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Site-Specific alterations in bone characteristics and mechanical properties in MYO9B-Deficient mice
Momoko Karashima1, Farah A Al-Omari1, Keiichiro Watanabe2
1Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH 43210, USA.
Journal of Biomechanics
|December 11, 2025
Summary
Myosin IXB (MYO9B) knockout negatively impacts femur growth and bone quality in mice. However, jawbone characteristics remain unaffected, suggesting site-specific roles for MYO9B in skeletal development.
Area of Science:
- Bone Biology
- Skeletal Development
- Genetics
Background:
- Myosin IXB (MYO9B) is crucial for skeletal growth, interacting with IGF-1 signaling in osteoblasts.
- The specific role of MYO9B in jawbone development is currently unknown.
Purpose of the Study:
- To investigate the impact of MYO9B knockout on mandible and femur characteristics in young mice.
- To understand MYO9B's role in osteoblastic IGF-1 signaling.
Main Methods:
- MYO9B knockout (KO) mice were generated on a C57BL/6 background.
- Microcomputed tomography and dynamic mechanical analysis were used to assess bone parameters.
- In vitro studies examined MYO9B-deficient osteoblasts and IGF-1 signaling.
Main Results:
- MYO9B KO mice exhibited significantly reduced femur length, mass, volume, geometry, and mechanical properties.
- Femur growth plates were thinner with lower bone fraction and tissue mineral density (TMD) in KO mice.
- Mandibular bone characteristics were not significantly different between wild-type (WT) and KO mice.
Conclusions:
- MYO9B deficiency severely impairs appendicular bone development but not jawbone development.
- Loss of MYO9B alters IGF1R expression and signaling, diminishing IGF-1 effects in osteoblasts.
- Differential roles of IGF-1 in jaw versus appendicular bone growth may explain site-specific effects of MYO9B.
