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Wang J, Kainrad N, Shen H, Zhou Z, Rote P, Zhang Y, Nagy LE, Wu J, You M. Hepatic Knockdown of Splicing Regulator Slu7 Ameliorates Inflammation and Attenuates Liver Injury in Ethanol-Fed Mice. THE AMERICAN JOURNAL OF PATHOLOGY 2018; 188:1807-1819. [PMID: 29870742 DOI: 10.1016/j.ajpath.2018.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 04/16/2018] [Accepted: 05/03/2018] [Indexed: 12/11/2022]
Abstract
Aberrant precursor mRNA splicing plays a pivotal role in liver diseases. However, roles of splicing regulators in alcoholic liver disease are unknown. Herein, we investigated a splicing regulator, Slu7, in the development of alcoholic steatohepatitis. Adenovirus-mediated alteration of hepatic Slu7 expression in mice pair fed either with or without (as control) ethanol in their diet was used. Knockdown of hepatic Slu7 by adenovirus-Slu7shRNA treatment ameliorated inflammation and attenuated liver injury in mice after ethanol administration. Mechanistically, reducing liver Slu7 expression increased the expression of sirtuin 1 (SIRT1) full-length and repressed the splicing of SIRT1 into SIRT1-ΔExon8 isoform in ethanol-fed mice. Knockdown of hepatic Slu7 in the ethanol-fed mice also ameliorated splicing of lipin-1 and serine/arginine-rich splicing factor 3 (Srsf3). In concordance with ameliorated splicing of SIRT1, lipin-1, and Srsf3, knockdown of hepatic Slu7 inhibited the activity of NF-κB, normalized iron and zinc homeostasis, reduced oxidative stress, and attenuated liver damage in ethanol-fed mice. In addition, hepatic Slu7 was significantly elevated in patients with alcoholic steatohepatitis. Our present study illustrates a novel role of Slu7 in alcoholic liver injury and suggests that dysregulated Slu7 may contribute to the pathogenesis of human alcoholic steatohepatitis.
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Affiliation(s)
- Jiayou Wang
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, Ohio; Department of Anatomy, School of Fundamental Medical Science, Guangzhou University of Chinese Medicine, Guangzhou, People's Republic of China
| | - Noah Kainrad
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, Ohio
| | - Hong Shen
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, Ohio; Department of Liver Diseases, Guangdong Hospital of Traditional Chinese Medicine in Zhuhai, Zhuhai, People's Republic of China
| | - Zhou Zhou
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, Ohio
| | - Paula Rote
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio
| | - Yanqiao Zhang
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio
| | - Laura E Nagy
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - Jiashin Wu
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, Ohio
| | - Min You
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, Rootstown, Ohio.
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52
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Propranolol sensitizes prostate cancer cells to glucose metabolism inhibition and prevents cancer progression. Sci Rep 2018; 8:7050. [PMID: 29728578 PMCID: PMC5935740 DOI: 10.1038/s41598-018-25340-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/18/2018] [Indexed: 02/04/2023] Open
Abstract
Propranolol, a widely used non-selective beta-adrenergic receptor blocker, was recently shown to display anticancer properties. Its potential to synergize with certain drugs has been also outlined. However, it is necessary to take into account all the properties of propranolol to select a drug that could be efficiently combined with. Propranolol was reported to block the late phase of autophagy. Hence, we hypothesized that in condition enhancing autophagy flux, cancer cells should be especially sensitive to propranolol. 2DG, a glycolysis inhibitor, is an anti-tumor agent having limited effect in monotherapy notably due to induction of pro-survival autophagy. Here, we report that treatment of cancer cells with propranolol in combination with the glycolysis inhibitor 2DG induced a massive accumulation of autophagosome due to autophagy blockade. The propranolol +2DG treatment efficiently prevents prostate cancer cell proliferation, induces cell apoptosis, alters mitochondrial morphology, inhibits mitochondrial bioenergetics and aggravates ER stress in vitro and also suppresses tumor growth in vivo. Our study underlines for the first time the interest to take advantage of the ability of propranolol to inhibit autophagy to design new anti-cancer therapies.
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53
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Wu Q, Madany P, Dobson JR, Schnabl JM, Sharma S, Smith TC, van Wijnen AJ, Stein JL, Lian JB, Stein GS, Muthuswami R, Imbalzano AN, Nickerson JA. The BRG1 chromatin remodeling enzyme links cancer cell metabolism and proliferation. Oncotarget 2018; 7:38270-38281. [PMID: 27223259 PMCID: PMC5122388 DOI: 10.18632/oncotarget.9505] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 05/01/2016] [Indexed: 12/20/2022] Open
Abstract
Cancer cells reprogram cellular metabolism to meet the demands of growth. Identification of the regulatory machinery that regulates cancer-specific metabolic changes may open new avenues for anti-cancer therapeutics. The epigenetic regulator BRG1 is a catalytic ATPase for some mammalian SWI/SNF chromatin remodeling enzymes. BRG1 is a well-characterized tumor suppressor in some human cancers, but is frequently overexpressed without mutation in other cancers, including breast cancer. Here we demonstrate that BRG1 upregulates de novo lipogenesis and that this is crucial for cancer cell proliferation. Knockdown of BRG1 attenuates lipid synthesis by impairing the transcription of enzymes catalyzing fatty acid and lipid synthesis. Remarkably, exogenous addition of palmitate, the key intermediate in fatty acid synthesis, rescued the cancer cell proliferation defect caused by BRG1 knockdown. Our work suggests that targeting BRG1 to reduce lipid metabolism and, thereby, to reduce proliferation, has promise for epigenetic therapy in triple negative breast cancer.
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Affiliation(s)
- Qiong Wu
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Pasil Madany
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jason R Dobson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jake M Schnabl
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Soni Sharma
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Tara C Smith
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Andre J van Wijnen
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Janet L Stein
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, WA, USA
| | - Jane B Lian
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, WA, USA
| | - Gary S Stein
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, WA, USA
| | - Rohini Muthuswami
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Anthony N Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
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Vozenilek AE, Navratil AR, Green JM, Coleman DT, Blackburn CMR, Finney AC, Pearson BH, Chrast R, Finck BN, Klein RL, Orr AW, Woolard MD. Macrophage-Associated Lipin-1 Enzymatic Activity Contributes to Modified Low-Density Lipoprotein-Induced Proinflammatory Signaling and Atherosclerosis. Arterioscler Thromb Vasc Biol 2017; 38:324-334. [PMID: 29217509 DOI: 10.1161/atvbaha.117.310455] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 11/20/2017] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Macrophage proinflammatory responses induced by modified low-density lipoproteins (modLDL) contribute to atherosclerotic progression. How modLDL causes macrophages to become proinflammatory is still enigmatic. Macrophage foam cell formation induced by modLDL requires glycerolipid synthesis. Lipin-1, a key enzyme in the glycerolipid synthesis pathway, contributes to modLDL-elicited macrophage proinflammatory responses in vitro. The objective of this study was to determine whether macrophage-associated lipin-1 contributes to atherogenesis and to assess its role in modLDL-mediated signaling in macrophages. APPROACH AND RESULTS We developed mice lacking lipin-1 in myeloid-derived cells and used adeno-associated viral vector 8 expressing the gain-of-function mutation of mouse proprotein convertase subtilisin/kexin type 9 (adeno-associated viral vector 8-proprotein convertase subtilisin/kexin type 9) to induce hypercholesterolemia and plaque formation. Mice lacking myeloid-associated lipin-1 had reduced atherosclerotic burden compared with control mice despite similar plasma lipid levels. Stimulation of bone marrow-derived macrophages with modLDL activated a persistent protein kinase Cα/βII-extracellular receptor kinase1/2-jun proto-oncogene signaling cascade that contributed to macrophage proinflammatory responses that was dependent on lipin-1 enzymatic activity. CONCLUSIONS Our data demonstrate that macrophage-associated lipin-1 is atherogenic, likely through persistent activation of a protein kinase Cα/βII-extracellular receptor kinase1/2-jun proto-oncogene signaling cascade that contributes to foam cell proinflammatory responses. Taken together, these results suggest that modLDL-induced foam cell formation and modLDL-induced macrophage proinflammatory responses are not independent consequences of modLDL stimulation but rather are both directly influenced by enhanced lipid synthesis.
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Affiliation(s)
- Aimee E Vozenilek
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - Aaron R Navratil
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - Jonette M Green
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - David T Coleman
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - Cassidy M R Blackburn
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - Alexandra C Finney
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - Brenna H Pearson
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - Roman Chrast
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - Brian N Finck
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - Ronald L Klein
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - A Wayne Orr
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.)
| | - Matthew D Woolard
- From the Department of Microbiology and Immunology (A.E.V., C.M.R.B., M.D.W.), Department of Pathology and Translational Pathobiology (J.M.G., B.H.P., A.W.O.), Department of Cell Biology and Anatomy (A.C.F.), Feist-Weiller Cancer Center (D.T.C.), and Pharmacology, Toxicology, and Neuroscience (R.L.K.), Louisiana State University Health Sciences Center, Shreveport; Department of Pharmacology, University of California San Diego, La Jolla (A.R.N.); Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (R.C.); and Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO (B.N.F.).
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55
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Pillai AN, Shukla S, Rahaman A. An evolutionarily conserved phosphatidate phosphatase maintains lipid droplet number and endoplasmic reticulum morphology but not nuclear morphology. Biol Open 2017; 6:1629-1643. [PMID: 28954739 PMCID: PMC5703613 DOI: 10.1242/bio.028233] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phosphatidic acid phosphatases are involved in the biosynthesis of phospholipids and triacylglycerol, and also act as transcriptional regulators. Studies to ascertain their role in lipid metabolism and membrane biogenesis are restricted to Opisthokonta and Archaeplastida. Here, we report the role of phosphatidate phosphatase (PAH) in Tetrahymena thermophila, belonging to the Alveolata clade. We identified two PAH homologs in Tetrahymena, TtPAH1 and TtPAH2 Loss of function of TtPAH1 results in reduced lipid droplet number and an increase in endoplasmic reticulum (ER) content. It also results in more ER sheet structure as compared to wild-type Tetrahymena Surprisingly, we did not observe a visible defect in the nuclear morphology of the ΔTtpah1 mutant. TtPAH1 rescued all known defects in the yeast pah1Δ strain and is conserved functionally between Tetrahymena and yeast. The homologous gene derived from Trypanosoma also rescued the defects of the yeast pah1Δ strain. Our results indicate that PAH, previously known to be conserved among Opisthokonts, is also present in a set of distant lineages. Thus, a phosphatase cascade is evolutionarily conserved and is functionally interchangeable across eukaryotic lineages.
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Affiliation(s)
- Anoop Narayana Pillai
- School of Biological Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, HBNI, P.O. Jatni, Khurda 752050, Odisha, India
| | - Sushmita Shukla
- School of Biological Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, HBNI, P.O. Jatni, Khurda 752050, Odisha, India
| | - Abdur Rahaman
- School of Biological Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, HBNI, P.O. Jatni, Khurda 752050, Odisha, India
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56
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Boroda S, Takkellapati S, Lawrence RT, Entwisle SW, Pearson JM, Granade ME, Mullins GR, Eaton JM, Villén J, Harris TE. The phosphatidic acid-binding, polybasic domain is responsible for the differences in the phosphoregulation of lipins 1 and 3. J Biol Chem 2017; 292:20481-20493. [PMID: 28982975 DOI: 10.1074/jbc.m117.786574] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 09/23/2017] [Indexed: 11/06/2022] Open
Abstract
Lipins 1, 2, and 3 are Mg2+-dependent phosphatidic acid phosphatases and catalyze the penultimate step of triacylglycerol synthesis. We have previously investigated the biochemistry of lipins 1 and 2 and shown that di-anionic phosphatidic acid (PA) augments their activity and lipid binding and that lipin 1 activity is negatively regulated by phosphorylation. In the present study, we show that phosphorylation does not affect the catalytic activity of lipin 3 or its ability to associate with PA in vitro The lipin proteins each contain a conserved polybasic domain (PBD) composed of nine lysine and arginine residues located between the conserved N- and C-terminal domains. In lipin 1, the PBD is the site of PA binding and sensing of the PA electrostatic charge. The specific arrangement and number of the lysines and arginines of the PBD vary among the lipins. We show that the different PBDs of lipins 1 and 3 are responsible for the presence of phosphoregulation on the former but not the latter enzyme. To do so, we generated lipin 1 that contained the PBD of lipin 3 and vice versa. The lipin 1 enzyme with the lipin 3 PBD lost its ability to be regulated by phosphorylation but remained downstream of phosphorylation by mammalian target of rapamycin. Conversely, the presence of the lipin 1 PBD in lipin 3 subjected the enzyme to negative intramolecular control by phosphorylation. These results indicate a mechanism for the observed differences in lipin phosphoregulation in vitro.
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Affiliation(s)
- Salome Boroda
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908 and
| | - Sankeerth Takkellapati
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908 and
| | - Robert T Lawrence
- the Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | - Samuel W Entwisle
- the Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | - Jennifer M Pearson
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908 and
| | - Mitchell E Granade
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908 and
| | - Garrett R Mullins
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908 and
| | - James M Eaton
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908 and
| | - Judit Villén
- the Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | - Thurl E Harris
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908 and
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57
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Sherr GL, LaMassa N, Li E, Phillips G, Shen CH. Pah1p negatively regulates the expression of V-ATPase genes as well as vacuolar acidification. Biochem Biophys Res Commun 2017; 491:693-700. [PMID: 28756231 DOI: 10.1016/j.bbrc.2017.07.127] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Accepted: 07/22/2017] [Indexed: 01/16/2023]
Abstract
In yeast, PAH1 plays an important role in cell homeostasis and lipid biosynthesis. PAH1 encodes for the PA phosphatase, Pah1p, which is responsible for de novo TAG and phospholipid synthesis. It has been suggested that the lack of Pah1p causes irregular vacuolar morphology and dysfunctional V-ATPase pump activity. However, the molecular connection between Pah1p and V-ATPase activity has remained unclear. Through real-time PCR, we have shown that PAH1 is maximally induced at the stationary stage in the presence of inositol. We also found that vacuoles were less fragmented when PAH1 is maximally expressed. Subsequently, we observed that vacuoles from pah1Δ cells were more acidic than those in WT cells. Furthermore, V-ATPase genes were upregulated in the absence of Pah1p. These results suggest that Pah1p plays an important role in vacuolar activity by negatively regulating the expression of V-ATPase genes. As such, we provide evidence to show the role of Pah1p in vacuolar acidification and fragmentation.
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Affiliation(s)
- Goldie Libby Sherr
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, United States; PhD Program in Biology, The Graduate Center, City University of New York, 365 Fifth Avenue, New York 10016, United States
| | - Nicole LaMassa
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, United States
| | - Erxin Li
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, United States
| | - Greg Phillips
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, United States
| | - Chang-Hui Shen
- Department of Biology, College of Staten Island, City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, United States; PhD Program in Biology, The Graduate Center, City University of New York, 365 Fifth Avenue, New York 10016, United States; Institute for Macromolecular Assemblies, City University of New York, 160 Convent Avenue, New York, NY 10031, United States.
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58
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Kim JY, Kim G, Lim SC, Choi HS. LPIN1 promotes epithelial cell transformation and mammary tumourigenesis via enhancing insulin receptor substrate 1 stability. Carcinogenesis 2016; 37:1199-1209. [PMID: 27729374 DOI: 10.1093/carcin/bgw104] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 08/25/2016] [Accepted: 10/10/2016] [Indexed: 02/07/2023] Open
Abstract
LPIN1 is a protein that exhibits dual functions as a phosphatidic acid phosphatase enzyme in regulation of triglyceride and glycerophospholipid metabolism and a transcriptional coregulator. Through unknown tumour-promoting mechanism, LPIN1 frequently observed in various human cancer cell lines controls main cellular processes involved in cancer progression. Here, we demonstrate that LPIN1 enhances the tumour-promoting function of insulin receptor substrate 1 (IRS1) by controlling IRS1 stability. LPIN1 interacts with IRS1 in an insulin growth factor-1-dependent signalling pathway and inhibits its serine phosphorylation, and thereby eliminating ubiquitin-dependent degradation of IRS1 via proteasomal and lysosomal pathways. Consequently, LPIN1 overexpression increases IRS1 abundance and enhances IRS1's ability to induce epithelial cell proliferation and mammary tumourigenesis. By contrast, depletion or inhibition of LPIN1 in breast cancer cells leads to a decreased IRS1 level, which subsequently inhibits the RAF1-mediated signalling pathway and AP-1 activity. In the syngeneic 4T1 breast cancer model, LPIN1 overexpression increased tumour development, whereas inhibition of LPIN1 and IRS1 suppressed it. Consistent with these observations, LPIN1 levels were positively correlated with IRS1 expression in human breast cancer. Thus, our results indicate a mechanism by which IRS1 expression is increased in breast cancer, and LPIN1 may be a promising drug target for anticancer therapy.
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Affiliation(s)
| | | | - Sung-Chul Lim
- Department of Pathology, School of Medicine, Chosun University, 309 Philmundaero, Dong-gu, Gwangju 61452, Republic of Korea
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59
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Qiu Y, Hassaninasab A, Han GS, Carman GM. Phosphorylation of Dgk1 Diacylglycerol Kinase by Casein Kinase II Regulates Phosphatidic Acid Production in Saccharomyces cerevisiae. J Biol Chem 2016; 291:26455-26467. [PMID: 27834677 DOI: 10.1074/jbc.m116.763839] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 11/08/2016] [Indexed: 11/06/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, Dgk1 diacylglycerol (DAG) kinase catalyzes the CTP-dependent phosphorylation of DAG to form phosphatidic acid (PA). The enzyme in conjunction with Pah1 PA phosphatase controls the levels of PA and DAG for the synthesis of triacylglycerol and membrane phospholipids, the growth of the nuclear/endoplasmic reticulum membrane, and the formation of lipid droplets. Little is known about how DAG kinase activity is regulated by posttranslational modification. In this work, we examined the phosphorylation of Dgk1 DAG kinase by casein kinase II (CKII). When phosphate groups were globally reduced using nonspecific alkaline phosphatase, Triton X-100-solubilized membranes from DGK1-overexpressing cells showed a 7.7-fold reduction in DAG kinase activity; the reduced enzyme activity could be increased 5.5-fold by treatment with CKII. Dgk1(1-77) expressed heterologously in Escherichia coli was phosphorylated by CKII on a serine residue, and its phosphorylation was dependent on time as well as on the concentrations of CKII, ATP, and Dgk1(1-77). We used site-specific mutagenesis, coupled with phosphorylation analysis and phosphopeptide mapping, to identify Ser-45 and Ser-46 of Dgk1 as the CKII target sites, with Ser-46 being the major phosphorylation site. In vivo, the S46A and S45A/S46A mutations of Dgk1 abolished the stationary phase-dependent stimulation of DAG kinase activity. In addition, the phosphorylation-deficient mutations decreased Dgk1 function in PA production and in eliciting pah1Δ phenotypes, such as the expansion of the nuclear/endoplasmic reticulum membrane, reduced lipid droplet formation, and temperature sensitivity. This work demonstrates that the CKII-mediated phosphorylation of Dgk1 regulates its function in the production of PA.
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Affiliation(s)
- Yixuan Qiu
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Azam Hassaninasab
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - George M Carman
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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60
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Wang R, Wang T, Lu W, Zhang W, Chen W, Kang X, Huang Y. Three indel variants in chicken LPIN1 exon 6/flanking region are associated with performance and carcass traits. Br Poult Sci 2016; 56:621-30. [PMID: 26523976 DOI: 10.1080/00071668.2015.1113502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
LPIN1 is a Mg(2+)-dependent phosphatidic acid phosphatase. Variation in chicken LPIN1 exon 6 and its flanking regions were identified and three indel variants in 6 breeds and their associations with performance traits were studied. Seven variants were detected from 6 breeds, which contained a synonymous tri-allelic variant (c.924A/T/C) and three indels. The exon 6 variants detected from chicken breeds were conserved among bird species. The indel variation frequency presented clear differences among breeds. Two coding indels (c.1014-1018del3 and c.1125-1138del12) were multiples of three nucleotides and maintained the open reading frames of LPIN1 proteins. However, they were predicted to result in the clear change of the RNA secondary structure of chicken LPIN1 exon 6 and LPIN1 protein conformation. The association analysis showed that c.871-15-22del6 variation had a significant effect on body weight at hatch (BW0) and 2 weeks (BW2); c. 1014-1018del3 variation had a significant effect on BW4, BW6, caecum length and gizzard weight (GW) traits; c.1125-1138del12 variation had a significant effect on BW12, shank length at 4 weeks (SL4), carcass weight, lactate dehydrogenase traits (LDH), glucose (GLU) and albumin (ALB) traits. The genotype combination for c.1014-1018del3 and c.1125-1138del12 also presented significant effects on SL4, SL8, GW, leg muscle weight, ALB, GLU and LDH. The study demonstrated that chicken LPIN1 has an important effect on body, carcass and organ weight, serum LDH, GLU and ALB level.
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Affiliation(s)
- R Wang
- a College of Livestock Husbandry and Veterinary Engineering , Henan Agricultural University , Zhengzhou , Henan , P. R. China
| | - T Wang
- a College of Livestock Husbandry and Veterinary Engineering , Henan Agricultural University , Zhengzhou , Henan , P. R. China
| | - W Lu
- a College of Livestock Husbandry and Veterinary Engineering , Henan Agricultural University , Zhengzhou , Henan , P. R. China
| | - W Zhang
- a College of Livestock Husbandry and Veterinary Engineering , Henan Agricultural University , Zhengzhou , Henan , P. R. China
| | - W Chen
- a College of Livestock Husbandry and Veterinary Engineering , Henan Agricultural University , Zhengzhou , Henan , P. R. China
| | - X Kang
- a College of Livestock Husbandry and Veterinary Engineering , Henan Agricultural University , Zhengzhou , Henan , P. R. China
| | - Y Huang
- a College of Livestock Husbandry and Veterinary Engineering , Henan Agricultural University , Zhengzhou , Henan , P. R. China
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61
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Temprano A, Sembongi H, Han GS, Sebastián D, Capellades J, Moreno C, Guardiola J, Wabitsch M, Richart C, Yanes O, Zorzano A, Carman GM, Siniossoglou S, Miranda M. Redundant roles of the phosphatidate phosphatase family in triacylglycerol synthesis in human adipocytes. Diabetologia 2016; 59:1985-94. [PMID: 27344312 PMCID: PMC4969345 DOI: 10.1007/s00125-016-4018-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 05/23/2016] [Indexed: 12/20/2022]
Abstract
AIMS/HYPOTHESIS In mammals, the evolutionary conserved family of Mg(2+)-dependent phosphatidate phosphatases (PAP1), involved in phospholipid and triacylglycerol synthesis, consists of lipin-1, lipin-2 and lipin-3. While mutations in the murine Lpin1 gene cause lipodystrophy and its knockdown in mouse 3T3-L1 cells impairs adipogenesis, deleterious mutations of human LPIN1 do not affect adipose tissue distribution. However, reduced LPIN1 and PAP1 activity has been described in participants with type 2 diabetes. We aimed to characterise the roles of all lipin family members in human adipose tissue and adipogenesis. METHODS The expression of the lipin family was analysed in adipose tissue in a cross-sectional study. Moreover, the effects of lipin small interfering RNA (siRNA)-mediated depletion on in vitro human adipogenesis were assessed. RESULTS Adipose tissue gene expression of the lipin family is altered in type 2 diabetes. Depletion of every lipin family member in a human Simpson-Golabi-Behmel syndrome (SGBS) pre-adipocyte cell line, alters expression levels of adipogenic transcription factors and lipid biosynthesis genes in early stages of differentiation. Lipin-1 knockdown alone causes a 95% depletion of PAP1 activity. Despite the reduced PAP1 activity and alterations in early adipogenesis, lipin-silenced cells differentiate and accumulate neutral lipids. Even combinatorial knockdown of lipins shows mild effects on triacylglycerol accumulation in mature adipocytes. CONCLUSIONS/INTERPRETATION Overall, our data support the hypothesis of alternative pathways for triacylglycerol synthesis in human adipocytes under conditions of repressed lipin expression. We propose that induction of alternative lipid phosphate phosphatases, along with the inhibition of lipid hydrolysis, contributes to the maintenance of triacylglycerol content to near normal levels.
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Affiliation(s)
- Ana Temprano
- Joan XXIII University Hospital, Pere Virgili Health Research Institut (IISPV), Modular Building, C/ Mallafre Guasch, Tarragona, 43005, Spain
- Department of Biochemistry and Molecular Biology, Rovira i Virgili University, Tarragona, Spain
| | - Hiroshi Sembongi
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/Medical Research Council Building, Hills Road, Cambridge, CB2 0XY, UK
- , Chesterford Research Park, Little Chesterford, Saffron Walden, UK
| | - Gil-Soo Han
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, NJ, USA
| | - David Sebastián
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Jordi Capellades
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Centre for Omic Sciences, Rovira i Virgili University, Reus, Spain
| | - Cristóbal Moreno
- Joan XXIII University Hospital, Pere Virgili Health Research Institut (IISPV), Modular Building, C/ Mallafre Guasch, Tarragona, 43005, Spain
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Juan Guardiola
- Department of Pulmonary, Critical Care and Sleep Medicine, University of Louisville, Louisville, KY, USA
| | - Martin Wabitsch
- Division of Paediatric Endocrinology and Diabetes, Interdisciplinary Obesity Clinic, University Clinic for Child and Adolescent Medicine, University of Ulm, Ulm, Germany
| | - Cristóbal Richart
- Joan XXIII University Hospital, Pere Virgili Health Research Institut (IISPV), Modular Building, C/ Mallafre Guasch, Tarragona, 43005, Spain
- GEMMAIR Research Group - Applied Medicine, Department of Medicine and Surgery, Rovira i Virgili University (URV), Tarragona, Spain
| | - Oscar Yanes
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
- Centre for Omic Sciences, Rovira i Virgili University, Reus, Spain
- Department of Electronic Engineering, Rovira i Virgili University, Tarragona, Spain
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - George M Carman
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, NJ, USA
| | - Symeon Siniossoglou
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/Medical Research Council Building, Hills Road, Cambridge, CB2 0XY, UK.
| | - Merce Miranda
- Joan XXIII University Hospital, Pere Virgili Health Research Institut (IISPV), Modular Building, C/ Mallafre Guasch, Tarragona, 43005, Spain.
- Biomedical Research Networking Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain, .
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Brohée L, Demine S, Willems J, Arnould T, Colige AC, Deroanne CF. Lipin-1 regulates cancer cell phenotype and is a potential target to potentiate rapamycin treatment. Oncotarget 2016; 6:11264-80. [PMID: 25834103 PMCID: PMC4484455 DOI: 10.18632/oncotarget.3595] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 02/20/2015] [Indexed: 01/30/2023] Open
Abstract
Lipogenesis inhibition was reported to induce apoptosis and repress proliferation of cancer cells while barely affecting normal cells. Lipins exhibit dual function as enzymes catalyzing the dephosphorylation of phosphatidic acid to diacylglycerol and as co-transcriptional regulators. Thus, they are able to regulate lipid homeostasis at several nodal points. Here, we show that lipin-1 is up-regulated in several cancer cell lines and overexpressed in 50 % of high grade prostate cancers. The proliferation of prostate and breast cancer cells, but not of non-tumorigenic cells, was repressed upon lipin-1 knock-down. Lipin-1 depletion also decreased cancer cell migration through RhoA activation. Lipin-1 silencing did not significantly affect global lipid synthesis but enhanced the cellular concentration of phosphatidic acid. In parallel, autophagy was induced while AKT and ribosomal protein S6 phosphorylation were repressed. We also observed a compensatory regulation between lipin-1 and lipin-2 and demonstrated that their co-silencing aggravates the phenotype induced by lipin-1 silencing alone. Most interestingly, lipin-1 depletion or lipins inhibition with propranolol sensitized cancer cells to rapamycin. These data indicate that lipin-1 controls main cellular processes involved in cancer progression and that its targeting, alone or in combination with other treatments, could open new avenues in anticancer therapy.
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Affiliation(s)
- Laura Brohée
- Laboratory of Connective Tissues Biology, GIGA-Cancer, University of Liège, Tour de Pathologie, Sart-Tilman, Belgium
| | - Stéphane Demine
- Laboratory of Biochemistry and Cell Biology (URBC), NARILIS (Namur Research Institute for Life Sciences), University of Namur (UNamur), Namur, Belgium
| | - Jérome Willems
- Laboratory of Connective Tissues Biology, GIGA-Cancer, University of Liège, Tour de Pathologie, Sart-Tilman, Belgium
| | - Thierry Arnould
- Laboratory of Biochemistry and Cell Biology (URBC), NARILIS (Namur Research Institute for Life Sciences), University of Namur (UNamur), Namur, Belgium
| | - Alain C Colige
- Laboratory of Connective Tissues Biology, GIGA-Cancer, University of Liège, Tour de Pathologie, Sart-Tilman, Belgium
| | - Christophe F Deroanne
- Laboratory of Connective Tissues Biology, GIGA-Cancer, University of Liège, Tour de Pathologie, Sart-Tilman, Belgium
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63
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Jaradat SA, Amayreh W, Al-Qa'qa' K, Krayyem J. Molecular analysis of LPIN1 in Jordanian patients with rhabdomyolysis. Meta Gene 2015; 7:90-4. [PMID: 26909335 PMCID: PMC4733219 DOI: 10.1016/j.mgene.2015.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 09/15/2015] [Accepted: 12/02/2015] [Indexed: 12/31/2022] Open
Abstract
Recessive mutations in LPIN1, which encodes a phosphatidate phosphatase enzyme, are a frequent cause of severe rhabdomyolysis in childhood. Hence, we sequenced the 19 coding exons of the gene in eight patients with recurrent hereditary myoglobinuria from four unrelated families in Jordan. The long-term goal is to facilitate molecular genetic diagnosis without the need for invasive procedures such as muscle biopsies. Three different mutations were detected, including the novel missense mutation c.2395G>C (Gly799Arg), which was found in two families. The two other mutations, c.2174G>A (Arg725His) and c.1162C>T (Arg388X), have been previously identified, and were found to cosegregate with the disease phenotype in the other two families. Intriguingly, patients homozygous for Arg725His were also homozygous for the c.1828C>T (Pro610Ser) polymorphism, and were exercise-intolerant between myoglobinuria episodes. Notably, patients homozygous for Arg388X were also homozygous for the c.2250G>C silent variant (Gly750Gly). Taken together, the data provide family-based evidence linking hereditary myoglobinuria to pathogenic variations in the C-terminal lipin domain of the enzyme. This finding highlights the functional significance of this domain in the absence of structural information. This is the first analysis of LPIN1 in myoglobinuria patients of Jordanian origin, and the fourth such analysis worldwide. LPIN1 mutations were cataloged in families with hereditary myoglobinuria. A novel missense Gly799Arg mutation was identified. Arg725His, the only other known missense mutation, was confirmed to be pathogenic. Arg388X, a known nonsense mutation, was the most common among Arabic patients. Patients exercise-intolerant between myoglobinuria episodes have a second mutation.
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Affiliation(s)
- Saied A Jaradat
- Princess Haya Biotechnology Center, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Wajdi Amayreh
- Department of Pediatrics, Metabolic Genetics Clinic, Queen Rania Al-Abdullah Children's Hospital, King Hussein Medical Centre, Amman 11855, Jordan
| | - Kefah Al-Qa'qa'
- Department of Pediatrics, Metabolic Genetics Clinic, Queen Rania Al-Abdullah Children's Hospital, King Hussein Medical Centre, Amman 11855, Jordan
| | - Jan Krayyem
- Princess Haya Biotechnology Center, Jordan University of Science and Technology, Irbid 22110, Jordan
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64
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Barneda D, Planas-Iglesias J, Gaspar ML, Mohammadyani D, Prasannan S, Dormann D, Han GS, Jesch SA, Carman GM, Kagan V, Parker MG, Ktistakis NT, Klein-Seetharaman J, Dixon AM, Henry SA, Christian M. The brown adipocyte protein CIDEA promotes lipid droplet fusion via a phosphatidic acid-binding amphipathic helix. eLife 2015; 4:e07485. [PMID: 26609809 PMCID: PMC4755750 DOI: 10.7554/elife.07485] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 11/25/2015] [Indexed: 12/22/2022] Open
Abstract
Maintenance of energy homeostasis depends on the highly regulated storage and release of triacylglycerol primarily in adipose tissue, and excessive storage is a feature of common metabolic disorders. CIDEA is a lipid droplet (LD)-protein enriched in brown adipocytes promoting the enlargement of LDs, which are dynamic, ubiquitous organelles specialized for storing neutral lipids. We demonstrate an essential role in this process for an amphipathic helix in CIDEA, which facilitates embedding in the LD phospholipid monolayer and binds phosphatidic acid (PA). LD pairs are docked by CIDEA trans-complexes through contributions of the N-terminal domain and a C-terminal dimerization region. These complexes, enriched at the LD–LD contact site, interact with the cone-shaped phospholipid PA and likely increase phospholipid barrier permeability, promoting LD fusion by transference of lipids. This physiological process is essential in adipocyte differentiation as well as serving to facilitate the tight coupling of lipolysis and lipogenesis in activated brown fat. DOI:http://dx.doi.org/10.7554/eLife.07485.001 If other energy sources become unavailable, cells fall back on stores of fatty molecules called lipids. These are held in membrane-enclosed compartments in the cell called lipid droplets, which in mammals are particularly abundant in fat cells called adipocytes. There are two main types of adipocytes: white adipocytes have a single giant lipid droplet, whereas brown adipocytes contain many smaller droplets. Proteins embedded in the membrane that surrounds a lipid droplet help to control the droplet’s growth and when it releases lipids. For example, a protein called CIDEA, which is only found in brown adipocytes, helps lipid droplets to grow by enabling one droplet to transfer its contents to another droplet. However, little is known about how this occurs. By combining cell biology, biophysical and computer modelling approaches, Barneda et al. investigated how normal and mutant forms of CIDEA affect the growth of lipid droplets. These experiments identified a helix in the structure of CIDEA that embeds it in the membrane, from where it can then interact with CIDEA proteins on other lipid droplets to hold the droplets together. In addition, the helix interacts with a molecule in the lipid droplet membrane called phosphatidic acid. Barneda et al. suggest that this interaction helps to transfer the contents of one droplet to another by making it easier for lipids to move through the droplets’ membranes. The next challenge is to characterize the mechanisms that control CIDEA activity to influence the formation of the multiple lipid droplets that distinguish brown and BRITE (brown-in-white) adipocytes from white adipocytes. The lipid droplets in brown adipocytes are an important target for research to combat obesity, due to the 'burning' rather than storing of lipids that occurs in these cells. DOI:http://dx.doi.org/10.7554/eLife.07485.002
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Affiliation(s)
- David Barneda
- Institute of Reproductive and Developmental Biology, Imperial College London, London, United Kingdom
| | | | - Maria L Gaspar
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Dariush Mohammadyani
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, United States
| | - Sunil Prasannan
- Department of Chemistry, University of Warwick, Coventry, United Kingdom
| | - Dirk Dormann
- Microscopy Facility, MRC Clinical Sciences Centre, Imperial College London, London, United Kingdom
| | - Gil-Soo Han
- Department of Food Science, Rutgers Center for Lipid Research, Rutgers University, New Brunswick, United States
| | - Stephen A Jesch
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - George M Carman
- Department of Food Science, Rutgers Center for Lipid Research, Rutgers University, New Brunswick, United States
| | - Valerian Kagan
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, United States
| | - Malcolm G Parker
- Institute of Reproductive and Developmental Biology, Imperial College London, London, United Kingdom
| | | | - Judith Klein-Seetharaman
- Warwick Medical School, University of Warwick, Coventry, United Kingdom.,Department of Bioengineering, University of Pittsburgh, Pittsburgh, United States
| | - Ann M Dixon
- Department of Chemistry, University of Warwick, Coventry, United Kingdom
| | - Susan A Henry
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Mark Christian
- Institute of Reproductive and Developmental Biology, Imperial College London, London, United Kingdom.,Warwick Medical School, University of Warwick, Coventry, United Kingdom
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Cardozo Gizzi AM, Prucca CG, Gaveglio VL, Renner ML, Pasquaré SJ, Caputto BL. The Catalytic Efficiency of Lipin 1β Increases by Physically Interacting with the Proto-oncoprotein c-Fos. J Biol Chem 2015; 290:29578-92. [PMID: 26475860 DOI: 10.1074/jbc.m115.678821] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Indexed: 01/19/2023] Open
Abstract
Phosphatidic acid (PA) is a central precursor for membrane phospholipid biosynthesis. The lipin family is a magnesium-dependent type I PA phosphatase involved in de novo synthesis of neutral lipids and phospholipids. The regulation of lipin activity may govern the pathways by which these lipids are synthesized and control the cellular levels of important signaling lipids. Moreover, the proto-oncoprotein c-Fos has an emerging role in glycerolipid synthesis regulation; by interacting with key synthesizing enzymes it is able to increase overall phospho- and glycolipid synthesis. We studied the lipin 1β enzyme activity in a cell-free system using PA/Triton X-100 mixed micelles as substrate, analyzing it in the presence/absence of c-Fos. We found that lipin 1β kcat value increases around 40% in the presence of c-Fos, with no change in the lipin 1β affinity for the PA/Triton X-100 mixed micelles. We also probed a physical interaction between both proteins. Although the c-Fos domain involved in lipin activation is its basic domain, the interaction domain is mapped to the N-terminal c-Fos. In conclusion, we provide evidence for a novel positive regulator of lipin 1β PA phosphatase activity that is not achieved via altering its subcellular localization or affinity for membranes but rather through directly increasing its catalytic efficiency.
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Affiliation(s)
- Andres M Cardozo Gizzi
- From the Centro de Investigaciones en Química Biológica de Córdoba (Consejo Nacional de Investigaciones Científicas y Técnicas), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba and
| | - Cesar G Prucca
- From the Centro de Investigaciones en Química Biológica de Córdoba (Consejo Nacional de Investigaciones Científicas y Técnicas), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba and
| | - Virginia L Gaveglio
- the Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Edificio El Camino La Carrindanga Km 7, 8000 Bahía Blanca, Argentina
| | - Marianne L Renner
- From the Centro de Investigaciones en Química Biológica de Córdoba (Consejo Nacional de Investigaciones Científicas y Técnicas), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba and
| | - Susana J Pasquaré
- the Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Edificio El Camino La Carrindanga Km 7, 8000 Bahía Blanca, Argentina
| | - Beatriz L Caputto
- From the Centro de Investigaciones en Química Biológica de Córdoba (Consejo Nacional de Investigaciones Científicas y Técnicas), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba and
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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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67
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Hsieh LS, Su WM, Han GS, Carman GM. Phosphorylation regulates the ubiquitin-independent degradation of yeast Pah1 phosphatidate phosphatase by the 20S proteasome. J Biol Chem 2015; 290:11467-78. [PMID: 25809482 DOI: 10.1074/jbc.m115.648659] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Indexed: 01/08/2023] Open
Abstract
Saccharomyces cerevisiae Pah1 phosphatidate phosphatase, which catalyzes the conversion of phosphatidate to diacylglycerol for triacylglycerol synthesis and simultaneously controls phosphatidate levels for phospholipid synthesis, is subject to the proteasome-mediated degradation in the stationary phase of growth. In this study, we examined the mechanism for its degradation using purified Pah1 and isolated proteasomes. Pah1 expressed in S. cerevisiae or Escherichia coli was not degraded by the 26S proteasome, but by its catalytic 20S core particle, indicating that its degradation is ubiquitin-independent. The degradation of Pah1 by the 20S proteasome was dependent on time and proteasome concentration at the pH optimum of 7.0. The 20S proteasomal degradation was conserved for human lipin 1 phosphatidate phosphatase. The degradation analysis using Pah1 truncations and its fusion with GFP indicated that proteolysis initiates at the N- and C-terminal unfolded regions. The folded region of Pah1, in particular the haloacid dehalogenase-like domain containing the DIDGT catalytic sequence, was resistant to the proteasomal degradation. The structural change of Pah1, as reflected by electrophoretic mobility shift, occurs through its phosphorylation by Pho85-Pho80, and the phosphorylation sites are located within its N- and C-terminal unfolded regions. Phosphorylation of Pah1 by Pho85-Pho80 inhibited its degradation, extending its half-life by ∼2-fold. The dephosphorylation of endogenously phosphorylated Pah1 by the Nem1-Spo7 protein phosphatase, which is highly specific for the sites phosphorylated by Pho85-Pho80, stimulated the 20S proteasomal degradation and reduced its half-life by 2.6-fold. These results indicate that the proteolysis of Pah1 by the 20S proteasome is controlled by its phosphorylation state.
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Affiliation(s)
- Lu-Sheng Hsieh
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Wen-Min Su
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - George M Carman
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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68
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Bi L, Jiang Z, Zhou J. The role of lipin-1 in the pathogenesis of alcoholic fatty liver. Alcohol Alcohol 2015; 50:146-51. [PMID: 25595739 DOI: 10.1093/alcalc/agu102] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
AIMS The aim of this review was to focus on the knowledge of the role of lipin-1 in the pathogenesis of alcoholic fatty liver. METHODS Systematic review of animal clinical and cell level studies related to the function of lipin-1 on alcoholic fatty liver, alcoholic hepatitis and alcoholic liver cirrhosis disease. RESULT Ethanol could increase the expression of lipin-1 through the AMPK-SREBP-1 signaling and dramatically increase the ratio of Lpin1β to Lpin1α by SIRT1-SFRS10-Lpin1β/α axis in the liver. Moreover, research has shown that over-expression of lipin-1 could also remarkably suppress very low density lipoprotein-triacylglyceride secretion. Last, lipin-1 has potent anti-inflammatory property. CONCLUSION In conclusion, lipin-1 has dual functions in lipid metabolism. In the cytoplasm, lipin-1β functions as a Mg(2+)-dependent phosphatidic acid phosphohydrolase (PAP) enzyme in triglyceride synthesis pathways. In the nucleus, lipin-1α acts as a transcriptional co-regulator to regulate the capacity of the liver for fatty acid oxidation and activity of the lipogenic enzyme. In hepatocytes of alcoholic fatty liver disease (AFLD), ethanol increases the expression of lipin-1 through the AMPK-SREBP-1 signaling and the Lpin1β/α ratio by SIRT1-SFRS10- Lpin1β/α axis. Of course, in addition to that, ethanol could also produce the PAP activity and interrupt the nucleus function of lipin-1. Furthermore, over-expression of lipin-1 could remarkably suppress very low-density lipoprotein-triacylglyceride (VLDL-TAG) secretion. In the end, endogenous lipin-1 has potent anti-inflammatory property. Increased synthesis of TAG, decreased fatty acid oxidation, impaired VLDL-TAG secretion and activated inflammatory factors act together to exacerbate the development of AFLD.
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Affiliation(s)
- Lijuan Bi
- Department of Infectious Disease, Third Hospital, Hebei Medical University, 139 ZiQiang Road, Shijiazhuang 050051, China
| | - Zhian Jiang
- Department of Infectious Disease, Third Hospital, Hebei Medical University, 139 ZiQiang Road, Shijiazhuang 050051, China
| | - Junying Zhou
- Department of Infectious Disease, Third Hospital, Hebei Medical University, 139 ZiQiang Road, Shijiazhuang 050051, China
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69
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Chen Y, Rui BB, Tang LY, Hu CM. Lipin Family Proteins - Key Regulators in Lipid Metabolism. ANNALS OF NUTRITION AND METABOLISM 2014; 66:10-8. [DOI: 10.1159/000368661] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 09/19/2014] [Indexed: 11/19/2022]
Abstract
Background: Proteins in the lipin family play a key role in lipid synthesis due to their phosphatidate phosphatase activity, and they also act as transcriptional coactivators to regulate the expression of genes involved in lipid metabolism. The lipin family includes three members, lipin1, lipin2, and lipin3, which exhibit tissue-specific expression, indicating that they may have distinct roles in mediating disease. To date, most studies have focused on lipin1, whereas the roles of lipin2 and lipin3 are less understood. Summary: This review introduces the structural characteristics, physiological functions, relationship to lipid metabolism, and patterns of expression of the lipin family proteins, highlighting their roles in lipid metabolic homeostasis. © 2014 S. Karger AG, Basel
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70
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Su WM, Han GS, Carman GM. Yeast Nem1-Spo7 protein phosphatase activity on Pah1 phosphatidate phosphatase is specific for the Pho85-Pho80 protein kinase phosphorylation sites. J Biol Chem 2014; 289:34699-708. [PMID: 25359770 DOI: 10.1074/jbc.m114.614883] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pah1 is the phosphatidate phosphatase in the yeast Saccharomyces cerevisiae that produces diacylglycerol for triacylglycerol synthesis and concurrently controls the levels of phosphatidate used for phospholipid synthesis. Phosphorylation and dephosphorylation of Pah1 regulate its subcellular location and phosphatidate phosphatase activity. Compared with its phosphorylation by multiple protein kinases, Pah1 is dephosphorylated by a protein phosphatase complex consisting of Nem1 (catalytic subunit) and Spo7 (regulatory subunit). In this work, we characterized the Nem1-Spo7 phosphatase complex for its enzymological, kinetic, and regulatory properties with phosphorylated Pah1. The dephosphorylation of Pah1 by Nem1-Spo7 phosphatase resulted in the stimulation (6-fold) of phosphatidate phosphatase activity. For Pah1 phosphorylated by the Pho85-Pho80 kinase complex, maximum Nem1-Spo7 phosphatase activity required Mg(2+) ions (8 mm) and Triton X-100 (0.25 mm) at pH 5.0. The energy of activation for the reaction was 8.4 kcal/mol, and the enzyme was thermally labile at temperatures above 40 °C. The enzyme activity was inhibited by sodium vanadate, sodium fluoride, N-ethylmaleimide, and phenylglyoxal but was not significantly affected by lipids or nucleotides. Nem1-Spo7 phosphatase activity was dependent on the concentrations of Pah1 phosphorylated by Pho85-Pho80, Cdc28-cyclin B, PKA, and PKC with kcat and Km values of 0.29 s(-1) and 81 nm, 0.11 s(-1) and 127 nm, 0.10 s(-1) and 46 nm, and 0.02 s(-1) and 38 nm, respectively. Its specificity constant (kcat/Km) for Pah1 phosphorylated by Pho85-Pho80 was 1.6-, 4-, and 6-fold higher, respectively, than that phosphorylated by PKA, Cdc28-cyclin B, and PKC.
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Affiliation(s)
- Wen-Min Su
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - George M Carman
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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71
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Eaton JM, Takkellapati S, Lawrence RT, McQueeney KE, Boroda S, Mullins GR, Sherwood SG, Finck BN, Villén J, Harris TE. Lipin 2 binds phosphatidic acid by the electrostatic hydrogen bond switch mechanism independent of phosphorylation. J Biol Chem 2014; 289:18055-66. [PMID: 24811178 DOI: 10.1074/jbc.m114.547604] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipin 2 is a phosphatidic acid phosphatase (PAP) responsible for the penultimate step of triglyceride synthesis and dephosphorylation of phosphatidic acid (PA) to generate diacylglycerol. The lipin family of PA phosphatases is composed of lipins 1-3, which are members of the conserved haloacid dehalogenase superfamily. Although genetic alteration of LPIN2 in humans is known to cause Majeed syndrome, little is known about the biochemical regulation of its PAP activity. Here, in an attempt to gain a better general understanding of the biochemical nature of lipin 2, we have performed kinetic and phosphorylation analyses. We provide evidence that lipin 2, like lipin 1, binds PA via the electrostatic hydrogen bond switch mechanism but has a lower rate of catalysis. Like lipin 1, lipin 2 is highly phosphorylated, and we identified 15 phosphosites. However, unlike lipin 1, the phosphorylation of lipin 2 is not induced by insulin signaling nor is it sensitive to inhibition of the mammalian target of rapamycin. Importantly, phosphorylation of lipin 2 does not negatively regulate either membrane binding or PAP activity. This suggests that lipin 2 functions as a constitutively active PA phosphatase in stark contrast to the high degree of phosphorylation-mediated regulation of lipin 1. This knowledge of lipin 2 regulation is important for a deeper understanding of how the lipin family functions with respect to lipid synthesis and, more generally, as an example of how the membrane environment around PA can influence its effector proteins.
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Affiliation(s)
- James M Eaton
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Sankeerth Takkellapati
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Robert T Lawrence
- the Department of Genome Sciences, University of Washington, Seattle, Washington 98105
| | - Kelley E McQueeney
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Salome Boroda
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Garrett R Mullins
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Samantha G Sherwood
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Brian N Finck
- the Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, and
| | - Judit Villén
- the Department of Genome Sciences, University of Washington, Seattle, Washington 98105
| | - Thurl E Harris
- From the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908,
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72
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Baba T, Kashiwagi Y, Arimitsu N, Kogure T, Edo A, Maruyama T, Nakao K, Nakanishi H, Kinoshita M, Frohman MA, Yamamoto A, Tani K. Phosphatidic acid (PA)-preferring phospholipase A1 regulates mitochondrial dynamics. J Biol Chem 2014; 289:11497-11511. [PMID: 24599962 PMCID: PMC4036285 DOI: 10.1074/jbc.m113.531921] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 03/04/2014] [Indexed: 12/14/2022] Open
Abstract
Recent studies have suggested that phosphatidic acid (PA), a cone-shaped phospholipid that can generate negative curvature of lipid membranes, participates in mitochondrial fusion. However, precise mechanisms underling the production and consumption of PA on the mitochondrial surface are not fully understood. Phosphatidic acid-preferring phospholipase A1 (PA-PLA1)/DDHD1 is the first identified intracellular phospholipase A1 and preferentially hydrolyzes PA in vitro. Its cellular and physiological functions have not been elucidated. In this study, we show that PA-PLA1 regulates mitochondrial dynamics. PA-PLA1, when ectopically expressed in HeLa cells, induced mitochondrial fragmentation, whereas its depletion caused mitochondrial elongation. The effects of PA-PLA1 on mitochondrial morphology appear to counteract those of MitoPLD, a mitochondrion-localized phospholipase D that produces PA from cardiolipin. Consistent with high levels of expression of PA-PLA1 in testis, PA-PLA1 knock-out mice have a defect in sperm formation. In PA-PLA1-deficient sperm, the mitochondrial structure is disorganized, and an abnormal gap structure exists between the middle and principal pieces. A flagellum is bent at that position, leading to a loss of motility. Our results suggest a possible mechanism of PA regulation of the mitochondrial membrane and demonstrate an in vivo function of PA-PLA1 in the organization of mitochondria during spermiogenesis.
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Affiliation(s)
- Takashi Baba
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Yuriko Kashiwagi
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Nagisa Arimitsu
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Takeshi Kogure
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Ayumi Edo
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Tomohiro Maruyama
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Kazuki Nakao
- RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Hiroki Nakanishi
- Research Center for Biosignal, Akita University, Akita 010-8543, Japan
| | - Makoto Kinoshita
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Michael A Frohman
- Department of Pharmacology and Center for Developmental Genetics, Stony Brook University, Stony Brook, New York 11794-5140, and
| | - Akitsugu Yamamoto
- Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga 526-0829, Japan
| | - Katsuko Tani
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan,.
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73
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Yin H, Hu M, Liang X, Ajmo JM, Li X, Bataller R, Odena G, Stevens SM, You M. Deletion of SIRT1 from hepatocytes in mice disrupts lipin-1 signaling and aggravates alcoholic fatty liver. Gastroenterology 2014; 146:801-11. [PMID: 24262277 PMCID: PMC3943758 DOI: 10.1053/j.gastro.2013.11.008] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 11/08/2013] [Accepted: 11/12/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS Sirtuin (SIRT1) is a nicotinamide adenine dinucleotide-dependent protein deacetylase that regulates hepatic lipid metabolism by modifying histones and transcription factors. Ethanol exposure disrupts SIRT1 activity and contributes to alcoholic liver disease in rodents, but the exact pathogenic mechanism is not clear. We compared mice with liver-specific deletion of Sirt1 (Sirt1LKO) mice with their LOX littermates (controls). METHODS We induced alcoholic liver injury in male Sirt1LKO and control mice, placing them on Lieber-DeCarli ethanol-containing diets for 10 days and then administering a single dose of ethanol (5 g/kg body weight) via gavage. Liver and serum samples were collected. We also measured messenger RNA levels of SIRT1, SFRS10, and lipin-1β and lipin-1α in liver samples from patients with alcoholic hepatitis and individuals without alcoholic hepatitis (controls). RESULTS On the ethanol-containing diet, livers of Sirt1LKO mice accumulated larger amounts of hepatic lipid and expressed higher levels of inflammatory cytokines than control mice; serum of Sirt1LKO mice had increased levels of alanine aminotransferase and aspartate aminotransferase. Hepatic deletion of SIRT1 exacerbated ethanol-mediated defects in lipid metabolism, mainly by altering the function of lipin-1, a transcriptional regulator of lipid metabolism. In cultured mouse AML-12 hepatocytes, transgenic expression of SIRT1 prevented fat accumulation in response to ethanol exposure, largely by reversing the aberrations in lipin-1 signaling induced by ethanol. Liver samples from patients with alcoholic hepatitis had reduced levels of SIRT1 and a higher ratio of Lpin1β/α messenger RNAs than controls. CONCLUSIONS In mice, hepatic deletion of Sirt1 promotes steatosis, inflammation, and fibrosis in response to ethanol challenge. Ethanol-mediated impairment of hepatic SIRT1 signaling via lipin-1 contributes to development of alcoholic steatosis and inflammation. Reagents designed to increase SIRT1 regulation of lipin-1 can be developed to treat patients with alcoholic fatty liver disease.
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Affiliation(s)
- Huquan Yin
- Department of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, 12901 Bruce B. Downs Blvd. Tampa, FL 33612 , USA
| | - Ming Hu
- Department of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, 12901 Bruce B. Downs Blvd. Tampa, FL 33612 , USA
| | - Xiaomei Liang
- Department of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, 12901 Bruce B. Downs Blvd. Tampa, FL 33612 , USA
| | - Joanne M. Ajmo
- Department of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, 12901 Bruce B. Downs Blvd. Tampa, FL 33612 , USA
| | - Xiaoling Li
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Ramon Bataller
- Departments of Medicine and Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Gemma Odena
- Departments of Medicine and Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Stanley M. Stevens
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Flowler Ave. Tampa FL, 33620, USA
| | - Min You
- Department of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida.
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74
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Pascual F, Hsieh LS, Soto-Cardalda A, Carman GM. Yeast Pah1p phosphatidate phosphatase is regulated by proteasome-mediated degradation. J Biol Chem 2014; 289:9811-22. [PMID: 24563465 DOI: 10.1074/jbc.m114.550103] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yeast PAH1-encoded phosphatidate phosphatase is the enzyme responsible for the production of the diacylglycerol used for the synthesis of triacylglycerol that accumulates in the stationary phase of growth. Paradoxically, the growth phase-mediated inductions of PAH1 and phosphatidate phosphatase activity do not correlate with the amount of Pah1p; enzyme abundance declined in a growth phase-dependent manner. Pah1p from exponential phase cells was a relatively stable protein, and its abundance was not affected by incubation with an extract from stationary phase cells. Recombinant Pah1p was degraded upon incubation with the 100,000 × g pellet fraction of stationary phase cells, although the enzyme was stable when incubated with the same fraction of exponential phase cells. MG132, an inhibitor of proteasome function, prevented degradation of the recombinant enzyme. Endogenously expressed and plasmid-mediated overexpressed levels of Pah1p were more abundant in the stationary phase of cells treated with MG132. Pah1p was stabilized in mutants with impaired proteasome (rpn4Δ, blm10Δ, ump1Δ, and pre1 pre2) and ubiquitination (hrd1Δ, ubc4Δ, ubc7Δ, ubc8Δ, and doa4Δ) functions. The pre1 pre2 mutations that eliminate nearly all chymotrypsin-like activity of the 20 S proteasome had the greatest stabilizing effect on enzyme levels. Taken together, these results supported the conclusion that Pah1p is subject to proteasome-mediated degradation in the stationary phase. That Pah1p abundance was stabilized in pah1Δ mutant cells expressing catalytically inactive forms of Pah1p and dgk1Δ mutant cells with induced expression of DGK1-encoded diacylglycerol kinase indicated that alteration in phosphatidate and/or diacylglycerol levels might be the signal that triggers Pah1p degradation.
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Affiliation(s)
- Florencia Pascual
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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75
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Kok BPC, Skene-Arnold TD, Ling J, Benesch MGK, Dewald J, Harris TE, Holmes CFB, Brindley DN. Conserved residues in the N terminus of lipin-1 are required for binding to protein phosphatase-1c, nuclear translocation, and phosphatidate phosphatase activity. J Biol Chem 2014; 289:10876-10886. [PMID: 24558042 DOI: 10.1074/jbc.m114.552612] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipin-1 is a phosphatidate phosphatase in glycerolipid biosynthesis and signal transduction. It also serves as a transcriptional co-regulator to control lipid metabolism and adipogenesis. These functions are controlled partly by its subcellular distribution. Hyperphosphorylated lipin-1 remains sequestered in the cytosol, whereas hypophosphorylated lipin-1 translocates to the endoplasmic reticulum and nucleus. The serine/threonine protein phosphatase-1 catalytic subunit (PP-1c) is a major protein dephosphorylation enzyme. Its activity is controlled by interactions with different regulatory proteins, many of which contain conserved RVXF binding motifs. We found that lipin-1 binds to PP-1cγ through a similar HVRF binding motif. This interaction depends on Mg(2+) or Mn(2+) and is competitively inhibited by (R/H)VXF-containing peptides. Mutating the HVRF motif in the highly conserved N terminus of lipin-1 greatly decreases PP-1cγ interaction. Moreover, mutations of other residues in the N terminus of lipin-1 also modulate PP-1cγ binding. PP-1cγ binds poorly to a phosphomimetic mutant of lipin-1 and binds well to the non-phosphorylatable lipin-1 mutant. This indicates that lipin-1 is dephosphorylated before PP-1cγ binds to its HVRF motif. Importantly, mutating the HVRF motif also abrogates the nuclear translocation and phosphatidate phosphatase activity of lipin-1. In conclusion, we provide novel evidence of the importance of the lipin-1 N-terminal domain for its catalytic activity, nuclear localization, and binding to PP-1cγ.
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Affiliation(s)
- Bernard P C Kok
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Tamara D Skene-Arnold
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Ji Ling
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Matthew G K Benesch
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Jay Dewald
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Thurl E Harris
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesvillle, Virginia 22908
| | - Charles F B Holmes
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - David N Brindley
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
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76
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Formation and regulation of mitochondrial membranes. Int J Cell Biol 2014; 2014:709828. [PMID: 24578708 PMCID: PMC3918842 DOI: 10.1155/2014/709828] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/04/2013] [Accepted: 11/05/2013] [Indexed: 01/09/2023] Open
Abstract
Mitochondrial membrane phospholipids are essential for the mitochondrial architecture, the activity of respiratory proteins, and the transport of proteins into the mitochondria. The accumulation of phospholipids within mitochondria depends on a coordinate synthesis, degradation, and trafficking of phospholipids between the endoplasmic reticulum (ER) and mitochondria as well as intramitochondrial lipid trafficking. Several studies highlight the contribution of dietary fatty acids to the remodeling of phospholipids and mitochondrial membrane homeostasis. Understanding the role of phospholipids in the mitochondrial membrane and their metabolism will shed light on the molecular mechanisms involved in the regulation of mitochondrial function and in the mitochondrial-related diseases.
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77
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The response to inositol: regulation of glycerolipid metabolism and stress response signaling in yeast. Chem Phys Lipids 2014; 180:23-43. [PMID: 24418527 DOI: 10.1016/j.chemphyslip.2013.12.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 12/26/2013] [Indexed: 12/13/2022]
Abstract
This article focuses on discoveries of the mechanisms governing the regulation of glycerolipid metabolism and stress response signaling in response to the phospholipid precursor, inositol. The regulation of glycerolipid lipid metabolism in yeast in response to inositol is highly complex, but increasingly well understood, and the roles of individual lipids in stress response are also increasingly well characterized. Discoveries that have emerged over several decades of genetic, molecular and biochemical analyses of metabolic, regulatory and signaling responses of yeast cells, both mutant and wild type, to the availability of the phospholipid precursor, inositol are discussed.
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78
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Sembongi H, Miranda M, Han GS, Fakas S, Grimsey N, Vendrell J, Carman GM, Siniossoglou S. Distinct roles of the phosphatidate phosphatases lipin 1 and 2 during adipogenesis and lipid droplet biogenesis in 3T3-L1 cells. J Biol Chem 2013; 288:34502-13. [PMID: 24133206 PMCID: PMC3843065 DOI: 10.1074/jbc.m113.488445] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 10/04/2013] [Indexed: 11/06/2022] Open
Abstract
Lipins are evolutionarily conserved Mg(2+)-dependent phosphatidate phosphatase (PAP) enzymes with essential roles in lipid biosynthesis. Mammals express three paralogues: lipins 1, 2, and 3. Loss of lipin 1 in mice inhibits adipogenesis at an early stage of differentiation and results in a lipodystrophic phenotype. The role of lipins at later stages of adipogenesis, when cells initiate the formation of lipid droplets, is less well characterized. We found that depletion of lipin 1, after the initiation of differentiation in 3T3-L1 cells but before the loading of lipid droplets with triacylglycerol, results in a reciprocal increase of lipin 2, but not lipin 3. We generated 3T3-L1 cells where total lipin protein and PAP activity levels are down-regulated by the combined depletion of lipins 1 and 2 at day 4 of differentiation. These cells still accumulated triacylglycerol but displayed a striking fragmentation of lipid droplets without significantly affecting their total volume per cell. This was due to the lack of the PAP activity of lipin 1 in adipocytes after day 4 of differentiation, whereas depletion of lipin 2 led to an increase of lipid droplet volume per cell. We propose that in addition to their roles during early adipogenesis, lipins also have a role in lipid droplet biogenesis.
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Affiliation(s)
- Hiroshi Sembongi
- From the Cambridge Institute for Medical Research, University of Cambridge, CB2 0XY Cambridge, United Kingdom
| | - Merce Miranda
- the Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, Institut d'Investigació Pere Virgili, Universitat Rovira i Virgili, Hospital Universitari Joan XXIII, Tarragona, Spain, and
| | - Gil-Soo Han
- the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Stylianos Fakas
- the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Neil Grimsey
- From the Cambridge Institute for Medical Research, University of Cambridge, CB2 0XY Cambridge, United Kingdom
| | - Joan Vendrell
- the Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, Institut d'Investigació Pere Virgili, Universitat Rovira i Virgili, Hospital Universitari Joan XXIII, Tarragona, Spain, and
| | - George M. Carman
- the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Symeon Siniossoglou
- From the Cambridge Institute for Medical Research, University of Cambridge, CB2 0XY Cambridge, United Kingdom
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79
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Pascual F, Soto-Cardalda A, Carman GM. PAH1-encoded phosphatidate phosphatase plays a role in the growth phase- and inositol-mediated regulation of lipid synthesis in Saccharomyces cerevisiae. J Biol Chem 2013; 288:35781-92. [PMID: 24196957 DOI: 10.1074/jbc.m113.525766] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, the synthesis of phospholipids in the exponential phase of growth occurs at the expense of the storage lipid triacylglycerol. As exponential phase cells progress into the stationary phase, the synthesis of triacylglycerol occurs at the expense of phospholipids. Early work indicates a role of the phosphatidate phosphatase (PAP) in this metabolism; the enzyme produces the diacylglycerol needed for the synthesis of triacylglycerol and simultaneously controls the level of phosphatidate for the synthesis of phospholipids. Four genes (APP1, DPP1, LPP1, and PAH1) encode PAP activity in yeast, and it has been unclear which gene is responsible for the synthesis of triacylglycerol throughout growth. An analysis of lipid synthesis and composition, as well as PAP activity in various PAP mutant strains, showed the essential role of PAH1 in triacylglycerol synthesis throughout growth. Pah1p is a phosphorylated enzyme whose in vivo function is dependent on its dephosphorylation by the Nem1p-Spo7p protein phosphatase complex. nem1Δ mutant cells exhibited defects in triacylglycerol synthesis and lipid metabolism that mirrored those imparted by the pah1Δ mutation, substantiating the importance of Pah1p dephosphorylation throughout growth. An analysis of cells bearing PPAH1-lacZ and PPAH1-DPP1 reporter genes showed that PAH1 expression was induced throughout growth and that the induction in the stationary phase was stimulated by inositol supplementation. A mutant analysis indicated that the Ino2p/Ino4p/Opi1p regulatory circuit and transcription factors Gis1p and Rph1p mediated this regulation.
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Affiliation(s)
- Florencia Pascual
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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80
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Michot C, Mamoune A, Vamecq J, Viou MT, Hsieh LS, Testet E, Lainé J, Hubert L, Dessein AF, Fontaine M, Ottolenghi C, Fouillen L, Nadra K, Blanc E, Bastin J, Candon S, Pende M, Munnich A, Smahi A, Djouadi F, Carman GM, Romero N, de Keyzer Y, de Lonlay P. Combination of lipid metabolism alterations and their sensitivity to inflammatory cytokines in human lipin-1-deficient myoblasts. Biochim Biophys Acta Mol Basis Dis 2013; 1832:2103-14. [PMID: 23928362 DOI: 10.1016/j.bbadis.2013.07.021] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 07/24/2013] [Accepted: 07/29/2013] [Indexed: 11/28/2022]
Abstract
Lipin-1 deficiency is associated with massive rhabdomyolysis episodes in humans, precipitated by febrile illnesses. Despite well-known roles of lipin-1 in lipid biosynthesis and transcriptional regulation, the pathogenic mechanisms leading to rhabdomyolysis remain unknown. Here we show that primary myoblasts from lipin-1-deficient patients exhibit a dramatic decrease in LPIN1 expression and phosphatidic acid phosphatase 1 activity, and a significant accumulation of lipid droplets (LD). The expression levels of LPIN1-target genes [peroxisome proliferator-activated receptors delta and alpha (PPARδ, PPARα), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), acyl-coenzyme A dehydrogenase, very long (ACADVL), carnitine palmitoyltransferase IB and 2 (CPT1B and CPT2)] were not affected while lipin-2 protein level, a closely related member of the family, was increased. Microarray analysis of patients' myotubes identified 19 down-regulated and 51 up-regulated genes, indicating pleiotropic effects of lipin-1 deficiency. Special attention was paid to the up-regulated ACACB (acetyl-CoA carboxylase beta), a key enzyme in the fatty acid synthesis/oxidation balance. We demonstrated that overexpression of ACACB was associated with free fatty acid accumulation in patients' myoblasts whereas malonyl-carnitine (as a measure of malonyl-CoA) and CPT1 activity were in the normal range in basal conditions accordingly to the normal daily activity reported by the patients. Remarkably ACACB invalidation in patients' myoblasts decreased LD number and size while LPIN1 invalidation in controls induced LD accumulation. Further, pro-inflammatory treatments tumor necrosis factor alpha+Interleukin-1beta(TNF1α+IL-1ß) designed to mimic febrile illness, resulted in increased malonyl-carnitine levels, reduced CPT1 activity and enhanced LD accumulation, a phenomenon reversed by dexamethasone and TNFα or IL-1ß inhibitors. Our data suggest that the pathogenic mechanism of rhabdomyolysis in lipin-1-deficient patients combines the predisposing constitutive impairment of lipid metabolism and its exacerbation by pro-inflammatory cytokines.
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Affiliation(s)
- Caroline Michot
- Inserm U781, Imagine Institut des Maladies Génétiques, Université Paris Descartes et Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker, AP-HP, Paris, France
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81
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Lipid droplets and peroxisomes: key players in cellular lipid homeostasis or a matter of fat--store 'em up or burn 'em down. Genetics 2013; 193:1-50. [PMID: 23275493 PMCID: PMC3527239 DOI: 10.1534/genetics.112.143362] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Lipid droplets (LDs) and peroxisomes are central players in cellular lipid homeostasis: some of their main functions are to control the metabolic flux and availability of fatty acids (LDs and peroxisomes) as well as of sterols (LDs). Both fatty acids and sterols serve multiple functions in the cell—as membrane stabilizers affecting membrane fluidity, as crucial structural elements of membrane-forming phospholipids and sphingolipids, as protein modifiers and signaling molecules, and last but not least, as a rich carbon and energy source. In addition, peroxisomes harbor enzymes of the malic acid shunt, which is indispensable to regenerate oxaloacetate for gluconeogenesis, thus allowing yeast cells to generate sugars from fatty acids or nonfermentable carbon sources. Therefore, failure of LD and peroxisome biogenesis and function are likely to lead to deregulated lipid fluxes and disrupted energy homeostasis with detrimental consequences for the cell. These pathological consequences of LD and peroxisome failure have indeed sparked great biomedical interest in understanding the biogenesis of these organelles, their functional roles in lipid homeostasis, interaction with cellular metabolism and other organelles, as well as their regulation, turnover, and inheritance. These questions are particularly burning in view of the pandemic development of lipid-associated disorders worldwide.
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82
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Lipins, lipinopathies, and the modulation of cellular lipid storage and signaling. Prog Lipid Res 2013; 52:305-16. [PMID: 23603613 DOI: 10.1016/j.plipres.2013.04.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 03/29/2013] [Accepted: 04/04/2013] [Indexed: 01/13/2023]
Abstract
Members of the lipin protein family are phosphatidate phosphatase (PAP) enzymes, which catalyze the dephosphorylation of phosphatidic acid to diacylglycerol, the penultimate step in TAG synthesis. Lipins are unique among the glycerolipid biosynthetic enzymes in that they also promote fatty acid oxidation through their activity as co-regulators of gene expression by DNA-bound transcription factors. Lipin function has been evolutionarily conserved from a single ortholog in yeast to the mammalian family of three lipin proteins-lipin-1, lipin-2, and lipin-3. In mice and humans, the levels of lipin activity are a determinant of TAG storage in diverse cell types, and humans with deficiency in lipin-1 or lipin-2 have severe metabolic diseases. Recent work has highlighted the complex physiological interactions between members of the lipin protein family, which exhibit both overlapping and unique functions in specific tissues. The analysis of "lipinopathies" in mouse models and in humans has revealed an important role for lipin activity in the regulation of lipid intermediates (phosphatidate and diacylglycerol), which influence fundamental cellular processes including adipocyte and nerve cell differentiation, adipocyte lipolysis, and hepatic insulin signaling. The elucidation of lipin molecular and physiological functions could lead to novel approaches to modulate cellular lipid storage and metabolic disease.
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83
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Kok BPC, Dyck JRB, Harris TE, Brindley DN. Differential regulation of the expressions of the PGC-1α splice variants, lipins, and PPARα in heart compared to liver. J Lipid Res 2013; 54:1662-1677. [PMID: 23505321 DOI: 10.1194/jlr.m036624] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Peroxisome proliferator-activated receptor α (PPARα) and PPARγ coactivator 1α (PGC-1α) are crucial transcriptional regulators for genes involved in FA oxidation. Lipin-1 is essential for this increased capacity for β-oxidation in fasted livers, and it is also a phosphatidate phosphatase involved in triacylglycerol and phospholipid synthesis. Little is known about the regulation of these proteins in the heart during fasting, where there is increased FA esterification and oxidation. Lipin-1, lipin-2, lipin-3, carnitine palmitoyltransferase-1b (Cpt1b), and PGC-1α-b mRNA were increased by glucocorticoids and cAMP in neonatal rat cardiomyocytes. However, Cpt1b upregulation was caused by increased PPARα activation rather than expression. By contrast, the effects of PPARα in fasted livers are mediated through increased expression. During fasting, the expressions of PGC-1α-b and PGC-1α-c are increased in mouse hearts, and this is explained by increased cAMP-dependent signaling. By contrast, PGC-1α-a expression is increased in liver. Contrary to our expectations, lipin-1 expression was decreased and lipin-2 remained unchanged in hearts compared with increases in fasted livers. Our results identify novel differences in the regulation of lipins, PPARα, and PGC-1α splice variants during fasting in heart versus liver, even though the ultimate outcome in both tissues is to increase FA turnover and oxidation.
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Affiliation(s)
- Bernard P C Kok
- Signal Transduction Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Jason R B Dyck
- Department of Biochemistry, and Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada; Department of Pediatrics, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Thurl E Harris
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia
| | - David N Brindley
- Signal Transduction Research Group, University of Alberta, Edmonton, Alberta, Canada; Department of Pediatrics, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada.
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84
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Gaveglio VL, Pasquaré SJ, Giusto NM. Phosphatidic acid metabolism in rat liver cell nuclei. FEBS Lett 2013; 587:950-6. [DOI: 10.1016/j.febslet.2013.01.074] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 11/22/2012] [Accepted: 01/02/2013] [Indexed: 11/28/2022]
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85
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Eaton JM, Mullins GR, Brindley DN, Harris TE. Phosphorylation of lipin 1 and charge on the phosphatidic acid head group control its phosphatidic acid phosphatase activity and membrane association. J Biol Chem 2013; 288:9933-9945. [PMID: 23426360 DOI: 10.1074/jbc.m112.441493] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The lipin gene family encodes a class of Mg(2+)-dependent phosphatidic acid phosphatases involved in the de novo synthesis of phospholipids and triglycerides. Unlike other enzymes in the Kennedy pathway, lipins are not integral membrane proteins, and they need to translocate from the cytosol to intracellular membranes to participate in glycerolipid synthesis. The movement of lipin 1 within the cell is closely associated with its phosphorylation status. Although cellular analyses have demonstrated that highly phosphorylated lipin 1 is enriched in the cytosol and dephosphorylated lipin 1 is found on membranes, the effects of phosphorylation on lipin 1 activity and binding to membranes has not been recapitulated in vitro. Herein we describe a new biochemical assay for lipin 1 using mixtures of phosphatidic acid (PA) and phosphatidylethanolamine that reflects its physiological activity and membrane interaction. This depends on our observation that lipin 1 binding to PA in membranes is highly responsive to the electrostatic charge of PA. The studies presented here demonstrate that phosphorylation regulates the ability of the polybasic domain of lipin 1 to recognize di-anionic PA and identify mTOR as a crucial upstream signaling component regulating lipin 1 phosphorylation. These results demonstrate how phosphorylation of lipin 1 together with pH and membrane phospholipid composition play important roles in the membrane association of lipin 1 and thus the regulation of its enzymatic activity.
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Affiliation(s)
- James M Eaton
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Garrett R Mullins
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - David N Brindley
- Signal Transduction Research Group, Department of Biochemistry, University of Alberta, Edmonton T6G 2S2, Canada
| | - Thurl E Harris
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908.
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86
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Li S, Chen W, Kang X, Han R, Sun G, Huang Y. Distinct tissue expression profiles of chicken Lpin1-α/β isoforms and the effect of the variation on muscle fiber traits. Gene 2013; 515:281-90. [PMID: 23266642 DOI: 10.1016/j.gene.2012.11.075] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 10/14/2012] [Accepted: 11/27/2012] [Indexed: 11/17/2022]
Affiliation(s)
- Suya Li
- College of Life Sciences, Henan Agricultural University, Zhengzhou 450002, Henan, China
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87
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Kelemen O, Convertini P, Zhang Z, Wen Y, Shen M, Falaleeva M, Stamm S. Function of alternative splicing. Gene 2013; 514:1-30. [PMID: 22909801 PMCID: PMC5632952 DOI: 10.1016/j.gene.2012.07.083] [Citation(s) in RCA: 514] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 12/15/2022]
Abstract
Almost all polymerase II transcripts undergo alternative pre-mRNA splicing. Here, we review the functions of alternative splicing events that have been experimentally determined. The overall function of alternative splicing is to increase the diversity of mRNAs expressed from the genome. Alternative splicing changes proteins encoded by mRNAs, which has profound functional effects. Experimental analysis of these protein isoforms showed that alternative splicing regulates binding between proteins, between proteins and nucleic acids as well as between proteins and membranes. Alternative splicing regulates the localization of proteins, their enzymatic properties and their interaction with ligands. In most cases, changes caused by individual splicing isoforms are small. However, cells typically coordinate numerous changes in 'splicing programs', which can have strong effects on cell proliferation, cell survival and properties of the nervous system. Due to its widespread usage and molecular versatility, alternative splicing emerges as a central element in gene regulation that interferes with almost every biological function analyzed.
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Affiliation(s)
- Olga Kelemen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Paolo Convertini
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhaiyi Zhang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Yuan Wen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Manli Shen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Marina Falaleeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Stefan Stamm
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
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88
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Comba S, Menendez-Bravo S, Arabolaza A, Gramajo H. Identification and physiological characterization of phosphatidic acid phosphatase enzymes involved in triacylglycerol biosynthesis in Streptomyces coelicolor. Microb Cell Fact 2013; 12:9. [PMID: 23356794 PMCID: PMC3599759 DOI: 10.1186/1475-2859-12-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 01/20/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Phosphatidic acid phosphatase (PAP, EC 3.1.3.4) catalyzes the dephosphorylation of phosphatidate yielding diacylglycerol (DAG), the lipid precursor for triacylglycerol (TAG) biosynthesis. Despite the importance of PAP activity in TAG producing bacteria, studies to establish its role in lipid metabolism have been so far restricted only to eukaryotes. Considering the increasing interest of bacterial TAG as a potential source of raw material for biofuel production, we have focused our studies on the identification and physiological characterization of the putative PAP present in the TAG producing bacterium Streptomyces coelicolor. RESULTS We have identified two S. coelicolor genes, named lppα (SCO1102) and lppβ (SCO1753), encoding for functional PAP proteins. Both enzymes mediate, at least in part, the formation of DAG for neutral lipid biosynthesis. Heterologous expression of lppα and lppβ genes in E. coli resulted in enhanced PAP activity in the membrane fractions of the recombinant strains and concomitantly in higher levels of DAG. In addition, the expression of these genes in yeast complemented the temperature-sensitive growth phenotype of the PAP deficient strain GHY58 (dpp1lpp1pah1). In S. coelicolor, disruption of either lppα or lppβ had no effect on TAG accumulation; however, the simultaneous mutation of both genes provoked a drastic reduction in de novo TAG biosynthesis as well as in total TAG content. Consistently, overexpression of Lppα and Lppβ in the wild type strain of S. coelicolor led to a significant increase in TAG production. CONCLUSIONS The present study describes the identification of PAP enzymes in bacteria and provides further insights on the genetic basis for prokaryotic oiliness. Furthermore, this finding completes the whole set of enzymes required for de novo TAG biosynthesis pathway in S. coelicolor. Remarkably, the overexpression of these PAPs in Streptomyces bacteria contributes to a higher productivity of this single cell oil. Altogether, these results provide new elements and tools for future cell engineering for next-generation biofuels production.
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Affiliation(s)
- Santiago Comba
- Microbiology Division, IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK, Rosario, Argentina
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89
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Chae M, Carman GM. Characterization of the yeast actin patch protein App1p phosphatidate phosphatase. J Biol Chem 2013; 288:6427-37. [PMID: 23335564 DOI: 10.1074/jbc.m112.449629] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yeast App1p is a phosphatidate phosphatase (PAP) that associates with endocytic proteins at cortical actin patches. App1p, which catalyzes the conversion of phosphatidate (PA) to diacylglycerol, is unique among Mg(2+)-dependent PAP enzymes in that its reaction is not involved with de novo lipid synthesis. Instead, App1p PAP is thought to play a role in endocytosis because its substrate and product facilitate membrane fission/fusion events and regulate enzymes that govern vesicular movement. App1p PAP was purified from yeast and characterized with respect to its enzymological, kinetic, and regulatory properties. Maximum PAP activity was dependent on Triton X-100 (20 mm), PA (2 mm), Mg(2+) (0.5 mm), and 2-mercaptoethanol (10 mm) at pH 7.5 and 30 °C. Analysis of surface dilution kinetics with Triton X-100/PA-mixed micelles yielded constants for surface binding (Ks(A) = 11 mm), interfacial PA binding (Km(B) = 4.2 mol %), and catalytic efficiency (Vmax = 557 μmol/min/mg). The activation energy, turnover number, and equilibrium constant were 16.5 kcal/mol, 406 s(-1), and 16.2, respectively. PAP activity was stimulated by anionic lipids (cardiolipin, phosphatidylglycerol, phosphatidylserine, and CDP-diacylglycerol) and inhibited by zwitterionic (phosphatidylcholine and phosphatidylethanolamine) and cationic (sphinganine) lipids, nucleotides (ATP and CTP), N-ethylmaleimide, propranolol, phenylglyoxal, and divalent cations (Ca(2+), Mn(2+), and Zn(2+)). App1p also utilized diacylglycerol pyrophosphate and lyso-PA as substrates with specificity constants 4- and 7-fold lower, respectively, when compared with PA.
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Affiliation(s)
- Minjung Chae
- Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901, USA
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90
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Everitt H, Hu M, Ajmo JM, Rogers CQ, Liang X, Zhang R, Yin H, Choi A, Bennett ES, You M. Ethanol administration exacerbates the abnormalities in hepatic lipid oxidation in genetically obese mice. Am J Physiol Gastrointest Liver Physiol 2013; 304:G38-47. [PMID: 23139221 PMCID: PMC3543633 DOI: 10.1152/ajpgi.00309.2012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Alcohol consumption synergistically increases the risk and severity of liver damage in obese patients. To gain insight into cellular or molecular mechanisms underlying the development of fatty liver caused by ethanol-obesity synergism, we have carried out animal experiments that examine the effects of ethanol administration in genetically obese mice. Lean wild-type (WT) and obese (ob/ob) mice were subjected to ethanol feeding for 4 wk using a modified Lieber-DeCarli diet. After ethanol feeding, the ob/ob mice displayed much more pronounced changes in terms of liver steatosis and elevated plasma levels of alanine aminotransferase and aspartate aminotransferase, indicators of liver injury, compared with control mice. Mechanistic studies showed that ethanol feeding augmented the impairment of hepatic sirtuin 1 (SIRT1)-AMP-activated kinase (AMPK) signaling in the ob/ob mice. Moreover, the impairment of SIRT1-AMPK signaling was closely associated with altered hepatic functional activity of peroxisome proliferator-activated receptor γ coactivator-α and lipin-1, two vital downstream lipid regulators, which ultimately contributed to aggravated fatty liver observed in ethanol-fed ob/ob mice. Taken together, our novel findings suggest that ethanol administration to obese mice exacerbates fatty liver via impairment of the hepatic lipid metabolism pathways mediated largely by a central signaling system, the SIRT1-AMPK axis.
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Affiliation(s)
- Hannah Everitt
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida
| | - Ming Hu
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida
| | - Joanne M. Ajmo
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida
| | - Christopher Q. Rogers
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida
| | - Xiaomei Liang
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida
| | - Ray Zhang
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida
| | - Huquan Yin
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida
| | - Alison Choi
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida
| | - Eric S. Bennett
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida
| | - Min You
- Departments of Molecular Pharmacology and Physiology, University of South Florida Health Sciences Center, Tampa, Florida
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91
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Chae M, Han GS, Carman GM. The Saccharomyces cerevisiae actin patch protein App1p is a phosphatidate phosphatase enzyme. J Biol Chem 2012; 287:40186-96. [PMID: 23071111 PMCID: PMC3504732 DOI: 10.1074/jbc.m112.421776] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 10/11/2012] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Phosphatidate phosphatase (PAP) plays diverse roles in lipid metabolism and cell signaling. RESULTS A novel yeast PAP is identified as the actin patch protein encoded by APP1. CONCLUSION APP1 and other known genes (PAH1, DPP1, LPP1) are responsible for all detectable PAP activity in yeast. SIGNIFICANCE Identification of App1p as a PAP enzyme will facilitate the understanding of its cellular function. Phosphatidate phosphatase (PAP) catalyzes the dephosphorylation of phosphatidate to yield diacylglycerol. In the yeast Saccharomyces cerevisiae, PAP is encoded by PAH1, DPP1, and LPP1. The presence of PAP activity in the pah1Δ dpp1Δ lpp1Δ triple mutant indicated another gene(s) encoding the enzyme. We purified PAP from the pah1Δ dpp1Δ lpp1Δ triple mutant by salt extraction of mitochondria followed by chromatography with DE52, Affi-Gel Blue, phenyl-Sepharose, MonoQ, and Superdex 200. Liquid chromatography/tandem mass spectrometry analysis of a PAP-enriched sample revealed multiple putative phosphatases. By analysis of PAP activity in mutants lacking each of the proteins, we found that APP1, a gene whose molecular function has been unknown, confers ~30% PAP activity of wild type cells. The overexpression of APP1 in the pah1Δ dpp1Δ lpp1Δ mutant exhibited a 10-fold increase in PAP activity. The PAP activity shown by App1p heterologously expressed in Escherichia coli confirmed that APP1 is the structural gene for the enzyme. Introduction of the app1Δ mutation into the pah1Δ dpp1Δ lpp1Δ triple mutant resulted in a complete loss of PAP activity, indicating that distinct PAP enzymes in S. cerevisiae are encoded by APP1, PAH1, DPP1, and LPP1. Lipid analysis of cells lacking the PAP genes, singly or in combination, showed that Pah1p is the only PAP involved in the synthesis of triacylglycerol as well as in the regulation of phospholipid synthesis. App1p, which shows interactions with endocytic proteins, may play a role in vesicular trafficking through its PAP activity.
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Affiliation(s)
- Minjung Chae
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - George M. Carman
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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92
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Michot C, Hubert L, Romero NB, Gouda A, Mamoune A, Mathew S, Kirk E, Viollet L, Rahman S, Bekri S, Peters H, McGill J, Glamuzina E, Farrar M, von der Hagen M, Alexander IE, Kirmse B, Barth M, Laforet P, Benlian P, Munnich A, JeanPierre M, Elpeleg O, Pines O, Delahodde A, de Keyzer Y, de Lonlay P. Study of LPIN1, LPIN2 and LPIN3 in rhabdomyolysis and exercise-induced myalgia. J Inherit Metab Dis 2012; 35:1119-28. [PMID: 22481384 DOI: 10.1007/s10545-012-9461-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 01/19/2012] [Accepted: 01/30/2012] [Indexed: 01/21/2023]
Abstract
BACKGROUND Recessive LPIN1 mutations were identified as a cause of severe rhabdomyolysis in pediatric patients. The human lipin family includes two other closely related members, lipin-2 and 3, which share strong homology and similar activity. The study aimed to determine the involvement of the LPIN family genes in a cohort of pediatric and adult patients (n = 171) presenting with muscular symptoms, ranging from severe (CK >10 000 UI/L) or moderate (CK <10 000 UI/L) rhabdomyolysis (n = 141) to exercise-induced myalgia (n = 30), and to report the clinical findings in patients harboring mutations. METHODS Coding regions of LPIN1, LPIN2 and LPIN3 genes were sequenced using genomic or complementary DNAs. RESULTS Eighteen patients harbored two LPIN1 mutations, including a frequent intragenic deletion. All presented with severe episodes of rhabdomyolysis, starting before age 6 years except two (8 and 42 years). Few patients also suffered from permanent muscle symptoms, including the eldest ones (≥ 40 years). Around 3/4 of muscle biopsies showed accumulation of lipid droplets. At least 40% of heterozygous relatives presented muscular myalgia. Nine heterozygous SNPs in LPIN family genes were identified in milder phenotypes (mild rhabdomyolysis or myalgia). These variants were non-functional in yeast complementation assay based on respiratory activity, except the LPIN3-P24L variant. CONCLUSION LPIN1-related myolysis constitutes a major cause of early-onset rhabdomyolysis and occasionally in adults. Heterozygous LPIN1 mutations may cause mild muscular symptoms. No major defects of LPIN2 or LPIN3 genes were associated with muscular manifestations.
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Affiliation(s)
- Caroline Michot
- Paris Descartes University, INSERM U781 and Reference Center of Metabolic Diseases, Necker Hospital, Paris, France
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93
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Perrone CE, Mattocks DAL, Plummer JD, Chittur SV, Mohney R, Vignola K, Orentreich DS, Orentreich N. Genomic and metabolic responses to methionine-restricted and methionine-restricted, cysteine-supplemented diets in Fischer 344 rat inguinal adipose tissue, liver and quadriceps muscle. JOURNAL OF NUTRIGENETICS AND NUTRIGENOMICS 2012; 5:132-57. [PMID: 23052097 DOI: 10.1159/000339347] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 05/04/2012] [Indexed: 01/26/2023]
Abstract
BACKGROUND/AIMS Methionine restriction (MR) is a dietary intervention that increases lifespan, reduces adiposity and improves insulin sensitivity. These effects are reversed by supplementation of the MR diet with cysteine (MRC). Genomic and metabolomic studies were conducted to identify potential mechanisms by which MR induces favorable metabolic effects, and that are reversed by cysteine supplementation. METHODS Gene expression was examined by microarray analysis and TaqMan quantitative PCR. Levels of selected proteins were measured by Western blot and metabolic intermediates were analyzed by mass spectrometry. RESULTS MR increased lipid metabolism in inguinal adipose tissue and quadriceps muscle while it decreased lipid synthesis in liver. In inguinal adipose tissue, MR not only caused the transcriptional upregulation of genes associated with fatty acid synthesis but also of Lpin1, Pc, Pck1 and Pdk1, genes that are associated with glyceroneogenesis. MR also upregulated lipolysis-associated genes in inguinal fat and led to increased oxidation in this tissue, as suggested by higher levels of methionine sulfoxide and 13-HODE + 9-HODE compared to control-fed (CF) rats. Moreover, MR caused a trend toward the downregulation of inflammation-associated genes in inguinal adipose tissue. MRC reversed most gene and metabolite changes induced by MR in inguinal adipose tissue, but drove the expression of Elovl6, Lpin1, Pc, and Pdk1 below CF levels. In liver, MR decreased levels of a number of long-chain fatty acids, glycerol and glycerol-3-phosphate corresponding with the gene expression data. Although MR increased the expression of genes associated with carbohydrate metabolism, levels of glycolytic intermediates were below CF levels. MR, however, stimulated gluconeogenesis and ketogenesis in liver tissue. As previously reported, sulfur amino acids derived from methionine were decreased in liver by MR, but homocysteine levels were elevated. Increased liver homocysteine levels by MR were associated with decreased cystathionine β-synthase (CBS) protein levels and lowered vitamin B6 and 5-methyltetrahydrofolate (5MeTHF) content. Finally, MR upregulated fibroblast growth factor 21 (FGF21) gene and protein levels in both liver and adipose tissues. MRC reversed some of MR's effects in liver and upregulated the transcription of genes associated with inflammation and carcinogenesis such as Cxcl16, Cdh17, Mmp12, Mybl1, and Cav1 among others. In quadriceps muscle, MR upregulated lipid metabolism-associated genes and increased 3-hydroxybutyrate levels suggesting increased fatty acid oxidation as well as stimulation of gluconeogenesis and glycogenolysis in this tissue. CONCLUSION Increased lipid metabolism in inguinal adipose tissue and quadriceps muscle, decreased triglyceride synthesis in liver and the downregulation of inflammation-associated genes are among the factors that could favor the lean phenotype and increased insulin sensitivity observed in MR rats.
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Affiliation(s)
- Carmen E Perrone
- Orentreich Foundation for the Advancement of Science, Inc, Cold Spring-on-Hudson, NY, USA.
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94
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Pascual F, Carman GM. Phosphatidate phosphatase, a key regulator of lipid homeostasis. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:514-22. [PMID: 22910056 DOI: 10.1016/j.bbalip.2012.08.006] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 08/03/2012] [Accepted: 08/06/2012] [Indexed: 10/28/2022]
Abstract
Yeast Pah1p phosphatidate phosphatase (PAP) catalyzes the penultimate step in the synthesis of triacylglycerol. PAP plays a crucial role in lipid homeostasis by controlling the relative proportions of its substrate phosphatidate and its product diacylglycerol. The cellular amounts of these lipid intermediates influence the synthesis of triacylglycerol and the pathways by which membrane phospholipids are synthesized. Physiological functions affected by PAP activity include phospholipid synthesis gene expression, nuclear/endoplasmic reticulum membrane growth, lipid droplet formation, and vacuole homeostasis and fusion. Yeast lacking Pah1p PAP activity are acutely sensitive to fatty acid-induced toxicity and exhibit respiratory deficiency. PAP is distinguished in its cellular location, catalytic mechanism, and physiological functions from Dpp1p and Lpp1p lipid phosphate phosphatases that utilize a variety of substrates that include phosphatidate. Phosphorylation/dephosphorylation is a major mechanism by which Pah1p PAP activity is regulated. Pah1p is phosphorylated by cytosolic-associated Pho85p-Pho80p, Cdc28p-cyclin B, and protein kinase A and is dephosphorylated by the endoplasmic reticulum-associated Nem1p-Spo7p phosphatase. The dephosphorylation of Pah1p stimulates PAP activity and facilitates the association with the membrane/phosphatidate allowing for its reaction and triacylglycerol synthesis. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Affiliation(s)
- Florencia Pascual
- Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA.
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95
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Kok BPC, Brindley DN. Myocardial fatty acid metabolism and lipotoxicity in the setting of insulin resistance. Heart Fail Clin 2012; 8:643-61. [PMID: 22999246 DOI: 10.1016/j.hfc.2012.06.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Management of diabetes and insulin resistance in the setting of cardiovascular disease has become an important issue in an increasingly obese society. Besides the development of hypertension and buildup of atherosclerotic plaques, the derangement of fatty acid and lipid metabolism in the heart plays an important role in promoting cardiac dysfunction and oxidative stress. This review discusses the mechanisms by which metabolic inflexibility in the use of fatty acids as the preferred cardiac substrate in diabetes produces detrimental effects on mechanical efficiency, mitochondrial function, and recovery from ischemia. Lipid accumulation and the consequences of toxic lipid metabolites are also discussed.
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Affiliation(s)
- Bernard P C Kok
- Signal Transduction Research Group, Department of Biochemistry, School of Translational Medicine, University of Alberta, 11207 87th Avenue, Edmonton, Alberta, Canada
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96
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Su WM, Han GS, Casciano J, Carman GM. Protein kinase A-mediated phosphorylation of Pah1p phosphatidate phosphatase functions in conjunction with the Pho85p-Pho80p and Cdc28p-cyclin B kinases to regulate lipid synthesis in yeast. J Biol Chem 2012; 287:33364-76. [PMID: 22865862 DOI: 10.1074/jbc.m112.402339] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Pah1p, which functions as phosphatidate phosphatase (PAP) in the yeast Saccharomyces cerevisiae, plays a crucial role in lipid homeostasis by controlling the relative proportions of its substrate phosphatidate and its product diacylglycerol. The diacylglycerol produced by PAP is used for the synthesis of triacylglycerol as well as for the synthesis of phospholipids via the Kennedy pathway. Pah1p is a highly phosphorylated protein in vivo and has been previously shown to be phosphorylated by the protein kinases Pho85p-Pho80p and Cdc28p-cyclin B. In this work, we showed that Pah1p was a bona fide substrate for protein kinase A, and we identified by mass spectrometry and mutagenesis that Ser-10, Ser-677, Ser-773, Ser-774, and Ser-788 were the target sites of phosphorylation. Protein kinase A-mediated phosphorylation of Pah1p inhibited its PAP activity by decreasing catalytic efficiency, and the inhibitory effect was primarily conferred by phosphorylation at Ser-10. Analysis of the S10A and S10D mutations (mimicking dephosphorylation and phosphorylation, respectively), alone or in combination with the seven alanine (7A) mutations of the sites phosphorylated by Pho85p-Pho80p and Cdc28p-cyclin B, indicated that phosphorylation at Ser-10 stabilized Pah1p abundance and inhibited its association with membranes, PAP activity, and triacylglycerol synthesis. The S10A mutation enhanced the physiological effects imparted by the 7A mutations, whereas the S10D mutations attenuated the effects of the 7A mutations. These data indicated that the protein kinase A-mediated phosphorylation of Ser-10 functions in conjunction with the phosphorylations mediated by Pho85p-Pho80p and Cdc28p-cyclin B and that phospho-Ser-10 should be dephosphorylated for proper PAP function.
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Affiliation(s)
- Wen-Min Su
- Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901, USA
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97
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Kok BPC, Venkatraman G, Capatos D, Brindley DN. Unlike two peas in a pod: lipid phosphate phosphatases and phosphatidate phosphatases. Chem Rev 2012; 112:5121-46. [PMID: 22742522 DOI: 10.1021/cr200433m] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Bernard P C Kok
- Signal Transduction Research Group, Department of Biochemistry, School of Translational Medicine, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
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98
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Mitochondria: signaling with phosphatidic acid. Int J Biochem Cell Biol 2012; 44:1346-50. [PMID: 22609101 DOI: 10.1016/j.biocel.2012.05.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 05/04/2012] [Accepted: 05/08/2012] [Indexed: 11/20/2022]
Abstract
Mitochondria, once viewed as functioning relatively autonomously in the cell, have increasingly been recognized to be involved in numerous signaling networks that impact on a wide range of cell biological processes. In addition to the many types of proteins that mediate these pathways, the importance of signaling functions regulated via lipids and lipid second messengers generated on the mitochondrial surface is also becoming well appreciated. We focus here on phosphatidic acid, a lipid second messenger produced via several different pathways that can in turn stimulate the formation of multiple other bioactive lipids. Taken together, fascinating roles for phosphatidic acid and the connected lipids in mitochondrial function and interaction with other organelles are being uncovered. These pathways present new opportunities for the development of therapeutic approaches relevant to reproduction, metabolism, and neurodegenerative disease.
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99
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Abstract
The gene encoding lipin 1 was identified with a positional cloning approach that localized the causative mutation in fatty liver dystrophic (fld) mice, a mouse model of lipodystrophy. The fld mouse lacks normal adipose tissue in the body, and displays metabolic dysregulation such as obesity, insulin resistance, and hypertriglyceridemia. Lipin 1 is abundantly expressed in key metabolic tissues, including adipose tissue, skeletal muscle, and liver. In the cytosol, lipin 1 acts as an Mg²⁺-dependent phosphatidate phosphatase type-1 (PAP1), catalyzing a key step in the synthesis of glycerolipids. In the nucleus, lipin 1 acts as a transcriptional coactivator through its direct interaction with peroxisome proliferator-activated receptor (PPAR) γ coactivator-1α (PGC-1α) and PPARα. Through two distinct functions in the nucleus and cytosol, lipin 1 modulates lipid metabolism and glucose homeostasis. Here we will discuss recent developments in our understanding of the role of lipin 1 in lipid metabolism.
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Affiliation(s)
- Kenji Ishimoto
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan.
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100
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Morisseau C, Schebb NH, Dong H, Ulu A, Aronov PA, Hammock BD. Role of soluble epoxide hydrolase phosphatase activity in the metabolism of lysophosphatidic acids. Biochem Biophys Res Commun 2012; 419:796-800. [PMID: 22387545 DOI: 10.1016/j.bbrc.2012.02.108] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 02/16/2012] [Indexed: 12/23/2022]
Abstract
The EPXH2 gene encodes for the soluble epoxide hydrolase (sEH), which has two distinct enzyme activities: epoxide hydrolase (Cterm-EH) and phosphatase (Nterm-phos). The Cterm-EH is involved in the metabolism of epoxides from arachidonic acid and other unsaturated fatty acids, endogenous chemical mediators that play important roles in blood pressure regulation, cell growth, inflammation and pain. While recent findings suggested complementary biological roles for Nterm-phos, its mode of action is not well understood. Herein, we demonstrate that lysophosphatidic acids are excellent substrates for Nterm-phos. We also showed that sEH phosphatase activity represents a significant (20-60%) part of LPA cellular hydrolysis, especially in the cytosol. This possible role of sEH on LPA hydrolysis could explain some of the biology previously associated with the Nterm-phos. These findings also underline possible cellular mechanisms by which both activities of sEH (EH and phosphatase) may have complementary or opposite roles.
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Affiliation(s)
- Christophe Morisseau
- Department of Entomology and UCD Cancer Center, One Shields Avenue, University of California, Davis, CA 95616, USA.
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