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Updated: Jul 18, 2026
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Visualizing and Quantifying Endonuclease-Based Site-Specific DNA Damage
Published on: August 21, 2021
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.
Summary
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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