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Early decrease in dna repair proteins, Ku70 and Ku86, and subsequent DNA fragmentation after transient focal cerebral
G W Kim1, N Noshita, T Sugawara
1Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA.
Stroke
|June 2, 2001
Summary
Reduced Ku70 and Ku86 DNA repair proteins after focal cerebral ischemia (FCI) correlate with DNA fragmentation. This suggests a loss of DNA damage defense contributes to brain injury following stroke.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Ku70 and Ku86 are key DNA repair proteins that bind broken DNA ends.
- These proteins initiate DNA repair pathways, particularly for double-strand breaks.
Purpose of the Study:
- To investigate the role of Ku proteins in DNA fragmentation after focal cerebral ischemia (FCI).
- To examine changes in Ku protein expression following transient FCI in a mouse model.
Main Methods:
- Adult male mice underwent 60 minutes of transient focal cerebral ischemia (FCI).
- Ku protein expression was analyzed using immunohistochemistry and Western blot.
- DNA fragmentation was assessed via gel electrophoresis and TUNEL assay.
- Spatial correlation between Ku expression and DNA fragmentation was determined through double labeling.
Main Results:
- Constitutive Ku protein expression was observed in control brains.
- A significant reduction in Ku-expressing cells and protein levels occurred within 4-24 hours post-reperfusion.
- DNA laddering (fragmentation) was evident 24 hours after reperfusion.
- Loss of Ku immunoreactivity coincided with increased TUNEL-positive staining.
Conclusions:
- Early reduction of Ku proteins following FCI is linked to DNA fragmentation.
- The diminished presence of Ku proteins may impair DNA damage defense mechanisms.
- This loss of defense could be a key factor in the mechanism of DNA fragmentation observed after stroke.