PKR plays a positive role in osteoblast differentiation by regulating GSK-3β activity through a β-catenin-independent pathway

Kaya Yoshida, Hirohiko Okamura, Kazuhiko Ochiai, Yumi Hoshino, Tatsuji Haneji, Masami Yoshioka, Daisuke Hinode, Hideo Yoshida

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7 Citations (Scopus)


Double-stranded RNA-dependent protein kinase (PKR) is involved in various cellular functions. We previously reported that PKR regulates osteoblast differentiation, but the specific mechanisms by which this occurs remain unclear. In this study, we investigated the role of PKR in Glycogen synthase kinase 3β (GSK-3β) regulation of osteoblast differentiation. Lithium chloride (LiCl), a GSK-3β inhibitor, increased GSK-3β phosphorylation in MC3T3-E1 and MG-63 cells. LiCl also inhibited Runx2 and expression of its regulated genes, causing inhibition of Alkaline phosphatase activity and mineralization. LiCl injection to the calvaria in mice suppressed bone formation. Further, GSK-3β phosphorylation was increased in osteoblasts, by Akt-independent mechanisms, in which PKR was constitutively inactivated. A PKR inhibitor, 2-aminopurine, also induced GSK-3β phosphorylation in MC3T3-E1 and MG-63 cells. Further, Runx2 and its regulated genes were inhibited in PKR-inactivated osteoblasts, and differentiation was suppressed through a β-catenin-independent pathway. PKR positively regulates the differentiation of osteoblasts by mediating GSK-3β activity through a β-catenin-independent pathway.

Original languageEnglish
Pages (from-to)99-105
Number of pages7
JournalMolecular and cellular endocrinology
Issue number1-2
Publication statusPublished - Sep 25 2012



  • Double-stranded RNA-dependent protein kinase
  • Glycogen synthase kinase 3β
  • Osteoblast differentiation

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology

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