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Integration of FGF and TWIST in calvarial bone and suture development.
Development. 2000 May; 127(9):1845-55.D

Abstract

Mutations in the FGFR1-FGFR3 and TWIST genes are known to cause craniosynostosis, the former by constitutive activation and the latter by haploinsufficiency. Although clinically achieving the same end result, the premature fusion of the calvarial bones, it is not known whether these genes lie in the same or independent pathways during calvarial bone development and later in suture closure. We have previously shown that Fgfr2c is expressed at the osteogenic fronts of the developing calvarial bones and that, when FGF is applied via beads to the osteogenic fronts, suture closure is accelerated (Kim, H.-J., Rice, D. P. C., Kettunen, P. J. and Thesleff, I. (1998) Development 125, 1241-1251). In order to investigate further the role of FGF signalling during mouse calvarial bone and suture development, we have performed detailed expression analysis of the splicing variants of Fgfr1-Fgfr3 and Fgfr4, as well as their potential ligand Fgf2. The IIIc splice variants of Fgfr1-Fgfr3 as well as the IIIb variant of Fgfr2 being expressed by differentiating osteoblasts at the osteogenic fronts (E15). In comparison to Fgf9, Fgf2 showed a more restricted expression pattern being primarily expressed in the sutural mesenchyme between the osteogenic fronts. We also carried out a detailed expression analysis of the helix-loop-helix factors (HLH) Twist and Id1 during calvaria and suture development (E10-P6). Twist and Id1 were expressed by early preosteoblasts, in patterns that overlapped those of the FGF ligands, but as these cells differentiated their expression dramatically decreased. Signalling pathways were further studied in vitro, in E15 mouse calvarial explants. Beads soaked in FGF2 induced Twist and inhibited Bsp, a marker of functioning osteoblasts. Meanwhile, BMP2 upregulated Id1. Id1 is a dominant negative HLH thought to inhibit basic HLH such as Twist. In Drosophila, the FGF receptor FR1 is known to be downstream of Twist. We demonstrated that in Twist(+/)(-) mice, FGFR2 protein expression was altered. We propose a model of osteoblast differentiation integrating Twist and FGF in the same pathway, in which FGF acts both at early and late stages. Disruption of this pathway may lead to craniosynostosis.

Authors+Show Affiliations

Institute of Biotechnology and Institute of Dentistry, PO Box 56, Finland. rice@operoni.helsinki.fiNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

10751173

Citation

Rice, D P., et al. "Integration of FGF and TWIST in Calvarial Bone and Suture Development." Development (Cambridge, England), vol. 127, no. 9, 2000, pp. 1845-55.
Rice DP, Aberg T, Chan Y, et al. Integration of FGF and TWIST in calvarial bone and suture development. Development. 2000;127(9):1845-55.
Rice, D. P., Aberg, T., Chan, Y., Tang, Z., Kettunen, P. J., Pakarinen, L., Maxson, R. E., & Thesleff, I. (2000). Integration of FGF and TWIST in calvarial bone and suture development. Development (Cambridge, England), 127(9), 1845-55.
Rice DP, et al. Integration of FGF and TWIST in Calvarial Bone and Suture Development. Development. 2000;127(9):1845-55. PubMed PMID: 10751173.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Integration of FGF and TWIST in calvarial bone and suture development. AU - Rice,D P, AU - Aberg,T, AU - Chan,Y, AU - Tang,Z, AU - Kettunen,P J, AU - Pakarinen,L, AU - Maxson,R E, AU - Thesleff,I, PY - 2000/4/6/pubmed PY - 2000/6/17/medline PY - 2000/4/6/entrez SP - 1845 EP - 55 JF - Development (Cambridge, England) JO - Development VL - 127 IS - 9 N2 - Mutations in the FGFR1-FGFR3 and TWIST genes are known to cause craniosynostosis, the former by constitutive activation and the latter by haploinsufficiency. Although clinically achieving the same end result, the premature fusion of the calvarial bones, it is not known whether these genes lie in the same or independent pathways during calvarial bone development and later in suture closure. We have previously shown that Fgfr2c is expressed at the osteogenic fronts of the developing calvarial bones and that, when FGF is applied via beads to the osteogenic fronts, suture closure is accelerated (Kim, H.-J., Rice, D. P. C., Kettunen, P. J. and Thesleff, I. (1998) Development 125, 1241-1251). In order to investigate further the role of FGF signalling during mouse calvarial bone and suture development, we have performed detailed expression analysis of the splicing variants of Fgfr1-Fgfr3 and Fgfr4, as well as their potential ligand Fgf2. The IIIc splice variants of Fgfr1-Fgfr3 as well as the IIIb variant of Fgfr2 being expressed by differentiating osteoblasts at the osteogenic fronts (E15). In comparison to Fgf9, Fgf2 showed a more restricted expression pattern being primarily expressed in the sutural mesenchyme between the osteogenic fronts. We also carried out a detailed expression analysis of the helix-loop-helix factors (HLH) Twist and Id1 during calvaria and suture development (E10-P6). Twist and Id1 were expressed by early preosteoblasts, in patterns that overlapped those of the FGF ligands, but as these cells differentiated their expression dramatically decreased. Signalling pathways were further studied in vitro, in E15 mouse calvarial explants. Beads soaked in FGF2 induced Twist and inhibited Bsp, a marker of functioning osteoblasts. Meanwhile, BMP2 upregulated Id1. Id1 is a dominant negative HLH thought to inhibit basic HLH such as Twist. In Drosophila, the FGF receptor FR1 is known to be downstream of Twist. We demonstrated that in Twist(+/)(-) mice, FGFR2 protein expression was altered. We propose a model of osteoblast differentiation integrating Twist and FGF in the same pathway, in which FGF acts both at early and late stages. Disruption of this pathway may lead to craniosynostosis. SN - 0950-1991 UR - https://www.unboundmedicine.com/medline/citation/10751173/Integration_of_FGF_and_TWIST_in_calvarial_bone_and_suture_development_ L2 - http://dev.biologists.org/cgi/pmidlookup?view=long&pmid=10751173 DB - PRIME DP - Unbound Medicine ER -