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Li XL, Tei R, Uematsu M, Baskin JM. Ultralow Background Membrane Editors for Spatiotemporal Control of Phosphatidic Acid Metabolism and Signaling. ACS CENTRAL SCIENCE 2024; 10:543-554. [PMID: 38559292 PMCID: PMC10979500 DOI: 10.1021/acscentsci.3c01105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 01/11/2024] [Accepted: 01/11/2024] [Indexed: 04/04/2024]
Abstract
Phosphatidic acid (PA) is a multifunctional lipid with important metabolic and signaling functions, and efforts to dissect its pleiotropy demand strategies for perturbing its levels with spatiotemporal precision. Previous membrane editing approaches for generating local PA pools used light-mediated induced proximity to recruit a PA-synthesizing enzyme, phospholipase D (PLD), from the cytosol to the target organelle membrane. Whereas these optogenetic PLDs exhibited high activity, their residual activity in the dark led to undesired chronic lipid production. Here, we report ultralow background membrane editors for PA wherein light directly controls PLD catalytic activity, as opposed to localization and access to substrates, exploiting a light-oxygen-voltage (LOV) domain-based conformational photoswitch inserted into the PLD sequence and enabling their stable and nonperturbative targeting to multiple organelle membranes. By coupling organelle-targeted LOVPLD activation to lipidomics analysis, we discovered different rates of metabolism for PA and its downstream products depending on the subcellular location of PA production. We also elucidated signaling roles for PA pools on different membranes in conferring local activation of AMP-activated protein kinase signaling. This work illustrates how membrane editors featuring acute, optogenetic conformational switches can provide new insights into organelle-selective lipid metabolic and signaling pathways.
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Affiliation(s)
- Xiang-Ling Li
- Weill
Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, United States
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United States
| | - Reika Tei
- Weill
Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, United States
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United States
| | - Masaaki Uematsu
- Weill
Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, United States
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United States
| | - Jeremy M. Baskin
- Weill
Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, United States
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United States
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2
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Silva E, Ferchaud‐Roucher V, Kramer A, Madi L, Pantham P, Chassen S, Jansson T, Powell TL. Oleic acid stimulation of amino acid uptake in primary human trophoblast cells is mediated by phosphatidic acid and mTOR signaling. FASEB Bioadv 2024; 6:1-11. [PMID: 38223199 PMCID: PMC10782470 DOI: 10.1096/fba.2023-00113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 10/19/2023] [Accepted: 10/30/2023] [Indexed: 01/16/2024] Open
Abstract
Normal fetal development is critically dependent on optimal nutrient supply by the placenta, and placental amino acid transport has been demonstrated to be positively associated with fetal growth. Mechanistic target of rapamycin (mTOR) is a positive regulator of placental amino acid transporters, such as System A. Oleic acid (OA) has been previously shown to have a stimulatory role on placental mTOR signaling and System A amino acid uptake in primary human trophoblast (PHT) cells. We investigated the mechanistic link between OA and System A activity in PHT. We found that inhibition of mTOR complex 1 or 2, using small interfering RNA to knock down raptor or rictor, prevented OA-stimulated System A amino acid transport indicating the interaction of OA with mTOR. Phosphatidic acid (PA) is a key intermediary for phospholipid biosynthesis and a known regulator of the mTOR pathway; however, phospholipid biosynthetic pathways have not been extensively studied in placenta. We identified placental isoforms of acyl transferase enzymes involved in de novo phospholipid synthesis. Silencing of 1-acylglycerol-3-phosphate-O-acyltransferase-4, an enzyme in this pathway, prevented OA mediated stimulation of mTOR and System A amino acid transport. These data indicate that OA stimulates mTOR and amino acid transport in PHT cells mediated through de novo synthesis of PA. We speculate that fatty acids in the maternal circulation, such as OA, regulate placental functions critical for fetal growth by interaction with mTOR and that late pregnancy hyperlipidemia may be critical for increasing nutrient transfer to the fetus.
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Affiliation(s)
- Elena Silva
- Department of Obstetrics & GynecologyUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
| | | | - Anita Kramer
- Department of Obstetrics & GynecologyUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
| | - Lana Madi
- Department of Obstetrics & GynecologyUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
| | - Priyadarshini Pantham
- Ob/Gyn & Reproductive SciencesUniversity of California, San DiegoLa JollaCaliforniaUSA
| | - Stephanie Chassen
- Department of Pediatrics, Section of NeonatologyUniversity of Colorado, Anschutz Medical CampusAuroraColoradoUSA
| | - Thomas Jansson
- Department of Obstetrics & GynecologyUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
| | - Theresa L. Powell
- Department of Obstetrics & GynecologyUniversity of Colorado Anschutz Medical CampusAuroraColoradoUSA
- Department of Pediatrics, Section of NeonatologyUniversity of Colorado, Anschutz Medical CampusAuroraColoradoUSA
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3
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Li XL, Tei R, Uematsu M, Baskin JM. Ultralow background membrane editors for spatiotemporal control of lipid metabolism and signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.31.555787. [PMID: 37693485 PMCID: PMC10491157 DOI: 10.1101/2023.08.31.555787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Phosphatidic acid (PA) is a multifunctional lipid with important metabolic and signaling functions, and efforts to dissect its pleiotropy demand strategies for perturbing its levels with spatiotemporal precision. Previous membrane editing approaches for generating local PA pools used light-mediated induced proximity to recruit a PA-synthesizing enzyme, phospholipase D (PLD), from the cytosol to the target organelle membrane. Whereas these optogenetic PLDs exhibited high activity, their residual activity in the dark led to undesired chronic lipid production. Here, we report ultralow background membrane editors for PA wherein light directly controls PLD catalytic activity, as opposed to localization and access to substrates, exploiting a LOV domain-based conformational photoswitch inserted into the PLD sequence and enabling their stable and non-perturbative targeting to multiple organelle membranes. By coupling organelle-targeted LOVPLD activation to lipidomics analysis, we discovered different rates of metabolism for PA and its downstream products depending on the subcellular location of PA production. We also elucidated signaling roles for PA pools on different membranes in conferring local activation of AMP-activated protein kinase signaling. This work illustrates how membrane editors featuring acute, optogenetic conformational switches can provide new insights into organelle-selective lipid metabolic and signaling pathways.
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Affiliation(s)
- Xiang-Ling Li
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Reika Tei
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Masaaki Uematsu
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Jeremy M. Baskin
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
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4
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Huang L, Wu H, Li H, Hou Y, Hu J, Huang L, Lu Y, Liu X. Hepatic glycerolipid metabolism is critical to the egg laying rate of Guangxi Ma chickens. Gene 2022; 830:146500. [PMID: 35472624 DOI: 10.1016/j.gene.2022.146500] [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: 01/27/2022] [Revised: 03/29/2022] [Accepted: 04/14/2022] [Indexed: 11/28/2022]
Abstract
Yolk formation in liver is an important process for egg production in hens. The correlations between egg laying rate decline and liver function changes in Guangxi Ma chickens remain unclear. In this study, a total of 21,750 genes and 76,288 transcripts were identified in the RNA expression profiles isolated from liver tissues of 5 groups of Guangxi Ma chickens divided according to the age and egg laying rate. Numerous differential genes (DEGs) were identified after pairwise comparison among samples, and time series analysis categorization (age-related factors) revealed that down-regulated DEGs with aging were predominantly involved in lipid transportation and metabolic processes in the low egg laying rate groups. Notably, functional enrichment analysis confirmed that DGAT2, LIPG, PNPLA2, LPL, CEL, LIPC, DGKD, AGPAT2, AGPAT1 and AGPAT3 were highlighted as hub genes in glycerolipid metabolism pathway, which may be an essential non-age related factors of egg laying rate by regulating the synthesis of triacylglycerol (TAG) in liver. Finally, we categorized DEGs in Guangxi Ma chickens with different egg laying rate caused by age-related factors and found that DEGs with different expression patterns performing different biological functions. The analysis of DEGs with lower egg laying rate caused by non-age related factors and showed that the transportation of TAG was suppressed. Furthermore, critical genes and pathways involved in the synthesis of TAG in livers were identified, which dynamically regulated the formation of yolk precursors. Our results expanded the knowledge of the molecular mechanisms of the yolk precursor synthesis in chicken livers. The results will be helpful to explore the factors that affect egg laying rate from the perspective of yolk synthesis and provide a theoretical basis for improving the egg production of Guangxi Ma chickens.
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Affiliation(s)
- Liangfeng Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Hanxiao Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Hu Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Yuanyuan Hou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Jianing Hu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Lin Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Yangqing Lu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Xingting Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, China.
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5
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Implication of Ceramide Kinase/C1P in Cancer Development and Progression. Cancers (Basel) 2022; 14:cancers14010227. [PMID: 35008391 PMCID: PMC8750078 DOI: 10.3390/cancers14010227] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/28/2021] [Accepted: 12/30/2021] [Indexed: 12/28/2022] Open
Abstract
Cancer cells rewire their metabolic programs to favor biological processes that promote cell survival, proliferation, and dissemination. Among this relevant reprogramming, sphingolipid metabolism provides metabolites that can favor or oppose these hallmarks of cancer. The sphingolipid ceramide 1-phosphate (C1P) and the enzyme responsible for its biosynthesis, ceramide kinase (CERK), are well established regulators of cell growth and survival in normal, as well as malignant cells through stress-regulated signaling pathways. This metabolite also promotes cell survival, which has been associated with the feedback regulation of other antitumoral sphingolipids or second messengers. C1P also regulates cancer cell invasion and migration of different types of cancer, including lung, breast, pancreas, prostate, or leukemia cells. More recently, CERK and C1P have been implicated in the control of inflammatory responses. The present review provides an updated view on the important role of CERK/C1P in the regulation of cancer cell growth, survival, and dissemination.
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6
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Tei R, Morstein J, Shemet A, Trauner D, Baskin JM. Optical Control of Phosphatidic Acid Signaling. ACS CENTRAL SCIENCE 2021; 7:1205-1215. [PMID: 34345670 PMCID: PMC8323247 DOI: 10.1021/acscentsci.1c00444] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Indexed: 05/31/2023]
Abstract
Phosphatidic acids (PAs) are glycerophospholipids that regulate key cell signaling pathways governing cell growth and proliferation, including the mTOR and Hippo pathways. Their acyl chains vary in tail length and degree of saturation, leading to marked differences in the signaling functions of different PA species. For example, in mTOR signaling, saturated forms of PA are inhibitory, whereas unsaturated forms are activating. To enable rapid control over PA signaling, we describe here the development of photoswitchable analogues of PA, termed AzoPA and dAzoPA, that contain azobenzene groups in one or both lipid tails, respectively. These photolipids enable optical control of their tail structure and can be reversibly switched between a straight trans form and a relatively bent cis form. We found that cis-dAzoPA selectively activates mTOR signaling, mimicking the bioactivity of unsaturated forms of PA. Further, in the context of Hippo signaling, whose growth-suppressing activity is blocked by PA, we found that the cis forms of both AzoPA and dAzoPA selectively inhibit this pathway. Collectively, these photoswitchable PA analogues enable optical control of mTOR and Hippo signaling, and we envision future applications of these probes to dissect the pleiotropic effects of physiological and pathological PA signaling.
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Affiliation(s)
- Reika Tei
- Department
of Chemistry and Chemical Biology and Weill Institute for Cell and
Molecular Biology, Cornell University, Ithaca, New York 14850, United States
| | - Johannes Morstein
- Department
of Chemistry, New York University, New York, New York 10003, United States
| | - Andrej Shemet
- Department
of Chemistry, New York University, New York, New York 10003, United States
| | - Dirk Trauner
- Department
of Chemistry, New York University, New York, New York 10003, United States
| | - Jeremy M. Baskin
- Department
of Chemistry and Chemical Biology and Weill Institute for Cell and
Molecular Biology, Cornell University, Ithaca, New York 14850, United States
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7
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Xiao D, Su X, Gao H, Li X, Qu Y. The Roles of Lpar1 in Central Nervous System Disorders and Diseases. Front Neurosci 2021; 15:710473. [PMID: 34385905 PMCID: PMC8353257 DOI: 10.3389/fnins.2021.710473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 07/09/2021] [Indexed: 12/16/2022] Open
Abstract
Lysophosphatidic acid receptor 1 (Lpar1), which is found in almost all human tissues but is most abundant in the brain, can couple to G protein-coupled receptors (GPCRs) and participate in regulating cell proliferation, migration, survival, and apoptosis. Endothelial differentiation gene-2 receptor (Edg2), the protein encoded by the Lpar1 gene, is present on various cell types in the central nervous system (CNS), such as neural stem cells (NSCs), oligodendrocytes, neurons, astrocytes, and microglia. Lpar1 deletion causes neurodevelopmental disorders and CNS diseases, such as brain cancer, neuropsychiatric disorders, demyelination diseases, and neuropathic pain. Here, we summarize the possible roles and mechanisms of Lpar1/Edg2 in CNS disorders and diseases and propose that Lpar1/Edg2 might be a potential therapeutic target for CNS disorders and diseases.
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Affiliation(s)
- Dongqiong Xiao
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Pediatrics, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Emergency, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Xiaojuan Su
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Pediatrics, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Hu Gao
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Emergency, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Xihong Li
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Emergency, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Yi Qu
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Pediatrics, Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, China
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8
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Phosphatidic Acid Stimulates Myoblast Proliferation through Interaction with LPA1 and LPA2 Receptors. Int J Mol Sci 2021; 22:ijms22031452. [PMID: 33535610 PMCID: PMC7867176 DOI: 10.3390/ijms22031452] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 01/19/2021] [Indexed: 12/31/2022] Open
Abstract
Phosphatidic acid (PA) is a bioactive phospholipid capable of regulating key biological functions, including neutrophil respiratory burst, chemotaxis, or cell growth and differentiation. However, the mechanisms whereby PA exerts these actions are not completely understood. In this work, we show that PA stimulates myoblast proliferation, as determined by measuring the incorporation of [3H]thymidine into DNA and by staining the cells with crystal violet. PA induced the rapid phosphorylation of Akt and ERK1/2, and pretreatment of the cells with specific small interferin RNA (siRNA) to silence the genes encoding these kinases, or with selective pharmacologic inhibitors, blocked PA-stimulated myoblast proliferation. The mitogenic effects of PA were abolished by the preincubation of the myoblasts with pertussis toxin, a Gi protein inhibitor, suggesting the implication of Gi protein-coupled receptors in this action. Although some of the effects of PA have been associated with its possible conversion to lysoPA (LPA), treatment of the myoblasts with PA for up to 60 min did not produce any significant amount of LPA in these cells. Of interest, pharmacological blockade of the LPA receptors 1 and 2, or specific siRNA to silence the genes encoding these receptors, abolished PA-stimulated myoblast proliferation. Moreover, PA was able to compete with LPA for binding to LPA receptors, suggesting that PA can act as a ligand of LPA receptors. It can be concluded that PA stimulates myoblast proliferation through interaction with LPA1 and LPA2 receptors and the subsequent activation of the PI3K/Akt and MEK/ERK1-2 pathways, independently of LPA formation.
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9
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Ahmed-Salim Y, Galazis N, Bracewell-Milnes T, Phelps DL, Jones BP, Chan M, Munoz-Gonzales MD, Matsuzono T, Smith JR, Yazbek J, Krell J, Ghaem-Maghami S, Saso S. The application of metabolomics in ovarian cancer management: a systematic review. Int J Gynecol Cancer 2020; 31:754-774. [PMID: 33106272 DOI: 10.1136/ijgc-2020-001862] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/24/2020] [Accepted: 09/28/2020] [Indexed: 12/15/2022] Open
Abstract
Metabolomics, the global analysis of metabolites in a biological specimen, could potentially provide a fast method of biomarker identification for ovarian cancer. This systematic review aims to examine findings from studies that apply metabolomics to the diagnosis, prognosis, treatment, and recurrence of ovarian cancer. A systematic search of English language publications was conducted on PubMed, Science Direct, and SciFinder. It was augmented by a snowball strategy, whereby further relevant studies are identified from reference lists of included studies. Studies in humans with ovarian cancer which focus on metabolomics of biofluids and tumor tissue were included. No restriction was placed on the time of publication. A separate review of targeted metabolomic studies was conducted for completion. Qualitative data were summarized in a comprehensive table. The studies were assessed for quality and risk of bias using the ROBINS-I tool. 32 global studies were included in the main systematic review. Most studies applied metabolomics to diagnosing ovarian cancer, within which the most frequently reported metabolite changes were a down-regulation of phospholipids and amino acids: histidine, citrulline, alanine, and methionine. Dysregulated phospholipid metabolism was also reported in the separately reviewed 18 targeted studies. Generally, combinations of more than one significant metabolite as a panel, in different studies, achieved a higher sensitivity and specificity for diagnosis than a single metabolite; for example, combinations of different phospholipids. Widespread metabolite differences were observed in studies examining prognosis, treatment, and recurrence, and limited conclusions could be drawn. Cellular processes of proliferation and invasion may be reflected in metabolic changes present in poor prognosis and recurrence. For example, lower levels of lysine, with increased cell invasion as an underlying mechanism, or glutamine dependency of rapidly proliferating cancer cells. In conclusion, this review highlights potential metabolites and biochemical pathways which may aid the clinical care of ovarian cancer if further validated.
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Affiliation(s)
| | - Nicolas Galazis
- Department of Obstetrics and Gynaecology, Northwick Park Hospital, Harrow, UK
| | | | - David L Phelps
- Department of Gynaecological Oncology, Hammersmith Hospital Campus, Du Cane Road, Imperial College Healthcare NHS Trust, London, UK
| | - Benjamin P Jones
- Division of Surgery and Cancer, Institute of Reproductive and Developmental Biology, Hammersmith Hospital Campus, Du Cane Road, Imperial College London, London, UK
| | - Maxine Chan
- South Kensington Campus, Imperial College London Department of Materials, London, UK
| | | | - Tomoko Matsuzono
- Queen Elizabeth Hospital, Department of Obstetrics and Gynaecology, Hong Kong, Hong Kong
| | - James Richard Smith
- West London Gynaecological Cancer Centre, Queen Charlotte's Hospital, Hammersmith Hospital Campus, Du Cane Road, Imperial College Healthcare NHS Trust, London, UK
| | - Joseph Yazbek
- West London Gynaecological Cancer Centre, Queen Charlotte's Hospital, Hammersmith Hospital Campus, Du Cane Road, Imperial College Healthcare NHS Trust, London, UK
| | - Jonathan Krell
- West London Gynaecological Cancer Centre, Queen Charlotte's Hospital, Hammersmith Hospital Campus, Du Cane Road, Imperial College Healthcare NHS Trust, London, UK
| | - Sadaf Ghaem-Maghami
- Department of Gynaecological Oncology, West London Gynaecological Cancer Centre, Queen Charlotte's Hospital, Hammersmith Hospital Campus, Imperial College London and NHS Trust, Du Cane Road, Imperial College London, London, UK
| | - Srdjan Saso
- Division of Surgery and Cancer, Institute of Reproductive and Developmental Biology, Hammersmith Hospital Campus, Du Cane Road, Imperial College London, London, UK
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10
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Beyond Lipid Signaling: Pleiotropic Effects of Diacylglycerol Kinases in Cellular Signaling. Int J Mol Sci 2020; 21:ijms21186861. [PMID: 32962151 PMCID: PMC7554708 DOI: 10.3390/ijms21186861] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/11/2020] [Accepted: 09/16/2020] [Indexed: 12/13/2022] Open
Abstract
The diacylglycerol kinase family, which can attenuate diacylglycerol signaling and activate phosphatidic acid signaling, regulates various signaling transductions in the mammalian cells. Studies on the regulation of diacylglycerol and phosphatidic acid levels by various enzymes, the identification and characterization of various diacylglycerol and phosphatidic acid-regulated proteins, and the overlap of different diacylglycerol and phosphatidic acid metabolic and signaling processes have revealed the complex and non-redundant roles of diacylglycerol kinases in regulating multiple biochemical and biological networks. In this review article, we summarized recent progress in the complex and non-redundant roles of diacylglycerol kinases, which is expected to aid in restoring dysregulated biochemical and biological networks in various pathological conditions at the bed side.
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11
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Wang Y, Zhang M, Wang Z, Guo W, Yang D. MYC-binding lncRNA EPIC1 promotes AKT-mTORC1 signaling and rapamycin resistance in breast and ovarian cancer. Mol Carcinog 2020; 59:1188-1198. [PMID: 32810332 DOI: 10.1002/mc.23248] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 07/28/2020] [Accepted: 07/30/2020] [Indexed: 12/27/2022]
Abstract
AKT-mTORC1 (mammalian target of rapamycin complex 1) signaling pathway plays a critical role in tumorigenesis and can be targeted by rapamycin. However, the underlying mechanism of how long noncoding RNA (lncRNAs) regulate the AKT-mTORC1 pathway remains unclear. EPIC1 (epigenetically-induced lncRNA 1) is a Myc-binding lncRNA, which has been previously demonstrated to be overexpressed in multiple cancer types. In a pathway analysis including 4962 cancer patients, we observed that lncRNA EPIC1 expression was positively correlated with the AKT-mTORC1 signaling pathway in more than 10 cancer types, including breast and ovarian cancers. RNA-seq analysis of breast and ovarian cancer cells demonstrated that EPIC1-knockdown led to the downregulation of genes in the AKT-mTORC1 signaling pathway. In MCF-7, OVCAR4, and A2780cis cell lines, EPIC1 knockdown and overexpression, respectively, inhibited and activated phosphorylated AKT and the downstream phosphorylation levels of 4EBP1 and S6K. Further knockdown of Myc abolished the EPIC1's regulation of AKT-mTORC1 signaling; suggested that the regulation of phosphorylation level of AKT, 4EBP1, and S6K by EPIC1 depended on the expression of Myc. Moreover, EPIC1 overexpressed MCF-7, A2780cis, and OVCAR4 cells treated with rapamycin showed a significant decreasing in rapamycin mediated inhibition of p-S6K and p-S6 comparing with the control group. In addition, Colony Formation assay and MTT assay indicated that EPIC1 overexpression led to rapamycin resistance in breast and ovarian cancer cell lines. Our results demonstrated the lncRNA EPIC1 expression activated the AKT-mTORC1 signaling pathway through Myc and led to rapamycin resistance in breast and ovarian cancer.
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Affiliation(s)
- Yifei Wang
- Department of Pharmaceutical Sciences, Center for Pharmacogenetics, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Min Zhang
- Department of Pharmaceutical Sciences, Center for Pharmacogenetics, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Zehua Wang
- Department of Pharmaceutical Sciences, Center for Pharmacogenetics, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Weiwei Guo
- Department of Pharmaceutical Sciences, Center for Pharmacogenetics, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Da Yang
- Department of Pharmaceutical Sciences, Center for Pharmacogenetics, University of Pittsburgh, Pittsburgh, Pennsylvania.,UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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12
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Weiss HR, Mellender SJ, Kiss GK, Chiricolo A, Liu X, Chi OZ. Lysophosphatidic Acid Reduces Microregional Oxygen Supply/Consumption Balance after Cerebral Ischemia-Reperfusion. J Vasc Res 2020; 57:178-184. [PMID: 32434183 DOI: 10.1159/000506011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 01/19/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Lysophosphatidic acid (LPA) is a small phospholipid-signaling molecule, which can alter responses to stress in the central nervous system. OBJECTIVE We hypothesized that exogenous LPA would increase the size of infarct and reduce microregional O2 supply/consumption balance after cerebral ischemia-reperfusion. METHODS This was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1 h and reperfusion for 2 h with or without LPA (1 mg/kg, at 30, 60, and 90 min after reperfusion). Regional cerebral blood flow was determined using a C14-iodoantipyrine autoradiographic technique. Regional small-vessel (20-60 µm in diameter) arterial and venous oxygen saturations were determined microspectrophotometrically. RESULTS There were no significant hemodynamic or arterial blood gas differences between groups. The control ischemic-reperfused cortex had a similar O2 consumption to the contralateral cortex. However, microregional O2 supply/consumption balance was significantly reduced in the ischemic-reperfused cortex with many areas of low O2 saturation (43 of 80 veins with O2 saturation below 50%). LPA did not significantly alter cerebral blood flow, but it did significantly increase O2 extraction and consumption of the ischemic-reperfused region. It also significantly increased the number of small veins with low O2 saturations in the reperfused region (76 of 80 veins with O2 saturation below 50%). This was associated with a significantly increased cortical infarct size after LPA administration (11.4 ± 0.5% control vs. 16.4 ± 0.6% LPA). CONCLUSION This suggests that LPA reduces cell survival and that it is associated with an increase in the number of small microregions with reduced local oxygen balance after cerebral ischemia-reperfusion.
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Affiliation(s)
- Harvey R Weiss
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA,
| | - Scott J Mellender
- Department of Anesthesiology and Perioperative Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - Geza K Kiss
- Department of Anesthesiology and Perioperative Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - Antonio Chiricolo
- Department of Anesthesiology and Perioperative Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - Xia Liu
- Department of Anesthesiology and Perioperative Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - Oak Z Chi
- Department of Anesthesiology and Perioperative Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
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13
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Gonzalez AM, Church DD, Townsend JR, Bagheri R. Emerging Nutritional Supplements for Strength and Hypertrophy: An Update of the Current Literature. Strength Cond J 2020. [DOI: 10.1519/ssc.0000000000000552] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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14
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Ovary removal modifies liver message RNA profiles in single Comb White Leghorn chickens. Poult Sci 2020; 99:1813-1821. [PMID: 32241461 PMCID: PMC7587799 DOI: 10.1016/j.psj.2019.12.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 11/29/2019] [Accepted: 12/02/2019] [Indexed: 12/12/2022] Open
Abstract
Ovaries produce sex hormones, and ovariectomized animals are often used as models for ovarian dysfunction. The liver is a vital organ involved in metabolism and immunity. In the present study, we conducted experiments to investigate the effects of ovariectomy on transcription and metabolic processes in the liver in chicken. Eight Single Comb White Leghorn (SCWL) female chickens were ovariectomized at 17 wk of age, and 8 intact SCWL females served as controls. At 100 wk of age, all chickens were euthanized. High-throughput transcriptome sequencing was performed on liver RNA obtained from ovariectomized and intact females. A total of 267 differentially expressed genes (DEG) were identified in our study. After analysis using DAVID functional annotation tool, one significant Kyoto Encyclopedia of Genes and Genomes pathway, the phosphatidylinositol signaling pathway, was clustered. Gene Ontology enrichment analysis yielded 46 significant Gene Ontology terms. Among terms describing biological processes, the glycerolipid metabolic and lipid localization processes were dominant. The anabolic genes, PEPCK and GK5, and the catabolic genes, VTG1; VTG2; PLD5; DGKQ; DGKE; and FABP3, were detected in ovariectomized chickens. Differentially expressed genes such as ENSGALG00000000162, IL-1Β, SVOPL, and CA12 implied that livers in ovariectomized chickens were subjected to strong inflammatory reactions, whereas defenses against endogenous materials were compromised. A comprehensive view of gene expression in the liver of ovariectomized chickens would advance our understanding of lipid metabolism, glycometabolism, and their relationships to pathologies induced by absence of the ovary. The identified DEG indicated that ovariectomy disturbed lipid metabolism in the liver and was accompanied by an increase in hepatic gluconeogenesis and reductions in phosphatidic acid synthesis and lipid carrier capacity.
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Noble AR, Hogg K, Suman R, Berney DM, Bourgoin S, Maitland NJ, Rumsby MG. Phospholipase D2 in prostate cancer: protein expression changes with Gleason score. Br J Cancer 2019; 121:1016-1026. [PMID: 31673104 PMCID: PMC6964697 DOI: 10.1038/s41416-019-0610-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 09/20/2019] [Accepted: 10/01/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Phospholipases D1 and D2 (PLD1/2) are implicated in tumorigenesis through their generation of the signalling lipid phosphatidic acid and its downstream effects. Inhibition of PLD1 blocks prostate cell growth and colony formation. Here a role for PLD2 in prostate cancer (PCa), the major cancer of men in the western world, is examined. METHODS PLD2 expression was analysed by immunohistochemistry and western blotting. The effects of PLD2 inhibition on PCa cell viability and cell motility were measured using MTS, colony forming and wound-healing assays. RESULTS PLD2 protein is expressed about equally in luminal and basal prostate epithelial cells. In cells from different Gleason-scored PCa tissue PLD2 protein expression is generally higher than in non-tumorigenic cells and increases in PCa tissue scored Gleason 6-8. PLD2 protein is detected in the cytosol and nucleus and had a punctate appearance. In BPH tissue stromal cells as well as basal and luminal cells express PLD2. PLD2 protein co-expresses with chromogranin A in castrate-resistant PCa tissue. PLD2 inhibition reduces PCa cell viability, colony forming ability and directional cell movement. CONCLUSIONS PLD2 expression correlates with increasing Gleason score to GS8. PLD2 inhibition has the potential to reduce PCa progression.
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Affiliation(s)
- Amanda R Noble
- Cancer Research Unit, Department of Biology, University of York, York, YO10 5DD, UK
| | - Karen Hogg
- Technology Facility, Department of Biology, University of York, York, YO10 5DD, UK
| | - Rakesh Suman
- Cancer Research Unit, Department of Biology, University of York, York, YO10 5DD, UK
| | - Daniel M Berney
- Department of Molecular Oncology, Barts Cancer Institute, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Sylvain Bourgoin
- Centre de Recherche du CHU de Québec, Axe des Maladies Infectieuses et Immunitaires, local T1-58, 2705 boulevard Laurier, Québec, G1V 4G2, QC, Canada
| | - Norman J Maitland
- Cancer Research Unit, Department of Biology, University of York, York, YO10 5DD, UK
| | - Martin G Rumsby
- Cancer Research Unit, Department of Biology, University of York, York, YO10 5DD, UK.
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16
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Smeuninx B, Nishimura Y, McKendry J, Limb M, Smith K, Atherton PJ, Breen L. The effect of acute oral phosphatidic acid ingestion on myofibrillar protein synthesis and intracellular signaling in older males. Clin Nutr 2019; 38:1423-1432. [PMID: 29970319 DOI: 10.1016/j.clnu.2018.06.963] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/30/2018] [Accepted: 06/10/2018] [Indexed: 01/02/2023]
Abstract
BACKGROUND Age-related muscle loss (sarcopenia) may be driven by a diminished myofibrillar protein synthesis (MyoPS) response to anabolic stimuli (i.e. exercise and nutrition). Oral phosphatidic acid (PA) ingestion has been reported to stimulate resting muscle protein synthesis in rodents, and enhance resistance training-induced muscle remodelling in young humans. PURPOSE This study examined the effects of acute oral PA ingestion on resting and exercise-induced MyoPS rates in older individuals. METHODS Sixteen older males performed a bout of unilateral leg resistance exercise followed by oral ingestion of 750 mg of soy-derived PA or a rice-flour placebo (PL) over 60 min post-exercise. A primed-continuous infusion of l-[ring-13C6]-phenylalanine with serial muscle biopsies was used to determine MyoPS at rest and between 0-150 and 150-300 min post-exercise. RESULTS Plasma [PA] concentrations were elevated above basal values from 180 to 300 min post-exercise in PA only (P = 0.02). Exercise increased MyoPS rates above basal values between 150 and 300 min post-exercise in PL (P = 0.001), but not PA (P = 0.83). Phosphorylation of p70S6K, rpS6, 4E-BP1 and Akt was elevated above basal levels in the exercised leg over 150-300 min post-exercise for PL only (P = 0.018, 0.007, 0.011 and 0.002, respectively), and were significantly greater than PA (P < 0.01 for all proteins). The effects of oral PA ingestion on proteolytic signaling markers were equivocal. CONCLUSIONS Acute oral phosphatidic acid ingestion appears to interfere with resistance exercise-induced intramuscular anabolic signaling and MyoPS in older males and, therefore, may not be a viable treatment to counteract sarcopenia. Clinicaltials.gov registration no: NCT03446924.
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Affiliation(s)
- Benoit Smeuninx
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, West Midlands B15 2TT, UK; MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, West Midlands B15 2TT, UK
| | - Yusuke Nishimura
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, West Midlands B15 2TT, UK
| | - James McKendry
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, West Midlands B15 2TT, UK
| | - Marie Limb
- Clinical, Metabolic and Molecular Physiology Group, University of Nottingham, Royal Derby Hospital, Nottingham DE22 3DT, UK
| | - Ken Smith
- MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, West Midlands B15 2TT, UK; Clinical, Metabolic and Molecular Physiology Group, University of Nottingham, Royal Derby Hospital, Nottingham DE22 3DT, UK
| | - Philip J Atherton
- MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, West Midlands B15 2TT, UK; Clinical, Metabolic and Molecular Physiology Group, University of Nottingham, Royal Derby Hospital, Nottingham DE22 3DT, UK
| | - Leigh Breen
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, West Midlands B15 2TT, UK; MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, West Midlands B15 2TT, UK.
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Abstract
Some amino acids (AA) act through several signalling pathways and mechanisms to mediate the control of gene expression at the translation level, and the regulation occurs, specifically, on the initiation and the signalling pathways for translation. The translation of mRNA to protein synthesis proceeds through the steps of initiation and elongation, and AA act as important feed-forward activators that are involved in many pathways, such as the sensing and the transportation of AA by cells, in these steps in many tissues of mammals. For the translation, phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) is a critical molecule that controls the translation initiation and its functions can be regulated by some AA. Another control point in the mRNA binding step in the translation initiation is at the regulation by mammalian target of rapamycin, which requires a change of phosphorylation status of ribosomal protein S6. In fact, the change of phosphorylation status of ribosomal protein S6 might be involved in global protein synthesis. The present review summarises recent work on the molecular mechanisms of the regulation of protein synthesis by AA and highlights new findings.
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18
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Tan FH, Bai Y, Saintigny P, Darido C. mTOR Signalling in Head and Neck Cancer: Heads Up. Cells 2019; 8:cells8040333. [PMID: 30970654 PMCID: PMC6523933 DOI: 10.3390/cells8040333] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 04/08/2019] [Accepted: 04/09/2019] [Indexed: 02/07/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) signalling pathway is a central regulator of metabolism in all cells. It senses intracellular and extracellular signals and nutrient levels, and coordinates the metabolic requirements for cell growth, survival, and proliferation. Genetic alterations that deregulate mTOR signalling lead to metabolic reprogramming, resulting in the development of several cancers including those of the head and neck. Gain-of-function mutations in EGFR, PIK3CA, and HRAS, or loss-of-function in p53 and PTEN are often associated with mTOR hyperactivation, whereas mutations identified from The Cancer Genome Atlas (TCGA) dataset that potentially lead to aberrant mTOR signalling are found in the EIF4G1, PLD1, RAC1, and SZT2 genes. In this review, we discuss how these mutant genes could affect mTOR signalling and highlight their impact on metabolic processes, as well as suggest potential targets for therapeutic intervention, primarily in head and neck cancer.
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Affiliation(s)
- Fiona H Tan
- Division of Cancer Research, Peter MacCallum Cancer Centre, Grattan Street, Melbourne, Victoria 3000, Australia.
| | - Yuchen Bai
- Division of Cancer Research, Peter MacCallum Cancer Centre, Grattan Street, Melbourne, Victoria 3000, Australia.
| | - Pierre Saintigny
- Univ Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Centre de recherche en cancérologie de Lyon, 69008 Lyon, France.
- Department of Medical Oncology, Centre Léon Bérard, 69008 Lyon, France.
| | - Charbel Darido
- Division of Cancer Research, Peter MacCallum Cancer Centre, Grattan Street, Melbourne, Victoria 3000, Australia.
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria 3052, Australia.
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19
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Olmez I, Love S, Xiao A, Manigat L, Randolph P, McKenna BD, Neal BP, Boroda S, Li M, Brenneman B, Abounader R, Floyd D, Lee J, Nakano I, Godlewski J, Bronisz A, Sulman EP, Mayo M, Gioeli D, Weber M, Harris TE, Purow B. Targeting the mesenchymal subtype in glioblastoma and other cancers via inhibition of diacylglycerol kinase alpha. Neuro Oncol 2019; 20:192-202. [PMID: 29048560 DOI: 10.1093/neuonc/nox119] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background The mesenchymal phenotype in glioblastoma (GBM) and other cancers drives aggressiveness and treatment resistance, leading to therapeutic failure and recurrence of disease. Currently, there is no successful treatment option available against the mesenchymal phenotype. Methods We classified patient-derived GBM stem cell lines into 3 subtypes: proneural, mesenchymal, and other/classical. Each subtype's response to the inhibition of diacylglycerol kinase alpha (DGKα) was compared both in vitro and in vivo. RhoA activation, liposome binding, immunoblot, and kinase assays were utilized to elucidate the novel link between DGKα and geranylgeranyltransferase I (GGTase I). Results Here we show that inhibition of DGKα with a small-molecule inhibitor, ritanserin, or RNA interference preferentially targets the mesenchymal subtype of GBM. We show that the mesenchymal phenotype creates the sensitivity to DGKα inhibition; shifting GBM cells from the proneural to the mesenchymal subtype increases ritanserin activity, with similar effects in epithelial-mesenchymal transition models of lung and pancreatic carcinoma. This enhanced sensitivity of mesenchymal cancer cells to ritanserin is through inhibition of GGTase I and downstream mediators previously associated with the mesenchymal cancer phenotype, including RhoA and nuclear factor-kappaB. DGKα inhibition is synergistic with both radiation and imatinib, a drug preferentially affecting proneural GBM. Conclusions Our findings demonstrate that a DGKα-GGTase I pathway can be targeted to combat the treatment-resistant mesenchymal cancer phenotype. Combining therapies with greater activity against each GBM subtype may represent a viable therapeutic option against GBM.
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Affiliation(s)
- Inan Olmez
- Department of Neurology, University of Virginia, Charlottesville, Virginia
| | - Shawn Love
- Department of Neurology, University of Virginia, Charlottesville, Virginia
| | - Aizhen Xiao
- Department of Neurology, University of Virginia, Charlottesville, Virginia
| | - Laryssa Manigat
- Department of Neurology, University of Virginia, Charlottesville, Virginia
| | - Peyton Randolph
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
| | - Brian D McKenna
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia
| | - Brian P Neal
- Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia
| | - Salome Boroda
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
| | - Ming Li
- Department of Neurology, University of Virginia, Charlottesville, Virginia
| | - Breanna Brenneman
- Department of Neurology, University of Virginia, Charlottesville, Virginia
| | - Roger Abounader
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia
| | - Desiree Floyd
- Department of Neurology, University of Virginia, Charlottesville, Virginia
| | - Jeongwu Lee
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - Ichiro Nakano
- Department of Neurosurgery, University of Alabama, Birmingham, Alabama
| | - Jakub Godlewski
- Department of Neurosurgery, Brigham and Women's Hospital, Boston, Massachusetts
| | - Agnieszka Bronisz
- Department of Neurosurgery, Brigham and Women's Hospital, Boston, Massachusetts
| | - Erik P Sulman
- Department of Radiation Oncology, MD Anderson Cancer Center, University of Texas, Houston, Texas
| | - Marty Mayo
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia
| | - Daniel Gioeli
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia
| | - Michael Weber
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia
| | - Thurl E Harris
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
| | - Benjamin Purow
- Department of Neurology, University of Virginia, Charlottesville, Virginia
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20
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Genc GE, Hipolito VEB, Botelho RJ, Gumuslu S. Lysophosphatidic acid represses autophagy in prostate carcinoma cells. Biochem Cell Biol 2018; 97:387-396. [PMID: 30403494 DOI: 10.1139/bcb-2018-0164] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Lysophosphatidic acid (LPA) is a small signaling phospholipid that mediates diverse functions including cell proliferation, migration, and survival by engaging LPA-agonized G-protein coupled receptors. Autophagy is a survival mechanism in response to nutrient depletion or organellar damage that encloses idle or damaged organelles within autophagosomes that are then delivered to lysosomes for degradation. However, the relationship between LPA and autophagy is largely unknown. The purpose of this study is to elucidate whether LPA affects autophagy through the ERK1/2 and (or) the Akt-mTOR signaling pathways. In this study, we investigated the effect of LPA on autophagy-regulating pathways in various prostate-derived cancer cells including PC3, LNCaP, and Du145 cells grown in complete medium and exposed to serum-free medium. Using Western blotting and ELISA, we determined that LPA stimulates the ERK and mTOR pathways in complete and serum-free medium. The mTOR pathway led to phosphorylation of S6K and ULK, which respectively stimulates protein synthesis and arrests autophagy. Consistent with this, LPA exposure suppressed autophagy as measured by LC3 maturation and formation of GFP-LC3 puncta. Altogether, these results suggest that LPA suffices to activate mTORC1 and suppress autophagy in prostate cancer cells.
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Affiliation(s)
- Gizem E Genc
- a Department of Medical Biochemistry, Faculty of Medicine, Akdeniz University, Antalya 07070, Turkey
| | - Victoria E B Hipolito
- b Department of Chemistry and Biology and the Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Roberto J Botelho
- b Department of Chemistry and Biology and the Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Saadet Gumuslu
- a Department of Medical Biochemistry, Faculty of Medicine, Akdeniz University, Antalya 07070, Turkey
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21
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Ribeiro MC, Peruchetti DB, Silva LS, Silva-Filho JL, Souza MC, Henriques MDG, Caruso-Neves C, Pinheiro AAS. LPS Induces mTORC1 and mTORC2 Activation During Monocyte Adhesion. Front Mol Biosci 2018; 5:67. [PMID: 30073169 PMCID: PMC6058081 DOI: 10.3389/fmolb.2018.00067] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 06/28/2018] [Indexed: 12/15/2022] Open
Abstract
Monocyte adhesion is a crucial step in transmigration and can be induced by lipopolysaccharide (LPS). Here, we studied the role of mammalian target of rapamycin (mTOR) complexes, mTORC1 and mTORC2, and PKC in this process. We used THP-1 cells, a human monocytic cell line, to investigate monocyte adhesion under static and flow conditions. We observed that 1.0 μg/mL LPS increased PI3K/mTORC2 pathway and PKC activity after 1 h of incubation. WYE-354 10−6 M (mTORC2/mTORC1 inhibitor) and 10−6 M wortmannin avoided monocyte adhesion in culture plates. In addition, WYE also blocked LPS-induced CD11a expression. Interestingly, rapamycin and WYE-354 blocked both LPS-induced monocyte adhesion in a cell monolayer and actin cytoskeleton rearrangement, confirming mTORC1 involvement in this process. Once activated, PKC activates mTORC1/S6K pathway in a similar effect observed to LPS. Activation of the mTORC1/S6K pathway was attenuated by 10−6 M U0126, an MEK/ERK inhibitor, and 10−6 M calphostin C, a PKC inhibitor, indicating that the MEK/ERK/TSC2 axis acts as a mediator. In agreement, 80 nM PMA (a PKC activator) mimicked the effect of LPS on the activation of the MEK/ERK/TSC2/mTORC1/S6K pathway, monocyte adhesion to ECV cells and actin cytoskeleton rearrangement. Our findings show that LPS induces activation of mTOR complexes. This signaling pathway led to integrin expression and cytoskeleton rearrangement resulting in monocyte adhesion. These results describe a new molecular mechanism involved in monocyte adhesion in immune-based diseases.
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Affiliation(s)
- Marcelle C Ribeiro
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Diogo B Peruchetti
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leandro S Silva
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - João L Silva-Filho
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Mariana C Souza
- Fundação Oswaldo Cruz, Instituto de Tecnologia em Fármacos, Rio de Janeiro, Brazil
| | | | - Celso Caruso-Neves
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Medicina Regenerativa, Rio de Janeiro, Brazil
| | - Ana Acacia S Pinheiro
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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22
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Lutkewitte AJ, Schweitzer GG, Kennon-McGill S, Clemens MM, James LP, Jaeschke H, Finck BN, McGill MR. Lipin deactivation after acetaminophen overdose causes phosphatidic acid accumulation in liver and plasma in mice and humans and enhances liver regeneration. Food Chem Toxicol 2018. [PMID: 29534981 DOI: 10.1016/j.fct.2018.03.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Andrew J Lutkewitte
- Div. of Geriatrics and Nutritional Sciences, Dept. of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
| | - George G Schweitzer
- Div. of Geriatrics and Nutritional Sciences, Dept. of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
| | - Stefanie Kennon-McGill
- Dept. of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
| | - Melissa M Clemens
- Interdisciplinary Biomedical Sciences Graduate Program, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Laura P James
- Dept. of Pediatrics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
| | - Hartmut Jaeschke
- Dept. of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA.
| | - Brian N Finck
- Div. of Geriatrics and Nutritional Sciences, Dept. of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
| | - Mitchell R McGill
- Dept. of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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23
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Poli G, Cantini G, Armignacco R, Fucci R, Santi R, Canu L, Nesi G, Mannelli M, Luconi M. Metformin as a new anti-cancer drug in adrenocortical carcinoma. Oncotarget 2018; 7:49636-49648. [PMID: 27391065 PMCID: PMC5226535 DOI: 10.18632/oncotarget.10421] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 06/09/2016] [Indexed: 12/30/2022] Open
Abstract
Adrenocortical carcinoma (ACC) is a rare heterogeneous malignancy with poor prognosis. Since radical surgery is the only available treatment, more specific and effective drugs are urgently required. The anti-diabetic drug metformin has been associated with a decreased cancer prevalence and mortality in several solid tumors, prompting its possible use for ACC treatment. This paper evaluates the in vitro and in vivo anti-cancer effects of metformin using the ACC cell model H295R. Metformin treatment significantly reduces cell viability and proliferation in a dose- and time-dependent manner and associates with a significant inhibition of ERK1/2 and mTOR phosphorylation/activation, as well as with stimulation of AMPK activity. Metformin also triggers the apoptotic pathway, shown by the decreased expression of Bcl-2 and HSP27, HSP60 and HSP70, and enhanced membrane exposure of annexin V, resulting in activation of caspase-3 apoptotic effector. Metformin interferes with the proliferative autocrine loop of IGF2/IGF-1R, which supports adrenal cancer growth. Finally, in the ACC xenograft mouse model, obtained by subcutaneous injection of H295R cells, metformin intraperitoneal administration inhibits tumor growth, confirmed by the significant reduction of Ki67%. Our data suggest that metformin inhibits H295R cell growth both in vitro and in vivo. Further preclinical studies are necessary to validate the potential anti-cancer effect of metformin in patients affected by ACC.
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Affiliation(s)
- Giada Poli
- Endocrinology Unit, Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Giulia Cantini
- Endocrinology Unit, Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Roberta Armignacco
- Endocrinology Unit, Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Rossella Fucci
- Endocrinology Unit, Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Raffaella Santi
- Division of Pathological Anatomy, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy
| | - Letizia Canu
- Endocrinology Unit, Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Gabriella Nesi
- Division of Pathological Anatomy, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy
| | - Massimo Mannelli
- Endocrinology Unit, Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Michaela Luconi
- Endocrinology Unit, Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
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24
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Ma Z, Liu X, Li F, Wang Y, Xu Y, Zhang M, Zhang X, Ying X, Zhang X. Perfluorooctanoic acid induces human Ishikawa endometrial cancer cell migration and invasion through activation of ERK/mTOR signaling. Oncotarget 2018; 7:66558-66568. [PMID: 27589685 PMCID: PMC5341820 DOI: 10.18632/oncotarget.11684] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Accepted: 08/25/2016] [Indexed: 12/26/2022] Open
Abstract
Perfluorooctanoic acid (PFOA) is a common environmental pollutant that has been associated with various diseases, including cancer. We explored the molecular mechanisms underlying PFOA-induced endometrial cancer cell invasion and migration. PFOA treatment enhanced migration and invasion by human Ishikawa endometrial cancer cells, which correlated with decreased E-cadherin expression, a marker of epithelial-mesenchymal transition. PFOA also induced activation of ERK1/2/mTOR signaling. Treatment with rapamycin, an mTOR inhibitor, antagonized the effects of PFOA and reversed the effects of PFOA activation in a xenograft mouse model of endometrial cancer. Consistent with these results, pre-treatment with rapamycin abolished PFOA-induced down-regulation of E-cadherin expression. These results indicate that PFOA is a carcinogen that promotes endometrial cancer cell migration and invasion through activation of ERK/mTOR signaling.
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Affiliation(s)
- Zhinan Ma
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.,Department of Obstetrics and Gynecology, Yangzhou Maternal and Child Health Hospital, Yangzhou University, Yangzhou, China.,State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Xiaoqiu Liu
- Key Laboratory of Pathogen Biology of Jiangsu Province, Nanjing Medical University, Nanjing, China.,Department of Microbiology, Nanjing Medical University, Nanjing, China
| | - Fujun Li
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Yixong Wang
- Department of Obstetrics and Gynecology, Yangzhou Maternal and Child Health Hospital, Yangzhou University, Yangzhou, China
| | - Yang Xu
- Department of Obstetrics and Gynecology, Yangzhou Maternal and Child Health Hospital, Yangzhou University, Yangzhou, China
| | - Mei Zhang
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Xiaoqian Zhang
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Xiaoyan Ying
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Xuesen Zhang
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
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A Phosphatidic Acid (PA) conveyor system of continuous intracellular transport from cell membrane to nucleus maintains EGF receptor homeostasis. Oncotarget 2018; 7:47002-47017. [PMID: 27256981 PMCID: PMC5216919 DOI: 10.18632/oncotarget.9685] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 05/14/2016] [Indexed: 12/11/2022] Open
Abstract
The intracellular concentration of the mitogen phosphatidic acid (PA) must be maintained at low levels until the need arises for cell proliferation. How temporal and spatial trafficking of PA affects its target proteins in the different cellular compartments is not fully understood. We report that in cancer cells, PA cycles back and forth from the cellular membrane to the nucleus, affecting the function of epidermal growth factor (EGF), in a process that involves PPARα/LXRα signaling. Upon binding to its ligand, EGF receptor (EGFR)-initiated activation of phospholipase D (PLD) causes a spike in intracellular PA production that forms vesicles transporting EGFR from early endosomes (EEA1 marker) and prolonged internalization in late endosomes and Golgi (RCAS marker). Cells incubated with fluorescent-labeled PA (NBD-PA) show PA in “diffuse” locations throughout the cytoplasm, punctae (small, <0.1 μm) vesicles) and large (>0.5 μm) vesicles that co-localize with EGFR. We also report that PPARα/LXRα form heterodimers that bind to new Responsive Elements (RE) in the EGFR promoter. Nuclear PA enhances EGFR expression, a role compatible with the mitogenic ability of the phospholipid. Newly made EGFR is packaged into PA recycling vesicles (Rab11 marker) and transported back to the cytoplasm and plasma membrane. However, a PLD+PA combination impedes binding of PPARα/LXRα to the EGFR promoter. Thus, if PA levels inside the nucleus reach a certain threshold (>100 nM) PA outcompetes the nuclear receptors and transcription is inhibited. This new signaling function of PLD-PA targeting EGFR trafficking and biphasically modulating its transcription, could explain cell proliferation initiation and its maintenance in cancer cells.
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26
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Wang T, Wang X, Zhou H, Jiang H, Mai K, He G. The Mitotic and Metabolic Effects of Phosphatidic Acid in the Primary Muscle Cells of Turbot ( Scophthalmus maximus). Front Endocrinol (Lausanne) 2018; 9:221. [PMID: 29780359 PMCID: PMC5946094 DOI: 10.3389/fendo.2018.00221] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 04/19/2018] [Indexed: 12/11/2022] Open
Abstract
Searching for nutraceuticals and understanding the underlying mechanism that promote fish growth is at high demand for aquaculture industry. In this study, the modulatory effects of soy phosphatidic acids (PA) on cell proliferation, nutrient sensing, and metabolic pathways were systematically examined in primary muscle cells of turbot (Scophthalmus maximus). PA was found to stimulate cell proliferation and promote G1/S phase transition through activation of target of rapamycin signaling pathway. The expression of myogenic regulatory factors, including myoD and follistatin, was upregulated, while that of myogenin and myostatin was downregulated by PA. Furthermore, PA increased intracellular free amino acid levels and enhanced protein synthesis, lipogenesis, and glycolysis, while suppressed amino acid degradation and lipolysis. PA also was found to increased cellular energy production through stimulated tricarboxylic acid cycle and oxidative phosphorylation. Our results identified PA as a potential nutraceutical that stimulates muscle cell proliferation and anabolism in fish.
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Affiliation(s)
- Tingting Wang
- Key Laboratory of Aquaculture Nutrition, Ministry of Agriculture, Ocean University of China, Qingdao, China
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
| | - Xuan Wang
- Key Laboratory of Aquaculture Nutrition, Ministry of Agriculture, Ocean University of China, Qingdao, China
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
| | - Huihui Zhou
- Key Laboratory of Aquaculture Nutrition, Ministry of Agriculture, Ocean University of China, Qingdao, China
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
| | - Haowen Jiang
- Key Laboratory of Aquaculture Nutrition, Ministry of Agriculture, Ocean University of China, Qingdao, China
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
| | - Kangsen Mai
- Key Laboratory of Aquaculture Nutrition, Ministry of Agriculture, Ocean University of China, Qingdao, China
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
| | - Gen He
- Key Laboratory of Aquaculture Nutrition, Ministry of Agriculture, Ocean University of China, Qingdao, China
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- *Correspondence: Gen He,
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27
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Goncharov NV, Nadeev AD, Jenkins RO, Avdonin PV. Markers and Biomarkers of Endothelium: When Something Is Rotten in the State. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:9759735. [PMID: 29333215 PMCID: PMC5733214 DOI: 10.1155/2017/9759735] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 09/05/2017] [Indexed: 12/14/2022]
Abstract
Endothelium is a community of endothelial cells (ECs), which line the blood and lymphatic vessels, thus forming an interface between the tissues and the blood or lympha. This strategic position of endothelium infers its indispensable functional role in controlling vasoregulation, haemostasis, and inflammation. The state of endothelium is simultaneously the cause and effect of many diseases, and this is coupled with modifications of endothelial phenotype represented by markers and with biochemical profile of blood represented by biomarkers. In this paper, we briefly review data on the functional role of endothelium, give definitions of endothelial markers and biomarkers, touch on the methodological approaches for revealing biomarkers, present an implicit role of endothelium in some toxicological mechanistic studies, and survey the role of reactive oxygen species (ROS) in modulation of endothelial status.
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Affiliation(s)
- Nikolay V. Goncharov
- Research Institute of Hygiene, Occupational Pathology and Human Ecology, Saint Petersburg, Russia
- Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, Saint Petersburg, Russia
| | - Alexander D. Nadeev
- Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, Saint Petersburg, Russia
- Institute of Cell Biophysics RAS, Pushchino, Russia
| | - Richard O. Jenkins
- School of Allied Health Sciences, De Montfort University, The Gateway, Leicester LE1 9BH, UK
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28
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Phospholipase D inhibitors reduce human prostate cancer cell proliferation and colony formation. Br J Cancer 2017; 118:189-199. [PMID: 29136407 PMCID: PMC5785744 DOI: 10.1038/bjc.2017.391] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/17/2017] [Accepted: 10/02/2017] [Indexed: 12/12/2022] Open
Abstract
Background: Phospholipases D1 and D2 (PLD1/2) hydrolyse cell membrane glycerophospholipids to generate phosphatidic acid, a signalling lipid, which regulates cell growth and cancer progression through effects on mTOR and PKB/Akt. PLD expression and/or activity is raised in breast, colorectal, gastric, kidney and thyroid carcinomas but its role in prostate cancer (PCa), the major cancer of men in the western world, is unclear. Methods: PLD1 protein expression in cultured PNT2C2, PNT1A, P4E6, LNCaP, PC3, PC3M, VCaP, 22RV1 cell lines and patient-derived PCa cells was analysed by western blotting. PLD1 protein localisation in normal, benign prostatic hyperplasia (BPH), and castrate-resistant prostate cancer (CRPC) tissue sections and in a PCa tissue microarray (TMA) was examined by immunohistochemistry. PLD activity in PCa tissue was assayed using an Amplex Red method. The effect of PLD inhibitors on PCa cell viability was measured using MTS and colony forming assays. Results: PLD1 protein expression was low in the luminal prostate cell lines (LNCaP, VCaP, 22RV1) compared with basal lines (PC3 and PC3M). PLD1 protein expression was elevated in BPH biopsy tissue relative to normal and PCa samples. In normal and BPH tissue, PLD1 was predominantly detected in basal cells as well in some stromal cells, rather than in luminal cells. In PCa tissue, luminal cells expressed PLD1. In a PCa TMA, the mean peroxidase intensity per DAB-stained Gleason 6 and 7 tissue section was significantly higher than in sections graded Gleason 9. In CRPC tissue, PLD1 was expressed prominently in the stromal compartment, in luminal cells in occasional glands and in an expanding population of cells that co-expressed chromogranin A and neurone-specific enolase. Levels of PLD activity in normal and PCa tissue samples were similar. A specific PLD1 inhibitor markedly reduced the survival of both prostate cell lines and patient-derived PCa cells compared with two dual PLD1/PLD2 inhibitors. Short-term exposure of PCa cells to the same specific PLD1 inhibitor significantly reduced colony formation. Conclusions: A new specific inhibitor of PLD1, which is well tolerated in mice, reduces PCa cell survival and thus has potential as a novel therapeutic agent to reduce prostate cancer progression. Increased PLD1 expression may contribute to the hyperplasia characteristic of BPH and in the progression of castrate-resistant PCa, where an expanding population of neuroendocrine-like cells express PLD1.
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29
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Posada IMD, Lectez B, Siddiqui FA, Oetken-Lindholm C, Sharma M, Abankwa D. Opposite feedback from mTORC1 to H-ras and K-ras4B downstream of SREBP1. Sci Rep 2017; 7:8944. [PMID: 28827765 PMCID: PMC5567141 DOI: 10.1038/s41598-017-09387-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 07/26/2017] [Indexed: 01/12/2023] Open
Abstract
As a major growth factor transducer, Ras is an upstream activator of mTORC1, which further integrates nutrient and energy inputs. To ensure a contextual coupling of cell division via Ras/MAPK-signalling and growth via mTORC1-signalling, feedback loops from one pathway back to the other are required. Here we describe a novel feedback from mTORC1, which oppositely affects oncogenic H-ras- and K-ras-signalling output, and as a consequence stemness properties of tumourigenic cells. Amino acid stimulation of mTORC1 increases the processed form of SREBP1, a major lipidome regulator. We show that modulation of the SREBP1 levels downstream of S6K1 has opposite effects on oncogenic H-ras and K-ras nanoscale membrane organisation, ensuing signalling output and promotion of mammospheres expressing these oncogenes. Our data suggest that modulation of phosphatidic acid, a major target of SREBP1 controlled lipid metabolism, is sufficient to affect H-ras and K-ras oppositely in the membrane. Thus mTORC1 activation increases H-ras-, but decreases K-ras-signalling output in cells transformed with the respective oncogene. Given the different impact of these two Ras isoforms on stemness, our results could have implications for stem cell biology and inhibition of cancer stem cells.
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Affiliation(s)
- Itziar M D Posada
- Turku Centre for Biotechnology, Åbo Akademi University, Tykistökatu 6B, 20520, Turku, Finland
| | - Benoit Lectez
- Turku Centre for Biotechnology, Åbo Akademi University, Tykistökatu 6B, 20520, Turku, Finland
| | - Farid A Siddiqui
- Turku Centre for Biotechnology, Åbo Akademi University, Tykistökatu 6B, 20520, Turku, Finland
| | | | - Mukund Sharma
- Turku Centre for Biotechnology, Åbo Akademi University, Tykistökatu 6B, 20520, Turku, Finland
| | - Daniel Abankwa
- Turku Centre for Biotechnology, Åbo Akademi University, Tykistökatu 6B, 20520, Turku, Finland.
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30
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Hino K, Horigome K, Nishio M, Komura S, Nagata S, Zhao C, Jin Y, Kawakami K, Yamada Y, Ohta A, Toguchida J, Ikeya M. Activin-A enhances mTOR signaling to promote aberrant chondrogenesis in fibrodysplasia ossificans progressiva. J Clin Invest 2017; 127:3339-3352. [PMID: 28758906 DOI: 10.1172/jci93521] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 06/13/2017] [Indexed: 12/27/2022] Open
Abstract
Fibrodysplasia ossificans progressiva (FOP) is a rare and intractable disease characterized by extraskeletal bone formation through endochondral ossification. Patients with FOP harbor point mutations in ACVR1, a type I receptor for BMPs. Although mutated ACVR1 (FOP-ACVR1) has been shown to render hyperactivity in BMP signaling, we and others have uncovered a mechanism by which FOP-ACVR1 mistransduces BMP signaling in response to Activin-A, a molecule that normally transduces TGF-β signaling. Although Activin-A evokes enhanced chondrogenesis in vitro and heterotopic ossification (HO) in vivo, the underlying mechanisms have yet to be revealed. To this end, we developed a high-throughput screening (HTS) system using FOP patient-derived induced pluripotent stem cells (FOP-iPSCs) to identify pivotal pathways in enhanced chondrogenesis that are initiated by Activin-A. In a screen of 6,809 small-molecule compounds, we identified mTOR signaling as a critical pathway for the aberrant chondrogenesis of mesenchymal stromal cells derived from FOP-iPSCs (FOP-iMSCs). Two different HO mouse models, an FOP model mouse expressing FOP-ACVR1 and an FOP-iPSC-based HO model mouse, revealed critical roles for mTOR signaling in vivo. Moreover, we identified ENPP2, an enzyme that generates lysophosphatidic acid, as a linker of FOP-ACVR1 and mTOR signaling in chondrogenesis. These results uncovered the crucial role of the Activin-A/FOP-ACVR1/ENPP2/mTOR axis in FOP pathogenesis.
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Affiliation(s)
- Kyosuke Hino
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan.,iPS Cell-Based Drug Discovery, Sumitomo Dainippon Pharma Co., Ltd., Osaka, Japan
| | - Kazuhiko Horigome
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan.,iPS Cell-Based Drug Discovery, Sumitomo Dainippon Pharma Co., Ltd., Osaka, Japan
| | - Megumi Nishio
- Department of Tissue Regeneration, Institute for Frontier Life and Medical Sciences, and
| | - Shingo Komura
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan.,Department of Orthopaedic Surgery, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Sanae Nagata
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Chengzhu Zhao
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Yonghui Jin
- Department of Tissue Regeneration, Institute for Frontier Life and Medical Sciences, and.,Institute for Advancement of Clinical and Translational Science (iACT), Kyoto University Hospital, Kyoto, Japan
| | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, Shizuoka, Japan.,Department of Genetics, Graduate University for Advanced Studies (SOKENDAI), Shizuoka, Japan
| | - Yasuhiro Yamada
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan.,Institute for Integrated Cell-Material Sciences (WPI-iCeMS)
| | - Akira Ohta
- Department of Fundamental Cell Technology, Center for iPS Cell Research and Application, and
| | - Junya Toguchida
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan.,Department of Tissue Regeneration, Institute for Frontier Life and Medical Sciences, and.,Institute for Advancement of Clinical and Translational Science (iACT), Kyoto University Hospital, Kyoto, Japan.,Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Makoto Ikeya
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
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31
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Deane CS, Wilkinson DJ, Phillips BE, Smith K, Etheridge T, Atherton PJ. "Nutraceuticals" in relation to human skeletal muscle and exercise. Am J Physiol Endocrinol Metab 2017; 312:E282-E299. [PMID: 28143855 PMCID: PMC5406990 DOI: 10.1152/ajpendo.00230.2016] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 01/25/2017] [Accepted: 01/25/2017] [Indexed: 12/16/2022]
Abstract
Skeletal muscles have a fundamental role in locomotion and whole body metabolism, with muscle mass and quality being linked to improved health and even lifespan. Optimizing nutrition in combination with exercise is considered an established, effective ergogenic practice for athletic performance. Importantly, exercise and nutritional approaches also remain arguably the most effective countermeasure for muscle dysfunction associated with aging and numerous clinical conditions, e.g., cancer cachexia, COPD, and organ failure, via engendering favorable adaptations such as increased muscle mass and oxidative capacity. Therefore, it is important to consider the effects of established and novel effectors of muscle mass, function, and metabolism in relation to nutrition and exercise. To address this gap, in this review, we detail existing evidence surrounding the efficacy of a nonexhaustive list of macronutrient, micronutrient, and "nutraceutical" compounds alone and in combination with exercise in relation to skeletal muscle mass, metabolism (protein and fuel), and exercise performance (i.e., strength and endurance capacity). It has long been established that macronutrients have specific roles and impact upon protein metabolism and exercise performance, (i.e., protein positively influences muscle mass and protein metabolism), whereas carbohydrate and fat intakes can influence fuel metabolism and exercise performance. Regarding novel nutraceuticals, we show that the following ones in particular may have effects in relation to 1) muscle mass/protein metabolism: leucine, hydroxyl β-methylbutyrate, creatine, vitamin-D, ursolic acid, and phosphatidic acid; and 2) exercise performance: (i.e., strength or endurance capacity): hydroxyl β-methylbutyrate, carnitine, creatine, nitrates, and β-alanine.
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Affiliation(s)
- Colleen S Deane
- Medical Research Council-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research and Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom
- Faculty of Health and Social Science, Bournemouth University, Bournemouth, United Kingdom; and
- Department of Sport and Health Science, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Daniel J Wilkinson
- Medical Research Council-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research and Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom
| | - Bethan E Phillips
- Medical Research Council-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research and Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom
| | - Kenneth Smith
- Medical Research Council-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research and Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom
| | - Timothy Etheridge
- Department of Sport and Health Science, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Philip J Atherton
- Medical Research Council-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research and Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Derby, United Kingdom;
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Bond P. Phosphatidic acid: biosynthesis, pharmacokinetics, mechanisms of action and effect on strength and body composition in resistance-trained individuals. Nutr Metab (Lond) 2017; 14:12. [PMID: 28184235 PMCID: PMC5294693 DOI: 10.1186/s12986-017-0166-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/03/2017] [Indexed: 12/12/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) has received much attention in the field of exercise physiology as a master regulator of skeletal muscle hypertrophy. The multiprotein complex is regulated by various signals such as growth factors, energy status, amino acids and mechanical stimuli. Importantly, the glycerophospholipid phosphatidic acid (PA) appears to play an important role in mTORC1 activation by mechanical stimulation. PA has been shown to modulate mTOR activity by direct binding to its FKBP12-rapamycin binding domain. Additionally, it has been suggested that exogenous PA activates mTORC1 via extracellular conversion to lysophosphatidic acid and subsequent binding to endothelial differentiation gene receptors on the cell surface. Recent trials have therefore evaluated the effects of PA supplementation in resistance-trained individuals on strength and body composition. As research in this field is rapidly evolving, this review attempts to provide a comprehensive overview of its biosynthesis, pharmacokinetics, mechanisms of action and effect on strength and body composition in resistance-trained individuals.
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Affiliation(s)
- Peter Bond
- PeterBond.nl, Waterhoenlaan 25, 3704 GV Zeist, The Netherlands
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33
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Chen SS, Hu Z, Zhong XP. Diacylglycerol Kinases in T Cell Tolerance and Effector Function. Front Cell Dev Biol 2016; 4:130. [PMID: 27891502 PMCID: PMC5103287 DOI: 10.3389/fcell.2016.00130] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/27/2016] [Indexed: 12/21/2022] Open
Abstract
Diacylglycerol kinases (DGKs) are a family of enzymes that regulate the relative levels of diacylglycerol (DAG) and phosphatidic acid (PA) in cells by phosphorylating DAG to produce PA. Both DAG and PA are important second messengers cascading T cell receptor (TCR) signal by recruiting multiple effector molecules, such as RasGRP1, PKCθ, and mTOR. Studies have revealed important physiological functions of DGKs in the regulation of receptor signaling and the development and activation of immune cells. In this review, we will focus on recent progresses in our understanding of two DGK isoforms, α and ζ, in CD8 T effector and memory cell differentiation, regulatory T cell development and function, and invariant NKT cell development and effector lineage differentiation.
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Affiliation(s)
- Shelley S Chen
- Division of Allergy and Immunology, Department of Pediatrics, Duke University Medical Center Durham, NC, USA
| | - Zhiming Hu
- Division of Allergy and Immunology, Department of Pediatrics, Duke University Medical CenterDurham, NC, USA; Institute of Biotherapy, School of Biotechnology, Southern Medical UniversityGuangzhou, China
| | - Xiao-Ping Zhong
- Division of Allergy and Immunology, Department of Pediatrics, Duke University Medical CenterDurham, NC, USA; Department of Immunology, Duke University Medical CenterDurham, NC, USA; Hematologic Malignancies and Cellular Therapies Program, Duke Cancer Institute, Duke University Medical CenterDurham, NC, USA
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34
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Escalante G, Alencar M, Haddock B, Harvey P. The effects of phosphatidic acid supplementation on strength, body composition, muscular endurance, power, agility, and vertical jump in resistance trained men. J Int Soc Sports Nutr 2016; 13:24. [PMID: 27274715 PMCID: PMC4891923 DOI: 10.1186/s12970-016-0135-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 05/27/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Phosphatidic acid (PA) is a lipid messenger that has been shown to increase muscle protein synthesis via signaling stimulation of the mammalian target of rapamycin (mTOR). MaxxTOR® (MT) is a supplement that contains PA as the main active ingredient but also contains other synergistic mTOR signaling substances including L-Leucine, Beta-Hydroxy-Beta-Methylbutyrate (HMB), and Vitamin D3. METHODS Eighteen healthy strength-trained males were randomly assigned to a group that either consumed MT (n = 8, 22.0 +/- 2.5 years; 175.8 +/- 11.5 cm; 80.3 +/- 15.1 kg) or a placebo (PLA) (n = 10, 25.6 +/- 4.2 years; 174.8 +/- 9.0 cm; 88.6 +/- 16.6 kg) as part of a double-blind, placebo controlled pre/post experimental design. All participants volunteered to complete the three day per week resistance training protocol for the eight week study duration. To determine the effects of MT, participants were tested on one repetition maximum (1RM) leg press strength (LP), 1RM bench press strength (BP), push-ups to failure (PU), vertical jump (VJ), pro-agility shuttle time (AG), peak power output (P), lean body mass (LBM), fat mass (FM), and thigh muscle mass (TMM). Subjects were placed and monitored on an isocaloric diet consisting of 25 protein, 50 carbohydrates, and 25 % fat by a registered dietitian. Separate two-way mixed factorial repeated measures ANOVA's (time [Pre, Post] x group [MT and PLA] were used to investigate strength, body composition, and other performance changes. Post-hoc tests were applied as appropriate. Analysis were performed via SPSS with significance at (p ≤ 0.05). RESULTS There was a significant main effect (F(1,16) = 33.30, p < 0.001) for LBM where MT significantly increased LBM when compared to the PLA group (p < 0.001). Additionally, there was a significant main effect for LP (F(1,16) = 666.74, p < 0.001) and BP (F(1,16) = 126.36, p < 0.001) where both increased significantly more in MT than PLA group (p < 0.001). No significant differences between MT and PLA were noted for FM, TMM, VJ, AG, P, or PU. CONCLUSION The results of this eight week trial suggest that the addition of MaxxTOR® to a 3-day per week resistance training program can positively impact LBM and strength beyond the results found with exercise alone.
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Affiliation(s)
- Guillermo Escalante
- California State University- San Bernardino, 5500 University Parkway, San Bernardino, CA 92407 USA
| | - Michelle Alencar
- California State University- Long Beach, 1250 Bellflower Boulevard, Long Beach, CA 90840 USA
| | - Bryan Haddock
- California State University- San Bernardino, 5500 University Parkway, San Bernardino, CA 92407 USA
| | - Phillip Harvey
- Max Muscle Sports Nutrition, 210 West Taft Avenue, Orange, CA 92865 USA ; University of Phoenix, San Diego Campus, 9645 Granite Ridge Drive, San Diego, CA 92123 USA
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35
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Shad BJ, Smeuninx B, Atherton PJ, Breen L. The mechanistic and ergogenic effects of phosphatidic acid in skeletal muscle. Appl Physiol Nutr Metab 2015; 40:1233-41. [PMID: 26566242 DOI: 10.1139/apnm-2015-0350] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Skeletal muscle mass plays a vital role in locomotion, whole-body metabolic health, and is a positive predictor of longevity. It is well established the mammalian target of rapamycin (mTOR) is a central regulator of skeletal muscle protein turnover. The pursuit to find novel nutrient compounds or functional food sources that possess the ability to activate mTOR and promote skeletal muscle protein accretion has been on going. Over the last decade, a key role has been proposed for the phospholipid phosphatidic acid (PA) in mTOR activation. Mechanical load-induced (i.e., resistance exercise) intramuscular PA can directly bind to and activate mTOR. In addition, PA provided exogenously in cell culture heightens mTOR activity, albeit indirectly. Thus, endogenously generated PA and exogenous provision of PA appear to act through distinct mechanisms that converge on mTOR and, potentially, may amplify muscle protein synthesis. In support of this notion, limited evidence from humans suggests that resistance exercise training combined with oral supplemental PA enhances strength gains and muscle hypertrophy. However, the precise mechanisms underpinning the augmented muscle remodelling response with supplemental PA remain elusive. In this review, we will critically examine available evidence from cell cultures and animal and human experimental models to provide an overview of the mechanisms through which endogenous and exogenous PA may act to promote muscle anabolism, and discuss the potential for PA as a therapeutic tool to maintain or restore skeletal muscle mass in the context of ageing and disease.
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Affiliation(s)
- Brandon James Shad
- a School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Benoit Smeuninx
- a School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Philip James Atherton
- b MRC-ARUK Centre for Excellence in Musculoskeletal Ageing Research, Birmingham, UK.,c Clinical, Metabolic and Molecular Physiology, University of Nottingham, Royal Derby Hospital, Nottingham, DE22 3DT, UK
| | - Leigh Breen
- b MRC-ARUK Centre for Excellence in Musculoskeletal Ageing Research, Birmingham, UK.,d School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, UK
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Mobley CB, Hornberger TA, Fox CD, Healy JC, Ferguson BS, Lowery RP, McNally RM, Lockwood CM, Stout JR, Kavazis AN, Wilson JM, Roberts MD. Effects of oral phosphatidic acid feeding with or without whey protein on muscle protein synthesis and anabolic signaling in rodent skeletal muscle. J Int Soc Sports Nutr 2015; 12:32. [PMID: 26279644 PMCID: PMC4537536 DOI: 10.1186/s12970-015-0094-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 08/09/2015] [Indexed: 11/10/2022] Open
Abstract
Background Phosphatidic acid (PA) is a diacyl-glycerophospholipid that acts as a signaling molecule in numerous cellular processes. Recently, PA has been proposed to stimulate skeletal muscle protein accretion, but mechanistic studies are lacking. Furthermore, it is unknown whether co-ingesting PA with other leucine-containing ingredients can enhance intramuscular anabolic signaling mechanisms. Thus, the purpose of this study was to examine if oral PA feeding acutely increases anabolic signaling markers and muscle protein synthesis (MPS) in gastrocnemius with and without whey protein concentrate (WPC). Methods Overnight fasted male Wistar rats (~250 g) were randomly assigned to four groups: control (CON, n = 6-13), PA (29 mg; n = 8), WPC (197 mg; n = 8), or PA + WPC (n = 8). Three hours post-feeding, gastrocnemius muscle was removed for markers of Akt-mTOR signaling, gene expression patterns related to skeletal muscle mass regulation and metabolism, and MPS analysis via the SUnSET method. Results Compared to CON rats, PA, WPC and PA + WPC resulted in a significant elevation in the phosphorylation of mTOR (Ser2481) and rps6 (Ser235/236) (p < 0.05) in the gastrocnemius though there were no differences between the supplemented groups. MPS levels in the gastrocnemius were significantly (p < 0.05) elevated in WPC versus CON rats, and tended to be elevated in PA versus CON rats (p = 0.08), though MPS was less in PA + WPC versus WPC rats (p < 0.05) in spite of robust increases in mTOR pathway activity markers in the former group. C2C12 myoblast data agreed with the in vivo data herein showing that PA increased MPS levels 51 % (p < 0.001) phosphorylated p70s6k (Thr389) levels 67 % (p < 0.001). Conclusions Our results are the first in vivo evidence to demonstrate that PA tends to increases MPS 3 h post-feeding, though PA may delay WPC-mediated MPS kinetics within a 3 h post-feeding window.
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Affiliation(s)
| | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI USA
| | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, AL USA
| | - James C Healy
- School of Kinesiology, Auburn University, Auburn, AL USA
| | | | - Ryan P Lowery
- Department of Health Sciences and Human Performance, University of Tampa, Tampa, FL USA
| | - Rachel M McNally
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI USA
| | | | - Jeffrey R Stout
- Human Performance Laboratory, University of Central Florida, Orlando, FL USA
| | | | - Jacob M Wilson
- Department of Health Sciences and Human Performance, University of Tampa, Tampa, FL USA
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Boneh A. Signal transduction in inherited metabolic disorders: a model for a possible pathogenetic mechanism. J Inherit Metab Dis 2015; 38:729-40. [PMID: 25735935 DOI: 10.1007/s10545-015-9820-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/20/2015] [Accepted: 02/02/2015] [Indexed: 01/08/2023]
Abstract
Signal transduction is the process by which external or internal signals exert their intracellular biological effects and by which intracellular communication is regulated. An important component of the signalling pathway is the second messenger, which is produced upon stimulation of the cell and mediates its effects downstream through phosphorylation and dephosphorylation of target proteins. Intracellular accumulation or deficiency of metabolites that serve as second messengers, due to inborn errors of their metabolism, may lead to perturbation of signalling pathways and disruption of the balance between them, serving as a missing link between the genotype, biochemical phenotype and clinical phenotype. The main second messengers that are putatively associated with the pathogenesis of IEM are 'bioactive lipids' (complex lipids and long-chain fatty acids), 'calcium', 'stress' (osmotic, reactive oxygen/nitorgen species, misfolded proteins and others) and 'metabolic' (AMP/ATP ratio, leucine, glutamine). They act through protein kinase C, calcium dependent kinases (CamK) and phosphatase (CN), 'stress-mediated' kinases (MAPK) and AMP/ATP-dependent kinase (AMPK). These signalling pathways lead to cell proliferation, inflammatory response, autophagy (and mitophagy) and apoptosis, suggesting that there are only few final common pathways involved in this pathogenetic mechanism. Questions remain regarding the complexity of the effects of the accumulating metabolites on different signalling pathways, and regarding the relative role and origin of 'proxy' second messengers such as reactive oxygen species. A better understanding of the signalling pathways in IEM may enhance the development of novel therapies in situations where normalising intracellular concentrations of the second messenger is impossible or impractical.
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Affiliation(s)
- Avihu Boneh
- Metabolic Research, Murdoch Childrens Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Vic, 3052, Melbourne, Australia,
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Golberg ND, Druzhevskaya AM, Rogozkin VA, Ahmetov II. Role of mTOR in the regulation of skeletal muscle metabolism. ACTA ACUST UNITED AC 2014. [DOI: 10.1134/s0362119714040070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Dennis MD, Coleman CS, Berg A, Jefferson LS, Kimball SR. REDD1 enhances protein phosphatase 2A-mediated dephosphorylation of Akt to repress mTORC1 signaling. Sci Signal 2014; 7:ra68. [PMID: 25056877 DOI: 10.1126/scisignal.2005103] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The protein kinase mTOR (mechanistic target of rapamycin) in complex 1 (mTORC1) promotes cell growth and proliferation in response to anabolic stimuli, including growth factors and nutrients. Growth factors activate mTORC1 by stimulating the kinase Akt, which phosphorylates and inhibits the tuberous sclerosis complex [TSC; which is composed of TSC1, TSC2, and TBC1D7 (Tre2-Bub2-Cdc16 domain family member 7)], thereby stimulating the mTORC1 activator Rheb (Ras homolog enriched in brain). We identified the mechanism through which REDD1 (regulated in DNA damage and development 1) represses the mTORC1 signaling pathway. We found that REDD1 promoted the protein phosphatase 2A (PP2A)-dependent dephosphorylation of Akt on Thr(308) but not on Ser(473). Consistent with previous studies showing that phosphorylation of Akt on Thr(308), but not on Ser(473), is necessary for phosphorylation of TSC2, we observed a REDD1-dependent reduction in the phosphorylation of TSC2 and subsequently in the activation state of Rheb. REDD1 and PP2A coimmunoprecipitated with Akt from wild-type but not REDD1 knockout mouse embryonic fibroblasts, suggesting that REDD1 may act as a targeting protein for the catalytic subunit of PP2A. Furthermore, binding to both Akt and PP2A was essential for REDD1 to repress signaling to mTORC1. Overall, the results demonstrate that REDD1 acts not only as a repressor of mTORC1 but also as a constant modulator of the phosphorylation of Akt in response to growth factors and nutrients.
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Affiliation(s)
- Michael D Dennis
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Catherine S Coleman
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Arthur Berg
- Division of Biostatistics and Bioinformatics, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Leonard S Jefferson
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Scot R Kimball
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA.
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Moon DG, Lee SE, Oh MM, Lee SC, Jeong SJ, Hong SK, Yoon CY, Byun SS, Park HS, Cheon J. NVP-BEZ235, a dual PI3K/mTOR inhibitor synergistically potentiates the antitumor effects of cisplatin in bladder cancer cells. Int J Oncol 2014; 45:1027-35. [PMID: 24969552 PMCID: PMC4121414 DOI: 10.3892/ijo.2014.2505] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 05/19/2014] [Indexed: 11/28/2022] Open
Abstract
The PI3K/Akt/mTOR pathway is a prototypic survival pathway and constitutively activated in many malignant conditions. Moreover, activation of the PI3K/Akt/mTOR pathway confers resistance to various cancer therapies and is often associated with a poor prognosis. In this study, we explored the antitumor effect of NVP-BEZ235, a dual PI3K/mTOR inhibitor in cisplatin-resistant human bladder cancer cells and its synergistic interaction with cisplatin. A human bladder cancer cell line with cisplatin resistance was exposed to escalating doses of NVP-BEZ235 alone or in combination with cisplatin and antitumor effects was determined by the CCK-8 assay. Based on a dose-response study, synergistic interaction between NVP-BEZ235 and cisplatin was evaluated by combination index (CI), three-dimensional model and clonogenic assay. The combination of NVP-BEZ235 and cisplatin caused significant synergistic antitumor effect in cisplatin-resistant bladder cancer cells over a wide dose range and reduced the IC50 of NVP-BEZ235 and cisplatin by 5.6- and 3.6-fold, respectively. Three-dimensional synergy analysis resulted in a synergy volume of 388.25 μM/ml2% indicating a strong synergistic effect of combination therapy. The combination therapy caused cell cycle arrest and caspase-dependent apoptosis. Although NVP-BEZ235 suppressed PI3K/mTOR signaling without any paradoxical induction of Akt activity, it caused MEK/ERK pathway activation. The present study demonstrated that the PI3K/mTOR dual inhibitor NVP-BEZ235 can synergistically potentiate the antitumor effects of cisplatin in cisplatin-resistant bladder cancer cells though the suppression of cell cycle progression and the survival pathway as well as induction of caspase-dependent apoptosis.
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Affiliation(s)
- Du G Moon
- Department of Urology, College of Medicine, Korea University, Guro Hospital, Seoul, Republic of Korea
| | - Sang E Lee
- Department of Urology, School of Medicine, Seoul National University, Bundang Hospital, Gyeonggi‑do, Seoul, Republic of Korea
| | - Mi M Oh
- Department of Urology, College of Medicine, Korea University, Guro Hospital, Seoul, Republic of Korea
| | - Sang C Lee
- Department of Urology, School of Medicine, Seoul National University, Bundang Hospital, Gyeonggi‑do, Seoul, Republic of Korea
| | - Seong J Jeong
- Department of Urology, School of Medicine, Seoul National University, Bundang Hospital, Gyeonggi‑do, Seoul, Republic of Korea
| | - Sung K Hong
- Department of Urology, School of Medicine, Seoul National University, Bundang Hospital, Gyeonggi‑do, Seoul, Republic of Korea
| | - Cheol Y Yoon
- Department of Urology, College of Medicine, Korea University, Guro Hospital, Seoul, Republic of Korea
| | - Seok S Byun
- Department of Urology, School of Medicine, Seoul National University, Bundang Hospital, Gyeonggi‑do, Seoul, Republic of Korea
| | - Hong S Park
- Department of Urology, College of Medicine, Korea University, Guro Hospital, Seoul, Republic of Korea
| | - Jun Cheon
- Department of Urology, College of Medicine, Korea University, Anam Hospital, Seoul, Republic of Korea
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Joy JM, Gundermann DM, Lowery RP, Jäger R, McCleary SA, Purpura M, Roberts MD, Wilson SM, Hornberger TA, Wilson JM. Phosphatidic acid enhances mTOR signaling and resistance exercise induced hypertrophy. Nutr Metab (Lond) 2014; 11:29. [PMID: 24959196 PMCID: PMC4066292 DOI: 10.1186/1743-7075-11-29] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 06/07/2014] [Indexed: 01/03/2023] Open
Abstract
Introduction The lipid messenger phosphatidic acid (PA) plays a critical role in the stimulation of mTOR signaling. However, the mechanism by which PA stimulates mTOR is currently unknown. Therefore, the purpose of this study was to compare the effects of various PA precursors and phospholipids on their ability to stimulate mTOR signaling and its ability to augment resistance training-induced changes in body composition and performance. Methods In phase one, C2C12 myoblasts cells were stimulated with different phospholipids and phospholipid precursors derived from soy and egg sources. The ratio of phosphorylated p70 (P-p70-389) to total p70 was then used as readout for mTOR signaling. In phase two, resistance trained subjects (n = 28, 21 ± 3 years, 77 ± 4 kg, 176 ± 9 cm) consumed either 750 mg PA daily or placebo and each took part in an 8 week periodized resistance training program. Results In phase one, soy-phosphatidylserine, soy-Lyso-PA, egg-PA, and soy-PA stimulated mTOR signaling, and the effects of soy-PA (+636%) were significantly greater than egg-PA (+221%). In phase two, PA significantly increased lean body mass (+2.4 kg), cross sectional area (+1.0 cm), and leg press strength (+51.9 kg) over placebo. Conclusion PA significantly activates mTOR and significantly improved responses in skeletal muscle hypertrophy, lean body mass, and maximal strength to resistance exercise.
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Affiliation(s)
- Jordan M Joy
- Department of Health Sciences and Human Performance, The University of Tampa, 401 W. Kennedy Blvd., Box 30 F, Tampa, FL 33606, USA
| | - David M Gundermann
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Ryan P Lowery
- Department of Health Sciences and Human Performance, The University of Tampa, 401 W. Kennedy Blvd., Box 30 F, Tampa, FL 33606, USA
| | - Ralf Jäger
- Increnovo LLC, 2138 E Lafayette Pl, Milwaukee, WI 53202, USA
| | - Sean A McCleary
- Department of Health Sciences and Human Performance, The University of Tampa, 401 W. Kennedy Blvd., Box 30 F, Tampa, FL 33606, USA
| | - Martin Purpura
- Increnovo LLC, 2138 E Lafayette Pl, Milwaukee, WI 53202, USA
| | | | | | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Jacob M Wilson
- Department of Health Sciences and Human Performance, The University of Tampa, 401 W. Kennedy Blvd., Box 30 F, Tampa, FL 33606, USA
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MicroRNA-363-mediated downregulation of S1PR1 suppresses the proliferation of hepatocellular carcinoma cells. Cell Signal 2014; 26:1347-54. [PMID: 24631531 DOI: 10.1016/j.cellsig.2014.02.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 02/14/2014] [Accepted: 02/26/2014] [Indexed: 12/20/2022]
Abstract
S1PR1 plays a crucial role in promoting proliferation of hepatocellular carcinoma (HCC). Over expression of S1PR1 is observed in HCC cell lines. The mechanisms underlying the aberrant expression of S1PR1 are not known well. MircroRNAs are important regulators of gene expression and disproportionate microRNAs can result in dysregulation of oncogenes in cancer cells. In this study, we found that miR-363, a potential tumor suppressor microRNA, downregulated the expression of S1PR1 and inhibited the proliferation of HCC cells. Bioinformatic analysis predicted a putative binding site of miR-363 within the 3'-UTR of S1PR1 mRNA. Luciferase reporter assay showed that miR-363 directly targeted the 3'-UTR of S1PR1 mRNA. Transfection of miR-363 mimics suppressed S1PR1 expression in HCC cells, followed by the repression of the activation of ERK and STAT3. Moreover, we found that the expression of downstream genes of ERK and STAT3, including PDGF-A, PDGF-B, MCL-1 and Bcl-xL, was suppressed after miR-363 transfection. Taken together, the present study demonstrated that miR-363 was a negative regulator of S1PR1 expression in HCC cells and inhibited cell proliferation, suggesting that the miR-363/S1PR1 pathway might be a novel target for the treatment of HCC.
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El Osta M, Liu M, Adada M, Senkal CE, Idkowiak-Baldys J, Obeid LM, Clarke CJ, Hannun YA. Sustained PKCβII activity confers oncogenic properties in a phospholipase D- and mTOR-dependent manner. FASEB J 2013; 28:495-505. [PMID: 24121461 DOI: 10.1096/fj.13-230557] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Protein kinase C (PKC) is a family of serine/threonine kinases implicated in a variety of physiological processes. We have shown previously that sustained activation of the classical PKCα and PKCβII induces their phospholipase D (PLD)-dependent internalization and translocation to a subset of the recycling endosomes defined by the presence of PKC and PLD (the pericentrion), which results in significant differences in phosphorylation of PKC substrates. Here, we have investigated the biological consequences of sustained PKC activity and the involvement of PLD in this process. We find that sustained activation of PKC results in activation of the mammalian target of rapamycin (mTOR)/S6 kinase pathway in a PLD- and endocytosis-dependent manner, with both pharmacologic inhibitors and siRNA implicating the PLD2 isoform. Notably, dysregulated overexpression of PKCβII in A549 lung cancer cells was necessary for the enhanced proliferation and migration of these cancer cells. Inhibition of PKCβII with enzastaurin reduced A549 cell proliferation by >60% (48 h) and migration by >50%. These biological effects also required both PLD activity and mTOR function, with both the PLD inhibitor FIPI and rapamycin reducing cell growth by >50%. Reciprocally, forced overexpression of wild-type PKCβII, but not an F666D mutant that cannot interact with PLD, was sufficient to enhance cell growth and increase migration of noncancerous HEK cells; indeed, both properties were almost doubled when compared to vector control and PKC-F666D-overexpressing cells. Notably, this condition was also dependent on both PLD and mTOR activity. In summary, these data define a PKC-driven oncogenic signaling pathway that requires both PLD and mTOR, and suggest that inhibitors of PLD or mTOR would be beneficial in cancers where PKC overexpression is a contributing or driving factor.
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Affiliation(s)
- Mohamad El Osta
- 2Stony Brook Cancer Center and Department of Medicine, Stony Brook University, 100 Nicolls Rd., Stony Brook, NY 11794, USA.
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Marino JS, Hinds TD, Potter RA, Ondrus E, Onion JL, Dowling A, McLoughlin TJ, Sanchez ER, Hill JW. Suppression of protein kinase C theta contributes to enhanced myogenesis in vitro via IRS1 and ERK1/2 phosphorylation. BMC Cell Biol 2013; 14:39. [PMID: 24053798 PMCID: PMC3848841 DOI: 10.1186/1471-2121-14-39] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 09/17/2013] [Indexed: 12/03/2022] Open
Abstract
Background Differentiation and fusion of skeletal muscle myoblasts into multi-nucleated myotubes is required for neonatal development and regeneration in adult skeletal muscle. Herein, we report novel findings that protein kinase C theta (PKCθ) regulates myoblast differentiation via phosphorylation of insulin receptor substrate-1 and ERK1/2. Results In this study, PKCθ knockdown (PKCθshRNA) myotubes had reduced inhibitory insulin receptor substrate-1 ser1095 phosphorylation, enhanced myoblast differentiation and cell fusion, and increased rates of protein synthesis as determined by [3H] phenylalanine incorporation. Phosphorylation of insulin receptor substrate-1 ser632/635 and extracellular signal-regulated kinase1/2 (ERK1/2) was increased in PKCθshRNA cells, with no change in ERK5 phosphorylation, highlighting a PKCθ-regulated myogenic pathway. Inhibition of PI3-kinase prevented cell differentiation and fusion in control cells, which was attenuated in PKCθshRNA cells. Thus, with reduced PKCθ, differentiation and fusion occur in the absence of PI3-kinase activity. Inhibition of the ERK kinase, MEK1/2, impaired differentiation and cell fusion in control cells. Differentiation was preserved in PKCθshRNA cells treated with a MEK1/2 inhibitor, although cell fusion was blunted, indicating PKCθ regulates differentiation via IRS1 and ERK1/2, and this occurs independently of MEK1/2 activation. Conclusion Cellular signaling regulating the myogenic program and protein synthesis are complex and intertwined. These studies suggest that PKCθ regulates myogenic and protein synthetic signaling via the modulation of IRS1and ERK1/2 phosphorylation. Myotubes lacking PKCθ had increased rates of protein synthesis and enhanced myotube development despite reduced activation of the canonical anabolic-signaling pathway. Further investigation of PKCθ regulated signaling may reveal important interactions regulating skeletal muscle health in an insulin resistant state.
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Affiliation(s)
- Joseph S Marino
- Center for Diabetes and Endocrine Research, Department of Physiology and Pharmacology, University of Toledo College of Medicine, Toledo, OH 43614, USA.
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Hong-Brown LQ, Brown CR, Navaratnarajah M, Lang CH. Activation of AMPK/TSC2/PLD by alcohol regulates mTORC1 and mTORC2 assembly in C2C12 myocytes. Alcohol Clin Exp Res 2013; 37:1849-61. [PMID: 23895284 DOI: 10.1111/acer.12174] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 04/03/2013] [Indexed: 01/02/2023]
Abstract
BACKGROUND Ethanol (EtOH) decreases muscle protein synthesis, and this is associated with reduced mammalian target of rapamycin complex (mTORC)1 and increased mTORC2 activities. In contrast, phospholipase D (PLD) and its metabolite phosphatidic acid (PA) positively regulate mTORC1 signaling, whereas their role in mTORC2 function is less well defined. Herein, we examine the role that PLD and PA play in EtOH-mediated mTOR signaling. METHODS C2C12 myoblasts were incubated with EtOH for 18 to 24 hours. For PA experiments, cells were pretreated with the drug for 25 minutes followed by 50-minute incubation with PA in the presence or absence of EtOH. The phosphorylation state of various proteins was assessed by immunoblotting. Protein-protein interactions were determined by immunoprecipitation and immunoblotting. PLD activity was measured using the Amplex Red PLD assay kit. PA concentrations were determined with a total PA assay kit. RESULTS PA levels and PLD activity increased in C2C12 myocytes exposed to EtOH (100 mM). Increased PLD activity was blocked by inhibitors of AMP-activated protein kinase (AMPK) (compound C) and phosphoinositide 3-kinase (PI3K) (wortmannin). Likewise, suppression of PLD activity with CAY10594 prevented EtOH-induced Akt (S473) phosphorylation. PLD inhibition also enhanced the binding of Rictor to mSin1 and the negative regulatory proteins Deptor and 14-3-3. Addition of PA to myocytes decreased Akt phosphorylation, but changes in mTORC2 activity were not associated with altered binding of complex members and 14-3-3. PA increased S6K1 phosphorylation, with the associated increase in mTORC1 activity being regulated by reduced phosphorylation of AMPKα (T172) and its target tuberous sclerosis protein complex (TSC)2 (S1387). This resulted in increased Rheb and RagA/RagC GTPase interactions with mTOR, as well as suppression of mTORC2. CONCLUSIONS EtOH-induced increases in PLD activity and PA may partially counterbalance the adverse effects of this agent. EtOH and PA regulate mTORC1 via a PI3K/AMPK/TSC2/PLD signaling cascade. PA stimulates mTORC1 function and suppresses activation of mTORC2 as part of an mTORC1/2 feedback loop.
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Affiliation(s)
- Ly Q Hong-Brown
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania
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Krishna S, Zhong XP. Regulation of Lipid Signaling by Diacylglycerol Kinases during T Cell Development and Function. Front Immunol 2013; 4:178. [PMID: 23847619 PMCID: PMC3701226 DOI: 10.3389/fimmu.2013.00178] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 06/19/2013] [Indexed: 01/14/2023] Open
Abstract
Diacylglycerol (DAG) and phosphatidic acid (PA) are bioactive lipids synthesized when the T cell receptor binds to a cognate peptide-MHC complex. DAG triggers signaling by recruiting Ras guanyl-releasing protein 1, PKCθ, and other effectors, whereas PA binds to effector molecules that include mechanistic target of rapamycin, Src homology region 2 domain-containing phosphatase 1, and Raf1. While DAG-mediated pathways have been shown to play vital roles in T cell development and function, the importance of PA-mediated signals remains less clear. The diacylglycerol kinase (DGK) family of enzymes phosphorylates DAG to produce PA, serving as a molecular switch that regulates the relative levels of these critical second messengers. Two DGK isoforms, α and ζ, are predominantly expressed in T lineage cells and play an important role in conventional αβ T cell development. In mature T cells, the activity of these DGK isoforms aids in the maintenance of self-tolerance by preventing T cell hyper-activation and promoting T cell anergy. In this review, we discuss the roles of DAG-mediated pathways, PA-effectors, and DGKs in T cell development and function. We also highlight recent work that has uncovered previously unappreciated roles for DGK activity, for instance in invariant NKT cell development, anti-tumor and anti-viral CD8 responses, and the directional secretion of soluble effectors.
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Affiliation(s)
- Sruti Krishna
- Department of Pediatrics, Division of Allergy and Immunology, Duke University Medical Center , Durham, NC , USA ; Department of Immunology, Duke University Medical Center , Durham, NC , USA
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Feng P, Huang C. Phospholipase D-mTOR signaling is compromised in a rat model of depression. J Psychiatr Res 2013; 47:579-85. [PMID: 23421961 DOI: 10.1016/j.jpsychires.2013.01.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 01/04/2013] [Accepted: 01/11/2013] [Indexed: 10/27/2022]
Abstract
Depression is associated with structural and neurochemical changes in limbic structures, including the hippocampus, that control emotion and mood. Structural abnormalities such as decrease in hippocampal cell proliferation, neurogenesis and hippocampal volume, and loss of neurons and glial cells have been widely reported in physical and psychosocial stress paradigms and animal model of depression, but corresponding neurochemical changes are largely unknown. Using neonatal clomipramine (CL)-treated rats as a model to elucidate the association of phospholipase D (PLD) and mammalian target of rapamycin (mTOR) signaling with depressive pathology, we found that the hippocampus of CL-treated rats showed significantly down-regulation of PLD1 expression and attenuation of PLD activity which leads to the less formation of phosphatidic acid (PA), an activator of mTOR, and free choline, a potential biomarker for depression. With lower PA levels which could affect mTOR signaling, we further observed that the phosphorylation of p70S6 kinase, one of the downstream effectors of mTOR, was also significantly decreased in the hippocampus of CL-treated rats compared to the controls. Down-regulation of PLD1 expression, PLD activity and p70S6 phosphorylation was also found in the hypothalamus and frontal cortex with CL-treated rats. Our results indicate that PLD-mTOR signaling is associated with depressive disorder.
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Affiliation(s)
- Pingfu Feng
- Louis Stokes Cleveland Veteran Affairs Medical Center, Cleveland, OH 44109, USA
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Ogasawara R, Kobayashi K, Tsutaki A, Lee K, Abe T, Fujita S, Nakazato K, Ishii N. mTOR signaling response to resistance exercise is altered by chronic resistance training and detraining in skeletal muscle. J Appl Physiol (1985) 2013; 114:934-40. [PMID: 23372143 DOI: 10.1152/japplphysiol.01161.2012] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Resistance training-induced muscle anabolism and subsequent hypertrophy occur most rapidly during the early phase of training and become progressively slower over time. Currently, little is known about the intracellular signaling mechanisms underlying changes in the sensitivity of muscles to training stimuli. We investigated the changes in the exercise-induced phosphorylation of hypertrophic signaling proteins during chronic resistance training and subsequent detraining. Male rats were divided into four groups: 1 bout (1B), 12 bouts (12B), 18 bouts (18B), and detraining (DT). In the DT group, rats were subjected to 12 exercise sessions, detrained for 12 days, and then were subjected to 1 exercise session before being killed. Isometric training consisted of maximum isometric contraction, which was produced by percutaneous electrical stimulation of the gastrocnemius muscle every other day. Muscles were removed 24 h after the final exercise session. Levels of total and phosphorylated p70S6K, 4E-BP1, rpS6, and p90RSK levels were measured, and phosphorylation of p70S6K, rpS6, and p90RSK was elevated in the 1B group compared with control muscle (CON) after acute resistance exercise, whereas repeated bouts of exercise suppressed those phosphorylation in both 12B and 18B groups. Interestingly, these phosphorylation levels were restored after 12 days of detraining in the DT group. On the contrary, phosphorylation of 4E-BP1 was not altered with chronic training and detraining, indicating that, with chronic resistance training, anabolic signaling becomes less sensitive to resistance exercise stimuli but is restored after a short detraining period.
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Affiliation(s)
- Riki Ogasawara
- The Research Organization of Science and Technology, Ritsumeikan University, Kusatsu, Shiga, Japan.
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Matheny RW, Lynch CM, Leandry LA. Enhanced Akt phosphorylation and myogenic differentiation in PI3K p110β-deficient myoblasts is mediated by PI3K p110α and mTORC2. Growth Factors 2012; 30:367-84. [PMID: 23137199 DOI: 10.3109/08977194.2012.734507] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Phosphoinositide 3-kinase (PI3K) is a principal regulator of Akt activation and myogenesis; however, the function of PI3K p110β in these processes is not well defined. To address this, we investigated the role of p110β in Akt activation and skeletal muscle cell differentiation. We found that Akt phosphorylation was enhanced in p110β-deficient myoblasts in response to Insulin-like Growth Factor-I (IGF-I), epidermal growth factor, or p110α overexpression, as compared to p110β-sufficient cells. This effect was associated with increased mammalian target of rapamycin complex 2 activation, even in myoblasts deficient in mSin1 and rictor. Conversely, in response to the G-protein-coupled receptor agonist lysophosphatidic acid, Akt phosphorylation was attenuated in p110β-deficient myoblasts. Loss of p110β also enhanced the expression of myogenic markers at the myoblast stage and during the first 48 h of differentiation. These data demonstrate that reductions in p110β are associated with agonist-specific Akt hyperactivation and accelerated myogenesis, thus revealing a negative role for p110β in Akt activation and during myoblast differentiation.
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Affiliation(s)
- Ronald W Matheny
- Military Performance Division, US Army Research Institute of Environmental Medicine, 15 Kansas Street, Building 42, Natick, MA 01760, USA.
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You JS, Frey JW, Hornberger TA. Mechanical stimulation induces mTOR signaling via an ERK-independent mechanism: implications for a direct activation of mTOR by phosphatidic acid. PLoS One 2012; 7:e47258. [PMID: 23077579 PMCID: PMC3471816 DOI: 10.1371/journal.pone.0047258] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 09/10/2012] [Indexed: 11/18/2022] Open
Abstract
Signaling by mTOR is a well-recognized component of the pathway through which mechanical signals regulate protein synthesis and muscle mass. However, the mechanisms involved in the mechanical regulation of mTOR signaling have not been defined. Nevertheless, recent studies suggest that a mechanically-induced increase in phosphatidic acid (PA) may be involved. There is also evidence which suggests that mechanical stimuli, and PA, utilize ERK to induce mTOR signaling. Hence, we reasoned that a mechanically-induced increase in PA might promote mTOR signaling via an ERK-dependent mechanism. To test this, we subjected mouse skeletal muscles to mechanical stimulation in the presence or absence of a MEK/ERK inhibitor, and then measured several commonly used markers of mTOR signaling. Transgenic mice expressing a rapamycin-resistant mutant of mTOR were also used to confirm the validity of these markers. The results demonstrated that mechanically-induced increases in p70(s6k) T389 and 4E-BP1 S64 phosphorylation, and unexpectedly, a loss in total 4E-BP1, were fully mTOR-dependent signaling events. Furthermore, we determined that mechanical stimulation induced these mTOR-dependent events, and protein synthesis, through an ERK-independent mechanism. Similar to mechanical stimulation, exogenous PA also induced mTOR-dependent signaling via an ERK-independent mechanism. Moreover, PA was able to directly activate mTOR signaling in vitro. Combined, these results demonstrate that mechanical stimulation induces mTOR signaling, and protein synthesis, via an ERK-independent mechanism that potentially involves a direct interaction of PA with mTOR. Furthermore, it appears that a decrease in total 4E-BP1 may be part of the mTOR-dependent mechanism through which mechanical stimuli activate protein synthesis.
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Affiliation(s)
- Jae Sung You
- Program in Cellular and Molecular Biology, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
- Department of Comparative Biosciences in the School of Veterinary Medicine, University of Wisconsin - Madison, Madison, Wisconsin, United States of America
| | - John W. Frey
- Department of Comparative Biosciences in the School of Veterinary Medicine, University of Wisconsin - Madison, Madison, Wisconsin, United States of America
| | - Troy A. Hornberger
- Program in Cellular and Molecular Biology, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
- Department of Comparative Biosciences in the School of Veterinary Medicine, University of Wisconsin - Madison, Madison, Wisconsin, United States of America
- * E-mail:
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