Gene inactivation of Na+/H+ exchanger isoform 1 attenuates apoptosis and mitochondrial damage following transient focal cerebral ischemia.
We investigated mechanisms underlying the Na+/H+ exchanger isoform 1 (NHE1)-mediated neuronal damage in transient focal ischemia. Physiological parameters, body and tympanic temperatures, and regional cerebral blood flow during 30 min of middle cerebral artery occlusion were similar in wild-type NHE1 (NHE1+/+) and NHE1 heterozygous (NHE1+/-) mice. NHE1+/+ mice developed infarct volume of 57.3 +/- 8.8 mm(3) at 24 h reperfusion (Rp), which progressed to 86.1 +/- 10.0 mm(3) at 72 h Rp. This delayed cell death was preceded by release of mitochondrial cytochrome c (Cyt. C), nuclear translocation of apoptosis-inducing factor (AIF), activation of caspase-3, and TUNEL-positive staining and chromatin condensation in the ipsilateral hemispheres of NHE1+/+ brains. In contrast, NHE1+/- mice had a significantly smaller infarct volume and improved neurological function. A similar neuroprotection was obtained with NHE1 inhibitor HOE 642. The number of apoptotic cells, release of AIF and Cyt. C or levels of active caspase-3 was significantly reduced in NHE1+/- brains. These data imply that NHE1 activity may contribute to ischemic apoptosis. Ischemic brains did not exhibit changes of NHE1 protein expression. In contrast, up-regulation of NHE1 expression was found in NHE1+/+ neurons after in vitro ischemia. These data suggest that NHE1 activation following cerebral ischemia contributes to mitochondrial damage and ischemic apoptosis.
Wang
Yanping
Y
Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
Luo
Jing
J
Chen
Xinzhi
X
Chen
Hai
H
Cramer
Sam W
SW
Sun
Dandan
D
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002545:Brain Ischemia / Q000378:metabolism / Q000473:pathology*; D053148:Caspase 3 / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation; D045304:Cytochromes c / Q000378:metabolism; D020868:Gene Silencing; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D051379:Mice; D008822:Mice, Transgenic; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology*; D009474:Neurons / Q000166:cytology / Q000502:physiology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012039:Regional Blood Flow; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics* / Q000378:metabolism
D027682:Cation Transport Proteins; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020033:Protein Isoforms; C490997:Slc9a1 protein, mouse; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers; D045304:Cytochromes c; D053148:Caspase 3