Activation of caspase-12 by endoplasmic reticulum stress induced by transient middle cerebral artery occlusion in mice.
We sought to clarify the involvement of caspase-12, a representative molecule related to endoplasmic reticulum (ER) stress-induced cell-death signaling pathways, in neuronal death resulting from ischemia/reperfusion in mice. Transient focal cerebral ischemia (1 h) was produced by intraluminal occlusion of the middle cerebral artery (MCA). We assessed the expression patterns of caspase-12, Bip/GRP78, an ER-resident molecular chaperone whose expression serves as a good marker of ER stress, and caspase-7 by Western blotting and/or immunohistochemistry. Double-fluorescent staining of caspase-12 immunohistochemistry and the terminal deoxynucleotidyl transferase-mediated DNA nick-end labeling (TUNEL) method was performed to clarify the involvement of caspase-12 in cell death. We confirmed that ER stress was induced during reperfusion in our model, as witnessed by up-regulated Bip/GRP78 expression in the MCA territory. Western blot analysis revealed that caspase-12 activation occurred at 5-23 h of reperfusion, and immunoreactivity for caspase-12 was enhanced mainly in striatal neurons on the ischemic side at the same time points. We found the co-localization of caspase-12 immunoreactivity and DNA fragmentation detectable by the TUNEL method. We did not detect the presence of caspase-7 in the ER fraction at the period of caspase-12 cleavage. Our results imply that cerebral ischemia/reperfusion induces ER stress and that caspase-12 activation concurred with ER stress. Caspase-12 seems to be involved in neuronal death induced by ischemia/reperfusion. Caspase-7 is not likely to contribute to the cleavage of caspase-12 in our experimental model.
Shibata
M
M
Department of Neurology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. mshibata@sc.itc.keio.ac.jp
Hattori
H
H
Sasaki
T
T
Gotoh
J
J
Hamada
J
J
Fukuuchi
Y
Y
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism; D053454:Caspase 12; D053179:Caspase 7; D020169:Caspases / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism / Q000473:pathology; D003342:Corpus Striatum / Q000378:metabolism / Q000473:pathology; D003600:Cytosol / Q000378:metabolism; D053938:DNA Fragmentation; D004721:Endoplasmic Reticulum / Q000201:enzymology / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D004789:Enzyme Activation; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins; D007150:Immunohistochemistry / Q000379:methods; D020287:In Situ Nick-End Labeling / Q000379:methods; D020244:Infarction, Middle Cerebral Artery / Q000150:complications / Q000378:metabolism*; D002546:Ischemic Attack, Transient / Q000209:etiology / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008861:Microsomes / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D015424:Reperfusion; D015398:Signal Transduction / Q000502:physiology; D013312:Stress, Physiological / Q000209:etiology / Q000378:metabolism*; D013347:Subcellular Fractions / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors
D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D008565:Membrane Proteins; D018832:Molecular Chaperones; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; C018551:glucose-regulated proteins; C418606:neugrin; C506440:Casp12 protein, mouse; C505524:Casp7 protein, mouse; D053454:Caspase 12; D053179:Caspase 7; D020169:Caspases