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Gata4 is required for maintenance of postnatal cardiac function and protection from pressure overload-induced heart failure.

ABSTRACT: An important event in the pathogenesis of heart failure is the development of pathological cardiac hypertrophy. In cultured cardiomyocytes, the transcription factor Gata4 is required for agonist-induced hypertrophy. We hypothesized that, in the intact organism, Gata4 is an important regulator of postnatal heart function and of the hypertrophic response of the heart to pathological stress. To test this hypothesis, we studied mice heterozygous for deletion of the second exon of Gata4 (G4D). At baseline, G4D mice had mild systolic and diastolic dysfunction associated with reduced heart weight and decreased cardiomyocyte number. After transverse aortic constriction (TAC), G4D mice developed overt heart failure and eccentric cardiac hypertrophy, associated with significantly increased fibrosis and cardiomyocyte apoptosis. Inhibition of apoptosis by overexpression of the insulin-like growth factor 1 receptor prevented TAC-induced heart failure in G4D mice. Unlike WT-TAC controls, G4D-TAC cardiomyocytes hypertrophied by increasing in length more than width. Gene expression profiling revealed up-regulation of genes associated with apoptosis and fibrosis, including members of the TGF-beta pathway. Our data demonstrate that Gata4 is essential for cardiac function in the postnatal heart. After pressure overload, Gata4 regulates the pattern of cardiomyocyte hypertrophy and protects the heart from load-induced failure.

SUBMITTER: Bisping E

PROVIDER: S-EPMC1636702 | biostudies-literature | 2006 Sep

REPOSITORIES: biostudies-literature

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Gata4 is required for maintenance of postnatal cardiac function and protection from pressure overload-induced heart failure.

Bisping Egbert E Ikeda Sadakatsu S Kong Sek Won SW Tarnavski Oleg O Bodyak Natalya N McMullen Julie R JR Rajagopal Satish S Son Jennifer K JK Ma Qing Q Springer Zhangli Z Kang Peter M PM Izumo Seigo S Pu William T WT

Proceedings of the National Academy of Sciences of the United States of America 20060918 39

An important event in the pathogenesis of heart failure is the development of pathological cardiac hypertrophy. In cultured cardiomyocytes, the transcription factor Gata4 is required for agonist-induced hypertrophy. We hypothesized that, in the intact organism, Gata4 is an important regulator of postnatal heart function and of the hypertrophic response of the heart to pathological stress. To test this hypothesis, we studied mice heterozygous for deletion of the second exon of Gata4 (G4D). At bas ...[more]

PMID: 16983087

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Project description:AimsThe role of uncoupling protein 2 (UCP2) in cardiac adaptation to pressure overload remains unclear. In a classical model of left ventricular pressure overload genetic deletion of UCP2 (UCP2-/-) protected against cardiac hypertrophy and failure. However, in UCP2-/- mice increased proliferation of pulmonary arterial smooth muscle cells induces mild pulmonary hypertension, right ventricular (RV) hypertrophy, and reduced cardiac output. This suggests a different role for UCP2 in RV and left ventricular adaptation to pressure overload. To clarify this situation in more detail UCP2-/- and wild-type mice were exposed to pulmonary arterial banding (PAB).Methods and resultsMice were analysed (haemodynamics, morphometry, and echocardiography) 3 weeks after PAB or sham surgery. Myocytes and non-myocytes were isolated and analysed separately. Cell shortening of myocytes and fura-2 loading of cardiomyocytes were used to characterize their function. Brd assay was performed to study fibroblast proliferation. Isolated mitochondria were analysed to investigate the role of UCP2 for reactive oxygen species (ROS) production. UCP2 mRNA was 2.7-fold stronger expressed in RV myocytes than in left ventricular myocytes and stronger expressed in non-myocytes compared with myocytes. Three weeks after PAB, cardiac output was reduced in wild type but preserved in UCP2-/- mice. UCP2-/- had increased RV wall thickness, but lower RV internal diameters and displayed a significant stronger fibrosis. Cardiac fibroblasts from UCP2-/- had reduced proliferation rates but higher collagen-1 expression. Myocytes isolated from mice after PAB banding showed preserved function that was further improved by UCP2-/-. Mitochondrial ROS production and respiration was similar between UCP2-/- or wild-type hearts.ConclusionDespite a mild pulmonary hypertension in UCP2-/- mice, hearts from these mice are well preserved against additional pressure overload (severe pulmonary hypertension). This-at least in part-depends on different behaviour of non-myocytes (fibroblasts).

Project description:AimsLymphatics are essential for cardiac health, and insufficient lymphatic expansion (lymphangiogenesis) contributes to development of heart failure (HF) after myocardial infarction. However, the regulation and impact of lymphangiogenesis in non-ischaemic cardiomyopathy following pressure-overload remains to be determined. Here, we investigated cardiac lymphangiogenesis following transversal aortic constriction (TAC) in C57Bl/6 and Balb/c mice, and in end-stage HF patients.Methods and resultsCardiac function was evaluated by echocardiography, and cardiac hypertrophy, lymphatics, inflammation, oedema, and fibrosis by immunohistochemistry, flow cytometry, microgravimetry, and gene expression analysis. Treatment with neutralizing anti-VEGFR3 antibodies was applied to inhibit cardiac lymphangiogenesis in mice. We found that VEGFR3-signalling was essential to prevent cardiac lymphatic rarefaction after TAC in C57Bl/6 mice. While anti-VEGFR3-induced lymphatic rarefaction did not significantly aggravate myocardial oedema post-TAC, cardiac immune cell levels were increased, notably myeloid cells at 3 weeks and T lymphocytes at 8 weeks. Moreover, whereas inhibition of lymphangiogenesis did not aggravate interstitial fibrosis, it increased perivascular fibrosis and accelerated development of left ventricular (LV) dilation and dysfunction. In clinical HF samples, cardiac lymphatic density tended to increase, although lymphatic sizes decreased, notably in patients with dilated cardiomyopathy. Similarly, comparing C57Bl/6 and Balb/c mice, lymphatic remodelling post-TAC was linked to LV dilation rather than to hypertrophy. The striking lymphangiogenesis in Balb/c was associated with reduced cardiac levels of macrophages, B cells, and perivascular fibrosis at 8 weeks post-TAC, as compared with C57Bl/6 mice that displayed weak lymphangiogenesis. Surprisingly, however, it did not suffice to resolve myocardial oedema, nor prevent HF development.ConclusionsWe demonstrate for the first time that endogenous lymphangiogenesis limits TAC-induced cardiac inflammation and perivascular fibrosis, delaying HF development in C57Bl/6 but not in Balb/c mice. While the functional impact of lymphatic remodelling remains to be determined in HF patients, our findings suggest that under settings of pressure-overload poor cardiac lymphangiogenesis may accelerate HF development.

Dataset Information

Gata4 is required for maintenance of postnatal cardiac function and protection from pressure overload-induced heart failure.

Publications

Gata4 is required for maintenance of postnatal cardiac function and protection from pressure overload-induced heart failure.

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