© 2001 by Oxford University Press
Use of Bid-ribozymes to characterize and Bid-affiliated apoptotic pathway
1 Gene Discovery Research center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-4 Higashi, Tsukuba Science City 305-8562, Japan, 2 Institute of Applied Biochemistry, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba Science City 305-8572, Japan, 3 Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Hongo, Tokyo 113-8656, Japan
Multiple cell and stimulus specific apoptosis pathways have been identified (1) revealing a complexity of molecular events involved. Tumor necrosis factor (TNF
) is known to activate mitochondria dependent or independent pathways for cell death. These pathways converge to activate effector caspases, caspases 3, 6 and 7 (2). The intermediate events including the substrates and effectors however are not clearly understood. In this report, we have employed ribozyme technology to elucidate some of these intermediate events. We show here that Bid, a pro-apoptotic facilitator that plays an important role in the mitochondrial pathway, can be targeted by Bid-specific ribozymes. MCF7 breast carcinoma cells stably transfected with expression plasmids encoding active (but not inactive or mock) Bid ribozymes showed delayed response to TNF. This was accompanied by decreased activation of caspases 7 and 9, but not of caspase 8. The data assign caspase 9 as an upstream activator of caspase 7 in TNF-induced Bid-mediated apoptosis.