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Mei L, Sun H, Yan Y, Ji H, Su Q, Chang L, Wang L. mTOR Signaling: Roles in Hepatitis B Virus Infection and Hepatocellular Carcinoma. Int J Biol Sci 2024; 20:4178-4189. [PMID: 39247820 PMCID: PMC11379076 DOI: 10.7150/ijbs.95894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Accepted: 07/24/2024] [Indexed: 09/10/2024] Open
Abstract
Currently, chronic hepatitis B virus infection is still one of the most serious public health problems in the world. Though current strategies are effective in controlling infection and slowing down the disease process, it remains a big challenge to achieve a functional cure for chronic hepatitis B in a majority of patients due to the inability to clear the cccDNA pool. The mammalian target of rapamycin (mTOR) integrates nutrition, energy, growth factors, and other extracellular signals, participating in gene transcription, protein translation, ribosome synthesis, and other biological processes. Additionally, mTOR plays an extremely important role in cell growth, apoptosis, autophagy, and metabolism. More and more evidence show that HBV infection can activate the mTOR pathway, suggesting that HBV uses or hijacks the mTOR pathway to facilitate its own replication. Therefore, mTOR signaling pathway may be a key target for controlling HBV infection. However, the role of the central cytokine mTOR in the pathogenesis of HBV infection has not yet been systematically addressed. Notably, mTOR is commonly activated in hepatocellular carcinoma, which can progress from chronic hepatitis B. This review systematically summarizes the role of mTOR in the life cycle of HBV and its impact on the clinical progression of HBV infection.
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Affiliation(s)
- Ling Mei
- National Center for Clinical Laboratories, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/ National Center of Gerontology, Beijing, 100730, P.R. China
- Beijing Engineering Research Center of Laboratory Medicine, Beijing Hospital, Beijing, 100730, P.R. China
- National Center for Clinical Laboratories, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100730, P.R. China
| | - Huizhen Sun
- National Center for Clinical Laboratories, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/ National Center of Gerontology, Beijing, 100730, P.R. China
- Beijing Engineering Research Center of Laboratory Medicine, Beijing Hospital, Beijing, 100730, P.R. China
| | - Ying Yan
- National Center for Clinical Laboratories, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/ National Center of Gerontology, Beijing, 100730, P.R. China
- Beijing Engineering Research Center of Laboratory Medicine, Beijing Hospital, Beijing, 100730, P.R. China
| | - Huimin Ji
- National Center for Clinical Laboratories, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/ National Center of Gerontology, Beijing, 100730, P.R. China
- Beijing Engineering Research Center of Laboratory Medicine, Beijing Hospital, Beijing, 100730, P.R. China
| | - Qian Su
- National Center for Clinical Laboratories, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/ National Center of Gerontology, Beijing, 100730, P.R. China
- Beijing Engineering Research Center of Laboratory Medicine, Beijing Hospital, Beijing, 100730, P.R. China
- National Center for Clinical Laboratories, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100730, P.R. China
| | - Le Chang
- National Center for Clinical Laboratories, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/ National Center of Gerontology, Beijing, 100730, P.R. China
- Beijing Engineering Research Center of Laboratory Medicine, Beijing Hospital, Beijing, 100730, P.R. China
- National Center for Clinical Laboratories, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100730, P.R. China
| | - Lunan Wang
- National Center for Clinical Laboratories, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/ National Center of Gerontology, Beijing, 100730, P.R. China
- Beijing Engineering Research Center of Laboratory Medicine, Beijing Hospital, Beijing, 100730, P.R. China
- National Center for Clinical Laboratories, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100730, P.R. China
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Over Fifty Years of Life, Death, and Cannibalism: A Historical Recollection of Apoptosis and Autophagy. Int J Mol Sci 2021; 22:ijms222212466. [PMID: 34830349 PMCID: PMC8618802 DOI: 10.3390/ijms222212466] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 01/18/2023] Open
Abstract
Research in biomedical sciences has changed dramatically over the past fifty years. There is no doubt that the discovery of apoptosis and autophagy as two highly synchronized and regulated mechanisms in cellular homeostasis are among the most important discoveries in these decades. Along with the advancement in molecular biology, identifying the genetic players in apoptosis and autophagy has shed light on our understanding of their function in physiological and pathological conditions. In this review, we first describe the history of key discoveries in apoptosis with a molecular insight and continue with apoptosis pathways and their regulation. We touch upon the role of apoptosis in human health and its malfunction in several diseases. We discuss the path to the morphological and molecular discovery of autophagy. Moreover, we dive deep into the precise regulation of autophagy and recent findings from basic research to clinical applications of autophagy modulation in human health and illnesses and the available therapies for many diseases caused by impaired autophagy. We conclude with the exciting crosstalk between apoptosis and autophagy, from the early discoveries to recent findings.
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3
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Small organic molecules accelerate the expansion of regulatory T cells. Bioorg Chem 2021; 111:104908. [PMID: 33895604 DOI: 10.1016/j.bioorg.2021.104908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 04/04/2021] [Accepted: 04/07/2021] [Indexed: 11/21/2022]
Abstract
The regulatory T cells (Treg cells) expressing CD4 + CD25 + FOXP3 + markers are indispensable for the initiation of immune homeostasis and tolerance to self-antigens in both mice and humans. A decrease in regulatory T cells leads to various autoimmune pathologies. Herein, we report three low molecular weight, small organic molecules as a new series of Treg proliferators TRP-1-3. These small molecules were tested for their proliferative effect on regulatory T cells. It was found that TRP-1 (Oleracein E) strongly accelerates the Treg proliferation in vitro in a concentration-dependent manner. The effect was evident for all subsets of Treg cells tested, including naturally occurring, thymus-derived and peripherally-induced or adaptive Treg, indicating an effect independent of the maturation site. Importantly, increased Treg cells numbers by TRP-1 correlated with improved CD4 + CD25 + FOXP3 + expression in vitro, while propidium iodide-based staining showed low TRP-1-induced cytotoxicity. Molecular docking plus simulation studies of these TRP-1-3 with IL-2R, mTOR and TCR receptors suggest a TCR-based Treg cells activation mechanism. Because of its high Treg cells activities and low cellular cytotoxicity, TRP-1-3 may be useful in stimulating ex-vivo/in-vivo, Treg cell-specific responses for therapeutic applications.
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Chang Y, Lim G, Huh WK. Analysis of the TORC1 interactome reveals a spatially distinct function of TORC1 in mRNP complexes. J Cell Biol 2021; 220:211781. [PMID: 33566094 PMCID: PMC7879482 DOI: 10.1083/jcb.201912060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 11/15/2020] [Accepted: 01/06/2021] [Indexed: 11/22/2022] Open
Abstract
The target of rapamycin complex 1 (TORC1) is mainly localized to the vacuolar membrane and regulates eukaryotic cell growth in response to nutrient availability. To obtain deeper insights into the functional roles of TORC1, we performed a genome-wide analysis of the TORC1 interactome in yeast using the bimolecular fluorescence complementation (BiFC) assay. We found that while most of the BiFC signals are observed at the vacuolar membrane, a fraction of them are detected at cytoplasmic messenger ribonucleoprotein (mRNP) granules. Moreover, mRNA-binding proteins are enriched in the TORC1 interactome, suggesting a functional relationship between TORC1 and mRNA metabolism. We show that a portion of TORC1 is consistently associated with mRNP complexes and interacts with a specific subset of mRNAs. We also demonstrate that TORC1 directly targets a translational repressor Scd6 and that the activity of Scd6 is inhibited by TORC1-dependent phosphorylation. Collectively, our data suggest that TORC1 plays a novel role in posttranscriptional regulation by controlling the activity of Scd6.
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Affiliation(s)
- Yeonji Chang
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea.,Institute of Microbiology, Seoul National University, Seoul, Republic of Korea
| | - Gyubum Lim
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Won-Ki Huh
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea.,Institute of Microbiology, Seoul National University, Seoul, Republic of Korea
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5
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Wright SCE, Vasilevski N, Serra V, Rodon J, Eichhorn PJA. Mechanisms of Resistance to PI3K Inhibitors in Cancer: Adaptive Responses, Drug Tolerance and Cellular Plasticity. Cancers (Basel) 2021; 13:cancers13071538. [PMID: 33810522 PMCID: PMC8037590 DOI: 10.3390/cancers13071538] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/11/2021] [Accepted: 03/15/2021] [Indexed: 12/24/2022] Open
Abstract
The phosphatidylinositol-3-kinase (PI3K) pathway plays a central role in the regulation of several signalling cascades which regulate biological processes such as cellular growth, survival, proliferation, motility and angiogenesis. The hyperactivation of this pathway is linked to tumour progression and is one of the most common events in human cancers. Additionally, aberrant activation of the PI3K pathway has been demonstrated to limit the effectiveness of a number of anti-tumour agents paving the way for the development and implementation of PI3K inhibitors in the clinic. However, the overall effectiveness of these compounds has been greatly limited by inadequate target engagement due to reactivation of the pathway by compensatory mechanisms. Herein, we review the common adaptive responses that lead to reactivation of the PI3K pathway, therapy resistance and potential strategies to overcome these mechanisms of resistance. Furthermore, we highlight the potential role in changes in cellular plasticity and PI3K inhibitor resistance.
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Affiliation(s)
- Sarah Christine Elisabeth Wright
- Faculty of Health Sciences, Curtin Medical School, Curtin University, Bentley 6102, Australia;
- Curtin Health Innovation Research Institute and Faculty of Health Sciences, Curtin University, Bentley 6102, Australia
- Correspondence: (S.C.E.W.); (N.V.)
| | - Natali Vasilevski
- Faculty of Health Sciences, Curtin Medical School, Curtin University, Bentley 6102, Australia;
- Curtin Health Innovation Research Institute and Faculty of Health Sciences, Curtin University, Bentley 6102, Australia
- Correspondence: (S.C.E.W.); (N.V.)
| | - Violeta Serra
- Vall d’Hebron Institute of Oncology (VHIO), Vall d’Hebron University Hospital, 08035 Barcelona, Spain;
| | - Jordi Rodon
- MD Anderson Cancer Center, Investigational Cancer Therapeutics Department, Houston, TX 77030, USA;
| | - Pieter Johan Adam Eichhorn
- Faculty of Health Sciences, Curtin Medical School, Curtin University, Bentley 6102, Australia;
- Curtin Health Innovation Research Institute and Faculty of Health Sciences, Curtin University, Bentley 6102, Australia
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
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6
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Sciarretta S, Forte M, Frati G, Sadoshima J. The complex network of mTOR signaling in the heart. Cardiovasc Res 2021; 118:424-439. [PMID: 33512477 DOI: 10.1093/cvr/cvab033] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/13/2020] [Accepted: 01/26/2021] [Indexed: 12/13/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) integrates several intracellular and extracellular signals involved in the regulation of anabolic and catabolic processes. mTOR assembles into two macromolecular complexes, named mTORC1 and mTORC2, which have different regulators, substrates and functions. Studies of gain- and loss-of-function animal models of mTOR signaling revealed that mTORC1/2 elicit both adaptive and maladaptive functions in the cardiovascular system. Both mTORC1 and mTORC2 are indispensable for driving cardiac development and cardiac adaption to stress, such as pressure overload. However, persistent and deregulated mTORC1 activation in the heart is detrimental during stress and contributes to the development and progression of cardiac remodeling and genetic and metabolic cardiomyopathies. In this review, we discuss the latest findings regarding the role of mTOR in the cardiovascular system, both under basal conditions and during stress, such as pressure overload, ischemia and metabolic stress. Current data suggest that mTOR modulation may represent a potential therapeutic strategy for the treatment of cardiac diseases.
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Affiliation(s)
- Sebastiano Sciarretta
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy.,IRCCS Neuromed, Pozzilli (IS), Italy
| | | | - Giacomo Frati
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy.,IRCCS Neuromed, Pozzilli (IS), Italy
| | - Junichi Sadoshima
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, NJ, USA
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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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8
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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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9
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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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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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11
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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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12
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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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13
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Li J, Vázquez-García I, Persson K, González A, Yue JX, Barré B, Hall MN, Long A, Warringer J, Mustonen V, Liti G. Shared Molecular Targets Confer Resistance over Short and Long Evolutionary Timescales. Mol Biol Evol 2019; 36:691-708. [PMID: 30657986 DOI: 10.1093/molbev/msz006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Pre-existing and de novo genetic variants can both drive adaptation to environmental changes, but their relative contributions and interplay remain poorly understood. Here we investigated the evolutionary dynamics in drug-treated yeast populations with different levels of pre-existing variation by experimental evolution coupled with time-resolved sequencing and phenotyping. We found a doubling of pre-existing variation alone boosts the adaptation by 64.1% and 51.5% in hydroxyurea and rapamycin, respectively. The causative pre-existing and de novo variants were selected on shared targets: RNR4 in hydroxyurea and TOR1, TOR2 in rapamycin. Interestingly, the pre-existing and de novo TOR variants map to different functional domains and act via distinct mechanisms. The pre-existing TOR variants from two domesticated strains exhibited opposite rapamycin resistance effects, reflecting lineage-specific functional divergence. This study provides a dynamic view on how pre-existing and de novo variants interactively drive adaptation and deepens our understanding of clonally evolving populations.
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Affiliation(s)
- Jing Li
- Université Côte d'Azur, CNRS, Inserm, IRCAN, Nice, France
| | - Ignacio Vázquez-García
- Wellcome Trust Sanger Institute, Cambridge, United Kingdom.,Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom.,Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY.,Department of Statistics, Columbia University, New York, NY
| | - Karl Persson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | | | - Jia-Xing Yue
- Université Côte d'Azur, CNRS, Inserm, IRCAN, Nice, France
| | - Benjamin Barré
- Université Côte d'Azur, CNRS, Inserm, IRCAN, Nice, France
| | | | - Anthony Long
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA
| | - Jonas Warringer
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Ville Mustonen
- Organismal and Evolutionary Biology Research Programme, Department of Computer Science, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Gianni Liti
- Université Côte d'Azur, CNRS, Inserm, IRCAN, Nice, France
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14
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Livi GP. Halcyon days of TOR: Reflections on the multiple independent discovery of the yeast and mammalian TOR proteins. Gene 2019; 692:145-155. [DOI: 10.1016/j.gene.2018.12.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 12/13/2018] [Accepted: 12/20/2018] [Indexed: 12/24/2022]
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15
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Bakshi A, Moin M, Madhav MS, Kirti PB. Target of rapamycin, a master regulator of multiple signalling pathways and a potential candidate gene for crop improvement. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:190-205. [PMID: 30411830 DOI: 10.1111/plb.12935] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 11/05/2018] [Indexed: 06/08/2023]
Abstract
The target of rapamycin (TOR) protein regulates growth and development in photosynthetic and non-photosynthetic eukaryotes. Although the TOR regulatory networks are involved in nutrient and energy signalling, and transcriptional and translational control of multiple signalling pathways, the molecular mechanism of TOR regulation of plant abiotic stress responses is still unclear. The TOR-mediated transcriptional regulation of genes encoding ribosomal proteins (RP) is a necessity under stress conditions for balanced growth and productivity in plants. The activation of SnRKs (sucrose non-fermenting-related kinases) and the inactivation of TOR signalling in abiotic stresses is in line with the accumulation of ABA and transcriptional activation of stress responsive genes. Autophagy is induced under abiotic stress conditions, which results in degradation of proteins and the release of amino acids, which might possibly induce phosphorylation of TOR and, hence, its activation. TOR signalling also has a role in regulating ABA biosynthesis for transcriptional regulation of stress-related genes. The switch between activation and inactivation of TOR by its phosphorylation and de-phosphorylation maintains balanced growth in response to stresses. In the present review, we discuss the important signalling pathways that are regulated by TOR and try to assess the relationship between TOR signalling and tolerance to abiotic stresses in plants. The review also discusses possible cross-talk between TOR and RP genes in response to abiotic stresses.
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Affiliation(s)
- A Bakshi
- Department of Plant Sciences, University of Hyderabad, Hyderabad, India
| | - M Moin
- Department of Biotechnology, Indian Institute of Rice Research, Hyderabad, India
| | - M S Madhav
- Department of Biotechnology, Indian Institute of Rice Research, Hyderabad, India
| | - P B Kirti
- Department of Plant Sciences, University of Hyderabad, Hyderabad, India
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16
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Palmisano NJ, Meléndez A. Autophagy in C. elegans development. Dev Biol 2019; 447:103-125. [PMID: 29709599 PMCID: PMC6204124 DOI: 10.1016/j.ydbio.2018.04.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 03/19/2018] [Accepted: 04/12/2018] [Indexed: 12/11/2022]
Abstract
Autophagy involves the sequestration of cytoplasmic contents in a double-membrane structure referred to as the autophagosome and the degradation of its contents upon delivery to lysosomes. Autophagy activity has a role in multiple biological processes during the development of the nematode Caenorhabditis elegans. Basal levels of autophagy are required to remove aggregate prone proteins, paternal mitochondria, and spermatid-specific membranous organelles. During larval development, autophagy is required for the remodeling that occurs during dauer development, and autophagy can selectively degrade components of the miRNA-induced silencing complex, and modulate miRNA-mediated silencing. Basal levels of autophagy are important in synapse formation and in the germ line, to promote the proliferation of proliferating stem cells. Autophagy activity is also required for the efficient removal of apoptotic cell corpses by promoting phagosome maturation. Finally, autophagy is also involved in lipid homeostasis and in the aging process. In this review, we first describe the molecular complexes involved in the process of autophagy, its regulation, and mechanisms for cargo recognition. In the second section, we discuss the developmental contexts where autophagy has been shown to be important. Studies in C. elegans provide valuable insights into the physiological relevance of this process during metazoan development.
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Affiliation(s)
- Nicholas J Palmisano
- Biology Department, Queens College, CUNY, Flushing, NY, USA; Biology Ph.D. Program, The Graduate Center of the City University of New York, NK, USA
| | - Alicia Meléndez
- Biology Department, Queens College, CUNY, Flushing, NY, USA; Biology Ph.D. Program, The Graduate Center of the City University of New York, NK, USA; Biochemistry Ph.D. Program, The Graduate Center of the City University of New York, NY, USA.
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17
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Kim J, Guan KL. mTOR as a central hub of nutrient signalling and cell growth. Nat Cell Biol 2019; 21:63-71. [PMID: 30602761 DOI: 10.1038/s41556-018-0205-1] [Citation(s) in RCA: 660] [Impact Index Per Article: 132.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 08/23/2018] [Indexed: 12/19/2022]
Abstract
The highly conserved protein kinase mechanistic target of rapamycin (mTOR; originally known as mammalian target of rapamycin) is a central cell growth regulator connecting cellular metabolism and growth with a wide range of environmental inputs as part of mTOR complex 1 (mTORC1) and mTORC2. In this Review, we introduce the landmark discoveries in the mTOR field, starting from the isolation of rapamycin to the molecular characterizations of key components of the mTORC signalling network with an emphasis on amino acid sensing, and discuss the perspectives of mTORC inhibitors in therapeutic applications.
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Affiliation(s)
- Joungmok Kim
- Department of Oral Biochemistry and Molecular Biology, School of Dentistry, Kyung Hee University, Seoul, Korea.
| | - Kun-Liang Guan
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA.
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18
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Abstract
Mammalian target of rapamycin (mTOR) is a conserved serine/threonine kinase of the phosphatidylinositol kinase-related kinase family that regulates cell growth, metabolism, and autophagy. Extensive research has linked mTOR to several human diseases including cancer, neurodegenerative disorders, and aging. In this review, recent publications regarding the mechanisms underlying the role of mTOR in female reproduction under physiological and pathological conditions are summarized. Moreover, we assess whether strategies to improve or suppress mTOR expression could have therapeutic potential for reproductive diseases like premature ovarian failure, polycystic ovarian syndrome, and endometriosis.
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19
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Caron A, Briscoe DM, Richard D, Laplante M. DEPTOR at the Nexus of Cancer, Metabolism, and Immunity. Physiol Rev 2018; 98:1765-1803. [PMID: 29897294 DOI: 10.1152/physrev.00064.2017] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
DEP domain-containing mechanistic target of rapamycin (mTOR)-interacting protein (DEPTOR) is an important modulator of mTOR, a kinase at the center of two important protein complexes named mTORC1 and mTORC2. These highly studied complexes play essential roles in regulating growth, metabolism, and immunity in response to mitogens, nutrients, and cytokines. Defects in mTOR signaling have been associated with the development of many diseases, including cancer and diabetes, and approaches aiming at modulating mTOR activity are envisioned as an attractive strategy to improve human health. DEPTOR interaction with mTOR represses its kinase activity and rewires the mTOR signaling pathway. Over the last years, several studies have revealed key roles for DEPTOR in numerous biological and pathological processes. Here, we provide the current state of the knowledge regarding the cellular and physiological functions of DEPTOR by focusing on its impact on the mTOR pathway and its role in promoting health and disease.
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Affiliation(s)
- Alexandre Caron
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center , Dallas, Texas ; Transplant Research Program, Boston Children's Hospital , Boston, Massachusetts ; Department of Pediatrics, Harvard Medical School , Boston, Massachusetts ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval , Québec , Canada ; and Centre de Recherche sur le Cancer de l'Université Laval, Université Laval , Québec , Canada
| | - David M Briscoe
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center , Dallas, Texas ; Transplant Research Program, Boston Children's Hospital , Boston, Massachusetts ; Department of Pediatrics, Harvard Medical School , Boston, Massachusetts ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval , Québec , Canada ; and Centre de Recherche sur le Cancer de l'Université Laval, Université Laval , Québec , Canada
| | - Denis Richard
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center , Dallas, Texas ; Transplant Research Program, Boston Children's Hospital , Boston, Massachusetts ; Department of Pediatrics, Harvard Medical School , Boston, Massachusetts ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval , Québec , Canada ; and Centre de Recherche sur le Cancer de l'Université Laval, Université Laval , Québec , Canada
| | - Mathieu Laplante
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center , Dallas, Texas ; Transplant Research Program, Boston Children's Hospital , Boston, Massachusetts ; Department of Pediatrics, Harvard Medical School , Boston, Massachusetts ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (CRIUCPQ), Faculté de Médecine, Université Laval , Québec , Canada ; and Centre de Recherche sur le Cancer de l'Université Laval, Université Laval , Québec , Canada
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20
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Pharmacokinetics, Tissue Distribution and Excretion of a Novel Diuretic (PU-48) in Rats. Pharmaceutics 2018; 10:pharmaceutics10030124. [PMID: 30096833 PMCID: PMC6160999 DOI: 10.3390/pharmaceutics10030124] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 07/21/2018] [Accepted: 07/27/2018] [Indexed: 01/02/2023] Open
Abstract
Methyl 3-amino-6-methoxythieno [2,3-b] quinoline-2-carboxylate (PU-48) is a novel diuretic urea transporter inhibitor. The aim of this study is to investigate the profile of plasma pharmacokinetics, tissue distribution, and excretion by oral dosing of PU-48 in rats. Concentrations of PU-48 within biological samples are determined using a validated high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. After oral administration of PU-48 (3, 6, and 12 mg/kg, respectively) in self-nanomicroemulsifying drug delivery system (SNEDDS) formulation, the peak plasma concentrations (Cmax), and the area under the curve (AUC0⁻∞) were increased by the dose-dependent and linear manner, but the marked different of plasma half-life (t1/2) were not observed. This suggests that the pharmacokinetic profile of PU-48 prototype was first-order elimination kinetic characteristics within the oral three doses range in rat plasma. Moreover, the prototype of PU-48 was rapidly and extensively distributed into thirteen tissues, especially higher concentrations were detected in stomach, intestine, liver, kidney, and bladder. The total accumulative excretion of PU-48 in the urine, feces, and bile was less than 2%. This research is the first report on disposition via oral administration of PU-48 in rats, and it provides important information for further development of PU-48 as a diuretic drug candidate.
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21
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Hill A, Niles B, Cuyegkeng A, Powers T. Redesigning TOR Kinase to Explore the Structural Basis for TORC1 and TORC2 Assembly. Biomolecules 2018; 8:biom8020036. [PMID: 29865216 PMCID: PMC6023025 DOI: 10.3390/biom8020036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 05/25/2018] [Accepted: 05/25/2018] [Indexed: 12/21/2022] Open
Abstract
TOR is a serine/threonine protein kinase that assembles into distinct TOR Complexes 1 and 2 (TORC1 or TORC2) to regulate cell growth. In mammalian cells, a single mTOR incorporates stably into mTORC1 and mTORC2. By contrast, in Saccharomyces cerevisiae, two highly similar Tor1 and Tor2 proteins exist, where Tor1 assembles exclusively into TORC1 and Tor2 assembles preferentially into TORC2. To gain insight into TOR complex assembly, we used this bifurcation in yeast to identify structural elements within Tor1 and Tor2 that govern their complex specificity. We have identified a concise region of ~500 amino acids within the N-terminus of Tor2, which we term the Major Assembly Specificity (MAS) domain, that is sufficient to confer significant TORC2 activity when placed into an otherwise Tor1 protein. Consistently, introduction of the corresponding MAS domain from Tor1 into an otherwise Tor2 is sufficient to confer stable association with TORC1-specific components. Remarkably, much like mTOR, this latter chimera also retains stable interactions with TORC2 components, indicating that determinants throughout Tor1/Tor2 contribute to complex specificity. Our findings are in excellent agreement with recent ultrastructural studies of TORC1 and TORC2, where the MAS domain is involved in quaternary interactions important for complex formation and/or stability.
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Affiliation(s)
- Andrew Hill
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California Davis, Davis, CA 95616, USA.
| | - Brad Niles
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California Davis, Davis, CA 95616, USA.
| | - Andrew Cuyegkeng
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California Davis, Davis, CA 95616, USA.
| | - Ted Powers
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California Davis, Davis, CA 95616, USA.
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22
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Tee AR. The Target of Rapamycin and Mechanisms of Cell Growth. Int J Mol Sci 2018; 19:ijms19030880. [PMID: 29547541 PMCID: PMC5877741 DOI: 10.3390/ijms19030880] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 03/12/2018] [Accepted: 03/13/2018] [Indexed: 01/09/2023] Open
Abstract
Mammalian target of rapamycin (mTOR, now referred to as mechanistic target of rapamycin) is considered as the master regulator of cell growth. A definition of cell growth is a build-up of cellular mass through the biosynthesis of macromolecules. mTOR regulation of cell growth and cell size is complex, involving tight regulation of both anabolic and catabolic processes. Upon a growth signal input, mTOR enhances a range of anabolic processes that coordinate the biosynthesis of macromolecules to build cellular biomass, while restricting catabolic processes such as autophagy. mTOR is highly dependent on the supply of nutrients and energy to promote cell growth, where the network of signalling pathways that influence mTOR activity ensures that energy and nutrient homeostasis are retained within the cell as they grow. As well as maintaining cell size, mTOR is fundamental in the regulation of organismal growth. This review examines the complexities of how mTOR complex 1 (mTORC1) enhances the cell’s capacity to synthesis de novo proteins required for cell growth. It also describes the discovery of mTORC1, the complexities of cell growth signalling involving nutrients and energy supply, as well as the multifaceted regulation of mTORC1 to orchestrate ribosomal biogenesis and protein translation.
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Affiliation(s)
- Andrew R Tee
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
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23
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mTOR signaling in skeletal development and disease. Bone Res 2018; 6:1. [PMID: 29423330 PMCID: PMC5802487 DOI: 10.1038/s41413-017-0004-5] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/13/2017] [Accepted: 10/23/2017] [Indexed: 02/07/2023] Open
Abstract
The mammalian/mechanistic target of rapamycin (mTOR) is a serine/threonine protein kinase that integrates inputs from nutrients and growth factors to control many fundamental cellular processes through two distinct protein complexes mTORC1 and mTORC2. Recent mouse genetic studies have established that mTOR pathways play important roles in regulating multiple aspects of skeletal development and homeostasis. In addition, mTORC1 has emerged as a common effector mediating the bone anabolic effect of Igf1, Wnt and Bmp. Dysregulation of mTORC1 could contribute to various skeletal diseases including osteoarthritis and osteoporosis. Here we review the current understanding of mTOR signaling in skeletal development and bone homeostasis, as well as in the maintenance of articular cartilage. We speculate that targeting mTOR signaling may be a valuable approach for treating skeletal diseases. Drugs directed at a key cellular signaling pathway could prove useful for treating skeletal diseases. Jianquan Chen from Soochow University in Suzhou, China, and Fanxin Long from Washington University School of Medicine in St. Louis, Missouri, USA, provide an overview of how proteins involved in the mechanistic target of rapamycin (mTOR) signaling pathway sense and integrate a range of environmental cues to regulate bone and cartilage development. In particular, they review the differing roles of the two distinct mTOR-containing protein complexes, mTORC1 and mTORC2. Both seem to mediate bone formation and resorption but in different ways, with implications for how best to treat osteoarthritis, osteoporosis, and other degenerative skeletal diseases. The authors suggest that more specific mTOR inhibitors with minimal side effects are needed to help stimulate bone growth in these diseases.
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24
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Takeda E, Jin N, Itakura E, Kira S, Kamada Y, Weisman LS, Noda T, Matsuura A. Vacuole-mediated selective regulation of TORC1-Sch9 signaling following oxidative stress. Mol Biol Cell 2017; 29:510-522. [PMID: 29237820 PMCID: PMC6014174 DOI: 10.1091/mbc.e17-09-0553] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 12/06/2017] [Accepted: 12/08/2017] [Indexed: 12/22/2022] Open
Abstract
TORC1 modulates proteosynthesis, nitrogen metabolism, stress responses, and autophagy. Here it is shown that the Sch9 branch of TORC1 signaling depends specifically on vacuolar membranes and that this specificity allows the cells to regulate selectively the outputs of divergent downstream pathways in response to oxidative stress. Target of rapamycin complex 1 (TORC1) is a central cellular signaling coordinator that allows eukaryotic cells to adapt to the environment. In the budding yeast, Saccharomyces cerevisiae, TORC1 senses nitrogen and various stressors and modulates proteosynthesis, nitrogen uptake and metabolism, stress responses, and autophagy. There is some indication that TORC1 may regulate these downstream pathways individually. However, the potential mechanisms for such differential regulation are unknown. Here we show that the serine/threonine protein kinase Sch9 branch of TORC1 signaling depends specifically on the integrity of the vacuolar membrane, and this dependency originates in changes in Sch9 localization reflected by phosphatidylinositol 3,5-bisphosphate. Moreover, oxidative stress induces the delocalization of Sch9 from vacuoles, contributing to the persistent inhibition of the Sch9 branch after stress. Thus, our results establish that regulation of the vacuolar localization of Sch9 serves as a selective switch for the Sch9 branch in divergent TORC1 signaling. We propose that the Sch9 branch integrates the intrinsic activity of TORC1 kinase and vacuolar status, which is monitored by the phospholipids of the vacuolar membrane, into the regulation of macromolecular synthesis.
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Affiliation(s)
- Eigo Takeda
- Department of Nanobiology, Graduate School of Advanced Integration Science
| | | | - Eisuke Itakura
- Department of Nanobiology, Graduate School of Advanced Integration Science.,Molecular Chirality Research Center, Chiba University, Inage-ku, Chiba, 263-8522, Japan
| | - Shintaro Kira
- Department of Biology, Graduate School of Science, Chiba University, Inage-ku, Chiba, 263-8522, Japan
| | - Yoshiaki Kamada
- Laboratory of Biological Diversity, National Institute for Basic Biology, Okazaki 444-8585, Japan.,Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
| | - Lois S Weisman
- Life Sciences Institute and.,Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Takeshi Noda
- Center for Frontier Oral Science, Graduate School of Dentistry, and.,Graduate School of Frontier BioSciences, Osaka University, Osaka 565-0871, Japan
| | - Akira Matsuura
- Department of Nanobiology, Graduate School of Advanced Integration Science .,Life Sciences Institute and.,Molecular Chirality Research Center, Chiba University, Inage-ku, Chiba, 263-8522, Japan
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25
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Antikainen H, Driscoll M, Haspel G, Dobrowolski R. TOR-mediated regulation of metabolism in aging. Aging Cell 2017; 16:1219-1233. [PMID: 28971552 PMCID: PMC5676073 DOI: 10.1111/acel.12689] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2017] [Indexed: 01/06/2023] Open
Abstract
Cellular metabolism is regulated by the mTOR kinase, a key component of the molecular nutrient sensor pathway that plays a central role in cellular survival and aging. The mTOR pathway promotes protein and lipid synthesis and inhibits autophagy, a process known for its contribution to longevity in several model organisms. The nutrient‐sensing pathway is regulated at the lysosomal membrane by a number of proteins for which deficiency triggers widespread aging phenotypes in tested animal models. In response to environmental cues, this recently discovered lysosomal nutrient‐sensing complex regulates autophagy transcriptionally through conserved factors, such as the transcription factors TFEB and FOXO, associated with lifespan extension. This key metabolic pathway strongly depends on nucleocytoplasmic compartmentalization, a cellular phenomenon gradually lost during aging. In this review, we discuss the current progress in understanding the contribution of mTOR‐regulating factors to autophagy and longevity. Furthermore, we review research on the regulation of metabolism conducted in multiple aging models, including Caenorhabditis elegans, Drosophila and mouse, and human iPSCs. We suggest that conserved molecular pathways have the strongest potential for the development of new avenues for treatment of age‐related diseases.
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Affiliation(s)
- Henri Antikainen
- Federated Department of Biological Sciences New Jersey Institute of Technology Rutgers University Newark NJ 07102 USA
| | - Monica Driscoll
- Department of Molecular Biology and Biochemistry Rutgers University Piscataway NJ 08854 USA
| | - Gal Haspel
- Federated Department of Biological Sciences New Jersey Institute of Technology Rutgers University Newark NJ 07102 USA
| | - Radek Dobrowolski
- Federated Department of Biological Sciences New Jersey Institute of Technology Rutgers University Newark NJ 07102 USA
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26
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Karuppasamy M, Kusmider B, Oliveira TM, Gaubitz C, Prouteau M, Loewith R, Schaffitzel C. Cryo-EM structure of Saccharomyces cerevisiae target of rapamycin complex 2. Nat Commun 2017; 8:1729. [PMID: 29170376 PMCID: PMC5700991 DOI: 10.1038/s41467-017-01862-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 10/18/2017] [Indexed: 12/11/2022] Open
Abstract
The target of rapamycin (TOR) kinase assembles into two distinct multiprotein complexes, conserved across eukaryote evolution. In contrast to TOR complex 1 (TORC1), TORC2 kinase activity is not inhibited by the macrolide rapamycin. Here, we present the structure of Saccharomyces cerevisiae TORC2 determined by electron cryo-microscopy. TORC2 contains six subunits assembling into a 1.4 MDa rhombohedron. Tor2 and Lst8 form the common core of both TOR complexes. Avo3/Rictor is unique to TORC2, but interacts with the same HEAT repeats of Tor2 that are engaged by Kog1/Raptor in mammalian TORC1, explaining the mutual exclusivity of these two proteins. Density, which we conclude is Avo3, occludes the FKBP12-rapamycin-binding site of Tor2’s FRB domain rendering TORC2 rapamycin insensitive and recessing the kinase active site. Although mobile, Avo1/hSin1 further restricts access to the active site as its conserved-region-in-the-middle (CRIM) domain is positioned along an edge of the TORC2 active-site-cleft, consistent with a role for CRIM in substrate recruitment. Target of rapamycin (TOR) kinase operates within two distinct multiprotein complexes named TORC1 and TORC2. Here the authors report a cryo-EM structure of TORC2, establish its subunit organization, providing a rationale for TORC2’s rapamycin insensitivity and the mutually exclusive inclusion of Avo3/Rictor or Raptor within their respective TOR complex.
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Affiliation(s)
- Manikandan Karuppasamy
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042, Grenoble, France
| | - Beata Kusmider
- Department of Molecular Biology, Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211, Geneva, Switzerland
| | - Taiana M Oliveira
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042, Grenoble, France
| | - Christl Gaubitz
- Department of Molecular Biology, Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211, Geneva, Switzerland
| | - Manoel Prouteau
- Department of Molecular Biology, Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211, Geneva, Switzerland
| | - Robbie Loewith
- Department of Molecular Biology, Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211, Geneva, Switzerland. .,Swiss National Centre for Competence in Research (NCCR) in Chemical Biology, University of Geneva, 30 Quai Ernest-Ansermet, Bristol, CH1211 Geneva, Switzerland.
| | - Christiane Schaffitzel
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042, Grenoble, France. .,School of Biochemistry, University of Bristol, University Walk, Bristol, BS8 1TD, UK.
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27
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Affiliation(s)
- Brendan D Manning
- From the Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston
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28
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Vignali PDA, Barbi J, Pan F. Metabolic Regulation of T Cell Immunity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1011:87-130. [DOI: 10.1007/978-94-024-1170-6_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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29
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Abstract
All organisms can respond to the availability of nutrients by regulating their metabolism, growth, and cell division. Central to the regulation of growth in response to nutrient availability is the target of rapamycin (TOR) signaling that is composed of two structurally distinct complexes: TOR complex 1 (TORC1) and TOR complex 2 (TORC2). The TOR genes were first identified in yeast as target of rapamycin, a natural product of a soil bacterium, which proved beneficial as an immunosuppressive and anticancer drug and is currently being tested for a handful of other pathological conditions including diabetes, neurodegeneration, and age-related diseases. Studies of the TOR pathway unraveled a complex growth-regulating network. TOR regulates nutrient uptake, transcription, protein synthesis and degradation, as well as metabolic pathways, in a coordinated manner that ensures that cells grow or cease growth in response to nutrient availability. The identification of specific signals and mechanisms that stimulate TOR signaling is an active and exciting field of research that has already identified nitrogen and amino acids as key regulators of TORC1 activity. The signals, as well as the cellular functions of TORC2, are far less well understood. Additional open questions in the field concern the relationships between TORC1 and TORC2, as well as the links with other nutrient-responsive pathways. Here I review the main features of TORC1 and TORC2, with a particular focus on yeasts as model organisms.
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The molecular basis of mTORC1-regulated translation. Biochem Soc Trans 2017; 45:213-221. [PMID: 28202675 DOI: 10.1042/bst20160072] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/05/2016] [Accepted: 12/08/2016] [Indexed: 12/26/2022]
Abstract
The mammalian target of rapamycin (mTOR) signaling pathway is a master regulator of cell growth throughout eukaryotes. The pathway senses nutrient and other growth signals, and then orchestrates the complex systems of anabolic and catabolic metabolism that underpin the growth process. A central target of mTOR signaling is the translation machinery. mTOR uses a multitude of translation factors to drive the bulk production of protein that growth requires, but also to direct a post-transcriptional program of growth-specific gene expression. This review will discuss current understanding of how mTOR controls these mechanisms and their functions in growth control.
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31
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Abstract
Mechanistic target of rapamycin controls cell growth, metabolism, and aging in response to nutrients, cellular energy stage, and growth factors. In cancers including breast cancer, mechanistic target of rapamycin is frequently upregulated. Blocking mechanistic target of rapamycin with rapamycin, first-generation and second-generation mechanistic target of rapamycin inhibitors, called rapalogs, have shown potent reduction of breast cancer tumor growth in preclinical models and clinical trials. In this review, we summarize the fundamental role of the mechanistic target of rapamycin pathway in driving breast tumors. Moreover, we also review key molecules involved with aberrant mechanistic target of rapamycin pathway activation in breast cancer and current efforts to target these components for therapeutic gain. Further development of predictive biomarkers will be useful in the selection of patients who will benefit from inhibition of the mechanistic target of rapamycin pathway.
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Affiliation(s)
- Jia Liu
- Maternal and Child Health Hospital of Qinhuangdao, Qinhuangdao, P.R. China
| | - Hui-Qing Li
- Maternal and Child Health Hospital of Qinhuangdao, Qinhuangdao, P.R. China
| | - Fu-Xia Zhou
- Maternal and Child Health Hospital of Qinhuangdao, Qinhuangdao, P.R. China
| | - Jie-Wen Yu
- Maternal and Child Health Hospital of Qinhuangdao, Qinhuangdao, P.R. China
| | - Ling Sun
- Maternal and Child Health Hospital of Qinhuangdao, Qinhuangdao, P.R. China
| | - Zhong-Hou Han
- Maternal and Child Health Hospital of Qinhuangdao, Qinhuangdao, P.R. China
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32
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The Architecture of the Rag GTPase Signaling Network. Biomolecules 2017; 7:biom7030048. [PMID: 28788436 PMCID: PMC5618229 DOI: 10.3390/biom7030048] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 06/22/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022] Open
Abstract
The evolutionarily conserved target of rapamycin complex 1 (TORC1) couples an array of intra- and extracellular stimuli to cell growth, proliferation and metabolism, and its deregulation is associated with various human pathologies such as immunodeficiency, epilepsy, and cancer. Among the diverse stimuli impinging on TORC1, amino acids represent essential input signals, but how they control TORC1 has long remained a mystery. The recent discovery of the Rag GTPases, which assemble as heterodimeric complexes on vacuolar/lysosomal membranes, as central elements of an amino acid signaling network upstream of TORC1 in yeast, flies, and mammalian cells represented a breakthrough in this field. Here, we review the architecture of the Rag GTPase signaling network with a special focus on structural aspects of the Rag GTPases and their regulators in yeast and highlight both the evolutionary conservation and divergence of the mechanisms that control Rag GTPases.
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Saxton RA, Sabatini DM. mTOR Signaling in Growth, Metabolism, and Disease. Cell 2017; 168:960-976. [PMID: 28283069 DOI: 10.1016/j.cell.2017.02.004] [Citation(s) in RCA: 3968] [Impact Index Per Article: 566.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Revised: 01/22/2017] [Accepted: 02/01/2017] [Indexed: 12/13/2022]
Abstract
The mechanistic target of rapamycin (mTOR) coordinates eukaryotic cell growth and metabolism with environmental inputs, including nutrients and growth factors. Extensive research over the past two decades has established a central role for mTOR in regulating many fundamental cell processes, from protein synthesis to autophagy, and deregulated mTOR signaling is implicated in the progression of cancer and diabetes, as well as the aging process. Here, we review recent advances in our understanding of mTOR function, regulation, and importance in mammalian physiology. We also highlight how the mTOR signaling network contributes to human disease and discuss the current and future prospects for therapeutically targeting mTOR in the clinic.
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Affiliation(s)
- Robert A Saxton
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 415 Main Street, Cambridge, MA 02142, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 415 Main Street, Cambridge, MA 02142, USA.
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34
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Control of B lymphocyte development and functions by the mTOR signaling pathways. Cytokine Growth Factor Rev 2017; 35:47-62. [PMID: 28583723 DOI: 10.1016/j.cytogfr.2017.04.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 04/07/2017] [Indexed: 12/21/2022]
Abstract
Mechanistic target of rapamycin (mTOR) is a serine/threonine kinase originally discovered as the molecular target of the immunosuppressant rapamycin. mTOR forms two compositionally and functionally distinct complexes, mTORC1 and mTORC2, which are crucial for coordinating nutrient, energy, oxygen, and growth factor availability with cellular growth, proliferation, and survival. Recent studies have identified critical, non-redundant roles for mTORC1 and mTORC2 in controlling B cell development, differentiation, and functions, and have highlighted emerging roles of the Folliculin-Fnip protein complex in regulating mTOR and B cell development. In this review, we summarize the basic mechanisms of mTOR signaling; describe what is known about the roles of mTORC1, mTORC2, and the Folliculin/Fnip1 pathway in B cell development and functions; and briefly outline current clinical approaches for targeting mTOR in B cell neoplasms. We conclude by highlighting a few salient questions and future perspectives regarding mTOR in B lineage cells.
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Abstract
The mechanistic target of rapamycin (mTOR) signaling pathway regulates many metabolic and physiological processes in different organs or tissues. Dysregulation of mTOR signaling has been implicated in many human diseases including obesity, diabetes, cancer, fatty liver diseases, and neuronal disorders. Here we review recent progress in understanding how mTORC1 (mTOR complex 1) signaling regulates lipid metabolism in the liver.
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36
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Jesus TT, Oliveira PF, Sousa M, Cheng CY, Alves MG. Mammalian target of rapamycin (mTOR): a central regulator of male fertility? Crit Rev Biochem Mol Biol 2017; 52:235-253. [PMID: 28124577 DOI: 10.1080/10409238.2017.1279120] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mammalian target of rapamycin (mTOR) is a central regulator of cellular metabolic phenotype and is involved in virtually all aspects of cellular function. It integrates not only nutrient and energy-sensing pathways but also actin cytoskeleton organization, in response to environmental cues including growth factors and cellular energy levels. These events are pivotal for spermatogenesis and determine the reproductive potential of males. Yet, the molecular mechanisms by which mTOR signaling acts in male reproductive system remain a matter of debate. Here, we review the current knowledge on physiological and molecular events mediated by mTOR in testis and testicular cells. In recent years, mTOR inhibition has been explored as a prime strategy to develop novel therapeutic approaches to treat cancer, cardiovascular disease, autoimmunity, and metabolic disorders. However, the physiological consequences of mTOR dysregulation and inhibition to male reproductive potential are still not fully understood. Compelling evidence suggests that mTOR is an arising regulator of male fertility and better understanding of this atypical protein kinase coordinated action in testis will provide insightful information concerning its biological significance in other tissues/organs. We also discuss why a new generation of mTOR inhibitors aiming to be used in clinical practice may also need to include an integrative view on the effects in male reproductive system.
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Affiliation(s)
- Tito T Jesus
- a Laboratory of Cell Biology, Department of Microscopy and Unit for Multidisciplinary Research in Biomedicine (UMIB), Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto , Porto , Portugal.,b CICS-UBI - Health Sciences Research Centre, University of Beira Interior , Covilhã , Portugal
| | - Pedro F Oliveira
- a Laboratory of Cell Biology, Department of Microscopy and Unit for Multidisciplinary Research in Biomedicine (UMIB), Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto , Porto , Portugal.,c i3S - Instituto de Investigação e Inovação em Saúde, University of Porto , Porto , Portugal
| | - Mário Sousa
- a Laboratory of Cell Biology, Department of Microscopy and Unit for Multidisciplinary Research in Biomedicine (UMIB), Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto , Porto , Portugal.,d Centre for Reproductive Genetics Prof. Alberto Barros , Porto , Portugal
| | - C Yan Cheng
- e The Mary M. Wohlford Laboratory for Male Contraceptive Research , Center for Biomedical Research, Population Council , New York , NY , USA
| | - Marco G Alves
- a Laboratory of Cell Biology, Department of Microscopy and Unit for Multidisciplinary Research in Biomedicine (UMIB), Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto , Porto , Portugal.,b CICS-UBI - Health Sciences Research Centre, University of Beira Interior , Covilhã , Portugal
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37
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Roach ES. Applying the Lessons of Tuberous Sclerosis: The 2015 Hower Award Lecture. Pediatr Neurol 2016; 63:6-22. [PMID: 27543366 DOI: 10.1016/j.pediatrneurol.2016.07.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/07/2016] [Indexed: 12/15/2022]
Abstract
Tuberous sclerosis complex is a dominantly inherited disorder that variably affects the brain, skin, kidneys, heart, and other organs. Its neurological manifestations include epilepsy, autism, cognitive and behavioral dysfunction, and giant cell tumors. A mutation of either TSC1 or TSC2 can cause tuberous sclerosis complex. Their two gene products, hamartin and tuberin, form a physical complex which normally inhibits protein synthesis mediated through the mechanistic target of rapamycin, so a TSC1 or TSC2 mutation results in overactivation of the mechanistic target of rapamycin cascade. In addition to their tumor suppressor roles, TSC1 and TSC2 help to regulate cell size, neuronal migration, axon formation, and synaptic plasticity. Clinical trials of two different the mechanistic target of rapamycin inhibitors have demonstrated substantial improvement of tuberous sclerosis complex-related tumors, and a recent trial also showed a benefit from the mechanistic target of rapamycin inhibitor everolimus in the treatment of refractory epilepsy due to tuberous sclerosis complex. Effective mechanism-based therapy is now available for some manifestations of tuberous sclerosis complex.
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Affiliation(s)
- E Steve Roach
- Division of Child Neurology, Ohio State University College of Medicine, Nationwide Children's Hospital, Columbus, Ohio.
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38
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Abstract
Protein phosphatase 2A (PP2A) plays a critical multi-faceted role in the regulation of the cell cycle. It is known to dephosphorylate over 300 substrates involved in the cell cycle, regulating almost all major pathways and cell cycle checkpoints. PP2A is involved in such diverse processes by the formation of structurally distinct families of holoenzymes, which are regulated spatially and temporally by specific regulators. Here, we review the involvement of PP2A in the regulation of three cell signaling pathways: wnt, mTOR and MAP kinase, as well as the G1→S transition, DNA synthesis and mitotic initiation. These processes are all crucial for proper cell survival and proliferation and are often deregulated in cancer and other diseases.
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Affiliation(s)
- Nathan Wlodarchak
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
| | - Yongna Xing
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
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39
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mTORC signaling in hematopoiesis. Int J Hematol 2016; 103:510-8. [PMID: 26791377 DOI: 10.1007/s12185-016-1944-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 01/07/2016] [Accepted: 01/07/2016] [Indexed: 01/08/2023]
Abstract
mTOR is a serine/threonine (Ser/Thr) protein kinase that responds to multiple signals, including growth factors, amino acids, energy status, stress, and oxygen, regulates cell survival, cell growth, the cell cycle, and cell metabolism, and maintains homeostasis [1]. Increased or decreased mTORC1 activity can alter HSC function and cause hematological disorders [2, 3]. Therefore, a comprehensive knowledge of mTOR is critical to understanding how HSCs function and maintain homeostasis in the hematopoietic system. In this review, we summarize recent advances in the understanding of the mTOR signaling pathway and its roles in hematopoiesis and leukemia. We also discuss pharmacological approaches to manipulate mTOR activity.
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Deng K, Yu L, Zheng X, Zhang K, Wang W, Dong P, Zhang J, Ren M. Target of Rapamycin Is a Key Player for Auxin Signaling Transduction in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2016; 7:291. [PMID: 27014314 PMCID: PMC4786968 DOI: 10.3389/fpls.2016.00291] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 02/23/2016] [Indexed: 05/08/2023]
Abstract
Target of rapamycin (TOR), a master sensor for growth factors and nutrition availability in eukaryotic species, is a specific target protein of rapamycin. Rapamycin inhibits TOR kinase activity viaFK506 binding protein 12 kDa (FKBP12) in all examined heterotrophic eukaryotic organisms. In Arabidopsis, several independent studies have shown that AtFKBP12 is non-functional under aerobic condition, but one study suggests that AtFKBP12 is functional during anaerobic growth. However, the functions of AtFKBP12 have never been examined in parallel under aerobic and anaerobic growth conditions so far. To this end, we cloned the FKBP12 gene of humans, yeast, and Arabidopsis, respectively. Transgenic plants were generated, and pharmacological examinations were performed in parallel with Arabidopsis under aerobic and anaerobic conditions. ScFKBP12 conferred plants with the strongest sensitivity to rapamycin, followed by HsFKBP12, whereas AtFKBP12 failed to generate rapamycin sensitivity under aerobic condition. Upon submergence, yeast and human FKBP12 can significantly block cotyledon greening while Arabidopsis FKBP12 only retards plant growth in the presence of rapamycin, suggesting that hypoxia stress could partially restore the functions of AtFKBP12 to bridge the interaction between rapamycin and TOR. To further determine if communication between TOR and auxin signaling exists in plants, yeast FKBP12 was introduced into DR5::GUS homozygous plants. The transgenic plants DR5/BP12 were then treated with rapamycin or KU63794 (a new inhibitor of TOR). GUS staining showed that the auxin content of root tips decreased compared to the control. DR5/BP12 plants lost sensitivity to auxin after treatment with rapamycin. Auxin-defective phenotypes, including short primary roots, fewer lateral roots, and loss of gravitropism, occurred in DR5/BP12 plants when seedlings were treated with rapamycin+KU63794. This indicated that the combination of rapamycin and KU63794 can significantly inhibit TOR and auxin signaling in DR5/BP12 plants. These studies demonstrate that TOR is essential for auxin signaling transduction in Arabidopsis.
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Affiliation(s)
- Kexuan Deng
- School of Life Sciences, Chongqing UniversityChongqing, China
| | - Lihua Yu
- School of Life Sciences, Chongqing UniversityChongqing, China
| | - Xianzhe Zheng
- School of Life Sciences, Chongqing UniversityChongqing, China
| | - Kang Zhang
- School of Life Sciences, Chongqing UniversityChongqing, China
| | - Wanjing Wang
- College of Agronomy and Biotechnology, Southwest UniversityChongqing, China
| | - Pan Dong
- School of Life Sciences, Chongqing UniversityChongqing, China
| | - Jiankui Zhang
- College of Agronomy and Biotechnology, Southwest UniversityChongqing, China
| | - Maozhi Ren
- School of Life Sciences, Chongqing UniversityChongqing, China
- *Correspondence: Maozhi Ren
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41
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Teixeira V, Costa V. Unraveling the role of the Target of Rapamycin signaling in sphingolipid metabolism. Prog Lipid Res 2015; 61:109-33. [PMID: 26703187 DOI: 10.1016/j.plipres.2015.11.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 02/06/2023]
Abstract
Sphingolipids are important bioactive molecules that regulate basic aspects of cellular metabolism and physiology, including cell growth, adhesion, migration, senescence, apoptosis, endocytosis, and autophagy in yeast and higher eukaryotes. Since they have the ability to modulate the activation of several proteins and signaling pathways, variations in the relative levels of different sphingolipid species result in important changes in overall cellular functions and fate. Sphingolipid metabolism and their route of synthesis are highly conserved from yeast to mammalian cells. Studies using the budding yeast Saccharomyces cerevisiae have served in many ways to foster our understanding of sphingolipid dynamics and their role in the regulation of cellular processes. In the past decade, studies in S. cerevisiae have unraveled a functional association between the Target of Rapamycin (TOR) pathway and sphingolipids, showing that both TOR Complex 1 (TORC1) and TOR Complex 2 (TORC2) branches control temporal and spatial aspects of sphingolipid metabolism in response to physiological and environmental cues. In this review, we report recent findings in this emerging and exciting link between the TOR pathway and sphingolipids and implications in human health and disease.
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Affiliation(s)
- Vitor Teixeira
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; IBMC, Instituto de Biologia Molecular e Celular, Porto, Portugal; ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Departamento de Biologia Molecular, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Vítor Costa
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; IBMC, Instituto de Biologia Molecular e Celular, Porto, Portugal; ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Departamento de Biologia Molecular, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
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Abstract
TOR (target of rapamycin) and its mammalian ortholog mTOR have been discovered in an effort to understand the mechanisms of action of the immunosuppressant drug rapamycin extracted from a bacterium of the Easter Island (Rapa Nui) soil. mTOR is a serine/threonine kinase found in two functionally distinct complexes, mTORC1 and mTORC2, which are differentially regulated by a great number of nutrients such as glucose and amino acids, energy (oxygen and ATP/AMP content), growth factors, hormones, and neurotransmitters. mTOR controls many basic cellular functions such as protein synthesis, energy metabolism, cell size, lipid metabolism, autophagy, mitochondria, and lysosome biogenesis. In addition, mTOR-controlled signaling pathways regulate many integrated physiological functions of the nervous system including neuronal development, synaptic plasticity, memory storage, and cognition. Thus it is not surprising that deregulation of mTOR signaling is associated with many neurological and psychiatric disorders. Preclinical and preliminary clinical studies indicate that inhibition of mTORC1 can be beneficial for some pathological conditions such as epilepsy, cognitive impairment, and brain tumors, whereas stimulation of mTORC1 (direct or indirect) can be beneficial for other pathologies such as depression or axonal growth and regeneration.
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Affiliation(s)
- Joël Bockaert
- Centre National de la Recherche Scientifique, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France; Institut National de la Santé et de la Recherche Médicale U1191, Montpellier, France; and Université de Montpellier, UMR-5203, Montpellier, France
| | - Philippe Marin
- Centre National de la Recherche Scientifique, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France; Institut National de la Santé et de la Recherche Médicale U1191, Montpellier, France; and Université de Montpellier, UMR-5203, Montpellier, France
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Abstract
mTOR (mechanistic target of rapamycin) functions as the central regulator for cell proliferation, growth and survival. Up-regulation of proteins regulating mTOR, as well as its downstream targets, has been reported in various cancers. This has promoted the development of anti-cancer therapies targeting mTOR, namely fungal macrolide rapamycin, a naturally occurring mTOR inhibitor, and its analogues (rapalogues). One such rapalogue, everolimus, has been approved in the clinical treatment of renal and breast cancers. Although results have demonstrated that these mTOR inhibitors are effective in attenuating cell growth of cancer cells under in vitro and in vivo conditions, subsequent sporadic response to rapalogues therapy in clinical trials has promoted researchers to look further into the complex understanding of the dynamics of mTOR regulation in the tumour environment. Limitations of these rapalogues include the sensitivity of tumour subsets to mTOR inhibition. Additionally, it is well known that rapamycin and its rapalogues mediate their effects by inhibiting mTORC (mTOR complex) 1, with limited or no effect on mTORC2 activity. The present review summarizes the pre-clinical, clinical and recent discoveries, with emphasis on the cellular and molecular effects of everolimus in cancer therapy.
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Wride DA, Pourmand N, Bray WM, Kosarchuk JJ, Nisam SC, Quan TK, Berkeley RF, Katzman S, Hartzog GA, Dobkin CE, Scott Lokey R. Confirmation of the cellular targets of benomyl and rapamycin using next-generation sequencing of resistant mutants in S. cerevisiae. MOLECULAR BIOSYSTEMS 2015; 10:3179-87. [PMID: 25257345 DOI: 10.1039/c4mb00146j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Investigating the mechanisms of action (MOAs) of bioactive compounds and the deconvolution of their cellular targets is an important and challenging undertaking. Drug resistance in model organisms such as S. cerevisiae has long been a means for discovering drug targets and MOAs. Strains are selected for resistance to a drug of interest, and the resistance mutations can often be mapped to the drug's molecular target using classical genetic techniques. Here we demonstrate the use of next generation sequencing (NGS) to identify mutations that confer resistance to two well-characterized drugs, benomyl and rapamycin. Applying NGS to pools of drug-resistant mutants, we develop a simple system for ranking single nucleotide polymorphisms (SNPs) based on their prevalence in the pool, and for ranking genes based on the number of SNPs that they contain. We clearly identified the known targets of benomyl (TUB2) and rapamycin (FPR1) as the highest-ranking genes under this system. The highest-ranking SNPs corresponded to specific amino acid changes that are known to confer resistance to these drugs. We also found that by screening in a pdr1Δ null background strain that lacks a transcription factor regulating the expression of drug efflux pumps, and by pre-screening mutants in a panel of unrelated anti-fungal agents, we were able to mitigate against the selection of multi-drug resistance (MDR) mutants. We call our approach "Mutagenesis to Uncover Targets by deep Sequencing", or "MUTseq", and show through this proof-of-concept study its potential utility in characterizing MOAs and targets of novel compounds.
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Affiliation(s)
- Dustin A Wride
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, USA.
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45
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Chantranupong L, Wolfson RL, Sabatini DM. Nutrient-sensing mechanisms across evolution. Cell 2015; 161:67-83. [PMID: 25815986 DOI: 10.1016/j.cell.2015.02.041] [Citation(s) in RCA: 229] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Indexed: 12/11/2022]
Abstract
For organisms to coordinate their growth and development with nutrient availability, they must be able to sense nutrient levels in their environment. Here, we review select nutrient-sensing mechanisms in a few diverse organisms. We discuss how these mechanisms reflect the nutrient requirements of specific species and how they have adapted to the emergence of multicellularity in eukaryotes.
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Affiliation(s)
- Lynne Chantranupong
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Rachel L Wolfson
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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Gaubitz C, Oliveira TM, Prouteau M, Leitner A, Karuppasamy M, Konstantinidou G, Rispal D, Eltschinger S, Robinson GC, Thore S, Aebersold R, Schaffitzel C, Loewith R. Molecular Basis of the Rapamycin Insensitivity of Target Of Rapamycin Complex 2. Mol Cell 2015; 58:977-88. [PMID: 26028537 DOI: 10.1016/j.molcel.2015.04.031] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 03/31/2015] [Accepted: 04/22/2015] [Indexed: 10/23/2022]
Abstract
Target of Rapamycin (TOR) plays central roles in the regulation of eukaryote growth as the hub of two essential multiprotein complexes: TORC1, which is rapamycin-sensitive, and the lesser characterized TORC2, which is not. TORC2 is a key regulator of lipid biosynthesis and Akt-mediated survival signaling. In spite of its importance, its structure and the molecular basis of its rapamycin insensitivity are unknown. Using crosslinking-mass spectrometry and electron microscopy, we determined the architecture of TORC2. TORC2 displays a rhomboid shape with pseudo-2-fold symmetry and a prominent central cavity. Our data indicate that the C-terminal part of Avo3, a subunit unique to TORC2, is close to the FKBP12-rapamycin-binding domain of Tor2. Removal of this sequence generated a FKBP12-rapamycin-sensitive TORC2 variant, which provides a powerful tool for deciphering TORC2 function in vivo. Using this variant, we demonstrate a role for TORC2 in G2/M cell-cycle progression.
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Affiliation(s)
- Christl Gaubitz
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Taiana M Oliveira
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France; Fondation ARC, 9 rue Guy Môquet, BP 90003, 04803 Villejuif Cedex, France
| | - Manoel Prouteau
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Alexander Leitner
- Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland
| | - Manikandan Karuppasamy
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Georgia Konstantinidou
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Delphine Rispal
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Sandra Eltschinger
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Graham C Robinson
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Stéphane Thore
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland; University of Bordeaux, European Institute for Chemistry and Biology, ARNA Laboratory, F-33607 Pessac, France; Institut National de la Santé Et de la Recherche Médicale, INSERM-U869, ARNA Laboratory, F-33000, Bordeaux, France
| | - Ruedi Aebersold
- Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland; Faculty of Science, University of Zürich, 8057 Zürich, Switzerland
| | - Christiane Schaffitzel
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France; School of Biochemistry, University of Bristol, Bristol, BS8 1TD, United Kingdom.
| | - Robbie Loewith
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland; National Centre of Competence in Research "Chemical Biology," University of Geneva, Geneva CH-1211, Switzerland.
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Abstract
AbstractOver the last few years extensive studies have linked the activity of mTORC1 to lysosomal function. These observations propose an intriguing integration of cellular catabolism, sustained by lysosomes, with anabolic processes, largely controlled by mTORC1. Interestingly, lysosomal function directly affects mTORC1 activity and is regulated by ZKSCAN3 and TFEB, two transcription factors and substrates of mTORC1. Thus, the lysosomal mTOR signaling complex represents a hub of cellular energy metabolism, and its dysregulation may lead to a number of human diseases. Here, we discuss the recent developments and highlight the open questions in this growing field.
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48
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Chen TT, Maevsky EI, Uchitel ML. Maintenance of homeostasis in the aging hypothalamus: the central and peripheral roles of succinate. Front Endocrinol (Lausanne) 2015; 6:7. [PMID: 25699017 PMCID: PMC4313775 DOI: 10.3389/fendo.2015.00007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 01/14/2015] [Indexed: 12/20/2022] Open
Abstract
Aging is the phenotype resulting from accumulation of genetic, cellular, and molecular damages. Many factors have been identified as either the cause or consequence of age-related decline in functions and repair mechanisms. The hypothalamus is the source and a target of many of these factors and hormones responsible for the overall homeostasis in the body. With advanced age, the sensitivity of the hypothalamus to various feedback signals begins to decline. In recent years, several aging-related genes have been identified and their signaling pathways elucidated. These gene products include mTOR, IKK-β/NF-κB complex, and HIF-1α, an important cellular survival signal. All of these activators/modulators of the aging process have also been identified in the hypothalamus and shown to play crucial roles in nutrient sensing, metabolic regulation, energy balance, reproductive function, and stress adaptation. This illustrates the central role of the hypothalamus in aging. Inside the mitochondria, succinate is one of the most prominent intermediates of the Krebs cycle. Succinate oxidation in mitochondria provides the most powerful energy output per unit time. Extra-mitochondrial succinate triggers a host of succinate receptor (SUCN1 or GPR91)-mediated signaling pathways in many peripheral tissues including the hypothalamus. One of the actions of succinate is to stabilize the hypoxia and cellular stress conditions by inducing the transcriptional regulator HIF-1α. Through these actions, it is hypothesized that succinate has the potential to restore the gradual but significant loss in functions associated with cellular senescence and systemic aging.
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Affiliation(s)
- Thomas T. Chen
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Moscow, Russia
- *Correspondence: Thomas T. Chen, Department of Life Sciences, Santa Monica College, 1900 Pico Boulevard, Santa Monica, CA 90405, USA e-mail:
| | - Eugene I. Maevsky
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Moscow, Russia
| | - Mikhail L. Uchitel
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Moscow, Russia
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49
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Li L, Song Y, Wang K, Dong P, Zhang X, Li F, Li Z, Ren M. TOR-inhibitor insensitive-1 (TRIN1) regulates cotyledons greening in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2015; 6:861. [PMID: 26557124 PMCID: PMC4617058 DOI: 10.3389/fpls.2015.00861] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Accepted: 09/29/2015] [Indexed: 05/19/2023]
Abstract
Target of Rapamycin (TOR) is an eukaryotic protein kinase and evolutionally conserved from the last eukaryotic common ancestor (LECA) to humans. The growing evidences have shown that TOR signaling acts as a central controller of cell growth and development. The downstream effectors of TOR have been well-identified in yeast and animals by using the immunosuppression agent rapamycin. However, less is known about TOR in plants. This is largely due to the fact that plants are insensitive to rapamycin. In this study, AZD8055 (AZD), the novel ATP-competitive inhibitor of TOR, was employed to decipher the downstream effectors of TOR in Arabidopsis. One AZD insensitive mutant, T O R - i nhibitor i n sensitive- 1 (trin1), was screened from 10,000 EMS-induced mutation seeds. The cotyledons of trin1 can turn green when its seeds were germinated on ½ MS medium supplemented with 2 μM AZD, whereas the cotyledons greening of wild-type (WT) can be completely blocked at this concentration. Through genetic mapping, TRIN1 was mapped onto the long arm of chromosome 2, between markers SGCSNP26 and MI277. Positional cloning revealed that TRIN1 was an allele of ABI4, which encoded an ABA-regulated AP2 domain transcription factor. Plants containing P35S::TRIN1 or P35S::TRIN1-GUS were hypersensitive to AZD treatment and displayed the opposite phenotype observed in trin1. Importantly, GUS signaling was significantly enhanced in P35S::TRIN1-GUS transgenic plants in response to AZD treatment, indicating that suppression of TOR resulted in the accumulation of TRIN1. These observations revealed that TOR controlled seed-to-seedling transition by negatively regulating the stability of TRIN1 in Arabidopsis. For the first time, TRIN1, the downstream effector of TOR signaling, was identified through a chemical genetics approach.
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Affiliation(s)
- Linxuan Li
- School of Life Sciences, Chongqing UniversityChongqing, China
- *Correspondence: Maozhi Ren
| | - Yun Song
- Institute of Cotton Research, Chinese Academy of Agricultural Sciences, the State Key Laboratory of Cotton BiologyHenan, China
- *Correspondence: Maozhi Ren
| | - Kai Wang
- School of Life Sciences, Chongqing UniversityChongqing, China
| | - Pan Dong
- School of Life Sciences, Chongqing UniversityChongqing, China
| | - Xueyan Zhang
- Institute of Cotton Research, Chinese Academy of Agricultural Sciences, the State Key Laboratory of Cotton BiologyHenan, China
| | - Fuguang Li
- Institute of Cotton Research, Chinese Academy of Agricultural Sciences, the State Key Laboratory of Cotton BiologyHenan, China
| | - Zhengguo Li
- School of Life Sciences, Chongqing UniversityChongqing, China
| | - Maozhi Ren
- School of Life Sciences, Chongqing UniversityChongqing, China
- *Correspondence: Maozhi Ren
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50
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Land SC, Scott CL, Walker D. mTOR signalling, embryogenesis and the control of lung development. Semin Cell Dev Biol 2014; 36:68-78. [PMID: 25289569 DOI: 10.1016/j.semcdb.2014.09.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 09/07/2014] [Accepted: 09/11/2014] [Indexed: 12/15/2022]
Abstract
The existence of a nutrient sensitive "autocatakinetic" regulator of embryonic tissue growth has been hypothesised since the early 20th century, beginning with pioneering work on the determinants of foetal size by the Australian physiologist, Thorburn Brailsford-Robertson. We now know that the mammalian target of rapamycin complexes (mTORC1 and 2) perform this essential function in all eukaryotic tissues by balancing nutrient and energy supply during the first stages of embryonic cleavage, the formation of embryonic stem cell layers and niches, the highly specified programmes of tissue growth during organogenesis and, at birth, paving the way for the first few breaths of life. This review provides a synopsis of the role of the mTOR complexes in each of these events, culminating in an analysis of lung branching morphogenesis as a way of demonstrating the central role mTOR in defining organ structural complexity. We conclude that the mTOR complexes satisfy the key requirements of a nutrient sensitive growth controller and can therefore be considered as Brailsford-Robertson's autocatakinetic centre that drives tissue growth programmes during foetal development.
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Affiliation(s)
- Stephen C Land
- Division of Cardiovascular and Diabetes Medicine, Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK.
| | - Claire L Scott
- Prostrakan Pharmaceuticals, Galabank Business Park, Galashiels TD1 1PR, UK
| | - David Walker
- School of Psychology & Neuroscience, Westburn Lane, St Andrews KY16 9JP, UK
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