Gene expression in aortic roots of wild type versus klotho-deficient mice at 6 weeks of age
Ontology highlight
ABSTRACT: 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:Klotho knock-out mice are an important model for CKD-induced calcification. In CKD, serum magnesium (Mg2+) inversely correlates with vascular calcification. This study aims to determine the effects of Mg2+ on aortic calcification in Klotho knock-out mice. Klotho knock-out mice were treated with either a minimal or a high Mg2+ diet from birth. After eight weeks, serum biochemistry was studied and organs were harvested. Protective effects of Mg2+ were characterized by RNA-sequencing of aortic tissue. Micro-CT analysis was performed to study bone integrity. High Mg2+ diet prevented vascular calcification and reduced aortic gene expression of Runx2 and matrix Gla protein, demonstrating the protective effect on pro-osteogenic signaling. Differential expression of inflammation and extracellular matrix remodeling genes accompany the beneficial effects of Mg2+ on calcification. High dietary Mg2+ did not affect serum parathyroid hormone, vitamin D3 and calcium. High Mg2+ intake prevented calcification despite increasing fibroblast growth factor-23 and phosphate concentration in knock-out mice. In addition, mice on the high Mg2+ diet had a 20% reduced femoral bone mineral density and increased osteoid formation indicating osteomalacia, while osteoclast activity was decreased in Klotho knock-out mice. In Saos-2 osteoblasts, Mg2+ supplementation reduced mineralization independent of osteoblastic matrix production, alkaline phosphatase activity and maturation markers alpha-1 type-I collagen and sclerostin. In conclusion, high dietary Mg2+ prevents calcification in Klotho knock-out mice. These effects are potentially mediated by reduction of inflammatory and extracellular matrix remodeling pathways in the aorta. Mg2+ treatment is promising to prevent vascular calcification, but the risk for osteomalacia should be considered.
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:Calcific aortic valve disease is the most common form of valvular heart disease in the Western World. Milder degrees of aortic valve calcification is called aortic sclerosis and severe calcification with impaired leaflet motion is called aortic stenosis. We used microarrays to detail the global programme of gene expression underlying cdevelopment of calcified aortic valve disease in humans.
Project description:Calcification of the aortic valve leads to increased leaflet stiffness resulting in development of calcific aortic valve disease (CAVD); however, the underlying molecular and cellular mechanisms of calcification are poorly understood. Here, we investigated gene expressions in relation to valvular calcification and promotion of CAVD progression.
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.
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:Although calcific aortic valve stenosis (CAVS) is the most prevalent valvular heart disease, the molecular mechanisms underlying aortic valve calcification remain unknown. Here, we found a significant elevation in stanniocalcin-1 (STC1) expression in the valve interstitial cells (VICs) of calcific aortic valves by combined analysis of our comprehensive gene expression data and microarray datasets reported previously. Immunohistochemical staining showed that STC1 was located around the calcific area in the aortic valves of patients with CAVS. In vitro experiments using inhibitors and siRNA targeting osteoblast differentiation signaling revealed that activation of the Akt/STC1 axis was essential for runt-related transcription factor 2 (RUNX2) induction in the VICs. RNA sequencing and bioinformatics analysis of STC1-knocked down VICs in osteoblast differentiation medium resulted in silencing of the induction of osteoarthritis signaling-related genes, including RUNX2 and COL10A1. STC1 depletion in the murine CAVS model improved aortic valve dysfunction with high peak velocity and valve thickening and suppressed the appearance of osteochondrocytes. STC1-deficient mice also exhibited complete calcification abolishment, although partial valve thickening by aortic valve injury was observed. Our findings suggest that STC1 may be a critical factor in determining valve calcification and a novel target for preventing the transition to severe CAVS with calcification. We analyzed the gene expression profiles of the valve interstitial cells (VICs) isolated from noncalcific and calcific areas in calcific aortic valve stenosis (CAVS) donors using a gene microarray.
Project description:Aortic valve calcification is a significant and serious clinical problem for which there are no effective medical treatments. Individuals born with bicuspid aortic valves, 1-2% of the population, are at the highest risk of developing aortic valve calcification. Aortic valve calcification involves increased levels of calcification and inflammatory genes. Bicuspid aortic valve leaflets experience increased strain. The molecular mechanisms involved in the pathogenesis of calcification of BAVs are not well understood, especially the molecular response to mechanical stretch. HOTAIR is a long non-coding RNA (lncRNA) that has been implicated with cancer but has not been studied in cardiac disease. We have found that HOTAIR levels are decreased in BAVs and in human aortic interstitial cells (AVICs) exposed to cyclic stretch. Reducing HOTAIR levels via siRNA in AVICs results in increased expression of calcification genes.
Project description:Aortic valve calcifications are often associated with calcium deposition and tissue mineralization, resulting in stiffness and dysfunction. To better understand the diversity of molecular and cellular processes for calcification in valve structures, we isolated human aortic valve interstitial cells (AVICs) and exposed them to calcification stimulation. RNA-seq revealed that in response to calcified stimuli, AVIC activates a robust ossification program, although the signaling pathways, cellular processes, and osteogenesis-related markers involved are diverse. In conclusion, this study provides a wealth of information suggesting that the pathogenesis of aortic valve calcification may be much more than previously understood.
Project description:The role of long noncoding RNAs (lncRNAs) in calcific aortic valve disease (CAVD) remains largely elusive. This study aims to report a novel therapeutic lncRNA, SNHG3, and elucidate its role in CAVD. Based on high-throughput transcriptomic sequencing of human aortic valves, SNHG3 is among the most highly expressed lncRNAs in CAVD. Furthermore, SNHG3 upregulation is verified in human calcified aortic valves, osteoblastic human aortic valve interstitial cells (hVICs), and aortic valve tissues in CAVD mice. Moreover, knockdown of SNHG3 with antisense oligonucleotide markedly ameliorates aortic valve calcification in high cholesterol diet-treated ApoE-/- mice, as evidenced by reduced calcium deposition in the aortic valve leaflets, improved echocardiographic parameters, and decreased osteogenic differentiation markers (RUNX2, osteopontin, and osteocalcin) in aortic valves. Consistent with these in vivo findings, SNHG3 overexpression aggravates the calcification of hVICs, while knockdown of SNHG3 alleviates the process of differential calcification. Transcriptomics sequencing, gene set enrichment analyses, RNA-pull down, RNA immunoprecipitation and chromatin immunoprecipitation-qPCR show that SNHG3 physically interacts with polycomb repressive complex 2 to suppress the H3K27 tri-methylation BMP2 locus, which in turn activates BMP2 expression and signaling pathways. Taken together, SNHG3 promotes aortic valve calcification by upregulating BMP2, which might be a novel therapeutic target in human CAVD.