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Updated: Jan 7, 2026
Isolation of Mouse Interstitial Valve Cells to Study the Calcification of the Aortic Valve In Vitro
Published on: May 10, 2021
VAPB Promotes Osteogenic Differentiation in Aortic Valve Interstitial Cells via Activation of the SMAD Signaling
Xiaolin Liu1,2, Kai Xing1,2, Qiang Zheng1
1Department of Cardiovascular Surgery, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, 250021, Shandong, China.
Insights
Vesicle-associated membrane protein-associated protein B (VAPB) promotes aortic valve calcification by activating the SMAD signaling pathway in valve interstitial cells. This finding offers new insights into calcific aortic valve disease mechanisms.
Area of Science:
- Cardiovascular Biology
- Molecular Cardiology
- Biochemistry
Background:
- Vesicle-associated membrane protein-associated protein B (VAPB) is implicated in cardiovascular diseases.
- The specific role of VAPB in calcific aortic valve disease (CAVD) remains unclear.
- Understanding VAPB's function in CAVD is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the role of VAPB in the pathogenesis of CAVD.
- To elucidate the molecular mechanisms by which VAPB influences aortic valve calcification.
- To explore the relationship between VAPB and the SMAD signaling pathway in valve interstitial cells.
Main Methods:
- Immunohistochemical analysis of VAPB expression in human CAVD tissues.
- In vitro studies using valve interstitial cells (VICs) to assess osteogenic differentiation and calcification.
- Gene set enrichment analysis (GSEA) to identify VAPB-regulated pathways.
- Western blotting and immunoprecipitation to analyze SMAD signaling and protein interactions.
Main Results:
- VAPB expression is significantly upregulated in CAVD aortic valves.
- VAPB overexpression enhances VIC osteogenic differentiation and calcification.
- VAPB activates the SMAD signaling pathway, evidenced by increased p-SMAD1/5/9.
- VAPB directly interacts with SMAD1/5/9, mediating its pro-calcification effects.
Conclusions:
- VAPB promotes osteogenic differentiation and calcification in VICs.
- VAPB's pro-calcific effects are mediated through the activation of the SMAD signaling pathway.
- VAPB represents a potential therapeutic target for CAVD.
Objective:
Prior studies have associated vesicle-associated membrane protein- associated protein B (VAPB) with various cardiovascular diseases, yet its role in calcific Aortic Valve Disease (CAVD) is not fully understood. This study aims to elucidate the relationship between VAPB and aortic valve calcification at both tissue and cellular molecular levels, exploring potential regulatory mechanisms.
Methods:
The expression levels of VAPB in calcified valve tissues were assessed using immunohistochemical analysis. Osteogenic differentiation and calcification levels of valve interstitial cells (VICs) were evaluated by alizarin red staining, calcium content quantification, and the detection of the osteogenic markers. Gene set enrichment analysis (GSEA) was used to identify downstream pathways regulated by VAPB, immunoblotting was used to detect the expression of key molecules of SMAD signaling, and immunoprecipitation was performed to detect interactions between VAPB and SMAD1/5/9.
Results:
VAPB expression was significantly upregulated in the aortic valve leaflets of patients with CAVD. VICs with VAPB overexpression exhibited a significant increase in calcium content (p < 0.001) and upregulation of osteogenic markers RUNX2, osteocalcin, and osteopontin (p <0. 01). Conversely, VAPB knockdown reduced osteogenic differentiation in VICs. Furthermore, VAPB overexpression led to the enhanced expression of p-SMAD1/5/9 through activation of the SMAD signaling pathway (p < 0.05), while inhibition of the SMAD pathway abrogated the pro-calcification effects of VAPB. Dual immunofluorescence staining demonstrated colocalization of VAPB with SMAD1/5/9, and immunoprecipitation confirmed an interaction between VAPB and SMAD1/5/9.
Conclusion:
The findings indicate that VAPB promotes osteogenic differentiation in aortic valve interstitial cells by activating the SMAD signaling pathway.
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