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Ababio GK, Ekem I, Acquaye J, Oppong SY, Amoah AGB, Brandful J, Quaye IK. Detection of Transversions and Transitions in HBG2 Cis-Elements Associated with Sickle Cell Allele in Ghanaians. Biochem Genet 2024; 62:666-674. [PMID: 37395849 DOI: 10.1007/s10528-023-10438-1] [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] [Received: 02/22/2023] [Accepted: 06/20/2023] [Indexed: 07/04/2023]
Abstract
Short tandem repeats located 5' prime to the β-globin gene, have been observed to be in linkage disequilibrium with the HbS allele, and thought to affect the severity of sickle cell disease. Here, we report on new mutants within the HBG2 region that may impact sickle cell disease. To determine the cis-acting elements microsatellites, indels and single nucleotide polymorphisms (SNPs), within the HBG2 region by sequencing, in subjects with sickle cell disease. The case-control study was located at the Center for Clinical Genetics, Sickle cell unit, Korle-Bu Teaching Hospital. A questionnaire was used for demographic data and clinical information. Hematological profile (red blood cell, white blood cell, platelet, hemoglobin and mean corpuscular volume) were assessed in 83 subjects. A set of 45 samples comprising amplified DNA on the HBG2 gene from HbSS (22), HbSC (17) and 6 controls (HbAA) were sequenced. Differences in the microsatellite region between sickle cell disease (SCD) (HbSS and HbSC) genotypes and control subjects were identified by counting and assessed by Chi-square analysis. Red blood cells, hematocrit, platelets, white blood cells and hemoglobin indices differed in genotypic groups. HbSS subjects were affirmed to have severer hemolytic anemia than HbSC subjects. Two indels (T1824 and C905) were seen in both SS and SC genotypes. Two peculiar SNPs: G:T1860 (transition) and A:G1872 transversions were found within the HBG2 gene that were significantly associated with the HbSS genotype (Fisher's exact test, p = 0.006) and HbS allele respectively (Fisher's exact test, p = 0.006). Cis-acting elements in HbSS and HbSC were different and may contribute to the phenotype seen in the disease state.
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Affiliation(s)
- G K Ababio
- Department of Medical Biochemistry, University of Ghana Medical School, Accra, Ghana.
| | - I Ekem
- Department of Hematology, University of Cape Coast School of Medicine, Cape Coast, Ghana
| | - J Acquaye
- Department of Hematology, University of Ghana Medical School, Accra, Ghana
| | - S Y Oppong
- Department of Medical Biochemistry, University of Ghana Medical School, Accra, Ghana
- Department of Chemical Pathology, University of Ghana Medical School, Accra, Ghana
| | - A G B Amoah
- Department of Medicine, University of Ghana Medical School, Accra, Ghana
| | - J Brandful
- Department of Virology, Noguchi Memorial Institute of Medical Research, Legon, Ghana
| | - I K Quaye
- Department of Biochemistry, University of Namibia Medical School, Windhoek, Namibia.
- Regent University College of Science and Technology, Dansoman, Accra, Ghana.
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Abraham AA, Tisdale JF. Gene therapy for sickle cell disease: moving from the bench to the bedside. Blood 2021; 138:932-941. [PMID: 34232993 PMCID: PMC9069474 DOI: 10.1182/blood.2019003776] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/21/2020] [Indexed: 11/20/2022] Open
Abstract
Gene therapy as a potential cure for sickle cell disease (SCD) has long been pursued, given that this hemoglobin (Hb) disorder results from a single point mutation. Advances in genomic sequencing have increased the understanding of Hb regulation, and discoveries of molecular tools for genome modification of hematopoietic stem cells have made gene therapy for SCD possible. Gene-addition strategies using gene transfer vectors have been optimized over the past few decades to increase expression of normal or antisickling globins as strategies to ameliorate SCD. Many hurdles had to be addressed before clinical translation, including collecting sufficient stem cells for gene modification, increasing expression of transferred genes to a therapeutic level, and conditioning patients in a safe manner that enabled adequate engraftment of gene-modified cells. The discovery of genome editors that make precise modifications has further advanced the safety and efficacy of gene therapy, and a rapid movement to clinical trial has undoubtedly been supported by lessons learned from optimizing gene-addition strategies. Current gene therapies being tested in clinical trial require significant infrastructure and expertise, given that cells must be harvested from and chemotherapy administered to patients who often have significant organ dysfunction and that gene-modification takes place ex vivo in specialized facilities. For these therapies to realize their full potential, they would have to be portable, safe, and efficient, to make an in vivo-based approach attractive. In addition, adequate resources for SCD screening and access to standardized care are critically important for gene therapy to be a viable treatment option for SCD.
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Affiliation(s)
- Allistair A Abraham
- Center for Cancer and Immunology Research and
- Division of Blood and Marrow Transplantation, Children's National Hospital, Washington, DC
- Department of Pediatrics, George Washington University School of Medicine and Health Sciences, Washington, DC; and
| | - John F Tisdale
- Cellular and Molecular Therapeutics Branch, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Bethesda, MD
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Alayash AI. βCysteine 93 in human hemoglobin: a gateway to oxidative stability in health and disease. J Transl Med 2021; 101:4-11. [PMID: 32980855 DOI: 10.1038/s41374-020-00492-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/11/2020] [Indexed: 12/14/2022] Open
Abstract
βcysteine 93 residue plays a key role in oxygen (O2)-linked conformational changes in the hemoglobin (Hb) molecule. This solvent accessible residue is also a target for binding of thiol reagents that can remotely alter O2 affinity, cooperativity, and Hb's sensitivity to changes in pH. In recent years, βCys93 was assigned a new physiological role in the transport of nitric oxide (NO) through a process of S-nitrosylation as red blood cells (RBCs) travel from lungs to tissues. βCys93 is readily and irreversibly oxidized in the presence of a mild oxidant to cysteic acid, which causes destabilization of Hb resulting in improper protein folding and the loss of heme. Under these oxidative conditions, ferryl heme (HbFe4+), a higher oxidation state of Hb is formed together with its protein radical (.HbFe4+). This radical migrates to βCys93 and interacts with other "hotspot" amino acids that are highly susceptible to oxidative modifications. Oxidized βCys93 may therefore be used as a biomarker of oxidative stress, reflecting the deterioration of Hb within RBCs intended for transfusion or RBCs from patients with hemoglobinopathies. Site specific mutation of a redox active amino acid(s) to reduce the ferryl heme or direct chemical modifications that can shield βCys93 have been proposed to improve oxidative resistance of Hb and may offer a protective therapeutic strategy.
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Affiliation(s)
- Abdu I Alayash
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research Food and Drug Administration (FDA), Silver Spring, MD, 20993, USA.
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The Providence Mutation (βK82D) in Human Hemoglobin Substantially Reduces βCysteine 93 Oxidation and Oxidative Stress in Endothelial Cells. Int J Mol Sci 2020; 21:ijms21249453. [PMID: 33322551 PMCID: PMC7763657 DOI: 10.3390/ijms21249453] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/03/2020] [Accepted: 12/09/2020] [Indexed: 01/17/2023] Open
Abstract
The highly toxic oxidative transformation of hemoglobin (Hb) to the ferryl state (HbFe4+) is known to occur in both in vitro and in vivo settings. We recently constructed oxidatively stable human Hbs, based on the Hb Providence (βK82D) mutation in sickle cell Hb (βE6V/βK82D) and in a recombinant crosslinked Hb (rHb0.1/βK82D). Using High Resolution Accurate Mass (HRAM) mass spectrometry, we first quantified the degree of irreversible oxidation of βCys93 in these proteins, induced by hydrogen peroxide (H2O2), and compared it to their respective controls (HbA and HbS). Both Hbs containing the βK82D mutation showed considerably less cysteic acid formation, a byproduct of cysteine irreversible oxidation. Next, we performed a novel study aimed at exploring the impact of introducing βK82D containing Hbs on vascular endothelial redox homeostasis and energy metabolism. Incubation of the mutants carrying βK82D with endothelial cells resulted in altered bioenergetic function, by improving basal cellular glycolysis and glycolytic capacity. Treatment of cells with Hb variants containing βK82D resulted in lower heme oxygenase-1 and ferritin expressions, compared to native Hbs. We conclude that the presence of βK82D confers oxidative stability to Hb and adds significant resistance to oxidative toxicity. Therefore, we propose that βK82D is a potential gene-editing target in the treatment of sickle cell disease and in the design of safe and effective oxygen therapeutics.
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Hicks W, Meng F, Kassa T, Alayash AI. Effects of α subunit substitutions on the oxidation of βCys93 and the stability of sickle cell hemoglobin. Redox Rep 2020; 25:95-103. [PMID: 33059548 PMCID: PMC7594797 DOI: 10.1080/13510002.2020.1834250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
The β subunit substitutions, F41Y and K82D, in sickle cell hemoglobin (Hb) (βE6 V) provides significant resistance to oxidative stress by shielding βCys93 from the oxidizing ferryl heme. We evaluated the oxidative resistance of βCys93 to hydrogen peroxide (H2O2) in α subunit mutations in βE6 V (at both the putative and lateral contact regions) that included (1) αH20Q/βE6 V; (2) αH50Q/βE6 V; (3) αH20Q/H50Q/βE6 V; (4) αH20R/βE6 V; and (5) αH20R/H50Q/βE6 V. Estimation by mass spectrometry of irreversible oxidation of βCys93 to cysteic acid (CA) was unchanged or moderately increased in the single mutants harboring a H20Q or H50Q substitution when compared to control (βE6 V). The introduction of Arg (R) singularly or in combination with Q enhanced the pseudoperoxidative cycle by slightly decreasing the ferryl in favor of ferrous and ferric species after treatment with H2O2. Higher rates for heme loss from the ferric forms of the Q species to the receptor high affinity recombinant apomyglobin were observed in contrast to the R mutants and control. Because of their improved solubility, a combination of Q and R substitutions together with mutations carrying redox active variants (F41Y/K82D) may provide dual antioxidant and antisickling targets in the design of gene therapy-based candidates.
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Affiliation(s)
- Wayne Hicks
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration (FDA), Silver Spring, Maryland, USA
| | - Fantao Meng
- Hemoglobin Oxygen Therapeutics, Souderton, Pennsylvania, USA
| | - Tigist Kassa
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration (FDA), Silver Spring, Maryland, USA
| | - Abdu I Alayash
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration (FDA), Silver Spring, Maryland, USA
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Ding Y, Ball KA, Webb KJ, Gao Y, D'Alessandro A, Old WM, Stowell MHB, Ding X. On-Chip Acousto Thermal Shift Assay for Rapid and Sensitive Assessment of Protein Thermodynamic Stability. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2003506. [PMID: 32893496 DOI: 10.1002/smll.202003506] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/12/2020] [Indexed: 06/11/2023]
Abstract
Thermal shift assays (TSAs) have been extensively used to study thermodynamics of proteins and provide an efficient means to assess protein-ligand binding or protein-protein interactions. However, existing TSAs have limitations, such as being time consuming, labor intensive, or having low sensitivity. Herein, an acousto thermal shift assay (ATSA), the first ultrasound enabled TSA, is reported for real-time analysis of protein thermodynamic stability. It capitalizes the coupling of unique acoustic mechanisms to achieve protein unfolding, concentration, and measurement on a single microfluidic chip within minutes. Compared to conventional TSA methods, the ATSA technique enables ultrafast (at least 30 times faster), highly sensitive (7-34 folds higher), and label-free monitoring of protein-ligand interactions and protein stability. ATSA paves new avenues for protein analysis in biology, medicine, and fast diagnosis.
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Affiliation(s)
- Yonghui Ding
- Paul M. Rady Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, USA
| | - Kerri A Ball
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Kristofor J Webb
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Yu Gao
- Paul M. Rady Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, USA
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - William M Old
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Michael H B Stowell
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Xiaoyun Ding
- Paul M. Rady Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, USA
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Habibi S, Lee HY, Moncada-Hernandez H, Gooding J, Minerick AR. Impacts of low concentration surfactant on red blood cell dielectrophoretic responses. BIOMICROFLUIDICS 2019; 13:054101. [PMID: 31531153 PMCID: PMC6746619 DOI: 10.1063/1.5113735] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/02/2019] [Indexed: 06/10/2023]
Abstract
Cell dielectrophoretic responses have been extensively studied for biomarker expression, blood typing, sepsis, circulating tumor cell separations, and others. Surfactants are often added to the analytical buffer in electrokinetic cellular microfluidic systems to lower surface/interfacial tensions. In nonelectrokinetic systems, surfactants influence cell size, shape, and agglomeration; this has not been systematically documented in electrokinetic systems. In the present work, the impacts of the Triton X-100 surfactant on human red blood cells (RBCs) were explored via ultraviolet-visible spectroscopy (UV-Vis) and dielectrophoresis (DEP) to compare nonelectrokinetic and electrokinetic responses, respectively. The UV-Vis spectra of Triton X-100 treated RBCs were dramatically different from that of native RBCs. DEP responses of RBCs were compared to RBCs treated with low concentrations of Triton X-100 (0.07-0.17 mM) to ascertain surfactant effects on dielectric properties. A star-shaped electrode design was used to quantify RBC dielectric properties by fitting a single-shell oblate cell model to experimentally-derived DEP spectra. The presence of 0.07 and 0.11 mM of Triton X-100 shifted the RBC's DEP spectra yielding lower crossover frequencies ( f C O ) . The single-shell oblate model revealed that cell radius and membrane permittivity are the dominant influencers of DEP spectral shifts. The trends observed were similar for 0.11 mM and 0.07 mM Triton X-100 treated cells. However, a further increase of Triton X-100 to 0.17 mM caused cells to only exhibit negative DEP. The magnitude of the DEP force increased with Triton X-100 concentration. This work indicates that dynamic surfactant interactions with cell membranes alter cell dielectric responses and properties.
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Kassa T, Wood F, Strader MB, Alayash AI. Antisickling Drugs Targeting βCys93 Reduce Iron Oxidation and Oxidative Changes in Sickle Cell Hemoglobin. Front Physiol 2019; 10:931. [PMID: 31396101 PMCID: PMC6668304 DOI: 10.3389/fphys.2019.00931] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/09/2019] [Indexed: 01/05/2023] Open
Abstract
Sickle cell disease is a genetic blood disorder caused by a single point mutation in the β globin gene where glutamic acid is replaced by valine at the sixth position of the β chain of hemoglobin (Hb). At low oxygen tension, the polymerization of deoxyHbS into fibers occurs in red blood cells (RBCs) leading to an impaired blood vessel transit. Sickle cell hemoglobin (HbS), when oxidized with hydrogen peroxide (H2O2), stays longer in a highly oxidizing ferryl (Fe4+) form causing irreversible oxidation of βCys93 to a destabilizing cysteic acid. We have previously reported that an antisickling drug can be designed to bind specifically to βCys93 and effectively protect against its irreversible oxidation by H2O2. Here, we report oxygen dissociation, oxidation, and polymerization kinetic reactions for four antisickling drugs (under different preclinical/clinical developmental stages) that either site-specifically target βCys93 or other sites on the HbS molecule. Molecules that specifically bind to or modify βCys93, such as 4,4′-di(1,2,3-triazolyl) disulfide (TD-3) and hydroxyurea (HU) were contrasted with molecules that target other sites on Hb including 5-hydroxymethyl-2-furfural (5-HMF) and L-glutamine. All reagents induced a left shift in the oxygen dissociation curve (ODC) except L-glutamine. In the presence of H2O2 (2.5:1, H2O2:heme), both TD-3 and HU reduced the ferryl heme by 22 and 37%, respectively, which corresponded to a 3- to 2-fold reduction in the levels of βCys93 oxidation as verified by mass spectrometry. Increases in the delay times prior to polymerization of HbS under hypoxia were in the following order: TD-3 > HU > 5-HMF = L-glutamine. Designing antisickling agents that can specifically target βCys93 may provide a dual antioxidant and antisickling therapeutic benefits in treating this disease.
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Affiliation(s)
- Tigist Kassa
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD, United States
| | - Francine Wood
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD, United States
| | - Michael Brad Strader
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD, United States
| | - Abdu I Alayash
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD, United States
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