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Are cysteine residues of human phospholipid scramblase 1 essential for Pb 2+ and Hg 2+ binding-induced scrambling of phospholipids? EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 50:745-757. [PMID: 33787949 DOI: 10.1007/s00249-021-01521-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 03/06/2021] [Accepted: 03/20/2021] [Indexed: 10/21/2022]
Abstract
Lead and mercury being common environmental pollutants are often associated with erythrocytes, where phosphatidylserine (PS) exposure-mediated procoagulant activation is induced. Human phospholipid scramblase 1 (hPLSCR1) identified in the erythrocyte membrane is a type II transmembrane protein involved in Ca2+-dependent bidirectional scrambling of phospholipids (PL) during blood coagulation, cell activation, and apoptosis. The prominent role of hPLSCR1 in Pb2+ and Hg2+ poisoning was demonstrated by a biochemical assay, where recombinant hPLSCR1 induced PL scrambling across bilayer with a higher binding affinity (Kd) towards Hg2+ (4.1 µM) and Pb2+ (5.8 µM) than Ca2+ (25.6 mM). The increased affinity could be the outcome of heavy metals interacting at auxiliary sites other than the calcium-binding motif of hPLSCR1. Similar to other metal-binding proteins, cysteine-based metal-binding motifs could be the potential additional binding sites in hPLSCR1. To explore the hypothesis, the cysteines were chemically modified, which significantly reduced only the Hg2+- and Pb2+-induced scrambling activity leaving Ca2+-induced activity unaltered. Recombinant constructs with deletion of prominent cysteine residues and point mutation in the calcium-binding motif including Δ100-hPLSCR1, Δ160-hPLSCR1, and D275A-hPLSCR1 were generated, purified, and assayed for scramblase activity. The cysteine-deleted constructs of hPLSCR1 showed reduced binding affinity (Kd) for Hg2+ and Pb2+ without altering the Ca2+-binding affinity whereas the point mutant had completely lost its affinity for Ca2+ and reduced affinities for Hg2+ and Pb2+. The results accentuated the significance of cysteine residues as additional binding sites for heavy metal ions in hPLSCR1.
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2
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Ohkawa R, Low H, Mukhamedova N, Fu Y, Lai SJ, Sasaoka M, Hara A, Yamazaki A, Kameda T, Horiuchi Y, Meikle PJ, Pernes G, Lancaster G, Ditiatkovski M, Nestel P, Vaisman B, Sviridov D, Murphy A, Remaley AT, Sviridov D, Tozuka M. Cholesterol transport between red blood cells and lipoproteins contributes to cholesterol metabolism in blood. J Lipid Res 2020; 61:1577-1588. [PMID: 32907987 PMCID: PMC7707172 DOI: 10.1194/jlr.ra120000635] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Lipoproteins play a key role in transport of cholesterol to and from tissues. Recent studies have also demonstrated that red blood cells (RBCs), which carry large quantities of free cholesterol in their membrane, play an important role in reverse cholesterol transport. However, the exact role of RBCs in systemic cholesterol metabolism is poorly understood. RBCs were incubated with autologous plasma or isolated lipoproteins resulting in a significant net amount of cholesterol moved from RBCs to HDL, while cholesterol from LDL moved in the opposite direction. Furthermore, the bi-directional cholesterol transport between RBCs and plasma lipoproteins was saturable and temperature-, energy-, and time-dependent, consistent with an active process. We did not find LDLR, ABCG1, or scavenger receptor class B type 1 in RBCs but found a substantial amount of ABCA1 mRNA and protein. However, specific cholesterol efflux from RBCs to isolated apoA-I was negligible, and ABCA1 silencing with siRNA or inhibition with vanadate and Probucol did not inhibit the efflux to apoA-I, HDL, or plasma. Cholesterol efflux from and cholesterol uptake by RBCs from Abca1+/+ and Abca1-/- mice were similar, arguing against the role of ABCA1 in cholesterol flux between RBCs and lipoproteins. Bioinformatics analysis identified ABCA7, ABCG5, lipoprotein lipase, and mitochondrial translocator protein as possible candidates that may mediate the cholesterol flux. Together, these results suggest that RBCs actively participate in cholesterol transport in the blood, but the role of cholesterol transporters in RBCs remains uncertain.
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Affiliation(s)
- Ryunosuke Ohkawa
- Department of Analytical Laboratory Chemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Baker Heart and Diabetes Institute, Melbourne, Australia.
| | - Hann Low
- Baker Heart and Diabetes Institute, Melbourne, Australia
| | | | - Ying Fu
- Baker Heart and Diabetes Institute, Melbourne, Australia
| | - Shao-Jui Lai
- Department of Analytical Laboratory Chemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Mai Sasaoka
- Department of Analytical Laboratory Chemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Ayuko Hara
- Department of Analytical Laboratory Chemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Azusa Yamazaki
- Department of Analytical Laboratory Chemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takahiro Kameda
- Department of Analytical Laboratory Chemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yuna Horiuchi
- Department of Analytical Laboratory Chemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Peter J Meikle
- Baker Heart and Diabetes Institute, Melbourne, Australia
| | - Gerard Pernes
- Baker Heart and Diabetes Institute, Melbourne, Australia
| | | | | | - Paul Nestel
- Baker Heart and Diabetes Institute, Melbourne, Australia
| | - Boris Vaisman
- Lipoprotein Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Denis Sviridov
- Lipoprotein Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Andrew Murphy
- Baker Heart and Diabetes Institute, Melbourne, Australia
| | - Alan T Remaley
- Lipoprotein Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Dmitri Sviridov
- Baker Heart and Diabetes Institute, Melbourne, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia.
| | - Minoru Tozuka
- Department of Analytical Laboratory Chemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Life Science Research Center, Nagano Children's Hospital, Azumino, Japan
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3
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Borchert C, Herman A, Roth M, Brooks AC, Friedenberg SG. RNA sequencing of whole blood in dogs with primary immune-mediated hemolytic anemia (IMHA) reveals novel insights into disease pathogenesis. PLoS One 2020; 15:e0240975. [PMID: 33091028 PMCID: PMC7580939 DOI: 10.1371/journal.pone.0240975] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 10/06/2020] [Indexed: 11/29/2022] Open
Abstract
Immune-mediated hemolytic anemia (IMHA) is a life-threatening autoimmune disorder characterized by a self-mediated attack on circulating red blood cells. The disease occurs naturally in both dogs and humans, but is significantly more prevalent in dogs. Because of its shared features across species, dogs offer a naturally occurring model for studying IMHA in people. In this study, we used RNA sequencing of whole blood from treatment-naïve dogs to study transcriptome-wide changes in gene expression in newly diagnosed animals compared to healthy controls. We found many overexpressed genes in pathways related to neutrophil function, coagulation, and hematopoiesis. In particular, the most highly overexpressed gene in cases was a phospholipase scramblase, which mediates the externalization of phosphatidylserine from the inner to the outer leaflet of cell membranes. This family of genes has been shown to be critically important for programmed cell death of erythrocytes as well as the initiation of the clotting cascade. Unexpectedly, we found marked underexpression of many genes related to lymphocyte function. We also identified groups of genes that are highly associated with the inflammatory response and red blood cell regeneration in affected dogs. We did not find any genes that distinguished dogs that lived vs. those that died at 30 days following diagnosis, nor did we find any relevant genomic signatures of microbial organisms in the blood of affected animals. Future studies are warranted to validate these findings and assess their implication in developing novel therapeutic approaches for dogs and humans with IMHA.
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Affiliation(s)
- Corie Borchert
- Department of Veterinary Clinical Sciences, University of Minnesota College of Veterinary Medicine, St. Paul, Minnesota, United States of America
| | - Adam Herman
- Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Megan Roth
- Department of Veterinary Clinical Sciences, University of Minnesota College of Veterinary Medicine, St. Paul, Minnesota, United States of America
| | - Aimee C. Brooks
- Department of Veterinary Clinical Sciences, Purdue University College of Veterinary Medicine, West Lafayette, Indiana, United States of America
| | - Steven G. Friedenberg
- Department of Veterinary Clinical Sciences, University of Minnesota College of Veterinary Medicine, St. Paul, Minnesota, United States of America
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4
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Molecular cloning and biochemical characterization of the phospholipid scramblase SCRM-1 from Caenorhabditis elegans. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2020; 49:163-173. [DOI: 10.1007/s00249-020-01423-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 12/22/2019] [Accepted: 01/14/2020] [Indexed: 10/25/2022]
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5
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Palanirajan SK, Gummadi SN. Heavy-Metals-Mediated Phospholipids Scrambling by Human Phospholipid Scramblase 3: A Probable Role in Mitochondrial Apoptosis. Chem Res Toxicol 2019; 33:553-564. [PMID: 31769662 DOI: 10.1021/acs.chemrestox.9b00406] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Human phospholipid scramblases are a family of four homologous transmembrane proteins (hPLSCR1-4) mediating phospholipids (PLs) translocation in plasma membrane upon Ca2+ activation. hPLSCR3, the only homologue localized to mitochondria, plays a vital role in mitochondrial structure, function, maintenance, and apoptosis. Upon Ca2+ activation, hPLSCR3 mediates PL translocation at the mitochondrial membrane enhancing t-bid-induced cytochrome c release and apoptosis. Mitochondria are important target organelles for heavy-metals-induced apoptotic signaling cascade and are the central executioner of apoptosis to trigger. Pb2+ and Hg2+ toxicity mediates apoptosis by increased reactive oxygen species (ROS) and cytochrome c release from mitochondria. To discover the role of hPLSCR3 in heavy metal toxicity, hPLSCR3 was overexpressed as a recombinant protein in Escherichia coli Rosetta (DE3) and purified by affinity chromatography. The biochemical assay using synthetic proteoliposomes demonstrated that hPLSCR3 translocated aminophospholipids in the presence of micromolar concentrations of Pb2+ and Hg2+. A point mutation in the Ca2+-binding motif (F258V) led to a ∼60% loss in the functional activity and decreased binding affinities for Pb2+ and Hg2+ implying that the divalent heavy metal ions bind to the Ca2+-binding motif. This was further affirmed by the characteristic spectra observed with stains-all dye. The conformational changes upon heavy metal binding were monitored by circular dichroism, intrinsic tryptophan fluorescence, and light-scattering studies. Our results revealed that Pb2+ and Hg2+ bind to hPLSCR3 with higher affinity than Ca2+ thus mediating scramblase activity. To summarize, this is the first biochemical evidence for heavy metals binding to the mitochondrial membrane protein leading to bidirectional translocation of PLs specifically toward phosphatidylethanolamine.
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Affiliation(s)
- Santosh Kumar Palanirajan
- Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences , Indian Institute of Technology Madras , Chennai 600 036 , India
| | - Sathyanarayana N Gummadi
- Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences , Indian Institute of Technology Madras , Chennai 600 036 , India
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6
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Palanirajan SK, Gummadi SN. Rapid method for an enhanced recovery of biologically active human phospholipid scramblase1 from inclusion bodies. Anal Biochem 2018; 556:104-111. [DOI: 10.1016/j.ab.2018.06.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 06/28/2018] [Accepted: 06/28/2018] [Indexed: 01/05/2023]
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7
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Ahyayauch H, García-Arribas AB, Sot J, González-Ramírez EJ, Busto JV, Monasterio BG, Jiménez-Rojo N, Contreras FX, Rendón-Ramírez A, Martin C, Alonso A, Goñi FM. Pb(II) Induces Scramblase Activation and Ceramide-Domain Generation in Red Blood Cells. Sci Rep 2018; 8:7456. [PMID: 29748552 PMCID: PMC5945622 DOI: 10.1038/s41598-018-25905-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 04/19/2018] [Indexed: 01/01/2023] Open
Abstract
The mechanisms of Pb(II) toxicity have been studied in human red blood cells using confocal microscopy, immunolabeling, fluorescence-activated cell sorting and atomic force microscopy. The process follows a sequence of events, starting with calcium entry, followed by potassium release, morphological change, generation of ceramide, lipid flip-flop and finally cell lysis. Clotrimazole blocks potassium channels and the whole process is inhibited. Immunolabeling reveals the generation of ceramide-enriched domains linked to a cell morphological change, while the use of a neutral sphingomyelinase inhibitor greatly delays the process after the morphological change, and lipid flip-flop is significantly reduced. These facts point to three major checkpoints in the process: first the upstream exchange of calcium and potassium, then ceramide domain formation, and finally the downstream scramblase activation necessary for cell lysis. In addition, partial non-cytotoxic cholesterol depletion of red blood cells accelerates the process as the morphological change occurs faster. Cholesterol could have a role in modulating the properties of the ceramide-enriched domains. This work is relevant in the context of cell death, heavy metal toxicity and sphingolipid signaling.
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Affiliation(s)
- Hasna Ahyayauch
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Institut Supérieur des Professions Infirmières et des Techniques de Santé, Rabat, Morocco.,Neuroendocrinology Unit, Laboratory of Genetics, Neuroendocrinology and Biotechnology, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco
| | - Aritz B García-Arribas
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Jesús Sot
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain
| | - Emilio J González-Ramírez
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Jon V Busto
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Bingen G Monasterio
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Noemi Jiménez-Rojo
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain.,NCCR Chemical Biology, Department of Biochemistry, University of Geneva, 1211, Geneva, Switzerland
| | - F Xabier Contreras
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Adela Rendón-Ramírez
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Cesar Martin
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Alicia Alonso
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain.,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain
| | - Félix M Goñi
- Instituto Biofisika (CSIC, UPV/EHU), 48080, Bilbao, Spain. .,Departamento de Bioquímica, University of the Basque Country (UPV/EHU), 48080, Bilbao, Spain.
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8
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Palanirajan SK, Sivagnanam U, Murugan S, Gummadi SN. In vitro reconstitution and biochemical characterization of human phospholipid scramblase 3: phospholipid specificity and metal ion binding studies. Biol Chem 2018; 399:361-374. [DOI: 10.1515/hsz-2017-0309] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 12/14/2017] [Indexed: 01/11/2023]
Abstract
AbstractHuman phospholipid scramblase 3 (hPLSCR3) is a single pass transmembrane protein that plays a vital role in fat metabolism, mitochondrial function, structure, maintenance and apoptosis. The mechanism of action of scramblases remains still unknown, and the role of scramblases in phospholipid translocation is heavily debated. hPLSCR3 is the only member of scramblase family localized to mitochondria and is involved in cardiolipin translocation at the mitochondrial membrane. Direct biochemical evidence of phospholipid translocation by hPLSCR3 is yet to be reported. Functional assay in synthetic proteoliposomes upon Ca2+and Mg2+revealed that, apart from cardiolipin, recombinant hPLSCR3 translocates aminophospholipids such as NBD-PE and NBD-PS but not neutral phospholipids. Point mutation in hPLSCR3 (F258V) resulted in decreased Ca2+binding affinity. Functional assay with F258V-hPLSCR3 led to ~50% loss in scramblase activity in the presence of Ca2+and Mg2+. Metal ion-induced conformational changes were monitored by intrinsic tryptophan fluorescence, circular dichroism, surface hydrophobicity changes and aggregation studies. Our results revealed that Ca2+and Mg2+bind to hPLSCR3 and trigger conformational changes mediated by aggregation. In summary, we suggest that the metal ion-induced conformational change and the aggregation of the protein are essential for the phospholipid translocation by hPLSCR3.
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9
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Sivagnanam U, Palanirajan SK, Gummadi SN. The role of human phospholipid scramblases in apoptosis: An overview. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:2261-2271. [PMID: 28844836 DOI: 10.1016/j.bbamcr.2017.08.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/03/2017] [Accepted: 08/10/2017] [Indexed: 02/08/2023]
Abstract
Human phospholipid scramblases (hPLSCRs) are a family of four homologous single pass transmembrane proteins (hPLSCR1-4) initially identified as the proteins responsible for Ca2+ mediated bidirectional phospholipid translocation in plasma membrane. Though in-vitro assays had provided evidence, the role of hPLSCRs in phospholipid translocation is still debated. Recent reports revealed a new class of proteins, TMEM16 and Xkr8 to exhibit scramblase activity challenging the function of hPLSCRs. Apart from phospholipid scrambling, numerous reports have emphasized the multifunctional roles of hPLSCRs in key cellular processes including tumorigenesis, antiviral defense, protein and DNA interactions, transcriptional regulation and apoptosis. In this review, the role of hPLSCRs in mediating cell death through phosphatidylserine exposure, interaction with death receptors, cardiolipin exposure, heavy metal and radiation induced apoptosis and pathological apoptosis followed by their involvement in cancer cells are discussed. This review aims to connect the multifunctional characteristics of hPLSCRs to their decisive involvement in apoptotic pathways.
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Affiliation(s)
- Ulaganathan Sivagnanam
- Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600 036, India
| | - Santosh Kumar Palanirajan
- Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600 036, India
| | - Sathyanarayana N Gummadi
- Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600 036, India.
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Manzur-Jattin F, Álvarez-Ortega N, Moneriz-Pretell C, Corrales-Santander H, Cantillo-García K. Eriptosis: mecanismos moleculares y su implicación en la enfermedad aterotrombótica. REVISTA COLOMBIANA DE CARDIOLOGÍA 2016. [DOI: 10.1016/j.rccar.2015.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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11
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Borné Y, Söderholm M, Barregard L, Fagerberg B, Persson M, Melander O, Thévenod F, Hedblad B, Engström G. Genome wide association study identifies two loci associated with cadmium in erythrocytes among never-smokers. Hum Mol Genet 2016; 25:2342-2348. [DOI: 10.1093/hmg/ddw083] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 03/09/2016] [Indexed: 12/15/2022] Open
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12
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Hernández G, Bernès S, Portillo O, Ruíz A, Moreno GE, Gutiérrez R. Crystal structures of three mercury(II) complexes [HgCl2 L] where L is a bidentate chiral imine ligand. Acta Crystallogr E Crystallogr Commun 2015; 71:1462-6. [PMID: 26870405 PMCID: PMC4719814 DOI: 10.1107/s2056989015020368] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 10/28/2015] [Indexed: 11/30/2022]
Abstract
The crystal structures of three complexes [HgCl2 L] were determined, namely, (S)-(+)-di-chlorido-[1-phenyl-N-(pyridin-2-yl-methyl-idene)ethyl-amine-κ(2) N,N']mercury(II), [HgCl2(C14H14N2)], (S)-(+)-di-chlorido-[1-(4-methyl-phen-yl)-N-(pyridin-2-yl-methyl-idene)ethyl-amine-κ(2) N,N']mercury(II), [HgCl2(C15H16N2)], and (1S,2S,3S,5R)-(+)-di-chlorido-[N-(pyridin-2-yl-methyl-idene)isopino-camph-eyl-amine-κ(2) N,N']mercury(II), [HgCl2(C16H22N2)]. The complexes consist of a bidentate chiral imine ligand coordinating to HgCl2 and crystallize with four independent mol-ecules in the first complex and two independent mol-ecules in the other two. The coordination geometry of mercury is tetra-hedral, with strong distortion towards a disphenoidal geometry, as a consequence of the imine bite angle being close to 70°. The Cl-Hg-Cl angles span a large range, 116.0 (2)-138.3 (3)°, which is related to the aggregation state in the crystals. For small Cl-Hg-Cl angles, complexes have a tendency to form dimers, via inter-molecular Hg⋯Cl contacts. These contacts become less significant in the third complex, which features the largest intra-molecular Cl-Hg-Cl angles.
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Affiliation(s)
- Guadalupe Hernández
- Laboratorio de Síntesis de Complejos, Facultad de Ciencias Químicas, Universidad Autónoma de Puebla, A.P. 1067, 72001 Puebla, Pue., Mexico
| | - Sylvain Bernès
- Instituto de Física, Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue., Mexico
| | - Oscar Portillo
- Laboratorio de Síntesis de Complejos, Facultad de Ciencias Químicas, Universidad Autónoma de Puebla, A.P. 1067, 72001 Puebla, Pue., Mexico
| | - Alejandro Ruíz
- Departamento de Microbiología, Facultad de Ciencias Químicas, Universidad Autónoma de Puebla, Puebla, Pue., Mexico
| | - Gloria E. Moreno
- Laboratorio de Síntesis de Complejos, Facultad de Ciencias Químicas, Universidad Autónoma de Puebla, A.P. 1067, 72001 Puebla, Pue., Mexico
| | - René Gutiérrez
- Laboratorio de Síntesis de Complejos, Facultad de Ciencias Químicas, Universidad Autónoma de Puebla, A.P. 1067, 72001 Puebla, Pue., Mexico
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13
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P4-ATPases: lipid flippases in cell membranes. Pflugers Arch 2015; 466:1227-40. [PMID: 24077738 PMCID: PMC4062807 DOI: 10.1007/s00424-013-1363-4] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 09/11/2013] [Accepted: 09/11/2013] [Indexed: 12/13/2022]
Abstract
Cellular membranes, notably eukaryotic plasma membranes, are equipped with special proteins that actively translocate lipids from one leaflet to the other and thereby help generate membrane lipid asymmetry. Among these ATP-driven transporters, the P4 subfamily of P-type ATPases (P4-ATPases) comprises lipid flippases that catalyze the translocation of phospholipids from the exoplasmic to the cytosolic leaflet of cell membranes. While initially characterized as aminophospholipid translocases, recent studies of individual P4-ATPase family members from fungi, plants, and animals show that P4-ATPases differ in their substrate specificities and mediate transport of a broader range of lipid substrates, including lysophospholipids and synthetic alkylphospholipids. At the same time, the cellular processes known to be directly or indirectly affected by this class of transporters have expanded to include the regulation of membrane traffic, cytoskeletal dynamics, cell division, lipid metabolism, and lipid signaling. In this review, we will summarize the basic features of P4-ATPases and the physiological implications of their lipid transport activity in the cell.
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14
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Kwon SY, Bae ON, Noh JY, Kim K, Kang S, Shin YJ, Lim KM, Chung JH. Erythrophagocytosis of lead-exposed erythrocytes by renal tubular cells: possible role in lead-induced nephrotoxicity. ENVIRONMENTAL HEALTH PERSPECTIVES 2015; 123:120-7. [PMID: 25302504 PMCID: PMC4314246 DOI: 10.1289/ehp.1408094] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 10/07/2014] [Indexed: 05/22/2023]
Abstract
BACKGROUND Nephrotoxicity associated with lead poisoning has been frequently reported in epidemiological studies, but the underlying mechanisms have not been fully described. OBJECTIVES We examined the role of erythrocytes, one of the major lead reservoirs, in lead-associated nephrotoxicity. METHODS AND RESULTS Co-incubation of lead-exposed human erythrocytes with HK-2 human renal proximal tubular cells resulted in renal tubular cytotoxicity, suggesting a role of erythrocytes in lead-induced nephrotoxicity. Morphological and flow cytometric analyses revealed that HK-2 cells actively phagocytized lead-exposed erythrocytes, which was associated with phosphatidylserine (PS) externalization on the erythrocyte membrane and generation of PS-bearing microvesicles. Increased oxidative stress and up-regulation of nephrotoxic biomarkers, such as NGAL, were observed in HK-2 cells undergoing erythrophagocytosis. Moreover, TGF-β, a marker of fibrosis, was also significantly up-regulated. We examined the significance of erythrophagocytosis in lead-induced nephrotoxicity in rats exposed to lead via drinking water for 12 weeks. We observed iron deposition and generation of oxidative stress in renal tissues of lead-exposed rats, as well as the histopathological alterations such as tubulointerstitial lesions, fibrosis, and up-regulation of KIM-1, NGAL, and TGF-β. CONCLUSIONS Our data strongly suggest that erythrophagocytosis and subsequent iron deposition in renal tubular cells could significantly enhance nephrotoxicity following lead exposure, providing insight on lead-associated kidney damages.
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Affiliation(s)
- So-Youn Kwon
- College of Pharmacy, Seoul National University, Seoul, Korea
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15
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Kodigepalli KM, Bowers K, Sharp A, Nanjundan M. Roles and regulation of phospholipid scramblases. FEBS Lett 2014; 589:3-14. [PMID: 25479087 DOI: 10.1016/j.febslet.2014.11.036] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/22/2014] [Accepted: 11/24/2014] [Indexed: 02/06/2023]
Abstract
Phospholipid scramblase activity is involved in the collapse of phospholipid (PL) asymmetry at the plasma membrane leading to externalization of phosphatidylserine. This activity is crucial for initiation of the blood coagulation cascade and for recognition/elimination of apoptotic cells by macrophages. Efforts to identify gene products associated with this activity led to the characterization of PL scramblase (PLSCR) and XKR family members which contribute to phosphatidylserine exposure in response to apoptotic stimuli. Meanwhile, TMEM16 family members were identified to externalize phosphatidylserine in response to elevated calcium in Scott syndrome platelets, which is critical for activation of the coagulation cascade. Herein, we report their mechanisms of gene regulation, molecular functions independent of their scrambling activity, and their potential roles in pathogenic conditions.
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Affiliation(s)
- Karthik M Kodigepalli
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL 33620, United States
| | - Kiah Bowers
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL 33620, United States
| | - Arielle Sharp
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL 33620, United States
| | - Meera Nanjundan
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL 33620, United States.
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16
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Xu Y, Jiang Z, Xiao Y, Zhang TT, Miao JY, Zhao BX. A new fluorescent turn-on chemodosimeter for mercury ions in solution and its application in cells and organisms. Anal Chim Acta 2014; 807:126-34. [DOI: 10.1016/j.aca.2013.11.042] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 11/11/2013] [Accepted: 11/19/2013] [Indexed: 12/11/2022]
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