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Continuous Inhibition of MAPK Signaling Promotes the Early Osteoblastic Differentiation and Mineralization of the Extracellular Matrix
Author(s) -
Higuchi Chikahisa,
Myoui Akira,
Hashimoto Nobuyuki,
Kuriyama Kohji,
Yoshioka Kiyoko,
Yoshikawa Hideki,
Itoh Kazuyuki
Publication year - 2002
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.2002.17.10.1785
Subject(s) - microbiology and biotechnology , extracellular matrix , mapk/erk pathway , chemistry , osteocalcin , bone morphogenetic protein , mek inhibitor , mesenchymal stem cell , kinase , type i collagen , bone morphogenetic protein 2 , protein kinase a , bone healing , cellular differentiation , endocrinology , biology , alkaline phosphatase , biochemistry , in vitro , anatomy , gene , enzyme
We screened the small molecule compounds that stimulate osteogenesis by themselves or promote bone morphogenetic protein (BMP)‐induced bone formation. We found that a specific inhibitor for MAPK/extracellular signal‐regulated kinase kinase (MEK)‐1, promoted the early osteoblastic differentiation and mineralization of extracellular matrix (ECM) in C2C12 pluripotent mesenchymal cells treated with recombinant human BMP‐2 (rhBMP‐2) and MC3T3‐E1 preosteoblastic cells. ALP activity was synergistically increased by the treatment with a specific MEK‐1 inhibitor PD98059 and rhBMP‐2 in both cell lines. Twenty‐five micromolar PD98059 promoted mineralization of ECM in rhBMP‐2‐treated C2C12 cells and MC3T3‐E1 cells. In contrast, PD98059 reduced osteocalcin (OCN) secretion and its transcriptional level in rhBMP‐2‐treated C2C12 cells but increased its secretion and mRNA level in MC3T3‐E1 cells. Stable expression of a dominant‐negative MEK‐1 mutant in C2C12 cells represented high ALP activity and low osteocalcin production in the presence of rhBMP‐2, while a constitutively active mutant of MEK‐1 attenuated both of them. Together, our results indicated that BMP‐2‐induced mineralization of ECM of pluripotent mesenchymal stem cells and preosteoblastic cells could be controlled by a fine tuning of the MAPK signaling pathway. Further, MEK‐1 inhibitors would be useful for the promotion of bone formation, for instance, the treatments for delayed fracture healing or advance of localized osteoporotic change after fracture healing.