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Updated: Aug 11, 2026
Tissue Preparation and Immunostaining of Mouse Craniofacial Tissues and Undecalcified Bone
Published on: May 10, 2019
Developmental expression of Dkk1-3 and Mmp9 and apoptosis in cranial base of mice
Xuguang Nie1, Keijo Luukko, Karianne Fjeld
1Section of Anatomy and Cell Biology, Department of Biomedicine, University of Bergen, Bergen, Norway. Xuguang.Nie@biomed.uib.no
Abstract:
The Dickkopf (Dkk) family and Mmp9 are important for apoptosis and a number of other developmental processes. However, little is known about their roles in the development of cranial base, which is an important structure for coordinated development and growth of the craniofacial skeletons. In order to establish whether and in what way these genes are involved in cranial base development, we examined their expression patterns and cell apoptosis. Dkk1 was first seen in the perichondral mesenchyme in restricted domains from E14, and later in the migrating mesenchymal cells within the cartilage. Thereafter, it was widespread throughout the bones of the cranial base. The expression was downregulated in postnatal stages. Dkk2 was localized in the perichondral mesenchyme outlining the anterior cranial base in embryogenesis. Dkk3 was mainly detected in the occipital-vertebral joint at E13 and E14. Mmp9 transcripts were clustered in the inner layer of perichondral mesenchyme, juxtaposed with the terminally differentiated hypertrophic chondrocytes from E14. Later Mmp9-expressing cells were found at the sites of chondrocyte apoptosis. This was particularly clear at the distal ends of the synchondroses. These data indicate that Mmp9 regulates skeletogenesis in cranial base in a manner that is largely similar to that of the appendicular skeletons. Expression of Dkks suggests other roles that remain to be defined.
Insights
Dickkopf (Dkk) family proteins and Mmp9 are crucial for cranial base development and chondrocyte apoptosis. Mmp9 expression correlates with skeletogenesis, while Dkk roles require further definition.
Area of Science:
- Developmental Biology
- Skeletal Biology
- Molecular Biology
Background:
- The Dickkopf (Dkk) family and matrix metallopeptidase 9 (Mmp9) are implicated in apoptosis and development.
- Cranial base development is vital for craniofacial skeletal growth, but the roles of Dkk and Mmp9 in this process are largely unknown.
Purpose of the Study:
- To investigate the involvement and expression patterns of Dkk family members and Mmp9 in cranial base development.
- To examine the relationship between Mmp9 expression and chondrocyte apoptosis during cranial base formation.
Main Methods:
- Analysis of gene expression patterns for Dkk1, Dkk2, Dkk3, and Mmp9 during embryonic and postnatal development.
- Assessment of cell apoptosis in the cranial base.
Main Results:
- Dkk1 expression was observed in perichondral mesenchyme, migrating cells, and developing cranial base bones, decreasing postnatally.
- Dkk2 localized to the anterior cranial base mesenchyme, and Dkk3 was found in the occipital-vertebral joint.
- Mmp9 transcripts were concentrated near hypertrophic chondrocytes and at sites of chondrocyte apoptosis, particularly in synchondroses, suggesting a role in skeletogenesis similar to appendicular skeletons.
Conclusions:
- Mmp9 plays a significant role in cranial base skeletogenesis, mirroring its function in appendicular skeleton development.
- The expression patterns of Dkk family members suggest distinct and potentially uncharacterized roles in cranial base development.
