Nuclear translocation of p21(WAF1/CIP1) protein prior to its cytosolic degradation by UV enhances DNA repair and survival

Biochem Biophys Res Commun. 2009 Dec 25;390(4):1361-6. doi: 10.1016/j.bbrc.2009.10.160. Epub 2009 Nov 4.

Abstract

We previously reported that UV induced rapid proteasomal degradation of p21 protein in an ubiquitination-independent manner. Here, UV-induced p21 proteolysis was found to occur in the cytosol. Before cytosolic degradation, however, p21 protein translocated to and transiently accumulated in the nucleus. Nuclear translocation of p21 was not required for its degradation, but rather promoted DNA repair and cell survival. Overexpression of the wild type p21, but not the one with defective nuclear localization signal (NLS), reduced UV-induced DNA damage and cell death. Some of p21 protein translocated to the nucleus were associated with chromatin-bound PCNA and saved from UV-induced proteolysis. These data together show that p21 translocates to the nucleus to participate in DNA repair, while the rest is rapidly degraded in the cytosol. We propose that our findings reflect a mechanism to facilitate removal of damaged cells, enhancing DNA repair at the same time.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Cell Line, Tumor
  • Cell Nucleus
  • Cell Survival
  • Chromatin / metabolism
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism*
  • Cyclin-Dependent Kinase Inhibitor p21 / radiation effects*
  • Cytosol / metabolism*
  • DNA Repair*
  • Humans
  • Proliferating Cell Nuclear Antigen / metabolism
  • Proteasome Endopeptidase Complex / metabolism
  • Ultraviolet Rays

Substances

  • CDKN1A protein, human
  • Chromatin
  • Cyclin-Dependent Kinase Inhibitor p21
  • Proliferating Cell Nuclear Antigen
  • Proteasome Endopeptidase Complex