1
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Małkowska P. Positive Effects of Physical Activity on Insulin Signaling. Curr Issues Mol Biol 2024; 46:5467-5487. [PMID: 38920999 PMCID: PMC11202552 DOI: 10.3390/cimb46060327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 05/24/2024] [Accepted: 05/28/2024] [Indexed: 06/27/2024] Open
Abstract
Physical activity is integral to metabolic health, particularly in addressing insulin resistance and related disorders such as type 2 diabetes mellitus (T2DM). Studies consistently demonstrate a strong association between physical activity levels and insulin sensitivity. Regular exercise interventions were shown to significantly improve glycemic control, highlighting exercise as a recommended therapeutic strategy for reducing insulin resistance. Physical inactivity is closely linked to islet cell insufficiency, exacerbating insulin resistance through various pathways including ER stress, mitochondrial dysfunction, oxidative stress, and inflammation. Conversely, physical training and exercise preserve and restore islet function, enhancing peripheral insulin sensitivity. Exercise interventions stimulate β-cell proliferation through increased circulating levels of growth factors, further emphasizing its role in maintaining pancreatic health and glucose metabolism. Furthermore, sedentary lifestyles contribute to elevated oxidative stress levels and ceramide production, impairing insulin signaling and glucose metabolism. Regular exercise induces anti-inflammatory responses, enhances antioxidant defenses, and promotes mitochondrial function, thereby improving insulin sensitivity and metabolic efficiency. Encouraging individuals to adopt active lifestyles and engage in regular exercise is crucial for preventing and managing insulin resistance and related metabolic disorders, ultimately promoting overall health and well-being.
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Affiliation(s)
- Paulina Małkowska
- Institute of Physical Culture Sciences, University of Szczecin, 71-065 Szczecin, Poland
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2
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Wu J, Fan S, Feinberg D, Wang X, Jabbar S, Kang Y. Inhibition of Sphingosine Kinase 2 Results in PARK2-Mediated Mitophagy and Induces Apoptosis in Multiple Myeloma. Curr Oncol 2023; 30:3047-3063. [PMID: 36975444 PMCID: PMC10047154 DOI: 10.3390/curroncol30030231] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/09/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023] Open
Abstract
Mitophagy plays an important role in maintaining mitochondrial homeostasis by clearing damaged mitochondria. Sphingosine kinase 2 (SK2), a type of sphingosine kinase, is an important metabolic enzyme involved in generating sphingosine-1-phosphate. Its expression level is elevated in many cancers and is associated with poor clinical outcomes. However, the relationship between SK2 and mitochondrial dysfunction remains unclear. We found that the genetic downregulation of SK2 or treatment with ABC294640, a specific inhibitor of SK2, induced mitophagy and apoptosis in multiple myeloma cell lines. We showed that mitophagy correlates with apoptosis induction and likely occurs through the SET/PP2AC/PARK2 pathway, where inhibiting PP2AC activity may rescue this process. Furthermore, we found that PP2AC and PARK2 form a complex, suggesting that they might regulate mitophagy through protein-protein interactions. Our study demonstrates the important role of SK2 in regulating mitophagy and provides new insights into the mechanism of mitophagy in multiple myeloma.
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Affiliation(s)
| | | | | | | | | | - Yubin Kang
- Division of Hematologic Malignancies and Cellular Therapy, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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3
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Tufano M, Marrone L, D'Ambrosio C, Di Giacomo V, Urzini S, Xiao Y, Matuozzo M, Scaloni A, Romano MF, Romano S. FKBP51 plays an essential role in Akt ubiquitination that requires Hsp90 and PHLPP. Cell Death Dis 2023; 14:116. [PMID: 36781840 PMCID: PMC9925821 DOI: 10.1038/s41419-023-05629-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 01/28/2023] [Accepted: 01/30/2023] [Indexed: 02/15/2023]
Abstract
FKBP51 plays a relevant role in sustaining cancer cells, particularly melanoma. This cochaperone participates in several signaling pathways. FKBP51 forms a complex with Akt and PHLPP, which is reported to dephosphorylate Akt. Given the recent discovery of a spliced FKBP51 isoform, in this paper, we interrogate the canonical and spliced isoforms in regulation of Akt activation. We show that the TPR domain of FKBP51 mediates Akt ubiquitination at K63, which is an essential step for Akt activation. The spliced FKBP51, lacking such domain, cannot link K63-Ub residues to Akt. Unexpectedly, PHLPP silencing does not foster phosphorylation of Akt, and its overexpression even induces phosphorylation of Akt. PHLPP stabilizes levels of E3-ubiquitin ligase TRAF6 and supports K63-ubiquitination of Akt. The interactome profile of FKBP51 from melanoma cells highlights a relevant role for PHLPP in improving oncogenic hallmarks, particularly, cell proliferation.
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Affiliation(s)
- Martina Tufano
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy
| | - Laura Marrone
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy
| | - Chiara D'Ambrosio
- Proteomics, Metabolomics and Mass Spectrometry Laboratory Institute for Animal Production Systems in Mediterranean Environments (ISPAAM), National Research Council (CNR), Piazzale Enrico Fermi 1, Portici, 80055, Naples, Italy
| | - Valeria Di Giacomo
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy
| | - Simona Urzini
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy
| | - Yichuan Xiao
- Chinese Academy of Sciences Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Monica Matuozzo
- Proteomics, Metabolomics and Mass Spectrometry Laboratory Institute for Animal Production Systems in Mediterranean Environments (ISPAAM), National Research Council (CNR), Piazzale Enrico Fermi 1, Portici, 80055, Naples, Italy
| | - Andrea Scaloni
- Proteomics, Metabolomics and Mass Spectrometry Laboratory Institute for Animal Production Systems in Mediterranean Environments (ISPAAM), National Research Council (CNR), Piazzale Enrico Fermi 1, Portici, 80055, Naples, Italy
| | - Maria Fiammetta Romano
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy.
| | - Simona Romano
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy.
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4
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Di Pietro P, Izzo C, Abate AC, Iesu P, Rusciano MR, Venturini E, Visco V, Sommella E, Ciccarelli M, Carrizzo A, Vecchione C. The Dark Side of Sphingolipids: Searching for Potential Cardiovascular Biomarkers. Biomolecules 2023; 13:168. [PMID: 36671552 PMCID: PMC9855992 DOI: 10.3390/biom13010168] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/31/2022] [Accepted: 01/11/2023] [Indexed: 01/14/2023] Open
Abstract
Cardiovascular diseases (CVDs) are the leading cause of death and illness in Europe and worldwide, responsible for a staggering 47% of deaths in Europe. Over the past few years, there has been increasing evidence pointing to bioactive sphingolipids as drivers of CVDs. Among them, most studies place emphasis on the cardiovascular effect of ceramides and sphingosine-1-phosphate (S1P), reporting correlation between their aberrant expression and CVD risk factors. In experimental in vivo models, pharmacological inhibition of de novo ceramide synthesis averts the development of diabetes, atherosclerosis, hypertension and heart failure. In humans, levels of circulating sphingolipids have been suggested as prognostic indicators for a broad spectrum of diseases. This article provides a comprehensive review of sphingolipids' contribution to cardiovascular, cerebrovascular and metabolic diseases, focusing on the latest experimental and clinical findings. Cumulatively, these studies indicate that monitoring sphingolipid level alterations could allow for better assessment of cardiovascular disease progression and/or severity, and also suggest them as a potential target for future therapeutic intervention. Some approaches may include the down-regulation of specific sphingolipid species levels in the circulation, by inhibiting critical enzymes that catalyze ceramide metabolism, such as ceramidases, sphingomyelinases and sphingosine kinases. Therefore, manipulation of the sphingolipid pathway may be a promising strategy for the treatment of cardio- and cerebrovascular diseases.
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Affiliation(s)
- Paola Di Pietro
- Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84081 Baronissi, Italy
| | - Carmine Izzo
- Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84081 Baronissi, Italy
| | - Angela Carmelita Abate
- Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84081 Baronissi, Italy
| | - Paola Iesu
- Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84081 Baronissi, Italy
| | - Maria Rosaria Rusciano
- Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84081 Baronissi, Italy
| | | | - Valeria Visco
- Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84081 Baronissi, Italy
| | - Eduardo Sommella
- Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy
| | - Michele Ciccarelli
- Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84081 Baronissi, Italy
| | - Albino Carrizzo
- Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84081 Baronissi, Italy
- Vascular Physiopathology Unit, IRCCS Neuromed, 86077 Pozzilli, Italy
| | - Carmine Vecchione
- Department of Medicine, Surgery and Dentistry “Scuola Medica Salernitana”, University of Salerno, 84081 Baronissi, Italy
- Vascular Physiopathology Unit, IRCCS Neuromed, 86077 Pozzilli, Italy
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5
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Zhang S, Zhou J, Shang P, Zhao G, Wang A, Mao J, Tao Y, Chen Z, Wang X, Guo C. SET/PP2A signaling regulates macrophage positioning in hypoxic tumor regions by amplifying chemotactic responses. Exp Mol Med 2022; 54:1741-1755. [PMID: 36224346 PMCID: PMC9636225 DOI: 10.1038/s12276-022-00867-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 07/02/2022] [Accepted: 08/01/2022] [Indexed: 12/29/2022] Open
Abstract
Tumor-associated macrophages (TAMs) are one of the main cellular components in the tumor microenvironment (TME). In many types of solid tumors, TAMs tend to accumulate in hypoxic areas and are intimately related to poor patient prognosis. However, the underlying mechanisms by which TAMs infiltrate hypoxic tumor regions remain unclear. In this study, we report that genetic deletion of SE translocation (SET) in myeloid cells inhibited the entry of TAMs into the hypoxic tumor region and abated their proangiogenic and immunosuppressive functions, ultimately inhibiting tumor growth. Mechanistically, in response to hypoxic tumor supernatant stimulation, SET in macrophages shuttled between the nucleus and cytoplasm via the PKC-CK2α signaling axis. Cytoplasmic retention of SET increased ERK and P38 signaling by inhibiting PP2A, which promoted TAM migration into the hypoxic area and polarization toward the M2 phenotype. Therefore, we conclude that SET modulates tumor immunity by acting as a key regulator of macrophage positioning and function in the tumor.
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Affiliation(s)
- Shaolong Zhang
- grid.254147.10000 0000 9776 7793School of Life Science and Technology, China Pharmaceutical University, Nanjing, PR China
| | - Jingping Zhou
- grid.254147.10000 0000 9776 7793School of Life Science and Technology, China Pharmaceutical University, Nanjing, PR China
| | - Pengzhao Shang
- grid.254147.10000 0000 9776 7793School of Life Science and Technology, China Pharmaceutical University, Nanjing, PR China
| | - Guomeng Zhao
- grid.254147.10000 0000 9776 7793School of Life Science and Technology, China Pharmaceutical University, Nanjing, PR China
| | - Anlei Wang
- grid.254147.10000 0000 9776 7793School of Life Science and Technology, China Pharmaceutical University, Nanjing, PR China
| | - Jinlei Mao
- grid.254147.10000 0000 9776 7793School of Life Science and Technology, China Pharmaceutical University, Nanjing, PR China
| | - Yuhang Tao
- grid.254147.10000 0000 9776 7793School of Life Science and Technology, China Pharmaceutical University, Nanjing, PR China
| | - Ziyi Chen
- grid.412676.00000 0004 1799 0784Hepatobiliary/Liver Transplantation Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, PR China
| | - Xuehao Wang
- grid.412676.00000 0004 1799 0784Hepatobiliary/Liver Transplantation Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, PR China
| | - Changying Guo
- grid.254147.10000 0000 9776 7793School of Life Science and Technology, China Pharmaceutical University, Nanjing, PR China
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6
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Idelfonso-García OG, Alarcón-Sánchez BR, Vásquez-Garzón VR, Baltiérrez-Hoyos R, Villa-Treviño S, Muriel P, Serrano H, Pérez-Carreón JI, Arellanes-Robledo J. Is Nucleoredoxin a Master Regulator of Cellular Redox Homeostasis? Its Implication in Different Pathologies. Antioxidants (Basel) 2022; 11:antiox11040670. [PMID: 35453355 PMCID: PMC9030443 DOI: 10.3390/antiox11040670] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/26/2022] [Accepted: 03/28/2022] [Indexed: 01/27/2023] Open
Abstract
Nucleoredoxin (NXN), an oxidoreductase enzyme, contributes to cellular redox homeostasis by regulating different signaling pathways in a redox-dependent manner. By interacting with seven proteins so far, namely disheveled (DVL), protein phosphatase 2A (PP2A), phosphofructokinase-1 (PFK1), translocation protein SEC63 homolog (SEC63), myeloid differentiation primary response gene-88 (MYD88), flightless-I (FLII), and calcium/calmodulin-dependent protein kinase II type alpha (CAMK2A), NXN is involved in the regulation of several key cellular processes, including proliferation, organogenesis, cell cycle progression, glycolysis, innate immunity and inflammation, motility, contraction, protein transport into the endoplasmic reticulum, neuronal plasticity, among others; as a result, NXN has been implicated in different pathologies, such as cancer, alcoholic and polycystic liver disease, liver fibrogenesis, obesity, Robinow syndrome, diabetes mellitus, Alzheimer’s disease, and retinitis pigmentosa. Together, this evidence places NXN as a strong candidate to be a master redox regulator of cell physiology and as the hub of different redox-sensitive signaling pathways and associated pathologies. This review summarizes and discusses the current insights on NXN-dependent redox regulation and its implication in different pathologies.
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Affiliation(s)
- Osiris Germán Idelfonso-García
- Laboratory of Liver Diseases, National Institute of Genomic Medicine–INMEGEN, Mexico City 14610, Mexico; (O.G.I.-G.); (B.R.A.-S.); (J.I.P.-C.)
- Department of Health Sciences, Metropolitan Autonomous University-Iztapalapa Campus, Mexico City 09340, Mexico;
| | - Brisa Rodope Alarcón-Sánchez
- Laboratory of Liver Diseases, National Institute of Genomic Medicine–INMEGEN, Mexico City 14610, Mexico; (O.G.I.-G.); (B.R.A.-S.); (J.I.P.-C.)
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute–CINVESTAV-IPN, Mexico City 07360, Mexico;
| | - Verónica Rocío Vásquez-Garzón
- Laboratory of Fibrosis and Cancer, Faculty of Medicine and Surgery, ‘Benito Juárez’ Autonomous University of Oaxaca–UABJO, Oaxaca 68020, Mexico; (V.R.V.-G.); (R.B.-H.)
- Directorate of Cátedras, National Council of Science and Technology–CONACYT, Mexico City 03940, Mexico
| | - Rafael Baltiérrez-Hoyos
- Laboratory of Fibrosis and Cancer, Faculty of Medicine and Surgery, ‘Benito Juárez’ Autonomous University of Oaxaca–UABJO, Oaxaca 68020, Mexico; (V.R.V.-G.); (R.B.-H.)
- Directorate of Cátedras, National Council of Science and Technology–CONACYT, Mexico City 03940, Mexico
| | - Saúl Villa-Treviño
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute–CINVESTAV-IPN, Mexico City 07360, Mexico;
| | - Pablo Muriel
- Laboratory of Experimental Hepatology, Department of Pharmacology, Center for Research and Advanced Studies of the National Polytechnic Institute–CINVESTAV-IPN, Mexico City 07360, Mexico;
| | - Héctor Serrano
- Department of Health Sciences, Metropolitan Autonomous University-Iztapalapa Campus, Mexico City 09340, Mexico;
| | - Julio Isael Pérez-Carreón
- Laboratory of Liver Diseases, National Institute of Genomic Medicine–INMEGEN, Mexico City 14610, Mexico; (O.G.I.-G.); (B.R.A.-S.); (J.I.P.-C.)
| | - Jaime Arellanes-Robledo
- Laboratory of Liver Diseases, National Institute of Genomic Medicine–INMEGEN, Mexico City 14610, Mexico; (O.G.I.-G.); (B.R.A.-S.); (J.I.P.-C.)
- Directorate of Cátedras, National Council of Science and Technology–CONACYT, Mexico City 03940, Mexico
- Correspondence: ; Tel.: +52-55-5350-1900 (ext. 1218)
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7
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Yan Q, Zhang B, Ling X, Zhu B, Mei S, Yang H, Zhang D, Huo J, Zhao Z. CTLA-4 Facilitates DNA Damage–Induced Apoptosis by Interacting With PP2A. Front Cell Dev Biol 2022; 10:728771. [PMID: 35281086 PMCID: PMC8907142 DOI: 10.3389/fcell.2022.728771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 01/06/2022] [Indexed: 12/15/2022] Open
Abstract
Cytotoxic T-lymphocyte–associated protein 4 (CTLA-4) plays a pivotal role in regulating immune responses. It accumulates in intracellular compartments, translocates to the cell surface, and is rapidly internalized. However, the cytoplasmic function of CTLA-4 remains largely unknown. Here, we describe the role of CTLA-4 as an immunomodulator in the DNA damage response to genotoxic stress. Using isogenic models of murine T cells with either sufficient or deficient CTLA-4 expression and performing a variety of assays, including cell apoptosis, cell cycle, comet, western blotting, co-immunoprecipitation, and immunofluorescence staining analyses, we show that CTLA-4 activates ataxia–telangiectasia mutated (ATM) by binding to the ATM inhibitor protein phosphatase 2A into the cytoplasm of T cells following transient treatment with zeocin, exacerbating the DNA damage response and inducing apoptosis. These findings provide new insights into how T cells maintain their immune function under high-stress conditions, which is clinically important for patients with tumors undergoing immunotherapy combined with chemoradiotherapy.
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Affiliation(s)
- Qiongyu Yan
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Bin Zhang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xi Ling
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Bin Zhu
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Shenghui Mei
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Hua Yang
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Dongjie Zhang
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jiping Huo
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Zhigang Zhao
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- *Correspondence: Zhigang Zhao,
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8
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Lee SH, Park SY, Choi CS. Insulin Resistance: From Mechanisms to Therapeutic Strategies. Diabetes Metab J 2022; 46:15-37. [PMID: 34965646 PMCID: PMC8831809 DOI: 10.4093/dmj.2021.0280] [Citation(s) in RCA: 238] [Impact Index Per Article: 119.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 12/27/2021] [Indexed: 11/12/2022] Open
Abstract
Insulin resistance is the pivotal pathogenic component of many metabolic diseases, including type 2 diabetes mellitus, and is defined as a state of reduced responsiveness of insulin-targeting tissues to physiological levels of insulin. Although the underlying mechanism of insulin resistance is not fully understood, several credible theories have been proposed. In this review, we summarize the functions of insulin in glucose metabolism in typical metabolic tissues and describe the mechanisms proposed to underlie insulin resistance, that is, ectopic lipid accumulation in liver and skeletal muscle, endoplasmic reticulum stress, and inflammation. In addition, we suggest potential therapeutic strategies for addressing insulin resistance.
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Affiliation(s)
- Shin-Hae Lee
- Korea Mouse Metabolic Phenotyping Center (KMMPC), Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea
| | - Shi-Young Park
- Korea Mouse Metabolic Phenotyping Center (KMMPC), Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea
| | - Cheol Soo Choi
- Korea Mouse Metabolic Phenotyping Center (KMMPC), Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea
- Department of Internal Medicine, Gachon University Gil Medical Center, Incheon, Korea
- Division of Molecular Medicine, Gachon University College of Medicine, Incheon, Korea
- Corresponding author: Cheol Soo Choi https://orcid.org/0000-0001-9627-058X Division of Molecular Medicine, Gachon University College of Medicine, 21 Namdongdaero 774beon-gil, Namdong-gu, Incheon 21565, Korea E-mail:
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9
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Fan J, Liu Y, Kong R, Ni D, Yu Z, Lu S, Zhang J. Harnessing Reversed Allosteric Communication: A Novel Strategy for Allosteric Drug Discovery. J Med Chem 2021; 64:17728-17743. [PMID: 34878270 DOI: 10.1021/acs.jmedchem.1c01695] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Allostery is a fundamental and extensive mechanism of intramolecular signal transmission. Allosteric drugs possess several unique pharmacological advantages over traditional orthosteric drugs, including greater selectivity, better physicochemical properties, and lower off-target toxicity. However, owing to the complexity of allosteric regulation, experimental approaches for the development of allosteric modulators are traditionally serendipitous. Recently, the reversed allosteric communication theory has been proposed, providing a feasible tool for the unbiased detection of allosteric sites. Herein, we review the latest research on the reversed allosteric communication effect using the examples of sirtuin 6, epidermal growth factor receptor, 3-phosphoinositide-dependent protein kinase 1, and Related to A and C kinases (RAC) serine/threonine protein kinase B and recapitulate the methodologies of reversed allosteric communication strategy. The novel reversed allosteric communication strategy greatly expands the horizon of allosteric site identification and allosteric mechanism exploration and is expected to accelerate an end-to-end framework for drug discovery.
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Affiliation(s)
- Jigang Fan
- College of Pharmacy, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, China.,State Key Laboratory of Oncogenes and Related Genes, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China.,Zhiyuan Innovative Research Center, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yaqin Liu
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Ren Kong
- Institute of Bioinformatics and Medical Engineering, School of Electrical and Information Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Duan Ni
- The Charles Perkins Centre, University of Sydney, Sydney, New South Wales 2006, Australia
| | | | - Shaoyong Lu
- College of Pharmacy, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, China.,State Key Laboratory of Oncogenes and Related Genes, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China.,Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Jian Zhang
- College of Pharmacy, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, China.,State Key Laboratory of Oncogenes and Related Genes, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China.,Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China.,School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, China
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10
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Zeng Q, Jin F, Qian H, Chen H, Wang Y, Zhang D, Wei Y, Chen T, Guo B, Chai C. The miR-345-3p/PPP2CA signaling axis promotes proliferation and invasion of breast cancer cells. Carcinogenesis 2021; 43:150-159. [PMID: 34922339 DOI: 10.1093/carcin/bgab124] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/27/2021] [Accepted: 12/10/2021] [Indexed: 11/13/2022] Open
Abstract
Breast cancer is the most common malignancy among women worldwide. Functional studies have demonstrated that miRNA dysregulation in many cases of cancer, in which miRNAs acting as either oncogenes or tumor suppressor. Here we report that miR-345-3p is generally upregulated in breast cancer tissues and breast cancer cell lines. Overexpression and inhibition of miR-345-3p revealed its capacity in regulating proliferation and invasion of breast cancer cells. Further research identified protein phosphatase 2 catalytic subunit alpha (PPP2CA), a suppressor of AKT phosphorylation, as a candidate target of miR-345-3p. In vitro, miR-345-3p mimics promoted AKT phosphorylation by targeting its negative regulator, PPP2CA. Blocking miR-345-3p relieves its inhibition of PPP2CA, which attenuated PI3K-AKT signaling pathway. In vivo, inhibiting miR-345-3p with miR-345-3p-inhibition lentivirus suppressed tumor growth and invasiveness in mice. Together, the miR-345-3p/PPP2CA signaling axis exhibits tumor promoting functions by regulating proliferation and invasion of breast cancer cells. These data provide a clue to novel therapeutic approaches for breast cancer.
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Affiliation(s)
- Qian Zeng
- Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing, P.R. China
| | - Fangfang Jin
- Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing, P.R. China
| | - Husun Qian
- Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing, P.R. China
| | - Hongling Chen
- Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing, P.R. China
| | - Yange Wang
- Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing, P.R. China
| | - Dian Zhang
- Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing, P.R. China
| | - Yu Wei
- Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing, P.R. China
| | - Tingmei Chen
- Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing, P.R. China
| | - Bianqin Guo
- Department of Clinical Laboratory, Chongqing University Cancer Hospital, Chongqing, P.R. China
| | - Chengsen Chai
- Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing, P.R. China
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Sindhu S, Leung YH, Arefanian H, Madiraju SRM, Al‐Mulla F, Ahmad R, Prentki M. Neutral sphingomyelinase-2 and cardiometabolic diseases. Obes Rev 2021; 22:e13248. [PMID: 33738905 PMCID: PMC8365731 DOI: 10.1111/obr.13248] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/18/2021] [Accepted: 02/26/2021] [Indexed: 12/13/2022]
Abstract
Sphingolipids, in particular ceramides, play vital role in pathophysiological processes linked to metabolic syndrome, with implications in the development of insulin resistance, pancreatic ß-cell dysfunction, type 2 diabetes, atherosclerosis, inflammation, nonalcoholic steatohepatitis, and cancer. Ceramides are produced by the hydrolysis of sphingomyelin, catalyzed by different sphingomyelinases, including neutral sphingomyelinase 2 (nSMase2), whose dysregulation appears to underlie many of the inflammation-related pathologies. In this review, we discuss the current knowledge on the biochemistry of nSMase2 and ceramide production and its regulation by inflammatory cytokines, with particular reference to cardiometabolic diseases. nSMase2 contribution to pathogenic processes appears to involve cyclical feed-forward interaction with proinflammatory cytokines, such as TNF-α and IL-1ß, which activate nSMase2 and the production of ceramides, that in turn triggers the synthesis and release of inflammatory cytokines. We elaborate these pathogenic interactions at the molecular level and discuss the potential therapeutic benefits of inhibiting nSMase2 against inflammation-driven cardiometabolic diseases.
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Affiliation(s)
- Sardar Sindhu
- Animal and Imaging core facilityDasman Diabetes InstituteDasmanKuwait
| | - Yat Hei Leung
- Departments of Nutrition, Biochemistry and Molecular MedicineUniversity of MontrealMontréalQuebecCanada
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM)Montreal Diabetes Research CenterMontréalQuebecCanada
| | - Hossein Arefanian
- Immunology and Microbiology DepartmentDasman Diabetes InstituteDasmanKuwait
| | - S. R. Murthy Madiraju
- Departments of Nutrition, Biochemistry and Molecular MedicineUniversity of MontrealMontréalQuebecCanada
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM)Montreal Diabetes Research CenterMontréalQuebecCanada
| | - Fahd Al‐Mulla
- Department of Genetics and BioinformaticsDasman Diabetes InstituteDasmanKuwait
| | - Rasheed Ahmad
- Immunology and Microbiology DepartmentDasman Diabetes InstituteDasmanKuwait
| | - Marc Prentki
- Departments of Nutrition, Biochemistry and Molecular MedicineUniversity of MontrealMontréalQuebecCanada
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM)Montreal Diabetes Research CenterMontréalQuebecCanada
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12
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Akt Isoforms: A Family Affair in Breast Cancer. Cancers (Basel) 2021; 13:cancers13143445. [PMID: 34298660 PMCID: PMC8306188 DOI: 10.3390/cancers13143445] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 12/11/2022] Open
Abstract
Simple Summary Breast cancer is the second leading cause of cancer-related death in women in the United States. The Akt signaling pathway is deregulated in approximately 70% of patients with breast cancer. While targeting Akt is an effective therapeutic strategy for the treatment of breast cancer, there are several members in the Akt family that play distinct roles in breast cancer. However, the function of Akt isoforms depends on many factors. This review analyzes current progress on the isoform-specific functions of Akt isoforms in breast cancer. Abstract Akt, also known as protein kinase B (PKB), belongs to the AGC family of protein kinases. It acts downstream of the phosphatidylinositol 3-kinase (PI3K) and regulates diverse cellular processes, including cell proliferation, cell survival, metabolism, tumor growth and metastasis. The PI3K/Akt signaling pathway is frequently deregulated in breast cancer and plays an important role in the development and progression of breast cancer. There are three closely related members in the Akt family, namely Akt1(PKBα), Akt2(PKBβ) and Akt3(PKBγ). Although Akt isoforms share similar structures, they exhibit redundant, distinct as well as opposite functions. While the Akt signaling pathway is an important target for cancer therapy, an understanding of the isoform-specific function of Akt is critical to effectively target this pathway. However, our perception regarding how Akt isoforms contribute to the genesis and progression of breast cancer changes as we gain new knowledge. The purpose of this review article is to analyze current literatures on distinct functions of Akt isoforms in breast cancer.
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13
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Liu T, Gatto NM, Chen Z, Qiu H, Lee G, Duerksen-Hughes P, Fraser G, Wang C. Vegetarian diets, circulating miRNA expression and healthspan in subjects living in the Blue Zone. PRECISION CLINICAL MEDICINE 2021; 3:245-259. [PMID: 33391847 PMCID: PMC7757436 DOI: 10.1093/pcmedi/pbaa037] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 10/11/2020] [Accepted: 10/18/2020] [Indexed: 12/21/2022] Open
Abstract
A long-term vegetarian diet plays a role in the longevity and maintenance of the healthspan, but the underlying mechanisms for these observations are largely unknown. Particularly, it is not known whether a long-term vegetarian dietary pattern may affect the circulating miRNA expression in such a way as to modulate the healthspan. The Adventist Health Study-2 (AHS-2) cohort includes a large number of older adults who primarily follow vegetarian dietary patterns and reside in Loma Linda, California, one of five “Blue Zones” in the world in which a higher proportion of the population enjoys a longer than average lifespan. We performed miRNA-seq in 96 subjects selected from the AHS-2 cohort with different dietary patterns. We identified several differentially expressed miRNAs between vegetarians and non-vegetarians, which are involved in immune response and cytokine signaling, cell growth and proliferation as well as age-related diseases such as cardiovascular diseases and neurodegenerative diseases. Overall, our study showed that a vegetarian diet modulates aging-associated circulating miRNAs in a sex-dependent manner of differential expression for certain miRNAs, which may be related in a beneficial manner to the healthspan. Further investigation is needed to validate these miRNAs as potential biomarkers for diet-modulated longevity in humans.
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Affiliation(s)
- Tiantian Liu
- Center for Genomics, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
| | - Nicole M Gatto
- School of Community and Global Health, Claremont Graduate University, Claremont, CA 91711, USA
| | - Zhong Chen
- Center for Genomics, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
| | - Hongyu Qiu
- Center of Molecular and Translational Medicine, Institution of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA
| | - Grace Lee
- Department of Psychology, School of Behavioral Health, Loma Linda University, Loma Linda, CA 92350, USA
| | - Penelope Duerksen-Hughes
- Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
| | - Gary Fraser
- School of Public Health, Loma Linda University, Loma Linda, CA 92350, USA
| | - Charles Wang
- Center for Genomics, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
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14
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The Influence of Physical Activity on the Bioactive Lipids Metabolism in Obesity-Induced Muscle Insulin Resistance. Biomolecules 2020; 10:biom10121665. [PMID: 33322719 PMCID: PMC7764345 DOI: 10.3390/biom10121665] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/08/2020] [Accepted: 12/11/2020] [Indexed: 12/14/2022] Open
Abstract
High-fat diet consumption and lack of physical activity are important risk factors for metabolic disorders such as insulin resistance and cardiovascular diseases. Insulin resistance is a state of a weakened response of tissues such as skeletal muscle, adipose tissue, and liver to insulin, which causes an increase in blood glucose levels. This condition is the result of inhibition of the intracellular insulin signaling pathway. Skeletal muscle is an important insulin-sensitive tissue that accounts for about 80% of insulin-dependent glucose uptake. Although the exact mechanism by which insulin resistance is induced has not been thoroughly understood, it is known that insulin resistance is most commonly associated with obesity. Therefore, it is believed that lipids may play an important role in inducing insulin resistance. Among lipids, researchers’ attention is mainly focused on biologically active lipids: diacylglycerols (DAG) and ceramides. These lipids are able to regulate the activity of intracellular enzymes, including those involved in insulin signaling. Available data indicate that physical activity affects lipid metabolism and has a positive effect on insulin sensitivity in skeletal muscles. In this review, we have presented the current state of knowledge about the impact of physical activity on insulin resistance and metabolism of biologically active lipids.
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15
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He X, Li M, Yu H, Liu G, Wang N, Yin C, Tu Q, Narla G, Tao Y, Cheng S, Yin H. Loss of hepatic aldolase B activates Akt and promotes hepatocellular carcinogenesis by destabilizing the Aldob/Akt/PP2A protein complex. PLoS Biol 2020; 18:e3000803. [PMID: 33275593 PMCID: PMC7744066 DOI: 10.1371/journal.pbio.3000803] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 12/16/2020] [Accepted: 11/13/2020] [Indexed: 12/21/2022] Open
Abstract
Loss of hepatic fructose-1, 6-bisphosphate aldolase B (Aldob) leads to a paradoxical up-regulation of glucose metabolism to favor hepatocellular carcinogenesis (HCC), but the upstream signaling events remain poorly defined. Akt is highly activated in HCC, and targeting Akt is being explored as a potential therapy for HCC. Herein, we demonstrate that Aldob suppresses Akt activity and tumor growth through a protein complex containing Aldob, Akt, and protein phosphatase 2A (PP2A), leading to inhibition of cell viability, cell cycle progression, glucose uptake, and metabolism. Interestingly, Aldob directly interacts with phosphorylated Akt (p-Akt) and promotes the recruitment of PP2A to dephosphorylate p-Akt, and this scaffolding effect of Aldob is independent of its enzymatic activity. Loss of Aldob or disruption of Aldob/Akt interaction in Aldob R304A mutant restores Akt activity and tumor-promoting effects. Consistently, Aldob and p-Akt expression are inversely correlated in human HCC tissues, and Aldob down-regulation coupled with p-Akt up-regulation predicts a poor prognosis for HCC. We have further discovered that Akt inhibition or a specific small-molecule activator of PP2A (SMAP) efficiently attenuates HCC tumorigenesis in xenograft mouse models. Our work reveals a novel nonenzymatic role of Aldob in negative regulation of Akt activation, suggesting that directly inhibiting Akt activity or through reactivating PP2A may be a potential therapeutic approach for HCC treatment.
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Affiliation(s)
- Xuxiao He
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Min Li
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Hongming Yu
- The Eastern Hepatobiliary Surgery Hospital, Shanghai, China
| | - Guijun Liu
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Ningning Wang
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Chunzhao Yin
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Qiaochu Tu
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Goutham Narla
- Division of Genetic Medicine, Department of International Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Yongzhen Tao
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
| | - Shuqun Cheng
- The Eastern Hepatobiliary Surgery Hospital, Shanghai, China
| | - Huiyong Yin
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences (CAS), Shanghai, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing, China
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16
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Colle JH, Périchon B, Garcia A. Antitumor and antibacterial properties of virally encoded cationic sequences. Biologics 2019; 13:117-126. [PMID: 31417238 PMCID: PMC6599856 DOI: 10.2147/btt.s201287] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 03/22/2019] [Indexed: 11/30/2022]
Abstract
Objective: The objective of this study was to test our Viral Quinta Columna Strategy (VQCS), a new biological hypothesis predicting that specific multifunctional virally encoded cationic domains may have the capacity to penetrate human cells and interact with PP2A proteins to deregulate important human intracellular pathways, and may display LL37 cathelicidin-like antagonistic effects against multiple pathogens such as bacteria or viruses. Methods: We comparatively analyzed the host defense properties of adenodiaphorins and of some specific cationic sequences encoded by different viruses using two distinct biological models: U87G, a well-characterized cell tumor model; and a group B Streptococcus agalactiae NEM316 ΔdltA, highly sensitive to LL37 cathelicidin. Results: We found that the adenovirus type 2 E4orf4 is a cell-permeable protein containing a new E4orf464–95 protein transduction domain, named large adenodiaphorin or LadD64–95. Interestingly, the host defense LL37 peptide is the unique cathelicidin in humans. In this context, we also demonstrated that similarly to LL37 LadD64–95, several virally encoded cationic sequences including the C-terminus HIV-1 89.6 Vpr77–92, shorter adenodiaphorins AdD67–84/AdD/69–84/AdD69–83, as well as HIV-2 Tat67–90 and JC polyomavirus small t115–134, displayed similar toxicity against Gram-positive S. agalactiae NEM316 ΔdltA strain. Finally, LadD64–95, adenodiaphorin AdD67–84, AdD69–84, and LL37 and LL17–32 cathelicidin peptides also inhibited the survival of human U87G glioblastoma cells. Conclusion: In this study, we demonstrated that specific cationic sequences encoded by four different viruses displayed antibacterial activities against S. agalactiae NEM316 ΔdltA strain. In addition, HIV-1 Vpr71–92 and adenovirus 2 E4orf464–95, two cationic penetrating sequences that bind PP2A, inhibited the survival of U87G glioblastoma cells. These results illustrate the host defense properties of virally encoded sequences and could represent an initial step for future complete validation of the VQCS hypothesis.
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Affiliation(s)
- Jean-Hervé Colle
- Laboratoire E3 des Phosphatases-Unité RMN, Institut Pasteur, Paris, France
| | - Bruno Périchon
- Unité de Biologie des Bactéries pathogènes à Gram-positif, Institut Pasteur, Paris, France
| | - Alphonse Garcia
- Laboratoire E3 des Phosphatases-Unité RMN, Institut Pasteur, Paris, France.,Département de Biologie Structurale et Chimie et pôle Dde-Design de la Biologie, Institut Pasteur, Paris, France
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17
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Hawse WF, Cattley RT. T cells transduce T-cell receptor signal strength by generating different phosphatidylinositols. J Biol Chem 2019; 294:4793-4805. [PMID: 30692200 DOI: 10.1074/jbc.ra118.006524] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/14/2019] [Indexed: 12/26/2022] Open
Abstract
T-cell receptor (TCR) signaling strength is a dominant factor regulating T-cell differentiation, thymic development, and cytokine signaling. The molecular mechanisms by which TCR signal strength is transduced to downstream signaling networks remains ill-defined. Using computational modeling, biochemical assays, and imaging flow cytometry, we found here that TCR signal strength differentially generates phosphatidylinositol species. Weak TCR signals generated elevated phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and reduced phosphatidylinositol (3,4,5)-trisphosphate (PIP3) levels, whereas strong TCR signals reduced PI(4,5)P2 and elevated PIP3 levels. A proteomics screen revealed that focal adhesion kinase bound PI(4,5)P2, biochemical assays disclosed that focal adhesion kinase is preferentially activated by weak TCR signals and is required for optimal Treg induction, and further biochemical experiments revealed how TCR signaling strength regulates AKT activation. Low PIP3 levels generated by weak TCR signals were sufficient to activate phosphoinositide-dependent kinase-1 to phosphorylate AKT on Thr-308 but insufficient to activate mTOR complex 2 (mTORC2), whereas elevated PIP3 levels generated by a strong TCR signal were required to activate mTORC2 to phosphorylate Ser-473 on AKT. Our results provide support for a model that links TCR signaling to mTORC2 activation via phosphoinositide 3-kinase signaling. Together, the findings in this work establish that T cells measure TCR signal strength by generating different levels of phosphatidylinositol species that engage alternate signaling networks to control cell fate decisions.
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Affiliation(s)
- William F Hawse
- From the Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Richard T Cattley
- From the Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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18
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Narla G, Sangodkar J, Ryder CB. The impact of phosphatases on proliferative and survival signaling in cancer. Cell Mol Life Sci 2018; 75:2695-2718. [PMID: 29725697 PMCID: PMC6023766 DOI: 10.1007/s00018-018-2826-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/24/2018] [Accepted: 04/23/2018] [Indexed: 02/06/2023]
Abstract
The dynamic and stringent coordination of kinase and phosphatase activity controls a myriad of physiologic processes. Aberrations that disrupt the balance of this interplay represent the basis of numerous diseases. For a variety of reasons, early work in this area portrayed kinases as the dominant actors in these signaling events with phosphatases playing a secondary role. In oncology, these efforts led to breakthroughs that have dramatically altered the course of certain diseases and directed vast resources toward the development of additional kinase-targeted therapies. Yet, more recent scientific efforts have demonstrated a prominent and sometimes driving role for phosphatases across numerous malignancies. This maturation of the phosphatase field has brought with it the promise of further therapeutic advances in the field of oncology. In this review, we discuss the role of phosphatases in the regulation of cellular proliferation and survival signaling using the examples of the MAPK and PI3K/AKT pathways, c-Myc and the apoptosis machinery. Emphasis is placed on instances where these signaling networks are perturbed by dysregulation of specific phosphatases to favor growth and persistence of human cancer.
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Affiliation(s)
| | - Jaya Sangodkar
- Icahn School of Medicine at Mount Sinai, New York, NY, USA
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19
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Bayarkhangai B, Noureldin S, Yu L, Zhao N, Gu Y, Xu H, Guo C. A comprehensive and perspective view of oncoprotein SET in cancer. Cancer Med 2018; 7:3084-3094. [PMID: 29749127 PMCID: PMC6051184 DOI: 10.1002/cam4.1526] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 03/25/2018] [Accepted: 04/05/2018] [Indexed: 12/16/2022] Open
Abstract
SET is a multifunctional oncoprotein which is ubiquitously expressed in all kinds of cells. The SET protein participates in many cellular processes including cell cycle, cell migration, apoptosis, transcription, and DNA repair. Accumulating evidence demonstrates that the expression and activity of SET correlate with cancer occurrence, metastasis, and prognosis. Therefore, the SET protein is regarded as a potential target for cancer therapy and several inhibitors are being developed for clinical use. Herein, we comprehensively review the physiological and pathological functions of SET as well as its structure-function relationship. Additionally, the regulatory mechanisms of SET at both transcriptional and posttranslational levels are also discussed.
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Affiliation(s)
- Buuvee Bayarkhangai
- State Key of Natural Medicine, China Pharmaceutical University, Nanjing, China
| | - Suzan Noureldin
- State Key of Natural Medicine, China Pharmaceutical University, Nanjing, China
| | - Liting Yu
- State Key of Natural Medicine, China Pharmaceutical University, Nanjing, China
| | - Na Zhao
- State Key of Natural Medicine, China Pharmaceutical University, Nanjing, China
| | - Yaru Gu
- State Key of Natural Medicine, China Pharmaceutical University, Nanjing, China
| | - Hanmei Xu
- State Key of Natural Medicine, China Pharmaceutical University, Nanjing, China
| | - Changying Guo
- State Key of Natural Medicine, China Pharmaceutical University, Nanjing, China
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20
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Dithiolethiones: a privileged pharmacophore for anticancer therapy and chemoprevention. Future Med Chem 2018; 10:1241-1260. [DOI: 10.4155/fmc-2017-0281] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Dithiolethiones are five-membered sulfur-containing cyclic scaffolds that exhibit antioxidative, anti-inflammatory, antithrombic and chemotherapeutic activities. Dithiolethiones display the chemopreventive and cytoprotective effects by activating the antioxidant response element and mounting the transcription of cytoprotective phase II enzymatic machinery. In addition, several classes of dithiolethiones efficiently modulate the activities of proteins that play crucial roles in normal and cancer cells, including glutathione S-transferase, cyclooxygenases and master regulator NF-κB. The present paper summarizes synthetic aspects, pharmacological potentials and biological attributes of dithiolethiones and its derivatives. Additionally, this review concludes with a discussion on how the current state-of-the-art technologies may help in defining a structure–activity relationship of dithiolethiones, thereby facilitating the design and synthesis of potent drug candidates.
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21
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Lučić I, Rathinaswamy MK, Truebestein L, Hamelin DJ, Burke JE, Leonard TA. Conformational sampling of membranes by Akt controls its activation and inactivation. Proc Natl Acad Sci U S A 2018; 115:E3940-E3949. [PMID: 29632185 PMCID: PMC5924885 DOI: 10.1073/pnas.1716109115] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The protein kinase Akt controls myriad signaling processes in cells, ranging from growth and proliferation to differentiation and metabolism. Akt is activated by a combination of binding to the lipid second messenger PI(3,4,5)P3 and its subsequent phosphorylation by phosphoinositide-dependent kinase 1 and mechanistic target of rapamycin complex 2. The relative contributions of these mechanisms to Akt activity and signaling have hitherto not been understood. Here, we show that phosphorylation and activation by membrane binding are mutually interdependent. Moreover, the converse is also true: Akt is more rapidly dephosphorylated in the absence of PIP3, an autoinhibitory process driven by the interaction of its PH and kinase domains. We present biophysical evidence for the conformational changes in Akt that accompany its activation on membranes, show that Akt is robustly autoinhibited in the absence of PIP3 irrespective of its phosphorylation, and map the autoinhibitory PH-kinase interface. Finally, we present a model for the activation and inactivation of Akt by an ordered series of membrane binding, phosphorylation, dissociation, and dephosphorylation events.
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Affiliation(s)
- Iva Lučić
- Department of Structural and Computational Biology, Max F. Perutz Laboratories, 1030 Vienna, Austria
- Center for Medical Biochemistry, Medical University of Vienna, 1030 Vienna, Austria
| | - Manoj K Rathinaswamy
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada V8W 2Y2
| | - Linda Truebestein
- Department of Structural and Computational Biology, Max F. Perutz Laboratories, 1030 Vienna, Austria
- Center for Medical Biochemistry, Medical University of Vienna, 1030 Vienna, Austria
| | - David J Hamelin
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada V8W 2Y2
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada V8W 2Y2
| | - Thomas A Leonard
- Department of Structural and Computational Biology, Max F. Perutz Laboratories, 1030 Vienna, Austria;
- Center for Medical Biochemistry, Medical University of Vienna, 1030 Vienna, Austria
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22
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Yang Y, Dong R, Chen Z, Hu D, Fu M, Tang Y, Wang DW, Xu X, Tu L. Endothelium-specific CYP2J2 overexpression attenuates age-related insulin resistance. Aging Cell 2018; 17. [PMID: 29318723 PMCID: PMC5847864 DOI: 10.1111/acel.12718] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2017] [Indexed: 12/18/2022] Open
Abstract
Ample evidences demonstrate that cytochrome P450 epoxygenase‐derived epoxyeicosatrienoic acids (EETs) exert diverse biological activities, which include potent vasodilatory, anti‐inflammatory, and cardiovascular protective effects. In this study, we investigated the effects of endothelium‐specific CYP2J2 overexpression on age‐related insulin resistance and metabolic dysfunction. Endothelium‐specific targeting of the human CYP epoxygenase, CYP2J2, transgenic mice (Tie2‐CYP2J2‐Tr mice) was utilized. The effects of endothelium‐specific CYP2J2 overexpression on aging‐associated obesity, inflammation, and peripheral insulin resistance were evaluated by assessing metabolic parameters in young (3 months old) and aged (16 months old) adult male Tie2‐CYP2J2‐Tr mice. Decreased insulin sensitivity and attenuated insulin signaling in aged skeletal muscle, adipose tissue, and liver were observed in aged adult male mice, and moreover, these effects were partly inhibited in 16‐month‐old CYP2J2‐Tr mice. In addition, CYP2J2 overexpression‐mediated insulin sensitization in aged mice was associated with the amelioration of inflammatory state. Notably, the aging‐associated increases in fat mass and adipocyte size were only observed in 16‐month‐old wild‐type mice, and CYP2J2 overexpression markedly prevented the increase in fat mass and adipocyte size in aged Tie2‐CYP2J2‐Tr mice, which was associated with increased energy expenditure and decreased lipogenic genes expression. Furthermore, these antiaging phenotypes of Tie2‐CYP2J2‐Tr mice were also associated with increased muscle blood flow, enhanced active‐phase locomotor activity, and improved mitochondrial dysfunction in skeletal muscle. Collectively, our findings indicated that endothelium‐specific CYP2J2 overexpression alleviated age‐related insulin resistance and metabolic dysfunction, which highlighted CYP epoxygenase‐EET system as a potential target for combating aging‐related metabolic disorders.
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Affiliation(s)
- Yan Yang
- Department of Geriatric Medicine; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
| | - Ruolan Dong
- Department of Geriatric Medicine; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
| | - Zhihui Chen
- Department of Geriatric Medicine; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
| | - Danli Hu
- Department of Geriatric Medicine; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
| | - Menglu Fu
- Department of Geriatric Medicine; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
| | - Ying Tang
- Department of Geriatric Medicine; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
| | - Dao Wen Wang
- Hubei Key laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders and Division of Cardiology; Department of Internal Medicine; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
| | - Xizhen Xu
- Hubei Key laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders and Division of Cardiology; Department of Internal Medicine; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
| | - Ling Tu
- Department of Geriatric Medicine; Tongji Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
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23
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Abstract
Small viral proteins with cationic domains can be involved in multiple biological processes including cell penetration or interaction with intracellular targets. Within the last two decades several reports indicated that the C-terminus of HIV-1 Vpr is a cell penetrating sequence, a PP2A-dependent death domain and also displays toxicity against Gram-negative E. coli. Interestingly, HIV-1 Vpr, as well as some cationic proteins encoded by different viruses, share similar physical properties with the unique anti-microbial human cathelicidin LL37 peptide. Consistent with these observations, the Viral Quinta Columna Hypothesis predicts that virally-encoded cationic peptides encoded by multiple viruses may at the same time i) behave as new cathelicidin-like viral positive effectors of innate immunity, mainly through electrostatic interactions with microbial walls, and also display specific toxic cellular effects through interactions with specific intracellular targets such as PP2A proteins. In this context, virally-encoded cationic peptides, potentially detectable in biological fluids, may define a new paradigm for a viral control of homeostasis. Finally, we can also predict that characterization of virally encoded sequences with anti-infective effects may serve as template for the design of new efficient therapeutics polypeptides.
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Affiliation(s)
- Alphonse Garcia
- Laboratoire E3 Phosphatases, Unité RMN, Institut Pasteur, 25 rue du Dr. Roux, 75015 Paris, France.
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24
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Law IKM, Padua DM, Iliopoulos D, Pothoulakis C. Role of G protein-coupled receptors-microRNA interactions in gastrointestinal pathophysiology. Am J Physiol Gastrointest Liver Physiol 2017; 313:G361-G372. [PMID: 28774868 PMCID: PMC5792214 DOI: 10.1152/ajpgi.00144.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/13/2017] [Accepted: 07/24/2017] [Indexed: 01/31/2023]
Abstract
G protein-coupled receptors (GPCRs) make up the largest transmembrane receptor superfamily in the human genome and are expressed in nearly all gastrointestinal cell types. Coupling of GPCRs and their respective ligands activates various phosphotransferases in the cytoplasm, and, thus, activation of GPCR signaling in intestine regulates many cellular and physiological processes. Studies in microRNAs (miRNAs) demonstrate that they represent critical epigenetic regulators of different pathophysiological responses in different organs and cell types in humans and animals. Here, we reviewed recent research on GPCR-miRNA interactions related to gastrointestinal pathophysiology, such as inflammatory bowel diseases, irritable bowel syndrome, and gastrointestinal cancers. Given that the presence of different types of cells in the gastrointestinal tract suggests the importance of cell-cell interactions in maintaining gastrointestinal homeostasis, we also discuss how GPCR-miRNA interactions regulate gene expression at the cellular level and subsequently modulate gastrointestinal pathophysiology through molecular regulatory circuits and cell-cell interactions. These studies helped identify novel molecular pathways leading to the discovery of potential biomarkers for gastrointestinal diseases.
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Affiliation(s)
- Ivy Ka Man Law
- 1Center for Inflammatory Bowel Diseases, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
| | - David Miguel Padua
- 1Center for Inflammatory Bowel Diseases, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
| | - Dimitrios Iliopoulos
- 1Center for Inflammatory Bowel Diseases, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and ,2Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California
| | - Charalabos Pothoulakis
- Center for Inflammatory Bowel Diseases, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
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25
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Hawse WF, Boggess WC, Morel PA. TCR Signal Strength Regulates Akt Substrate Specificity To Induce Alternate Murine Th and T Regulatory Cell Differentiation Programs. THE JOURNAL OF IMMUNOLOGY 2017; 199:589-597. [PMID: 28600288 DOI: 10.4049/jimmunol.1700369] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/19/2017] [Indexed: 12/31/2022]
Abstract
The Akt/mTOR pathway is a key driver of murine CD4+ T cell differentiation, and induction of regulatory T (Treg) cells results from low TCR signal strength and low Akt/mTOR signaling. However, strong TCR signals induce high Akt activity that promotes Th cell induction. Yet, it is unclear how Akt controls alternate T cell fate decisions. We find that the strength of the TCR signal results in differential Akt enzymatic activity. Surprisingly, the Akt substrate networks associated with T cell fate decisions are qualitatively different. Proteomic profiling of Akt signaling networks during Treg versus Th induction demonstrates that Akt differentially regulates RNA processing and splicing factors to drive T cell differentiation. Interestingly, heterogeneous nuclear ribonucleoprotein (hnRNP) L or hnRNP A1 are Akt substrates during Treg induction and have known roles in regulating the stability and splicing of key mRNAs that code for proteins in the canonical TCR signaling pathway, including CD3ζ and CD45. Functionally, inhibition of Akt enzymatic activity results in the dysregulation of splicing during T cell differentiation, and knockdown of hnRNP L or hnRNP A1 results in the lower induction of Treg cells. Together, this work suggests that a switch in substrate specificity coupled to the phosphorylation status of Akt may lead to alternative cell fates and demonstrates that proteins involved with alternative splicing are important factors in T cell fate decisions.
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Affiliation(s)
- William F Hawse
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261; and
| | - William C Boggess
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
| | - Penelope A Morel
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261; and
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26
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Liao P, Wang W, Li Y, Wang R, Jin J, Pang W, Chen Y, Shen M, Wang X, Jiang D, Pang J, Liu M, Lin X, Feng XH, Wang P, Ge X. Palmitoylated SCP1 is targeted to the plasma membrane and negatively regulates angiogenesis. eLife 2017; 6:e22058. [PMID: 28440748 PMCID: PMC5404917 DOI: 10.7554/elife.22058] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Accepted: 03/25/2017] [Indexed: 12/12/2022] Open
Abstract
SCP1 as a nuclear transcriptional regulator acts globally to silence neuronal genes and to affect the dephosphorylation of RNA Pol ll. However, we report the first finding and description of SCP1 as a plasma membrane-localized protein in various cancer cells using EGFP- or other epitope-fused SCP1. Membrane-located SCP1 dephosphorylates AKT at serine 473, leading to the abolishment of serine 473 phosphorylation that results in suppressed angiogenesis and a decreased risk of tumorigenesis. Consistently, we observed increased AKT phosphorylation and angiogenesis followed by enhanced tumorigenesis in Ctdsp1 (which encodes SCP1) gene - knockout mice. Importantly, we discovered that the membrane localization of SCP1 is crucial for impeding angiogenesis and tumor growth, and this localization depends on palmitoylation of a conserved cysteine motif within its NH2 terminus. Thus, our study discovers a novel mechanism underlying SCP1 shuttling between the plasma membrane and nucleus, which constitutes a unique pathway in transducing AKT signaling that is closely linked to angiogenesis and tumorigenesis.
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Affiliation(s)
- Peng Liao
- Department of Central Laboratory, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Weichao Wang
- Department of Central Laboratory, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Yu Li
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Rui Wang
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Jiali Jin
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Weijuan Pang
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Yunfei Chen
- Department of Central Laboratory, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Mingyue Shen
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Xinbo Wang
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Dongyang Jiang
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Jinjiang Pang
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Mingyao Liu
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Xia Lin
- Department of Surgery, Baylor College of Medicine, Houston, United States
| | - Xin-Hua Feng
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Zhejiang, China
| | - Ping Wang
- Department of Central Laboratory, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
- School of Life Science and Technology, Tongji University, Shanghai, China
| | - Xin Ge
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
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27
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Lipina C, Vaanholt LM, Davidova A, Mitchell SE, Storey-Gordon E, Hambly C, Irving AJ, Speakman JR, Hundal HS. CB1 receptor blockade counters age-induced insulin resistance and metabolic dysfunction. Aging Cell 2016; 15:325-35. [PMID: 26757949 PMCID: PMC4783351 DOI: 10.1111/acel.12438] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2015] [Indexed: 12/11/2022] Open
Abstract
The endocannabinoid system can modulate energy homeostasis by regulating feeding behaviour as well as peripheral energy storage and utilization. Importantly, many of its metabolic actions are mediated through the cannabinoid type 1 receptor (CB1R), whose hyperactivation is associated with obesity and impaired metabolic function. Herein, we explored the effects of administering rimonabant, a selective CB1R inverse agonist, upon key metabolic parameters in young (4 month old) and aged (17 month old) adult male C57BL/6 mice. Daily treatment with rimonabant for 14 days transiently reduced food intake in young and aged mice; however, the anorectic response was more profound in aged animals, coinciding with a substantive loss in body fat mass. Notably, reduced insulin sensitivity in aged skeletal muscle and liver concurred with increased CB1R mRNA abundance. Strikingly, rimonabant was shown to improve glucose tolerance and enhance skeletal muscle and liver insulin sensitivity in aged, but not young, adult mice. Moreover, rimonabant‐mediated insulin sensitization in aged adipose tissue coincided with amelioration of low‐grade inflammation and repressed lipogenic gene expression. Collectively, our findings indicate a key role for CB1R in aging‐related insulin resistance and metabolic dysfunction and highlight CB1R blockade as a potential strategy for combating metabolic disorders associated with aging.
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Affiliation(s)
- Christopher Lipina
- Division of Cell Signalling and Immunology; Sir James Black Centre; School of Life Sciences; University of Dundee; Dundee UK
| | - Lobke M. Vaanholt
- Institute of Biological and Environmental Sciences; University of Aberdeen; Aberdeen UK
| | - Anastasija Davidova
- Division of Cell Signalling and Immunology; Sir James Black Centre; School of Life Sciences; University of Dundee; Dundee UK
| | - Sharon E. Mitchell
- Institute of Biological and Environmental Sciences; University of Aberdeen; Aberdeen UK
| | - Emma Storey-Gordon
- Division of Cell Signalling and Immunology; Sir James Black Centre; School of Life Sciences; University of Dundee; Dundee UK
| | - Catherine Hambly
- Institute of Biological and Environmental Sciences; University of Aberdeen; Aberdeen UK
| | - Andrew J. Irving
- Division of Neuroscience; Medical Research Institute; Ninewells Hospital; University of Dundee; Dundee UK
| | - John R. Speakman
- Institute of Biological and Environmental Sciences; University of Aberdeen; Aberdeen UK
- Institute of Genetics and Developmental Biology; Chinese Academy of Sciences, Chaoyang; Beijing China
| | - Harinder S. Hundal
- Division of Cell Signalling and Immunology; Sir James Black Centre; School of Life Sciences; University of Dundee; Dundee UK
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28
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Wang J, Li Z, Liu B, Chen G, Shao N, Ying X, Wang Y. Systematic study of cis-antisense miRNAs in animal species reveals miR-3661 to target PPP2CA in human cells. RNA (NEW YORK, N.Y.) 2016; 22:87-95. [PMID: 26577378 PMCID: PMC4691837 DOI: 10.1261/rna.052894.115] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 10/03/2015] [Indexed: 05/13/2023]
Abstract
MicroRNAs (miRNAs) suppress targeting gene expression through blocking translation or triggering mRNA degradation and, in general, act in trans, through a partially complementary interaction with the 3' untranslated region (3' UTR) or coding regions of a target gene. Although it has been reported previously that some miRNAs suppress their target genes on the opposite strand with a fully complementary sequence (i.e., natural antisense miRNAs that act in cis), there is no report to systematically study such cis-antisense miRNAs in different animal species. Here we report that cis-antisense miRNAs do exist in different animal species: 48 in Caenorhabditis elegans, 17 in Drosophila, 36 in Mus musculus, and 52 in Homo sapiens using a systematical bioinformatics approach. We show that most of these cis-antisense miRNAs can efficiently reduce the expression levels of their target genes in human cells. We further investigate hsa-miR-3661, one of the predicted cis-antisense miRNAs, in detail and demonstrate that this miRNA directly targets the coding sequence of PPP2CA located on the opposite DNA strand and inhibits the PPP2CA expression. Taken together, these results indicate that cis-antisense miRNAs are conservative and functional in animal species including humans.
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Affiliation(s)
- Jian Wang
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322, USA
| | - Zongcheng Li
- Beijing Institute of Basic Medical Sciences, Beijing 100850, China
| | - Bailong Liu
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322, USA The First Norman Bethune Hospital of Jilin University, Changchun 130012, China
| | - Guangnan Chen
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322, USA
| | - Ningsheng Shao
- Beijing Institute of Basic Medical Sciences, Beijing 100850, China
| | - Xiaomin Ying
- Beijing Institute of Basic Medical Sciences, Beijing 100850, China
| | - Ya Wang
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322, USA
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29
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Rapid alteration of protein phosphorylation during postmortem: implication in the study of protein phosphorylation. Sci Rep 2015; 5:15709. [PMID: 26511732 PMCID: PMC4625177 DOI: 10.1038/srep15709] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/29/2015] [Indexed: 11/26/2022] Open
Abstract
Protein phosphorylation is an important post-translational modification of proteins. Postmortem tissues are widely being utilized in the biomedical studies, but the effects of postmortem on protein phosphorylation have not been received enough attention. In the present study, we found here that most proteins in mouse brain, heart, liver, and kidney were rapidly dephosphorylated to various degrees during 20 sec to 10 min postmortem. Phosphorylation of tau at Thr212 and glycogen synthase kinase 3β (GSK-3β) at Ser9 was reduced by 50% in the brain with 40 sec postmortem, a regular time for tissue processing. During postmortem, phosphorylation of cAMP-dependent protein kinase (PKA) and AMP activated kinase (AMPK) was increased in the brain, but not in other organs. Perfusion of the brain with cold or room temperature phosphate-buffered saline (PBS) also caused significant alteration of protein phosphorylation. Cooling down and maintaining mouse brains in the ice-cold buffer prevented the alteration effectively. This study suggests that phosphorylation of proteins is rapidly changed during postmortem. Thus, immediate processing of tissues followed by cooling down in ice-cold buffer is vitally important and perfusion has to be avoided when protein phosphorylation is to be studied.
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30
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Akt kinase C-terminal modifications control activation loop dephosphorylation and enhance insulin response. Biochem J 2015. [PMID: 26201515 DOI: 10.1042/bj20150325] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The Akt protein kinase, also known as protein kinase B, plays key roles in insulin receptor signalling and regulates cell growth, survival and metabolism. Recently, we described a mechanism to enhance Akt phosphorylation that restricts access of cellular phosphatases to the Akt activation loop (Thr(308) in Akt1 or protein kinase B isoform alpha) in an ATP-dependent manner. In the present paper, we describe a distinct mechanism to control Thr(308) dephosphorylation and thus Akt deactivation that depends on intramolecular interactions of Akt C-terminal sequences with its kinase domain. Modifications of amino acids surrounding the Akt1 C-terminal mTORC2 (mammalian target of rapamycin complex 2) phosphorylation site (Ser(473)) increased phosphatase resistance of the phosphorylated activation loop (pThr(308)) and amplified Akt phosphorylation. Furthermore, the phosphatase-resistant Akt was refractory to ceramide-dependent dephosphorylation and amplified insulin-dependent Thr(308) phosphorylation in a regulated fashion. Collectively, these results suggest that the Akt C-terminal hydrophobic groove is a target for the development of agents that enhance Akt phosphorylation by insulin.
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31
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Differential thiol oxidation of the signaling proteins Akt, PTEN or PP2A determines whether Akt phosphorylation is enhanced or inhibited by oxidative stress in C2C12 myotubes derived from skeletal muscle. Int J Biochem Cell Biol 2015; 62:72-9. [DOI: 10.1016/j.biocel.2015.02.015] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/17/2015] [Accepted: 02/20/2015] [Indexed: 11/17/2022]
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32
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Castro-Alvarez JF, Uribe-Arias A, Cardona-Gómez GP. Cyclin-Dependent kinase 5 targeting prevents β-Amyloid aggregation involving glycogen synthase kinase 3β and phosphatases. J Neurosci Res 2015; 93:1258-66. [PMID: 25711385 DOI: 10.1002/jnr.23576] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 01/20/2015] [Accepted: 01/22/2015] [Indexed: 01/24/2023]
Abstract
Inappropriate activation of cyclin-dependent kinase 5 (CDK5) resulting from proteolytic release of the activator fragment p25 from the membrane contributes to the formation of neurofibrillary tangles, β-amyloid (βA) aggregation, and chronic neurodegeneration. At 18 months of age, 3× Tg-AD mice were sacrificed after either 3 weeks (short term) or 1 year (long term) of CDK5 knockdown. In short-term-treated animals, CDK5 knockdown reversed βA aggregation in the hippocampi via inhibitory phosphorylation of glycogen synthase kinase 3β Ser9 and activation of phosphatase PP2A. In long-term-treated animals, CDK5 knockdown induced a persistent reduction in CDK5 and prevented βA aggregation, but the effect on amyloid precursor protein processing was reduced, suggesting that yearly booster therapy would be required. These findings further validate CDK5 as a target for preventing or blocking amyloidosis in older transgenic mice.
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Affiliation(s)
- John Fredy Castro-Alvarez
- Cellular and Molecular Neurobiology Area, Neuroscience Group of Antioquia, Faculty of Medicine, SIU, University of Antioquia, Medellín, Colombia
| | - Alejandro Uribe-Arias
- Cellular and Molecular Neurobiology Area, Neuroscience Group of Antioquia, Faculty of Medicine, SIU, University of Antioquia, Medellín, Colombia
| | - Gloria Patricia Cardona-Gómez
- Cellular and Molecular Neurobiology Area, Neuroscience Group of Antioquia, Faculty of Medicine, SIU, University of Antioquia, Medellín, Colombia
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33
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Kurek K, Mikłosz A, Łukaszuk B, Chabowski A, Górski J, Żendzian-Piotrowska M. Inhibition of Ceramide De Novo Synthesis Ameliorates Diet Induced Skeletal Muscles Insulin Resistance. J Diabetes Res 2015; 2015:154762. [PMID: 26380311 PMCID: PMC4562089 DOI: 10.1155/2015/154762] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 03/18/2015] [Accepted: 03/25/2015] [Indexed: 12/22/2022] Open
Abstract
Nowadays wrong nutritional habits and lack of physical activity give a rich soil for the development of insulin resistance and obesity. Many researches indicate lipids, especially the one from the sphingolipids class, as the group of molecules heavily implicated in the progress of insulin resistance in skeletal muscle. Recently, scientists have focused their scrutiny on myriocin, a potent chemical compound that inhibits ceramide (i.e., central hub of sphingolipids signaling pathway) de novo synthesis. In the present research we evaluated the effects of myriocin application on type 2 diabetes mellitus in three different types of skeletal muscles: (1) slow-oxidative (red gastrocnemius), (2) oxidative-glycolytic (soleus), and (3) glycolytic (white gastrocnemius). For these reasons the animals were randomly divided into four groups: "control" (C), "myriocin" (M), "high fat diet" (HFD), "high fat diet" (HFD), and "high fat diet + myriocin" (HFD + M). Our in vivo study demonstrated that ceramide synthesis inhibition reduces intramuscular ceramide, its precursor sphinganine, and its derivatives sphingosine and sphingosine-1-phosphate concentrations. Moreover, FFA and TG contents were also decreased after myriocin treatment. Thus, myriocin presents potential therapeutic perspectives with respect to the treatment of insulin resistance and its serious consequences in obese patients.
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Affiliation(s)
- Krzysztof Kurek
- Department of Physiology, Medical University of Bialystok, 2C Mickiewicza Street, 15-222 Białystok, Poland
- *Krzysztof Kurek:
| | - Agnieszka Mikłosz
- Department of Physiology, Medical University of Bialystok, 2C Mickiewicza Street, 15-222 Białystok, Poland
| | - Bartłomiej Łukaszuk
- Department of Physiology, Medical University of Bialystok, 2C Mickiewicza Street, 15-222 Białystok, Poland
| | - Adrian Chabowski
- Department of Physiology, Medical University of Bialystok, 2C Mickiewicza Street, 15-222 Białystok, Poland
| | - Jan Górski
- Department of Physiology, Medical University of Bialystok, 2C Mickiewicza Street, 15-222 Białystok, Poland
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34
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Castro-Alvarez JF, Uribe-Arias SA, Mejía-Raigosa D, Cardona-Gómez GP. Cyclin-dependent kinase 5, a node protein in diminished tauopathy: a systems biology approach. Front Aging Neurosci 2014; 6:232. [PMID: 25225483 PMCID: PMC4150361 DOI: 10.3389/fnagi.2014.00232] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 08/11/2014] [Indexed: 11/23/2022] Open
Abstract
Alzheimer's disease (AD) is the most common cause of dementia worldwide. One of the main pathological changes that occurs in AD is the intracellular accumulation of hyperphosphorylated Tau protein in neurons. Cyclin-dependent kinase 5 (CDK5) is one of the major kinases involved in Tau phosphorylation, directly phosphorylating various residues and simultaneously regulating various substrates such as kinases and phosphatases that influence Tau phosphorylation in a synergistic and antagonistic way. It remains unknown how the interaction between CDK5 and its substrates promotes Tau phosphorylation, and systemic approaches are needed that allow an analysis of all the proteins involved. In this review, the role of the CDK5 signaling pathway in Tau hyperphosphorylation is described, an in silico model of the CDK5 signaling pathway is presented. The relationship among these theoretical and computational models shows that the regulation of Tau phosphorylation by PP2A and glycogen synthase kinase 3β (GSK3β) is essential under basal conditions and also describes the leading role of CDK5 under excitotoxic conditions, where silencing of CDK5 can generate changes in these enzymes to reverse a pathological condition that simulates AD.
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Affiliation(s)
- John F Castro-Alvarez
- Neuroscience Group of Antioquia, Cellular and Molecular Neurobiology Area, Faculty of Medicine, University of Antioquia, Sede de Investigación Universitaria Medellin, Colombia
| | - S Alejandro Uribe-Arias
- Neuroscience Group of Antioquia, Cellular and Molecular Neurobiology Area, Faculty of Medicine, University of Antioquia, Sede de Investigación Universitaria Medellin, Colombia
| | - Daniel Mejía-Raigosa
- Group of Biophysics, Faculty of Exact and Natural Sciences, Institute of Physics, University of Antioquia Medellin, Colombia
| | - Gloria P Cardona-Gómez
- Neuroscience Group of Antioquia, Cellular and Molecular Neurobiology Area, Faculty of Medicine, University of Antioquia, Sede de Investigación Universitaria Medellin, Colombia
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35
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Ceramide inhibits insulin-stimulated Akt phosphorylation through activation of Rheb/mTORC1/S6K signaling in skeletal muscle. Cell Signal 2014; 26:1400-8. [PMID: 24650522 DOI: 10.1016/j.cellsig.2014.03.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 02/20/2014] [Accepted: 03/06/2014] [Indexed: 11/20/2022]
Abstract
Ceramide is a negative regulator of insulin activity. At the molecular level, it causes a decrease in insulin-stimulated Akt Ser473 phosphorylation in C2C12 myotubes. Interestingly, we found that the phosphorylation of S6K at Thr389 was increased under the same conditions. Utilizing both rapamycin to inhibit mTORC1 activity and shRNA to knock down Rheb, we demonstrated that the decrease in Akt Ser473 phosphorylation stimulated by insulin after C2-ceramide incubation can be prevented. The mechanism by which C2-ceramide impairs signaling would seem to involve a negative feedback of activated S6K via phosphorylation of insulin receptor substrate-1 at Ser636/639, since S6K inhibitor can block this phenomenon. Finally, rapamycin treatment was found not to affect C2-ceramide-induced PKCζ activation, suggesting that the pathway revealed in this study is parallel to the one involving PKCζ activation. We proposed a novel pathway/mechanism involving Rheb/mTORC1/S6K signaling to explain how C2-ceramide impairs insulin signaling via Akt phosphorylation. The existence of multiple pathways involved in insulin signaling impairment by C2-ceramide treatment implies that different strategies might be needed to ameliorate insulin resistance caused by C2-ceramide.
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36
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Inhibition of ceramide de novo synthesis with myriocin affects lipid metabolism in the liver of rats with streptozotocin-induced type 1 diabetes. BIOMED RESEARCH INTERNATIONAL 2014; 2014:980815. [PMID: 24701589 PMCID: PMC3950399 DOI: 10.1155/2014/980815] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 12/27/2013] [Accepted: 12/31/2013] [Indexed: 12/11/2022]
Abstract
Nowadays diabetes is one of the most common metabolic diseases. Sphingolipids, which are vitally important constituents of intracellular signal transduction pathways, may be among the most pathogenic lipid moieties intermingled in the origin and development of diabetes. It is now well established that inhibition of de novo ceramide synthesis with myriocin exerts positive effects on lipid metabolism and glucose homeostasis in type 2 diabetes mellitus animal models. However, its influence on type I diabetes still remains unknown. Therefore, the scope of this paper is to fulfill that particular gap in our knowledge.
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37
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Okadaic Acid, a Bioactive Fatty Acid from Halichondria okadai, Stimulates Lipolysis in Rat Adipocytes: The Pivotal Role of Perilipin Translocation. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:545739. [PMID: 24319476 PMCID: PMC3844197 DOI: 10.1155/2013/545739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 10/07/2013] [Indexed: 11/17/2022]
Abstract
Lipid metabolism in visceral fat cells is correlated with metabolic syndrome and cardiovascular diseases. Okadaic-acid, a 38-carbon fatty acid isolated from the black sponge Halichondria okadai, can stimulate lipolysis by promoting the phosphorylation of several proteins in adipocytes. However, the mechanism of okadaic acid-induced lipolysis and the effects of okadaic acid on lipid-droplet-associated proteins (perilipins and beta-actin) remain unclear. We isolated adipocytes from rat epididymal fat pads and treated them with isoproterenol and/or okadaic acid to estimate lipolysis by measuring glycerol release. Incubating adipocytes with okadaic acid stimulated time-dependent lipolysis. Lipid-droplet-associated perilipins and beta-actin were analyzed by immunoblotting and immunofluorescence, and the association of perilipin A and B was found to be decreased in response to isoproterenol or okadaic acid treatment. Moreover, okadaic-acid treatment could enhance isoproterenol-mediated lipolysis, whereas treatment of several inhibitors such as KT-5720 (PKA inhibitor), calphostin C (PKC inhibitor), or KT-5823 (PKG inhibitor) did not attenuate okadaic-acid-induced lipolysis. By contrast, vanadyl acetylacetonate (tyrosine phosphatase inhibitor) blocked okadaic-acid-dependent lipolysis. These results suggest that okadaic acid induces the phosphorylation and detachment of lipid-droplet-associated perilipin A and B from the lipid droplet surface and thereby leads to accelerated lipolysis.
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Sphingolipid metabolic pathway: an overview of major roles played in human diseases. J Lipids 2013; 2013:178910. [PMID: 23984075 PMCID: PMC3747619 DOI: 10.1155/2013/178910] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/03/2013] [Indexed: 12/14/2022] Open
Abstract
Sphingolipids, a family of membrane lipids, are bioactive molecules that participate in diverse functions controlling fundamental cellular processes such as cell division, differentiation, and cell death. Given that most of these cellular processes form the basis for several pathologies, it is not surprising that sphingolipids are key players in several pathological processes. This review discusses the role of the sphingolipid metabolic pathway in diabetes, Alzheimer's disease, and hepatocellular carcinoma, with a special emphasis on the changes in gene expression pattern in these disease conditions. For convenience, the sphingolipid metabolic pathway is divided into hypothetical compartments (modules) with each compartment representing a physiological process and changes in gene expression pattern are mapped to each of these modules. It appears that alterations in the gene expression pattern in these disease conditions are biased to manipulate the system in order to result in a particular disease.
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Vadlakonda L, Dash A, Pasupuleti M, Anil Kumar K, Reddanna P. The Paradox of Akt-mTOR Interactions. Front Oncol 2013; 3:165. [PMID: 23802099 PMCID: PMC3687210 DOI: 10.3389/fonc.2013.00165] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Accepted: 06/07/2013] [Indexed: 12/20/2022] Open
Abstract
The serine threonine protein kinase, Akt, is at the central hub of signaling pathways that regulates cell growth, differentiation, and survival. The reciprocal relation that exists between the two activating phosphorylation sites of Akt, T308 and S473, and the two mTOR complexes, C1 and C2, forms the central controlling hub that regulates these cellular functions. In our previous review “PI3Kinase (PI3K)-AKT-mTOR and Wnt signaling pathways in cell cycle” we discussed the reciprocal relation between mTORC1 and C2 complexes in regulating cell metabolism and cell cycle progression in cancer cells. We present in this article, a hypothesis that activation of Akt-T308 phosphorylation in the presence of high ATP:AMP ratio promotes the stability of its phosphorylations and activates mTORC1 and the energy consuming biosynthetic processes. Depletion of energy leads to inactivation of mTORC1, activation of AMPK, FoxO, and promotes constitution of mTORC2 that leads to phosphorylation of Akt S473. Akt can also be activated independent of PI3K; this appears to have an advantage under situations like dietary restrictions, where insulin/insulin growth factor signaling could be a casualty.
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Boon J, Hoy AJ, Stark R, Brown RD, Meex RC, Henstridge DC, Schenk S, Meikle PJ, Horowitz JF, Kingwell BA, Bruce CR, Watt MJ. Ceramides contained in LDL are elevated in type 2 diabetes and promote inflammation and skeletal muscle insulin resistance. Diabetes 2013; 62:401-10. [PMID: 23139352 PMCID: PMC3554351 DOI: 10.2337/db12-0686] [Citation(s) in RCA: 226] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Dysregulated lipid metabolism and inflammation are linked to the development of insulin resistance in obesity, and the intracellular accumulation of the sphingolipid ceramide has been implicated in these processes. Here, we explored the role of circulating ceramide on the pathogenesis of insulin resistance. Ceramide transported in LDL is elevated in the plasma of obese patients with type 2 diabetes and correlated with insulin resistance but not with the degree of obesity. Treating cultured myotubes with LDL containing ceramide promoted ceramide accrual in cells and was accompanied by reduced insulin-stimulated glucose uptake, Akt phosphorylation, and GLUT4 translocation compared with LDL deficient in ceramide. LDL-ceramide induced a proinflammatory response in cultured macrophages via toll-like receptor-dependent and -independent mechanisms. Finally, infusing LDL-ceramide into lean mice reduced insulin-stimulated glucose uptake, and this was due to impaired insulin action specifically in skeletal muscle. These newly identified roles of LDL-ceramide suggest that strategies aimed at reducing hepatic ceramide production or reducing ceramide packaging into lipoproteins may improve skeletal muscle insulin action.
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MESH Headings
- Animals
- Cells, Cultured
- Ceramides/blood
- Ceramides/pharmacology
- Diabetes Mellitus, Type 2/blood
- Diabetes Mellitus, Type 2/metabolism
- Female
- Glucose/metabolism
- Glucose Transporter Type 4/metabolism
- Humans
- Inflammation/blood
- Inflammation/metabolism
- Insulin/metabolism
- Insulin Resistance/physiology
- Lipoproteins, LDL/blood
- Lipoproteins, LDL/pharmacology
- Macrophages/drug effects
- Macrophages/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Obesity/blood
- Obesity/metabolism
- Phosphorylation
- Proto-Oncogene Proteins c-akt/metabolism
- Toll-Like Receptors/metabolism
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Affiliation(s)
- James Boon
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Andrew J. Hoy
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Romana Stark
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Russell D. Brown
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Ruth C. Meex
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | | | - Simon Schenk
- Department of Orthopaedic Surgery, University of California, San Diego, California
| | - Peter J. Meikle
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | | | | | - Clinton R. Bruce
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Matthew J. Watt
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
- Corresponding author: Matthew J. Watt,
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Kaur M, Cole MD. MYC acts via the PTEN tumor suppressor to elicit autoregulation and genome-wide gene repression by activation of the Ezh2 methyltransferase. Cancer Res 2012; 73:695-705. [PMID: 23135913 DOI: 10.1158/0008-5472.can-12-2522] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The control of normal cell growth is a balance between stimulatory and inhibitory signals. MYC is a pleiotropic transcription factor that both activates and represses a broad range of target genes and is indispensable for cell growth. Whereas much is known about gene activation by MYC, there is no established mechanism for the majority of MYC-repressed genes. We report that MYC transcriptionally activates the PTEN tumor suppressor in normal cells to inactivate the phosphoinositide 3-kinase (PI3K) pathway, thus suppressing AKT activation. Suppression of AKT enhances the activity of the EZH2 histone methyltransferase, a subunit of the epigenetic repressor Polycomb Repressive Complex 2 (PRC2), while simultaneously stabilizing the protein. MYC-mediated enhancement in EZH2 protein level and activity results in local and genome-wide elevation in the repressive H3K27me3 histone modification, leading to widespread gene repression including feedback autoregulation of the MYC gene itself. Depletion of either PTEN or EZH2 and inhibition of the PI3K/AKT pathway leads to gene derepression. Importantly, expression of a phospho-defective EZH2 mutant is sufficient to recapitulate nearly half of all MYC-mediated gene repression. We present a novel epigenetic model for MYC-mediated gene repression and propose that PTEN and MYC exist in homeostatic balance to control normal growth, which is disrupted in cancer cells.
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Affiliation(s)
- Mandeep Kaur
- Department of Pharmacology, Dartmouth Medical School, Norris Cotton Cancer Center, Lebanon, New Hampshire 03756, USA
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Wang D, Lao WF, Kuang YY, Geng SM, Mo LJ, He C. A novel variant of the RON receptor tyrosine kinase derived from colorectal carcinoma cells which lacks tyrosine phosphorylation but induces cell migration. Exp Cell Res 2012; 318:2548-58. [PMID: 22975341 DOI: 10.1016/j.yexcr.2012.08.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 08/23/2012] [Accepted: 08/28/2012] [Indexed: 10/27/2022]
Abstract
Generation of splice variants in the RON receptor tyrosine kinase facilitates the invasive phenotype of colorectal cancers. Here, we report a new splice variant of RON in the human colorectal cancer cell line HCT116. This variant is encoded by a transcript differing from the full-length RON mRNA by an in-frame deletion of 106 amino acids in the extracellular domain of RON β-chain. The deleted transcript originates by an alternative deletion of exon 2 and exon 3. The molecular weight of this variant is 160 kDa. Thus, we named this variant RONΔ160(E2E3). This variant is a single-chain protein and expressed in the intracellular compartment. We found that RONΔ160(E2E3) had no tyrosine phosphorylation ability, but it has constitutively activated Akt activity in transfected HEK293 epithelial cells. The expression of this variant in HEK293 cells resulted in an increased migratory activity in vitro mediated through the PI-3K/Akt pathway. Our data describes a new splice variant of RON and suggests a novel role for the RON receptor in the progression of metastasis in colorectal cancer.
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Affiliation(s)
- Da Wang
- Department of Colorectal Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine/SRRSH, 3 East Qingchun Road, Hangzhou, Zhejiang 310016, People's Republic of China
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Salles J, Tardif N, Landrier JF, Mothe-Satney I, Guillet C, Boue-Vaysse C, Combaret L, Giraudet C, Patrac V, Bertrand-Michel J, Denis P, Chardigny JM, Boirie Y, Walrand S. TNFα gene knockout differentially affects lipid deposition in liver and skeletal muscle of high-fat-diet mice. J Nutr Biochem 2012; 23:1685-93. [PMID: 22464148 DOI: 10.1016/j.jnutbio.2011.12.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 12/01/2011] [Accepted: 12/02/2011] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS Inflammation and ectopic lipid deposition contribute to obesity-related insulin resistance (IR). Studies have shown that deficiency of the proinflammatory cytokine tumor necrosis factor-α (TNFα) protects against the IR induced by a high-fat diet (HFD). We aimed to evaluate the relationship between HFD-related inflammation and lipid deposition in skeletal muscle and liver. EXPERIMENTAL DESIGN Wild-type (WT) and TNFα-deficient (TNFα-KO) mice were subjected to an HFD for 12 weeks. A glucose tolerance test was performed to evaluate IR. Inflammatory status was assessed by measuring plasma and tissue transcript levels of cytokines. Lipid intermediate concentrations were measured in plasma, muscle and liver. The expression of genes involved in fatty acid transport, synthesis and oxidation was analyzed in adipose tissue, muscle and liver. RESULTS HFD induced a higher body weight gain in TNFα-KO mice than in WT mice. The weight of epididymal and abdominal adipose tissues was twofold lower in WT mice than in TNFα-KO mice, whereas liver weight was significantly heavier in WT mice. IR, systemic and adipose tissue inflammation, and plasma nonesterified fatty acid levels were reduced in TNFα-KO mice fed an HFD. TNFα deficiency improved fatty acid metabolism and had a protective effect against lipid deposition, inflammation and fibrosis associated with HFD in liver but had no impact on these markers in muscle. CONCLUSIONS Our data suggest that in an HFD context, TNFα deficiency reduced hepatic lipid accumulation through two mechanisms: an increase in adipose tissue storage capacity and a decrease in fatty acid uptake and synthesis in the liver.
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Affiliation(s)
- Jérôme Salles
- INRA, UMR 1019, UNH, CRNH Auvergne, F-63000 Clermont-Ferrand, France
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Farooqui AA, Farooqui T, Panza F, Frisardi V. Metabolic syndrome as a risk factor for neurological disorders. Cell Mol Life Sci 2012; 69:741-62. [PMID: 21997383 PMCID: PMC11115054 DOI: 10.1007/s00018-011-0840-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 09/08/2011] [Accepted: 09/15/2011] [Indexed: 02/07/2023]
Abstract
The metabolic syndrome is a cluster of common pathologies: abdominal obesity linked to an excess of visceral fat, insulin resistance, dyslipidemia and hypertension. At the molecular level, metabolic syndrome is accompanied not only by dysregulation in the expression of adipokines (cytokines and chemokines), but also by alterations in levels of leptin, a peptide hormone released by white adipose tissue. These changes modulate immune response and inflammation that lead to alterations in the hypothalamic 'bodyweight/appetite/satiety set point,' resulting in the initiation and development of metabolic syndrome. Metabolic syndrome is a risk factor for neurological disorders such as stroke, depression and Alzheimer's disease. The molecular mechanism underlying the mirror relationship between metabolic syndrome and neurological disorders is not fully understood. However, it is becoming increasingly evident that all cellular and biochemical alterations observed in metabolic syndrome like impairment of endothelial cell function, abnormality in essential fatty acid metabolism and alterations in lipid mediators along with abnormal insulin/leptin signaling may represent a pathological bridge between metabolic syndrome and neurological disorders such as stroke, Alzheimer's disease and depression. The purpose of this review is not only to describe the involvement of brain in the pathogenesis of metabolic syndrome, but also to link the pathogenesis of metabolic syndrome with neurochemical changes in stroke, Alzheimer's disease and depression to a wider audience of neuroscientists with the hope that this discussion will initiate more studies on the relationship between metabolic syndrome and neurological disorders.
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Affiliation(s)
- Akhlaq A Farooqui
- Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, OH 43221, USA.
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Pitre A, Davis N, Paul M, Orr AW, Skalli O. Synemin promotes AKT-dependent glioblastoma cell proliferation by antagonizing PP2A. Mol Biol Cell 2012; 23:1243-53. [PMID: 22337773 PMCID: PMC3315805 DOI: 10.1091/mbc.e11-08-0685] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Synemin is an intermediate filament protein present in glioblastomas (GBMs) but not in normal brain. In GBM cells synemin interacts with and antagonizes PP2A, which is the phosphatase dephosphorylating Akt. This maintains the phosphorylation status of Akt sites that are substrates for PDPK1 and mTORc2, thereby fostering proliferation. The intermediate filament protein synemin is present in astrocyte progenitors and glioblastoma cells but not in mature astrocytes. Here we demonstrate a role for synemin in enhancing glioblastoma cell proliferation and clonogenic survival, as synemin RNA interference decreased both behaviors by inducing G1 arrest along with Rb hypophosphorylation and increased protein levels of the G1/S inhibitors p21Cip1 and p27Kip1. Akt involvement was demonstrated by decreased phosphorylation of its substrate, p21Cip1, and reduced Akt catalytic activity and phosphorylation at essential activation sites. Synemin silencing, however, did not affect the activities of PDPK1 and mTOR complex 2, which directly phosphorylate Akt activation sites, but instead enhanced the activity of the major regulator of Akt dephosphorylation, protein phosphatase type 2A (PP2A). This was accompanied by changes in PP2A subcellular distribution resulting in increased physical interactions between PP2A and Akt, as shown by proximity ligation assays (PLAs). PLAs and immunoprecipitation experiments further revealed that synemin and PP2A form a protein complex. In addition, treatment of synemin-silenced cells with the PP2A inhibitor cantharidic acid resulted in proliferation and pAkt and pRb levels similar to those of controls. Collectively these results indicate that synemin positively regulates glioblastoma cell proliferation by helping sequester PP2A away from Akt, thereby favoring Akt activation.
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Affiliation(s)
- Aaron Pitre
- Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
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46
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Shahaf G, Rotem-Dai N, Koifman G, Raveh-Amit H, Frost SA, Livneh E. PKCη is a negative regulator of AKT inhibiting the IGF-I induced proliferation. Exp Cell Res 2012; 318:789-99. [PMID: 22305966 DOI: 10.1016/j.yexcr.2012.01.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 01/16/2012] [Accepted: 01/17/2012] [Indexed: 10/14/2022]
Abstract
The PI3K-AKT pathway is frequently activated in human cancers, including breast cancer, and its activation appears to be critical for tumor maintenance. Some malignant cells are dependent on activated AKT for their survival; tumors exhibiting elevated AKT activity show sensitivity to its inhibition, providing an Achilles heel for their treatment. Here we show that the PKCη isoform is a negative regulator of the AKT signaling pathway. The IGF-I induced phosphorylation on Ser473 of AKT was inhibited by the PKCη-induced expression in MCF-7 breast adenocarcinoma cancer cells. This was further confirmed in shRNA PKCη-knocked-down MCF-7 cells, demonstrating elevated phosphorylation on AKT Ser473. While PKCη exhibited negative regulation on AKT phosphorylation it did not alter the IGF-I induced ERK phosphorylation. However, it enhanced ERK phosphorylation when stimulated by PDGF. Moreover, its effects on IGF-I/AKT and PDGF/ERK pathways were in correlation with cell proliferation. We further show that both PKCη and IGF-I confer protection against UV-induced apoptosis and cell death having additive effects. Although the protective effect of IGF-I involved activation of AKT, it was not affected by PKCη expression, suggesting that PKCη acts through a different route to increase cell survival. Hence, our studies show that PKCη provides negative control on AKT pathway leading to reduced cell proliferation, and further suggest that its presence/absence in breast cancer cells will affect cell death, which could be of therapeutic value.
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Affiliation(s)
- Galit Shahaf
- The Shraga Segal department of Microbiology and Immunology, Faculty of Health Science and the Cancer Research Center, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
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Switzer CH, Glynn SA, Ridnour LA, Cheng RYS, Vitek MP, Ambs S, Wink DA. Nitric oxide and protein phosphatase 2A provide novel therapeutic opportunities in ER-negative breast cancer. Trends Pharmacol Sci 2011; 32:644-51. [PMID: 21893353 PMCID: PMC3380363 DOI: 10.1016/j.tips.2011.07.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 06/24/2011] [Accepted: 07/06/2011] [Indexed: 12/16/2022]
Abstract
Basal-like breast cancer is an aggressive disease with limited therapeutic options because these tumors frequently express the 'triple-negative' phenotype. We have recently reported that inducible nitric oxide synthase (NOS2) is a strong predictor of survival in patients with estrogen receptor negative [ER(-)] breast cancer, and that NOS2 expression is correlated with a basal-like phenotype. Recent reports also describe the pro-tumor effects of NO in breast and many other types of cancer. NO promotes cancer progression by activating several oncogenic signaling pathways such as extracellular signal-regulated kinases (ERK)-1/2, phosphoinositide 3-kinases (PI3K)/Akt, and c-Myc. Protein phosphatase 2A (PP2A) is a tumor suppressor that negatively regulates the same cancer-related signaling pathways that are activated by NO. PP2A activity is suppressed in tumor cells, but potential pharmacological agents have recently been described to increase PP2A activity in ER(-) breast cancer cells. We examine here the various functions of NO and PP2A in breast cancer and propose a novel mechanism by which activation of PP2A antagonizes NO signaling that promotes ER(-) breast cancer.
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Affiliation(s)
- Christopher H Switzer
- Radiation Biology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Bakirtzi K, Hatziapostolou M, Karagiannides I, Polytarchou C, Jaeger S, Iliopoulos D, Pothoulakis C. Neurotensin signaling activates microRNAs-21 and -155 and Akt, promotes tumor growth in mice, and is increased in human colon tumors. Gastroenterology 2011; 141:1749-61.e1. [PMID: 21806946 PMCID: PMC4442678 DOI: 10.1053/j.gastro.2011.07.038] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Revised: 07/05/2011] [Accepted: 07/26/2011] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Neurotensin promotes inflammation and colon cancer via the neurotensin-1 receptor (NTR1). MicroRNAs (miR) regulate protein synthesis by degrading or preventing translation of mRNAs. We analyzed expression of 365 different microRNAs by human colonic epithelial cells (NCM460) after activation of NTR1. METHODS We performed microarray analysis of mRNA expression by neurotensin-stimulated NCM460 cells that overexpressed NTR1. Nuclear factor-κB (NF-κB) binding sites were identified and tumorigenesis was assessed using soft agar assays and xenograft analysis of severe combined immunodeficiency mice. Targets of neurotensin-regulated microRNAs were identified via bioinformatic, real-time polymerase chain reaction, and immunoblot analyses. We analyzed RNA samples from human normal colon and tumor samples. RESULTS Neurotensin stimulated differential expression of 38 microRNAs, including miR-21 and miR-155, which have been associated with tumor growth and contain NF-κB binding sites. Neurotensin expression increased colony formation by HCT-116 cells. Blocking miR-21 and/or miR-155 prevented colony formation (P < .001). In mice, intraperitoneal administration of neurotensin increased the growth rate of HCT-116 xenograft tumors; blocking miR-21 and/or miR-155 slowed this tumor growth. Neurotensin activated Akt in HCT-116 cells; this effect was inhibited by blocking miR-21 and/or miR-155 (P < .001). Neurotensin activated AKT through miR-155-mediated suppression of the phosphatase protein phosphatase 2A catalytic subunit alpha (PPP2CA). Levels of phosphatase and tensin homolog (PTEN) and suppressor of cytokine signaling 1 (SOCS1) mRNA, potential targets of miR-21 and miR-155, respectively, were down-regulated by these miRs. Levels of NTR1, miR-21, and miR-155 increased significantly in human colon tumor samples, compared with normal tissues, whereas PPP2CA, SOCS1, and PTEN mRNAs were reduced significantly. CONCLUSIONS NTR1 activation stimulates expression of miR-21 and miR-155 in colonocytes, via Akt and NF-κB, to down-regulate PTEN and SOCS1 and promote growth of tumors in mice. Levels of NTR1, miR-21, and miR-155 increase in human colon tumor samples and correlate with tumor stage.
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Affiliation(s)
- Kyriaki Bakirtzi
- Inflammatory Bowel Disease Center, Division of Digestive Diseases, Inflammatory Bowel Disease Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
| | - Maria Hatziapostolou
- Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Boston, MA 02115,Department of Pathology, Harvard Medical School, Boston, MA 02115
| | - Iordanes Karagiannides
- Inflammatory Bowel Disease Center, Division of Digestive Diseases, Inflammatory Bowel Disease Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
| | | | - Savina Jaeger
- Department of Developmental Molecular Pathways, Novartis Institute for Biomedical Research, Cambridge, MA 02139
| | - Dimitrios Iliopoulos
- Department of Cancer Immunology & AIDS, Dana-Farber Cancer Institute, Boston, MA 02115,Department of Pathology, Harvard Medical School, Boston, MA 02115
| | - Charalabos Pothoulakis
- Inflammatory Bowel Disease Center, Division of Digestive Diseases, Inflammatory Bowel Disease Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
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Resistance of Akt kinases to dephosphorylation through ATP-dependent conformational plasticity. Proc Natl Acad Sci U S A 2011; 108:E1120-7. [PMID: 22031698 DOI: 10.1073/pnas.1109879108] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Phosphorylation of a threonine residue (T308 in Akt1) in the activation loop of Akt kinases is a prerequisite for deregulated Akt activity frequently observed in neoplasia. Akt phosphorylation in vivo is balanced by the opposite activities of kinases and phosphatases. Here we describe that targeting Akt kinase to the cell membrane markedly reduced sensitivity of phosphorylated Akt to dephosphorylation by protein phosphatase 2A. This effect was amplified by occupancy of the ATP binding pocket by either ATP or ATP-competitive inhibitors. Mutational analysis revealed that R273 in Akt1 and the corresponding R274 in Akt2 are essential for shielding T308 in the activation loop against dephosphorylation. Thus, occupancy of the nucleotide binding pocket of Akt kinases enables intramolecular interactions that restrict phosphatase access and sustain Akt phosphorylation. This mechanism provides an explanation for the "paradoxical" Akt hyperphosphorylation induced by ATP-competitive inhibitor, A-443654. The lack of phosphatase resistance further contributes insight into the mechanism by which the human Akt2 R274H missense mutation may cause autosomal-dominant diabetes mellitus.
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50
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Beltran L, Chaussade C, Vanhaesebroeck B, Cutillas PR. Calpain interacts with class IA phosphoinositide 3-kinases regulating their stability and signaling activity. Proc Natl Acad Sci U S A 2011; 108:16217-22. [PMID: 21930956 PMCID: PMC3182684 DOI: 10.1073/pnas.1107692108] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Class IA phosphoinositide 3-kinases (PI3Ks) are signaling enzymes with key roles in the regulation of essential cellular functions and disease, including cancer. Accordingly, their activity is tightly controlled in cells to maintain homeostasis. The formation of multiprotein complexes is a ubiquitous mechanism to regulate enzyme activity but the contribution of protein-protein interactions to the regulation of PI3K signaling is not fully understood. We designed an affinity purification quantitative mass spectrometry strategy to identify proteins interacting dynamically with PI3K in response to pathway activation, with the view that such binding partners may have a functional role in pathway regulation. Our study reveals that calpain small subunit 1 interacts with PI3K and that the association between these proteins is lower in cells stimulated with serum compared to starved cells. Calpain and PI3K activity assays confirmed these results, thus demonstrating that active calpain heterodimers associate dynamically with PI3K. In addition, calpains were found to cleave PI3K proteins in vitro (resulting in a reduction of PI3K lipid kinase activity) and to regulate endogenous PI3K protein levels in vivo. Further investigations revealed that calpains have a role in the negative regulation of PI3K/Akt pathway activity (as measured by Akt and ribosomal S6 phosphorylation) and that their inhibition promotes cell survival during serum starvation. These results indicate that the interaction between calpain and PI3K is a novel mechanism for the regulation of class IA PI3K stability and activity.
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Affiliation(s)
| | - Claire Chaussade
- Cell Signaling Group, Centre for Cell Signaling, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, United Kingdom
| | - Bart Vanhaesebroeck
- Cell Signaling Group, Centre for Cell Signaling, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, United Kingdom
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