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Ragupathi A, Kim C, Jacinto E. The mTORC2 signaling network: targets and cross-talks. Biochem J 2024; 481:45-91. [PMID: 38270460 PMCID: PMC10903481 DOI: 10.1042/bcj20220325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/29/2023] [Accepted: 12/18/2023] [Indexed: 01/26/2024]
Abstract
The mechanistic target of rapamycin, mTOR, controls cell metabolism in response to growth signals and stress stimuli. The cellular functions of mTOR are mediated by two distinct protein complexes, mTOR complex 1 (mTORC1) and mTORC2. Rapamycin and its analogs are currently used in the clinic to treat a variety of diseases and have been instrumental in delineating the functions of its direct target, mTORC1. Despite the lack of a specific mTORC2 inhibitor, genetic studies that disrupt mTORC2 expression unravel the functions of this more elusive mTOR complex. Like mTORC1 which responds to growth signals, mTORC2 is also activated by anabolic signals but is additionally triggered by stress. mTORC2 mediates signals from growth factor receptors and G-protein coupled receptors. How stress conditions such as nutrient limitation modulate mTORC2 activation to allow metabolic reprogramming and ensure cell survival remains poorly understood. A variety of downstream effectors of mTORC2 have been identified but the most well-characterized mTORC2 substrates include Akt, PKC, and SGK, which are members of the AGC protein kinase family. Here, we review how mTORC2 is regulated by cellular stimuli including how compartmentalization and modulation of complex components affect mTORC2 signaling. We elaborate on how phosphorylation of its substrates, particularly the AGC kinases, mediates its diverse functions in growth, proliferation, survival, and differentiation. We discuss other signaling and metabolic components that cross-talk with mTORC2 and the cellular output of these signals. Lastly, we consider how to more effectively target the mTORC2 pathway to treat diseases that have deregulated mTOR signaling.
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Affiliation(s)
- Aparna Ragupathi
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, U.S.A
| | - Christian Kim
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, U.S.A
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, U.S.A
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2
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Okoh J, Mays J, Bacq A, Oses-Prieto JA, Tyanova S, Chen CJ, Imanbeyev K, Doladilhe M, Zhou H, Jafar-Nejad P, Burlingame A, Noebels J, Baulac S, Costa-Mattioli M. Targeted suppression of mTORC2 reduces seizures across models of epilepsy. Nat Commun 2023; 14:7364. [PMID: 37963879 PMCID: PMC10645975 DOI: 10.1038/s41467-023-42922-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 10/26/2023] [Indexed: 11/16/2023] Open
Abstract
Epilepsy is a neurological disorder that poses a major threat to public health. Hyperactivation of mTOR complex 1 (mTORC1) is believed to lead to abnormal network rhythmicity associated with epilepsy, and its inhibition is proposed to provide some therapeutic benefit. However, mTOR complex 2 (mTORC2) is also activated in the epileptic brain, and little is known about its role in seizures. Here we discover that genetic deletion of mTORC2 from forebrain neurons is protective against kainic acid-induced behavioral and EEG seizures. Furthermore, inhibition of mTORC2 with a specific antisense oligonucleotide robustly suppresses seizures in several pharmacological and genetic mouse models of epilepsy. Finally, we identify a target of mTORC2, Nav1.2, which has been implicated in epilepsy and neuronal excitability. Our findings, which are generalizable to several models of human seizures, raise the possibility that inhibition of mTORC2 may serve as a broader therapeutic strategy against epilepsy.
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Affiliation(s)
- James Okoh
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | - Jacqunae Mays
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
| | - Alexandre Bacq
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Juan A Oses-Prieto
- Departments of Chemistry and Pharmaceutical Chemistry, University of California San Fransisco, San Fransisco, CA, USA
| | - Stefka Tyanova
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | - Chien-Ju Chen
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Novartis Inc, Boston, MA, USA
| | - Khalel Imanbeyev
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
| | - Marion Doladilhe
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Hongyi Zhou
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | | | - Alma Burlingame
- Departments of Chemistry and Pharmaceutical Chemistry, University of California San Fransisco, San Fransisco, CA, USA
| | - Jeffrey Noebels
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Stephanie Baulac
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Mauro Costa-Mattioli
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA.
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA.
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3
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Ezine E, Lebbe C, Dumaz N. Unmasking the tumourigenic role of SIN1/MAPKAP1 in the mTOR complex 2. Clin Transl Med 2023; 13:e1464. [PMID: 37877351 PMCID: PMC10599286 DOI: 10.1002/ctm2.1464] [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: 04/11/2023] [Revised: 10/09/2023] [Accepted: 10/16/2023] [Indexed: 10/26/2023] Open
Abstract
BACKGROUND Although the PI3K/AKT/mTOR pathway is one of the most altered pathways in human tumours, therapies targeting this pathway have shown numerous adverse effects due to positive feedback paradoxically activating upstream signaling nodes. The somewhat limited clinical efficacy of these inhibitors calls for the development of novel and more effective approaches for targeting the PI3K pathway for therapeutic benefit in cancer. MAIN BODY Recent studies have shown the central role of mTOR complex 2 (mTORC2) as a pro-tumourigenic factor of the PI3K/AKT/mTOR pathway in a number of cancers. SIN1/MAPKAP1 is a major partner of mTORC2, acting as a scaffold and responsible for the substrate specificity of the mTOR catalytic subunit. Its overexpression promotes the proliferation, invasion and metastasis of certain cancers whereas its inhibition decreases tumour growth in vitro and in vivo. It is also involved in epithelial-mesenchymal transition, stress response and lipogenesis. Moreover, the numerous interactions of SIN1 inside or outside mTORC2 connect it with other signaling pathways, which are often disrupted in human tumours such as Hippo, WNT, Notch and MAPK. CONCLUSION Therefore, SIN1's fundamental characteristics and numerous connexions with oncogenic pathways make it a particularly interesting therapeutic target. This review is an opportunity to highlight the tumourigenic role of SIN1 across many solid cancers and demonstrates the importance of targeting SIN1 with a specific therapy.
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Affiliation(s)
- Emilien Ezine
- INSERMU976Team 1Human Immunology Pathophysiology & Immunotherapy (HIPI)ParisFrance
- Département de DermatologieHôpital Saint LouisAP‐HPParisFrance
| | - Céleste Lebbe
- INSERMU976Team 1Human Immunology Pathophysiology & Immunotherapy (HIPI)ParisFrance
- Département de DermatologieHôpital Saint LouisAP‐HPParisFrance
- Université Paris CitéInstitut de Recherche Saint Louis (IRSL)ParisFrance
| | - Nicolas Dumaz
- INSERMU976Team 1Human Immunology Pathophysiology & Immunotherapy (HIPI)ParisFrance
- Université Paris CitéInstitut de Recherche Saint Louis (IRSL)ParisFrance
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4
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Hanim A, Mohamed IN, Mohamed RMP, Mokhtar MH, Makpol S, Naomi R, Bahari H, Kamal H, Kumar J. Alcohol Dependence Modulates Amygdalar mTORC2 and PKCε Expression in a Rodent Model. Nutrients 2023; 15:3036. [PMID: 37447362 PMCID: PMC10346598 DOI: 10.3390/nu15133036] [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: 06/01/2023] [Revised: 06/24/2023] [Accepted: 06/25/2023] [Indexed: 07/15/2023] Open
Abstract
Multiple alcohol use disorder (AUD)-related behavioral alterations are governed by protein kinase C epsilon (PKCε), particularly in the amygdala. Protein kinase C (PKC) is readily phosphorylated at Ser729 before activation by the mTORC2 protein complex. In keeping with this, the current study was conducted to assess the variations in mTORC2 and PKCε during different ethanol exposure stages. The following groups of rats were employed: control, acute, chronic, ethanol withdrawal (EW), and EW + ethanol (EtOH). Ethanol-containing and non-ethanol-containing modified liquid diets (MLDs) were administered for 27 days. On day 28, either saline or ethanol (2.5 g/kg, 20% v/v) was intraperitoneally administered, followed by bilateral amygdala extraction. PKCε mRNA levels were noticeably increased in the amygdala of the EW + EtOH and EW groups. Following chronic ethanol consumption, the stress-activated map kinase-interacting protein 1 (Sin1) gene expression was markedly decreased. In the EW, EW + EtOH, and chronic ethanol groups, there was a profound increase in the protein expression of mTOR, Sin1, PKCε, and phosphorylated PKCε (Ser729). The PKCε gene and protein expressions showed a statistically significant moderate association, according to a correlation analysis. Our results suggest that an elevated PKCε protein expression in the amygdala during EW and EW + EtOH occurred at the transcriptional level. However, an elevation in the PKCε protein expression, but not its mRNA, after chronic ethanol intake warrants further investigation to fully understand the signaling pathways during different episodes of AUD.
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Affiliation(s)
- Athirah Hanim
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia; (A.H.); (M.H.M.); (H.K.)
| | - Isa N. Mohamed
- Department of Pharmacology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia;
| | - Rashidi M. P. Mohamed
- Department of Family Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia;
| | - Mohd Helmy Mokhtar
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia; (A.H.); (M.H.M.); (H.K.)
| | - Suzana Makpol
- Department of Biochemistry, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia;
| | - Ruth Naomi
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia; (R.N.); (H.B.)
| | - Hasnah Bahari
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia; (R.N.); (H.B.)
| | - Haziq Kamal
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia; (A.H.); (M.H.M.); (H.K.)
| | - Jaya Kumar
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia; (A.H.); (M.H.M.); (H.K.)
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5
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Martinez-Lopez N, Mattar P, Toledo M, Bains H, Kalyani M, Aoun ML, Sharma M, McIntire LBJ, Gunther-Cummins L, Macaluso FP, Aguilan JT, Sidoli S, Bourdenx M, Singh R. mTORC2-NDRG1-CDC42 axis couples fasting to mitochondrial fission. Nat Cell Biol 2023:10.1038/s41556-023-01163-3. [PMID: 37386153 PMCID: PMC10344787 DOI: 10.1038/s41556-023-01163-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 05/04/2023] [Indexed: 07/01/2023]
Abstract
Fasting triggers diverse physiological adaptations including increases in circulating fatty acids and mitochondrial respiration to facilitate organismal survival. The mechanisms driving mitochondrial adaptations and respiratory sufficiency during fasting remain incompletely understood. Here we show that fasting or lipid availability stimulates mTORC2 activity. Activation of mTORC2 and phosphorylation of its downstream target NDRG1 at serine 336 sustains mitochondrial fission and respiratory sufficiency. Time-lapse imaging shows that NDRG1, but not the phosphorylation-deficient NDRG1Ser336Ala mutant, engages with mitochondria to facilitate fission in control cells, as well as in those lacking DRP1. Using proteomics, a small interfering RNA screen, and epistasis experiments, we show that mTORC2-phosphorylated NDRG1 cooperates with small GTPase CDC42 and effectors and regulators of CDC42 to orchestrate fission. Accordingly, RictorKO, NDRG1Ser336Ala mutants and Cdc42-deficient cells each display mitochondrial phenotypes reminiscent of fission failure. During nutrient surplus, mTOR complexes perform anabolic functions; however, paradoxical reactivation of mTORC2 during fasting unexpectedly drives mitochondrial fission and respiration.
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Affiliation(s)
- Nuria Martinez-Lopez
- Department of Medicine, University of California Los Angeles, Los Angeles, CA, USA
- Vatche and Tamar Manoukian Division of Digestive Diseases, University of California Los Angeles, Los Angeles, CA, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
- Liver Basic Research Center at University of California Los Angeles, Los Angeles, CA, USA
| | - Pamela Mattar
- Department of Medicine, University of California Los Angeles, Los Angeles, CA, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Miriam Toledo
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
- Neuronal Control of Metabolism Laboratory, Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Henrietta Bains
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Manu Kalyani
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Marie Louise Aoun
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Mridul Sharma
- Department of Medicine, University of California Los Angeles, Los Angeles, CA, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
| | | | - Leslie Gunther-Cummins
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Frank P Macaluso
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Jennifer T Aguilan
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Simone Sidoli
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Mathieu Bourdenx
- UK Dementia Research Institute, London, UK
- UCL Queen Square Institute of Neurology, London, UK
| | - Rajat Singh
- Department of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
- Vatche and Tamar Manoukian Division of Digestive Diseases, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA.
- Liver Basic Research Center at University of California Los Angeles, Los Angeles, CA, USA.
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA.
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6
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Saha B, Shabbir W, Takagi E, Duan XP, Leite Dellova DCA, Demko J, Manis A, Loffing-Cueni D, Loffing J, Sørensen MV, Wang WH, Pearce D. Potassium Activates mTORC2-dependent SGK1 Phosphorylation to Stimulate Epithelial Sodium Channel: Role in Rapid Renal Responses to Dietary Potassium. J Am Soc Nephrol 2023; 34:1019-1038. [PMID: 36890646 PMCID: PMC10278851 DOI: 10.1681/asn.0000000000000109] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 02/06/2023] [Indexed: 03/10/2023] Open
Abstract
SIGNIFICANCE STATEMENT Rapid renal responses to ingested potassium are essential to prevent hyperkalemia and also play a central role in blood pressure regulation. Although local extracellular K + concentration in kidney tissue is increasingly recognized as an important regulator of K + secretion, the underlying mechanisms that are relevant in vivo remain controversial. To assess the role of the signaling kinase mTOR complex-2 (mTORC2), the authors compared the effects of K + administered by gavage in wild-type mice and knockout mice with kidney tubule-specific inactivation of mTORC2. They found that mTORC2 is rapidly activated to trigger K + secretion and maintain electrolyte homeostasis. Downstream targets of mTORC2 implicated in epithelial sodium channel regulation (SGK1 and Nedd4-2) were concomitantly phosphorylated in wild-type, but not knockout, mice. These findings offer insight into electrolyte physiologic and regulatory mechanisms. BACKGROUND Increasing evidence implicates the signaling kinase mTOR complex-2 (mTORC2) in rapid renal responses to changes in plasma potassium concentration [K + ]. However, the underlying cellular and molecular mechanisms that are relevant in vivo for these responses remain controversial. METHODS We used Cre-Lox-mediated knockout of rapamycin-insensitive companion of TOR (Rictor) to inactivate mTORC2 in kidney tubule cells of mice. In a series of time-course experiments in wild-type and knockout mice, we assessed urinary and blood parameters and renal expression and activity of signaling molecules and transport proteins after a K + load by gavage. RESULTS A K + load rapidly stimulated epithelial sodium channel (ENaC) processing, plasma membrane localization, and activity in wild-type, but not in knockout, mice. Downstream targets of mTORC2 implicated in ENaC regulation (SGK1 and Nedd4-2) were concomitantly phosphorylated in wild-type, but not knockout, mice. We observed differences in urine electrolytes within 60 minutes, and plasma [K + ] was greater in knockout mice within 3 hours of gavage. Renal outer medullary potassium (ROMK) channels were not acutely stimulated in wild-type or knockout mice, nor were phosphorylation of other mTORC2 substrates (PKC and Akt). CONCLUSIONS The mTORC2-SGK1-Nedd4-2-ENaC signaling axis is a key mediator of rapid tubule cell responses to increased plasma [K + ] in vivo . The effects of K + on this signaling module are specific, in that other downstream mTORC2 targets, such as PKC and Akt, are not acutely affected, and ROMK and Large-conductance K + (BK) channels are not activated. These findings provide new insight into the signaling network and ion transport systems that underlie renal responses to K +in vivo .
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Affiliation(s)
- Bidisha Saha
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Waheed Shabbir
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Enzo Takagi
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Xin-Peng Duan
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Deise Carla Almeida Leite Dellova
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
- Current address: Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga, Sao Paulo, Brazil
| | - John Demko
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Anna Manis
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | | | | | - Mads Vaarby Sørensen
- Department of Biomedicine, Unit of Physiology, Aarhus University, Aarhus, Denmark
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - David Pearce
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
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7
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Fricke AL, Mühlhäuser WWD, Reimann L, Zimmermann JP, Reichenbach C, Knapp B, Peikert CD, Heberle AM, Faessler E, Schäuble S, Hahn U, Thedieck K, Radziwill G, Warscheid B. Phosphoproteomics Profiling Defines a Target Landscape of the Basophilic Protein Kinases AKT, S6K, and RSK in Skeletal Myotubes. J Proteome Res 2023; 22:768-789. [PMID: 36763541 DOI: 10.1021/acs.jproteome.2c00505] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Phosphorylation-dependent signal transduction plays an important role in regulating the functions and fate of skeletal muscle cells. Central players in the phospho-signaling network are the protein kinases AKT, S6K, and RSK as part of the PI3K-AKT-mTOR-S6K and RAF-MEK-ERK-RSK pathways. However, despite their functional importance, knowledge about their specific targets is incomplete because these kinases share the same basophilic substrate motif RxRxxp[ST]. To address this, we performed a multifaceted quantitative phosphoproteomics study of skeletal myotubes following kinase inhibition. Our data corroborate a cross talk between AKT and RAF, a negative feedback loop of RSK on ERK, and a putative connection between RSK and PI3K signaling. Altogether, we report a kinase target landscape containing 49 so far unknown target sites. AKT, S6K, and RSK phosphorylate numerous proteins involved in muscle development, integrity, and functions, and signaling converges on factors that are central for the skeletal muscle cytoskeleton. Whereas AKT controls insulin signaling and impinges on GTPase signaling, nuclear signaling is characteristic for RSK. Our data further support a role of RSK in glucose metabolism. Shared targets have functions in RNA maturation, stability, and translation, which suggests that these basophilic kinases establish an intricate signaling network to orchestrate and regulate processes involved in translation.
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Affiliation(s)
- Anna L Fricke
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.,Biochemistry II, Theodor Boveri-Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Wignand W D Mühlhäuser
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Lena Reimann
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Johannes P Zimmermann
- Biochemistry II, Theodor Boveri-Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Christa Reichenbach
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Bettina Knapp
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Christian D Peikert
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Alexander M Heberle
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, 6020 Innsbruck, Austria
| | - Erik Faessler
- Jena University Language & Information Engineering (JULIE) Lab, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Sascha Schäuble
- Jena University Language & Information Engineering (JULIE) Lab, Friedrich Schiller University Jena, 07743 Jena, Germany.,Systems Biology and Bioinformatics Unit, Leibniz Institute for Natural Product Research and Infection Biology─Leibniz-HKI, 07745 Jena, Germany
| | - Udo Hahn
- Jena University Language & Information Engineering (JULIE) Lab, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Kathrin Thedieck
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, 6020 Innsbruck, Austria.,Department of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen 9700 RB, The Netherlands.,Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg 26129, Germany
| | - Gerald Radziwill
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, 79104 Freiburg, Germany
| | - Bettina Warscheid
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.,Biochemistry II, Theodor Boveri-Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, 79104 Freiburg, Germany
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8
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H’ng CH, Khaladkar A, Rosello-Diez A. Look who's TORking: mTOR-mediated integration of cell status and external signals during limb development and endochondral bone growth. Front Cell Dev Biol 2023; 11:1153473. [PMID: 37152288 PMCID: PMC10154674 DOI: 10.3389/fcell.2023.1153473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 04/03/2023] [Indexed: 05/09/2023] Open
Abstract
The balance of cell proliferation and size is key for the control of organ development and repair. Moreover, this balance has to be coordinated within tissues and between tissues to achieve robustness in the organ's pattern and size. The tetrapod limb has been used to study these topics during development and repair, and several conserved pathways have emerged. Among them, mechanistic target of rapamycin (mTOR) signaling, despite being active in several cell types and developmental stages, is one of the least understood in limb development, perhaps because of its multiple potential roles and interactions with other pathways. In the body of this review, we have collated and integrated what is known about the role of mTOR signaling in three aspects of tetrapod limb development: 1) limb outgrowth; 2) chondrocyte differentiation after mesenchymal condensation and 3) endochondral ossification-driven longitudinal bone growth. We conclude that, given its ability to interact with the most common signaling pathways, its presence in multiple cell types, and its ability to influence cell proliferation, size and differentiation, the mTOR pathway is a critical integrator of external stimuli and internal status, coordinating developmental transitions as complex as those taking place during limb development. This suggests that the study of the signaling pathways and transcription factors involved in limb patterning, morphogenesis and growth could benefit from probing the interaction of these pathways with mTOR components.
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Affiliation(s)
- Chee Ho H’ng
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC, Australia
| | - Ashwini Khaladkar
- Department of Biochemistry, Central University of Hyderabad, Hyderabad, India
| | - Alberto Rosello-Diez
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC, Australia
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
- *Correspondence: Alberto Rosello-Diez, ,
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9
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Saha B, Leite-Dellova DCA, Demko J, Sørensen MV, Takagi E, Gleason CE, Shabbir W, Pearce D. WNK1 is a chloride-stimulated scaffold that regulates mTORC2 activity and ion transport. J Cell Sci 2022; 135:jcs260313. [PMID: 36373794 PMCID: PMC9789407 DOI: 10.1242/jcs.260313] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 10/26/2022] [Indexed: 11/16/2022] Open
Abstract
Mammalian (or mechanistic) target of rapamycin complex 2 (mTORC2) is a kinase complex that targets predominantly Akt family proteins, SGK1 and protein kinase C (PKC), and has well-characterized roles in mediating hormone and growth factor effects on a wide array of cellular processes. Recent evidence suggests that mTORC2 is also directly stimulated in renal tubule cells by increased extracellular K+ concentration, leading to activation of the Na+ channel, ENaC, and increasing the electrical driving force for K+ secretion. We identify here a signaling mechanism for this local effect of K+. We show that an increase in extracellular [K+] leads to a rise in intracellular chloride (Cl-), which stimulates a previously unknown scaffolding activity of the protein 'with no lysine-1' (WNK1) kinase. WNK1 interacts selectively with SGK1 and recruits it to mTORC2, resulting in enhanced SGK1 phosphorylation and SGK1-dependent activation of ENaC. This scaffolding effect of WNK1 is independent of its own kinase activity and does not cause a generalized stimulation of mTORC2 kinase activity. These findings establish a novel WNK1-dependent regulatory mechanism that harnesses mTORC2 kinase activity selectively toward SGK1 to control epithelial ion transport and electrolyte homeostasis.
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Affiliation(s)
- Bidisha Saha
- Division of Nephrology, Departments of Medicine and Cellular & Molecular Pharmacology,University of California at San Francisco, San Francisco, CA 94158, USA
| | - Deise C. A. Leite-Dellova
- Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga, Sao Paulo 13635-900, Brazil
| | - John Demko
- Division of Nephrology, Departments of Medicine and Cellular & Molecular Pharmacology,University of California at San Francisco, San Francisco, CA 94158, USA
| | - Mads Vaarby Sørensen
- Departments of Biomedicine and Physiology, Aarhus University, 8000 Aarhus C, Denmark
| | - Enzo Takagi
- Division of Nephrology, Departments of Medicine and Cellular & Molecular Pharmacology,University of California at San Francisco, San Francisco, CA 94158, USA
| | - Catherine E. Gleason
- Division of Nephrology, Departments of Medicine and Cellular & Molecular Pharmacology,University of California at San Francisco, San Francisco, CA 94158, USA
| | - Waheed Shabbir
- Division of Nephrology, Departments of Medicine and Cellular & Molecular Pharmacology,University of California at San Francisco, San Francisco, CA 94158, USA
| | - David Pearce
- Division of Nephrology, Departments of Medicine and Cellular & Molecular Pharmacology,University of California at San Francisco, San Francisco, CA 94158, USA
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10
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Thorner J. TOR complex 2 is a master regulator of plasma membrane homeostasis. Biochem J 2022; 479:1917-1940. [PMID: 36149412 PMCID: PMC9555796 DOI: 10.1042/bcj20220388] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/17/2022]
Abstract
As first demonstrated in budding yeast (Saccharomyces cerevisiae), all eukaryotic cells contain two, distinct multi-component protein kinase complexes that each harbor the TOR (Target Of Rapamycin) polypeptide as the catalytic subunit. These ensembles, dubbed TORC1 and TORC2, function as universal, centrally important sensors, integrators, and controllers of eukaryotic cell growth and homeostasis. TORC1, activated on the cytosolic surface of the lysosome (or, in yeast, on the cytosolic surface of the vacuole), has emerged as a primary nutrient sensor that promotes cellular biosynthesis and suppresses autophagy. TORC2, located primarily at the plasma membrane, plays a major role in maintaining the proper levels and bilayer distribution of all plasma membrane components (sphingolipids, glycerophospholipids, sterols, and integral membrane proteins). This article surveys what we have learned about signaling via the TORC2 complex, largely through studies conducted in S. cerevisiae. In this yeast, conditions that challenge plasma membrane integrity can, depending on the nature of the stress, stimulate or inhibit TORC2, resulting in, respectively, up-regulation or down-regulation of the phosphorylation and thus the activity of its essential downstream effector the AGC family protein kinase Ypk1. Through the ensuing effect on the efficiency with which Ypk1 phosphorylates multiple substrates that control diverse processes, membrane homeostasis is maintained. Thus, the major focus here is on TORC2, Ypk1, and the multifarious targets of Ypk1 and how the functions of these substrates are regulated by their Ypk1-mediated phosphorylation, with emphasis on recent advances in our understanding of these processes.
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Affiliation(s)
- Jeremy Thorner
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, U.S.A
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11
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Yu Z, Chen J, Takagi E, Wang F, Saha B, Liu X, Joubert LM, Gleason CE, Jin M, Li C, Nowotny C, Agard D, Cheng Y, Pearce D. Interactions between mTORC2 core subunits Rictor and mSin1 dictate selective and context-dependent phosphorylation of substrate kinases SGK1 and Akt. J Biol Chem 2022; 298:102288. [PMID: 35926713 PMCID: PMC9440446 DOI: 10.1016/j.jbc.2022.102288] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 07/04/2022] [Accepted: 07/05/2022] [Indexed: 12/02/2022] Open
Abstract
Mechanistic target of rapamycin complex 2 (mTORC2) is a multi-subunit kinase complex, central to multiple essential signaling pathways. Two core subunits, Rictor and mSin1, distinguish it from the related mTORC1 and support context-dependent phosphorylation of its substrates. mTORC2 structures have been determined previously; however, important questions remain, particularly regarding the structural determinants mediating substrate specificity and context-dependent activity. Here, we used cryo-EM to obtain high-resolution structures of the human mTORC2 apo-complex in the presence of substrates Akt and SGK1. Using functional assays, we then tested predictions suggested by substrate-induced structural changes in mTORC2. For the first time, we visualized in the apo-state the side chain interactions between Rictor and mTOR that sterically occlude recruitment of mTORC1 substrates and confer resistance to the mTORC1 inhibitor rapamycin. Also in the apo-state, we observed that mSin1 formed extensive contacts with Rictor via a pair of short α-helices nestled between two Rictor helical repeat clusters, as well as by an extended strand that makes multiple weak contacts with Rictor helical cluster 1. In co-complex structures, we found that SGK1, but not Akt, markedly altered the conformation of the mSin1 N-terminal extended strand, disrupting multiple weak interactions while inducing a large rotation of mSin1 residue Arg-83, which then interacts with a patch of negatively charged residues within Rictor. Finally, we demonstrate mutation of Arg-83 to Ala selectively disrupts mTORC2-dependent phosphorylation of SGK1, but not of Akt, supporting context-dependent substrate selection. These findings provide new structural and functional insights into mTORC2 specificity and context-dependent activity.
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Affiliation(s)
- Zanlin Yu
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA
| | - Junliang Chen
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, UCSF, San Francisco, California, USA
| | - Enzo Takagi
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, UCSF, San Francisco, California, USA
| | - Feng Wang
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA
| | - Bidisha Saha
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, UCSF, San Francisco, California, USA
| | - Xi Liu
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, USA
| | - Lydia-Marie Joubert
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California, USA
| | - Catherine E Gleason
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, UCSF, San Francisco, California, USA
| | - Mingliang Jin
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA
| | - Chengmin Li
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA
| | - Carlos Nowotny
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA
| | - David Agard
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA; Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, USA
| | - David Pearce
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, UCSF, San Francisco, California, USA.
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12
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Pilo CA, Newton AC. Two Sides of the Same Coin: Protein Kinase C γ in Cancer and Neurodegeneration. Front Cell Dev Biol 2022; 10:929510. [PMID: 35800893 PMCID: PMC9253466 DOI: 10.3389/fcell.2022.929510] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 05/23/2022] [Indexed: 12/23/2022] Open
Abstract
Protein kinase C (PKC) isozymes transduce myriad signals within the cell in response to the generation of second messengers from membrane phospholipids. The conventional isozyme PKCγ reversibly binds Ca2+ and diacylglycerol, which leads to an open, active conformation. PKCγ expression is typically restricted to neurons, but evidence for its expression in certain cancers has emerged. PKC isozymes have been labeled as oncogenes since the discovery that they bind tumor-promoting phorbol esters, however, studies of cancer-associated PKC mutations and clinical trial data showing that PKC inhibitors have worsened patient survival have reframed PKC as a tumor suppressor. Aberrant expression of PKCγ in certain cancers suggests a role outside the brain, although whether PKCγ also acts as a tumor suppressor remains to be established. On the other hand, PKCγ variants associated with spinocerebellar ataxia type 14 (SCA14), a neurodegenerative disorder characterized by Purkinje cell degeneration, enhance basal activity while preventing phorbol ester-mediated degradation. Although the basis for SCA14 Purkinje cell degeneration remains unknown, studies have revealed how altered PKCγ activity rewires cerebellar signaling to drive SCA14. Importantly, enhanced basal activity of SCA14-associated mutants inversely correlates with age of onset, supporting that enhanced PKCγ activity drives SCA14. Thus, PKCγ activity should likely be inhibited in SCA14, whereas restoring PKC activity should be the goal in cancer therapies. This review describes how PKCγ activity can be lost or gained in disease and the overarching need for a PKC structure as a powerful tool to predict the effect of PKCγ mutations in disease.
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Affiliation(s)
- Caila A. Pilo
- Department of Pharmacology, University of California, San Diego, San Diego, CA, United States
- Biomedical Sciences Graduate Program, University of California, San Diego, San Diego, CA, United States
| | - Alexandra C. Newton
- Department of Pharmacology, University of California, San Diego, San Diego, CA, United States
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13
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Baffi TR, Newton AC. Protein kinase C: release from quarantine by mTORC2. Trends Biochem Sci 2022; 47:518-530. [DOI: 10.1016/j.tibs.2022.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 02/14/2022] [Accepted: 03/02/2022] [Indexed: 01/31/2023]
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14
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Ni L, Wei Y, Pan J, Li X, Xu B, Deng Y, Yang T, Liu W. Shedding New Light on Methylmercury-induced Neurotoxicity Through the Crosstalk Between Autophagy and Apoptosis. Toxicol Lett 2022; 359:55-64. [PMID: 35122893 DOI: 10.1016/j.toxlet.2022.01.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 11/23/2021] [Accepted: 01/29/2022] [Indexed: 02/06/2023]
Abstract
Methylmercury (MeHg) is a bio-accumulative global environmental contaminant present in fish and seafood. MeHg accumulates in the aquatic environment and eventually reaches the human system via the food chain by bio-magnification. The central nervous system is the primary target of toxicity and is particularly vulnerable during development. It is well documented that developmental MeHg exposure can lead to neurological alterations, including cognitive and motor dysfunction. Apoptosis is a primary characteristic of MeHg-induced neurotoxicity, and may be regulated by autophagic activity. However, mechanisms mediating the interaction between apoptosis and autophagy remains to be explored. Autophagy is an adaptive response under stressful conditions, and the basal level of autophagy ensures the physiological turnover of old and damaged organelles. Autophagy can regulate cell fate through different crosstalk signaling pathways. A complex interplay between autophagy and apoptosis determines the degree of apoptosis and the progression of MeHg-induced neurotoxicity as demonstrated by pre-clinical models and clinical trials. This review summarizes recent advances in the roles of autophagy and apoptosis in MeHg neurotoxicity and thoroughly explores the relationship between them. The autophagic pathway may be a potential therapeutic target in MeHg neurotoxicity through modulation of apoptosis.
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Affiliation(s)
- Linlin Ni
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, People's Republic of China
| | - Yanfeng Wei
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, People's Republic of China
| | - Jingjing Pan
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, People's Republic of China
| | - Xiaoyang Li
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, People's Republic of China
| | - Bin Xu
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, People's Republic of China
| | - Yu Deng
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, People's Republic of China
| | - Tianyao Yang
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, People's Republic of China
| | - Wei Liu
- Department of Environmental Health, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, Liaoning, People's Republic of China.
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15
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Morozumi Y, Hishinuma A, Furusawa S, Sofyantoro F, Tatebe H, Shiozaki K. Fission yeast TOR complex 1 phosphorylates Psk1 through an evolutionarily conserved interaction mediated by the TOS motif. J Cell Sci 2021; 134:272450. [PMID: 34499159 PMCID: PMC8542387 DOI: 10.1242/jcs.258865] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 09/03/2021] [Indexed: 12/28/2022] Open
Abstract
TOR complex 1 (TORC1) is a multi-subunit protein kinase complex that controls cellular growth in response to environmental cues. The regulatory subunits of mammalian TORC1 (mTORC1) include RAPTOR (also known as RPTOR), which recruits mTORC1 substrates, such as S6K1 (also known as RPS6KB1) and 4EBP1 (EIF4EBP1), by interacting with their TOR signaling (TOS) motif. Despite the evolutionary conservation of TORC1, no TOS motif has been described in lower eukaryotes. In the present study, we show that the fission yeast S6 kinase Psk1 contains a TOS motif that interacts with Mip1, a RAPTOR ortholog. The TOS motif in Psk1 resembles those in mammals, including the conserved phenylalanine and aspartic acid residues essential for the Mip1 interaction and TORC1-dependent phosphorylation of Psk1. The binding of the TOS motif to Mip1 is dependent on Mip1 Tyr-533, whose equivalent in RAPTOR is known to interact with the TOS motif in their co-crystals. Furthermore, we utilized the mip1-Y533A mutation to screen the known TORC1 substrates in fission yeast and successfully identified Atg13 as a novel TOS-motif-containing substrate. These results strongly suggest that the TOS motif represents an evolutionarily conserved mechanism of the substrate recognition by TORC1. Summary: By analyzing S6 kinase in fission yeast, we have demonstrated that the TOR signaling (TOS) motif-mediated substrate recognition by TOR complex 1 is conserved from yeast to humans.
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Affiliation(s)
- Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Ai Hishinuma
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.,Tohoku Agricultural Research Center, National Agriculture and Food Research Organization, Daisen, Akita 019-2112, Japan
| | - Suguru Furusawa
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Fajar Sofyantoro
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.,Department of Animal Physiology, Faculty of Biology, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia
| | - Hisashi Tatebe
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.,Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA
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16
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Holmes B, Benavides-Serrato A, Saunders JT, Kumar S, Nishimura RN, Gera J. mTORC2-mediated direct phosphorylation regulates YAP activity promoting glioblastoma growth and invasive characteristics. Neoplasia 2021; 23:951-965. [PMID: 34343821 PMCID: PMC8347669 DOI: 10.1016/j.neo.2021.07.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/08/2021] [Accepted: 07/12/2021] [Indexed: 11/24/2022]
Abstract
The Hippo and mTOR signaling cascades are major regulators of cell growth and division. Aberrant regulation of these pathways has been demonstrated to contribute to gliomagenesis and result in enhanced glioblastoma proliferation and invasive characteristics. Several crosstalk mechanisms have been described between these two pathways, although a complete picture of these signaling interactions is lacking and is required for effective therapeutic targeting. Here we report the ability of mTORC2 to directly phosphorylate YAP at serine 436 (Ser436) positively regulating YAP activity. We show that mTORC2 activity enhances YAP transcriptional activity and the induction of YAP-dependent target gene expression while its ablation via genetic or pharmacological means has the opposite affects on YAP function. mTORC2 interacts with YAP via Sin1 and mutational analysis of serine 436 demonstrates that this phosphorylation event affects several properties of YAP leading to enhanced transactivation potential. Moreover, YAP serine 436 mutants display altered glioblastoma growth, migratory capacity and invasiveness both in vitro and in xenograft experiments. We further demonstrate that mTORC2 is able to regulate a Hippo pathway resistant allele of YAP suggesting that mTORC2 can regulate YAP independent of Hippo signaling. Correlative associations between the expression of these components in GBM patient samples also supported the presence of this signaling relationship. These results advance a direct mTORC2/YAP signaling axis driving GBM growth, motility and invasiveness.
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Affiliation(s)
- Brent Holmes
- Departments of Medicine; Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CL
| | - Angelica Benavides-Serrato
- Departments of Medicine; Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CL
| | - Jacquelyn T Saunders
- Departments of Medicine; Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CL
| | - Sunil Kumar
- Department of Pharmaceutical and Biomedical Sciences, California Health Sciences University, Clovis, CL; Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CL
| | - Robert N Nishimura
- Neurology, David Geffen School of Medicine at UCLA; Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CL
| | - Joseph Gera
- Departments of Medicine; Jonnson Comprehensive Cancer Center; Molecular Biology Institute, University of California-Los Angeles, CL; Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CL.
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17
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Castel P, Dharmaiah S, Sale MJ, Messing S, Rizzuto G, Cuevas-Navarro A, Cheng A, Trnka MJ, Urisman A, Esposito D, Simanshu DK, McCormick F. RAS interaction with Sin1 is dispensable for mTORC2 assembly and activity. Proc Natl Acad Sci U S A 2021; 118:e2103261118. [PMID: 34380736 PMCID: PMC8379911 DOI: 10.1073/pnas.2103261118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
RAS proteins are molecular switches that interact with effector proteins when bound to guanosine triphosphate, stimulating downstream signaling in response to multiple stimuli. Although several canonical downstream effectors have been extensively studied and tested as potential targets for RAS-driven cancers, many of these remain poorly characterized. In this study, we undertook a biochemical and structural approach to further study the role of Sin1 as a RAS effector. Sin1 interacted predominantly with KRAS isoform 4A in cells through an atypical RAS-binding domain that we have characterized by X-ray crystallography. Despite the essential role of Sin1 in the assembly and activity of mTORC2, we find that the interaction with RAS is not required for these functions. Cells and mice expressing a mutant of Sin1 that is unable to bind RAS are proficient for activation and assembly of mTORC2. Our results suggest that Sin1 is a bona fide RAS effector that regulates downstream signaling in an mTORC2-independent manner.
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Affiliation(s)
- Pau Castel
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
| | - Srisathiyanarayanan Dharmaiah
- National Cancer Institute (NCI) RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702
| | - Matthew J Sale
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
| | - Simon Messing
- National Cancer Institute (NCI) RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702
| | - Gabrielle Rizzuto
- Department of Anatomic Pathology, University of California, San Francisco, CA 94158
| | - Antonio Cuevas-Navarro
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
| | - Alice Cheng
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158
| | - Michael J Trnka
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158
| | - Anatoly Urisman
- Department of Anatomic Pathology, University of California, San Francisco, CA 94158
| | - Dominic Esposito
- National Cancer Institute (NCI) RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702
| | - Dhirendra K Simanshu
- National Cancer Institute (NCI) RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702;
| | - Frank McCormick
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158;
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18
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Ballesteros‐Álvarez J, Andersen JK. mTORC2: The other mTOR in autophagy regulation. Aging Cell 2021; 20:e13431. [PMID: 34250734 PMCID: PMC8373318 DOI: 10.1111/acel.13431] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 06/15/2021] [Accepted: 06/24/2021] [Indexed: 12/13/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) has gathered significant attention as a ubiquitously expressed multimeric kinase with key implications for cell growth, proliferation, and survival. This kinase forms the central core of two distinct complexes, mTORC1 and mTORC2, which share the ability of integrating environmental, nutritional, and hormonal cues but which regulate separate molecular pathways that result in different cellular responses. Particularly, mTORC1 has been described as a major negative regulator of endosomal biogenesis and autophagy, a catabolic process that degrades intracellular components and organelles within the lysosomes and is thought to play a key role in human health and disease. In contrast, the role of mTORC2 in the regulation of autophagy has been considerably less studied despite mounting evidence this complex may regulate autophagy in a different and perhaps complementary manner to that of mTORC1. Genetic ablation of unique subunits is currently being utilized to study the differential effects of the two mTOR complexes. RICTOR is the best‐described subunit specific to mTORC2 and as such has become a useful tool for investigating the specific actions of this complex. The development of complex‐specific inhibitors for mTORC2 is also an area of intense interest. Studies to date have demonstrated that mTORC1/2 complexes each signal to a variety of exclusive downstream molecules with distinct biological roles. Pinpointing the particular effects of these downstream effectors is crucial toward the development of novel therapies aimed at accurately modulating autophagy in the context of human aging and disease.
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19
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Baffi TR, Lordén G, Wozniak JM, Feichtner A, Yeung W, Kornev AP, King CC, Del Rio JC, Limaye AJ, Bogomolovas J, Gould CM, Chen J, Kennedy EJ, Kannan N, Gonzalez DJ, Stefan E, Taylor SS, Newton AC. mTORC2 controls the activity of PKC and Akt by phosphorylating a conserved TOR interaction motif. Sci Signal 2021; 14:eabe4509. [PMID: 33850054 PMCID: PMC8208635 DOI: 10.1126/scisignal.abe4509] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The complex mTORC2 is accepted to be the kinase that controls the phosphorylation of the hydrophobic motif, a key regulatory switch for AGC kinases, although whether mTOR directly phosphorylates this motif remains controversial. Here, we identified an mTOR-mediated phosphorylation site that we termed the TOR interaction motif (TIM; F-x3-F-pT), which controls the phosphorylation of the hydrophobic motif of PKC and Akt and the activity of these kinases. The TIM is invariant in mTORC2-dependent AGC kinases, is evolutionarily conserved, and coevolved with mTORC2 components. Mutation of this motif in Akt1 and PKCβII abolished cellular kinase activity by impairing activation loop and hydrophobic motif phosphorylation. mTORC2 directly phosphorylated the PKC TIM in vitro, and this phosphorylation event was detected in mouse brain. Overexpression of PDK1 in mTORC2-deficient cells rescued hydrophobic motif phosphorylation of PKC and Akt by a mechanism dependent on their intrinsic catalytic activity, revealing that mTORC2 facilitates the PDK1 phosphorylation step, which, in turn, enables autophosphorylation. Structural analysis revealed that PKC homodimerization is driven by a TIM-containing helix, and biophysical proximity assays showed that newly synthesized, unphosphorylated PKC dimerizes in cells. Furthermore, disruption of the dimer interface by stapled peptides promoted hydrophobic motif phosphorylation. Our data support a model in which mTORC2 relieves nascent PKC dimerization through TIM phosphorylation, recruiting PDK1 to phosphorylate the activation loop and triggering intramolecular hydrophobic motif autophosphorylation. Identification of TIM phosphorylation and its role in the regulation of PKC provides the basis for AGC kinase regulation by mTORC2.
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Affiliation(s)
- Timothy R Baffi
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Gema Lordén
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
| | - Jacob M Wozniak
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, CA 92093, USA
| | - Andreas Feichtner
- Institute of Biochemistry and Center for Molecular Biosciences, University of Innsbruck, Innsbruck A-6020, Austria
| | - Wayland Yeung
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Alexandr P Kornev
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
| | - Charles C King
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
| | - Jason C Del Rio
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Ameya J Limaye
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA 30602, USA
| | - Julius Bogomolovas
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Christine M Gould
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Ju Chen
- Department of Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Eileen J Kennedy
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA 30602, USA
| | - Natarajan Kannan
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - David J Gonzalez
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, CA 92093, USA
| | - Eduard Stefan
- Institute of Biochemistry and Center for Molecular Biosciences, University of Innsbruck, Innsbruck A-6020, Austria
| | - Susan S Taylor
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093, USA
| | - Alexandra C Newton
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA.
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20
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Abstract
Cells metabolize nutrients for biosynthetic and bioenergetic needs to fuel growth and proliferation. The uptake of nutrients from the environment and their intracellular metabolism is a highly controlled process that involves cross talk between growth signaling and metabolic pathways. Despite constant fluctuations in nutrient availability and environmental signals, normal cells restore metabolic homeostasis to maintain cellular functions and prevent disease. A central signaling molecule that integrates growth with metabolism is the mechanistic target of rapamycin (mTOR). mTOR is a protein kinase that responds to levels of nutrients and growth signals. mTOR forms two protein complexes, mTORC1, which is sensitive to rapamycin, and mTORC2, which is not directly inhibited by this drug. Rapamycin has facilitated the discovery of the various functions of mTORC1 in metabolism. Genetic models that disrupt either mTORC1 or mTORC2 have expanded our knowledge of their cellular, tissue, as well as systemic functions in metabolism. Nevertheless, our knowledge of the regulation and functions of mTORC2, particularly in metabolism, has lagged behind. Since mTOR is an important target for cancer, aging, and other metabolism-related pathologies, understanding the distinct and overlapping regulation and functions of the two mTOR complexes is vital for the development of more effective therapeutic strategies. This review discusses the key discoveries and recent findings on the regulation and metabolic functions of the mTOR complexes. We highlight findings from cancer models but also discuss other examples of the mTOR-mediated metabolic reprogramming occurring in stem and immune cells, type 2 diabetes/obesity, neurodegenerative disorders, and aging.
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Affiliation(s)
- Angelia Szwed
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Eugene Kim
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
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21
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Parker PJ, Brown SJ, Calleja V, Chakravarty P, Cobbaut M, Linch M, Marshall JJT, Martini S, McDonald NQ, Soliman T, Watson L. Equivocal, explicit and emergent actions of PKC isoforms in cancer. Nat Rev Cancer 2021; 21:51-63. [PMID: 33177705 DOI: 10.1038/s41568-020-00310-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/02/2020] [Indexed: 01/02/2023]
Abstract
The maturing mutational landscape of cancer genomes, the development and application of clinical interventions and evolving insights into tumour-associated functions reveal unexpected features of the protein kinase C (PKC) family of serine/threonine protein kinases. These advances include recent work showing gain or loss-of-function mutations relating to driver or bystander roles, how conformational constraints and plasticity impact this class of proteins and how emergent cancer-associated properties may offer opportunities for intervention. The profound impact of the tumour microenvironment, reflected in the efficacy of immune checkpoint interventions, further prompts to incorporate PKC family actions and interventions in this ecosystem, informed by insights into the control of stromal and immune cell functions. Drugging PKC isoforms has offered much promise, but when and how is not obvious.
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Affiliation(s)
- Peter J Parker
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK.
- School of Cancer and Pharmaceutical Sciences, King's College London, Guy's Campus, London, UK.
| | - Sophie J Brown
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Veronique Calleja
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | | | - Mathias Cobbaut
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Mark Linch
- UCL Cancer Institute, University College London, London, UK
| | | | - Silvia Martini
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Neil Q McDonald
- Signalling and Structural Biology Laboratory, Francis Crick Institute, London, UK
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, UK
| | - Tanya Soliman
- Centre for Cancer Genomics and Computational Biology, Bart's Cancer Institute, London, UK
| | - Lisa Watson
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
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22
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Endicott SJ, Ziemba ZJ, Beckmann LJ, Boynton DN, Miller RA. Inhibition of class I PI3K enhances chaperone-mediated autophagy. J Cell Biol 2020; 219:211459. [PMID: 33048163 PMCID: PMC7557678 DOI: 10.1083/jcb.202001031] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 04/14/2020] [Accepted: 09/09/2020] [Indexed: 01/04/2023] Open
Abstract
Chaperone-mediated autophagy (CMA) is the most selective form of lysosomal proteolysis, where individual peptides, recognized by a consensus motif, are translocated directly across the lysosomal membrane. CMA regulates the abundance of many disease-related proteins, with causative roles in neoplasia, neurodegeneration, hepatosteatosis, and other pathologies relevant to human health and aging. At the lysosomal membrane, CMA is inhibited by Akt-dependent phosphorylation of the CMA regulator GFAP. The INS-PI3K-PDPK1 pathway regulates Akt, but its role in CMA is unclear. Here, we report that inhibition of class I PI3K or PDPK1 activates CMA. In contrast, selective inhibition of class III PI3Ks does not activate CMA. Isolated liver lysosomes from mice treated with either of two orally bioavailable class I PI3K inhibitors, pictilisib or buparlisib, display elevated CMA activity, and decreased phosphorylation of lysosomal GFAP, with no change in macroautophagy. The findings of this study represent an important first step in repurposing class I PI3K inhibitors to modulate CMA in vivo.
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Affiliation(s)
- S. Joseph Endicott
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI
| | - Zachary J. Ziemba
- College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, MI
| | - Logan J. Beckmann
- College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, MI
| | - Dennis N. Boynton
- College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, MI
| | - Richard A. Miller
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI,University of Michigan Geriatrics Center, Ann Arbor, MI,Correspondence to Richard A. Miller:
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23
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Abstract
The Ras oncogene is notoriously difficult to target with specific therapeutics. Consequently, there is interest to better understand the Ras signaling pathways to identify potential targetable effectors. Recently, the mechanistic target of rapamycin complex 2 (mTORC2) was identified as an evolutionarily conserved Ras effector. mTORC2 regulates essential cellular processes, including metabolism, survival, growth, proliferation and migration. Moreover, increasing evidence implicate mTORC2 in oncogenesis. Little is known about the regulation of mTORC2 activity, but proposed mechanisms include a role for phosphatidylinositol (3,4,5)-trisphosphate - which is produced by class I phosphatidylinositol 3-kinases (PI3Ks), well-characterized Ras effectors. Therefore, the relationship between Ras, PI3K and mTORC2, in both normal physiology and cancer is unclear; moreover, seemingly conflicting observations have been reported. Here, we review the evidence on potential links between Ras, PI3K and mTORC2. Interestingly, data suggest that Ras and PI3K are both direct regulators of mTORC2 but that they act on distinct pools of mTORC2: Ras activates mTORC2 at the plasma membrane, whereas PI3K activates mTORC2 at intracellular compartments. Consequently, we propose a model to explain how Ras and PI3K can differentially regulate mTORC2, and highlight the diversity in the mechanisms of mTORC2 regulation, which appear to be determined by the stimulus, cell type, and the molecularly and spatially distinct mTORC2 pools.
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24
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Parker PJ, Lockwood N, Davis K, Kelly JR, Soliman TN, Pardo AL, Marshall JJT, Redmond JM, Vitale M, Silvia Martini. A cancer-associated, genome protective programme engaging PKCε. Adv Biol Regul 2020; 78:100759. [PMID: 33039823 PMCID: PMC7689578 DOI: 10.1016/j.jbior.2020.100759] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 09/27/2020] [Accepted: 10/02/2020] [Indexed: 12/21/2022]
Abstract
Associated with their roles as targets for tumour promoters, there has been a long-standing interest in how members of the protein kinase C (PKC) family act to modulate cell growth and division. This has generated a great deal of observational data, but has for the most part not afforded clear mechanistic insights into the control mechanisms at play. Here, we review the roles of PKCε in protecting transformed cells from non-disjunction. In this particular cell cycle context, there is a growing understanding of the pathways involved, affording biomarker and interventional insights and opportunities.
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Affiliation(s)
- Peter J Parker
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, NW1 1AT, UK; School of Cancer and Pharmaceutical Sciences, Guy's Campus, London, SE1 1UL, UK.
| | - Nicola Lockwood
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, NW1 1AT, UK
| | - Khalil Davis
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, NW1 1AT, UK
| | - Joanna R Kelly
- Cancer Research UK, Manchester Institute, Alderley Park, SK10 4TG, UK
| | - Tanya N Soliman
- Barts Cancer Institute, Charterhouse Square, London, EC1M 6BE, UK
| | - Ainara Lopez Pardo
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, NW1 1AT, UK
| | | | | | - Marco Vitale
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Silvia Martini
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, NW1 1AT, UK
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25
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Huang L, Xu W, Yan D, You X, Shi X, Zhang S, Hong H, Dai L. Genetic Predisposition to Glioma Mediated by a MAPKAP1 Enhancer Variant. Cell Mol Neurobiol 2020; 40:643-652. [PMID: 31773361 DOI: 10.1007/s10571-019-00763-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/18/2019] [Indexed: 12/12/2022]
Abstract
Mitogen-activated protein kinase-associated protein 1 (MAPKAP1) is a unique component of the mechanistic target of rapamycin (MTOR) pathway which plays a pivotal role in carcinogenesis. The role of enhancer variant in carcinogenesis receives increased attentions. However, the significance of enhancer variants of MAPKAP1 in glioma has not yet been investigated. The associations of enhancer variants of MAPKAP1 with glioma susceptibility were evaluated in a cohort of 400 glioma patients and 651 controls. The function of glioma susceptibility locus was examined by a set of biochemical assays. We found that an enhancer variant of MAPKAP1 rs473426 was associated with a significantly increased risk of glioma in a dominant manner (OR 1.53, 95% CI 1.13-2.06; P = 0.006). The association for rs1339499 located in the same enhancer approached the borderline of significance after multiple testing correction (OR 0.74, 95% CI 0.56-0.98; P = 0.037). Furthermore, cumulative associations of rs473426 and rs1339499 with glioma risk were observed (P = 0.011). Functional analyses showed that the risk allele rs473426 C downregulated the regulatory activity of enhancer by reducing the binding affinity of a transcriptional activator NFΙC, which resulted in lower gene expression both in vitro and in vivo. These results demonstrate for the first time that enhancer variant of MAPKAP1 confers susceptibility to glioma by downregulation of MAPKAP1 expression, and provide further evidence highlighting MAPKAP1 as a cancer suppressor in glioma carcinogenesis.
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Affiliation(s)
- Liming Huang
- Department of Medical Oncology (39th Section), The First Affiliated Hospital, Fujian Medical University, Fuzhou, 350005, China.
| | - Wenshen Xu
- Department of Laboratory Medicine, The First Affiliated Hospital, Fujian Medical University, Fuzhou, 350005, China
| | - Danfang Yan
- Department of Radiation Oncology, The First Affiliated Hospital, Zhejiang University, Hangzhou, 310003, China
| | - Xin You
- Department of Medical Oncology (39th Section), The First Affiliated Hospital, Fujian Medical University, Fuzhou, 350005, China
| | - Xi Shi
- Department of Medical Oncology (39th Section), The First Affiliated Hospital, Fujian Medical University, Fuzhou, 350005, China
| | - Shu Zhang
- Department of Medical Oncology (39th Section), The First Affiliated Hospital, Fujian Medical University, Fuzhou, 350005, China
| | - Hualan Hong
- Department of Medical Oncology (39th Section), The First Affiliated Hospital, Fujian Medical University, Fuzhou, 350005, China
| | - Lian Dai
- Department of Medicine, The Third Affiliated People's Hospital, Fujian University of Traditional Chinese Medicine, Fuzhou, 350108, China.
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26
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mTOR complex 2 is an integrator of cancer metabolism and epigenetics. Cancer Lett 2020; 478:1-7. [PMID: 32145344 DOI: 10.1016/j.canlet.2020.03.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Revised: 02/18/2020] [Accepted: 03/02/2020] [Indexed: 02/07/2023]
Abstract
Metabolic reprogramming is a central hallmark of cancer and is driven by abnormalites of oncogenes and tumor suppressors. This enables tumor cells to obtain the macromolecular precursors and energy needed for rapid tumor growth. Accelerated metabolism also translates into cancer cell aggression through epigenetic changes. The aberrant signaling cascades activated by oncogenes coordinate metabolic reprogramming with epigenetic shifts and subsequent global transcriptional changes through the dysregulation of rate-limiting metabolic enzymes as well as by facilitating the production of intermediary metabolites. As the landscape of cancer cell metabolism has been elucidated, it is now time for this knowledge to be translated into benefit for patients. Here we review the recently identified central regulatory role for mechanistic/mammalian target of rapamycin complex 2 (mTORC2), a downstream effector of many cancer-causing mutations, in reprogramming the metabolic and epigenetic landscape. This leads to tumor cell survival and cancer drug resistance.
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27
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Novel compounds for the modulation of mTOR and autophagy to treat neurodegenerative diseases. Cell Signal 2020; 65:109442. [DOI: 10.1016/j.cellsig.2019.109442] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 10/10/2019] [Accepted: 10/11/2019] [Indexed: 12/16/2022]
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28
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Magaway C, Kim E, Jacinto E. Targeting mTOR and Metabolism in Cancer: Lessons and Innovations. Cells 2019; 8:cells8121584. [PMID: 31817676 PMCID: PMC6952948 DOI: 10.3390/cells8121584] [Citation(s) in RCA: 130] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/02/2019] [Accepted: 12/03/2019] [Indexed: 12/14/2022] Open
Abstract
Cancer cells support their growth and proliferation by reprogramming their metabolism in order to gain access to nutrients. Despite the heterogeneity in genetic mutations that lead to tumorigenesis, a common alteration in tumors occurs in pathways that upregulate nutrient acquisition. A central signaling pathway that controls metabolic processes is the mTOR pathway. The elucidation of the regulation and functions of mTOR can be traced to the discovery of the natural compound, rapamycin. Studies using rapamycin have unraveled the role of mTOR in the control of cell growth and metabolism. By sensing the intracellular nutrient status, mTOR orchestrates metabolic reprogramming by controlling nutrient uptake and flux through various metabolic pathways. The central role of mTOR in metabolic rewiring makes it a promising target for cancer therapy. Numerous clinical trials are ongoing to evaluate the efficacy of mTOR inhibition for cancer treatment. Rapamycin analogs have been approved to treat specific types of cancer. Since rapamycin does not fully inhibit mTOR activity, new compounds have been engineered to inhibit the catalytic activity of mTOR to more potently block its functions. Despite highly promising pre-clinical studies, early clinical trial results of these second generation mTOR inhibitors revealed increased toxicity and modest antitumor activity. The plasticity of metabolic processes and seemingly enormous capacity of malignant cells to salvage nutrients through various mechanisms make cancer therapy extremely challenging. Therefore, identifying metabolic vulnerabilities in different types of tumors would present opportunities for rational therapeutic strategies. Understanding how the different sources of nutrients are metabolized not just by the growing tumor but also by other cells from the microenvironment, in particular, immune cells, will also facilitate the design of more sophisticated and effective therapeutic regimen. In this review, we discuss the functions of mTOR in cancer metabolism that have been illuminated from pre-clinical studies. We then review key findings from clinical trials that target mTOR and the lessons we have learned from both pre-clinical and clinical studies that could provide insights on innovative therapeutic strategies, including immunotherapy to target mTOR signaling and the metabolic network in cancer.
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29
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Ruan C, Ouyang X, Liu H, Li S, Jin J, Tang W, Xia Y, Su B. Sin1-mediated mTOR signaling in cell growth, metabolism and immune response. Natl Sci Rev 2019; 6:1149-1162. [PMID: 34691993 PMCID: PMC8291397 DOI: 10.1093/nsr/nwz171] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/22/2019] [Accepted: 10/22/2019] [Indexed: 12/22/2022] Open
Abstract
Abstract
The mammalian target of rapamycin (mTOR) is an evolutionarily conserved Ser/Thr protein kinase with essential cellular function via processing various extracellular and intracellular inputs. Two distinct multi-protein mTOR complexes (mTORC), mTORC1 and mTORC2, have been identified and well characterized in eukaryotic cells from yeast to human. Sin1, which stands for Sty1/Spc1-interacting protein1, also known as mitogen-activated protein kinase (MAPK) associated protein (MAPKAP)1, is an evolutionarily conserved adaptor protein. Mammalian Sin1 interacts with many cellular proteins, but it has been widely studied as an essential component of mTORC2, and it is crucial not only for the assembly of mTORC2 but also for the regulation of its substrate specificity. In this review, we summarize our current knowledge of the structure and functions of Sin1, focusing specifically on its protein interaction network and its roles in the mTOR pathway that could account for various cellular functions of mTOR in growth, metabolism, immunity and cancer.
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Affiliation(s)
- Chun Ruan
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xinxing Ouyang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Hongzhi Liu
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Song Li
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jingsi Jin
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Weiyi Tang
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yu Xia
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bing Su
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
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30
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Ras functional proximity proteomics establishes mTORC2 as new direct ras effector. Oncotarget 2019; 10:5126-5135. [PMID: 31497244 PMCID: PMC6718260 DOI: 10.18632/oncotarget.27025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 05/29/2019] [Indexed: 01/14/2023] Open
Abstract
Although oncogenic mutations in the three major Ras isoforms, KRAS, HRAS and NRAS, are present in nearly a third of human cancers, therapeutic targeting of Ras remains a challenge due to its structure and complex regulation. However, an in-depth examination of the protein interactome of oncogenic Ras may provide new insights into key regulators, effectors and other mediators of its tumorigenic functions. Previous proteomic analyses have been limited by experimental tools that fail to capture the dynamic, transient nature of Ras cellular interactions. Therefore, in a recent study, we integrated proximity-dependent biotin labeling (BioID) proteomics with CRISPR screening of identified proteins to identify Ras proximal proteins required for Ras-dependent cancer cell growth. Oncogenic Ras was proximal to proteins involved in unexpected biological processes, such as vesicular trafficking and solute transport. Critically, we identified a direct, bona fide interaction between active Ras and the mTOR Complex 2 (mTORC2) that stimulated mTORC2 kinase activity. The oncogenic Ras-mTORC2 interaction resulted in a downstream pro-proliferative transcriptional program and promoted Ras-dependent tumor growth in vivo. Here we provide additional insight into the Ras isoform-specific protein interactomes, highlighting new opportunities for unique tumor-type therapies. Finally, we discuss the active Ras-mTORC2 interaction in detail, providing a more complete understanding of the direct relationship between Ras and mTORC2. Collectively, our findings support a model wherein Ras integrates an expanded array of pro-oncogenic signals to drive tumorigenic processes, including action on mTORC2 as a direct effector of Ras-driven proliferative signals.
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31
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Gleason CE, Oses-Prieto JA, Li KH, Saha B, Situ G, Burlingame AL, Pearce D. Phosphorylation at distinct subcellular locations underlies specificity in mTORC2-mediated activation of SGK1 and Akt. J Cell Sci 2019; 132:jcs.224931. [PMID: 30837283 DOI: 10.1242/jcs.224931] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 02/21/2019] [Indexed: 02/04/2023] Open
Abstract
mTORC2 lies at the intersection of signaling pathways that control metabolism and ion transport through phosphorylation of the AGC-family kinases, the Akt and SGK1 proteins. How mTORC2 targets these functionally distinct downstream effectors in a context-specific manner is not known. Here, we show that the salt- and blood pressure-regulatory hormone, angiotensin II (AngII) stimulates selective mTORC2-dependent phosphorylation of SGK1 (S422) but not Akt (S473 and equivalent sites). Conventional PKC (cPKC), a critical mediator of the angiotensin type I receptor (AT1R, also known as AGTR1) signaling, regulates the subcellular localization of SIN1 (also known as MAPKAP1) and SGK1. Inhibition of cPKC catalytic activity disturbs SIN1 and SGK1 subcellular localization, re-localizing them from the nucleus and a perinuclear compartment to the plasma membrane in advance of hormonal stimulation. Surprisingly, pre-targeting of SIN1 and SGK1 to the plasma membrane prevents SGK1 S422 but not Akt S473 phosphorylation. Additionally, we identify three sites on SIN1 (S128, S315 and S356) that are phosphorylated in response to cPKC activation. Collectively, these data demonstrate that SGK1 activation occurs at a distinct subcellular compartment from that of Akt and suggests a mechanism for the selective activation of these functionally distinct mTORC2 targets through subcellular partitioning of mTORC2 activity.
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Affiliation(s)
- Catherine E Gleason
- Department of Medicine, Division of Nephrology, UCSF, San Francisco, CA 94143, USA
| | - Juan A Oses-Prieto
- Departments of Chemistry and Pharmaceutical Chemistry, UCSF, San Francisco, CA 94143, USA
| | - Kathy H Li
- Departments of Chemistry and Pharmaceutical Chemistry, UCSF, San Francisco, CA 94143, USA
| | - Bidisha Saha
- Department of Medicine, Division of Nephrology, UCSF, San Francisco, CA 94143, USA
| | - Gavin Situ
- Department of Medicine, Division of Nephrology, UCSF, San Francisco, CA 94143, USA
| | - Alma L Burlingame
- Departments of Chemistry and Pharmaceutical Chemistry, UCSF, San Francisco, CA 94143, USA
| | - David Pearce
- Department of Medicine, Division of Nephrology, UCSF, San Francisco, CA 94143, USA
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32
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Kovalski JR, Bhaduri A, Zehnder AM, Neela PH, Che Y, Wozniak GG, Khavari PA. The Functional Proximal Proteome of Oncogenic Ras Includes mTORC2. Mol Cell 2019; 73:830-844.e12. [PMID: 30639242 DOI: 10.1016/j.molcel.2018.12.001] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 10/29/2018] [Accepted: 11/29/2018] [Indexed: 12/31/2022]
Abstract
Proximity-dependent biotin labeling (BioID) may identify new targets for cancers driven by difficult-to-drug oncogenes such as Ras. Therefore, BioID was used with wild-type (WT) and oncogenic mutant (MT) H-, K-, and N-Ras, identifying known interactors, including Raf and PI3K, as well as a common set of 130 novel proteins proximal to all Ras isoforms. A CRISPR screen of these proteins for Ras dependence identified mTOR, which was also found proximal to MT Ras in human tumors. Oncogenic Ras directly bound two mTOR complex 2 (mTORC2) components, mTOR and MAPKAP1, to promote mTORC2 kinase activity at the plasma membrane. mTORC2 enabled the Ras pro-proliferative cell cycle transcriptional program, and perturbing the Ras-mTORC2 interaction impaired Ras-dependent neoplasia in vivo. Combining proximity-dependent proteomics with CRISPR screening identified a new set of functional Ras-associated proteins, defined mTORC2 as a new direct Ras effector, and offers a strategy for finding new proteins that cooperate with dominant oncogenes.
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Affiliation(s)
- Joanna R Kovalski
- Program in Epithelial Biology, Stanford University, Stanford, CA 94305, USA; Program in Cancer Biology, Stanford University, Stanford, CA 94305, USA
| | - Aparna Bhaduri
- The Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA 94131, USA
| | - Ashley M Zehnder
- Program in Epithelial Biology, Stanford University, Stanford, CA 94305, USA
| | - Poornima H Neela
- Program in Epithelial Biology, Stanford University, Stanford, CA 94305, USA
| | - Yonglu Che
- Program in Epithelial Biology, Stanford University, Stanford, CA 94305, USA; Program in Cancer Biology, Stanford University, Stanford, CA 94305, USA
| | - Glenn G Wozniak
- Program in Epithelial Biology, Stanford University, Stanford, CA 94305, USA
| | - Paul A Khavari
- Program in Epithelial Biology, Stanford University, Stanford, CA 94305, USA; Program in Cancer Biology, Stanford University, Stanford, CA 94305, USA; VA Palo Alto Healthcare System, Palo Alto, CA 94304, USA.
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33
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Abstract
Protein kinase C (PKC) isozymes belong to a family of Ser/Thr kinases whose activity is governed by reversible release of an autoinhibitory pseudosubstrate. For conventional and novel isozymes, this is effected by binding the lipid second messenger, diacylglycerol, but for atypical PKC isozymes, this is effected by binding protein scaffolds. PKC shot into the limelight following the discovery in the 1980s that the diacylglycerol-sensitive isozymes are "receptors" for the potent tumor-promoting phorbol esters. This set in place a concept that PKC isozymes are oncoproteins. Yet three decades of cancer clinical trials targeting PKC with inhibitors failed and, in some cases, worsened patient outcome. Emerging evidence from cancer-associated mutations and protein expression levels provide a reason: PKC isozymes generally function as tumor suppressors and their activity should be restored, not inhibited, in cancer therapies. And whereas not enough activity is associated with cancer, variants with enhanced activity are associated with degenerative diseases such as Alzheimer's disease. This review describes the tightly controlled mechanisms that ensure PKC activity is perfectly balanced and what happens when these controls are deregulated. PKC isozymes serve as a paradigm for the wisdom of Confucius: "to go beyond is as wrong as to fall short."
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Affiliation(s)
- Alexandra C Newton
- a Department of Pharmacology , University of California at San Diego , La Jolla , CA , USA
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34
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Walker NM, Mazzoni SM, Vittal R, Fingar DC, Lama VN. c-Jun N-terminal kinase (JNK)-mediated induction of mSin1 expression and mTORC2 activation in mesenchymal cells during fibrosis. J Biol Chem 2018; 293:17229-17239. [PMID: 30217824 DOI: 10.1074/jbc.ra118.003926] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 09/06/2018] [Indexed: 02/03/2023] Open
Abstract
Mammalian target of rapamycin complex 2 (mTORC2) has been shown to regulate mTORC1/4E-BP1/eIF4E signaling and collagen I expression in mesenchymal cells (MCs) during fibrotic activation. Here we investigated the regulation of the mTORC2 binding partner mammalian stress-activated protein kinase-interacting protein 1 (mSin1) in MCs derived from human lung allografts and identified a novel role for mSin1 during fibrosis. mSin1 was identified as a common downstream target of key fibrotic pathways, and its expression was increased in MCs in response to pro-fibrotic mediators: lysophosphatidic acid (LPA), transforming growth factor β, and interleukin 13. Fibrotic MCs had higher mSin1 protein levels than nonfibrotic MCs, and siRNA-mediated silencing of mSIN1 inhibited collagen I expression and mTORC1/2 activity in these cells. Autocrine LPA signaling contributed to constitutive up-regulation of mSin1 in fibrotic MCs, and mSin1 was decreased because of LPA receptor 1 siRNA treatment. We identified c-Jun N-terminal kinase (JNK) as a key intermediary in mSin1 up-regulation by the pro-fibrotic mediators, as pharmacological and siRNA-mediated inhibition of JNK prevented the LPA-induced mSin1 increase. Proteasomal inhibition rescued mSin1 levels after JNK inhibition in LPA-treated MCs, and the decrease in mSin1 ubiquitination in response to LPA was counteracted by JNK inhibitors. Constitutive JNK1 overexpression induced mSin1 expression and could drive mTORC2 and mTORC1 activation and collagen I expression in nonfibrotic MCs, effects that were reversed by siRNA-mediated mSIN1 silencing. These results indicate that LPA stabilizes mSin1 protein expression via JNK signaling by blocking its proteasomal degradation and identify the LPA/JNK/mSin1/mTORC/collagen I pathway as critical for fibrotic activation of MCs.
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Affiliation(s)
- Natalie M Walker
- From the Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and
| | - Serina M Mazzoni
- From the Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and
| | - Ragini Vittal
- From the Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and
| | - Diane C Fingar
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-0360
| | - Vibha N Lama
- From the Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and
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35
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Who does TORC2 talk to? Biochem J 2018; 475:1721-1738. [PMID: 29794170 DOI: 10.1042/bcj20180130] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 04/19/2018] [Accepted: 04/23/2018] [Indexed: 12/21/2022]
Abstract
The target of rapamycin (TOR) is a protein kinase that, by forming complexes with partner proteins, governs diverse cellular signalling networks to regulate a wide range of processes. TOR thus plays central roles in maintaining normal cellular functions and, when dysregulated, in diverse diseases. TOR forms two distinct types of multiprotein complexes (TOR complexes 1 and 2, TORC1 and TORC2). TORC1 and TORC2 differ in their composition, their control and their substrates, so that they play quite distinct roles in cellular physiology. Much effort has been focused on deciphering the detailed regulatory links within the TOR pathways and the structure and control of TOR complexes. In this review, we summarize recent advances in understanding mammalian (m) TORC2, its structure, its regulation, and its substrates, which link TORC2 signalling to the control of cell functions. It is now clear that TORC2 regulates several aspects of cell metabolism, including lipogenesis and glucose transport. It also regulates gene transcription, the cytoskeleton, and the activity of a subset of other protein kinases.
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36
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Abstract
The mechanistic target of rapamycin (mTOR) is an evolutionarily conserved serine/threonine kinase that senses and integrates environmental information into cellular regulation and homeostasis. Accumulating evidence has suggested a master role of mTOR signalling in many fundamental aspects of cell biology and organismal development. mTOR deregulation is implicated in a broad range of pathological conditions, including diabetes, cancer, neurodegenerative diseases, myopathies, inflammatory, infectious, and autoimmune conditions. Here, we review recent advances in our knowledge of mTOR signalling in mammalian physiology. We also discuss the impact of mTOR alteration in human diseases and how targeting mTOR function can treat human diseases.
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Affiliation(s)
- Yassine El Hiani
- a Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS B3H 4R2, Canada
| | - Emmanuel Eroume-A Egom
- b Jewish General Hospital and Lady Davis Institute for Medical Research, Montreal, QC H3T 1E2, Canada
| | - Xian-Ping Dong
- a Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS B3H 4R2, Canada
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37
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Chen X, Liu M, Tian Y, Li J, Qi Y, Zhao D, Wu Z, Huang M, Wong CCL, Wang HW, Wang J, Yang H, Xu Y. Cryo-EM structure of human mTOR complex 2. Cell Res 2018; 28:518-528. [PMID: 29567957 DOI: 10.1038/s41422-018-0029-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 02/02/2018] [Accepted: 02/24/2018] [Indexed: 02/07/2023] Open
Abstract
Mechanistic target of rapamycin (mTOR) complex 2 (mTORC2) plays an essential role in regulating cell proliferation through phosphorylating AGC protein kinase family members, including AKT, PKC and SGK1. The functional core complex consists of mTOR, mLST8, and two mTORC2-specific components, Rictor and mSin1. Here we investigated the intermolecular interactions within mTORC2 complex and determined its cryo-electron microscopy structure at 4.9 Å resolution. The structure reveals a hollow rhombohedral fold with a 2-fold symmetry. The dimerized mTOR serves as a scaffold for the complex assembly. The N-terminal half of Rictor is composed of helical repeat clusters and binds to mTOR through multiple contacts. mSin1 is located close to the FRB domain and catalytic cavity of mTOR. Rictor and mSin1 together generate steric hindrance to inhibit binding of FKBP12-rapamycin to mTOR, revealing the mechanism for rapamycin insensitivity of mTORC2. The mTOR dimer in mTORC2 shows more compact conformation than that of mTORC1 (rapamycin sensitive), which might result from the interaction between mTOR and Rictor-mSin1. Structural comparison shows that binding of Rictor and Raptor (mTORC1-specific component) to mTOR is mutually exclusive. Our study provides a basis for understanding the assembly of mTORC2 and a framework to further characterize the regulatory mechanism of mTORC2 pathway.
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Affiliation(s)
- Xizi Chen
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,Key Laboratory of Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Mengjie Liu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,Key Laboratory of Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Yuan Tian
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,Key Laboratory of Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Jiabei Li
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,Key Laboratory of Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Yilun Qi
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,Key Laboratory of Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Dan Zhao
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,Key Laboratory of Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Zihan Wu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,Key Laboratory of Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.,State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Min Huang
- National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 201210, China
| | - Catherine C L Wong
- National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 201210, China.,Center for Precision Medicine Multi-Omics Research (CPMMOR), Peking University Health Science Center, Beijing, 100871, China.,State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Science, Peking University, Beijing, 100871, China
| | - Hong-Wei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jiawei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Huirong Yang
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China. .,Key Laboratory of Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China. .,State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China.
| | - Yanhui Xu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China. .,Key Laboratory of Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China. .,State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China. .,CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, 200031, China.
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38
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Murray ER, Cameron AJM. Towards specific inhibition of mTORC2. Aging (Albany NY) 2017; 9:2461-2462. [PMID: 29232655 PMCID: PMC5764381 DOI: 10.18632/aging.101346] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 12/11/2017] [Indexed: 11/25/2022]
Affiliation(s)
- Elizabeth R Murray
- Kinase Biology Laboratory, Centre for Tumour Biology, Barts Cancer Institute, Queen Mary, University of London, John Vane Science Centre, Charterhouse Square, London, EC1M 6BQ, UK
| | - Angus J M Cameron
- Kinase Biology Laboratory, Centre for Tumour Biology, Barts Cancer Institute, Queen Mary, University of London, John Vane Science Centre, Charterhouse Square, London, EC1M 6BQ, UK
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39
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Evolutionary Conservation of the Components in the TOR Signaling Pathways. Biomolecules 2017; 7:biom7040077. [PMID: 29104218 PMCID: PMC5745459 DOI: 10.3390/biom7040077] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/26/2017] [Accepted: 10/27/2017] [Indexed: 01/08/2023] Open
Abstract
Target of rapamycin (TOR) is an evolutionarily conserved protein kinase that controls multiple cellular processes upon various intracellular and extracellular stimuli. Since its first discovery, extensive studies have been conducted both in yeast and animal species including humans. Those studies have revealed that TOR forms two structurally and physiologically distinct protein complexes; TOR complex 1 (TORC1) is ubiquitous among eukaryotes including animals, yeast, protozoa, and plants, while TOR complex 2 (TORC2) is conserved in diverse eukaryotic species other than plants. The studies have also identified two crucial regulators of mammalian TORC1 (mTORC1), Ras homolog enriched in brain (RHEB) and RAG GTPases. Of these, RAG regulates TORC1 in yeast as well and is conserved among eukaryotes with the green algae and land plants as apparent exceptions. RHEB is present in various eukaryotes but sporadically missing in multiple taxa. RHEB, in the budding yeast Saccharomyces cerevisiae, appears to be extremely divergent with concomitant loss of its function as a TORC1 regulator. In this review, we summarize the evolutionarily conserved functions of the key regulatory subunits of TORC1 and TORC2, namely RAPTOR, RICTOR, and SIN1. We also delve into the evolutionary conservation of RHEB and RAG and discuss the conserved roles of these GTPases in regulating TORC1.
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40
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Cameron AJ, Veeriah S, Marshall JJ, Murray ER, Larijani B, Parker PJ. Uncoupling TORC2 from AGC kinases inhibits tumour growth. Oncotarget 2017; 8:84685-84696. [PMID: 29156676 PMCID: PMC5689566 DOI: 10.18632/oncotarget.20086] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 06/26/2017] [Indexed: 12/28/2022] Open
Abstract
Mammalian target of rapamycin (mTOR) is a central regulator of growth and metabolism. mTOR resides in two distinct multi-protein complexes - mTORC1 and mTORC2 - with distinct upstream regulators and downstream targets. While it is possible to specifically inhibit mTORC1 with rapamycin, or inhibit both mTOR complexes together with ATP pocket directed mTOR kinase inhibitors, it is not possible to assess the specific roles for mTORC2 pharmacologically. To overcome this, we have developed a novel, inducible, dominant negative system for disrupting substrate recruitment to mTORC2. Previously we identified the mTORC2 specific subunit Sin1 as a direct binding partner for AGC kinases Akt and PKC. Sin1 mutants, which retain the ability to bind Rictor and mTOR, but fail to recruit their AGC client kinases, inhibit AKT and PKC priming and block cell growth. In this study, we demonstrate that uncoupling mTORC2 from AGC kinases in DLD1 colon cancer cells inhibits Akt activation and blocks tumour growth in vivo. Further we demonstrate, using time resolved two-site amplified FRET (A-FRET) analysis of xenograft tumours, that inhibition of tumour growth correlates with the degree of mTORC2 uncoupling from its downstream targets, as demonstrated for Akt. These data add weight to the body of evidence that mTORC2 represents a pharmacological target in cancer independently of mTORC1.
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Affiliation(s)
- Angus J.M. Cameron
- Kinase Biology Laboratory, Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London, UK
| | - Selvaraju Veeriah
- Translational Cancer Therapeutics Laboratory, Paul O’Gorman Building, University College London Cancer Institute, London, United Kingdom
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | | | - Elizabeth R. Murray
- Kinase Biology Laboratory, Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London, UK
| | - Banafshé Larijani
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Research Centre for Experimental Marine Biology and Biotechnology (PiE) & Biofísika Instituto (UPV/EHU, CSIC), University of the Basque Country, Areatza Hiribidea, Plentzia, Spain
| | - Peter J. Parker
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
- Division of Cancer Studies, King’s College London, New Hunts House, Guy’s Campus, London, UK
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41
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Alcantara D, Elmslie F, Tetreault M, Bareke E, Hartley T, Majewski J, Boycott K, Innes AM, Dyment DA, O'Driscoll M. SHORT syndrome due to a novel de novo mutation in PRKCE (Protein Kinase Cɛ) impairing TORC2-dependent AKT activation. Hum Mol Genet 2017; 26:3713-3721. [PMID: 28934384 DOI: 10.1093/hmg/ddx256] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 06/29/2017] [Indexed: 02/11/2024] Open
Abstract
SHORT syndrome is a rare, recognizable syndrome resulting from heterozygous mutations in PIK3R1 encoding a regulatory subunit of phosphoinositide-3-kinase (PI3K). The condition is characterized by short stature, intrauterine growth restriction, lipoatrophy and a facial gestalt involving a triangular face, deep set eyes, low hanging columella and small chin. PIK3R1 mutations in SHORT syndrome result in reduced signaling through the PI3K-AKT-mTOR pathway. We performed whole exome sequencing for an individual with clinical features of SHORT syndrome but negative for PIK3R1 mutation and her parents. A rare de novo variant in PRKCE was identified. The gene encodes PKCε and, as such, the AKT-mTOR pathway function was assessed using phospho-specific antibodies with patient lymphoblasts and following ectopic expression of the mutant in HEK293 cells. Kinase analysis showed that the variant resulted in a partial loss-of-function. Whilst interaction with PDK1 and the mTORC2 complex component SIN1 was preserved in the mutant PKCε, it bound to SIN1 with a higher affinity than wild-type PKCε and the dynamics of mTORC2-dependent priming of mutant PKCε was altered. Further, mutant PKCε caused impaired mTORC2-dependent pAKT-S473 following rapamycin treatment. Reduced pFOXO1-S256 and pS6-S240/244 levels were also observed in the patient LCLs. To date, mutations in PIK3R1 causing impaired PI3K-dependent AKT activation are the only known cause of SHORT syndrome. We identify a SHORT syndrome child with a novel partial loss-of-function defect in PKCε. This variant causes impaired AKT activation via compromised mTORC2 complex function.
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Affiliation(s)
- Diana Alcantara
- Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, UK
| | - Frances Elmslie
- South West Thames Regional Genetics Service, St. George's, University of London, London SW17 0RE, UK
| | - Martine Tetreault
- McGill University and Genome Quebec Innovation Centre, Montreal, QC H3A 1A4, Canada
| | - Eric Bareke
- McGill University and Genome Quebec Innovation Centre, Montreal, QC H3A 1A4, Canada
| | - Taila Hartley
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON K1H 8L1, Canada
| | - Jacek Majewski
- McGill University and Genome Quebec Innovation Centre, Montreal, QC H3A 1A4, Canada
| | - Kym Boycott
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON K1H 8L1, Canada
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON K1H 8L1, Canada
| | - A Micheil Innes
- Department of Medical Genetics, Alberta Children's Hospital Research Institute for Child and Maternal Health, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - David A Dyment
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON K1H 8L1, Canada
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON K1H 8L1, Canada
| | - Mark O'Driscoll
- Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, UK
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42
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Ali MU, Ur Rahman MS, Jia Z, Jiang C. Eukaryotic translation initiation factors and cancer. Tumour Biol 2017; 39:1010428317709805. [PMID: 28653885 DOI: 10.1177/1010428317709805] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Recent technological advancements have shown tremendous mechanistic accomplishments in our understanding of the mechanism of messenger RNA translation in eukaryotic cells. Eukaryotic messenger RNA translation is very complex process that includes four phases (initiation, elongation, termination, and ribosome recycling) and diverse mechanisms involving protein and non-protein molecules. Translation regulation is principally achieved during initiation step of translation, which is organized by multiple eukaryotic translation initiation factors. Eukaryotic translation initiation factor proteins help in stabilizing the formation of the functional ribosome around the start codon and provide regulatory mechanisms in translation initiation. Dysregulated messenger RNA translation is a common feature of tumorigenesis. Various oncogenic and tumor suppressive genes affect/are affected by the translation machinery, making the components of the translation apparatus promising therapeutic targets for the novel anticancer drug. This review provides details on the role of eukaryotic translation initiation factors in messenger RNA translation initiation, their contribution to onset and progression of tumor, and how dysregulated eukaryotic translation initiation factors can be used as a target to treat carcinogenesis.
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Affiliation(s)
- Muhammad Umar Ali
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Muhammad Saif Ur Rahman
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhenyu Jia
- 2 Institute of Occupational Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, China
| | - Cao Jiang
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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43
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Yao CA, Ortiz-Vega S, Sun YY, Chien CT, Chuang JH, Lin Y. Association of mSin1 with mTORC2 Ras and Akt reveals a crucial domain on mSin1 involved in Akt phosphorylation. Oncotarget 2017; 8:63392-63404. [PMID: 28968999 PMCID: PMC5609931 DOI: 10.18632/oncotarget.18818] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 06/02/2017] [Indexed: 12/15/2022] Open
Abstract
mSin1 is a unique component within the mammalian target of rapamycin (mTOR) complex 2 (mTORC2), which is responsible for cellular morphology and glucose metabolism. The association between mSin1 and other mTORC2 components, as well as their functions, has been explored previously; nevertheless, the mapping of the various binding domains of the components is lacking. Based on an evolutionary analysis of the gene, we constructed various fragments and truncated-forms of mSin1. We characterized the individual binding sites of mSin1 with its various partners, including mTOR, Rictor, Ras, and Akt. mTOR and Rictor bind to the amino acid (aa) 100-240 region of mSin1, which is different to the Ras binding site, the aa 260-460 region. A reciprocal examination found that mSin1 associated with the aa 2148-2300 region of mTOR, which is within the kinase domain, and with the carboxyl terminus of Rictor. Interestingly, Akt was found to associate with mSin1 in a region that slightly overlapped with the mTOR/Rictor complex binding site, namely aa 220-260. When only the Akt binding site was deleted from mSin1, phosphorylation of Akt S473 was greatly reduced. Furthermore, the association between Akt and mTOR can be regulated by serum, insulin and LY294002, but not by rapamycin or MAPK kinase inhibitors. Taken together, mSin1 would seem to act as a hub that allows mTORC2 to phosphorylate Akt S473. Our findings should facilitate future proteomic and crystallographic studies, help the development of dominant inhibitors and promote the identification of new drug targets.
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Affiliation(s)
- Chien-An Yao
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan.,Department of Family Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Sara Ortiz-Vega
- Diabetes Unit and Medical Services and The Department of Molecular Biology, Massachusetts General Hospital and The Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Yun-Ya Sun
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Chiang-Ting Chien
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Jen-Hua Chuang
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Yenshou Lin
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
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44
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Stuttfeld E, Imseng S, Maier T. A central role for a region in the middle. eLife 2017; 6. [PMID: 28266914 PMCID: PMC5340523 DOI: 10.7554/elife.25700] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 03/03/2017] [Indexed: 11/26/2022] Open
Abstract
A domain called the 'Conserved region in the middle' is responsible for target recognition in the TORC2 complex in fission yeast and the mTORC2 complex in mammals.
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Affiliation(s)
| | | | - Timm Maier
- Biozentrum, University of Basel, Basel, Switzerland
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45
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Tatebe H, Murayama S, Yonekura T, Hatano T, Richter D, Furuya T, Kataoka S, Furuita K, Kojima C, Shiozaki K. Substrate specificity of TOR complex 2 is determined by a ubiquitin-fold domain of the Sin1 subunit. eLife 2017; 6. [PMID: 28264193 PMCID: PMC5340527 DOI: 10.7554/elife.19594] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 01/27/2017] [Indexed: 01/20/2023] Open
Abstract
The target of rapamycin (TOR) protein kinase forms multi-subunit TOR complex 1 (TORC1) and TOR complex 2 (TORC2), which exhibit distinct substrate specificities. Sin1 is one of the TORC2-specific subunit essential for phosphorylation and activation of certain AGC-family kinases. Here, we show that Sin1 is dispensable for the catalytic activity of TORC2, but its conserved region in the middle (Sin1CRIM) forms a discrete domain that specifically binds the TORC2 substrate kinases. Sin1CRIM fused to a different TORC2 subunit can recruit the TORC2 substrate Gad8 for phosphorylation even in the sin1 null mutant of fission yeast. The solution structure of Sin1CRIM shows a ubiquitin-like fold with a characteristic acidic loop, which is essential for interaction with the TORC2 substrates. The specific substrate-recognition function is conserved in human Sin1CRIM, which may represent a potential target for novel anticancer drugs that prevent activation of the mTORC2 substrates such as AKT.
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Affiliation(s)
- Hisashi Tatebe
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - Shinichi Murayama
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - Toshiya Yonekura
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - Tomoyuki Hatano
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - David Richter
- Department of Microbiology and Molecular Genetics, University of California, California, United States
| | - Tomomi Furuya
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - Saori Kataoka
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Kyoko Furuita
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Chojiro Kojima
- Institute for Protein Research, Osaka University, Osaka, Japan.,Graduate School of Engineering, Yokohama National University, Yokohama, Japan
| | - Kazuhiro Shiozaki
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan.,Department of Microbiology and Molecular Genetics, University of California, California, United States
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Ebner M, Sinkovics B, Szczygieł M, Ribeiro DW, Yudushkin I. Localization of mTORC2 activity inside cells. J Cell Biol 2017; 216:343-353. [PMID: 28143890 PMCID: PMC5294791 DOI: 10.1083/jcb.201610060] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 12/19/2016] [Accepted: 01/04/2017] [Indexed: 12/20/2022] Open
Abstract
mTORC2 integrates extracellular cues with pathways controlling growth and proliferation, but the spatial control of mTORC2 activity is unclear. Using a new reporter, Ebner et al. show that endogenous mTORC2 activity localizes to plasma membrane, mitochondrial, and endosomal pools, which display distinct sensitivity to growth factors. Activation of protein kinase Akt via its direct phosphorylation by mammalian target of rapamycin (mTOR) complex 2 (mTORC2) couples extracellular growth and survival cues with pathways controlling cell growth and proliferation, yet how growth factors target the activity of mTORC2 toward Akt is unknown. In this study, we examine the localization of the obligate mTORC2 component, mSin1, inside cells and report the development of a reporter to examine intracellular localization and regulation by growth factors of the endogenous mTORC2 activity. Using a combination of imaging and biochemical approaches, we demonstrate that inside cells, mTORC2 activity localizes to the plasma membrane, mitochondria, and a subpopulation of endosomal vesicles. We show that unlike the endosomal pool, the activity and localization of mTORC2 via the Sin1 pleckstrin homology domain at the plasma membrane is PI3K and growth factor independent. Furthermore, we show that membrane recruitment is sufficient for Akt phosphorylation in response to growth factors. Our results indicate the existence of spatially separated mTORC2 populations with distinct sensitivity to PI3K inside cells and suggest that intracellular localization could contribute to regulation of mTORC2 activity toward Akt.
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Affiliation(s)
- Michael Ebner
- Max F. Perutz Laboratories, Department of Structural and Computational Biology, Vienna BioCenter, 1030 Vienna, Austria.,Department of Medical Biochemistry, Medical University of Vienna, 1030 Vienna, Austria
| | - Benjamin Sinkovics
- Department of Medical Biochemistry, Medical University of Vienna, 1030 Vienna, Austria.,Center for Molecular Biology, Student Services, University of Vienna, 1030 Vienna, Austria
| | - Magdalena Szczygieł
- Vienna BioCenter Summer School Program, Division of Systems Biology of Signal Transduction, 69120 Heidelberg, Germany
| | | | - Ivan Yudushkin
- Max F. Perutz Laboratories, Department of Structural and Computational Biology, Vienna BioCenter, 1030 Vienna, Austria .,Department of Medical Biochemistry, Medical University of Vienna, 1030 Vienna, Austria
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47
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Abstract
The mTOR complex 2, mTORC2, is a critical downstream effector of PI3K that stimulates AGC kinase members, including AKT, PKC, and SGK. Liu and colleagues reported that the pleckstrin homology domain of SIN1, an essential component of mTORC2, directly binds the PI3K product PtdIns(3,4,5)P3 to promote mTORC2 kinase activation and membrane localization, thereby revealing a mechanistic link between PI3K and mTORC2. Cancer Discov; 5(11); 1127-9. ©2015 AACR.See related article by Liu and colleagues, p. 1194.
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Affiliation(s)
- Hai-Xin Yuan
- Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Kun-Liang Guan
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, California.
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48
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Zheng B, Mao JH, Li XQ, Qian L, Zhu H, Gu DH, Pan XD. Over-expression of DNA-PKcs in renal cell carcinoma regulates mTORC2 activation, HIF-2α expression and cell proliferation. Sci Rep 2016; 6:29415. [PMID: 27412013 PMCID: PMC4944168 DOI: 10.1038/srep29415] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 06/13/2016] [Indexed: 12/23/2022] Open
Abstract
Here, we demonstrated that DNA-PKcs is over-expressed in multiple human renal cell carcinoma (RCC) tissues and in primary/established human RCCs. Pharmacological or genetic inhibition of DNA-PKcs suppressed proliferation of RCC cells. DNA-PKcs was in the complex of mTOR and SIN1, mediating mTORC2 activation and HIF-2α expression in RCC cells. Inhibiting or silencing DNA-PKcs suppressed AKT Ser-473 phosphorylation and HIF-2α expression. In vivo, DNA-PKcs knockdown or oral administration of the DNA-PKcs inhibitor NU-7441 inhibited AKT Ser-473 phosphorylation, HIF-2α expression and 786-0 RCC xenograft growth in nude mice. We showed that miRNA-101 level was decreased in RCC tissues/cells, which could be responsible for DNA-PKcs overexpression and DNA-PKcs mediated oncogenic actions in RCC cells. We show that DNA-PKcs over-expression regulates mTORC2-AKT activation, HIF-2α expression and RCC cell proliferation.
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Affiliation(s)
- Bing Zheng
- Department of Urology, The Second Affiliated Hospital of Nantong University, Nantong 226000, China
| | - Jia-Hui Mao
- Department of pathophysiology, Nantong University School of Medicine, Nantong, China
| | - Xiao-Qing Li
- Department of pathophysiology, Nantong University School of Medicine, Nantong, China
| | - Lin Qian
- Department of Urology, The Second Affiliated Hospital of Nantong University, Nantong 226000, China
| | - Hua Zhu
- Department of Urology, The Second Affiliated Hospital of Nantong University, Nantong 226000, China
| | - Dong-Hua Gu
- Department of Urology, The Second Affiliated Hospital of Nantong University, Nantong 226000, China
| | - Xiao-Dong Pan
- Department of Urology, The Second Affiliated Hospital of Nantong University, Nantong 226000, China
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49
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Gaubitz C, Prouteau M, Kusmider B, Loewith R. TORC2 Structure and Function. Trends Biochem Sci 2016; 41:532-545. [PMID: 27161823 DOI: 10.1016/j.tibs.2016.04.001] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/30/2016] [Accepted: 04/05/2016] [Indexed: 12/21/2022]
Abstract
The target of rapamycin (TOR) kinase functions in two multiprotein complexes, TORC1 and TORC2. Although both complexes are evolutionarily conserved, only TORC1 is acutely inhibited by rapamycin. Consequently, only TORC1 signaling is relatively well understood; and, at present, only mammalian TORC1 is a validated drug target, pursued in immunosuppression and oncology. However, the knowledge void surrounding TORC2 is dissipating. Acute inhibition of TORC2 with small molecules is now possible and structural studies of both TORC1 and TORC2 have recently been reported. Here we review these recent advances as well as observations made from tissue-specific mTORC2 knockout mice. Together these studies help define TORC2 structure-function relationships and suggest that mammalian TORC2 may one day also become a bona fide clinical target.
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Affiliation(s)
- Christl Gaubitz
- Department of Molecular Biology, and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Manoel Prouteau
- Department of Molecular Biology, and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Beata Kusmider
- Department of Molecular Biology, and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Robbie Loewith
- Department of Molecular Biology, and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 quai Ernest Ansermet, CH1211 Geneva, Switzerland; National Centre of Competence in Research "Chemical Biology", University of Geneva, Geneva CH-1211, Switzerland.
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50
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Cozzoli DK, Courson J, Rostock C, Campbell RR, Wroten MG, McGregor H, Caruana AL, Miller BW, Hu JH, Zhang PW, Xiao B, Worley PF, Crabbe JC, Finn DA, Szumlinski KK. Protein Kinase C Epsilon Activity in the Nucleus Accumbens and Central Nucleus of the Amygdala Mediates Binge Alcohol Consumption. Biol Psychiatry 2016; 79:443-51. [PMID: 25861702 PMCID: PMC4561036 DOI: 10.1016/j.biopsych.2015.01.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 01/09/2015] [Accepted: 01/20/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND Protein kinase C epsilon (PKCε) is emerging as a potential target for the development of pharmacotherapies to treat alcohol use disorders, yet little is known regarding how a history of a highly prevalent form of drinking, binge alcohol intake, influences enzyme priming or the functional relevance of kinase activity for excessive alcohol intake. METHODS Immunoblotting was employed on tissue from subregions of the nucleus accumbens (NAc) and the amygdala to examine both idiopathic and binge drinking-induced changes in constitutive PKCε priming. The functional relevance of PKCε translocation for binge drinking and determination of potential upstream signaling pathways involved were investigated using neuropharmacologic approaches within the context of two distinct binge drinking procedures, drinking in the dark and scheduled high alcohol consumption. RESULTS Binge alcohol drinking elevated p(Ser729)-PKCε levels in both the NAc and the central nucleus of the amygdala (CeA). Moreover, immunoblotting studies of selectively bred and transgenic mouse lines revealed a positive correlation between the propensity to binge drink alcohol and constitutive p(Ser729)-PKCε levels in the NAc and CeA. Finally, neuropharmacologic inhibition of PKCε translocation within both regions reduced binge alcohol consumption in a manner requiring intact group 1 metabotropic glutamate receptors, Homer2, phospholipase C, and/or phosphotidylinositide-3 kinase function. CONCLUSIONS Taken together, these data indicate that PKCε signaling in both the NAc and CeA is a major contributor to binge alcohol drinking and to the genetic propensity to consume excessive amounts of alcohol.
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Affiliation(s)
- Debra K. Cozzoli
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A,Department of Behavioral Neuroscience, Oregon Health & Science University and Portland Alcohol Research Center, VA Portland Healthcare System, Portland, OR 97239, U.S.A
| | - Justin Courson
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Charlotte Rostock
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Rianne R. Campbell
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Melissa G. Wroten
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Hadley McGregor
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Amanda L. Caruana
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Bailey W. Miller
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
| | - Jia-Hua Hu
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, U.S.A
| | - Ping Wu Zhang
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, U.S.A
| | - Bo Xiao
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, U.S.A
| | - Paul F. Worley
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, U.S.A
| | - John C. Crabbe
- Department of Behavioral Neuroscience, Oregon Health & Science University and Portland Alcohol Research Center, VA Portland Healthcare System, Portland, OR 97239, U.S.A
| | - Deborah A. Finn
- Department of Behavioral Neuroscience, Oregon Health & Science University and Portland Alcohol Research Center, VA Portland Healthcare System, Portland, OR 97239, U.S.A
| | - Karen K. Szumlinski
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106-9660, U.S.A
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