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Tipin and Timeless form a mutually protective complex required for genotoxic stress resistance and checkpoint

Danny M Chou1, Stephen J Elledge

  • 1Department of Genetics, Howard Hughes Medical Institute, Center for Genetics and Genomics, Brigham and Women's Hospital, Harvard University Medical School, Boston, MA 02115, USA.

Proceedings of the National Academy of Sciences of the United States of America
|November 23, 2006
PubMed

Insights

Tipin, a nuclear protein, protects cells from DNA damage by associating with the replicative helicase. Its depletion causes sensitivity to genotoxic agents and spontaneous DNA double-strand breaks.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • Tipin is a mammalian protein that interacts with Timeless.
  • Timeless is involved in DNA damage checkpoint responses.

Purpose of the Study:

  • To investigate Tipin's role in DNA damage response.
  • To elucidate the interaction between Tipin and Timeless.

Main Methods:

  • Cellular localization studies to determine Tipin is nuclear.
  • Assays to assess Tipin's association with the replicative helicase.
  • Depletion studies using siRNA to evaluate Tipin's function.
  • Analysis of DNA damage markers like gamma-H2AX foci.

Main Results:

  • Tipin is a nuclear protein that associates with the replicative helicase.
  • Tipin protects cells against genotoxic agents and is required for cell cycle arrest after DNA damage.
  • Tipin depletion leads to sensitivity to ionizing radiation and replication stress.
  • Loss of Tipin results in spontaneous gamma-H2AX foci, indicating DNA double-strand breaks.
  • Tipin and Timeless form a complex that stabilizes both proteins; loss of one leads to the degradation of the other.

Conclusions:

  • Tipin plays a crucial role in maintaining genomic stability by protecting cells from DNA damage.
  • The Tipin-Timeless complex is essential for proper DNA damage checkpoint activation and cellular survival.
  • Similar checkpoint phenotypes in Tipin- and Timeless-depleted cells are explained by their interdependent stability.

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