Redistribution of intramitochondrial cardiolipin at the early stage of apoptosis is associated with ROS

Cardiolipin is a unique and ubiquitous diphosphatidylglycerol phospholipid, located exclusively in inner membrane of mitochondria and particularly intermembrane contact sites. Cardiolipin is essential for mitochondrial to maintain its functions. Numerous mitochondrial proteins and processes require the presence of cardiolipin. Recent researches gradually confirm that cardiolipin participates in several mitochondria-dependent apoptotic steps: interactions between cardiolipin and cytochrome c, Bid and caspase-8 have now been established. These functions are associated with the redistribution of cardiolipin in mitochondria. However, the exact mechanism of the redistribution, which happens at the early stage of apoptosis, is still controversial. In this study, we used 10-N-nonyl-3, 6-bis (dimethylamino) acridine (10-N-nonyl acridine orange), a specific probe for cardiolipin to monitor changes of cardiolipin redistribution during apoptosis. We demonstrated that during apoptosis cardiolipin moves to the outer leaflet of mitochondrial inner membrane from the inner leaflet, where it used to be riched in. We also found that ROS (reactive oxygen species) may have association with the redistribution of cardiolipin.