TY - JOUR
T1 - The caspase-cleaved DAP5 protein supports internal ribosome entry site-mediated translation of death proteins
AU - Henis-Korenblit, Sivan
AU - Shani, Gidi
AU - Sines, Tal
AU - Marash, Lea
AU - Shohat, Galit
AU - Kimchi, Adi
PY - 2002/4/16
Y1 - 2002/4/16
N2 - Apoptosis is characterized by a translation switch from capdependent to internal ribosome entry site (IRES)-mediated protein translation. During apoptosis, several members of the eukaryotic initiation factor (eIF)4G family are cleaved specifically by caspases. Here we investigated which of the caspase-cleaved eIF4G family members could support cap-independent translation through IRES elements that retain activity in the dying cell. We focused on two major fragments arising from the cleavage of eIF4GI and death-associated protein 5 (DAP5) proteins (eIF4GI M-FAG/p76 and DAP5/p86, respectively), because they are the only potential candidates to preserve the minimal scaffold function needed to mediate translation. Transfection-based experiments in cell cultures indicated that expression of DAP5/p86 in cells stimulated protein translation from the IRESs of c-Myc, Apaf-1, DAP5, and XIAP. In contrast, these IRESs were refractory to the ectopically expressed eIF4GI M-FAG/p76. Furthermore, our study provides in vivo evidence that the caspase-mediated removal of the C-terminal tail of DAP5/p97 relieves an inhibitory effect on the protein's ability to support cap-independent translation through the DAP5 IRES. Altogether, the data suggest that DAP5 is a caspase-activated translation factor that mediates translation through a repertoire of IRES elements, supporting the translation of apoptosis-related proteins.
AB - Apoptosis is characterized by a translation switch from capdependent to internal ribosome entry site (IRES)-mediated protein translation. During apoptosis, several members of the eukaryotic initiation factor (eIF)4G family are cleaved specifically by caspases. Here we investigated which of the caspase-cleaved eIF4G family members could support cap-independent translation through IRES elements that retain activity in the dying cell. We focused on two major fragments arising from the cleavage of eIF4GI and death-associated protein 5 (DAP5) proteins (eIF4GI M-FAG/p76 and DAP5/p86, respectively), because they are the only potential candidates to preserve the minimal scaffold function needed to mediate translation. Transfection-based experiments in cell cultures indicated that expression of DAP5/p86 in cells stimulated protein translation from the IRESs of c-Myc, Apaf-1, DAP5, and XIAP. In contrast, these IRESs were refractory to the ectopically expressed eIF4GI M-FAG/p76. Furthermore, our study provides in vivo evidence that the caspase-mediated removal of the C-terminal tail of DAP5/p97 relieves an inhibitory effect on the protein's ability to support cap-independent translation through the DAP5 IRES. Altogether, the data suggest that DAP5 is a caspase-activated translation factor that mediates translation through a repertoire of IRES elements, supporting the translation of apoptosis-related proteins.
UR - http://www.scopus.com/inward/record.url?scp=0037117540&partnerID=8YFLogxK
U2 - 10.1073/pnas.082102499
DO - 10.1073/pnas.082102499
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C2 - 11943866
AN - SCOPUS:0037117540
SN - 0027-8424
VL - 99
SP - 5400
EP - 5405
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 8
ER -