References of "Larbuisson, Arnaud"
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See detailRôle des récepteurs Fgfs dans la formation des cartilages crâniens du zebrafish
Larbuisson, Arnaud ULg

Doctoral thesis (2013)

Les récepteurs des « fibroblast growth factor » (Fgfrs) sont des récepteurs membranaires à domaine tyrosine kinase. On en dénombre 5 jusqu’à présent. C’est l’interaction ligand-récepteur qui permet le ... [more ▼]

Les récepteurs des « fibroblast growth factor » (Fgfrs) sont des récepteurs membranaires à domaine tyrosine kinase. On en dénombre 5 jusqu’à présent. C’est l’interaction ligand-récepteur qui permet le passage de l’information et, entre autres, l’activation de facteurs de transcription impliqués dans le développement cellulaire et/ou dans la morphogenèse. Notre étude concerne la fonction des Fgfrs dans le développement des cartilages crâniens chez le zebrafish. Le profil d’expression de 4 récepteurs a été étudié à différents stades du développement par hybridation in situ. Ces résultats suggèrent que, au niveau de la région pharyngienne, les Fgfr1a et Fgfr2 sont exprimés dans l’endoderme de 24 hpf à 3 dpf. Le Fgfr3 est également exprimé dans l’endoderme pharyngien aux mêmes stades mais dans le cartilage à 3 dpf. La fonction des récepteurs 1a, 2 et 3 a été étudiée par l’injection de morpholinos dirigés contre leur ARNm. Le marquage des cartilages par l’Alcian Blue montre qu’à 4 dpf, l’absence de chacun des récepteurs engendre des modifications dans la structure et la morphologie des cartilages pharyngiens. L’utilisation d’un transgénique dominant négatif pour les récepteurs nous a permis de déterminer que la signalisation Fgf est cruciale aux alentours de 30 hpf pour la chondrogenèse pharyngienne. Nous avons mis en évidence que les Fgfr1a et Fgfr2 participent à la chondrogenèse pharyngienne via le contrôle d’une cascade génétique endodermique Runx3-Egr1-Sox9b-Fsta sans affecter la différenciation et migration des CCNc/chondrocytes. De plus, notre étude préliminaire portant sur le Fgfr3 nous permet d’émettre l’hypothèse que ce récepteur est impliqué dans le processus de chondrogenèse et que celui-ci joue son rôle avant la migration des CCNc à 24 hpf. [less ▲]

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See detailFunctional study of the Ser/Arg-rich splicing factor SRSF5a during zebrafish embryonic development.
Joris, Marine ULg; Larbuisson, Arnaud ULg; Muller, Marc ULg et al

Poster (2013, April 18)

To investigate the role of the splicing factor SRSF5a during zebrafish embryonic development, we performed SRSF5a knockdown by morpholino microinjection and we analysed control and morphant transcriptomes ... [more ▼]

To investigate the role of the splicing factor SRSF5a during zebrafish embryonic development, we performed SRSF5a knockdown by morpholino microinjection and we analysed control and morphant transcriptomes using RNA sequencing. [less ▲]

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See detailFgf receptors Fgfr1a and Fgfr2 control the function of pharyngeal endoderm in late cranial cartilage development.
Larbuisson, Arnaud ULg; Dalcq, Julia ULg; Martial, Joseph ULg et al

in Differentiation; research in biological diversity (2013), 86

Cranial cartilage derives mainly from cranial neural crest cells and its formation requires fibroblast growth factor (Fgf) signaling for early differentiation and survival of developing chondrocytes as ... [more ▼]

Cranial cartilage derives mainly from cranial neural crest cells and its formation requires fibroblast growth factor (Fgf) signaling for early differentiation and survival of developing chondrocytes as well as patterning of the endodermal pouches. Here, we investigate the role of Fgf receptors in chondrocyte maturation at later stages, beyond 24hpf. Using inducible expression of a dominant-negative Fgf receptor, we show that Fgf signaling is required around 30hpf for correct cartilage formation. The receptor genes fgfr1a and fgr2 are expressed in pharyngeal endodermal pouches after 24hpf or 26hpf, respectively. Depletion of any of these two receptors by microinjection of antisense morpholinos results in severe defects in cartilage formation at 4dpf and a decrease in expression of the late chondrocyte markers barx1 and runx2b. Although endodermal pouches are correctly formed and patterned, receptor knock down leads to decreased expression of runx3, egr1 and sox9b in this tissue, while expression of fsta, coding for a secreted BMP/Tgfss inhibitor, is clearly increased. Rescue experiments revealed that each Fgfr1a or Fgfr2 receptor is able to compensate for the loss of the other. Thus, we show that minimal amounts of Fgfr1a or Fgfr2 are required to initiate a regulatory cascade in pharyngeal endoderm reducing expression of fsta, thereby allowing correct BMP signaling to the maturing chondrocytes of the head cartilage. [less ▲]

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See detailRoles of Fgf receptors in cranial cartilage formation in zebrafish
Larbuisson, Arnaud ULg

Poster (2012, June)

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See detailRUNX3, EGR1 AND SOX9B FORM A REGULATORY CASCADE REQUIRED TO MODULATE BMP-SIGNALING DURING CRANIAL CARTILAGE DEVELOPMENT IN ZEBRAFISH.
Dalcq, Julia ULg; Pasque, Vincent; Ghaye, Aurélie ULg et al

in PLoS ONE (2012), in press

The cartilaginous elements forming the pharyngeal arches of the zebrafish derive from cranial neural crest cells. Their proper differentiation and patterning are regulated by reciprocal interactions ... [more ▼]

The cartilaginous elements forming the pharyngeal arches of the zebrafish derive from cranial neural crest cells. Their proper differentiation and patterning are regulated by reciprocal interactions between neural crest cells and surrounding endodermal, ectodermal and mesodermal tissues. In this study, we show that the endodermal factors Runx3 and Sox9b form a regulatory cascade with Egr1 resulting in transcriptional repression of the fsta gene, encoding a BMP antagonist, in pharyngeal endoderm. Using a transgenic line expressing a dominant negative BMP receptor or a specific BMP inhibitor (dorsomorphin), we show that BMP signaling is indeed required around 30 hpf in the neural crest cells to allow cell differentiation and proper pharyngeal cartilage formation. Runx3, Egr1, Sox9b and BMP signaling are required for expression of runx2b, one of the key regulator of cranial cartilage maturation and bone formation. Finally, we show that egr1 depletion leads to increased expression of fsta and inhibition of BMP signaling in the pharyngeal region. In conclusion, we show that the successive induction of the transcription factors Runx3, Egr1 and Sox9b constitutes a regulatory cascade that controls expression of Follistatin A in pharyngeal endoderm, the latter modulating BMP signaling in developing cranial cartilage in zebrafish. [less ▲]

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