Anti-correlation between longevity gene SirT1 and Notch signaling in ascending aorta biopsies from patients with bicuspid aortic valve disease

About 1–2% of the population present with bicuspid aortic valves (BAV), a defect of the aortic valve resulting in the formation of two leaflets instead of three. This disease leads to an abnormal aorta, altered in strength and size, which in turn is a high risk factor for potentially lethal events such as aortic dissection and aneurysm formation. BAV is inheritable, with a demonstrated association with Notch1, a member of the Notch intercellular signaling pathway that is implicated in various cardiovascular disorders. Sirtuin 1 (SirT1) is a protein deacetylase of the sirtuin family, whose activation appears beneficial for cardiac diseases. A recent study has shown that SirT1 can limit Notch signaling in model systems of vascular growth. If a concomitant dysregulation in Notch and SirT1 signaling pathways can cause the phenotypic form of human BAV is unknown. To address this issue, we analyzed human ascending aorta biopsies from BAV and control patients obtained at the time of cardiac surgery. RNA and proteins were extracted from formalin-fixed and paraffin-embedded specimens, and quantitative real-time PCR and immunoblotting were used to determine the expression of sirtuins and members of the Notch family of proteins. We found a significant increase in SirT1 expression that correlates with a decreased expression of the Notch signaling effectors detected. We put forward the idea that an altered interaction between SirT1 and Notch signaling could participate in BAV pathogenesis and that these molecules could be used as potential clinical markers.