Folbp1 promotes embryonic myocardial cell proliferation and apoptosis through the WNT signal transduction pathway

The aim of this study was to evaluate the relationship between Folate-binding protein one (Folbp1) and embryonic cardiac proliferation, apoptosis, and differentiation. Folbp1 gene expression and short interference RNA expression vectors were constructed. Morphology of P19 cells during differentiation was observed by inverted microscope. Cell proliferation was tested using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazoliumbromide (MTT) method. Cell apoptosis was evaluated by DNA ladder and flow cytometry methods, and marker gene expression during differentiation, such as atrial natriuretic peptide (ANP) and cardiac troponin I (cTnI), and marker gene expression during apoptosis (Bax/Bcl-2) was measured by RT-PCR. Additionally, the critical genes (Wnt, GSK3beta, and/or beta-catenin) expressed in the Wnt signaling pathway were confirmed by RT-PCR. The Folbp1 expressing vector and the silencing vector were constructed. From day 5 of differentiation, the absorbance of cells overexpressing Folbp1 was notably higher than the controls, whereas the controls were notably higher than Folbp1 gene silenced P19 cells. P19 cell apoptosis with Folbp1 gene silencing was lower than the controls; however, more cells were driven into S phase. No significant morphological difference was observed in any of the groups. RT-PCR results show that ANP, cTnI, Wnt, Bax/Bcl-2, and beta-catenin were elevated whereas GSK3beta depressed in cells which overexpressed Folbp1 and was contradictory in Folbp1 gene silenced P19 cells. Folbp1 may be an important candidate mediator of folic acid deficiency-induced congenital cardiac anomalies which are induced by the dysfunction of proliferation and apoptosis of the myocardial cell, and possibly caused by the dysfunction of the Wnt signaling pathway.