Appearance of Nuclear-sorted Caspase-12 Fragments in Cerebral Cortical and Hippocampal Neurons in Rats Damaged by Autologous Blood Clot Embolic Brain Infarctions
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Following endoplasmic reticulum (ER) stress, cerebral infarctions have been reported to involve an apoptotic process, including the activation of the caspase cascade. To confirm whether fragmented caspase-12, which is activated by cleavage and is detectable during ER stress, is also involved in embolic cerebral infarctions in rats, we adopted an autologous blood clot model for the analysis of cerebral infarctions. We performed experiments in rats with brain infarctions, which are closely related to embolic cerebral infarctions. We utilized a homologous blood clot, i.e., natural materials, to form the infarct area. Our findings reveal that caspase-12 is fragmented when infarct areas form in cerebral cortical neurons. Interestingly, we observed that these fragments translocated to the nuclei of not only cerebral cortical neurons but hippocampal neurons. We further found that glucose-regulated protein 78 (GRP78), a marker of ER stress, is up-regulated in both cerebral cortical and hippocampal neurons during cerebral infarction. This result suggests that the fragmentation of caspase-12 and the subsequent nuclear translocation of these fragments are involved in the brain infarction process in rats.
KeywordsCaspase-12 Endoplasmic reticulum stress Translocation Nucleus Cerebral infarction Apoptosis
Glucose-regulated protein 78
Middle cerebral artery occlusion
Hematoxylin and eosin
Terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate nick end labeling
Unfolded protein response
This study was supported by grants-in-aid for scientific research (KAKENHI 21570152) and the “Strategic Project to Support the Formation of Research Bases at Private Universities (SENRYAKU)” (2008–2012) from MEXT (Ministry of Education, Culture, Sports, Science and Technology of Japan). This work was also supported by the Kansai University Special Research Fund, 2009.
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