論文 - 詳細
| RRC ID | 61243 |
|---|---|
| 著者 | Suzuki E, Ochiai-Shino H, Aoki H, Onodera S, Saito A, Saito A, Azuma T. |
| タイトル | Akt activation is required for TGF-β1-induced osteoblast differentiation of MC3T3-E1 pre-osteoblasts. |
| ジャーナル | PLoS One |
| Abstract |
BACKGROUND:We have previously reported that repeated treatment of human periodontal ligament cells and murine pre-osteoblast MC3T3-E1 cells with transforming growth factor-beta 1 (TGF-β1) inhibited their osteoblastic differentiation because of decreased insulin-like growth factor-1 (IGF-1) secretion. We also found that IGF-1/PI3K signaling plays an important role in osteoblast differentiation induced by TGF-β1 treatment; however, the downstream signaling controlling this remains unknown. The aim of this current study is to investigate whether Akt activation is required for osteoblast differentiation. METHODOLOGY/PRINCIPAL FINDINGS:MC3T3-E1 cells were cultured in osteoblast differentiation medium (OBM) with or without 0.1 ng/mL TGF-β1. OBM containing TGF-β1 was changed every 12 h to provide repeated TGF-β1 administration. MC3T3-E1 cells were infected with retroviral vectors expressing constitutively active (CA) or dominant-negative (DN)-Akt. Alkaline phosphatase (ALP) activity and osteoblastic marker mRNA levels were substantially decreased by repeated TGF-β1 treatment compared with a single TGF-β1 treatment. However, expression of CA-Akt restored ALP activity following TGF-β1 treatment. Surprisingly, ALP activity increased following multiple TGF-β1 treatments as the number of administrations of TGF-β1 increased. Activation of Akt significantly enhanced expression of osteocalcin, but TGF-β1 treatment inhibited this. Mineralization of MC3T3-E1 cells was markedly enhanced by CA-Akt expression under all medium conditions. Exogenous IGF-1 restored the down-regulation of osteoblast-related gene expression by repeated TGF-β1 administration. However, in cells expressing DN-Akt, these levels remained inhibited regardless of IGF-1 treatment. These findings indicate that Akt activation is required for the early phase of osteoblast differentiation of MC3T3-E1 cells induced by TGF-β1. However, Akt activation is insufficient to reverse the inhibitory effects of TGF-β1 in the late stages of osteoblast differentiation. CONCLUSIONS:TGF-β1 could be an inducer or an inhibitor of osteoblastic differentiation of MC3T3-E1 cells depending on the state of Akt phosphorylation. Our results indicate that Akt is the molecular switch for TGF-β1-induced osteoblastic differentiation of MC3T3-E1 cells. |
| 巻・号 | 9(12) |
| ページ | e112566 |
| 公開日 | 2014-1-1 |
| DOI | 10.1371/journal.pone.0112566 |
| PII | PONE-D-14-34911 |
| PMID | 25470129 |
| PMC | PMC4254279 |
| MeSH | Adaptor Proteins, Signal Transducing / metabolism* Animals Cell Differentiation / drug effects Cell Line Gene Expression Regulation / drug effects Genetic Markers Membrane Proteins / metabolism* Mice Osteoblasts / cytology Osteoblasts / drug effects Osteoblasts / physiology* Osteogenesis Proto-Oncogene Proteins c-akt / metabolism* Transforming Growth Factor beta1 / pharmacology* |
| IF | 2.74 |
| リソース情報 | |
| ヒト・動物細胞 | MC3T3-E1(RCB1126) |