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Yang C, Sun X, Wu G. New insights into GATOR2-dependent interactions and its conformational changes in amino acid sensing. Biosci Rep 2024; 44:BSR20240038. [PMID: 38372438 PMCID: PMC10938194 DOI: 10.1042/bsr20240038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 02/08/2024] [Accepted: 02/13/2024] [Indexed: 02/20/2024] Open
Abstract
Eukaryotic cells coordinate growth under different environmental conditions via mechanistic target of rapamycin complex 1 (mTORC1). In the amino-acid-sensing signalling pathway, the GATOR2 complex, containing five evolutionarily conserved subunits (WDR59, Mios, WDR24, Seh1L and Sec13), is required to regulate mTORC1 activity by interacting with upstream CASTOR1 (arginine sensor) and Sestrin2 (leucine sensor and downstream GATOR1 complex). GATOR2 complex utilizes β-propellers to engage with CASTOR1, Sestrin2 and GATOR1, removal of these β-propellers results in substantial loss of mTORC1 capacity. However, structural information regarding the interface between amino acid sensors and GATOR2 remains elusive. With the recent progress of the AI-based tool AlphaFold2 (AF2) for protein structure prediction, structural models were predicted for Sentrin2-WDR24-Seh1L and CASTOR1-Mios β-propeller. Furthermore, the effectiveness of relevant residues within the interface was examined using biochemical experiments combined with molecular dynamics (MD) simulations. Notably, fluorescence resonance energy transfer (FRET) analysis detected the structural transition of GATOR2 in response to amino acid signals, and the deletion of Mios β-propeller severely impeded that change at distinct arginine levels. These findings provide structural perspectives on the association between GATOR2 and amino acid sensors and can facilitate future research on structure determination and function.
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Affiliation(s)
- Can Yang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, the Joint International Research Laboratory of Metabolic and Developmental Sciences MOE, Shanghai Jiao Tong University, Shanghai, China
| | - Xuan Sun
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, the Joint International Research Laboratory of Metabolic and Developmental Sciences MOE, Shanghai Jiao Tong University, Shanghai, China
| | - Geng Wu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, the Joint International Research Laboratory of Metabolic and Developmental Sciences MOE, Shanghai Jiao Tong University, Shanghai, China
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2
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Kanzaki K, Wada M. Effects of Leucine Ingestion and Contraction on the Sestrin/GATOR2 Pathway and mTORC1 Activation in Rat Fast-Twitch muscle. J Nutr 2023; 153:2228-2236. [PMID: 37328110 DOI: 10.1016/j.tjnut.2023.06.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 06/05/2023] [Accepted: 06/13/2023] [Indexed: 06/18/2023] Open
Abstract
BACKGROUND Leucine activates the mechanistic/mammalian target of rapamycin complex 1 (mTORC1) in mammalian skeletal muscle. Recent studies have shown that Sestrin, a leucine sensor, might play a role in this process. However, it remains unknown whether Sestrin dissociates from GATOR2 in a dose- and time-dependent manner and whether an acute bout of muscle contraction augments this dissociation. OBJECTIVE This study aimed to examine the effects of leucine ingestion and muscle contraction on the interaction between Sestrin1/2 and GATOR2 and on mTORC1 activation. METHODS Male Wistar rats were randomly assigned to control (C), leucine 3 (L3), or leucine 10 (L10) groups. Intact gastrocnemius muscles were subjected to 30 repetitive unilateral contractions. The L3 and L10 groups were then orally administered 3 and 10 mmol/kg body weight of L-leucine 2 h after the end of the contractions, respectively. Blood and muscle samples were collected 30, 60, or 120 min after the administration. RESULTS The blood and muscle leucine concentrations increased in a dose-dependent manner. The ratio of phosphorylated ribosomal protein S6 kinase (S6K) to total S6K (which indicates mTORC1 signaling activation) was markedly increased by muscle contraction and increased in a dose-dependent manner only in rested muscle. Leucine ingestion but not muscle contraction increased Sestrin1 dissociation from GATOR2 and Sestrin2 association with GATOR2. A negative relationship was observed between the blood and muscle leucine concentrations and the Sestrin1 association with GATOR2. CONCLUSIONS The results suggest that Sestrin1, but not Sestrin2, regulates leucine-related mTORC1 activation via its dissociation from GATOR2 and that acute exercise-induced mTORC1 activation involves pathways other than the leucine-related Sestrin1/GATOR2 pathway.
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Affiliation(s)
- Keita Kanzaki
- Department of Clinical Nutrition, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, Okayama, Japan.
| | - Masanobu Wada
- Graduate School of Humanities and Social Sciences, Hiroshima University, Hiroshima, Japan
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Parikh J, Bhatt K, Patel N, Modi K, Parmar N. Host-guest interaction of tryptophane with acid-functionalized calix[4]pyrrole: a fluorescence-based study. J Biomol Struct Dyn 2023:1-8. [PMID: 37378514 DOI: 10.1080/07391102.2023.2229448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 06/19/2023] [Indexed: 06/29/2023]
Abstract
Functionalized calix[4]pyrroles are at forefront of host-guest aided molecular sensors. They offer unique platform for flexible functionalization to develop receptors suitable for different applications. In this context, calix[4]pyrrole derivative (TACP) was functionalized with an acidic group to investigate its binding behavior with different amino acids. The acid functionalization facilitated host-guest interactions through hydrogen bonding and increase the solubility of ligand in 90% aqueous media. The results indicated that TACP exhibited significant fluorescence enhancement in the presence of tryptophan while no considerable changes were observed with other amino acids. The other complexation properties such as LOD and LOQ were determined to be 25 µM and 22 µM respectively with 1:1 stoichiometry. In addition, the proposed binding phenomena were further confirmed through computational docking studies and NMR complexation study. Overall, this work highlights the potential of acid functionalization in developing molecular sensors for amino acid detection using calix[4]pyrrole derivatives.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Jaymin Parikh
- Department of Chemistry, Faculty of Science, Ganpat University, Mehsana, Gujarat, India
| | - Keyur Bhatt
- Department of Chemistry, Faculty of Science, Ganpat University, Mehsana, Gujarat, India
| | - Nihal Patel
- Department of Chemistry, Faculty of Science, Ganpat University, Mehsana, Gujarat, India
| | - Krunal Modi
- Department of Humanity and Sciences, School of engineering, Indrashil university, Kadi, Mehsana, Gujarat, India
| | - Nirali Parmar
- Department of Chemistry, Faculty of Science, Ganpat University, Mehsana, Gujarat, India
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4
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Li FL, Guan KL. The Arf family GTPases: Regulation of vesicle biogenesis and beyond. Bioessays 2023; 45:e2200214. [PMID: 36998106 DOI: 10.1002/bies.202200214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 03/16/2023] [Accepted: 03/17/2023] [Indexed: 04/01/2023]
Abstract
The Arf family proteins are best known for their roles in the vesicle biogenesis. However, they also play fundamental roles in a wide range of cellular regulation besides vesicular trafficking, such as modulation of lipid metabolic enzymes, cytoskeleton remodeling, ciliogenesis, lysosomal, and mitochondrial morphology and functions. Growing studies continue to expand the downstream effector landscape of Arf proteins, especially for the less-studied members, revealing new biological functions, such as amino acid sensing. Experiments with cutting-edge technologies and in vivo functional studies in the last decade help to provide a more comprehensive view of Arf family functions. In this review, we summarize the cellular functions that are regulated by at least two different Arf members with an emphasis on those beyond vesicle biogenesis.
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Affiliation(s)
- Fu-Long Li
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Kun-Liang Guan
- Department of Pharmacology and Moores Cancer Center, University of California San Diego, La Jolla, California, USA
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5
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Lama-Sherpa TD, Jeong MH, Jewell JL. Regulation of mTORC1 by the Rag GTPases. Biochem Soc Trans 2023:BST20210038. [PMID: 36929165 DOI: 10.1042/BST20210038] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 02/21/2023] [Accepted: 02/23/2023] [Indexed: 03/18/2023]
Abstract
The Rag GTPases are an evolutionarily conserved family that play a crucial role in amino acid sensing by the mammalian target of rapamycin complex 1 (mTORC1). mTORC1 is often referred to as the master regulator of cell growth. mTORC1 hyperactivation is observed in multiple diseases such as cancer, obesity, metabolic disorders, and neurodegeneration. The Rag GTPases sense amino acid levels and form heterodimers, where RagA or RagB binds to RagC or RagD, to recruit mTORC1 to the lysosome where it becomes activated. Here, we review amino acid signaling to mTORC1 through the Rag GTPases.
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Jiang C, Dai X, He S, Zhou H, Fang L, Guo J, Liu S, Zhang T, Pan W, Yu H, Fu T, Li D, Inuzuka H, Wang P, Xiao J, Wei W. Ring domains are essential for GATOR2-dependent mTORC1 activation. Mol Cell 2023; 83:74-89.e9. [PMID: 36528027 PMCID: PMC11027793 DOI: 10.1016/j.molcel.2022.11.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 09/14/2022] [Accepted: 11/22/2022] [Indexed: 12/23/2022]
Abstract
The GATOR2-GATOR1 signaling axis is essential for amino-acid-dependent mTORC1 activation. However, the molecular function of the GATOR2 complex remains unknown. Here, we report that disruption of the Ring domains of Mios, WDR24, or WDR59 completely impedes amino-acid-mediated mTORC1 activation. Mechanistically, via interacting with Ring domains of WDR59 and WDR24, the Ring domain of Mios acts as a hub to maintain GATOR2 integrity, disruption of which leads to self-ubiquitination of WDR24. Physiologically, leucine stimulation dissociates Sestrin2 from the Ring domain of WDR24 and confers its availability to UBE2D3 and subsequent ubiquitination of NPRL2, contributing to GATOR2-mediated GATOR1 inactivation. As such, WDR24 ablation or Ring deletion prevents mTORC1 activation, leading to severe growth defects and embryonic lethality at E10.5 in mice. Hence, our findings demonstrate that Ring domains are essential for GATOR2 to transmit amino acid availability to mTORC1 and further reveal the essentiality of nutrient sensing during embryonic development.
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Affiliation(s)
- Cong Jiang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Xiaoming Dai
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Shaohui He
- Joint Research Center for Musculoskeletal Tumor of Shanghai Changzheng Hospital and University of Shanghai for Science and Technology, Spinal Tumor Center, Department of Orthopedic Oncology, Shanghai Changzheng Hospital, Shanghai 200003, China
| | - Hongfei Zhou
- Joint Research Center for Musculoskeletal Tumor of Shanghai Changzheng Hospital and University of Shanghai for Science and Technology, Spinal Tumor Center, Department of Orthopedic Oncology, Shanghai Changzheng Hospital, Shanghai 200003, China
| | - Lan Fang
- Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Jianping Guo
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Songlei Liu
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Tao Zhang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Weijuan Pan
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Haihong Yu
- Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Tianmin Fu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Dali Li
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Hiroyuki Inuzuka
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Ping Wang
- Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Jianru Xiao
- Joint Research Center for Musculoskeletal Tumor of Shanghai Changzheng Hospital and University of Shanghai for Science and Technology, Spinal Tumor Center, Department of Orthopedic Oncology, Shanghai Changzheng Hospital, Shanghai 200003, China.
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
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Paolina Crocco, Serena Dato, Alberto Montesanto, Anna Rita Bonfigli, Roberto Testa, Fabiola Olivieri, Giuseppe Passarino, Giuseppina Rose. The Genetic Variability of Members of the SLC38 Family of Amino Acid Transporters ( SLC38A3, SLC38A7 and SLC38A9) Affects Susceptibility to Type 2 Diabetes and Vascular Complications. Nutrients 2022; 14:4440. [PMID: 36364703 DOI: 10.3390/nu14214440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/18/2022] [Accepted: 10/20/2022] [Indexed: 01/25/2023] Open
Abstract
Type 2 Diabetes (T2D) is a metabolic disease associated with long-term complications, with a multifactorial pathogenesis related to the interplay between genetic and modifiable risk factors, of which nutrition is the most relevant. In particular, the importance of proteins and constitutive amino acids (AAs) in disease susceptibility is emerging. The ability to sense and respond to changes in AA supplies is mediated by complex networks, of which AA transporters (AATs) are crucial components acting also as sensors of AA availability. This study explored the associations between polymorphisms in selected AATs genes and T2D and vascular complications in 433 patients and 506 healthy controls. Analyses revealed significant association of SLC38A3-rs1858828 with disease risk. Stratification of patients based on presence/absence of vascular complications highlighted significant associations of SLC7A8-rs3783436 and SLC38A7-rs9806843 with diabetic retinopathy. Additionally, the SLC38A9-rs4865615 resulted associated with chronic kidney disease. Notably, these genes function as AAs sensors, specifically glutamine, leucine, and arginine, linked to the main nutrient signaling pathway mammalian target of rapamycin complex 1 (mTORC1). Thus, their genetic variability may contribute to T2D by influencing the ability to properly transduce a signal activating mTORC1 in response to AA availability. In this scenario, the contribution of dietary AAs supply to disease risk may be relevant.
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8
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Abdullah MO, Zeng RX, Margerum CL, Papadopoli D, Monnin C, Punter KB, Chu C, Al-Rofaidi M, Al-Tannak NF, Berardi D, Rattray Z, Rattray NJW, Abraham SA, Eskelinen EL, Watson DG, Avizonis D, Topisirovic I, Chan EYW. Mitochondrial hyperfusion via metabolic sensing of regulatory amino acids. Cell Rep 2022; 40:111198. [PMID: 35977476 DOI: 10.1016/j.celrep.2022.111198] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 06/06/2022] [Accepted: 07/21/2022] [Indexed: 11/24/2022] Open
Abstract
The relationship between nutrient starvation and mitochondrial dynamics is poorly understood. We find that cells facing amino acid starvation display clear mitochondrial fusion as a means to evade mitophagy. Surprisingly, further supplementation of glutamine (Q), leucine (L), and arginine (R) did not reverse, but produced stronger mitochondrial hyperfusion. Interestingly, the hyperfusion response to Q + L + R was dependent upon mitochondrial fusion proteins Mfn1 and Opa1 but was independent of MTORC1. Metabolite profiling indicates that Q + L + R addback replenishes amino acid and nucleotide pools. Inhibition of fumarate hydratase, glutaminolysis, or inosine monophosphate dehydrogenase all block Q + L + R-dependent mitochondrial hyperfusion, which suggests critical roles for the tricarboxylic acid (TCA) cycle and purine biosynthesis in this response. Metabolic tracer analyses further support the idea that supplemented Q promotes purine biosynthesis by serving as a donor of amine groups. We thus describe a metabolic mechanism for direct sensing of cellular amino acids to control mitochondrial fusion and cell fate.
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Moormann J, Heinemann B, Hildebrandt TM. News about amino acid metabolism in plant-microbe interactions. Trends Biochem Sci 2022; 47:839-850. [PMID: 35927139 DOI: 10.1016/j.tibs.2022.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 06/17/2022] [Accepted: 07/06/2022] [Indexed: 01/17/2023]
Abstract
Plants constantly come into contact with a diverse mix of pathogenic and beneficial microbes. The ability to distinguish between them and to respond appropriately is essential for plant health. Here we review recent progress in understanding the role of amino acid sensing, signaling, transport, and metabolism during plant-microbe interactions. Biochemical pathways converting individual amino acids into active compounds have recently been elucidated, and comprehensive large-scale approaches have brought amino acid sensors and transporters into focus. These findings show that plant central amino acid metabolism is closely interwoven with stress signaling and defense responses at various levels. The individual biochemical mechanisms and the interconnections between the different processes are just beginning to emerge and might serve as a foundation for new plant protection strategies.
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Affiliation(s)
- Jannis Moormann
- Institute for Plant Genetics, Department of Plant Proteomics, Leibniz University Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany
| | - Björn Heinemann
- Institute for Plant Genetics, Department of Plant Proteomics, Leibniz University Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany
| | - Tatjana M Hildebrandt
- Institute for Plant Sciences, Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Zülpicher Straße 47a, 50674 Cologne, Germany.
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10
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Wang D, Xu C, Yang W, Chen J, Ou Y, Guan Y, Guan J, Liu Y. E3 ligase RNF167 and deubiquitinase STAMBPL1 modulate mTOR and cancer progression. Mol Cell 2022; 82:770-784.e9. [PMID: 35114100 DOI: 10.1016/j.molcel.2022.01.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 11/15/2021] [Accepted: 12/29/2021] [Indexed: 12/16/2022]
Abstract
The mTOR complex 1 (mTORC1) is an essential metabolic hub that coordinates cellular metabolism with the availability of nutrients, including amino acids. Sestrin2 has been identified as a cytosolic leucine sensor that transmits leucine status signals to mTORC1. In this study, we identify an E3 ubiquitin ligase RING finger protein 167 (RNF167) and a deubiquitinase STAMBPL1 that function in concert to control the polyubiquitination level of Sestrin2 in response to leucine availability. Ubiquitination of Sestrin2 promotes its interaction with GATOR2 and inhibits mTORC1 signaling. Bioinformatic analysis reveals decreased RNF167 expression and increased STAMBPL1 expression in gastric and colorectal tumors. Knockout of STAMBPL1 or correction of the heterozygous STAMBPL1 mutation in a human colon cancer cell line suppresses xenograft tumor growth. Lastly, a cell-permeable peptide that blocks the STAMBPL1-Sestrin2 interaction inhibits mTORC1 and provides a potential option for cancer therapy.
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Affiliation(s)
- Dong Wang
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Chenchen Xu
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Wenyu Yang
- Yuan Pei College, Peking University, Beijing 100871, China
| | - Jie Chen
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Yuhui Ou
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Yuanyuan Guan
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China
| | - Jialiang Guan
- PKU-Tsinghua-NIBS Graduate Program, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Ying Liu
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China; Beijing Advanced Innovation Center for Genomics, Beijing 100871, China.
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11
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Zhu M, Teng F, Li N, Zhang L, Zhang S, Xu F, Shao J, Sun H, Zhu H. Monomethyl branched-chain fatty acid mediates amino acid sensing upstream of mTORC1. Dev Cell 2021; 56:2692-2702.e5. [PMID: 34610328 DOI: 10.1016/j.devcel.2021.09.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 07/24/2021] [Accepted: 09/10/2021] [Indexed: 10/20/2022]
Abstract
Animals have developed various nutrient-sensing mechanisms for survival under fluctuating environmental conditions. Although extensive cell-culture-based analyses have identified diverse mediators of amino acid sensing upstream of mTOR, studies using animal models to examine intestine-initiated amino acid sensing mechanisms under specific physiological conditions are lacking. Here, we developed a Caenorhabditis elegans model to examine the impact of amino acid deficiency on development. We discovered a leucine-derived monomethyl branched-chain fatty acid and its downstream metabolite, glycosphingolipid, which critically mediates the overall amino acid sensing by intestinal and neuronal mTORC1, which in turn regulates postembryonic development at least partly by controlling protein translation and ribosomal biogenesis. Additional data suggest that a similar mechanism may operate in mammals. This study uncovers an amino-acid-sensing mechanism mediated by a lipid biosynthesis pathway.
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Affiliation(s)
- Mengnan Zhu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China; CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Fukang Teng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Na Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China; CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Li Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Shuxian Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Fan Xu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Jing Shao
- National Humanities Center Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Center for Cardiovascular Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China
| | - Haipeng Sun
- National Humanities Center Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Center for Cardiovascular Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China
| | - Huanhu Zhu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
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12
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Marek A, Opalek M, Kałdon A, Mickowska B, Wloch-Salamon D. Hypersensitive SSY1 mutations negatively influence transition to quiescence in yeast Saccharomyces cerevisiae. Yeast 2020; 38:102-116. [PMID: 33179371 DOI: 10.1002/yea.3536] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 10/28/2020] [Accepted: 11/02/2020] [Indexed: 01/20/2023] Open
Abstract
Most cells spend the majority of their life in the non-proliferating, quiescent state. Transition to this state is crucial for microorganisms to survive long starvation periods and restart divisions afterwards. Experimental evolution allowed us to identify several mutation in genes that are presumably important for such transition in yeast cells. Most of these candidate genes belong to the SPS amino acid sensing pathway or to the SIR complex. We assembled these mutations on the ancestral strain background. Analysis of the quiescent/non-quiescent cell ratio of the starved yeast populations confirmed the crucial role of SSY1, the primary receptor component of the SPS sensor, in transition to the Q state. The evolved SSY1 mutations increased yeast sensitivity to amino acid presence in the environment. This resulted in decreased quiescent cell fraction and a 5.14% increase of the total amino acid content in the starved populations. We discuss external amino acid sensing via the SPS pathway as one of the mechanisms influencing transition to quiescence.
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Affiliation(s)
- Agnieszka Marek
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Krakow, Poland
| | - Monika Opalek
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Krakow, Poland
| | - Aleksandra Kałdon
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Krakow, Poland
| | - Barbara Mickowska
- Faculty of Food Technology, Malopolska Centre of Food Monitoring, University of Agriculture in Krakow, Krakow, Poland
| | - Dominika Wloch-Salamon
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Krakow, Poland
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13
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Goldman-Pinkovich A, Kannan S, Nitzan-Koren R, Puri M, Pawar H, Bar-Avraham Y, McDonald J, Sur A, Zhang WW, Matlashewski G, Madhubala R, Michaeli S, Myler PJ, Zilberstein D. Sensing Host Arginine Is Essential for Leishmania Parasites' Intracellular Development. mBio 2020; 11:e02023-20. [PMID: 33051367 DOI: 10.1128/mBio.02023-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this study, we report that the ability of the human pathogen Leishmania to sense and monitor the lack of arginine in the phagolysosome of the host macrophage is essential for disease development. Phagolysosomes of macrophages are the niche where Leishmania resides and causes human leishmaniasis. During infection, the arginine concentration in the phagolysosome decreases as part of the host innate immune response. An arginine sensor on the Leishmania cell surface activates an arginine deprivation response pathway that upregulates the expression of a parasite arginine transporter (AAP3). Here, we use CRISPR/Cas9-mediated disruption of the AAP3 locus to show that this response enables Leishmania parasites to successfully compete with the host macrophage in the “hunger games” for arginine. Arginine homeostasis in lysosomes is critical for the growth and metabolism of mammalian cells. Phagolysosomes of macrophages are the niche where the parasitic protozoan Leishmania resides and causes human leishmaniasis. During infection, parasites encounter arginine deprivation, which is monitored by a sensor on the parasite cell surface. The sensor promptly activates a mitogen-activated protein kinase 2 (MAPK2)-mediated arginine deprivation response (ADR) pathway, resulting in upregulating the abundance and activity of the Leishmania arginine transporter (AAP3). Significantly, the ADR is also activated during macrophage infection, implying that arginine levels within the host phagolysosome are limiting for growth. We hypothesize that ADR-mediated upregulation of AAP3 activity is necessary to withstand arginine starvation, suggesting that the ADR is essential for parasite intracellular development. CRISPR/Cas9-mediated disruption of the AAP3 locus yielded mutants that retain a basal level of arginine transport but lack the ability to respond to arginine starvation. While these mutants grow normally in culture, they were impaired in their ability to develop inside THP-1 macrophages and were ∼70 to 80% less infective in BALB/c mice. Hence, inside the host macrophage, Leishmania must overcome the arginine “hunger games” by upregulating the transport of arginine via the ADR. We show that the ability to monitor and respond to changes in host metabolite levels is essential for pathogenesis.
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Newton P, Thomas DR, Reed SCO, Lau N, Xu B, Ong SY, Pasricha S, Madhamshettiwar PB, Edgington-Mitchell LE, Simpson KJ, Roy CR, Newton HJ. Lysosomal degradation products induce Coxiella burnetii virulence. Proc Natl Acad Sci U S A 2020; 117:6801-10. [PMID: 32152125 DOI: 10.1073/pnas.1921344117] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Coxiella burnetii is a unique bacterial pathogen that replicates to high numbers in a lysosome-like intracellular niche. This study identified host proteins that contribute to the pathogen’s capacity to establish this niche and activate the Dot/Icm secretion system required for intracellular replication. Many host proteins were found to contribute to the establishment of C. burnetii virulence by aiding trafficking of the pathogen to the lysosome and creating the degradative lysosome environment. Pathogenic bacteria are able to sense and adapt to their environment by altering their gene expression profile. Here we demonstrated that C. burnetii detects specific amino acids present in the lysosome using a two-component system that up-regulates expression of genes required for Dot/Icm activity. Coxiella burnetii is an intracellular pathogen that replicates in a lysosome-like vacuole through activation of a Dot/Icm-type IVB secretion system and subsequent translocation of effectors that remodel the host cell. Here a genome-wide small interfering RNA screen and reporter assay were used to identify host proteins required for Dot/Icm effector translocation. Significant, and independently validated, hits demonstrated the importance of multiple protein families required for endocytic trafficking of the C. burnetii-containing vacuole to the lysosome. Further analysis demonstrated that the degradative activity of the lysosome created by proteases, such as TPP1, which are transported to the lysosome by receptors, such as M6PR and LRP1, are critical for C. burnetii virulence. Indeed, the C. burnetii PmrA/B regulon, responsible for transcriptional up-regulation of genes encoding the Dot/Icm apparatus and a subset of effectors, induced expression of a virulence-associated transcriptome in response to degradative products of the lysosome. Luciferase reporter strains, and subsequent RNA-sequencing analysis, demonstrated that particular amino acids activate the C. burnetii PmrA/B two-component system. This study has further enhanced our understanding of C. burnetii pathogenesis, the host–pathogen interactions that contribute to bacterial virulence, and the different environmental triggers pathogens can sense to facilitate virulence.
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15
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Meng D, Yang Q, Wang H, Melick CH, Navlani R, Frank AR, Jewell JL. Glutamine and asparagine activate mTORC1 independently of Rag GTPases. J Biol Chem 2020; 295:2890-2899. [PMID: 32019866 DOI: 10.1074/jbc.ac119.011578] [Citation(s) in RCA: 113] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/24/2020] [Indexed: 12/14/2022] Open
Abstract
Nutrient sensing by cells is crucial, and when this sensing mechanism is disturbed, human disease can occur. mTOR complex 1 (mTORC1) senses amino acids to control cell growth, metabolism, and autophagy. Leucine, arginine, and methionine signal to mTORC1 through the well-characterized Rag GTPase signaling pathway. In contrast, glutamine activates mTORC1 through a Rag GTPase-independent mechanism that requires ADP-ribosylation factor 1 (Arf1). Here, using several biochemical and genetic approaches, we show that eight amino acids filter through the Rag GTPase pathway. Like glutamine, asparagine signals to mTORC1 through Arf1 in the absence of the Rag GTPases. Both the Rag-dependent and Rag-independent pathways required the lysosome and lysosomal function for mTORC1 activation. Our results show that mTORC1 is differentially regulated by amino acids through two distinct pathways.
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Affiliation(s)
- Delong Meng
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Qianmei Yang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Huanyu Wang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Chase H Melick
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Rishika Navlani
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Anderson R Frank
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Jenna L Jewell
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390.
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16
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Al-Bari MAA, Xu P. Molecular regulation of autophagy machinery by mTOR-dependent and -independent pathways. Ann N Y Acad Sci 2020; 1467:3-20. [PMID: 31985829 DOI: 10.1111/nyas.14305] [Citation(s) in RCA: 147] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 11/23/2019] [Accepted: 01/07/2020] [Indexed: 12/15/2022]
Abstract
Macroautophagy is a lysosomal degradative pathway or recycling process that maintains cellular homeostasis. This autophagy involves a series of sequential processing events, such as initiation; elongation and nucleation of the isolation membrane; cargo recruitment and maturation of the autophagosome (AP); transport of the AP; docking and fusion of the AP with a late endosome or lysosome; and regeneration of the lysosome by the autophagic lysosomal reformation cycle. These events are critically coordinated by the action of a set of several key components, including autophagy-related proteins (Atg), and regulated by intricate networks, such as mechanistic target of rapamycin (mTOR), a master regulator of autophagy, as well as mTOR-independent signaling pathways. Among mTOR-independent pathways, the transient receptor potential (TRP) calcium ion channel TRPML (mucolipin) subfamily is emerging as an important signaling channel to modulate lysosomal biogenesis and autophagy. This review discusses the recent advances in elucidating the molecular mechanisms and regulation of the autophagy process. Understanding these mechanisms may ultimately allow scientists and clinicians to control this process in order to improve human health.
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Affiliation(s)
| | - Pingyong Xu
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
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17
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Graber TG, Fry CS, Brightwell CR, Moro T, Maroto R, Bhattarai N, Porter C, Wakamiya M, Rasmussen BB. Skeletal muscle-specific knockout of DEP domain containing 5 protein increases mTORC1 signaling, muscle cell hypertrophy, and mitochondrial respiration. J Biol Chem 2019; 294:4091-4102. [PMID: 30635399 DOI: 10.1074/jbc.ra118.005970] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 01/09/2019] [Indexed: 11/06/2022] Open
Abstract
mTORC1 regulates protein synthesis and in turn is regulated by growth factors, energy status, and amino acid availability. In kidney cell (HEK293-T) culture, the GAP activity toward RAG (GATOR1) protein complex suppresses activation of the RAG A/B-RAG C/D heterodimer when amino acids are insufficient. During amino acid sufficiency, the RAG heterodimer recruits mTORC1 to the lysosomal membrane where its interaction with Ras homolog enriched in brain (Rheb) stimulates mTORC1's kinase activity. The DEP domain containing 5 (DEPDC5) protein, a GATOR1 subunit, causes familial focal epilepsy when mutated, and global knockout of the Depdc5 gene is embryonically lethal. To study the function of DEPDC5 in skeletal muscle, we generated a muscle-specific inducible Depdc5 knockout mouse, hypothesizing that knocking out Depdc5 in muscle would make mTORC1 constitutively active, causing hypertrophy and improving muscle function. Examining mTORC1 signaling, morphology, mitochondrial respiratory capacity, contractile function, and applied physical function (e.g. rotarod, treadmill, grip test, and wheel running), we observed that mTORC1 activity was significantly higher in knockout (KO) mice, indicated by the increased phosphorylation of mTOR and its downstream effectors (by 118% for p-mTOR/mTOR, 114% for p-S6K1/S6K1, and 35% for p-4E-BP1/4E-BP1). The KO animals also exhibited soleus muscle cell hypertrophy and a 2.5-fold increase in mitochondrial respiratory capacity. However, contrary to our hypothesis, neither physical nor contractile function improved. In conclusion, DEPDC5 depletion in adult skeletal muscle removes GATOR1 inhibition of mTORC1, resulting in muscle hypertrophy and increased mitochondrial respiration, but does not improve overall muscle quality and function.
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Affiliation(s)
- Ted G Graber
- From the Division of Rehabilitation Sciences.,the Department of Nutrition and Metabolism
| | | | | | | | | | | | | | - Maki Wakamiya
- the Transgenics Core Facility, University of Texas Medical Branch, Galveston, Texas 77555
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18
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Son SM, Park SJ, Lee H, Siddiqi F, Lee JE, Menzies FM, Rubinsztein DC. Leucine Signals to mTORC1 via Its Metabolite Acetyl-Coenzyme A. Cell Metab 2019; 29:192-201.e7. [PMID: 30197302 DOI: 10.1016/j.cmet.2018.08.013] [Citation(s) in RCA: 138] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 06/01/2018] [Accepted: 08/12/2018] [Indexed: 12/20/2022]
Abstract
The mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) is a master regulator of cell growth and metabolism. Leucine (Leu) activates mTORC1 and many have tried to identify the mechanisms whereby cells sense Leu in this context. Here we describe that the Leu metabolite acetyl-coenzyme A (AcCoA) positively regulates mTORC1 activity by EP300-mediated acetylation of the mTORC1 regulator, Raptor, at K1097. Leu metabolism and consequent mTORC1 activity are regulated by intermediary enzymes. As AcCoA is a Leu metabolite, this process directly correlates with Leu abundance, and does not require Leu sensing via intermediary proteins, as has been described previously. Importantly, we describe that this pathway regulates mTORC1 in a cell-type-specific manner. Finally, we observed decreased acetylated Raptor, and inhibited mTORC1 and EP300 activity in fasted mice tissues. These results provide a direct mechanism for mTORC1 regulation by Leu metabolism.
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van Vliet S, Smith GI, Porter L, Ramaswamy R, Reeds DN, Okunade AL, Yoshino J, Klein S, Mittendorfer B. The muscle anabolic effect of protein ingestion during a hyperinsulinaemic euglycaemic clamp in middle-aged women is not caused by leucine alone. J Physiol 2018; 596:4681-4692. [PMID: 30054913 DOI: 10.1113/jp276504] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/26/2018] [Indexed: 12/30/2022] Open
Abstract
KEY POINTS It has been suggested that leucine is primarily responsible for the increase in muscle protein synthesis after protein ingestion because leucine uniquely activates the mTOR-p70S6K signalling cascade. We compared the effects of ingesting protein or an amount of leucine equal to that in the protein during a hyperinsulinaemic-euglycaemic clamp (to eliminate potential confounding as a result of differences in the insulinogenic effect of protein and leucine ingestion) on muscle anabolic signalling and protein turnover in 28 women. We found that protein, but not leucine, ingestion increased muscle p-mTORSer2448 and p-p70S6KThr389 , although only protein, and not leucine, ingestion decreased muscle p-eIF2αSer51 and increased muscle protein synthesis. ABSTRACT It has been suggested that leucine is primarily responsible for the increase in muscle protein synthesis (MPS) after protein ingestion because leucine uniquely activates the mTOR-p70S6K signalling cascade. We tested this hypothesis by measuring muscle p-mTORSer2448 , p-p70S6KThr389 and p-eIF2αSer51 , as well as protein turnover (by stable isotope labelled amino acid tracer infusion in conjunction with leg arteriovenous blood and muscle tissue sampling), in 28 women who consumed either 0.45 g protein kg-1 fat-free mass (containing 0.0513 g leucine kg-1 fat-free mass) or a control drink (n = 14) or 0.0513 g leucine kg-1 fat-free mass or a control drink (n = 14) during a hyperinsulinaemic-euglycaemic clamp procedure (HECP). Compared to basal conditions, the HECP alone (without protein or leucine ingestion) suppressed muscle protein breakdown by ∼20% and increased p-mTORSer2448 and p-p70S6KThr389 by >50% (all P < 0.05) but had no effect on p-eIF2αSer51 and MPS. Both protein and leucine ingestion further increased p-mTORSer2448 and p-p70S6KThr389 , although only protein, and not leucine, ingestion decreased (by ∼35%) p-eIF2αSer51 and increased (by ∼100%) MPS (all P < 0.05). Accordingly, leg net protein balance changed from negative (loss) during basal conditions to equilibrium during the HECP alone and the HECP with concomitant leucine ingestion and to positive (gain) during the HECP with concomitant protein ingestion. These results provide new insights into the regulation of MPS by demonstrating that leucine and mTOR signalling alone are not responsible for the muscle anabolic effect of protein ingestion during physiological hyperinsulinaemia, most probably because they fail to signal to eIF2α to initiate translation and/or additional amino acids are needed to sustain translation.
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Affiliation(s)
| | | | | | - Raja Ramaswamy
- Department of Radiology, Washington University School of Medicine, St Louis, MO, USA
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Comesaña S, Velasco C, Conde-Sieira M, Míguez JM, Soengas JL, Morais S. Feeding Stimulation Ability and Central Effects of Intraperitoneal Treatment of L-Leucine, L-Valine, and L-Proline on Amino Acid Sensing Systems in Rainbow Trout: Implication in Food Intake Control. Front Physiol 2018; 9:1209. [PMID: 30210366 PMCID: PMC6121200 DOI: 10.3389/fphys.2018.01209] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/13/2018] [Indexed: 12/13/2022] Open
Abstract
To continue gathering knowledge on the central regulation of food intake in response to amino acids in teleost fish, using as a model rainbow trout (Oncorhynchus mykiss), we evaluated in a first experiment the feeding attractiveness of L-leucine, L-valine, and L-proline offered as an agar gel matrix. In a second experiment, we assessed the effect of intraperitoneal (IP) treatment with the same amino acids on food intake. In a third experiment, we carried out a similar IP administration of amino acids to evaluate the response of amino acid sensing mechanisms in the hypothalamus and telencephalon. Results are discussed in conjunction with an earlier study where leucine and valine were administered intracerebroventricularly (ICV). The attractiveness of amino acids does not appear to relate to their effects on food intake, at least when administrated by-passing ingestion and luminal absorption, since two attractive amino acids resulted in an anorexigenic (Leu) or no effects (Pro) on food intake while a non-attractive amino acid (Val) induced anorexigenic (IP treatment) or orexigenic (ICV treatment) responses. The effects of Leu on food intake might relate to the expression of hypothalamic neuropeptides and result from the direct activation of amino acid sensing systems. In contrast, while valine had few effects on hypothalamic amino acid sensing systems after ICV treatment, a significant amount of parameters become affected by IP treatment suggesting that the effect of Val after IP treatment is indirect. Proline had no relevant effects on amino acid sensing systems, neuropeptide expression, and food intake, which suggest that this amino acid might not have a relevant role in the homeostatic regulation of food intake through hypothalamic mechanisms. In telencephalon, the same amino acid sensing systems operating in hypothalamus appear to be present and respond to Leu and Val, but it is still unclear how they might relate to the control of food intake.
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Affiliation(s)
- Sara Comesaña
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
| | - Cristina Velasco
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
| | - Marta Conde-Sieira
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
| | - Jesús M Míguez
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
| | - José L Soengas
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
| | - Sofía Morais
- Lucta S.A., Innovation Division, UAB Research Park, Bellaterra, Spain
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Rodionova IA, Goodacre N, Do J, Hosseinnia A, Babu M, Uetz P, Saier MH. The uridylyltransferase GlnD and tRNA modification GTPase MnmE allosterically control Escherichia coli folylpoly-γ-glutamate synthase FolC. J Biol Chem 2018; 293:15725-15732. [PMID: 30089654 DOI: 10.1074/jbc.ra118.004425] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 07/31/2018] [Indexed: 01/20/2023] Open
Abstract
Folate derivatives are important cofactors for enzymes in several metabolic processes. Folate-related inhibition and resistance mechanisms in bacteria are potential targets for antimicrobial therapies and therefore a significant focus of current research. Here, we report that the activity of Escherichia coli poly-γ-glutamyl tetrahydrofolate/dihydrofolate synthase (FolC) is regulated by glutamate/glutamine-sensing uridylyltransferase (GlnD), THF-dependent tRNA modification enzyme (MnmE), and UDP-glucose dehydrogenase (Ugd) as shown by direct in vitro protein-protein interactions. Using kinetics analyses, we observed that GlnD, Ugd, and MnmE activate FolC many-fold by decreasing the K half of FolC for its substrate l-glutamate. Moreover, FolC inhibited the GTPase activity of MnmE at low GTP concentrations. The growth phenotypes associated with these proteins are discussed. These results, obtained using direct in vitro enzyme assays, reveal unanticipated networks of allosteric regulatory interactions in the folate pathway in E. coli and indicate regulation of polyglutamylated tetrahydrofolate biosynthesis by the availability of nitrogen sources, signaled by the glutamine-sensing GlnD protein.
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Affiliation(s)
- Irina A Rodionova
- From the Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116,
| | - Norman Goodacre
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284, and
| | - Jimmy Do
- From the Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116
| | - Ali Hosseinnia
- Department of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Mohan Babu
- Department of Biochemistry, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Peter Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia 23284, and
| | - Milton H Saier
- From the Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116,
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Hoffmann TM, Cwiklinski E, Shah DS, Stretton C, Hyde R, Taylor PM, Hundal HS. Effects of Sodium and Amino Acid Substrate Availability upon the Expression and Stability of the SNAT2 (SLC38A2) Amino Acid Transporter. Front Pharmacol 2018; 9:63. [PMID: 29467657 PMCID: PMC5808304 DOI: 10.3389/fphar.2018.00063] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/17/2018] [Indexed: 12/14/2022] Open
Abstract
The SNAT2 (SLC38A2) System A amino acid transporter mediates Na+-coupled cellular uptake of small neutral α-amino acids (AAs) and is extensively regulated in response to humoral and nutritional cues. Understanding the basis of such regulation is important given that AA uptake via SNAT2 has been linked to activation of mTORC1; a major controller of many important cellular processes including, for example, mRNA translation, lipid synthesis, and autophagy and whose dysregulation has been implicated in the development of cancer and conditions such as obesity and type 2 diabetes. Extracellular AA withdrawal induces an adaptive upregulation of SNAT2 gene transcription and SNAT2 protein stability but, as yet, the sensing mechanism(s) that initiate this response remain poorly understood although interactions between SNAT2 and its substrates may play a vital role. Herein, we have explored how changes in substrate (AA and Na+) availability impact upon the adaptive regulation of SNAT2 in HeLa cells. We show that while AA deprivation induces SNAT2 gene expression, this induction was not apparent if extracellular Na+ was removed during the AA withdrawal period. Furthermore, we show that the increase in SNAT2 protein stability associated with AA withdrawal is selectively repressed by provision of SNAT2 AA substrates (N-methylaminoisobutyric acid and glutamine), but not non-substrates. This stabilization and substrate-induced repression were critically dependent upon the cytoplasmic N-terminal tail of SNAT2 (containing lysyl residues which are putative targets of the ubiquitin-proteasome system), because “grafting” this tail onto SNAT5, a related SLC38 family member that does not exhibit adaptive regulation, confers substrate-induced changes in stability of the SNAT2-5 chimeric transporter. In contrast, expression of SNAT2 in which the N-terminal lysyl residues were mutated to alanine rendered the transporter stable and insensitive to substrate-induced changes in protein stability. Intriguingly, SNAT2 protein stability was dramatically reduced in the absence of extracellular Na+ irrespective of whether substrate AAs were present or absent. Our findings indicate that the presence of extracellular Na+ (and potentially its binding to SNAT2) may be crucial for not only sensing SNAT2 AA occupancy and consequently for initiating the adaptive response under AA insufficient conditions, but for enabling substrate-induced changes in SNAT2 protein stability.
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Affiliation(s)
- Thorsten M Hoffmann
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Emma Cwiklinski
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Dinesh S Shah
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Clare Stretton
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Russell Hyde
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Peter M Taylor
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Harinder S Hundal
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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23
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He XD, Gong W, Zhang JN, Nie J, Yao CF, Guo FS, Lin Y, Wu XH, Li F, Li J, Sun WC, Wang ED, An YP, Tang HR, Yan GQ, Yang PY, Wei Y, Mao YZ, Lin PC, Zhao JY, Xu Y, Xu W, Zhao SM. Sensing and Transmitting Intracellular Amino Acid Signals through Reversible Lysine Aminoacylations. Cell Metab 2018; 27:151-166.e6. [PMID: 29198988 DOI: 10.1016/j.cmet.2017.10.015] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/17/2017] [Accepted: 10/26/2017] [Indexed: 02/05/2023]
Abstract
Amino acids are known regulators of cellular signaling and physiology, but how they are sensed intracellularly is not fully understood. Herein, we report that each aminoacyl-tRNA synthetase (ARS) senses its cognate amino acid sufficiency through catalyzing the formation of lysine aminoacylation (K-AA) on its specific substrate proteins. At physiologic levels, amino acids promote ARSs bound to their substrates and form K-AAs on the ɛ-amine of lysines in their substrates by producing reactive aminoacyl adenylates. The K-AA marks can be removed by deacetylases, such as SIRT1 and SIRT3, employing the same mechanism as that involved in deacetylation. These dynamically regulated K-AAs transduce signals of their respective amino acids. Reversible leucylation on ras-related GTP-binding protein A/B regulates activity of the mammalian target of rapamycin complex 1. Glutaminylation on apoptosis signal-regulating kinase 1 suppresses apoptosis. We discovered non-canonical functions of ARSs and revealed systematic and functional amino acid sensing and signal transduction networks.
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Affiliation(s)
- Xia-Di He
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Wei Gong
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Fudan University Shanghai Cancer Center, Fudan University, Shanghai 200032, PRC
| | - Jia-Nong Zhang
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Ji Nie
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Cui-Fang Yao
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Fu-Shen Guo
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Yan Lin
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Xiao-Hui Wu
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Institute of Developmental Biology and Molecular Medicine, Fudan University, Shanghai 200032, PRC
| | - Feng Li
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Jie Li
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Fudan University Shanghai Cancer Center, Fudan University, Shanghai 200032, PRC
| | - Wei-Cheng Sun
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - En-Duo Wang
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - Yan-Peng An
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Hui-Ru Tang
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Guo-Quan Yan
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC
| | - Peng-Yuan Yang
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC
| | - Yun Wei
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Yun-Zi Mao
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Peng-Cheng Lin
- Key Laboratory for Tibet Plateau Phytochemistry of Qinghai Province, College of Pharmacy, Qinghai University for Nationalities, Xining 810007, PRC
| | - Jian-Yuan Zhao
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Yanhui Xu
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Fudan University Shanghai Cancer Center, Fudan University, Shanghai 200032, PRC; CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, PRC.
| | - Wei Xu
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC.
| | - Shi-Min Zhao
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC.
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Battu S, Minhas G, Mishra A, Khan N. Amino Acid Sensing via General Control Nonderepressible-2 Kinase and Immunological Programming. Front Immunol 2017; 8:1719. [PMID: 29321774 PMCID: PMC5732134 DOI: 10.3389/fimmu.2017.01719] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/21/2017] [Indexed: 12/16/2022] Open
Abstract
Metabolic adaptation to the changing nutrient levels in the cellular microenvironment plays a decisive role in the maintenance of homeostasis. Eukaryotic cells are equipped with nutrient sensors, which sense the fluctuating nutrients levels and accordingly program the cellular machinery to mount an appropriate response. Nutrients including amino acids play a vital role in maintaining cellular homeostasis. Therefore, over the evolution, different species have developed diverse mechanisms to detect amino acids abundance or scarcity. Immune responses have been known to be closely associated with the cellular metabolism especially amino acid sensing pathway, which influences innate as well as adaptive immune-effector functions. Thus, exploring the cross-talk between amino acid sensing mechanisms and immune responses in disease as well as in normal physiological conditions might open up avenues to explore how this association can be exploited to tailor immunological functions toward the design of better therapeutics for controlling metabolic diseases. In this review, we discuss the advances in the knowledge of various amino acid sensing pathways including general control nonderepressible-2 kinase in the control of inflammation and metabolic diseases.
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Affiliation(s)
- Srikanth Battu
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Gillipsie Minhas
- Department of Biomedical Engineering, IIT Hyderabad, Hyderabad, India
| | - Aman Mishra
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Nooruddin Khan
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
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25
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Wyant GA, Abu-Remaileh M, Wolfson RL, Chen WW, Freinkman E, Danai LV, Vander Heiden MG, Sabatini DM. mTORC1 Activator SLC38A9 Is Required to Efflux Essential Amino Acids from Lysosomes and Use Protein as a Nutrient. Cell 2017; 171:642-654.e12. [PMID: 29053970 DOI: 10.1016/j.cell.2017.09.046] [Citation(s) in RCA: 293] [Impact Index Per Article: 41.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 07/18/2017] [Accepted: 09/25/2017] [Indexed: 12/17/2022]
Abstract
The mTORC1 kinase is a master growth regulator that senses many environmental cues, including amino acids. Activation of mTORC1 by arginine requires SLC38A9, a poorly understood lysosomal membrane protein with homology to amino acid transporters. Here, we validate that SLC38A9 is an arginine sensor for the mTORC1 pathway, and we uncover an unexpectedly central role for SLC38A9 in amino acid homeostasis. SLC38A9 mediates the transport, in an arginine-regulated fashion, of many essential amino acids out of lysosomes, including leucine, which mTORC1 senses through the cytosolic Sestrin proteins. SLC38A9 is necessary for leucine generated via lysosomal proteolysis to exit lysosomes and activate mTORC1. Pancreatic cancer cells, which use macropinocytosed protein as a nutrient source, require SLC38A9 to form tumors. Thus, through SLC38A9, arginine serves as a lysosomal messenger that couples mTORC1 activation to the release from lysosomes of the essential amino acids needed to drive cell growth.
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Affiliation(s)
- Gregory A Wyant
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, 7 Cambridge Center, Cambridge, MA 02142, USA
| | - Monther Abu-Remaileh
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, 7 Cambridge Center, Cambridge, MA 02142, USA
| | - Rachel L Wolfson
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, 7 Cambridge Center, Cambridge, MA 02142, USA; Harvard Medical School M.D.-Ph.D. Program, Daniel C. Tosteson Medical Education Center, 260 Longwood Avenue, Boston, MA 02115, USA
| | - Walter W Chen
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, 7 Cambridge Center, Cambridge, MA 02142, USA; Harvard Medical School M.D.-Ph.D. Program, Daniel C. Tosteson Medical Education Center, 260 Longwood Avenue, Boston, MA 02115, USA
| | - Elizaveta Freinkman
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - Laura V Danai
- Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Matthew G Vander Heiden
- Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, 7 Cambridge Center, Cambridge, MA 02142, USA; Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, 7 Cambridge Center, Cambridge, MA 02142, USA.
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26
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Shen K, Choe A, Sabatini DM. Intersubunit Crosstalk in the Rag GTPase Heterodimer Enables mTORC1 to Respond Rapidly to Amino Acid Availability. Mol Cell 2017; 68:552-565.e8. [PMID: 29056322 DOI: 10.1016/j.molcel.2017.09.026] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 08/14/2017] [Accepted: 09/19/2017] [Indexed: 01/03/2023]
Abstract
mTOR complex I (mTORC1) is a central growth regulator that senses amino acids through a pathway that converges on the Rag GTPases, an obligate heterodimer of two related GTPases. Despite their central role in amino acid sensing, it is unknown why the Rag GTPases are heterodimeric and whether their subunits communicate with each other. Here, we find that the binding of guanosine triphosphate (GTP) to one subunit inhibits the binding and induces the hydrolysis of GTP by the other. This intersubunit communication pushes the Rag GTPases into either of two stable configurations, which represent active "on" or "off" states that interconvert via transient intermediates. Subunit coupling confers on the mTORC1 pathway its capacity to respond rapidly to the amino acid level. Thus, the dynamic response of mTORC1 requires intersubunit communication by the Rag GTPases, providing a rationale for why they exist as a dimer and revealing a distinct mode of control for a GTP-binding protein.
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Affiliation(s)
- Kuang Shen
- 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; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge, MA 02142, USA
| | - Abigail Choe
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, 9 Cambridge Center, Cambridge, MA 02142, 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; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge, MA 02142, USA.
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27
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Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth that responds to a diverse set of environmental inputs, including amino acids. Over the past 10 years, a number of proteins have been identified that help transmit amino acid availability to mTORC1. However, amino acid sensors for this pathway have only recently been discovered. Here, we review these recent advances and highlight the variety of unexplored questions that emerge from the identification of these sensors.
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Affiliation(s)
- Rachel L Wolfson
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research at MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute, 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, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research at MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute, 415 Main Street, Cambridge, MA 02142, USA.
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28
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Hoxhaj G, Caddye E, Najafov A, Houde VP, Johnson C, Dissanayake K, Toth R, Campbell DG, Prescott AR, MacKintosh C. The E3 ubiquitin ligase ZNRF2 is a substrate of mTORC1 and regulates its activation by amino acids. eLife 2016; 5. [PMID: 27244671 PMCID: PMC4889327 DOI: 10.7554/elife.12278] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 03/28/2016] [Indexed: 12/22/2022] Open
Abstract
The mechanistic Target of Rapamycin complex 1 (mTORC1) senses intracellular amino acid levels through an intricate machinery, which includes the Rag GTPases, Ragulator and vacuolar ATPase (V-ATPase). The membrane-associated E3 ubiquitin ligase ZNRF2 is released into the cytosol upon its phosphorylation by Akt. In this study, we show that ZNRF2 interacts with mTOR on membranes, promoting the amino acid-stimulated translocation of mTORC1 to lysosomes and its activation in human cells. ZNRF2 also interacts with the V-ATPase and preserves lysosomal acidity. Moreover, knockdown of ZNRF2 decreases cell size and cell proliferation. Upon growth factor and amino acid stimulation, mTORC1 phosphorylates ZNRF2 on Ser145, and this phosphosite is dephosphorylated by protein phosphatase 6. Ser145 phosphorylation stimulates vesicle-to-cytosol translocation of ZNRF2 and forms a novel negative feedback on mTORC1. Our findings uncover ZNRF2 as a component of the amino acid sensing machinery that acts upstream of Rag-GTPases and the V-ATPase to activate mTORC1. DOI:http://dx.doi.org/10.7554/eLife.12278.001 During digestion, proteins are broken down into their constituent parts called amino acids. Amino acids are transported in the bloodstream and are used to build up new cells and repair old ones. Optimal regulation of the cellular rates of amino acid uptake and protein synthesis is critical to the overall health of our bodies. Inside each of our cells is a molecule called mammalian target of rapamycin (mTOR for short), which acts as a controller that receives information about amino acid availability. mTOR also senses how much of each amino acid the cell needs and calibrates the cell’s amino acid uptake and protein synthesis machineries accordingly. When investigating an enzyme named ZNRF2, Hoxhaj et al. discovered that it interacts with mTOR on membranes inside cells. This raised questions about how ZNRF2 might work with mTOR to sense amino acid supplies and regulate cell growth. Hoxhaj et al. found that when cells are provided with amino acids and growth-stimulating hormones, mTOR is activated and attaches a phosphate group to ZNRF2. This chemical modification promotes the release of ZNRF2 from membranes so that ZNRF2 separates from mTOR. In contrast, when cells are starved of amino acids, this phosphate group is removed from ZNRF2, which then returns to the membranes. On membranes, ZNRF2 also influences the activity of a pump called V-ATPase, which controls the internal acidity of the membrane-enclosed vesicles named lysosomes that help to recycle amino acids inside cells. The action of ZNRF2 on the pump may help to prime mTOR so that it is ready to sense amino acids. These findings by Hoxhaj et al. suggest that ZNRF2 and mTOR may ‘tune’ each other, making constant to-and-fro adjustments to help ensure that levels of amino acid uptake and cell growth are set just right. However, many questions about ZNRF2 still remain to be addressed. For example, are genetic mutations in ZNRF2 involved in cancers, developmental disorders or growth syndromes? Is ZNRF2 most important in the brain, where it is particularly abundant? And how does ZNRF2 affect acidity within the lysosomes? DOI:http://dx.doi.org/10.7554/eLife.12278.002
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Affiliation(s)
- Gerta Hoxhaj
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, United States
| | - Edward Caddye
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Ayaz Najafov
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Vanessa P Houde
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Catherine Johnson
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Kumara Dissanayake
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Cell and Developmental Biology Division, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Rachel Toth
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - David G Campbell
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Alan R Prescott
- Cell Signalling and Immunology Division, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Carol MacKintosh
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Cell and Developmental Biology Division, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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29
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Robertson LT, Treviño-Villarreal JH, Mejia P, Grondin Y, Harputlugil E, Hine C, Vargas D, Zheng H, Ozaki CK, Kristal BS, Simpson SJ, Mitchell JR. Protein and Calorie Restriction Contribute Additively to Protection from Renal Ischemia Reperfusion Injury Partly via Leptin Reduction in Male Mice. J Nutr 2015; 145:1717-27. [PMID: 26041674 PMCID: PMC4516761 DOI: 10.3945/jn.114.199380] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 05/15/2015] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Short-term dietary restriction (DR) without malnutrition preconditions against surgical stress in rodents; however, the nutritional basis and underlying nutrient/energy-sensing pathways remain poorly understood. OBJECTIVES We investigated the relative contribution of protein restriction (PR) vs. calorie restriction (CR) to protection from renal ischemia reperfusion injury (IRI) and changes in organ-autonomous nutrient/energy-sensing pathways and hormones underlying beneficial effects. METHODS Mice were preconditioned on experimental diets lacking total calories (0-50% CR) or protein/essential amino acids (EAAs) vs. complete diets consumed ad libitum (AL) for 1 wk before IRI. Renal outcome was assessed by serum markers and histology and integrated over a 2-dimensional protein/energy landscape by geometric framework analysis. Changes in renal nutrient/energy-sensing signal transduction and systemic hormones leptin and adiponectin were also measured. The genetic requirement for amino acid sensing via general control non-derepressible 2 (GCN2) was tested with knockout vs. control mice. The involvement of the hormone leptin was tested by injection of recombinant protein vs. vehicle during the preconditioning period. RESULTS CR-mediated protection was dose dependent up to 50% with maximal 2-fold effect sizes. PR benefits were abrogated by EAA re-addition and additive with CR, with maximal benefits at any given amount of CR occurring with a protein-free diet. GCN2 was not required for functional benefits of PR. Activation and repression of nutrient/energy-sensing kinases, AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin complex 1 (mTORC1), respectively, on PR reflected a state of negative energy balance, paralleled by 13% weight loss and an 87% decrease in leptin, independent of calorie intake. Recombinant leptin administration partially abrogated benefits of dietary preconditioning against renal IRI. CONCLUSIONS In male mice, PR and CR both contributed to the benefits of short-term DR against renal IRI independent of GCN2 but partially dependent on reduced circulating leptin and coincident with AMPK activation and mTORC1 repression.
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Affiliation(s)
| | | | - Pedro Mejia
- Departments of Genetics and Complex Diseases and
| | - Yohann Grondin
- Environmental Health, Harvard School of Public Health, Boston, MA
| | | | | | | | | | | | - Bruce S Kristal
- Neurosurgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA; and
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30
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Clemmensen C, Smajilovic S, Wellendorph P, Bräuner-Osborne H. The GPCR, class C, group 6, subtype A (GPRC6A) receptor: from cloning to physiological function. Br J Pharmacol 2014; 171:1129-41. [PMID: 24032653 DOI: 10.1111/bph.12365] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 07/25/2013] [Accepted: 08/26/2013] [Indexed: 12/16/2022] Open
Abstract
GPRC6A (GPCR, class C, group 6, subtype A) is a class C GPCR that has been cloned from human, mouse and rat. Several groups have shown that the receptor is activated by a range of basic and small aliphatic L-α-amino acids of which L-arginine, L-lysine and L-ornithine are the most potent compounds with EC50 values in the mid-micromolar range. In addition, several groups have shown that the receptor is either directly activated or positively modulated by divalent cations such as Ca(2+) albeit in concentrations above 5 mM, which is above the physiological concentration in most tissues. More recently, the peptide osteocalcin and the steroid testosterone have also been suggested to be endogenous GPRC6A agonists. The receptor is widely expressed in all three species which, along with the omnipresence of the amino acids and divalent cation ligands, suggest that the receptor could be involved in a broad range of physiological functions. So far, this has mainly been addressed by analyses of genetically modified mice where the GPRC6A receptor has been ablated. Although there has been some discrepancies among results reported from different groups, there is increasing evidence that the receptor is involved in regulation of inflammation, metabolism and endocrine functions. GPRC6A could thus be an interesting target for new drugs in these therapeutic areas.
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Affiliation(s)
- C Clemmensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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31
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Abstract
The mechanistic target of rapamycin complex I (mTORC1) is a central regulator of cellular and organismal growth, and hyperactivation of this pathway is implicated in the pathogenesis of many human diseases including cancer and diabetes. mTORC1 promotes growth in response to the availability of nutrients, such as amino acids, which drive mTORC1 to the lysosomal surface, its site of activation. How amino acid levels are communicated to mTORC1 is only recently coming to light by the discovery of a lysosome-based signaling system composed of Rags (Ras-related GTPases) and Ragulator v-ATPase, GATOR (GAP activity towards Rags), and folliculin (FLCN) complexes. Increased understanding of this pathway will not only provide insight into growth control but also into the human pathologies triggered by its deregulation.
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Affiliation(s)
- Liron Bar-Peled
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, Nine Cambridge Center, Cambridge, MA 02142, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge, Cambridge MA 02142, USA.
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Ghosh S, Wanders D, Stone KP, Van NT, Cortez CC, Gettys TW. A systems biology analysis of the unique and overlapping transcriptional responses to caloric restriction and dietary methionine restriction in rats. FASEB J 2014; 28:2577-90. [PMID: 24571921 DOI: 10.1096/fj.14-249458] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Dietary methionine restriction (MR) and calorie restriction (CR) each improve metabolic health and extend life span. We used comprehensive transcriptome profiling and systems biology analysis to interrogate the unique and overlapping molecular responses in rats provided these dietary regimens for 20 mo after weaning. Microarray analysis was conducted on inguinal white adipose (IWAT), brown adipose tissue (BAT), liver, and skeletal muscle. Compared to controls, CR-induced transcriptomic responses (absolute fold change ≥1.5 and P≤0.05) were comparable in IWAT, BAT, and liver (~800 genes). MR-induced effects were largely restricted to IWAT and liver (~2400 genes). Pathway enrichment and gene-coexpression analyses showed that induction of fatty acid synthesis in IWAT was common to CR and MR, whereas immunity and proinflammatory signaling pathways were specifically down-regulated in MR-treated IWAT and liver (FDR≤0.07-0.3). BAT demonstrated consistent down-regulation of PPAR-signaling under CR and MR, whereas muscle was largely unaffected. Interactome analysis identified CR-specific down-regulation of cytoskeletal matrix components in IWAT and MR-specific up-regulation of ribosomal genes in liver (FDR≤0.001). Transcriptomic down-regulation of inflammation genes by MR in IWAT was consistent with upstream inhibition of STAT3. Together, these results provide an integrated picture of the breadth of transcriptional responses to MR and CR among key metabolic tissues.
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Affiliation(s)
- Sujoy Ghosh
- Laboratory of Computational Biology and Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA; and Cardiovascular and Metabolic Disorders Research Program, Duke-National University of Singapore Graduate Medical School, Singapore
| | - Desiree Wanders
- Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA; and
| | - Kirsten P Stone
- Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA; and
| | - Nancy T Van
- Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA; and
| | - Cory C Cortez
- Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA; and
| | - Thomas W Gettys
- Laboratory of Computational Biology and Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA; and
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Wanders D, Ghosh S, Stone KP, Van NT, Gettys TW. Transcriptional impact of dietary methionine restriction on systemic inflammation: relevance to biomarkers of metabolic disease during aging. Biofactors 2014; 40:13-26. [PMID: 23813805 PMCID: PMC3796060 DOI: 10.1002/biof.1111] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 04/15/2013] [Accepted: 04/25/2013] [Indexed: 02/06/2023]
Abstract
Calorie restriction (CR) without malnutrition increases lifespan and produces significant improvements in biomarkers of metabolic health. The improvements are attributable in part to effects of CR on energy balance, which limit fat accumulation by restricting energy intake. Normal age-associated increases in adiposity and insulin resistance are associated with development of a systemic proinflammatory state, while chronic CR limits fat deposition and expression of inflammatory markers. Dietary methionine restriction (MR) has emerged as an effective CR mimetic because it produces a comparable extension in lifespan. MR also reduces adiposity through a compensatory increase in energy expenditure that effectively limits fat accumulation, but essentially nothing is known about the effects of MR on systemic inflammation. Here, we review the relationships between these two interventions and discuss their transcriptional impact. In addition, using tissues from rats after long-term consumption of CR or MR diets, transcriptional profiling was used to examine retrospectively the systems biology of 59 networks of molecules annotated to inflammation. Transcriptional effects of both diets occurred primarily in white adipose tissue and liver, and the responses to MR were far more robust than those to CR. The primary transcriptional targets of MR in both liver and white adipose tissue were phagocytes and macrophages, where expression of genes associated with immune cell infiltration and quantity was reduced. These findings support the conclusion that anti-inflammatory responses produced by CR and MR are not strictly dependent upon reduced adiposity but are significantly influenced by the metabolic mechanisms through which energy balance is altered.
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Affiliation(s)
- Desiree Wanders
- Laboratories of Nutrient Sensing and Adipocyte Signaling, Baton Rouge, LA
| | - Sujoy Ghosh
- Computational Biology Pennington Biomedical Research Center, Baton Rouge, LA
| | - Kirsten P. Stone
- Laboratories of Nutrient Sensing and Adipocyte Signaling, Baton Rouge, LA
| | - Nancy T. Van
- Laboratories of Nutrient Sensing and Adipocyte Signaling, Baton Rouge, LA
| | - Thomas W. Gettys
- Laboratories of Nutrient Sensing and Adipocyte Signaling, Baton Rouge, LA
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Liou AP, Sei Y, Zhao X, Feng J, Lu X, Thomas C, Pechhold S, Raybould HE, Wank SA. The extracellular calcium-sensing receptor is required for cholecystokinin secretion in response to L-phenylalanine in acutely isolated intestinal I cells. Am J Physiol Gastrointest Liver Physiol 2011; 300:G538-46. [PMID: 21252045 PMCID: PMC3074990 DOI: 10.1152/ajpgi.00342.2010] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The extracellular calcium-sensing receptor (CaSR) has recently been recognized as an L-amino acid sensor and has been implicated in mediating cholecystokinin (CCK) secretion in response to aromatic amino acids. We investigated whether direct detection of L-phenylalanine (L-Phe) by CaSR results in CCK secretion in the native I cell. Fluorescence-activated cell sorting of duodenal I cells from CCK-enhanced green fluorescent protein (eGFP) transgenic mice demonstrated CaSR gene expression. Immunostaining of fixed and fresh duodenal tissue sections confirmed CaSR protein expression. Intracellular calcium fluxes were CaSR dependent, stereoselective for L-Phe over D-Phe, and responsive to type II calcimimetic cinacalcet in CCK-eGFP cells. Additionally, CCK secretion by an isolated I cell population was increased by 30 and 62% in response to L-Phe in the presence of physiological (1.26 mM) and superphysiological (2.5 mM) extracellular calcium concentrations, respectively. While the deletion of CaSR from CCK-eGFP cells did not affect basal CCK secretion, the effect of L-Phe or cinacalcet on intracellular calcium flux was lost. In fact, both secretagogues, as well as superphysiological Ca(2+), evoked an unexpected 20-30% decrease in CCK secretion compared with basal secretion in CaSR(-/-) CCK-eGFP cells. CCK secretion in response to KCl or tryptone was unaffected by the absence of CaSR. The present data suggest that CaSR is required for hormone secretion in the specific response to L-Phe by the native I cell, and that a receptor-mediated mechanism may inhibit hormone secretion in the absence of a fully functional CaSR.
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Affiliation(s)
- Alice P. Liou
- 1Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland; ,2School of Veterinary Medicine, Department of Anatomy, Physiology, and Cell Biology, University of California, Davis, Davis, California; and
| | - Yoshitatsu Sei
- 1Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland;
| | - Xilin Zhao
- 1Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland;
| | - Jianying Feng
- 1Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland;
| | - Xinping Lu
- 1Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland;
| | - Craig Thomas
- 3Chemical Genomics Center, National Human Genome Research Institute, and
| | - Susanne Pechhold
- 4Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Helen E. Raybould
- 2School of Veterinary Medicine, Department of Anatomy, Physiology, and Cell Biology, University of California, Davis, Davis, California; and
| | - Stephen A. Wank
- 1Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland;
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