A vertebrate homolog of the cell cycle regulator Dbf4 is an inhibitor of Wnt signaling required for heart development.
Early stages of vertebrate heart development have been linked to Wnt signaling. Here we show in both gain- and loss-of-function experiments that XDbf4, a known regulator of Cdc7 kinase, is an inhibitor of the canonical Wnt signaling pathway. Depletion of endogenous XDbf4 protein did not disturb gastrulation movements or early organizer genes but resulted in embryos with morphologically defective heart and eyes and suppressed cardiac markers. These markers were restored by overexpressed XDbf4, or an XDbf4 mutant that inhibits Wnt signaling but lacks the ability to regulate Cdc7. This indicates that the function of XDbf4 in heart development is independent of its role in the cell cycle. Moreover, our data suggest that XDbf4 acts through the physical and functional interaction with Frodo, a context-dependent regulator of Wnt signaling. These findings establish an unexpected function for a vertebrate Dbf4 homolog and demonstrate the requirement for Wnt inhibition in early cardiac specification.
Brott
Barbara K
BK
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02215, USA.
Sokol
Sergei Y
SY
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D019521:Body Patterning; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D004247:DNA / Q000235:genetics; D005123:Eye / Q000196:embryology; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000196:embryology*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D015398:Signal Transduction; D051153:Wnt Proteins; D014981:Xenopus / Q000196:embryology* / Q000235:genetics / Q000502:physiology*; D029867:Xenopus Proteins / Q000235:genetics / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C454443:DACT1 protein, Xenopus; D036341:Intercellular Signaling Peptides and Proteins; D051153:Wnt Proteins; D029867:Xenopus Proteins; D004247:DNA