Aberrant fibroblast growth factor (FGF) signaling disturbs chondrocyte differentiation in skeletal dysplasia, but the mechanisms underlying this process remain unclear. Recently, FGF was found to activate canonical WNT/β-catenin pathway in chondrocytes via Erk MAP kinase-mediated phosphorylation of WNT co-receptor Lrp6. Here, we explore the cellular consequences of such a signaling interaction. WNT enhanced the FGF-mediated suppression of chondrocyte differentiation in mouse limb bud micromass and limb organ cultures, leading to inhibition of cartilage nodule formation in micromass cultures, and suppression of growth in cultured limbs. Simultaneous activation of the FGF and WNT/β-catenin pathways resulted in loss of chondrocyte extracellular matrix, expression of genes typical for mineralized tissues and alteration of cellular shape. WNT enhanced the FGF-mediated downregulation of chondrocyte proteoglycan and collagen extracellular matrix via inhibition of matrix synthesis and induction of proteinases involved in matrix degradation. Expression of genes regulating RhoA GTPase pathway was induced by FGF in cooperation with WNT, and inhibition of the RhoA signaling rescued the FGF/WNT-mediated changes in chondrocyte cellular shape. Our results suggest that aberrant FGF signaling cooperates with WNT/β-catenin in suppression of chondrocyte differentiation.

• MeSH
• beta-katenin genetika   metabolismus   MeSH
• biologické modely MeSH
• buněčná diferenciace účinky léků   genetika   MeSH
• chondrocyty účinky léků   metabolismus   MeSH
• chrupavka cytologie   účinky léků   metabolismus   MeSH
• fibroblastové růstové faktory farmakologie   MeSH
• fibroblastový růstový faktor 2 farmakologie   MeSH
• HEK293 buňky MeSH
• končetinové pupeny účinky léků   embryologie   metabolismus   MeSH
• konfokální mikroskopie MeSH
• krysa rodu rattus MeSH
• kultivované buňky MeSH
• LDL receptor related protein 6 genetika   metabolismus   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• protein Wnt3A farmakologie   MeSH
• proteiny Wnt genetika   metabolismus   farmakologie   MeSH
• receptory fibroblastových růstových faktorů genetika   metabolismus   MeSH
• signální transdukce účinky léků   genetika   MeSH
• synergismus léků MeSH
• transkriptom účinky léků   genetika   MeSH
• western blotting MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Ecotropical viral integration site 1 (Evi-1) is a transcription factor essential for vascularisation and cell proliferation during embryonic development. The chimeric transcription factor AML1-EVI-1 is activated in leukaemia where it plays a role as a differentiation block and stimulator of proliferation. Here, we cloned chicken Evi-1 and analysed its expression during embryonic development. There was early expression in the pharyngeal arches, in the brain and intermediate mesoderm of chicken embryos at stage 15. Later at stage 20, Evi-1 mesenchymal expression was concentrated in the second pharyngeal arch, and weaker expression was found in the mandibular and maxillary prominences. Facial expression decreased in intensity during development. Evi-1 expression in the limb was also limited to the mesenchyme with the most prominent expression in the anterior margin. Evi-1 was not detectable in the posterior limb bud. At later stages, Evi-1 was expressed in the peripheral mesenchyme of the limb but not in the developing precartilage blastema. At stage 29, the expression became restricted to the perichondrium and interdigital areas; however, the cartilage condensations themselves were negative. To study the function of Evi-1 in chondrogenesis, we knocked down expression in limb micromass cultures using siRNA. Chondrogenesis was significantly reduced in both anterior and posterior cultures. Since Evi-1 was expressed adjacent to the apical ectodermal ridge and this area is a source of FGFs, we tested whether endogenous FGF receptor signalling was necessary to maintain its expression. Inhibitors of FGFRs (PD161570 and SU5402) were applied to wing mesenchyme, and downregulation of Evi-1 expression was observed after treatment with both inhibitors. Therefore, Evi-1 may be a transcription factor mediating the effects of FGF and may also be defining the size of cartilage elements in the limb.

• MeSH
• chondrogeneze MeSH
• chrupavka embryologie   metabolismus   MeSH
• fibroblastový růstový faktor 2 fyziologie   MeSH
• genový knockdown MeSH
• hlava embryologie   MeSH
• klonování DNA MeSH
• končetinové pupeny embryologie   metabolismus   MeSH
• konzervovaná sekvence MeSH
• kuřecí embryo MeSH
• malá interferující RNA genetika   MeSH
• orgánová specificita MeSH
• ptačí proteiny genetika   metabolismus   MeSH
• rozvržení tělního plánu MeSH
• sekvence aminokyselin MeSH
• sekvenční analýza DNA MeSH
• terciární struktura proteinů MeSH
• transkripční faktory genetika   metabolismus   MeSH
• vývojová regulace genové exprese * MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH