Xenbase Image ID: 147976

Fig. 4. APOBEC2 is a TGFβ inhibitor in Xenopus. (A–F) xA2 prevents cap elongation induced by derrière but not Xnr1. RNAs were injected in the animal poles of 2 cell stage embryos (xA2 2 ng, derrière 200 pg, Xnr1 30 pg). Caps were explanted at stage 10 and cultured to stage 18. (G, H) Expression of xA2 RNA represses derrière-, but not Xnr1-dependent gene induction. RT-PCR of early gastrula (G) and late neurula (H) stage animal caps injected with derrière RNA (200 pg), or Xnr1 RNA (20 pg), with or without xA2 RNA (2 ng). (I) xA2 depletion increased mesoderm induction by derrière RNA. RT-PCR for mesodermal genes (Xnr2, Xbra and MyoD), with ODC as loading control, in stage 18 animal caps injected with derrière RNA (100 pg) and xA2 MO (10 ng). (J) xA2 specifically inhibits Derrière-induced transcription. Transcription assays for the Activin/nodal reporter ARE. Transcriptional inhibition by xA2 was statistically significant with derrière (200 pg RNA), but not with Xnr1 (20 pg RNA). (K) An intact putative deaminase domain is required for the inhibitory activity of xA2. Wild-type, but not the triple mutant xA2 (Mut xA2, 2 ng RNA), inhibited transcription induced by derrière (200 pg RNA). Only the difference in transcriptional activity induced by Derrière alone vs. Derrière + xA2 wild-type was statistically significant (P < 0.001). (L) xA2 blocks the C-terminal phosphorylation of endogenous Smad2/3 induced by derrière. Western blot for total Smad2/3 and C-terminally phosphorylated Smad2/3 in stage 10.5 animal caps. No effect was seen on total Smad2/3 protein levels. Image published in: Vonica A et al. (2011) Copyright © 2011. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

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