Nasevicius, A., Hyatt, T., Kim, H., Guttman, J., Walsh, E., Sumanas, S., Wang, Y.S., and Ekker, S.C. (1998) Evidence for a fizzled-mediated wnt pathway required for zebrafish dorsal mesoderm formation. Development (Cambridge, England). 125:4283-4292.
We have used zebrafish as a model system for the study of vertebrate dorsoventral patterning. We isolated a maternally expressed and dorsal organizer localized member of the frizzled family of wnt receptors. Wild-type and dominant, loss-of-function molecules in misexpression studies demonstrate frizzled function is necessary and sufficient for dorsal mesoderm specification. frizzled activity is antagonized by the action of GSK-3, and we show GSK-3 is also required for zebrafish dorsal mesoderm formation. frizzled cooperatively interacts with the maternally encoded zebrafish wnt8 protein in dorsal mesodermal fate determination. This frizzled -mediated wnt pathway for dorsal mesoderm specification provides the first evidence for the requirement of a wnt-like signal in vertebrate axis determination.