Estrogen facilitates osteoblast differentiation by upregulating bone morphogenetic protein-4 signaling

• Published in: Steroids Vol. 78; no. 5; pp. 513 - 520
• Main Authors: Matsumoto, Yoshinori, Otsuka, Fumio, Takano-Narazaki, Mariko, Katsuyama, Takayuki, Nakamura, Eri, Tsukamoto, Naoko, Inagaki, Kenichi, Sada, Ken-ei, Makino, Hirofumi
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.2013
• Subjects: Animals; Bone morphogenetic protein (BMP); Bone Morphogenetic Protein 4 - genetics; Bone Morphogenetic Protein 4 - metabolism; Cell Differentiation - drug effects; Cell Line; Estradiol; Estrogen; Estrogen receptor (ER); Estrogens - pharmacology; Mice; Mineralization; Osteoblast differentiation; Osteoblasts - cytology; Osteoblasts - drug effects; Osteoblasts - metabolism; Signal Transduction - drug effects; Up-Regulation - drug effects; ALK; Bone morphogenetic protein (BMP); BMP; E2-BSA; ALP; Estrogen; Estrogen receptor (ER); DN; Runx; E2; ER; Estradiol; BMPRІІ; Osteoblast differentiation; ActRІІ; TNF-α; Mineralization; TGF-β
• ISSN: 0039-128X; 1878-5867
• DOI: 10.1016/j.steroids.2013.02.011

[Display omitted] •Estradiol enhanced BMP-4-induced osteoblastic marker expression and mineralization.•Estrogen facilitated BMP-4-induced Smad pathway by regulating BMPR and inhibitory Smads expression.•Non-genomic ER activity was involved in osteoblast differentiation induced by BMP-4 and estrogen.•Expression of ERα and BMP-4 was suppressed by BMP-4, showing a negative feedback of osteoblast differentiation. Imbalanced functions of osteoclasts and osteoblasts are involved in various types of bone damage including postmenopausal osteoporosis. In the present study, we investigated the cellular mechanism by which estrogen interacts in the process of osteoblastic differentiation regulated by BMP-4 using mouse MC3T3-E1 cells that express estrogen receptors (ER) and BMP-4. Estradiol enhanced BMP-4-induced Runx2, osterix, ALP and osteocalcin expression in MC3T3-E1 cells. BMP-4-induced mineralization shown by Alizarin red staining was also facilitated by estrogen treatment. It was revealed that estrogen upregulated BMP-4-induced Smad1/5/8 phosphorylation, BRE-Luc activity and Id-1 mRNA expression. The expression of BMPRII was increased by estrogen in MC3T3-E1 cells, and inhibition of BMPRII or ALK-2/3 signaling impaired the effect of estrogen on BMP-4 signaling. Of note, the enhanced expression of osterix, ALP and osteocalcin mRNAs induced by BMP-4 and estrogen was reversed in the presence of an ER antagonist. Given that membrane-impermeable estrogen also upregulated BMP-4-induced expression of osteoblastic markers and Id-1 mRNA, non-genomic ER activity is involved in the mechanism by which estrogen enhances BMP-4-induced osteoblast differentiation in MC3T3-E1 cells. On the other hand, the expression of ERα and endogenous BMP-4 was suppressed by BMP-4 treatment regardless of the presence of estrogen, implying the presence of a negative feedback loop for osteoblast differentiation. Thus, estrogen is functionally involved in the process of osteoblast differentiation regulated by BMP-4 through upregulating BMP sensitivity of MC3T3-E1 cells.