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Identification of functional mutations in GATA4 in patients with congenital heart disease.

ABSTRACT: Congenital heart disease (CHD) is one of the most prevalent developmental anomalies and the leading cause of noninfectious morbidity and mortality in newborns. Despite its prevalence and clinical significance, the etiology of CHD remains largely unknown. GATA4 is a highly conserved transcription factor that regulates a variety of physiological processes and has been extensively studied, particularly on its role in heart development. With the combination of TBX5 and MEF2C, GATA4 can reprogram postnatal fibroblasts into functional cardiomyocytes directly. In the past decade, a variety of GATA4 mutations were identified and these findings originally came from familial CHD pedigree studies. Given that familial and sporadic CHD cases allegedly share a basic genetic basis, we explore the GATA4 mutations in different types of CHD. In this study, via direct sequencing of the GATA4 coding region and exon-intron boundaries in 384 sporadic Chinese CHD patients, we identified 12 heterozygous non-synonymous mutations, among which 8 mutations were only found in CHD patients when compared with 957 controls. Six of these non-synonymous mutations have not been previously reported. Subsequent functional analyses revealed that the transcriptional activity, subcellular localization and DNA binding affinity of some mutant GATA4 proteins were significantly altered. Our results expand the spectrum of GATA4 mutations linked to cardiac defects. Together with the newly reported mutations, approximately 110 non-synonymous mutations have currently been identified in GATA4. Our future analysis will explore why the evolutionarily conserved GATA4 appears to be hypermutable.

SUBMITTER: Wang E

PROVIDER: S-EPMC3633926 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Defects of atrial and ventricular septation are the most frequent form of congenital heart disease, accounting for almost 50% of all cases. We previously reported that a heterozygous G296S missense mutation of GATA4 caused atrial and ventricular septal defects and pulmonary valve stenosis in humans. GATA4 encodes a cardiac transcription factor, and when deleted in mice it results in cardiac bifida and lethality by embryonic day (E)9.5. In vitro, the mutant GATA4 protein has a reduced DNA binding affinity and transcriptional activity and abolishes a physical interaction with TBX5, a transcription factor critical for normal heart formation. To characterize the mutation in vivo, we generated mice harboring the same mutation, Gata4 G295S. Mice homozygous for the Gata4 G295S mutant allele have normal ventral body patterning and heart looping, but have a thin ventricular myocardium, single ventricular chamber, and lethality by E11.5. While heterozygous Gata4 G295S mutant mice are viable, a subset of these mice have semilunar valve stenosis and small defects of the atrial septum. Gene expression studies of homozygous mutant mice suggest the G295S protein can sufficiently activate downstream targets of Gata4 in the endoderm but not in the developing heart. Cardiomyocyte proliferation deficits and decreased cardiac expression of CCND2, a member of the cyclin family and a direct target of Gata4, were found in embryos both homozygous and heterozygous for the Gata4 G295S allele. To further define functions of the Gata4 G295S mutation in vivo, compound mutant mice were generated in which specific cell lineages harbored both the Gata4 G295S mutant and Gata4 null alleles. Examination of these mice demonstrated that the Gata4 G295S protein has functional deficits in early myocardial development. In summary, the Gata4 G295S mutation functions as a hypomorph in vivo and leads to defects in cardiomyocyte proliferation during embryogenesis, which may contribute to the development of congenital heart defects in humans.

Project description:BACKGROUND: The 3'-untranslated region (3'-UTR) of mRNA contains regulatory elements that are essential for the appropriate expression of many genes. These regulatory elements are involved in the control of nuclear transport, polyadenylation status, subcellular targetting as well as rates of translation and degradation of mRNA. Indeed, 3'-UTR mutations have been associated with disease, but frequently this region is not analyzed. To gain insights into congenital heart disease (CHD), we have been analyzing cardiac-specific transcription factor genes, including GATA4, which encodes a zinc finger transcription factor. Germline mutations in the coding region of GATA4 have been associated with septation defects of the human heart, but mutations are rather rare. Previously, we identified 19 somatically-derived zinc finger mutations in diseased tissues of malformed hearts. We now continued our search in the 609 bp 3'-UTR region of GATA4 to explore further molecular avenues leading to CHD. METHODS: By direct sequencing, we analyzed the 3'-UTR of GATA4 in DNA isolated from 68 formalin-fixed explanted hearts with complex cardiac malformations encompassing ventricular, atrial, and atrioventricular septal defects. We also analyzed blood samples of 12 patients with CHD and 100 unrelated healthy individuals. RESULTS: We identified germline and somatic mutations in the 3'-UTR of GATA4. In the malformed hearts, we found nine frequently occurring sequence alterations and six dbSNPs in the 3'-UTR region of GATA4. Seven of these mutations are predicted to affect RNA folding. We also found further five nonsynonymous mutations in exons 6 and 7 of GATA4. Except for the dbSNPs, analysis of tissue distal to the septation defect failed to detect sequence variations in the same donor, thus suggesting somatic origin and mosaicism of mutations. In a family, we observed c.+119A > T in the 3'-UTR associated with ASD type II. CONCLUSION: Our results suggest that somatic GATA4 mutations in the 3'-UTR may provide an additional molecular rationale for CHD.

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Identification of functional mutations in GATA4 in patients with congenital heart disease.

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