GATA5 and endothelial nitric oxide synthase expression in the ascending aorta is related to aortic size and valve morphology.

BACKGROUND: The pathogenesis of aortic dilatation in patients with congenital aortic valve anomalies is poorly understood. Recent studies suggest that alterations of gene expression may be related to ascending aortic aneurysm formation in these patients. Knockout of endothelial nitric oxide synthase (eNOS) and GATA5 is associated with bicuspid aortic valves in mice. To study the role of eNOS and GATA5 in human congenital aortic valve disease and aortic dilatation, we investigated their gene expression in aortic tissue from patients with unicuspid, bicuspid, and tricuspid aortic valves. METHODS: Samples from 84 patients (33 tricuspid, 32 bicuspid, and 19 unicuspid) were harvested intraoperatively from the ascending aorta. GATA5 and eNOS expression was determined by real-time polymerase chain reaction. RESULTS: GATA5 and eNOS expression in the aortic wall from patients with unicuspid aortic valves (GATA5: mean [M], 2.14; standard deviation [SD], 1.72; eNOS: M, 3.40; SD, 3.83) was significantly higher than in tricuspid aortic valves (GATA5: M, 1.12; SD, 0.80; eNOS: M, 1.00; SD, 0.74; each p < 0.05). Patients with bicuspid aortic valves (GATA5: M, 1.29, SD, 1.33; eNOS: M, 1.66; SD, 1.31) had a significantly higher eNOS expression than patients with tricuspid aortic valves (p < 0.05). The expression levels of eNOS and GATA5 correlated positively with each other and negatively with the ascending aortic diameter. CONCLUSIONS: Our data suggest that GATA5, possibly through upregulation of eNOS, plays a role in the development of aortic dilatation in patients with unicuspid and bicuspid aortic valves. The differential gene expression in patients with unicuspid compared with bicuspid aortic valves suggests that the pathogenesis of both aortic valve anomalies may be different.

Identification of reference genes for quantitative RT-PCR in ascending aortic aneurysms.

Hypertension and congenital aortic valve malformations are frequent causes of ascending aortic aneurysms. The molecular mechanisms of aneurysm formation under these circumstances are not well understood. Reference genes for gene activity studies in aortic tissue that are not influenced by aortic valve morphology and its hemodynamic consequences, aortic dilatation, hypertension, or antihypertensive medication are not available so far. This study determines genes in ascending aortic tissue that are independent of these parameters. Tissue specimens from dilated and undilated ascending aortas were obtained from 60 patients (age ≤70 years) with different morphologies of the aortic valve (tricuspid undilated n = 24, dilated n = 11; bicuspid undilated n = 6, dilated n = 15; unicuspid dilated n = 4). Of the studied individuals, 36 had hypertension, and 31 received ACE inhibitors or AT1 receptor antagonists. The specimens were obtained intraoperatively from the wall of the ascending aorta. We analyzed the expression levels of 32 candidate reference genes by quantitative RT-PCR (RT-qPCR). Differential expression levels were assessed by parametric statistics. The expression analysis of these 32 genes by RT-qPCR showed that EIF2B1, ELF1, and PPIA remained constant in their expression levels in the different specimen groups, thus being insensitive to aortic valve morphology, aortic dilatation, hypertension, and medication with ACE inhibitors or AT1 receptor antagonists. Unlike many other commonly used reference genes, the genes EIF2B1, ELF1, and PPIA are neither confounded by aortic comorbidities nor by antihypertensive medication and therefore are most suitable for gene expression analysis of ascending aortic tissue.