Genetic analysis of the promoter region of the GATA4 gene in patients with ventricular septal defects
Chinese Academy of Medical Sciences, Peping, Beijing, ChinaTranslational research : the journal of laboratory and clinical medicine 05/2012; 159(5):376-82. DOI: 10.1016/j.trsl.2011.10.012
Ventricular septal defects (VSDs) are the most common type of congenital heart diseases (CHDs). To date, the genetic causes for sporadic VSDs remain largely unknown. GATA transcription factor 4 (GATA4) is a zinc-finger transcription factor that is expressed in developing heart and adult cardiomyocytes. Mutations in the coding region of the GATA4 gene have been identified in CHD patients, including VSD. As the GATA4 factor is a dosage-sensitive regulator, we hypothesized that the promoter region variants of the GATA4 gene may be genetic causes of VSD. In this study, we analyzed the promoter region of the GATA4 gene by bidirectional sequencing in 172 VSD patients and 171 healthy controls. The results showed that 5 heterozygous sequence variants (NG_008177:g.4071T>C, NG_008177:g.4148C>A, NG_008177:g.4566C>T, NG_008177:g.4653G>T, and NG_008177:g.4690G>deletion) within the promoter region of the GATA gene were identified in 5 VSD patients, but in none of controls. One heterozygous sequence variant (g.4762C>A) was found only in one control, which may have no functional significance. A functional analysis revealed that the transcriptional activity of variant NG_008177:g.4566C>T was reduced significantly, whereas the transcriptional activities of the variants (NG_008177:g.4071T>C, NG_008177:g.4148C>A, NG_008177:g.4653G>T, and NG_008177:g.4690G>deletion) were increased significantly compared with the wild-type GATA4 gene promoter. As GATA4 is a dosage-sensitive regulator during development, our data suggest that these sequence variants within the promoter region of the GATA4 gene may contribute to the VSD etiology by altering its gene expression. Additional studies in experimental animals will deepen our understanding of the genetic basis of VSD and shed light on designing novel molecular therapies for adult VSD patients carrying these variants.
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ABSTRACT: Congenital heart disease (CHD) is the most common birth defects in humans. The genetic causes for CHD remain largely unknown. T-box transcription factor 1 (TBX1), a dosage-sensitive regulator, plays a critical role in the heart development. Mutations in the coding regions of TBX1 gene have been associated to 22q11 deletion syndrome with cardiac defects and isolated CHD cases, including ventricular septal defect (VSD). To date, TBX1 gene promoter region has not been analyzed and reported in CHD patients. We hypothesized that the sequence variants within TBX1 gene promoter region may change TBX1 levels and mediate CHD development. In this study, the promoter regions of TBX1 gene were genetically and functionally analyzed in 280 VSD patients and 267 healthy controls. Two novel heterozygous variants, g.4353C>T and g.4510A>C, were found in two VSD patients, but in none of controls. The single-nucleotide polymorphism-rs41260844, g.4199T>C, was found more frequent in VSD patients than controls (P < 0.01). Functional analyses revealed that these sequence variants significantly enhanced transcriptional activities of TBX1 gene promoter. Therefore, the sequence variants within TBX1 gene promoter may contribute to the VSD etiology by altering the expression levels of TBX1 gene. Pharmaceutical or genetic manipulation of TBX1 gene expression may provide a novel personalized therapy to prevent and treat late cardiac complications for the adult CHD patients carrying these variants.
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ABSTRACT: Mutations in cardiac transcription factor genes, such as GATA-4, NKX2-5 and TBX5 genes, have been associated to the patients with familial and isolated congenital heart disease (CHD). Little work has been done on the epigenetic causes for CHD. Sirtuis are highly conserved NAD-dependent class III deacetylases. In mammals, there are seven members of surtuin family, SIRT1–SIRT7. SIRT1, the closest to yeast Sir2, has deacetylase activity and ADP-ribosyltransferase activity. SIRT1 has been involved in many cellular processes and implicated in human diseases, such as obesity, type 2 diabetes, cancer and neurodegenerative diseases. We hypothesized that altered levels of SIRT1 gene expression, rather than mutations in SIRT1 gene, may contribute to the human diseases. In this study, we genetically analyze the SIRT1 gene promoter in patients with ventricular septal defects (VSD) (n = 333) and ethic-matched healthy controls (n = 348). In all, six single-nucleotide polymorphisms (SNPs) and twelve heterozygous sequence variants were identified. Four novel heterozygous variants, g.69643693A > G, g.69643963A > T, g.69643971G > A and g.69644366Ins, were found in six VSD patients, but in none of controls. Six SNPs and variants, g.69643707A > C (rs35706870), g.69643874C > A, g.69644209C > G, g.69644213G > A, g.69644268T > A and g.69644441G > A, were only identified in controls. The other SNPs and variants were found in both groups with similar frequencies. Therefore, the variants within the SIRT1 gene promoter identified in VSD patients may alter the transcriptional activities of SIRT1 gene promoter. Changed SIRT1 protein levels may contribute to the VSD etiology by affecting the activities of its substrates.
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