Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.61 (caspase-8)
 6,833 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The release of cytochrome c from the mitochondria to the cytosol is a critical step for downstream caspase-mediated apoptotic signal transduction in ischemia-reperfusion (I/R)-induced myocardial tissue injury. 10-N-nonyl acridine orange (NAO), a cardiolipin-specific dye, has been shown to inhibit Bid-mediated cytochrome c release from isolated mitochondria in vitro; however, the possible protective effects of NAO and the mechanisms underlying the protection from myocardial I/R-induced tissue injury in a rat model are unknown. Male Sprague-Dawley rats were subjected to a 30-min coronary arterial occlusion followed by reperfusion. All rats received either vehicle or NAO (100 microg/kg iv) 10 min before the occlusion. The infarct size in the heart at 24 h after reperfusion was significantly reduced in NAO-treated rats compared with vehicle-treated rats. NAO treatment significantly reduced the cytosolic cytochrome c contents and caspase-9 activity in the ischemic region but did not affect caspase-8 activity. Furthermore, NAO treatment markedly suppressed the translocation of truncated Bid, a proapoptotic Bcl-2 family member, to the mitochondrial fraction. NAO also suppressed the mitochondrial swelling and oxygen uptake stimulated by calcium overload. The results suggest that NAO possesses protective effects against myocardial I/R injury, which may be due to the suppression of cytochrome c release through blockade of truncated Bid translocation to mitochondria and inhibition of the opening of mitochondrial permeability transition pores.
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PMID:Inhibition of cytochrome c release by 10-N-nonyl acridine orange, a cardiolipin-specific dye, during myocardial ischemia-reperfusion in the rat. 1994 77

Cardiolipin (CL) has recently been shown to be both an anchor and an essential activating platform for caspase-8 on mitochondria. These platforms may be at the mitochondrial contact sites in which truncated Bid (tBid) has been demonstrated to be located. A possible role for CL is to anchor caspase-8 at contact sites (between inner and outer membranes), facilitating its self-activation, Bid-full length (FL) cleavage, tBid generation (and Bax/Bak activation and oligomerization), mitochondrial destabilization and apoptosis. We have developed an in vitro system that mimics the mitochondrial membrane contact site platform. This system involves reconstituting caspase-8, Bid-FL and CL complexes in giant unilamellar vesicles (GUVs). We first validated the system by flow cytometry analysis of light-scattering properties and nonyl acridine orange staining of their CL content. Then, we used flow cytometry analysis to detect the binding of active caspase-8 to CL and the subsequent truncation of bound Bid-FL. The tBid generated interacts with CL and induces GUV breakage and partial re-vesiculation at a smaller size. Our findings suggest an active role for mitochondrial membrane lipids, particularly CL, in binding active caspase-8 and providing a docking site for Bid-FL. This phenomenon was previously only poorly documented and substantially underestimated.
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PMID:Giant unilamellar vesicles (GUVs) as a new tool for analysis of caspase-8/Bid-FL complex binding to cardiolipin and its functional activity. 2136 76