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Rai S, Szaruga M, Pitera AP, Bertolotti A. Integrated stress response activator halofuginone protects mice from diabetes-like phenotypes. J Cell Biol 2024; 223:e202405175. [PMID: 39150520 PMCID: PMC11329777 DOI: 10.1083/jcb.202405175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 06/27/2024] [Accepted: 06/27/2024] [Indexed: 08/17/2024] Open
Abstract
The integrated stress response (ISR) is a vital signaling pathway initiated by four kinases, PERK, GCN2, HRI and PKR, that ensure cellular resilience and protect cells from challenges. Here, we investigated whether increasing ISR signaling could rescue diabetes-like phenotypes in a mouse model of diet-induced obesity (DIO). We show that the orally available and clinically approved GCN2 activator halofuginone (HF) can activate the ISR in mouse tissues. We found that daily oral administration of HF increases glucose tolerance whilst reducing weight gain, insulin resistance, and serum insulin in DIO mice. Conversely, the ISR inhibitor GSK2656157, used at low doses to optimize its selectivity, aggravates glucose intolerance in DIO mice. Whilst loss of function mutations in mice and humans have revealed that PERK is the essential ISR kinase that protects from diabetes, our work demonstrates the therapeutic value of increasing ISR signaling by activating the related kinase GCN2 to reduce diabetes phenotypes in a DIO mouse model.
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Affiliation(s)
- Shashank Rai
- MRC Laboratory of Molecular Biology , Cambridge, UK
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2
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Stępkowski TM, Linke V, Stadnik D, Zakrzewski M, Zawada AE, Serwa RA, Chacinska A. Temporal alterations of the nascent proteome in response to mitochondrial stress. Cell Rep 2024; 43:114803. [PMID: 39361503 DOI: 10.1016/j.celrep.2024.114803] [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: 10/03/2023] [Revised: 08/02/2024] [Accepted: 09/12/2024] [Indexed: 10/05/2024] Open
Abstract
Under stress, protein synthesis is attenuated to preserve energy and mitigate challenges to protein homeostasis. Here, we describe, with high temporal resolution, the dynamic landscape of changes in the abundance of proteins synthesized upon stress from transient mitochondrial inner membrane depolarization. This nascent proteome was altered when global translation was attenuated by stress and began to normalize as translation was recovering. This transition was associated with a transient desynchronization of cytosolic and mitochondrial translation and recovery of cytosolic and mitochondrial ribosomal proteins. Further, the elongation factor EEF1A1 was downregulated upon mitochondrial stress, and its silencing mimicked the stress-induced nascent proteome remodeling, including alterations in the nascent respiratory chain proteins. Unexpectedly, the stress-induced alterations in the nascent proteome were independent of physiological protein abundance and turnover. In summary, we provide insights into the physiological and pathological consequences of mitochondrial function and dysfunction.
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Affiliation(s)
- Tomasz M Stępkowski
- Remedy International Research Agenda Unit, IMol Polish Academy of Sciences, 02-247 Warsaw, Poland; IMol Polish Academy of Sciences, 02-247 Warsaw, Poland
| | - Vanessa Linke
- Remedy International Research Agenda Unit, IMol Polish Academy of Sciences, 02-247 Warsaw, Poland; IMol Polish Academy of Sciences, 02-247 Warsaw, Poland
| | - Dorota Stadnik
- Remedy International Research Agenda Unit, IMol Polish Academy of Sciences, 02-247 Warsaw, Poland; IMol Polish Academy of Sciences, 02-247 Warsaw, Poland
| | | | - Anna E Zawada
- IMol Polish Academy of Sciences, 02-247 Warsaw, Poland
| | - Remigiusz A Serwa
- Remedy International Research Agenda Unit, IMol Polish Academy of Sciences, 02-247 Warsaw, Poland; IMol Polish Academy of Sciences, 02-247 Warsaw, Poland
| | - Agnieszka Chacinska
- Remedy International Research Agenda Unit, IMol Polish Academy of Sciences, 02-247 Warsaw, Poland; IMol Polish Academy of Sciences, 02-247 Warsaw, Poland.
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3
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Volloch V, Rits-Volloch S. Quintessential Synergy: Concurrent Transient Administration of Integrated Stress Response Inhibitors and BACE1 and/or BACE2 Activators as the Optimal Therapeutic Strategy for Alzheimer's Disease. Int J Mol Sci 2024; 25:9913. [PMID: 39337400 PMCID: PMC11432332 DOI: 10.3390/ijms25189913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2024] [Revised: 09/01/2024] [Accepted: 09/03/2024] [Indexed: 09/30/2024] Open
Abstract
The present study analyzes two potential therapeutic approaches for Alzheimer's disease (AD). One is the suppression of the neuronal integrated stress response (ISR). Another is the targeted degradation of intraneuronal amyloid-beta (iAβ) via the activation of BACE1 (Beta-site Aβ-protein-precursor Cleaving Enzyme) and/or BACE2. Both approaches are rational. Both are promising. Both have substantial intrinsic limitations. However, when combined in a carefully orchestrated manner into a composite therapy they display a prototypical synergy and constitute the apparently optimal, potentially most effective therapeutic strategy for AD.
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Affiliation(s)
- Vladimir Volloch
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Children's Hospital, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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4
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Kosakamoto H, Sakuma C, Okada R, Miura M, Obata F. Context-dependent impact of the dietary non-essential amino acid tyrosine on Drosophila physiology and longevity. SCIENCE ADVANCES 2024; 10:eadn7167. [PMID: 39213345 PMCID: PMC11364096 DOI: 10.1126/sciadv.adn7167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Accepted: 07/26/2024] [Indexed: 09/04/2024]
Abstract
Dietary protein intake modulates growth, reproduction, and longevity by stimulating amino acid (AA)-sensing pathways. Essential AAs are often considered as limiting nutrients during protein scarcity, and the role of dietary non-essential AAs (NEAAs) is less explored. Although tyrosine has been reported to be crucial for sensing protein restriction in Drosophila larvae, its effect on adult physiology and longevity remains unclear. Here, using a synthetic diet, we perform a systematic investigation of the effect of single NEAA deprivation on nutrient-sensing pathways, reproductive ability, starvation resistance, feeding behavior, and life span in adult female flies. Specifically, dietary tyrosine deprivation decreases internal tyrosine levels and fecundity, influences AA-sensing machineries, and extends life span. These nutritional responses are not observed under higher total AA intake or in infertile female flies, suggesting a context-dependent influence of dietary tyrosine. Our findings highlight the unique role of tyrosine as a potentially limiting nutrient, underscoring its value for dietary interventions aimed at enhancing health span.
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Affiliation(s)
- Hina Kosakamoto
- RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Chisako Sakuma
- RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Rina Okada
- RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Masayuki Miura
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Fumiaki Obata
- RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
- Laboratory of Molecular Cell Biology and Development, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
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5
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Dai H, Wu B, Ge Y, Hao Y, Zhou L, Hong R, Zhang J, Jiang W, Zhang Y, Li H, Zhang L. Deubiquitylase OTUD3 regulates integrated stress response to suppress progression and sorafenib resistance of liver cancer. Cell Rep 2024; 43:114487. [PMID: 38996071 DOI: 10.1016/j.celrep.2024.114487] [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: 01/29/2024] [Revised: 05/13/2024] [Accepted: 06/25/2024] [Indexed: 07/14/2024] Open
Abstract
The integrated stress response (ISR) is activated in response to intrinsic and extrinsic stimuli, playing a role in tumor progression and drug resistance. The regulatory role and mechanism of ISR in liver cancer, however, remain largely unexplored. Here, we demonstrate that OTU domain-containing protein 3 (OTUD3) is a deubiquitylase of eukaryotic initiation factor 2α (eIF2α), antagonizing ISR and suppressing liver cancer. OTUD3 decreases interactions between eIF2α and the kinase EIF2ΑK3 by removing K27-linked polyubiquitylation on eIF2α. OTUD3 deficiency in mice leads to enhanced ISR and accelerated progression of N-nitrosodiethylamine-induced hepatocellular carcinoma. Additionally, decreased OTUD3 expression associated with elevated eIF2α phosphorylation correlates with the progression of human liver cancer. Moreover, ISR activation due to decreased OTUD3 expression renders liver cancer cells resistant to sorafenib, while the combined use of the ISR inhibitor ISRIB significantly improves their sensitivity to sorafenib. Collectively, these findings illuminate the regulatory mechanism of ISR in liver cancer and provide a potential strategy to counteract sorafenib resistance.
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Affiliation(s)
- Hongmiao Dai
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China; Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Bo Wu
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China
| | - Yingwei Ge
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China
| | - Yang Hao
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China
| | - Lijie Zhou
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China; School of Medicine, Tsinghua University, Beijing 100084, China
| | - Ruolin Hong
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China; Department of Pathology and Pathophysiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui 230032, China
| | - Jinhao Zhang
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China; Department of Cell Biology, School of Basic Medicine, Medical College, Qingdao University, Qingdao 266071, China
| | - Wenli Jiang
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China; School of Life Sciences, Hebei University, Baoding, Hebei 071002, China
| | - Yuting Zhang
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China; School of Life Sciences, Hebei University, Baoding, Hebei 071002, China
| | - Hongchang Li
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China.
| | - Lingqiang Zhang
- State Key Laboratory of Medical Proteomics, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 100850, China.
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6
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Lama-Diaz T, Blanco MG. Alternative translation initiation by ribosomal leaky scanning produces multiple isoforms of the Pif1 helicase. Nucleic Acids Res 2024; 52:6928-6944. [PMID: 38783074 PMCID: PMC11229318 DOI: 10.1093/nar/gkae400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 04/24/2024] [Accepted: 05/01/2024] [Indexed: 05/25/2024] Open
Abstract
In budding yeast, the integrity of both the nuclear and mitochondrial genomes relies on dual-targeted isoforms of the conserved Pif1 helicase, generated by alternative translation initiation (ATI) of PIF1 mRNA from two consecutive AUG codons flanking a mitochondrial targeting signal. Here, we demonstrate that ribosomal leaky scanning is the specific ATI mechanism that produces not only these, but also novel, previously uncharacterized Pif1 isoforms. Both in-frame, downstream AUGs as well as near-cognate start codons contribute to the generation of these alternative isoforms. This has crucial implications for the rational design of genuine separation-of-function alleles and provides an explanation for the suboptimal behaviour of the widely employed mitochondrial- (pif1-m1) and nuclear-deficient (pif1-m2) alleles, with mutations in the first or second AUG codon, respectively. We have taken advantage of this refined model to develop improved versions of these alleles, which will serve as valuable tools to elucidate novel functions of this helicase and to disambiguate previously described genetic interactions of PIF1 in the context of nuclear and mitochondrial genome stability.
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Affiliation(s)
- Tomas Lama-Diaz
- Department of Biochemistry and Molecular Biology, CIMUS, Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, A Coruña 15782, Spain
| | - Miguel G Blanco
- Department of Biochemistry and Molecular Biology, CIMUS, Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, A Coruña 15782, Spain
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7
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Liao K, Liu K, Wang Z, Zhao K, Mei Y. TRIM2 promotes metabolic adaptation to glutamine deprivation via enhancement of CPT1A activity. FEBS J 2024. [PMID: 38949993 DOI: 10.1111/febs.17218] [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: 01/06/2024] [Revised: 05/14/2024] [Accepted: 06/20/2024] [Indexed: 07/03/2024]
Abstract
Cancer cells undergo metabolic adaptation to promote their survival and growth under energy stress conditions, yet the underlying mechanisms remain largely unclear. Here, we report that tripartite motif-containing protein 2 (TRIM2) is upregulated in response to glutamine deprivation by the transcription factor cyclic AMP-dependent transcription factor (ATF4). TRIM2 is shown to specifically interact with carnitine O-palmitoyltransferase 1 (CPT1A), a rate-limiting enzyme of fatty acid oxidation. Via this interaction, TRIM2 enhances the enzymatic activity of CPT1A, thereby regulating intracellular lipid levels and protecting cells from glutamine deprivation-induced apoptosis. Furthermore, TRIM2 is able to promote both in vitro cell proliferation and in vivo xenograft tumor growth via CPT1A. Together, these findings establish TRIM2 as an important regulator of the metabolic adaptation of cancer cells to glutamine deprivation and implicate TRIM2 as a potential therapeutic target for cancer.
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Affiliation(s)
- Kaimin Liao
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Kaiyue Liu
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Zhongyu Wang
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Kailiang Zhao
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yide Mei
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
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8
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Dabsan S, Twito G, Biadsy S, Igbaria A. Less is better: various means to reduce protein load in the endoplasmic reticulum. FEBS J 2024. [PMID: 38865586 DOI: 10.1111/febs.17201] [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: 12/27/2023] [Revised: 04/08/2024] [Accepted: 06/05/2024] [Indexed: 06/14/2024]
Abstract
The endoplasmic reticulum (ER) is an important organelle that controls the intracellular and extracellular environments. The ER is responsible for folding almost one-third of the total protein population in the eukaryotic cell. Disruption of ER-protein folding is associated with numerous human diseases, including metabolic disorders, neurodegenerative diseases, and cancer. During ER perturbations, the cells deploy various mechanisms to increase the ER-folding capacity and reduce ER-protein load by minimizing the number of substrates entering the ER to regain homeostasis. These mechanisms include signaling pathways, degradation mechanisms, and other processes that mediate the reflux of ER content to the cytosol. In this review, we will discuss the recent discoveries of five different ER quality control mechanisms, including the unfolded protein response (UPR), ER-associated-degradation (ERAD), pre-emptive quality control, ER-phagy and ER to cytosol signaling (ERCYS). We will discuss the roles of these processes in decreasing ER-protein load and inter-mechanism crosstalk.
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Affiliation(s)
- Salam Dabsan
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Gal Twito
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Suma Biadsy
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Aeid Igbaria
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
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9
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Yin JZ, Keszei AFA, Houliston S, Filandr F, Beenstock J, Daou S, Kitaygorodsky J, Schriemer DC, Mazhab-Jafari MT, Gingras AC, Sicheri F. The HisRS-like domain of GCN2 is a pseudoenzyme that can bind uncharged tRNA. Structure 2024; 32:795-811.e6. [PMID: 38531363 DOI: 10.1016/j.str.2024.02.021] [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: 06/22/2023] [Revised: 01/09/2024] [Accepted: 02/28/2024] [Indexed: 03/28/2024]
Abstract
GCN2 is a stress response kinase that phosphorylates the translation initiation factor eIF2α to inhibit general protein synthesis when activated by uncharged tRNA and stalled ribosomes. The presence of a HisRS-like domain in GCN2, normally associated with tRNA aminoacylation, led to the hypothesis that eIF2α kinase activity is regulated by the direct binding of this domain to uncharged tRNA. Here we solved the structure of the HisRS-like domain in the context of full-length GCN2 by cryoEM. Structure and function analysis shows the HisRS-like domain of GCN2 has lost histidine and ATP binding but retains tRNA binding abilities. Hydrogen deuterium exchange mass spectrometry, site-directed mutagenesis and computational docking experiments support a tRNA binding model that is partially shifted from that employed by bona fide HisRS enzymes. These results demonstrate that the HisRS-like domain of GCN2 is a pseudoenzyme and advance our understanding of GCN2 regulation and function.
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Affiliation(s)
- Jay Z Yin
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Alexander F A Keszei
- Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Scott Houliston
- Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON M5G 1L7, Canada; Structural Genomics Consortium, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Frantisek Filandr
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Jonah Beenstock
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
| | - Salima Daou
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
| | - Julia Kitaygorodsky
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - David C Schriemer
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Mohammad T Mazhab-Jafari
- Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Frank Sicheri
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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10
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Diamond PD, McGlincy NJ, Ingolia NT. Depletion of cap-binding protein eIF4E dysregulates amino acid metabolic gene expression. Mol Cell 2024; 84:2119-2134.e5. [PMID: 38848691 DOI: 10.1016/j.molcel.2024.05.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 02/21/2024] [Accepted: 05/09/2024] [Indexed: 06/09/2024]
Abstract
Protein synthesis is metabolically costly and must be tightly coordinated with changing cellular needs and nutrient availability. The cap-binding protein eIF4E makes the earliest contact between mRNAs and the translation machinery, offering a key regulatory nexus. We acutely depleted this essential protein and found surprisingly modest effects on cell growth and recovery of protein synthesis. Paradoxically, impaired protein biosynthesis upregulated genes involved in the catabolism of aromatic amino acids simultaneously with the induction of the amino acid biosynthetic regulon driven by the integrated stress response factor GCN4. We further identified the translational control of Pho85 cyclin 5 (PCL5), a negative regulator of Gcn4, that provides a consistent protein-to-mRNA ratio under varied translation environments. This regulation depended in part on a uniquely long poly(A) tract in the PCL5 5' UTR and poly(A) binding protein. Collectively, these results highlight how eIF4E connects protein synthesis to metabolic gene regulation, uncovering mechanisms controlling translation during environmental challenges.
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Affiliation(s)
- Paige D Diamond
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Nicholas J McGlincy
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Nicholas T Ingolia
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Center for Computational Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA.
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11
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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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12
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Pei Y, Liu S, Wang L, Chen C, Hu M, Xue Y, Guan D, Xie L, Liao H, Zhou J, Zhang H. Design, Synthesis, and Biological Evaluation of Eukaryotic Initiation Factor 2B (eIF2B) Activators. ChemMedChem 2024; 19:e202300716. [PMID: 38426720 DOI: 10.1002/cmdc.202300716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/29/2024] [Accepted: 02/29/2024] [Indexed: 03/02/2024]
Abstract
The eukaryotic initiation factor 2B (eIF2B) is a key regulator in protein-regulated signaling pathways and is closely related to the function of the central nervous system. Modulating eIF2B could retard the process of neurodegenerative diseases, including Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and vanishing white matter disease (VWM) et al. Here, we designed and synthesized a series of novel eIF2B activators containing oxadiazole fragments. The activating effects of compounds on eIF2B were investigated through testing the inhibition of ATF4 expression. Of all the targeted compounds, compounds 21 and 29 exhibited potent inhibition on ATF4 expression with IC50 values of 32.43 nM and 47.71 nM, respectively, which were stronger than that of ISRIB (IC50=67.90 nM). ATF4 mRNA assay showed that these two compounds could restore ATF4 mRNA to normal levels in thapsigargin-stimulated HeLa cells. Protein Translation assay showed that both compounds were effective in restoring protein synthesis. Compound potency assay showed that both compounds had similar potency to ISRIB with EC50 values of 5.844 and 37.70 nM. Cytotoxicity assay revealed that compounds 21 and 29 had low toxicity and were worth further investigation.
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Affiliation(s)
- Yifeng Pei
- Center for Drug Discovery, Jiangsu Key Laboratory of Drug Discovery for Metabolic Disease, China Pharmaceutical University, Nanjing, 210009, PR China
| | - Sentao Liu
- Center for Drug Discovery, Jiangsu Key Laboratory of Drug Discovery for Metabolic Disease, China Pharmaceutical University, Nanjing, 210009, PR China
| | - Lixun Wang
- Center for Drug Discovery, Jiangsu Key Laboratory of Drug Discovery for Metabolic Disease, China Pharmaceutical University, Nanjing, 210009, PR China
| | - Chao Chen
- Center for Drug Discovery, Jiangsu Key Laboratory of Drug Discovery for Metabolic Disease, China Pharmaceutical University, Nanjing, 210009, PR China
| | - Mengqiu Hu
- New Drug Screening Center, Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
| | - Yi Xue
- Center for Drug Discovery, Jiangsu Key Laboratory of Drug Discovery for Metabolic Disease, China Pharmaceutical University, Nanjing, 210009, PR China
| | - Dezhong Guan
- Department of Medicinal Chemistry, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing, 210009, PR China
| | - Lingfeng Xie
- Center for Drug Discovery, Jiangsu Key Laboratory of Drug Discovery for Metabolic Disease, China Pharmaceutical University, Nanjing, 210009, PR China
| | - Hong Liao
- New Drug Screening Center, Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
| | - Jinpei Zhou
- Department of Medicinal Chemistry, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing, 210009, PR China
| | - Huibin Zhang
- Center for Drug Discovery, Jiangsu Key Laboratory of Drug Discovery for Metabolic Disease, China Pharmaceutical University, Nanjing, 210009, PR China
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13
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Volloch V, Rits-Volloch S. ACH2.0/E, the Consolidated Theory of Conventional and Unconventional Alzheimer's Disease: Origins, Progression, and Therapeutic Strategies. Int J Mol Sci 2024; 25:6036. [PMID: 38892224 PMCID: PMC11172602 DOI: 10.3390/ijms25116036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 05/19/2024] [Accepted: 05/21/2024] [Indexed: 06/21/2024] Open
Abstract
The centrality of amyloid-beta (Aβ) is an indisputable tenet of Alzheimer's disease (AD). It was initially indicated by the detection (1991) of a mutation within Aβ protein precursor (AβPP) segregating with the disease, which served as a basis for the long-standing Amyloid Cascade Hypothesis (ACH) theory of AD. In the intervening three decades, this notion was affirmed and substantiated by the discovery of numerous AD-causing and AD-protective mutations with all, without an exception, affecting the structure, production, and intraneuronal degradation of Aβ. The ACH postulated that the disease is caused and driven by extracellular Aβ. When it became clear that this is not the case, and the ACH was largely discredited, a new theory of AD, dubbed ACH2.0 to re-emphasize the centrality of Aβ, was formulated. In the ACH2.0, AD is caused by physiologically accumulated intraneuronal Aβ (iAβ) derived from AβPP. Upon reaching the critical threshold, it triggers activation of the autonomous AβPP-independent iAβ generation pathway; its output is retained intraneuronally and drives the AD pathology. The bridge between iAβ derived from AβPP and that generated independently of AβPP is the neuronal integrated stress response (ISR) elicited by the former. The ISR severely suppresses cellular protein synthesis; concurrently, it activates the production of a small subset of proteins, which apparently includes components necessary for operation of the AβPP-independent iAβ generation pathway that are absent under regular circumstances. The above sequence of events defines "conventional" AD, which is both caused and driven by differentially derived iAβ. Since the ISR can be elicited by a multitude of stressors, the logic of the ACH2.0 mandates that another class of AD, referred to as "unconventional", has to occur. Unconventional AD is defined as a disease where a stressor distinct from AβPP-derived iAβ elicits the neuronal ISR. Thus, the essence of both, conventional and unconventional, forms of AD is one and the same, namely autonomous, self-sustainable, AβPP-independent production of iAβ. What distinguishes them is the manner of activation of this pathway, i.e., the mode of causation of the disease. In unconventional AD, processes occurring at locations as distant from and seemingly as unrelated to the brain as, say, the knee can potentially trigger the disease. The present study asserts that these processes include traumatic brain injury (TBI), chronic traumatic encephalopathy, viral and bacterial infections, and a wide array of inflammatory conditions. It considers the pathways which are common to all these occurrences and culminate in the elicitation of the neuronal ISR, analyzes the dynamics of conventional versus unconventional AD, shows how the former can morph into the latter, explains how a single TBI can hasten the occurrence of AD and why it takes multiple TBIs to trigger the disease, and proposes the appropriate therapeutic strategies. It posits that yet another class of unconventional AD may occur where the autonomous AβPP-independent iAβ production pathway is initiated by an ISR-unrelated activator, and consolidates the above notions in a theory of AD, designated ACH2.0/E (for expanded ACH2.0), which incorporates the ACH2.0 as its special case and retains the centrality of iAβ produced independently of AβPP as the driving agent of the disease.
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Affiliation(s)
- Vladimir Volloch
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Children’s Hospital, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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14
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Malnassy G, Ziolkowski L, Macleod KF, Oakes SA. The Integrated Stress Response in Pancreatic Development, Tissue Homeostasis, and Cancer. Gastroenterology 2024:S0016-5085(24)04931-X. [PMID: 38768690 DOI: 10.1053/j.gastro.2024.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 04/06/2024] [Accepted: 05/02/2024] [Indexed: 05/22/2024]
Abstract
Present in all eukaryotic cells, the integrated stress response (ISR) is a highly coordinated signaling network that controls cellular behavior, metabolism, and survival in response to diverse stresses. The ISR is initiated when any 1 of 4 stress-sensing kinases (protein kinase R-like endoplasmic reticulum kinase [PERK], general control non-derepressible 2 [GCN2], double-stranded RNA-dependent protein kinase [PKR], heme-regulated eukaryotic translation initiation factor 2α kinase [HRI]) becomes activated to phosphorylate the protein translation initiation factor eukaryotic translation initiation factor 2α (eIF2α), shifting gene expression toward a comprehensive rewiring of cellular machinery to promote adaptation. Although the ISR has been shown to play an important role in the homeostasis of multiple tissues, evidence suggests that it is particularly crucial for the development and ongoing health of the pancreas. Among the most synthetically dynamic tissues in the body, the exocrine and endocrine pancreas relies heavily on the ISR to rapidly adjust cell function to meet the metabolic demands of the organism. The hardwiring of the ISR into normal pancreatic functions and adaptation to stress may explain why it is a commonly used pro-oncogenic and therapy-resistance mechanism in pancreatic ductal adenocarcinoma and pancreatic neuroendocrine tumors. Here, we review what is known about the key roles that the ISR plays in the development, homeostasis, and neoplasia of the pancreas.
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Affiliation(s)
- Greg Malnassy
- Department of Pathology, University of Chicago, Chicago, Illinois
| | - Leah Ziolkowski
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinoi; Committee on Molecular Metabolism and Nutrition, University of Chicago, Chicago, Illinois
| | - Kay F Macleod
- The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinoi; Committee on Molecular Metabolism and Nutrition, University of Chicago, Chicago, Illinois; Committee on Cancer Biology, University of Chicago, Chicago, Illinois.
| | - Scott A Oakes
- Department of Pathology, University of Chicago, Chicago, Illinois; Committee on Molecular Metabolism and Nutrition, University of Chicago, Chicago, Illinois; Committee on Cancer Biology, University of Chicago, Chicago, Illinois.
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15
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Hazari Y, Chevet E, Bailly-Maitre B, Hetz C. ER stress signaling at the interphase between MASH and HCC. Hepatology 2024:01515467-990000000-00844. [PMID: 38626349 DOI: 10.1097/hep.0000000000000893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Accepted: 03/28/2024] [Indexed: 04/18/2024]
Abstract
HCC is the most frequent primary liver cancer with an extremely poor prognosis and often develops on preset of chronic liver diseases. Major risk factors for HCC include metabolic dysfunction-associated steatohepatitis, a complex multifactorial condition associated with abnormal endoplasmic reticulum (ER) proteostasis. To cope with ER stress, the unfolded protein response engages adaptive reactions to restore the secretory capacity of the cell. Recent advances revealed that ER stress signaling plays a critical role in HCC progression. Here, we propose that chronic ER stress is a common transversal factor contributing to the transition from liver disease (risk factor) to HCC. Interventional strategies to target the unfolded protein response in HCC, such as cancer therapy, are also discussed.
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Affiliation(s)
- Younis Hazari
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
- Faculty of Medicine, Biomedical Neuroscience Institute (BNI), University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Department of Biotechnology, University of Kashmir, Srinagar, India
| | - Eric Chevet
- Inserm U1242, University of Rennes, Rennes, France
- Centre de Lutte Contre le Cancer Eugène Marquis, Rennes, France
| | - Béatrice Bailly-Maitre
- Institut National de la Santé et de la Recherche Médicale (INSERM) UMR1065, Université Côte d'Azur (UCA), Centre Méditerranéen de Médecine Moléculaire (C3M), 06204 Nice, France Team "Metainflammation and Hematometabolism", Metabolism Department, France
- Université Côte d'Azur, INSERM, U1065, C3M, 06200 Nice, France
| | - Claudio Hetz
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
- Faculty of Medicine, Biomedical Neuroscience Institute (BNI), University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Buck Institute for Research on Aging, Novato, California, USA
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16
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Henis M, Rücker T, Scharrenberg R, Richter M, Baltussen L, Hong S, Meka DP, Schwanke B, Neelagandan N, Daaboul D, Murtaza N, Krisp C, Harder S, Schlüter H, Kneussel M, Hermans-Borgmeyer I, de Wit J, Singh KK, Duncan KE, de Anda FC. The autism susceptibility kinase, TAOK2, phosphorylates eEF2 and modulates translation. SCIENCE ADVANCES 2024; 10:eadf7001. [PMID: 38608030 PMCID: PMC11014455 DOI: 10.1126/sciadv.adf7001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/12/2024] [Indexed: 04/14/2024]
Abstract
Genes implicated in translation control have been associated with autism spectrum disorders (ASDs). However, some important genetic causes of autism, including the 16p11.2 microdeletion, bear no obvious connection to translation. Here, we use proteomics, genetics, and translation assays in cultured cells and mouse brain to reveal altered translation mediated by loss of the kinase TAOK2 in 16p11.2 deletion models. We show that TAOK2 associates with the translational machinery and functions as a translational brake by phosphorylating eukaryotic elongation factor 2 (eEF2). Previously, all signal-mediated regulation of translation elongation via eEF2 phosphorylation was believed to be mediated by a single kinase, eEF2K. However, we show that TAOK2 can directly phosphorylate eEF2 on the same regulatory site, but functions independently of eEF2K signaling. Collectively, our results reveal an eEF2K-independent signaling pathway for control of translation elongation and suggest altered translation as a molecular component in the etiology of some forms of ASD.
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Affiliation(s)
- Melad Henis
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, New Valley University, 72511 El-Kharga, Egypt
| | - Tabitha Rücker
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Robin Scharrenberg
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Melanie Richter
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Lucas Baltussen
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Shuai Hong
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Durga Praveen Meka
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Birgit Schwanke
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Nagammal Neelagandan
- Neuronal Translational Control Group, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Falkenried 94, 20251 Hamburg, Germany
- Institute of Bioengineering (IBI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Danie Daaboul
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Nadeem Murtaza
- Krembil Research Institute, Donald K. Johnson Eye Institute, University Health Network, 60 Leonard Ave, Toronto, Ontario M5T 0S8, Canada
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster University, Hamilton, Ontario L8S 4A9, Canada
| | - Christoph Krisp
- Institute for Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics Group, Campus Forschung, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Sönke Harder
- Institute for Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics Group, Campus Forschung, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Hartmut Schlüter
- Institute for Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics Group, Campus Forschung, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Matthias Kneussel
- Institute of Neurogenetics, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf (UKE), 20251 Hamburg, Germany
| | - Irm Hermans-Borgmeyer
- Transgenic Service Group, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Falkenried 94, 20251 Hamburg, Germany
| | - Joris de Wit
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Karun K. Singh
- Krembil Research Institute, Donald K. Johnson Eye Institute, University Health Network, 60 Leonard Ave, Toronto, Ontario M5T 0S8, Canada
- Faculty of Medicine, University of Toronto, Medical Sciences Building, 1 King's College Cir, Toronto, Ontario M5S 1 A8, Canada
| | - Kent E. Duncan
- Neuronal Translational Control Group, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Falkenried 94, 20251 Hamburg, Germany
- Evotec SE, Manfred Eigen Campus, Essener Bogen 7, 22419 Hamburg, Germany
| | - Froylan Calderón de Anda
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
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17
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Ryoo HD. The integrated stress response in metabolic adaptation. J Biol Chem 2024; 300:107151. [PMID: 38462161 PMCID: PMC10998230 DOI: 10.1016/j.jbc.2024.107151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 02/28/2024] [Accepted: 03/03/2024] [Indexed: 03/12/2024] Open
Abstract
The integrated stress response (ISR) refers to signaling pathways initiated by stress-activated eIF2α kinases. Distinct eIF2α kinases respond to different stress signals, including amino acid deprivation and mitochondrial stress. Such stress-induced eIF2α phosphorylation attenuates general mRNA translation and, at the same time, stimulates the preferential translation of specific downstream factors to orchestrate an adaptive gene expression program. In recent years, there have been significant new advances in our understanding of ISR during metabolic stress adaptation. Here, I discuss those advances, reviewing among others the ISR activation mechanisms in response to amino acid deprivation and mitochondrial stress. In addition, I review how ISR regulates the amino acid metabolic pathways and how changes in the ISR impact the physiology and pathology of various disease models.
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Affiliation(s)
- Hyung Don Ryoo
- Department of Cell Biology, New York University Grossman School of Medicine, New York, New York, USA.
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18
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Volloch V, Rits-Volloch S. On the Inadequacy of the Current Transgenic Animal Models of Alzheimer's Disease: The Path Forward. Int J Mol Sci 2024; 25:2981. [PMID: 38474228 PMCID: PMC10932000 DOI: 10.3390/ijms25052981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 02/27/2024] [Accepted: 02/28/2024] [Indexed: 03/14/2024] Open
Abstract
For at least two reasons, the current transgenic animal models of Alzheimer's disease (AD) appear to be patently inadequate. They may be useful in many respects, the AD models; however, they are not. First, they are incapable of developing the full spectrum of the AD pathology. Second, they respond spectacularly well to drugs that are completely ineffective in the treatment of symptomatic AD. These observations indicate that both the transgenic animal models and the drugs faithfully reflect the theory that guided the design and development of both, the amyloid cascade hypothesis (ACH), and that both are inadequate because their underlying theory is. This conclusion necessitated the formulation of a new, all-encompassing theory of conventional AD-the ACH2.0. The two principal attributes of the ACH2.0 are the following. One, in conventional AD, the agent that causes the disease and drives its pathology is the intraneuronal amyloid-β (iAβ) produced in two distinctly different pathways. Two, following the commencement of AD, the bulk of Aβ is generated independently of Aβ protein precursor (AβPP) and is retained inside the neuron as iAβ. Within the framework of the ACH2.0, AβPP-derived iAβ accumulates physiologically in a lifelong process. It cannot reach levels required to support the progression of AD; it does, however, cause the disease. Indeed, conventional AD occurs if and when the levels of AβPP-derived iAβ cross the critical threshold, elicit the neuronal integrated stress response (ISR), and trigger the activation of the AβPP-independent iAβ generation pathway; the disease commences only when this pathway is operational. The iAβ produced in this pathway reaches levels sufficient to drive the AD pathology; it also propagates its own production and thus sustains the activity of the pathway and perpetuates its operation. The present study analyzes the reason underlying the evident inadequacy of the current transgenic animal models of AD. It concludes that they model, in fact, not Alzheimer's disease but rather the effects of the neuronal ISR sustained by AβPP-derived iAβ, that this is due to the lack of the operational AβPP-independent iAβ production pathway, and that this mechanism must be incorporated into any successful AD model faithfully emulating the disease. The study dissects the plausible molecular mechanisms of the AβPP-independent iAβ production and the pathways leading to their activation, and introduces the concept of conventional versus unconventional Alzheimer's disease. It also proposes the path forward, posits the principles of design of productive transgenic animal models of the disease, and describes the molecular details of their construction.
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Affiliation(s)
- Vladimir Volloch
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Children’s Hospital, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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19
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Volloch V, Rits-Volloch S. Next Generation Therapeutic Strategy for Treatment and Prevention of Alzheimer's Disease and Aging-Associated Cognitive Decline: Transient, Once-in-a-Lifetime-Only Depletion of Intraneuronal Aβ ( iAβ) by Its Targeted Degradation via Augmentation of Intra- iAβ-Cleaving Activities of BACE1 and/or BACE2. Int J Mol Sci 2023; 24:17586. [PMID: 38139415 PMCID: PMC10744314 DOI: 10.3390/ijms242417586] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 12/04/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
Although the long-standing Amyloid Cascade Hypothesis (ACH) has been largely discredited, its main attribute, the centrality of amyloid-beta (Aβ) in Alzheimer's disease (AD), remains the cornerstone of any potential interpretation of the disease: All known AD-causing mutations, without a single exception, affect, in one way or another, Aβ. The ACH2.0, a recently introduced theory of AD, preserves this attribute but otherwise differs fundamentally from the ACH. It posits that AD is a two-stage disorder where both stages are driven by intraneuronal (rather than extracellular) Aβ (iAβ) albeit of two distinctly different origins. The first asymptomatic stage is the decades-long accumulation of Aβ protein precursor (AβPP)-derived iAβ to the critical threshold. This triggers the activation of the self-sustaining AβPP-independent iAβ production pathway and the commencement of the second, symptomatic AD stage. Importantly, Aβ produced independently of AβPP is retained intraneuronally. It drives the AD pathology and perpetuates the operation of the pathway; continuous cycles of the iAβ-stimulated propagation of its own AβPP-independent production constitute an engine that drives AD, the AD Engine. It appears that the dynamics of AβPP-derived iAβ accumulation is the determining factor that either drives Aging-Associated Cognitive Decline (AACD) and triggers AD or confers the resistance to both. Within the ACH2.0 framework, the ACH-based drugs, designed to lower levels of extracellular Aβ, could be applicable in the prevention of AD and treatment of AACD because they reduce the rate of accumulation of AβPP-derived iAβ. The present study analyzes their utility and concludes that it is severely limited. Indeed, their short-term employment is ineffective, their long-term engagement is highly problematic, their implementation at the symptomatic stages of AD is futile, and their evaluation in conventional clinical trials for the prevention of AD is impractical at best, impossible at worst, and misleading in between. In contrast, the ACH2.0-guided Next Generation Therapeutic Strategy for the treatment and prevention of both AD and AACD, namely the depletion of iAβ via its transient, short-duration, targeted degradation by the novel ACH2.0-based drugs, has none of the shortcomings of the ACH-based drugs. It is potentially highly effective, easily evaluable in clinical trials, and opens up the possibility of once-in-a-lifetime-only therapeutic intervention for prevention and treatment of both conditions. It also identifies two plausible ACH2.0-based drugs: activators of physiologically occurring intra-iAβ-cleaving capabilities of BACE1 and/or BACE2.
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Affiliation(s)
- Vladimir Volloch
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Children’s Hospital, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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20
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Lee HC, Chao HT, Lee SYH, Lin CY, Tsai HJ. The Upstream 1350~1250 Nucleotide Sequences of the Human ENDOU-1 Gene Contain Critical Cis-Elements Responsible for Upregulating Its Transcription during ER Stress. Int J Mol Sci 2023; 24:17393. [PMID: 38139221 PMCID: PMC10744159 DOI: 10.3390/ijms242417393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/04/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
ENDOU-1 encodes an endoribonuclease that overcomes the inhibitory upstream open reading frame (uORF)-trap at 5'-untranslated region (UTR) of the CHOP transcript, allowing the downstream coding sequence of CHOP be translated during endoplasmic reticulum (ER) stress. However, transcriptional control of ENDOU-1 remains enigmatic. To address this, we cloned an upstream 2.1 kb (-2055~+77 bp) of human ENDOU-1 (pE2.1p) fused with reporter luciferase (luc) cDNA. The promoter strength driven by pE2.1p was significantly upregulated in both pE2.1p-transfected cells and pE2.1p-injected zebrafish embryos treated with stress inducers. Comparing the luc activities driven by pE2.1p and -1125~+77 (pE1.2p) segments, we revealed that cis-elements located at the -2055~-1125 segment might play a critical role in ENDOU-1 upregulation during ER stress. Since bioinformatics analysis predicted many cis-elements clustered at the -1850~-1250, we further deconstructed this segment to generate pE2.1p-based derivatives lacking -1850~-1750, -1749~-1650, -1649~-1486, -1485~-1350 or -1350~-1250 segments. Quantification of promoter activities driven by these five internal deletion plasmids suggested a repressor binding element within the -1649~-1486 and an activator binding element within the -1350~-1250. Since luc activities driven by the -1649~-1486 were not significantly different between normal and stress conditions, we herein propose that the stress-inducible activator bound at the -1350~-1250 segment makes a major contribution to the increased expression of human ENDOU-1 upon ER stresses.
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Affiliation(s)
- Hung-Chieh Lee
- Department of Life Science, Fu-Jen Catholic University, New Taipei City 242062, Taiwan
| | - Hsuan-Te Chao
- Department of Life Science, Fu-Jen Catholic University, New Taipei City 242062, Taiwan
| | - Selina Yi-Hsuan Lee
- Faculty of Sciences and Engineering, Maastricht University, 6211 LK Maastricht, The Netherlands
| | - Cheng-Yung Lin
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City 25245, Taiwan
| | - Huai-Jen Tsai
- Department of Life Science, Fu-Jen Catholic University, New Taipei City 242062, Taiwan
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21
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Chambers MJ, Scobell S, Sadhu MJ. Systematic characterization of the local evolutionary space available to human PKR and vaccinia virus K3. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.21.568178. [PMID: 38076952 PMCID: PMC10705557 DOI: 10.1101/2023.11.21.568178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
The interfaces between host and viral proteins can be dynamic spaces in which genetic variants are continually pursued, giving rise to evolutionary arms races. One such scenario is found between the mammalian innate immunity protein PKR (protein kinase R) and the poxvirus antagonist K3. Once activated, PKR phosphorylates the natural substrate eIF2α, which halts protein synthesis within the cell and prevents viral replication. K3 acts as a pseudosubstrate antagonist against PKR by directly antagonizing this halt in protein synthesis, enabling poxviruses to replicate in the cell. Exploring the impact of genetic variants in both PKR and K3 is necessary not only to highlight residues of evolutionary constraint and opportunity but also to elucidate the mechanism by which human PKR is able to subvert a rapidly evolving viral antagonist. To systematically explore this dynamic interface, we have generated a combinatorial library of PKR and K3 missense variants to be co-expressed and characterized in a high-throughput yeast selection assay. This assay allows us to characterize hundreds of thousands of unique PKR-K3 genetic combinations in a single pooled experiment. Our results highlight specific missense variants available to PKR that subvert the K3 antagonist. We find that improved PKR variants are readily available at sites under positive selection, with limited opportunity at sites interfacing with K3 and eIF2α. Additionally, we find many variants that improve and disable K3 antagonism, suggesting a pliable interface. We reason that this approach can be leveraged to explore the evolutionary plasticity of many other host-virus interfaces.
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Affiliation(s)
- Michael J Chambers
- Center for Genomics and Data Science Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
- Department of Microbiology & Immunology, Georgetown University, Washington DC, USA
| | - Sophia Scobell
- Center for Genomics and Data Science Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Meru J Sadhu
- Center for Genomics and Data Science Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
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22
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Johnstone JN, Mirth CK, Johnson TK, Schittenhelm RB, Piper MDW. GCN2 mediates access to stored amino acids for somatic maintenance during Drosophila ageing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.14.566972. [PMID: 38014136 PMCID: PMC10680771 DOI: 10.1101/2023.11.14.566972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Many mechanistic theories of ageing argue that a progressive failure of somatic maintenance, the use of energy and resources to prevent and repair damage to the cell, underpins ageing. To sustain somatic maintenance an organism must acquire dozens of essential nutrients from the diet, including essential amino acids (EAAs), which are physiologically limiting for many animals. In Drosophila , adulthood deprivation of each individual EAA yields vastly different lifespan trajectories, and adulthood deprivation of one EAA, phenylalanine (Phe), has no associated lifespan cost; this is despite each EAA being strictly required for growth and reproduction. Moreover, survival under any EAA deprivation depends entirely on the conserved AA sensor GCN2, a component of the integrated stress response (ISR), suggesting that a novel ISR-mediated mechanism sustains lifelong somatic maintenance during EAA deprivation. Here we investigated this mechanism, finding that flies chronically deprived of dietary Phe continue to incorporate Phe into new proteins, and that challenging flies to increase the somatic requirement for Phe shortens lifespan under Phe deprivation. Further, we show that autophagy is required for full lifespan under Phe deprivation, and that activation of the ISR can partially rescue the shortened lifespan of GCN2 -nulls under Phe deprivation. We therefore propose a mechanism by which GCN2, via the ISR, activates autophagy during EAA deprivation, breaking down a larvally-acquired store of EAAs to support somatic maintenance. These data refine our understanding of the strategies by which flies sustain lifelong somatic maintenance, which determines length of life in response to changes in the nutritional environment.
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Kutschka I, Bertero E, Wasmus C, Xiao K, Yang L, Chen X, Oshima Y, Fischer M, Erk M, Arslan B, Alhasan L, Grosser D, Ermer KJ, Nickel A, Kohlhaas M, Eberl H, Rebs S, Streckfuss-Bömeke K, Schmitz W, Rehling P, Thum T, Higuchi T, Rabinowitz J, Maack C, Dudek J. Activation of the integrated stress response rewires cardiac metabolism in Barth syndrome. Basic Res Cardiol 2023; 118:47. [PMID: 37930434 PMCID: PMC10628049 DOI: 10.1007/s00395-023-01017-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 09/29/2023] [Accepted: 10/14/2023] [Indexed: 11/07/2023]
Abstract
Barth Syndrome (BTHS) is an inherited cardiomyopathy caused by defects in the mitochondrial transacylase TAFAZZIN (Taz), required for the synthesis of the phospholipid cardiolipin. BTHS is characterized by heart failure, increased propensity for arrhythmias and a blunted inotropic reserve. Defects in Ca2+-induced Krebs cycle activation contribute to these functional defects, but despite oxidation of pyridine nucleotides, no oxidative stress developed in the heart. Here, we investigated how retrograde signaling pathways orchestrate metabolic rewiring to compensate for mitochondrial defects. In mice with an inducible knockdown (KD) of TAFAZZIN, and in induced pluripotent stem cell-derived cardiac myocytes, mitochondrial uptake and oxidation of fatty acids was strongly decreased, while glucose uptake was increased. Unbiased transcriptomic analyses revealed that the activation of the eIF2α/ATF4 axis of the integrated stress response upregulates one-carbon metabolism, which diverts glycolytic intermediates towards the biosynthesis of serine and fuels the biosynthesis of glutathione. In addition, strong upregulation of the glutamate/cystine antiporter xCT increases cardiac cystine import required for glutathione synthesis. Increased glutamate uptake facilitates anaplerotic replenishment of the Krebs cycle, sustaining energy production and antioxidative pathways. These data indicate that ATF4-driven rewiring of metabolism compensates for defects in mitochondrial uptake of fatty acids to sustain energy production and antioxidation.
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Affiliation(s)
- Ilona Kutschka
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
| | - Edoardo Bertero
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
- Department of Internal Medicine, University of Genova, Genoa, Italy
- Cardiovascular Disease Unit, IRCCS Ospedale Policlinico San Martino - Italian IRCCS Cardiology Network, Genoa, Italy
| | - Christina Wasmus
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
| | - Ke Xiao
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
- Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM), Nikolai-Fuchs-Straße 1, 30625, Hannover, Germany
| | - Lifeng Yang
- Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, 320 Yueyang Rd, Shanghai, 200031, China
| | - Xinyu Chen
- Department of Nuclear Medicine, University Clinic Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Yasuhiro Oshima
- Department of Nuclear Medicine, University Clinic Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Marcus Fischer
- Division of Pediatric Cardiology and Intensive Care, University Hospital LMU Munich, Marchioninistr. 15, 81377, Munich, Germany
| | - Manuela Erk
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
| | - Berkan Arslan
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
| | - Lin Alhasan
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
| | - Daria Grosser
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
| | - Katharina J Ermer
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
| | - Alexander Nickel
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
| | - Michael Kohlhaas
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
| | - Hanna Eberl
- Department for Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, 97078, Würzburg, Germany
| | - Sabine Rebs
- Department for Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, 97078, Würzburg, Germany
| | - Katrin Streckfuss-Bömeke
- Department for Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, 97078, Würzburg, Germany
- Clinic for Cardiology and Pneumology, Georg-August University Göttingen and DZHK (German Center for Cardiovascular Research), Partner Site, Göttingen, Germany
| | - Werner Schmitz
- Department of Biochemistry and Molecular Biology, University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Peter Rehling
- University Göttingen, Institute of Biochemistry and Molecular Cell Biology, Humboldtallee 23, 37072, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Thomas Thum
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
- Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM), Nikolai-Fuchs-Straße 1, 30625, Hannover, Germany
- Rebirth Center for Translational Regenerative Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Takahiro Higuchi
- Department of Nuclear Medicine, University Clinic Würzburg, Oberdürrbacher Strasse 6, 97080, Würzburg, Germany
| | - Joshua Rabinowitz
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, 08544, USA
| | - Christoph Maack
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany
- Medical Clinic I, University Clinic Würzburg, Würzburg, Germany
| | - Jan Dudek
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Am Schwarzenberg 15, Haus A15, 97078, Würzburg, Germany.
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Levy JL, Mirek ET, Rodriguez EM, Zalma B, Burns J, Jonsson WO, Sampath H, Staschke KA, Wek RC, Anthony TG. GCN2 is required to maintain core body temperature in mice during acute cold. Am J Physiol Endocrinol Metab 2023; 325:E624-E637. [PMID: 37792040 PMCID: PMC10864021 DOI: 10.1152/ajpendo.00181.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 09/01/2023] [Accepted: 09/29/2023] [Indexed: 10/05/2023]
Abstract
Nonshivering thermogenesis in rodents requires macronutrients to fuel the generation of heat during hypothermic conditions. In this study, we examined the role of the nutrient sensing kinase, general control nonderepressible 2 (GCN2) in directing adaptive thermogenesis during acute cold exposure in mice. We hypothesized that GCN2 is required for adaptation to acute cold stress via activation of the integrated stress response (ISR) resulting in liver production of FGF21 and increased amino acid transport to support nonshivering thermogenesis. In alignment with our hypothesis, female and male mice lacking GCN2 failed to adequately increase energy expenditure and veered into torpor. Mice administered a small molecule inhibitor of GCN2 were also profoundly intolerant to acute cold stress. Gcn2 deletion also impeded liver-derived FGF21 but in males only. Within the brown adipose tissue (BAT), acute cold exposure increased ISR activation and its transcriptional execution in males and females. RNA sequencing in BAT identified transcripts that encode actomyosin mechanics and transmembrane transport as requiring GCN2 during cold exposure. These transcripts included class II myosin heavy chain and amino acid transporters, critical for maximal thermogenesis during cold stress. Importantly, Gcn2 deletion corresponded with higher circulating amino acids and lower intracellular amino acids in the BAT during cold stress. In conclusion, we identify a sex-independent role for GCN2 activation to support adaptive thermogenesis via uptake of amino acids into brown adipose.NEW & NOTEWORTHY This paper details the discovery that GCN2 activation is required in both male and female mice to maintain core body temperature during acute cold exposure. The results point to a novel role for GCN2 in supporting adaptive thermogenesis via amino acid transport and actomyosin mechanics in brown adipose tissue.
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Affiliation(s)
- Jordan L Levy
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Emily T Mirek
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Esther M Rodriguez
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Brian Zalma
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Jeffrey Burns
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - William O Jonsson
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Harini Sampath
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
| | - Kirk A Staschke
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, United States
| | - Ronald C Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, United States
| | - Tracy G Anthony
- Department of Nutritional Sciences, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey, United States
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25
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Meydan S, Guydosh NR. Is there a localized role for translational quality control? RNA (NEW YORK, N.Y.) 2023; 29:1623-1643. [PMID: 37582617 PMCID: PMC10578494 DOI: 10.1261/rna.079683.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/26/2023] [Indexed: 08/17/2023]
Abstract
It is known that mRNAs and the machinery that translates them are not uniformly distributed throughout the cytoplasm. As a result, the expression of some genes is localized to particular parts of the cell and this makes it possible to carry out important activities, such as growth and signaling, in three-dimensional space. However, the functions of localized gene expression are not fully understood, and the underlying mechanisms that enable localized expression have not been determined in many cases. One consideration that could help in addressing these challenges is the role of quality control (QC) mechanisms that monitor translating ribosomes. On a global level, QC pathways are critical for detecting aberrant translation events, such as a ribosome that stalls while translating, and responding by activating stress pathways and resolving problematic ribosomes and mRNAs at the molecular level. However, it is unclear how these pathways, even when uniformly active throughout the cell, affect local translation. Importantly, some QC pathways have themselves been reported to be enriched in the proximity of particular organelles, but the extent of such localized activity remains largely unknown. Here, we describe the major QC pathways and review studies that have begun to explore their roles in localized translation. Given the limited data in this area, we also pose broad questions about the possibilities and limitations for how QC pathways could facilitate localized gene expression in the cell with the goal of offering ideas for future experimentation.
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Affiliation(s)
- Sezen Meydan
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
- National Institute of General Medical Sciences, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Nicholas R Guydosh
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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26
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Abstract
Heat stress is described as the cumulative detrimental effect caused by an imbalance between heat production within the body and heat dissipation. When cattle are exposed to heat stress with skin surface temperatures exceeding 35 °C, gene networks within and across cells respond to environmental heat loads with both intra and extracellular signals that coordinate cellular and whole-animal metabolism changes to store heat and rapidly increase evaporative heat loss. In this study, we examined evidence from genes known to be associated with heat tolerance (Hsp70, HSF1, HspB8, SOD1, PRLH, ATP1A1, MTOR, and EIF2AK4). This information could serve as valuable resource material for breeding programs aimed at increasing the thermotolerance of cattle.
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Affiliation(s)
- LuLan Zeng
- College of Life Sciences, Northwest A&F University, Yangling, China
| | - Kaixing Qu
- Yunnan Academy of Grassland and Animal Science, Kunming, China
| | - Jicai Zhang
- Yunnan Academy of Grassland and Animal Science, Kunming, China
| | - Bizhi Huang
- Yunnan Academy of Grassland and Animal Science, Kunming, China
| | - Chuzhao Lei
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
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27
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Livneh I, Cohen-Kaplan V, Fabre B, Abramovitch I, Lulu C, Nataraj NB, Lazar I, Ziv T, Yarden Y, Zohar Y, Gottlieb E, Ciechanover A. Regulation of nucleo-cytosolic 26S proteasome translocation by aromatic amino acids via mTOR is essential for cell survival under stress. Mol Cell 2023; 83:3333-3346.e5. [PMID: 37738964 DOI: 10.1016/j.molcel.2023.08.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 07/12/2023] [Accepted: 08/14/2023] [Indexed: 09/24/2023]
Abstract
The proteasome is responsible for removal of ubiquitinated proteins. Although several aspects of its regulation (e.g., assembly, composition, and post-translational modifications) have been unraveled, studying its adaptive compartmentalization in response to stress is just starting to emerge. We found that following amino acid starvation, the proteasome is translocated from its large nuclear pool to the cytoplasm-a response regulated by newly identified mTOR-agonistic amino acids-Tyr, Trp, and Phe (YWF). YWF relay their signal upstream of mTOR through Sestrin3 by disrupting its interaction with the GATOR2 complex. The triad activates mTOR toward its downstream substrates p62 and transcription factor EB (TFEB), affecting both proteasomal and autophagic activities. Proteasome translocation stimulates cytosolic proteolysis which replenishes amino acids, thus enabling cell survival. In contrast, nuclear sequestration of the proteasome following mTOR activation by YWF inhibits this proteolytic adaptive mechanism, leading to cell death, which establishes this newly identified pathway as a key stress-coping mechanism.
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Affiliation(s)
- Ido Livneh
- The Rappaport Faculty of Medicine and Integrated Cancer Center, Technion-Israel Institute of Technology, Haifa 3109601, Israel; Institute of Pathology, Rambam Health Care Campus, Haifa 3109601, Israel.
| | - Victoria Cohen-Kaplan
- The Rappaport Faculty of Medicine and Integrated Cancer Center, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Bertrand Fabre
- The Rappaport Faculty of Medicine and Integrated Cancer Center, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Ifat Abramovitch
- The Rappaport Faculty of Medicine and Integrated Cancer Center, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Chen Lulu
- The Rappaport Faculty of Medicine and Integrated Cancer Center, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | | | - Ikrame Lazar
- The Rappaport Faculty of Medicine and Integrated Cancer Center, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Tamar Ziv
- Smoler Proteomic Center, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Yosef Yarden
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yaniv Zohar
- The Rappaport Faculty of Medicine and Integrated Cancer Center, Technion-Israel Institute of Technology, Haifa 3109601, Israel; Institute of Pathology, Rambam Health Care Campus, Haifa 3109601, Israel
| | - Eyal Gottlieb
- The Rappaport Faculty of Medicine and Integrated Cancer Center, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Aaron Ciechanover
- The Rappaport Faculty of Medicine and Integrated Cancer Center, Technion-Israel Institute of Technology, Haifa 3109601, Israel.
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28
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Ruocco C, Malavazos AE, Ragni M, Carruba MO, Valerio A, Iacobellis G, Nisoli E. Amino acids contribute to adaptive thermogenesis. New insights into the mechanisms of action of recent drugs for metabolic disorders are emerging. Pharmacol Res 2023; 195:106892. [PMID: 37619907 DOI: 10.1016/j.phrs.2023.106892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/28/2023] [Accepted: 08/17/2023] [Indexed: 08/26/2023]
Abstract
Adaptive thermogenesis is the heat production by muscle contractions (shivering thermogenesis) or brown adipose tissue (BAT) and beige fat (non-shivering thermogenesis) in response to external stimuli, including cold exposure. BAT and beige fat communicate with peripheral organs and the brain through a variegate secretory and absorption processes - controlling adipokines, microRNAs, extracellular vesicles, and metabolites - and have received much attention as potential therapeutic targets for managing obesity-related disorders. The sympathetic nervous system and norepinephrine-releasing adipose tissue macrophages (ATM) activate uncoupling protein 1 (UCP1), expressed explicitly in brown and beige adipocytes, dissolving the electrochemical gradient and uncoupling tricarboxylic acid cycle and the electron transport chain from ATP production. Mounting evidence has attracted attention to the multiple effects of dietary and endogenously synthesised amino acids in BAT thermogenesis and metabolic phenotype in animals and humans. However, the mechanisms implicated in these processes have yet to be conclusively characterized. In the present review article, we aim to define the principal investigation areas in this context, including intestinal microbiota constitution, adipose autophagy modulation, and secretome and metabolic fluxes control, which lead to increased brown/beige thermogenesis. Finally, also based on our recent epicardial adipose tissue results, we summarise the evidence supporting the notion that the new dual and triple agonists of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon (GCG) receptor - with never before seen weight loss and insulin-sensitizing efficacy - promote thermogenic-like amino acid profiles in BAT with robust heat production and likely trigger sympathetic activation and adaptive thermogenesis by controlling amino acid metabolism and ATM expansion in BAT and beige fat.
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Affiliation(s)
- Chiara Ruocco
- Center for Study and Research on Obesity, Department of Biomedical Technology and Translational Medicine, University of Milan, via Vanvitelli, 32, 20129 Milan, Italy
| | - Alexis Elias Malavazos
- Endocrinology Unit, Clinical Nutrition and Cardiovascular Prevention Service, IRCCS Policlinico San Donato, Piazza Edmondo Malan, 2, San Donato Milanese, 20097 Milan, Italy; Department of Biomedical, Surgical and Dental Sciences, University of Milan, via della Commenda, 10, 20122 Milan, Italy
| | - Maurizio Ragni
- Center for Study and Research on Obesity, Department of Biomedical Technology and Translational Medicine, University of Milan, via Vanvitelli, 32, 20129 Milan, Italy
| | - Michele O Carruba
- Center for Study and Research on Obesity, Department of Biomedical Technology and Translational Medicine, University of Milan, via Vanvitelli, 32, 20129 Milan, Italy
| | - Alessandra Valerio
- Department of Molecular and Translational Medicine, University of Brescia, viale Europa, 11, 25123 Brescia, Italy
| | - Gianluca Iacobellis
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami, 1400 NW 12th Ave, Miami, FL, USA
| | - Enzo Nisoli
- Center for Study and Research on Obesity, Department of Biomedical Technology and Translational Medicine, University of Milan, via Vanvitelli, 32, 20129 Milan, Italy.
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29
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Volloch V, Rits-Volloch S. Principles of Design of Clinical Trials for Prevention and Treatment of Alzheimer's Disease and Aging-Associated Cognitive Decline in the ACH2.0 Perspective: Potential Outcomes, Challenges, and Solutions. J Alzheimers Dis Rep 2023; 7:921-955. [PMID: 37849639 PMCID: PMC10578334 DOI: 10.3233/adr-230037] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 07/31/2023] [Indexed: 10/19/2023] Open
Abstract
With the Amyloid Cascade Hypothesis (ACH) largely discredited, the ACH2.0 theory of Alzheimer's disease (AD) has been recently introduced. Within the framework of the ACH2.0, AD is triggered by amyloid-β protein precursor (AβPP)-derived intraneuronal Aβ (iAβ) and is driven by iAβ produced in the AβPP-independent pathway and retained intraneuronally. In this paradigm, the depletion of extracellular Aβ or suppression of Aβ production by AβPP proteolysis, the two sources of AβPP-derived iAβ, would be futile in symptomatic AD, due to its reliance on iAβ generated independently of AβPP, but effective in preventing AD and treating Aging-Associated Cognitive Decline (AACD) driven, in the ACH2.0 framework, by AβPP-derived iAβ. The observed effect of lecanemab and donanemab, interpreted in the ACH2.0 perspective, supports this notion and mandates AD-preventive clinical trials. Such trials are currently in progress. They are likely, however, to fail or to yield deceptive results if conducted conventionally. The present study considers concepts of design of clinical trials of lecanemab, donanemab, or any other drug, targeting the influx of AβPP-derived iAβ, in prevention of AD and treatment of AACD. It analyzes possible outcomes and explains why selection of high-risk asymptomatic participants seems reasonable but is not. It argues that outcomes of such AD preventive trials could be grossly misleading, discusses inevitable potential problems, and proposes feasible solutions. It advocates the initial evaluation of this type of drugs in clinical trials for treatment of AACD. Whereas AD protective trials of these drugs are potentially of an impractical length, AACD clinical trials are expected to yield unequivocal results within a relatively short duration. Moreover, success of the latter, in addition to its intrinsic value, would constitute a proof of concept for the former. Furthermore, this study introduces concepts of the active versus passive iAβ depletion, contends that targeted degradation of iAβ is the best therapeutic strategy for both prevention and treatment of AD and AACD, proposes potential iAβ-degrading drugs, and describes their feasible and unambiguous evaluation in clinical trials.
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Affiliation(s)
- Vladimir Volloch
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Children’s Hospital, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
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30
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Lines CL, McGrath MJ, Dorwart T, Conn CS. The integrated stress response in cancer progression: a force for plasticity and resistance. Front Oncol 2023; 13:1206561. [PMID: 37601686 PMCID: PMC10435748 DOI: 10.3389/fonc.2023.1206561] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 06/07/2023] [Indexed: 08/22/2023] Open
Abstract
During their quest for growth, adaptation, and survival, cancer cells create a favorable environment through the manipulation of normal cellular mechanisms. They increase anabolic processes, including protein synthesis, to facilitate uncontrolled proliferation and deplete the tumor microenvironment of resources. As a dynamic adaptation to the self-imposed oncogenic stress, cancer cells promptly hijack translational control to alter gene expression. Rewiring the cellular proteome shifts the phenotypic balance between growth and adaptation to promote therapeutic resistance and cancer cell survival. The integrated stress response (ISR) is a key translational program activated by oncogenic stress that is utilized to fine-tune protein synthesis and adjust to environmental barriers. Here, we focus on the role of ISR signaling for driving cancer progression. We highlight mechanisms of regulation for distinct mRNA translation downstream of the ISR, expand on oncogenic signaling utilizing the ISR in response to environmental stresses, and pinpoint the impact this has for cancer cell plasticity during resistance to therapy. There is an ongoing need for innovative drug targets in cancer treatment, and modulating ISR activity may provide a unique avenue for clinical benefit.
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Affiliation(s)
| | | | | | - Crystal S. Conn
- Department of Radiation Oncology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
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31
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Volloch V, Rits-Volloch S. The Amyloid Cascade Hypothesis 2.0 for Alzheimer's Disease and Aging-Associated Cognitive Decline: From Molecular Basis to Effective Therapy. Int J Mol Sci 2023; 24:12246. [PMID: 37569624 PMCID: PMC10419172 DOI: 10.3390/ijms241512246] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023] Open
Abstract
With the long-standing amyloid cascade hypothesis (ACH) largely discredited, there is an acute need for a new all-encompassing interpretation of Alzheimer's disease (AD). Whereas such a recently proposed theory of AD is designated ACH2.0, its commonality with the ACH is limited to the recognition of the centrality of amyloid-β (Aβ) in the disease, necessitated by the observation that all AD-causing mutations affect, in one way or another, Aβ. Yet, even this narrow commonality is superficial since AD-causing Aβ of the ACH differs distinctly from that specified in the ACH2.0: Whereas in the former, the disease is caused by secreted extracellular Aβ, in the latter, it is triggered by Aβ-protein-precursor (AβPP)-derived intraneuronal Aβ (iAβ) and driven by iAβ generated independently of AβPP. The ACH2.0 envisions AD as a two-stage disorder. The first, asymptomatic stage is a decades-long accumulation of AβPP-derived iAβ, which occurs via internalization of secreted Aβ and through intracellular retention of a fraction of Aβ produced by AβPP proteolysis. When AβPP-derived iAβ reaches critical levels, it activates a self-perpetuating AβPP-independent production of iAβ that drives the second, devastating AD stage, a cascade that includes tau pathology and culminates in neuronal loss. The present study analyzes the dynamics of iAβ accumulation in health and disease and concludes that it is the prime factor driving both AD and aging-associated cognitive decline (AACD). It discusses mechanisms potentially involved in AβPP-independent generation of iAβ, provides mechanistic interpretations for all principal aspects of AD and AACD including the protective effect of the Icelandic AβPP mutation, the early onset of FAD and the sequential manifestation of AD pathology in defined regions of the affected brain, and explains why current mouse AD models are neither adequate nor suitable. It posits that while drugs affecting the accumulation of AβPP-derived iAβ can be effective only protectively for AD, the targeted degradation of iAβ is the best therapeutic strategy for both prevention and effective treatment of AD and AACD. It also proposes potential iAβ-degrading drugs.
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Affiliation(s)
- Vladimir Volloch
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Children’s Hospital, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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Batjargal T, Zappa F, Grant RJ, Piscopio RA, Chialastri A, Dey SS, Acosta-Alvear D, Wilson MZ. Optogenetic control of the integrated stress response reveals proportional encoding and the stress memory landscape. Cell Syst 2023; 14:551-562.e5. [PMID: 37473728 DOI: 10.1016/j.cels.2023.06.001] [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: 06/13/2022] [Revised: 12/27/2022] [Accepted: 06/09/2023] [Indexed: 07/22/2023]
Abstract
The integrated stress response (ISR) is a conserved signaling network that detects aberrations and computes cellular responses. Dissecting these computations has been difficult because physical and chemical inducers of stress activate multiple parallel pathways. To overcome this challenge, we engineered a photo-switchable control over the ISR sensor kinase PKR (opto-PKR), enabling virtual, on-target activation. Using light to control opto-PKR dynamics, we traced information flow through the transcriptome and for key downstream ISR effectors. Our analyses revealed a biphasic, proportional transcriptional response with two dynamic modes, transient and gradual, that correspond to adaptive and terminal outcomes. We then constructed an ordinary differential equation (ODE) model of the ISR, which demonstrated the dependence of future stress responses on past stress. Finally, we tested our model using high-throughput light-delivery to map the stress memory landscape. Our results demonstrate that cells encode information in stress levels, durations, and the timing between encounters. A record of this paper's transparent peer review process is included in the supplemental information.
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Affiliation(s)
- Taivan Batjargal
- Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Francesca Zappa
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Ryan J Grant
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Robert A Piscopio
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Alex Chialastri
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Siddharth S Dey
- Center for BioEngineering, University of California Santa Barbara, Santa Barbara, CA, USA; Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA; Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Diego Acosta-Alvear
- Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, CA, USA; Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA; Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA.
| | - Maxwell Z Wilson
- Center for BioEngineering, University of California Santa Barbara, Santa Barbara, CA, USA; Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, CA, USA; Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA; Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA.
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Lidsky PV, Yuan J, Lashkevich KA, Dmitriev SE, Andino R. Monitoring integrated stress response in live Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.13.548942. [PMID: 37502856 PMCID: PMC10369977 DOI: 10.1101/2023.07.13.548942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Cells exhibit stress responses to various environmental changes. Among these responses, the integrated stress response (ISR) plays a pivotal role as a crucial stress signaling pathway. While extensive ISR research has been conducted on cultured cells, our understanding of its implications in multicellular organisms remains limited, largely due to the constraints of current techniques that hinder our ability to track and manipulate the ISR in vivo. To overcome these limitations, we have successfully developed an internal ribosome entry site (IRES)-based fluorescent reporter system. This innovative reporter enables us to label Drosophila cells, within the context of a living organism, that exhibit eIF2 phosphorylation-dependent translational shutoff - a characteristic feature of the ISR and viral infections. Through this methodology, we have unveiled tissue- and cell-specific regulation of stress response in Drosophila flies and have even been able to detect stressed tissues in vivo during virus and bacterial infections. To further validate the specificity of our reporter, we have engineered ISR-null eIF2αS50A mutant flies for stress response analysis. Our results shed light on the tremendous potential of this technique for investigating a broad range of developmental, stress, and infection-related experimental conditions. Combining the reporter tool with ISR-null mutants establishes Drosophila as an exceptionally powerful model for studying the ISR in the context of multicellular organisms.
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Affiliation(s)
- Peter V Lidsky
- University of California San Francisco, San Francisco, CA, 94158
| | - Jing Yuan
- University of California San Francisco, San Francisco, CA, 94158
| | - Kseniya A Lashkevich
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234 Russia
| | - Sergey E Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234 Russia
| | - Raul Andino
- University of California San Francisco, San Francisco, CA, 94158
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Nguyen T, Mills JC, Cho CJ. The coordinated management of ribosome and translation during injury and regeneration. Front Cell Dev Biol 2023; 11:1186638. [PMID: 37427381 PMCID: PMC10325863 DOI: 10.3389/fcell.2023.1186638] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 06/06/2023] [Indexed: 07/11/2023] Open
Abstract
Diverse acute and chronic injuries induce damage responses in the gastrointestinal (GI) system, and numerous cell types in the gastrointestinal tract demonstrate remarkable resilience, adaptability, and regenerative capacity in response to stress. Metaplasias, such as columnar and secretory cell metaplasia, are well-known adaptations that these cells make, the majority of which are epidemiologically associated with an elevated cancer risk. On a number of fronts, it is now being investigated how cells respond to injury at the tissue level, where diverse cell types that differ in proliferation capacity and differentiation state cooperate and compete with one another to participate in regeneration. In addition, the cascades or series of molecular responses that cells show are just beginning to be understood. Notably, the ribosome, a ribonucleoprotein complex that is essential for translation on the endoplasmic reticulum (ER) and in the cytoplasm, is recognized as the central organelle during this process. The highly regulated management of ribosomes as key translational machinery, and their platform, rough endoplasmic reticulum, are not only essential for maintaining differentiated cell identity, but also for achieving successful cell regeneration after injury. This review will cover in depth how ribosomes, the endoplasmic reticulum, and translation are regulated and managed in response to injury (e.g., paligenosis), as well as why this is essential for the proper adaptation of a cell to stress. For this, we will first discuss how multiple gastrointestinal organs respond to stress through metaplasia. Next, we will cover how ribosomes are generated, maintained, and degraded, in addition to the factors that govern translation. Finally, we will investigate how ribosomes and translation machinery are dynamically regulated in response to injury. Our increased understanding of this overlooked cell fate decision mechanism will facilitate the discovery of novel therapeutic targets for gastrointestinal tract tumors, focusing on ribosomes and translation machinery.
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Affiliation(s)
- Thanh Nguyen
- Department of Medicine, Baylor College of Medicine, Houston, TX, United States
| | - Jason C. Mills
- Department of Medicine, Baylor College of Medicine, Houston, TX, United States
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, United States
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, United States
| | - Charles J. Cho
- Department of Medicine, Baylor College of Medicine, Houston, TX, United States
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Diamond PD, McGlincy NJ, Ingolia NT. Dysregulation of amino acid metabolism upon rapid depletion of cap-binding protein eIF4E. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.11.540079. [PMID: 37214807 PMCID: PMC10197679 DOI: 10.1101/2023.05.11.540079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Protein synthesis is a crucial but metabolically costly biological process that must be tightly coordinated with cellular needs and nutrient availability. In response to environmental stress, translation initiation is modulated to control protein output while meeting new demands. The cap-binding protein eIF4E-the earliest contact between mRNAs and the translation machinery-serves as one point of control, but its contributions to mRNA-specific translation regulation remain poorly understood. To survey eIF4E-dependent translational control, we acutely depleted eIF4E and determined how this impacts protein synthesis. Despite its essentiality, eIF4E depletion had surprisingly modest effects on cell growth and protein synthesis. Analysis of transcript-level changes revealed that long-lived transcripts were downregulated, likely reflecting accelerated turnover. Paradoxically, eIF4E depletion led to simultaneous upregulation of genes involved in catabolism of aromatic amino acids, which arose as secondary effects of reduced protein biosynthesis on amino acid pools, and genes involved in the biosynthesis of amino acids. These futile cycles of amino acid synthesis and degradation were driven, in part, by translational activation of GCN4, a transcription factor typically induced by amino acid starvation. Furthermore, we identified a novel regulatory mechanism governing translation of PCL5, a negative regulator of Gcn4, that provides a consistent protein-to-mRNA ratio under varied translation environments. This translational control was partial dependent on a uniquely long poly-(A) tract in the PCL5 5' UTR and on poly-(A) binding protein. Collectively, these results highlight how eIF4E connects translation to amino acid homeostasis and stress responses and uncovers new mechanisms underlying how cells tightly control protein synthesis during environmental challenges.
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Affiliation(s)
- Paige D. Diamond
- Department of Molecular and Cell Biology, University of California, Berkeley
| | | | - Nicholas T. Ingolia
- Department of Molecular and Cell Biology, University of California, Berkeley
- Center for Computational Biology and California Institute for Quantitative Biosciences, University of California, Berkeley
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Knowles CM, Goich D, Bloom ALM, Kalem MC, Panepinto JC. Contributions of Ccr4 and Gcn2 to the Translational Response of C. neoformans to Host-Relevant Stressors and Integrated Stress Response Induction. mBio 2023; 14:e0019623. [PMID: 37017529 PMCID: PMC10127693 DOI: 10.1128/mbio.00196-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 03/06/2023] [Indexed: 04/06/2023] Open
Abstract
In response to the host environment, the human pathogen Cryptococcus neoformans must rapidly reprogram its translatome from one which promotes growth to one which is responsive to host stress. In this study, we investigate the two events which comprise translatome reprogramming: the removal of abundant, pro-growth mRNAs from the translating pool, and the regulated entry of stress-responsive mRNAs into the translating pool. Removal of pro-growth mRNAs from the translating pool is controlled primarily by two regulatory mechanisms, repression of translation initiation via Gcn2, and decay mediated by Ccr4. We determined that translatome reprogramming in response to oxidative stress requires both Gcn2 and Ccr4, whereas the response to temperature requires only Ccr4. Additionally, we assessed ribosome collision in response to host-relevant stress and found that collided ribosomes accumulated during temperature stress but not during oxidative stress. The phosphorylation of eIF2α that occurred as a result of translational stress led us to investigate the induction of the integrated stress response (ISR). We found that eIF2α phosphorylation varied in response to the type and magnitude of stress, yet all tested conditions induced translation of the ISR transcription factor Gcn4. However, Gcn4 translation did not necessarily result in canonical Gcn4-dependent transcription. Finally, we define the ISR regulon in response to oxidative stress. In conclusion, this study begins to reveal the translational regulation in response to host-relevant stressors in an environmental fungus which is capable of adapting to the environment inside the human host. IMPORTANCE Cryptococcus neoformans is a human pathogen capable of causing devastating infections. It must rapidly adapt to changing environments as it leaves its niche in the soil and enters the human lung. Previous work has demonstrated a need to reprogram gene expression at the level of translation to promote stress adaptation. In this work, we investigate the contributions and interplay of the major mechanisms that regulate entry of new mRNAs into the pool (translation initiation) and the clearance of unneeded mRNAs from the pool (mRNA decay). One result of this reprogramming is the induction of the integrated stress response (ISR) regulon. Surprisingly, all stresses tested led to the production of the ISR transcription factor Gcn4, but not necessarily to transcription of ISR target genes. Furthermore, stresses result in differential levels of ribosome collisions, but these are not necessarily predictive of initiation repression as has been suggested in the model yeast.
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Affiliation(s)
- Corey M. Knowles
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA
| | - David Goich
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA
| | - Amanda L. M. Bloom
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA
| | - Murat C. Kalem
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA
| | - John C. Panepinto
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA
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37
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Gupta R, Hinnebusch AG. Differential requirements for P stalk components in activating yeast protein kinase Gcn2 by stalled ribosomes during stress. Proc Natl Acad Sci U S A 2023; 120:e2300521120. [PMID: 37043534 PMCID: PMC10120022 DOI: 10.1073/pnas.2300521120] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 03/13/2023] [Indexed: 04/13/2023] Open
Abstract
The General Amino Acid Control is a conserved response to amino acid starvation involving activation of protein kinase Gcn2, which phosphorylates eukaryotic initiation factor 2 (eIF2α) with attendant inhibition of global protein synthesis and increased translation of yeast transcriptional activator GCN4. Gcn2 can be activated by either amino acid starvation or conditions that stall elongating ribosomes without reducing aminoacylation of tRNA, but it is unclear whether distinct molecular mechanisms operate in these two circumstances. We identified three regimes that activate Gcn2 in yeast cells by starvation-independent (SI) ribosome-stalling: treatment with tigecycline, eliminating the sole gene encoding tRNAArgUCC, and depletion of translation termination factor eRF1. We further demonstrated requirements for the tRNA- and ribosome-binding domains of Gcn2, the positive effector proteins Gcn1/Gcn20, and the tethering of at least one of two distinct P1/P2 heterodimers to the uL10 subunit of the ribosomal P stalk, for detectable activation by SI-ribosome stalling. Remarkably, no tethered P1/P2 proteins were required for strong Gcn2 activation elicited by starvation for histidine or branched-chain amino acids isoleucine/valine. These results indicate that Gcn2 activation has different requirements for the P stalk depending on how ribosomes are stalled. We propose that accumulation of deacylated tRNAs in amino acid-starved cells can functionally substitute for the P stalk in binding to the histidyl-tRNA synthetase-like domain of Gcn2 for eIF2α kinase activation by ribosomes stalled with A sites devoid of the eEF1A∙GTP∙aminoacyl-tRNA ternary complex.
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Affiliation(s)
- Ritu Gupta
- Section on Nutrient Control of Gene Expression, Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD20892
| | - Alan G. Hinnebusch
- Section on Nutrient Control of Gene Expression, Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD20892
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38
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Weber SL, Hustedt K, Schnepel N, Visscher C, Muscher-Banse AS. Modulation of GCN2/eIF2α/ATF4 Pathway in the Liver and Induction of FGF21 in Young Goats Fed a Protein- and/or Phosphorus-Reduced Diet. Int J Mol Sci 2023; 24:ijms24087153. [PMID: 37108315 PMCID: PMC10138370 DOI: 10.3390/ijms24087153] [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: 03/07/2023] [Revised: 04/08/2023] [Accepted: 04/10/2023] [Indexed: 04/29/2023] Open
Abstract
Mammals respond to amino acid (AA) deficiency by initiating an AA response pathway (AAR) that involves the activation of general control nonderepressible 2 (GCN2), phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), and activation of transcription factor 4 (ATF4). In this study, the effects of protein (N) and/or phosphorus (P) restriction on the GCN2/eIF2α/ATF4 pathway in the liver and the induction of fibroblast growth factor 21 (FGF21) in young goats were investigated. An N-reduced diet resulted in a decrease in circulating essential AA (EAA) and an increase in non-essential AA (NEAA), as well as an increase in hepatic mRNA expression of GCN2 and ATF4 and protein expression of GCN2. Dietary N restriction robustly increased both hepatic FGF21 mRNA expression and circulating FGF21 levels. Accordingly, numerous significant correlations demonstrated the effects of the AA profile on the AAR pathway and confirmed an association. Furthermore, activation of the AAR pathway depended on the sufficient availability of P. When dietary P was restricted, the GCN2/eIF2α/ATF4 pathway was not initiated, and no increase in FGF21 was observed. These results illustrate how the AAR pathway responds to N- and/or P-reduced diets in ruminants, thus demonstrating the complexity of dietary component changes.
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Affiliation(s)
- Sarah L Weber
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
| | - Karin Hustedt
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
| | - Nadine Schnepel
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
| | - Christian Visscher
- Institute for Animal Nutrition, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
| | - Alexandra S Muscher-Banse
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
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Kohler V, Andréasson C. Reversible protein assemblies in the proteostasis network in health and disease. Front Mol Biosci 2023; 10:1155521. [PMID: 37021114 PMCID: PMC10067754 DOI: 10.3389/fmolb.2023.1155521] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 03/09/2023] [Indexed: 04/07/2023] Open
Abstract
While proteins populating their native conformations constitute the functional entities of cells, protein aggregates are traditionally associated with cellular dysfunction, stress and disease. During recent years, it has become clear that large aggregate-like protein condensates formed via liquid-liquid phase separation age into more solid aggregate-like particles that harbor misfolded proteins and are decorated by protein quality control factors. The constituent proteins of the condensates/aggregates are disentangled by protein disaggregation systems mainly based on Hsp70 and AAA ATPase Hsp100 chaperones prior to their handover to refolding and degradation systems. Here, we discuss the functional roles that condensate formation/aggregation and disaggregation play in protein quality control to maintain proteostasis and why it matters for understanding health and disease.
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Affiliation(s)
- Verena Kohler
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Claes Andréasson
- Department of Molecular Biosciences, Stockholm University, Stockholm, Sweden
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40
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Izadpanah A, Willingham K, Chandrasekar B, Alt EU, Izadpanah R. Unfolded protein response and angiogenesis in malignancies. Biochim Biophys Acta Rev Cancer 2023; 1878:188839. [PMID: 36414127 PMCID: PMC10167724 DOI: 10.1016/j.bbcan.2022.188839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 11/08/2022] [Accepted: 11/12/2022] [Indexed: 11/21/2022]
Abstract
Cellular stress, arising from accumulation of unfolded proteins, occurs frequently in rapidly proliferating cancer cells. This cellular stress, in turn, activates the unfolded protein response (UPR), an interconnected set of signal transduction pathways that alleviate the proteostatic stress. The UPR is implicated in cancer cell survival and proliferation through upregulation of pro-tumorigenic pathways that ultimately promote malignant metabolism and neoangiogenesis. Here, we reviewed mechanisms of signaling crosstalk between the UPR and angiogenesis pathways, as well as transmissible ER stress and the role in tumor growth and development. To characterize differences in UPR and UPR-mediated angiogenesis in malignancy, we employed a data mining approach using patient tumor data from The Cancer Genome Atlas (TCGA). The analysis of TCGA revealed differences in UPR between malignant samples versus their non-malignant counterparts.
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Affiliation(s)
- Amin Izadpanah
- Applied Stem Cell Laboratory, Department of Medicine/Heart and Vascular Institute, Tulane University School of Medicine, New Orleans, LA, USA
| | - Kurtis Willingham
- Applied Stem Cell Laboratory, Department of Medicine/Heart and Vascular Institute, Tulane University School of Medicine, New Orleans, LA, USA
| | - Bysani Chandrasekar
- Department of Medicine, University of Missouri School of Medicine and Harry S. Truman Memorial Veterans Hospital, Columbia, MO, USA
| | - Eckhard U Alt
- Applied Stem Cell Laboratory, Department of Medicine/Heart and Vascular Institute, Tulane University School of Medicine, New Orleans, LA, USA.
| | - Reza Izadpanah
- Applied Stem Cell Laboratory, Department of Medicine/Heart and Vascular Institute, Tulane University School of Medicine, New Orleans, LA, USA; Department of Surgery, Tulane University School of Medicine, New Orleans, LA, USA.
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41
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Greene ES, Maynard C, Mullenix G, Bedford M, Dridi S. Potential role of endoplasmic reticulum stress in broiler woody breast myopathy. Am J Physiol Cell Physiol 2023; 324:C679-C693. [PMID: 36717103 DOI: 10.1152/ajpcell.00275.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Although broiler (meat-type) chickens are one of the most efficient protein sources that supports the livelihoods and food security of billions of people worldwide, they are facing several challenges. Due to its unknown etiology and heavy economic impact, woody breast (WB) myopathy is one of the most challenging problems facing the poultry industry, and for which there is no effective solution. Here, using a primary chicken myotube culture model, we show that hypoxia and endoplasmic reticulum (ER) stress are an integral component of the etiology of the myopathy. Multiple components of the ER stress response are significantly upregulated in WB as compared with normal muscle, and this response was mimicked by hypoxic conditions in chicken primary myotube culture. In addition, apoptotic pathways were activated as indicated by increases in active caspase 3 protein levels in both WB-affected tissues and hypoxic myotube culture, and caspase 3 activity and apoptosis in hypoxic myotube culture. Finally, as a phenotypic hallmark of WB is enhanced fibrosis and increased collagen aggregation, here, we show that hypoxic conditions increase collagen 1A1 and 1A2 gene expression, as well as collagen 1 protein levels in primary myotubes. These effects were partially reversed by tauroursodeoxycholic acid (TUDCA), an ER-stress inhibitor, in myotube culture. Taken together, these findings indicate that hypoxia and ER stress are present in WB, hypoxia can upregulate the cell death arm of the unfolded protein response (UPR) and lead to collagen production in a culture model of WB. This opens new vistas for potential mechanistic targets for future effective interventions to mitigate this myopathy.
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Affiliation(s)
- Elizabeth S Greene
- Center of Excellence for Poultry Science, Division of Agriculture, University of Arkansas, Fayetteville, Arkansas, United States
| | - Clay Maynard
- Center of Excellence for Poultry Science, Division of Agriculture, University of Arkansas, Fayetteville, Arkansas, United States
| | - Garrett Mullenix
- Center of Excellence for Poultry Science, Division of Agriculture, University of Arkansas, Fayetteville, Arkansas, United States
| | | | - Sami Dridi
- Center of Excellence for Poultry Science, Division of Agriculture, University of Arkansas, Fayetteville, Arkansas, United States
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42
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Su Y, Xu C, Shea J, DeStephanis D, Su Z. Transcriptomic changes in single yeast cells under various stress conditions. BMC Genomics 2023; 24:88. [PMID: 36829151 PMCID: PMC9960639 DOI: 10.1186/s12864-023-09184-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/13/2023] [Indexed: 02/26/2023] Open
Abstract
BACKGROUND The stress response of Saccharomyces cerevisiae has been extensively studied in the past decade. However, with the advent of recent technology in single-cell transcriptome profiling, there is a new opportunity to expand and further understanding of the yeast stress response with greater resolution on a system level. To understand transcriptomic changes in baker's yeast S. cerevisiae cells under stress conditions, we sequenced 117 yeast cells under three stress treatments (hypotonic condition, glucose starvation and amino acid starvation) using a full-length single-cell RNA-Seq method. RESULTS We found that though single cells from the same treatment showed varying degrees of uniformity, technical noise and batch effects can confound results significantly. However, upon careful selection of samples to reduce technical artifacts and account for batch-effects, we were able to capture distinct transcriptomic signatures for different stress conditions as well as putative regulatory relationships between transcription factors and target genes. CONCLUSION Our results show that a full-length single-cell based transcriptomic analysis of the yeast may help paint a clearer picture of how the model organism responds to stress than do bulk cell population-based methods.
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Affiliation(s)
- Yangqi Su
- Department of Bioinformatics and Genomics, The University of North Carolina at Charlotte, 28223, Charlotte, NC, USA
| | - Chen Xu
- Department of Bioinformatics and Genomics, The University of North Carolina at Charlotte, 28223, Charlotte, NC, USA
| | - Jonathan Shea
- Department of Bioinformatics and Genomics, The University of North Carolina at Charlotte, 28223, Charlotte, NC, USA
| | - Darla DeStephanis
- Department of Bioinformatics and Genomics, The University of North Carolina at Charlotte, 28223, Charlotte, NC, USA
| | - Zhengchang Su
- Department of Bioinformatics and Genomics, The University of North Carolina at Charlotte, 28223, Charlotte, NC, USA.
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Volloch V, Rits-Volloch S. The Amyloid Cascade Hypothesis 2.0: Generalization of the Concept. J Alzheimers Dis Rep 2023; 7:21-35. [PMID: 36777328 PMCID: PMC9912825 DOI: 10.3233/adr-220079] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 12/09/2022] [Indexed: 12/31/2022] Open
Abstract
Recently, we proposed the Amyloid Cascade Hypothesis 2.0 (ACH2.0), a reformulation of the ACH. In the former, in contrast to the latter, Alzheimer's disease (AD) is driven by intraneuronal amyloid-β (iAβ) and occurs in two stages. In the first, relatively benign stage, Aβ protein precursor (AβPP)-derived iAβ activates, upon reaching a critical threshold, the AβPP-independent iAβ-generating pathway, triggering a devastating second stage resulting in neuronal death. While the ACH2.0 remains aligned with the ACH premise that Aβ is toxic, the toxicity is exerted because of intra- rather than extracellular Aβ. In this framework, a once-in-a-lifetime-only iAβ depletion treatment via transient activation of BACE1 and/or BACE2 (exploiting their Aβ-cleaving activities) or by any means appears to be the best therapeutic strategy for AD. Whereas the notion of differentially derived iAβ being the principal moving force at both AD stages is both plausible and elegant, a possibility remains that the second AD stage is enabled by an AβPP-derived iAβ-activated self-sustaining mechanism producing a yet undefined deleterious "substance X" (sX) which anchors the second AD stage. The present study generalizes the ACH2.0 by incorporating this possibility and shows that, in this scenario, the iAβ depletion therapy may be ineffective at symptomatic AD stages but fully retains its preventive potential for both AD and the aging-associated cognitive decline, which is defined in the ACH2.0 framework as the extended first stage of AD.
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Affiliation(s)
- Vladimir Volloch
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA,Correspondence to: Vladimir Volloch, Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA. and Sophia Rits-Volloch, Division of Molecular Medicine, Children’s Hospital, Boston, MA, USA. E-mail:
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Children’s Hospital, Boston, MA, USA,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
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Brownsword MJ, Locker N. A little less aggregation a little more replication: Viral manipulation of stress granules. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1741. [PMID: 35709333 PMCID: PMC10078398 DOI: 10.1002/wrna.1741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/29/2022] [Accepted: 05/05/2022] [Indexed: 01/31/2023]
Abstract
Recent exciting studies have uncovered how membrane-less organelles, also known as biocondensates, are providing cells with rapid response pathways, allowing them to re-organize their cellular contents and adapt to stressful conditions. Their assembly is driven by the phase separation of their RNAs and intrinsically disordered protein components into condensed foci. Among these, stress granules (SGs) are dynamic cytoplasmic biocondensates that form in response to many stresses, including activation of the integrated stress response or viral infections. SGs sit at the crossroads between antiviral signaling and translation because they concentrate signaling proteins and components of the innate immune response, in addition to translation machinery and stalled mRNAs. Consequently, they have been proposed to contribute to antiviral activities, and therefore are targeted by viral countermeasures. Equally, SGs components can be commandeered by viruses for their own efficient replication. Phase separation processes are an important component of the viral life cycle, for example, driving the assembly of replication factories or inclusion bodies. Therefore, in this review, we will outline the recent understanding of this complex interplay and tug of war between viruses, SGs, and their components. This article is categorized under: RNA in Disease and Development > RNA in Disease Translation > Regulation RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Matthew J. Brownsword
- Faculty of Health and Medical Sciences, School of Biosciences and MedicineUniversity of SurreyGuildfordSurreyUK
| | - Nicolas Locker
- Faculty of Health and Medical Sciences, School of Biosciences and MedicineUniversity of SurreyGuildfordSurreyUK
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Vivas W, Weis S. Tidy up - The unfolded protein response in sepsis. Front Immunol 2022; 13:980680. [PMID: 36341413 PMCID: PMC9632622 DOI: 10.3389/fimmu.2022.980680] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 10/06/2022] [Indexed: 11/23/2022] Open
Abstract
Pathogens, their toxic byproducts, and the subsequent immune reaction exert different forms of stress and damage to the tissue of the infected host. This stress can trigger specific transcriptional and post-transcriptional programs that have evolved to limit the pathogenesis of infectious diseases by conferring tissue damage control. If these programs fail, infectious diseases can take a severe course including organ dysfunction and damage, a phenomenon that is known as sepsis and which is associated with high mortality. One of the key adaptive mechanisms to counter infection-associated stress is the unfolded protein response (UPR), aiming to reduce endoplasmic reticulum stress and restore protein homeostasis. This is mediated via a set of diverse and complementary mechanisms, i.e. the reduction of protein translation, increase of protein folding capacity, and increase of polyubiquitination of misfolded proteins and subsequent proteasomal degradation. However, UPR is not exclusively beneficial since its enhanced or prolonged activation might lead to detrimental effects such as cell death. Thus, fine-tuning and time-restricted regulation of the UPR should diminish disease severity of infectious disease and improve the outcome of sepsis while not bearing long-term consequences. In this review, we describe the current knowledge of the UPR, its role in infectious diseases, regulation mechanisms, and further clinical implications in sepsis.
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Affiliation(s)
- Wolfgang Vivas
- Department of Anesthesiology and Intensive Care Medicine, Jena University Hospital, Friedrich Schiller University, Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (HKI), Jena, Germany
- *Correspondence: Wolfgang Vivas,
| | - Sebastian Weis
- Department of Anesthesiology and Intensive Care Medicine, Jena University Hospital, Friedrich Schiller University, Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (HKI), Jena, Germany
- Institute for Infectious Disease and Infection Control, Jena University Hospital, Friedrich Schiller University, Jena, Germany
- Center for Sepsis Control and Care, Jena University Hospital, Friedrich Schiller University, Jena, Germany
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Bottorff TA, Park H, Geballe AP, Subramaniam AR. Translational buffering by ribosome stalling in upstream open reading frames. PLoS Genet 2022; 18:e1010460. [PMID: 36315596 PMCID: PMC9648851 DOI: 10.1371/journal.pgen.1010460] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 11/10/2022] [Accepted: 10/04/2022] [Indexed: 11/05/2022] Open
Abstract
Upstream open reading frames (uORFs) are present in over half of all human mRNAs. uORFs can potently regulate the translation of downstream open reading frames through several mechanisms: siphoning away scanning ribosomes, regulating re-initiation, and allowing interactions between scanning and elongating ribosomes. However, the consequences of these different mechanisms for the regulation of protein expression remain incompletely understood. Here, we performed systematic measurements on the uORF-containing 5' UTR of the cytomegaloviral UL4 mRNA to test alternative models of uORF-mediated regulation in human cells. We find that a terminal diproline-dependent elongating ribosome stall in the UL4 uORF prevents decreases in main ORF protein expression when ribosome loading onto the mRNA is reduced. This uORF-mediated buffering is insensitive to the location of the ribosome stall along the uORF. Computational kinetic modeling based on our measurements suggests that scanning ribosomes dissociate rather than queue when they collide with stalled elongating ribosomes within the UL4 uORF. We identify several human uORFs that repress main ORF protein expression via a similar terminal diproline motif. We propose that ribosome stalls in uORFs provide a general mechanism for buffering against reductions in main ORF translation during stress and developmental transitions.
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Affiliation(s)
- Ty A. Bottorff
- Basic Sciences Division and Computational Biology Program of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
- Biological Physics, Structure and Design Graduate Program, University of Washington, Seattle, Washington, United States of America
| | - Heungwon Park
- Basic Sciences Division and Computational Biology Program of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Adam P. Geballe
- Human Biology and Clinical Research Divisions, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Arvind Rasi Subramaniam
- Basic Sciences Division and Computational Biology Program of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
- Biological Physics, Structure and Design Graduate Program, University of Washington, Seattle, Washington, United States of America
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Volloch V, Rits-Volloch S. The Amyloid Cascade Hypothesis 2.0: On the Possibility of Once-in-a-Lifetime-Only Treatment for Prevention of Alzheimer’s Disease and for Its Potential Cure at Symptomatic Stages. J Alzheimers Dis Rep 2022; 6:369-399. [PMID: 36072366 PMCID: PMC9397896 DOI: 10.3233/adr-220031] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 06/08/2022] [Indexed: 11/15/2022] Open
Abstract
We posit that Alzheimer’s disease (AD) is driven by amyloid-β (Aβ) generated in the amyloid-β protein precursor (AβPP) independent pathway activated by AβPP-derived Aβ accumulated intraneuronally in a life-long process. This interpretation constitutes the Amyloid Cascade Hypothesis 2.0 (ACH2.0). It defines a tandem intraneuronal-Aβ (iAβ)-anchored cascade occurrence: intraneuronally-accumulated, AβPP-derived iAβ triggers relatively benign cascade that activates the AβPP-independent iAβ-generating pathway, which, in turn, initiates the second, devastating cascade that includes tau pathology and leads to neuronal loss. The entire output of the AβPP-independent iAβ-generating pathway is retained intraneuronally and perpetuates the pathway’s operation. This process constitutes a self-propagating, autonomous engine that drives AD and ultimately kills its host cells. Once activated, the AD Engine is self-reliant and independent from Aβ production in the AβPP proteolytic pathway; operation of the former renders the latter irrelevant to the progression of AD and brands its manipulation for therapeutic purposes, such as BACE (beta-site AβPP-cleaving enzyme) inhibition, as futile. In the proposed AD paradigm, the only valid direct therapeutic strategy is targeting the engine’s components, and the most effective feasible approach appears to be the activation of BACE1 and/or of its homolog BACE2, with the aim of exploiting their Aβ-cleaving activities. Such treatment would collapse the iAβ population and ‘reset’ its levels below those required for the operation of the AD Engine. Any sufficiently selective iAβ-depleting treatment would be equally effective. Remarkably, this approach opens the possibility of a short-duration, once-in-a-lifetime-only or very infrequent, preventive or curative therapy for AD; this therapy would be also effective for prevention and treatment of the ‘common’ pervasive aging-associated cognitive decline. The ACH2.0 clarifies all ACH-unresolved inconsistencies, explains the widespread ‘resilience to AD’ phenomenon, predicts occurrences of a category of AD-afflicted individuals without excessive Aβ plaque load and of a novel type of familial insusceptibility to AD; it also predicts the lifespan-dependent inevitability of AD in humans if untreated preventively. The article details strategy and methodology to generate an adequate AD model and validate the hypothesis; the proposed AD model may also serve as a research and drug development platform.
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Affiliation(s)
- Vladimir Volloch
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Children’s Hospital, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
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Lahiri V, Metur SP, Hu Z, Song X, Mari M, Hawkins WD, Bhattarai J, Delorme-Axford E, Reggiori F, Tang D, Dengjel J, Klionsky DJ. Post-transcriptional regulation of ATG1 is a critical node that modulates autophagy during distinct nutrient stresses. Autophagy 2022; 18:1694-1714. [PMID: 34836487 PMCID: PMC9298455 DOI: 10.1080/15548627.2021.1997305] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 01/18/2023] Open
Abstract
Macroautophagy/autophagy is a highly conserved nutrient-recycling pathway that eukaryotes utilize to combat diverse stresses including nutrient depletion. Dysregulation of autophagy disrupts cellular homeostasis leading to starvation susceptibility in yeast and disease development in humans. In yeast, the robust autophagy response to starvation is controlled by the upregulation of ATG genes, via regulatory processes involving multiple levels of gene expression. Despite the identification of several regulators through genetic studies, the predominant mechanism of regulation modulating the autophagy response to subtle differences in nutrient status remains undefined. Here, we report the unexpected finding that subtle changes in nutrient availability can cause large differences in autophagy flux, governed by hitherto unknown post-transcriptional regulatory mechanisms affecting the expression of the key autophagyinducing kinase Atg1 (ULK1/ULK2 in mammals). We have identified two novel post-transcriptional regulators of ATG1 expression, the kinase Rad53 and the RNA-binding protein Ded1 (DDX3 in mammals). Furthermore, we show that DDX3 regulates ULK1 expression post-transcriptionally, establishing mechanistic conservation and highlighting the power of yeast biology in uncovering regulatory mechanisms that can inform therapeutic approaches.
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Affiliation(s)
- Vikramjit Lahiri
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Shree Padma Metur
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Zehan Hu
- Department of Biology, University of Fribourg, FribourgSwitzerland
| | - Xinxin Song
- Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Muriel Mari
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, GroningenThe Netherlands
| | - Wayne D. Hawkins
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Janakraj Bhattarai
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | | | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, GroningenThe Netherlands
| | - Daolin Tang
- Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Joern Dengjel
- Department of Biology, University of Fribourg, FribourgSwitzerland
| | - Daniel J. Klionsky
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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Stress- and metabolic responses of Candida albicans require Tor1 kinase N-terminal HEAT repeats. PLoS Pathog 2022; 18:e1010089. [PMID: 35687592 PMCID: PMC9223334 DOI: 10.1371/journal.ppat.1010089] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 06/23/2022] [Accepted: 05/12/2022] [Indexed: 11/19/2022] Open
Abstract
Whether to commit limited cellular resources toward growth and proliferation, or toward survival and stress responses, is an essential determination made by Target of Rapamycin Complex 1 (TORC1) for a eukaryotic cell in response to favorable or adverse conditions. Loss of TORC1 function is lethal. The TORC1 inhibitor rapamycin that targets the highly conserved Tor kinase domain kills fungal pathogens like Candida albicans, but is also severely toxic to human cells. The least conserved region of fungal and human Tor kinases are the N-terminal HEAT domains. We examined the role of the 8 most N-terminal HEAT repeats of C. albicans Tor1. We compared nutritional- and stress responses of cells that express a message for N-terminally truncated Tor1 from repressible tetO, with cells expressing wild type TOR1 from tetO or from the native promoter. Some but not all stress responses were significantly impaired by loss of Tor1 N-terminal HEAT repeats, including those to oxidative-, cell wall-, and heat stress; in contrast, plasma membrane stress and antifungal agents that disrupt plasma membrane function were tolerated by cells lacking this Tor1 region. Translation was inappropriately upregulated during oxidative stress in cells lacking N-terminal Tor1 HEAT repeats despite simultaneously elevated Gcn2 activity, while activation of the oxidative stress response MAP kinase Hog1 was weak. Conversely, these cells were unable to take advantage of favorable nutritional conditions by accelerating their growth. Consuming oxygen more slowly than cells containing wild type TOR1 alleles during growth in glucose, cells lacking N-terminal Tor1 HEAT repeats additionally were incapable of utilizing non-fermentable carbon sources. They were also hypersensitive to inhibitors of specific complexes within the respiratory electron transport chain, suggesting that inefficient ATP generation and a resulting dearth of nucleotide sugar building blocks for cell wall polysaccharides causes cell wall integrity defects in these mutants. Genome-wide expression analysis of cells lacking N-terminal HEAT repeats showed dysregulation of carbon metabolism, cell wall biosynthetic enzymes, translational machinery biosynthesis, oxidative stress responses, and hyphal- as well as white-opaque cell type-associated genes. Targeting fungal-specific Tor1 N-terminal HEAT repeats with small molecules might selectively abrogate fungal viability, especially when during infection multiple stresses are imposed by the host immune system. Whether growing harmlessly on our mucous membranes in competition with bacterial multitudes, or invading our tissues and bloodstream, the fungus Candida albicans must be capable of rapid growth when it finds abundant nutrients and favorable conditions. It must also be able to switch to stress- and survival mode when encountering host immune cells and when starving for nutrients. Tor1 kinase is the central regulator at the heart of these cellular decisions. As an essential protein, it is an attractive drug target. But the Tor1 kinase domain is very similar to its human counterpart, rendering its inhibitors like rapamycin toxic for humans. We identified a region of helical protein-protein interaction domains, the N-terminal HEAT repeats, as the least conserved part of C. albicans Tor1. Using genetic- and genome-wide expression analysis, we found that 8 N-terminal HEAT repeats are required for growth acceleration in nutrient-rich environments and for decreased translation in starvation- and stress conditions. This Tor1 region contributes to oxidative-, cell wall- and heat stress reponses, to hyphal growth and to respiration, but apparently not to plasma membrane stress endurance or fermentation. Small molecules that disrupt the protein-protein interactions mediated by this region could become fungal-selective inhibitors of Tor kinase.
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Pitera AP, Szaruga M, Peak‐Chew S, Wingett SW, Bertolotti A. Cellular responses to halofuginone reveal a vulnerability of the GCN2 branch of the integrated stress response. EMBO J 2022; 41:e109985. [PMID: 35466425 PMCID: PMC9156968 DOI: 10.15252/embj.2021109985] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 03/16/2022] [Accepted: 03/26/2022] [Indexed: 12/13/2022] Open
Abstract
Halofuginone (HF) is a phase 2 clinical compound that inhibits the glutamyl-prolyl-tRNA synthetase (EPRS) thereby inducing the integrated stress response (ISR). Here, we report that halofuginone indeed triggers the predicted canonical ISR adaptations, consisting of attenuation of protein synthesis and gene expression reprogramming. However, the former is surprisingly atypical and occurs to a similar magnitude in wild-type cells, cells lacking GCN2 and those incapable of phosphorylating eIF2α. Proline supplementation rescues the observed HF-induced changes indicating that they result from inhibition of EPRS. The failure of the GCN2-to-eIF2α pathway to elicit a measurable protective attenuation of translation initiation allows translation elongation defects to prevail upon HF treatment. Exploiting this vulnerability of the ISR, we show that cancer cells with increased proline dependency are more sensitive to halofuginone. This work reveals that the consequences of EPRS inhibition are more complex than anticipated and provides novel insights into ISR signaling, as well as a molecular framework to guide the targeted development of halofuginone as a therapeutic.
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