TGF-β2 Is Necessary to Induce Snail Expression and Regulate Proliferation and E-Cadherin in the Hair Bud

<div><p>(A–D) Skins from TGF-β2 WT or KO E17.5 embryos were analyzed for expression of TGF-β2 protein (A), which is present in the epidermis and dermis as previously described [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0030011#pbio-0030011-b33" target="_blank">33</a>] and in the hair bud, pSMAD2 (B), Snail (C), and <i>Snail</i> mRNA (D). Arrows point to the hair buds.</p> <p>(E) Western blot analyses of Snail expression in the skins of 2-wk-old <i>K14-Smad2</i> transgenic (SMAD2 TG) and WT littermate (WT) mice. Antibody to tubulin was used as a control for equal protein loadings. The K14-Smad2 Tg mouse was previously shown to possess activated TGF-β signaling [<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0030011#pbio-0030011-b35" target="_blank">35</a>].</p> <p>(F–G) Proliferation markers Ki67 (F) and pMAPK (G) are diminished in <i>TGF-β2</i>-null hair relative to its WT counterpart.</p> <p>(H–J) <i>TGF-β2</i>-null hair fails to down-regulate E-cadherin (H). Wnt and noggin signaling pathways are still intact in the TGF-β2 null hair as nuclear LEF-1 (I) and nuclear β-catenin (J) are still expressed.</p>