TY - JOUR
T1 - Combined effects of androgen and growth hormone on osteoblast marker expression in mouse C2C12 and MC3T3-E1 cells induced by bone morphogenetic protein
AU - Kimura, Kosuke
AU - Terasaka, Tomohiro
AU - Iwata, Nahoko
AU - Katsuyama, Takayuki
AU - Komatsubara, Motoshi
AU - Nagao, Ryota
AU - Inagaki, Kenichi
AU - Otsuka, Fumio
N1 - Publisher Copyright:
© 2017 by the authors; licensee MDPI, Basel, Switzerland.
PY - 2017/1
Y1 - 2017/1
N2 - Osteoblasts undergo differentiation in response to various factors, including growth factors and steroids. Bone mass is diminished in androgen-and/or growth hormone (GH)-deficient patients. However the functional relationship between androgen and GH, and their combined effects on bone metabolism, remains unclear. Here we investigated the mutual effects of androgen and GH on osteoblastic marker expression using mouse myoblastic C2C12 and osteoblast-like MC3T3-E1 cells. Combined treatment with dihydrotestosterone (DHT) and GH enhanced BMP-2-induced expression of Runx2, ALP, and osteocalcin mRNA, compared with the individual treatments in C2C12 cells. Co-treatment with DHT and GH activated Smad1/5/8 phosphorylation, Id-1 transcription, and ALP activity induced by BMP-2 in C2C12 cells but not in MC3T3-E1 cells. The insulin-like growth factor (IGF-I) mRNA level was amplified by GH and BMP-2 treatment and was restored by co-treatment with DHT in C2C12 cells. The mRNA level of the IGF-I receptor was not significantly altered by GH or DHT, while it was increased by IGF-I. In addition, IGF-I treatment increased collagen-1 mRNA expression, whereas blockage of endogenous IGF-I activity using an anti-IGF-I antibody failed to suppress the effect of GH and DHT on BMP-2-induced Runx2 expression in C2C12 cells, suggesting that endogenous IGF-I was not substantially involved in the underlying GH actions. On the other hand, androgen receptor and GH receptor mRNA expression was suppressed by BMP-2 in both cell lines, implying the existence of a feedback action. Collectively the results showed that the combined effects of androgen and GH facilitated BMP-2-induced osteoblast differentiation at an early stage by upregulating BMP receptor signaling.
AB - Osteoblasts undergo differentiation in response to various factors, including growth factors and steroids. Bone mass is diminished in androgen-and/or growth hormone (GH)-deficient patients. However the functional relationship between androgen and GH, and their combined effects on bone metabolism, remains unclear. Here we investigated the mutual effects of androgen and GH on osteoblastic marker expression using mouse myoblastic C2C12 and osteoblast-like MC3T3-E1 cells. Combined treatment with dihydrotestosterone (DHT) and GH enhanced BMP-2-induced expression of Runx2, ALP, and osteocalcin mRNA, compared with the individual treatments in C2C12 cells. Co-treatment with DHT and GH activated Smad1/5/8 phosphorylation, Id-1 transcription, and ALP activity induced by BMP-2 in C2C12 cells but not in MC3T3-E1 cells. The insulin-like growth factor (IGF-I) mRNA level was amplified by GH and BMP-2 treatment and was restored by co-treatment with DHT in C2C12 cells. The mRNA level of the IGF-I receptor was not significantly altered by GH or DHT, while it was increased by IGF-I. In addition, IGF-I treatment increased collagen-1 mRNA expression, whereas blockage of endogenous IGF-I activity using an anti-IGF-I antibody failed to suppress the effect of GH and DHT on BMP-2-induced Runx2 expression in C2C12 cells, suggesting that endogenous IGF-I was not substantially involved in the underlying GH actions. On the other hand, androgen receptor and GH receptor mRNA expression was suppressed by BMP-2 in both cell lines, implying the existence of a feedback action. Collectively the results showed that the combined effects of androgen and GH facilitated BMP-2-induced osteoblast differentiation at an early stage by upregulating BMP receptor signaling.
KW - Androgen
KW - Bone morphogenetic protein (BMP)
KW - Dihydrotestosteone (DHT)
KW - Growth hormone (GH)
KW - Osteoblasts
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U2 - 10.3390/jcm6010006
DO - 10.3390/jcm6010006
M3 - Article
AN - SCOPUS:85073271439
VL - 6
JO - Journal of Clinical Medicine
JF - Journal of Clinical Medicine
SN - 2077-0383
IS - 1
ER -