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Kim KQ, Nanjaraj Urs AN, Lasehinde V, Greenlaw AC, Hudson BH, Zaher HS. eIF4F complex dynamics are important for the activation of the integrated stress response. Mol Cell 2024; 84:2135-2151.e7. [PMID: 38848692 PMCID: PMC11189614 DOI: 10.1016/j.molcel.2024.04.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 12/08/2023] [Accepted: 04/19/2024] [Indexed: 06/09/2024]
Abstract
In response to stress, eukaryotes activate the integrated stress response (ISR) via phosphorylation of eIF2α to promote the translation of pro-survival effector genes, such as GCN4 in yeast. Complementing the ISR is the target of rapamycin (TOR) pathway, which regulates eIF4E function. Here, we probe translational control in the absence of eIF4E in Saccharomyces cerevisiae. Intriguingly, we find that loss of eIF4E leads to de-repression of GCN4 translation. In addition, we find that de-repression of GCN4 translation is accompanied by neither eIF2α phosphorylation nor reduction in initiator ternary complex (TC). Our data suggest that when eIF4E levels are depleted, GCN4 translation is de-repressed via a unique mechanism that may involve faster scanning by the small ribosome subunit due to increased local concentration of eIF4A. Overall, our findings suggest that relative levels of eIF4F components are key to ribosome dynamics and may play important roles in translational control of gene expression.
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Affiliation(s)
- Kyusik Q Kim
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | | | - Victor Lasehinde
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Alison C Greenlaw
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Benjamin H Hudson
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Hani S Zaher
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA.
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Williams TD, Rousseau A. Translation regulation in response to stress. FEBS J 2024. [PMID: 38308808 DOI: 10.1111/febs.17076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 12/07/2023] [Accepted: 01/22/2024] [Indexed: 02/05/2024]
Abstract
Cell stresses occur in a wide variety of settings: in disease, during industrial processes, and as part of normal day-to-day rhythms. Adaptation to these stresses requires cells to alter their proteome. Cells modify the proteins they synthesize to aid proteome adaptation. Changes in both mRNA transcription and translation contribute to altered protein synthesis. Here, we discuss the changes in translational mechanisms that occur following the onset of stress, and the impact these have on stress adaptation.
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Affiliation(s)
- Thomas D Williams
- MRC-PPU, School of Life Sciences, University of Dundee, UK
- Sir William Dunn School of Pathology, University of Oxford, UK
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Tai YT, Fukuda T, Morozumi Y, Hirai H, Oda AH, Kamada Y, Akikusa Y, Kanki T, Ohta K, Shiozaki K. Fission Yeast TORC1 Promotes Cell Proliferation through Sfp1, a Transcription Factor Involved in Ribosome Biogenesis. Mol Cell Biol 2023; 43:675-692. [PMID: 38051102 PMCID: PMC10761059 DOI: 10.1080/10985549.2023.2282349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 11/06/2023] [Indexed: 12/07/2023] Open
Abstract
Target of rapamycin complex 1 (TORC1) is activated in response to nutrient availability and growth factors, promoting cellular anabolism and proliferation. To explore the mechanism of TORC1-mediated proliferation control, we performed a genetic screen in fission yeast and identified Sfp1, a zinc-finger transcription factor, as a multicopy suppressor of temperature-sensitive TORC1 mutants. Our observations suggest that TORC1 phosphorylates Sfp1 and protects Sfp1 from proteasomal degradation. Transcription analysis revealed that Sfp1 positively regulates genes involved in ribosome production together with two additional transcription factors, Ifh1/Crf1 and Fhl1. Ifh1 physically interacts with Fhl1, and the nuclear localization of Ifh1 is regulated in response to nutrient levels in a manner dependent on TORC1 and Sfp1. Taken together, our data suggest that the transcriptional regulation of the genes involved in ribosome biosynthesis by Sfp1, Ifh1, and Fhl1 is one of the key pathways through which nutrient-activated TORC1 promotes cell proliferation.
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Affiliation(s)
- Yen Teng Tai
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Tomoyuki Fukuda
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Hayato Hirai
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Arisa H. Oda
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Yoshiaki Kamada
- National Institute for Basic Biology, Okazaki, Aichi, Japan
- Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa, Japan
| | - Yutaka Akikusa
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Tomotake Kanki
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Kunihiro Ohta
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
- Department of Microbiology and Molecular Genetics, University of California, Davis, California, USA
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