RESUMO
Scaffoldin, an S100 fused-type protein (SFTP) with high amino acid sequence similarity to the mammalian hair follicle protein trichohyalin, has been identified in reptiles and birds, but its functions are not yet fully understood. Here, we investigated the expression pattern of scaffoldin and cornulin, a related SFTP, in the developing beaks of birds. We determined the mRNA levels of both SFTPs by reverse transcription polymerase chain reaction (RT-PCR) in the beak and other ectodermal tissues of chicken (Gallus gallus) and quail (Coturnix japonica) embryos. Immunohistochemical staining was performed to localize scaffoldin in tissues. Scaffoldin and cornulin were expressed in the beak and, at lower levels, in other embryonic tissues of both chickens and quails. Immunohistochemistry revealed scaffoldin in the peridermal compartment of the egg tooth, a transitory cornified protuberance (caruncle) on the upper beak which breaks the eggshell during hatching. Furthermore, scaffoldin marked a multilayered peridermal structure on the lower beak. The results of this study suggest that scaffoldin plays an evolutionarily conserved role in the development of the avian beak with a particular function in the morphogenesis of the egg tooth.
Assuntos
Proteínas Aviárias/genética , Bico/metabolismo , Galinhas/genética , Coturnix/genética , Plumas/metabolismo , Casco e Garras/metabolismo , Animais , Proteínas Aviárias/metabolismo , Bico/citologia , Bico/embriologia , Evolução Biológica , Embrião de Galinha , Galinhas/crescimento & desenvolvimento , Galinhas/metabolismo , Sequência Conservada , Coturnix/embriologia , Coturnix/metabolismo , Embrião não Mamífero , Epiderme/embriologia , Epiderme/metabolismo , Plumas/citologia , Plumas/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Casco e Garras/citologia , Casco e Garras/embriologia , Proteínas de Filamentos Intermediários/genética , Proteínas de Filamentos Intermediários/metabolismo , Queratinócitos/citologia , Queratinócitos/metabolismo , Mamíferos , Morfogênese/genética , Zigoto/crescimento & desenvolvimento , Zigoto/metabolismoRESUMO
Morphogenesis of hair follicles, teeth, and mammary glands depends on inductive epithelial-mesenchymal interactions mediated by a conserved set of signalling molecules. The early development of different skin appendages is remarkably similar. Initiation of organogenesis is marked by the appearance of a local epithelial thickening, a placode, which subsequently invaginates to produce a bud. These early developmental stages require many of the same genes and signalling circuits and consequently alterations in them often cause similar phenotypes in several skin appendages. After the bud stage, these organs adopt diverse patterns of epithelial growth, reflected in the usage of more divergent genes in each.
Assuntos
Ectodisplasinas/metabolismo , Plumas/embriologia , Folículo Piloso/embriologia , Glândulas Mamárias Humanas/embriologia , Pele/embriologia , Pele/metabolismo , Dente/embriologia , Animais , Ectodisplasinas/genética , Plumas/citologia , Plumas/metabolismo , Folículo Piloso/citologia , Humanos , Glândulas Mamárias Humanas/citologia , Glândulas Mamárias Humanas/metabolismo , Modelos Biológicos , Morfogênese , Pele/citologia , Dente/citologia , Dente/metabolismoRESUMO
Epithelial appendages are derivatives of epithelia that elaborate to form specialized structures and functions. The appendage can protrude out, such as in teeth and feathers, or invaginate in, such as in glands. The epithelia can be ectodermal, such as in hairs, or endodermal, such as in livers. Using feather as a prototype of epithelial appendage, we study the molecular signals involved in the successive stages of epithelial-mesenchymal interactions during morphogenesis. We propose that these form the basics of gene networks, which can be integrated to gene supernetwork and totinetwork. Because the unit of development is molecular pathway rather than single molecule, and the unit of morphogenesis is cell group rather than single cell, we make the analogy between genes/developmental pathways and words/sentences. The study of developmental pathways in epithelial appendage organogenesis will help us to understand the grammar of genes and the basic rules in constructing regulated new growth. This knowledge may contribute to the study of cancer biology (deregulated new growth) and organ regeneration.