Abstract
Rapamycin inhibits the activity of the target of rapamycin (TOR)-dependent signaling pathway, which has been characterized as one dedicated to translational regulation through modulating cap-dependent translation, involving eIF4E binding protein (eIF4E-BP) or 4E-BP. Results show that rapamycin strongly inhibits global translation in Drosophila cells. However, Hsp70 mRNA translation is virtually unaffected by rapamycin treatment, whereas Hsp90 mRNA translation is strongly inhibited, at normal growth temperature. Intriguingly, during heat shock Hsp90 mRNA becomes significantly less sensitive to rapamycin-mediated inhibition, suggesting the pathway for Hsp90 mRNA translation is altered during heat shock. Reporter mRNAs containing the Hsp90 or Hsp70 mRNAs’ 5′ untranslated region recapitulate these rapamycin-dependent translational characteristics, indicating this region regulates rapamycin-dependent translational sensitivity as well as heat shock preferential translation. Surprisingly, rapamycin-mediated inhibition of Hsp90 mRNA translation at normal growth temperature is not caused by 4E-BP-mediated inhibition of cap-dependent translation. Indeed, no evidence for rapamycin-mediated impaired eIF4E function is observed. These results support the proposal that preferential translation of different Hsp mRNA utilizes distinct translation mechanisms, even within a single species.
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Abbreviations
- TOR:
-
Target of rapamycin
- S6K:
-
ribosomal protein S6 kinase
- PI3K:
-
phosphatidyl inositol 3-kinase
- eIF:
-
eukaryotic initiation factor
- 4E-BP:
-
eIF4E binding protein (eIF4E-BP)
- 5′UTR:
-
5′ untranslated region of mRNA
- FBS:
-
fetal bovine serum
- SM:
-
Schneider's medium
- EBSS:
-
Earle's buffered salt solution
- PABP or dmPABP:
-
poly(A)-binding protein (from Drosophila melanogaster)
- “d” prefix precedingmolecular designations:
-
Drosophila forms of the enzymes
References
Ahmed R, Duncan RF (2004) Translational Regulation of Hsp90 mRNA: AUG-proximal 5’¢ untranslated region elements essential for preferential heart shock translation. J Biol Chem 279:49919–49930
Barbet NC, Schneider U, Helliwell SB, Stansfield I, Tuite MF, Hall MN (1996) TOR controls translation initiation and early G1 progression in yeast. Mole Biol Cell 7:25–42
Beretta L, Gingras A-C, Svitkin YV, Hall MN, Sonenberg N (1996) Rapamycin blocks the phosphorylation of 4E-BP1 and inhibits cap-dependent initiation of translation. EMBO J 15:658–664
Borman AM, Michel YM, Malnou CE, Kean KM (2002) Free poly(A) stimulates capped mRNA translation in vitro through the eIF4G-poly(A)-binding protein interaction. J Biol Chem 277:36818–36824
Brown EJ, Schreiber SL (1996) A signaling pathway to translational control. Cell 86:517–520
Cotto JJ, Morimoto RI (1999) Stress-induced activation of the heat-shock response: cell and molecular biology of heat-shock factors. Biochem Soc Symp 64:105–118
De Benedetti A, Joshi-Barve S, Rinker-Schaeffer C, Rhoads RE (1991) Expression of antisense RNA against initiation factor eIF-4E mRNA in HeLa cells results in lengthened cell division times, diminished translation rates, and reduced levels of both eIF-4E and the p220 component of eIF-4F. Mol Cell Biol 11:5435–5445
Duncan RF (1995) Cordycepin blocks recovery of non-heat shock mRNA translation following heat shock in Drosophila. Eur J Biochem 233:784–792
Duncan RF (1996) Translational control during heat shock. In: Hershey JWB, Mathews M, Sonenberg N (eds) Translational control. Cold Spring Harbor Laboratory Press, New York
Duncan R, Hershey JWB (1984a) Heat-shock induced translational alterations in HeLa cells: initiation factor modifications and the inhibition of translation. J Biol Chem 259:11882–11889
Duncan R, Hershey JWB (1984b) Evaluation of isoelectric focusing running conditions during two-dimensional isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis: variation of gel patterns with changing conditions and optimized isoelectric focusing conditions. Anal Biochem 138:144–155
Duncan RF, Song HJ (1999) Striking multiplicity of eIF4E-BP1 phosphorylated isoforms identified by 2D gel electrophoresis regulation by heat shock. Eur J Biochem 265:728–743
Duncan R, Milburn SC, Hershey JWB (1987) Regulated phosphorylation and low abundance of HeLa cell initiation factor eIF-4F suggest a role in translational control. J Biol Chem 262:380–388
Fadden P, Haystead TA, Lawrence JC Jr (1997) Identification of phosphorylation sites in the translational regulator, PHAS-I, that are controlled by insulin and rapamycin in rat adipocytes. J Biol Chem 272:10240–10247
Gabai VL, Sherman MY (2002) Interplay between molecular chaperones and signaling pathways in survival of heat shock. J Appl Physiol 92:1743–1748
Gingras AC, Gygi SP, Raught B, Polakiewicz RD, Abraham RT, Hoekstra MF, Aebersold R, Sonenberg N (1999) Regulation of 4E-BP1 phosphorylation: a novel two-step mechanism. Genes Dev 13:1422–1437
Gingras AC, Raught B, Sonenberg N (2001a) Regulation of translation initiation by FRAP/mTOR. Genes Dev 15:807–826
Gingras AC, Raught B, Gygi SP, Niedzwiecka A, Miron M, Burley SK, Polakiewicz RD, Wyslouch-Cieszynska A, Aebersold R, Sonenberg N (2001b) Hierarchical phosphorylation of the translation inhibitor 4E-BP1. Genes Dev 15:2852–2864
Gross JD, Moerke NJ, von der Haar T, Lugovskoy AA, Sachs AB, McCarthy JE, Wagner G (2003) Ribosome loading onto the mRNA cap is driven by conformational coupling between eIF4G and eIF4E. Cell 115:739–750
Haghihat A, Sonenberg N (1997) eIF4G dramatically enhances the binding of eIF4E to the mRNA 5’¢-cap structure. J Biol Chem 272:21677–21680
Harris TE, Chi A, Shabanowitz J, Hunt DF, Rhoads RE, Lawrence JC Jr (2006) mTOR-dependent stimulation of the association of eIF4G and eIF3 by insulin. EMBO J 25:1659–1668
Hess MA, Duncan RF (1996) Sequence and structure determinants of Drosophila Hsp70 mRNA translation: 5’¢-UTR secondary structure specifically inhibits heat shock protein mRNA translation. Nucleic Acids Res 24:2441–2449
Holz MK, Ballif BA, Gygi SP, Blenis J (2005) mTOR and S6K1 mediate assembly of the translation preinitiation complex through dynamic protein interchange and ordered phosphorylation events. Cell 123:569–580
Hultmark D, Klemenz R, Gehring WJ (1986) Translational and transcriptional control elements in the untranslated leader of the heat-shock gene hsp22. Cell 44:429–438
Ireland RC, Berger E, Sirotkin K, Yund MA, Osterbur D, Fristrom J (1982) Ecdysterone induces the transcription of four heat-shock genes in Drosophila S3 cells and imaginal discs. Dev Biol 93:498–507
Lamphear BJ, Panniers R (1991) Heat shock impairs the interaction of cap-binding protein complex with 5’¢ mRNA cap. J Biol Chem 266:2789–2794
Lefrere V, Duncan RF (1994) Heat shock-induced repression of proteolysis:poly(A)-binding protein degradation patterns can illusorily suggest its specific loss during heat shock. Nucleic Acids Res 22:1640–1642
Li D, Duncan RF (1995) Rapid turnover of heat shock protein 70 in Drosophila: stabilization during heat shock, and consequent effects on accumulation. Eur J Biochem 231:454–465
Lindquist S (1980a) Varying patterns of protein synthesis in Drosophila during heat shock: implications for regulation. Dev Biol 77:463–479
Lindquist S (1980b) Translational efficiency of heat-induced messages in Drosophila melanogaster cells. J Mol Biol 137:151–158
Lindquist S (1986) The heat -shock response. Ann Rev Biochem 55:1151–1191
Lindquist S, Petersen R (1990) Selective translation and degradation of heat-shock messenger RNAs in Drosophila. Enzyme 44:147–166
McGarry TJ, Lindquist S (1985) The preferential translation of Drosophila hsp70 mRNA requires sequences in the untranslated leader. Cell 42:903–911
Miron M, Verdu J, Lachance PE, Birnbaum MJ, Lasko PF, Sonenberg N (2001) The translational inhibitor 4E-BP is an effector of PI(3)K/Akt signalling and cell growth in Drosophila. Nat Cell Biol 3:596–601
Miron M, Lasko PF, Sonenberg N (2003) Signaling from Akt to FRAP/TOR targets both 4E-BP and S6K in Drosophila melanogaster. Mol Cell Biol 23:9117–9126
Morley SJ, Naegele S (2002) Phosphorylation of initiation factor (eIF) 4E is not required for de novo protein synthesis following recovery from hypertonic stress in human kidney cells. J Biol Chem 277:32855–32859
O’Farrell PH (1975) High resolution two-dimensional electrophoresis of proteins. J Biol Chem 250:4007–4021
Panniers R, Stewart EB, Merrick WC, Henshaw EC (1985) Mechanism of inhibition of polypeptide chain initiation in heat-shocked Ehrlich cells involves reduction of eukaryotic initiation factor 4F activity. J Biol Chem 260:9648–9653
Parsell DA, Lindquist S (1993) The function of heat -shock proteins in stress tolerance: degradation and reactivation of damaged proteins. Annu Rev Genet 27:437–496
Raught B, Gingras AC, Gygi SP, Imataka H, Morino S, Gradi A, Aebersold R, Sonenberg N (2000) Serum-stimulated, rapamycin-sensitive phosphorylation sites in the eukaryotic translation initiation factor 4GI. EMBO J 19:434–444
Raught B, Peiretti F, Gingras A-C, Livingstone M, Shahbazian D, Mayeur GL, Polakiewicz RD, Sonenberg N, Hershey JWB (2004) Phosphorylation of eucaryotic translation initiation factor 4B Ser422 is modulated by S6 kinases. EMBO J 23:1761–1769
Rhoads RE, Lamphear BJ (1995) Cap-independent translation of heat shock messenger RNAs. Curr Top Microbiol Immunol 203:131–153
Ritossa FM (1962) A new puffing pattern induced by temperature shock and DNP in Drosophila. Experientia 18:571–573
Song H-J, Gallie DR, Duncan RF (1995) m7GpppG cap dependence for efficient translation of Drosophila HSP70 mRNA. Eur J Biochem 232:778–788
Storti RV, Scott MP, Rich A, Pardue ML (1980) Translational control of protein synthesis in response to heat shock in D. melanogaster cells. Cell 22:825–834
Tarun SZ Jr., Sachs AB (1996) Association of the yeast poly(A) tail binding protein with translation initiation factor eIF-4G. EMBO J 15:7168–7177
Tissieres A, Mitchell HK, Tracy WM (1974) Protein synthesis in salivary glands of Drosophila melanogaster: relation to chromosome puffs. J Mol Biol 84:389–398
Yueh A, Schneider RJ (2000) Translation by ribosome shunting on adenovirus and hsp70 mRNAs facilitated by complementarity to 18S rRNA. Genes Dev 14:414–421
Zapata JM, Maroto FG, Sierra JM (1991) Inactivation of mRNA cap-binding protein complex in Drosophila melanogaster embryos under heat shock. J Biol Chem 266:16007–16014
Zapata JM, Martinez MA, Sierra JM (1994) Purification and characterization of eukaryotic polypeptide chain initiation factor 4F from Drosophila melanogaster embryos. J Biol Chem 269:18047–18052
Acknowledgements
This research was supported by NSF grant MCB-9728753. We thank Drs. N. Sonenberg, M. Miron, and J. Sierra for providing antisera to Drosophila eIF4E, 4E-BP, and eIF4G. We thank Dr. A. Vincent for providing antisera to Drosophila PABP. We thank Dr. R. Ahmed for the preparation of the plasmid vectors.
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Duncan, R.F. Rapamycin conditionally inhibits Hsp90 but not Hsp70 mRNA translation in Drosophila: implications for the mechanisms of Hsp mRNA translation. Cell Stress and Chaperones 13, 143–155 (2008). https://doi.org/10.1007/s12192-008-0024-6
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DOI: https://doi.org/10.1007/s12192-008-0024-6
Keywords
- Translation
- Heat shock
- Rapamycin
- Hsp90
- Hsp70