Is BMP‐2 a component of the particulate matrix that is responsible for epithelial/mesenchymal transformation during heart development

Abstract

Early cardiac development involves an epithelial/mesenchymal transformation (EMT) of endothelial cells in the atrioventricular (AV) canal and outflow tract (OT) regions of the heart. It has been shown that the myocardium secrets factors, collectively called particulate matrix that induce this process. Previous reports from our laboratory showed that, only myocardial conditioned media (MyoCM) or EDTA extract can replace the myocardium and drive mesenchyme formation. Reports from other laboratories suggest that bone morphogenetic protein 2 (BMP‐2) has a role in EMT. So, we asked whether BMP‐2 is a part of the particulate matrix. Initial experiments using immunostaining of stage 15–16 chick embryo sections with anti BMP‐2 antibody revealed that BMP‐2 signals were detected within the myocardium of the cushion forming regions and in a group of cells in the endocardial layer of these regions in the heart, but not in the extracellular matrix. To confirm these results, whole heart lysate, EDTA extract from stage 15–16 embryos and soybean agglutinin (SBA) binding proteins from MyoCM will be examined for the presence of BMP‐2 by western blotting analysis.Grant Funding Source : none