Dataset Information

Transcriptional regulation of the murine Connexin40 promoter by cardiac factors Nkx2-5, GATA4 and Tbx5.

ABSTRACT: Connexin40 (Cx40) is a gap junction protein expressed specifically in developing and mature atrial myocytes and cells of the conduction system. In this report, we identify cis-acting elements within the mouse Cx40 promoter and unravel part of the complex pathways involved in the cardiac expression of this gene.To identify the factors involved in the cardiac expression of Cx40, we used transient transfections in mammalian cells coupled with electrophoretic mobility shift assays (EMSA) and RT-PCR.Within the promoter region, we identified the minimal elements required for transcriptional activity within 150 base pairs (bp) upstream of the transcriptional start site. Several putative regulatory sites for transcription factors were predicted within this region by computer analysis, and we demonstrated that the nuclear factors Sp1, Nkx2-5, GATA4 and Tbx5 could interact specifically with elements present in the minimal promoter region of the Cx40. Furthermore, co-transfection experiments showed the ability of Nkx2-5 and GATA4 to transactivate the minimal Cx40 promoter while Tbx5 repressed Nkx2-5/GATA4-mediated activation. Mutagenesis of the Nkx2-5 core site in the Cx40 promoter led to significantly decreased activity in rat smooth muscle cell line A7r5. Consistent with this, mouse embryos lacking Nkx2-5 showed a marked decrease in Cx40 expression.In this work, we cloned the promoter region of the Cx40 and demonstrated that the core promoter was modulated by cardiac transcriptional factors Nkx2-5, Tbx5 and GATA4 acting together with ubiquitous Sp1.

SUBMITTER: Linhares VL

PROVIDER: S-EPMC3252638 | biostudies-literature | 2004 Dec

REPOSITORIES: biostudies-literature

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Transcriptional regulation of the murine Connexin40 promoter by cardiac factors Nkx2-5, GATA4 and Tbx5.

Linhares Vania L F VL Almeida Norma A S NA Menezes Diego C DC Elliott David A DA Lai Donna D Beyer Eric C EC Campos de Carvalho Antonio C AC Costa Mauro W MW

Cardiovascular research 20041201 3

<h4>Objective</h4>Connexin40 (Cx40) is a gap junction protein expressed specifically in developing and mature atrial myocytes and cells of the conduction system. In this report, we identify cis-acting elements within the mouse Cx40 promoter and unravel part of the complex pathways involved in the cardiac expression of this gene.<h4>Methods</h4>To identify the factors involved in the cardiac expression of Cx40, we used transient transfections in mammalian cells coupled with electrophoretic mobili ...[more]

PMID: 15537493

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Project description:Cardiac transcription factors are master regulators during heart development. Some were shown to transdifferentiate tail tip and cardiac fibroblasts into cardiomyocytes. However, recent studies have showed that controversies exist. Potential difference in tail tip and cardiac fibroblast isolation may possibly confound the observations. Moreover, due to the use of a cardiac reporter (Myh6) selection strategy for induced cardiomyocyte enrichment, and the lack of tracking signals for each transcription factors, individual roles of each transcription factors in activating cardiac gene expression in mammalian non-myoblastic cells have never been elucidated. Answers to these questions are an important step toward cardiomyocyte regeneration. Because mouse 10T1/2 fibroblasts are non-myoblastic in nature and can be induced to express genes of all three types of muscle cells, they are an ideal model for the analysis of cardiac and non-cardiac gene activation after induction. We constructed bi-cistronic lentiviral vectors, capable of expressing cardiac transcription factors along with different fluorescent tracking signals. By infecting 10T1/2 fibroblasts with Nkx2-5, Tbx5, Gata4 or Myocd cardiac transcription factor lentivirus alone or different combinations, we found that only Tbx5+Myocd and Tbx5+Gata4+Myocd combinations induced Myh6 and Tnnt2 cardiac marker protein expression. Microarray-based gene ontology analysis revealed that Tbx5 alone activated genes involved in the Wnt receptor signaling pathway and inhibited genes involved in a number of cardiac-related processes. Myocd alone activated genes involved in a number of cardiac-related processes and inhibited genes involved in the Wnt receptor signaling pathway and non-cardiac processes. Gata4 alone inhibited genes involved in non-cardiac processes. Tbx5+Gata4+Myocd was the most effective activator of genes associated with cardiac-related processes. Unlike Tbx5, Gata4, Myocd alone or Tbx5+Myocd, Tbx5+Gata4+Myocd activated the fewest genes associated with non-cardiac processes. Conclusively, Tbx5, Gata4 and Myocd play different roles in cardiac gene activation in mammalian non-myoblastic cells. Tbx5+Gata4+Myocd activates the most cardiac and the least non-cardiac gene expression.

Project description:BackgroundSeveral genes encoding transcription factors are known to be the primary cause of congenital heart disease. NKX2-5 and GATA4 were the first congenital heart disease-causing genes identified by linkage analysis. This study designed to study the association of five single-nucleotide variants of NKX2-5, GATA4, and TBX5 genes with sporadic nonsyndromic cases of a congenital cardiac septal defect in Egyptian children.MethodsVenous blood samples from 150 congenital heart disease children (including a ventricular septal defect, atrial septal defect, tetralogy of Fallot, and patent ductus arteriosus) and 90 apparently healthy of matched age and sex were studied by polymerase chain reaction followed by direct sequencing in order to study two single-nucleotide variants of NKX2-5 (rs2277923, rs28936670), two single-nucleotide variants of GATA4 (rs368418329, rs56166237) and one single-nucleotide variant TBX5 (rs6489957). The distribution of genotype and allele frequency in the congenital heart diseases (CHD) group and control group were analyzed.ResultsWe found different genotype frequencies of the two variants of NKX2-5, as CT genotype of rs2277923 was present in 58% and 36% in cases and control respectively, and TT genotype present in 6% of the cases. Also regarding missense variant rs28936670, heterozygous AG presented in 82% of the cases. Also, we observed a five prime UTR variant rs368418329, GT (42% of the cases) and GG (46% of the cases) genotypes showed the most frequent presentation in cases. While regarding a synonymous variant rs56166237, GT and GG were the most presented in cases (41.4%, 56% respectively) in contrast to control group (20%, 1.7% respectively). Also, a synonymous variant in TBX5, the distribution of genotype frequency was significantly different between the CHD group and control group. CT genotype of TBX5 -rs6489957 was found in 12 ASD, 24 VSD, six PDA, three aortic coarctation and nine fallot that represent 42% of the cases.ConclusionsSignificantly higher frequency of different allelle of five variants was observed in cases when compared to the control group, with significant risky effect for the development of septal defect. In addition to two polymorphisms of NKX2-5 (rs2277923, rs28936670) variant in the cardiac septal defect, two variants in GATA4 (rs368418329, rs56166237) and one variant in TBX5 (rs6489957) seem to have a role in the pathogenesis of congenital heart disease.

Dataset Information

Transcriptional regulation of the murine Connexin40 promoter by cardiac factors Nkx2-5, GATA4 and Tbx5.

Publications

Transcriptional regulation of the murine Connexin40 promoter by cardiac factors Nkx2-5, GATA4 and Tbx5.

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