ZEB2 regulates a transcriptional network of calcium-handling genes in the injured heart

Abstract   Intracellular calcium (Ca2+) overload is known to play a critical role in the development of cardiac dysfunction. Despite the remarkable progress in managing the progression of the disease, the development of effective therapies for heart failure (HF) remains challenging. Therefore, it is of great importance to understand the molecular mechanisms that maintain calcium level and contractility in homeostatic conditions. Here we identified a transcription factor ZEB2 that regulates the expression of numerous contractile and calcium-related genes. Zinc finger E-box-binding homeobox2 (ZEB2) is a transcription factor that plays a role during early fetal development and epithelial-to-mesenchymal transition (EMT); however, its function in the heart remains to be determined. Recently, we found that ZEB2 is upregulated in murine cardiomyocytes shortly after an ischemic event, but returns to baseline levels as the disease progresses. Gain- and loss-of-function genetic mouse models revealed the necessity and sufficiency of ZEB2 to maintain proper cardiac function after ischemic injury. We show that cardiomyocyte-specific ZEB2 overexpression (Zeb2 cTG) protected from ischemia-induced diastolic dysfunction and attenuated the structural remodeling of the heart. Moreover, RNA-sequencing of Zeb2 cTG hearts post-injury implicated ZEB2 in the regulation of numerous calcium-handling and contractile-related genes when compared to wildtype mice. Mechanistically, ZEB2 overexpression increased the phosphorylation of phospholamban (PLN) at both serine-16 and threonine-17, implying enhanced activity of the sarcoplasmic reticulum Ca2+-ATPase (SERCA2A), thereby augmenting contractility. Improved cardiac function in ZEB2-overexpressing hearts correlated with higher expression of several sarcomeric proteins like myosin-binding protein C3 (MYBPC3), desmin (DES) and myosin regulatory light chain 2 (MYL2) further contributing to the observed protective phenotype. Furthermore, we observed a decrease in the activity of Ca2+-depended calcineurin/NFAT signaling, which is the main driver of pathological cardiac remodeling. Conversely to Zeb2 cTg mice, loss of ZEB2 from cardiomyocytes perturbed the expression of calcium- and contractile-related proteins and increased the activity of calcineurin/NFAT pathway, exacerbating cardiac dysfunction. Together, we show that ZEB2 is a central regulator of contractile and calcium-handling components, consequently mediating contractility in the mammalian heart. Further mechanistic understanding of the role of ZEB2 in the regulation of calcium homeostasis in cardiomyocytes is a critical step towards the development of improved therapies for various forms of heart failure. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): DR. E. Dekker from Dutch Heart Foundation