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
Project description:To describe the protein profile in hippocampus, colon and ileum tissue’ changing after the old faeces transplants, we adopted a quantitative label free proteomics approach.
Project description:The generation of sufficient numbers of mature ventricular myocytes for effective cell-based therapy is a central barrier for cardiac regenerative medicine. Here we demonstrate that induced pluripotent stem cells (iPSCs) can be derived from murine ventricular myocytes, and consistent with other reports of iPSCs derived from various somatic cell types, ventricular myocyte derived iPSCs (ViPSCs) exhibit a markedly higher propensity to differentiate into beating cardiomyocytes as compared to genetically-matched embryonic stem cells (ESCs) or iPSCs derived from tail-tip fibroblasts. Strikingly, ViPSC-derived cardiomyocytes form up to 99% ventricular myocytes suggesting that ventricular myocyte-derived iPSCs may be a viable strategy to generate specific cardiomyocyte subtypes for cell-based therapies. The enhanced ventricular myogenesis in ViPSCs is mediated via increased numbers of cardiovascular progenitors at early stages of differentiation. In order to investigate the mechanism of enhanced ventricular myogenesis from ViPSCs, we performed global gene expression and DNA methylation analysis, which revealed a distinct epigenetic signature that may be involved in specifying the ventricular myocyte fate in pluripotent stem cells. Total RNA was extracted from mouse ES cells, tail tip fibroblasts (TTFs), ventricular myocytes (VMs), TTF-derived induced pluripotent stem cells (TiPSCs) and VM-derived induced pluripotent stem cells (ViPSCs). Global gene expression profiling was performed using affymetrix mouse 430 2.0 gene arrays.
Project description:Growth and expansion of ventricular chambers is essential during cardiogenesis and is achieved by proliferation of cardiac progenitors that are not fully differentiated. Disruption of this process can lead to prenatal lethality. In contrast, adult cardiomyocytes achieve growth through hypertrophy rather than hyperplasia. Although epicardial-derived signals may contribute to the proliferative process in myocytes, the factors and cell types responsible for development of the ventricular myocardial thickness are unclear. Moreover, the function of embryonic cardiac fibroblasts, derived from epicardium, and their secreted factors are largely unknown. Using a novel co-culture system, we found that embryonic cardiac fibroblasts induced proliferation of cardiomyocytes, in contrast to adult cardiac fibroblasts that promoted myocyte hypertrophy. We identified fibronectin, collagen and heparin-binding EGF-like growth factor as embryonic cardiac fibroblast-specific signals that collaboratively promoted cardiomyocyte proliferation in a paracrine fashion. b1 integrin was required for this proliferative response, and ventricular cardiomyocyte-specific deletion of b1 integrin in mice resulted in reduced myocardial proliferation and impaired ventricular compaction. These findings reveal a previously unrecognized paracrine function of embryonic cardiac fibroblasts in regulating cardiomyocyte proliferation. To identify candidate fibroblast-derived factors that promote myocyte proliferation, we isolated RNA from Nkx-YFP+ cardiomyocytes, embryonic cardiac fibroblasts, and adult cardiac fibroblasts and profiled mRNA expressions by microarray analyses. Arrays were performed using Affymetrix mouse Gene 1.0 ST arrays. Analysis was performed on three biological replicates of mouse embyonic cardiomyocytes, fibroblasts and adult cardiac fibroblasts.
Project description:Cardiac Purkinje cells (PCs) comprise the most distal portion of the ventricular conduction system (VCS) and are essential for synchronous activation of the ventricular myocardium. Contactin-2 (CNTN2), a member of the immunoglobulin superfamily cell adhesion molecules (IgSF-CAMs), was previously identified as a marker of the VCS. Through differential transcriptional profiling we discovered two additional highly enriched IgSF-CAMs in the VCS, NCAM-1 and ALCAM. Immunofluorescence staining showed dynamic expression patterns for each IgSF-CAM during embryonic and early post-natal stages, but ultimately all three proteins became highly enriched in mature PCs. Mice deficient in NCAM-1, but not CNTN2 or ALCAM, exhibited defects in Purkinje cell gene expression and VCS patterning, as well as cardiac conduction disease. Moreover, using ST8sia2 and ST8sia4 knockout mice, we show that inhibition of post-translational modification of NCAM-1 by polysialic acid (PSA) disrupts trafficking of sarcolemmal intercalated disc proteins to Purkinje cell junctional membranes and abnormal expansion of the extracellular space between apposing Purkinje cells. Taken together, our data provide novel insights into the complex developmental biology of the ventricular conduction system.
Project description:The generation of sufficient numbers of mature ventricular myocytes for effective cell-based therapy is a central barrier for cardiac regenerative medicine. Here we demonstrate that induced pluripotent stem cells (iPSCs) can be derived from murine ventricular myocytes, and consistent with other reports of iPSCs derived from various somatic cell types, ventricular myocyte derived iPSCs (ViPSCs) exhibit a markedly higher propensity to differentiate into beating cardiomyocytes as compared to genetically-matched embryonic stem cells (ESCs) or iPSCs derived from tail-tip fibroblasts. Strikingly, ViPSC-derived cardiomyocytes form up to 99% ventricular myocytes suggesting that ventricular myocyte-derived iPSCs may be a viable strategy to generate specific cardiomyocyte subtypes for cell-based therapies. The enhanced ventricular myogenesis in ViPSCs is mediated via increased numbers of cardiovascular progenitors at early stages of differentiation. In order to investigate the mechanism of enhanced ventricular myogenesis from ViPSCs, we performed global gene expression and DNA methylation analysis, which revealed a distinct epigenetic signature that may be involved in specifying the ventricular myocyte fate in pluripotent stem cells.