Affinity labeling displays the stepwise activation of ICE-related proteases by Fas, staurosporine, and CrmA-sensitive caspase-8
Abstract
The activation of multiple interleukin-1beta converting enzyme-related proteases (caspases) in apoptotic mammalian cells raises questions as to whether the multiple active caspases have distinct roles in apoptotic execution as well as how these proteases are organized in apoptotic signaling pathways. Here we used an affinity-labeling agent, YV(bio)KD-aomk, to investigate the caspases activated during apoptotic cell death. YV(bio)KD-aomk identified six distinct polypeptides corresponding to active caspases in Fas-stimulated Jurkat T cells. On staurosporine treatment, four polypeptides were detected. Competition experiments showed that the labeled caspases have distinct substrate preferences. Stepwise appearance of the labeled caspases in each cell death event was consistent with the view that the activated caspases are organized into protease cascades. Moreover, we found that stepwise activation of caspases similar to that induced by Fas ligation is triggered by exposing non-apoptotic Jurkat cell extracts to caspase-8 (MACH/FLICE/Mch5). Conversely, CrmA protein, a viral suppressor of Fas-induced apoptosis, inhibited the protease activity of caspase-8. Overall, these findings provide evidence that caspase-8, a CrmA-sensitive prot...Continue Reading
Citations
Maspin overexpression modulates tumor cell apoptosis through the regulation of Bcl-2 family proteins
Related Concepts
Related Feeds
Apoptotic Caspases
Apoptotic caspases belong to the protease enzyme family and are known to play an essential role in inflammation and programmed cell death. Here is the latest research.
Apoptosis
Apoptosis is a specific process that leads to programmed cell death through the activation of an evolutionary conserved intracellular pathway leading to pathognomic cellular changes distinct from cellular necrosis