DKK1 Induced by 1,25D3 Is Required for the Mineralization of Osteoblasts
Overview
Biophysics
Cell Biology
Molecular Biology
Authors
Affiliations
1α,25-dihydroxyvitamin D3 (1,25D3), the most popular drug for osteoporosis treatment, drives osteoblast differentiation and bone mineralization. Wnt/β-catenin signaling is involved in commitment and differentiation of osteoblasts, but the role of the Dickkopf-related protein 1 (DKK1), a Wnt antagonist, in osteoblasts remains unknown. Here, we demonstrate the molecular mechanism of DKK1 induction by 1,25D3 and its physiological role during osteoblast differentiation. 1,25D3 markedly promoted the expression of both CCAAT/enhancer binding protein beta (C/EBPβ) and DKK1 at day 7 during osteoblast differentiation. Interestingly, mRNA and protein levels of C/EBPβ and DKK1 in osteoblasts were elevated by 1,25D3. We also found that C/EBPβ, in response to 1,25D3, directly binds to the human DKK1 promoter. Knockdown of C/EBPβ downregulated the expression of DKK1 in osteoblasts, which was partially reversed by 1,25D3. In contrast, overexpression of C/EBPβ upregulated DKK1 expression in osteoblasts, which was enhanced by 1,25D3. Furthermore, 1,25D3 treatment in osteoblasts stimulated secretion of DKK1 protein within the endoplasmic reticulum to extracellular. Intriguingly, blocking DKK1 attenuated calcified nodule formation in mineralized osteoblasts, but not ALP activity or collagen synthesis. Taken together, these observations suggest that 1,25D3 promotes the mineralization of osteoblasts through activation of DKK1 followed by an increase of C/EBPβ.
TGF-β signaling regulates differentiation of MSCs in bone metabolism: disputes among viewpoints.
Wei E, Hu M, Wu L, Pan X, Zhu Q, Liu H Stem Cell Res Ther. 2024; 15(1):156.
PMID: 38816830 PMC: 11140988. DOI: 10.1186/s13287-024-03761-w.
Kwon S J Rheum Dis. 2023; 29(1):1-3.
PMID: 37476699 PMC: 10324921. DOI: 10.4078/jrd.2022.29.1.1.
The TNF-NF-kB-DKK1 Axis Promoted Bone Formation in the Enthesis of Ankylosing Spondylitis.
Jo S, Nam B, Lee Y, Park H, Weon S, Choi S J Rheum Dis. 2023; 28(4):216-224.
PMID: 37476360 PMC: 10324906. DOI: 10.4078/jrd.2021.28.4.216.
Vitamin D and Bone: A Story of Endocrine and Auto/Paracrine Action in Osteoblasts.
van Driel M, van Leeuwen J Nutrients. 2023; 15(3).
PMID: 36771187 PMC: 9919888. DOI: 10.3390/nu15030480.
Gao X, Sun X, Cheng H, Ruzbarsky J, Mullen M, Huard M Int J Mol Sci. 2023; 24(3).
PMID: 36768718 PMC: 9916619. DOI: 10.3390/ijms24032396.