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Implication of caspases and subcellular compartments in tert-butylhydroperoxide induced apoptosis.

Authors: Haidara, K  Marion, M  Gascon-Barre, M  Denizeau, F  Averill-Bates, DA 
Citation: Haidara K, etal., Toxicol Appl Pharmacol. 2008 May 15;229(1):65-76. Epub 2008 Jan 29.
Pubmed: (View Article at PubMed) PMID:18316105
DOI: Full-text: DOI:10.1016/j.taap.2008.01.010

Oxidative stress has been implicated in many physiopathologies including neurodegenerative diseases, cancer, cardiovascular and respiratory diseases, and in mechanisms of action of environmental toxicants. tert-butylhydroperoxide (t-BHP) is an organic lipid hydroperoxide analogue, which is commonly used as a pro-oxidant for evaluating mechanisms involving oxidative stress in cells and tissues. This study investigates mechanisms of apoptosis induced by oxidative stress in hepatocytes, in particular, the involvement of caspases and subcellular compartments. Freshly isolated hepatocytes were exposed to 0.4 mM t-BHP during 1 h. A general caspase inhibitor, Boc-D-FMK, reduced t-BHP-induced apoptosis (chromatin condensation), confirming the involvement of caspases in apoptosis. A caspase-9 inhibitor, Z-LEHD-FMK, also reduced t-BHP-induced apoptosis, suggesting that caspase-9 plays a critical role in this process. Procaspase-9 underwent cleavage in mitochondria and translocation to the nucleus, where increased caspase-9 activity was detected. The caspase-9 substrates, caspase-3 and caspase-7, were not activated. Caspase-7 was translocated from the cytosol to the endoplasmic reticulum (ER), where it underwent processing; however, enzymatic activity of caspase-7 was inhibited by t-BHP. t-BHP caused cleavage of procaspase-12 at the ER and its subsequent translocation to the nucleus, where increased caspase-12 activity was found. t-BHP caused translocation of calpain from the cytosol to the ER. Calpain inhibition reduced chromatin condensation and caspase-12 activity in the nucleus, suggesting that calpain is involved in caspase-12 activation and apoptosis. This study demonstrates that caspase-9 and caspase-12 are activated in t-BHP-induced apoptosis in hepatocytes. We highlight the importance of subcellular compartments such as mitochondria, ER and nuclei in the apoptotic process.

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RGD Object Information
RGD ID: 2311460
Created: 2009-07-17
Species: All species
Last Modified: 2009-07-17
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.