脳虚血に対する Heat shock protein 70 の保護作用-新生仔マウス脳虚血・低酸素負荷モデルを用いて-

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Apoptosis is implicated in neonatal brain injury among various forms of cell death. Here we show that over-expression of heat shock protein (Hsp) 70, an anti-apoptotic protein, protects the neonatal brain from hypoxic/ischemic (H/I) injury and the pathways involved in the protection. In our study, postnatal day 7 (P7) transgenic mice over-expressing rat Hsp70 (Tg) and their wild type littermates (Wt) underwen unilateral common carotid artery ligation followed by 30 min exposure to 8% O_2. Significant neuroprotection was observed in Tg versus Wt mice on P12, correlating with high level of constitutive but not inducible Hsp70 in the Tg. Western blot analysis showed that translocation of cytochrome c, but not apoptosis-inducing factor (AIF), from mitochondria into cytosol was significantly reduced in Tg 24 hrs after H/I compared to Wt mice. Reduced caspase-9 cleavage was also observed in Hsp70 Tg mice compared to Wt littermates 24 hrs after H/I. Co-immunoprecipitation detected more Hsp70 bound to Apaf-1 and AIF in Tg than Wt mice 24 hrs after H/I, inversely correlating with the amount of nuclear but not cytosolic AIF translocation.　In conclusion, Hsp70 could suppress the activation of caspase-9 by reducing cytochrome c release via mitochondria and directly interacting with Apaf-1 in the apoptotic pathway during neonatal H/I injury. Also interaction between Hsp70 and AIF might have reduced downstream events leading to cell death, including the reduction of nuclear AIF translocation in the neonatal brains of Hsp70 Tg mice after H/I. We hope that those findings may help identify new potential targets for anti-ischemic therapy.　Key word: Heat shock protein 70, hypoxic/ischemia, apoptosis
山形大学の論文
2005-08-15

脳虚血に対する Heat shock protein 70 の保護作用-新生仔マウス脳虚血・低酸素負荷モデルを用いて-

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