Background

The vertebrate heart makes its first sign of appearance at the gastrulation. Gene regulatory network controlling heart development is still not completely understood. Wnt signaling plays a pivotal role in orchestrating differ-ent aspects of early and late embryonic development including heart formation. Wnt ligands through canoni-cal and non-canonical pathways have been shown to be essential for cardiac specification and morphogenesis. For example, Wnt3A and Wnt8 found to be capable of inhibiting endogenous heart induction, antagonizing Dkk-1 and Crescent and sufficient to induce heart forma-tion in non-cardiogenic ventral marginal zone mesoderm [1]. Wnt receptors, Frizzleds, are seven-transmembrane proteins to which Wnts bind to their extracellular part, the cysteine-rich domain (CRD) [2]. Little is still know