Early Postnatal Cardiac Changes and Premature Death in Transgenic Mice Overexpressing a Mutant Form of Serum Response Factor

Harvard University, Cambridge, Massachusetts, United States
Journal of Biological Chemistry (Impact Factor: 4.57). 11/2001; 276(43):40033-40. DOI: 10.1074/jbc.M104934200
Source: PubMed


Serum response factor (SRF) is a key regulator of a number of extracellular signal-regulated genes important for cell growth and differentiation. A form of the SRF gene with a double mutation (dmSRF) was generated. This mutation reduced the binding activity of SRF protein to the serum response element and reduced the capability of SRF to activate the atrial natriuretic factor promoter that contains the serum response element. Cardiac-specific overexpression of dmSRF attenuated the total SRF binding activity and resulted in remarkable morphologic changes in the heart of the transgenic mice. These mice had dilated atrial and ventricular chambers, and their ventricular wall thicknesses were only 1/2 to 1/3 the thickness of that of nontransgenic mice. Also these mice had smaller cardiac myocytes and had less myofibrils in their myocytes relative to nontransgenic mice. Altered gene expression and slight interstitial fibrosis were observed in the myocardium of the transgenic mice. All the transgenic mice died within the first 12 days after birth, because of the early onset of severe, dilated cardiomyopathy. These results indicate that dmSRF overexpression in the heart apparently alters cardiac gene expression and blocks normal postnatal cardiac growth and development.

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    • "The plasmid pcDNA3-p49/STRAP containing the mouse p49/STRAP cDNA (accession # AY611629) was constructed as previously described [1]. Briefly, to make a transgenic DNA construct, a 2.7 kb DNA fragment containing CMV promoter, the mouse p49/STRAP cDNA and the BGH polyadenylation signal sequence was released from the plasmid pcDNA3-p49/STRAP using NruI and DraIII restriction enzymes, and was separated on a low melting gel and then isolated and purified as previously described [9,49]. "
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    ABSTRACT: Background The protein p49/STRAP (SRFBP1) is a transcription cofactor of serum response factor (SRF) which regulates cytoskeletal and muscle-specific genes. Results Two conserved domains were found in the p49/STRAP protein. The SRF-binding domain was at its N-terminus and was highly conserved among mammalian species, xenopus and zebrafish. A BUD22 domain was found at its C-terminus in three sequence databases. The BUD22 domain was conserved among mammalian p49/STRAP proteins, and yeast cellular morphogenesis proteins, which is involved in ribosome biogenesis that affects growth rate and cell size. The endogenous p49/SRAP protein was localized mainly in the nucleus but also widely distributed in the cytoplasm, and was in close proximity to the actin. Transfected GFP-p49/STRAP protein co-localized with nucleolin within the nucleolus. Overexpression of p49/STRAP reduced actin content in cultured cells and resulted in smaller cell size versus control cells. Increased expression of p49/STRAP in transgenic mice resulted in newborns with malformations, which included asymmetric abdominal and thoracic cavities, and substantial changes in cardiac morphology. p49/STRAP altered the expression of certain muscle-specific genes, including that of the SRF gene, which is a key regulator of cardiac genes at the developmental, structural and maintenance level and has two SRE binding sites. Conclusions Since p49/STRAP is a co-factor of SRF, our data suggest that p49/STRAP likely regulates cell size and morphology through SRF target genes. The function of its BUD22 domain warrants further investigation. The observed increase in p49/STRAP expression during cellular aging may contribute to observed morphological changes in senescence.
    BMC Cell Biology 09/2014; 15(1):32. DOI:10.1186/1471-2121-15-32 · 2.34 Impact Factor
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    • "Several recent findings from transgenic studies and human disorders indicate the importance of SRF in the myocardium. Heart-specific overexpression of SRF in transgenic mice led to the development of cardiac hypertrophy and cardiomyopathy [41], whereas overexpression of a mutant dominant-negative form of SRF led to a severe dilated cardiomyopathy [42]. Interestingly, here we demonstrated for the first time overexpression of SRF early at 1 week post-MI not only in the infarct core but also in the remote myocardial region. "
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    ABSTRACT: Molecular mechanisms associated with pathophysiological changes in ventricular remodelling due to myocardial infarction (MI) remain poorly understood. We analyzed changes in gene expression by microarray technology in porcine myocardial tissue at 1, 4, and 6 weeks post-MI. MI was induced by coronary artery ligation in 9 female pigs (30–40 kg). Animals were randomly sacrificed at 1, 4, or 6 weeks post-MI (n = 3 per group) and 3 healthy animals were also included as control group. Total RNA from myocardial samples was hybridized to GeneChip® Porcine Genome Arrays. Functional analysis was obtained with the Ingenuity Pathway Analysis (IPA) online tool. Validation of microarray data was performed by quantitative real-time PCR (qRT-PCR). More than 8,000 different probe sets showed altered expression in the remodelling myocardium at 1, 4, or 6 weeks post-MI. Ninety-seven percent of altered transcripts were detected in the infarct core and 255 probe sets were differentially expressed in the remote myocardium. Functional analysis revealed 28 genes de-regulated in the remote myocardial region in at least one of the three temporal analyzed stages, including genes associated with heart failure (HF), systemic sclerosis and coronary artery disease. In the infarct core tissue, eight major time-dependent gene expression patterns were recognized among 4,221 probe sets commonly altered over time. Altered gene expression of ACVR2B, BID, BMP2, BMPR1A, LMNA, NFKBIA, SMAD1, TGFB3, TNFRSF1A, and TP53 were further validated. The clustering of similar expression patterns for gene products with related function revealed molecular footprints, some of them described for the first time, which elucidate changes in biological processes at different stages after MI.
    PLoS ONE 01/2013; 8(1):e54785. DOI:10.1371/journal.pone.0054785 · 3.23 Impact Factor
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    • "ABBREVIATIONS: AHF anterior heart field ANF atrial natriuretic factor BAF BRG1-associated-factor CHD congenital heart defects DORV double-outlet right ventricle ES cells embryonic stem cells H3K4 histone H3 lysine 4 H3K4me3 trimethylated histone H3 lysine 4 H3K27 histone H3 lysine 27 H3K27me3 trimethylated histone H3 lysine 27 HDAC histone deacetylase HMTase histone methyltransferase Hox genes homeotic genes KDM lysine demethylases LV left ventricle OFT outflow tract PcG Polycomb Group PRC1 Polycomb Repressor Complex 1 PRC2 Polycomb Repressor Complex 2 PR-DUB Polycomb Repressor Deubiquitinase RV right ventricle SHF second heart field TAC transverse aortic constriction TrxG Trithorax Group uH2A mono-ubiquitinated H2A VSD ventricular septal defect the heart's stress response such as hypertrophic growth (Aries et al., 2004; Balza and Misra, 2006; Oka et al., 2006, 2007; Parlakian et al., 2005; Toko et al., 2002; Wang et al., 2005; Zhang et al., 2001). "
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    ABSTRACT: Heart disease is a leading cause of death and disability in developed countries. Heart disease includes a broad range of diseases that affect the development and/or function of the cardiovascular system. Some of these diseases, such as congenital heart defects, are present at birth. Others develop over time and may be influenced by both genetic and environmental factors. Many of the known heart diseases are associated with abnormal expression of genes. Understanding the factors and mechanisms that regulate gene expression in the heart is essential for the detection, treatment, and prevention of heart diseases. Polycomb Group (PcG) and Trithorax Group (TrxG) proteins are special families of chromatin factors that regulate developmental gene expression in many tissues and organs. Accumulating evidence suggests that these proteins are important regulators of development and function of the heart as well. A better understanding of their roles and functional mechanisms will translate into new opportunities for combating heart disease.
    Developmental Dynamics 06/2012; 241(6):1021-33. DOI:10.1002/dvdy.23796 · 2.38 Impact Factor
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