MiR-21 is continually elevated long-term in the brain after exposure to ionizing radiation

Radiat Res. 2012 Jan;177(1):124-8. doi: 10.1667/rr2764.1. Epub 2011 Oct 28.

Abstract

Ionizing radiation stimulates miR-21 expression in different types of mammalian cells in culture. However, it remains unclear whether radiation could stimulate miR-21 expression in brain cells and tissue and, if so, how long the upregulation of miR-21 would be maintained after exposure to different types of radiation. To answer these questions, we examined the miR-21 levels in irradiated mouse hippocampal cells and brain tissue from mice at different times up to 1 year after whole-body exposure to 0.5 Gy of X rays [low linear energy transfer (LET)] or (56)Fe ions (high LET). The results showed that radiation stimulated miR-21 expression in mouse hippocampal cells and upregulation of EGFR, which is similar to that in human hepatocytes, as we reported previously. Interestingly, the miR-21 levels gradually increased within 1 year after irradiation, although there was no significant difference in the miR-21 low- and high-LET irradiated mice. The high expression of miR-21 in the brain was also associated with high expression of EGFR in irradiated mice; thus our data strongly support that EGFR and miR-21 are in a positive regulatory loop, because it is known that radiation stimulates miR-21 through the EGFR/Stat3 pathway and miR-21 activates the EGFR pathway. Since the brain is relatively resistant to radiation-induced histomorphological changes, our findings may provide a new way to explore radiation-induced pathological changes in the brain by investigating miR-21 and its multiple targets.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Brain / cytology
  • Brain / metabolism*
  • Brain / physiology
  • Brain / radiation effects*
  • Cell Line
  • Gene Expression Regulation / radiation effects
  • Humans
  • Mice
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Neurons / metabolism
  • Neurons / radiation effects
  • Time Factors

Substances

  • MIRN21 microRNA, mouse
  • MicroRNAs