RESUMO
BACKGROUND: Dand5 encodes a protein that acts as an antagonist to Nodal/TGF-ß and Wnt pathways. A mouse knockout (KO) model has shown that this molecule is associated with left-right asymmetry and cardiac development, with its depletion causing heterotaxia and cardiac hyperplasia. OBJECTIVE: This study aimed to investigate the molecular mechanisms affected by the depletion of Dand5. METHODS: DAND5-KO and wild-type embryoid bodies (EBs) were used to assess genetic expression with RNA sequencing. To complement the expression results that pointed towards differences in epithelial to mesenchymal transition (EMT), we evaluated migration and cell attachment. Lastly, in vivo valve development was investigated, as it was an established model of EMT. RESULTS: DAND5-KO EBs progress faster through differentiation. The differences in expression will lead to differences in the expression of genes involved with Notch and Wnt signalling pathways, as well as changes in the expression of genes encoding membrane proteins. Such changes were accompanied by lower migratory rates in DAND5-KO EBs, as well as higher concentrations of focal adhesions. Within valve development, Dand5 is expressed in the myocardium underlying future valve sites, and its depletion compromises correct valve structure. CONCLUSION: The DAND5 range of action goes beyond early development. Its absence leads to significantly different expression patterns in vitro and defects in EMT and migration. These results have an in vivo translation in mouse heart valve development. Knowledge regarding the influence of DAND5 in EMT and cell transformation allows further understanding of its role in development, or even in some disease contexts, such as congenital heart defects.
RESUMO
The collagen- and calcium-binding EGF-like domains 1 (CCBE1) is a secreted protein extensively described as indispensable for lymphangiogenesis during development enhancing VEGF-C signaling. In human patients, mutations in CCBE1 have been found to cause Hennekam syndrome, an inherited disease characterized by malformation of the lymphatic system that presents a wide variety of symptoms such as primary lymphedema, lymphangiectasia, and heart defects. Importantly, over the last decade, an essential role for CCBE1 during heart development is being uncovered. In mice, Ccbe1 expression was initially detected in distinct cardiac progenitors such as first and second heart field, and the proepicardium. More recently, Ccbe1 expression was identified in the epicardium and sinus venosus (SV) myocardium at E11.5-E13.5, the stage when SV endocardium-derived (VEGF-C dependent) coronary vessels start to form. Concordantly, CCBE1 is required for the correct formation of the coronary vessels and the coronary artery stem in the mouse. Additionally, Ccbe1 was found to be enriched in mouse embryonic stem cells (ESC) and revealed as a new essential gene for the differentiation of ESC-derived early cardiac precursor cell lineages. Here, we bring an up-to-date review on the role of CCBE1 in cardiac development, function, and human disease implications. Finally, we envisage the potential of this molecule's functions from a regenerative medicine perspective, particularly novel therapeutic strategies for heart disease.
