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Ramanadham S, Turk J, Bhatnagar S. Noncanonical Regulation of cAMP-Dependent Insulin Secretion and Its Implications in Type 2 Diabetes. Compr Physiol 2023; 13:5023-5049. [PMID: 37358504 PMCID: PMC10809800 DOI: 10.1002/cphy.c220031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
Impaired glucose tolerance (IGT) and β-cell dysfunction in insulin resistance associated with obesity lead to type 2 diabetes (T2D). Glucose-stimulated insulin secretion (GSIS) from β-cells occurs via a canonical pathway that involves glucose metabolism, ATP generation, inactivation of K ATP channels, plasma membrane depolarization, and increases in cytosolic concentrations of [Ca 2+ ] c . However, optimal insulin secretion requires amplification of GSIS by increases in cyclic adenosine monophosphate (cAMP) signaling. The cAMP effectors protein kinase A (PKA) and exchange factor activated by cyclic-AMP (Epac) regulate membrane depolarization, gene expression, and trafficking and fusion of insulin granules to the plasma membrane for amplifying GSIS. The widely recognized lipid signaling generated within β-cells by the β-isoform of Ca 2+ -independent phospholipase A 2 enzyme (iPLA 2 β) participates in cAMP-stimulated insulin secretion (cSIS). Recent work has identified the role of a G-protein coupled receptor (GPCR) activated signaling by the complement 1q like-3 (C1ql3) secreted protein in inhibiting cSIS. In the IGT state, cSIS is attenuated, and the β-cell function is reduced. Interestingly, while β-cell-specific deletion of iPLA 2 β reduces cAMP-mediated amplification of GSIS, the loss of iPLA 2 β in macrophages (MØ) confers protection against the development of glucose intolerance associated with diet-induced obesity (DIO). In this article, we discuss canonical (glucose and cAMP) and novel noncanonical (iPLA 2 β and C1ql3) pathways and how they may affect β-cell (dys)function in the context of impaired glucose intolerance associated with obesity and T2D. In conclusion, we provide a perspective that in IGT states, targeting noncanonical pathways along with canonical pathways could be a more comprehensive approach for restoring β-cell function in T2D. © 2023 American Physiological Society. Compr Physiol 13:5023-5049, 2023.
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Affiliation(s)
- Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Alabama, USA
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
| | - John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sushant Bhatnagar
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Alabama, USA
- Department of Medicine, University of Alabama at Birmingham, Alabama, USA
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Kuhlmann FM, Key PN, Hickerson SM, Turk J, Hsu FF, Beverley SM. Inositol phosphorylceramide synthase null Leishmania are viable and virulent in animal infections where salvage of host sphingomyelin predominates. J Biol Chem 2022; 298:102522. [PMID: 36162499 PMCID: PMC9637897 DOI: 10.1016/j.jbc.2022.102522] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/14/2022] [Accepted: 09/16/2022] [Indexed: 12/03/2022] Open
Abstract
Many pathogens synthesize inositol phosphorylceramide (IPC) as the major sphingolipid (SL), differing from the mammalian host where sphingomyelin (SM) or more complex SLs predominate. The divergence between IPC synthase and mammalian SL synthases has prompted interest as a potential drug target. However, in the trypanosomatid protozoan Leishmania, cultured insect stage promastigotes lack de novo SL synthesis (Δspt2-) and SLs survive and remain virulent, as infective amastigotes salvage host SLs and continue to produce IPC. To further understand the role of IPC, we generated null IPCS mutants in Leishmania major (Δipcs-). Unexpectedly and unlike fungi where IPCS is essential, Δipcs- was remarkably normal in culture and highly virulent in mouse infections. Both IPCS activity and IPC were absent in Δipcs- promastigotes and amastigotes, arguing against an alternative route of IPC synthesis. Notably, salvaged mammalian SM was highly abundant in purified amastigotes from both WT and Δipcs-, and salvaged SLs could be further metabolized into IPC. SM was about 7-fold more abundant than IPC in WT amastigotes, establishing that SM is the dominant amastigote SL, thereby rendering IPC partially redundant. These data suggest that SM salvage likely plays key roles in the survival and virulence of both WT and Δipcs- parasites in the infected host, confirmation of which will require the development of methods or mutants deficient in host SL/SM uptake in the future. Our findings call into question the suitability of IPCS as a target for chemotherapy, instead suggesting that approaches targeting SM/SL uptake or catabolism may warrant further emphasis.
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Affiliation(s)
- F. Matthew Kuhlmann
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA,Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Phillip N. Key
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Suzanne M. Hickerson
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - John Turk
- Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Fong-Fu Hsu
- Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Stephen M. Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA,For correspondence: Stephen M. Beverley
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Turk M, Gorman A, Murray K, Alammari Y, Young F, Turk J, Zahavi E, Gallagher P, Freeman L, Fearon U, Veale D. POS0462 ALCOHOL AND INFLAMMATORY ARTHRITIS DISEASE ACTIVITY: PERSPECTIVES FROM A 979-PATIENT COHORT WITH SYSTEMATIC REVIEW AND META-ANALYSIS. Ann Rheum Dis 2021. [DOI: 10.1136/annrheumdis-2021-eular.2099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Background:The effect of alcohol on disease activity in inflammatory arthritis remains poorly understood. Studies of alcohol and the incidence or risk of inflammatory arthritis are conflicting [1,2]. Alcohol does downregulate pro-inflammatory cytokines and may therefore reduce immune-mediated disease activity.Objectives:This study investigates the relationship between alcohol consumption and disease activity in our inflammatory arthritis patient cohort and performs a systematic review with meta-analysis.Methods:Cohort Study Design and data analysisPatients attending a rheumatology clinic between 2010-2020 were prospectively followed. Information on demographics, alcohol use, smoking habits, and disease outcome measures were collected. Statistical analysis included univariate and multivariate linear and binary logistic regressions, Mann Whitney-U tests, and one-way ANOVA with Tukey’s HSD.Meta-analysisEMBASE, Pubmed, the Cochrane library, and Web of Science were searched. Studies reporting on alcohol consumption and disease activity in a cohort of RA patients were included for further investigation. Forest plots were generated from 95% confidence intervals of extracted data using mean differences. Linear regression was used to determine correlations between alcohol and antibody status, gender, and smoking status.Results:Cohort StudyOf the 979 analysed patients, 62% had RA, 26.7% had PsA, and 11.2% had AS. Mean DAS28-CRP in RA and PsA at one year was 2.96 ± 1.39, and 64.2% of patients were in remission (DAS28-CRP ≤ 2.6 or BASDAI ≤ 4). Both male gender and risky drinking (>15 units of weekly alcohol) were both significantly associated with remission. Compared to women, men had an odds ratio of 1.78 [1.04, 2.52] (p=0.034) for any alcohol consumption and 6.9 [4.7, 9.1] (p=0.001) for drinking at least 15 weekly drinks. when adjusted for gender, there was no significant association between alcohol and disease activity. Yet, when adjusted for alcohol consumption, gender still influenced disease activity.Meta-analysisThe search identified 4126 citations of which 14 were included. The pooled mean difference in DAS28 (95% CI) was 0.34 (0.24,0.44) (p<10-5) between non-drinkers and drinkers, 0.33 (0.05,0.62) (p=0.02) between non-drinkers and heavy drinkers, and 0 (-0.3,0.3) (p=0.98). between low- and high-risk drinkers. There was a significant difference in the mean difference of HAQ assessments between those who drink alcohol compared to those who do not (0.3 (0.18,0.41), p<10-5). There was no significant correlation between drinking and gender, smoking status, or antibody positivity.Conclusion:While it appears that alcohol is linked to remission in inflammatory arthritis, this association is lost when adjusted for gender. Men with inflammatory arthritis drink significantly more than women and men generally have less severe disease activity. However, the meta-analysis suggests alcohol consumption is associated with lower disease activity and self-reported health assessment in rheumatoid arthritis.References:[1]Bae S-C, Lee YH. Alcohol intake and risk of rheumatoid arthritis: a Mendelian randomization study. Z Rheumatol 2019;78:791–6. doi:10.1007/s00393-018-0537-z[2]Scott IC, Tan R, Stahl D, et al. The protective effect of alcohol on developing rheumatoid arthritis: a systematic review and meta-analysis. Rheumatology (Oxford) 2013;52:856–67. doi:10.1093/rheumatology/kes376Figure 1.Mean differences in DAS28 between drinking groups. A between non-drinkers and drinkers. B between non-drinkers and high-risk drinkers. C between low-risk and high-risk drinkers.Disclosure of Interests:None declared
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Ferrara PJ, Rong X, Maschek JA, Verkerke AR, Siripoksup P, Song H, Green TD, Krishnan KC, Johnson JM, Turk J, Houmard JA, Lusis AJ, Drummond MJ, McClung JM, Cox JE, Shaikh SR, Tontonoz P, Holland WL, Funai K. Lysophospholipid acylation modulates plasma membrane lipid organization and insulin sensitivity in skeletal muscle. J Clin Invest 2021; 131:135963. [PMID: 33591957 DOI: 10.1172/jci135963] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 02/11/2021] [Indexed: 01/09/2023] Open
Abstract
Aberrant lipid metabolism promotes the development of skeletal muscle insulin resistance, but the exact identity of lipid-mediated mechanisms relevant to human obesity remains unclear. A comprehensive lipidomic analysis of primary myocytes from individuals who were insulin-sensitive and lean (LN) or insulin-resistant with obesity (OB) revealed several species of lysophospholipids (lyso-PLs) that were differentially abundant. These changes coincided with greater expression of lysophosphatidylcholine acyltransferase 3 (LPCAT3), an enzyme involved in phospholipid transacylation (Lands cycle). Strikingly, mice with skeletal muscle-specific knockout of LPCAT3 (LPCAT3-MKO) exhibited greater muscle lysophosphatidylcholine/phosphatidylcholine, concomitant with improved skeletal muscle insulin sensitivity. Conversely, skeletal muscle-specific overexpression of LPCAT3 (LPCAT3-MKI) promoted glucose intolerance. The absence of LPCAT3 reduced phospholipid packing of cellular membranes and increased plasma membrane lipid clustering, suggesting that LPCAT3 affects insulin receptor phosphorylation by modulating plasma membrane lipid organization. In conclusion, obesity accelerates the skeletal muscle Lands cycle, whose consequence might induce the disruption of plasma membrane organization that suppresses muscle insulin action.
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Affiliation(s)
- Patrick J Ferrara
- Diabetes and Metabolism Research Center and.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA.,East Carolina Diabetes and Obesity Institute and.,Human Performance Laboratory, East Carolina University, Greenville, North Carolina, USA.,Molecular Medicine Program, University of Utah, Salt Lake City, Utah, USA
| | - Xin Rong
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA
| | - J Alan Maschek
- Diabetes and Metabolism Research Center and.,Metabolomics, Mass Spectrometry, and Proteomics Core and
| | - Anthony Rp Verkerke
- Diabetes and Metabolism Research Center and.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA.,East Carolina Diabetes and Obesity Institute and.,Human Performance Laboratory, East Carolina University, Greenville, North Carolina, USA
| | - Piyarat Siripoksup
- Diabetes and Metabolism Research Center and.,Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, Utah, USA
| | - Haowei Song
- Division of Endocrinology Metabolism and Lipid Research, School of Medicine, Washington University in St. Louis, St. Louis, Missouri, USA
| | | | | | - Jordan M Johnson
- Diabetes and Metabolism Research Center and.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA.,East Carolina Diabetes and Obesity Institute and.,Human Performance Laboratory, East Carolina University, Greenville, North Carolina, USA
| | - John Turk
- Division of Endocrinology Metabolism and Lipid Research, School of Medicine, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Joseph A Houmard
- East Carolina Diabetes and Obesity Institute and.,Human Performance Laboratory, East Carolina University, Greenville, North Carolina, USA
| | - Aldons J Lusis
- Cardiology Division, Department of Medicine, UCLA, Los Angeles, California, USA
| | - Micah J Drummond
- Diabetes and Metabolism Research Center and.,Molecular Medicine Program, University of Utah, Salt Lake City, Utah, USA.,Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, Utah, USA
| | | | - James E Cox
- Diabetes and Metabolism Research Center and.,Metabolomics, Mass Spectrometry, and Proteomics Core and.,Department of Biochemistry, University of Utah, Salt Lake City, Utah, USA
| | - Saame Raza Shaikh
- East Carolina Diabetes and Obesity Institute and.,Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA
| | - William L Holland
- Diabetes and Metabolism Research Center and.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA.,Molecular Medicine Program, University of Utah, Salt Lake City, Utah, USA
| | - Katsuhiko Funai
- Diabetes and Metabolism Research Center and.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA.,East Carolina Diabetes and Obesity Institute and.,Human Performance Laboratory, East Carolina University, Greenville, North Carolina, USA.,Molecular Medicine Program, University of Utah, Salt Lake City, Utah, USA.,Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, Utah, USA
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Frankfater C, Henson WR, Juenger-Leif A, Foston M, Moon TS, Turk J, Kao JLF, Haas A, Hsu FF. Structural Determination of a New Peptidolipid Family from Rhodococcus opacus and the Pathogen Rhodococcus equi by Multiple Stage Mass Spectrometry. J Am Soc Mass Spectrom 2020; 31:611-623. [PMID: 31967470 DOI: 10.1021/jasms.9b00059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The cell walls of the genus Rhodococcus including the pathogenic bacterium Rhodococcus equi (R. equi) and biotechnologically important bacterium Rhodococcus opacus (R. opacus) contain an abundant peptidolipid (or termed lipopeptide) family whose structures have not been reported previously. Here, we describe a linear ion-trap multiple-stage mass spectrometric (LIT MSn) approach with high resolution mass spectrometry (HRMS), in conjunction with NMR spectroscopy, chemical reactions, and GC/MS analysis to define the structures of these compounds. We employed LIT MSn (n = 2-8) on the [M + Na]+ ion species to establish the peptide sequence, the identity of the fatty acyl substituent, and its location within the molecule, while NMR spectroscopy and GC/MS were used to recognize the Leu and Ile moieties. The major new lipopeptide found in R. opacus is defined as C17H35CH(OH)CH2CO-NHLeu-Ser-Leu-Ile-Thr-Ile-PheCOOH, where a β-OH fatty acyl (C18-C22) substituent is attached to the N-terminal of the LSLITIF peptide chain via a NH-CO bond. By contrast, the main peptidolipids found in R. equi belong to the cyclopeptidolipid family, which possesses the same peptide sequence and lipid chain, but the β-OH group of the fatty acyl moiety and the C-terminus of the peptide (i.e., the -COOH) are cyclized by an ester bond formation to a lactone, with a structure similar to iturin-A (Peypoux, F. et al. Biochemistry 1978, 17, 3992-3996). The antibiotic activity test of these new lipids did not reveal an activity against any of seven microorganisms tested.
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Affiliation(s)
| | | | - Alexandra Juenger-Leif
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Strasse 61a, 53121 Bonn, Germany
| | | | | | | | | | - Albert Haas
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Strasse 61a, 53121 Bonn, Germany
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Turk J, White TD, Nelson AJ, Lei X, Ramanadham S. iPLA 2β and its role in male fertility, neurological disorders, metabolic disorders, and inflammation. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:846-860. [PMID: 30408523 DOI: 10.1016/j.bbalip.2018.10.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 10/26/2018] [Accepted: 10/29/2018] [Indexed: 02/06/2023]
Abstract
The Ca2+-independent phospholipases, designated as group VI iPLA2s, also referred to as PNPLAs due to their shared homology with patatin, include the β, γ, δ, ε, ζ, and η forms of the enzyme. The iPLA2s are ubiquitously expressed, share a consensus GXSXG catalytic motif, and exhibit organelle/cell-specific localization. Among the iPLA2s, iPLA2β has received wide attention as it is recognized to be involved in membrane remodeling, cell proliferation, cell death, and signal transduction. Ongoing studies implicate participation of iPLA2β in a variety of disease processes including cancer, cardiovascular abnormalities, glaucoma, and peridonditis. This review will focus on iPLA2β and its links to male fertility, neurological disorders, metabolic disorders, and inflammation.
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Affiliation(s)
- John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, United States of America
| | - Tayleur D White
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States of America; Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States of America
| | - Alexander J Nelson
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States of America; Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States of America
| | - Xiaoyong Lei
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States of America; Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States of America
| | - Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States of America; Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, United States of America.
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Turk J, Simonson K, Landy U, Steinauer J. Restrictions affecting abortion training in obstetrics and gynecology residency programs. Contraception 2018. [DOI: 10.1016/j.contraception.2018.07.133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lin MH, Miner JH, Turk J, Hsu FF. Linear ion-trap MS n with high-resolution MS reveals structural diversity of 1-O-acylceramide family in mouse epidermis. J Lipid Res 2017; 58:772-782. [PMID: 28154204 DOI: 10.1194/jlr.d071647] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Revised: 01/27/2017] [Indexed: 12/30/2022] Open
Abstract
1-O-acylceramide is a new class of epidermal cer-amide (Cer) found in humans and mice. Here, we report an ESI linear ion-trap (LIT) multiple-stage MS (MSn) approach with high resolution toward structural characterization of this lipid family isolated from mice. Molecular species desorbed as the [M + H]+ ions were subjected to LIT MS2 to yield predominately the [M + H - H2O]+ ions, followed by MS3 to cleave the 1-O-acyl residue to yield the [M + H - H2O - (1-O-FA)]+ ions. The structures of the N-acyl chain and long-chain base (LCB) of the molecule were determined by MS4 on [M + H - H2O - (1-O-FA)]+ ions that yielded multiple sets of specific ions. Using this approach, isomers varied in the 1-O-acyl (from 14:0- to 30:0-O-acyl) and N-acyl chains (from 14:0- to 34:1-N-acyl) with 18:1-sphingosine as the major LCB were found for the entire family. Minor isomers consisting of 16:1-, 17:1-, 18:2-, and 19:1-sphingosine LCBs with odd fatty acyl chain or with monounsaturated N- or O-fatty acyl substituents were also identified. An estimation of more than 700 1-O-acylceramide species, largely isobaric isomers, are present, underscoring the complexity of this Cer family.
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Affiliation(s)
- Meei-Hua Lin
- Division of Nephrology Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Jeffrey H Miner
- Division of Nephrology Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - John Turk
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO.
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Ashley JW, Hancock WD, Nelson AJ, Bone RN, Tse HM, Wohltmann M, Turk J, Ramanadham S. Polarization of Macrophages toward M2 Phenotype Is Favored by Reduction in iPLA2β (Group VIA Phospholipase A2). J Biol Chem 2016; 291:23268-23281. [PMID: 27650501 DOI: 10.1074/jbc.m116.754945] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Indexed: 11/06/2022] Open
Abstract
Macrophages are important in innate and adaptive immunity. Macrophage participation in inflammation or tissue repair is directed by various extracellular signals and mediated by multiple intracellular pathways. Activation of group VIA phospholipase A2 (iPLA2β) causes accumulation of arachidonic acid, lysophospholipids, and eicosanoids that can promote inflammation and pathologic states. We examined the role of iPLA2β in peritoneal macrophage immune function by comparing wild type (WT) and iPLA2β-/- mouse macrophages. Compared with WT, iPLA2β-/- macrophages exhibited reduced proinflammatory M1 markers when classically activated. In contrast, anti-inflammatory M2 markers were elevated under naïve conditions and induced to higher levels by alternative activation in iPLA2β-/- macrophages compared with WT. Induction of eicosanoid (12-lipoxygenase (12-LO) and cyclooxygenase 2 (COX2))- and reactive oxygen species (NADPH oxidase 4 (NOX4))-generating enzymes by classical activation pathways was also blunted in iPLA2β-/- macrophages compared with WT. The effects of inhibitors of iPLA2β, COX2, or 12-LO to reduce M1 polarization were greater than those to enhance M2 polarization. Certain lipids (lysophosphatidylcholine, lysophosphatidic acid, and prostaglandin E2) recapitulated M1 phenotype in iPLA2β-/- macrophages, but none tested promoted M2 phenotype. These findings suggest that (a) lipids generated by iPLA2β and subsequently oxidized by cyclooxygenase and 12-LO favor macrophage inflammatory M1 polarization, and (b) the absence of iPLA2β promotes macrophage M2 polarization. Reducing macrophage iPLA2β activity and thereby attenuating macrophage M1 polarization might cause a shift from an inflammatory to a recovery/repair milieu.
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Affiliation(s)
- Jason W Ashley
- From the Department of Biology, Eastern Washington University, Cheney, Washington 99004
| | - William D Hancock
- Department of Cell, Developmental, and Integrative Biology.,Comprehensive Diabetes Center, and
| | - Alexander J Nelson
- Department of Cell, Developmental, and Integrative Biology.,Comprehensive Diabetes Center, and
| | - Robert N Bone
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, and
| | - Hubert M Tse
- Comprehensive Diabetes Center, and.,Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Mary Wohltmann
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology, .,Comprehensive Diabetes Center, and
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Muth BL, Astor BC, Turk J, Mohamed M, Parajuli S, Kaufman DB, Mandelbrot DA, Djamali A. Outpatient Management of Delayed Graft Function Is Associated With Reduced Length of Stay Without an Increase in Adverse Events. Am J Transplant 2016; 16:1604-11. [PMID: 26700736 DOI: 10.1111/ajt.13689] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 11/20/2015] [Accepted: 12/14/2015] [Indexed: 01/25/2023]
Abstract
Delayed graft function (DGF) is a common and costly complication of kidney transplantation. In July 2011, we established a multidisciplinary DGF clinic managed by nurse practitioners to facilitate early discharge and intensive management of DGF in the outpatient setting. We compared length of stay, 30-day readmission, acute rejection, and patient/graft survival in 697 consecutive deceased donor kidney transplantations performed between July 2009 and July 2014. Patients were divided into three groups: no DGF (n = 487), DGF before implementation of the DGF clinic (n = 118), and DGF clinic (n = 92). Baseline characteristics including age, gender, panel reactive antibody, retransplantation rates, HLA mismatches, induction, and maintenance immunosuppression were not significantly different between pre- and post-DGF clinic groups. Length of stay was significantly longer in pre-DGF clinic (10.9 ± 6.2 vs. 6.1 ± 2.1 days, p < 0.001). Thirty-day readmission (21% vs. 16%), graft loss (7% vs. 20%), and patient death (2% vs. 11%) did not differ significantly between pre- and post-DGF clinic. Patients in the DGF clinic were less likely to develop acute rejection (21% vs. 40%, p = 0.006). Outpatient management of DGF in a specialized clinic is associated with substantially shorter hospitalization and lower incidence of acute rejection without significant difference in 30-day readmission or patient and graft survival.
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Affiliation(s)
- B L Muth
- Division of Nephrology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - B C Astor
- Division of Nephrology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI.,Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - J Turk
- Division of Nephrology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - M Mohamed
- Division of Nephrology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - S Parajuli
- Division of Nephrology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - D B Kaufman
- Division of Transplantation, Department of Surgery, University of Wisconsin School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
| | - D A Mandelbrot
- Division of Nephrology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - A Djamali
- Division of Nephrology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI.,Division of Transplantation, Department of Surgery, University of Wisconsin School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
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Karner CM, Esen E, Chen J, Hsu FF, Turk J, Long F. Wnt Protein Signaling Reduces Nuclear Acetyl-CoA Levels to Suppress Gene Expression during Osteoblast Differentiation. J Biol Chem 2016; 291:13028-39. [PMID: 27129247 DOI: 10.1074/jbc.m115.708578] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Indexed: 02/04/2023] Open
Abstract
Developmental signals in metazoans play critical roles in inducing cell differentiation from multipotent progenitors. The existing paradigm posits that the signals operate directly through their downstream transcription factors to activate expression of cell type-specific genes, which are the hallmark of cell identity. We have investigated the mechanism through which Wnt signaling induces osteoblast differentiation in an osteoblast-adipocyte bipotent progenitor cell line. Unexpectedly, Wnt3a acutely suppresses the expression of a large number of genes while inducing osteoblast differentiation. The suppressed genes include Pparg and Cebpa, which encode adipocyte-specifying transcription factors and suppression of which is sufficient to induce osteoblast differentiation. The large scale gene suppression induced by Wnt3a corresponds to a global decrease in histone acetylation, an epigenetic modification that is associated with gene activation. Mechanistically, Wnt3a does not alter histone acetyltransferase or deacetylase activities but, rather, decreases the level of acetyl-CoA in the nucleus. The Wnt-induced decrease in histone acetylation is independent of β-catenin signaling but, rather, correlates with suppression of glucose metabolism in the tricarboxylic acid cycle. Functionally, preventing histone deacetylation by increasing nucleocytoplasmic acetyl-CoA levels impairs Wnt3a-induced osteoblast differentiation. Thus, Wnt signaling induces osteoblast differentiation in part through histone deacetylation and epigenetic suppression of an alternative cell fate.
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Affiliation(s)
| | - Emel Esen
- From the Department of Orthopaedic Surgery, Division of Biology and Biomedical Sciences
| | | | - Fong-Fu Hsu
- Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri 63131
| | - John Turk
- Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri 63131
| | - Fanxin Long
- From the Department of Orthopaedic Surgery, Division of Biology and Biomedical Sciences, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri 63131 Department of Developmental Biology, and
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Flentie KN, Stallings CL, Turk J, Minnaard AJ, Hsu FF. Characterization of phthiocerol and phthiodiolone dimycocerosate esters of M. tuberculosis by multiple-stage linear ion-trap MS. J Lipid Res 2016; 57:142-55. [PMID: 26574042 PMCID: PMC4689332 DOI: 10.1194/jlr.d063735] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 11/13/2015] [Indexed: 12/29/2022] Open
Abstract
Both phthiocerol/phthiodiolone dimycocerosate (PDIM) and phenolic glycolipids are abundant virulent lipids in the cell wall of various pathogenic mycobacteria, which can synthesize a wide range of complex high-molecular-mass lipids. In this article, we describe linear ion-trap MS(n) mass spectrometric approach for structural study of PDIMs, which were desorbed as the [M + Li](+) and [M + NH(4)](+) ions by ESI. We also applied charge-switch strategy to convert the mycocerosic acid substituents to their N-(4-aminomethylphenyl) pyridinium (AMPP) derivatives and analyzed them as M (+) ions, following alkaline hydrolysis of the PDIM to release mycocerosic acids. The structural information from MS(n) on the [M + Li](+) and [M + NH(4)](+) molecular species and on the M (+) ions of the mycocerosic acid-AMPP derivative affords realization of the complex structures of PDIMs in Mycobacterium tuberculosis biofilm, differentiation of phthiocerol and phthiodiolone lipid families and complete structure identification, including the phthiocerol and phthiodiolone backbones, and the mycocerosic acid substituents, including the locations of their multiple methyl side chains, can be achieved.
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Affiliation(s)
- Kelly N Flentie
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO
| | - Christina L Stallings
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO
| | - John Turk
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Department of Internal Medicine
| | - Adriaan J Minnaard
- Stratingh Institute for Chemistry, University of Groningen, Groningen, The Netherlands
| | - Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Department of Internal Medicine,
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14
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Prisenk J, Turk J, Pazek K. Multi-goal Optimization Process for Formulation of Daily Dairy Cow Rations on Organic Farms: A Slovenian Case Study. ANIM NUTR FEED TECHN 2016. [DOI: 10.5958/0974-181x.2016.00002.0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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15
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Abi Nahed R, Martinez G, Escoffier J, Yassine S, Karaouzène T, Hograindleur JP, Turk J, Kokotos G, Ray PF, Bottari S, Lambeau G, Hennebicq S, Arnoult C. Progesterone-induced Acrosome Exocytosis Requires Sequential Involvement of Calcium-independent Phospholipase A2β (iPLA2β) and Group X Secreted Phospholipase A2 (sPLA2). J Biol Chem 2015; 291:3076-89. [PMID: 26655718 DOI: 10.1074/jbc.m115.677799] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Indexed: 11/06/2022] Open
Abstract
Phospholipase A2 (PLA2) activity has been shown to be involved in the sperm acrosome reaction (AR), but the molecular identity of PLA2 isoforms has remained elusive. Here, we have tested the role of two intracellular (iPLA2β and cytosolic PLA2α) and one secreted (group X) PLA2s in spontaneous and progesterone (P4)-induced AR by using a set of specific inhibitors and knock-out mice. iPLA2β is critical for spontaneous AR, whereas both iPLA2β and group X secreted PLA2 are involved in P4-induced AR. Cytosolic PLA2α is dispensable in both types of AR. P4-induced AR spreads over 30 min in the mouse, and kinetic analyses suggest the presence of different sperm subpopulations, using distinct PLA2 pathways to achieve AR. At low P4 concentration (2 μm), sperm undergoing early AR (0-5 min post-P4) rely on iPLA2β, whereas sperm undergoing late AR (20-30 min post-P4) rely on group X secreted PLA2. Moreover, the role of PLA2s in AR depends on P4 concentration, with the PLA2s being key actors at low physiological P4 concentrations (≤2 μm) but not at higher P4 concentrations (~10 μm).
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Affiliation(s)
- Roland Abi Nahed
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Guillaume Martinez
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Jessica Escoffier
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Sandra Yassine
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Thomas Karaouzène
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Jean-Pascal Hograindleur
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - John Turk
- the Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, St. Louis, Missouri 63110
| | - George Kokotos
- the Department of Chemistry, University of Athens, Panepistimiopolis, Athens 15771, Greece
| | - Pierre F Ray
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France, the Centre Hospitalier Universitaire de Grenoble, Unité Fonctionnelle de Biochimie et Génétique Moléculaire, Grenoble F-38000, France
| | - Serge Bottari
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France, the Centre Hospitalier Universitaire de Grenoble, Plate-forme de Radioanalyse, IBP, CS10217, Grenoble F-38000, France
| | - Gérard Lambeau
- the Université de Nice-Sophia Antipolis, Valbonne 06560, France, the Centre Hospitalier Universitaire de Grenoble, Centre d'AMP-CECOS, CS1021, Grenoble F-38000, France
| | - Sylviane Hennebicq
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France, the Centre Hospitalier Universitaire de Grenoble, Centre d'AMP-CECOS, CS1021, Grenoble F-38000, France
| | - Christophe Arnoult
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France,
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Paran CW, Zou K, Ferrara PJ, Song H, Turk J, Funai K. Lipogenesis mitigates dysregulated sarcoplasmic reticulum calcium uptake in muscular dystrophy. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1530-8. [PMID: 26361872 DOI: 10.1016/j.bbalip.2015.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 08/27/2015] [Accepted: 09/06/2015] [Indexed: 01/07/2023]
Abstract
Muscular dystrophy is accompanied by a reduction in activity of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) that contributes to abnormal Ca(2+) homeostasis in sarco/endoplasmic reticulum (SR/ER). Recent findings suggest that skeletal muscle fatty acid synthase (FAS) modulates SERCA activity and muscle function via its effects on SR membrane phospholipids. In this study, we examined muscle's lipid metabolism in mdx mice, a mouse model for Duchenne muscular dystrophy (DMD). De novo lipogenesis was ~50% reduced in mdx muscles compared to wildtype (WT) muscles. Gene expressions of lipogenic and other ER lipid-modifying enzymes were found to be differentially expressed between wildtype (WT) and mdx muscles. A comprehensive examination of muscles' SR phospholipidome revealed elevated phosphatidylcholine (PC) and PC/phosphatidylethanolamine (PE) ratio in mdx compared to WT mice. Studies in primary myocytes suggested that defects in key lipogenic enzymes including FAS, stearoyl-CoA desaturase-1 (SCD1), and Lipin1 are likely contributing to reduced SERCA activity in mdx mice. Triple transgenic expression of FAS, SCD1, and Lipin1 (3TG) in mdx myocytes partly rescued SERCA activity, which coincided with an increase in SR PE that normalized PC/PE ratio. These findings implicate a defect in lipogenesis to be a contributing factor for SERCA dysfunction in muscular dystrophy. Restoration of muscle's lipogenic pathway appears to mitigate SERCA function through its effects on SR membrane composition.
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Affiliation(s)
- Christopher W Paran
- Department of Kinesiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; Department of Physiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA
| | - Kai Zou
- Department of Kinesiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA
| | - Patrick J Ferrara
- Department of Kinesiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA
| | - Haowei Song
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - John Turk
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
| | - Katsuhiko Funai
- Department of Kinesiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; Department of Physiology, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, 115 Heart Drive, Greenville, North Carolina 27834, USA.
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Paran CW, Verkerke AR, Heden TD, Park S, Zou K, Lawson HA, Song H, Turk J, Houmard JA, Funai K. Reduced efficiency of sarcolipin-dependent respiration in myocytes from humans with severe obesity. Obesity (Silver Spring) 2015; 23:1440-9. [PMID: 25970801 PMCID: PMC4483165 DOI: 10.1002/oby.21123] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 03/16/2015] [Accepted: 03/26/2015] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Sarcolipin (SLN) regulates muscle energy expenditure through its action on sarco/endoplasmic reticulum Ca(2+) -ATPase (SERCA) pump. It is unknown whether SLN-dependent respiration has relevance to human obesity, but whole-transcriptome gene expression profiling revealed that SLN was more highly expressed in myocytes from individuals with severe obesity (OB) than in lean controls (LN). The purpose of this study was to examine SLN-dependent cellular respiratory rates in LN and OB human muscles. METHODS Primary myocytes were isolated from muscle biopsy from seven LN and OB Caucasian females. Cellular respiration was assessed with and without lentivirus-mediated SLN knockdown in LN and OB myocytes. RESULTS SLN mRNA and protein abundance was greater in OB compared to LN cells. Despite elevated SLN levels in wild-type OB cells, respiratory rates among SLN-deficient cells were higher in OB compared to LN. Obesity-induced reduction in efficiency of SLN-dependent respiration was associated with altered sarcoplasmic reticulum phospholipidome. CONCLUSIONS SLN-dependent respiration is reduced in muscles from humans with severe obesity compared to lean controls. Identification of the molecular mechanism that affects SLN efficiency might lead to interventions that promote an increase in skeletal muscle energy expenditure.
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Affiliation(s)
- Christopher W. Paran
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
- Physiology, East Carolina University, Greenville, NC, USA
| | - Anthony R.P. Verkerke
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Timothy D. Heden
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Sanghee Park
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Kai Zou
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Heather A. Lawson
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Haowei Song
- Medicine Mass Spectrometry Facility, Washington University School of Medicine, St. Louis, MO, USA
| | - John Turk
- Medicine Mass Spectrometry Facility, Washington University School of Medicine, St. Louis, MO, USA
| | - Joseph A. Houmard
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
| | - Katsuhiko Funai
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
- Department of Kinesiology, East Carolina University, Greenville, NC, USA
- Physiology, East Carolina University, Greenville, NC, USA
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Thimgan MS, Seugnet L, Turk J, Shaw PJ. Identification of genes associated with resilience/vulnerability to sleep deprivation and starvation in Drosophila. Sleep 2015; 38:801-14. [PMID: 25409104 DOI: 10.5665/sleep.4680] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 10/10/2014] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND AND STUDY OBJECTIVES Flies mutant for the canonical clock protein cycle (cyc(01)) exhibit a sleep rebound that is ∼10 times larger than wild-type flies and die after only 10 h of sleep deprivation. Surprisingly, when starved, cyc(01) mutants can remain awake for 28 h without demonstrating negative outcomes. Thus, we hypothesized that identifying transcripts that are differentially regulated between waking induced by sleep deprivation and waking induced by starvation would identify genes that underlie the deleterious effects of sleep deprivation and/or protect flies from the negative consequences of waking. DESIGN We used partial complementary DNA microarrays to identify transcripts that are differentially expressed between cyc(01) mutants that had been sleep deprived or starved for 7 h. We then used genetics to determine whether disrupting genes involved in lipid metabolism would exhibit alterations in their response to sleep deprivation. SETTING Laboratory. PATIENTS OR PARTICIPANTS Drosophila melanogaster. INTERVENTIONS Sleep deprivation and starvation. MEASUREMENTS AND RESULTS We identified 84 genes with transcript levels that were differentially modulated by 7 h of sleep deprivation and starvation in cyc(01) mutants and were confirmed in independent samples using quantitative polymerase chain reaction. Several of these genes were predicted to be lipid metabolism genes, including bubblegum, cueball, and CG4500, which based on our data we have renamed heimdall (hll). Using lipidomics we confirmed that knockdown of hll using RNA interference significantly decreased lipid stores. Importantly, genetically modifying bubblegum, cueball, or hll resulted in sleep rebound alterations following sleep deprivation compared to genetic background controls. CONCLUSIONS We have identified a set of genes that may confer resilience/vulnerability to sleep deprivation and demonstrate that genes involved in lipid metabolism modulate sleep homeostasis.
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Affiliation(s)
- Matthew S Thimgan
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO.,Missouri University of Science and Technology, Department of Biological Sciences, Rolla, MO
| | - Laurent Seugnet
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO.,Centre de Recherche en Neurosciences de Lyon, Integrated Physiology of Arousal Systems Team, Lyon, France
| | - John Turk
- Division of Endocrinology, Diabetes, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Paul J Shaw
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO
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Duraffourg A, Yayehd K, Fourny M, Turk J, Massoutier M, Ageron FX, Debaty G, Ricard C, Vanzetto G, Belle L, Labarere J. [Reperfusion in ST elevation myocardial infarction. From the guidelines to practice]. Ann Cardiol Angeiol (Paris) 2014; 63:312-320. [PMID: 25283574 DOI: 10.1016/j.ancard.2014.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
BACKGROUND International guidelines have recommendations for selecting the type of reperfusion (fibrinolysis or angioplasty) in the setting of ST-segment elevation myocardial infarction (STEMI), and suggest that emergency-care networks adapt these recommendations according to the local environment. AIM To assess the proportions of STEMI patients treated with fibrinolysis or angioplasty in accordance with regional guidelines. METHOD Observational study based on a permanent registry of patients with STEMI of <12h duration in an emergency network in the French North Alps (Isère, Savoie, Haute-Savoie) from January 2009 to December 2012. RESULTS The registry included 2620 patients. Reperfusion was given in 2425/2620 (93%) of patients. Reperfusion type was in accordance with recommendations in 1567/2620 (60%) patients. Guideline-recommended fibrinolysis and angioplasty were performed in 47% (656/1385) and 79% (911/1149) respectively, of patients. In multivariable analysis, variables independently associated with guideline-recommended reperfusion were: an age < 65 years (OR 1.60; 95%CI 1.33-1.90), being managed in Haute-Savoie versus Isère or Savoie (OR 1.38; 95%CI 1.12-1.71), an arterial tension < 100mmHg (OR 1.73; 95%CI 1.27-2.35), a cardiogenic shock (OR 0.50; 95%CI 0.30-0.84), a pacemaker or left bundle branch block (OR 0.49; 95%CI 0.28-0.88), and an initial management outside the network (followed by treatment in an interventional centre in the network) (OR 0.62; 95%CI 0.40-0.94). Patients initially treated by mobile intensive care units were more often reperfused in accordance with recommendations when admitted < 3 (versus ≥ 3) h following symptom onset (adjusted OR 2.05; 95% CI 1.61-2.59), while those initially treated by in-hospital emergency units were less often reperfused in accordance with recommendation when treated < 3h following symptom onset (adjusted OR 0.67; 95% CI 0.46-0.97). In-hospital major adverse cardiac events (9.1% vs. 8.5%) and in-hospital mortality (6.4% vs. 5.1%) were not significantly different between patients reperfused in accordance with (versus not) recommendations. CONCLUSIONS Forty percent of patients with STEMI were not reperfused with fibrinolysis or angioplasty in accordance with regional guidelines. Characterization of this population should allow us to improve guideline adherence.
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Affiliation(s)
- A Duraffourg
- Médecins de Montagne Rhône-Alpes, 256, rue de la République, 73000 Chambery, France
| | - K Yayehd
- Service de cardiologie, CHU Campus, 03 BP 30284, Lomé, Togo
| | - M Fourny
- Unité d'évaluation médicale, CHU, 38000 Grenoble, France
| | - J Turk
- Service d'aide médicale urgente, centre hospitalier, 73000 Chambery, France
| | - M Massoutier
- Unité d'évaluation médicale, CHU, 38000 Grenoble, France
| | - F X Ageron
- Service d'aide médicale urgente, centre hospitalier, 74000 Annecy, France
| | - G Debaty
- Service d'aide médicale urgente, CHU, 38000 Grenoble, France
| | - C Ricard
- Réseau nord Alpin des urgences, centre hospitalier, 74000 Annecy, France
| | - G Vanzetto
- Service de cardiologie, CHU, 38000 Grenoble, France
| | - L Belle
- Service de cardiologie, centre hospitalier, 74000 Annecy, France.
| | - J Labarere
- Unité d'évaluation médicale, CHU, 38000 Grenoble, France
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20
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Hsu FF, Lodhi IJ, Turk J, Semenkovich CF. Structural distinction of diacyl-, alkylacyl, and alk-1-enylacyl glycerophosphocholines as [M - 15]⁻ ions by multiple-stage linear ion-trap mass spectrometry with electrospray ionization. J Am Soc Mass Spectrom 2014; 25:1412-20. [PMID: 24781459 PMCID: PMC4331342 DOI: 10.1007/s13361-014-0908-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/27/2014] [Accepted: 03/27/2014] [Indexed: 05/15/2023]
Abstract
We describe a linear ion-trap (LIT) multiple-stage (MS(n)) mass spectrometric approach towards differentiation of alkylacyl, alk-1-enylacyl- and diacyl-glycerophoscholines (PCs) as the [M - 15]⁻ ions desorbed by electrospray ionization (ESI) in the negative-ion mode. The MS⁴ mass spectra of the [M - 15 - R²'CH = CO]⁻ ions originated from the three PC subfamilies are readily distinguishable, resulting in unambiguous distinction of the lipid classes. This method is applied to two alkyl ether rich PC mixtures isolated from murine bone marrow neutrophils and kidney, respectively, to explore its utility in the characterization of complex PC mixture of biological origin, resulting in the realization of the detailed structures of the PC species, including various classes and many minor isobaric isomers.
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Affiliation(s)
- Fong-Fu Hsu
- Mass Spectrometry Resource, Washington University School of Medicine, St. Louis, MO, 63110, USA,
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21
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Song H, Wohltmann M, Tan M, Ladenson JH, Turk J. Group VIA phospholipase A2 mitigates palmitate-induced β-cell mitochondrial injury and apoptosis. J Biol Chem 2014; 289:14194-210. [PMID: 24648512 DOI: 10.1074/jbc.m114.561910] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Palmitate (C16:0) induces apoptosis of insulin-secreting β-cells by processes that involve generation of reactive oxygen species, and chronically elevated blood long chain free fatty acid levels are thought to contribute to β-cell lipotoxicity and the development of diabetes mellitus. Group VIA phospholipase A2 (iPLA2β) affects β-cell sensitivity to apoptosis, and here we examined iPLA2β effects on events that occur in β-cells incubated with C16:0. Such events in INS-1 insulinoma cells were found to include activation of caspase-3, expression of stress response genes (C/EBP homologous protein and activating transcription factor 4), accumulation of ceramide, loss of mitochondrial membrane potential, and apoptosis. All of these responses were blunted in INS-1 cells that overexpress iPLA2β, which has been proposed to facilitate repair of oxidized mitochondrial phospholipids, e.g. cardiolipin (CL), by excising oxidized polyunsaturated fatty acid residues, e.g. linoleate (C18:2), to yield lysophospholipids, e.g. monolysocardiolipin (MLCL), that can be reacylated to regenerate the native phospholipid structures. Here the MLCL content of mouse pancreatic islets was found to rise with increasing iPLA2β expression, and recombinant iPLA2β hydrolyzed CL to MLCL and released oxygenated C18:2 residues from oxidized CL in preference to native C18:2. C16:0 induced accumulation of oxidized CL species and of the oxidized phospholipid (C18:0/hydroxyeicosatetraenoic acid)-glycerophosphoethanolamine, and these effects were blunted in INS-1 cells that overexpress iPLA2β, consistent with iPLA2β-mediated removal of oxidized phospholipids. C16:0 also induced iPLA2β association with INS-1 cell mitochondria, consistent with a role in mitochondrial repair. These findings indicate that iPLA2β confers significant protection of β-cells against C16:0-induced injury.
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Affiliation(s)
- Haowei Song
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
| | - Mary Wohltmann
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
| | - Min Tan
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
| | - Jack H Ladenson
- Division of Laboratory and Genomic Medicine, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - John Turk
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
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Hsu FF, Kuhlmann FM, Turk J, Beverley SM. Multiple-stage linear ion-trap with high resolution mass spectrometry towards complete structural characterization of phosphatidylethanolamines containing cyclopropane fatty acyl chain in Leishmania infantum. J Mass Spectrom 2014; 49:201-9. [PMID: 24619546 PMCID: PMC4007172 DOI: 10.1002/jms.3327] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 12/06/2013] [Accepted: 12/11/2013] [Indexed: 05/24/2023]
Abstract
The structures of phosphatidylethanolamine (PE) in Leishmania infantum are unique in that they consist of a rare cyclopropane fatty acid (CFA) containing PE subfamily, including CFA-containing plasmalogen PE species. In this contribution, we applied multiple-stage linear ion-trap combined with high-resolution mass spectrometry to define the structures of PEs that were desorbed as [M - H](-) and [M - H + 2Li](+) ions by ESI, respectively. The structural information arising from MS(n) on both the molecular species are complimentary, permitting complete determination of PE structures, including the identities of the fatty acid substituents and their location on the glycerol backbone, more importantly, the positions of the double bond(s) and of the cyclopropane chain of the fatty acid chain, directing to the realization of the CFA biosynthesis pathways that were reported previously. We also uncovered the presence of a minor dimethyl-PE subclass that has not been previously reported in L. infantum. This LIT MS(n) mass spectrometric approach led to unambiguous identification of PE molecules including many isomers in complex mixture that would otherwise be very difficult to define using other analytical approaches.
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Affiliation(s)
- Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism and Lipid Research, USA
| | - F. Matthew Kuhlmann
- Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - John Turk
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism and Lipid Research, USA
| | - Stephen M. Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
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Tan C, Day R, Bao S, Turk J, Zhao QD. Group VIA phospholipase A2 mediates enhanced macrophage migration in diabetes mellitus by increasing expression of nicotinamide adenine dinucleotide phosphate oxidase 4. Arterioscler Thromb Vasc Biol 2014; 34:768-78. [PMID: 24482376 DOI: 10.1161/atvbaha.113.302847] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE We previously demonstrated that nicotinamide adenine dinucleotide phosphate oxidase 4 (Nox4) mediates increased monocyte priming and chemotaxis under conditions of diabetic metabolic stress, and emerging data indicate that group VIA phospholipase A2 (iPLA2β) also participates in regulating monocyte chemotaxis. Here, we examined relationships between iPLA2β expression and Nox4 action in mouse peritoneal macrophages subjected to diabetic metabolic stress. APPROACH AND RESULTS Increased iPLA2β expression and activity were observed in macrophages from low-density lipoprotein receptor knockout mice that were fed a high-fat diet, and this was associated with time-dependent increases in atherosclerotic lesion size and macrophage content. Incubating macrophages with 30 mmol/L D-glucose, 100 μg/mL low-density lipoprotein, or both (D-glucose+low-density lipoprotein) induced a robust increase in iPLA2β expression and activity and in cell migration in response to monocyte chemoattractant protein-1. The increases in iPLA2β activity and cell migration were prevented by a bromoenol lactone iPLA2β suicide inhibitor or an iPLA2β antisense oligonucleotide. Incubating macrophages under conditions that mimic diabetic metabolic stress ex vivo resulted in increased Nox4 expression and activity and hydrogen peroxide generation compared with controls. Bromoenol lactone prevented those effects without affecting Nox2 expression. Nox4 inhibition eliminated diabetic metabolic stress-induced acceleration of macrophage migration. Lysophosphatidic acid restored Nox4 expression, hydrogen peroxide generation, and migration to bromoenol lactone-treated cells, and a lysophosphatidic acid receptor antagonist abrogated iPLA2β-mediated increases in Nox4 expression. CONCLUSIONS Taken together, these observations identify iPLA2β and lysophosphatidic acid derived from its action as critical in regulating macrophage Nox4 activity and migration in the diabetic state in vivo and under similar conditions ex vivo.
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Affiliation(s)
- Chunyan Tan
- From the Department of Medicine, University of Texas Health Science Center, San Antonio (C.T., R.D., Q.D.Z.); and Department of Medicine, Washington University School of Medicine, St. Louis, MO (S.B., J.T.)
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Sharma J, Eickhoff CS, Hoft DF, Marentette JO, Turk J, McHowat J. Absence of calcium-independent phospholipase A2 β impairs platelet-activating factor production and inflammatory cell recruitment in Trypanosoma cruzi-infected endothelial cells. Physiol Rep 2014; 2:e00196. [PMID: 24744875 PMCID: PMC3967679 DOI: 10.1002/phy2.196] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 12/06/2013] [Accepted: 12/08/2013] [Indexed: 01/06/2023] Open
Abstract
Both acute and chronic phases of Trypanosoma cruzi (T. cruzi) infection are characterized by tissue inflammation, mainly in the heart. A key step in the inflammatory process is the transmigration of inflammatory cells across the endothelium to underlying infected tissues. We observed increased arachidonic acid release and platelet-activating factor (PAF) production in human coronary artery endothelial cells (HCAEC) at up to 96 h of T. cruzi infection. Arachidonic acid release is mediated by activation of the calcium-independent phospholipase A2 (iPLA2) isoforms iPLA2 β and iPLA2 γ, whereas PAF production was dependent upon iPLA2 β activation alone. Trypanosoma cruzi infection also resulted in increased cell surface expression of adhesion molecules. Increased adherence of inflammatory cells to T. cruzi-infected endothelium was blocked by inhibition of endothelial cell iPLA2 β or by blocking the PAF receptor on inflammatory cells. This suggests that PAF, in combination with adhesion molecules, might contribute to parasite clearing in the heart by recruiting inflammatory cells to the endothelium.
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Affiliation(s)
- Janhavi Sharma
- Department of Pathology, Saint Louis University School of Medicine, 1402 S. Grand BlvdSt Louis, 63104, Missouri
| | - Christopher S. Eickhoff
- Division of Infectious Diseases, Department of Internal Medicine, Saint Louis University School of Medicine, 1402 S. Grand Blvd., St Louis, 63104, Missouri
| | - Daniel F. Hoft
- Division of Infectious Diseases, Department of Internal Medicine, Saint Louis University School of Medicine, 1402 S. Grand Blvd., St Louis, 63104, Missouri
| | - John O. Marentette
- Department of Pathology, Saint Louis University School of Medicine, 1402 S. Grand BlvdSt Louis, 63104, Missouri
| | - John Turk
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, Washington University in St. Louis, St. Louis, 63110, Missouri
| | - Jane McHowat
- Department of Pathology, Saint Louis University School of Medicine, 1402 S. Grand BlvdSt Louis, 63104, Missouri
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Prišenk J, Pažek K, Rozman Č, Turk J, Janžekovič M, Borec A. Application of weighted goal programming in the optimization of rations for sport horses. J Anim Feed Sci 2013. [DOI: 10.22358/jafs/65922/2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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26
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Preskill F, Turk J, Mock H, Pomerantz T, Landy U, Steinauer J. Prospective cohort of U.S. ob-Gyns regarding abortion training and practice post-residency. Contraception 2013. [DOI: 10.1016/j.contraception.2013.05.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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27
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Purdy GE, Pacheco S, Turk J, Hsu FF. Characterization of mycobacterial triacylglycerols and monomeromycolyl diacylglycerols from Mycobacterium smegmatis biofilm by electrospray ionization multiple-stage and high-resolution mass spectrometry. Anal Bioanal Chem 2013; 405:7415-26. [PMID: 23852148 DOI: 10.1007/s00216-013-7179-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 06/21/2013] [Accepted: 06/25/2013] [Indexed: 11/28/2022]
Abstract
The storage of triacylglycerols (TAGs) is essential for non-replicating persistence relevant to survival and the re-growth of mycobacteria during their exit from non-replicating state stress conditions. However, the detailed structures of this lipid family in mycobacteria largely remain unexplored. In this contribution, we describe a multiple-stage linear ion-trap mass spectrometric approach with high resolution mass spectrometry toward direct structural analysis of the TAGs, including a novel lipid subclass previously defined as monomeromycolyl diacylglycerol (MMDAG) isolated from biofilm of Mycobacterium smegmatis, a rapidly growing, non-pathogenic mycobacterium that has been used as a tool for molecular analysis of mycobacteria. Our results demonstrate that the major isomer in each of the molecular species of TAGs and MMDAGs consists of the common structure in which Δ(9)18:1- and 16:0-fatty acyl substituents are exclusively located at sn-1 and sn-2, respectively. Several isomers were found for most of the molecular species, and thus hundreds of structures are present in this lipid family. More importantly, this study revealed the structures of MMDAG, a novel subclass of TAG that has not been previously reported by direct mass spectrometric approaches.
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Affiliation(s)
- Georgiana E Purdy
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR 97239, USA
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Chen A, Tang Y, Davis V, Hsu FF, Kennedy SM, Song H, Turk J, Brunt EM, Newberry EP, Davidson NO. Liver fatty acid binding protein (L-Fabp) modulates murine stellate cell activation and diet-induced nonalcoholic fatty liver disease. Hepatology 2013; 57:2202-12. [PMID: 23401290 PMCID: PMC3665693 DOI: 10.1002/hep.26318] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 01/31/2013] [Indexed: 12/12/2022]
Abstract
UNLABELLED Activation of hepatic stellate cells (HSCs) is crucial to the development of fibrosis in nonalcoholic fatty liver disease. Quiescent HSCs contain lipid droplets (LDs), whose depletion upon activation induces a fibrogenic gene program. Here we show that liver fatty acid-binding protein (L-Fabp), an abundant cytosolic protein that modulates fatty acid (FA) metabolism in enterocytes and hepatocytes, also modulates HSC FA utilization and in turn regulates the fibrogenic program. L-Fabp expression decreased 10-fold following HSC activation, concomitant with depletion of LDs. Primary HSCs isolated from L-FABP(-/-) mice contain fewer LDs than wild-type (WT) HSCs, and exhibit up-regulated expression of genes involved in HSC activation. Adenoviral L-Fabp transduction inhibited activation of passaged WT HSCs and increased both the expression of prolipogenic genes and also augmented intracellular lipid accumulation, including triglyceride and FA, predominantly palmitate. Freshly isolated HSCs from L-FABP(-/-) mice correspondingly exhibited decreased palmitate in the free FA pool. To investigate whether L-FABP deletion promotes HSC activation in vivo, we fed L-FABP(-/-) and WT mice a high-fat diet supplemented with trans-fatty acids and fructose (TFF). TFF-fed L-FABP(-/-) mice exhibited reduced hepatic steatosis along with decreased LD abundance and size compared to WT mice. In addition, TFF-fed L-FABP(-/-) mice exhibited decreased hepatic fibrosis, with reduced expression of fibrogenic genes, compared to WT mice. CONCLUSION L-FABP deletion attenuates both diet-induced hepatic steatosis and fibrogenesis, despite the observation that L-Fabp paradoxically promotes FA and LD accumulation and inhibits HSC activation in vitro. These findings highlight the importance of cell-specific modulation of hepatic lipid metabolism in promoting fibrogenesis in nonalcoholic fatty liver disease. (Hepatology 2013).
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Affiliation(s)
- Anping Chen
- Departments of Pathology, School of Medicine, Saint Louis University, Saint Louis, MO. 63104
| | - Youcai Tang
- Departments of Pathology, School of Medicine, Saint Louis University, Saint Louis, MO. 63104
| | - Victoria Davis
- Department of Medicine, Washington University School of Medicine, St. Louis, MO. 63110
| | - Fong-Fu Hsu
- Department of Medicine, Washington University School of Medicine, St. Louis, MO. 63110
| | - Susan M. Kennedy
- Department of Medicine, Washington University School of Medicine, St. Louis, MO. 63110
| | - Haowei Song
- Department of Medicine, Washington University School of Medicine, St. Louis, MO. 63110
| | - John Turk
- Department of Medicine, Washington University School of Medicine, St. Louis, MO. 63110
| | - Elizabeth M. Brunt
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO. 63110
| | - Elizabeth P. Newberry
- Department of Medicine, Washington University School of Medicine, St. Louis, MO. 63110
| | - Nicholas O. Davidson
- Department of Medicine, Washington University School of Medicine, St. Louis, MO. 63110,Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO. 63110,Corresponding author: Tel: 314-362-2027; Fax: 314-362-2033;
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Rector RS, Morris EM, Ridenhour S, Meers GM, Hsu FF, Turk J, Ibdah JA. Selective hepatic insulin resistance in a murine model heterozygous for a mitochondrial trifunctional protein defect. Hepatology 2013; 57:2213-23. [PMID: 23359250 PMCID: PMC3660447 DOI: 10.1002/hep.26285] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 01/04/2013] [Indexed: 12/20/2022]
Abstract
UNLABELLED Earlier reports suggest a link between mitochondrial dysfunction and development of hepatic insulin resistance. Here we used a murine model heterozygous (HET) for a mitochondrial trifunctional protein (MTP) gene defect to determine if a primary defect in mitochondrial long-chain fatty acid oxidation disrupts hepatic insulin action. Hyperinsulinemic-euglycemic clamps and signaling studies were performed for assessment of whole-body and hepatic insulin resistance/signaling. In addition, hepatic fatty acid oxidation and hepatic insulin action were assessed in vitro using primary hepatocytes isolated from HET and wildtype (WT) mice. In both hepatic mitochondria and isolated primary hepatocytes, heterozygosity of MTP caused an ∼50% reduction in mitochondrial fatty acid oxidation, a significantly impaired glucose disposal during the insulin clamp, and a markedly lower insulin-stimulated suppression of hepatic glucose production. HET mice also exhibited impaired insulin signaling, with increased hepatic phosphorylation of IRS2 (ser731) and reduced Akt phosphorylation (ser473) in both hepatic tissue and isolated primary hepatocytes. Assessment of insulin-stimulated FOXO1/phospho-FOXO1 protein content and PEPCK/G6Pase messenger RNA (mRNA) expression did not reveal differences between HET and WT mice. However, insulin-induced phosphorylation of GSK3β was significantly blunted in HET mice. Hepatic insulin resistance was associated with an increased methylation status of the catalytic subunit of protein phosphatase 2A (PP2A-C), but was not associated with differences in hepatic diacylglycerol content, activated protein kinase C-ϵ (PKC-ϵ), inhibitor κB kinase β (IKK-β), c-Jun N-terminal kinase (JNK), or phospho-JNK protein contents. Surprisingly, hepatic ceramides were significantly lower in the HET mice compared with WT. CONCLUSION A primary defect in mitochondrial fatty acid β-oxidation causes hepatic insulin resistance selective to hepatic glycogen metabolism that is associated with elevated methylated PP2A-C, but independent of other mechanisms commonly considered responsible for insulin resistance. (HEPATOLOGY 2013;).
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Affiliation(s)
- R. Scott Rector
- Harry S Truman Memorial Veterans Medical Center, Columbia, Missouri 65212, USA,Department of Internal Medicine-Division of Gastroenterology and Hepatology, University of Missouri,Department of Nutrition and Exercise Physiology, University of Missouri
| | - E. Matthew Morris
- Harry S Truman Memorial Veterans Medical Center, Columbia, Missouri 65212, USA,Department of Internal Medicine-Division of Gastroenterology and Hepatology, University of Missouri
| | - Suzanne Ridenhour
- Harry S Truman Memorial Veterans Medical Center, Columbia, Missouri 65212, USA,Department of Internal Medicine-Division of Gastroenterology and Hepatology, University of Missouri
| | - Grace M. Meers
- Harry S Truman Memorial Veterans Medical Center, Columbia, Missouri 65212, USA,Department of Internal Medicine-Division of Gastroenterology and Hepatology, University of Missouri
| | - Fong-Fu Hsu
- Department of Internal Medicine, Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - John Turk
- Department of Internal Medicine, Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jamal A. Ibdah
- Harry S Truman Memorial Veterans Medical Center, Columbia, Missouri 65212, USA,Department of Internal Medicine-Division of Gastroenterology and Hepatology, University of Missouri,Department of Nutrition and Exercise Physiology, University of Missouri,Department of Medical Pharmacology and Physiology, University of Missouri
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Hsu FF, Lobasso S, Turk J, Corcelli A. Structural studies on archaeal phytanyl-ether lipids isolated from membranes of extreme halophiles by linear ion-trap multiple-stage tandem mass spectrometry with electrospray ionization. Anal Chim Acta 2013; 771:73-85. [PMID: 23522115 PMCID: PMC3618892 DOI: 10.1016/j.aca.2013.02.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Revised: 01/30/2013] [Accepted: 02/08/2013] [Indexed: 10/27/2022]
Abstract
The structures of archaeal glycerophospholipids and glycolipids are unique in that they consist of phytanyl substituents ether linked to the glycerol backbone, imparting stability to the molecules. In this contribution, we described multiple-stage linear ion-trap combined with high resolution mass spectrometry toward structural characterization of this lipid family desorbed as lithiated adduct ions or as the [M-H](-) and [M-2H](2-) ions by ESI. MS(n) on various forms of the lithiated adduct ions yielded rich structurally informative ions leading to complete structure identification of this lipid family, including the location of the methyl branches of the phytanyl chain. By contrast, structural information deriving from MS(n) on the [M-H](-) and [M-2H](2-) ions is not complete. The fragmentation pathways in an ion-trap, including unusual internal loss of glycerol moiety and internal loss of hexose found for this lipid family were proposed. This mass spectrometric approach provides a simple tool to facilitate confident characterization of this unique lipid family.
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Affiliation(s)
- Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, United States.
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Zhu T, Chappel JC, Hsu FF, Turk J, Aurora R, Hyrc K, De Camilli P, Broekelmann TJ, Mecham RP, Teitelbaum SL, Zou W. Type I phosphotidylinosotol 4-phosphate 5-kinase γ regulates osteoclasts in a bifunctional manner. J Biol Chem 2013; 288:5268-77. [PMID: 23300084 PMCID: PMC3581369 DOI: 10.1074/jbc.m112.446054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Indexed: 12/22/2022] Open
Abstract
Type 1 phosphotidylinosotol-4 phosphate 5 kinase γ (PIP5KIγ) is central to generation of phosphotidylinosotol (4,5)P(2) (PI(4,5)P(2)). PIP5KIγ also participates in cytoskeletal organization by delivering talin to integrins, thereby enhancing their ligand binding capacity. As the cytoskeleton is pivotal to osteoclast function, we hypothesized that absence of PIP5KIγ would compromise their resorptive capacity. Absence of the kinase diminishes PI(4,5) abundance and desensitizes precursors to RANK ligand-stimulated differentiation. Thus, PIP5KIγ(-/-) osteoclasts are reduced in number in vitro and confirm physiological relevance in vivo. Despite reduced numbers, PIP5KIγ(-/-) osteoclasts surprisingly have normal cytoskeletons and effectively resorb bone. PIP5KIγ overexpression, which increases PI(4,5)P(2), also delays osteoclast differentiation and reduces cell number but in contrast to cells lacking the kinase, its excess disrupts the cytoskeleton. The cytoskeleton-disruptive effects of excess PIP5KIγ reflect its kinase activity and are independent of talin recognition. The combined arrested differentiation and disorganized cytoskeleton of PIP5KIγ-transduced osteoclasts compromises bone resorption. Thus, optimal PIP5KIγ and PI(4,5)P(2) expression, by osteoclasts, are essential for skeletal homeostasis.
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Affiliation(s)
| | | | | | | | - Rajeev Aurora
- the Department of Molecular Microbiology and Immunology, St. Louis University School of Medicine, St. Louis, Missouri 63104, and
| | - Krzysztof Hyrc
- Center for the Investigation of Membrane Excitability Diseases, Washington University in St. Louis School of Medicine, St. Louis, Missouri 63110
| | - Pietro De Camilli
- the Department of Cell Biology and Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520
| | | | | | | | - Wei Zou
- From the Department of Pathology and Immunology
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Musselman LP, Fink JL, Ramachandran PV, Patterson BW, Okunade AL, Maier E, Brent MR, Turk J, Baranski TJ. Role of fat body lipogenesis in protection against the effects of caloric overload in Drosophila. J Biol Chem 2013; 288:8028-8042. [PMID: 23355467 DOI: 10.1074/jbc.m112.371047] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Drosophila fat body is a liver- and adipose-like tissue that stores fat and serves as a detoxifying and immune responsive organ. We have previously shown that a high sugar diet leads to elevated hemolymph glucose and systemic insulin resistance in developing larvae and adults. Here, we used stable isotope tracer feeding to demonstrate that rearing larvae on high sugar diets impaired the synthesis of esterified fatty acids from dietary glucose. Fat body lipid profiling revealed changes in both carbon chain length and degree of unsaturation of fatty acid substituents, particularly in stored triglycerides. We tested the role of the fat body in larval tolerance of caloric excess. Our experiments demonstrated that lipogenesis was necessary for animals to tolerate high sugar feeding as tissue-specific loss of orthologs of carbohydrate response element-binding protein or stearoyl-CoA desaturase 1 resulted in lethality on high sugar diets. By contrast, increasing the fat content of the fat body by knockdown of king-tubby was associated with reduced hyperglycemia and improved growth and tolerance of high sugar diets. Our work supports a critical role for the fat body and the Drosophila carbohydrate response element-binding protein ortholog in metabolic homeostasis in Drosophila.
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Affiliation(s)
- Laura Palanker Musselman
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Jill L Fink
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Prasanna Venkatesh Ramachandran
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Bruce W Patterson
- Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Adewole L Okunade
- Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Ezekiel Maier
- Department of Computer Science and Center for Genome Sciences and Systems Biology, Washington University, St. Louis, Missouri 63130
| | - Michael R Brent
- Department of Computer Science and Center for Genome Sciences and Systems Biology, Washington University, St. Louis, Missouri 63130
| | - John Turk
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Thomas J Baranski
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
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Lei X, Bone RN, Ali T, Wohltmann M, Gai Y, Goodwin KJ, Bohrer AE, Turk J, Ramanadham S. Genetic modulation of islet β-cell iPLA₂β expression provides evidence for its impact on β-cell apoptosis and autophagy. Islets 2013; 5:29-44. [PMID: 23411472 PMCID: PMC3662380 DOI: 10.4161/isl.23758] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
β-cell apoptosis is a significant contributor to β-cell dysfunction in diabetes and ER stress is among the factors that contributes to β-cell death. We previously identified that the Ca²⁺-independent phospholipase A₂β (iPLA₂β), which in islets is localized in β-cells, participates in ER stress-induced β-cell apoptosis. Here, direct assessment of iPLA₂β role was made using β-cell-specific iPLA₂β overexpressing (RIP-iPLA₂β-Tg) and globally iPLA₂β-deficient (iPLA₂β-KO) mice. Islets from Tg, but not KO, express higher islet iPLA₂β and neutral sphingomyelinase, decrease in sphingomyelins, and increase in ceramides, relative to WT group. ER stress induces iPLA₂β, ER stress factors, loss of mitochondrial membrane potential (∆Ψ), caspase-3 activation, and β-cell apoptosis in the WT and these are all amplified in the Tg group. Surprisingly, β-cells apoptosis while reduced in the KO is higher than in the WT group. This, however, was not accompanied by greater caspase-3 activation but with larger loss of ∆Ψ, suggesting that iPLA₂β deficiency impacts mitochondrial membrane integrity and causes apoptosis by a caspase-independent manner. Further, autophagy, as reflected by LC3-II accumulation, is increased in Tg and decreased in KO, relative to WT. Our findings suggest that (1) iPLA₂β impacts upstream (UPR) and downstream (ceramide generation and mitochondrial) pathways in β-cells and (2) both over- or under-expression of iPLA₂β is deleterious to the β-cells. Further, we present for the first time evidence for potential regulation of autophagy by iPLA₂β in islet β-cells. These findings support the hypothesis that iPLA₂β induction under stress, as in diabetes, is a key component to amplifying β-cell death processes.
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Affiliation(s)
- Xiaoyong Lei
- Department of Cell, Developmental, and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Robert N. Bone
- Department of Pathology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Tomader Ali
- Department of Cell, Developmental, and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Mary Wohltmann
- Department of Medicine; Mass Spectrometry Resource; Division of Endocrinology, Metabolism and Lipid Research; Washington University School of Medicine; St. Louis, MO USA
| | - Ying Gai
- Department of Cell, Developmental, and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Karen J. Goodwin
- Department of Cell, Developmental, and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Alan E. Bohrer
- Department of Medicine; Mass Spectrometry Resource; Division of Endocrinology, Metabolism and Lipid Research; Washington University School of Medicine; St. Louis, MO USA
| | - John Turk
- Department of Medicine; Mass Spectrometry Resource; Division of Endocrinology, Metabolism and Lipid Research; Washington University School of Medicine; St. Louis, MO USA
| | - Sasanka Ramanadham
- Department of Cell, Developmental, and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
- Correspondence to: Sasanka Ramanadham,
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Steinauer J, Turk J, Simonson K, Landy U. O383 IMPLEMENTING RESIDENT TRAINING IN ABORTION: SUMMARY OF RYAN PROGRAMS IN OB-GYN RESIDENCY PROGRAMS IN THE US AND CANADA. Int J Gynaecol Obstet 2012. [DOI: 10.1016/s0020-7292(12)60813-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Steinauer J, Devaskar S, Cipriano S, Sufrin C, Perrucci A, Turk J. O656 VALUES CLARIFICATION ABOUT FAMILY PLANNING AS A TOOL TO INCREASE MEDICAL STUDENT PROFESSIONALISM. Int J Gynaecol Obstet 2012. [DOI: 10.1016/s0020-7292(12)61086-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Hsu FF, Pacheco S, Turk J, Purdy G. Structural determination of glycopeptidolipids of Mycobacterium smegmatis by high-resolution multiple-stage linear ion-trap mass spectrometry with electrospray ionization. J Mass Spectrom 2012; 47:1269-1281. [PMID: 23019158 PMCID: PMC3462375 DOI: 10.1002/jms.3070] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Glycopeptidolipids (GPLs) are abundant in the cell walls of different species of mycobacteria and consist of tripeptide-amino-alcohol core of D-Phe-D-allo-Thr-D-Ala-L-alaninol linked to 3-hydroxy or 3-methoxy C(26-34) fatty acyl chain at the N-terminal of D-Phe via amide linkage, and a 6-deoxytalose (6-dTal) and an O-methyl rhamnose residues, respectively, attach to D-allo-Thr and the terminal L-alaninol. They are important cell-surface antigens that are implicated in the pathogenesis of opportunistic mycobacteria belonging to the Mycobacterium avium complex. In this contribution, we described multiple-stage linear ion trap in conjunction with high-resolution mass spectrometry towards structural characterization of complex GPLs as [M + Na](+) ions isolated from Mycobacterium smegmatis, a fast-growing and non-pathogenic mycobacterial species. Following resonance excitation in an ion trap, MS(n) spectra of the [M + Na](+) ions of GPLs contained mainly b and y series ions that readily determine the peptide sequence. Fragment ions from MS(n) also afford locating the 6-dTal and O-methyl rhamnose residues linked to the D-allo-Thr and terminal L-alaninol of the peptide core, respectively, as well as recognizing the modifications of the glycosides, including their acetylation and methylation states and the presence of succinyl group. The GPL families consisting of 3-hydroxy fatty acyl and of 3-methoxy fatty acyl substituents are readily distinguishable. The MS profiles of the GPLs from cells are dependant on the conditions they were grown, and several isobaric isomers were identified for many of the molecular species. These multiple-stage mass spectrometric approaches give detailed structures of GPL in complex mixtures of which the isomeric structures are difficult to define using other analytical methods.
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Affiliation(s)
- Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism and Lipid Research, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Lodhi IJ, Yin L, Jensen-Urstad APL, Funai K, Coleman T, Baird JH, El Ramahi MK, Razani B, Song H, Fu-Hsu F, Turk J, Semenkovich CF. Inhibiting adipose tissue lipogenesis reprograms thermogenesis and PPARγ activation to decrease diet-induced obesity. Cell Metab 2012; 16:189-201. [PMID: 22863804 PMCID: PMC3467338 DOI: 10.1016/j.cmet.2012.06.013] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 03/07/2012] [Accepted: 06/22/2012] [Indexed: 10/28/2022]
Abstract
De novo lipogenesis in adipocytes, especially with high fat feeding, is poorly understood. We demonstrate that an adipocyte lipogenic pathway encompassing fatty acid synthase (FAS) and PexRAP (peroxisomal reductase activating PPARγ) modulates endogenous PPARγ activation and adiposity. Mice lacking FAS in adult adipose tissue manifested increased energy expenditure, increased brown fat-like adipocytes in subcutaneous adipose tissue, and resistance to diet-induced obesity. FAS knockdown in embryonic fibroblasts decreased PPARγ transcriptional activity and adipogenesis. FAS-dependent alkyl ether phosphatidylcholine species were associated with PPARγ and treatment of 3T3-L1 cells with one such ether lipid increased PPARγ transcriptional activity. PexRAP, a protein required for alkyl ether lipid synthesis, was associated with peroxisomes and induced during adipogenesis. PexRAP knockdown in cells decreased PPARγ transcriptional activity and adipogenesis. PexRAP knockdown in mice decreased expression of PPARγ-dependent genes and reduced diet-induced adiposity. These findings suggest that inhibiting PexRAP or related lipogenic enzymes could treat obesity and diabetes.
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Affiliation(s)
- Irfan J Lodhi
- Division of Endocrinology, Metabolism & Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA
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Liu S, Xie Z, Zhao Q, Pang H, Turk J, Calderon L, Su W, Zhao G, Xu H, Gong MC, Guo Z. Smooth muscle-specific expression of calcium-independent phospholipase A2β (iPLA2β) participates in the initiation and early progression of vascular inflammation and neointima formation. J Biol Chem 2012; 287:24739-53. [PMID: 22637477 DOI: 10.1074/jbc.m112.340216] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Whether group VIA phospholipase A(2) (iPLA(2)β) is involved in vascular inflammation and neointima formation is largely unknown. Here, we report that iPLA(2)β expression increases in the vascular tunica media upon carotid artery ligation and that neointima formation is suppressed by genetic deletion of iPLA(2)β or by inhibiting its activity or expression via perivascular delivery of bromoenol lactone or of antisense oligonucleotides, respectively. To investigate whether smooth muscle-specific iPLA(2)β is involved in neointima formation, we generated transgenic mice in which iPLA(2)β is expressed specifically in smooth muscle cells and demonstrate that smooth muscle-specific expression of iPLA(2)β exacerbates ligation-induced neointima formation and enhanced both production of proinflammatory cytokines and vascular infiltration by macrophages. With cultured vascular smooth muscle cell, angiotensin II, arachidonic acid, and TNF-α markedly induce increased expression of IL-6 and TNF-α mRNAs, all of which were suppressed by inhibiting iPLA(2)β activity or expression with bromoenol lactone, antisense oligonucleotides, and genetic deletion, respectively. Similar suppression also results from genetic deletion of 12/15-lipoxygenase or inhibiting its activity with nordihydroguaiaretic acid or luteolin. Expression of iPLA(2)β protein in cultured vascular smooth muscle cells was found to depend on the phenotypic state and to rise upon incubation with TNF-α. Our studies thus illustrate that smooth muscle cell-specific iPLA(2)β participates in the initiation and early progression of vascular inflammation and neointima formation and suggest that iPLA(2)β may represent a novel therapeutic target for preventing cardiovascular diseases.
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Affiliation(s)
- Shu Liu
- Department of Internal Medicine, University of Kentucky School of Medicine, Lexington, Kentucky 40536, USA
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Cheon Y, Kim HW, Igarashi M, Modi HR, Chang L, Ma K, Greenstein D, Wohltmann M, Turk J, Rapoport SI, Taha AY. Disturbed brain phospholipid and docosahexaenoic acid metabolism in calcium-independent phospholipase A(2)-VIA (iPLA(2)β)-knockout mice. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:1278-86. [PMID: 22349267 DOI: 10.1016/j.bbalip.2012.02.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 01/25/2012] [Accepted: 02/03/2012] [Indexed: 10/14/2022]
Abstract
Calcium-independent phospholipase A(2) group VIA (iPLA(2)β) releases docosahexaenoic acid (DHA) from phospholipids in vitro. Mutations in the iPLA(2)β gene, PLA2G6, are associated with dystonia-parkinsonism and infantile neuroaxonal dystrophy. To understand the role of iPLA(2)β in brain, we applied our in vivo kinetic method using radiolabeled DHA in 4 to 5-month-old wild type (iPLA(2)β(+/+)) and knockout (iPLA(2)β(-/-)) mice, and measured brain DHA kinetics, lipid concentrations, and expression of PLA(2), cyclooxygenase (COX), and lipoxygenase (LOX) enzymes. Compared to iPLA(2)β(+/+) mice, iPLA(2)β(-/-) mice showed decreased rates of incorporation of unesterified DHA from plasma into brain phospholipids, reduced concentrations of several fatty acids (including DHA) esterified in ethanolamine- and serine-glycerophospholipids, and increased lysophospholipid fatty acid concentrations. DHA turnover in brain phospholipids did not differ between genotypes. In iPLA(2)β(-/-) mice, brain levels of iPLA(2)β mRNA, protein, and activity were decreased, as was the iPLA(2)γ (Group VIB PLA(2)) mRNA level, while levels of secretory sPLA(2)-V mRNA, protein, and activity and cytosolic cPLA(2)-IVA mRNA were increased. Levels of COX-1 protein were decreased in brain, while COX-2 protein and mRNA were increased. Levels of 5-, 12-, and 15-LOX proteins did not differ significantly between genotypes. Thus, a genetic iPLA(2)β deficiency in mice is associated with reduced DHA metabolism, profound changes in lipid-metabolizing enzyme expression (demonstrating lack of redundancy) and of phospholipid fatty acid content of brain (particularly of DHA), which may be relevant to neurologic abnormalities in humans with PLA2G6 mutations.
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Affiliation(s)
- Yewon Cheon
- National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA.
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Hassiotis A, Turk J. Mental Health Needs in Adolescents with Intellectual Disabilities: Cross-Sectional Survey of a Service Sample. Journal of Applied Research in Intellectual Disabilities 2012; 25:252-61. [DOI: 10.1111/j.1468-3148.2011.00662.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Sharma J, Young DM, Marentette JO, Rastogi P, Turk J, McHowat J. Lung endothelial cell platelet-activating factor production and inflammatory cell adherence are increased in response to cigarette smoke component exposure. Am J Physiol Lung Cell Mol Physiol 2012; 302:L47-55. [PMID: 21984569 PMCID: PMC3349370 DOI: 10.1152/ajplung.00179.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 10/03/2011] [Indexed: 12/30/2022] Open
Abstract
An early event in the pathogenesis of emphysema is the development of inflammation associated with accumulation of polymorphonuclear leukocytes (PMN) in small airways, and inflammatory cell recruitment from the circulation involves migration across endothelial and epithelial cell barriers. Platelet-activating factor (PAF) promotes transendothelial migration in several vascular beds, and we postulated that increased PAF production in the airways of smokers might enhance inflammatory cell recruitment and exacerbate inflammation. To examine this possibility, we incubated human lung microvascular endothelial cells (HMVEC-L) with cigarette smoke extract (CSE) and found that CSE inhibits PAF-acetylhydrolase (PAF-AH) activity. This enhances HMVEC-L PAF production and PMN adherence, and adherence is blocked by PAF receptor antagonists (CV3988 or ginkgolide B). CSE also inhibited PAF-AH activity of lung endothelial cells isolated from wild-type (WT) and iPLA(2)β knockout mice, and with WT cells, CSE enhanced PAF production and RAW 264.7 cell adherence. In contrast, CSE did not affect PAF production or RAW 264.7 cell adherence to iPLA(2)β-null cells, suggesting that iPLA(2)β plays an important role in PAF production by lung endothelial cells. These findings suggest that inhibition of PAF-AH by components of cigarette smoke may initiate or exacerbate inflammatory lung disease by enhancing PAF production and promoting accumulation of inflammatory cells in small airways. In addition, iPLA(2)β is identified as a potential target for therapeutic interventions to reduce airway inflammation and the progression of chronic lung disease.
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Affiliation(s)
- Janhavi Sharma
- Department of Pathology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA
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Tatituri RVV, Brenner MB, Turk J, Hsu FF. Structural elucidation of diglycosyl diacylglycerol and monoglycosyl diacylglycerol from Streptococcus pneumoniae by multiple-stage linear ion-trap mass spectrometry with electrospray ionization. J Mass Spectrom 2012; 47:115-23. [PMID: 22282097 PMCID: PMC3712276 DOI: 10.1002/jms.2033] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The cell wall of the pathogenic bacterium Streptococcus pneumoniae contains glucopyranosyl diacylglycerol (GlcDAG) and galactoglucopyranosyldiacylglycerol (GalGlcDAG). The specific GlcDAG consisting of vaccenic acid substituent at sn-2 was recently identified as another glycolipid antigen family recognized by invariant natural killer T-cells. Here, we describe a linear ion-trap multiple-stage (MS(n) ) mass spectrometric approach towards structural analysis of GalGlcDAG and GlcDAG. Structural information derived from MS(n) (n = 2, 3) on the [M + Li](+) adduct ions desorbed by electrospray ionization affords identification of the fatty acid substituents, assignment of the fatty acyl groups on the glycerol backbone, as well as the location of double bond along the fatty acyl chain. The identification of the fatty acyl groups and determination of their regio-specificity were confirmed by MS(n) (n = 2, 3) on the [M + NH(4) ](+) ions. We establish the structures of GalGlcDAG and GlcDAG isolated from S. pneumoniae, in which the major species consists of a 16:1- or 18:1-fatty acid substituent mainly at sn-2, and the double bond of the fatty acid is located at ω-7 (n-7). More than one isomers were found for each mass in the family. This mass spectrometric approach provides a simple method to achieve structure identification of this important lipid family that would be very difficult to define using the traditional method.
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Affiliation(s)
- Raju Venkata Veera Tatituri
- Division of Rheumatology, Immunology, and Allergy, Brigham and Women’s Hospital, Harvard Medical School, 1 Jimmy Fund Way, Boston, Massachusetts 02115
| | - Michael B. Brenner
- Division of Rheumatology, Immunology, and Allergy, Brigham and Women’s Hospital, Harvard Medical School, 1 Jimmy Fund Way, Boston, Massachusetts 02115
| | - John Turk
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid research, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110
| | - Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid research, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110
- To whom the correspondence should be addressed: Dr. Fong-Fu Hsu, Box 8127, Washington University School of Medicine, 660 S Euclid, St. Louis, MO 63110. Tel: 314-362-0056,
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Song H, Wohltmann M, Tan M, Bao S, Ladenson JH, Turk J. Group VIA PLA2 (iPLA2β) is activated upstream of p38 mitogen-activated protein kinase (MAPK) in pancreatic islet β-cell signaling. J Biol Chem 2011; 287:5528-41. [PMID: 22194610 DOI: 10.1074/jbc.m111.285114] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Group VIA phospholipase A(2) (iPLA(2)β) in pancreatic islet β-cells participates in glucose-stimulated insulin secretion and sarco(endo)plasmic reticulum ATPase (SERCA) inhibitor-induced apoptosis, and both are attenuated by pharmacologic or genetic reductions in iPLA(2)β activity and amplified by iPLA(2)β overexpression. While exploring signaling events that occur downstream of iPLA(2)β activation, we found that p38 MAPK is activated by phosphorylation in INS-1 insulinoma cells and mouse pancreatic islets, that this increases with iPLA(2)β expression level, and that it is stimulated by the iPLA(2)β reaction product arachidonic acid. The insulin secretagogue D-glucose also stimulates β-cell p38 MAPK phosphorylation, and this is prevented by the iPLA(2)β inhibitor bromoenol lactone. Insulin secretion induced by d-glucose and forskolin is amplified by overexpressing iPLA(2)β in INS-1 cells and in mouse islets, and the p38 MAPK inhibitor PD169316 prevents both responses. The SERCA inhibitor thapsigargin also stimulates phosphorylation of both β-cell MAPK kinase isoforms and p38 MAPK, and bromoenol lactone prevents both events. Others have reported that iPLA(2)β products activate Rho family G-proteins that promote MAPK kinase activation via a mechanism inhibited by Clostridium difficile toxin B, which we find to inhibit thapsigargin-induced β-cell p38 MAPK phosphorylation. Thapsigargin-induced β-cell apoptosis and ceramide generation are also prevented by the p38 MAPK inhibitor PD169316. These observations indicate that p38 MAPK is activated downstream of iPLA(2)β in β-cells incubated with insulin secretagogues or thapsigargin, that this requires prior iPLA(2)β activation, and that p38 MAPK is involved in the β-cell functional responses of insulin secretion and apoptosis in which iPLA(2)β participates.
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Affiliation(s)
- Haowei Song
- Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Guo Y, Xu M, Deng B, Frontera JR, Kover KL, Aires D, Ding H, Carlson SE, Turk J, Wang W, Zhu H. Beta-Cell Injury in Ncb5or-null Mice is Exacerbated by Consumption of a High-Fat Diet. EUR J LIPID SCI TECH 2011; 114:233-243. [PMID: 22582025 DOI: 10.1002/ejlt.201100309] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
NADH-cytochrome b5 oxidoreductase (Ncb5or) in endoplasmic reticulum (ER) is involved in fatty acid metabolism, and Ncb5or(-/-) mice fed standard chow (SC) are insulin-sensitive but weigh less than wild type (WT) littermates. Ncb5or(-/-) mice develop hyperglycemia at about age 7 weeks due to β-cell dysfunction and loss associated with saturated fatty acid accumulation and manifestations of ER and oxidative stress. Here we report that when Ncb5or(-/-) mice born to heterozygous mothers fed a high fat (HF) diet continue to ingest HF, they weigh as much as SC-fed WT at age 5 weeks. By age 7 weeks, diabetes mellitus develops in all HF-fed vs. 68% of SC-fed Ncb5or(-/-) mice. Islet β-cell content in age 5-week Ncb5or(-/-) mice fed HF for 7 days is lower (53%) than for those fed SC (63%), and both are lower than for WT (75%, SC, vs. 69%, HF). Islet transcript levels for markers of mitochondrial biogenesis (PGC-1α) and ER stress (ATF6α) are higher in Ncb5or(-/-) than WT mice but not significantly affected by diet. Consuming a HF diet exacerbates Ncb5or(-/-) β-cell accumulation of intracellular saturated fatty acids and increases the frequency of ER distention from 11% (SC) to 47% (HF), thus accelerates β-cell injury in Ncb5or(-/-) mice.
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Affiliation(s)
- Ying Guo
- Department of Endocrinology, The Second Affiliated Hospital of Sun Yat-sen University, Guangzhou, China 510275
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Hsu FF, Wohlmann J, Turk J, Haas A. Structural definition of trehalose 6-monomycolates and trehalose 6,6'-dimycolates from the pathogen Rhodococcus equi by multiple-stage linear ion-trap mass spectrometry with electrospray ionization. J Am Soc Mass Spectrom 2011; 22:2160-2170. [PMID: 21972013 PMCID: PMC3938585 DOI: 10.1007/s13361-011-0240-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 08/18/2011] [Accepted: 08/22/2011] [Indexed: 05/31/2023]
Abstract
The cell wall of the pathogenic bacterium Rhodococcus equi (R. equi) contains abundant trehalose monomycolate (TMM) and trehalose dimycolate (TDM), the glycolipids bearing mycolic acids. Here, we describe multiple-stage (MS(n)) linear ion-trap (LIT) mass spectrometric approaches toward structural characterization of TMM and TDM desorbed as [M + Alk](+) (Alk = Na, Li) and as [M + X](-) (X = CH(3)CO(2), HCO(2)) ions by electrospray ionization (ESI). Upon MS(n) (n=2, 3, 4) on the [M + Alk](+) or the [M + X](-) adduct ions of TMM and TDM, abundant structurally informative fragment ions are readily available, permitting fast assignment of the length of the meromycolate chain and of the α-branch on the mycolyl residues. In this way, structures of TMM and TDM isolated from pathogenic R. equi strain 103 can be determined. Our results indicate that the major TMM and TDM molecules possess 6, and/or 6'-mycolyl groups that consist of mainly C14 and C16 α-branches with meromycolate branches ranging from C18 to C28, similar to the structures of the unbound mycolic acids found in the cell envelope. Up to 60 isobaric isomers varying in chain length of the α-branch and of the meromycolate backbone were observed for some of the TDM species in the mixture. This mass spectrometric approach provides a direct method that affords identification of various TMM and TDM isomers in a mixture of which the complexity of this lipid class has not been previously reported using other analytical methods.
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Affiliation(s)
- Fong-Fu Hsu
- Department of Internal Medicine, Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Washington University School of Medicine, 660 S Euclid, Box 8127, St. Louis, MO 63110, USA.
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Xie Z, Liu D, Liu S, Calderon L, Zhao G, Turk J, Guo Z. Identification of a cAMP-response element in the regulator of G-protein signaling-2 (RGS2) promoter as a key cis-regulatory element for RGS2 transcriptional regulation by angiotensin II in cultured vascular smooth muscles. J Biol Chem 2011; 286:44646-58. [PMID: 22057271 DOI: 10.1074/jbc.m111.265462] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mice deficient in regulator of G-protein signaling-2 (RGS2) have severe hypertension, and RGS2 genetic variations occur in hypertensive humans. A potentially important negative feedback loop in blood pressure homeostasis is that angiotensin II (Ang II) increases vascular smooth muscle cell (VSMC) RGS2 expression. We reported that Group VIA phospholipase A(2) (iPLA(2)β) is required for this response (Xie, Z., Gong, M. C., Su, W., Turk, J., and Guo, Z. (2007) J. Biol. Chem. 282, 25278-25289), but the specific molecular causes and consequences of iPLA(2)β activation are not known. Here we demonstrate that both protein kinases C (PKC) and A (PKA) participate in Ang II-induced VSMC RGS2 mRNA up-regulation, and that actions of PKC and PKA precede and follow iPLA(2)β activation, respectively. Moreover, we identified a conserved cAMP-response element (CRE) in the murine RGS2 promoter that is critical for cAMP-response element-binding protein (CREB) binding and RGS2 promoter activation. Forskolin-stimulated RGS2 mRNA up-regulation is inhibited by CREB sequestration or specific disruption of the CREB-RGS2 promoter interaction, and Ang II-induced CREB phosphorylation and nuclear localization are blocked by iPLA(2)β pharmacologic inhibition or genetic ablation. Ang II-induced intracellular cyclic AMP accumulation precedes CREB phosphorylation and is diminished by inhibiting iPLA(2), cyclooxygenase, or lipoxygenase. Moreover, three single nucleotide polymorphisms identified in hypertensive patients are located in the human RGS2 promoter CREB binding site. Point mutations corresponding to these single nucleotide polymorphisms interfere with stimulation of human RGS2 promoter activity by forskolin. Our studies thus delineate a negative feedback loop to attenuate Ang II signaling in VSMC with potential importance in blood pressure homeostasis and the pathogenesis of human essential hypertension.
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Affiliation(s)
- Zhongwen Xie
- Department of Physiology, University of Kentucky School of Medicine, Lexington, Kentucky 40536, USA
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Rhoades ER, Streeter C, Turk J, Hsu FF. Characterization of sulfolipids of Mycobacterium tuberculosis H37Rv by multiple-stage linear ion-trap high-resolution mass spectrometry with electrospray ionization reveals that the family of sulfolipid II predominates. Biochemistry 2011; 50:9135-47. [PMID: 21919534 DOI: 10.1021/bi2012178] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis, is unique among bacterial pathogens in that it contains a wide array of complex lipids and lipoglycans on its cell wall. Among them, the sulfated glycolipid, termed the sulfolipid, is thought to mediate specific host-pathogen interactions during infection. Sulfolipids (SLs), including sulfolipid I (SL-I) and sulfolipid II (SL-II), are 2,3,6,6'-tetraacyltrehalose 2'-sulfates. SL-I was identified as a family of homologous 2-palmitoyl(stearoyl)-3-phthioceranoyl-6,6'-bis(hydroxyphthioceranoy1)trehalose 2'-sulfates and was believed to be the principal sulfolipid of M. tuberculosis strain H37Rv. We cultured and extracted sulfolipids using various conditions, including those originally described, and employed high-resolution multiple-stage linear ion-trap mass spectrometry with electrospray ionization to characterize the structure of the principal SL. We revealed that SL-II, a family of homologous 2-stearoyl(palmitoyl)-3,6,6'-tris(hydroxyphthioceranoy1)trehalose 2'-sulfates, rather than SL-I is the principal sulfolipid class. We identified a great number of isomers resulting from permutation of the various hydroxyphthioceranoyl substituents at positions 6 and 6' of the trehalose backbone for each of the SL-II species in the entire family. We redefined the structure of this important lipid family that was misassigned using the traditional methods 40 years ago.
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Affiliation(s)
- Elizabeth R Rhoades
- Department of Microbiology and Immunology, C5 109 Vet Medical Center, Cornell University, Ithaca, New York 14853, United States
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Rosenstein M, Steinauer J, Turk J, Kerns J. A national survey of dilation and evacuation training in maternal–fetal medicine fellowships. Contraception 2011. [DOI: 10.1016/j.contraception.2011.05.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Kerns J, Steinauer J, Landy U, Turk J. Second-trimester abortion practice patterns and barriers to provision. Contraception 2011. [DOI: 10.1016/j.contraception.2011.05.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Wang W, Guo Y, Xu M, Huang HH, Novikova L, Larade K, Jiang ZG, Thayer TC, Frontera JR, Aires D, Ding H, Turk J, Mathews CE, Bunn HF, Stehno-Bittel L, Zhu H. Development of diabetes in lean Ncb5or-null mice is associated with manifestations of endoplasmic reticulum and oxidative stress in beta cells. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1532-41. [PMID: 21839170 DOI: 10.1016/j.bbadis.2011.07.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 07/15/2011] [Accepted: 07/26/2011] [Indexed: 01/01/2023]
Abstract
NADH-cytochrome b5 oxidoreductase (Ncb5or) is an endoplasmic reticulum (ER)-associated redox enzyme involved in fatty acid metabolism, and phenotypic abnormalities of Ncb5or(-/-) mice include diabetes and lipoatrophy. These mice are lean and insulin-sensitive but become hyperglycemic at age 7 weeks as a result of β-cell dysfunction and loss. Here we examine early cellular and molecular events associated with manifestations of β-cell defects in Ncb5or(-/-) mice. We observe lower islet β-cell content in pancreata at age 4 weeks and prominent ER distention in β-cells by age 5 weeks. Ultrastructural changes progress rapidly in severity from age 5 to 6 weeks, and their frequency rises from 10% of β-cells at 5 weeks to 33% at 6 weeks. These changes correlate temporally with the onset of diabetes. ER stress responses and lipid load in Ncb5or(-/-) β-cells were assessed with isolated islets from mice at age 5 weeks. Expression levels of the stress marker protein Grp78/BiP and of phosphorylated eIF2α protein were found to be reduced, although their transcript levels did not decline. This pattern stands in contrast to the canonical unfolded protein response. Ncb5or(-/-) β-cells also accumulated higher intracellular levels of palmitate and other free fatty acids and exhibited greater reactive oxygen species production than wild-type cells. An alloxan-susceptible genetic background was found to confer accelerated onset of diabetes in Ncb5or(-/-) mice. These findings provide the first direct evidence that manifestations of diabetes in lean Ncb5or(-/-) mice involve saturated free fatty acid overload of β-cells and ER and oxidative stress responses.
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Affiliation(s)
- Wenfang Wang
- Department of Physical Therapy and Rehabilitation Science, The University of Kansas Medical Center, Kansas City, KS 66160, USA
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