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Isolation of Ku70-binding proteins (KUBs)
1Department of Radiation Oncology and Department of Pharmacology and the Ireland Cancer Center,Laboratory of Molecular Stress Responses, Case Western Reserve University, BRB-326 East,10900 Euclid Avenue, Cleveland, OH 44106-4942, USA.
Nucleic Acids Research
|April 29, 1999
Summary
Apolipoprotein J (apoJ) binds to Ku70, a component of the DNA-PK complex involved in DNA repair. This interaction affects DNA end binding, suggesting apoJ
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- DNA double-strand breaks are critical DNA lesions repaired by non-homologous end joining (NHEJ).
- The DNA-dependent protein kinase (DNA-PK) complex, comprising DNA-PKcs, Ku70, and Ku80, is central to NHEJ.
- Other proteins involved in this DNA repair pathway are not fully characterized.
Purpose of the Study:
- To identify novel proteins interacting with the Ku70 subunit of DNA-PK.
- To investigate the role of apolipoprotein J (apoJ) in DNA repair.
Main Methods:
- Yeast two-hybrid analysis to identify Ku70-binding proteins (KUBs).
- Co-immunoprecipitation and far-western analyses to confirm protein interactions.
- Stable expression of apoJ/XIP8 in cell lines to assess its effect on DNA end binding.
Main Results:
- Apolipoprotein J (apoJ), also known as XIP8, was identified as a Ku70-binding protein (KUB1).
- Interactions between apoJ/XIP8 and Ku70 were confirmed in breast cancer and fibroblast cells.
- Overexpression of apoJ/XIP8 decreased Ku70/Ku80 DNA end binding, which was reversible with antibodies.
Conclusions:
- Apolipoprotein J (apoJ/XIP8) interacts with Ku70, a key component of the DNA repair complex.
- This interaction influences the DNA binding activity of the Ku70/Ku80 complex.
- The precise role of apoJ/XIP8 in DNA repair and radiation sensitivity requires further investigation.