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Formation of the vertebrate heart requires a complex interplay of several temporally regulated signalling cascades. In Xenopus laevis, cardiac specification occurs during gastrulation and requires signals from the dorsal lip and underlying endoderm. Among known Xenopus Wnt genes, only Wnt-11 shows a spatiotemporal pattern of expression that correlates with(More)
Wnt ligands and Frizzled (Fz) receptors have been shown to activate multiple intracellular signaling pathways. Activation of the Wnt-beta-catenin pathway has been described in greatest detail, but it has been reported that Wnts and Fzs also activate vertebrate planar cell polarity (PCP) and Wnt-Ca2+ pathways. Although the intracellular protein Dishevelled(More)
Islet-1 is a LIM-homeodomain transcription factor that has been defined to label cardiac progenitor cells of the second heart field. Here we provide the first analysis of the expression pattern of Xenopus islet-1 (Xisl-1) in the context of cardiovascular development. During early stages of heart development Xisl-1 is co-expressed with Nkx2.5 in the cardiac(More)
In mouse, the LIM-homeodomain transcription factor Islet1 (Isl1) has been shown to demarcate a separate cardiac cell population that is essential for the formation of the right ventricle and the outflow tract of the heart. Whether Isl1 plays a crucial role in the early regulatory network of transcription factors that establishes a cardiac fate in mesodermal(More)
Wnt proteins can activate different intracellular signaling cascades in various organisms by interacting with receptors of the Frizzled family. The first identified Wnt signaling pathway, the Wnt/beta-catenin pathway, has been studied in much detail and is highly conserved among species. As to non-canonical Wnt pathways, the current situation is more(More)
Human endothelial circulating progenitor cells (CPCs) can differentiate to cardiomyogenic cells during co-culture with neonatal rat cardiomyocytes. Wnt proteins induce myogenic specification and cardiac myogenesis. Here, we elucidated the effect of Wnts on differentiation of CPCs to cardiomyogenic cells. CPCs from peripheral blood mononuclear cells were(More)
Adult mammalian cardiac stem cells express the LIM-homeodomain transcription factor Islet1 (Isl1). They are considered remnants of Isl1-positive embryonic cardiac progenitor cells. During amniote heart development, Isl1-positive progenitor cells give rise mainly to the outflow tract, the right ventricle, and parts of the atria. This led to the hypothesis(More)
Six genes are homeobox-containing transcription factors, many of which are expressed in head structures. We isolated a full-length cDNA of a previously unknown Xenopus member of this family. It shares a high sequence homology with mouse and human Six1, which during development are expressed in mesoderm and muscle. In contrast, XSix1 is prominently expressed(More)
FHL2 is a LIM-domain protein expressed in myoblasts but down-regulated in malignant rhabdomyosarcoma cells, suggesting an important role of FHL2 in muscle development. To investigate the importance of FHL2 during myoblast differentiation, we performed a yeast two-hybrid screen using a cDNA library derived from myoblasts induced for differentiation. We(More)
The Wnt family of secreted glycoproteins is involved in the regulation of diverse developmental processes. The classical Wnt/beta-catenin pathway has been thoroughly investigated resulting in the identification of a plethora of components involved in the activation of beta-catenin target genes. Moreover, two additional Wnt-triggered pathways have been(More)