Inhibitory effects of activin-A on osteoblast differentiation during cultures of fetal rat calvarial cells

Takashi Ikenoue, Seiya Jingushi, Ken Urabe, Ken Okazaki, Yukihide Iwamoto

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61 Citations (Scopus)


Activin-A is a member of the transforming growth factor-β (TGF-β) superfamily and is expressed by osteoblasts. However, the role of activin-A on osteoblasts is not clearly understood. We examined the effects of activin- A on osteoblast proliferation or differentiation, and mineralization by the osteoblasts in the first subcultures of fetal rat osteoblasts obtained from calvarial bones. Exogenous activin-A led to impaired formation of bone nodules in a dose-dependent manner, although it did not influence cell proliferation using an MTT assay. This inhibitory effect depended upon the time at which activin-A was added to the culture media, and the effect was most significant when addition took place at the early phase of the culture. In addition, exogenous activin-A inhibited gene expression of type I procollagen, alkaline phosphatase, osteonectin, and osteopontin in the cultured cells using Northern blot analysis. The peak of osteocalcin mRNA was delayed. Gene expression for TGF-β was not influenced by exogenous activin- A. The βA subunit (activin-A) mRNA was detected during the early phase of this culture. These results indicate that activin-A inhibited early differentiation of the fetal rat calvarial cells, or osteoblasts.

Original languageEnglish
Pages (from-to)206-214
Number of pages9
JournalJournal of Cellular Biochemistry
Issue number2
Publication statusPublished - Nov 1 1999

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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