Apoptosis-inducing factor (AIF) inhibits protein synthesis by interacting with the eukaryotic translation initiation factor 3 subunit p44 (eIF3g).
Apoptosis-inducing factor (AIF) is a ubiquitous FAD-binding flavoprotein comprised of 613 amino acids and plays an important role in caspase-independent apoptosis. During apoptotic induction, AIF is translocated from the mitochondrial intermembrane space to the nucleus, where it interacts with DNA and activates a nuclear endonuclease. By performing a yeast two-hybrid screen with mature AIF, we have isolated the eukaryotic translation initiation factor 3 subunit p44 (eIF3g). Our deletion mutant analysis revealed that the eIF3g N-terminus interacts with the C-terminal region of AIF. The direct interaction between AIF and eIF3g was confirmed in a GST pull-down assay and also verified by the results of co-immunoprecipitation and confocal microscopy studies. Using an in vitro TNT coupled transcription-translation system, we found that mature AIF could inhibit newly-translated protein synthesis and this inhibition was significantly blocked by eIF3g competitively. These results were also confirmed in cells. In addition, mature AIF overexpression specifically resulted in the activation of caspase-7, thereby amplifying the inhibition of protein synthesis including eIF3g cleavage. Our data suggest that eIF3g is one of the cytosolic targets that interacts with mature AIF, and provide insight into the AIF's cellular functions of the inhibition of protein synthesis during apoptosis.
Kim
Jong-Tae
JT
Department of Biological Sciences, Research Center for Women's Diseases, Sookmyung Women's University, Chungpa-Dong, Yongsan-Gu, Seoul 140-742, Republic of Korea.
Kim
Kwang Dong
KD
Song
Eun Young
EY
Lee
Hee Gu
HG
Kim
Jae Wha
JW
Kim
Jung Woo
JW
Chae
Suhn-Kee
SK
Kim
Eunhee
E
Lee
Myeong-Sok
MS
Yang
Young
Y
Lim
Jong-Seok
JS
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D017209:Apoptosis / Q000502:physiology*; D051033:Apoptosis Inducing Factor / Q000235:genetics / Q000378:metabolism*; D053179:Caspase 7 / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D002474:Cell-Free System / Q000378:metabolism; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism; D039621:Eukaryotic Initiation Factor-3 / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D014176:Protein Biosynthesis / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000235:genetics
C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; D039621:Eukaryotic Initiation Factor-3; D009687:Nuclear Proteins; D004720:Endonucleases; D053179:Caspase 7