Project description:Serum Response Factor (SRF) is a transcriptional regulator required for mesodermal development. Numerous studies have implicated SRF as a central regulator of muscle gene expression and myogenesis. In this present study we used a loss of function approach to delineate the role of SRF in cardiac myocyte gene expression and function. In SRF null neonatal cardiomyocytes, we observe severe defects in the contractile apparatus, including Z-disc and stress fiber formation, as well as mislocalization and/or attenuation of sarcomeric proteins. Consistent with this, gene array and RT-PCR analyses show downregulation of genes encoding key cardiac transcriptional regulatory factors and proteins required for the maintenance of sarcomeric structure, function, and regulation. Chromatin IP analysis reveals that at least a subset of these proteins are likely regulated directly by SRF. Together the results presented here reveal new cellular and genetic mechanisms through which SRF exacts control over the contractile apparatus in cardiac myocytes. Experiment Overall Design: There are three control replicates (cardiomyocytes transduced with Adeno-GFP virus) and three experimental replicates (cardiomyocytes transduced with Adeno-CRE to excise SRF).
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: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:Serum Response Factor (SRF) is a transcriptional regulator required for mesodermal development. Numerous studies have implicated SRF as a central regulator of muscle gene expression and myogenesis. In this present study we used a loss of function approach to delineate the role of SRF in cardiac myocyte gene expression and function. In SRF null neonatal cardiomyocytes, we observe severe defects in the contractile apparatus, including Z-disc and stress fiber formation, as well as mislocalization and/or attenuation of sarcomeric proteins. Consistent with this, gene array and RT-PCR analyses show downregulation of genes encoding key cardiac transcriptional regulatory factors and proteins required for the maintenance of sarcomeric structure, function, and regulation. Chromatin IP analysis reveals that at least a subset of these proteins are likely regulated directly by SRF. Together the results presented here reveal new cellular and genetic mechanisms through which SRF exacts control over the contractile apparatus in cardiac myocytes. Keywords: genetic modification