tRNA binds to cytochrome c and inhibits caspase activation.
The specific molecular events that characterize the intrinsic apoptosis pathway have been the subject of intense research due to the pathway's fundamental role in development, homeostasis, and cancer. This pathway is defined by the release of cytochrome c from mitochondria into the cytosol and subsequent binding of cytochrome c to the caspase activator Apaf-1. Here, we report that both mitochondrial and cytosolic transfer RNA (tRNA) bind to cytochrome c. This binding prevents cytochrome c interaction with Apaf-1, blocking Apaf-1 oligomerization and caspase activation. tRNA hydrolysis in living cells and cell lysates enhances apoptosis and caspase activation, whereas microinjection of tRNA into living cells blocks apoptosis. These findings suggest that tRNA, in addition to its well-established role in gene expression, may determine cellular responsiveness to apoptotic stimuli.
Department of Cancer Biology and Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Yide
Y
Mei
Jeongsik
J
Yong
Hongtu
H
Liu
Yigong
Y
Shi
Judy
J
Meinkoth
Gideon
G
Dreyfuss
Xiaolu
X
Yang
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053477:Apoptotic Protease-Activating Factor 1 / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D061945:Caspase Inhibitors; D002417:Cattle; D002470:Cell Survival; D045304:Cytochromes c / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D004317:Doxorubicin / Q000494:pharmacology; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D019169:Jurkat Cells; D008845:Microinjections; D008928:Mitochondria / Q000201:enzymology; D011485:Protein Binding; D012331:RNA, Fungal / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012259:Ribonuclease, Pancreatic / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism; D014162:Transfection
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; D061945:Caspase Inhibitors; D012331:RNA, Fungal; D011994:Recombinant Proteins; D004317:Doxorubicin; D045304:Cytochromes c; D012343:RNA, Transfer; D012260:Ribonucleases; D012259:Ribonuclease, Pancreatic; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; C058703:ranpirnase