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Fgf8 Expression (fgf8 + expression)
Selected AbstractsExpression survey of genes critical for tooth development in the human embryonic tooth germDEVELOPMENTAL DYNAMICS, Issue 5 2007Dahe Lin Abstract In the developing murine tooth, the expression patterns of numerous regulatory genes have been examined and their roles have begun to be revealed. To unveil the molecular mechanisms that regulate human tooth morphogenesis, we examined the expression patterns of several regulatory genes, including BMP4, FGF8, MSX1, PAX9, PITX2, and SHOX2, and compared them with that found in mice. All of these genes are known to play critical roles in murine tooth development. Our results show that these genes exhibit basically similar expression patterns in the human tooth germ compared with that in the mouse. However, slightly different expression patterns were also observed for some of the genes at certain stages. For example, MSX1 expression was detected in the inner enamel epithelium in addition to the dental mesenchyme at the bell stage of the human tooth. Moreover, FGF8 expression remained in the dental epithelium at the cap stage, while PAX9 and SHOX2 expression was detected in both dental epithelium and mesenchyme of the human tooth germ. Our results indicate that, although slight differences exist in the gene expression patterns, the human and mouse teeth not only share considerable homology in odontogenesis but also use similar underlying molecular networks. Developmental Dynamics 236:1307,1312, 2007. © 2007 Wiley-Liss, Inc. [source] Many ways to make a gradientBIOESSAYS, Issue 7 2004J.C. Smith A recent publication1 describes a novel mechanism by which a morphogen gradient might be established. These results concern a gradient of FGF8 expression along the longitudinal axis of the chick embryo with a high level of transcripts at the tail, fading off in an anterior direction. Assaying for intron transcripts, it is shown that fgf8 is transcribed only in the tail cells and that the gradient of fgf8 transcripts is produced by growth and mRNA degradation. This possible mechanism of gradient formation can operate only when growth is involved, as is the case in many examples including the longitudinal axis formation of vertebrates, but is not in some other systems. BioEssays 26:705,706, 2004. © 2004 Wiley Periodicals, Inc. [source] Coordinated regulation of dorsal bone morphogenetic protein 4 and ventral Sonic hedgehog signaling specifies the dorso-ventral polarity in the optic vesicle and governs ocular morphogenesis through fibroblast growth factor 8 upregulationDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 4 2010Takuma Kobayashi Dorsal and ventral specification in the early optic vesicle plays a crucial role in vertebrate ocular morphogenesis, and proper dorsal-ventral polarity in the optic vesicle ensures that distinct structures develop in separate domains within the eye primordium. The polarity is determined progressively during development by coordinated regulation of extraocular dorsal and ventral factors. In the present study, we cultured discrete portions of embryonic chick brains by preparing anterior cephalon, anterior dorsal cephalon and anterior ventral cephalon, and clearly demonstrate that bone morphogenetic protein 4 (BMP4) and Sonic hedgehog (Shh) constitute a dorsal-ventral signaling system together with fibroblast growth factor 8 (FGF8). BMP4 and Shh upregulate Tbx5 and Pax2, as reported previously, and at the same time Shh downregulates Tbx5, while BMP4 affects Pax2 expression to downregulate similarly. Shh induces Fgf8 expression in the ventral optic vesicle. This, in turn, determines the distinct boundary of the retinal pigmented epithelium and the neural retina by suppressing Mitf expression. The lens develops only when signals from both the dorsal and ventral regions come across together. Inverted deposition of Shh and BMP4 signals in organ-cultured optic vesicle completely re-organized ocular structures to be inverted. Based on these observations we propose a novel model in which the two signals govern the whole of ocular development when they encounter each other in the ocular morphogenic domain. [source] Retinoic acid affects craniofacial patterning by changing Fgf8 expression in the pharyngeal ectodermDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 9 2008Makoto Abe Retinoic acid signaling plays important roles in establishing normal patterning and cellular differentiation during embryonic development. In this study, we show that single administration of retinoic acid at embryonic day 8.5 causes homeotic transformation of the lower jaw into upper jaw-like structures. This homeosis was preceded by downregulation of Fgf8 and Sprouty expression in the proximal domain of the first pharyngeal arch. Downregulation of mesenchymal genes such as Dlx5, Hand2, Tbx1 and Pitx2 was also observed. The oropharynx in retinoic acid-treated embryos was severely constricted. Consistent with this observation, Patched expression in the arch endoderm and mesenchyme was downregulated. Thus, retinoic acid affects the expression of subsets of epithelial and mesenchymal genes, possibly disrupting the regional identity of the pharyngeal arch. [source] Phenotypic analyses of mouse embryos with ubiquitous expression of Oct4: Effects on mid,hindbrain patterning and gene expressionDEVELOPMENTAL DYNAMICS, Issue 1 2005Verónica Ramos-Mejía Abstract Oct4 is a transcription factor that has been associated with pluripotency and fate determination in the initial cell lineages of mammals. On the other hand, Pou2, the ortholog of Oct4 in zebrafish, serves additional later functions during brain development acting as a differentiation switch. In mice, Oct4 is expressed throughout the neural plate of embryos until embryonic day (E) 8.0. In this study, we produced transgenic mouse embryos that ubiquitously express Oct4 and analyzed the consequences during development. We show that, at E8.0, a higher dosage of Oct4 in the neuroectoderm is sufficient to transiently alter mid,hindbrain patterning and produced a strong up-regulation of Pax2, indicating that Oct4 can regulate this gene in vivo. After E9.5, ectopic Oct4 in this region produced cell death and affected the development of the forebrain, suggesting that, at these later stages, Oct4 down-regulation is necessary for normal development to proceed. The phenotype of the transgenic embryos was also accompanied with an increase of Fgf8 expression in several of its endogenous domains, suggesting the possibility that Oct4 can participate in the regulation of expression of this ligand. Our observations support the hypothesis that Oct4, like zebrafish Pou2, has a conserved function during early brain patterning in mouse. Developmental Dynamics 232:180,190, 2005. © 2004 Wiley-Liss, Inc. [source] | ||||||||||