Abstract
The development of the endocardial cushions in the embryonic heart appears to involve the expression of a number of extracellular matrix (ECM) proteins and their receptors. Defects of atrioventricular canal endocardial cushion formation occur most frequently in children with trisomy 21 (Down's syndrome). Genes encoding two of the three chains for type VI collagen, a component of most ECMs, are located on human chromosome 21 within the region thought responsible for the congenital heart defect phenotype associated with trisomy 21. We have examined the expression patterns of type VI collagen in the embryonic mouse heart. An affinity-purified polyclonal type VI collagen antibody was used for immunohistochemical analysis on cryofixed mouse heart sections (d8.0 p.c. to neonatal). Primary antibody was visualized with a FITC-conjugated secondary antibody viewed under fluorescent microscopy. We have determined that type VI collagen is first expressed in the endocardial cushions of the antrioventricular (AV) canal in close association with the endocardium and forming cushion mesenchymal cells. Although type VI collagen is subsequently expressed in other areas of the heart, it remains concentrated in the cushion tissue destined to become the AV valves and membranous septa. This expression pattern is retained in the AV valve leaflets and septa of later stage embryos and neonatal mice. Localization of the three individual type VI collagen chains by in situ hybridization using radiolabeled chain-specific riboprobes on embryonic mouse heart sections correlates well with the observed type VI collagen protein immuno-localization. These data demonstrate that type VI collagen is expressed in the developing AV valves and septa, supporting the molecular genetic studies indicating that type VI collagen is involved in the heart defect phenotype seen in trisomy 21.(Supported by NIH SCOR in Congenital Heart Disease, HL 42266-06).
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
