Bisphenol A impacts cardiomyocyte differentiation in vitro by modulating cardiac protein expression

Abstract

introduction: Bisphenol A (BPA) is an environmental toxin commonly found in plastics and is able to mimic the actions of endogenous steroid hormones. BPA binds and activates intracellular estrogen receptors (eRα and eRβ) and estrogen related receptor γ (eRRγ), all of which are present in cardiomyocytes. however, it is unclear how BPA impacts the heart. We hypothesized that BPA modulates the expression of proteins regulating cardiac structure, energy and calcium homeostasis during cardiomyocyte differentiation in vitro. Methods: We differentiated h9C2 cells into cardiomyocytes in hormone-replete (Rm) or hormone-depleted (hD) media. We co-treated the cells with graded amounts of Bpa and pure anti-estrogen ICI 182,780, which blocks eRα and eRβ activity. Immunoblotting measured the expression of the structural protein β-myosin heavy chain (βmhC), calcium homeostasis protein sarcoendoplasmic reticulum calcium aTpase (seRCa2a), and the cardiac energy-producing protein creatine kinase (CK). results: expression of these proteins was hormone-dependent during cardiomyocyte differentiation, with expression highest in Rm media after 72 or 96 hours of differentiation. adding 10-8 m BPA to hD media increased cardiac structural (βmhC), energy (CK), and calcium homeostasis (seRCa2a) protein expression. Conversely, 10-7 m BPA added to Rm media decreased protein expression. Co-treatment with ICI 182,780 reduced Bpa-mediated induction of seRCa2a and CK expression in hD media. discussion: BPA modulates cardiac structure, calcium and energy homeostasis protein expression during cardiomyocyte differention in vitro. moreover, the data suggest that BPA mediates these changes in protein expression through activation of cardiomyocyte eRα, eRβ, or eRRγ.