Effects of constitutive β-catenin activation on vertebral bone growth and remodeling at different postnatal stages in mice.
OBJECTIVE
The Wnt/β-catenin signaling pathway is essential for controlling bone mass; however, little is known about the variable effects of the constitutive activation of β-catenin (CA-β-catenin) on bone growth and remodeling at different postnatal stages. The goal of the present study was to observe the effects of CA-β-catenin on vertebral bone growth and remodeling in mice at different postnatal stages. In particular, special attention was paid to whether CA-β-catenin has detrimental effects on these processes.


METHODS
Catnblox(ex 3) mice were crossed with mice expressing the TM-inducible Cre fusion protein, which could be activated at designated time points via injection of tamoxifen. β-catenin was stabilized by tamoxifen injection 3 days, and 2, 4, 5, and 7 months after birth, and the effects lasted for one month. Radiographic imaging, micro-computed tomography, immunohistochemistry, and safranin O and tartrate-resistant acid phosphatase staining were employed to observe the effects of CA-β-catenin on vertebral bone growth and remodeling.


RESULTS
CA-β-catenin in both early (3 days after birth) and late stages (2, 4, 5, and 7 months after birth) increased bone formation and decreased bone resorption, which together increased vertebral bone volume. However, when β-catenin was stabilized in the early stage, vertebral linear growth was retarded, and the mice demonstrated shorter statures. In addition, the newly formed bone was mainly immature and located close to the growth plate. In contrast, when β-catenin was stabilized in the late stage, vertebral linear growth was unaffected, and the newly formed bone was mainly mature and evenly distributed throughout the vertebral body.


CONCLUSIONS
CA-β-catenin in both early and late stages of growth can increase vertebral bone volume, but β-catenin has differential effects on vertebral growth and remodeling when activated at different postnatal stages.
Department of Trauma Surgery, State Key Laboratory of Trauma, Burn and Combined injury, Daping Hospital, Third Military Medical University, ChongQing, China.
Min
M
Jia
Sixu
S
Chen
Bo
B
Zhang
Huaping
H
Liang
Jianquan
J
Feng
Zhaowen
Z
Zong
D000818:Animals; D001846:Bone Development / Q000187:drug effects*; D002454:Cell Differentiation; D005260:Female; D006132:Growth Plate / Q000187:drug effects; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D015398:Signal Transduction / Q000187:drug effects; D014714:Vertebrates / Q000254:growth & development* / Q000378:metabolism; D051176:beta Catenin / Q000494:pharmacology*
D051176:beta Catenin