XB-IMG-147665
Xenbase Image ID: 147665
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Figure 3.
Ectodermin Prevents TGF-β and BMP Signaling
(A) RT-PCR analysis of animal caps expressing the indicated mRNAs (dose in parenthesis). Lanes 2–5: the inductions by Activin (40 pg) are downregulated by increasing doses of Ecto (lane 3, 200 pg; lane 4, 400 pg; lane 5, 800 pg). Lanes 6–11: Ecto (500 pg) blocks inductions by CA-Alk5 (200 pg) and Smad2 (300 pg) but not by FGFr1 (1 ng).
(B) RT-PCR analysis of injected animal caps shows that a low dose of Ecto-MO (25 ng), which is inactive by itself, can induce mesoderm very effectively in conjunction with suboptimal doses of Activin protein (compare lane 4 with lanes 2 and 3).
(C) Ectopic mesoderm gene expressions triggered by Ecto-MO (60 ng) are blocked by coinjection of the TGF-β antagonist Cer-S mRNA (300 pg).
(D) Activation of the BMP target Vent-1 by Smad1 mRNA (1 ng) and CABR mRNA (700 pg) is antagonized by Ecto mRNA (800 pg).
(E) Forced expression of Ecto mRNA (400 pg and 800 pg) in cultured animal caps (harvested at stage 27) leads to upregulation of neural markers (NCAM and Sox2) and downregulation of epidermis (Ker).
(F) Ecto-depleted animal cap cells display a reduced responsiveness to neural induction triggered by increasing amounts of Chordin mRNA. Ecto-depleted animal cap cells are resistant to weak BMP antagonism (lanes 3 and 4) but still undergo neural default differentiation upon complete BMP blockade (lanes 7 and 8). To prevent any interference with the mesoderm-inducing effects of Ecto-MO (+), animal caps were explanted at the early blastula stage (stage 8–8.5), when they have not yet received any mesoderm-inducing signal. (−) stands for Control-MO.
(G–L) Downregulation of Ectodermin by doses of Ecto-MO parallels with reduction of neural tissue (Sox2) and concomitant expansion of epidermis (ker).
(M) A model for the function of Ectodermin during embryogenesis.
Image published in: Dupont S et al. (2005) Copyright © 2005. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View |