Xenbase Image ID: 74590

Figure 1. dkk-1 and crescent, but not frzb, induce cardiac specific gene expression in noncardiogenic tissue. (A) mRNAs encoding various Wnt and BMP antagonists were injected equatorially into ven- tral blastomeres at the four-cell stage. Ventral marginal zone (VMZ) tissue was then explanted at stage 10 and cultured until analyzed by RTCR for gene expres- sion at stage 30 (see Materials and Meth- ods). (B) Injection of dkk-1 or crescent induced both markers of cardiac mesoderm (Tbx5 and Nkx2.5) and heart musclepecific genes (cardiac isoform of troponin-I, TnIc, and myosin heavy chain-alpha, MHC-alpha) in VMZ tissue. frzb, in contrast, induced muscle actin (m. actin), which is primarily a skeletal muscle marker, but not cardiac specific gene expression. Induced genes were expressed at levels comparable to endogenous expression in control dorsal marginal zone (DMZ) explants. (C) TnIc transcripts induced by injection of 1.5 ng of dkk-1 or crescent mRNAs were highly localized, similar to endogenous expression (cf. with control DMZ shown in Figs. 3Cﲒ and 5G), whereas injection of frzb mRNA does not induce TnIc. (F,G) dkk-1, crescent, and frzb block Wnt8 induction of Siamois in animal cap tissue. Wnt8 and Wnt antagonist mRNAs were injected into the animal region of two-cell-stage embryos and caps were isolated at stage 9, cultured, and processed for RTCR at stage 10.5 (F). Antagonism of Wnt8 signaling indicates that functional protein is translated from the injected mRNAs in each case (G). EF1-alpha expression is shown as a control for the RT reaction in all cases. Image published in: Schneider VA and Mercola M (2001) Copyright © 2001. Image reproduced on with permission of the Publisher, Cold Spring Harbor Laboratory Press. This is an Open Access article. Larger Image Printer Friendly View

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