Related Experiment Video
Updated: Jun 17, 2026
Isolation and Characterization of Primary Rat Valve Interstitial Cells: A New Model to Study Aortic Valve Calcification
Published on: November 20, 2017
Reduced sox9 function promotes heart valve calcification phenotypes in vivo
Jacqueline D Peacock1, Agata K Levay, Devin B Gillaspie
1Department of Molecular and Cellular Pharmacology, Leonard M. Miller School of Medicine, University of Miami, 1600 NW 10th Ave., Miami, FL 33136, USA.
Insights
Reduced Sox9 function in heart valves promotes calcification, mimicking valvular disease. This finding suggests Sox9 deficiency may be a genetic cause of calcific valvular disease, offering new insights into treatment strategies.
Area of Science:
- Cardiovascular Biology
- Molecular Genetics
- Connective Tissue Biology
Background:
- Heart valve calcification is a common disease with unknown causes, often requiring valve replacement.
- Sox9, a transcription factor, is crucial for cartilage development and is present in heart valves.
- The role of Sox9 deficiency in promoting heart valve calcification was previously unexamined.
Purpose of the Study:
- To investigate the function of Sox9 in maintaining mature heart valve connective tissue homeostasis.
- To determine if Sox9 deficiency contributes to heart valve calcification.
Main Methods:
- Utilized Sox9(fl/+);Col2a1-cre mice to study Sox9 function in vivo.
- Performed histological and molecular analyses on heart valve tissues.
- Investigated Sox9's role in vitro using direct knockdown and retinoic acid treatment.
Main Results:
- Sox9(fl/+);Col2a1-cre mice exhibited calcific lesions in heart valves with increased bone-related gene expression, inflammation, and matrix remodeling.
- Direct knockdown of Sox9 in vitro led to ectopic calcification in heart valves.
- Retinoic acid induced calcification in vitro, which was reduced by Sox9 overexpression.
Conclusions:
- Reduced Sox9 function promotes heart valve calcification.
- Sox9 deficiency is implicated as a potential genetic factor in calcific valvular disease.
- This study provides novel insights into the molecular mechanisms underlying heart valve calcification.
Rationale:
Calcification of heart valve structures is the most common form of valvular disease and is characterized by the appearance of bone-like phenotypes within affected structures. Despite the clinical significance, the underlying etiology of disease onset and progression is largely unknown and valve replacement remains the most effective treatment. The SRY-related transcription factor Sox9 is expressed in developing and mature heart valves, and its function is required for expression of cartilage-associated proteins, similar to its role in chondrogenesis. In addition to cartilage-associated defects, mice with reduced sox9 function develop skeletal bone prematurely; however, the ability of sox9 deficiency to promote ectopic osteogenic phenotypes in heart valves has not been examined.
Objective:
This study aims to determine the role of Sox9 in maintaining connective tissue homeostasis in mature heart valves using in vivo and in vitro approaches.
Methods And Results:
Using histological and molecular analyses, we report that, from 3 months of age, Sox9(fl/+);Col2a1-cre mice develop calcific lesions in heart valve leaflets associated with increased expression of bone-related genes and activation of inflammation and matrix remodeling processes. Consistently, ectopic calcification is also observed following direct knockdown of Sox9 in heart valves in vitro. Furthermore, we show that retinoic acid treatment in mature heart valves is sufficient to promote calcific processes in vitro, which can be attenuated by Sox9 overexpression.
Conclusions:
This study provides insight into the molecular mechanisms of heart valve calcification and identifies reduced Sox9 function as a potential genetic basis for calcific valvular disease.
