1
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Robert F, Cencic R, Cai R, Schmeing TM, Pelletier J. RNA-tethering assay and eIF4G:eIF4A obligate dimer design uncovers multiple eIF4F functional complexes. Nucleic Acids Res 2020; 48:8562-8575. [PMID: 32749456 PMCID: PMC7470955 DOI: 10.1093/nar/gkaa646] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 07/05/2020] [Accepted: 07/30/2020] [Indexed: 12/11/2022] Open
Abstract
Eukaryotic cellular mRNAs possess a 5′ cap structure (m7GpppN) which plays a critical role in translation initiation mediated by eukaryotic initiation factor (eIF) 4F. The heterotrimeric eIF4F complex possesses several activities imparted by its subunits that include cap recognition (by eIF4E), RNA unwinding (eIF4A), and factor/ribosome recruitment (eIF4G). Mammalian cells have paralogs of all three eIF4F subunits and it remains an open question as to whether these all can participate in the process of ribosome recruitment. To query the activities of the eIF4F subunits in translation initiation, we adopted an RNA-tethering assay in which select subunits are recruited to a specific address on a reporter mRNA template. We find that all eIF4F subunits can participate in the initiation process. Based on eIF4G:eIF4A structural information, we also designed obligate dimer pairs to probe the activity of all combinations of eIF4G and eIF4A paralogs. We demonstrate that both eIF4GI and eIF4GII can associate with either eIF4A1 or eIF4A2 to recruit ribosomes to mRNA templates. In combination with eIF4E and eIF4E3, our results indicate the presence of up to eight eIF4F complexes that can operate in translation initiation.
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Affiliation(s)
- Francis Robert
- Department of Biochemistry, McGill University, Montreal, Canada
| | - Regina Cencic
- Department of Biochemistry, McGill University, Montreal, Canada
| | - Renying Cai
- Department of Biochemistry, McGill University, Montreal, Canada
| | | | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Canada.,Department of Oncology.,Rosalind & Morris Goodman Cancer Research Centre, McGill University, Montreal, Canada
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2
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Naineni SK, Itoua Maïga R, Cencic R, Putnam AA, Amador LA, Rodriguez AD, Jankowsky E, Pelletier J. A comparative study of small molecules targeting eIF4A. RNA (NEW YORK, N.Y.) 2020; 26:541-549. [PMID: 32014999 PMCID: PMC7161356 DOI: 10.1261/rna.072884.119] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 01/30/2020] [Indexed: 05/13/2023]
Abstract
The PI3K/Akt/mTOR kinase pathway is extensively deregulated in human cancers. One critical node under regulation of this signaling axis is eukaryotic initiation factor (eIF) 4F, a complex involved in the control of translation initiation rates. eIF4F-dependent addictions arise during tumor initiation and maintenance due to increased eIF4F activity-generally in response to elevated PI3K/Akt/mTOR signaling flux. There is thus much interest in exploring eIF4F as a small molecule target for the development of new anticancer drugs. The DEAD-box RNA helicase, eIF4A, is an essential subunit of eIF4F, and several potent small molecules (rocaglates, hippuristanol, pateamine A) affecting its activity have been identified and shown to demonstrate anticancer activity in vitro and in vivo in preclinical models. Recently, a number of new small molecules have been reported as having the capacity to target and inhibit eIF4A. Here, we undertook a comparative analysis of their biological activity and specificity relative to the eIF4A inhibitor, hippuristanol.
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Affiliation(s)
- Sai Kiran Naineni
- Department of Biochemistry, McGill University, Montreal, Québec H3G 1Y6, Canada
| | - Rayelle Itoua Maïga
- Department of Biochemistry, McGill University, Montreal, Québec H3G 1Y6, Canada
| | - Regina Cencic
- Department of Biochemistry, McGill University, Montreal, Québec H3G 1Y6, Canada
| | - Andrea A Putnam
- School of Medicine, Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Luis A Amador
- Department of Chemistry, Faculty of Natural Sciences, University of Puerto Rico, San Juan, 00931-3346, Puerto Rico
| | - Abimael D Rodriguez
- Department of Chemistry, Faculty of Natural Sciences, University of Puerto Rico, San Juan, 00931-3346, Puerto Rico
| | - Eckhard Jankowsky
- School of Medicine, Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Québec H3G 1Y6, Canada
- Department of Oncology, McGill University, Montreal, Québec H4A 3T2, Canada
- Rosalind & Morris Goodman Cancer Research Centre, McGill University, Montreal, Québec H3A 1A3, Canada
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3
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Link AJ, Niu X, Weaver CM, Jennings JL, Duncan DT, McAfee KJ, Sammons M, Gerbasi VR, Farley AR, Fleischer TC, Browne CM, Samir P, Galassie A, Boone B. Targeted Identification of Protein Interactions in Eukaryotic mRNA Translation. Proteomics 2020; 20:e1900177. [PMID: 32027465 DOI: 10.1002/pmic.201900177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 12/13/2019] [Indexed: 11/09/2022]
Abstract
To identify protein-protein interactions and phosphorylated amino acid sites in eukaryotic mRNA translation, replicate TAP-MudPIT and control experiments are performed targeting Saccharomyces cerevisiae genes previously implicated in eukaryotic mRNA translation by their genetic and/or functional roles in translation initiation, elongation, termination, or interactions with ribosomal complexes. Replicate tandem affinity purifications of each targeted yeast TAP-tagged mRNA translation protein coupled with multidimensional liquid chromatography and tandem mass spectrometry analysis are used to identify and quantify copurifying proteins. To improve sensitivity and minimize spurious, nonspecific interactions, a novel cross-validation approach is employed to identify the most statistically significant protein-protein interactions. Using experimental and computational strategies discussed herein, the previously described protein composition of the canonical eukaryotic mRNA translation initiation, elongation, and termination complexes is calculated. In addition, statistically significant unpublished protein interactions and phosphorylation sites for S. cerevisiae's mRNA translation proteins and complexes are identified.
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Affiliation(s)
- Andrew J Link
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.,Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA.,Department of Chemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Xinnan Niu
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Connie M Weaver
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Jennifer L Jennings
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Dexter T Duncan
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - K Jill McAfee
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Morgan Sammons
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, 37232, USA
| | - Vince R Gerbasi
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Adam R Farley
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Tracey C Fleischer
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | | | - Parimal Samir
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Allison Galassie
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37232, USA
| | - Braden Boone
- Department of Bioinformatics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
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4
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Steele AD, Teijaro CN, Yang D, Shen B. Leveraging a large microbial strain collection for natural product discovery. J Biol Chem 2019; 294:16567-16576. [PMID: 31570525 DOI: 10.1074/jbc.rev119.006514] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Throughout history, natural products have significantly contributed to the discovery of novel chemistry, drug leads, and tool molecules to probe and address complex challenges in biology and medicine. Recent microbial genome sequencing efforts have uncovered many microbial biosynthetic gene clusters without an associated natural product. This means that the natural products isolated to date do not fully reflect the biosynthetic potential of microbial strains. This observation has rejuvenated the natural product community and inspired a return to microbial strain collections. Mining large microbial strain collections with the most current technologies in genome sequencing, bioinformatics, and high-throughput screening techniques presents new opportunities in natural product discovery. In this review, we report on the newly expanded microbial strain collection at The Scripps Research Institute, which represents one of the largest and most diverse strain collections in the world. Two complementary approaches, i.e. structure-centric and function-centric, are presented here to showcase how to leverage a large microbial strain collection for natural product discovery and to address challenges and harness opportunities for future efforts. Highlighted examples include the discovery of alternative producers of known natural products with superior growth characteristics and high titers, novel analogs of privileged scaffolds, novel natural products, and new activities of known and new natural products. We anticipate that this large microbial strain collection will facilitate the discovery of new natural products for many applications.
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Affiliation(s)
- Andrew D Steele
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458
| | | | - Dong Yang
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458.,Natural Products Library Initiative, The Scripps Research Institute, Jupiter, Florida 33458
| | - Ben Shen
- Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458 .,Natural Products Library Initiative, The Scripps Research Institute, Jupiter, Florida 33458.,Department of Molecular Medicine, The Scripps Research Institute, Jupiter, Florida 33458
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5
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Carvalho A, Chu J, Meinguet C, Kiss R, Vandenbussche G, Masereel B, Wouters J, Kornienko A, Pelletier J, Mathieu V. A harmine-derived beta-carboline displays anti-cancer effects in vitro by targeting protein synthesis. Eur J Pharmacol 2017; 805:25-35. [PMID: 28322844 DOI: 10.1016/j.ejphar.2017.03.034] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 03/13/2017] [Accepted: 03/15/2017] [Indexed: 12/17/2022]
Abstract
Growing evidence indicates that protein synthesis is deregulated in cancer onset and progression and targeting this process might be a selective way to combat cancers. While harmine is known to inhibit DYRK1A and intercalate into the DNA, tri-substitution was shown previously to modify its activity profile in favor of protein synthesis inhibition. In this study, we thus evaluated the optimized derivative CM16 in vitro anti-cancer effects unfolding its protein synthesis inhibition activity. Indeed, the growth inhibitory profile of CM16 in the NCI 60-cancer-cell-line-panel correlated with those of other compounds described as protein synthesis inhibitors. Accordingly, CM16 decreased in a time- and concentration-dependent manner the translation of neosynthesized proteins in vitro while it did not affect mRNA transcription. CM16 rapidly penetrated into the cell in the perinuclear region of the endoplasmic reticulum where it appears to target translation initiation as highlighted by ribosomal disorganization. More precisely, we found that the mRNA expression levels of the initiation factors EIF1AX, EIF3E and EIF3H differ when comparing resistant or sensitive cell models to CM16. Additionally, CM16 induced eIF2α phosphorylation. Those effects could explain, at least partly, the CM16 cytostatic anti-cancer effects observed in vitro while neither cell cycle arrest nor DNA intercalation could be demonstrated. Therefore, targeting protein synthesis initiation with CM16 could represent a new promising alternative to current cancer therapies due to the specific alterations of the translation machinery in cancer cells as recently evidenced with respect to EIF1AX and eIF3 complex, the potential targets identified in this present study.
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Affiliation(s)
- Annelise Carvalho
- Laboratoire de Cancérologie et Toxicologie Expérimentale, Faculté de Pharmacie, Université Libre de Bruxelles, Brussels, Belgium
| | - Jennifer Chu
- Department of Biochemistry, McGill University, Montreal, Québec, Canada
| | - Céline Meinguet
- Namur Medicine and Drug Innovation Center (NAMEDIC-NARILIS), Université de Namur, Namur, Belgium
| | - Robert Kiss
- Laboratoire de Cancérologie et Toxicologie Expérimentale, Faculté de Pharmacie, Université Libre de Bruxelles, Brussels, Belgium
| | - Guy Vandenbussche
- Laboratory for the Structure and Function of Biological Membranes, Faculté des Sciences, Université Libre de Bruxelles, Brussels, Belgium
| | - Bernard Masereel
- Namur Medicine and Drug Innovation Center (NAMEDIC-NARILIS), Université de Namur, Namur, Belgium
| | - Johan Wouters
- Namur Medicine and Drug Innovation Center (NAMEDIC-NARILIS), Université de Namur, Namur, Belgium
| | - Alexander Kornienko
- Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Québec, Canada
| | - Véronique Mathieu
- Laboratoire de Cancérologie et Toxicologie Expérimentale, Faculté de Pharmacie, Université Libre de Bruxelles, Brussels, Belgium.
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6
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Henry S, Kidner R, Reisenauer MR, Magedov IV, Kiss R, Mathieu V, Lefranc F, Dasari R, Evidente A, Yu X, Ma X, Pertsemlidis A, Cencic R, Pelletier J, Cavazos DA, Brenner AJ, Aksenov AV, Rogelj S, Kornienko A, Frolova LV. 5,10b-Ethanophenanthridine amaryllidaceae alkaloids inspire the discovery of novel bicyclic ring systems with activity against drug resistant cancer cells. Eur J Med Chem 2016; 120:313-28. [PMID: 27218860 PMCID: PMC4943583 DOI: 10.1016/j.ejmech.2016.05.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 05/01/2016] [Accepted: 05/02/2016] [Indexed: 12/13/2022]
Abstract
Plants of the Amaryllidaceae family produce a large variety of alkaloids and non-basic secondary metabolites, many of which are investigated for their promising anticancer activities. Of these, crinine-type alkaloids based on the 5,10b-ethanophenanthridine ring system were recently shown to be effective at inhibiting proliferation of cancer cells resistant to various pro-apoptotic stimuli and representing tumors with dismal prognoses refractory to current chemotherapy, such as glioma, melanoma, non-small-cell lung, esophageal, head and neck cancers, among others. Using this discovery as a starting point and taking advantage of a concise biomimetic route to the crinine skeleton, a collection of crinine analogues were synthetically prepared and evaluated against cancer cells. The compounds exhibited single-digit micromolar activities and retained this activity in a variety of drug-resistant cancer cell cultures. This investigation resulted in the discovery of new bicyclic ring systems with significant potential in the development of effective clinical cancer drugs capable of overcoming cancer chemotherapy resistance.
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Affiliation(s)
- Sean Henry
- Departments of Chemistry and Biology, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA
| | - Ria Kidner
- Departments of Chemistry and Biology, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA
| | - Mary R Reisenauer
- Departments of Chemistry and Biology, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA
| | - Igor V Magedov
- Departments of Chemistry and Biology, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA
| | - Robert Kiss
- Laboratoire de Cancérologie et de Toxicologie Expérimentale, Faculté de Pharmacie, Université Libre de Bruxelles (ULB), Campus de la Plaine, CP205/1, Boulevard du Triomphe, Brussels, Belgium
| | - Véronique Mathieu
- Laboratoire de Cancérologie et de Toxicologie Expérimentale, Faculté de Pharmacie, Université Libre de Bruxelles (ULB), Campus de la Plaine, CP205/1, Boulevard du Triomphe, Brussels, Belgium
| | - Florence Lefranc
- Service de Neurochirurgie, Hôpital Erasme, ULB, 808 route de Lennik, 1070 Brussels, Belgium
| | - Ramesh Dasari
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
| | - Antonio Evidente
- Dipartimento di Scienze Chimiche, Universita' di Napoli Federico II, Complesso Universitario Monte Sant'Angelo, Via Cintia 4, 80126 Napoli, Italy
| | - Xiaojie Yu
- Greehey Children's Cancer Research Institute, UT Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Xiuye Ma
- Greehey Children's Cancer Research Institute, UT Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Alexander Pertsemlidis
- Greehey Children's Cancer Research Institute, UT Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Regina Cencic
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada
| | - David A Cavazos
- Cancer Therapy and Research Center, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Andrew J Brenner
- Cancer Therapy and Research Center, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Alexander V Aksenov
- Department of Chemistry, North Caucasus University, 1a Pushkin St., Stavropol 355009, Russian Federation
| | - Snezna Rogelj
- Departments of Chemistry and Biology, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA
| | - Alexander Kornienko
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA.
| | - Liliya V Frolova
- Departments of Chemistry and Biology, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA.
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7
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Royall E, Doyle N, Abdul-Wahab A, Emmott E, Morley SJ, Goodfellow I, Roberts LO, Locker N. Murine norovirus 1 (MNV1) replication induces translational control of the host by regulating eIF4E activity during infection. J Biol Chem 2015; 290:4748-4758. [PMID: 25561727 PMCID: PMC4335213 DOI: 10.1074/jbc.m114.602649] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Protein synthesis is a tightly controlled process responding to several stimuli, including viral infection. As obligate intracellular parasites, viruses depend on the translation machinery of the host and can manipulate it by affecting the availability and function of specific eukaryotic initiation factors (eIFs). Human norovirus is a member of the Caliciviridae family and is responsible for gastroenteritis outbreaks. Previous studies on feline calicivirus and murine norovirus 1 (MNV1) demonstrated that the viral protein, genome-linked (VPg), acts to direct translation by hijacking the host protein synthesis machinery. Here we report that MNV1 infection modulates the MAPK pathway to activate eIF4E phosphorylation. Our results show that the activation of p38 and Mnk during MNV1 infection is important for MNV1 replication. Furthermore, phosphorylated eIF4E relocates to the polysomes, and this contributes to changes in the translational state of specific host mRNAs. We propose that global translational control of the host by eIF4E phosphorylation is a key component of the host-pathogen interaction.
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Affiliation(s)
- Elizabeth Royall
- University of Surrey, Faculty of Health and Medical Sciences, School of Biosciences and Medicine, Guildford GU2 7HX, United Kingdom
| | - Nicole Doyle
- University of Surrey, Faculty of Health and Medical Sciences, School of Biosciences and Medicine, Guildford GU2 7HX, United Kingdom
| | - Azimah Abdul-Wahab
- University of Surrey, Faculty of Health and Medical Sciences, School of Biosciences and Medicine, Guildford GU2 7HX, United Kingdom
| | - Ed Emmott
- Division of Virology, Department of Pathology, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, United Kingdom
| | - Simon J Morley
- Department of Biochemistry and Molecular Biology, School of Life Sciences, University of Sussex, JMS Building, Brighton BN1 9RH, United Kingdom
| | - Ian Goodfellow
- Division of Virology, Department of Pathology, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, United Kingdom
| | - Lisa O Roberts
- University of Surrey, Faculty of Health and Medical Sciences, School of Biosciences and Medicine, Guildford GU2 7HX, United Kingdom
| | - Nicolas Locker
- University of Surrey, Faculty of Health and Medical Sciences, School of Biosciences and Medicine, Guildford GU2 7HX, United Kingdom.
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8
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Wang QS, Au HHT, Jan E. Methods for studying IRES-mediated translation of positive-strand RNA viruses. Methods 2012; 59:167-79. [PMID: 23009811 DOI: 10.1016/j.ymeth.2012.09.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 06/25/2012] [Accepted: 09/13/2012] [Indexed: 02/05/2023] Open
Abstract
Internal ribosome entry sites are RNA elements that mediate translation in a cap-independent manner. A subset of positive strand RNA viruses utilize an IRES mechanism as a viral strategy to ensure efficient viral protein synthesis. IRES elements vary in sequence, structure, and factor requirements between virus families. Here, we describe methods to determine IRES activity and approaches to study the regulation and function of IRES-mediated translation both in vitro and in vivo. Finally, we describe a new IRES-directed reporter system which exploits the 2A 'self-cleavage' or 'stop-go' peptide for optimal detection of IRES activity.
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Affiliation(s)
- Qing S Wang
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
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9
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Galicia-Vázquez G, Cencic R, Robert F, Agenor AQ, Pelletier J. A cellular response linking eIF4AI activity to eIF4AII transcription. RNA (NEW YORK, N.Y.) 2012; 18:1373-84. [PMID: 22589333 PMCID: PMC3383968 DOI: 10.1261/rna.033209.112] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Accepted: 04/05/2012] [Indexed: 05/18/2023]
Abstract
The recruitment of ribosomes to eukaryotic cellular mRNAs requires the activity of two prototypic RNA helicases, eukaryotic initiation factor (eIF) 4AI and eIF4AII. The eIF4A isoforms are highly conserved, are thought to be functionally interchangeable, and are directed to the 5' m(7)GpppN cap structure of mRNAs during translation initiation by virtue of their assembly into eIF4F, a heterotrimeric complex that also harbors the eIF4E cap binding protein and eIF4G scaffolding unit. During the course of RNA interference experiments aimed at investigating the respective roles of eIF4AI and eIF4AII in translation, we uncovered a cellular response pathway whereby suppression of eIF4AI increases transcription of the eIF4AII gene, leading to elevated eIF4AII mRNA and protein levels. Inhibition of eIF4AI suppresses protein synthesis, and although eIF4AII protein levels increase above and beyond what should be sufficient to compensate for the decrease in eIF4AI levels, there is no corresponding rescue of translation or of the block on cellular proliferation that occurs upon eIF4AI suppression. These results were phenocopied using the small molecule eIF4A inhibitor hippuristanol. Taken together, our results indicate that eIF4AI and eIF4AII expression appear linked and that the two protein isoforms exhibit functional differences.
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Affiliation(s)
| | | | | | | | - Jerry Pelletier
- Department of Biochemistry and
- The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Quebec, Canada, H3G 1Y6
- Corresponding authorE-mail
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10
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Cencic R, Galicia-Vázquez G, Pelletier J. Inhibitors of translation targeting eukaryotic translation initiation factor 4A. Methods Enzymol 2012; 511:437-61. [PMID: 22713332 DOI: 10.1016/b978-0-12-396546-2.00020-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The RNA helicases eIF4AI and eIF4AII play key roles in recruiting ribosomes to mRNA templates during eukaryotic translation initiation. Small molecule inhibitors of eIF4AI and eIF4AII have been useful for chemically dissecting their role in translation in vitro and in vivo. Here, we describe a screen performed on a small focused library of kinase inhibitors to identify a novel helicase inhibitor. We describe assays that have been critical for characterizing novel RNA helicase inhibitors.
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Affiliation(s)
- Regina Cencic
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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11
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Cycloheximide and congeners as inhibitors of eukaryotic protein synthesis from endophytic actinomycetes Streptomyces sps. YIM56132 and YIM56141. J Antibiot (Tokyo) 2010; 64:163-6. [PMID: 21139626 DOI: 10.1038/ja.2010.150] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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12
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Sadovski O, Jaikaran ASI, Samanta S, Fabian MR, Dowling RJO, Sonenberg N, Woolley GA. A collection of caged compounds for probing roles of local translation in neurobiology. Bioorg Med Chem 2010; 18:7746-52. [PMID: 20427189 DOI: 10.1016/j.bmc.2010.04.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 03/25/2010] [Accepted: 04/01/2010] [Indexed: 01/01/2023]
Abstract
Spatially localized translation plays a vital role in the normal functioning of neuronal systems and is widely believed to be involved in both learning and memory formation. It is of central interest to understand both the phenomenon and molecular mechanisms of local translation using new tools and approaches. Caged compounds can, in principle, be used as tools to investigate local translation since optical activation of bioactive molecules can achieve both spatial and temporal resolution on the micron scale and on the order of seconds or less, respectively. Successful caging of bioactive molecules requires the identification of key functional groups in appropriate molecules and the introduction of a suitable caging moiety. Here we present the design, synthesis and testing of a collection of three caged compounds: anisomycin caged with a diethylaminocoumarin moiety and dimethoxynitrobenzyl caged versions of 4E-BP and rapamycin. Whereas caged anisomycin can be used to control general translation, caged 4E-BP serves as a probe of cap-dependent translation initiation and caged rapamycin serves a probe of the role of mTORC1 in translation initiation. In vitro translation assays demonstrate that these caging strategies, in combination with the aforementioned compounds, are effective for optical control making it likely that such strategies can successfully employed in the study of local translation in living systems.
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Affiliation(s)
- Oleg Sadovski
- Department of Chemistry, University of Toronto, 80 St. George ST., Toronto, ON, Canada M5S 3H6
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13
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Robert F, Williams C, Yan Y, Donohue E, Cencic R, Burley SK, Pelletier J. Blocking UV-induced eIF2alpha phosphorylation with small molecule inhibitors of GCN2. Chem Biol Drug Des 2009; 74:57-67. [PMID: 19519745 DOI: 10.1111/j.1747-0285.2009.00827.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The eIF2alpha kinase general control non-depressible 2 integrates translation initiation rates to amino acid availability. General control non-depressible 2 also regulates translation initiation during synaptic plasticity and GCN2(-/-) mice show improved memory compared with wild-type mice with a reduced threshold for triggering late long-term potentiation. This property suggests that inhibiting general control non-depressible 2 function might represent a therapeutic avenue for improving memory. We screened for general control non-depressible 2 inhibitors using a small library of known kinase inhibitors and ATP-analogs and identified three compounds--indirubin-3'-monoxime, SP600125 and a SyK inhibitor with activity against general control non-depressible 2. All three compounds inhibit the ability of general control non-depressible 2 to phosphorylate eIF2alphain vitro as well as in vivo following UV-treatment of mouse embryonic fibroblasts. Using computer-assisted modeling, we modeled the binding of the inhibitors in the ATP-binding site of general control non-depressible 2. This work provides the molecular basis for undertaking structure-activity relationships of these compounds in order to develop specific inhibitors of general control non-depressible 2.
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Affiliation(s)
- Francis Robert
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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Mokas S, Mills JR, Garreau C, Fournier MJ, Robert F, Arya P, Kaufman RJ, Pelletier J, Mazroui R. Uncoupling stress granule assembly and translation initiation inhibition. Mol Biol Cell 2009; 20:2673-83. [PMID: 19369421 DOI: 10.1091/mbc.e08-10-1061] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Cytoplasmic stress granules (SGs) are specialized regulatory sites of mRNA translation that form under different stress conditions known to inhibit translation initiation. The formation of SG occurs via two pathways; the eukaryotic initiation factor (eIF) 2alpha phosphorylation-dependent pathway mediated by stress and the eIF2alpha phosphorylation-independent pathway mediated by inactivation of the translation initiation factors eIF4A and eIF4G. In this study, we investigated the effects of targeting different translation initiation factors and steps in SG formation in HeLa cells. By depleting eIF2alpha, we demonstrate that reduced levels of the eIF2.GTP.Met-tRNAi(Met) ternary translation initiation complexes is sufficient to induce SGs. Likewise, reduced levels of eIF4B, eIF4H, or polyA-binding protein, also trigger SG formation. In contrast, depletion of the cap-binding protein eIF4E or preventing its assembly into eIF4F results in modest SG formation. Intriguingly, interfering with the last step of translation initiation by blocking the recruitment of 60S ribosome either with 2-(4-methyl-2,6-dinitroanilino)-N-methylpropionamideis or through depletion of the large ribosomal subunits protein L28 does not induce SG assembly. Our study identifies translation initiation steps and factors involved in SG formation as well as those that can be targeted without induction of SGs.
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Affiliation(s)
- Sophie Mokas
- Département de Biologie Médicale, Centre Hospitalier Universitaire de Québec/Centre De Recherche Hôpital Saint-François D'assise, Université Laval, Quebec, QC, Canada
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