title: Hsp70 overexpression sequesters AIF and reduces neonatal hypoxic/ischemic brain injury.
abstract: Apoptosis is implicated in neonatal hypoxic/ischemic (H/I) brain injury among various forms of cell death. Here we investigate whether overexpression of heat shock protein (Hsp) 70, an antiapoptotic protein, protects the neonatal brain from H/I injury and the pathways involved in the protection. Postnatal day 7 (P7) transgenic mice overexpressing rat Hsp70 (Tg) and their wild-type littermates (Wt) underwent unilateral common carotid artery ligation followed by 30 mins exposure to 8% O(2). Significant neuroprotection was observed in Tg versus Wt mice on both P12 and P21, correlating with a high level of constitutive but not inducible Hsp70 in the Tg. More prominent injury was observed in Wt and Tg mice on P21, suggesting its continuous evolution after P12. Western blot analysis showed that translocation of cytochrome c, but not the second mitochondria-derived activator of caspase (Smac)/DIABLO and apoptosis-inducing factor (AIF), from mitochondria into cytosol was significantly reduced in Tg 24 h after H/I compared with Wt mice. Coimmunoprecipitation detected more Hsp70 bound to AIF in Tg than Wt mice 24 h after H/I, inversely correlating with the amount of nuclear, but not cytosolic, AIF translocation. Our results suggest that 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.
authors.affiliation: Department of Neurological Surgery, University of California at San Francisco 94121, USA.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Matsumori
authors.forename: Shwuhuey M
authors.initials: SM
authors.lastname: Hong
authors.forename: Koji
authors.initials: K
authors.lastname: Aoyama
authors.forename: Yang
authors.initials: Y
authors.lastname: Fan
authors.forename: Takamasa
authors.initials: T
authors.lastname: Kayama
authors.forename: R Ann
authors.initials: RA
authors.lastname: Sheldon
authors.forename: Zinaida S
authors.initials: ZS
authors.lastname: Vexler
authors.forename: Donna M
authors.initials: DM
authors.lastname: Ferriero
authors.forename: Philip R
authors.initials: PR
authors.lastname: Weinstein
authors.forename: Jialing
authors.initials: J
authors.lastname: Liu
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; D001810:Blood Volume; D001930:Brain Injuries / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D018450:Disease Progression; D005420:Flavoproteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D020925:Hypoxia-Ischemia, Brain / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D051381:Rats; D013997:Time Factors
chemical_list: C494831:Aifm1 protein, rat; D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; C489013:DIABLO protein, rat; C499605:Diablo protein, mouse; D005420:Flavoproteins; D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; C494830:AIFM1 protein, mouse; D045304:Cytochromes c