Related Experiment Videos
Possible involvement of the p57(Kip2) gene in bone metabolism
1Department of Geriatric Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
Abstract:
We previously uncovered that growth stimulation of rat primary osteoblasts by transforming growth factor-beta1 (TGF-beta1) resulted in a dramatic decrease in p57(Kip2), a member of cyclin-dependent kinase (CDK) inhibitors, through the proteasomal degradation pathway (Urano et al., J. Biol. Chem. 274, 12197-12200, 1999). Here we demonstrated that the amount of p57 protein increases markedly, when rat calvarial primary osteoblasts treated with 1,25-dihydroxyvitamin D3 transit from proliferation toward differentiation. Next, we have analyzed the association of four amino acids deletion polymorphism of p57 and bone mineral density (BMD). The p57 genotype was determined in 154 postmenopausal Japanese women. When we separated the subjects into two groups, one having one or two copies of deletion polymorphism and the other without the deletion, the former subjects had higher BMD (Z score of total body, 0.67 +/- 0.93 vs 0. 23 +/- 0.90, mean +/- standard deviation; P = 0.021). Taken together, these findings suggest that the p57 regulated in the osteoblast proliferation and differentiation may play a role in determination of bone mineral density and pathogenesis of osteoporosis.
Insights
The p57 protein regulates osteoblast growth and differentiation. A specific p57 gene variation is linked to higher bone mineral density in postmenopausal women, potentially impacting osteoporosis risk.
Area of Science:
- Bone Biology
- Cell Cycle Regulation
- Genetics
Background:
- Transforming growth factor-beta1 (TGF-beta1) reduces p57 protein levels in osteoblasts via proteasomal degradation.
- p57 (a cyclin-dependent kinase inhibitor) plays a role in cell cycle control.
Purpose of the Study:
- To investigate the regulation of p57 protein during osteoblast differentiation.
- To analyze the association between p57 gene polymorphism and bone mineral density (BMD).
Main Methods:
- Rat calvarial primary osteoblasts were treated with 1,25-dihydroxyvitamin D3.
- p57 protein levels were assessed during osteoblast proliferation and differentiation.
- p57 genotype was determined in 154 postmenopausal Japanese women.
Main Results:
- p57 protein levels significantly increased as osteoblasts transitioned from proliferation to differentiation.
- Postmenopausal women with a p57 deletion polymorphism exhibited higher BMD compared to those without the deletion (P = 0.021).
Conclusions:
- p57 regulation during osteoblast differentiation is significant.
- p57 gene polymorphism may influence bone mineral density and osteoporosis development.