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Yuan Y, Wang P, Zhang H, Liu Y. Identification of M2 Macrophage-Related Key Genes in Advanced Atherosclerotic Plaques by Network-Based Analysis. J Cardiovasc Pharmacol 2024; 83:276-288. [PMID: 38194604 DOI: 10.1097/fjc.0000000000001528] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 12/05/2023] [Indexed: 01/11/2024]
Abstract
ABSTRACT Atherosclerotic plaque accounts for major adverse cardiovascular events because of its vulnerability. The classically activated macrophage (M1) and alternatively activated macrophage (M2) are implicated in the progression and regression of plaque, respectively. However, the therapeutic targets related to M2 macrophages still remain largely elusive. In this study, cell-type identification by estimating relative subsets of RNA transcripts and weighted gene coexpression network analysis algorithms were used to establish a weighted gene coexpression network for identifying M2 macrophage-related hub genes using GSE43292 data set. The results showed that genes were classified into 7 modules, with the blue module (Cor = 0.67, P = 3e-05) being the one that was most related to M2 macrophage infiltration in advanced plaques, and then 99 hub genes were identified from blue module. Meanwhile, 1289 differentially expressed genes were produced in GSE43292 data set. Subsequently, the intersection genes of hub genes and differentially expressed genes, including AKTIP , ASPN , FAM26E , RAB23 , PLS3 , and PLSCR4 , were obtained by Venn diagrams and named as key genes. Further validation using data sets GSE100927 and GSE41571 showed that 6 key genes all downregulated in advanced and vulnerable plaques compared with early and stable plaque samples (|Log2 (fold change)| > 0.5, P < 0.05 or 0.001), respectively. Receiver operator characteristic curve analysis indicated that the 6 key genes might have potential diagnostic value. The validation of key genes in the model in vitro and in vivo also demonstrated decreased mRNA expressions of AKTIP , ASPN , FAM26E , RAB23 , PLS3 , and PLSCR4 ( P < 0.05 or 0.001). Collectively, we identified AKTIP, ASPN, FAM26E, RAB23, PLS3, and PLSCR4 as M2 macrophage-related key genes during atherosclerotic progression, proposing potential intervention targets for advanced atherosclerotic plaques.
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Affiliation(s)
- Yao Yuan
- Department of Pharmacology, College of Pharmacy, Army Medical University (Military Medical University), Chongqing, China
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Shi L, Hu M, Lai W, Yi W, Liu Z, Sun H, Li F, Yan S. Detection of genomic variations and selection signatures in Wagyu using whole-genome sequencing data. Anim Genet 2023; 54:808-812. [PMID: 37792466 DOI: 10.1111/age.13364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 04/28/2023] [Revised: 07/28/2023] [Accepted: 09/21/2023] [Indexed: 10/05/2023]
Abstract
Wagyu is recognized for producing marbled beef with high nutritional value and flavor. Reportedly, Wagyu has been widely used to improve the meat quality of local breeds around the world. However, studies on the genetic mechanism of meat quality in Wagyu at the whole-genome level are rarely reported. Here, whole-genome sequencing data of 11 Wagyu and 115 other individuals were used to explore the genomic variations and genes under selection pressure in Wagyu. A total of 31 349 non-synonymous variants and 53 102 synonymous variants were identified in Wagyu. The population structure analysis showed that Wagyu had the closest genetic relationship with Mishima-Ushi cattle and was apparently separated from other cattle breeds. Then, composite likelihood ratio (CLR), integrated haplotype score, fixation index and cross-population composite likelihood ratio (XP-CLR) tests were performed to identify the candidate genes under positive selection in Wagyu. In total, 770 regions containing 312 genes were identified by at least three methods. Among them, 97 regions containing 27 genes were detected by all four methods. We specifically illustrate a list of interesting genes, including LRP2BP, GAA, CACNG6, CXADR, GPCPD1, KLF2, KLF13, SOX5, MYBPC1, SLC25A10, ATP8A1 and MYH15, which are associated with lipid metabolism, fat deposition, muscle development, bone development, feed intake and growth traits in Wagyu. This is the first study to explore the genomic variations and selection signatures of Wagyu at the whole-genome level. These results will provide significant help to beef cattle improvement and breeding.
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Affiliation(s)
- Lulu Shi
- College of Animal Science, Jilin University, Changchun, China
| | - Mingyue Hu
- College of Animal Science, Jilin University, Changchun, China
| | - Weining Lai
- College of Animal Science, Jilin University, Changchun, China
| | - Wenfeng Yi
- College of Animal Science, Jilin University, Changchun, China
| | - Zhengxi Liu
- College of Animal Science, Jilin University, Changchun, China
| | - Hao Sun
- College of Animal Science, Jilin University, Changchun, China
| | - Feng Li
- Shandong Binzhou Animal Science and Veterinary Medicine Academy, Binzhou, China
| | - Shouqing Yan
- College of Animal Science, Jilin University, Changchun, China
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3
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Li M. Fortifying immunity: PLSCR1 picks battle against SARS-CoV-2. Cell Host Microbe 2023; 31:1417-1419. [PMID: 37708846 DOI: 10.1016/j.chom.2023.08.014] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 08/15/2023] [Accepted: 08/17/2023] [Indexed: 09/16/2023]
Abstract
Interferons (IFNs) and interferon-stimulated genes (ISGs) are the major players in the host innate immunity against viral infection. In a recent Nature paper, Xu et al. identified phospholipid scramblase 1 (PLSCR1) as a novel ISG that restricts severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by blocking virus-cell fusion.
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Affiliation(s)
- Minghua Li
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Center for Tropical Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA.
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Wu N, Veillette A. Lipid scrambling in immunology: why it is important. Cell Mol Immunol 2023; 20:1081-1083. [PMID: 37012395 PMCID: PMC10071233 DOI: 10.1038/s41423-023-01009-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 04/05/2023] Open
Affiliation(s)
- Ning Wu
- The First Affiliated Hospital of Anhui Medical University, Clinical Immunology Institute, Anhui Medical University, Hefei, Anhui, China.
| | - André Veillette
- Laboratory of Molecular Oncology, Institut de recherches cliniques de Montréal (IRCM), Montréal, QC, H2W1R7, Canada.
- Department of Medicine, University of Montréal, Montréal, QC, H3T 1J4, Canada.
- Department of Medicine, McGill University, Montréal, QC, H3G 1Y6, Canada.
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Banet N, Masnick M, Quddus MR. Evaluation of Saccharomyces cerevisiae -like 1 (SEC14L1) in Gynecologic Malignancies Shows Overexpression in Endometrial Serous Carcinoma. Int J Gynecol Pathol 2023; 42:136-142. [PMID: 35283446 DOI: 10.1097/pgp.0000000000000866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Saccharomyces cerevisiae -like 1 ( SEC14L1 ) is a member of the SEC14 family and is involved in liposoluble vitamin transfer, and in a large cohort of breast cancer cases, was one of the genes most significantly associated with lymphovascular invasion (LVI), and had a significant relationship with human epidermal growth factor receptor 2 status, survival, and histologic grade. In this study, 111 separate gynecologic tumors were studied for SEC14L1 protein expression, including: uterine adenosarcoma, ovarian clear cell carcinoma, endometrial stromal sarcoma, endometrioid carcinoma of the uterus, high-grade serous carcinoma, ovarian endometrioid carcinoma, uterine leiomyosarcoma, low-grade serous carcinoma, uterine carcinosarcoma, and uterine serous carcinoma (USC). Overall, LVI was noted in 31/111 (28%) cases, highest in uterine carcinosarcoma (5/11; 45%), high-grade serous carcinoma (9/21; 43%), and ovarian clear cell carcinoma (4/10; 40%). SEC14L1 was positive in 25/111 (23%) cases; the highest percentage and only statistically significant finding by tumor type was USC at 9/12 (75%) cases positive. No relation between LVI or survival and SEC14L1 expression was noted. The relation between USC, a tumor known to show human epidermal growth factor receptor 2 overexpression and SEC14L1 is a novel finding, the significance of which warrants further study.
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Abstract
Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Here, we review the impact of high-density lipoproteins (HDL) on sepsis from the perspective of biochemistry and pathophysiology, epidemiological research, and intervention studies in animals. Pathogen lipid moieties are major ligands for innate immunity receptors, such as toll-like receptors. The binding of pathogen-associated lipids to lipoproteins leads to sequestration, neutralization, and inactivation of their pro-inflammatory effects. Lipoproteins constitute an arm of the innate immune system. Pathogen-associated lipids can be removed from the body via the reverse lipopolysaccharide transport pathway in which HDL play a key role. Independent of the capacity for sequestration, the direct anti-inflammatory effects of HDL may counteract the development of sepsis. Mendelian randomization research using genetic variants associated with HDL cholesterol as an instrumental variable was consistent with a probable causal relationship between increased HDL cholesterol levels and decreased risk of infectious hospitalizations. Low HDL cholesterol independently predicts an adverse prognosis in sepsis both in observational epidemiology and in Mendelian randomization studies. Several HDL-associated enzymes, including phospholipid transfer protein (PLTP) and cholesterol ester transfer protein (CETP), undergo profound changes during sepsis. Potential HDL-directed interventions for treatment of sepsis include apolipoprotein A-I-based therapies, recombinant PLTP, and CETP inhibition.
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Affiliation(s)
- Bart De Geest
- Centre for Molecular and Vascular Biology, Catholic University of Leuven, 3000 Leuven, Belgium
- Correspondence: ; Tel.: +32-16-372059
| | - Mudit Mishra
- Department of Cardiothoracic Surgery, University Medical Centre Utrecht, 3508 GA Utrecht, The Netherlands
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Cheshenko N, Bonanno JB, Hoffmann HH, Jangra RK, Chandran K, Rice CM, Almo SC, Herold BC. Cell-impermeable staurosporine analog targets extracellular kinases to inhibit HSV and SARS-CoV-2. Commun Biol 2022; 5:1096. [PMID: 36245045 PMCID: PMC9569420 DOI: 10.1038/s42003-022-04067-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 10/04/2022] [Indexed: 11/09/2022] Open
Abstract
Herpes simplex virus (HSV) receptor engagement activates phospholipid scramblase triggering Akt translocation to the outer leaflet of the plasma membrane where its subsequent phosphorylation promotes viral entry. We hypothesize that this previously unrecognized outside-inside signaling pathway is employed by other viruses and that cell-impermeable kinase inhibitors could provide novel antivirals. We synthesized a cell-impermeable analog of staurosporine, CIMSS, which inhibited outer membrane HSV-induced Akt phosphorylation and blocked viral entry without inducing apoptosis. CIMSS also blocked the phosphorylation of 3-phosphoinositide dependent protein kinase 1 and phospholipase C gamma, which were both detected at the outer leaflet following HSV exposure. Moreover, vesicular stomatitis virus pseudotyped with SARS-CoV-2 spike protein (VSV-S), but not native VSV or VSV pseudotyped with Ebola virus glycoprotein, triggered this scramblase-Akt outer membrane signaling pathway. VSV-S and native SARS-CoV-2 infection were inhibited by CIMSS. Thus, CIMSS uncovered unique extracellular kinase processes linked to HSV and SARS-CoV-2 entry.
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Affiliation(s)
- Natalia Cheshenko
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Jeffrey B Bonanno
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Hans-Heinrich Hoffmann
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA
| | - Rohit K Jangra
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
- Department of Microbiology and Immunology, Louisiana State University Health Science Center-Shreveport, Shreveport, LA, USA
| | - Kartik Chandran
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA
| | - Steven C Almo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Betsy C Herold
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY, USA.
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA.
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8
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Kousathanas A, Pairo-Castineira E, Rawlik K, Stuckey A, Odhams CA, Walker S, Russell CD, Malinauskas T, Wu Y, Millar J, Shen X, Elliott KS, Griffiths F, Oosthuyzen W, Morrice K, Keating S, Wang B, Rhodes D, Klaric L, Zechner M, Parkinson N, Siddiq A, Goddard P, Donovan S, Maslove D, Nichol A, Semple MG, Zainy T, Maleady-Crowe F, Todd L, Salehi S, Knight J, Elgar G, Chan G, Arumugam P, Patch C, Rendon A, Bentley D, Kingsley C, Kosmicki JA, Horowitz JE, Baras A, Abecasis GR, Ferreira MAR, Justice A, Mirshahi T, Oetjens M, Rader DJ, Ritchie MD, Verma A, Fowler TA, Shankar-Hari M, Summers C, Hinds C, Horby P, Ling L, McAuley D, Montgomery H, Openshaw PJM, Elliott P, Walsh T, Tenesa A, Fawkes A, Murphy L, Rowan K, Ponting CP, Vitart V, Wilson JF, Yang J, Bretherick AD, Scott RH, Hendry SC, Moutsianas L, Law A, Caulfield MJ, Baillie JK. Whole-genome sequencing reveals host factors underlying critical COVID-19. Nature 2022; 607:97-103. [PMID: 35255492 PMCID: PMC9259496 DOI: 10.1038/s41586-022-04576-6] [Citation(s) in RCA: 132] [Impact Index Per Article: 66.0] [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] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 02/23/2022] [Indexed: 12/15/2022]
Abstract
Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2-4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes-including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)-in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease.
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Affiliation(s)
| | - Erola Pairo-Castineira
- Roslin Institute, University of Edinburgh, Edinburgh, UK
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - Konrad Rawlik
- Roslin Institute, University of Edinburgh, Edinburgh, UK
| | | | | | | | - Clark D Russell
- Roslin Institute, University of Edinburgh, Edinburgh, UK
- Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Tomas Malinauskas
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Yang Wu
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | | | - Xia Shen
- Biostatistics Group, Greater Bay Area Institute of Precision Medicine (Guangzhou), Fudan University, Guangzhou, China
- Centre for Global Health Research, Usher Institute of Population Health Sciences and Informatics, Edinburgh, UK
| | | | | | | | - Kirstie Morrice
- Edinburgh Clinical Research Facility, Western General Hospital, University of Edinburgh, Edinburgh, UK
| | - Sean Keating
- Intensive Care Unit, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - Bo Wang
- Roslin Institute, University of Edinburgh, Edinburgh, UK
| | | | - Lucija Klaric
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - Marie Zechner
- Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Nick Parkinson
- Roslin Institute, University of Edinburgh, Edinburgh, UK
| | | | | | | | - David Maslove
- Department of Critical Care Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Alistair Nichol
- Clinical Research Centre at St Vincent's University Hospital, University College Dublin, Dublin, Ireland
| | - Malcolm G Semple
- NIHR Health Protection Research Unit for Emerging and Zoonotic Infections, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
- Respiratory Medicine and Institute in the Park, Alder Hey Children's Hospital and University of Liverpool, Liverpool, UK
| | | | | | | | | | - Julian Knight
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | | | | | | | | | | | | | | | | | | | - Aris Baras
- Regeneron Genetics Center, Tarrytown, NY, USA
| | | | | | | | | | | | - Daniel J Rader
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Marylyn D Ritchie
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Anurag Verma
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Tom A Fowler
- Genomics England, London, UK
- Test and Trace, the Health Security Agency, Department of Health and Social Care, London, UK
| | - Manu Shankar-Hari
- Department of Intensive Care Medicine, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | | | - Charles Hinds
- William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Peter Horby
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Lowell Ling
- Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - Danny McAuley
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, UK
- Department of Intensive Care Medicine, Royal Victoria Hospital, Belfast, UK
| | | | - Peter J M Openshaw
- National Heart and Lung Institute, Imperial College London, London, UK
- Imperial College Healthcare NHS Trust: London, London, UK
| | | | - Timothy Walsh
- Intensive Care Unit, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - Albert Tenesa
- Roslin Institute, University of Edinburgh, Edinburgh, UK
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
- Centre for Global Health Research, Usher Institute of Population Health Sciences and Informatics, Edinburgh, UK
| | - Angie Fawkes
- Edinburgh Clinical Research Facility, Western General Hospital, University of Edinburgh, Edinburgh, UK
| | - Lee Murphy
- Edinburgh Clinical Research Facility, Western General Hospital, University of Edinburgh, Edinburgh, UK
| | - Kathy Rowan
- Intensive Care National Audit and Research Centre, London, UK
| | - Chris P Ponting
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - Veronique Vitart
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - James F Wilson
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
- Centre for Global Health Research, Usher Institute of Population Health Sciences and Informatics, Edinburgh, UK
| | - Jian Yang
- School of Life Sciences, Westlake University, Hangzhou, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, China
| | - Andrew D Bretherick
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - Richard H Scott
- Genomics England, London, UK
- Great Ormond Street Hospital, London, UK
| | | | | | - Andy Law
- Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Mark J Caulfield
- Genomics England, London, UK.
- William Harvey Research Institute, Queen Mary University of London, London, UK.
| | - J Kenneth Baillie
- Roslin Institute, University of Edinburgh, Edinburgh, UK.
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK.
- Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK.
- Intensive Care Unit, Royal Infirmary of Edinburgh, Edinburgh, UK.
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Jiang C, Jiang W. AGTR1, PLTP, and SCG2 associated with immune genes and immune cell infiltration in calcific aortic valve stenosis: analysis from integrated bioinformatics and machine learning. Math Biosci Eng 2022; 19:3787-3802. [PMID: 35341274 DOI: 10.3934/mbe.2022174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Background: Calcific aortic valve stenosis (CAVS) is a crucial cardiovascular disease facing aging societies. Our research attempts to identify immune-related genes through bioinformatics and machine learning analysis. Two machine learning strategies include Least Absolute Shrinkage Selection Operator (LASSO) and Support Vector Machine Recursive Feature Elimination (SVM-RFE). In addition, we deeply explore the role of immune cell infiltration in CAVS, aiming to study the potential therapeutic targets of CAVS and explore possible drugs. Methods: Download three data sets related to CAVS from the Gene Expression Omnibus. Gene set variation analysis (GSVA) looks for potential mechanisms, determines differentially expressed immune-related genes (DEIRGs) by combining the ImmPort database with CAVS differential genes, and explores the functions and pathways of enrichment. Two machine learning methods, LASSO and SVM-RFE, screen key immune signals and validate them in external data sets. Single-sample GSEA (ssGSEA) and CIBERSORT analyze the subtypes of immune infiltrating cells and integrate the analysis with DEIRGs and key immune signals. Finally, the possible targeted drugs are analyzed through the Connectivity Map (CMap). Results: GSVA analysis of the gene set suggests that it is highly correlated with multiple immune pathways. 266 differential genes (DEGs) integrate with immune genes to obtain 71 DEIRGs. Enrichment analysis found that DEIRGs are related to oxidative stress, synaptic membrane components, receptor activity, and a variety of cardiovascular diseases and immune pathways. Angiotensin II Receptor Type 1(AGTR1), Phospholipid Transfer Protein (PLTP), Secretogranin II (SCG2) are identified as key immune signals of CAVS by machine learning. Immune infiltration found that B cells naï ve and Macrophages M2 are less in CAVS, while Macrophages M0 is more in CAVS. Simultaneously, AGTR1, PLTP, SCG2 are highly correlated with a variety of immune cell subtypes. CMap analysis found that isoliquiritigenin, parthenolide, and pyrrolidine-dithiocarbamate are the top three targeted drugs related to CAVS immunity. Conclusion: The key immune signals, immune infiltration and potential drugs obtained from the research play a vital role in the pathophysiological progress of CAVS.
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Affiliation(s)
- Chenyang Jiang
- Department of Cardiology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
| | - Weidong Jiang
- Department of Cardiology, Nantong Traditional Chinese Medicine Hospital, Nantong 226001, China
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10
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Wang J, Li C, Jiang Y, Zheng H, Li D, Liang Y, Deng W, Zhang D. Effect of ceramide-1-phosphate transfer protein on intestinal bacterial translocation in severe acute pancreatitis. Clin Res Hepatol Gastroenterol 2017; 41:86-92. [PMID: 27637474 DOI: 10.1016/j.clinre.2016.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 07/23/2016] [Accepted: 08/10/2016] [Indexed: 02/04/2023]
Abstract
BACKGROUND AND OBJECTIVE The aim of the study was to investigate the effects of ceramide-1-phosphate transfer protein (CPTP) on the intestinal epithelial tight junction proteins in patients with severe acute pancreatitis (SAP). METHODS Fifty patients with SAP were classified into two groups according to the presence of bacterial translocation (BT) in the blood. Thirty healthy individuals were included in the control group. The presence of BT was analyzed by polymerase chain reaction. The expression of tight junction proteins and CPTP was determined using immunohistochemistry and western blotting. RESULTS Bacterial DNA was detected in the peripheral blood of 62.0% of the patients with SAP. The expression of CPTP and tight junction proteins in SAP patients was lower than that in healthy controls. Among the patients with SAP, those positive for BT(+) showed a lower level of CPTP and occluding (OC) and zonula occludens-1 (ZO-1) expression and a higher level of IVA cPLA2 expression than BT(-) patients. Moreover, the expression of CPTP was significantly associated with ZO-1 and showed a negative correlation with expression of IVA cPLA2 in SAP-BT(+) patients. CONCLUSIONS CPTP affects the expression of tight junction proteins and may protects the intestinal epithelial barrier by downregulating the expression of IVA cPLA2.
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Affiliation(s)
- Jiang Wang
- Qingdao University, Qingdao Municipal Hospital, Center of Colon and Rectum, n(o) 1 Jiaozhou Road, Qingdao 266011, Shandong Province, China
| | - Chang Li
- Qingdao University, Qingdao Municipal Hospital, Center of Colon and Rectum, n(o) 1 Jiaozhou Road, Qingdao 266011, Shandong Province, China
| | - Yingjian Jiang
- Qingdao University, Qingdao Municipal Hospital, Center of Colon and Rectum, n(o) 1 Jiaozhou Road, Qingdao 266011, Shandong Province, China
| | - Hongmei Zheng
- Qingdao University, Qingdao Municipal Hospital, Center of Colon and Rectum, n(o) 1 Jiaozhou Road, Qingdao 266011, Shandong Province, China
| | - Dehui Li
- Qingdao University, Qingdao Municipal Hospital, Center of Colon and Rectum, n(o) 1 Jiaozhou Road, Qingdao 266011, Shandong Province, China
| | - Yibo Liang
- Qingdao University, Qingdao Municipal Hospital, Center of Colon and Rectum, n(o) 1 Jiaozhou Road, Qingdao 266011, Shandong Province, China
| | - Wensheng Deng
- Pingxiang People's Hospital, Center of Anorectal Branch, Pingxiang 337000, Jiangxi Province, China
| | - Dianliang Zhang
- Qingdao University, Qingdao Municipal Hospital, Center of Colon and Rectum, n(o) 1 Jiaozhou Road, Qingdao 266011, Shandong Province, China.
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Tu AY, Cheung MC, Zhu X, Knopp RH, Albers JJ. Low-Density Lipoprotein Inhibits Secretion of Phospholipid Transfer Protein in Human Trophoblastic BeWo Cells. Exp Biol Med (Maywood) 2016; 229:1046-52. [PMID: 15522841 DOI: 10.1177/153537020422901009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 11/17/2022] Open
Abstract
Human plasma phospholipid transfer protein (PLTP) plays an important role in lipoprotein metabolism. In this study, we investigated the effects of lipoproteins on the secretion of PLTP in cultured BeWo choriocarcinoma cells. Low-density lipoproteins (LDLs) decreased PLTP secretion in a dose- and time-dependent manner, whereas very low density lipoproteins and high-density lipoproteins (HDLs) had little effect. LDL suppression of PLTP secretion was not altered by the inhibition of both LDL receptor and LDL receptor–related protein with receptor-associated protein. Mitogen-activated protein kinase (MAPK) kinase (MEK) inhibitor, U0126, could abolish the LDL-mediated inhibition of PLTP secretion. Furthermore, LDL, but not HDL, could stimulate the expression of MAPK phosphatase-1 (MKP-1) in BeWo cells that resulted in the inactivation of p44/p42 extracellular signal-regulated kinase (ERK) 1 and 2, the family members of MAPKs. These results support the conclusion that LDL-mediated suppression of PLTP secretion in BeWo cells is through a LDL receptor-independent MAPK signaling pathway.
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Affiliation(s)
- An-Yue Tu
- Department of Medicine, Northwest Lipid Research Laboratories, Northwest Lipid Research Clinic, Division of Metabolism, Endocrinology, and Nutrition, University of Washington, 2121 N 35th Street, Seattle, WA 98103, USA.
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12
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Abstract
Scramblases translocate phospholipids across the membrane bilayer bidirectionally in an ATP-independent manner. The first scramblase to be identified and biochemically verified was opsin, the apoprotein of the photoreceptor rhodopsin. Rhodopsin is a G protein-coupled receptor localized in rod photoreceptor disc membranes of the retina where it is responsible for the perception of light. Rhodopsin's scramblase activity does not depend on its ligand 11-cis-retinal, i.e., the apoprotein opsin is also active as a scramblase. Although constitutive and regulated phospholipid scrambling play an important role in cell physiology, only a few phospholipid scramblases have been identified so far besides opsin. Here we describe a fluorescence-based assay of opsin's scramblase activity. Opsin is reconstituted into large unilamellar liposomes composed of phosphatidylcholine, phosphatidylglycerol and a trace quantity of fluorescent NBD-labeled PC (1-palmitoyl-2-{6-[7-nitro-2-1,3-benzoxadiazole-4-yl)amino]hexanoyl}-sn-glycero-3-phosphocholine). Scramblase activity is determined by measuring the extent to which NBD-PC molecules located in the inner leaflet of the vesicle are able to access the outer leaflet where their fluorescence is chemically eliminated by a reducing agent that cannot cross the membrane. The methods we describe have general applicability and can be used to identify and characterize scramblase activities of other membrane proteins.
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Affiliation(s)
- Birgit Ploier
- Department of Biochemistry, Weill Cornell Medical College
| | - Anant K Menon
- Department of Biochemistry, Weill Cornell Medical College;
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Gupta A, Montepiedra G, Gupte A, Zeldow B, Jubulis J, Detrick B, Violari A, Madhi S, Bobat R, Cotton M, Mitchell C, Spector S. Low Vitamin-D Levels Combined with PKP3-SIGIRR-TMEM16J Host Variants Is Associated with Tuberculosis and Death in HIV-Infected and -Exposed Infants. PLoS One 2016; 11:e0148649. [PMID: 26872154 PMCID: PMC4752266 DOI: 10.1371/journal.pone.0148649] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 01/18/2016] [Indexed: 12/13/2022] Open
Abstract
Background This study examined the associations of 25-hydroxyvitamin D and specific host genetic variants that affect vitamin D levels or its effects on immune function, with the risk of TB or mortality in children. Methods A case-cohort sample of 466 South African infants enrolled in P1041 trial (NCT00080119) underwent 25-hydroxyvitamin D testing by chemiluminescent immunoassay. Single nucleotide polymorphisms (SNPs) that alter the effect of vitamin D [e.g. vitamin D receptor (VDR)], vitamin D levels [e.g. vitamin D binding protein (VDBP)], or toll like receptor (TLR) expression (SIGIRR including adjacent genes PKP3 and TMEM16J) were identified by real-time PCR. Outcomes were time to TB, and to the composite of TB or death by 192 weeks of follow-up. Effect modification between vitamin D status and SNPs for outcomes was assessed. Findings Median age at 25-hydroxyvitamin D determination was 8 months; 11% were breastfed, 51% were HIV-infected and 26% had low 25-hydroxyvitamin D (<32ng/mL). By 192 weeks, 138 incident TB cases (43 definite/probable, and 95 possible) and 26 deaths occurred. Adjusting for HIV status and potential confounders, low 25-hydroxyvitamin D was associated with any TB (adjusted hazard ratio [aHR] 1.76, 95% CI 1.01–3.05; p = 0.046) and any TB or death (aHR 1.76, 95% CI 1.03–3.00; p = 0.038). Children with low 25-hydroxyvitamin D and TMEM 16J rs7111432-AA or PKP3 rs10902158-GG were at increased risk for probable/definite TB or death (aHR 8.12 and 4.83, p<0.05) and any TB or death (aHR 4.78 and 3.26, p<0.005) respectively; SNPs in VDBP, VDR, and vitamin D precursor or hydroxylation genes were not. There was significant interaction between low 25-hydroxyvitamin D and, TMEM 16J rs7111432-AA (p = 0.04) and PKP3 rs10902158-GG (p = 0.02) SNPs. Conclusions Two novel SNPs, thought to be associated with innate immunity, in combination with low vitamin D levels were identified as increasing a young child’s risk of developing TB disease or death. Identifying high-risk children and providing targeted interventions such as vitamin D supplementation may be beneficial. Trial Registration ClinicalTrials.gov NCT00080119
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Affiliation(s)
- Amita Gupta
- Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States of America
- * E-mail: (A. Gupta); (SS)
| | - Grace Montepiedra
- Harvard School of Public Health, Boston, MA, United States of America
| | - Akshay Gupte
- Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Bret Zeldow
- Harvard School of Public Health, Boston, MA, United States of America
| | - Jennifer Jubulis
- Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Barbara Detrick
- Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Avy Violari
- Perinatal HIV Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Shabir Madhi
- Medical Research Council: Respiratory and Meningeal Pathogens Research Unit and Department of Science and Technology/National Research Foundation: Vaccine Preventable Diseases, University of the Witwatersrand, Johannesburg, South Africa
| | - Raziya Bobat
- Department of Pediatrics, University of KwaZulu-Natal, Durban, South Africa
| | - Mark Cotton
- Children’s Infectious Diseases Clinical Research Unit, Faculty of Medicine and Health Sciences, Stellenbosch University, Stellenbosch, South Africa
| | | | - Stephen Spector
- University of California San Diego, La Jolla, CA, United States of America, and Rady Children’s Hospital, San Diego, CA, United States of America
- * E-mail: (A. Gupta); (SS)
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14
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Harper MT, Poole AW. Chloride channels are necessary for full platelet phosphatidylserine exposure and procoagulant activity. Cell Death Dis 2013; 4:e969. [PMID: 24357800 PMCID: PMC3877565 DOI: 10.1038/cddis.2013.495] [Citation(s) in RCA: 42] [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] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/16/2013] [Accepted: 11/08/2013] [Indexed: 02/07/2023]
Abstract
Platelets enhance thrombin generation at sites of vascular injury by exposing phosphatidylserine during necrosis-like cell death. Anoctamin 6 (Ano6) is required for Ca(2+)-dependent phosphatidylserine exposure and is defective in patients with Scott syndrome, a rare bleeding disorder. Ano6 may also form Cl(-) channels, though the role of Cl(-) fluxes in platelet procoagulant activity has not been explored. We found that Cl(-) channel blockers or removal of extracellular Cl(-) inhibited agonist-induced phosphatidylserine exposure. However, this was not due to direct inhibition of Ca(2+)-dependent scrambling since Ca(2+) ionophore-induced phosphatidylserine exposure was normal. This implies that the role of Ano6 in Ca(2+-)dependent PS exposure is likely to differ from any putative function of Ano6 as a Cl(-) channel. Instead, Cl(-) channel blockade inhibited agonist-induced Ca(2+) entry. Importantly, Cl(-) channel blockers also prevented agonist-induced membrane hyperpolarization, resulting in depolarization. We propose that Cl(-) entry through Cl(-) channels is required for this hyperpolarization, maintaining the driving force for Ca(2+) entry and triggering full phosphatidylserine exposure. This demonstrates a novel role for Cl(-) channels in controlling platelet death and procoagulant activity.
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Affiliation(s)
- M T Harper
- School of Physiology and Pharmacology, Bristol Heart Institute, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - A W Poole
- School of Physiology and Pharmacology, Bristol Heart Institute, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
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Groen A, Romero MR, Kunne C, Hoosdally SJ, Dixon PH, Wooding C, Williamson C, Seppen J, Van den Oever K, Mok KS, Paulusma CC, Linton KJ, Oude Elferink RPJ. Complementary functions of the flippase ATP8B1 and the floppase ABCB4 in maintaining canalicular membrane integrity. Gastroenterology 2011; 141:1927-37.e1-4. [PMID: 21820390 DOI: 10.1053/j.gastro.2011.07.042] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 07/12/2011] [Accepted: 07/27/2011] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Progressive familial intrahepatic cholestasis can be caused by mutations in ABCB4 or ATP8B1; each encodes a protein that translocates phospholipids, but in opposite directions. ABCB4 flops phosphatidylcholine from the inner to the outer leaflet, where it is extracted by bile salts. ATP8B1, in complex with the accessory protein CDC50A, flips phosphatidylserine in the reverse direction. Abcb4(-/-) mice lack biliary secretion of phosphatidylcholine, whereas Atp8b1-deficient mice have increased excretion of phosphatidylserine into bile. Each system is thought to have a role protecting the canalicular membrane from bile salts. METHODS To investigate the relationship between the mechanisms of ABCB4 and ATP8B1, we expressed the transporters separately and together in cultured cells and studied viability and phospholipid transport. We also created mice with disruptions in ABCB4 and ATP8B1 (double knockouts) and studied bile formation and hepatic damage in mice fed bile salts. RESULTS Overexpression of ABCB4 was toxic to HEK293T cells; the toxicity was counteracted by coexpression of the ATP8B1-CDC50A complex. In Atp8b1-deficient mice, bile salts induced extraction of phosphatidylserine and ectoenzymes from the canalicular membrane; this process was not observed in the double-knockout mice. CONCLUSIONS ATP8B1 is required for hepatocyte function, particularly in the presence of ABCB4. This is most likely because the phosphatidylserine flippase complex of ATP8B1-CDC50A counteracts the destabilization of the membrane that occurs when ABCB4 flops phosphatidylcholine. Lipid asymmetry is therefore important for the integrity of the canalicular membrane; ABCB4 and ATP8B1 cooperate to protect hepatocytes from bile salts.
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Affiliation(s)
- Annemiek Groen
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
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16
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Groen A, Kunne C, Paulusma CC, Kramer W, Agellon LB, Bull LN, Oude Elferink RPJ. Intestinal bile salt absorption in Atp8b1 deficient mice. J Hepatol 2007; 47:114-22. [PMID: 17448567 DOI: 10.1016/j.jhep.2007.02.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 02/04/2007] [Accepted: 02/12/2007] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS Mutations in the ATP8B1 gene can cause Progressive Familial Intrahepatic Cholestasis type 1. We have previously reported that Atp8b1(G308V/G308V) mice, a model for PFIC1, have slightly, but significantly, higher baseline serum bile salt (BS) concentrations compared to wt mice. Upon BS feeding, serum BS concentrations strongly increased in Atp8b1-deficient mice. Despite these findings, we observed only mildly impaired canalicular BS transport. In the present report we tested the hypothesis that Atp8b1(G308V/G308V) mice hyperabsorb BS in the intestine during BS feeding. METHODS Intestinal BS absorption was measured in intestinal perfusion and in intestinal explants. In addition, we measured BS concentrations in portal blood. Ileal expression of the Fxr-targets Asbt, Ilbp and Shp was assessed. RESULTS In wt and Atp8b1(G308V/G308V) mice, intestinal taurocholate absorption is primarily mediated by the ileal bile salt transporter Asbt. Neither of the experimental systems revealed enhanced absorption of BS in Atp8b1(G308V/G308V) mice compared to wt mice. In line with these observations, we found no difference in the ileal protein expression of Asbt. Induction of Shp expression during BS feeding also demonstrated that Fxr signalling is intact in Atp8b1(G308V/G308V) mice. CONCLUSIONS The accumulation of BS in plasma of Atp8b1(G308V/G308V) mice during BS feeding is not caused by increased intestinal BS absorption.
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Affiliation(s)
- Annemiek Groen
- AMC Liver Center, Academic Medical Center, Room S1-166, Meibergdreef 69-71, 1105 BK Amsterdam, The Netherlands
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17
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Groen A, Kunne C, Oude Elferink RPJ. Increased Serum Concentrations of Secondary Bile Salts during Cholate Feeding Are Due to Coprophagy. A Study with Wild-Type and Atp8b1-Deficient Mice. Mol Pharm 2006; 3:756-61. [PMID: 17140263 DOI: 10.1021/mp060009t] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Coprophagy (i.e., consumption of feces) is a behavior seen in rodents and other animal species. This behavior can substantially influence the enterohepatic cycling of compounds, including bile salts. Since many studies involve the feeding of rodents with bile salt supplemented diets, it is of importance to know the influence of coprophagy on bile salt composition in such studies. We compared the peripheral and portal bile salt composition of mice in conventional and metabolic cages when fed a control diet or a diet containing 0.5% cholate. We also performed these experiments with Atp8b1-deficient mice as it has been suggested that in the absence of this transporter bile salt absorption in the intestine would be increased. In mice on a control diet there is little difference in bile salt composition between conventional housing and metabolic housing. Metabolic housing led to a near complete disappearance of the low levels of dihydroxy bile salts (i.e., deoxycholate + chenodeoxycholate) in peripheral serum. In mice fed a control diet, the portal blood concentration of unconjugated dihydroxy bile salts was extremely low (<2%), but these rose to about 10% when mice were fed a cholate-supplemented diet. In metabolic cages the portal blood content of these unconjugated dihydroxy bile salts was reduced to undetectable levels. Whether housed in conventional cages or in metabolic cages, wild-type and Atp8b1-deficient mice had similar concentrations in portal blood, suggesting that intestinal bile salt absorption is not altered in Atp8b1-deficient mice.
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Affiliation(s)
- Annemiek Groen
- AMC Liver Center, Academic Medical Center, Amsterdam, The Netherlands.
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18
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Paulusma CC, Groen A, Kunne C, Ho-Mok KS, Spijkerboer AL, Rudi de Waart D, Hoek FJ, Vreeling H, Hoeben KA, van Marle J, Pawlikowska L, Bull LN, Hofmann AF, Knisely AS, Oude Elferink RPJ. Atp8b1 deficiency in mice reduces resistance of the canalicular membrane to hydrophobic bile salts and impairs bile salt transport. Hepatology 2006; 44:195-204. [PMID: 16799980 DOI: 10.1002/hep.21212] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Progressive familial intrahepatic cholestasis type 1 (PFIC1, Byler disease, OMIM 211600) is a severe inherited liver disease caused by mutations in ATP8B1. ATP8B1 is a member of the type 4 subfamily of P-type ATPases, which are phospholipid flippases. PFIC1 patients generally develop end-stage liver disease before the second decade of life. The disease is characterized by impaired biliary bile salt excretion, but the mechanism whereby impaired ATP8B1 function results in cholestasis is unclear. In a mouse model for PFIC1, we observed decreased resistance of the hepatocanalicular membrane to hydrophobic bile salts as evidenced by enhanced biliary recovery of phosphatidylserine, cholesterol, and ectoenzymes. In liver specimens from PFIC1 patients, but not in those from control subjects, ectoenzyme expression at the canalicular membrane was markedly deficient. In isolated mouse livers Atp8b1 deficiency impaired the transport of hydrophobic bile salts into bile. In conclusion, our study shows that Atp8b1 deficiency causes loss of canalicular phospholipid membrane asymmetry that in turn renders the canalicular membrane less resistant toward hydrophobic bile salts. The loss of phospholipid asymmetry may subsequently impair bile salt transport and cause cholestasis.
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Affiliation(s)
- Coen C Paulusma
- Amsterdam Liver Center, Department of Experimental Hepatology, Academic Medical Center, Amsterdam, the Netherlands.
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Oude Elferink RPJ, Paulusma CC, Groen AK. Hepatocanalicular transport defects: pathophysiologic mechanisms of rare diseases. Gastroenterology 2006; 130:908-25. [PMID: 16530529 DOI: 10.1053/j.gastro.2005.08.052] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Accepted: 09/20/2005] [Indexed: 12/31/2022]
Abstract
The apical membrane of the hepatocyte fulfils a unique function in the formation of primary bile. For all important biliary constituents a primary active transporter is present that extrudes or translocates its substrate toward the canalicular lumen. Most of these transporters are ATP-binding cassette (ABC) transporters. Two types of transporters can be recognized: those having endogenous metabolites as substrates (which could be referred to as "physiologic" transporters) and those involved in the elimination of drugs, toxins, and waste products. It should be emphasized that this distinction cannot be strictly made as some endogenous metabolites can be regarded as toxins as well. The importance of the canalicular transporters has been recognized by the pathologic consequence of their genetic defects. For each of the physiologic transporter genes an inherited disease has now been identified and most of these diseases have a quite serious clinical phenotype. Strikingly, complete defects in drug transporter function have not been recognized (yet) or only cause a mild phenotype. In this review we only briefly discuss the inherited defects in transporter function, and we focus on the pathophysiologic concepts that these diseases have generated.
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21
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Paulusma CC, Oude Elferink RPJ. The type 4 subfamily of P-type ATPases, putative aminophospholipid translocases with a role in human disease. Biochim Biophys Acta Mol Basis Dis 2005; 1741:11-24. [PMID: 15919184 DOI: 10.1016/j.bbadis.2005.04.006] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 04/21/2005] [Accepted: 04/25/2005] [Indexed: 11/22/2022]
Abstract
The maintenance of phospholipid asymmetry in membrane bilayers is a paradigm in cell biology. However, the mechanisms and proteins involved in phospholipid translocation are still poorly understood. Members of the type 4 subfamily of P-type ATPases have been implicated in the translocation of phospholipids from the outer to the inner leaflet of membrane bilayers. In humans, several inherited disorders have been identified which are associated with loci harboring type 4 P-type ATPase genes. Up to now, one inherited disorder, Byler disease or progressive familial intrahepatic cholestasis type 1 (PFIC1), has been directly linked to mutations in a type 4 P-type ATPase gene. How the absence of an aminophospholipid translocase activity relates to this severe disease is, however, still unclear. Studies in the yeast Saccharomyces cerevisiae have recently identified important roles for type 4 P-type ATPases in intracellular membrane- and protein-trafficking events. These processes require an (amino)phospholipid translocase activity to initiate budding or fusion of membrane vesicles from or with other membranes. The studies in yeast have greatly contributed to our cell biological insight in membrane dynamics and intracellular-trafficking events; if this knowledge can be translated to mammalian cells and organs, it will help to elucidate the molecular mechanisms which underlie severe inherited human diseases such as Byler disease.
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Affiliation(s)
- C C Paulusma
- Department of Experimental Hepatology, Academic Medical Center/AMC Liver Center, Meibergdreef 69-71, 1105 BK Amsterdam, The Netherlands.
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Affiliation(s)
- Guillaume Lenoir
- Department of Membrane Enzymology, Institute of Biomembranes, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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23
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van Mil SWC, van Oort MM, van den Berg IET, Berger R, Houwen RHJ, Klomp LWJ. Fic1 is expressed at apical membranes of different epithelial cells in the digestive tract and is induced in the small intestine during postnatal development of mice. Pediatr Res 2004; 56:981-7. [PMID: 15496606 DOI: 10.1203/01.pdr.0000145564.06791.d1] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Mutations in ATP8B1 are associated with FIC1 disease, an autosomal recessive disorder in which intrahepatic cholestasis is the predominant manifestation. ATP8B1 encodes FIC1, which is expressed in several tissues, most prominently in the intestine, pancreas, and stomach and, to a much lesser extent, in the liver. In this study, Fic1 localization and expression during postnatal development was examined in healthy mice. Immunoblot and RT-PCR analysis indicated Fic1 is expressed abundantly in regions of the adult gastrointestinal tract of humans and mice. Immunohistochemistry revealed that Fic1 was localized to the apical membranes of enterocytes, pancreatic acinar cells, gastric pit epithelial cells, and hepatocytes and cholangiocytes. Subsequent analysis of early postnatal expression revealed that Fic1 expression in the small intestine was limited or absent at the age of 7 and 14 d and increased significantly with maturation. In contrast, pancreatic, hepatic, and gastric Fic1 expression was not diminished during the first 3 wk of postnatal development. In conclusion, these data show that Fic1 is expressed in a tissue-specific and developmentally regulated fashion at the apical membranes of epithelial cells. We speculate that the developing bile salt pool in the maturing intestine accounts for the increase in Fic1 protein expression in this tissue.
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Affiliation(s)
- Saskia W C van Mil
- Department of Pediatric Gastroenterology, University Medical Center Utrecht, 3584 EA Utrecht, The Netherlands
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Abstract
Phosphatidylinositol/phosphatidylcholine transfer proteins (PITPs) are ubiquitous and highly conserved proteins that are believed to regulate lipid-mediated signaling events. Their ubiquity and conservation notwithstanding, PITPs remain remarkably uninvestigated. Little is known about the coupling of specific PITPs to explicit cellular functions or the mechanisms by which PITPs interface with appropriate cellular functions. The available information indicates a role for these proteins in regulating the interface between lipid metabolism and membrane trafficking in yeast, signaling in plant development, the trafficking of specialized luminal cargo in mammalian enterocytes, and neurological function in mammals. Herein, we review recent advances in PITP biology and discuss as yet unresolved issues in this field.
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Affiliation(s)
- Sheri M Routt
- Department of Cell and Developmental Biology, School of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 27599-7090, USA
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25
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Schneider M, Vergès B, Klein A, Miller ER, Deckert V, Desrumaux C, Masson D, Gambert P, Brun JM, Fruchart-Najib J, Blache D, Witztum JL, Lagrost L. Alterations in plasma vitamin E distribution in type 2 diabetic patients with elevated plasma phospholipid transfer protein activity. Diabetes 2004; 53:2633-9. [PMID: 15448094 DOI: 10.2337/diabetes.53.10.2633] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mouse studies indicated that plasma phospholipid transfer protein (PLTP) determines the plasma distribution of vitamin E, a potent lipophilic antioxidant. Vitamin E distribution, antioxidant status, and titer of anti-oxidized LDLs (oxLDL) autoantibodies were evaluated in plasma from control subjects (n = 31) and type 2 diabetic patients (n = 31) with elevated plasma PLTP concentration. Unlike diabetic and control HDLs, which displayed similar vitamin E contents, diabetic VLDLs and diabetic LDLs contained fewer vitamin E molecules than normal counterparts. Plasma PLTP concentration in diabetic plasmas correlated negatively with vitamin E in VLDL+LDL, but positively with vitamin E in HDL, with an even stronger correlation with the VLDL+LDL-to-HDL vitamin E ratio. Circulating levels of oxLDL were significantly higher in diabetic plasmas than in control plasmas. Whereas the titer of IgG autoantibodies to modified LDL did not differ significantly between diabetic patients and control subjects, diabetic plasmas showed significantly lower levels of potentially protective IgM autoantibodies. The present observations support a pathophysiological role of PLTP in decreasing the vitamin E content of apolipoprotein B-containing lipoproteins, but not of HDL in plasma of type 2 diabetic patients, contributing to a greater potential for LDL oxidation.
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Affiliation(s)
- Martina Schneider
- Institut National de la Santé et de la Recherche Médicale, U498, Dijon Cedex, France
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Wicky S, Schwarz H, Singer-Krüger B. Molecular interactions of yeast Neo1p, an essential member of the Drs2 family of aminophospholipid translocases, and its role in membrane trafficking within the endomembrane system. Mol Cell Biol 2004; 24:7402-18. [PMID: 15314152 PMCID: PMC507011 DOI: 10.1128/mcb.24.17.7402-7418.2004] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neo1p is an essential yeast member of the highly conserved Drs2 family of P-type ATPases with proposed aminophospholipid translocase activity. Here we present evidence that Neo1p localizes to endosomes and Golgi elements. In agreement with that finding, the temperature-sensitive neo1-37 and neo1-69 mutants exhibit defects in receptor-mediated endocytosis, vacuole biogenesis, and vacuolar protein sorting. Furthermore, neo1 mutants accumulate aberrantly shaped membranous structures most likely derived from vacuoles and the endosomal/Golgi system. At permissive temperatures, HA-Neo1-69p, like wild-type Neo1p, is stable and associates with endosomes. In contrast, HA-Neo1-37p is rapidly degraded and is predominantly retained within the endoplasmic reticulum (ER). Thus, the two neo1 alleles affect the stability and localization of the mutant polypeptides in different ways. A C-terminally truncated and a C-terminally epitope-tagged version of Neo1p are nonfunctional and also mislocalize to the ER. In agreement with a role within the endomembrane system, Neo1p exhibits genetic and physical interactions with Ysl2p, a potential guanine nucleotide exchange factor for Arl1p. Interestingly, deletion of ARL1 rescues the temperature sensitivity of neo1-37 and neo1-69. We demonstrate that Arl1p in its myristoylated and GTP-bound form is responsible for the inhibitory effect. Thus, Neo1p, Ysl2p, and Arl1p represent three proteins that collaborate in membrane trafficking within the endosomal/Golgi system.
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Affiliation(s)
- Sidonie Wicky
- Institute for Biochemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
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Abstract
Transbilayer flipping of glycerophospholipids in the endoplasmic reticulum (ER) is a key feature of membrane biogenesis. Flipping appears to be an ATP-independent, bidirectional process facilitated by specific proteins or flippases. Although a phospholipid flippase has yet to be identified, evidence supporting the existence of dedicated flippases was recently obtained through biochemical reconstitution studies showing that certain chromatographically resolved fractions of detergent-solubilized ER proteins were enriched in flippase activity, whereas others were inactive. We now extend these studies by describing two convenient assays of flippase activity utilizing fluorescent phospholipid analogues as transport reporters. We use these assays to show that (i) proteoliposomes generated from a flippase-enriched Triton X-100 extract of ER can flip analogues of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine; (ii) flipping of all three phospholipids is likely due to the same flippase(s) rather than distinct, phospholipid-specific transport proteins; (iii) functional flippases represent approximately 1% (w/w) of ER membrane proteins in the Triton extract; and (iv) glycerophospholipid flippase activity in the ER can be attributed to two functionally distinct proteins (or classes of proteins) defined by their sensitivity to the cysteine and histidine modification reagents N-ethylmaleimide and diethylpyrocarbonate, respectively. Analyses of the N-ethylmaleimide-sensitive class of flippase activity revealed that the functionally critical sulfhydryl group in the flippase protein is buried in a hydrophobic environment in the membrane but becomes reactive on extraction of the protein into Triton X-100. This observation holds considerable promise for future attempts to isolate the flippase via an affinity approach.
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Affiliation(s)
- Qing-long Chang
- Department of Biochemistry, University of Wisconsin, 433 Babcock Drive, Madison, Wisconsin 53706-1569, USA
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Wiedmer T, Zhao J, Li L, Zhou Q, Hevener A, Olefsky JM, Curtiss LK, Sims PJ. Adiposity, dyslipidemia, and insulin resistance in mice with targeted deletion of phospholipid scramblase 3 (PLSCR3). Proc Natl Acad Sci U S A 2004; 101:13296-301. [PMID: 15328404 PMCID: PMC516563 DOI: 10.1073/pnas.0405354101] [Citation(s) in RCA: 36] [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: 05/03/2004] [Indexed: 12/22/2022] Open
Abstract
The phospholipid scramblases (PLSCR1 to PLSCR4) are a structurally and functionally unique class of proteins, which are products of a tetrad of genes conserved from Caenorhabditis elegans to humans. The best characterized member of this family, PLSCR1, is implicated in the remodeling of the transbilayer distribution of plasma membrane phospholipids but is also required for normal signaling through select growth factor receptors. Mice with targeted deletion of PLSCR1 display perinatal granulocytopenia due to defective response of hematopoietic precursors to granulocyte colony-stimulating factor and stem cell factor. To gain insight into the biologic function of another member of the PLSCR family, we investigated mice with targeted deletion of PLSCR3, a protein that like PLSCR1 is expressed in many blood cells but which, by contrast to PLSCR1, is also highly expressed in fat and muscle. PLSCR3(-/-) mice at 2 months of age displayed aberrant accumulation of abdominal fat when maintained on standard rodent chow, which was accompanied by insulin resistance, glucose intolerance, and dyslipidemia. Primary adipocytes and cultured bone-marrow-derived macrophages from PLSCR3(-/-) mice were engorged with neutral lipid, and adipocytes displayed defective responses to exogenous insulin. Plasma of PLSCR3(-/-) mice was elevated in non-high-density lipoproteins, cholesterol, triglycerides, nonesterified fatty acids, and leptin, whereas adiponectin was low. These data suggest that the expression of PLSCR3 may be required for normal adipocyte and/or macrophage maturation or function and raise the possibility that deletions or mutations affecting the PLSCR3(-/-) gene locus may contribute to the risk for lipid-related disorders in humans.
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Affiliation(s)
- Therese Wiedmer
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
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29
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De Deken X, Raymond M. Constitutive activation of the PDR16 promoter in a Candida albicans azole-resistant clinical isolate overexpressing CDR1 and CDR2. Antimicrob Agents Chemother 2004; 48:2700-3. [PMID: 15215129 PMCID: PMC434214 DOI: 10.1128/aac.48.7.2700-2703.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Candida albicans azole-resistant clinical isolates overexpressing the CDR1 and CDR2 genes (multidrug transporters) also overexpress the PDR16 gene (phosphatidylinositol transfer protein). We show here that the PDR16 promoter displays higher transcriptional activity following integration in an azole-resistant isolate than in the matched azole-susceptible one. Thus, the upregulation of PDR16 in the resistant strain results from a mutation acting in trans.
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Affiliation(s)
- Xavier De Deken
- Institut de Recherches Cliniques de Montréal, 110 Pine Avenue West, Montréal, Québec, Canada H2W 1R7
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30
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Dong B, Zhou Q, Zhao J, Zhou A, Harty RN, Bose S, Banerjee A, Slee R, Guenther J, Williams BRG, Wiedmer T, Sims PJ, Silverman RH. Phospholipid scramblase 1 potentiates the antiviral activity of interferon. J Virol 2004; 78:8983-93. [PMID: 15308695 PMCID: PMC506946 DOI: 10.1128/jvi.78.17.8983-8993.2004] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [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: 03/14/2004] [Accepted: 04/14/2004] [Indexed: 11/20/2022] Open
Abstract
Phospholipid scramblase 1 (PLSCR1) is an interferon (IFN)- and growth factor-inducible, calcium-binding protein that either inserts into the plasma membrane or binds DNA in the nucleus depending on its state of palmyitoylation. In certain hematopoietic cells, PLSCR1 is required for normal maturation and terminal differentiation from progenitor cells as regulated by select growth factors, where it promotes recruitment and activation of Src kinases. PLSCR1 is a substrate of Src (and Abl) kinases, and transcription of the PLSCR1 gene is regulated by the same growth factor receptor pathways in which PLSCR1 potentiates afferent signaling. The marked transcriptional upregulation of PLSCR1 by IFNs led us to explore whether PLSCR1 plays an analogous role in cellular responses to IFN, with specific focus on antiviral activities. Accordingly, human cells in which PLSCR1 expression was decreased with short interfering RNA were rendered relatively insensitive to the antiviral activity of IFNs, resulting in higher titers of vesicular stomatitis virus (VSV) and encephalomyocarditis virus. Similarly, VSV replicated to higher titers in mouse PLSCR1(-/-) embryonic fibroblasts than in identical cells transduced to express PLSCR1. PLSCR1 inhibited accumulation of primary VSV transcripts, similar to the effects of IFN against VSV. The antiviral effect of PLSCR1 correlated with increased expression of a subset of IFN-stimulated genes (ISGs), including ISG15, ISG54, p56, and guanylate binding proteins. Our results suggest that PLSCR1, which is itself an ISG-encoded protein, provides a mechanism for amplifying and enhancing the IFN response through increased expression of a select subset of potent antiviral genes.
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Affiliation(s)
- Beihua Dong
- Department of Cancer Biology, The Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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Zhou M, Parr RD, Petrescu AD, Payne HR, Atshaves BP, Kier AB, Ball JM, Schroeder F. Sterol carrier protein-2 directly interacts with caveolin-1 in vitro and in vivo. Biochemistry 2004; 43:7288-306. [PMID: 15182174 DOI: 10.1021/bi035914n] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [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: 11/29/2022]
Abstract
HDL-mediated reverse-cholesterol transport as well as phosphoinositide signaling are mediated through plasma membrane microdomains termed caveolae/lipid rafts. However, relatively little is known regarding mechanism(s) whereby these lipids traffic to or are targeted to caveolae/lipid rafts. Since sterol carrier protein-2 (SCP-2) binds both cholesterol and phosphatidylinositol, the possibility that SCP-2 might interact with caveolin-1 and caveolae was examined. Double immunolabeling and laser scanning fluorescence microscopy showed that a small but significant portion of SCP-2 colocalized with caveolin-1 primarily at the plasma membrane of L-cells and more so within intracellular punctuate structures in hepatoma cells. In SCP-2 overexpressing L-cells, SCP-2 was detected in close proximity to caveolin, 48 +/- 4 A, as determined by fluorescence resonance energy transfer (FRET) and immunogold electron microscopy. Cell fractionation of SCP-2 overexpressing L-cells and Western blotting detected SCP-2 in purified plasma membranes, especially in caveolae/ lipid rafts as compared to the nonraft fraction. SCP-2 and caveolin-1 were coimmunoprecipitated from cell lysates by anti-caveolin-1 and anti-SCP-2. Finally, a yeast two-hybrid assay demonstrated that SCP-2 directly interacts with caveolin-1 in vivo. These interactions of SCP-2 with caveolin-1 were specific since a functionally related protein, phosphatidyinositol transfer protein (PITP), colocalized much less well with caveolin-1, was not in close proximity to caveolin-1 (i.e., >120 A), and was not coimmunoprecipitated by anti-caveolin-1 from cell lysates. In summary, it was shown for the first time that SCP-2 (but not PITP) selectively interacted with caveolin-1, both within the cytoplasm and at the plasma membrane. These data contribute significantly to our understanding of the role of SCP-2 in cholesterol and phosphatidylinositol targeted from intracellular sites of synthesis in the endoplasmic reticulum to caveolae/lipid rafts at the cell surface plasma membrane.
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Affiliation(s)
- Minglong Zhou
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, Texas 77843-4466, USA
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Tao J, Feng L, Guo H, Li Y, Wang L. The O-antigen gene cluster of Shigella boydii O11 and functional identification of its wzy gene. FEMS Microbiol Lett 2004; 234:125-32. [PMID: 15109730 DOI: 10.1016/j.femsle.2004.03.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2004] [Revised: 02/26/2004] [Accepted: 03/08/2004] [Indexed: 09/30/2022] Open
Abstract
Shigella strains are human pathogens and their identification is usually based on their O-antigens. The O-antigen gene cluster of Shigella boydii O11 was sequenced. All the expected genes for the synthesis of the O-antigen were identified on the basis of homology and genes for the biosynthesis of dTDP-l-Rhamnose, genes encoding sugar transferases, as well as genes encoding O unit flippase (wzx) and O-antigen polymerase (wzy). The identity of the putative wzy gene was confirmed by showing that a wzy deficient mutant strain of S. boydii O11 produced a semi-rough LPS phenotype. The predicted wzx gene has an opposite transcription direction to that of all of the other genes in the S. boydii O11 O-antigen gene cluster. This unusual feature for the wzx gene has only previously been reported in S. boydii O6. Further comparison revealed an evolutionary relationship between O6 and O11 O-antigen gene clusters. Adjacent-gene PCR showed that Escherichia coli O105 and S. boydii O11, which share the identical O-antigen, also have the same genes and organization for their respective O-antigen gene clusters. Three genes specific for the S. boydii O11 and E. coli O105 gene clusters were identified.
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Affiliation(s)
- Jiang Tao
- TEDA School of Biological Sciences and Biotechnology, Nankai University, 23Hong Da Street, TEDA, Tianjin 300457, PR China
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33
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Abstract
OBJECTIVE Dyslipidaemia in obesity is characterized by hypertriglyceridaemia, low HDL-C levels, small, dense HDL particles and increased phospholipid transfer protein (PLTP) activity. METHODS In the present study, we investigated PLTP activity and HDL particle size in 16 morbidly obese, middle-aged women, who underwent Swedish Adjustable Gastric Banding surgery. Study subjects were tested within 2 months before and 1 y after surgery. PLTP activity was determined by exogenous substrate assay and HDL particle size by gradient gel electrophoresis, respectively. RESULTS Pronounced weight loss after gastric banding surgery resulted in a significant decrease of PLTP activity from 8.42+/-2.04 to 7.43+/-2.21 micromol/ml/h (P=0.02). The size of HDL(2) particles increased signficantly from 14.04+/-0.86 to 14.28+/-0.64 nm (P=0.02) after body weight reduction, while no change in HDL(3) particle size was apparent. DISCUSSION Our results suggest that dyslipidaemia in obesity is--at least partially--reversible by weight loss. We hypothesize that reduction of PLTP activity and increase of HDL particle size are important component factors in converting the atherogenic lipoprotein profile of obese subjects into a less atherogenic profile with weight loss.
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Affiliation(s)
- S Kaser
- Clinical Department of General Internal Medicine, Medical University of Innsbruck, A-6020 Innsbruck, Austria
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Yatsuya H, Tamakoshi K, Hattori H, Otsuka R, Wada K, Zhang H, Mabuchi T, Ishikawa M, Murata C, Yoshida T, Kondo T, Toyoshima H. Serum phospholipid transfer protein mass as a possible protective factor for coronary heart diseases. Circ J 2004; 68:11-6. [PMID: 14695459 DOI: 10.1253/circj.68.11] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Phospholipid transfer protein (PLTP) can generate pre-beta high-density lipoprotein (HDL), an efficient acceptor of peripheral cholesterol, by mediating a process called HDL conversion. The transfer of phospholipids to immature HDL is also essential in maintaining reverse cholesterol transport. The phospholipid transfer activity of PLTP has been associated with various patho-physiological conditions; however, little information is available concerning the relationship between PLTP mass and disease. METHODS AND RESULTS Using a sandwich enzyme-linked immunosorbent assay, PLTP concentration was measured and related to the risk of developing cardiovascular disease in a worksite-based cohort of Japanese men (n=2,567). Multiple linear regression analysis showed significant associations between PLTP and HDL cholesterol, triglycerides, low-density lipoprotein cholesterol, and body mass index (standardized beta=0.395, -0.191, -0.064, and -0.064, respectively; R(2)=0.31). During the follow-up period, there were 10 cases of coronary heart disease (CHD) and 7 of stroke. The multivariate adjusted relative risk of CHD was 0.46 (95% confidence interval, 0.20-1.07) for an increase of 1 standard deviation in the PLTP value (p=0.071). PLTP concentration was not related to the risk of stroke. CONCLUSIONS The results of this prospective study indicate that the serum PLTP concentration would serve as a predictor of CHD, independent of HDL cholesterol, triglycerides and other established risk factors.
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Affiliation(s)
- Hiroshi Yatsuya
- Department of Public Health/Health Information Dynamics, Nagoya University Graduate School of Medicine, Japan
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35
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Ben-Efraim I, Zhou Q, Wiedmer T, Gerace L, Sims PJ. Phospholipid scramblase 1 is imported into the nucleus by a receptor-mediated pathway and interacts with DNA. Biochemistry 2004; 43:3518-26. [PMID: 15035622 DOI: 10.1021/bi0356911] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [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: 11/30/2022]
Abstract
Phospholipid scramblase 1 (PLSCR1) is a multiply palmitoylated, Ca(2+)-binding, endofacial plasma membrane protein originally identified by its capacity to accelerate transbilayer movement of membrane phospholipids. We recently reported that when palmitoylation of PLSCR1 does not occur, it is localized to the nucleus rather than the plasma membrane. Nuclear localization of PLSCR1 was also observed upon induction of its de novo synthesis by cytokines such as interferon alpha that activate the PLSCR1 gene. Despite its capacity to enter the nucleus, its sequence does not predict a nuclear localization signal. To gain insight into the mechanism and potential significance of nuclear PLSCR1, we investigated the conditions required for its import and retention in the nucleus. We show that nuclear localization of PLSCR1 is dependent on cytosolic factors and energy. Furthermore, we show that PLSCR1 is specifically transported into the nucleus by the importin alpha/beta import pathway, and binds directly and with high affinity to importin alpha. Analysis of deletion mutants suggested that the NLS of PLSCR1 is between residues 242 and 290 and, furthermore, that a peptide within this region encompassing residues (257)GKISKHWTGI(266) is sufficient for nuclear import when conjugated to BSA. In addition, in intact cells, mutation of positively charged amino acids within this putative NLS in the full-length protein completely blocked its entry into the nucleus, consistent with its role in targeting PLSCR1 to the nucleus. Release of PLSCR1 from the nucleus was only observed after treatment of cells with both detergent and an elevated NaCl concentration, or following DNase treatment of the nucleus, suggesting ionic interactions of PLSCR1 with a nuclear component bound to genomic DNA or directly with genomic DNA. Purified PLSCR1 was also found to bind directly to a genomic DNA-cellulose conjugate, and its elution from DNA also required an elevated NaCl concentration. These data support a mechanism of receptor-mediated nuclear import of PLSCR1 and suggest a potential nuclear function for this plasma membrane protein.
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Affiliation(s)
- Iris Ben-Efraim
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
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36
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Natarajan P, Wang J, Hua Z, Graham TR. Drs2p-coupled aminophospholipid translocase activity in yeast Golgi membranes and relationship to in vivo function. Proc Natl Acad Sci U S A 2004; 101:10614-9. [PMID: 15249668 PMCID: PMC489982 DOI: 10.1073/pnas.0404146101] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.6] [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: 11/18/2022] Open
Abstract
Aminophospholipid translocases (APLTs) are defined primarily by their ability to flip fluorescent or spin-labeled derivatives of phosphatidylserine (PS) and phosphatidylethanolamine (PE) from the external leaflet of a membrane bilayer to the cytosolic leaflet and are thought to establish phospholipid asymmetry in biological membranes. The identities of APLTs remain unknown, although candidate proteins include the Drs2p/ATPase II subfamily of P-type ATPases. Drs2p from budding yeast localizes to the trans-Golgi network (TGN), and here we show that this membrane contains an ATP-dependent APLT that flips 7-nitro-2-1,3-benzoxadiazol-4-yl (NBD) PS and PE derivatives from the luminal to the cytosolic leaflet. To assess the contribution of Drs2p to this activity, TGN membranes were prepared from strains harboring WT or temperature-sensitive alleles of DRS2 and null alleles of three other potential APLT genes (DNF1, DNF2, and DNF3). Assay of these membranes indicated that Drs2p was required for the ATP-dependent translocation of NBD-PS, whereas no active translocation of NBD-PE or NBD-phosphatidylcholine was detected. The specificity of Drs2p for NBD-PS suggested that translocation of PS would be required for the function of Drs2p in protein transport from the TGN. However, cho1 yeast strains that are unable to synthesize PS do not phenocopy drs2 but instead transport proteins normally via the secretory pathway. In addition, a drs2 cho1 double mutant retains drs2 transport defects. Therefore, whereas NBD-PS is a preferred substrate for Drs2p in vitro, endogenous PS is not an obligatory substrate in vivo for the role Drs2p plays in protein transport.
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Affiliation(s)
- Paramasivam Natarajan
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634, USA
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Abstract
Evidence based prevention of cholecystolithiasis. Cholesterol cholelithiasis is one of the most common and expensive gastroenterological diseases. Beside common exogenous risk factors, recent molecular genetic studies have identified genetic risk factors for both cholesterol and pigment stone formation. Examples are low phospholipid-associated cholelithiasis due to mutations of the gene encoding the hepatocanalicular phosphatidylcholine transporter, and pigment stones in association with mutations of the ileal bile salt transporter gene. Evidence-based options for primary prevention of cholecystolithiasis include physical activity, slow weight reduction, regular vitamin C supplementation, and moderate coffee consumption. The ongoing genome projects provide the basis for future epidemiological studies of human gallstone (LITH) genes, which might offer new prospects for individual risk assessment and prevention of gallstones.
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Affiliation(s)
- Frank Lammert
- Medizinische Klinik III, Universitätsklinikum Aachen, RWTH Aachen, Aachen
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Castegna A, Lauderback CM, Mohmmad-Abdul H, Butterfield DA. Modulation of phospholipid asymmetry in synaptosomal membranes by the lipid peroxidation products, 4-hydroxynonenal and acrolein: implications for Alzheimer's disease. Brain Res 2004; 1004:193-7. [PMID: 15033435 DOI: 10.1016/j.brainres.2004.01.036] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [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] [Accepted: 01/25/2004] [Indexed: 11/28/2022]
Abstract
Membrane lipid bilayer asymmetry is maintained by the ATP-dependent enzyme flippase. An early signal of synaptosomal apoptosis is the loss of phospholipid asymmetry and the appearance of phosphatidylserine (PS) in the outer leaflet of the membrane. Two highly reactive products of lipid peroxidation, 4-hydroxynonenal (HNE) and acrolein, both elevated in Alzheimer's disease (AD) brain, have been shown to induce apoptosis and disrupt cellular ion homeostasis. These reactive aldehydes can structurally modify proteins by covalent interaction and inhibit enzyme function. Phospholipid asymmetry of PS is maintained by the ATP-requiring enzyme flippase. We have investigated the inactivation of the transmembrane enzyme aminophospholipid-translocase (or flippase) by HNE and acrolein. Flippase activity depends on a critical cysteine residue, a possible site of covalent modification by HNE or acrolein. The present study demonstrates that these alkenals induce the appearance of PS on the outer bilayer lamellae and suggests that increases in intracellular Ca(2+) might not be the sole cause for loss of flippase activity. Rather, other mechanisms that could modulate the function of flippase might be important in phospholipid asymmetry disruption. These results are discussed with potential relevance to neuronal loss in Alzheimer's disease brain.
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Affiliation(s)
- Alessandra Castegna
- Department of Chemistry, Center of Membrane Sciences, and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40506-0055, USA
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Wang L, Beserra C, Garbers DL. A novel aminophospholipid transporter exclusively expressed in spermatozoa is required for membrane lipid asymmetry and normal fertilization. Dev Biol 2004; 267:203-15. [PMID: 14975727 DOI: 10.1016/j.ydbio.2003.11.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [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: 08/14/2003] [Revised: 11/06/2003] [Accepted: 11/07/2003] [Indexed: 10/26/2022]
Abstract
Through the use of a functionally unbiased signal peptide trap screen, we have discovered an ATP-dependent aminophospholipid transporter that is exclusively expressed in the acrosomal region of spermatozoa; it is about 62% similar to the flippase, FIC1. We disrupted the transporter gene and found that the size of litters from male null mice was slightly smaller than found with wild-type males. Sperm morphology and motility were the same between null and wild-type littermates, but agents (merocyanine and annexin) that measure phospholipid packing or phosphatidylserine (PS) in the outer membrane leaflet showed that PS already existed in the outer leaflet of null spermatozoa before sperm capacitation. Fertilization rates were normal when null spermatozoa were added to zona pellucida-free eggs, but in the presence of the extracellular matrix, fewer transporter(-/-) spermatozoa bound tightly or penetrated the zona pellucida (ZP), and fewer underwent acrosome reactions. In vitro fertilization was compromised, especially at early time points or at low sperm concentrations after mixing null spermatozoa and eggs. Thus, a new aminophospholipid transporter expressed exclusively in spermatozoa is critical for normal phospholipid distribution in the bilayer, and for normal binding, penetration, and signaling by the zona pellucida.
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Affiliation(s)
- Lei Wang
- Cecil H. and Ida Green Center for Reproductive Biology Sciences, Howard Hughes Medical Institute and Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9051, USA
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Abstract
Defining the mechanisms that confer metastatic ability on cancer cells is an important goal towards prevention of metastasis. A gene array screen between a non-metastatic prostate cancer cell and its metastatic derivative line revealed decreased expression of Raf kinase inhibitor protein (RKIP) in the metastatic cell line. This finding is consistent with the possibility that loss of RKIP is associated with metastasis. RKIP is expressed in many tissues including brain, lung, and liver. RKIP blocks Raf-induced phosphorylation of MEK. In addition to its modulation of Raf signaling, RKIP modulates both G-protein signaling and NF-kappaB activity. The impact that RKIP has on multiple signaling pathways grants it the ability to play a role in several cellular functions including membrane biosynthesis, spermatogenesis, and neural signaling. Novel cellular functions for RKIP continue to be identified, several of which contribute to cancer biology. For example, RKIP promotes apoptosis of cancer cells, which suggests that loss of RKIP in cancer will protect cancer cells against cell death. Additionally, restoration of RKIP expression ina metastatic prostate cancer cell line does not effect primary tumor growth, but it does inhibit prostate cancer metastasis. These parameters identify RKIP as a metastasis suppressor gene, which suggest that it or proteins it interacts with are putative molecular targets to control metastasis. These findings are supported by the observation that RKIP expression is decreased in metastases of prostate cancer patients, compared to normal prostate or the primary prostate tumor. In this review, RKIP biology and its role in cancer will be described.
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Affiliation(s)
- Evan T Keller
- Department of Urology, University of Michigan, Ann Arbor, MI 48109, USA.
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Kazuki Y, Kimura M, Nishigaki R, Kai Y, Abe S, Okita C, Shirayoshi Y, Schulz TC, Tomizuka K, Hanaoka K, Inoue T, Oshimura M. Human chromosome 21q22.2-qter carries a gene(s) responsible for downregulation of mlc2a and PEBP in Down syndrome model mice. Biochem Biophys Res Commun 2004; 317:491-9. [PMID: 15063784 DOI: 10.1016/j.bbrc.2004.03.069] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Indexed: 11/23/2022]
Abstract
Congenital heart disease (CHD) is a major clinical manifestation of Down syndrome (DS). We recently showed that chimeric mice containing a human chromosome 21 (Chr 21) exhibited phenotypic traits of DS, including CHD. Our previous study showed that myosin light chain-2a (mlc2a) expression was reduced in the hearts of chimeric mice and DS patients. We found that phosphatidylethanolamine binding protein (PEBP) was also downregulated in Chr 21 chimeras in this study. As mlc2a is involved in heart morphogenesis, and PEBP controls the proliferation and differentiation of different cell types, these genes are candidates for involvement in DS-CHD. The DS-CHD candidate region has been suggested to span between PFKL and D21S3, which is the STS marker near the ETS2 loci. To identify gene(s) or a gene cluster on Chr 21 responsible for the downregulation of mlc2a and PEBP, we fragmented Chr 21 at the EST2 loci, by telomere-directed chromosome truncation in homologous recombination-proficient chicken DT40 cells. The modified Chr 21 was transferred to mouse ES cells by microcell-mediated chromosome transfer (MMCT), via CHO cells. We used ES cell lines retaining the Chr 21 truncated at the ETS2 locus (Chr 21E) to produce chimeric mice and compared overall protein expression patterns in hearts of the chimeras containing the intact and the fragmented Chr 21 by two-dimensional electrophoresis. While mouse mlc2a and PEBP expression was downregulated in the chimeras containing the intact Chr 21, the expression was not affected in the Chr 21E chimeras. Therefore, we suggest that Chr 21 gene(s) distal from the ETS2 locus reduce mouse mlc2a and PEBP expression in DS model mice and DS. Thus, this chromosome engineering technology is a useful tool for identification or mapping of genes that contribute to the DS phenotypes.
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Affiliation(s)
- Yasuhiro Kazuki
- Department of Molecular and Cell Genetics, Graduate School of Medical Science, Tottori University, 86 Nishimachi, Yonago, Tottori 683-8503, Japan
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42
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Abstract
Due to their role in oxygen transport and the presence of redox active haemoglobin molecules, red blood cells (RBC) generate relatively high levels of reactive oxygen species (ROS). To counteract the potential deleterious effects of ROS, RBCs have a well-integrated network of anti-oxidant mechanisms to combat this oxidative stress. ROS formation is increased in sickle-cell disease (SCD) and our studies in a murine SCD model showed a significant increase in the generation of ROS when compared with normal mice. Our data also indicated that murine sickle RBCs exhibit a significantly increased ATP catabolism, partly due to the increased activity of glucose-6-phosphate dehydrogenase and glutathione reductase to regenerate intracellular glutathione (GSH) levels to neutralize the adverse milieu of oxidative stress. Higher ATP consumption by the murine sickle RBCs, together with the increased ROS formation and impairment of the aminophospholipid translocase or flipase may underlie the exposure of phosphatidylserine on the surface of these cells.
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Affiliation(s)
- Tinku Banerjee
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA 94609, USA
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Saito K, Fujimura-Kamada K, Furuta N, Kato U, Umeda M, Tanaka K. Cdc50p, a protein required for polarized growth, associates with the Drs2p P-type ATPase implicated in phospholipid translocation in Saccharomyces cerevisiae. Mol Biol Cell 2004; 15:3418-32. [PMID: 15090616 PMCID: PMC452594 DOI: 10.1091/mbc.e03-11-0829] [Citation(s) in RCA: 200] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cdc50p, a transmembrane protein localized to the late endosome, is required for polarized cell growth in yeast. Genetic studies suggest that CDC50 performs a function similar to DRS2, which encodes a P-type ATPase of the aminophospholipid translocase (APT) subfamily. At low temperatures, drs2Delta mutant cells exhibited depolarization of cortical actin patches and mislocalization of polarity regulators, such as Bni1p and Gic1p, in a manner similar to the cdc50Delta mutant. Both Cdc50p and Drs2p were localized to the trans-Golgi network and late endosome. Cdc50p was coimmunoprecipitated with Drs2p from membrane protein extracts. In cdc50Delta mutant cells, Drs2p resided on the endoplasmic reticulum (ER), whereas Cdc50p was found on the ER membrane in drs2Delta cells, suggesting that the association on the ER membrane is required for transport of the Cdc50p-Drs2p complex to the trans-Golgi network. Lem3/Ros3p, a homolog of Cdc50p, was coimmunoprecipitated with another APT, Dnf1p; Lem3p was required for exit of Dnf1p out of the ER. Both Cdc50p-Drs2p and Lem3p-Dnf1p were confined to the plasma membrane upon blockade of endocytosis, suggesting that these proteins cycle between the exocytic and endocytic pathways, likely performing redundant functions. Thus, phospholipid asymmetry plays an important role in the establishment of cell polarity; the Cdc50p/Lem3p family likely constitute potential subunits specific to unique P-type ATPases of the APT subfamily.
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Affiliation(s)
- Koji Saito
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Medicine, Sapporo 060-0815, Japan
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Feng L, Tao J, Guo H, Xu J, Li Y, Rezwan F, Reeves P, Wang L. Structure of the Shigella dysenteriae 7 O antigen gene cluster and identification of its antigen specific genes. Microb Pathog 2004; 36:109-15. [PMID: 14687563 DOI: 10.1016/j.micpath.2003.10.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Shigella strains are human pathogens. The O antigen gene cluster of Shigella dysenteriae O7 was sequenced and analyzed. It contains genes for synthesis of nucleotide sugars including UDP-2-acetamido-2-deoxy-D-galacturonamide, UDP-2-acetamido-2-deoxy-D-galacturonic acid and dTDP-4-amino-4,6-dideoxy-D-glucose. Also found in the gene cluster are genes encoding O unit flippase, O antigen polymerase and sugar transferases. The Escherichia coli O121 O antigen, which is present in an important Shiga toxin-producing strain, has the same structure as that of S. dysenteriae O7, and we found that the gene clusters also had the same genes and organization. Four genes specific to S. dysenteriae O7 and E. coli O121 were identified by PCR screening against representatives of 186 E. coli (including Shigella) O serotypes. E. coli O121 and S. dysenteriae O7 isolates can be distinguished by PCR of the H antigen fliC gene.
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Affiliation(s)
- Lu Feng
- College of Life Sciences, Nankai University, Tianjin, China
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45
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Myssina S, Huber SM, Birka C, Lang PA, Lang KS, Friedrich B, Risler T, Wieder T, Lang F. Inhibition of erythrocyte cation channels by erythropoietin. J Am Soc Nephrol 2004; 14:2750-7. [PMID: 14569084 DOI: 10.1097/01.asn.0000093253.42641.c1] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Recombinant human erythropoietin therapy is used to counteract anemia that is the result of renal insufficiency. It stimulates the formation of peripheral blood erythrocytes by inhibiting apoptosis of erythrocyte precursor cells. Mature erythrocytes have similarly been shown to undergo apoptosis. Hyperosmotic shock and Cl(-) removal activate a Ca(2+)-permeable, ethylisopropylamiloride-inhibitable cation channel. The subsequent increase of cytosolic Ca(2+) activates a scramblase that breaks down cell membrane phosphatidylserine asymmetry, leading to annexin binding. Studied was whether channel activity and erythrocyte cell death are regulated by erythropoietin. Scatchard plot analysis disclosed low-abundance, high-affinity binding of (125)I-erythropoietin to erythrocytes. Whole cell patch clamp experiments revealed significant inhibition of the ethylisopropylamiloride-sensitive current by 1 U/ml erythropoietin. Cl(-) removal triggered annexin binding, an effect abrogated by erythropoietin (1 U/ml) but not by GM-CSF (10 ng/ml). Osmotic shock (700 mOsm) stimulated annexin binding within 24 h in the majority of the erythrocytes, an effect blunted by erythropoietin (1 U/ml) but not by GM-CSF (10 ng/ml). In the nominal absence of Ca(2+), the effect of osmotic shock was blunted and the effect of erythropoietin abolished. In hemodialysis patients, intravenous administration of erythropoietin (50 IU/kg) within 4 h decreased the number of annexin binding circulating erythrocytes. Erythropoietin binds to erythrocytes and inhibits volume-sensitive erythrocyte cation channels and thus the breakdown of phosphatidylserine asymmetry after activation of this channel. The effect could prolong the erythrocyte lifespan and may contribute to the enhancement of the erythrocyte number during erythropoietin therapy in dialysis patients.
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Frasch SC, Henson PM, Nagaosa K, Fessler MB, Borregaard N, Bratton DL. Phospholipid Flip-Flop and Phospholipid Scramblase 1 (PLSCR1) Co-localize to Uropod Rafts in Formylated Met-Leu-Phe-stimulated Neutrophils. J Biol Chem 2004; 279:17625-33. [PMID: 14766753 DOI: 10.1074/jbc.m313414200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [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: 11/06/2022] Open
Abstract
Movement of phosphatidylserine (PS) to the plasma membrane outer leaflet is a nearly universal marker of apoptosis and occurs during activation of many cells. Neutrophils stimulated with the chemotactic peptide formylated Met-Leu-Phe (fMLP) demonstrated transient PS exposure. Stimulated outward movement of PS was accompanied by enhanced inward movement of several phosphorylcholine lipid probes and was associated with enhanced FM 1-43 staining indicative of phospholipid packing changes. Unlike apoptosis, inward movement of exogenously added fluorescent PS did not decline, and DNA was not cleaved during fMLP stimulation. Movement of phospholipids occurred within minutes following stimulation, was independent of endocytosis/pinocytosis, and was consistent with bidirectional, transbilayer phospholipid flip-flop. While the role of phospholipid scramblase 1 (PLSCR1) is controversial in flip-flop, we sought evidence for its role in enhanced phospholipid movements during fMLP stimulation. Using antibodies to the carboxyl-terminal domain of PLSCR1, its presence in the plasma membranes of non-permeabilized neutrophils was confirmed by flow cytometry. Additionally subcellular fractionation demonstrated that PLSCR1 was also located in secretory vesicles and tertiary and secondary granules. Activation of neutrophils with fMLP, however, did not significantly alter surface labeling suggesting that stimulated phospholipid flip-flop does not require additional mobilization of PLSCR1 to the plasma membrane. As expected for palmitoylated proteins, PLSCR1 was enriched in detergent-insoluble membranes and co-localized with raft markers at the neutrophil uropod after stimulation. Of note, PS exposure, phospholipid uptake, and FM 1-43 staining also localized to the uropod following stimulation demonstrating that both PLSCR1 and phospholipid flip-flop characterize this specialized domain of polarized neutrophils.
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Affiliation(s)
- S Courtney Frasch
- Department of Pediatrics, Division of Cell Biology, National Jewish Medical and Research Center, Denver, Colorado 80206, USA
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Monaco ME, Kim J, Ruan W, Wieczorek R, Kleinberg DL, Walden PD. Lipid metabolism in phosphatidylinositol transfer protein α-deficient vibrator mice. Biochem Biophys Res Commun 2004; 317:444-50. [PMID: 15063778 DOI: 10.1016/j.bbrc.2004.03.054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2004] [Indexed: 10/26/2022]
Abstract
Mice that are homozygous for the vibrator mutation express 65-85% less phosphatidylinositol transfer protein alpha (PITPalpha) than their wild type litter mates. By postnatal day 10-12 (P10-12) they exhibit signs of neurodegeneration and die prematurely by P40. In the present study, we examine the lipid content of brain, liver, and mammary glands from these animals. Lipid-mediated signal transduction is evaluated in primary fibroblast cultures. With respect to the lipid make-up of brain and liver, we report that there is a significant increase (2- to 4-fold) in the neutral lipids present in the livers of vb/vb animals when compared with wild type (+/+) litter mates. No significant changes are observed in the brains of these animals. The mammary glands of vb/vb mice are underdeveloped with respect to ductal and alveolar structures, and the fat pad is composed of predominantly brown adipose tissue rather than the white adipose tissue characteristic of age-matched wild type litter mates. No differences are observed in any aspect of lipid-mediated signal transduction.
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Affiliation(s)
- Marie E Monaco
- Department of Urology, NYU School of Medicine, New York, NY 10016, USA.
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48
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Huynh H, Wang X, Li W, Bottini N, Williams S, Nika K, Ishihara H, Godzik A, Mustelin T. Homotypic secretory vesicle fusion induced by the protein tyrosine phosphatase MEG2 depends on polyphosphoinositides in T cells. J Immunol 2004; 171:6661-71. [PMID: 14662869 DOI: 10.4049/jimmunol.171.12.6661] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Sec14p homology domains are found in a large number of proteins from plants, yeast, invertebrates, and higher eukaryotes. We report that the N-terminal Sec14p homology domain of the human protein tyrosine phosphatase PTP-MEG2 binds phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P(3)) in vitro and colocalizes with this lipid on secretory vesicle membranes in intact cells. Point mutations that prevented PtdIns(3,4,5)P(3) binding abrogated the capacity of PTP-MEG2 to induce homotypic secretory vesicle fusion in cells. Inhibition of cellular PtdIns(3,4,5)P(3) synthesis also rapidly reversed the effect of PTP-MEG2 on secretory vesicles. Finally, we show that several different phosphoinositide kinases colocalize with PTP-MEG2, thus allowing for local synthesis of PtdIns(3,4,5)P(3) in secretory vesicle membranes. We suggest that PTP-MEG2 through its Sec14p homology domain couples inositide phosphorylation to tyrosine dephosphorylation and the regulation of intracellular traffic of the secretory pathway in T cells.
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Affiliation(s)
- Huong Huynh
- Program of Signal Transduction, Cancer Research Center, The Burnham Institute, La Jolla, CA 92037, USA
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49
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Hilarius PM, Ebbing IG, Dekkers DWC, Lagerberg JWM, de Korte D, Verhoeven AJ. Generation of Singlet Oxygen Induces Phospholipid Scrambling in Human Erythrocytes. Biochemistry 2004; 43:4012-9. [PMID: 15049708 DOI: 10.1021/bi035637k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Maintenance of phospholipid asymmetry of the plasma membrane is essential for cells to prevent phagocytic removal or acceleration of coagulation. Photodynamic treatment (PDT), which relies on the generation of reactive oxygen species to achieve inactivation of pathogens, might be a promising approach in the future for decontamination of red blood cell concentrates. To investigate whether PDT affects phospholipid asymmetry, erythrocytes were illuminated in the presence of 1,9-dimethyl-methylene blue (DMMB) as photosensitizer and subsequently labeled with FITC-labeled annexin V. This treatment resulted in about 10% annexin V positive cells, indicating exposure of phosphatidylserine (PS). Treatment of erythrocytes with N-ethylmaleimide (NEM) prior to illumination, to inhibit inward translocation of PS via the aminophospholipid translocase, resulted in enhanced PS exposure, while treatment with H(2)O(2) (previously shown to inhibit phospholipid scrambling) greatly diminished PS exposure, indicating the induction of phospholipid scrambling by PDT. Only erythrocytes illuminated in the presence of DMMB showed translocation of NBD-phosphatidylcholine (NBD-PC), confirming scrambling induction. Double label experiments indicated that PS exposure does not occur without concurrent scrambling activity. Induction of scrambling was only moderately affected by Ca(2+) depletion of the cells. In contrast, scavengers of singlet oxygen were found to prevent phospholipid scrambling induced by PDT. The results of this study show that phospholipid scrambling is induced in human erythrocytes by exposure to singlet oxygen.
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Affiliation(s)
- P M Hilarius
- Sanquin Research at CLB, Plesmanlaan 125, 1066 CX Amsterdam, The Netherlands
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50
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Goumon Y, Angelone T, Schoentgen F, Chasserot-Golaz S, Almas B, Fukami MM, Langley K, Welters ID, Tota B, Aunis D, Metz-Boutigue MH. The Hippocampal Cholinergic Neurostimulating Peptide, the N-terminal Fragment of the Secreted Phosphatidylethanolamine-binding Protein, Possesses a New Biological Activity on Cardiac Physiology. J Biol Chem 2004; 279:13054-64. [PMID: 14724289 DOI: 10.1074/jbc.m308533200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphatidylethanolamine-binding protein (PEBP), alternatively named Raf-1 kinase inhibitor protein, is the precursor of the hippocampal cholinergic neurostimulating peptide (HCNP) corresponding to its natural N-terminal fragment, previously described to be released by hippocampal neurons. PEBP is a soluble cytoplasmic protein, also associated with plasma and reticulum membranes of numerous cell types. In the present report, using biochemistry and cell biology techniques, we report for the first time the presence of PEBP in bovine chromaffin cell, a well described secretion model. We have examined its presence at the subcellular level and characterized this protein on both secretory granule membranes and intragranular matrix. In addition, its presence in bovine chromaffin cell and platelet exocytotic medium, as well as in serum, was reported showing that it is secreted. Like many other proteins that lack signal sequence, PEBP may be secreted through non-classic signal secretory mechanisms, which could be due to interactions with granule membrane lipids and lipid rafts. By two-dimensional liquid chromatography-tandem mass spectrometry, HCNP was detected among the intragranular matrix components. The observation that PEBP and HCNP were secreted with catecholamines into the circulation prompted us to investigate endocrine effects of this peptide on cardiovascular system. By using as bioassay an isolated and perfused frog (Rana esculenta) heart preparation, we show here that HCNP acts on the cardiac mechanical performance exerting a negative inotropism and counteracting the adrenergic stimulation of isoproterenol. All together, these data suggest that PEBP and HCNP might be considered as new endocrine factors involved in cardiac physiology.
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Affiliation(s)
- Yannick Goumon
- INSERM Unité 575, Physiopathologie du Système Nerveux, IFR 37, 67084 Strasbourg, France
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