Cyclin D1 in low-dose radiation-induced adaptive resistance

K. M. Ahmed, M. Fan, D. Nantajit, N. Cao, Jian-Jian Li

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Cyclin D1 is involved in cell-cycle arrest in DNA-damage response. This study tested the hypothesis that cyclin D1 regulates mitochondrial apoptosis. Cyclin D1 was induced by low-dose ionizing radiation (LDIR; 10-cGy X-ray) in human keratinocytes with an adaptive radioresistance that can be inhibited by short interfering RNA (siRNA)-mediated cyclin D1 inhibition. Cyclin D1 was found to form complex with chaperon 14-3-3ζ in unstressed cells and mutation of 14-3-3ζ Ser-58 to Asp (S58D) significantly impaired 14-3-3ζ binding to cyclin D1. The formation of cyclin D1/14-3-3ζ complex was differently regulated by exposure to low (10-cGy X-ray) versus high (5-Gy γ-ray) doses of radiation. Unlike exposure to 5-Gy that predominantly enhanced cyclin D1 nuclear accumulation, LDIR induced the dissociation of the cyclin D1/14-3-3ζ complex without nuclear translocation, indicating that cytosolic accumulation of cyclin D1 was required for LDIR-induced adaptive response. Further studies revealed a direct interaction of cyclin D1 with proapoptotic Bax and an improved mitochondrial membrane potential (Δψm) in LDIR-treated cells. Consistently, blocking cyclin D1/Bax formation by cyclin D1 siRNA reversed Δψm and inhibited the LDIR-associated antiapoptotic response. These results demonstrate the evidence that cytosolic cyclin D1 is able to regulate apoptosis by interaction with Bax in LDIR-induced adaptive resistance.

Original languageEnglish (US)
Pages (from-to)6738-6748
Number of pages11
Issue number53
StatePublished - Nov 13 2008
Externally publishedYes


  • 14-3-3
  • Adaptive response
  • Bax
  • Cyclin D1
  • Human keratinocytes
  • Radiation resistance

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research
  • Genetics


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