201
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Popova NV, Jücker M. The Role of mTOR Signaling as a Therapeutic Target in Cancer. Int J Mol Sci 2021; 22:ijms22041743. [PMID: 33572326 PMCID: PMC7916160 DOI: 10.3390/ijms22041743] [Citation(s) in RCA: 126] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 01/30/2021] [Accepted: 02/03/2021] [Indexed: 12/11/2022] Open
Abstract
The aim of this review was to summarize current available information about the role of phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling in cancer as a potential target for new therapy options. The mTOR and PI3K/AKT/mTORC1 (mTOR complex 1) signaling are critical for the regulation of many fundamental cell processes including protein synthesis, cell growth, metabolism, survival, catabolism, and autophagy, and deregulated mTOR signaling is implicated in cancer, metabolic dysregulation, and the aging process. In this review, we summarize the information about the structure and function of the mTOR pathway and discuss the mechanisms of its deregulation in human cancers including genetic alterations of PI3K/AKT/mTOR pathway components. We also present recent data regarding the PI3K/AKT/mTOR inhibitors in clinical studies and the treatment of cancer, as well the attendant problems of resistance and adverse effects.
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Affiliation(s)
- Nadezhda V. Popova
- Laboratory of Receptor Cell Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str., 16/10, 117997 Moscow, Russia;
| | - Manfred Jücker
- Institute of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
- Correspondence: ; Tel.: +49-(0)-40-7410-56339
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202
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Miyokawa R, Kanaya HJ, Itoh TQ, Kobayakawa Y, Kusumi J. Immature symbiotic system between horizontally transmitted green algae and brown hydra. Sci Rep 2021; 11:2921. [PMID: 33536483 PMCID: PMC7859245 DOI: 10.1038/s41598-021-82489-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 01/18/2021] [Indexed: 01/30/2023] Open
Abstract
Some strains of brown hydra (Hydra vulgaris) are able to harbor the green algae Chlorococcum in their endodermal epithelial cells as symbionts. However, the relationship between brown hydra and chlorococcum is considered to be incipient symbiosis because most artificially introduced symbionts are not stable and because symbiotic H. vulgaris strains are rare in the wild. In this study, we compared the gene expression levels of the newly established symbiotic hydra (strain 105G), the native symbiotic strain (J7), and their non-symbiotic polyps to determine what changes would occur at the early stage of the evolution of symbiosis. We found that both the 105G and J7 strains showed comparable expression patterns, exhibiting upregulation of lysosomal enzymes and downregulation of genes related to nematocyte development and function. Meanwhile, genes involved in translation and the respiratory chain were upregulated only in strain 105G. Furthermore, treatment with rapamycin, which inhibits translation activity, induced the degeneration of the symbiotic strains (105G and J7). This effect was severe in strain 105G. Our results suggested that evolving the ability to balance the cellular metabolism between the host and the symbiont is a key requirement for adapting to endosymbiosis with chlorococcum.
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Affiliation(s)
- Ryo Miyokawa
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Science for Global Society, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka, 819-0395 Japan
| | - Hiroyuki J. Kanaya
- grid.177174.30000 0001 2242 4849School of Science, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka, 819-0395 Japan
| | - Taichi Q. Itoh
- grid.177174.30000 0001 2242 4849Faculty of Arts and Science, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka, 819-0395 Japan
| | - Yoshitaka Kobayakawa
- grid.177174.30000 0001 2242 4849Faculty of Arts and Science, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka, 819-0395 Japan
| | - Junko Kusumi
- grid.177174.30000 0001 2242 4849Department of Environmental Changes, Faculty of Social and Cultural Studies, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka, 819-0395 Japan
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203
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Li L, Zhu T, Song Y, Feng L, Farag EAH, Ren M. ABSCISIC ACID INSENSITIVE5 Interacts With RIBOSOMAL S6 KINASE2 to Mediate ABA Responses During Seedling Growth in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2021; 11:598654. [PMID: 33537040 PMCID: PMC7847994 DOI: 10.3389/fpls.2020.598654] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 12/31/2020] [Indexed: 05/28/2023]
Abstract
ABSCISIC ACID INSENSITIVE5 (ABI5) is an important regulator of abscisic acid (ABA) signaling pathway involved in regulating seed germination and postgerminative growth in Arabidopsis, which integrates various phytohormone pathways to balance plant growth and stress responses. However, the transcriptional regulatory mechanisms underlying ABI5 and its interacting proteins remain largely unknown. Here, we found that inhibition of AtTOR could increase ABA content by up-regulating the expression levels of ABA biosynthesis-related genes, and thus activated the expression of ABA-responsive genes. Pharmacological assay showed that abi5-1 mutant was insensitive to TOR inhibitor AZD8055, whereas AtABI5 overexpression lines were hypersensitive to AZD8055 in Arabidopsis. Biochemical interaction assays demonstrated that ABI5 physically interacted with the RIBOSOMAL S6 KINASE2 (S6K2) protein in plant cell. S6K2 positively regulated ABA responses during seedling growth and upregulated ABA-responsive genes expression. Furthermore, genetic and physiological analysis indicated that AtS6K2 overexpression lines enhanced resistance to drought treatment while AtS6K2 interference lines were sensitive to drought. These results indicated that AtABI5 interacted with AtS6K2 to positively modulate ABA responses during seedling growth and shed light on a underlying mechanism of the crosstalk between TOR and ABA signaling pathways in modulating seedling growth in Arabidopsis.
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Affiliation(s)
- Linxuan Li
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences/Chengdu National Agricultural Science and Technology Center, Chengdu, China
| | - Tingting Zhu
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences/Chengdu National Agricultural Science and Technology Center, Chengdu, China
| | - Yun Song
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, China
| | - Li Feng
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences/Chengdu National Agricultural Science and Technology Center, Chengdu, China
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, China
| | | | - Maozhi Ren
- Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences/Chengdu National Agricultural Science and Technology Center, Chengdu, China
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, China
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204
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Morozumi Y, Shiozaki K. Conserved and Divergent Mechanisms That Control TORC1 in Yeasts and Mammals. Genes (Basel) 2021; 12:genes12010088. [PMID: 33445779 PMCID: PMC7828246 DOI: 10.3390/genes12010088] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/10/2021] [Accepted: 01/11/2021] [Indexed: 12/23/2022] Open
Abstract
Target of rapamycin complex 1 (TORC1), a serine/threonine-protein kinase complex highly conserved among eukaryotes, coordinates cellular growth and metabolism with environmental cues, including nutrients and growth factors. Aberrant TORC1 signaling is associated with cancers and various human diseases, and TORC1 also plays a key role in ageing and lifespan, urging current active research on the mechanisms of TORC1 regulation in a variety of model organisms. Identification and characterization of the RAG small GTPases as well as their regulators, many of which are highly conserved from yeast to humans, led to a series of breakthroughs in understanding the molecular bases of TORC1 regulation. Recruitment of mammalian TORC1 (mTORC1) by RAGs to lysosomal membranes is a key step for mTORC1 activation. Interestingly, the RAG GTPases in fission yeast are primarily responsible for attenuation of TORC1 activity on vacuoles, the yeast equivalent of lysosomes. In this review, we summarize our current knowledge about the functions of TORC1 regulators on yeast vacuoles, and illustrate the conserved and divergent mechanisms of TORC1 regulation between yeasts and mammals.
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Affiliation(s)
- Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan;
- Correspondence: ; Tel.: +81-743-72-5543
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan;
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA
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205
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Smith EM, Benbahouche N, Morris K, Wilczynska A, Gillen S, Schmidt T, Meijer H, Jukes-Jones R, Cain K, Jones C, Stoneley M, Waldron J, Bell C, Fonseca B, Blagden S, Willis A, Bushell M. The mTOR regulated RNA-binding protein LARP1 requires PABPC1 for guided mRNA interaction. Nucleic Acids Res 2021; 49:458-478. [PMID: 33332560 PMCID: PMC7797073 DOI: 10.1093/nar/gkaa1189] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 11/16/2020] [Accepted: 12/11/2020] [Indexed: 12/16/2022] Open
Abstract
The mammalian target of rapamycin (mTOR) is a critical regulator of cell growth, integrating multiple signalling cues and pathways. Key among the downstream activities of mTOR is the control of the protein synthesis machinery. This is achieved, in part, via the co-ordinated regulation of mRNAs that contain a terminal oligopyrimidine tract (TOP) at their 5'ends, although the mechanisms by which this occurs downstream of mTOR signalling are still unclear. We used RNA-binding protein (RBP) capture to identify changes in the protein-RNA interaction landscape following mTOR inhibition. Upon mTOR inhibition, the binding of LARP1 to a number of mRNAs, including TOP-containing mRNAs, increased. Importantly, non-TOP-containing mRNAs bound by LARP1 are in a translationally-repressed state, even under control conditions. The mRNA interactome of the LARP1-associated protein PABPC1 was found to have a high degree of overlap with that of LARP1 and our data show that PABPC1 is required for the association of LARP1 with its specific mRNA targets. Finally, we demonstrate that mRNAs, including those encoding proteins critical for cell growth and survival, are translationally repressed when bound by both LARP1 and PABPC1.
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Affiliation(s)
- Ewan M Smith
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Nour El Houda Benbahouche
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Katherine Morris
- MRC Toxicology Unit, University of Cambridge, Leicester LE1 9HN, UK
| | - Ania Wilczynska
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1QH, UK
| | - Sarah Gillen
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Tobias Schmidt
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Hedda A Meijer
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | | | - Kelvin Cain
- MRC Toxicology Unit, University of Cambridge, Leicester LE1 9HN, UK
| | - Carolyn Jones
- MRC Toxicology Unit, University of Cambridge, Leicester LE1 9HN, UK
| | - Mark Stoneley
- MRC Toxicology Unit, University of Cambridge, Leicester LE1 9HN, UK
| | - Joseph A Waldron
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Cameron Bell
- Cancer Research UK Therapeutic Discovery Laboratories, London Bioscience Innovation Centre, 2 Royal College Street, London NW1 0NH, UK
| | | | - Sarah Blagden
- Department of Oncology, University of Oxford, Oxford, OX3 7LE, UK
| | - Anne E Willis
- MRC Toxicology Unit, University of Cambridge, Leicester LE1 9HN, UK
| | - Martin Bushell
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1QH, UK
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206
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Waetzig R, Matthes M, Leister J, Penkivech G, Heise T, Corbacioglu S, Sommer G. Comparing mTOR inhibitor Rapamycin with Torin-2 within the RIST molecular-targeted regimen in neuroblastoma cells. Int J Med Sci 2021; 18:137-149. [PMID: 33390782 PMCID: PMC7738968 DOI: 10.7150/ijms.48393] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 10/16/2020] [Indexed: 12/14/2022] Open
Abstract
The prognosis for patients with relapsed or refractory high-risk neuroblastoma remains dismal and novel therapeutic options are urgently needed. The RIST treatment protocol has a multimodal metronomic therapy design combining molecular-targeted drugs (Rapamycin and Dasatinib) with chemotherapy backbone (Irinotecan and Temozolomide), which is currently verified in a phase II clinical trial (NCT01467986). With the availability of novel and more potent ATP competitive mTOR inhibitors, we expect to improve the RIST combination therapy. By comparing the IC50 values of Torin-1, Torin-2, AZD3147 and PP242 we established that only Torin-2 inhibited cell viability of all three MycN-amplified neuroblastoma cell lines tested at nanomolar concentration. Single treatment of both mTOR inhibitors induced a significant G1 cell cycle arrest and combination treatment with Dasatinib reduced the expression of cell cycle regulator cyclin D1 or increased the expression of cell cycle inhibitor p21. The combinatorial index depicted for both mTOR inhibitors a synergistic effect with Dasatinib. Interestingly, compared to Rapamycin, the combination treatment with Torin-2 resulted in a broader mTOR pathway inhibition as indicated by reduced phosphorylation of AKT (Thr308, Ser473), 4E-BP (Ser65), and S6K (Thr389). Furthermore, substituting Rapamycin in the modified multimodal RIST protocol with Torin-2 reduced cell viability and induced apoptosis despite a significant lower Torin-2 drug concentration applied. The efficacy of nanomolar concentrations may significantly reduce unwanted immunosuppression associated with Rapamycin. However, at this point we cannot rule out that Torin-2 has increased toxicity due to its potency in more complex systems. Nonetheless, our results suggest that including Torin-2 as a substitute for Rapamycin in the RIST protocol may represent a valid option to be evaluated in prospective clinical trials for relapsed or treatment-refractory high-risk neuroblastoma.
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Affiliation(s)
- Rebecca Waetzig
- Department of Pediatric Hematology, Oncology and Stem Cell Transplantation, University Hospital of Regensburg, Franz-Josef-Strauss Allee 11, 93053, Regensburg, Germany
| | - Marie Matthes
- Department of Pediatric Hematology, Oncology and Stem Cell Transplantation, University Hospital of Regensburg, Franz-Josef-Strauss Allee 11, 93053, Regensburg, Germany
| | - Johannes Leister
- Department of Pediatric Hematology, Oncology and Stem Cell Transplantation, University Hospital of Regensburg, Franz-Josef-Strauss Allee 11, 93053, Regensburg, Germany
| | - Gina Penkivech
- Department of Pediatric Hematology, Oncology and Stem Cell Transplantation, University Hospital of Regensburg, Franz-Josef-Strauss Allee 11, 93053, Regensburg, Germany
| | - Tilman Heise
- Department of Pediatric Hematology, Oncology and Stem Cell Transplantation, University Hospital of Regensburg, Franz-Josef-Strauss Allee 11, 93053, Regensburg, Germany
| | - Selim Corbacioglu
- Department of Pediatric Hematology, Oncology and Stem Cell Transplantation, University Hospital of Regensburg, Franz-Josef-Strauss Allee 11, 93053, Regensburg, Germany
| | - Gunhild Sommer
- Department of Pediatric Hematology, Oncology and Stem Cell Transplantation, University Hospital of Regensburg, Franz-Josef-Strauss Allee 11, 93053, Regensburg, Germany
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207
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Samidurai A, Ockaili R, Cain C, Roh SK, Filippone SM, Kraskauskas D, Kukreja RC, Das A. Differential Regulation of mTOR Complexes with miR-302a Attenuates Myocardial Reperfusion Injury in Diabetes. iScience 2020; 23:101863. [PMID: 33319180 PMCID: PMC7725936 DOI: 10.1016/j.isci.2020.101863] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 09/07/2020] [Accepted: 11/20/2020] [Indexed: 01/11/2023] Open
Abstract
Persistent activation of mTOR (mammalian target of rapamycin) in diabetes increases the vulnerability of the heart to ischemia/reperfusion (I/R) injury. We show here that infusion of rapamycin (mTOR inhibitor) at reperfusion following ischemia reduced myocardial infarct size and apoptosis with restoration of cardiac function in type 1 diabetic rabbits. Likewise, treatment with rapamycin protected hyperglycemic human-pluripotent-stem-cells-derived cardiomyocytes (HG-hiPSC-CMs) following simulated ischemia (SI) and reoxygenation (RO). Phosphorylation of S6 (mTORC1 marker) was increased, whereas AKT phosphorylation (mTORC2 marker) and microRNA-302a were reduced with concomitant increase of its target, PTEN, following I/R injury in diabetic heart and HG-hiPSC-CMs. Rapamycin inhibited mTORC1 and PTEN, but augmented mTORC2 with restoration of miRNA-302a under diabetic conditions. Inhibition of miRNA-302a blocked mTORC2 and abolished rapamycin-induced protection against SI/RO injury in HG-hiPSC-CMs. We conclude that rapamycin attenuates reperfusion injury in diabetic heart through inhibition of PTEN and mTORC1 with restoration of miR-302a-mTORC2 signaling. miR-302a and AKT phosphorylation are suppressed in post-ischemic diabetic heart Negative regulator of insulin signaling, PTEN, is induced after ischemia reperfusion miRNA-302a-mimic abolishes ischemic injury in hyperglycemic human iPS cardiocytes Rapamycin treatment restores miR-302a-mTORC2 cardioprotective signaling in diabetes
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Affiliation(s)
- Arun Samidurai
- Division of Cardiology, Pauley Heart Center, Box 980204, Virginia Commonwealth University Medical Center, 1101 East Marshall Street, Sanger Hall, Room 7020d & 7020b, Richmond, VA 23298-0204, USA
| | - Ramzi Ockaili
- Division of Cardiology, Pauley Heart Center, Box 980204, Virginia Commonwealth University Medical Center, 1101 East Marshall Street, Sanger Hall, Room 7020d & 7020b, Richmond, VA 23298-0204, USA
| | - Chad Cain
- Division of Cardiology, Pauley Heart Center, Box 980204, Virginia Commonwealth University Medical Center, 1101 East Marshall Street, Sanger Hall, Room 7020d & 7020b, Richmond, VA 23298-0204, USA
| | - Sean K Roh
- Division of Cardiology, Pauley Heart Center, Box 980204, Virginia Commonwealth University Medical Center, 1101 East Marshall Street, Sanger Hall, Room 7020d & 7020b, Richmond, VA 23298-0204, USA
| | - Scott M Filippone
- Division of Cardiology, Pauley Heart Center, Box 980204, Virginia Commonwealth University Medical Center, 1101 East Marshall Street, Sanger Hall, Room 7020d & 7020b, Richmond, VA 23298-0204, USA
| | - Donatas Kraskauskas
- Division of Cardiology, Pauley Heart Center, Box 980204, Virginia Commonwealth University Medical Center, 1101 East Marshall Street, Sanger Hall, Room 7020d & 7020b, Richmond, VA 23298-0204, USA
| | - Rakesh C Kukreja
- Division of Cardiology, Pauley Heart Center, Box 980204, Virginia Commonwealth University Medical Center, 1101 East Marshall Street, Sanger Hall, Room 7020d & 7020b, Richmond, VA 23298-0204, USA
| | - Anindita Das
- Division of Cardiology, Pauley Heart Center, Box 980204, Virginia Commonwealth University Medical Center, 1101 East Marshall Street, Sanger Hall, Room 7020d & 7020b, Richmond, VA 23298-0204, USA
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208
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A Tour of TOR Complex Signaling in Plants. Trends Biochem Sci 2020; 46:417-428. [PMID: 33309324 DOI: 10.1016/j.tibs.2020.11.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/26/2020] [Accepted: 11/09/2020] [Indexed: 01/07/2023]
Abstract
To identify the appropriate times for growth and development, organisms must sense and process information about the availability of nutrients, energy status, and environmental cues. For sessile eukaryotes such as plants, integrating such information can be critical in life or death decisions. For nearly 30 years, the conserved phosphatidylinositol 3-kinase-related protein kinases (PIKKs) target of rapamycin (TOR) has been established as a central hub for integrating external and internal metabolic cues. Despite the functional conservation across eukaryotes, the TOR complex has evolved specific functional and mechanistic features in plants. Here, we present recent findings on the plant TOR complex that highlight the conserved and unique nature of this critical growth regulator and its role in multiple aspects of plant life.
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209
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Azar WS, Njeim R, Fares AH, Azar NS, Azar ST, El Sayed M, Eid AA. COVID-19 and diabetes mellitus: how one pandemic worsens the other. Rev Endocr Metab Disord 2020; 21:451-463. [PMID: 32743793 PMCID: PMC7395898 DOI: 10.1007/s11154-020-09573-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In light of the most challenging public health crisis of modern history, COVID-19 mortality continues to rise at an alarming rate. Patients with co-morbidities such as hypertension, cardiovascular disease, and diabetes mellitus (DM) seem to be more prone to severe symptoms and appear to have a higher mortality rate. In this review, we elucidate suggested mechanisms underlying the increased susceptibility of patients with diabetes to infection with SARS-CoV-2 with a more severe COVID-19 disease. The worsened prognosis of COVID-19 patients with DM can be attributed to a facilitated viral uptake assisted by the host's receptor angiotensin-converting enzyme 2 (ACE2). It can also be associated with a higher basal level of pro-inflammatory cytokines present in patients with diabetes, which enables a hyperinflammatory "cytokine storm" in response to the virus. This review also suggests a link between elevated levels of IL-6 and AMPK/mTOR signaling pathway and their role in exacerbating diabetes-induced complications and insulin resistance. If further studied, these findings could help identify novel therapeutic intervention strategies for patients with diabetes comorbid with COVID-19.
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Affiliation(s)
- William S Azar
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Bliss Street, 11-0236, Riad El-Solh, Beirut, 1107-2020, Lebanon
- AUB Diabetes, American University of Beirut, Beirut, Lebanon
- Department of Physiology and Biophysics, Georgetown University Medical Center, Washington, DC, USA
| | - Rachel Njeim
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Bliss Street, 11-0236, Riad El-Solh, Beirut, 1107-2020, Lebanon
- AUB Diabetes, American University of Beirut, Beirut, Lebanon
| | - Angie H Fares
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Bliss Street, 11-0236, Riad El-Solh, Beirut, 1107-2020, Lebanon
- AUB Diabetes, American University of Beirut, Beirut, Lebanon
| | - Nadim S Azar
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Bliss Street, 11-0236, Riad El-Solh, Beirut, 1107-2020, Lebanon
- AUB Diabetes, American University of Beirut, Beirut, Lebanon
| | - Sami T Azar
- AUB Diabetes, American University of Beirut, Beirut, Lebanon
- Department of Internal Medicine, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
| | - Mazen El Sayed
- Department of Emergency Medicine, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
| | - Assaad A Eid
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Bliss Street, 11-0236, Riad El-Solh, Beirut, 1107-2020, Lebanon.
- AUB Diabetes, American University of Beirut, Beirut, Lebanon.
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210
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Martin-Perez M, Grillo AS, Ito TK, Valente AS, Han J, Entwisle SW, Huang HZ, Kim D, Yajima M, Kaeberlein M, Villén J. PKC downregulation upon rapamycin treatment attenuates mitochondrial disease. Nat Metab 2020; 2:1472-1481. [PMID: 33324011 PMCID: PMC8017771 DOI: 10.1038/s42255-020-00319-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 11/06/2020] [Indexed: 02/06/2023]
Abstract
Leigh syndrome is a fatal neurometabolic disorder caused by defects in mitochondrial function. Mechanistic target of rapamycin (mTOR) inhibition with rapamycin attenuates disease progression in a mouse model of Leigh syndrome (Ndufs4 knock-out (KO) mouse); however, the mechanism of rescue is unknown. Here we identify protein kinase C (PKC) downregulation as a key event mediating the beneficial effects of rapamycin treatment of Ndufs4 KO mice. Assessing the impact of rapamycin on the brain proteome and phosphoproteome of Ndufs4 KO mice, we find that rapamycin restores mitochondrial protein levels, inhibits signalling through both mTOR complexes and reduces the abundance and activity of multiple PKC isoforms. Administration of PKC inhibitors increases survival, delays neurological deficits, prevents hair loss and decreases inflammation in Ndufs4 KO mice. Thus, PKC may be a viable therapeutic target for treating severe mitochondrial disease.
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Affiliation(s)
- Miguel Martin-Perez
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Department of Cell Biology, Physiology and Immunology, University of Barcelona, Barcelona, Spain
| | - Anthony S Grillo
- Department of Pathology, University of Washington, Seattle, WA, USA
| | - Takashi K Ito
- Department of Pathology, University of Washington, Seattle, WA, USA
- RIKEN Center for Sustainable Resource Science, Saitama, Japan
| | - Anthony S Valente
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Jeehae Han
- Department of Pathology, University of Washington, Seattle, WA, USA
| | - Samuel W Entwisle
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Heather Z Huang
- Department of Pathology, University of Washington, Seattle, WA, USA
| | - Dayae Kim
- Department of Pathology, University of Washington, Seattle, WA, USA
| | - Masanao Yajima
- Department of Mathematics and Statistics, Boston University, Boston, MA, USA
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, WA, USA.
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA, USA.
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA, USA.
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211
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Peroxisome Proliferator-Activated Receptors as Molecular Links between Caloric Restriction and Circadian Rhythm. Nutrients 2020; 12:nu12113476. [PMID: 33198317 PMCID: PMC7696073 DOI: 10.3390/nu12113476] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 11/04/2020] [Accepted: 11/09/2020] [Indexed: 02/06/2023] Open
Abstract
The circadian rhythm plays a chief role in the adaptation of all bodily processes to internal and environmental changes on the daily basis. Next to light/dark phases, feeding patterns constitute the most essential element entraining daily oscillations, and therefore, timely and appropriate restrictive diets have a great capacity to restore the circadian rhythm. One of the restrictive nutritional approaches, caloric restriction (CR) achieves stunning results in extending health span and life span via coordinated changes in multiple biological functions from the molecular, cellular, to the whole-body levels. The main molecular pathways affected by CR include mTOR, insulin signaling, AMPK, and sirtuins. Members of the family of nuclear receptors, the three peroxisome proliferator-activated receptors (PPARs), PPARα, PPARβ/δ, and PPARγ take part in the modulation of these pathways. In this non-systematic review, we describe the molecular interconnection between circadian rhythm, CR-associated pathways, and PPARs. Further, we identify a link between circadian rhythm and the outcomes of CR on the whole-body level including oxidative stress, inflammation, and aging. Since PPARs contribute to many changes triggered by CR, we discuss the potential involvement of PPARs in bridging CR and circadian rhythm.
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FAK Signaling in Rhabdomyosarcoma. Int J Mol Sci 2020; 21:ijms21228422. [PMID: 33182556 PMCID: PMC7697003 DOI: 10.3390/ijms21228422] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/07/2020] [Accepted: 11/08/2020] [Indexed: 01/01/2023] Open
Abstract
Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of children and adolescents. The fusion-positive (FP)-RMS variant expressing chimeric oncoproteins such as PAX3-FOXO1 and PAX7-FOXO1 is at high risk. The fusion negative subgroup, FN-RMS, has a good prognosis when non-metastatic. Despite a multimodal therapeutic approach, FP-RMS and metastatic FN-RMS often show a dismal prognosis with 5-year survival of less than 30%. Therefore, novel targets need to be discovered to develop therapies that halt tumor progression, reducing long-term side effects in young patients. Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that regulates focal contacts at the cellular edges. It plays a role in cell motility, survival, and proliferation in response to integrin and growth factor receptors’ activation. FAK is often dysregulated in cancer, being upregulated and/or overactivated in several adult and pediatric tumor types. In RMS, both in vitro and preclinical studies point to a role of FAK in tumor cell motility/invasion and proliferation, which is inhibited by FAK inhibitors. In this review, we summarize the data on FAK expression and modulation in RMS. Moreover, we give an overview of the approaches to inhibit FAK in both preclinical and clinical cancer settings.
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Rubio C, Luna R, Rosiles A, Rubio-Osornio M. Caloric Restriction and Ketogenic Diet Therapy for Epilepsy: A Molecular Approach Involving Wnt Pathway and K ATP Channels. Front Neurol 2020; 11:584298. [PMID: 33250850 PMCID: PMC7676225 DOI: 10.3389/fneur.2020.584298] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 09/28/2020] [Indexed: 12/30/2022] Open
Abstract
Epilepsy is a neurological disorder in which, in many cases, there is poor pharmacological control of seizures. Nevertheless, it may respond beneficially to alternative treatments such as dietary therapy, like the ketogenic diet or caloric restriction. One of the mechanisms of these diets is to produce a hyperpolarization mediated by the adenosine triphosphate (ATP)-sensitive potassium (KATP) channels (KATP channels). An extracellular increase of K+ prevents the release of Ca2+ by inhibiting the signaling of the Wnt pathway and the translocation of β-catenin to the cell nucleus. Wnt ligands hyperpolarize the cells by activating K+ current by Ca2+. Each of the diets described in this paper has in common a lower use of carbohydrates, which leads to biochemical, genetic processes presumed to be involved in the reduction of epileptic seizures. Currently, there is not much information about the genetic processes implicated as well as the possible beneficial effects of diet therapy on epilepsy. In this review, we aim to describe some of the possible genes involved in Wnt pathways, their regulation through the KATP channels which are implicated in each one of the diets, and how they can reduce epileptic seizures at the molecular level.
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Affiliation(s)
- Carmen Rubio
- Neurophysiology Department, National Institute of Neurology and Neurosurgery, Manuel Velasco Suárez, Mexico City, Mexico
| | - Rudy Luna
- Neurophysiology Department, National Institute of Neurology and Neurosurgery, Manuel Velasco Suárez, Mexico City, Mexico
| | - Artemio Rosiles
- Experimental Laboratory of Neurodegenerative Diseases, National Institute of Neurology and Neurosurgery, Manuel Velasco Suárez, Mexico City, Mexico
| | - Moisés Rubio-Osornio
- Experimental Laboratory of Neurodegenerative Diseases, National Institute of Neurology and Neurosurgery, Manuel Velasco Suárez, Mexico City, Mexico
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214
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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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215
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Pataki E, Simhaev L, Engel H, Cohen A, Kupiec M, Weisman R. TOR Complex 2- independent mutations in the regulatory PIF pocket of Gad8AKT1/SGK1 define separate branches of the stress response mechanisms in fission yeast. PLoS Genet 2020; 16:e1009196. [PMID: 33137119 PMCID: PMC7660925 DOI: 10.1371/journal.pgen.1009196] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/12/2020] [Accepted: 10/14/2020] [Indexed: 12/12/2022] Open
Abstract
The Target of rapamycin (TOR) protein kinase forms part of TOR complex 1 (TORC1) and TOR complex 2 (TORC2), two multi-subunit protein complexes that regulate growth, proliferation, survival and developmental processes by phosphorylation and activation of AGC-family kinases. In the fission yeast, Schizosaccharomyces pombe, TORC2 and its target, the AGC kinase Gad8 (an orthologue of human AKT or SGK1) are required for viability under stress conditions and for developmental processes in response to starvation cues. In this study, we describe the isolation of gad8 mutant alleles that bypass the requirement for TORC2 and reveal a separation of function of TORC2 and Gad8 under stress conditions. In particular, osmotic and nutritional stress responses appear to form a separate branch from genotoxic stress responses downstream of TORC2-Gad8. Interestingly, TORC2-independent mutations map into the regulatory PIF pocket of Gad8, a highly conserved motif in AGC kinases that regulates substrate binding in PDK1 (phosphoinositide dependent kinase-1) and kinase activity in several AGC kinases. Gad8 activation is thought to require a two-step mechanism, in which phosphorylation by TORC2 allows further phosphorylation and activation by Ksg1 (an orthologue of PDK1). We focus on the Gad8-K263C mutation and demonstrate that it renders the Gad8 kinase activity independent of TORC2 in vitro and independent of the phosphorylation sites of TORC2 in vivo. Molecular dynamics simulations of Gad8-K263C revealed abnormal high flexibility at T387, the phosphorylation site for Ksg1, suggesting a mechanism for the TORC2-independent Gad8 activity. Significantly, the K263 residue is highly conserved in the family of AGC-kinases, which may suggest a general way of keeping their activity in check when acting downstream of TOR complexes. Protein kinases catalyze the transfer of phosphate from high-energy, phosphate-donating molecules, such as ATP, to their substrates. This process is pivotal for regulation of almost any aspect of cellular biology. Many human diseases are associated with aberrant functions of protein kinases due to mutations. Accordingly, there is a growing number of kinase inhibitors that have been approved for clinical use. A better understanding of how protein kinases become active and how their activity is relayed to regulate their cellular functions is much needed for rational design of kinase inhibitors and for their optimal use in the clinic. The AGC-family of protein kinases play key roles in regulating cellular growth, proliferation and survival. In human cells, as well as in the fission yeast, our cellular model system, a subgroup of the AGC kinases is activated by the TOR protein kinases. Here we report the isolation of mutations in the AGC kinase Gad8 (AKT or SGK1 in human) that bypass the requirement for activation by TOR. Analyses of how these mutations affect cellular growth revealed separate branches of stress response mechanisms downstream of Gad8, while computer simulation methods suggested a molecular mechanism that keeps the activity of Gad8 in check.
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Affiliation(s)
- Emese Pataki
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
| | - Luba Simhaev
- Blavatnik Center for Drug Discovery, Tel Aviv University, Tel Aviv, Israel
| | - Hamutal Engel
- Blavatnik Center for Drug Discovery, Tel Aviv University, Tel Aviv, Israel
| | - Adiel Cohen
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
| | - Martin Kupiec
- The Shmunis School of Biomedicine & Cancer Research, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
| | - Ronit Weisman
- Department of Natural and Life Sciences, The Open University of Israel, Ra'anana, Israel
- * E-mail:
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Scaiola A, Mangia F, Imseng S, Boehringer D, Berneiser K, Shimobayashi M, Stuttfeld E, Hall MN, Ban N, Maier T. The 3.2-Å resolution structure of human mTORC2. SCIENCE ADVANCES 2020; 6:6/45/eabc1251. [PMID: 33158864 PMCID: PMC7673708 DOI: 10.1126/sciadv.abc1251] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 09/22/2020] [Indexed: 05/22/2023]
Abstract
The protein kinase mammalian target of rapamycin (mTOR) is the central regulator of cell growth. Aberrant mTOR signaling is linked to cancer, diabetes, and neurological disorders. mTOR exerts its functions in two distinct multiprotein complexes, mTORC1 and mTORC2. Here, we report a 3.2-Å resolution cryo-EM reconstruction of mTORC2. It reveals entangled folds of the defining Rictor and the substrate-binding SIN1 subunits, identifies the carboxyl-terminal domain of Rictor as the source of the rapamycin insensitivity of mTORC2, and resolves mechanisms for mTORC2 regulation by complex destabilization. Two previously uncharacterized small-molecule binding sites are visualized, an inositol hexakisphosphate (InsP6) pocket in mTOR and an mTORC2-specific nucleotide binding site in Rictor, which also forms a zinc finger. Structural and biochemical analyses suggest that InsP6 and nucleotide binding do not control mTORC2 activity directly but rather have roles in folding or ternary interactions. These insights provide a firm basis for studying mTORC2 signaling and for developing mTORC2-specific inhibitors.
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Affiliation(s)
- Alain Scaiola
- Institute for Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Francesca Mangia
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Stefan Imseng
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | | | - Karolin Berneiser
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Mitsugu Shimobayashi
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Edward Stuttfeld
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Michael N Hall
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Nenad Ban
- Institute for Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland.
| | - Timm Maier
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland.
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217
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Indole hydrazide compound ZJQ-24 inhibits angiogenesis and induces apoptosis cell death through abrogation of AKT/mTOR pathway in hepatocellular carcinoma. Cell Death Dis 2020; 11:926. [PMID: 33116125 PMCID: PMC7595202 DOI: 10.1038/s41419-020-03108-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 09/27/2020] [Accepted: 09/30/2020] [Indexed: 12/24/2022]
Abstract
Angiogenesis and the activation of AKT/mTOR pathway are crucial for hepatocarcinoma development and progression, the activation of mTORC1/2 and relevant substrates have been confirmed in clinical hepatocarcinoma samples. Therefore, AKT/mTOR pathway represents the major targets for anti-cancer drugs development. Here, we investigated the anti-proliferative activity and mechanisms of ZJQ-24 in hepatocellular carcinoma, both in vivo and in vitro. A hepatocellular carcinoma xenograft model showed that ZJQ-24 significantly inhibited tumor growth with few side effects. MTT assays, flow cytometric analysis, Western blotting and immunohistochemistry identified that ZJQ-24 effectively suppressed hepatocellular carcinoma cell proliferation via G2/M phase arrest and caspase-dependent apoptosis but had no cytotoxic on normal cells. Furthermore, ZJQ-24 significantly blocked AKT/mTOR signaling by down-regulation of mTORC1 molecules, including phospho-p70S6K (Thr389) and phospho-4EBP-1 (Ser65, Thr37/46, Thr70) and phospho-AKT (Ser473) in HCC cells. It is very important that the ZJQ-24 did not induce the mTORC1-depdent PI3K/Akt feedback activation through JNK excitation. Moreover, ZJQ-24 inhibited the cap-dependent translation initiation by impairing the assembly of the eIF4E/eIF4G complex. Immunohistochemistry further confirmed ZJQ-24 inhibited the tumor growth through suppression of VEGF and AKT/mTOR pathways in vivo. Thus, the present study is the first to illustrate that ZJQ-24 triggers antiangiogenic activity and apoptosis via inhibiting the AKT/mTOR pathway in hepatocellular carcinoma cells, providing basic scientific evidence that ZJQ-24 shows great potential function as inhibitor of angiogenesis and tumor growth in hepatocellular carcinoma.
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218
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Požgajová M, Navrátilová A, Šebová E, Kovár M, Kačániová M. Cadmium-Induced Cell Homeostasis Impairment is Suppressed by the Tor1 Deficiency in Fission Yeast. Int J Mol Sci 2020; 21:ijms21217847. [PMID: 33105893 PMCID: PMC7660220 DOI: 10.3390/ijms21217847] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 10/10/2020] [Accepted: 10/19/2020] [Indexed: 12/16/2022] Open
Abstract
Cadmium has no known physiological function in the body; however, its adverse effects are associated with cancer and many types of organ system damage. Although much has been shown about Cd toxicity, the underlying mechanisms of its responses to the organism remain unclear. In this study, the role of Tor1, a catalytic subunit of the target of rapamycin complex 2 (TORC2), in Cd-mediated effects on cell proliferation, the antioxidant system, morphology, and ionome balance was investigated in the eukaryotic model organism Schizosaccharomyces pombe. Surprisingly, spectrophotometric and biochemical analyses revealed that the growth rate conditions and antioxidant defense mechanisms are considerably better in cells lacking the Tor1 signaling. The malondialdehyde (MDA) content of Tor1-deficient cells upon Cd treatment represents approximately half of the wild-type content. The microscopic determination of the cell morphological parameters indicates the role for Tor1 in cell shape maintenance. The ion content, determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), showed that the Cd uptake potency was markedly lower in Tor1-depleted compared to wild-type cells. Conclusively, we show that the cadmium-mediated cell impairments in the fission yeast significantly depend on the Tor1 signaling. Additionally, the data presented here suggest the yet-undefined role of Tor1 in the transport of ions.
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Affiliation(s)
- Miroslava Požgajová
- AgroBioTech Research Centre, Slovak University of Agriculture in Nitra, 949 76 Nitra, Slovakia
- Correspondence: ; Tel.: +421-37-641-4919
| | - Alica Navrátilová
- Department of Genetics and Breeding Biology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, 94976 Nitra, Slovakia;
| | - Eva Šebová
- Institute of Experimental Medicine, Czech Academy of Science, 14220 Prague, Czech Republic;
| | - Marek Kovár
- Department of Plant Physiology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, 94976 Nitra, Slovakia;
| | - Miroslava Kačániová
- Department of Fruit Science, Viticulture and Enology, Faculty of Horticulture and Landscape Engineering, Slovak University of Agriculture in Nitra, 94976 Nitra, Slovakia;
- Department of Bioenergetics, Food Analysis and Microbiology, Institute of Food Technology and Nutrition, University of Rzeszow, 35-601 Rzeszow, Poland
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219
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Scarpin MR, Leiboff S, Brunkard JO. Parallel global profiling of plant TOR dynamics reveals a conserved role for LARP1 in translation. eLife 2020; 9:e58795. [PMID: 33054972 PMCID: PMC7584452 DOI: 10.7554/elife.58795] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 10/14/2020] [Indexed: 12/15/2022] Open
Abstract
Target of rapamycin (TOR) is a protein kinase that coordinates eukaryotic metabolism. In mammals, TOR specifically promotes translation of ribosomal protein (RP) mRNAs when amino acids are available to support protein synthesis. The mechanisms controlling translation downstream from TOR remain contested, however, and are largely unexplored in plants. To define these mechanisms in plants, we globally profiled the plant TOR-regulated transcriptome, translatome, proteome, and phosphoproteome. We found that TOR regulates ribosome biogenesis in plants at multiple levels, but through mechanisms that do not directly depend on 5' oligopyrimidine tract motifs (5'TOPs) found in mammalian RP mRNAs. We then show that the TOR-LARP1-5'TOP signaling axis is conserved in plants and regulates expression of a core set of eukaryotic 5'TOP mRNAs, as well as new, plant-specific 5'TOP mRNAs. Our study illuminates ancestral roles of the TOR-LARP1-5'TOP metabolic regulatory network and provides evolutionary context for ongoing debates about the molecular function of LARP1.
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Affiliation(s)
- M Regina Scarpin
- Department of Plant and Microbial Biology, University of California at BerkeleyBerkeleyUnited States
- Plant Gene Expression Center, U.S. Department of Agriculture Agricultural Research ServiceAlbanyUnited States
| | - Samuel Leiboff
- Department of Plant and Microbial Biology, University of California at BerkeleyBerkeleyUnited States
- Plant Gene Expression Center, U.S. Department of Agriculture Agricultural Research ServiceAlbanyUnited States
- Department of Botany and Plant Pathology, Oregon State UniversityCorvallisUnited States
| | - Jacob O Brunkard
- Department of Plant and Microbial Biology, University of California at BerkeleyBerkeleyUnited States
- Plant Gene Expression Center, U.S. Department of Agriculture Agricultural Research ServiceAlbanyUnited States
- Laboratory of Genetics, University of Wisconsin—MadisonMadisonUnited States
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220
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Santos SM, Laflin S, Broadway A, Burnet C, Hartheimer J, Rodgers J, Smith DL, Hartman JL. High-resolution yeast quiescence profiling in human-like media reveals complex influences of auxotrophy and nutrient availability. GeroScience 2020; 43:941-964. [PMID: 33015753 PMCID: PMC8110628 DOI: 10.1007/s11357-020-00265-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 09/03/2020] [Indexed: 12/15/2022] Open
Abstract
Yeast cells survive in stationary phase culture by entering quiescence, which is measured by colony-forming capacity upon nutrient re-exposure. Yeast chronological lifespan (CLS) studies, employing the comprehensive collection of gene knockout strains, have correlated weakly between independent laboratories, which is hypothesized to reflect differential interaction between the deleted genes, auxotrophy, media composition, and other assay conditions influencing quiescence. This hypothesis was investigated by high-throughput quiescence profiling of the parental prototrophic strain, from which the gene deletion strain libraries were constructed, and all possible auxotrophic allele combinations in that background. Defined media resembling human cell culture media promoted long-term quiescence and was used to assess effects of glucose, ammonium sulfate, auxotrophic nutrient availability, target of rapamycin signaling, and replication stress. Frequent, high-replicate measurements of colony-forming capacity from cultures aged past 60 days provided profiles of quiescence phenomena such as gasping and hormesis. Media acidification was assayed in parallel to assess correlation. Influences of leucine, methionine, glucose, and ammonium sulfate metabolism were clarified, and a role for lysine metabolism newly characterized, while histidine and uracil perturbations had less impact. Interactions occurred between glucose, ammonium sulfate, auxotrophy, auxotrophic nutrient limitation, aeration, TOR signaling, and/or replication stress. Weak correlation existed between media acidification and maintenance of quiescence. In summary, experimental factors, uncontrolled across previous genome-wide yeast CLS studies, influence quiescence and interact extensively, revealing quiescence as a complex metabolic and developmental process that should be studied in a prototrophic context, omitting ammonium sulfate from defined media, and employing highly replicable protocols.
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Affiliation(s)
- Sean M Santos
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Samantha Laflin
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Audrie Broadway
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Cosby Burnet
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Joline Hartheimer
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - John Rodgers
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Daniel L Smith
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - John L Hartman
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA.
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221
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Chen H, Miller PW, Johnson DL, Laribee RN. The Ccr4-Not complex regulates TORC1 signaling and mitochondrial metabolism by promoting vacuole V-ATPase activity. PLoS Genet 2020; 16:e1009046. [PMID: 33064727 PMCID: PMC7592917 DOI: 10.1371/journal.pgen.1009046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 10/28/2020] [Accepted: 08/12/2020] [Indexed: 01/30/2023] Open
Abstract
The Ccr4-Not complex functions as an effector of multiple signaling pathways that control gene transcription and mRNA turnover. Consequently, Ccr4-Not contributes to a diverse array of processes, which includes a significant role in cell metabolism. Yet a mechanistic understanding of how it contributes to metabolism is lacking. Herein, we provide evidence that Ccr4-Not activates nutrient signaling through the essential target of rapamycin complex 1 (TORC1) pathway. Ccr4-Not disruption reduces global TORC1 signaling, and it also upregulates expression of the cell wall integrity (CWI) pathway terminal kinase Mpk1. Although CWI signaling represses TORC1 signaling, we find that Ccr4-Not loss inhibits TORC1 independently of CWI activation. Instead, we demonstrate that Ccr4-Not promotes the function of the vacuole V-ATPase, which interacts with the Gtr1 GTPase-containing EGO complex to stimulate TORC1 in response to nutrient sufficiency. Bypassing the V-ATPase requirement in TORC1 activation using a constitutively active Gtr1 mutant fully restores TORC1 signaling in Ccr4-Not deficient cells. Transcriptome analysis and functional studies revealed that loss of the Ccr4 subunit activates the TORC1 repressed retrograde signaling pathway to upregulate mitochondrial activity. Blocking this mitochondrial upregulation in Ccr4-Not deficient cells further represses TORC1 signaling, and it causes synergistic deficiencies in mitochondrial-dependent metabolism. These data support a model whereby Ccr4-Not loss impairs V-ATPase dependent TORC1 activation that forces cells to enhance mitochondrial metabolism to sustain a minimal level of TORC1 signaling necessary for cell growth and proliferation. Therefore, Ccr4-Not plays an integral role in nutrient signaling and cell metabolism by promoting V-ATPase dependent TORC1 activation.
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Affiliation(s)
- Hongfeng Chen
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - P. Winston Miller
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - Daniel L. Johnson
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
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Xu W, Hua H, Chiu YH, Li G, Zhi H, Yu Z, Ren F, Luo Y, Cui W. CD146 Regulates Growth Factor-Induced mTORC2 Activity Independent of the PI3K and mTORC1 Pathways. Cell Rep 2020; 29:1311-1322.e5. [PMID: 31665642 DOI: 10.1016/j.celrep.2019.09.047] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 08/09/2019] [Accepted: 09/17/2019] [Indexed: 12/21/2022] Open
Abstract
The mechanistic target of rapamycin complex 2 (mTORC2) coordinates cell proliferation, survival, and metabolism with environmental inputs, yet how extracellular stimuli such as growth factors (GFs) activate mTORC2 remains enigmatic. Here we demonstrate that in human endothelial cells, activation of mTORC2 signaling by GFs is mediated by transmembrane cell adhesion protein CD146. Upon GF stimulation, the cytoplasmic tail of CD146 is phosphorylated, which permits its positively charged, juxtamembrane KKGK motif to interact with Rictor, the defining subunit of mTORC2. The formation of the CD146-Rictor/mTORC2 complex protects Rictor from ubiquitin-proteasome-mediated degradation, thereby specifically upregulating mTORC2 activity with no intervention of the PI3K and mTORC1 pathways. This CD146-mediated mTORC2 activation in response to GF stimulation promotes cell proliferation and survival. Therefore, our findings identify a molecular mechanism by which extracellular stimuli regulate mTORC2 activity, linking environmental cues with mTORC2 regulation.
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Affiliation(s)
- Wenyi Xu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China; College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Huijuan Hua
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China; College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yueh-Ho Chiu
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Guannan Li
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China; College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Huihan Zhi
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Zhengquan Yu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China; College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Fazheng Ren
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China; College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Yongting Luo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China.
| | - Wei Cui
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK.
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Yang R, Han M, Fu Z, Wang Y, Zhao W, Yu G, Ma Z. Immune Responses of Asian Seabass Lates calcarifer to Dietary Glycyrrhiza uralensis. Animals (Basel) 2020; 10:E1629. [PMID: 32932808 PMCID: PMC7552140 DOI: 10.3390/ani10091629] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 08/26/2020] [Accepted: 09/09/2020] [Indexed: 11/29/2022] Open
Abstract
To understand the impacts of dietary Glycyrrhiza uralensis on the immune responses of Lates calcarifer, the expression of immune-related genes including crp, c-3, c-4, mtor, mlst-8, eif4e, hsp-70, hsp-90, il-8il-8, il-10, tgfβ1, tnf, ifn-γ1, and mxf in L. calcarifer juveniles was evaluated in this study. Fish were fed experimental diets with G. uralensis levels of 0%, 1%, 3%, and 5% for 56 days. The results showed that dietary G. uralensis could improve the growth and survival of L. calcarifer and regulate the immune-related genes' expression in L. calcarifer. Dietary G. uralensis significantly upregulated the expression level of crp, mtor, hsp-90, c-3, and c-4 genes in the liver of L. calcarifer, while hsp-70 gene expression was nearly downregulated. It did not upregulate the expression of elf4e and mlst-8 in the 1% and 3% inclusion groups, but it was the exact opposite in the 5% inclusion group. G. uralensis significantly affected the expression of il-8, il-10, tnf, ifn-γ1, mxf, and tgfβ1 in the head kidney of L. calcarifer. G. uralensis upregulated the expression of tnf and tgfβ1 consistently, but ifn-γ1 was at a low expression level. The expression of il-8 and il-10 was upregulated in the 1% group, while it was downregulated in the 5% group. The results from the present study indicate that dietary G. uralensis appeared to improve the immune function of L. calcarifer, and the optimum inclusion level should be between 1-3%.
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Affiliation(s)
- Rui Yang
- Tropical Aquaculture Research and Development Center, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Sanya 572018, China; (R.Y.); (M.H.); (Z.F.); (Y.W.); (W.Z.); (G.Y.)
- Key Laboratory of South China Sea Fishery Resources Exploitation and Utilization, Ministry of Agriculture and Rural Affairs, Guangzhou 510300, China
- Sanya Tropical Fisheries Research Institute, Sanya 572018, China
| | - Mingyang Han
- Tropical Aquaculture Research and Development Center, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Sanya 572018, China; (R.Y.); (M.H.); (Z.F.); (Y.W.); (W.Z.); (G.Y.)
- Sanya Tropical Fisheries Research Institute, Sanya 572018, China
| | - Zhengyi Fu
- Tropical Aquaculture Research and Development Center, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Sanya 572018, China; (R.Y.); (M.H.); (Z.F.); (Y.W.); (W.Z.); (G.Y.)
- Sanya Tropical Fisheries Research Institute, Sanya 572018, China
| | - Yifu Wang
- Tropical Aquaculture Research and Development Center, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Sanya 572018, China; (R.Y.); (M.H.); (Z.F.); (Y.W.); (W.Z.); (G.Y.)
- Sanya Tropical Fisheries Research Institute, Sanya 572018, China
| | - Wang Zhao
- Tropical Aquaculture Research and Development Center, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Sanya 572018, China; (R.Y.); (M.H.); (Z.F.); (Y.W.); (W.Z.); (G.Y.)
- Key Laboratory of South China Sea Fishery Resources Exploitation and Utilization, Ministry of Agriculture and Rural Affairs, Guangzhou 510300, China
- Sanya Tropical Fisheries Research Institute, Sanya 572018, China
| | - Gang Yu
- Tropical Aquaculture Research and Development Center, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Sanya 572018, China; (R.Y.); (M.H.); (Z.F.); (Y.W.); (W.Z.); (G.Y.)
- Key Laboratory of South China Sea Fishery Resources Exploitation and Utilization, Ministry of Agriculture and Rural Affairs, Guangzhou 510300, China
| | - Zhenhua Ma
- Tropical Aquaculture Research and Development Center, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Sanya 572018, China; (R.Y.); (M.H.); (Z.F.); (Y.W.); (W.Z.); (G.Y.)
- Key Laboratory of South China Sea Fishery Resources Exploitation and Utilization, Ministry of Agriculture and Rural Affairs, Guangzhou 510300, China
- Sanya Tropical Fisheries Research Institute, Sanya 572018, China
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Uemura S, Mochizuki T, Amemiya K, Kurosaka G, Yazawa M, Nakamoto K, Ishikawa Y, Izawa S, Abe F. Amino acid homeostatic control by TORC1 in Saccharomyces cerevisiae under high hydrostatic pressure. J Cell Sci 2020; 133:jcs245555. [PMID: 32801125 DOI: 10.1242/jcs.245555] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 08/05/2020] [Indexed: 12/30/2022] Open
Abstract
Mechanical stresses, including high hydrostatic pressure, elicit diverse physiological effects on organisms. Gtr1, Gtr2, Ego1 (also known as Meh1) and Ego3 (also known as Slm4), central regulators of the TOR complex 1 (TORC1) nutrient signaling pathway, are required for the growth of Saccharomyces cerevisiae cells under high pressure. Here, we showed that a pressure of 25 MPa (∼250 kg/cm2) stimulates TORC1 to promote phosphorylation of Sch9, which depends on the EGO complex (EGOC) and Pib2. Incubation of cells at this pressure aberrantly increased glutamine and alanine levels in the ego1Δ, gtr1Δ, tor1Δ and pib2Δ mutants, whereas the polysome profiles were unaffected. Moreover, we found that glutamine levels were reduced by combined deletions of EGO1, GTR1, TOR1 and PIB2 with GLN3 These results suggest that high pressure leads to the intracellular accumulation of amino acids. Subsequently, Pib2 loaded with glutamine stimulates the EGOC-TORC1 complex to inactivate Gln3, downregulating glutamine synthesis. Our findings illustrate the regulatory circuit that maintains intracellular amino acid homeostasis and suggest critical roles for the EGOC-TORC1 and Pib2-TORC1 complexes in the growth of yeast under high hydrostatic pressure.
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Affiliation(s)
- Satoshi Uemura
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
- Division of Medical Biochemistry, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, 1-15-1, Fukumuro, Miyagino-ku, Sendai, Miyagi 983-8536, Japan
| | - Takahiro Mochizuki
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Kengo Amemiya
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Goyu Kurosaka
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Miho Yazawa
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Keiko Nakamoto
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Yu Ishikawa
- Laboratory of Microbial Technology, Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
| | - Shingo Izawa
- Laboratory of Microbial Technology, Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
| | - Fumiyoshi Abe
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
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225
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Fu W, Hall MN. Regulation of mTORC2 Signaling. Genes (Basel) 2020; 11:E1045. [PMID: 32899613 PMCID: PMC7564249 DOI: 10.3390/genes11091045] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 12/12/2022] Open
Abstract
Mammalian target of rapamycin (mTOR), a serine/threonine protein kinase and a master regulator of cell growth and metabolism, forms two structurally and functionally distinct complexes, mTOR complex 1 (mTORC1) and mTORC2. While mTORC1 signaling is well characterized, mTORC2 is relatively poorly understood. mTORC2 appears to exist in functionally distinct pools, but few mTORC2 effectors/substrates have been identified. Here, we review recent advances in our understanding of mTORC2 signaling, with particular emphasis on factors that control mTORC2 activity.
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Affiliation(s)
- Wenxiang Fu
- Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming 650500, China
- Biozentrum, University of Basel, CH4056 Basel, Switzerland;
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Zhang X, Wu D, Wang C, Luo Y, Ding X, Yang X, Silva F, Arenas S, Weaver JM, Mandell M, Deretic V, Liu M. Sustained activation of autophagy suppresses adipocyte maturation via a lipolysis-dependent mechanism. Autophagy 2020; 16:1668-1682. [PMID: 31840569 PMCID: PMC8386625 DOI: 10.1080/15548627.2019.1703355] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Dysregulation of macroautophagy/autophagy is implicated in obesity and insulin resistance. However, it remains poorly defined how autophagy regulates adipocyte development. Using adipose-specific rptor/raptor knockout (KO), atg7 KO and atg7 rptor double-KO mice, we show that inhibiting MTORC1 by RPTOR deficiency led to autophagic sequestration of lipid droplets, formation of LD-containing lysosomes, and elevation of basal and isoproterenol-induced lipolysis in vivo and in primary adipocytes. Despite normal differentiation at an early phase, progressive degradation and shrinkage of cellular LDs and downregulation of adipogenic markers PPARG and PLIN1 occurred in terminal differentiation of rptor KO adipocytes, which was rescued by inhibiting lipolysis or lysosome. In contrast, inactivating autophagy by depletion of ATG7 protected adipocytes against RPTOR deficiency-induced formation of LD-containing lysosomes, LD degradation, and downregulation of adipogenic markers in vitro. Ultimately, atg7 rptor double-KO mice displayed decreased lipolysis, restored adipose tissue development, and upregulated thermogenic gene expression in brown and inguinal adipose tissue compared to RPTOR-deficient mice in vivo. Collectively, our study demonstrates that autophagy plays an important role in regulating adipocyte maturation via a lipophagy and lipolysis-dependent mechanism. ABBREVIATIONS ATG7: autophagy related 7; BAT: brown adipose tissue; CEBPB/C/EBPβ: CCAAT enhancer binding protein beta; DGAT1: diacylglycerol O-acyltransferase 1; eWAT: epididymal white adipose tissue; iWAT: inguinal white adipose tissue; KO: knockout; LD: lipid droplet; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; MTORC1: mechanistic target of rapamycin kinase complex 1; PLIN1: perepilin 1; PNPLA2/ATGL: patatin-like phospholipase domain containing 2; PPARG/PPARγ: peroxisome proliferator activated receptor gamma; RPTOR: regulatory associated protein of MTOR complex1; TG: triglyceride; ULK1: unc-51 like kinase 1; UCP1: uncoupling protein 1; WAT: white adipose tissue.
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Affiliation(s)
- Xing Zhang
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Dandan Wu
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Chunqing Wang
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Yan Luo
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Xiaofeng Ding
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Xin Yang
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Floyd Silva
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Sara Arenas
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - John Michael Weaver
- Autophagy Inflammation and Metabolism Center for Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Michael Mandell
- Autophagy Inflammation and Metabolism Center for Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Vojo Deretic
- Autophagy Inflammation and Metabolism Center for Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | - Meilian Liu
- Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA,CONTACT Meilian Liu Department of Biochemistry and Molecular Biology, University of New Mexico Health Sciences Center, Albuquerque, USA
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227
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Natarajan N, Thiruvenkatam V. An Insight of Scientific Developments in TSC for Better Therapeutic Strategy. Curr Top Med Chem 2020; 20:2080-2093. [PMID: 32842942 DOI: 10.2174/1568026620666200825170355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/15/2020] [Accepted: 07/20/2020] [Indexed: 11/22/2022]
Abstract
Tuberous sclerosis complex (TSC) is a rare genetic disease, which is characterized by noncancerous tumors in multi-organ systems in the body. Mutations in the TSC1 or TSC2 genes are known to cause the disease. The resultant mutant proteins TSC1 (hamartin) and TSC2 (tuberin) complex evade its normal tumor suppressor function, which leads to abnormal cell growth and proliferation. Both TSC1 and TSC2 are involved in several protein-protein interactions, which play a significant role in maintaining cellular homeostasis. The recent biochemical, genetic, structural biology, clinical and drug discovery advancements on TSC give a useful insight into the disease as well as the molecular aspects of TSC1 and TSC2. The complex nature of TSC disease, a wide range of manifestations, mosaicism and several other factors limits the treatment choices. This review is a compilation of the course of TSC, starting from its discovery to the current findings that would take us a step ahead in finding a cure for TSC.
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Affiliation(s)
- Nalini Natarajan
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat-382355, India
| | - Vijay Thiruvenkatam
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat-382355, India
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228
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Castets P, Ham DJ, Rüegg MA. The TOR Pathway at the Neuromuscular Junction: More Than a Metabolic Player? Front Mol Neurosci 2020; 13:162. [PMID: 32982690 PMCID: PMC7485269 DOI: 10.3389/fnmol.2020.00162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/05/2020] [Indexed: 12/18/2022] Open
Abstract
The neuromuscular junction (NMJ) is the chemical synapse connecting motor neurons and skeletal muscle fibers. NMJs allow all voluntary movements, and ensure vital functions like breathing. Changes in the structure and function of NMJs are hallmarks of numerous pathological conditions that affect muscle function including sarcopenia, the age-related loss of muscle mass and function. However, the molecular mechanisms leading to the morphological and functional perturbations in the pre- and post-synaptic compartments of the NMJ remain poorly understood. Here, we discuss the role of the metabolic pathway associated to the kinase TOR (Target of Rapamycin) in the development, maintenance and alterations of the NMJ. This is of particular interest as the TOR pathway has been implicated in aging, but its role at the NMJ is still ill-defined. We highlight the respective functions of the two TOR-associated complexes, TORC1 and TORC2, and discuss the role of localized protein synthesis and autophagy regulation in motor neuron terminals and sub-synaptic regions of muscle fibers and their possible effects on NMJ maintenance.
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Affiliation(s)
- Perrine Castets
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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229
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Cao G, Wu X, Wang Z, Tian X, Zhang C, Wu X, Zhang H, Jing G, Yan T. What is the optimum systemic treatment for advanced/metastatic renal cell carcinoma of favourable, intermediate and poor risk, respectively? A systematic review and network meta-analysis. BMJ Open 2020; 10:e034626. [PMID: 32859659 PMCID: PMC7454197 DOI: 10.1136/bmjopen-2019-034626] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE The optimum systemic therapies for advanced/metastatic renal cell carcinoma (RCC) of favourable, intermediate and poor risk have not been established. We aimed to compare and rank the effects associated with systemic therapies in the first-line setting. METHODS We searched PubMed, Cochrane databases, Web of Science and ClinicalTrials.gov for randomised controlled trials (RCT) published up to February 2020 of all available treatments for advanced/metastatic RCC. Analysis was done on a Bayesian framework. RESULTS 15 unique RCTs including 8995 patients were identified. For advanced/metastatic RCC of favourable risk, avelumab plus axitinib was associated with a significantly higher improvement in progression-free survival (PFS) than sunitinib (HR 0.57, 95% CI 0.34 to 0.96). For intermediate-risk patients, cabozantinib, nivolumab plus ipilimumab, pembrolizumab plus axitinib and avelumab plus axitinib were associated with significantly higher improvement in PFS than sunitinib (HR 0.63, 95% CI 0.44 to 0.97; HR 0.66, 95% CI 0.53 to 0.81; HR 0.58, 95% CI 0.44 to 0.80; HR 0.62, 95% CI 0.47 to 0.83, respectively); pembrolizumab plus axitinib and nivolumab plus ipilimumab were associated with significantly higher improvement in overall survival (OS) than sunitinib (HR 0.53, 95% CI 0.34 to 0.81; HR 0.66, 95% CI 0.50 to 0.87, respectively). For poor-risk patients, nivolumab plus ipilimumab and pembrolizumab plus axitinib were associated with significantly higher improvement in PFS than sunitinib (HR 0.57, 95% CI 0.43 to 0.76; HR 0.48, 95% CI 0.30 to 0.82, respectively); nivolumab plus ipilimumab and pembrolizumab plus axitinib were significantly more efficacious for OS than sunitinib (HR 0.57, 95% CI 0.39 to 0.883; HR 0.43, 95% CI 0.23 to 0.80, respectively). For OS, there were 81% and 78% probabilities that pembrolizumab plus axitinib was the best option for intermediate-risk and poor-risk patients, respectively. CONCLUSION Avelumab plus axitinib might be the optimum treatment for advanced/metastatic RCC of favourable risk. Pembrolizumab plus axitinib might be the optimum treatment for intermediate-risk and poor-risk patients.
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Affiliation(s)
- Guanghui Cao
- Department of Urology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
| | - Xiaoqiang Wu
- Department of Urology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
| | - Zhiwei Wang
- Department of Urology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
| | - Xiangyong Tian
- Department of Urology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
| | - Chan Zhang
- Department of Urology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
| | - Xuan Wu
- Department of Urology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
| | - Haotian Zhang
- Department of Urology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
| | - Gaopeng Jing
- Department of Urology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
| | - Tianzhong Yan
- Department of Urology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
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230
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Melick CH, Jewell JL. Regulation of mTORC1 by Upstream Stimuli. Genes (Basel) 2020; 11:genes11090989. [PMID: 32854217 PMCID: PMC7565831 DOI: 10.3390/genes11090989] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/22/2020] [Accepted: 08/23/2020] [Indexed: 01/08/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) is an evolutionary conserved Ser/Thr protein kinase that senses multiple upstream stimuli to control cell growth, metabolism, and autophagy. mTOR is the catalytic subunit of mTOR complex 1 (mTORC1). A significant amount of research has uncovered the signaling pathways regulated by mTORC1, and the involvement of these signaling cascades in human diseases like cancer, diabetes, and ageing. Here, we review advances in mTORC1 regulation by upstream stimuli. We specifically focus on how growth factors, amino acids, G-protein coupled receptors (GPCRs), phosphorylation, and small GTPases regulate mTORC1 activity and signaling.
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Affiliation(s)
- Chase H. Melick
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA;
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jenna L. Jewell
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA;
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Correspondence:
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231
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Alcaide-Gavilán M, Lucena R, Banuelos S, Kellogg DR. Conserved Ark1-related kinases function in a TORC2 signaling network. Mol Biol Cell 2020; 31:2057-2069. [PMID: 32614710 PMCID: PMC7543068 DOI: 10.1091/mbc.e19-12-0685] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In all orders of life, cell cycle progression in proliferating cells is dependent on cell growth, and the extent of growth required for cell cycle progression is proportional to growth rate. Thus, cells growing rapidly in rich nutrients are substantially larger than slow-growing cells. In budding yeast, a conserved signaling network surrounding Tor complex 2 (target of rapamycin complex 2; TORC2) controls growth rate and cell size in response to nutrient availability. Here, a search for new components of the TORC2 network identified a pair of redundant kinase paralogues called Ark1 and Prk1. Previous studies found that Ark/Prk play roles in endocytosis. Here, we show that Ark/Prk are embedded in the TORC2 network, where they appear to influence TORC2 signaling independently of their roles in endocytosis. We also show that reduced endocytosis leads to increased cell size, which suggests that cell size homeostasis requires coordinated control of plasma membrane growth and endocytosis. The discovery that Ark/Prk are embedded in the TORC2 network suggests a model in which TORC2-dependent signals control both plasma membrane growth and endocytosis, which would ensure that the rates of each process are matched to each other and to the availability of nutrients so that cells achieve and maintain an appropriate size.
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Affiliation(s)
- Maria Alcaide-Gavilán
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Rafael Lucena
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Selene Banuelos
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Douglas R Kellogg
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
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232
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Ruta LL, Farcasanu IC. Saccharomyces cerevisiae and Caffeine Implications on the Eukaryotic Cell. Nutrients 2020; 12:nu12082440. [PMID: 32823708 PMCID: PMC7468979 DOI: 10.3390/nu12082440] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/07/2020] [Accepted: 08/10/2020] [Indexed: 02/07/2023] Open
Abstract
Caffeine-a methylxanthine analogue of the purine bases adenine and guanine-is by far the most consumed neuro-stimulant, being the active principle of widely consumed beverages such as coffee, tea, hot chocolate, and cola. While the best-known action of caffeine is to prevent sleepiness by blocking the adenosine receptors, caffeine exerts a pleiotropic effect on cells, which lead to the activation or inhibition of various cell integrity pathways. The aim of this review is to present the main studies set to investigate the effects of caffeine on cells using the model eukaryotic microorganism Saccharomyces cerevisiae, highlighting the caffeine synergy with external cell stressors, such as irradiation or exposure to various chemical hazards, including cigarette smoke or chemical carcinogens. The review also focuses on the importance of caffeine-related yeast phenotypes used to resolve molecular mechanisms involved in cell signaling through conserved pathways, such as target of rapamycin (TOR) signaling, Pkc1-Mpk1 mitogen activated protein kinase (MAPK) cascade, or Ras/cAMP protein kinase A (PKA) pathway.
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233
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Tafur L, Kefauver J, Loewith R. Structural Insights into TOR Signaling. Genes (Basel) 2020; 11:E885. [PMID: 32759652 PMCID: PMC7464330 DOI: 10.3390/genes11080885] [Citation(s) in RCA: 24] [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: 07/09/2020] [Revised: 07/31/2020] [Accepted: 08/02/2020] [Indexed: 12/31/2022] Open
Abstract
The Target of Rapamycin (TOR) is a highly conserved serine/threonine protein kinase that performs essential roles in the control of cellular growth and metabolism. TOR acts in two distinct multiprotein complexes, TORC1 and TORC2 (mTORC1 and mTORC2 in humans), which maintain different aspects of cellular homeostasis and orchestrate the cellular responses to diverse environmental challenges. Interest in understanding TOR signaling is further motivated by observations that link aberrant TOR signaling to a variety of diseases, ranging from epilepsy to cancer. In the last few years, driven in large part by recent advances in cryo-electron microscopy, there has been an explosion of available structures of (m)TORC1 and its regulators, as well as several (m)TORC2 structures, derived from both yeast and mammals. In this review, we highlight and summarize the main findings from these reports and discuss both the fascinating and unexpected molecular biology revealed and how this knowledge will potentially contribute to new therapeutic strategies to manipulate signaling through these clinically relevant pathways.
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Affiliation(s)
- Lucas Tafur
- Department of Molecular Biology, University of Geneva, 30 quai Ernest-Ansermet, CH1211 Geneva, Switzerland; (L.T.); (J.K.)
| | - Jennifer Kefauver
- Department of Molecular Biology, University of Geneva, 30 quai Ernest-Ansermet, CH1211 Geneva, Switzerland; (L.T.); (J.K.)
| | - Robbie Loewith
- Department of Molecular Biology, University of Geneva, 30 quai Ernest-Ansermet, CH1211 Geneva, Switzerland; (L.T.); (J.K.)
- Swiss National Centre for Competence in Research (NCCR) in Chemical Biology, University of Geneva, Sciences II, Room 3-308, 30 Quai Ernest-Ansermet, CH1211 Geneva, Switzerland
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Kumar A, Daware A, Kumar A, Kumar V, Gopala Krishnan S, Mondal S, Patra BC, Singh AK, Tyagi AK, Parida SK, Thakur JK. Genome-wide analysis of polymorphisms identified domestication-associated long low-diversity region carrying important rice grain size/weight quantitative trait loci. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1525-1547. [PMID: 32432802 DOI: 10.1111/tpj.14845] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 05/01/2020] [Accepted: 05/12/2020] [Indexed: 05/02/2023]
Abstract
Rice grain size and weight are major determinants of grain quality and yield and so have been under rigorous selection since domestication. However, the genetic basis for contrasting grain size/weight trait among Indian germplasms and their association with domestication-driven evolution is not well understood. In this study, two long (LGG) and two short grain (SGG) genotypes were resequenced. LGG (LGR and PB 1121) differentiated from SGG (Sonasal and Bindli) by 504 439 single nucleotide polymorphisms (SNPs) and 78 166 insertion-and-deletion polymorphisms. The LRK gene cluster was different and a truncation mutation in the LRK8 kinase domain was associated with LGG. Phylogeny with 3000 diverse rice accessions revealed that the four sequenced genotypes belonged to the japonica group and were at the edge of the clades indicating them to be the potential source of genetic diversity available in Indian rice germplasm. Six SNPs were significantly associated with grain size/weight and the top four of these could be validated in mapping a population, suggesting this study as a valuable resource for high-throughput genotyping. A contiguous long low-diversity region (LDR) of approximately 6 Mb carrying a major grain weight quantitative trait loci (harbouring OsTOR gene) was identified on Chromosome 5. This LDR was identified as an evolutionary important site with significant positive selection and multiple selection sweeps, and showed association with many domestication-related traits, including grain size/weight. The aus population retained more allelic variations in the LDR than the japonica and indica populations, suggesting it to be one of the divergence loci. All the data and analyses can be accessed from the RiceSzWtBase database.
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Affiliation(s)
- Angad Kumar
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Anurag Daware
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Arvind Kumar
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Vinay Kumar
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - S Gopala Krishnan
- Division of Genetics, ICAR-Indian Agricultural Research Institute, Pusa, New Delhi, 110012, India
| | - Subhasish Mondal
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Bhaskar C Patra
- Crop Improvement Division, ICAR-National Rice Research Institute, Cuttack, 753006, India
| | - Ashok K Singh
- Division of Genetics, ICAR-Indian Agricultural Research Institute, Pusa, New Delhi, 110012, India
| | - Akhilesh K Tyagi
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India
| | - Swarup K Parida
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Jitendra K Thakur
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
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235
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Xu T, Sun D, Chen Y, Ouyang L. Targeting mTOR for fighting diseases: A revisited review of mTOR inhibitors. Eur J Med Chem 2020; 199:112391. [DOI: 10.1016/j.ejmech.2020.112391] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/24/2020] [Accepted: 04/24/2020] [Indexed: 02/07/2023]
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Escamilla-Ramírez A, Castillo-Rodríguez RA, Zavala-Vega S, Jimenez-Farfan D, Anaya-Rubio I, Briseño E, Palencia G, Guevara P, Cruz-Salgado A, Sotelo J, Trejo-Solís C. Autophagy as a Potential Therapy for Malignant Glioma. Pharmaceuticals (Basel) 2020; 13:ph13070156. [PMID: 32707662 PMCID: PMC7407942 DOI: 10.3390/ph13070156] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 07/01/2020] [Accepted: 07/14/2020] [Indexed: 02/06/2023] Open
Abstract
Glioma is the most frequent and aggressive type of brain neoplasm, being anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM), its most malignant forms. The survival rate in patients with these neoplasms is 15 months after diagnosis, despite a diversity of treatments, including surgery, radiation, chemotherapy, and immunotherapy. The resistance of GBM to various therapies is due to a highly mutated genome; these genetic changes induce a de-regulation of several signaling pathways and result in higher cell proliferation rates, angiogenesis, invasion, and a marked resistance to apoptosis; this latter trait is a hallmark of highly invasive tumor cells, such as glioma cells. Due to a defective apoptosis in gliomas, induced autophagic death can be an alternative to remove tumor cells. Paradoxically, however, autophagy in cancer can promote either a cell death or survival. Modulating the autophagic pathway as a death mechanism for cancer cells has prompted the use of both inhibitors and autophagy inducers. The autophagic process, either as a cancer suppressing or inducing mechanism in high-grade gliomas is discussed in this review, along with therapeutic approaches to inhibit or induce autophagy in pre-clinical and clinical studies, aiming to increase the efficiency of conventional treatments to remove glioma neoplastic cells.
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Affiliation(s)
- Angel Escamilla-Ramírez
- Departamento de Neuroinmunología, Instituto Nacional de Neurología y Neurocirugía, Ciudad de México 14269, Mexico; (A.E.-R.); (I.A.-R.); (G.P.); (P.G.); (A.C.-S.); (J.S.)
| | - Rosa A. Castillo-Rodríguez
- Laboratorio de Oncología Experimental, CONACYT-Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico;
| | - Sergio Zavala-Vega
- Departamento de Patología, Instituto Nacional de Neurología y Neurocirugía, Ciudad de México 14269, Mexico;
| | - Dolores Jimenez-Farfan
- Laboratorio de Inmunología, División de Estudios de Posgrado e Investigación, Facultad de Odontología, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico;
| | - Isabel Anaya-Rubio
- Departamento de Neuroinmunología, Instituto Nacional de Neurología y Neurocirugía, Ciudad de México 14269, Mexico; (A.E.-R.); (I.A.-R.); (G.P.); (P.G.); (A.C.-S.); (J.S.)
| | - Eduardo Briseño
- Clínica de Neurooncología, Instituto Nacional de Neurología y Neurocirugía, Ciudad de México 14269, Mexico;
| | - Guadalupe Palencia
- Departamento de Neuroinmunología, Instituto Nacional de Neurología y Neurocirugía, Ciudad de México 14269, Mexico; (A.E.-R.); (I.A.-R.); (G.P.); (P.G.); (A.C.-S.); (J.S.)
| | - Patricia Guevara
- Departamento de Neuroinmunología, Instituto Nacional de Neurología y Neurocirugía, Ciudad de México 14269, Mexico; (A.E.-R.); (I.A.-R.); (G.P.); (P.G.); (A.C.-S.); (J.S.)
| | - Arturo Cruz-Salgado
- Departamento de Neuroinmunología, Instituto Nacional de Neurología y Neurocirugía, Ciudad de México 14269, Mexico; (A.E.-R.); (I.A.-R.); (G.P.); (P.G.); (A.C.-S.); (J.S.)
| | - Julio Sotelo
- Departamento de Neuroinmunología, Instituto Nacional de Neurología y Neurocirugía, Ciudad de México 14269, Mexico; (A.E.-R.); (I.A.-R.); (G.P.); (P.G.); (A.C.-S.); (J.S.)
| | - Cristina Trejo-Solís
- Departamento de Neuroinmunología, Instituto Nacional de Neurología y Neurocirugía, Ciudad de México 14269, Mexico; (A.E.-R.); (I.A.-R.); (G.P.); (P.G.); (A.C.-S.); (J.S.)
- Correspondence: ; Tel.: +52-555-060-4040
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Peroxisome Proliferator-Activated Receptors and Caloric Restriction-Common Pathways Affecting Metabolism, Health, and Longevity. Cells 2020; 9:cells9071708. [PMID: 32708786 PMCID: PMC7407644 DOI: 10.3390/cells9071708] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 02/06/2023] Open
Abstract
Caloric restriction (CR) is a traditional but scientifically verified approach to promoting health and increasing lifespan. CR exerts its effects through multiple molecular pathways that trigger major metabolic adaptations. It influences key nutrient and energy-sensing pathways including mammalian target of rapamycin, Sirtuin 1, AMP-activated protein kinase, and insulin signaling, ultimately resulting in reductions in basic metabolic rate, inflammation, and oxidative stress, as well as increased autophagy and mitochondrial efficiency. CR shares multiple overlapping pathways with peroxisome proliferator-activated receptors (PPARs), particularly in energy metabolism and inflammation. Consequently, several lines of evidence suggest that PPARs might be indispensable for beneficial outcomes related to CR. In this review, we present the available evidence for the interconnection between CR and PPARs, highlighting their shared pathways and analyzing their interaction. We also discuss the possible contributions of PPARs to the effects of CR on whole organism outcomes.
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238
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Athanasopoulos A, André B, Sophianopoulou V, Gournas C. Fungal plasma membrane domains. FEMS Microbiol Rev 2020; 43:642-673. [PMID: 31504467 DOI: 10.1093/femsre/fuz022] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/25/2019] [Indexed: 12/11/2022] Open
Abstract
The plasma membrane (PM) performs a plethora of physiological processes, the coordination of which requires spatial and temporal organization into specialized domains of different sizes, stability, protein/lipid composition and overall architecture. Compartmentalization of the PM has been particularly well studied in the yeast Saccharomyces cerevisiae, where five non-overlapping domains have been described: The Membrane Compartments containing the arginine permease Can1 (MCC), the H+-ATPase Pma1 (MCP), the TORC2 kinase (MCT), the sterol transporters Ltc3/4 (MCL), and the cell wall stress mechanosensor Wsc1 (MCW). Additional cortical foci at the fungal PM are the sites where clathrin-dependent endocytosis occurs, the sites where the external pH sensing complex PAL/Rim localizes, and sterol-rich domains found in apically grown regions of fungal membranes. In this review, we summarize knowledge from several fungal species regarding the organization of the lateral PM segregation. We discuss the mechanisms of formation of these domains, and the mechanisms of partitioning of proteins there. Finally, we discuss the physiological roles of the best-known membrane compartments, including the regulation of membrane and cell wall homeostasis, apical growth of fungal cells and the newly emerging role of MCCs as starvation-protective membrane domains.
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Affiliation(s)
- Alexandros Athanasopoulos
- Microbial Molecular Genetics Laboratory, Institute of Biosciences and Applications, National Centre for Scientific Research 'Demokritos,' Patr. Grigoriou E & 27 Neapoleos St. 15341, Agia Paraskevi, Greece
| | - Bruno André
- Molecular Physiology of the Cell laboratory, Université Libre de Bruxelles (ULB), Institut de Biologie et de Médecine Moléculaires, rue des Pr Jeener et Brachet 12, 6041, Gosselies, Belgium
| | - Vicky Sophianopoulou
- Microbial Molecular Genetics Laboratory, Institute of Biosciences and Applications, National Centre for Scientific Research 'Demokritos,' Patr. Grigoriou E & 27 Neapoleos St. 15341, Agia Paraskevi, Greece
| | - Christos Gournas
- Microbial Molecular Genetics Laboratory, Institute of Biosciences and Applications, National Centre for Scientific Research 'Demokritos,' Patr. Grigoriou E & 27 Neapoleos St. 15341, Agia Paraskevi, Greece
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TLR2/6 signaling promotes the expansion of premalignant hematopoietic stem and progenitor cells in the NUP98-HOXD13 mouse model of MDS. Exp Hematol 2020; 88:42-55. [PMID: 32652111 PMCID: PMC7673652 DOI: 10.1016/j.exphem.2020.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/19/2020] [Accepted: 07/03/2020] [Indexed: 01/23/2023]
Abstract
Toll-like receptor 2 (TLR2) expression is increased on hematopoietic stem and progenitor cells (HSPCs) of patients with myelodysplastic syndromes (MDS), and enhanced TLR2 signaling is thought to contribute to MDS pathogenesis. Notably, TLR2 heterodimerizes with TLR1 or TLR6, and while high TLR2 is associated with lower-risk disease, high TLR6, but not TLR1, correlates with higher-risk disease. This raises the possibility of heterodimer-specific effects of TLR2 signaling in MDS, and in the work described here, we tested the effects of specific modulation of TLR1/2 versus TLR2/6 signaling on premalignant HSPCs. Indeed, chronic stimulation of TLR2/6, but not TLR1/2, accelerates leukemic transformation in the NHD13 mouse model of MDS, and conversely, loss of TLR6, but not TLR1, slows this process. TLR2/6 stimulation expands premalignant HSPCs, and chimeric mouse studies revealed that cell-autonomous signaling contributes to this expansion. Finally, TLR2/6 stimulation is associated with an enrichment of Myc and mTORC1 activities. While Myc inhibition partially suppressed the TLR2/6 agonist-mediated expansion of premalignant HSPCs, inhibition of mTORC1 exacerbated it, suggesting that these pathways play opposite roles in regulating the effects of TLR2/6 ligation on HSPCs. Together, these data reveal heterodimer-specific effects of TLR2 signaling on premalignant HSPCs, with TLR2/6 signaling promoting their expansion and leukemic transformation.
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240
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Qian J, Su S, Liu P. Experimental Approaches in Delineating mTOR Signaling. Genes (Basel) 2020; 11:E738. [PMID: 32630768 PMCID: PMC7397015 DOI: 10.3390/genes11070738] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 06/28/2020] [Accepted: 06/30/2020] [Indexed: 11/16/2022] Open
Abstract
The mTOR signaling controls essential biological functions including proliferation, growth, metabolism, autophagy, ageing, and others. Hyperactivation of mTOR signaling leads to a plethora of human disorders; thus, mTOR is an attractive drug target. The discovery of mTOR signaling started from isolation of rapamycin in 1975 and cloning of TOR genes in 1993. In the past 27 years, numerous research groups have contributed significantly to advancing our understanding of mTOR signaling and mTOR biology. Notably, a variety of experimental approaches have been employed in these studies to identify key mTOR pathway members that shape up the mTOR signaling we know today. Technique development drives mTOR research, while canonical biochemical and yeast genetics lay the foundation for mTOR studies. Here in this review, we summarize major experimental approaches used in the past in delineating mTOR signaling, including biochemical immunoprecipitation approaches, genetic approaches, immunofluorescence microscopic approaches, hypothesis-driven studies, protein sequence or motif search driven approaches, and bioinformatic approaches. We hope that revisiting these distinct types of experimental approaches will provide a blueprint for major techniques driving mTOR research. More importantly, we hope that thinking and reasonings behind these experimental designs will inspire future mTOR research as well as studies of other protein kinases beyond mTOR.
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Affiliation(s)
- Jiayi Qian
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.Q.); (S.S.)
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Siyuan Su
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.Q.); (S.S.)
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Pengda Liu
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.Q.); (S.S.)
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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241
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Moniliophthora perniciosa development: key genes involved in stress-mediated cell wall organization and autophagy. Int J Biol Macromol 2020; 154:1022-1035. [PMID: 32194118 DOI: 10.1016/j.ijbiomac.2020.03.125] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 02/29/2020] [Accepted: 03/13/2020] [Indexed: 12/11/2022]
Abstract
Moniliophthora perniciosa is a basidiomycete responsible for the witches' broom disease in cacao (Theobroma cacao L.). Chitin synthase (CHS), chitinase (CHIT) and autophagy (ATG) genes have been associated to stress response preceding the formation of basidiocarp. An analysis of literature mining, interactomics and gene expression was developed to identify the main proteins related to development, cell wall organization and autophagy in M. perniciosa. TORC2 complex elements were identified and were involved in the response to the nutrient starvation during the fungus development stages preceding the basidiocarp formation. This complex interacted with target proteins related to cell wall synthesis and to polarization and cell division (FKS1, CHS, CDC42, ROM2). Autolysis and autophagy processes were associated to CHIT2, ATG8 and to the TORC1 complex (TOR1 and KOG1), which is central in the upstream signalization of the stress response due to nutrient starvation and growth regulation. Other important elements that participate to steps preceding basidiocarp formation were also identified (KOG1, SSZ1, GDI1, FKS1, CCD10, CKS1, CDC42, RHO1, AVO1, BAG7). Similar gene expression patterns during fungus reproductive structure formation and when treated by rapamycin (a nutritional related-autophagy stress agent) were observed: cell division related-genes were repressed while those related to autolysis/autophagy were overexpressed.
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242
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Shorning BY, Dass MS, Smalley MJ, Pearson HB. The PI3K-AKT-mTOR Pathway and Prostate Cancer: At the Crossroads of AR, MAPK, and WNT Signaling. Int J Mol Sci 2020; 21:E4507. [PMID: 32630372 PMCID: PMC7350257 DOI: 10.3390/ijms21124507] [Citation(s) in RCA: 287] [Impact Index Per Article: 71.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/22/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022] Open
Abstract
Oncogenic activation of the phosphatidylinositol-3-kinase (PI3K), protein kinase B (PKB/AKT), and mammalian target of rapamycin (mTOR) pathway is a frequent event in prostate cancer that facilitates tumor formation, disease progression and therapeutic resistance. Recent discoveries indicate that the complex crosstalk between the PI3K-AKT-mTOR pathway and multiple interacting cell signaling cascades can further promote prostate cancer progression and influence the sensitivity of prostate cancer cells to PI3K-AKT-mTOR-targeted therapies being explored in the clinic, as well as standard treatment approaches such as androgen-deprivation therapy (ADT). However, the full extent of the PI3K-AKT-mTOR signaling network during prostate tumorigenesis, invasive progression and disease recurrence remains to be determined. In this review, we outline the emerging diversity of the genetic alterations that lead to activated PI3K-AKT-mTOR signaling in prostate cancer, and discuss new mechanistic insights into the interplay between the PI3K-AKT-mTOR pathway and several key interacting oncogenic signaling cascades that can cooperate to facilitate prostate cancer growth and drug-resistance, specifically the androgen receptor (AR), mitogen-activated protein kinase (MAPK), and WNT signaling cascades. Ultimately, deepening our understanding of the broader PI3K-AKT-mTOR signaling network is crucial to aid patient stratification for PI3K-AKT-mTOR pathway-directed therapies, and to discover new therapeutic approaches for prostate cancer that improve patient outcome.
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Affiliation(s)
| | | | | | - Helen B. Pearson
- The European Cancer Stem Cell Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, Wales, UK; (B.Y.S.); (M.S.D.); (M.J.S.)
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243
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Laribee RN, Weisman R. Nuclear Functions of TOR: Impact on Transcription and the Epigenome. Genes (Basel) 2020; 11:E641. [PMID: 32532005 PMCID: PMC7349558 DOI: 10.3390/genes11060641] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/04/2020] [Accepted: 06/09/2020] [Indexed: 12/15/2022] Open
Abstract
The target of rapamycin (TOR) protein kinase is at the core of growth factor- and nutrient-dependent signaling pathways that are well-known for their regulation of metabolism, growth, and proliferation. However, TOR is also involved in the regulation of gene expression, genomic and epigenomic stability. TOR affects nuclear functions indirectly through its activity in the cytoplasm, but also directly through active nuclear TOR pools. The mechanisms by which TOR regulates its nuclear functions are less well-understood compared with its cytoplasmic activities. TOR is an important pharmacological target for several diseases, including cancer, metabolic and neurological disorders. Thus, studies of the nuclear functions of TOR are important for our understanding of basic biological processes, as well as for clinical implications.
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Affiliation(s)
- R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and Center for Cancer Research, University of Tennessee Health Science Center, 19 South Manassas, Cancer Research Building Rm 318, Memphis, TN 38163, USA
| | - Ronit Weisman
- Department of Natural and Life Sciences, The Open University of Israel, University Road 1, Ra’anana 4353701, Israel
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Jeong YJ, Hwang SK, Magae J, Chang YC. Ascofuranone suppresses invasion and F-actin cytoskeleton organization in cancer cells by inhibiting the mTOR complex 1 signaling pathway. Cell Oncol (Dordr) 2020; 43:793-805. [PMID: 32488849 DOI: 10.1007/s13402-020-00520-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 03/29/2020] [Accepted: 04/15/2020] [Indexed: 11/28/2022] Open
Abstract
PURPOSE Ascofuranone is an antiviral antibiotic that is known to exert multiple anti-tumor effects, including cell cycle arrest, inhibition of mitochondrial respiration, and inhibition of angiogenesis. In this study, we investigated the molecular mechanisms underlying the anti-metastatic effects of ascofuranone in insulin-like growth factor-I (IGF-1)-responsive cancer cells. METHODS The inhibitory effect of ascofuranone on cancer cell migration and invasion was assessed using scratch wound healing and Matrigel invasion assays, respectively. F-actin cytoskeleton organization was assessed using FITC conjugated phalloidin staining. Target gene expression was evaluated using Western blotting and gene silencing was performed using siRNA transfections. Finally, the anti-metastatic effect of ascofuranone was investigated in vivo. RESULTS We found that ascofuranone suppressed IGF-1-induced cell migration, invasion and motility in multiple cancer cell lines. The effects of ascofuranone on actin cytoskeleton organization were found to be mediated by suppression of the mTOR/p70S6K/4EBP1 pathway. Ascofuranone inhibited IGF-1-induced mTOR phosphorylation and actin cytoskeleton organization via upregulation of AMPK and downregulation of Akt phosphorylation. It also selectively suppressed the IGF-1-induced mTOR complex (mTORC)1 by phosphorylation of Raptor, but did not affect mTORC2. Furthermore, we found that focal adhesion kinase (FAK) activation decreased in response to ascofuranone, rapamycin, compound C and wortmannin treatment. Finally, we found that ascofuranone suppressed phosphorylation of FAK and mTOR and dephosphorylation of Raptor in cancerous metastatic lung tissues in vivo. CONCLUSIONS Our data indicate that ascofuranone suppresses IGF-1-induced cancer cell migration and invasion by blocking actin cytoskeleton organization and FAK activation through inhibition of the mTORC1 pathway, and reveal a novel anti-metastatic function of this compound.
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Affiliation(s)
- Yun-Jeong Jeong
- Research Institute of Biomedical Engineering, Department of Medicine, Catholic University of Daegu School of Medicine, 42472, Deagu, Korea
| | - Soon-Kyung Hwang
- Research Institute of Biomedical Engineering, Department of Medicine, Catholic University of Daegu School of Medicine, 42472, Deagu, Korea
| | - Junji Magae
- Magae Bioscience Institute, 49-4 Fujimidai, 300-1263, Tsukuba, Japan
| | - Young-Chae Chang
- Research Institute of Biomedical Engineering, Department of Medicine, Catholic University of Daegu School of Medicine, 42472, Deagu, Korea. .,Department of Cell Biology, Catholic University of Daegu School of Medicine, 3056-6, Daemyung-4-Dong, Nam-gu, 42472, Daegu, Korea.
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Small molecule H89 renders the phosphorylation of S6K1 and AKT resistant to mTOR inhibitors. Biochem J 2020; 477:1847-1863. [PMID: 32347294 PMCID: PMC7261416 DOI: 10.1042/bcj20190958] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 04/27/2020] [Accepted: 04/28/2020] [Indexed: 11/30/2022]
Abstract
The mammalian target of rapamycin (mTOR) is an evolutionarily conserved Ser/Thr kinase that comprises two complexes, termed mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). mTORC1 phosphorylates S6K1 at Thr 389, whereas mTORC2 phosphorylates AKT at Ser 473 to promote cell growth. As the mTOR name implies it is the target of natural product called rapamycin, a clinically approved drug used to treat human disease. Short-term rapamycin treatment inhibits the kinase activity of mTORC1 but not mTORC2. However, the ATP-competitive catalytic mTOR inhibitor Torin1 was identified to inhibit the kinase activity of both mTORC1 and mTORC2. Here, we report that H89 (N-(2-(4-bromocinnamylamino) ethyl)-5-isoquinolinesulfonamide), a well-characterized ATP-mimetic kinase inhibitor, renders the phosphorylation of S6K1 and AKT resistant to mTOR inhibitors across multiple cell lines. Moreover, H89 prevented the dephosphorylation of AKT and S6K1 under nutrient depleted conditions. PKA and other known H89-targeted kinases do not alter the phosphorylation status of S6K1 and AKT. Pharmacological inhibition of some phosphatases also enhanced S6K1 and AKT phosphorylation. These findings suggest a new target for H89 by which it sustains the phosphorylation status of S6K1 and AKT, resulting in mTOR signaling.
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Abstract
A complex molecular machinery converges on the surface of lysosomes to ensure that the growth-promoting signaling mediated by mechanistic target of rapamycin complex 1 (mTORC1) is tightly controlled by the availability of nutrients and growth factors. The final step in this activation process is dependent on Rheb, a small GTPase that binds to mTOR and allosterically activates its kinase activity. Here we review the mechanisms that determine the subcellular localization of Rheb (and the closely related RhebL1 protein) as well as the significance of these mechanisms for controlling mTORC1 activation. In particular, we explore how the relatively weak membrane interactions conferred by C-terminal farnesylation are critical for the ability of Rheb to activate mTORC1. In addition to supporting transient membrane interactions, Rheb C-terminal farnesylation also supports an interaction between Rheb and the δ subunit of phosphodiesterase 6 (PDEδ). This interaction provides a potential mechanism for targeting Rheb to membranes that contain Arl2, a small GTPase that triggers the release of prenylated proteins from PDEδ. The minimal membrane targeting conferred by C-terminal farnesylation of Rheb and RhebL1 distinguishes them from other members of the Ras superfamily that possess additional membrane interaction motifs that work with farnesylation for enrichment on the specific subcellular membranes where they engage key effectors. Finally, we highlight diversity in Rheb membrane targeting mechanisms as well as the potential for alternative mTORC1 activation mechanisms across species.
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Affiliation(s)
- Brittany Angarola
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
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247
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Lee J, Lunde-Young R, Naik V, Ramirez J, Orzabal M, Ramadoss J. Chronic Binge Alcohol Exposure During Pregnancy Alters mTOR System in Rat Fetal Hippocampus. Alcohol Clin Exp Res 2020; 44:1329-1336. [PMID: 32333810 DOI: 10.1111/acer.14348] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 04/10/2020] [Accepted: 04/19/2020] [Indexed: 01/04/2023]
Abstract
BACKGROUND Gestational alcohol exposure can contribute to fetal alcohol spectrum disorders (FASD), an array of cognitive, behavioral, and physical developmental impairments. Mammalian target of rapamycin (mTOR) plays a key role in regulating protein synthesis in response to neuronal activity, thereby modulating synaptic plasticity and long-term memory formation in the brain. Based on our previous quantitative mass spectrometry proteomic studies, we hypothesized that gestational chronic binge alcohol exposure alters mTOR signaling and downstream pathways in the fetal hippocampus. METHODS Pregnant Sprague-Dawley rats were assigned to either a pair-fed control (PF-Cont) or a binge alcohol (Alcohol) treatment group. Alcohol dams were acclimatized via a once-daily orogastric gavage of 4.5 g/kg alcohol (peak BAC, 216 mg/dl) from GD 5-10 and progressed to 6 g/kg alcohol (peak BAC, 289 mg/dl) from GD 11-21. Pair-fed dams similarly received isocaloric maltose dextrin. RESULTS In the Alcohol group, following this exposure paradigm, fetal body weight and crown-rump length were decreased. The phosphorylation level of mTOR (P-mTOR) in the fetal hippocampus was decreased in the Alcohol group compared with controls. Alcohol exposure resulted in dysregulation of fetal hippocampal mTORC1 signaling, as evidenced by an increase in total 4E-BP1 expression. Phosphorylation levels of 4E-BP1 and p70 S6K were also increased following alcohol exposure. P-mTOR and P-4E-BP1 were exclusively detected in the dentate gyrus and oriens layer of the fetal hippocampus, respectively. DEPTOR and RICTOR expression levels in the fetal hippocampus were increased; however, RAPTOR was not altered by chronic binge alcohol exposure. CONCLUSION We conclude that chronic binge alcohol exposure during pregnancy alters mTORC1 signaling pathway in the fetal hippocampus. We conjecture that this dysregulation of mTOR protein expression, its activity, and downstream proteins may play a critical role in FASD neurobiological phenotypes.
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Affiliation(s)
- Jehoon Lee
- From the, Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Raine Lunde-Young
- From the, Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Vishal Naik
- From the, Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Josue Ramirez
- From the, Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Marcus Orzabal
- From the, Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Jayanth Ramadoss
- From the, Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
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248
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Riggi M, Kusmider B, Loewith R. The flipside of the TOR coin - TORC2 and plasma membrane homeostasis at a glance. J Cell Sci 2020; 133:133/9/jcs242040. [PMID: 32393676 DOI: 10.1242/jcs.242040] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Target of rapamycin (TOR) is a serine/threonine protein kinase conserved in most eukaryote organisms. TOR assembles into two multiprotein complexes (TORC1 and TORC2), which function as regulators of cellular growth and homeostasis by serving as direct transducers of extracellular biotic and abiotic signals, and, through their participation in intrinsic feedback loops, respectively. TORC1, the better-studied complex, is mainly involved in cell volume homeostasis through regulating accumulation of proteins and other macromolecules, while the functions of the lesser-studied TORC2 are only now starting to emerge. In this Cell Science at a Glance article and accompanying poster, we aim to highlight recent advances in our understanding of TORC2 signalling, particularly those derived from studies in yeast wherein TORC2 has emerged as a major regulator of cell surface homeostasis.
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Affiliation(s)
- Margot Riggi
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland.,Department of Biochemistry, University of Geneva, Geneva, Switzerland.,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Beata Kusmider
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland.,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Robbie Loewith
- Swiss National Centre for Competence in Research Program Chemical Biology, Geneva, Switzerland .,Department of Molecular Biology, University of Geneva, Geneva, Switzerland
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249
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Park KT, Han JK, Kim SJ, Lim YH. Gamma-Aminobutyric Acid Increases Erythropoietin by Activation of Citrate Cycle and Stimulation of Hypoxia-Inducible Factors Expression in Rats. Biomolecules 2020; 10:E595. [PMID: 32290638 PMCID: PMC7226430 DOI: 10.3390/biom10040595] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 04/04/2020] [Accepted: 04/09/2020] [Indexed: 02/07/2023] Open
Abstract
Erythropoietin (EPO) is the primary regulator of erythropoiesis in the mammalian fetus and adult. Deficiency of EPO induces anemia. In this study, we investigated the effect of gamma-aminobutyric acid (GABA) on serum EPO levels and erythropoiesis in rats. Expression levels of Epo-related genes were measured by quantitative real-time PCR (qPCR) and expression of Epo and Epo receptor (Epor) proteins were measured by immunohistochemistry. The gene and protein expression profiles of kidney tissue in GABA-treated rats were evaluated by ribonucleic acid (RNA) sequencing and two-dimensional electrophoresis (2-DE), respectively. GABA significantly increased serum EPO levels and expression levels of Epo and Epor. GABA increased expression levels of hypoxia-inducible factor (Hif)-1 and Hif-2. Seven proteins with expression levels showing >2-fold change were identified by 2-DE followed by MALDI-TOF MS in GABA-treated rat kidney. The top KEGG pathway from the identified proteins was the tricarboxylic acid cycle, and nicotinamide adenine dinucleotide (NADH) dehydrogenase, succinate dehydrogenase, and isocitrate dehydrogenase were identified as key proteins. GABA treatment significantly increased ATP levels and NADH dehydrogenase activity in a dose-dependent manner. In conclusion, GABA shows a new physiological role in EPO production, and it can thus can contribute to the prevention of anemia when used alone or in combination with other anemia treating drugs.
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Affiliation(s)
- Keun-Tae Park
- Research and Development Center, Milae Bioresources Co., Ltd., Seoul 05836, Korea; (K.-T.P.); (J.-K.H.); (S.J.K.)
- Department of Integrated Biomedical and Life Sciences, College of Health Science, Korea University, Seoul 02841, Korea
| | - Jong-Kwon Han
- Research and Development Center, Milae Bioresources Co., Ltd., Seoul 05836, Korea; (K.-T.P.); (J.-K.H.); (S.J.K.)
| | - Seong Jin Kim
- Research and Development Center, Milae Bioresources Co., Ltd., Seoul 05836, Korea; (K.-T.P.); (J.-K.H.); (S.J.K.)
| | - Young-Hee Lim
- Department of Integrated Biomedical and Life Sciences, College of Health Science, Korea University, Seoul 02841, Korea
- Department of Public Health Science (BK21 PLUS Program), Graduate School, Korea University, Seoul 02841, Korea
- Department of Laboratory Medicine, Korea University Guro Hospital, Seoul 08308, Korea
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250
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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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