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Rahman M, Nguyen TM, Lee GJ, Kim B, Park MK, Lee CH. Unraveling the Role of Ras Homolog Enriched in Brain (Rheb1 and Rheb2): Bridging Neuronal Dynamics and Cancer Pathogenesis through Mechanistic Target of Rapamycin Signaling. Int J Mol Sci 2024; 25:1489. [PMID: 38338768 PMCID: PMC10855792 DOI: 10.3390/ijms25031489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/14/2024] [Accepted: 01/17/2024] [Indexed: 02/12/2024] Open
Abstract
Ras homolog enriched in brain (Rheb1 and Rheb2), small GTPases, play a crucial role in regulating neuronal activity and have gained attention for their implications in cancer development, particularly in breast cancer. This study delves into the intricate connection between the multifaceted functions of Rheb1 in neurons and cancer, with a specific focus on the mTOR pathway. It aims to elucidate Rheb1's involvement in pivotal cellular processes such as proliferation, apoptosis resistance, migration, invasion, metastasis, and inflammatory responses while acknowledging that Rheb2 has not been extensively studied. Despite the recognized associations, a comprehensive understanding of the intricate interplay between Rheb1 and Rheb2 and their roles in both nerve and cancer remains elusive. This review consolidates current knowledge regarding the impact of Rheb1 on cancer hallmarks and explores the potential of Rheb1 as a therapeutic target in cancer treatment. It emphasizes the necessity for a deeper comprehension of the molecular mechanisms underlying Rheb1-mediated oncogenic processes, underscoring the existing gaps in our understanding. Additionally, the review highlights the exploration of Rheb1 inhibitors as a promising avenue for cancer therapy. By shedding light on the complicated roles between Rheb1/Rheb2 and cancer, this study provides valuable insights to the scientific community. These insights are instrumental in guiding the identification of novel targets and advancing the development of effective therapeutic strategies for treating cancer.
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Affiliation(s)
- Mostafizur Rahman
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Tuan Minh Nguyen
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Gi Jeong Lee
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Boram Kim
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
| | - Mi Kyung Park
- Department of BioHealthcare, Hwasung Medi-Science University, Hwaseong-si 18274, Republic of Korea
| | - Chang Hoon Lee
- College of Pharmacy, Dongguk University, Seoul 04620, Republic of Korea; (M.R.); (G.J.L.)
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2
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Tei R, Bagde SR, Fromme JC, Baskin JM. Activity-based directed evolution of a membrane editor in mammalian cells. Nat Chem 2023; 15:1030-1039. [PMID: 37217787 PMCID: PMC10525039 DOI: 10.1038/s41557-023-01214-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 04/24/2023] [Indexed: 05/24/2023]
Abstract
Cellular membranes contain numerous lipid species, and efforts to understand the biological functions of individual lipids have been stymied by a lack of approaches for controlled modulation of membrane composition in situ. Here we present a strategy for editing phospholipids, the most abundant lipids in biological membranes. Our membrane editor is based on a bacterial phospholipase D (PLD), which exchanges phospholipid head groups through hydrolysis or transphosphatidylation of phosphatidylcholine with water or exogenous alcohols. Exploiting activity-dependent directed enzyme evolution in mammalian cells, we have developed and structurally characterized a family of 'superPLDs' with up to a 100-fold enhancement in intracellular activity. We demonstrate the utility of superPLDs for both optogenetics-enabled editing of phospholipids within specific organelle membranes in live cells and biocatalytic synthesis of natural and unnatural designer phospholipids in vitro. Beyond the superPLDs, activity-based directed enzyme evolution in mammalian cells is a generalizable approach to engineer additional chemoenzymatic biomolecule editors.
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Affiliation(s)
- Reika Tei
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Saket R Bagde
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - J Christopher Fromme
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Jeremy M Baskin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA.
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3
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Frias MA, Hatipoglu A, Foster DA. Regulation of mTOR by phosphatidic acid. Trends Endocrinol Metab 2023; 34:170-180. [PMID: 36732094 PMCID: PMC9957947 DOI: 10.1016/j.tem.2023.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 01/03/2023] [Indexed: 02/03/2023]
Abstract
mTORC1, the mammalian target of rapamycin complex 1, is a key regulator of cellular physiology. The lipid metabolite phosphatidic acid (PA) binds to and activates mTORC1 in response to nutrients and growth factors. We review structural findings and propose a model for PA activation of mTORC1. PA binds to a highly conserved sequence in the α4 helix of the FK506 binding protein 12 (FKBP12)/rapamycin-binding (FRB) domain of mTOR. It is proposed that PA binding to two adjacent positively charged amino acids breaks and shortens the C-terminal region of helix α4. This has profound consequences for both substrate binding and the catalytic activity of mTORC1.
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Affiliation(s)
- Maria A Frias
- Department of Biology and Health Promotion, St. Francis College, Brooklyn, NY 11201, USA; Department of Biological Sciences, Hunter College of the City University of New York, New York, NY 10065, USA.
| | - Ahmet Hatipoglu
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY 10065, USA; Biochemistry Program, Graduate Center of the City University of New York, New York, NY 10016, USA
| | - David A Foster
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY 10065, USA; Biochemistry Program, Graduate Center of the City University of New York, New York, NY 10016, USA; Biology Program, Graduate Center of the City University of New York, New York, NY 10016, USA; Department of Pharmacology, Weill Cornell Medicine, New York, NY 10021, USA.
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4
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Abou Daher A, Alkhansa S, Azar WS, Rafeh R, Ghadieh HE, Eid AA. Translational Aspects of the Mammalian Target of Rapamycin Complexes in Diabetic Nephropathy. Antioxid Redox Signal 2022; 37:802-819. [PMID: 34544257 DOI: 10.1089/ars.2021.0217] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Significance: Despite the many efforts put into understanding diabetic nephropathy (DN), direct treatments for DN have yet to be discovered. Understanding the mechanisms behind DN is an essential step in the development of novel therapeutic regimens. The mammalian target of rapamycin (mTOR) pathway has emerged as an important candidate in the quest for drug discovery because of its role in regulating growth, proliferation, as well as protein and lipid metabolism. Recent Advances: Kidney cells have been found to rely on basal autophagy for survival and for conserving kidney integrity. Recent studies have shown that diabetes induces renal autophagy deregulation, leading to kidney injury. Hyper-activation of the mTOR pathway and oxidative stress have been suggested to play a role in diabetes-induced autophagy imbalance. Critical Issues: A detailed understanding of the role of mTOR signaling in diabetes-associated complications is of major importance in the search for a cure. In this review, we provide evidence that mTOR is heavily implicated in diabetes-induced kidney injury. We suggest possible mechanisms through which mTOR exerts its negative effects by increasing insulin resistance, upregulating oxidative stress, and inhibiting autophagy. Future Directions: Both increased oxidative stress and autophagy deregulation are deeply embedded in DN. However, the mechanisms controlling oxidative stress and autophagy are not well understood. Although Akt/mTOR signaling seems to play an important role in oxidative stress and autophagy, further investigation is required to uncover the details of this signaling pathway. Antioxid. Redox Signal. 37, 802-819.
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Affiliation(s)
- Alaa Abou Daher
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
| | - Sahar Alkhansa
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,AUB Diabetes, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
| | - William S Azar
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,AUB Diabetes, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,Department of Physiology and Biophysics, Georgetown University Medical School, Washington, District of Columbia, USA
| | - Rim Rafeh
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,AUB Diabetes, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
| | - Hilda E Ghadieh
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,AUB Diabetes, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
| | - Assaad A Eid
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon.,AUB Diabetes, Faculty of Medicine and Medical Center, American University of Beirut, Beirut, Lebanon
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5
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Wang G, Chen L, Qin S, Zhang T, Yao J, Yi Y, Deng L. Mechanistic Target of Rapamycin Complex 1: From a Nutrient Sensor to a Key Regulator of Metabolism and Health. Adv Nutr 2022; 13:1882-1900. [PMID: 35561748 PMCID: PMC9526850 DOI: 10.1093/advances/nmac055] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 04/26/2022] [Accepted: 05/09/2022] [Indexed: 01/28/2023] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a multi-protein complex widely found in eukaryotes. It serves as a central signaling node to coordinate cell growth and metabolism by sensing diverse extracellular and intracellular inputs, including amino acid-, growth factor-, glucose-, and nucleotide-related signals. It is well documented that mTORC1 is recruited to the lysosomal surface, where it is activated and, accordingly, modulates downstream effectors involved in regulating protein, lipid, and glucose metabolism. mTORC1 is thus the central node for coordinating the storage and mobilization of nutrients and energy across various tissues. However, emerging evidence indicated that the overactivation of mTORC1 induced by nutritional disorders leads to the occurrence of a variety of metabolic diseases, including obesity and type 2 diabetes, as well as cancer, neurodegenerative disorders, and aging. That the mTORC1 pathway plays a crucial role in regulating the occurrence of metabolic diseases renders it a prime target for the development of effective therapeutic strategies. Here, we focus on recent advances in our understanding of the regulatory mechanisms underlying how mTORC1 integrates metabolic inputs as well as the role of mTORC1 in the regulation of nutritional and metabolic diseases.
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Affiliation(s)
- Guoyan Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Lei Chen
- Division of Laboratory Safety and Services, Northwest A&F University, Yangling Shaanxi, China
| | - Senlin Qin
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Tingting Zhang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Junhu Yao
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Yanglei Yi
- Address correspondence to YLY (e-mail: )
| | - Lu Deng
- Address correspondence to LD (e-mail: )
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6
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Zhang S, Lin X, Hou Q, Hu Z, Wang Y, Wang Z. Regulation of mTORC1 by amino acids in mammalian cells: A general picture of recent advances. ACTA ACUST UNITED AC 2021; 7:1009-1023. [PMID: 34738031 PMCID: PMC8536509 DOI: 10.1016/j.aninu.2021.05.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 05/13/2021] [Accepted: 05/18/2021] [Indexed: 12/11/2022]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) integrates various types of signal inputs, such as energy, growth factors, and amino acids to regulate cell growth and proliferation mainly through the 2 direct downstream targets, eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) and ribosomal protein S6 kinase 1 (S6K1). Most of the signal arms upstream of mTORC1 including energy status, stress signals, and growth factors converge on the tuberous sclerosis complex (TSC) - Ras homologue enriched in brain (Rheb) axis. Amino acids, however, are distinct from other signals and modulate mTORC1 using a unique pathway. In recent years, the transmission mechanism of amino acid signals upstream of mTORC1 has been gradually elucidated, and some sensors or signal transmission pathways for individual amino acids have also been discovered. With the help of these findings, we propose a general picture of recent advances, which demonstrates that various amino acids from lysosomes, cytoplasm, and Golgi are sensed by their respective sensors. These signals converge on mTORC1 and form a huge and complicated signal network with multiple synergies, antagonisms, and feedback mechanisms.
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Affiliation(s)
- Shizhe Zhang
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Xueyan Lin
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Qiuling Hou
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Zhiyong Hu
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Yun Wang
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Zhonghua Wang
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
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7
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AMPK-mTOR Signaling and Cellular Adaptations in Hypoxia. Int J Mol Sci 2021; 22:ijms22189765. [PMID: 34575924 PMCID: PMC8465282 DOI: 10.3390/ijms22189765] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/02/2021] [Accepted: 09/06/2021] [Indexed: 12/14/2022] Open
Abstract
Cellular energy is primarily provided by the oxidative degradation of nutrients coupled with mitochondrial respiration, in which oxygen participates in the mitochondrial electron transport chain to enable electron flow through the chain complex (I-IV), leading to ATP production. Therefore, oxygen supply is an indispensable chapter in intracellular bioenergetics. In mammals, oxygen is delivered by the bloodstream. Accordingly, the decrease in cellular oxygen level (hypoxia) is accompanied by nutrient starvation, thereby integrating hypoxic signaling and nutrient signaling at the cellular level. Importantly, hypoxia profoundly affects cellular metabolism and many relevant physiological reactions induce cellular adaptations of hypoxia-inducible gene expression, metabolism, reactive oxygen species, and autophagy. Here, we introduce the current knowledge of hypoxia signaling with two-well known cellular energy and nutrient sensing pathways, AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin complex 1 (mTORC1). Additionally, the molecular crosstalk between hypoxic signaling and AMPK/mTOR pathways in various hypoxic cellular adaptions is discussed.
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8
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Amino Acids in Autophagy: Regulation and Function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1332:51-66. [PMID: 34251638 DOI: 10.1007/978-3-030-74180-8_4] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Autophagy is a dynamic process in which the eukaryotic cells break down intracellular components by lysosomal degradation. Under the normal condition, the basal level of autophagy removes damaged organelles, misfolded proteins, or protein aggregates to keep cells in a homeostatic condition. Deprivation of nutrients (e.g., removal of amino acids) stimulates autophagy activity, promoting lysosomal degradation and the recycling of cellular components for cell survival. Importantly, insulin and amino acids are two main inhibitors of autophagy. They both activate the mTOR complex 1 (mTORC1) signaling pathway to inhibit the autophagy upstream of the uncoordinated-51 like kinase 1/2 (ULK1/2) complex that triggers autophagosome formation. In particular, insulin activates mTORC1 via the PI3K class I-AKT pathway; while amino acids activate mTORC1 either through the PI3K class III (hVps34) pathway or through a variety of amino acid sensors located in the cytosol or lysosomal membrane. These amino acid sensors control the translocation of mTORC1 from the cytosol to the lysosomal surface where mTORC1 is activated by Rheb GTPase, therefore regulating autophagy and the lysosomal protein degradation.
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9
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Nagumo Y, Kandori S, Tanuma K, Nitta S, Chihara I, Shiga M, Hoshi A, Negoro H, Kojima T, Mathis BJ, Funakoshi Y, Nishiyama H. PLD1 promotes tumor invasion by regulation of MMP-13 expression via NF-κB signaling in bladder cancer. Cancer Lett 2021; 511:15-25. [PMID: 33945837 DOI: 10.1016/j.canlet.2021.04.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/14/2021] [Accepted: 04/16/2021] [Indexed: 12/31/2022]
Abstract
Invasion of bladder cancer (BC) cells from the mucosa into the muscle layer is canonical for BC progression while phospholipase D isoform 1 (PLD1) is known to mediate development of cancer through phosphatidic acid (PA) production. We therefore used in silico, in vitro and in vivo approaches to detail the effect of PLD1 on BC invasion. In BC patients, higher levels of PLD1 expression were associated with poor prognoses. PLD1 knockdown significantly suppressed cellular invasion by human BC cells and matrix metalloproteinase-13 (MMP-13) was observed to mediate this effect. In our mouse bladder carcinogenesis model, the development of invasive BCs was suppressed by PLD1 knockout and a global transcriptomic analysis in this model indicated MMP-13 as a potential tumor invasion gene with NF-κB (nuclear factor-kB) as its transcriptional regulator. Furthermore, PA administration increased MMP-13 expression in line with NF-κB p65 phosphorylation levels. Collectively, we demonstrate that PLD1 promotes tumor invasion of BC by regulation of MMP-13 expression through the NF-κB signaling pathway and that PLD1 might be a potential therapeutic target to prevent clinical progression in BC patients.
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Affiliation(s)
- Yoshiyuki Nagumo
- Department of Urology, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan
| | - Shuya Kandori
- Department of Urology, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan.
| | - Kozaburo Tanuma
- Department of Urology, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan
| | - Satoshi Nitta
- Department of Urology, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan
| | - Ichiro Chihara
- Department of Urology, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan
| | - Masanobu Shiga
- Department of Urology, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan
| | - Akio Hoshi
- Department of Urology, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan
| | - Hiromitsu Negoro
- Department of Urology, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan
| | - Takahiro Kojima
- Department of Urology, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan
| | - Bryan J Mathis
- International Medical Center, University of Tsukuba Affiliated Hospital, Ibaraki, Japan
| | - Yuji Funakoshi
- Department of Physiological Chemistry, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan
| | - Hiroyuki Nishiyama
- Department of Urology, Faculty of Medicine and Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan
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10
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Bowling FZ, Frohman MA, Airola MV. Structure and regulation of human phospholipase D. Adv Biol Regul 2021; 79:100783. [PMID: 33495125 DOI: 10.1016/j.jbior.2020.100783] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 12/22/2020] [Accepted: 12/28/2020] [Indexed: 12/13/2022]
Abstract
Mammalian phospholipase D (PLD) generates phosphatidic acid, a dynamic lipid secondary messenger involved with a broad spectrum of cellular functions including but not limited to metabolism, migration, and exocytosis. As a promising pharmaceutical target, the biochemical properties of PLD have been well characterized. This has led to the recent crystal structures of human PLD1 and PLD2, the development of PLD specific pharmacological inhibitors, and the identification of cellular regulators of PLD. In this review, we discuss the PLD1 and PLD2 structures, PLD inhibition by small molecules, and the regulation of PLD activity by effector proteins and lipids.
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Affiliation(s)
- Forrest Z Bowling
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA
| | - Michael A Frohman
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY, USA
| | - Michael V Airola
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA.
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11
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Yao Y, Hong S, Ikeda T, Mori H, MacDougald OA, Nada S, Okada M, Inoki K. Amino Acids Enhance Polyubiquitination of Rheb and Its Binding to mTORC1 by Blocking Lysosomal ATXN3 Deubiquitinase Activity. Mol Cell 2020; 80:437-451.e6. [PMID: 33157014 PMCID: PMC7665239 DOI: 10.1016/j.molcel.2020.10.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 08/22/2020] [Accepted: 10/02/2020] [Indexed: 01/02/2023]
Abstract
Amino-acid-induced lysosomal mechanistic target of rapamycin complex 1 (mTORC1) localization through the Rag GTPases is a critical step for its activation by Rheb GTPase. However, how the mTORC1 interacts with Rheb on the lysosome remains elusive. We report that amino acids enhance the polyubiquitination of Rheb (Ub-Rheb), which shows a strong binding preference for mTORC1 and supports its activation, while the Ub-Rheb is subjected to subsequent degradation. Mechanistically, we identified ATXN3 as a Ub-Rheb deubiquitinase whose lysosomal localization is blocked by active Rag heterodimer in response to amino acid stimulation. Consistently, cells lacking functional Rag heterodimer on the lysosome accumulate Ub-Rheb, and blockade of its degradation instigates robust lysosomal mTORC1 localization and its activation without the Ragulator-Rag system. Thus, polyubiquitination of Rheb is an important post-translational modification, which facilitates the binding of mTORC1 to Rheb on the lysosome and is another crosstalk between the amino acid and growth factor signaling for mTORC1 activation.
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Affiliation(s)
- Yao Yao
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA
| | - Sungki Hong
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA
| | - Takayuki Ikeda
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA; Department of Biochemistry, Kanazawa Medical University School of Medicine, 1-1 Daigaku, Uchinada, Kahoku-gun, Ishikawa 920-0293, Japan
| | - Hiroyuki Mori
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 E. Catherine St., Ann Arbor, MI 48109-5622, USA
| | - Ormond A MacDougald
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 E. Catherine St., Ann Arbor, MI 48109-5622, USA; Department of Internal Medicine, University of Michigan Medical School, 1500 East Medical Center Drive, Ann Arbor, MI 48109-5368, USA
| | - Shigeyuki Nada
- Department of Oncogene Research, the Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Masato Okada
- Department of Oncogene Research, the Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ken Inoki
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216, USA; Department of Molecular and Integrative Physiology, University of Michigan Medical School, 1137 E. Catherine St., Ann Arbor, MI 48109-5622, USA; Department of Internal Medicine, University of Michigan Medical School, 1500 East Medical Center Drive, Ann Arbor, MI 48109-5368, USA.
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12
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Texada MJ, Koyama T, Rewitz K. Regulation of Body Size and Growth Control. Genetics 2020; 216:269-313. [PMID: 33023929 PMCID: PMC7536854 DOI: 10.1534/genetics.120.303095] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/29/2020] [Indexed: 12/20/2022] Open
Abstract
The control of body and organ growth is essential for the development of adults with proper size and proportions, which is important for survival and reproduction. In animals, adult body size is determined by the rate and duration of juvenile growth, which are influenced by the environment. In nutrient-scarce environments in which more time is needed for growth, the juvenile growth period can be extended by delaying maturation, whereas juvenile development is rapidly completed in nutrient-rich conditions. This flexibility requires the integration of environmental cues with developmental signals that govern internal checkpoints to ensure that maturation does not begin until sufficient tissue growth has occurred to reach a proper adult size. The Target of Rapamycin (TOR) pathway is the primary cell-autonomous nutrient sensor, while circulating hormones such as steroids and insulin-like growth factors are the main systemic regulators of growth and maturation in animals. We discuss recent findings in Drosophila melanogaster showing that cell-autonomous environment and growth-sensing mechanisms, involving TOR and other growth-regulatory pathways, that converge on insulin and steroid relay centers are responsible for adjusting systemic growth, and development, in response to external and internal conditions. In addition to this, proper organ growth is also monitored and coordinated with whole-body growth and the timing of maturation through modulation of steroid signaling. This coordination involves interorgan communication mediated by Drosophila insulin-like peptide 8 in response to tissue growth status. Together, these multiple nutritional and developmental cues feed into neuroendocrine hubs controlling insulin and steroid signaling, serving as checkpoints at which developmental progression toward maturation can be delayed. This review focuses on these mechanisms by which external and internal conditions can modulate developmental growth and ensure proper adult body size, and highlights the conserved architecture of this system, which has made Drosophila a prime model for understanding the coordination of growth and maturation in animals.
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Affiliation(s)
| | - Takashi Koyama
- Department of Biology, University of Copenhagen, 2100, Denmark
| | - Kim Rewitz
- Department of Biology, University of Copenhagen, 2100, Denmark
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13
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Zhu M, Wang XQ. Regulation of mTORC1 by Small GTPases in Response to Nutrients. J Nutr 2020; 150:1004-1011. [PMID: 31965176 DOI: 10.1093/jn/nxz301] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 10/07/2019] [Accepted: 11/18/2019] [Indexed: 12/15/2022] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a highly evolutionarily conserved serine/threonine kinase that regulates cell growth and metabolism in response to multiple environmental cues, such as nutrients, hormones, energy, and stress. Deregulation of mTORC1 can lead to diseases such as diabetes, obesity, and cancer. A series of small GTPases, including Rag, Ras homolog enriched in brain (Rheb), adenosine diphosphate ribosylation factor 1 (Arf1), Ras-related protein Ral-A, Ras homolog (Rho), and Rab, are involved in regulating mTORC1 in response to nutrients, and mTORC1 is differentially regulated via these small GTPases according to specific conditions. Leucine and arginine sensing are considered to be well-confirmed amino acid-sensing signals, activating mTORC1 via a Rag GTPase-dependent mechanism as well as the Ragulator complex and vacuolar H+-adenosine triphosphatase (v-ATPase). Glutamine promotes mTORC1 activation via Arf1 independently of the Rag GTPase. In this review, we summarize current knowledge regarding the regulation of mTORC1 activity by small GTPases in response to nutrients, focusing on the function of small GTPases in mTORC1 activation and how small GTPases are regulated by nutrients.
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Affiliation(s)
- Min Zhu
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong, China
| | - Xiu-Qi Wang
- College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition Control/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong, China
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14
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Carroll B. Spatial regulation of mTORC1 signalling: Beyond the Rag GTPases. Semin Cell Dev Biol 2020; 107:103-111. [PMID: 32122730 DOI: 10.1016/j.semcdb.2020.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/17/2020] [Accepted: 02/20/2020] [Indexed: 12/15/2022]
Abstract
The mechanistic (or mammalian) Target of Rapamycin Complex 1 (mTORC1) is a central regulator of cell growth and metabolism. By integrating mitogenic signals, mTORC1-dependent phosphorylation of substrates dictates the balance between anabolic, pro-growth and catabolic, recycling processes in the cell. The discovery that amino acids activate mTORC1 by promoting its translocation to the lysosome was a fundamental advance in the understanding of mTORC1 signalling. It has since become clear that the lysosome-cytoplasm shuttling of mTORC1 represents just one layer of spatial control of this signalling pathway. This review will focus on exploring the subcellular localisation of mTORC1 and its regulators to multiple sites within the cell. We will discuss how these spatially distinct regions such as endoplasmic reticulum, plasma membrane and the endosomal pathway co-operate to transduce nutrient availability to mTORC1, allowing for tight control of cell growth.
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Affiliation(s)
- Bernadette Carroll
- School of Biochemistry, Biomedical Sciences Building, University Walk, Bristol, BS8, United Kingdom.
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15
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Yao Y, Wang X, Li H, Fan J, Qian X, Li H, Xu Y. Phospholipase D as a key modulator of cancer progression. Biol Rev Camb Philos Soc 2020; 95:911-935. [PMID: 32073216 DOI: 10.1111/brv.12592] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 02/01/2020] [Accepted: 02/06/2020] [Indexed: 12/15/2022]
Abstract
The phospholipase D (PLD) family has a ubiquitous expression in cells. PLD isoforms (PLDs) and their hydrolysate phosphatidic acid (PA) have been demonstrated to engage in multiple stages of cancer progression. Aberrant expression of PLDs, especially PLD1 and PLD2, has been detected in various cancers. Inhibition or elimination of PLDs activity has been shown to reduce tumour growth and metastasis. PLDs and PA also serve as downstream effectors of various cell-surface receptors, to trigger and regulate propagation of intracellular signals in the process of tumourigenesis and metastasis. Here, we discuss recent advances in understanding the functions of PLDs and PA in discrete stages of cancer progression, including cancer cell growth, invasion and migration, and angiogenesis, with special emphasis on the tumour-associated signalling pathways mediated by PLDs and PA and the functional importance of PLDs and PA in cancer therapy.
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Affiliation(s)
- Yuanfa Yao
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Endocrinology, The Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xinyi Wang
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Clinical Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Hanbing Li
- Institute of Pharmacology, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Jiannan Fan
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China
| | - Xiaohan Qian
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Respiratory Disease, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hong Li
- Department of Endocrinology, The Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yingke Xu
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Endocrinology, The Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
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16
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Frias MA, Mukhopadhyay S, Lehman E, Walasek A, Utter M, Menon D, Foster DA. Phosphatidic acid drives mTORC1 lysosomal translocation in the absence of amino acids. J Biol Chem 2020; 295:263-274. [PMID: 31767684 PMCID: PMC6952608 DOI: 10.1074/jbc.ra119.010892] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 11/14/2019] [Indexed: 01/30/2023] Open
Abstract
Mammalian target of rapamycin complex 1 (mTORC1) promotes cell growth and proliferation in response to nutrients and growth factors. Amino acids induce lysosomal translocation of mTORC1 via the Rag GTPases. Growth factors activate Ras homolog enriched in brain (Rheb), which in turn activates mTORC1 at the lysosome. Amino acids and growth factors also induce the phospholipase D (PLD)-phosphatidic acid (PA) pathway, required for mTORC1 signaling through mechanisms that are not fully understood. Here, using human and murine cell lines, along with immunofluorescence, confocal microscopy, endocytosis, PLD activity, and cell viability assays, we show that exogenously supplied PA vesicles deliver mTORC1 to the lysosome in the absence of amino acids, Rag GTPases, growth factors, and Rheb. Of note, pharmacological or genetic inhibition of endogenous PLD prevented mTORC1 lysosomal translocation. We observed that precancerous cells with constitutive Rheb activation through loss of tuberous sclerosis complex subunit 2 (TSC2) exploit the PLD-PA pathway and thereby sustain mTORC1 activation at the lysosome in the absence of amino acids. Our findings indicate that sequential inputs from amino acids and growth factors trigger PA production required for mTORC1 translocation and activation at the lysosome.
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Affiliation(s)
- Maria A Frias
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10021; Clinical and Translational Master's Program, Clinical and Translational Science Center, Weill Cornell Medicine, New York, New York 10065.
| | - Suman Mukhopadhyay
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10021
| | - Elyssa Lehman
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10021
| | - Aleksandra Walasek
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10021
| | - Matthew Utter
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10021
| | - Deepak Menon
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10021
| | - David A Foster
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10021; Department of Pharmacology, Weill Cornell Medicine, New York, New York 10065.
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17
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McDermott MI, Wang Y, Wakelam MJO, Bankaitis VA. Mammalian phospholipase D: Function, and therapeutics. Prog Lipid Res 2019; 78:101018. [PMID: 31830503 DOI: 10.1016/j.plipres.2019.101018] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/08/2019] [Accepted: 10/14/2019] [Indexed: 01/23/2023]
Abstract
Despite being discovered over 60 years ago, the precise role of phospholipase D (PLD) is still being elucidated. PLD enzymes catalyze the hydrolysis of the phosphodiester bond of glycerophospholipids producing phosphatidic acid and the free headgroup. PLD family members are found in organisms ranging from viruses, and bacteria to plants, and mammals. They display a range of substrate specificities, are regulated by a diverse range of molecules, and have been implicated in a broad range of cellular processes including receptor signaling, cytoskeletal regulation and membrane trafficking. Recent technological advances including: the development of PLD knockout mice, isoform-specific antibodies, and specific inhibitors are finally permitting a thorough analysis of the in vivo role of mammalian PLDs. These studies are facilitating increased recognition of PLD's role in disease states including cancers and Alzheimer's disease, offering potential as a target for therapeutic intervention.
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Affiliation(s)
- M I McDermott
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, United States of America.
| | - Y Wang
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, United States of America; Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128, United States of America
| | - M J O Wakelam
- Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - V A Bankaitis
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, United States of America; Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128, United States of America; Department of Chemistry, Texas A&M University, College Station, Texas 77840, United States of America
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18
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Arhab Y, Abousalham A, Noiriel A. Plant phospholipase D mining unravels new conserved residues important for catalytic activity. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:688-703. [DOI: 10.1016/j.bbalip.2019.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 01/09/2019] [Accepted: 01/13/2019] [Indexed: 01/16/2023]
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19
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Wang F, Zhang J, Zhou G. Deregulated phospholipase D2/mammalian target of rapamycin/hypoxia-inducible factor 1 alpha in peripheral T lymphocytes of oral lichen planus correlated with disease severity. Arch Oral Biol 2019; 98:26-31. [DOI: 10.1016/j.archoralbio.2018.11.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 10/23/2018] [Accepted: 11/01/2018] [Indexed: 12/15/2022]
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20
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Faham N, Zhao L, Welm AL. mTORC1 is a key mediator of RON-dependent breast cancer metastasis with therapeutic potential. NPJ Breast Cancer 2018; 4:36. [PMID: 30456298 PMCID: PMC6226524 DOI: 10.1038/s41523-018-0091-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 10/11/2018] [Indexed: 02/02/2023] Open
Abstract
Metastasis is the biggest challenge in treating breast cancer, and it kills >40,000 breast cancer patients annually in the US. Aberrant expression of the RON receptor tyrosine kinase in breast tumors correlates with poor prognosis and has been shown to promote metastasis. However, the molecular mechanisms that govern how RON promotes metastasis, and how to block it, are still largely unknown. We sought to determine critical effectors of RON using a combination of mutational and pharmacologic strategies. High-throughput proteomic analysis of breast cancer cells upon activation of RON showed robust phosphorylation of ribosomal protein S6. Further analysis revealed that RON strongly signals through mTORC1/p70S6K, which is mediated predominantly by the PI3K pathway. A targeted mutation approach to modulate RON signaling validated the importance of PI3K/mTORC1 pathway for spontaneous metastasis in vivo. Finally, inhibition of mTORC1 with an FDA-approved drug, everolimus, resulted in transient shrinkage of established RON-dependent metastases, and combined blockade of mTORC1 and RON delayed progression. These studies have identified a key downstream mediator of RON-dependent metastasis in breast cancer cells and revealed that inhibition of mTORC1, or combined inhibition of mTORC1 and RON, may be effective for treatment of metastatic breast cancers with elevated expression of RON.
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Affiliation(s)
- Najme Faham
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT USA
| | - Ling Zhao
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT USA
| | - Alana L Welm
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT USA
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21
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Bernfeld E, Menon D, Vaghela V, Zerin I, Faruque P, Frias MA, Foster DA. Phospholipase D-dependent mTOR complex 1 (mTORC1) activation by glutamine. J Biol Chem 2018; 293:16390-16401. [PMID: 30194281 DOI: 10.1074/jbc.ra118.004972] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 08/31/2018] [Indexed: 01/06/2023] Open
Abstract
Glutamine is a key nutrient required for sustaining cell proliferation, contributing to nucleotide, protein, and lipid synthesis. The mTOR complex 1 (mTORC1) is a highly conserved protein complex that acts as a sensor of nutrients, relaying signals for the shift from catabolic to anabolic metabolism. Although glutamine plays an important role in mTORC1 activation, the mechanism is not clear. Here we describe a leucine- and Rag-independent mechanism of mTORC1 activation by glutamine that depends on phospholipase D and the production of phosphatidic acid, which is required for the stability and activity of mTORC1. The phospholipase D-dependent activation of mTORC1 by glutamine depended on the GTPases ADP ribosylation factor 1 (Arf1), RalA, and Rheb. Glutamine deprivation could be rescued by α-ketoglutarate, a downstream metabolite of glutamine. This mechanism represents a distinct nutrient input to mTORC1 that is independent of Rag GTPases and leucine.
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Affiliation(s)
- Elyssa Bernfeld
- From the Departments of Biological Sciences and.,the Biochemistry Program and
| | - Deepak Menon
- From the Departments of Biological Sciences and.,the Biochemistry Program and
| | - Vishaldeep Vaghela
- From the Departments of Biological Sciences and.,Biology Program, Graduate Center, City University of New York, New York, New York 10016, and
| | - Ismat Zerin
- Chemistry, Hunter College, City University of New York, New York, New York 10065
| | | | | | - David A Foster
- From the Departments of Biological Sciences and .,the Biochemistry Program and.,Biology Program, Graduate Center, City University of New York, New York, New York 10016, and.,the Department of Pharmacology, Weill Cornell Medicine, New York, New York 10021
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22
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Nguyen TL, Nokin MJ, Egorov M, Tomé M, Bodineau C, Di Primo C, Minder L, Wdzieczak-Bakala J, Garcia-Alvarez MC, Bignon J, Thoison O, Delpech B, Surpateanu G, Frapart YM, Peyrot F, Abbas K, Terés S, Evrard S, Khatib AM, Soubeyran P, Iorga BI, Durán RV, Collin P. mTOR Inhibition via Displacement of Phosphatidic Acid Induces Enhanced Cytotoxicity Specifically in Cancer Cells. Cancer Res 2018; 78:5384-5397. [PMID: 30054335 DOI: 10.1158/0008-5472.can-18-0232] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 06/09/2018] [Accepted: 07/23/2018] [Indexed: 11/16/2022]
Abstract
The mTOR is a central regulator of cell growth and is highly activated in cancer cells to allow rapid tumor growth. The use of mTOR inhibitors as anticancer therapy has been approved for some types of tumors, albeit with modest results. We recently reported the synthesis of ICSN3250, a halitulin analogue with enhanced cytotoxicity. We report here that ICSN3250 is a specific mTOR inhibitor that operates through a mechanism distinct from those described for previous mTOR inhibitors. ICSN3250 competed with and displaced phosphatidic acid from the FRB domain in mTOR, thus preventing mTOR activation and leading to cytotoxicity. Docking and molecular dynamics simulations evidenced not only the high conformational plasticity of the FRB domain, but also the specific interactions of both ICSN3250 and phosphatidic acid with the FRB domain in mTOR. Furthermore, ICSN3250 toxicity was shown to act specifically in cancer cells, as noncancer cells showed up to 100-fold less sensitivity to ICSN3250, in contrast to other mTOR inhibitors that did not show selectivity. Thus, our results define ICSN3250 as a new class of mTOR inhibitors that specifically targets cancer cells.Significance: ICSN3250 defines a new class of mTORC1 inhibitors that displaces phosphatidic acid at the FRB domain of mTOR, inducing cell death specifically in cancer cells but not in noncancer cells. Cancer Res; 78(18); 5384-97. ©2018 AACR.
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Affiliation(s)
- Tra-Ly Nguyen
- Institut Européen de Chimie et Biologie, INSERM U1218, Université de Bordeaux, Pessac, France
| | - Marie-Julie Nokin
- Institut Européen de Chimie et Biologie, INSERM U1218, Université de Bordeaux, Pessac, France.,Metastasis Research Laboratory, GIGA-Cancer, University of Liège (ULiège), Liège, Belgium
| | - Maxim Egorov
- ATLANTHERA, Cedex, France.,Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Gif-sur-Yvette, France
| | - Mercedes Tomé
- Laboratoire de l'Angiogénèse et du Microenvironnement des Cancers, INSERM U1029, Université de Bordeaux, Allée Geoffroy Saint Hilaire, Bâtiment, Pessac, France
| | - Clément Bodineau
- Institut Européen de Chimie et Biologie, INSERM U1218, Université de Bordeaux, Pessac, France
| | - Carmelo Di Primo
- Université de Bordeaux, Laboratoire ARNA, Bordeaux, France; INSERM U1212, CNRS UMR 5320, Institut Européen de Chimie et Biologie, CNRS UMS3033/INSERMUS001, Pessac, France
| | - Lætitia Minder
- Université de Bordeaux, CNRS UMS3033/INSERM US001, Institut Européen de Chimie et Biologie, Pessac, France
| | | | | | - Jérôme Bignon
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Gif-sur-Yvette, France
| | - Odile Thoison
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Gif-sur-Yvette, France
| | - Bernard Delpech
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Gif-sur-Yvette, France
| | - Georgiana Surpateanu
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Gif-sur-Yvette, France
| | - Yves-Michel Frapart
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS UMR8601, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Fabienne Peyrot
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS UMR8601, Université Paris Descartes, Sorbonne Paris Cité, Paris, France.,Ecole Supérieure du Professorat et de l'Education de l'Académie de Paris, Sorbonne Université, Paris, France
| | - Kahina Abbas
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS UMR8601, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Silvia Terés
- Institut Européen de Chimie et Biologie, INSERM U1218, Université de Bordeaux, Pessac, France
| | - Serge Evrard
- Institut Bergonié, Digestive Tumours Unit, Université de Bordeaux, Bordeaux, France
| | - Abdel-Majid Khatib
- Laboratoire de l'Angiogénèse et du Microenvironnement des Cancers, INSERM U1029, Université de Bordeaux, Allée Geoffroy Saint Hilaire, Bâtiment, Pessac, France
| | - Pierre Soubeyran
- Institut Bergonié, INSERM U1218, Université de Bordeaux, Bordeaux, France
| | - Bogdan I Iorga
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Gif-sur-Yvette, France.
| | - Raúl V Durán
- Institut Européen de Chimie et Biologie, INSERM U1218, Université de Bordeaux, Pessac, France.
| | - Pascal Collin
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Gif-sur-Yvette, France.,Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, CNRS UMR8601, Université Paris Descartes, Sorbonne Paris Cité, Paris, France.,Université Paris Diderot, UFR Odontologie, Paris, France
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23
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Kandori S, Kojima T, Matsuoka T, Yoshino T, Sugiyama A, Nakamura E, Shimazui T, Funakoshi Y, Kanaho Y, Nishiyama H. Phospholipase D2 promotes disease progression of renal cell carcinoma through the induction of angiogenin. Cancer Sci 2018; 109:1865-1875. [PMID: 29660846 PMCID: PMC5989877 DOI: 10.1111/cas.13609] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 03/01/2018] [Accepted: 04/04/2018] [Indexed: 12/18/2022] Open
Abstract
A hallmark of clear cell renal cell carcinoma (ccRCC) is the presence of intracellular lipid droplets (LD) and it is assumed that phosphatidic acid (PA) produced by phospholipase D (PLD) plays some role in the LD formation. However, little is known about the significance of PLD in ccRCC. In this study, we examined the expression levels of PLD in ccRCC. The classical mammalian isoforms of PLD are PLD1 and PLD2, and the levels of both mRNA were higher at the primary tumor sites than in normal kidney tissues. Similarly, both PLD were significantly abundant in tumor cells as determined by analysis using immunohistochemical staining. Importantly, a higher level of PLD was significantly associated with a higher tumor stage and grade. Because PLD2 knockdown effectively suppressed the cell proliferation and invasion of ccRCC as compared with PLD1 in vitro, we examined the effect of PLD2 in vivo. Notably, shRNA-mediated knockdown of PLD2 suppressed the growth and invasion of tumors in nude mouse xenograft models. Moreover, the higher expression of PLD2 was significantly associated with poorer prognosis in 67 patients. As for genes relating to the tumor invasion of PLD2, we found that angiogenin (ANG) was positively regulated by PLD2. In fact, the expression levels of ANG were elevated in tumor tissues as compared with normal kidney and the inhibition of ANG activity with a neutralizing antibody significantly suppressed tumor invasion. Overall, we revealed for the first time that PLD2-produced PA promoted cell invasion through the expression of ANG in ccRCC cells.
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Affiliation(s)
- Shuya Kandori
- Faculty of MedicineDepartment of UrologyUniversity of TsukubaTsukubaJapan
| | - Takahiro Kojima
- Faculty of MedicineDepartment of UrologyUniversity of TsukubaTsukubaJapan
| | - Taeko Matsuoka
- Faculty of MedicineDepartment of UrologyUniversity of TsukubaTsukubaJapan
| | - Takayuki Yoshino
- Faculty of MedicineDepartment of UrologyUniversity of TsukubaTsukubaJapan
| | - Aiko Sugiyama
- DSK ProjectMedical Innovation CenterKyoto University Graduate School of MedicineKyotoJapan
| | - Eijiro Nakamura
- DSK ProjectMedical Innovation CenterKyoto University Graduate School of MedicineKyotoJapan
| | - Toru Shimazui
- Department of UrologyIbaraki Prefectural Central HospitalKasamaJapan
- Faculty of MedicineDepartment of UrologyIbaraki Clinical Education and Training CenterUniversity of TsukubaTsukubaJapan
| | - Yuji Funakoshi
- Department of Physiological ChemistryFaculty of Medicine and Graduate School of Comprehensive Human SciencesUniversity of TsukubaTsukubaJapan
| | - Yasunori Kanaho
- Department of Physiological ChemistryFaculty of Medicine and Graduate School of Comprehensive Human SciencesUniversity of TsukubaTsukubaJapan
| | - Hiroyuki Nishiyama
- Faculty of MedicineDepartment of UrologyUniversity of TsukubaTsukubaJapan
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24
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Pai GM, Zielinski A, Koalick D, Ludwig K, Wang ZQ, Borgmann K, Pospiech H, Rubio I. TSC loss distorts DNA replication programme and sensitises cells to genotoxic stress. Oncotarget 2018; 7:85365-85380. [PMID: 27863419 PMCID: PMC5356742 DOI: 10.18632/oncotarget.13378] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 10/26/2016] [Indexed: 01/14/2023] Open
Abstract
Tuberous Sclerosis (TSC) is characterized by exorbitant mTORC1 signalling and manifests as non-malignant, apoptosis-prone neoplasia. Previous reports have shown that TSC-/- cells are highly susceptible to mild, innocuous doses of genotoxic stress, which drive TSC-/- cells into apoptotic death. It has been argued that this hypersensitivity to stress derives from a metabolic/energetic shortfall in TSC-/- cells, but how metabolic dysregulation affects the DNA damage response and cell cycle alterations in TSC-/- cells exposed to genotoxic stress is not understood. We report here the occurrence of futile checkpoint responses and an unusual type of replicative stress (RS) in TSC1-/- fibroblasts exposed to low-dose genotoxins. This RS is characterized by elevated nucleotide incorporation rates despite only modest origin over-firing. Strikingly, an increased propensity for asymmetric fork progression and profuse chromosomal aberrations upon mild DNA damage confirmed that TSC loss indeed proved detrimental to stress adaptation. We conclude that low stress tolerance of TSC-/- cells manifests at the level of DNA replication control, imposing strong negative selection on genomic instability that could in turn detain TSC-mutant tumours benign.
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Affiliation(s)
- Govind M Pai
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine, University Hospital, 07745 Jena, Germany
| | - Alexandra Zielinski
- Laboratory of Radiobiology & Experimental Radiooncology, Department of Radiotherapy and Radiooncology, Center of Oncology, University Medical Center Hamburg-Eppendorf, Germany, 20246 Hamburg, Germany
| | - Dennis Koalick
- Leibniz Institute on Aging - Fritz Lipmann Institute, 07745 Jena, Germany
| | - Kristin Ludwig
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine, University Hospital, 07745 Jena, Germany
| | - Zhao-Qi Wang
- Leibniz Institute on Aging - Fritz Lipmann Institute, 07745 Jena, Germany
| | - Kerstin Borgmann
- Laboratory of Radiobiology & Experimental Radiooncology, Department of Radiotherapy and Radiooncology, Center of Oncology, University Medical Center Hamburg-Eppendorf, Germany, 20246 Hamburg, Germany
| | - Helmut Pospiech
- Leibniz Institute on Aging - Fritz Lipmann Institute, 07745 Jena, Germany.,Faculty of Biochemistry and Molecular Medicine, University of Oulu, 90014 Oulu, Finland
| | - Ignacio Rubio
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine, University Hospital, 07745 Jena, Germany
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25
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Nakhaei-Rad S, Haghighi F, Nouri P, Rezaei Adariani S, Lissy J, Kazemein Jasemi NS, Dvorsky R, Ahmadian MR. Structural fingerprints, interactions, and signaling networks of RAS family proteins beyond RAS isoforms. Crit Rev Biochem Mol Biol 2018; 53:130-156. [PMID: 29457927 DOI: 10.1080/10409238.2018.1431605] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Saeideh Nakhaei-Rad
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Fereshteh Haghighi
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Parivash Nouri
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Soheila Rezaei Adariani
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Jana Lissy
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Neda S Kazemein Jasemi
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Radovan Dvorsky
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
| | - Mohammad Reza Ahmadian
- a Institute of Biochemistry and Molecular Biology II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany
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26
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Biguanides sensitize leukemia cells to ABT-737-induced apoptosis by inhibiting mitochondrial electron transport. Oncotarget 2018; 7:51435-51449. [PMID: 27283492 PMCID: PMC5239486 DOI: 10.18632/oncotarget.9843] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/22/2016] [Indexed: 02/04/2023] Open
Abstract
Metformin displays antileukemic effects partly due to activation of AMPK and subsequent inhibition of mTOR signaling. Nevertheless, Metformin also inhibits mitochondrial electron transport at complex I in an AMPK-independent manner, Here we report that Metformin and rotenone inhibit mitochondrial electron transport and increase triglyceride levels in leukemia cell lines, suggesting impairment of fatty acid oxidation (FAO). We also report that, like other FAO inhibitors, both agents and the related biguanide, Phenformin, increase sensitivity to apoptosis induction by the bcl-2 inhibitor ABT-737 supporting the notion that electron transport antagonizes activation of the intrinsic apoptosis pathway in leukemia cells. Both biguanides and rotenone induce superoxide generation in leukemia cells, indicating that oxidative damage may sensitize toABT-737 induced apoptosis. In addition, we demonstrate that Metformin sensitizes leukemia cells to the oligomerization of Bak, suggesting that the observed synergy with ABT-737 is mediated, at least in part, by enhanced outer mitochondrial membrane permeabilization. Notably, Phenformin was at least 10-fold more potent than Metformin in abrogating electron transport and increasing sensitivity to ABT-737, suggesting that this agent may be better suited for targeting hematological malignancies. Taken together, our results suggest that inhibition of mitochondrial metabolism by Metformin or Phenformin is associated with increased leukemia cell susceptibility to induction of intrinsic apoptosis, and provide a rationale for clinical studies exploring the efficacy of combining biguanides with the orally bioavailable derivative of ABT-737, Venetoclax.
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Heard JJ, Phung I, Potes MI, Tamanoi F. An oncogenic mutant of RHEB, RHEB Y35N, exhibits an altered interaction with BRAF resulting in cancer transformation. BMC Cancer 2018; 18:69. [PMID: 29320991 PMCID: PMC5763582 DOI: 10.1186/s12885-017-3938-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 12/19/2017] [Indexed: 12/31/2022] Open
Abstract
Background RHEB is a unique member of the RAS superfamily of small GTPases expressed in all tissues and conserved from yeast to humans. Early studies on RHEB indicated a possible RHEB-RAF interaction, but this has not been fully explored. Recent work on cancer genome databases has revealed a reoccurring mutation in RHEB at the Tyr35 position, and a recent study points to the oncogenic potential of this mutant that involves activation of RAF/MEK/ERK signaling. These developments prompted us to reassess the significance of RHEB effect on RAF, and to compare mutant and wild type RHEB. Methods To study RHEB-RAF interaction, and the effect of the Y35N mutation on this interaction, we used transfection, immunoprecipitation, and Western blotting techniques. We generated cell lines stably expressing RHEB WT, RHEB Y35N, and KRAS G12V, and monitored cellular transforming properties through cell proliferation, anchorage independent growth, cell cycle analysis, and foci formation assays. Results We observe a strong interaction between RHEB and BRAF, but not with CRAF. This interaction is dependent on an intact RHEB effector domain and RHEB-GTP loading status. RHEB overexpression decreases RAF activation of the RAF/MEK/ERK pathway and RHEB knockdown results in an increase in RAF/MEK/ERK activation. RHEB Y35N mutation has decreased interaction with BRAF, and RHEB Y35N cells exhibit greater BRAF/CRAF heterodimerization resulting in increased RAF/MEK/ERK signaling. This leads to cancer transformation of RHEB Y35N stably expressing cell lines, similar to KRAS G12 V expressing cell lines. Conclusions RHEB interaction with BRAF is crucial for inhibiting RAF/MEK/ERK signaling. The RHEB Y35N mutant sustains RAF/MEK/ERK signaling due to a decreased interaction with BRAF, leading to increased BRAF/CRAF heterodimerization. RHEB Y35N expressing cells undergo cancer transformation due to decreased interaction between RHEB and BRAF resulting in overactive RAF/MEK/ERK signaling. Taken together with the previously established function of RHEB to activate mTORC1 signaling, it appears that RHEB performs a dual function; one is to suppress the RAF/MEK/ERK signaling and the other is to activate mTORC1 signaling. Electronic supplementary material The online version of this article (10.1186/s12885-017-3938-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jeffrey J Heard
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, 1602 Molecular Sciences Bldg, 609 Charles E. Young Dr. East, Los Angeles, CA, 90095-1489, USA
| | - Ivy Phung
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, 1602 Molecular Sciences Bldg, 609 Charles E. Young Dr. East, Los Angeles, CA, 90095-1489, USA
| | - Mark I Potes
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, 1602 Molecular Sciences Bldg, 609 Charles E. Young Dr. East, Los Angeles, CA, 90095-1489, USA
| | - Fuyuhiko Tamanoi
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, 1602 Molecular Sciences Bldg, 609 Charles E. Young Dr. East, Los Angeles, CA, 90095-1489, USA. .,Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, Japan.
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A Unique Homeostatic Signaling Pathway Links Synaptic Inactivity to Postsynaptic mTORC1. J Neurosci 2018; 38:2207-2225. [PMID: 29311141 DOI: 10.1523/jneurosci.1843-17.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 11/23/2017] [Accepted: 12/27/2017] [Indexed: 12/31/2022] Open
Abstract
mTORC1-dependent translational control plays a key role in several enduring forms of synaptic plasticity such as long term potentiation (LTP) and mGluR-dependent long term depression. Recent evidence demonstrates an additional role in regulating synaptic homeostasis in response to inactivity, where dendritic mTORC1 serves to modulate presynaptic function via retrograde signaling. Presently, it is unclear whether LTP and homeostatic plasticity use a common route to mTORC1-dependent signaling or whether each engage mTORC1 through distinct pathways. Here, we report a unique signaling pathway that specifically couples homeostatic signaling to postsynaptic mTORC1 after loss of excitatory synaptic input. We find that AMPAR blockade, but not LTP-inducing stimulation, induces phospholipase D (PLD)-dependent synthesis of the lipid second messenger phosphatidic acid (PA) in rat cultured hippocampal neurons of either sex. Pharmacological blockade of PLD1/2 or pharmacogenetic disruption of PA interactions with mTOR eliminates mTORC1 signaling and presynaptic compensation driven by AMPAR blockade, but does not alter mTORC1 activation or functional changes during chemical LTP (cLTP). Overexpression of PLD1, but not PLD2, recapitulates both functional synaptic changes as well as signature cellular adaptations associated with homeostatic plasticity. Finally, transient application of exogenous PA is sufficient to drive rapid presynaptic compensation requiring mTORC1-dependent translation of BDNF in the postsynaptic compartment. These results thus define a unique homeostatic signaling pathway coupling mTORC1 activation to changes in excitatory synaptic drive. Our results further imply that more than one canonical mTORC1 activation pathway may be relevant for the design of novel therapeutic approaches against neurodevelopmental disorders associated with mTORC1 dysregulation.SIGNIFICANCE STATEMENT Homeostatic and Hebbian forms of synaptic plasticity are thought to play complementary roles in regulating neural circuit function, but we know little about how these forms of plasticity are distinguished at the single neuron level. Here, we define a signaling pathway that uniquely links mTORC1 with homeostatic signaling in neurons.
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Liu M, Clarke CJ, Salama MF, Choi YJ, Obeid LM, Hannun YA. Co-ordinated activation of classical and novel PKC isoforms is required for PMA-induced mTORC1 activation. PLoS One 2017; 12:e0184818. [PMID: 28926616 PMCID: PMC5604983 DOI: 10.1371/journal.pone.0184818] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 08/31/2017] [Indexed: 01/19/2023] Open
Abstract
Protein kinase C (PKC) has been shown to activate the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway, a central hub in the regulation of cell metabolism, growth and proliferation. However, the mechanisms by which PKCs activate mTORC1 are still ambiguous. Our previous study revealed that activation of classical PKCs (cPKC) results in the perinuclear accumulation of cPKC and phospholipase D2 (PLD2) in recycling endosomes in a PLD2-dependent manner. Here, we report that mTORC1 activation by phorbol 12,13-myristate acetate (PMA) requires both classic, cPKC, and novel PKC (nPKC) isoforms, specifically PKCη, acting through distinct pathways. The translocation of mTOR to perinuclear lysosomes was detected after treatment of PKC activators, which was not colocalized with PKCα- or RAB11-positive endosomes and was not inhibited by PLD inhibitors. We found that PKCη inhibition by siRNA or bisindolylmaleimide I effectively decreased mTOR accumulation in lysosomes and its activity. Also, we identified that PKCη plays a role upstream of the v-ATPase/Ragulator/Rag pathway in response to PMA. These data provides a spatial aspect to the regulation of mTORC1 by sustained activation of PKC, requiring co-ordinated activation of two distinct elements, the perinuclear accumulation of cPKC- and PLD-containing endosomes and the nPKC-dependent translation of of mTOR in the perinuclear lysosomes. The close proximity of these two distinct compartments shown in this study suggests the possibility that transcompartment signaling may be a factor in the regulation of mTORC1 activity and also underscores the importance of PKCη as a potential therapeutic target of mTORC-related disorders.
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Affiliation(s)
- Mengling Liu
- Department of Medicine, Stony Brook University, Stony Brook, NY, United States of America
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, United States of America
| | - Christopher J. Clarke
- Department of Medicine, Stony Brook University, Stony Brook, NY, United States of America
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, United States of America
| | - Mohamed F. Salama
- Department of Medicine, Stony Brook University, Stony Brook, NY, United States of America
- Department of Biochemistry, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Yeon Ja Choi
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, United States of America
- Department of Pathology, Stony Brook University, Stony Brook, NY, United States of America
| | - Lina M. Obeid
- Department of Medicine, Stony Brook University, Stony Brook, NY, United States of America
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, United States of America
| | - Yusuf A. Hannun
- Department of Medicine, Stony Brook University, Stony Brook, NY, United States of America
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, United States of America
- Department of Pathology, Stony Brook University, Stony Brook, NY, United States of America
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30
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Thelen AM, Zoncu R. Emerging Roles for the Lysosome in Lipid Metabolism. Trends Cell Biol 2017; 27:833-850. [PMID: 28838620 DOI: 10.1016/j.tcb.2017.07.006] [Citation(s) in RCA: 160] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 12/20/2022]
Abstract
Precise regulation of lipid biosynthesis, transport, and storage is key to the homeostasis of cells and organisms. Cells rely on a sophisticated but poorly understood network of vesicular and nonvesicular transport mechanisms to ensure efficient delivery of lipids to target organelles. The lysosome stands at the crossroads of this network due to its ability to process and sort exogenous and endogenous lipids. The lipid-sorting function of the lysosome is intimately connected to its recently discovered role as a metabolic command-and-control center, which relays multiple nutrient cues to the master growth regulator, mechanistic target of rapamycin complex (mTORC)1 kinase. In turn, mTORC1 potently drives anabolic processes, including de novo lipid synthesis, while inhibiting lipid catabolism. Here, we describe the dual role of the lysosome in lipid transport and biogenesis, and we discuss how integration of these two processes may play important roles both in normal physiology and in disease.
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Affiliation(s)
- Ashley M Thelen
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720, USA.
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31
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Potheraveedu VN, Schöpel M, Stoll R, Heumann R. Rheb in neuronal degeneration, regeneration, and connectivity. Biol Chem 2017; 398:589-606. [PMID: 28212107 DOI: 10.1515/hsz-2016-0312] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 02/02/2017] [Indexed: 01/31/2023]
Abstract
The small GTPase Rheb was originally detected as an immediate early response protein whose expression was induced by NMDA-dependent synaptic activity in the brain. Rheb's activity is highly regulated by its GTPase activating protein (GAP), the tuberous sclerosis complex protein, which stimulates the conversion from the active, GTP-loaded into the inactive, GDP-loaded conformation. Rheb has been established as an evolutionarily conserved molecular switch protein regulating cellular growth, cell volume, cell cycle, autophagy, and amino acid uptake. The subcellular localization of Rheb and its interacting proteins critically regulate its activity and function. In stem cells, constitutive activation of Rheb enhances differentiation at the expense of self-renewal partially explaining the adverse effects of deregulated Rheb in the mammalian brain. In the context of various cellular stress conditions such as oxidative stress, ER-stress, death factor signaling, and cellular aging, Rheb activation surprisingly enhances rather than prevents cellular degeneration. This review addresses cell type- and cell state-specific function(s) of Rheb and mainly focuses on neurons and their surrounding glial cells. Mechanisms will be discussed in the context of therapy that interferes with Rheb's activity using the antibiotic rapamycin or low molecular weight compounds.
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Affiliation(s)
- Veena Nambiar Potheraveedu
- Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätstr. 150, D-44780 Bochum
| | - Miriam Schöpel
- Biomolecular NMR, Ruhr University of Bochum, D-44780 Bochum
| | - Raphael Stoll
- Biomolecular NMR, Ruhr University of Bochum, D-44780 Bochum
| | - Rolf Heumann
- Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätstr. 150, D-44780 Bochum
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32
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Intramuscular Anabolic Signaling and Endocrine Response Following Resistance Exercise: Implications for Muscle Hypertrophy. Sports Med 2017; 46:671-85. [PMID: 26666743 DOI: 10.1007/s40279-015-0450-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Maintaining skeletal muscle mass and function is critical for disease prevention, mobility and quality of life, and whole-body metabolism. Resistance exercise is known to be a major regulator for promoting muscle protein synthesis and muscle mass accretion. Manipulation of exercise intensity, volume, and rest elicit specific muscular adaptations that can maximize the magnitude of muscle growth. The stimulus of muscle contraction that occurs during differing intensities of resistance exercise results in varying biochemical responses regulating the rate of protein synthesis, known as mechanotransduction. At the cellular level, skeletal muscle adaptation appears to be the result of the cumulative effects of transient changes in gene expression following acute bouts of exercise. Thus, maximizing the resistance exercise-induced anabolic response produces the greatest potential for hypertrophic adaptation with training. The mechanisms involved in converting mechanical signals into the molecular events that control muscle growth are not completely understood; however, skeletal muscle protein synthesis appears to be regulated by the multi-protein phosphorylation cascade, mTORC1 (mammalian/mechanistic target of rapamycin complex 1). The purpose of this review is to examine the physiological response to resistance exercise, with particular emphasis on the endocrine response and intramuscular anabolic signaling through mTORC1. It appears that resistance exercise protocols that maximize muscle fiber recruitment, time-under-tension, and metabolic stress will contribute to maximizing intramuscular anabolic signaling; however, the resistance exercise parameters for maximizing the anabolic response remain unclear.
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Rheb1 deletion in myeloid cells aggravates OVA-induced allergic inflammation in mice. Sci Rep 2017; 7:42655. [PMID: 28225024 PMCID: PMC5320517 DOI: 10.1038/srep42655] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 01/12/2017] [Indexed: 12/28/2022] Open
Abstract
The small GTPase ras homolog enriched in brain (Rheb) is a downstream target of tuberous sclerosis complex 1/2 (TSC1/2) and an upstream activator of the mechanistic target of rapamycin complex 1 (mTORC1), the emerging essential modulator of M1/M2 balance in macrophages. However, the role and regulatory mechanisms of Rheb in macrophage polarization and allergic asthma are not known. In the present study, we utilized a mouse model with myeloid cell-specific deletion of the Rheb1 gene and an ovalbumin (OVA)-induced allergic asthma model to investigate the role of Rheb1 in allergic asthma and macrophage polarization. Increased activity of Rheb1 and mTORC1 was observed in myeloid cells of C57BL/6 mice with OVA-induced asthma. In an OVA-induced asthma model, Rheb1-KO mice demonstrated a more serious inflammatory response, more mucus production, enhanced airway hyper-responsiveness, and greater eosinophil numbers in bronchoalveolar lavage fluid (BALF). They also showed increased numbers of bone marrow macrophages and BALF myeloid cells, elevated M2 polarization and reduced M1 polarization of macrophages. Thus, we have established that Rheb1 is critical for the polarization of macrophages and inhibition of allergic asthma. Deletion of Rheb1 enhances M2 polarization but decreases M1 polarization in alveolar macrophages, leading to the aggravation of OVA-induced allergic asthma.
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Smiles WJ, Hawley JA, Camera DM. Effects of skeletal muscle energy availability on protein turnover responses to exercise. ACTA ACUST UNITED AC 2016; 219:214-25. [PMID: 26792333 DOI: 10.1242/jeb.125104] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Skeletal muscle adaptation to exercise training is a consequence of repeated contraction-induced increases in gene expression that lead to the accumulation of functional proteins whose role is to blunt the homeostatic perturbations generated by escalations in energetic demand and substrate turnover. The development of a specific 'exercise phenotype' is the result of new, augmented steady-state mRNA and protein levels that stem from the training stimulus (i.e. endurance or resistance based). Maintaining appropriate skeletal muscle integrity to meet the demands of training (i.e. increases in myofibrillar and/or mitochondrial protein) is regulated by cyclic phases of synthesis and breakdown, the rate and turnover largely determined by the protein's half-life. Cross-talk among several intracellular systems regulating protein synthesis, breakdown and folding is required to ensure protein equilibrium is maintained. These pathways include both proteasomal and lysosomal degradation systems (ubiquitin-mediated and autophagy, respectively) and the protein translational and folding machinery. The activities of these cellular pathways are bioenergetically expensive and are modified by intracellular energy availability (i.e. macronutrient intake) and the 'training impulse' (i.e. summation of the volume, intensity and frequency). As such, exercise-nutrient interactions can modulate signal transduction cascades that converge on these protein regulatory systems, especially in the early post-exercise recovery period. This review focuses on the regulation of muscle protein synthetic response-adaptation processes to divergent exercise stimuli and how intracellular energy availability interacts with contractile activity to impact on muscle remodelling.
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Affiliation(s)
- William J Smiles
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC 3065, Australia
| | - John A Hawley
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC 3065, Australia Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Donny M Camera
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC 3065, Australia
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35
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Yoon MS, Son K, Arauz E, Han JM, Kim S, Chen J. Leucyl-tRNA Synthetase Activates Vps34 in Amino Acid-Sensing mTORC1 Signaling. Cell Rep 2016; 16:1510-1517. [PMID: 27477288 DOI: 10.1016/j.celrep.2016.07.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 06/08/2016] [Accepted: 07/01/2016] [Indexed: 11/16/2022] Open
Abstract
Amino acid availability activates signaling by the mammalian target of rapamycin (mTOR) complex 1, mTORC1, a master regulator of cell growth. The class III PI-3-kinase Vps34 mediates amino acid signaling to mTORC1 by regulating lysosomal translocation and activation of the phospholipase PLD1. Here, we identify leucyl-tRNA synthetase (LRS) as a leucine sensor for the activation of Vps34-PLD1 upstream of mTORC1. LRS is necessary for amino acid-induced Vps34 activation, cellular PI(3)P level increase, PLD1 activation, and PLD1 lysosomal translocation. Leucine binding, but not tRNA charging activity of LRS, is required for this regulation. Moreover, LRS physically interacts with Vps34 in amino acid-stimulatable non-autophagic complexes. Finally, purified LRS protein activates Vps34 kinase in vitro in a leucine-dependent manner. Collectively, our findings provide compelling evidence for a direct role of LRS in amino acid activation of Vps34 via a non-canonical mechanism and fill a gap in the amino acid-sensing mTORC1 signaling network.
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Affiliation(s)
- Mee-Sup Yoon
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601 South Goodwin Avenue B107, Urbana, IL 61801, USA; Department of Molecular Medicine, School of Medicine, Gachon University, Incheon 406-840, Republic of Korea.
| | - Kook Son
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601 South Goodwin Avenue B107, Urbana, IL 61801, USA
| | - Edwin Arauz
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601 South Goodwin Avenue B107, Urbana, IL 61801, USA
| | - Jung Min Han
- Department of Integrated OMICS for Biomedical Science, Yonsei University, Seoul 120-749, Republic of Korea; College of Pharmacy, Yonsei University, Incheon 406-840, Republic of Korea
| | - Sunghoon Kim
- Medicinal Bioconvergence Research Center, Seoul National University, Seoul 151-742, Republic of Korea
| | - Jie Chen
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601 South Goodwin Avenue B107, Urbana, IL 61801, USA.
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Bae JY, Shin KO, Woo J, Woo SH, Jang KS, Lee YH, Kang S. Exercise and dietary change ameliorate high fat diet induced obesity and insulin resistance via mTOR signaling pathway. J Exerc Nutrition Biochem 2016; 20:28-33. [PMID: 27508151 PMCID: PMC4977908 DOI: 10.20463/jenb.2016.06.20.2.4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 04/25/2016] [Accepted: 05/23/2016] [Indexed: 12/11/2022] Open
Abstract
[Purpose] The purpose of this study was to investigate the effect of exercise and dietary change on obesity and insulin resistance and mTOR signaling protein levels in skeletal muscles of obese rats. [Methods] Sixty male Sprague-Dawley rats were divided into CO (Normal diet) and HF (High Fat diet) groups in order to induce obesity for 15 weeks. The rats were then subdivided into CO, COT (CO + Training), HF, HFT (HF + Training), HFND (Dietary change), and HFNDT (HFND + Training) groups (10 rats / group). The training groups underwent moderate-intensity treadmill exercise for 8 weeks, after which soleus muscles were excised and analyzed. Data was statistically analyzed by independent t-test and One-way ANOVA tests with a 0.05 significance level. [Results] Fasting blood glucose, plasma insulin, and HOMA-IR in the HF group were significantly higher, as compared with other groups (p <.05). Protein levels of insulin receptor subunit-1 (IRS-1), IRS-2, and p-Akt were significantly higher in the HFT, HFND, and HFNDT groups, as compared with HF group. In addition, the protein levels of the mammalian target of rapamycin complex 1 (mTORC1) and ribosomal S6 protein kinase 1 were significantly decreased by exercise and dietary change (p <.05). However, mTORC2 and phosphoinositide 3-kinase were significantly increased (p <.05). [Conclusion] In summary, despite the negative impact of continuous high fat intake, regular exercise and dietary change showed a positive effect on insulin resistance and mTOR signaling protein levels.
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Affiliation(s)
- Ju Yong Bae
- Laboratory of Exercise Biochemistry, Department of Physical Education, Dong-A University, Busan Republic of Korea
| | - Ki Ok Shin
- Laboratory of Exercise Biochemistry, Department of Physical Education, Dong-A University, Busan Republic of Korea
| | - Jinhee Woo
- Laboratory of Exercise Biochemistry, Department of Physical Education, Dong-A University, Busan Republic of Korea
| | - Sang Heon Woo
- Laboratory of Exercise Biochemistry, Department of Physical Education, Dong-A University, Busan Republic of Korea
| | - Ki Soeng Jang
- Laboratory of Exercise Biochemistry, Department of Physical Education, Dong-A University, Busan Republic of Korea
| | - Yul Hyo Lee
- Laboratory of Exercise Biochemistry, Department of Physical Education, Dong-A University, Busan Republic of Korea
| | - Sunghwun Kang
- Laboratory of Exercise physiology, Division of Sport Science, Kangwon National University, Chuncheon Republic of Korea
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Ghosh AP, Marshall CB, Coric T, Shim EH, Kirkman R, Ballestas ME, Ikura M, Bjornsti MA, Sudarshan S. Point mutations of the mTOR-RHEB pathway in renal cell carcinoma. Oncotarget 2016; 6:17895-910. [PMID: 26255626 PMCID: PMC4627224 DOI: 10.18632/oncotarget.4963] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 07/03/2015] [Indexed: 01/21/2023] Open
Abstract
Aberrations in the mTOR (mechanistic target of rapamycin) axis are frequently reported in cancer. Using publicly available tumor genome sequencing data, we identified several point mutations in MTOR and its upstream regulator RHEB (Ras homolog enriched in brain) in patients with clear cell renal cell carcinoma (ccRCC), the most common histology of kidney cancer. Interestingly, we found a prominent cluster of hyperactivating mutations in the FAT (FRAP-ATM-TTRAP) domain of mTOR in renal cell carcinoma that led to an increase in both mTORC1 and mTORC2 activities and led to an increased proliferation of cells. Several of the FAT domain mutants demonstrated a decreased binding of DEPTOR (DEP domain containing mTOR-interacting protein), while a subset of these mutations showed altered binding of the negative regulator PRAS40 (proline rich AKT substrate 40). We also identified a recurrent mutation in RHEB in ccRCC patients that leads to an increase in mTORC1 activity. In vitro characterization of this RHEB mutation revealed that this mutant showed considerable resistance to TSC2 (Tuberous Sclerosis 2) GAP (GTPase activating protein) activity, though its interaction with TSC2 remained unaltered. Mutations in the FAT domain of MTOR and in RHEB remained sensitive to rapamycin, though several of these mutations demonstrated residual mTOR kinase activity after treatment with rapamycin at clinically relevant doses. Overall, our data suggests that point mutations in the mTOR pathway may lead to downstream mTOR hyperactivation through multiple different mechanisms to confer a proliferative advantage to a tumor cell.
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Affiliation(s)
- Arindam P Ghosh
- Department of Urology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Christopher B Marshall
- Department of Medical Biophysics, Campbell Family Cancer Research Institute, Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada
| | - Tatjana Coric
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Eun-Hee Shim
- Department of Urology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Richard Kirkman
- Department of Urology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Mary E Ballestas
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Mitsuhiko Ikura
- Department of Medical Biophysics, Campbell Family Cancer Research Institute, Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada
| | - Mary-Ann Bjornsti
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sunil Sudarshan
- Department of Urology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Mukhopadhyay S, Frias MA, Chatterjee A, Yellen P, Foster DA. The Enigma of Rapamycin Dosage. Mol Cancer Ther 2016; 15:347-53. [PMID: 26916116 DOI: 10.1158/1535-7163.mct-15-0720] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 11/03/2015] [Indexed: 12/20/2022]
Abstract
The mTOR pathway is a critical regulator of cell growth, proliferation, metabolism, and survival. Dysregulation of mTOR signaling has been observed in most cancers and, thus, the mTOR pathway has been extensively studied for therapeutic intervention. Rapamycin is a natural product that inhibits mTOR with high specificity. However, its efficacy varies by dose in several contexts. First, different doses of rapamycin are needed to suppress mTOR in different cell lines; second, different doses of rapamycin are needed to suppress the phosphorylation of different mTOR substrates; and third, there is a differential sensitivity of the two mTOR complexes mTORC1 and mTORC2 to rapamycin. Intriguingly, the enigmatic properties of rapamycin dosage can be explained in large part by the competition between rapamycin and phosphatidic acid (PA) for mTOR. Rapamycin and PA have opposite effects on mTOR whereby rapamycin destabilizes and PA stabilizes both mTOR complexes. In this review, we discuss the properties of rapamycin dosage in the context of anticancer therapeutics.
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Affiliation(s)
- Suman Mukhopadhyay
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York
| | - Maria A Frias
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York
| | - Amrita Chatterjee
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York
| | - Paige Yellen
- Molecular Pharmacology & Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York
| | - David A Foster
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York. Department of Pharmacology, Weill-Cornell Medical College, New York, New York.
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The role of amino acid-induced mammalian target of rapamycin complex 1(mTORC1) signaling in insulin resistance. Exp Mol Med 2016; 48:e201. [PMID: 27534530 PMCID: PMC4686696 DOI: 10.1038/emm.2015.93] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 09/16/2015] [Accepted: 10/02/2015] [Indexed: 01/07/2023] Open
Abstract
Mammalian target of rapamycin (mTOR) controls cell growth and metabolism in response to nutrients, energy, and growth factors. Recent findings have placed the lysosome at the core of mTOR complex 1 (mTORC1) regulation by amino acids. Two parallel pathways, Rag GTPase-Ragulator and Vps34-phospholipase D1 (PLD1), regulate mTOR activation on the lysosome. This review describes the recent advances in understanding amino acid-induced mTOR signaling with a particular focus on the role of mTOR in insulin resistance.
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40
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Carroll B, Maetzel D, Maddocks ODK, Otten G, Ratcliff M, Smith GR, Dunlop EA, Passos JF, Davies OR, Jaenisch R, Tee AR, Sarkar S, Korolchuk VI. Control of TSC2-Rheb signaling axis by arginine regulates mTORC1 activity. eLife 2016; 5:e11058. [PMID: 26742086 PMCID: PMC4764560 DOI: 10.7554/elife.11058] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 12/30/2015] [Indexed: 01/07/2023] Open
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) is the key signaling hub that regulates cellular protein homeostasis, growth, and proliferation in health and disease. As a prerequisite for activation of mTORC1 by hormones and mitogens, there first has to be an available pool of intracellular amino acids. Arginine, an amino acid essential during mammalian embryogenesis and early development is one of the key activators of mTORC1. Herein, we demonstrate that arginine acts independently of its metabolism to allow maximal activation of mTORC1 by growth factors via a mechanism that does not involve regulation of mTORC1 localization to lysosomes. Instead, arginine specifically suppresses lysosomal localization of the TSC complex and interaction with its target small GTPase protein, Rheb. By interfering with TSC-Rheb complex, arginine relieves allosteric inhibition of Rheb by TSC. Arginine cooperates with growth factor signaling which further promotes dissociation of TSC2 from lysosomes and activation of mTORC1. Arginine is the main amino acid sensed by the mTORC1 pathway in several cell types including human embryonic stem cells (hESCs). Dependence on arginine is maintained once hESCs are differentiated to fibroblasts, neurons, and hepatocytes, highlighting the fundamental importance of arginine-sensing to mTORC1 signaling. Together, our data provide evidence that different growth promoting cues cooperate to a greater extent than previously recognized to achieve tight spatial and temporal regulation of mTORC1 signaling.
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Affiliation(s)
- Bernadette Carroll
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Dorothea Maetzel
- Whitehead Institute for Biomedical ResearchMassachusetts Institute of TechnologyCambridgeUnited States
| | | | - Gisela Otten
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Matthew Ratcliff
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Graham R Smith
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Elaine A Dunlop
- Institute of Cancer and GeneticsCardiff UniversityCardiffUnited Kingdom
| | - João F Passos
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Owen R Davies
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
| | - Rudolf Jaenisch
- Whitehead Institute for Biomedical ResearchMassachusetts Institute of TechnologyCambridgeUnited States
| | - Andrew R Tee
- Institute of Cancer and GeneticsCardiff UniversityCardiffUnited Kingdom
| | - Sovan Sarkar
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental SciencesUniversity of BirminghamBirminghamUnited Kingdom
| | - Viktor I Korolchuk
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle upon TyneUnited Kingdom
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Abstract
The small GTPases from the rat sarcoma (Ras) superfamily are a heterogeneous group of proteins of about 21 kDa that act as molecular switches, modulating cell signaling pathways and controlling diverse cellular processes. They are active when bound to guanosine triphosphate (GTP) and inactive when bound to guanosine diphosphate (GDP). Ras homolog enriched in brain (Rheb) is a member of the Ras GTPase superfamily and a key activator of the mammalian/mechanistic target of rapamycin complex 1 (mTORC1). We recently determined that microspherule protein 1 (MCRS1) maintains Rheb at lysosomal surfaces in an amino acid-dependent manner. MCRS1 depletion promotes the formation of the GDP-bound form of Rheb, which is then delocalized from the lysosomal platform and transported to endocytic recycling vesicles, leading to mTORC1 inactivation. During this delocalization process, Rheb-GDP remains farnesylated and associated with cellular endomembranes. These findings provide new insights into the regulation of small GTPases, whose activity depends on both their GTP/GDP switch state and their capacity to move between different cellular membrane-bound compartments. Dynamic spatial transport between compartments makes it possible to alter the proximity of small GTPases to their activatory sites depending on the prevailing physiological and cellular conditions.
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Affiliation(s)
- Amanda Garrido
- a Cancer Cell Biology Program, Growth Factors, Nutrients and Cancer Group , Centro Nacional de Investigaciones Oncológicas , CNIO , Madrid , Spain
| | - Marta Brandt
- a Cancer Cell Biology Program, Growth Factors, Nutrients and Cancer Group , Centro Nacional de Investigaciones Oncológicas , CNIO , Madrid , Spain
| | - Nabil Djouder
- a Cancer Cell Biology Program, Growth Factors, Nutrients and Cancer Group , Centro Nacional de Investigaciones Oncológicas , CNIO , Madrid , Spain
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Abstract
Although the eukaryotic TOR (target of rapamycin) kinase signalling pathway has emerged as a key player for integrating nutrient-, energy- and stress-related cues with growth and metabolic outputs, relatively little is known of how this ancient regulatory mechanism has been adapted in higher plants. Drawing comparisons with the substantial knowledge base around TOR kinase signalling in fungal and animal systems, functional aspects of this pathway in plants are reviewed. Both conserved and divergent elements are discussed in relation to unique aspects associated with an autotrophic mode of nutrition and adaptive strategies for multicellular development exhibited by plants.
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43
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Bruntz RC, Lindsley CW, Brown HA. Phospholipase D signaling pathways and phosphatidic acid as therapeutic targets in cancer. Pharmacol Rev 2015; 66:1033-79. [PMID: 25244928 DOI: 10.1124/pr.114.009217] [Citation(s) in RCA: 161] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phospholipase D is a ubiquitous class of enzymes that generates phosphatidic acid as an intracellular signaling species. The phospholipase D superfamily plays a central role in a variety of functions in prokaryotes, viruses, yeast, fungi, plants, and eukaryotic species. In mammalian cells, the pathways modulating catalytic activity involve a variety of cellular signaling components, including G protein-coupled receptors, receptor tyrosine kinases, polyphosphatidylinositol lipids, Ras/Rho/ADP-ribosylation factor GTPases, and conventional isoforms of protein kinase C, among others. Recent findings have shown that phosphatidic acid generated by phospholipase D plays roles in numerous essential cellular functions, such as vesicular trafficking, exocytosis, autophagy, regulation of cellular metabolism, and tumorigenesis. Many of these cellular events are modulated by the actions of phosphatidic acid, and identification of two targets (mammalian target of rapamycin and Akt kinase) has especially highlighted a role for phospholipase D in the regulation of cellular metabolism. Phospholipase D is a regulator of intercellular signaling and metabolic pathways, particularly in cells that are under stress conditions. This review provides a comprehensive overview of the regulation of phospholipase D activity and its modulation of cellular signaling pathways and functions.
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Affiliation(s)
- Ronald C Bruntz
- Department of Pharmacology (R.C.B., C.W.L., H.A.B.) and Vanderbilt Center for Neuroscience Drug Discovery (C.W.L.), Vanderbilt University Medical Center; Department of Chemistry, Vanderbilt Institute of Chemical Biology (C.W.L., H.A.B.); Vanderbilt Specialized Chemistry for Accelerated Probe Development (C.W.L.); and Department of Biochemistry, Vanderbilt-Ingram Cancer Center (H.A.B.), Vanderbilt University, Nashville, Tennessee
| | - Craig W Lindsley
- Department of Pharmacology (R.C.B., C.W.L., H.A.B.) and Vanderbilt Center for Neuroscience Drug Discovery (C.W.L.), Vanderbilt University Medical Center; Department of Chemistry, Vanderbilt Institute of Chemical Biology (C.W.L., H.A.B.); Vanderbilt Specialized Chemistry for Accelerated Probe Development (C.W.L.); and Department of Biochemistry, Vanderbilt-Ingram Cancer Center (H.A.B.), Vanderbilt University, Nashville, Tennessee
| | - H Alex Brown
- Department of Pharmacology (R.C.B., C.W.L., H.A.B.) and Vanderbilt Center for Neuroscience Drug Discovery (C.W.L.), Vanderbilt University Medical Center; Department of Chemistry, Vanderbilt Institute of Chemical Biology (C.W.L., H.A.B.); Vanderbilt Specialized Chemistry for Accelerated Probe Development (C.W.L.); and Department of Biochemistry, Vanderbilt-Ingram Cancer Center (H.A.B.), Vanderbilt University, Nashville, Tennessee
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44
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De Cicco M, Rahim MSA, Dames SA. Regulation of the Target of Rapamycin and Other Phosphatidylinositol 3-Kinase-Related Kinases by Membrane Targeting. MEMBRANES 2015; 5:553-75. [PMID: 26426064 PMCID: PMC4703999 DOI: 10.3390/membranes5040553] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 09/24/2015] [Indexed: 01/05/2023]
Abstract
Phosphatidylinositol 3-kinase-related kinases (PIKKs) play vital roles in the regulation of cell growth, proliferation, survival, and consequently metabolism, as well as in the cellular response to stresses such as ionizing radiation or redox changes. In humans six family members are known to date, namely mammalian/mechanistic target of rapamycin (mTOR), ataxia-telangiectasia mutated (ATM), ataxia- and Rad3-related (ATR), DNA-dependent protein kinase catalytic subunit (DNA-PKcs), suppressor of morphogenesis in genitalia-1 (SMG-1), and transformation/transcription domain-associated protein (TRRAP). All fulfill rather diverse functions and most of them have been detected in different cellular compartments including various cellular membranes. It has been suggested that the regulation of the localization of signaling proteins allows for generating a locally specific output. Moreover, spatial partitioning is expected to improve the reliability of biochemical signaling. Since these assumptions may also be true for the regulation of PIKK function, the current knowledge about the regulation of the localization of PIKKs at different cellular (membrane) compartments by a network of interactions is reviewed. Membrane targeting can involve direct lipid-/membrane interactions as well as interactions with membrane-anchored regulatory proteins, such as, for example, small GTPases, or a combination of both.
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Affiliation(s)
- Maristella De Cicco
- Department of Chemistry, Biomolecular NMR Spectroscopy, Technische Universität München, Lichtenbergstr. 4, Garching 85747, Germany.
| | - Munirah S Abd Rahim
- Department of Chemistry, Biomolecular NMR Spectroscopy, Technische Universität München, Lichtenbergstr. 4, Garching 85747, Germany.
| | - Sonja A Dames
- Department of Chemistry, Biomolecular NMR Spectroscopy, Technische Universität München, Lichtenbergstr. 4, Garching 85747, Germany.
- Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg 85764, Germany.
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45
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Engström W, Darbre P, Eriksson S, Gulliver L, Hultman T, Karamouzis MV, Klaunig JE, Mehta R, Moorwood K, Sanderson T, Sone H, Vadgama P, Wagemaker G, Ward A, Singh N, Al-Mulla F, Al-Temaimi R, Amedei A, Colacci AM, Vaccari M, Mondello C, Scovassi AI, Raju J, Hamid RA, Memeo L, Forte S, Roy R, Woodrick J, Salem HK, Ryan EP, Brown DG, Bisson WH. The potential for chemical mixtures from the environment to enable the cancer hallmark of sustained proliferative signalling. Carcinogenesis 2015; 36 Suppl 1:S38-60. [PMID: 26106143 DOI: 10.1093/carcin/bgv030] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The aim of this work is to review current knowledge relating the established cancer hallmark, sustained cell proliferation to the existence of chemicals present as low dose mixtures in the environment. Normal cell proliferation is under tight control, i.e. cells respond to a signal to proliferate, and although most cells continue to proliferate into adult life, the multiplication ceases once the stimulatory signal disappears or if the cells are exposed to growth inhibitory signals. Under such circumstances, normal cells remain quiescent until they are stimulated to resume further proliferation. In contrast, tumour cells are unable to halt proliferation, either when subjected to growth inhibitory signals or in the absence of growth stimulatory signals. Environmental chemicals with carcinogenic potential may cause sustained cell proliferation by interfering with some cell proliferation control mechanisms committing cells to an indefinite proliferative span.
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Affiliation(s)
- Wilhelm Engström
- Department of Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, PO Box 7028, 75007 Uppsala, Sweden,
| | - Philippa Darbre
- School of Biological Sciences, University of Reading, Whiteknights, Reading RG6 6UB, UK
| | - Staffan Eriksson
- Department of Biochemistry, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, Box 575, 75123 Uppsala, Sweden
| | - Linda Gulliver
- Faculty of Medicine, University of Otago, PO Box 913, Dunedin 9050, New Zealand
| | - Tove Hultman
- Department of Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, PO Box 7028, 75007 Uppsala, Sweden, School of Biological Sciences, University of Reading, Whiteknights, Reading RG6 6UB, UK
| | - Michalis V Karamouzis
- Department of Biological Chemistry Medical School, Institute of Molecular Medicine and Biomedical Research, University of Athens, Marasli 3, Kolonaki, Athens 10676, Greece
| | - James E Klaunig
- Department of Environmental Health, School of Public Health, Indiana University Bloomington , 1025 E. 7th Street, Suite 111, Bloomington, IN 47405, USA
| | - Rekha Mehta
- Regulatory Toxicology Research Division, Bureau of Chemical Safety, Food Directorate, HPFB, Health Canada, 251 Sir F.G. Banting Driveway, AL # 2202C, Tunney's Pasture, Ottawa, Ontario K1A 0K9, Canada
| | - Kim Moorwood
- Department of Biochemistry and Biology, University of Bath , Claverton Down, Bath BA2 7AY, UK
| | - Thomas Sanderson
- INRS-Institut Armand-Frappier, 531 boulevard des Prairies, Laval, Quebec H7V 1B7, Canada
| | - Hideko Sone
- Environmental Exposure Research Section, Center for Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibraki 3058506, Japan
| | - Pankaj Vadgama
- IRC in Biomedical Materials, School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Gerard Wagemaker
- Center for Stem Cell Research and Development, Hacettepe University, Ankara 06100, Turkey
| | - Andrew Ward
- Department of Biochemistry and Biology, University of Bath , Claverton Down, Bath BA2 7AY, UK
| | - Neetu Singh
- Centre for Advanced Research, King George's Medical University, Chowk, Lucknow, Uttar Pradesh 226003, India
| | - Fahd Al-Mulla
- Department of Pathology, Kuwait University, Safat 13110, Kuwait
| | | | - Amedeo Amedei
- Department of Experimental and Clinical Medicine, University of Firenze, Firenze 50134, Italy
| | - Anna Maria Colacci
- Center for Environmental Carcinogenesis and Risk Assessment, Environmental Protection and Health Prevention Agency, Bologna 40126, Italy
| | - Monica Vaccari
- Center for Environmental Carcinogenesis and Risk Assessment, Environmental Protection and Health Prevention Agency, Bologna 40126, Italy
| | - Chiara Mondello
- Institute of Molecular Genetics, National Research Council, Pavia 27100, Italy
| | - A Ivana Scovassi
- Institute of Molecular Genetics, National Research Council, Pavia 27100, Italy
| | - Jayadev Raju
- Regulatoty Toxicology Research Division, Bureau of Chemical Safety, Food Directorate, HPFB, Health Canada, Ottawa, Ontario K1A0K9, Canada
| | - Roslida A Hamid
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Lorenzo Memeo
- Mediterranean Institute of Oncology, Viagrande 95029, Italy
| | - Stefano Forte
- Mediterranean Institute of Oncology, Viagrande 95029, Italy
| | - Rabindra Roy
- Molecular Oncology Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Jordan Woodrick
- Molecular Oncology Program, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Hosni K Salem
- Urology Dept. kasr Al-Ainy School of Medicine, Cairo University, El Manial, Cairo 12515, Egypt
| | - Elizabeth P Ryan
- Department of Environmental and Radiological Sciences, Colorado State University//Colorado School of Public Health, Fort Collins CO 80523-1680, USA and
| | - Dustin G Brown
- Department of Environmental and Radiological Sciences, Colorado State University//Colorado School of Public Health, Fort Collins CO 80523-1680, USA and
| | - William H Bisson
- Environmental and Molecular Toxicology, Environmental Health Sciences Center, Oregon State University, Corvallis, OR 97331, USA
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46
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Torres-Ayuso P, Tello-Lafoz M, Mérida I, Ávila-Flores A. Diacylglycerol kinase-ζ regulates mTORC1 and lipogenic metabolism in cancer cells through SREBP-1. Oncogenesis 2015; 4:e164. [PMID: 26302180 PMCID: PMC4632073 DOI: 10.1038/oncsis.2015.22] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 06/26/2015] [Accepted: 07/07/2015] [Indexed: 01/03/2023] Open
Abstract
Diacylglycerol kinases (DGKs) transform diacylglycerol (DAG) into phosphatidic acid (PA), balancing the levels of these key metabolic and signaling lipids. We previously showed that PA derived from the DGKζ isoform promotes mammalian target of rapamycin complex 1 (mTORC1) activation. This function might be crucial for the growth and survival of cancer cells, especially for those resistant to the allosteric mTOR inhibitor rapamycin. How this positive function of DGKζ coordinates with DAG metabolism and signaling is unknown. In this study, we used a rapamycin-resistant colon cancer cell line as a model to address the role of DGKζ in tumor cells. We found that DGKζ predominated over other PA sources such as DGKα or phospholipase D to activate mTORC1, and that its activity was a component of the rapamycin-induced feedback loops. We show that the DGKζ DAG-consuming function is central to cell homeostasis, as DAG negatively regulates levels of the lipogenic transcription factor SREBP-1. Our findings suggest a model in which simultaneous regulation of DAG and PA levels by DGKζ is integrated with mTOR function to maintain tumor cell homeostasis; we provide new evidence of the crosstalk between mTOR and lipid metabolism that will be advantageous in the design of drug therapies.
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Affiliation(s)
- P Torres-Ayuso
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - M Tello-Lafoz
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - I Mérida
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - A Ávila-Flores
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
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47
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Armijo ME, Campos T, Fuentes-Villalobos F, Palma ME, Pincheira R, Castro AF. Rheb signaling and tumorigenesis: mTORC1 and new horizons. Int J Cancer 2015; 138:1815-23. [PMID: 26234902 DOI: 10.1002/ijc.29707] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 07/22/2015] [Indexed: 01/05/2023]
Abstract
Rheb is a conserved small GTPase that belongs to the Ras superfamily, and is mainly involved in activation of cell growth through stimulation of mTORC1 activity. Because deregulation of the Rheb/mTORC1 signaling is associated with proliferative disorders and cancer, inhibition of mTORC1 has been therapeutically approached. Although this therapy has proven antitumor activity, its efficacy is not as expected. Here, we will review the main work on the identification of the role of Rheb in cell growth, and on the relevance of Rheb in proliferative disorders, including cancer. We will also review the Rheb functions that could explain tumor resistance to therapies with mTORC1 inhibitors, and will mainly focus our discussion on mTORC1-independent Rheb functions that could also be implicated in cancer cell survival and tumorigenesis. The current progress on the understanding of the noncanonical Rheb functions prompts future studies to establish their relevance in cancer and in the context of current cancer therapies.
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Affiliation(s)
- Marisol E Armijo
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad De Concepción, Concepción, Chile
| | - Tania Campos
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad De Concepción, Concepción, Chile
| | - Francisco Fuentes-Villalobos
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad De Concepción, Concepción, Chile
| | - Mario E Palma
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad De Concepción, Concepción, Chile
| | - Roxana Pincheira
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad De Concepción, Concepción, Chile
| | - Ariel F Castro
- Laboratorio de Transducción de Señales y Cáncer, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad De Concepción, Concepción, Chile
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48
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Chen YX, Koch S, Uhlenbrock K, Weise K, Das D, Gremer L, Brunsveld L, Wittinghofer A, Winter R, Triola G, Waldmann H. Synthesis of the Rheb and K-Ras4B GTPases. Angew Chem Int Ed Engl 2015; 49:6090-5. [PMID: 20652921 DOI: 10.1002/anie.201001884] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Yong-Xiang Chen
- Abteilung Chemische Biologie, Max-Planck-Institut für molekulare Physiologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
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49
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Dibble CC, Cantley LC. Regulation of mTORC1 by PI3K signaling. Trends Cell Biol 2015; 25:545-55. [PMID: 26159692 DOI: 10.1016/j.tcb.2015.06.002] [Citation(s) in RCA: 552] [Impact Index Per Article: 61.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 06/08/2015] [Accepted: 06/08/2015] [Indexed: 11/29/2022]
Abstract
The class I phosphoinositide 3-kinase (PI3K)-mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) signaling network directs cellular metabolism and growth. Activation of mTORC1 [composed of mTOR, regulatory-associated protein of mTOR (Raptor), mammalian lethal with SEC13 protein 8(mLST8), 40-kDa proline-rich Akt substrate (PRAS40), and DEP domain-containing mTOR-interacting protein (DEPTOR)] depends on the Ras-related GTPases (Rags) and Ras homolog enriched in brain (Rheb) GTPase and requires signals from amino acids, glucose, oxygen, energy (ATP), and growth factors (including cytokines and hormones such as insulin). Here we discuss the signal transduction mechanisms through which growth factor-responsive PI3K signaling activates mTORC1. We focus on how PI3K-dependent activation of Akt and spatial regulation of the tuberous sclerosis complex (TSC) complex (TSC complex) [composed of TSC1, TSC2, and Tre2-Bub2-Cdc16-1 domain family member 7 (TBC1D7)] switches on Rheb at the lysosome, where mTORC1 is activated. Integration of PI3K- and amino acid-dependent signals upstream of mTORC1 at the lysosome is detailed in a working model. A coherent understanding of the PI3K-mTORC1 network is imperative as its dysregulation has been implicated in diverse pathologies including cancer, diabetes, autism, and aging.
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Affiliation(s)
- Christian C Dibble
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Lewis C Cantley
- Meyer Cancer Center, Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA.
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Yoon MS, Rosenberger CL, Wu C, Truong N, Sweedler JV, Chen J. Rapid mitogenic regulation of the mTORC1 inhibitor, DEPTOR, by phosphatidic acid. Mol Cell 2015; 58:549-56. [PMID: 25936805 DOI: 10.1016/j.molcel.2015.03.028] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/23/2015] [Accepted: 03/23/2015] [Indexed: 02/06/2023]
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) is regulated, in part, by the endogenous inhibitor DEPTOR. However, the mechanism of DEPTOR regulation with regard to rapid mTORC1 activation remains unknown. We report that DEPTOR is rapidly and temporarily dissociated from mTORC1 upon mitogenic stimulation, suggesting a mechanism underlying acute mTORC1 activation. This mitogen-stimulated DEPTOR dissociation is blocked by inhibition or depletion of the mTORC1 regulator, phospholipase D (PLD), and recapitulated with the addition of the PLD product phosphatidic acid (PA). Our mass spectrometry analysis has independently identified DEPTOR as an mTOR binding partner dissociated by PA. Interestingly, only PA species with unsaturated fatty acid chains, such as those produced by PLD, are capable of displacing DEPTOR and activating mTORC1, with high affinity for the FRB domain of mTOR. Our findings reveal a mechanism of mTOR regulation and provide a molecular explanation for the exquisite specificity of PA function.
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Affiliation(s)
- Mee-Sup Yoon
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA; Department of Molecular Medicine, Graduate School of Medicine, Gachon University, Incheon 406-840, Republic of Korea.
| | - Christina L Rosenberger
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA
| | - Cong Wu
- Departments of Chemistry and Biochemistry, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA
| | - Nga Truong
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA
| | - Jonathan V Sweedler
- Departments of Chemistry and Biochemistry, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA
| | - Jie Chen
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA.
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