Different modes of translation for hid, grim and sickle mRNAs in Drosophila.
Protein synthesis is inhibited during apoptosis. However, the translation of many mRNAs still proceeds driven by internal ribosome entry sites (IRESs). Here we show that the 5'UTR of hid and grim mRNAs promote translation of uncapped-mRNA reporters in cell-free embryonic extracts and that hid and grim mRNA 5'UTRs drive IRES-mediated translation. The translation of capped-reporters proceeds in the presence of cap competitor and in extracts where cap-dependent translation is impaired. We show that the endogenous hid and grim mRNAs are present in polysomes of heat-shocked embryos, indicating that cap recognition is not required for translation. In contrast, sickle mRNA is translated in a cap-dependent manner in all these assays. Our results show that IRES-dependent initiation may play a role in the translation of Drosophila proapoptotic genes and suggest a variety of regulatory pathways.
Vazquez-Pianzola
P
P
Max-Planck-Institut für biophysikalische Chemie, Abt. Molekulare Biologie, Am Fassberg 11, Göttingen, Germany.
Hernández
G
G
Suter
B
B
Rivera-Pomar
R
R
D020121:5' Untranslated Regions / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000166:cytology / Q000196:embryology / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D039561:Eukaryotic Initiation Factor-4E / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018869:Heat-Shock Response; D018398:Homeodomain Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D010442:Peptide Chain Initiation, Translational / Q000235:genetics; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis / Q000235:genetics*; D021381:Protein Transport; D012315:RNA Caps / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000235:genetics
D020121:5' Untranslated Regions; D029721:Drosophila Proteins; D039561:Eukaryotic Initiation Factor-4E; C108880:HID protein, Drosophila; D018398:Homeodomain Proteins; D009479:Neuropeptides; D012315:RNA Caps; D012333:RNA, Messenger; D014157:Transcription Factors; C084564:cad protein, Drosophila; C108881:grim protein, Drosophila; C452430:skl protein, Drosophila