Figure 7.
Loss of Prdm16 expression perturbs in vivo TGFβ signaling in the mandible. Immunofluorescent detection of TGFβ2, Phospho-SMAD2 and SMAD7 protein expression in wild-type (wt) (A–F) versus Prdm16Gt683Lex gene trap null mutant (gt) (G–I) E13.5 embryos. Expression of each protein in wild-type embryos is evident in secondary palate shelves (ps), tongue (T), Meckel's cartilage (white ovals in A–I), molar teeth (white arrows) and the undifferentiated mesenchyme between the oral sulci (white asterisks) at the sides of the tongue and the perichodrium surrounding Meckel's cartilage which contains the salivary ducts (sd) (A–F). A dramatic reduction in protein expression levels for each protein is observed in Prdm16Gt683Lex mutants in and around Meckel's cartilage and the region near the base of the tongue, consistent with the mandibular and salivary gland hypoplasia and gross tongue abnormalities observed in these mutants.