that Cn is broadly required for the activation of the myogenic gene expression program. Cn promotes gene expression through direct binding to myogenic promoter sequences and facilitating the binding of BRG1 and other SWI/SNF subunit proteins as well as the binding of MyoD, a critical lineage determinant for skeletal muscle differentiation. We conclude that the Cn phosphatase directly impacts the expression of myogenic genes by promoting ATP-dependent chromatin remodeling and formation of transcription-competent promoters.
Project description:Pulmonary arterial hypertension (PAH) is a vascular remodeling disease characterized by enhanced pulmonary artery smooth muscle cell (PASMC) proliferation and suppressed apoptosis. Downregulation of the BMPR2 gene along with activation of the transcription factor NFAT have been implicated in the maintenance of pro-proliferative and anti-apoptotic stages of cells. Since an increasing number of microRNAs have been implicated in the regulation of genes specifically important for cell proliferation and apoptosis, we hypothesized that microRNAs might be associated with these cellular features in the etiology of PAH. We demonstrate that downregulation of one such microRNA (miR-204) in human PAH-PASMC promotes the activation of an Src/STAT3/NFAT axis that increases PAH-PASMC proliferation and their resistance to apoptosis. Stimulation experiments using the pro-PAH factors (PDGF, endothelin-1 and angiotensin II) and time course analysis in experimental PAH show that STAT3 activation leads to miR-204 downregulation, thereby activating an Src-dependent positive feedback loop sustaining STAT3 and activating NFAT. More importantly, restoring miR-204 expression decreases proliferation and resistance to apoptosis in human and in an experimental PAH model. Taken together, our study uncovers a new STAT3-miR-204-Src/STAT3/NFAT axis that links the STAT3-dependent downregulation of BMPR2 with the NFAT-mediated pro-proliferative and anti-apoptotic phenotype observed in PAH. Our data point toward a novel potential strategy for treating patients with PAH. Comparative expression profiling of PAH versus healthy patients to evaluate the modulated genes in the disease. Following the demonstration of the downregulation of miR-204 in PAH we want to investigate the effect of the inhibition (using antagomir) of miR-204 expression in PASMC cells.
Project description:Pulmonary arterial hypertension (PAH) is a vascular remodeling disease characterized by enhanced pulmonary artery smooth muscle cell (PASMC) proliferation and suppressed apoptosis. Downregulation of the BMPR2 gene along with activation of the transcription factor NFAT have been implicated in the maintenance of pro-proliferative and anti-apoptotic stages of cells. Since an increasing number of microRNAs have been implicated in the regulation of genes specifically important for cell proliferation and apoptosis, we hypothesized that microRNAs might be associated with these cellular features in the etiology of PAH. We demonstrate that downregulation of one such microRNA (miR-204) in human PAH-PASMC promotes the activation of an Src/STAT3/NFAT axis that increases PAH-PASMC proliferation and their resistance to apoptosis. Stimulation experiments using the pro-PAH factors (PDGF, endothelin-1 and angiotensin II) and time course analysis in experimental PAH show that STAT3 activation leads to miR-204 downregulation, thereby activating an Src-dependent positive feedback loop sustaining STAT3 and activating NFAT. More importantly, restoring miR-204 expression decreases proliferation and resistance to apoptosis in human and in an experimental PAH model. Taken together, our study uncovers a new STAT3-miR-204-Src/STAT3/NFAT axis that links the STAT3-dependent downregulation of BMPR2 with the NFAT-mediated pro-proliferative and anti-apoptotic phenotype observed in PAH. Our data point toward a novel potential strategy for treating patients with PAH. Comparative expression profiling of PAH versus healthy patients to evaluate the modulated genes in the disease. Following the demonstration of the downregulation of miR-204 in PAH we want to investigate the effect of the inhibition (using antagomir) of miR-204 expression in PASMC cells.