Related Experiment Videos
Expression and function of activin beta A during mouse cardiac cushion tissue formation
C S Moore1, C H Mjaatvedt, J D Gearhart
1Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Summary
Activin betaA is crucial for cardiac cushion formation during embryonic development. This protein promotes endothelial cells to transform into mesenchymal cells, essential for heart septation and valve development.
Area of Science:
- Developmental Biology
- Cell Biology
- Molecular Biology
Background:
- Cardiac cushion tissue formation is vital for developing heart valves and septa.
- This process relies on cardiac endothelial cells undergoing an epithelial-mesenchymal transition (EMT).
Purpose of the Study:
- To investigate the role of activin betaA in the epithelial-mesenchymal transition of cardiac endothelial cells during embryonic heart development.
- To determine if activin betaA is the primary inducer of EMT in this context.
Main Methods:
- Utilized Northern and in situ hybridization to detect activin betaA mRNA expression in developing mouse embryos.
- Adapted an in vitro chick assay for mammalian embryos, using conditioned media from embryonic mouse cardiocyte cultures (CCM).
- Employed Western blot analysis to confirm activin betaA presence in CCM and used antisense oligonucleotides to block its function. Studied embryos with a null allele for activin betaA.
Main Results:
- Activin betaA mRNA expression was temporally and spatially correlated with endothelial cell transition during mouse embryogenesis.
- Conditioned media from cardiocyte cultures (CCM) induced mesenchymal cell formation in vitro.
- Antisense oligonucleotides targeting activin betaA inhibited the endothelial-mesenchymal transition.
- CCM derived from activin betaA null embryos showed reduced induction of mesenchymal cells compared to wild-type CCM.
Conclusions:
- Activin betaA plays a significant role in promoting the epithelial-mesenchymal transition of cardiac endothelial cells.
- The findings suggest activin betaA is essential for the formation of mesenchymal cells within endothelial cushions, which is critical for normal heart septation.