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Stroganov S, Harris T, Fellus-Alyagor L, Ben Moyal L, Plitman Mayo R, Golani O, Hirsch D, Ben-Dor S, Brandis A, Mehlman T, Kovo M, Biron-Shental T, Dekel N, Neeman M. The differential regulation of placenta trophoblast bisphosphoglycerate mutase in fetal growth restriction: preclinical study in mice and observational histological study of human placenta. eLife 2024; 13:e82631. [PMID: 38314803 PMCID: PMC10883672 DOI: 10.7554/elife.82631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 01/25/2024] [Indexed: 02/07/2024] Open
Abstract
Background Fetal growth restriction (FGR) is a pregnancy complication in which a newborn fails to achieve its growth potential, increasing the risk of perinatal morbidity and mortality. Chronic maternal gestational hypoxia, as well as placental insufficiency are associated with increased FGR incidence; however, the molecular mechanisms underlying FGR remain unknown. Methods Pregnant mice were subjected to acute or chronic hypoxia (12.5% O2) resulting in reduced fetal weight. Placenta oxygen transport was assessed by blood oxygenation level dependent (BOLD) contrast magnetic resonance imaging (MRI). The placentae were analyzed via immunohistochemistry and in situ hybridization. Human placentae were selected from FGR and matched controls and analyzed by immunohistochemistry (IHC). Maternal and cord sera were analyzed by mass spectrometry. Results We show that murine acute and chronic gestational hypoxia recapitulates FGR phenotype and affects placental structure and morphology. Gestational hypoxia decreased labyrinth area, increased the incidence of red blood cells (RBCs) in the labyrinth while expanding the placental spiral arteries (SpA) diameter. Hypoxic placentae exhibited higher hemoglobin-oxygen affinity compared to the control. Placental abundance of Bisphosphoglycerate mutase (BPGM) was upregulated in the syncytiotrophoblast and spiral artery trophoblast cells (SpA TGCs) in the murine gestational hypoxia groups compared to the control. Hif1α levels were higher in the acute hypoxia group compared to the control. In contrast, human FGR placentae exhibited reduced BPGM levels in the syncytiotrophoblast layer compared to placentae from healthy uncomplicated pregnancies. Levels of 2,3 BPG, the product of BPGM, were lower in cord serum of human FGR placentae compared to control. Polar expression of BPGM was found in both human and mouse placentae syncytiotrophoblast, with higher expression facing the maternal circulation. Moreover, in the murine SpA TGCs expression of BPGM was concentrated exclusively in the apical cell side, in direct proximity to the maternal circulation. Conclusions This study suggests a possible involvement of placental BPGM in maternal-fetal oxygen transfer, and in the pathophysiology of FGR. Funding This work was supported by the Weizmann Krenter Foundation and the Weizmann - Ichilov (Tel Aviv Sourasky Medical Center) Collaborative Grant in Biomedical Research, by the Minerva Foundation, by the ISF KillCorona grant 3777/19.
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Affiliation(s)
- Sima Stroganov
- Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Talia Harris
- Chemical Research Support Weizmann Institute of Science, Rehovot, Israel
| | | | - Lital Ben Moyal
- Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Romina Plitman Mayo
- Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Ofra Golani
- Life Science Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Dana Hirsch
- Life Science Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Shifra Ben-Dor
- Life Science Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Alexander Brandis
- Life Science Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Tevie Mehlman
- Life Science Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Michal Kovo
- OBGYN, Meir Medical Center, Kfar Saba, Israel
- Tel Aviv University, School of Medicine, Tel Aviv, Israel
| | - Tal Biron-Shental
- OBGYN, Meir Medical Center, Kfar Saba, Israel
- Tel Aviv University, School of Medicine, Tel Aviv, Israel
| | - Nava Dekel
- Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Michal Neeman
- Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
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2
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Teofili L, Papacci P, Giannantonio C, Bianchi M, Giovanna Valentini C, Vento G. Allogenic Cord Blood Transfusion in Preterm Infants. Clin Perinatol 2023; 50:881-893. [PMID: 37866854 DOI: 10.1016/j.clp.2023.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Repeated red blood cell (RBC) transfusions in preterm neonates cause the progressive displacement of fetal hemoglobin (HbF) by adult hemoglobin. The ensuing increase of oxygen delivery may result at the cellular level in a dangerous condition of hyperoxia, explaining the association between low-HbF levels and retinopathy of prematurity or bronchopulmonary dysplasia. Transfusing preterm neonates with RBC concentrates obtained from allogeneic umbilical blood is a strategy to increase hemoglobin concentration without depleting the physiologic HbF reservoir. This review summarizes the mechanisms underlying a plausible beneficial impact of this strategy and reports clinical experience gathered so far in this field.
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Affiliation(s)
- Luciana Teofili
- Transfusion Medicine Department, Fondazione Policlinico A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, Largo Gemelli 8, Rome, Italy.
| | - Patrizia Papacci
- Neonatal Intensive Care Unit, Fondazione Policlinico A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, Largo Gemelli 8, Rome, Italy
| | - Carmen Giannantonio
- Neonatal Intensive Care Unit, Fondazione Policlinico A. Gemelli IRCCS, Largo Gemelli 8, Rome, Italy
| | - Maria Bianchi
- Transfusion Medicine Department, Fondazione Policlinico A. Gemelli IRCCS, Largo Gemelli 8, Rome, Italy
| | | | - Giovanni Vento
- Neonatal Intensive Care Unit, Fondazione Policlinico A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, Largo Gemelli 8, Rome, Italy
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3
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Manning JM, Manning LR, Dumoulin A, Padovan JC, Chait B. Embryonic and Fetal Human Hemoglobins: Structures, Oxygen Binding, and Physiological Roles. Subcell Biochem 2020; 94:275-296. [PMID: 32189304 DOI: 10.1007/978-3-030-41769-7_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
During the past two decades, significant advances have been made in our understanding of the human fetal and embryonic hemoglobins made possible by the availability of pure, highly characterized materials and novel methods, e.g., nano gel filtration, to study their properties and to correct some misconceptions. For example, whereas the structures of the human adult, fetal, and embryonic hemoglobins are very similar, it has generally been assumed that functional differences between them are due to primary sequence effects. However, more recent studies indicate that the strengths of the interactions between their subunits are very different leading to changes in their oxygen binding properties compared to adult hemoglobin. Fetal hemoglobin in the oxy conformation is a much stronger tetramer than adult hemoglobin and dissociates to dimers 70-times less than adult hemoglobin. This property may form the basis for its protective effect against malaria. A major source of the increased strength of fetal hemoglobin resides within the A-helix of its gamma subunit as demonstrated in studies with the hybrid hemoglobin Felix and related hybrids. Re-activating fetal hemoglobin synthesis in vivo is currently a major focus of clinical efforts designed to treat sickle cell anemia since it inhibits the aggregation of sickle hemoglobin. The mechanisms for both the increased oxygen affinity of fetal hemoglobin and its decreased response to DPG have been clarified. Acetylated fetal hemoglobin, which makes up 10-20% of total fetal hemoglobin, has a significantly weakened tetramer structure suggesting a similar role for other kinds of protein acetylation. Embryonic hemoglobins have the weakest tetramer and dimer structures. In general, the progressively increasing strength of the subunit interfaces of the hemoglobin family during development from the embryonic to the fetal and ultimately to the adult types correlates with their temporal appearance and disappearance in vivo, i.e., ontogeny.
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Affiliation(s)
- James M Manning
- Department of Biology, Northeastern University, Boston, MA, 02115, USA.
| | - Lois R Manning
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Antoine Dumoulin
- Department of Developability, Pierre Fabre Research Centre, Castres, 81106, France
| | - Julio C Padovan
- Laboratory of Gaseous Ion Chemistry, Rockefeller University, New York, NY, 10065, USA
| | - Brian Chait
- Laboratory of Gaseous Ion Chemistry, Rockefeller University, New York, NY, 10065, USA
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4
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Oliveira JL. Algorithmic evaluation of hereditary erythrocytosis: Pathways and caveats. Int J Lab Hematol 2019; 41 Suppl 1:89-94. [PMID: 31069987 DOI: 10.1111/ijlh.13019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 11/28/2022]
Abstract
Multiple algorithms have been published for the evaluation of hereditary erythrocytosis (HE). Typical entry points begin after excluding the more common acquired conditions through investigations of clinical history and assessment of cardiac, pulmonary, or vascular system disorders. Prior exclusion of JAK2 mutations, particularly the common JAK2 V617F mutation, is indicated in adults but less so in pediatric populations. Key decision trees are based on serum erythropoietin levels and p50 results. Recent data reveal some overlap in clinical presentation and laboratory findings in erythrocytosis. Caveats to consider when using algorithmic approaches are discussed.
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Affiliation(s)
- Jennifer L Oliveira
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
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5
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Chen WR, Chou CC, Wang CC. Phthalides serve as potent modulators to boost fetal hemoglobin induction therapy for β-hemoglobinopathies. Blood Adv 2019; 3:1493-1498. [PMID: 31072835 PMCID: PMC6517670 DOI: 10.1182/bloodadvances.2019031120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/19/2019] [Indexed: 01/22/2023] Open
Abstract
Fetal hemoglobin (HbF) induction therapy has become the most promising strategy for treating β-hemoglobinopathies, including sickle-cell diseases and β-thalassemia. However, subtle but critical structural difference exists between HbF and normal adult hemoglobin (HbA), which inevitably leads to reduced binding of the endogenous modulator 2,3-bisphosphoglycerate (2,3-BPG) to HbF and thus increased oxygen affinity and decreased oxygen transport efficiency of HbF. We combined the oxygen equilibrium experiments, resonance Raman (RR) spectroscopy, and molecular docking modeling, and we discuss 2 phthalides, z-butylidenephthalide and z-ligustilide, that can effectively lower the oxygen affinity of HbF. They adjust it to a level closer to that of HbA and make it a more satisfactory oxygen carrier for adults. From the oxygen equilibrium curve measurements, we show that the 2 phthalides are more effective than 2,3-BPG for modulating HbF. The RR spectra show that phthalides allosterically stabilize the oxygenated HbF in the low oxygen affinity conformation, and the molecular docking modeling reveals that the 2 chosen phthalides interact with HbF via the cleft around the γ1/γ2 interface with a binding strength ∼1.6 times stronger than that of 2,3-BPG. We discuss the implications of z-butylidenephthalide and z-ligustilide in boosting the efficacy of HbF induction therapy to mitigate the clinical severities of β-hemoglobinopathies.
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Affiliation(s)
- Wei-Ren Chen
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan, Republic of China
| | - Chia-Cheng Chou
- National Center for High-performance Computing, National Applied Research Laboratories, Hsinchu, Taiwan, Republic of China; and
| | - Chia C Wang
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan, Republic of China
- Aerosol Science Research Center, National Sun Yat-sen University, Kaohsiung, Taiwan, Republic of China
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6
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Kettisen K, Strader MB, Wood F, Alayash AI, Bülow L. Site-directed mutagenesis of cysteine residues alters oxidative stability of fetal hemoglobin. Redox Biol 2018; 19:218-225. [PMID: 30193183 PMCID: PMC6126208 DOI: 10.1016/j.redox.2018.08.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/18/2018] [Accepted: 08/20/2018] [Indexed: 01/06/2023] Open
Abstract
Redox active cysteine residues including βCys93 are part of hemoglobin's "oxidation hotspot". Irreversible oxidation of βCys93 ultimately leads to the collapse of the hemoglobin structure and release of heme. Human fetal hemoglobin (HbF), similarly to the adult hemoglobin (HbA), carries redox active γCys93 in the vicinity of the heme pocket. Site-directed mutagenesis has been used in this study to examine the impact of removal and/or addition of cysteine residues in HbF. The redox activities of the recombinant mutants were examined by determining the spontaneous autoxidation rate, the hydrogen peroxide induced ferric to ferryl oxidation rate, and irreversible oxidation of cysteine by quantitative mass spectrometry. We found that substitution of γCys93Ala resulted in oxidative instability characterized by increased oxidation rates. Moreover, the addition of a cysteine residue at α19 on the exposed surface of the α-chain altered the regular electron transfer pathway within the protein by forming an alternative oxidative site. This may also create an accessible site for di-sulfide bonding between Hb subunits. Engineering of cysteine residues at suitable locations may be useful as a tool for managing oxidation in a protein, and for Hb, a way to stave off oxidation reactions resulting in a protein structural collapse.
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Affiliation(s)
- Karin Kettisen
- Pure and Applied Biochemistry, Department of Chemistry, Lund University, Lund 22362, Sweden
| | - Michael Brad Strader
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Francine Wood
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Abdu I Alayash
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Leif Bülow
- Pure and Applied Biochemistry, Department of Chemistry, Lund University, Lund 22362, Sweden.
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7
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Banaei A, Ghourchian H, Rahimi P, Moosavi Movahedi AA, Amjadi R. Different electrochemical behavior of adult and fetal hemoglobin at ionic liquid-carbon nanotube nanocomposite. JOURNAL OF THE IRANIAN CHEMICAL SOCIETY 2014. [DOI: 10.1007/s13738-014-0527-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Lin Z, Fisher JW, Wang R, Ross MK, Filipov NM. Estimation of placental and lactational transfer and tissue distribution of atrazine and its main metabolites in rodent dams, fetuses, and neonates with physiologically based pharmacokinetic modeling. Toxicol Appl Pharmacol 2013; 273:140-58. [DOI: 10.1016/j.taap.2013.08.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 08/07/2013] [Accepted: 08/10/2013] [Indexed: 11/27/2022]
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9
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Bertrand R. Nitric oxide-mediated suppression of 2,3-bisphosphoglycerate synthesis: Therapeutic relevance for environmental hypoxia and sickle cell disease. Med Hypotheses 2012; 79:315-8. [DOI: 10.1016/j.mehy.2012.05.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 05/10/2012] [Indexed: 11/26/2022]
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10
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Novozhilov AV, Katyukhin LN, Feizullaev BA. Dynamics of hematologic parameters and of the erythrocyte deformability index at the juvenal period of rats and guinea pigs. J EVOL BIOCHEM PHYS+ 2012. [DOI: 10.1134/s0022093012010057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Jorge SEDC, Petruk AA, Kimura EM, Oliveira DM, Caire L, Suemasu CN, Silveira PAA, Albuquerque DM, Costa FF, Skaf MS, Martínez L, Sonati MDF. Hb S-São Paulo: a new sickling hemoglobin with stable polymers and decreased oxygen affinity. Arch Biochem Biophys 2012; 519:23-31. [PMID: 22244832 DOI: 10.1016/j.abb.2012.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 12/22/2011] [Accepted: 01/01/2012] [Indexed: 01/19/2023]
Abstract
Hb S-São Paulo (SP) [HBB:c.20A>T p.Glu6Val; c.196A>G p.Lys65Glu] is a new double-mutant hemoglobin that was found in heterozygosis in an 18-month-old Brazilian male with moderate anemia. It behaves like Hb S in acid electrophoresis, isoelectric focusing and solubility testing but shows different behavior in alkaline electrophoresis, cation-exchange HPLC and RP-HPLC. The variant is slightly unstable, showed reduced oxygen affinity and also appeared to form polymers more stable than the Hb S. Molecular dynamics simulation suggests that the polymerization is favored by interfacial electrostatic interactions. This provides a plausible explanation for some of the reported experimental observations.
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Affiliation(s)
- Susan E D C Jorge
- Department of Clinical Pathology, School of Medical Sciences, State University of Campinas, Campinas, State of São Paulo, Brazil
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12
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Gu M, Pritlove DC, Boyd CAR, Vatish M. Placental expression of 2,3 bisphosphoglycerate mutase in IGF-II knock out mouse: correlation of circulating maternal 2,3 bisphosphoglycerate and fetal growth. Placenta 2009; 30:919-22. [PMID: 19733906 DOI: 10.1016/j.placenta.2009.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 08/14/2009] [Accepted: 08/18/2009] [Indexed: 11/16/2022]
Abstract
Bisphosphoglycerate mutase (BPGM) catalyses the formation of 2,3 bisphosphoglycerate (BPG) a ligand of haemoglobin. BPG facilitates liberation of oxygen from haemoglobin at low oxygen tension enabling efficient delivery of oxygen to tissues. We describe expression of BPGM in mouse labyrinthine trophoblasts, located at the maternal-placental interface. Expression is lower in placentae of igf2(+/-) knockout mice, a widely used model of growth restriction, compared to wild type placentae. Circulating maternal BPG increased throughout gestation but this increase was less in wt mothers carrying igf2(+/-) pups than in those carrying exclusively wt pups. This reduction was observed well before term and may contribute to the low birth weight of igf2(+/-) pups. Strikingly, we also measured reductions of fetal and placental weight in wt littermates of igf2(+/-) pups compared to pups developing in an exclusively wt environment. These data suggest that placental expression of BPGM can influence maternal BPG concentrations and supports a hypothesis under which BPG synthesized in the placenta may act on maternal haemoglobin to enhance delivery of oxygen to the developing fetus.
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Affiliation(s)
- M Gu
- Clinical Sciences Research Institute, University of Warwick Medical School, Clifford Bridge Road, Coventry, UK
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Higashimoto T, Urbinati F, Perumbeti A, Jiang G, Zarzuela A, Chang LJ, Kohn DB, Malik P. The woodchuck hepatitis virus post-transcriptional regulatory element reduces readthrough transcription from retroviral vectors. Gene Ther 2007; 14:1298-304. [PMID: 17597793 DOI: 10.1038/sj.gt.3302979] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The woodchuck hepatitis virus post-transcriptional regulatory element (WPRE) increases transgene expression from a variety of viral vectors, although the precise mechanism is not known. WPRE is most effective when placed downstream of the transgene, proximal to the polyadenylation signal. We hypothesized that WPRE likely reduces viral mRNA readthrough transcription by improving transcript termination, which in turn would increase viral titers and expression. Using a Cre-lox-mediated plasmid-based assay, we found significant readthrough transcription from gamma-retroviral vector (RV) long terminal repeat (wt RV-LTR) and RV LTR with a self-inactivating deletion (SIN RV-LTR). WPRE, when placed upstream of the RV LTRs, significantly reduced readthrough transcription. Readthrough, present at much lower levels with the SIN HIV-1 LV-LTR, was also reduced with WPRE. When placed in RV vectors, WPRE increased total RV genomic mRNA; and increased viral titers from transiently transfected 293T cells and stable PG13 producer cells by 7- to 15-fold. The mechanism of increased titers and expression was not due to increased nuclear mRNA export, increased rate of viral transcription or a significant increase in viral mRNA half-life. Our results showed that WPRE improved vector genomic transcript termination to increase titers and expression from RVs.
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Affiliation(s)
- T Higashimoto
- Division of Hematology-Oncology, Department of Pediatrics and Pathology, Keck School of Medicine University of Southern California, Childrens Hospital Los Angeles, Los Angeles, CA, USA
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14
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Pomponi M, Bertonati C, Patamia M, Marta M, Derocher AE, Lydersen C, Kovacs KM, Wiig O, Bårdgard AJ. Polar bear hemoglobin and human Hb A0: same 2,3-diphosphoglycerate binding site but asymmetry of the binding? Hemoglobin 2002; 26:363-71. [PMID: 12484631 DOI: 10.1081/hem-120016373] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Polar bear (Ursus maritimus) hemoglobin (Hb) shows a low response to 2,3-diphosphoglycerate (2,3-DPG), compared to human Hb A0, even though these proteins have the same 2,3-DPG-binding site. In addition, polar bear Hb shows a high response to chloride and an alkaline Bohr effect (deltalog P50/deltapH) that is significantly greater than that of human Hb A0. The difference in sequence Pro (Hb A0)-->Gly (polar bear Hb) at position A2 in the A helix seems to be critical for reduced binding of 2,3-DPG. Our results also show that the A2 position may influence not only the flexibility of the A helix, but that differences in flexibility of the first turn of the A helix may affect the unloading of oxygen for the intrinsic ligand affinities of the alpha and beta chains. However, preferential binding to either chain can only take place if there is appreciable asymmetric binding of the phosphoric effector. Regarding this point, 31P NMR data suggest a loss of symmetry of the 2,3-DPG-binding site in the deoxyHb-2,3-DPG complex.
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Affiliation(s)
- Massimo Pomponi
- Istituto di Biochimica, Università Cattolica Sacro Cuore, Facoltà di Medicina A. Gemelli Largo F. Vito 1, 00168 Roma, Italia.
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15
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Adachi K, Zhao Y, Yamaguchi T, Surrey S. Assembly of gamma- with alpha-globin chains to form human fetal hemoglobin in vitro and in vivo. J Biol Chem 2000; 275:12424-9. [PMID: 10777526 DOI: 10.1074/jbc.c000137200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Soluble gamma-globin chains were expressed in bacteria and purified to assess the mechanism of gamma- and alpha-chain assembly to form Hb F. Formation of Hb F in vitro following incubation of equimolar mixtures of gamma and alpha chains was about 4 x 10(5)-fold slower than assembly of alpha and beta chains to form Hb A in vitro. Results of assembly for gamma(116Ile-->His) and gamma(112Thr-->Asp) chains with alpha chains were similar to that of beta chains, whereas assembly of gamma(112Thr-->Cys) and alpha chains was similar to wild type gamma chains, indicating that amino acid differences at alpha1beta1 and alpha1gamma1 interaction sites between gamma116 Ile and beta116 His are responsible for the different assembly rates in vitro in the formation of Hb F and Hb A. Homoassembly in vitro of individual gamma chains as assessed by size-exclusion chromatography shows that gamma and gamma(112Thr-->Cys) chains form stable dimers like alphabeta and alphagamma that do not dissociate readily into monomers like beta chains. In contrast, gamma(116Ile-->His) chains form monomers and dimers upon dilution. These results are consistent with the slower assembly rate in vitro of gamma and gamma(112Thr-->Cys) with alpha chains, whereas the faster rate of assembly of gamma(116Ile-->His) and gamma(112Thr-->Asp) chains with alpha chains, like beta chains, may be caused by dissociation to monomers. These results suggest that dissociation of gamma(2) dimers to monomers limits formation of Hb F in vitro. However, yields of soluble Hb F expressed in bacteria were similar to Hb A, and no unassembled alpha and gamma chains were detected. These results indicate that gamma chains assemble in vivo with alpha chains prior to forming stable gamma(2) dimers, possibly binding to alpha chains as partially folded nascent gamma-globin chains prior to release from polyribosomes.
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Affiliation(s)
- K Adachi
- The Children's Hospital of Philadelphia, Division of Hematology and University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
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16
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Papassotiriou I, Kister J, Griffon N, Stamoulakatou A, Abraham DJ, Marden MC, Loukopoulos D, Poyart C. Modulating the oxygen affinity of human fetal haemoglobin with synthetic allosteric modulators. Br J Haematol 1998; 102:1165-71. [PMID: 9753039 DOI: 10.1046/j.1365-2141.1998.00886.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Improving the delivery of oxygen to the tissues by decreasing the oxygen affinity of haemoglobin has been a major aim of several laboratories over recent years because this may reduce the consequences of anaemia and/or improve tissue oxygenation in cases of decreased blood perfusion. Within the same context, lowering the oxygen affinity may prove valuable in the application of native or recombinant haemoglobin solutions as a blood substitute. The shift of the oxygen equilibrium curve to the right is obtained by various modulators. Among them, the bezafibrate derivatives are considered as a most interesting group. These principles are of the utmost importance in thalassaemia and other haemoglobinopathies where the beneficial effects of the compensatory synthesis of fetal haemoglobin are diminished by the increased oxygen affinity of this pigment. In this paper we present the results of a study initiated to determine whether a potent oxygen affinity modifier, RSR-4, could satisfactorily decrease the oxygen affinity of fetal haemoglobin, thus improving tissue oxygenation. The experiments were carried out on whole blood and on purified haemoglobin solutions and showed that the effector markedly decreased the oxygen affinity of HbF (from 18.7 to 3.73 mmHg in whole blood). At the same time the cooperativity index (n50) and the oxygen saturation levels remained within normal limits under the conditions of the main experiment. These observations have important implications for the potential application of oxygen affinity modifiers in vivo.
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Affiliation(s)
- I Papassotiriou
- Haematology Laboratory, Aghia Sophia Children's Hospital, Athens, Greece
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18
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Abstract
AbstractStudies on assembly in vitro of α-globin chains with recombinant β16 Gly→Asp, β95 Lys→Glu, β120 Lys→Glu and β16 Gly→Asp, 120 Lys→Glu human β-globin chain variants in addition to human βA- and βS-globin chains were performed to evaluate effects of increased anionic charge in the β chain on hemoglobin assembly using soluble recombinant β-globin chains expressed in bacteria. A β112 Cys→Asp change was also engineered to monitor effects on assembly of increased negative charge at α1β1 interaction sites. Order of tetramer formation in vitro under limiting α-globin chain conditions showed Hb βG16D, K120E = Hb βK120E = Hb βK95E > Hb βG16D > Hb A > Hb S >>> Hb βC112D. In addition, β112 Cys→Asp chains exist as monomers rather than β4tetramers in the absence of α chains, and the β chain in Hb βC112D tetramers was readily exchanged by addition of βs. These results suggest that affinity between α and β chains is promoted by negatively-charged β chains up to a maximum of two additional net negative charges and is independent of location on the surface except at the α1β1 interaction site. In addition, our findings show that β112 Cys on the G helix is critical for facilitating formation of stable αβ dimers, which then form functional hemoglobin tetramers, and that β112 Cys→Asp inhibits formation of stable α1β1 and β1β2 interactions in α2β2 and β4 tetramers, respectively.
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