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Msx2 gene dosage influences the number of proliferative osteogenic cells in growth centers of the developing murine skull: a possible mechanism for MSX2-mediated craniosynostosis in humans.
Dev Biol. 1999 Jan 15; 205(2):260-74.DB

Abstract

Throughout its complex morphogenesis, the vertebrate skull must at once protect the brain and expand to accommodate its growth. A key structural adaptation that allows this dual role is the separation of the bony plates of the skull with sutures, fibrous joints that serve as growth centers and allow the calvarial bones to expand as the brain enlarges. Craniosynostosis, the premature fusion of one or more calvarial bones with consequent abnormalities in skull shape, is a common developmental anomaly that disrupts this process. We found previously that a single amino acid substitution in the homeodomain of the human MSX2 gene is associated with the autosomal dominant disorder craniosynostosis, Boston type. This mutation enhances the affinity of Msx2 for its target sequence, suggesting that the mutation acts by a dominant positive mechanism. Consistent with this prediction, we showed that general overexpression of Msx2 under the control of the broadly expressed CMV promoter causes the calvarial bones to invade the sagittal suture. Here we use tissue-specific overexpression of Msx2 within the calvarial sutures to address the developmental mechanisms of craniosynostosis and skull morphogenesis. We demonstrate that a segment of the Msx2 promoter directs reporter gene expression to subsets of cells within the sutures. In late embryonic and neonatal stages, this promoter is expressed in undifferentiated mesenchymal cells medial to the growing bone. By P4, promoter activity is reduced in the suture, exhibiting a punctate pattern in undifferentiated osteoblastic cells in the outer margin of the osteogenic front. Overexpression of Msx2 under the control of this promoter is sufficient to enhance parietal bone growth into the sagittal suture by P6. This phenotype is preceded by an increase in both the number and the BrdU labeling of osteoblastic cells in the osteogenic fronts of the calvarial bones. These findings suggest that an important early event in MSX2-mediated craniosynostosis in humans is a transient retardation of osteogenic cell differentiation in the suture and a consequent increase in the pool of osteogenic cells.

Authors+Show Affiliations

Department of Biochemistry and Molecular Biology, Kenneth R. Norris Cancer Hospital and Institute, 1441 Eastlake Avenue, Los Angeles, California, 90033, USA.No affiliation info availableNo 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, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9917362

Citation

Liu, Y H., et al. "Msx2 Gene Dosage Influences the Number of Proliferative Osteogenic Cells in Growth Centers of the Developing Murine Skull: a Possible Mechanism for MSX2-mediated Craniosynostosis in Humans." Developmental Biology, vol. 205, no. 2, 1999, pp. 260-74.
Liu YH, Tang Z, Kundu RK, et al. Msx2 gene dosage influences the number of proliferative osteogenic cells in growth centers of the developing murine skull: a possible mechanism for MSX2-mediated craniosynostosis in humans. Dev Biol. 1999;205(2):260-74.
Liu, Y. H., Tang, Z., Kundu, R. K., Wu, L., Luo, W., Zhu, D., Sangiorgi, F., Snead, M. L., & Maxson, R. E. (1999). Msx2 gene dosage influences the number of proliferative osteogenic cells in growth centers of the developing murine skull: a possible mechanism for MSX2-mediated craniosynostosis in humans. Developmental Biology, 205(2), 260-74.
Liu YH, et al. Msx2 Gene Dosage Influences the Number of Proliferative Osteogenic Cells in Growth Centers of the Developing Murine Skull: a Possible Mechanism for MSX2-mediated Craniosynostosis in Humans. Dev Biol. 1999 Jan 15;205(2):260-74. PubMed PMID: 9917362.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Msx2 gene dosage influences the number of proliferative osteogenic cells in growth centers of the developing murine skull: a possible mechanism for MSX2-mediated craniosynostosis in humans. AU - Liu,Y H, AU - Tang,Z, AU - Kundu,R K, AU - Wu,L, AU - Luo,W, AU - Zhu,D, AU - Sangiorgi,F, AU - Snead,M L, AU - Maxson,R E, PY - 1999/1/26/pubmed PY - 1999/1/26/medline PY - 1999/1/26/entrez SP - 260 EP - 74 JF - Developmental biology JO - Dev. Biol. VL - 205 IS - 2 N2 - Throughout its complex morphogenesis, the vertebrate skull must at once protect the brain and expand to accommodate its growth. A key structural adaptation that allows this dual role is the separation of the bony plates of the skull with sutures, fibrous joints that serve as growth centers and allow the calvarial bones to expand as the brain enlarges. Craniosynostosis, the premature fusion of one or more calvarial bones with consequent abnormalities in skull shape, is a common developmental anomaly that disrupts this process. We found previously that a single amino acid substitution in the homeodomain of the human MSX2 gene is associated with the autosomal dominant disorder craniosynostosis, Boston type. This mutation enhances the affinity of Msx2 for its target sequence, suggesting that the mutation acts by a dominant positive mechanism. Consistent with this prediction, we showed that general overexpression of Msx2 under the control of the broadly expressed CMV promoter causes the calvarial bones to invade the sagittal suture. Here we use tissue-specific overexpression of Msx2 within the calvarial sutures to address the developmental mechanisms of craniosynostosis and skull morphogenesis. We demonstrate that a segment of the Msx2 promoter directs reporter gene expression to subsets of cells within the sutures. In late embryonic and neonatal stages, this promoter is expressed in undifferentiated mesenchymal cells medial to the growing bone. By P4, promoter activity is reduced in the suture, exhibiting a punctate pattern in undifferentiated osteoblastic cells in the outer margin of the osteogenic front. Overexpression of Msx2 under the control of this promoter is sufficient to enhance parietal bone growth into the sagittal suture by P6. This phenotype is preceded by an increase in both the number and the BrdU labeling of osteoblastic cells in the osteogenic fronts of the calvarial bones. These findings suggest that an important early event in MSX2-mediated craniosynostosis in humans is a transient retardation of osteogenic cell differentiation in the suture and a consequent increase in the pool of osteogenic cells. SN - 0012-1606 UR - https://www.unboundmedicine.com/medline/citation/9917362/Msx2_gene_dosage_influences_the_number_of_proliferative_osteogenic_cells_in_growth_centers_of_the_developing_murine_skull:_a_possible_mechanism_for_MSX2_mediated_craniosynostosis_in_humans_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0012-1606(98)99114-X DB - PRIME DP - Unbound Medicine ER -