Persistent low level of osterix accelerates interleukin-6 production and impairs regeneration after tissue injury

PLoS One. 2013 Jul 26;8(7):e69859. doi: 10.1371/journal.pone.0069859. Print 2013.

Abstract

Osterix (Osx) is an essential transcription factor for osteoblast differentiation and bone formation. Osx knockout show a complete absence of bone formation, whereas Osx conditional knockout in osteoblasts produce an osteopenic phenotype after birth. Here, we questioned whether Osx has a potential role in regulating physiological homeostasis. In Osx heterozygotes expressing low levels of Osx in bones, the expression levels of pro-inflammatory cytokines were significantly elevated, indicating that reduced Osx expression may reflect an inflammatory-prone state. In particular, the expression of interleukin-6, a key mediator of chronic inflammation, was increased in Osx heterozygotes and decreased in Osx overexpressing osteoblasts, and transcriptionally down-regulated by Osx. Although no significant differences were revealed in renal morphology and function between Osx heterozygotes and wild-type under normoxic conditions, recovery of kidneys after ischemic damage was remarkably delayed in Osx heterozygotes, as indicated by elevated blood urea nitrogen and creatinine levels, and by morphological alterations consistent with acute tubular necrosis. Eventually, protracted low Osx expression level caused an inflammatory-prone state in the body, resulting in the enhanced susceptibility to renal injury and the delayed renal repair after ischemia/reperfusion. This study suggests that the maintenance of Osx expression in bone is important in terms of preventing the onset of an inflammatory-prone state.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Down-Regulation
  • Heterozygote
  • Inflammation / pathology
  • Interleukin-6 / biosynthesis*
  • Interleukin-6 / genetics
  • Kidney / metabolism*
  • Kidney / pathology*
  • Kidney / physiopathology
  • Kidney Function Tests
  • Mice
  • Models, Biological
  • Osteoblasts / metabolism
  • Osteoblasts / pathology
  • Osteogenesis
  • Regeneration*
  • Sp7 Transcription Factor
  • Transcription Factors / metabolism*
  • Transcription, Genetic

Substances

  • Interleukin-6
  • Sp7 Transcription Factor
  • Sp7 protein, mouse
  • Transcription Factors

Grants and funding

This work was supported by Basic Science Research Program through The National Research Foundation of Korea (NRF) funded by The Ministry of Education, Science and Technology (grant # 2012R1A1A2007161 and 2012R1A6A3A01017109, http://www.nrf.re.kr). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.