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Hammel A, Cucos LM, Caras I, Ionescu I, Tucureanu C, Tofan V, Costache A, Onu A, Hoepfner L, Hippler M, Neupert J, Popescu CI, Stavaru C, Branza-Nichita N, Bock R. The red alga Porphyridium as a host for molecular farming: Efficient production of immunologically active hepatitis C virus glycoprotein. Proc Natl Acad Sci U S A 2024; 121:e2400145121. [PMID: 38833465 PMCID: PMC11181018 DOI: 10.1073/pnas.2400145121] [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: 01/08/2024] [Accepted: 05/03/2024] [Indexed: 06/06/2024] Open
Abstract
Microalgae are promising production platforms for the cost-effective production of recombinant proteins. We have recently established that the red alga Porphyridium purpureum provides superior transgene expression properties, due to the episomal maintenance of transformation vectors as multicopy plasmids in the nucleus. Here, we have explored the potential of Porphyridium to synthesize complex pharmaceutical proteins to high levels. Testing expression constructs for a candidate subunit vaccine against the hepatitis C virus (HCV), we show that the soluble HCV E2 glycoprotein can be produced in transgenic algal cultures to high levels. The antigen undergoes faithful posttranslational modification by N-glycosylation and is recognized by conformationally selective antibodies, suggesting that it adopts a proper antigenic conformation in the endoplasmic reticulum of red algal cells. We also report the experimental determination of the structure of the N-glycan moiety that is attached to glycosylated proteins in Porphyridium. Finally, we demonstrate the immunogenicity of the HCV antigen produced in red algae when administered by injection as pure protein or by feeding of algal biomass.
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Affiliation(s)
- Alexander Hammel
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department of Organelle Biology, Biotechnology and Molecular Ecophysiology, D-14476Potsdam-Golm, Germany
| | - Lia-Maria Cucos
- Institute of Biochemistry of the Romanian Academy, Department of Viral Glycoproteins, 060031Bucharest, Romania
| | - Iuliana Caras
- ”Cantacuzino” Medico-Military National Research Institute, 050096Bucharest, Romania
| | - Irina Ionescu
- ”Cantacuzino” Medico-Military National Research Institute, 050096Bucharest, Romania
| | - Catalin Tucureanu
- ”Cantacuzino” Medico-Military National Research Institute, 050096Bucharest, Romania
| | - Vlad Tofan
- ”Cantacuzino” Medico-Military National Research Institute, 050096Bucharest, Romania
| | - Adriana Costache
- ”Cantacuzino” Medico-Military National Research Institute, 050096Bucharest, Romania
| | - Adrian Onu
- ”Cantacuzino” Medico-Military National Research Institute, 050096Bucharest, Romania
| | - Lara Hoepfner
- Institute of Plant Biology and Biotechnology, University of Münster, D-48143Münster, Germany
| | - Michael Hippler
- Institute of Plant Biology and Biotechnology, University of Münster, D-48143Münster, Germany
- Institute of Plant Science and Resources, Okayama University, Kurashiki710-0046, Japan
| | - Juliane Neupert
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department of Organelle Biology, Biotechnology and Molecular Ecophysiology, D-14476Potsdam-Golm, Germany
| | - Costin-Ioan Popescu
- Institute of Biochemistry of the Romanian Academy, Department of Viral Glycoproteins, 060031Bucharest, Romania
| | - Crina Stavaru
- ”Cantacuzino” Medico-Military National Research Institute, 050096Bucharest, Romania
| | - Norica Branza-Nichita
- Institute of Biochemistry of the Romanian Academy, Department of Viral Glycoproteins, 060031Bucharest, Romania
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department of Organelle Biology, Biotechnology and Molecular Ecophysiology, D-14476Potsdam-Golm, Germany
- NIBIO, Norwegian Institute of Bioeconomy Research, NO-1431 Ås, Norway
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2
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Thibault E, Brandizzi F. Post-translational modifications: emerging directors of cell-fate decisions during endoplasmic reticulum stress in Arabidopsis thaliana. Biochem Soc Trans 2024; 52:831-848. [PMID: 38600022 PMCID: PMC11088923 DOI: 10.1042/bst20231025] [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: 01/19/2024] [Revised: 03/23/2024] [Accepted: 04/02/2024] [Indexed: 04/12/2024]
Abstract
Homeostasis of the endoplasmic reticulum (ER) is critical for growth, development, and stress responses. Perturbations causing an imbalance in ER proteostasis lead to a potentially lethal condition known as ER stress. In ER stress situations, cell-fate decisions either activate pro-life pathways that reestablish homeostasis or initiate pro-death pathways to prevent further damage to the organism. Understanding the mechanisms underpinning cell-fate decisions in ER stress is critical for crop development and has the potential to enable translation of conserved components to ER stress-related diseases in metazoans. Post-translational modifications (PTMs) of proteins are emerging as key players in cell-fate decisions in situations of imbalanced ER proteostasis. In this review, we address PTMs orchestrating cell-fate decisions in ER stress in plants and provide evidence-based perspectives for where future studies may focus to identify additional PTMs involved in ER stress management.
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Affiliation(s)
- Ethan Thibault
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, U.S.A
- Department of Plant Biology, Michigan State University, East Lansing, MI, U.S.A
| | - Federica Brandizzi
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, U.S.A
- Department of Plant Biology, Michigan State University, East Lansing, MI, U.S.A
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, U.S.A
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3
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Rabeh K, Oubohssaine M, Hnini M. TOR in plants: Multidimensional regulators of plant growth and signaling pathways. JOURNAL OF PLANT PHYSIOLOGY 2024; 294:154186. [PMID: 38330538 DOI: 10.1016/j.jplph.2024.154186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 01/20/2024] [Accepted: 01/22/2024] [Indexed: 02/10/2024]
Abstract
Target Of Rapamycin (TOR) represents a ubiquitous kinase complex that has emerged as a central regulator of cell growth and metabolism in nearly all eukaryotic organisms. TOR is an evolutionarily conserved protein kinase, functioning as a central signaling hub that integrates diverse internal and external cues to regulate a multitude of biological processes. These processes collectively exert significant influence on plant growth, development, nutrient assimilation, photosynthesis, fruit ripening, and interactions with microorganisms. Within the plant domain, the TOR complex comprises three integral components: TOR, RAPTOR, and LST8. This comprehensive review provides insights into various facets of the TOR protein, encompassing its origin, structure, function, and the regulatory and signaling pathways operative in photosynthetic organisms. Additionally, we explore future perspectives related to this pivotal protein kinase.
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Affiliation(s)
- Karim Rabeh
- Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnologies, Biodiversity and Environment, Faculty of Sciences, Mohammed V University, Rabat, Morocco.
| | - Malika Oubohssaine
- Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnologies, Biodiversity and Environment, Faculty of Sciences, Mohammed V University, Rabat, Morocco
| | - Mohamed Hnini
- Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnologies, Biodiversity and Environment, Faculty of Sciences, Mohammed V University, Rabat, Morocco
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4
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Castillo-Medina RE, Islas-Flores T, Morales-Ruiz E, Villanueva MA. Biochemical and molecular characterization of the SBiP1 chaperone from Symbiodinium microadriaticum CassKB8 and light parameters that modulate its phosphorylation. PLoS One 2023; 18:e0293299. [PMID: 37862348 PMCID: PMC10588850 DOI: 10.1371/journal.pone.0293299] [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: 07/21/2023] [Accepted: 10/10/2023] [Indexed: 10/22/2023] Open
Abstract
The coding and promoter region sequences from the BiP-like protein SBiP1 from Symbiodinium microadriaticum CassKB8 were obtained by PCR, sequenced and compared with annotated sequences. The nucleotides corresponding to the full sequence were correctly annotated and the main SBiP1 features determined at the nucleotide and amino acid level. The translated protein was organized into the typical domains of the BiP/HSP70 family including a signal peptide, a substrate- and a nucleotide-binding domain, and an ER localization sequence. Conserved motifs included a highly conserved Thr513 phosphorylation site and two ADP-ribosylation sites from eukaryotic BiP's. Molecular modeling showed the corresponding domain regions and main exposed post-translational target sites in its three-dimensional structure, which also closely matched Homo sapiens BiP further indicating that it indeed corresponds to a BiP/HSP70 family protein. The gene promoter region showed at least eight light regulation-related sequences consistent with the molecule being highly phosphorylated in Thr under dark conditions and dephosphorylated upon light stimuli. We tested light parameter variations that could modulate the light mediated phosphorylation effect and found that SBiP1 Thr dephosphorylation was only significantly detected after 15-30 min light stimulation. Such light-induced dephosphorylation was observed even when dichlorophenyl dimethyl urea, a photosynthesis inhibitor, was also present in the cells during the light stimulation. Dephosphorylation occurred indistinctly under red, yellow, blue or the full visible light spectra. In additon, it was observed at a light intensity of as low as 1 μmole photon m-2 s-1. Our results indicate that: a) SBiP1 is a chaperone belonging to the BiP/HSP70 family proteins; b) its light-modulated phosphorylation/dephosphorylation most likely functions as an activity switch for the chaperone; c) this light-induced modulation occurs relatively slow but is highly sensitive to the full spectrum of visible light; and d) the light induced Thr dephosphorylation is independent of photosynthetic activity in these cells.
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Affiliation(s)
- Raúl Eduardo Castillo-Medina
- Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México-UNAM, Puerto Morelos, Quintana Roo, México
| | - Tania Islas-Flores
- Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México-UNAM, Puerto Morelos, Quintana Roo, México
| | - Estefanía Morales-Ruiz
- Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México-UNAM, Puerto Morelos, Quintana Roo, México
| | - Marco A. Villanueva
- Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México-UNAM, Puerto Morelos, Quintana Roo, México
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5
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Ingargiola C, Jéhanno I, Forzani C, Marmagne A, Broutin J, Clément G, Leprince AS, Meyer C. The Arabidopsis Target of Rapamycin (TOR) kinase regulates ammonium assimilation and glutamine metabolism. PLANT PHYSIOLOGY 2023:kiad216. [PMID: 37042394 DOI: 10.1093/plphys/kiad216] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 03/01/2023] [Accepted: 04/11/2023] [Indexed: 06/19/2023]
Abstract
In eukaryotes, Target of Rapamycin (TOR) is a well conserved kinase that controls cell metabolism and growth in response to nutrients and environmental factors. Nitrogen (N) is an essential element for plants, and TOR functions as a crucial N and amino acid sensor in animals and yeast. However, knowledge on the connections between TOR and the overall N metabolism and assimilation in plants is still limited. In this study, we investigated the regulation of TOR in Arabidopsis (Arabidopsis thaliana) by the N source as well as the impact of TOR deficiency on N metabolism. Inhibition of TOR globally decreased ammonium uptake while triggering a massive accumulation of amino acids, such as Gln, but also of polyamines. Consistently, TOR complex mutants were hypersensitive to Gln. We also showed that the glutamine synthetase inhibitor glufosinate abolishes Gln accumulation resulting from TOR inhibition and improves the growth of TOR complex mutants. These results suggest that a high level of Gln contributes to the reduction in plant growth resulting from TOR inhibition. Glutamine synthetase activity was reduced by TOR inhibition while the enzyme amount increased. In conclusion, our findings show that the TOR pathway is intimately connected to N metabolism and that a decrease in TOR activity results in glutamine synthetase-dependent Gln and amino acid accumulation.
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Affiliation(s)
- Camille Ingargiola
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France
| | - Isabelle Jéhanno
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France
| | - Céline Forzani
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France
| | - Anne Marmagne
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France
| | - Justine Broutin
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France
| | - Gilles Clément
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France
| | - Anne-Sophie Leprince
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France
- Faculté des Sciences et d'Ingénierie, Sorbonne Université, UFR 927, 4 Place Jussieu, 75252 Paris, France
| | - Christian Meyer
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France
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6
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Mallén-Ponce MJ, Pérez-Pérez ME, Crespo JL. Deciphering the function and evolution of the target of rapamycin signaling pathway in microalgae. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:6993-7005. [PMID: 35710309 PMCID: PMC9664231 DOI: 10.1093/jxb/erac264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 06/16/2022] [Indexed: 06/15/2023]
Abstract
Microalgae constitute a highly diverse group of photosynthetic microorganisms that are widely distributed on Earth. The rich diversity of microalgae arose from endosymbiotic events that took place early in the evolution of eukaryotes and gave rise to multiple lineages including green algae, the ancestors of land plants. In addition to their fundamental role as the primary source of marine and freshwater food chains, microalgae are essential producers of oxygen on the planet and a major biotechnological target for sustainable biofuel production and CO2 mitigation. Microalgae integrate light and nutrient signals to regulate cell growth. Recent studies identified the target of rapamycin (TOR) kinase as a central regulator of cell growth and a nutrient sensor in microalgae. TOR promotes protein synthesis and regulates processes that are induced under nutrient stress such as autophagy and the accumulation of triacylglycerol and starch. A detailed analysis of representative genomes from the entire microalgal lineage revealed that the highly conserved central components of the TOR pathway are likely to have been present in the last eukaryotic common ancestor, and the loss of specific TOR signaling elements at an early stage in the evolution of microalgae. Here we examine the evolutionary conservation of TOR signaling components in diverse microalgae and discuss recent progress of this signaling pathway in these organisms.
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Affiliation(s)
- Manuel J Mallén-Ponce
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Sevilla, Spain
| | - María Esther Pérez-Pérez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Sevilla, Spain
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7
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Caló G, De Marco MA, Salerno GL, Martínez-Noël GMA. TOR signaling in the green picoalga Ostreococcus tauri. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 323:111390. [PMID: 35868347 DOI: 10.1016/j.plantsci.2022.111390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/29/2022] [Accepted: 07/15/2022] [Indexed: 06/15/2023]
Abstract
Target of rapamycin (TOR) is a master regulator that controls growth and metabolism by integrating external and internal signals. Although there was a great progress in the study of TOR in plants and in the model alga Chlamydomonas, scarce data are available in other green algae. Thus, in this work we studied TOR signaling in Ostreococcus tauri, the smallest free-living eukaryote described to date. This picoalga is particularly important because it has a key site at the base of the green lineage and is part of the marine phytoplankton, contributing to global photosynthesis. We investigated OtTOR complex in silico and experimentally, by using first- and second-generation TOR inhibitors, such as rapamycin and PP242. We analyzed the effect of TOR down-regulation on cell growth and on the accumulation of carbon reserves. The results showed that O. tauri responds to TOR inhibitors more similarly to plants than to Chlamydomonas, being PP242 a valuable tool to study this pathway. Besides, Ottor expression analysis revealed that the kinase is dynamically regulated under nutritional stress. Our data indicate that TOR signaling is conserved in O. tauri and we propose this alga as a good and simple model for studying TOR kinase and its regulation.
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Affiliation(s)
- Gonzalo Caló
- INBIOTEC, Vieytes, 3103, 7600 Mar del Plata, Argentina; FIBA, Vieytes 3103, 7600 Mar del Plata, Argentina
| | - María Agustina De Marco
- INBIOTEC, Vieytes, 3103, 7600 Mar del Plata, Argentina; FIBA, Vieytes 3103, 7600 Mar del Plata, Argentina
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Bin-Jumah MN, Nadeem MS, Gilani SJ, Al-Abbasi FA, Ullah I, Alzarea SI, Ghoneim MM, Alshehri S, Uddin A, Murtaza BN, Kazmi I. Genes and Longevity of Lifespan. Int J Mol Sci 2022; 23:1499. [PMID: 35163422 PMCID: PMC8836117 DOI: 10.3390/ijms23031499] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/04/2022] [Accepted: 01/26/2022] [Indexed: 12/12/2022] Open
Abstract
Aging is a complex process indicated by low energy levels, declined physiological activity, stress induced loss of homeostasis leading to the risk of diseases and mortality. Recent developments in medical sciences and an increased availability of nutritional requirements has significantly increased the average human lifespan worldwide. Several environmental and physiological factors contribute to the aging process. However, about 40% human life expectancy is inherited among generations, many lifespan associated genes, genetic mechanisms and pathways have been demonstrated during last decades. In the present review, we have evaluated many human genes and their non-human orthologs established for their role in the regulation of lifespan. The study has included more than fifty genes reported in the literature for their contributions to the longevity of life. Intact genomic DNA is essential for the life activities at the level of cell, tissue, and organ. Nucleic acids are vulnerable to oxidative stress, chemotherapies, and exposure to radiations. Efficient DNA repair mechanisms are essential for the maintenance of genomic integrity, damaged DNA is not replicated and transferred to next generations rather the presence of deleterious DNA initiates signaling cascades leading to the cell cycle arrest or apoptosis. DNA modifications, DNA methylation, histone methylation, histone acetylation and DNA damage can eventually lead towards apoptosis. The importance of calorie restriction therapy in the extension of lifespan has also been discussed. The role of pathways involved in the regulation of lifespan such as DAF-16/FOXO (forkhead box protein O1), TOR and JNK pathways has also been particularized. The study provides an updated account of genetic factors associated with the extended lifespan and their interactive contributory role with cellular pathways.
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Affiliation(s)
- May Nasser Bin-Jumah
- Biology Department, College of Science, Princess Nourah Bint Abdulrahman University, Riyadh 11671, Saudi Arabia;
- Environment and Biomaterial Unit, Health Sciences Research Center, Princess Nourah Bint Abdulrahman University, Riyadh 11671, Saudi Arabia
| | - Muhammad Shahid Nadeem
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
| | - Sadaf Jamal Gilani
- Department of Basic Health Sciences, Princess Nourah Bint Abdulrahman University, Riyadh 11671, Saudi Arabia;
| | - Fahad A. Al-Abbasi
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
| | - Inam Ullah
- Institute of Molecular Biology and Biotechnology, The University of Lahore, Lahore 54000, Pakistan;
| | - Sami I. Alzarea
- Department of Pharmacology, College of Pharmacy, Jouf University, Sakaka 72341, Saudi Arabia;
| | - Mohammed M. Ghoneim
- Department of Pharmacy Practice, College of Pharmacy, AlMaarefa University, Ad Diriyah 13713, Saudi Arabia;
| | - Sultan Alshehri
- Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia;
| | - Aziz Uddin
- Department of Biotechnology and Genetic Engineering, Hazara University, Mansehra 21300, Pakistan;
| | - Bibi Nazia Murtaza
- Department of Zoology, Abbottabad University of Science and Technology (AUST), Abbottabad 22310, Pakistan;
| | - Imran Kazmi
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
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9
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Abstract
The target of rapamycin (TOR) kinase is a master regulator that integrates nutrient signals to promote cell growth in all eukaryotes. It is well established that amino acids and glucose are major regulators of TOR signaling in yeast and metazoan, but whether and how TOR responds to carbon availability in photosynthetic organisms is less understood. In this study, we showed that photosynthetic assimilation of CO2 by the Calvin-Benson-Bassham (CBB) cycle regulates TOR activity in the model single-celled microalga Chlamydomonas reinhardtii Stimulation of CO2 fixation boosted TOR activity, whereas inhibition of the CBB cycle and photosynthesis down-regulated TOR. We uncovered a tight link between TOR activity and the endogenous level of a set of amino acids including Ala, Glu, Gln, Leu, and Val through the modulation of CO2 fixation and the use of amino acid synthesis inhibitors. Moreover, the finding that the Chlamydomonas starch-deficient mutant sta6 displayed disproportionate TOR activity and high levels of most amino acids, particularly Gln, further connected carbon assimilation and amino acids to TOR signaling. Thus, our results showed that CO2 fixation regulates TOR signaling, likely through the synthesis of key amino acids.
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Mugume Y, Kazibwe Z, Bassham DC. Target of Rapamycin in Control of Autophagy: Puppet Master and Signal Integrator. Int J Mol Sci 2020; 21:ijms21218259. [PMID: 33158137 PMCID: PMC7672647 DOI: 10.3390/ijms21218259] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/01/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023] Open
Abstract
The target of rapamycin (TOR) is an evolutionarily-conserved serine/threonine kinase that senses and integrates signals from the environment to coordinate developmental and metabolic processes. TOR senses nutrients, hormones, metabolites, and stress signals to promote cell and organ growth when conditions are favorable. However, TOR is inhibited when conditions are unfavorable, promoting catabolic processes such as autophagy. Autophagy is a macromolecular degradation pathway by which cells degrade and recycle cytoplasmic materials. TOR negatively regulates autophagy through phosphorylation of ATG13, preventing activation of the autophagy-initiating ATG1-ATG13 kinase complex. Here we review TOR complex composition and function in photosynthetic and non-photosynthetic organisms. We also review recent developments in the identification of upstream TOR activators and downstream effectors of TOR. Finally, we discuss recent developments in our understanding of the regulation of autophagy by TOR in photosynthetic organisms.
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11
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Ingargiola C, Turqueto Duarte G, Robaglia C, Leprince AS, Meyer C. The Plant Target of Rapamycin: A Conduc TOR of Nutrition and Metabolism in Photosynthetic Organisms. Genes (Basel) 2020; 11:genes11111285. [PMID: 33138108 PMCID: PMC7694126 DOI: 10.3390/genes11111285] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 12/15/2022] Open
Abstract
Living organisms possess many mechanisms to sense nutrients and favorable conditions, which allow them to grow and develop. Photosynthetic organisms are very diverse, from green unicellular algae to multicellular flowering plants, but most of them are sessile and thus unable to escape from the biotic and abiotic stresses they experience. The Target of Rapamycin (TOR) signaling pathway is conserved in all eukaryotes and acts as a central regulatory hub between growth and extrinsic factors, such as nutrients or stress. However, relatively little is known about the regulations and roles of this pathway in plants and algae. Although some features of the TOR pathway seem to have been highly conserved throughout evolution, others clearly differ in plants, perhaps reflecting adaptations to different lifestyles and the rewiring of this primordial signaling module to adapt to specific requirements. Indeed, TOR is involved in plant responses to a vast array of signals including nutrients, hormones, light, stresses or pathogens. In this review, we will summarize recent studies that address the regulations of TOR by nutrients in photosynthetic organisms, and the roles of TOR in controlling important metabolic pathways, highlighting similarities and differences with the other eukaryotes.
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Affiliation(s)
- Camille Ingargiola
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France; (C.I.); (G.T.D.); (A.-S.L.)
| | - Gustavo Turqueto Duarte
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France; (C.I.); (G.T.D.); (A.-S.L.)
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam, Germany
| | - Christophe Robaglia
- Laboratoire de Génétique et Biophysique des Plantes, Faculté des Sciences de Luminy, UMR 7265, CEA, CNRS, BIAM, Aix Marseille Université, 13009 Marseille, France;
| | - Anne-Sophie Leprince
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France; (C.I.); (G.T.D.); (A.-S.L.)
- Faculté des Sciences et d’Ingénierie, Sorbonne Université, UFR 927, 4 Place Jussieu, 75252 Paris, France
| | - Christian Meyer
- Institut Jean-Pierre Bourgin (IJPB), INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France; (C.I.); (G.T.D.); (A.-S.L.)
- Correspondence:
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12
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Upadhyaya S, Agrawal S, Gorakshakar A, Rao BJ. TOR kinase activity in Chlamydomonas reinhardtii is modulated by cellular metabolic states. FEBS Lett 2020; 594:3122-3141. [PMID: 32677084 DOI: 10.1002/1873-3468.13888] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 11/28/2019] [Accepted: 11/28/2019] [Indexed: 12/25/2022]
Abstract
Target of rapamycin (TOR) kinase is a sensor and a central integrator of internal and external metabolic cues. However, in algae and in higher plants, the components of TOR kinase signaling are yet to be characterized. Here, we establish an assay system to study TOR kinase activity in Chlamydomonas reinhardtii using the phosphorylation status of its putative downstream target, CrS6K. Using this assay, we probe the modulation of cellular TOR kinase activity under various physiological states such as photoautotrophy, heterotrophy, mixotrophy, and nitrogen (N) starvation. Importantly, we uncover that excess acetate in the medium leads to high cellular reactive oxygen species levels, triggering autophagy and a concomitant drop in TOR kinase activity in a dose-dependent manner, thus leading to a N-starvation-like cellular phenotype, even when nitrogen is present.
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Affiliation(s)
- Shivani Upadhyaya
- Department of Biological Sciences, Tata Institute of Fundamental Research (TIFR), Mumbai, India
| | - Shreya Agrawal
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Anmol Gorakshakar
- School of Biosciences and Technology, VIT University, Vellore, India
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13
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Pancha I, Chokshi K, Tanaka K, Imamura S. Microalgal Target of Rapamycin (TOR): A Central Regulatory Hub for Growth, Stress Response and Biomass Production. PLANT & CELL PHYSIOLOGY 2020; 61:675-684. [PMID: 32105317 DOI: 10.1093/pcp/pcaa023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 02/17/2020] [Indexed: 06/10/2023]
Abstract
Target of rapamycin (TOR) is an evolutionarily conserved protein kinase that plays an important role in the regulation of cell growth and the sensing of nutrient and energy status in eukaryotes. In yeasts and mammals, the roles of TOR have been very well described and various functions of TOR signaling in plant lineages have also been revealed over the past 20 years. In the case of microalgae, the functions of TOR have been primarily studied in the model green alga Chlamydomonas reinhardtii and were summarized in an earlier single review article. However, the recent development of tools for the functional analysis of TOR has helped to reveal the involvement of TOR in various functions, including autophagy, transcription, translation, accumulation of energy storage molecules, etc., in microalgae. In the present review, we discuss recent novel findings relating to TOR signaling and its roles in microalgae along with relevant information on land plants and also provide details of topics that must be addressed in future studies to reveal how TOR regulates various physiological functions in microalgae.
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Affiliation(s)
- Imran Pancha
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan
- Department of Biology, SRM University-AP, Amaravati, Andhra Pradesh 522502, India
| | - Kaumeel Chokshi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan
| | - Sousuke Imamura
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan
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14
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15
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Couso I, Pérez-Pérez ME, Ford MM, Martínez-Force E, Hicks LM, Umen JG, Crespo JL. Phosphorus Availability Regulates TORC1 Signaling via LST8 in Chlamydomonas. THE PLANT CELL 2020; 32:69-80. [PMID: 31712405 PMCID: PMC6961625 DOI: 10.1105/tpc.19.00179] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 10/07/2019] [Accepted: 11/08/2019] [Indexed: 05/05/2023]
Abstract
Target of rapamycin complex 1 (TORC1) is a central regulator of cell growth. It balances anabolic and catabolic processes in response to nutrients, growth factors, and energy availability. Nitrogen- and carbon-containing metabolites have been shown to activate TORC1 in yeast, animals, and plants. Here, we show that phosphorus (P) regulates TORC1 signaling in the model green alga Chlamydomonas (Chlamydomonas reinhardtii) via LST8, a conserved TORC1 subunit that interacts with the kinase domain of TOR. P starvation results in a sharp decrease in LST8 abundance and downregulation of TORC1 activity. A hypomorphic lst8 mutation resulted in decreased LST8 abundance, and it both reduced TORC1 signaling and altered the cellular response to P starvation. Additionally, we found that LST8 levels and TORC1 activity were not properly regulated in a mutant defective in the transcription factor PSR1, which is the major mediator of P deprivation responses in Chlamydomonas. Unlike wild-type cells, the psr1 mutant failed to downregulate LST8 abundance and TORC1 activity when under P limitation. These results identify PSR1 as an upstream regulator of TORC1 and demonstrate that TORC1 is a key component in P signaling in Chlamydomonas.
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Affiliation(s)
- Inmaculada Couso
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, 41092 Sevilla, Spain
| | - María Esther Pérez-Pérez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, 41092 Sevilla, Spain
| | - Megan M Ford
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Enrique Martínez-Force
- Instituto de la Grasa (Consejo Superior de Investigaciones Científicas), Edificio 46, Campus Universitario Pablo de Olavide, 41013 Sevilla, Spain
| | - Leslie M Hicks
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - James G Umen
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
| | - José L Crespo
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, 41092 Sevilla, Spain
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16
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Mubeen U, Giavalisco P, Caldana C. TOR inhibition interrupts the metabolic homeostasis by shifting the carbon-nitrogen balance in Chlamydomonas reinhardtii. PLANT SIGNALING & BEHAVIOR 2019; 14:1670595. [PMID: 31583958 PMCID: PMC6804693 DOI: 10.1080/15592324.2019.1670595] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 09/13/2019] [Accepted: 09/17/2019] [Indexed: 06/10/2023]
Abstract
The allocation of nutrient resources to growth and metabolism is an essential function for controlling biomass accumulation in photoautotrophic organisms. One essential protein complex involved in this process is the target of rapamycin (TOR) kinase. It has been shown that the inhibition of TOR leads to a considerable upsurge in the amino acid levels. This molecular phenotype relies mainly on the availability of light, carbon (C) and nitrogen (N). To validate the time-resolved response of C and N metabolites, we used a targeted gas chromatography mass spectrometery (GC-MS)-based metabolomic approach, where we examined the response of Chlamydomonas reinhardtii upon TOR inhibition under C-limited condition, namely extended darkness. Contrary to C-supplemented conditions, the rapid increase in the amino acid levels is suppressed almost completely 4 h after TOR inhibition, confirming that C supply is essential to raise the amino acid levels mediated by their de novo synthesis. An exception to this observation was the levels of aspartate, which is presumably synthesized via the anaplerotic pathway. In agreement with previous reports, TOR repression, under these C-limited conditions, leads to a significant reduction in the C/N ratio, corroborating with the crucial role of the pathway in maintaining the metabolic balance of the cells and consequently propelling growth.
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Affiliation(s)
- Umarah Mubeen
- Molecular Physiology Department, Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | | | - Camila Caldana
- Molecular Physiology Department, Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
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17
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Ford MM, Smythers AL, McConnell EW, Lowery SC, Kolling DRJ, Hicks LM. Inhibition of TOR in Chlamydomonas reinhardtii Leads to Rapid Cysteine Oxidation Reflecting Sustained Physiological Changes. Cells 2019; 8:cells8101171. [PMID: 31569396 PMCID: PMC6829209 DOI: 10.3390/cells8101171] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 09/16/2019] [Accepted: 09/26/2019] [Indexed: 12/16/2022] Open
Abstract
The target of rapamycin (TOR) kinase is a master metabolic regulator with roles in nutritional sensing, protein translation, and autophagy. In Chlamydomonas reinhardtii, a unicellular green alga, TOR has been linked to the regulation of increased triacylglycerol (TAG) accumulation, suggesting that TOR or a downstream target(s) is responsible for the elusive “lipid switch” in control of increasing TAG accumulation under nutrient limitation. However, while TOR has been well characterized in mammalian systems, it is still poorly understood in photosynthetic systems, and little work has been done to show the role of oxidative signaling in TOR regulation. In this study, the TOR inhibitor AZD8055 was used to relate reversible thiol oxidation to the physiological changes seen under TOR inhibition, including increased TAG content. Using oxidized cysteine resin-assisted capture enrichment coupled with label-free quantitative proteomics, 401 proteins were determined to have significant changes in oxidation following TOR inhibition. These oxidative changes mirrored characterized physiological modifications, supporting the role of reversible thiol oxidation in TOR regulation of TAG production, protein translation, carbohydrate catabolism, and photosynthesis through the use of reversible thiol oxidation. The delineation of redox-controlled proteins under TOR inhibition provides a framework for further characterization of the TOR pathway in photosynthetic eukaryotes.
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Affiliation(s)
- Megan M Ford
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Amanda L Smythers
- Department of Chemistry, Marshall University, Huntington, WV 25755, USA.
| | - Evan W McConnell
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Sarah C Lowery
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | | | - Leslie M Hicks
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Castillo-Medina RE, Islas-Flores T, Villanueva MA. Phosphorylation/dephosphorylation response to light stimuli of Symbiodinium proteins: specific light-induced dephosphorylation of an HSP-like 75 kDa protein from S. microadriaticum. PeerJ 2019; 7:e7406. [PMID: 31423357 PMCID: PMC6694782 DOI: 10.7717/peerj.7406] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 07/03/2019] [Indexed: 12/30/2022] Open
Abstract
Background Some genera of the family Symbiodiniaceae establish mutualistic endosymbioses with various marine invertebrates, with coral being the most important ecologically. Little is known about the biochemical communication of this association and the perception and translation of signals from the environment in the symbiont. However, specific phosphorylation/dephosphorylation processes are fundamental for the transmission of external signals to activate physiological responses. In this work, we searched phosphorylatable proteins in amino acids of Ser, Thr and Tyr from three species of the family Symbiodiniaceae, Symbiodinium kawagutii, Symbiodinium sp. Mf11 and Symbiodinium microadriaticum. Methods We used specific antibodies to the phosphorylated aminoacids pSer, pThr and pTyr to identify proteins harboring them in total extracts from three species of Symbiodinium in culture. Extractions were carried out on logarithmic phase growing cultures under a 12 h light/dark photoperiod. Various light/dark, nutritional and other stimuli were applied to the cultures prior to the extractions, and proteins were subjected to SDS-PAGE and western immunoblotting. Partial peptide sequencing was carried out by MALDI-TOF on specific protein spots separated by 2D electrophoresis. Results At 4 h of the light cycle, several Thr-phosphorylated proteins were consistently detected in the three species suggesting a genus-dependent expression; however, most Ser- and Tyr-phosphorylated proteins were species-specific. Analysis of protein extracts of S. microadriaticum cultures demonstrated that the level of phosphorylation of two Thr-phosphorylated proteins with molecular weights of 43 and 75 kDa, responded inversely to a light stimulus. The 43 kDa protein, originally weakly Thr-phosphorylated when the cells were previously adapted to their 12 h dark cycle, underwent an increase in Thr phosphorylation when stimulated for 30 min with light. On the other hand, the 75 kDa protein, which was significantly Thr-phosphorylated in the dark, underwent dephosphorylation in Thr after 30 min of the light stimulus. The phosphorylation response of the 43 kDa protein only occurred in S. microadriaticum, whereas the dephosphorylation of the 75 kDa protein occurred in the three species studied suggesting a general response. The 75 kDa protein was separated on 2D gels as two isoforms and the sequenced spots corresponded to a BiP-like protein of the HSP70 protein family. The presence of differential phosphorylations on these proteins after a light stimulus imply important light-regulated physiological processes in these organisms.
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Affiliation(s)
- Raúl E Castillo-Medina
- Posgrado en Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Delegación Coyoacán, Ciudad Universitaria, Ciudad de México, México.,Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología-UNAM, Puerto Morelos, Quintana Roo, México
| | - Tania Islas-Flores
- Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología-UNAM, Puerto Morelos, Quintana Roo, México
| | - Marco A Villanueva
- Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología-UNAM, Puerto Morelos, Quintana Roo, México
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Jamsheer K M, Jindal S, Laxmi A. Evolution of TOR-SnRK dynamics in green plants and its integration with phytohormone signaling networks. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:2239-2259. [PMID: 30870564 DOI: 10.1093/jxb/erz107] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/26/2019] [Indexed: 05/07/2023]
Abstract
The target of rapamycin (TOR)-sucrose non-fermenting 1 (SNF1)-related protein kinase 1 (SnRK1) signaling is an ancient regulatory mechanism that originated in eukaryotes to regulate nutrient-dependent growth. Although the TOR-SnRK1 signaling cascade shows highly conserved functions among eukaryotes, studies in the past two decades have identified many important plant-specific innovations in this pathway. Plants also possess SnRK2 and SnRK3 kinases, which originated from the ancient SnRK1-related kinases and have specialized roles in controlling growth, stress responses and nutrient homeostasis in plants. Recently, an integrative picture has started to emerge in which different SnRKs and TOR kinase are highly interconnected to control nutrient and stress responses of plants. Further, these kinases are intimately involved with phytohormone signaling networks that originated at different stages of plant evolution. In this review, we highlight the evolution and divergence of TOR-SnRK signaling components in plants and their communication with each other as well as phytohormone signaling to fine-tune growth and stress responses in plants.
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Affiliation(s)
- Muhammed Jamsheer K
- Amity Food & Agriculture Foundation, Amity University Uttar Pradesh, Noida, India
| | - Sunita Jindal
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
| | - Ashverya Laxmi
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
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20
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Pancha I, Shima H, Higashitani N, Igarashi K, Higashitani A, Tanaka K, Imamura S. Target of rapamycin-signaling modulates starch accumulation via glycogenin phosphorylation status in the unicellular red alga Cyanidioschyzon merolae. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 97:485-499. [PMID: 30351485 DOI: 10.1111/tpj.14136] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 09/23/2018] [Accepted: 10/15/2018] [Indexed: 06/08/2023]
Abstract
The target of rapamycin (TOR) signaling pathway is involved in starch accumulation in various eukaryotic organisms; however, the molecular mechanism behind this phenomenon in eukaryotes has not been elucidated. We report a regulatory mechanism of starch accumulation by TOR in the unicellular red alga, Cyanidioschyzon merolae. The starch content in C. merolae after TOR-inactivation by rapamycin, a TOR-specific inhibitor, was increased by approximately 10-fold in comparison with its drug vehicle, dimethyl sulfoxide. However, our previous transcriptome analysis showed that the expression level of genes related to carbohydrate metabolism was unaffected by rapamycin, indicating that starch accumulation is regulated at post-transcriptional levels. In this study, we performed a phosphoproteome analysis using liquid chromatography-tandem mass spectrometry to investigate potential post-transcriptional modifications, and identified 52 proteins as candidate TOR substrates. Among the possible substrates, we focused on the function of CmGLG1, because its phosphorylation at the Ser613 residue was decreased after rapamycin treatment, and overexpression of CmGLG1 resulted in a 4.7-fold higher starch content. CmGLG1 is similar to the priming protein, glycogenin, which is required for the initiation of starch/glycogen synthesis, and a budding yeast complementation assay demonstrated that CmGLG1 can functionally substitute for glycogenin. We found an approximately 60% reduction in the starch content in a phospho-mimicking CmGLG1 overexpression strain, in which Ser613 was substituted with aspartic acid, in comparison with the wild-type CmGLG1 overexpression cells. Our results indicate that TOR modulates starch accumulation by changing the phosphorylation status of the CmGLG1 Ser613 residue in C. merolae.
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Affiliation(s)
- Imran Pancha
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
| | - Hiroki Shima
- Department of Biochemistry, Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Aoba-ku, Sendai, 980-8575, Japan
| | - Nahoko Higashitani
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Kazuhiko Igarashi
- Department of Biochemistry, Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Aoba-ku, Sendai, 980-8575, Japan
| | - Atsushi Higashitani
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
| | - Sousuke Imamura
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
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21
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Takeuchi T, Benning C. Nitrogen-dependent coordination of cell cycle, quiescence and TAG accumulation in Chlamydomonas. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:292. [PMID: 31890020 PMCID: PMC6927116 DOI: 10.1186/s13068-019-1635-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 12/12/2019] [Indexed: 05/07/2023]
Abstract
Microalgae hold great promises as sustainable cellular factories for the production of alternative fuels, feeds, and biopharmaceuticals for human health. While the biorefinery approach for fuels along with the coproduction of high-value compounds with industrial, therapeutic, or nutraceutical applications have the potential to make algal biofuels more economically viable, a number of challenges continue to hamper algal production systems at all levels. One such hurdle includes the metabolic trade-off often observed between the increased yields of desired products, such as triacylglycerols (TAG), and the growth of an organism. Initial genetic engineering strategies to improve lipid productivity in microalgae, which focused on overproducing the enzymes involved in fatty acid and TAG biosynthesis or inactivating competing carbon (C) metabolism, have seen some successes albeit at the cost of often greatly reduced biomass. Emergent approaches that aim at modifying the dynamics of entire metabolic pathways by engineering of pertinent transcription factors or signaling networks appear to have successfully achieved a balance between growth and neutral lipid accumulation. However, the biological knowledge of key signaling networks and molecular components linking these two processes is still incomplete in photosynthetic eukaryotes, making it difficult to optimize metabolic engineering strategies for microalgae. Here, we focus on nitrogen (N) starvation of the model green microalga, Chlamydomonas reinhardtii, to present the current understanding of the nutrient-dependent switch between proliferation and quiescence, and the drastic reprogramming of metabolism that results in the storage of C compounds following N starvation. We discuss the potential components mediating the transcriptional repression of cell cycle genes and the establishment of quiescence in Chlamydomonas, and highlight the importance of signaling pathways such as those governed by the target of rapamycin (TOR) and sucrose nonfermenting-related (SnRK) kinases in the coordination of metabolic status with cellular growth. A better understanding of how the cell division cycle is regulated in response to nutrient scarcity and of the signaling pathways linking cellular growth to energy and lipid homeostasis, is essential to improve the prospects of biofuels and biomass production in microalgae.
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Affiliation(s)
- Tomomi Takeuchi
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
| | - Christoph Benning
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
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Mubeen U, Jüppner J, Alpers J, Hincha DK, Giavalisco P. Target of Rapamycin Inhibition in Chlamydomonas reinhardtii Triggers de Novo Amino Acid Synthesis by Enhancing Nitrogen Assimilation. THE PLANT CELL 2018; 30:2240-2254. [PMID: 30228127 PMCID: PMC6241278 DOI: 10.1105/tpc.18.00159] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 07/30/2018] [Accepted: 09/13/2018] [Indexed: 05/19/2023]
Abstract
The Target of Rapamycin (TOR) kinase is a central regulator of growth and metabolism in all eukaryotic organisms, including animals, fungi, and plants. Even though the inputs and outputs of TOR signaling are well characterized for animals and fungi, our understanding of the upstream regulators of TOR and its downstream targets is still fragmentary in photosynthetic organisms. In this study, we employed the rapamycin-sensitive green alga Chlamydomonas reinhardtii to elucidate the molecular cause of the amino acid accumulation that occurs after rapamycin-induced inhibition of TOR. Using different growth conditions and stable 13C- and 15N-isotope labeling, we show that this phenotype is accompanied by increased nitrogen (N) uptake, which is induced within minutes of TOR inhibition. Interestingly, this increased N influx is accompanied by increased activities of glutamine synthetase and glutamine oxoglutarate aminotransferase, the main N-assimilating enzymes, which are responsible for the rise in levels of several amino acids, which occurs within a few minutes. Accordingly, we conclude that even though translation initiation and autophagy have been reported to be the main downstream targets of TOR, the upregulation of de novo amino acid synthesis seems to be one of the earliest responses induced after the inhibition of TOR in Chlamydomonas.
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Affiliation(s)
- Umarah Mubeen
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Jessica Jüppner
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Jessica Alpers
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Dirk K Hincha
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Patrick Giavalisco
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
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23
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Avin-Wittenberg T, Baluška F, Bozhkov PV, Elander PH, Fernie AR, Galili G, Hassan A, Hofius D, Isono E, Le Bars R, Masclaux-Daubresse C, Minina EA, Peled-Zehavi H, Coll NS, Sandalio LM, Satiat-Jeunemaitre B, Sirko A, Testillano PS, Batoko H. Autophagy-related approaches for improving nutrient use efficiency and crop yield protection. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:1335-1353. [PMID: 29474677 DOI: 10.1093/jxb/ery069] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 02/16/2018] [Indexed: 05/18/2023]
Abstract
Autophagy is a eukaryotic catabolic pathway essential for growth and development. In plants, it is activated in response to environmental cues or developmental stimuli. However, in contrast to other eukaryotic systems, we know relatively little regarding the molecular players involved in autophagy and the regulation of this complex pathway. In the framework of the COST (European Cooperation in Science and Technology) action TRANSAUTOPHAGY (2016-2020), we decided to review our current knowledge of autophagy responses in higher plants, with emphasis on knowledge gaps. We also assess here the potential of translating the acquired knowledge to improve crop plant growth and development in a context of growing social and environmental challenges for agriculture in the near future.
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Affiliation(s)
- Tamar Avin-Wittenberg
- Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - Frantisek Baluška
- Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee, Bonn, Germany
| | - Peter V Bozhkov
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Pernilla H Elander
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Alisdair R Fernie
- Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg, Potsdam-Golm, Germany
| | - Gad Galili
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot Israel
| | - Ammar Hassan
- Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee, Bonn, Germany
| | - Daniel Hofius
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center of Plant Biology, Uppsala, Sweden
| | - Erika Isono
- Department of Biology, University of Konstanz, Universitätsstrasse, Konstanz, Germany
| | - Romain Le Bars
- Cell Biology Pôle Imagerie-Gif, Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Céline Masclaux-Daubresse
- INRA-AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, ERL CNRS 3559, Saclay Plant Sciences, Versailles, France
| | - Elena A Minina
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Hadas Peled-Zehavi
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot Israel
| | - Núria S Coll
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra-Cerdanyola del Valles, Catalonia, Spain
| | - Luisa M Sandalio
- Departmento de Bioquímica, Biología Celular y Molecular de Plantas Experimental del Zaidín, CSIC, Granada, Spain
| | - Béatrice Satiat-Jeunemaitre
- Cell Biology Pôle Imagerie-Gif, Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Agnieszka Sirko
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, ul. Pawinskiego, Warsaw, Poland
| | - Pilar S Testillano
- Pollen Biotechnology of Crop Plants group, Centro de Investigaciones Biológicas, Biological Research Centre (CIB), CSIC, Ramiro de Maeztu, Madrid, Spain
| | - Henri Batoko
- Université Catholique de Louvain, Institute of Life Sciences, Croix du Sud, Louvain-la-Neuve, Belgium
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Jüppner J, Mubeen U, Leisse A, Caldana C, Wiszniewski A, Steinhauser D, Giavalisco P. The target of rapamycin kinase affects biomass accumulation and cell cycle progression by altering carbon/nitrogen balance in synchronized Chlamydomonas reinhardtii cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:355-376. [PMID: 29172247 DOI: 10.1111/tpj.13787] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 10/31/2017] [Accepted: 11/15/2017] [Indexed: 05/19/2023]
Abstract
Several metabolic processes tightly regulate growth and biomass accumulation. A highly conserved protein complex containing the target of rapamycin (TOR) kinase is known to integrate intra- and extracellular stimuli controlling nutrient allocation and hence cellular growth. Although several functions of TOR have been described in various heterotrophic eukaryotes, our understanding lags far behind in photosynthetic organisms. In the present investigation, we used the model alga Chlamydomonas reinhardtii to conduct a time-resolved analysis of molecular and physiological features throughout the diurnal cycle after TOR inhibition. Detailed examination of the cell cycle phases revealed that growth is not only repressed by 50%, but also that significant, non-linear delays in the progression can be observed. By using metabolomics analysis, we elucidated that the growth repression was mainly driven by differential carbon partitioning between anabolic and catabolic processes. Accordingly, the time-resolved analysis illustrated that metabolic processes including amino acid-, starch- and triacylglycerol synthesis, as well RNA degradation, were redirected within minutes of TOR inhibition. Here especially the high accumulation of nitrogen-containing compounds indicated that an active TOR kinase controls the carbon to nitrogen balance of the cell, which is responsible for biomass accumulation, growth and cell cycle progression.
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Affiliation(s)
- Jessica Jüppner
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Umarah Mubeen
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Andrea Leisse
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Camila Caldana
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
- Brazilian Bioethanol Science and Technology Laboratory/CNPEM, Rua Giuseppe Máximo Scolfano 10000, 13083-970, Campinas, Brazil
| | - Andrew Wiszniewski
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Dirk Steinhauser
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Patrick Giavalisco
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
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25
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Roustan V, Weckwerth W. Quantitative Phosphoproteomic and System-Level Analysis of TOR Inhibition Unravel Distinct Organellar Acclimation in Chlamydomonas reinhardtii. FRONTIERS IN PLANT SCIENCE 2018; 9:1590. [PMID: 30546371 PMCID: PMC6280106 DOI: 10.3389/fpls.2018.01590] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 10/15/2018] [Indexed: 05/13/2023]
Abstract
Rapamycin is an inhibitor of the evolutionary conserved Target of Rapamycin (TOR) kinase which promotes and coordinates translation with cell growth and division. In heterotrophic organisms, TOR regulation is based on intra- and extracellular stimuli such as amino acids level and insulin perception. However, how plant TOR pathways have evolved to integrate plastid endosymbiosis is a remaining question. Despite the close association of the TOR signaling with the coordination between protein turn-over and growth, proteome and phosphoproteome acclimation to a rapamycin treatment have not yet been thoroughly investigated in Chlamydomonas reinhardtii. In this study, we have used in vivo label-free phospho-proteomic analysis to profile both protein and phosphorylation changes at 0, 24, and 48 h in Chlamydomonas cells treated with rapamycin. Using multivariate statistics we highlight the impact of TOR inhibition on both the proteome and the phosphoproteome. Two-way ANOVA distinguished differential levels of proteins and phosphoproteins in response either to culture duration and rapamycin treatment or combined effects. Finally, protein-protein interaction networks and functional enrichment analysis underlined the relation between plastid and mitochondrial metabolism. Prominent changes of proteins involved in sulfur, cysteine, and methionine as well as nucleotide metabolism on the one hand, and changes in the TCA cycle on the other highlight the interplay of chloroplast and mitochondria metabolism. Furthermore, TOR inhibition revealed changes in the endomembrane trafficking system. Phosphoproteomics data, on the other hand, highlighted specific differentially regulated phosphorylation sites for calcium-regulated protein kinases as well as ATG7, S6K, and PP2C. To conclude we provide a first combined Chlamydomonas proteomics and phosphoproteomics dataset in response to TOR inhibition, which will support further investigations.
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Affiliation(s)
- Valentin Roustan
- Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria
| | - Wolfram Weckwerth
- Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria
- Vienna Metabolomics Center (VIME), University of Vienna, Vienna, Austria
- *Correspondence: Wolfram Weckwerth,
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The TOR Signaling Network in the Model Unicellular Green Alga Chlamydomonas reinhardtii. Biomolecules 2017; 7:biom7030054. [PMID: 28704927 PMCID: PMC5618235 DOI: 10.3390/biom7030054] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/06/2017] [Accepted: 07/07/2017] [Indexed: 12/18/2022] Open
Abstract
Cell growth is tightly coupled to nutrient availability. The target of rapamycin (TOR) kinase transmits nutritional and environmental cues to the cellular growth machinery. TOR functions in two distinct multiprotein complexes, termed TOR complex 1 (TORC1) and TOR complex 2 (TORC2). While the structure and functions of TORC1 are highly conserved in all eukaryotes, including algae and plants, TORC2 core proteins seem to be missing in photosynthetic organisms. TORC1 controls cell growth by promoting anabolic processes, including protein synthesis and ribosome biogenesis, and inhibiting catabolic processes such as autophagy. Recent studies identified rapamycin-sensitive TORC1 signaling regulating cell growth, autophagy, lipid metabolism, and central metabolic pathways in the model unicellular green alga Chlamydomonas reinhardtii. The central role that microalgae play in global biomass production, together with the high biotechnological potential of these organisms in biofuel production, has drawn attention to the study of proteins that regulate cell growth such as the TOR kinase. In this review we discuss the recent progress on TOR signaling in algae.
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27
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Schepetilnikov M, Ryabova LA. Auxin Signaling in Regulation of Plant Translation Reinitiation. FRONTIERS IN PLANT SCIENCE 2017; 8:1014. [PMID: 28659957 PMCID: PMC5469914 DOI: 10.3389/fpls.2017.01014] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/26/2017] [Indexed: 05/03/2023]
Abstract
The mRNA translation machinery directs protein production, and thus cell growth, according to prevailing cellular and environmental conditions. The target of rapamycin (TOR) signaling pathway-a major growth-related pathway-plays a pivotal role in optimizing protein synthesis in mammals, while its deregulation triggers uncontrolled cell proliferation and the development of severe diseases. In plants, several signaling pathways sensitive to environmental changes, hormones, and pathogens have been implicated in post-transcriptional control, and thus far phytohormones have attracted most attention as TOR upstream regulators in plants. Recent data have suggested that the coordinated actions of the phytohormone auxin, Rho-like small GTPases (ROPs) from plants, and TOR signaling contribute to translation regulation of mRNAs that harbor upstream open reading frames (uORFs) within their 5'-untranslated regions (5'-UTRs). This review will summarize recent advances in translational regulation of a specific set of uORF-containing mRNAs that encode regulatory proteins-transcription factors, protein kinases and other cellular controllers-and how their control can impact plant growth and development.
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Affiliation(s)
- Mikhail Schepetilnikov
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de StrasbourgStrasbourg, France
| | - Lyubov A. Ryabova
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de StrasbourgStrasbourg, France
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28
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HSPA5 Gene encoding Hsp70 chaperone BiP in the endoplasmic reticulum. Gene 2017; 618:14-23. [PMID: 28286085 DOI: 10.1016/j.gene.2017.03.005] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 02/28/2017] [Accepted: 03/06/2017] [Indexed: 01/07/2023]
Abstract
The HSPA5 gene encodes the binding immunoglobulin protein (BiP), an Hsp70 family chaperone localized in the ER lumen. As a highly conserved molecular chaperone, BiP assists in a wide range of folding processes via its two structural domains, a nucleotide-binding domain (NBD) and substrate-binding domain (SBD). BiP is also an essential component of the translocation machinery for protein import into the ER, a regulator for Ca2+ homeostasis in the ER, as well as a facilitator of ER-associated protein degradation (ERAD) via retrograde transportation of aberrant proteins across the ER membrane. When unfolded/misfolded proteins in the ER overwhelm the capacity of protein folding machinery, BiP can initiate the unfolded protein response (UPR), decrease unfolded/misfolded protein load, induce autophagy, and crosstalk with apoptosis machinery to assist in the cell survival decision. Post-translational modifications (PTMs) of BiP have been shown to regulate BiP's activity, turnover, and availability upon different extrinsic or intrinsic stimuli. As a master regulator of ER function, BiP is associated with cancer, cardiovascular disease, neurodegenerative disease, and immunological diseases. BiP has been targeted in cancer therapies and shows promise for application in other relevant diseases.
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29
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Maheshwari R, Pushpa K, Subramaniam K. A role for post-transcriptional control of endoplasmic reticulum dynamics and function in C. elegans germline stem cell maintenance. Development 2016; 143:3097-108. [PMID: 27510976 DOI: 10.1242/dev.134056] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 07/21/2016] [Indexed: 01/02/2023]
Abstract
Membrane-bound receptors, which are crucial for mediating several key developmental signals, are synthesized on endoplasmic reticulum (ER). The functional integrity of ER must therefore be important for the regulation of at least some developmental programs. However, the developmental control of ER function is not well understood. Here, we identify the C. elegans protein FARL-11, an ortholog of the mammalian STRIPAK complex component STRIP1/2 (FAM40A/B), as an ER protein. In the C. elegans embryo, we find that FARL-11 is essential for the cell cycle-dependent morphological changes of ER and for embryonic viability. In the germline, FARL-11 is required for normal ER morphology and for membrane localization of the GLP-1/Notch receptor involved in germline stem cell (GSC) maintenance. Furthermore, we provide evidence that PUF-8, a key translational regulator in the germline, promotes the translation of farl-11 mRNA. These findings reveal that ER form and function in the C. elegans germline are post-transcriptionally regulated and essential for the niche-GSC signaling mediated by GLP-1.
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Affiliation(s)
- Richa Maheshwari
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Kumari Pushpa
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Kuppuswamy Subramaniam
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India Department of Biotechnology, Indian Institute of Technology - Madras, Chennai 600036, India
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30
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Dobrenel T, Caldana C, Hanson J, Robaglia C, Vincentz M, Veit B, Meyer C. TOR Signaling and Nutrient Sensing. ANNUAL REVIEW OF PLANT BIOLOGY 2016; 67:261-85. [PMID: 26905651 DOI: 10.1146/annurev-arplant-043014-114648] [Citation(s) in RCA: 243] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
All living organisms rely on nutrients to sustain cell metabolism and energy production, which in turn need to be adjusted based on available resources. The evolutionarily conserved target of rapamycin (TOR) protein kinase is a central regulatory hub that connects environmental information about the quantity and quality of nutrients to developmental and metabolic processes in order to maintain cellular homeostasis. TOR is activated by both nitrogen and carbon metabolites and promotes energy-consuming processes such as cell division, mRNA translation, and anabolism in times of abundance while repressing nutrient remobilization through autophagy. In animals and yeasts, TOR acts antagonistically to the starvation-induced AMP-activated kinase (AMPK)/sucrose nonfermenting 1 (Snf1) kinase, called Snf1-related kinase 1 (SnRK1) in plants. This review summarizes the immense knowledge on the relationship between TOR signaling and nutrients in nonphotosynthetic organisms and presents recent findings in plants that illuminate the crucial role of this pathway in conveying nutrient-derived signals and regulating many aspects of metabolism and growth.
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Affiliation(s)
- Thomas Dobrenel
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, ERL CNRS 3559, Saclay Plant Sciences, Versailles 78026, France;
- Umeå Plant Science Center, Department of Plant Physiology, Umeå University, Umeå 90187, Sweden
| | - Camila Caldana
- Molecular Physiology of Plant Biomass Production Group, Max Planck Partner Group, Brazilian Bioethanol Science and Technology Laboratory, CEP 13083-100 Campinas, São Paulo, Brazil
| | - Johannes Hanson
- Umeå Plant Science Center, Department of Plant Physiology, Umeå University, Umeå 90187, Sweden
| | - Christophe Robaglia
- Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, DSV, IBEB, SBVME, CEA, CNRS, Aix Marseille Université, Faculté des Sciences de Luminy, Marseille 13009, France
| | - Michel Vincentz
- Laboratório de Genética de Plantas, Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, CEP 13083-875 Campinas, São Paulo, Brazil
| | - Bruce Veit
- Forage Improvement, AgResearch, Institute of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Christian Meyer
- Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, ERL CNRS 3559, Saclay Plant Sciences, Versailles 78026, France;
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31
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Abstract
Target of rapamycin (TOR) forms two conserved, structurally distinct kinase complexes termed TOR complex 1 (TORC1) and TORC2. Each complex phosphorylates a different set of substrates to regulate cell growth. In mammals, mTOR is stimulated by nutrients and growth factors and inhibited by stress to ensure that cells grow only during favorable conditions. Studies in different organisms have reported localization of TOR to several distinct subcellular compartments. Notably, the finding that mTORC1 is localized to the lysosome has significantly enhanced our understanding of mTORC1 regulation. Subcellular localization may be a general principle used by TOR to enact precise spatial and temporal control of cell growth.
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Affiliation(s)
- Charles Betz
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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32
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Kato N, Dong T, Bailey M, Lum T, Ingram D. Triacylglycerol mobilization is suppressed by brefeldin A in Chlamydomonas reinhardtii. PLANT & CELL PHYSIOLOGY 2013; 54:1585-99. [PMID: 23872273 PMCID: PMC4081630 DOI: 10.1093/pcp/pct103] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Brefeldin A suppresses vesicle trafficking by inhibiting exchange of GDP for GTP in ADP-ribosylation factor. We report that brefeldin A suppresses mobilization of triacylglycerols in Chlamydomonas reinhardtii, a model organism of green microalgae. Analyses revealed that brefeldin A causes Chlamydomonas to form lipid droplets in which triacylglycerols accumulate in a dose-dependent manner. Pulse labeling experiment using fluorescent fatty acids suggested that brefeldin A inhibits the cells from degrading fatty acids. The experiment also revealed that the cells transiently form novel compartments that accumulate exogenously added fatty acids in the cytoplasm, designated fatty acid-induced microbodies (FAIMs). Brefeldin A up-regulates the formation of FAIMs, whereas nitrogen deprivation that up-regulates triacylglycerol synthesis in Chlamydomonas does not cause the cells to form FAIMs. These results underscore the role of the vesicle trafficking machinery in triacylglycerol metabolism in green microalgae.
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Affiliation(s)
- Naohiro Kato
- Department of Biological Sciences, Louisiana State University, 226 Life Sciences Building, Baton Rouge, LA 70803, USA
- *Corresponding author: E-mail: ; Fax: +1-225-578-2597
| | - Trung Dong
- Department of Biological Sciences, Louisiana State University, 226 Life Sciences Building, Baton Rouge, LA 70803, USA
| | - Michael Bailey
- Department of Biological Sciences, Louisiana State University, 226 Life Sciences Building, Baton Rouge, LA 70803, USA
| | - Tony Lum
- Department of Biological Sciences, Louisiana State University, 226 Life Sciences Building, Baton Rouge, LA 70803, USA
| | - Drury Ingram
- Cell Biology & Bioimaging Core, Pennington Biomedical Research Center, 6400 Perkins Rd., Baton Rouge, LA 70808, USA
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33
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Sanz-Luque E, Ocaña-Calahorro F, Llamas A, Galvan A, Fernandez E. Nitric oxide controls nitrate and ammonium assimilation in Chlamydomonas reinhardtii. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:3373-83. [PMID: 23918969 DOI: 10.1093/jxb/ert175] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nitrate and ammonium are major inorganic nitrogen sources for plants and algae. These compounds are assimilated by means of finely regulated processes at transcriptional and post-translational levels. In Chlamydomonas, the expression of several genes involved in high-affinity ammonium (AMT1.1, AMT1.2) and nitrate transport (NRT2.1) as well as nitrate reduction (NIA1) are downregulated by ammonium through a nitric oxide (NO)-dependent mechanism. At the post-translational level, nitrate/nitrite uptake and nitrate reductase (NR) are also inhibited by ammonium, but the mechanisms implicated in this regulation are scarcely known. In this work, the effect of NO on nitrate assimilation and the high-affinity ammonium uptake was addressed. NO inhibited the high-affinity uptake of ammonium and nitrate/nitrite, as well as the NR activity, in a reversible form. In contrast, nitrite reductase and glutamine synthetase activities were not affected. The in vivo and in vitro studies suggested that NR enzyme is inhibited by NO in a mediated process that requires the cell integrity. These data highlight a role of NO in inorganic nitrogen assimilation and suggest that this signalling molecule is an important regulator for the first steps of the pathway.
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Affiliation(s)
- Emanuel Sanz-Luque
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Campus de Excelencia Agroalimentario CeiA3, Campus de Rabanales, Edificio Severo Ochoa, Córdoba 14071, Spain
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34
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Pu Y, Bassham DC. Links between ER stress and autophagy in plants. PLANT SIGNALING & BEHAVIOR 2013; 8:e24297. [PMID: 23603973 PMCID: PMC3907440 DOI: 10.4161/psb.24297] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 03/13/2013] [Indexed: 05/23/2023]
Abstract
Autophagy is a major pathway for the delivery of proteins or organelles to be degraded in the vacuole and recycled. It can be induced by abiotic stresses, senescence, and pathogen infection. Recent research has shown that autophagy is activated by ER stress. Here we review the major progress that has been made in the study of autophagy and ER stress in plants, and describe the links between ER stress and autophagy to guide further study on how autophagy is regulated in response to ER stress.
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35
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Liu Y, Burgos JS, Deng Y, Srivastava R, Howell SH, Bassham DC. Degradation of the endoplasmic reticulum by autophagy during endoplasmic reticulum stress in Arabidopsis. THE PLANT CELL 2012; 24:4635-51. [PMID: 23175745 PMCID: PMC3531857 DOI: 10.1105/tpc.112.101535] [Citation(s) in RCA: 202] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 10/17/2012] [Accepted: 10/30/2012] [Indexed: 05/18/2023]
Abstract
In this article, we show that the endoplasmic reticulum (ER) in Arabidopsis thaliana undergoes morphological changes in structure during ER stress that can be attributed to autophagy. ER stress agents trigger autophagy as demonstrated by increased production of autophagosomes. In response to ER stress, a soluble ER marker localizes to autophagosomes and accumulates in the vacuole upon inhibition of vacuolar proteases. Membrane lamellae decorated with ribosomes were observed inside autophagic bodies, demonstrating that portions of the ER are delivered to the vacuole by autophagy during ER stress. In addition, an ER stress sensor, INOSITOL-REQUIRING ENZYME-1b (IRE1b), was found to be required for ER stress-induced autophagy. However, the IRE1b splicing target, bZIP60, did not seem to be involved, suggesting the existence of an undiscovered signaling pathway to regulate ER stress-induced autophagy in plants. Together, these results suggest that autophagy serves as a pathway for the turnover of ER membrane and its contents in response to ER stress in plants.
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Affiliation(s)
- Yimo Liu
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011
- Interdepartmental Genetics Program, Iowa State University, Ames, Iowa 50011
| | - Junmarie Soto Burgos
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011
| | - Yan Deng
- Plant Sciences Institute, Iowa State University, Ames, Iowa 50011
| | - Renu Srivastava
- Plant Sciences Institute, Iowa State University, Ames, Iowa 50011
| | - Stephen H. Howell
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011
- Plant Sciences Institute, Iowa State University, Ames, Iowa 50011
| | - Diane C. Bassham
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011
- Interdepartmental Genetics Program, Iowa State University, Ames, Iowa 50011
- Plant Sciences Institute, Iowa State University, Ames, Iowa 50011
- Address correspondence to
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36
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Pérez-Pérez ME, Lemaire SD, Crespo JL. Reactive oxygen species and autophagy in plants and algae. PLANT PHYSIOLOGY 2012; 160:156-64. [PMID: 22744983 PMCID: PMC3440194 DOI: 10.1104/pp.112.199992] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
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37
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Abstract
The highly conserved target of rapamycin (TOR) Ser/Thr kinase promotes protein synthesis under favorable growth conditions in all eukaryotes. Downregulation of TOR signaling in the model unicellular green alga Chlamydomonas reinhardtii has recently revealed a link between control of protein synthesis, endoplasmic reticulum (ER) stress and the reversible modification of the BiP chaperone by phosphorylation. Inhibition of protein synthesis by rapamycin or cycloheximide resulted in the phosphorylation of BiP on threonine residues while ER stress induced by tunicamycin or heat shock caused the fast dephosphorylation of the protein. Regulation of BiP function by phosphorylation/dephosphorylation events was proposed in early studies in mammalian cells although no connection to TOR signaling has been established so far. Here I will discuss about the coordinated regulation of BiP modification by TOR and ER stress signals in Chlamydomonas.
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Affiliation(s)
- José L Crespo
- Instituto de Bioquímica Vegetal y Fotosíntesis-Consejo Superior de Investigaciones Científicas, CSIC, Avda. Américo Vespucio, Sevilla, Spain.
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