Project description:We are interested in the role of NOTCH1 and Shear Stress in Aortic Valve Endothelium. Primary human aortic valve endothelium was subjected to 4 conditions in vitro. 1) Control siRNA, No shear stress. 2) NOTCH1 siRNA, No shear stress. 3) Control siRNA, 15 dynes/cm2 shear stress. 4) NOTCH1 siRNA, 15 dynes/cm2 shear stress. Triplicates of each condition were pooled for library perp and sequencing
Project description:Aortic valve calcification is the most common form of valvular heart disease, but the mechanisms of calcific aortic valve disease (CAVD) are unknown. NOTCH1 mutations are associated with aortic valve malformations and adult-onset calcification in families with inherited disease. The Notch signaling pathway is critical for multiple cell differentiation processes, but its role in the development of CAVD is not well understood. The aim of this study was to investigate the molecular changes that occur with inhibition of Notch signaling in the aortic valve. Notch signaling pathway members are expressed in adult aortic valve cusps, and examination of diseased human aortic valves revealed decreased expression of NOTCH1 in areas of calcium deposition. To identify downstream mediators of Notch1, we examined gene expression changes that occur with chemical inhibition of Notch signaling in rat aortic valve interstitial cells (AVICs). We found significant downregulation of Sox9 along with several cartilage-specific genes that were direct targets of the transcription factor, Sox9. Loss of expression Sox9 has been published to be associated with aortic valve calcification. Utilizing an in vitro porcine aortic valve calcification model system, inhibition of Notch activity resulted in accelerated calcification while stimulation of Notch signaling attenuated the calcific process. Finally, the addition of Sox9 was able to prevent the calcification of porcine AVICs that occurs with Notch inhibition. In conclusion, loss of Notch signaling contributes to aortic valve calcification via a Sox9-dependent mechanism. 3 samples of aortic valve interstitial cells treated with DAPT were compared with 3 samples of aortic valve interstitial cells treated with DMSO
Project description:Aortic valve calcification is the most common form of valvular heart disease, but the mechanisms of calcific aortic valve disease (CAVD) are unknown. NOTCH1 mutations are associated with aortic valve malformations and adult-onset calcification in families with inherited disease. The Notch signaling pathway is critical for multiple cell differentiation processes, but its role in the development of CAVD is not well understood. The aim of this study was to investigate the molecular changes that occur with inhibition of Notch signaling in the aortic valve. Notch signaling pathway members are expressed in adult aortic valve cusps, and examination of diseased human aortic valves revealed decreased expression of NOTCH1 in areas of calcium deposition. To identify downstream mediators of Notch1, we examined gene expression changes that occur with chemical inhibition of Notch signaling in rat aortic valve interstitial cells (AVICs). We found significant downregulation of Sox9 along with several cartilage-specific genes that were direct targets of the transcription factor, Sox9. Loss of expression Sox9 has been published to be associated with aortic valve calcification. Utilizing an in vitro porcine aortic valve calcification model system, inhibition of Notch activity resulted in accelerated calcification while stimulation of Notch signaling attenuated the calcific process. Finally, the addition of Sox9 was able to prevent the calcification of porcine AVICs that occurs with Notch inhibition. In conclusion, loss of Notch signaling contributes to aortic valve calcification via a Sox9-dependent mechanism.
Project description:Klotho-deficient mice develop aortic valve annulus calcification by 6 weeks of age. Understanding the molecular basis by which aortic valve calcification is initiated will help define potential molecular targets which may be inhibited to reduce or prevent aortic valve calcification. Changes in gene expression related to aortic valve annulus calcification were analyzed by comparing gene expression in the aortic roots from wild type versus klotho-deficient mice.
Project description:Calcific aortic valve disease (CAVD) is an increasingly prevalent condition and endothelial dysfunction is implicated in its etiology. We previously identified nitric oxide (NO) as a calcification inhibitor by its activation of NOTCH1, which is genetically linked to human CAVD. Here, we show that NO rescues calcification by a S-nitrosylation-mediated mechanism in porcine aortic valve interstitial cells (pAVICs) and single cell RNA-seq demonstrated regulation of NOTCH pathway by NO. A unbiased proteomic approach to identify S-nitrosylated proteins in valve cells found enrichment of the ubiquitin proteasome pathway and implicated S-nitrosylation of USP9X in NOTCH regulation during calcification. Furthermore, S-nitrosylated USP9X was shown to deubiquitinate and stabilize MIB1 for NOTCH1 activation. Consistent with this, genetic deletion of Usp9x in mice demonstrated aortic valve disease and human calcified aortic valves displayed reduced S-nitrosylation of USP9X. These results demonstrate a novel mechanism by which S-nitrosylation dependent regulation of ubiquitin-associated pathway prevents CAVD.
Project description:Introduction: Renal failure is associated with aortic valve calcification. Using our rat model of uraemia-induced reversible aortic valve calcification, we assessed the role of apoptosis and survival pathways in aortic valve calcification. We also explored the effects of raloxifene - an estrogen receptor modulator on valvular calcification. Methods: Gene array analysis was performed in aortic valves obtained from 3 groups of rats (n=7 each): calcified valves from rats fed with uremic diet -high-adenine (0.75%), high-phosphate diet (1.5%), valves after calcification resolution following diet cessation (reversibility) and control. In addition, four groups of rats (n=10 each) were used in order to evaluate the effect of raloxifene in aortic valve calcification: three groups as mentioned above and a fourth group fed with the uremic diet which also received daily raloxifene. Evaluation of these groups included imaging, histology and antigen expression analysis. Results: Gene array results showed that the majority of the expressed genes that were altered were from the diet group valves. Most apoptosis-related genes were changed in a pro-apoptotic direction in calcified valves. Apoptosis and decrease in several survival pathways were confirmed in calcified valves. Resolution of aortic valve calcification was accompanied by decreased apoptosis and upregulation of these ant-apoptotic pathways. Imaging and histology demonstrated that raloxifene significantly decreased aortic valve calcification. Conclusion: Downregulation of several survival pathways and apoptosis are involved in the pathogenesis of aortic valve calcification. The beneficial effect of raloxifene in valve calcification is related to apoptosis modulation. This novel observation is important for developing remedies for aortic valve calcification in patients with renal failure. Introduction: Renal failure is associated with aortic valve calcification. Using our rat model of uraemia-induced reversible aortic valve calcification, we assessed the role of apoptosis and survival pathways in aortic valve calcification. We also explored the effects of raloxifene - an estrogen receptor modulator on valvular calcification. Methods: Gene array analysis was performed in aortic valves obtained from 3 groups of rats (n=7 each): calcified valves from rats fed with uremic diet -high-adenine (0.75%), high-phosphate diet (1.5%), valves after calcification resolution following diet cessation (reversibility) and control. In addition, four groups of rats (n=10 each) were used in order to evaluate the effect of raloxifene in aortic valve calcification: three groups as mentioned above and a fourth group fed with the uremic diet which also received daily raloxifene. Evaluation of these groups included imaging, histology and antigen expression analysis. Results: Gene array results showed that the majority of the expressed genes that were altered were from the diet group valves. Most apoptosis-related genes were changed in a pro-apoptotic direction in calcified valves. Apoptosis and decrease in several survival pathways were confirmed in calcified valves. Resolution of aortic valve calcification was accompanied by decreased apoptosis and upregulation of these ant-apoptotic pathways. Imaging and histology demonstrated that raloxifene significantly decreased aortic valve calcification. Conclusion: Downregulation of several survival pathways and apoptosis are involved in the pathogenesis of aortic valve calcification. The beneficial effect of raloxifene in valve calcification is related to apoptosis modulation. This novel observation is important for developing remedies for aortic valve calcification in patients with renal failure.