PKR-mediated degradation of STAT1 regulates osteoblast differentiation

Kaya Yoshida, Hirohiko Okamura, Bruna Rabelo Amorim, Daisuke Hinode, Hideo Yoshida, Tatsuji Haneji

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The double-stranded RNA-dependent protein kinase (PKR) plays a critical role in various biological responses including antiviral defense, cell differentiation, apoptosis, and tumorigenesis. In this study, we investigated whether PKR could affect the post-translational modifications of STAT1 protein and whether these modifications regulate osteoblast differentiation. We demonstrated that PKR was necessary for the ubiquitination of STAT1 protein. The expressions of bone-related genes such as type I collagen, integrin binding sialoprotein, osteopontin, and osterix were suppressed in osteoblasts lacking PKR activity. In contrast, the expressions of interleukin-6 and matrix metalloproteinases 8 and 13 increased in PKR-mutated osteoblasts. The expression and degradation of STAT1 protein were regulated by PKR in a SLIM-dependent pathway. Inhibition of SLIM by RNA interference resulted in the decreased activity of Runx2 in osteoblasts. Stimulation of interleukin-6 expression and suppression of alkaline phosphatase activity were regulated through by SLIM-dependent pathway. However, expressions of bone-related genes and MMPs were regulated by SLIM-independent pathway. Our present results suggest that the aberrant accumulation of STAT1 protein induced by loss of PKR regulate osteoblast differentiation through both SLIM/STAT1-dependent and -independent pathways.

Original languageEnglish
Pages (from-to)2105-2114
Number of pages10
JournalExperimental Cell Research
Volume315
Issue number12
DOIs
Publication statusPublished - Jul 15 2009
Externally publishedYes

Keywords

  • Differentiation
  • Osteoblast
  • PKR
  • SLIM
  • STAT1

ASJC Scopus subject areas

  • Cell Biology

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