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Updated: Apr 16, 2026
Analysis of Craniomaxillofacial Malformations in Mice Using Three-dimensional Microcomputed Tomography
Published on: January 17, 2025
Integration of comprehensive 3D microCT and signaling analysis reveals differential regulatory mechanisms of
Thach-Vu Ho1, Junichi Iwata1, Hoang Anh Ho1
1Center for Craniofacial Molecular Biology, Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA.
Abstract:
Growth factor signaling regulates tissue-tissue interactions to control organogenesis and tissue homeostasis. Specifically, transforming growth factor beta (TGFβ) signaling plays a crucial role in the development of cranial neural crest (CNC) cell-derived bone, and loss of Tgfbr2 in CNC cells results in craniofacial skeletal malformations. Our recent studies indicate that non-canonical TGFβ signaling is activated whereas canonical TGFβ signaling is compromised in the absence of Tgfbr2 (in Tgfbr2(fl/fl);Wnt1-Cre mice). A haploinsufficiency of Tgfbr1 (aka Alk5) (Tgfbr2(fl/fl);Wnt1-Cre;Alk5(fl/+)) largely rescues craniofacial deformities in Tgfbr2 mutant mice by reducing ectopic non-canonical TGFβ signaling. However, the relative involvement of canonical and non-canonical TGFβ signaling in regulating specific craniofacial bone formation remains unclear. We compared the size and volume of CNC-derived craniofacial bones (frontal bone, premaxilla, maxilla, palatine bone, and mandible) from E18.5 control, Tgfbr2(fl/fl);Wnt1-Cre, and Tgfbr2(fl/fl);Wnt1-Cre;Alk5(fl/+)mice. By analyzing three dimensional (3D) micro-computed tomography (microCT) images, we found that different craniofacial bones were restored to different degrees in Tgfbr2(fl/fl);Wnt1-Cre;Alk5(fl/+) mice. Our study provides comprehensive information on anatomical landmarks and the size and volume of each craniofacial bone, as well as insights into the extent that canonical and non-canonical TGFβ signaling cascades contribute to the formation of each CNC-derived bone. Our data will serve as an important resource for developmental biologists who are interested in craniofacial morphogenesis.
Insights
Transforming growth factor beta (TGFβ) signaling is vital for craniofacial bone development. Reducing TGFβ receptor 1 (Tgfbr1) levels partially rescues skeletal defects caused by Tgfbr2 loss, revealing differential pathway contributions.
Area of Science:
- Developmental Biology
- Molecular Biology
- Genetics
Background:
- Growth factor signaling, particularly transforming growth factor beta (TGFβ), is essential for organogenesis and tissue homeostasis.
- TGFβ signaling critically regulates cranial neural crest (CNC) cell-derived bone development, with loss of Tgfbr2 in CNC cells leading to craniofacial skeletal malformations.
- In Tgfbr2-deficient CNC cells, non-canonical TGFβ signaling is aberrantly activated while canonical signaling is compromised.
Purpose of the Study:
- To investigate the distinct roles of canonical and non-canonical TGFβ signaling in the formation of specific CNC-derived craniofacial bones.
- To quantify the rescue effects of Tgfbr1 haploinsufficiency on craniofacial deformities in Tgfbr2 mutant mice.
- To provide a detailed resource on craniofacial bone anatomy and size in the context of TGFβ signaling perturbations.
Main Methods:
- Utilized a mouse model with conditional deletion of Tgfbr2 in CNC cells (Tgfbr2(fl/fl);Wnt1-Cre) and a model with additional Tgfbr1 haploinsufficiency (Tgfbr2(fl/fl);Wnt1-Cre;Alk5(fl/+)).
- Analyzed craniofacial skeletal development at embryonic day 18.5 (E18.5).
- Employed three-dimensional (3D) micro-computed tomography (microCT) to assess the size and volume of specific CNC-derived bones: frontal bone, premaxilla, maxilla, palatine bone, and mandible.
Main Results:
- Haploinsufficiency of Tgfbr1 (Alk5) partially rescued craniofacial deformities in Tgfbr2 mutant mice, correlating with reduced ectopic non-canonical TGFβ signaling.
- Different craniofacial bones exhibited varying degrees of restoration in Tgfbr2(fl/fl);Wnt1-Cre;Alk5(fl/+) mice, indicating differential sensitivity to TGFβ signaling pathways.
- Comprehensive 3D microCT data provided detailed anatomical landmarks, size, and volume measurements for individual craniofacial bones.
Conclusions:
- Canonical and non-canonical TGFβ signaling pathways contribute differentially to the formation of distinct CNC-derived craniofacial bones.
- Tgfbr1 haploinsufficiency can partially ameliorate craniofacial defects by modulating TGFβ signaling balance.
- The generated data serves as a valuable resource for understanding craniofacial morphogenesis and the intricate roles of TGFβ signaling in skeletal development.
