The protection of Bcl-2 overexpression on rat cortical neuronal injury caused by analogous ischemia/reperfusion in vitro.
Recent studies have suggested that neuronal apoptosis in cerebral ischemia could arise from dysfunction of endoplasmic reticulum (ER) and mitochondria. B-cell lymphoma/leukemia-2 gene (Bcl-2) has been described as an inhibitor both in programmed cell death (PCD) and ER dysfunction during apoptosis, and the Bcl-2 family play a key role in regulating the PCD, both locally at the ER and from a distance at the mitochondrial membrane. However, its signal pathways and concrete mechanisms in endoplasmic reticulum-initiated apoptosis remain incompletely understood. We therefore investigate whether ischemia/reperfusion (I/R) causes neuronal apoptosis in part via cross-talk between ER and mitochondria or not, and how the overexpression of Bcl-2 prevents this form of cell death. Here we show that analogous I/R-induced cell death occurs consequent to interactions of ER stress and mitochondrial death pathways. The participation of the mitochondrial pathway was demonstrated by the release of cytochrome C (cyt C) from mitochondrial into cytoplasmic fractions and caspase-9 cleavage. The involvement of ER stress was further supported by the observable increase of glucose-regulated protein 78(GRP78)/BiP expression and caspase-12 activity. Furthermore, prior to these changes, swelling of the ER lumen and dissociation of ribosomes from rough ER were detected by electron microscopy. Bcl-2 overexpression inhibits the release of cyt C and the activation of caspase-9/-8/-3 but not caspase-12 based on the results of Western blot. These suggest that cross-talk between ER and mitochondria participate in neuronal damage after ischemia/reperfusion. Bcl-2 overexpression could suppress I/R-induced neuronal apoptosis via influencing mitochondrial integrity.
Zhang
Hong
H
Institute of Cerebrovascular Diseases, Affiliated Hospital of Qingdao University Medical College, Qingdao 266003, China.
Li
Qin
Q
Li
Zhen
Z
Mei
Yuanwu
Y
Guo
Yunliang
Y
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000293:injuries*; D045304:Cytochromes c / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure*; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000503:physiopathology*; D015398:Signal Transduction / Q000502:physiology; D015854:Up-Regulation
D019253:Proto-Oncogene Proteins c-bcl-2; D045304:Cytochromes c; D020169:Caspases