Project description:Epithelial-mesenchymal transition (EMT) is a complex and pivotal process involved in organogenesis and is related to several pathological processes, including cancer and fibrosis. During heart development, EMT mediates the conversion of epicardial cells into vascular smooth muscle cells and cardiac interstitial fibroblasts. Here, we show that the oncogenic transcription factor EB (TFEB) is a key regulator of EMT in epicardial cells and that its genetic overexpression in mouse epicardium is lethal due to heart defects linked to impaired EMT. TFEB specifically orchestrates the EMT-promoting function of transforming growth factor (TGF) β, and this effect results from activated transcription of thymine-guanine-interacting factor (TGIF)1, a TGFβ/Smad pathway repressor. The Tgif1 promoter is activated by TFEB, and in vitro and in vivo findings demonstrate its increased expression when Tfeb is overexpressed. Furthermore, Tfeb overexpression in vitro prevented TGFβ-induced EMT, and this effect was abolished by Tgif1 silencing. Tfeb loss of function, similar to that of Tgif1, sensitized cells to TGFβ, inducing an EMT response to low doses of TGFβ. Together, our findings reveal an unexpected function of TFEB in regulating EMT, which might provide new insights into injured heart repair and control of cancer progression.
Project description:The epicardium is a mesothelial layer covering the myocardium and contributes to different cardiac lineage descendants during cardiogenesis. Fine-tuned balanced signaling defines epicardial specification and regulates cell plasticity and cell-fate decisions of epicardial-derived cells (EPCDs) by epicardial-to-mesenchymal transition (EMT). However, powerful tools to investigate epicardial cell function, including markers with pivotal roles in developmental signaling, are still lacking. Here, we recapitulated embryonic epicardiogenesis using human induced pluripotent stem cells (hiPSCs) and identified type II classical cadherin CDH18 as a novel biomarker defining lineage specification in human developing epicardium. The loss of CDH18 led to the onset of EMT and specific differentiation towards cardiac smooth muscle cells. Furthermore, GATA4 regulated epicardial CDH18 expression. These results demonstrate the production and enrichment of hiPSC-derived epicardial cells via the tracing of CDH18 expression, providing a model for investigating epicardial function in human development and disease and enabling new possibilities for regenerative medicine.
Project description:Epicardial cells undergo an epithelial-to-mesenchymal transtion (EMT) to generate coronary vascular smooth muscle cells (VSMC) and cardiac fibroblasts. Little is known about the mechanisms regulating EMT or the in vivo signals directing epicardial-derived cell (EPDC) fate. Here, we show that loss of PDGF signaling leads to a disruption in Sox9 expression, and when Sox9 expression was restored in mutant hearts, the EMT defect was rescued. Interestingly, mutants lacking only one of the PDGF genes exhibited a lineage specific requirement for the individual receptors. Loss of PDGFRα resulted in a deficit in cardiac fibroblast formation, while cVSMC development was unperturbed. Conversely, PDGFRβ was required for cVSMC development but not cardiac fibroblast development. Combined, our data demonstrate a novel role for PDGF receptors in epicardial EMT and EPDC development. GSM671723-GSM671724: Total RNA was isolated from E12.5 control and PDGF receptor epicardial knockout hearts using the Trizol reagent. RNA was processed as per manufacturer's instructions (Illumina Gene expression array, Illumina, inc. San Diego, CA, USA) GSM671877-GSM671882: Total RNA was isolated from E12.5 control and PDGF receptor epicardial knockout primary epicardial cultures using the Trizol reagent. RNA was processed as per manufacturer's instructions (Illumina Gene expression array, Illumina, inc. San Diego, CA, USA)
Project description:Epicardial cells are progenitors giving rise to the majority of cardiac fibroblasts, coronary smooth muscle cells, and pericytes during cardiac development, and critically modulating heart morphogenesis and coronary development. An integral phase of epicardial cell fate transition is epithelial-to-mesenchymal transition (EMT), which confers motility and facilitates cell fate transition. We identify a pathway involving protein arginine methyltransferase 1 (PRMT1) and its downstream p53 signaling that drives epicardial EMT and invasion. We show that PRMT1 determines the half-life of p53 through regulating alternative splicing of Mdm4, which is a key controller of p53 degradation. Loss of PRMT1 promotes the expression of Mdm4 short form, which inhibits p53 degradation. Accumulation of p53 subsequently enhances Slug degradation and blocks epicardial EMT. We further demonstrated that the PRMT1-Mdm4-p53 pathway drives epicardial cell fate transition into cardiac fibroblasts, coronary smooth muscle cells and pericytes in vivo, and modulates ventricular morphogenesis and coronary vessel formation. Together, our results establish critical functions of the PRMT1-Mdm4-p53 pathway in epicardial EMT, invasion and cell fate transition.
Project description:Epicardial cells undergo an epithelial-to-mesenchymal transtion (EMT) to generate coronary vascular smooth muscle cells (VSMC) and cardiac fibroblasts. Little is known about the mechanisms regulating EMT or the in vivo signals directing epicardial-derived cell (EPDC) fate. Here, we show that loss of PDGF signaling leads to a disruption in Sox9 expression, and when Sox9 expression was restored in mutant hearts, the EMT defect was rescued. Interestingly, mutants lacking only one of the PDGF genes exhibited a lineage specific requirement for the individual receptors. Loss of PDGFRα resulted in a deficit in cardiac fibroblast formation, while cVSMC development was unperturbed. Conversely, PDGFRβ was required for cVSMC development but not cardiac fibroblast development. Combined, our data demonstrate a novel role for PDGF receptors in epicardial EMT and EPDC development.
Project description:Nonmuscle myosin IIB (NMIIB; heavy chain encoded by MYH10) is essential for cardiac myocyte cytokinesis. The role of NMIIB in other cardiac cells is not known. Here, we show that NMIIB is required in epicardial formation and functions to support myocardial proliferation and coronary vessel development. Ablation of NMIIB in epicardial cells results in disruption of epicardial integrity with a loss of E-cadherin at cell-cell junctions and a focal detachment of epicardial cells from the myocardium. NMIIB-knockout and blebbistatin-treated epicardial explants demonstrate impaired mesenchymal cell maturation during epicardial epithelial-mesenchymal transition. This is manifested by an impaired invasion of collagen gels by the epicardium-derived mesenchymal cells and the reorganization of the cytoskeletal structure. Although there is a marked decrease in the expression of mesenchymal genes, there is no change in Snail (also known as Snai1) or E-cadherin expression. Studies from epicardium-specific NMIIB-knockout mice confirm the importance of NMIIB for epicardial integrity and epicardial functions in promoting cardiac myocyte proliferation and coronary vessel formation during heart development. Our findings provide a novel mechanism linking epicardial formation and epicardial function to the activity of the cytoplasmic motor protein NMIIB.
Project description:Lysosomal degradation of the endoplasmic reticulum (ER) via autophagy (ER-phagy) is emerging as a critical regulator of cell homeostasis and function1. The recent identification of ER-phagy receptors has shed light on the molecular mechanism underlining this process; however, the signaling pathways regulating ER-phagy in response to cellular needs are still largely unknown. We found that the nutrient responsive transcription factors TFEB and TFE3 - master regulators of lysosomal biogenesis and autophagy2- control ER-phagy by inducing the expression of the ER-phagy receptor FAM134B. The TFEB/TFE3-FAM134B axis promotes ER-phagy activation upon prolonged starvation. In addition, we discovered that this pathway is activated in chondrocytes by FGF signaling, a critical regulator of cell differentiation 3. FGF signaling induces a JNK-dependent proteasomal degradation of the insulin receptor substrate 1, which inhibits the insulin-PI3K-PKB/Akt-mTORC1 pathway and promotes TFEB/TFE3 nuclear translocation and FAM134B induction. Consistent with a role of the TFEB/TFE3-FAM134B axis in chondrocytes, FAM134B knock-down impairs cartilage growth and mineralization in medaka fish. This study identifies a new signaling pathway that allows ER-phagy to respond to both metabolic and developmental cues.
Project description:In order to identify the effects of transcription factor EB (TFEB) overexpression on the liver transcriptome, we performed Affymetrix GeneChip hybridization experiments on injected mice overexpressing TFEB specifically in the liver. For the analysis of the injected mice overexpressing TFEB, total RNA was extracted from the liver of three mice. RNA extracted from the liver of 3 not-injected mice was used as a control.
Project description:Cardiac fibrosis is a detrimental pathophysiological state involved in a number of cardiovascular diseases. Myofibroblasts mediate fibrosis by excessive remodeling of the extracellular matrix, which ultimately leads to tissue stiffness and impaired heart performance. Recently, it was shown that a substantial fraction of cardiac myofibroblasts may originate from the epicardium through Epithelial-to-Mesenchymal Transition (EMT). We have developed a cellular model of EMT in which adult murine epicardium-derived cells are differentiated into myofibroblast-like cells in the presence of Interleukin-1beta, Tumor Necrosis Factor-alpha, or Transforming Growth Factor-beta. Using this model of EMT, the microRNAome was assessed by microRNA (miRNA) arrays. Subsequently, expression levels of differentially expressed miRNAs were validated by qPCR. These miRNAs were targeted by transfecting epicardium-derived cells with anti- or pre-miRs prior to EMT initiation. The ability of the anti- or pre-miRs to inhibit EMT was assessed on a number of phenotypic markers. In this study we have identified a number of miRNAs that potentially play an intrinsic role in cardiac EMT. We speculate that by targeting those miRNA, the onset and long-term progression of cardiac fibrosis can be substantially reduced. Epicardial mesothelial cells were isolated and expanded from the epicardium of adult rats (8-10 weeks). Epithelial-to-mesenchymal Transition was induced by 10 ng/mL Interleukin-1beta, Tumor Necrosis Factor-alpha, or Transforming Growth Factor-beta1 for 48h. The assocciated differential microRNA expressions relative to a control treatment was computed by microRNA arrays. The experiment was conducted on biological quadruplicates for the control treatment and biological triplicates for cytokine treatments.