Early decrease in apurinic/apyrimidinic endonuclease is followed by DNA fragmentation after cold injury-induced brain trauma in mice.
Apurinic/apyrimidinic endonuclease, a multifunctional protein in the DNA base excision repair pathway, plays a central role in repairing DNA damage caused by reactive oxygen species. We examined protein expression of apurinic/apyrimidinic endonuclease before and after cold injury-induced brain trauma in mice, where we have previously shown reactive oxygen species to participate. Immunohistochemistry showed the nuclear expression of apurinic/apyrimidinic endonuclease in the entire region of control brains. One hour after cold injury-induced brain trauma, nuclear immunoreactivity was predominantly decreased in the inner boundary of the lesion, whereas there was a slight increase in the outer boundary area. Four hours after cold injury-induced brain trauma, nuclear immunoreactivity was almost absent in the entire lesion, and remained so until 24 h. At this time, a marked increase in apurinic/apyrimidinic endonuclease immunoreactivity was seen in the outer boundary zone. Western blot analysis of the sample from the non-ischemic area showed a characteristic 37,000 mol. wt band, which decreased markedly 24 h after cold injury-induced brain trauma. A time-dependent increase in DNA fragmentation was also observed after cold injury-induced brain trauma. Our data provide the first evidence that apurinic/apyrimidinic endonuclease decreased rapidly in the lesion after cold injury-induced brain trauma, whereas it was significantly increased at the outer boundary zone. Although further examination is necessary to elucidate the direct relationship between apurinic/apyrimidinic endonuclease alteration and the pathogenesis of cold injury-induced brain trauma, our results suggest the possibility that an early decrease in apurinic/apyrimidinic endonuclease and failure of the DNA repair mechanism may contribute to DNA-damaged neuronal cell death after cold injury-induced brain trauma.
Morita-Fujimura
Y
Y
Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, CA 94304, USA.
Fujimura
M
M
Kawase
M
M
Chan
P H
PH
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D001929:Brain Edema / Q000201:enzymology; D001930:Brain Injuries / Q000201:enzymology*; D019757:Carbon-Oxygen Lyases / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D002544:Cerebral Infarction / Q000201:enzymology; D002560:Cerebrovascular Circulation; D003080:Cold Temperature / Q000009:adverse effects*; D053938:DNA Fragmentation; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004586:Electrophoresis; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009419:Nerve Tissue Proteins / Q000032:analysis; D009474:Neurons / Q000737:chemistry / Q000166:cytology / Q000201:enzymology
D009419:Nerve Tissue Proteins; D043223:Deoxyribonuclease IV (Phage T4-Induced); D019757:Carbon-Oxygen Lyases; C486216:Apex1 protein, mouse; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase