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Haase S, Condron M, Miller D, Cherkaoui D, Jordan S, Gulbis JM, Baum J. Identification and characterisation of a phospholipid scramblase in the malaria parasite Plasmodium falciparum. Mol Biochem Parasitol 2021; 243:111374. [PMID: 33974939 PMCID: PMC8202325 DOI: 10.1016/j.molbiopara.2021.111374] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/27/2021] [Accepted: 05/06/2021] [Indexed: 02/07/2023]
Abstract
Recent studies highlight the emerging role of lipids as important messengers in malaria parasite biology. In an attempt to identify interacting proteins and regulators of these dynamic and versatile molecules, we hypothesised the involvement of phospholipid translocases and their substrates in the infection of the host erythrocyte by the malaria parasite Plasmodium spp. Here, using a data base searching approach of the Plasmodium Genomics Resources (www.plasmodb.org), we have identified a putative phospholipid (PL) scramblase in P. falciparum (PfPLSCR) that is conserved across the genus and in closely related unicellular algae. By reconstituting recombinant PfPLSCR into liposomes, we demonstrate metal ion dependent PL translocase activity and substrate preference, confirming PfPLSCR as a bona fide scramblase. We show that PfPLSCR is expressed during asexual and sexual parasite development, localising to different membranous compartments of the parasite throughout the intra-erythrocytic life cycle. Two different gene knockout approaches, however, suggest that PfPLSCR is not essential for erythrocyte invasion and asexual parasite development, pointing towards a possible role in other stages of the parasite life cycle.
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Affiliation(s)
- Silvia Haase
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK.
| | - Melanie Condron
- Division of Infection and Immunity, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
| | - David Miller
- Division of Structural Biology, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
| | - Dounia Cherkaoui
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK
| | - Sarah Jordan
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK
| | - Jacqueline M Gulbis
- Division of Structural Biology, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Jake Baum
- Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London, UK.
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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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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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Sandamalika WMG, Priyathilaka TT, Nam BH, Lee J. Two phospholipid scramblase 1-related proteins (PLSCR1like-a & -b) from Liza haematocheila: Molecular and transcriptional features and expression analysis after immune stimulation. FISH & SHELLFISH IMMUNOLOGY 2019; 87:32-42. [PMID: 30593902 DOI: 10.1016/j.fsi.2018.12.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 12/17/2018] [Accepted: 12/21/2018] [Indexed: 06/09/2023]
Abstract
Phospholipid scramblases (PLSCRs) are a family of transmembrane proteins known to be responsible for Ca2+-mediated bidirectional phospholipid translocation in the plasma membrane. Apart from the scrambling activity of PLSCRs, recent studies revealed their diverse other roles, including antiviral defense, tumorigenesis, protein-DNA interactions, apoptosis regulation, and cell activation. Nonetheless, the biological and transcriptional functions of PLSCRs in fish have not been discovered to date. Therefore, in this study, two new members related to the PLSCR1 family were identified in the red lip mullet (Liza haematocheila) as MuPLSCR1like-a and MuPLSCR1like-b, and their characteristics were studied at molecular and transcriptional levels. Sequence analysis revealed that MuPLSCR1like-a and MuPLSCR1like-b are composed of 245 and 228 amino acid residues (aa) with the predicted molecular weights of 27.82 and 25.74 kDa, respectively. A constructed phylogenetic tree showed that MuPLSCR1like-a and MuPLSCR1like-b are clustered together with other known PLSCR1 and -2 orthologues, thus pointing to the relatedness to both PLSCR1 and PLSCR2 families. Two-dimensional (2D) and 3D graphical representations illustrated the well-known 12-stranded β-barrel structure of MuPLSCR1like-a and MuPLSCR1like-b with transmembrane orientation toward the phospholipid bilayer. In analysis of tissue-specific expression, the highest expression of MuPLSCR1like-a was observed in the intestine, whereas MuPLSCR1like-b was highly expressed in the brain, indicating isoform specificity. Of note, we found that the transcription of MuPLSCR1like-a and MuPLSCR1like-b was significantly upregulated when the fish were stimulated with poly(I:C), suggesting that such immune responses target viral infections. Overall, this study provides the first experimental insight into the characteristics and immune-system relevance of PLSCR1-related genes in red lip mullets.
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Affiliation(s)
- W M Gayashani Sandamalika
- Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea
| | - Thanthrige Thiunuwan Priyathilaka
- Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea
| | - Bo-Hye Nam
- Biotechnology Research Division, National Institute of Fisheries Science, 408-1 Sirang-ri, Gijang-up, Gijang-gun, Busan, 46083, Republic of Korea
| | - Jehee Lee
- Department of Marine Life Sciences & Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea.
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Li C, Wang J, Song K, Meng J, Xu F, Li L, Zhang G. Construction of a high-density genetic map and fine QTL mapping for growth and nutritional traits of Crassostrea gigas. BMC Genomics 2018; 19:626. [PMID: 30134839 PMCID: PMC6106840 DOI: 10.1186/s12864-018-4996-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 08/03/2018] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Both growth and nutritional traits are important economic traits of Crassostrea gigas (C. gigas) in industry. But few work has been done to study the genetic architecture of nutritional traits of the oyster. In this study, we constructed a high-density genetic map of C. gigas to help assemble the genome sequence onto chromosomes, meanwhile explore the genetic basis for nutritional traits via quantitative trait loci (QTL) mapping. RESULTS The constructed genetic map contained 5024 evenly distributed markers, with an average marker interval of 0.68 cM, thus representing the densest genetic map produced for the oyster. According to the high collinearity between the consensus map and the oyster genome, 1574 scaffold (about 70%) of the genome sequence of C. gigas were successfully anchored to 10 linkage groups (LGs) of the consensus map. Using this high-qualified genetic map, we then conducted QTL analysis for growth and nutritional traits, the latter of which includes glycogen, amino acid (AA), and fatty acid (FA). Overall, 41 QTLs were detected for 17 traits. In addition, six candidate genes identified in the QTL interval showed significant correlation with the traits on transcriptional levels. These genes include growth-related genes AMY and BMP1, AA metabolism related genes PLSCR and GR, and FA metabolism regulation genes DYRK and ADAMTS. CONCLUSION Using the constructed high-qualified linkage map, this study not only assembled nearly 70% of the oyster genome sequence onto chromosomes, but also identified valuable markers and candidate genes for growth and nutritional traits, especially for AA and FA that undergone few studies before. These findings will facilitate genome assembly and molecular breeding of important economic traits in C. gigas.
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Affiliation(s)
- Chunyan Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- National & Local Joint Engineering Laboratory of Ecological Mariculture, Chinese Academy of Sciences, Institute of Oceanology, Qingdao, China
| | - Jinpeng Wang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- National & Local Joint Engineering Laboratory of Ecological Mariculture, Chinese Academy of Sciences, Institute of Oceanology, Qingdao, China
| | - Kai Song
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- National & Local Joint Engineering Laboratory of Ecological Mariculture, Chinese Academy of Sciences, Institute of Oceanology, Qingdao, China
| | - Jie Meng
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- National & Local Joint Engineering Laboratory of Ecological Mariculture, Chinese Academy of Sciences, Institute of Oceanology, Qingdao, China
| | - Fei Xu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- National & Local Joint Engineering Laboratory of Ecological Mariculture, Chinese Academy of Sciences, Institute of Oceanology, Qingdao, China
| | - Li Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
- Laboratory for Marine Fisheries and Aquaculture, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.
- National & Local Joint Engineering Laboratory of Ecological Mariculture, Chinese Academy of Sciences, Institute of Oceanology, Qingdao, China.
| | - Guofan Zhang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.
- National & Local Joint Engineering Laboratory of Ecological Mariculture, Chinese Academy of Sciences, Institute of Oceanology, Qingdao, China.
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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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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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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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Andraka N, Sánchez-Magraner L, García-Pacios M, Goñi FM, Arrondo JLR. The conformation of human phospholipid scramblase 1, as studied by infrared spectroscopy. Effects of calcium and detergent. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1019-1028. [PMID: 28238818 DOI: 10.1016/j.bbamem.2017.02.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 02/18/2017] [Accepted: 02/22/2017] [Indexed: 12/18/2022]
Abstract
Human phospholipid scramblase 1 (SCR) is a membrane protein that catalyzes the transmembrane (flip-flop) motion of phospholipids. It can also exist in a non membrane-bound form in the nucleus, where it modulates several aspects of gene expression. Catalysis of phospholipid flip-flop requires the presence of millimolar Ca2+, and occurs in the absence of ATP. Membrane-bound SCR contains a C-terminal α-helical domain embedded in the membrane bilayer. The latter domain can be removed giving rise to a stable truncated mutant SCRΔ that is devoid of scramblase activity. In order to improve our understanding of SCR structure infrared spectra have been recorded of both the native and truncated forms, and the effects of adding Ca2+, or removing detergent, or thermally denaturing the protein have been observed. Under all conditions the main structural component of SCR/SCRΔ is a β-sheet. Removing the C-terminal 28 aa residues, which anchor SCR to the membrane, leads to a change in tertiary structure and an increased structural flexibility. The main effect of Ca2+ is an increase in the α/β ratio of secondary structure components, with a concomitant increase in the proportion of non-periodic structures. At least in SCRΔ, detergent (Zwittergent 3-12) decreases the structural flexibility, an effect somewhat opposite to that of increasing temperature. Thermal denaturation is affected by Ca2+, detergent, and by the presence or absence of the C-terminal domain, each of them influencing in different ways the denaturation pattern.
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Affiliation(s)
- Nagore Andraka
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain
| | - Lissete Sánchez-Magraner
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain
| | - Marcos García-Pacios
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain
| | - Félix M Goñi
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain
| | - José L R Arrondo
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, P.O. Box 644, 48080 Bilbao, Spain.
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10
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Sivagnanam U, Narayana Murthy S, Gummadi SN. Identification and characterization of the novel nuclease activity of human phospholipid scramblase 1. BMC BIOCHEMISTRY 2016; 17:10. [PMID: 27206388 PMCID: PMC4875679 DOI: 10.1186/s12858-016-0067-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 05/17/2016] [Indexed: 01/05/2023]
Abstract
Background Human phospholipid scramblase 1 (hPLSCR1) was initially identified as a Ca2+ dependent phospholipid translocator involved in disrupting membrane asymmetry. Recent reports revealed that hPLSCR1 acts as a multifunctional signaling molecule rather than functioning as scramblase. hPLSCR1 is overexpressed in a variety of tumor cells and is known to interact with a number of protein molecules implying diverse functions. Results In this study, the nuclease activity of recombinant hPLSCR1 and its biochemical properties have been determined. Point mutations were generated to identify the critical region responsible for the nuclease activity. Recombinant hPLSCR1 exhibits Mg2+ dependent nuclease activity with an optimum pH and temperature of 8.5 and 37 °C respectively. Experiments with amino acid modifying reagents revealed that histidine, cysteine and arginine residues were crucial for its function. hPLSCR1 has five histidine residues and point mutations of histidine residues to alanine in hPLSCR1 resulted in 60 % loss in nuclease activity. Thus histidine residues could play a critical role in the nuclease activity of hPLSCR1. Conclusions This is the first report on the novel nuclease activity of the multi-functional hPLSCR1. hPLSCR1 shows a metal dependent nuclease activity which could play a role in key cellular processes that needs to be further investigated.
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Affiliation(s)
- Ulaganathan Sivagnanam
- From the Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600 036, India
| | - Shweta Narayana Murthy
- From the 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
- From the 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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11
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Kassas A, Moura IC, Yamashita Y, Scheffel J, Guérin-Marchand C, Blank U, Sims PJ, Wiedmer T, Monteiro RC, Rivera J, Charles N, Benhamou M. Regulation of the tyrosine phosphorylation of Phospholipid Scramblase 1 in mast cells that are stimulated through the high-affinity IgE receptor. PLoS One 2014; 9:e109800. [PMID: 25289695 PMCID: PMC4188579 DOI: 10.1371/journal.pone.0109800] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 09/14/2014] [Indexed: 01/05/2023] Open
Abstract
Engagement of high-affinity immunoglobulin E receptors (FcεRI) activates two signaling pathways in mast cells. The Lyn pathway leads to recruitment of Syk and to calcium mobilization whereas the Fyn pathway leads to phosphatidylinositol 3-kinase recruitment. Mapping the connections between both pathways remains an important task to be completed. We previously reported that Phospholipid Scramblase 1 (PLSCR1) is phosphorylated on tyrosine after cross-linking FcεRI on RBL-2H3 rat mast cells, amplifies mast cell degranulation, and is associated with both Lyn and Syk tyrosine kinases. Here, analysis of the pathway leading to PLSCR1 tyrosine phosphorylation reveals that it depends on the FcRγ chain. FcεRI aggregation in Fyn-deficient mouse bone marrow-derived mast cells (BMMC) induced a more robust increase in FcεRI-dependent tyrosine phosphorylation of PLSCR1 compared to wild-type cells, whereas PLSCR1 phosphorylation was abolished in Lyn-deficient BMMC. Lyn association with PLSCR1 was not altered in Fyn-deficient BMMC. PLSCR1 phosphorylation was also dependent on the kinase Syk and significantly, but partially, dependent on detectable calcium mobilization. Thus, the Lyn/Syk/calcium axis promotes PLSCR1 phosphorylation in multiple ways. Conversely, the Fyn-dependent pathway negatively regulates it. This study reveals a complex regulation for PLSCR1 tyrosine phosphorylation in FcεRI-activated mast cells and that PLSCR1 sits at a crossroads between Lyn and Fyn pathways.
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Affiliation(s)
- Asma Kassas
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
| | - Ivan C. Moura
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
| | - Yumi Yamashita
- Laboratory of Molecular Immunogenetics, Molecular Immunology and Inflammation Branch, NIAMSD, NIH, Bethesda, Maryland, United States of America
| | - Jorg Scheffel
- Laboratory of Molecular Immunogenetics, Molecular Immunology and Inflammation Branch, NIAMSD, NIH, Bethesda, Maryland, United States of America
| | - Claudine Guérin-Marchand
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
| | - Ulrich Blank
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
| | - Peter J. Sims
- Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Therese Wiedmer
- Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Renato C. Monteiro
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
| | - Juan Rivera
- Laboratory of Molecular Immunogenetics, Molecular Immunology and Inflammation Branch, NIAMSD, NIH, Bethesda, Maryland, United States of America
| | - Nicolas Charles
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
- * E-mail: (NC); (MB)
| | - Marc Benhamou
- INSERM U1149, Faculté de Médecine Xavier Bichat, Paris, France
- University Paris-Diderot, Sorbonne Paris Cité, Laboratoire d’excellence INFLAMEX, DHU FIRE, Paris, France
- * E-mail: (NC); (MB)
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12
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Slone EA, Fleming SD. Membrane lipid interactions in intestinal ischemia/reperfusion-induced Injury. Clin Immunol 2014; 153:228-40. [PMID: 24814240 DOI: 10.1016/j.clim.2014.04.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 04/10/2014] [Accepted: 04/29/2014] [Indexed: 01/02/2023]
Abstract
Ischemia, lack of blood flow, and reperfusion, return of blood flow, are a common phenomenon affecting millions of Americans each year. Roughly 30,000 Americans per year experience intestinal ischemia-reperfusion (IR), which is associated with a high mortality rate. Previous studies of the intestine established a role for neutrophils, eicosanoids, the complement system and naturally occurring antibodies in IR-induced pathology. Furthermore, data indicate involvement of a lipid or lipid-like moiety in mediating IR-induced damage. It has been proposed that antibodies recognize exposure of neo-antigens, triggering action of the complement cascade. While it is evident that the pathophysiology of IR-induced injury is complex and multi-factorial, we focus this review on the involvement of eicosanoids, phospholipids and neo-antigens in the early pathogenesis. Lipid changes occurring in response to IR, neo-antigens exposed and the role of a phospholipid transporter, phospholipid scramblase 1 will be discussed.
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Affiliation(s)
- Emily Archer Slone
- College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
| | - Sherry D Fleming
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
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13
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Membrane binding of human phospholipid scramblase 1 cytoplasmic domain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1785-92. [PMID: 24680654 DOI: 10.1016/j.bbamem.2014.03.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 03/12/2014] [Accepted: 03/18/2014] [Indexed: 02/08/2023]
Abstract
Human phospholipid scramblase 1 (SCR) consists of a large cytoplasmic domain and a small presumed transmembrane domain near the C-terminal end of the protein. Previous studies with the SCRΔ mutant lacking the C-terminal portion (last 28 aa) revealed the importance of this C-terminal moiety for protein function and calcium-binding affinity. The present contribution is intended to elucidate the effect of the transmembrane domain suppression on SCRΔ binding to model membranes (lipid monolayers and bilayers) and on SCRΔ reconstitution in proteoliposomes. In all cases the protein cytoplasmic domain showed a great affinity for lipid membranes, and behaved in most aspects as an intrinsic membrane protein. Assays have been performed in the presence of phosphatidylserine, presumably important for the SCR cytoplasmic domain to be electrostatically anchored to the plasma membrane inner surface. The fusion protein maltose binding protein-SCR has also been studied as an intermediate case of a molecule that can insert into the bilayer hydrophobic core, yet it is stable in detergent-free buffers. Although the intracellular location of SCR has been the object of debate, the present data support the view of SCR as an integral membrane protein, in which not only the transmembrane domain but also the cytoplasmic moiety play a role in membrane docking of the protein.
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14
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The C-terminal transmembrane domain of human phospholipid scramblase 1 is essential for the protein flip-flop activity and Ca²⁺-binding. J Membr Biol 2013; 247:155-65. [PMID: 24343571 DOI: 10.1007/s00232-013-9619-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 11/26/2013] [Indexed: 10/25/2022]
Abstract
Human phospholipid scramblase 1 (SCR) is a 318 amino acid protein that was originally described as catalyzing phospholipid transbilayer (flip-flop) motion in plasma membranes in a Ca²⁺-dependent, ATP-independent way. Further studies have suggested an intranuclear role for this protein in addition. A putative transmembrane domain located at the C terminus (aa 291-309) has been related to the flip-flop catalysis. In order to clarify the role of the C-terminal region of SCR, a mutant was produced (SCRΔ) in which the last 28 amino acid residues were lacking, including the α-helix. SCRΔ had lost the scramblase activity and its affinity for Ca²⁺ was decreased by one order of magnitude. Fluorescence and IR spectroscopic studies revealed that the C-terminal region of SCR was essential for the proper folding of the protein. Moreover, it was found that Ca²⁺ exerted an overall destabilizing effect on SCR, which might facilitate its binding to membranes.
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15
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Membrane binding and insertion of the predicted transmembrane domain of human scramblase 1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:388-97. [PMID: 24099740 DOI: 10.1016/j.bbamem.2013.09.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 09/19/2013] [Accepted: 09/25/2013] [Indexed: 10/26/2022]
Abstract
Human phospholipid scramblase 1 (SCR) was originally described as an intrinsic membrane protein catalyzing transbilayer phospholipid transfer in the absence of ATP. More recently, a role as a nuclear transcription factor has been proposed for SCR, either in addition or alternatively to its capacity to facilitate phospholipid flip-flop. Uncertainties exist as well from the structural point of view. A predicted α-helix (aa residues 288-306) located near the C-terminus has been alternatively proposed as a transmembrane domain, or as a protein core structural element. This paper explores the possibilities of the above helical segment as a transmembrane domain. To this aim two peptides were synthesized, one corresponding to the 19 α-helical residues, and one containing both the helix and the subsequent 12-residues constituting the C-end of the protein. The interaction of these peptides with lipid monolayers and bilayers was tested with Langmuir balance surface pressure measurements, proteoliposome reconstitution and analysis, differential scanning calorimetry, tests of bilayer permeability, and fluorescence confocal microscopy. Bilayers of 28 different lipid compositions were examined in which lipid electric charge, bilayer fluidity and lateral heterogeneity (domain formation) were varied. All the results concur in supporting the idea that the 288-306 peptide of SCR becomes membrane inserted in the presence of lipid bilayers. Thus, the data are in agreement with the possibility of SCR as an integral membrane protein, without rejecting alternative cell locations.
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Key Words
- 1,1,1,3,3,3-hexafluoro-2-propanol
- 1,1′-dioctadecyl-3,3,3′,3′-tetramethyl-indodicarbocyanine
- 8-aminonaphtalene-1,3,6-trisulfonic acid sodium salt
- ANTS
- DID
- DPX
- GUVs
- HFIP
- LUVs
- Lipid phases
- MLVs
- PC
- PE
- PG
- PI
- PLSCR1
- PS
- SCR
- SCR 288–306 peptide
- SCR 288–318 peptide
- Scramblase
- TM
- TM19
- TM31C
- Transbilayer
- Transmembrane helix
- giant unilamellar vesicles
- human phospholipid scramblase 1, or hPLSCR1
- large unilamellar vesicles
- multilamellar vesicles
- p-xylene-bis(pyridinium) bromide
- pSM
- palmitoyl sphingomyelin
- phosphatidylcholine
- phosphatidylethanolamine
- phosphatidylglycerol
- phosphatidylinositol
- phosphatidylserine
- transmembrane
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16
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Francis VG, Mohammed AM, Aradhyam GK, Gummadi SN. The single C-terminal helix of human phospholipid scramblase 1 is required for membrane insertion and scrambling activity. FEBS J 2013; 280:2855-69. [PMID: 23590222 DOI: 10.1111/febs.12289] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 03/12/2013] [Accepted: 04/15/2013] [Indexed: 11/29/2022]
Abstract
Human phospholipid scramblase 1 (hPLSCR1) belongs to the ATP-independent class of phospholipid translocators which possess a single EF-hand-like Ca(2+)-binding motif and also a C-terminal helix (CTH). The CTH domain of hPLSCR1 was believed to be a putative single transmembrane helix at the C-terminus. Recent homology modeling studies by Bateman et al. predicted that the hydrophobic nature of this helix is due to its packing in the core of the protein domain and proposed that this is not a true transmembrane helix [Bateman A, Finn RD, Sims PJ, Wiedmer T, Biegert A & Johannes S. Bioinformatics 2008, 25, 159]. To determine the exact function of the CTH of hPLSCR1, we deleted the CTH domain and determined: (a) whether CTH plays any role beyond membrane anchorage, (b) the functional consequences of CTH deletion, and (c) any conformational changes associated with CTH in a lipid environment. In vitro reconstitution studies confirm that the predicted CTH is required for membrane insertion and scrambling activity. CTH deletion caused a 50% decrease in binding affinity of Ca(2+) for ∆CTH-hPLSCR1 (K(a) = 115 μM) compared with hPLSCR1 (K(a) = 249 μM). Far UV-CD studies revealed that the CTH peptide adopts α-helicity only in the presence of SDS micelles and negatively charged vesicles, indicating that electrostatic interactions are required for insertion of the peptide. CTH peptide-quenching studies confirm that the predicted CTH inserts into the membrane and its ability to interact with the membrane depends on the presence of charge interactions. TOXCAT assay revealed that CTH of hPLSCR1 does not oligomerize in the membrane. We conclude that CTH is required for membrane insertion and Ca(2+) coordination and also plays an important role in the functional conformation of hPLSCR1.
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Affiliation(s)
- Vincent G Francis
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India
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17
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Shettihalli AK, Gummadi SN. Biochemical evidence for lead and mercury induced transbilayer movement of phospholipids mediated by human phospholipid scramblase 1. Chem Res Toxicol 2013; 26:918-25. [PMID: 23659204 DOI: 10.1021/tx400090h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Human phospholipid scramblase 1(hPLSCR1) is a transmembrane protein involved in bidirectional scrambling of plasma membrane phospholipids during cell activation, blood coagulation, and apoptosis in response to elevated intracellular Ca(2+) levels. Pb(2+) and Hg(2+) are known to cause procoagulant activation via phosphatidylserine exposure to the external surface in erythrocytes, resulting in blood coagulation. To explore its role in lead and mercury poisoning, hPLSCR1 was overexpressed in Escherichia coli BL21 (DE3) and purified using affinity chromatography. The biochemical assay showed rapid scrambling of phospholipids in the presence of Hg(2+) and Pb(2+). The binding constant (Ka) was calculated and found to be 250 nM(-1) and 170 nM(-1) for Hg(2+) and Pb(2+), respectively. The intrinsic tryptophan fluorescence and far ultraviolet circular dichroism studies revealed that Hg(2+) and Pb(2+) bind to hPLSCR1 and induce conformational changes. hPLSCR1 treated with protein modifying reagent N-ethylmaleimide before functional reconstitution showed 40% and 24% inhibition in the presence of Hg(2+) and Pb(2+), respectively. This is the first biochemical evidence to prove the above hypothesis that hPLSCR1 is activated in heavy metal poisoning, which leads to bidirectional transbilayer movement of phospholipids.
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Affiliation(s)
- Ashok Kumar Shettihalli
- Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036, India
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18
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Kilpinen L, Tigistu-Sahle F, Oja S, Greco D, Parmar A, Saavalainen P, Nikkilä J, Korhonen M, Lehenkari P, Käkelä R, Laitinen S. Aging bone marrow mesenchymal stromal cells have altered membrane glycerophospholipid composition and functionality. J Lipid Res 2012; 54:622-635. [PMID: 23271708 DOI: 10.1194/jlr.m030650] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Human mesenchymal stem/stromal cells (hMSC) are increasingly used in advanced cellular therapies. The clinical use of hMSCs demands sequential cell expansions. As it is well established that membrane glycerophospholipids (GPL) provide precursors for signaling lipids that modulate cellular functions, we studied the effect of the donor's age and cell doublings on the GPL profile of human bone marrow MSC (hBMSC). The hBMSCs, which were harvested from five young and five old adults, showed clear compositional changes during expansion seen at the level of lipid classes, lipid species, and acyl chains. The ratio of phosphatidylinositol to phosphatidylserine increased toward the late-passage samples. Furthermore, 20:4n-6-containing species of phosphatidylcholine and phosphatidylethanolamine accumulated while the species containing monounsaturated fatty acids (FA) decreased during passaging. Additionally, in the total FA pool of the cells, 20:4n-6 increased, which happened at the expense of n-3 polyunsaturated FAs, especially 22:6n-3. The GPL and FA correlated with the decreased immunosuppressive capacity of hBMSCs during expansion. Our observations were further supported by alterations in the gene expression levels of several enzymes involved in lipid metabolism and immunomodulation. The results show that extensive expansion of hBMSCs harmfully modulates membrane GPLs, affecting lipid signaling and eventually impairing functionality.
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Affiliation(s)
- Lotta Kilpinen
- Advanced Therapies and Product Development, Finnish Red Cross Blood Service, Helsinki, Finland
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Silva-Neta HL, Torrezan E, de Araújo Leite JC, Santi-Gadelha T, Marques-Santos LF. Involvement of ABCB1 and ABCC1 transporters in sea urchin Echinometra lucunter fertilization. Mol Reprod Dev 2012; 79:861-9. [PMID: 23070745 DOI: 10.1002/mrd.22125] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 10/09/2012] [Indexed: 12/11/2022]
Abstract
Fertilization is an ordered sequence of cellular interactions that promotes gamete fusion to form a new individual. Since the pioneering work of Oskar Hertwig conducted on sea urchins, echinoderms have contributed to the understanding of cellular and molecular aspects of the fertilization processes. Studies on sea urchin spermatozoa reported the involvement of a plasma membrane protein that belongs to the ABC proteins superfamily in the acrosome reaction. ABC transporters are expressed in membranes of eukaryotic and prokaryotic cells, and are associated with the transport of several compounds or ions across biomembranes. We aimed to investigate ABCB1 and ABCC1 transporter activity in sea urchin spermatozoa and their involvement in fertilization. Our results indicate that Echinometra lucunter spermatozoa exhibit a low intracellular calcein accumulation (18.5% stained cells); however, the ABC blockers reversin205, verapamil, and MK571 increased dye accumulation (93.0-96.6% stained cells). We also demonstrated that pharmacologically blocking ABCB1 and ABCC1 decreased spermatozoa fertilizing capacity (70% inhibition), and this phenotype was independent of extracellular calcium. These data suggest that functional spermatozoa ABCB1 and ABCC1 transporters are crucial for a successful fertilization. Additional studies must be performed to investigate the involvement of membrane lipid homeostasis in the fertilization process.
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Affiliation(s)
- Helena Lima Silva-Neta
- Departamento de Biologia Molecular, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
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Falconer RJ, Collins BM. Survey of the year 2009: applications of isothermal titration calorimetry. J Mol Recognit 2010; 24:1-16. [DOI: 10.1002/jmr.1073] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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21
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Transbilayer (flip-flop
) lipid motion and lipid scrambling in membranes. FEBS Lett 2009; 584:1779-86. [DOI: 10.1016/j.febslet.2009.12.049] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 12/18/2009] [Indexed: 12/24/2022]
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