scholarly journals Investigating Zeta Globin Gene Expression to Develop a Potential Therapy for Alpha Thalassemia Major

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 3-4
Author(s):  
Georgia L. Gregory ◽  
Beeke Wienert ◽  
Marisa Schwab ◽  
Billie Rachael Lianoglou ◽  
Roger P. Hollis ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Globin Gene ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Beta Globin ◽  
Wild Type ◽  
Advisory Committees ◽  
Alpha Thalassemia ◽  
Alpha Globin ◽  
Zeta Globin Gene

Introduction: Alpha globin mutations are very common worldwide, and the severity of resulting anemia depends on the number and type of mutated alleles. While the 4 gene mutation (alpha thalassemia major, ATM) was previously deemed fatal except in rare cases, emerging evidence indicates that survival to birth and good postnatal outcomes are possible with in utero transfusions. We hypothesized that the embryonic zeta globin gene, which is expressed early in gestation prior to alpha globin, may compensate for the lack of alpha globin and that induction of zeta globin after it has naturally been silenced may become a new therapy for patients with ATM. Methods: We evaluated mutations in the UCSF international registry of patients with ATM to understand factors related to patient survival with and without in utero transfusions. We then engineered Human Umbilical Cord Derived Erythroid Progenitor Cells (HUDEP-2 cells) carrying the common SEA alpha globin deletion, in which zeta globin expression is preserved (H-SEA), as well as those on which the zeta globin genes were deleted (HBZ-/-) using CRISPR-Cas9. We evaluated the expression of alpha and zeta globins using qPCR, Western blot, and flow cytometry. We generated lentiviral vectors expressing zeta globin under the control of beta-globin promoters to examine changes in both zeta and alpha globin in a dynamic way. Results: None of the registry patients who survived to birth spontaneously (n=11) had a mutation that involves a concomitant deletion in zeta globin (such as the -FIL, -THAI, or -MEDII mutation), while alpha globin mutations extending into the zeta globin gene were found in 14 of 37 (38%) patients who were diagnosed prenatally, suggesting that the presence of zeta globin may play a role in the ability to survive to birth without fetal therapy. Interestingly, we found that H-SEA clones express higher levels of zeta globin than WT cells, as illustrated by quantitative real-time PCR (Fig 1A), Western blot (Fig 1B) and flow cytometry (Fig 1C). These cells also developed beta globin dimers due to excess unpaired beta-globin chains, as demonstrated by Western blotting with and without reducing agents, indicating that they are an appropriate cell model for ATM. We next generated HUDEP-2 clones lacking zeta globin (HBZ KO) and transduced these clones with lentiviral vectors expressing high levels of zeta globin (lenti-zeta) (Fig 1D). Western blotting revealed that increasing the levels of zeta globin in these cells resulted in decreased expression of alpha globin, suggesting reciprocal control between these genes (Fig 1E). Most importantly, we saw a reduction in toxic beta-globin dimers in H-SEA cells expressing high levels of zeta-globin after transduction with lenti-zeta, suggesting that zeta globin could functionally replace the missing alpha-globin (Fig 1 F,G). To understand transcriptomic differences in H-SEA cells that may result in increased zeta globin expression, we performed bulk RNA sequencing of wild type and H-SEA clones. We confirmed that zeta expression is significantly upregulated in H-SEA compared to wild type (log2 fold change of 4.25, p=2.24E-38). Pathway analysis of differentially expressed genes is ongoing. Conclusions: Our international patient registry suggests that expression of zeta globin may play a role in the spontaneous survival to birth in a subset of patients. Zeta globin expression is increased in the setting of H-SEA cells in vitro, and restoration of zeta expression by lentivirus results in a reduction of toxic beta globin dimers in these ATM cells. Furthermore, expressing zeta globin at high levels in H-WT cells decreased alpha globin expression, suggesting a reciprocal regulation of these two genes. This concept is similar to the relationship between fetal gamma and adult beta globins which has been exploited for therapeutic editing approaches in patients with beta-thalassemia. At this point, the natural repressor of zeta globin is not yet known, but our data suggests that a strategy of upregulating zeta globin could potentially be developed to mimic the ongoing trials of using the BCL11A repressor to induce gamma globin in patients with beta thalassemia and sickle cell disease. Disclosures Wienert: Integral Medicines: Current Employment. Kohn:Allogene Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Consultancy, Patents & Royalties, Research Funding. MacKenzie:Acrigen: Membership on an entity's Board of Directors or advisory committees; Ultragenyx: Research Funding.

scholarly journals Molecular analysis of beta zero-thalassemia intermedia in Sardinia

Blood ◽  
1989 ◽  
Vol 74 (2) ◽  
pp. 823-827 ◽  
Author(s):  
R Galanello ◽  
E Dessi ◽  
MA Melis ◽  
M Addis ◽  
MA Sanna ◽  
...  
Keyword(s):  
Nonsense Mutation ◽  
Frameshift Mutation ◽  
Globin Gene ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Beta Globin ◽  
Thalassemia Intermedia ◽  
Mild Phenotype ◽  
Beta Globin Gene ◽  
Alpha Thalassemia

Abstract In this study we have carried out alpha- and beta-globin gene analysis and defined the beta-globin gene polymorphisms in a group of patients with thalassemia intermedia of Sardinian descent. A group of patients (109) with thalassemia major of the same origin served as control. Characterization of the beta-thalassemia mutation showed either a frameshift mutation at codon 6 or a codon 39 nonsense mutation. We found that homozygotes for the frameshift mutation at codon 6 or compound heterozygotes for this mutation and for the codon 39 nonsense mutation develop thalassemia intermedia more frequently than thalassemia major. The frameshift mutation at codon 6 was associated with haplotype IX that contains the C-T change at position -158 5′ to the G gamma globin gene implicated in high gamma chain production and thus the mild phenotype. In patients' homozygotes for codon 39 nonsense mutation, those with thalassemia intermedia more frequently had the two- gene deletion form of alpha-thalassemia, or functional loss of the alpha 2 gene as compared with those with thalassemia major. In a few siblings with thalassemia major and intermedia, the thalassemia intermedia syndrome correlated with the presence of the -alpha/-alpha genotype. No cause for the mild phenotype was detected in the majority of patients who had not inherited either haplotype IX or alpha- thalassemia.

scholarly journals Loss of Alpha Globin Genes in Human Subjects Is Associated with Improved Nitric Oxide-Mediated Vascular Perfusion

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 6-7
Author(s):  
Christopher C Denton ◽  
Payal Shah ◽  
Silvie Suriany ◽  
Honglei Liu ◽  
Wanwara Thuptimdang ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Beneficial Effect ◽  
Board Of Directors ◽  
Globin Gene ◽  
Globin Genes ◽  
Vascular Perfusion ◽  
Advisory Committees ◽  
Alpha Thalassemia ◽  
Alpha Globin ◽  
Thalassemia Trait

Introduction Absence of alpha globin genes has long been known to influence the physiology of sickle cell disease (SCD). Individuals with SCD who are missing one or two alpha globin genes have decreased rates of cerebral vasculopathy, stroke, acute chest syndrome, and leg ulcers (Bernaudin, Blood 2008; Flanagan, Blood 2011; Nolan, Br J Haematol 2006). Although there is laboratory evidence of decreased hemolytic rate in these patients (Higgs, N Engl J Med 1982), the mechanism for their improved clinical outcomes has not been identified. Recently, the alpha globin protein has been shown to be present in the endothelial wall of human arterioles, where it modulates nitric oxide (NO) scavenging during vasoconstriction (Straub, Nature 2012). In mice, pharmacological inhibition of alpha globin leads to increased endothelial NO activity, independently of NO production, and results in increased blood perfusion, reduced systemic hypertension, and increased pulmonary artery vasodilation (Keller, Hypertension 2016; Alvarez, Am J Respir Cell Mol Biol 2017). The relationship between absence of alpha globin and arterial vasodilation, and the role of alpha globin in NO-mediated vascular signaling are potential mechanisms that could explain the beneficial effect of missing alpha globin genes in SCD. Using alpha thalassemia as a naturally occurring human model of alpha globin gene knockout, we hypothesized that loss of alpha globin genes leads to improvement in microvascular blood flow in thalassemia trait subjects without hemolysis. Methods Alpha thalassemia trait subjects missing one or two alpha globin genes, and healthy controls were recruited to the study, which was approved by the Children's Hospital Los Angeles Institutional Review Board. Blood samples were obtained from all subjects to test for hemoglobin, mean corpuscular volume (MCV), reticulocyte count, plasma hemoglobin, lactate dehydrogenase, and alpha globin genotype. We assessed flow-mediated dilation (FMD) of the brachial artery following distal forearm occlusion (Detterich, Blood 2015) simultaneously with laser Doppler flowmetry (LDF) and photoplethysmography (PPG) in the fingertip. We also measured the increase in microvascular perfusion with a thermal stimulus. The maximal change in vascular perfusion after provocation indicates vasodilatory capacity. Statistical analysis was performed in JMP® version 14 (SAS Institute Inc., USA). Results Twenty-seven subjects were enrolled, including 12 controls (4 alpha globin genes), 10 patients with 3 alpha globin genes and 5 with 2. The mean MCV was lower in subjects missing alpha globin genes than in controls (p=0.0099). Importantly, hemoglobin levels and markers of hemolysis were normal in both groups. There was no detectable difference in FMD between individuals missing one and two alpha globin genes; thus, these groups were combined and labeled as alpha trait for further analyses. FMD was significantly higher in alpha trait subjects after adjusting for age (Figure 1, p=0.0357). Missing alpha globin genes had no effect on microvascular flow by LDF or PPG (data not shown). Discussion FMD is an established and specific predictor of NO bioavailability (Thijssen, Am J Physiol Heart Circ Physiol 2011), and, in addition to shear-mediated NO circulation in conduit vessels, it reflects the sum of flow in multiple arteriolar networks downstream of the conduit artery. Using this method, a difference in endothelial function between control and alpha thalassemia trait was easily detected (Figure 1). Because endothelial alpha globin is present in arterioles rather than conduit vessels (Butcher, Free Radic Biol Med 2014), we measured microvascular flow in a 1-mm3 volume in the skin using a laser Doppler sensor, and in the fingertip by PPG, but were unable to detect an effect of alpha trait. As none of the subjects had anemia or evidence of hemolysis, the significantly increased FMD associated with loss of alpha globin genes is most likely due to increased NO as a result of decreased scavenging by alpha globin. The finding reported here that lower alpha globin gene number is associated with increased NO-related perfusion in humans may explain the beneficial effect of alpha thalassemia trait in SCD and suggests that the presence of alpha thalassemia trait may also play a role in other types of vascular disease. Disclosures Wood: BiomedInformatics: Consultancy; Imago Biosciences: Consultancy; BluebirdBio: Consultancy; Celgene: Consultancy; WorldcareClinical: Consultancy; Philips Medical Systems: Research Funding. Coates:apo pharma (Chiesi Pharma): Consultancy, Honoraria; Sangamo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Agios pharma: Consultancy, Honoraria; Vifor Pharma: Consultancy, Honoraria; Celgene, BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bluebird Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees.

scholarly journals Alpha globin gene deletions in amelioration of clinical severity in beta haemoglobinopathy subjects with the β0/β+ genotype

2020 ◽  
Author(s):  
Dipankar Saha ◽  
Prosanto Kumar Chowdhury ◽  
Amrita Panja ◽  
Debashis Pal ◽  
Sharmistha Chakraborty ◽  
...  
Keyword(s):  
Clinical Symptoms ◽  
Globin Gene ◽  
Disease Onset ◽  
Thalassemia Major ◽  
Clinical Severity ◽  
Beta Thalassemia ◽  
Beta Globin ◽  
Gene Deletions ◽  
Transfusion Requirements ◽  
Alpha Globin

AbstractThalassemia is the commonest inherited hemoglobinopathy worldwide. Variation of clinical symptoms entail differences in disease-onset and transfusion requirements. Our objective was to investigate the role of alpha gene deletions in modulating the clinical heterogeneity of thalassemia syndromes. A total of 214 individuals with diagnosed beta-thalassemia major/intermedia were included in the study. Beta globin mutations were determined and categorized as β+ and β0. Eight common alpha globin gene deletions were detected by multiplex GAP-PCR. Out of the 17 individuals with β+/β+, 16 did not harbour alpha deletions (αα/αα), and most of them were non-severe. On the other hand, out of 46 individuals with β0/β0, 30 did not reveal alpha deletions, whereas 16 possessed one or more alpha deletion(s). Accordingly, most of them presented as clinically severe. Out of the 151 β0/β+ individuals, 119 were negative for alpha deletion, whereas 32 possessed alpha deletions. It was observed that, only in this last category, alpha deletions made a significant contribution (P< 0.0001) in modulation of clinical non severity in this genotype. In conclusion, alpha globin gene deletions play a role to help in ameliorating the phenotype in the β+/β0 genotype. However, they may have only minor/no role in patients with β+/β+ or β0/β0 genotype.

scholarly journals Adult Hemoglobin Production, Chain Rebalance, and Splice Correction in IVS2-745 Beta-Thalassemia Patient Cells Using 2'-O-Methoxyethyl Splice-Switching Oligos

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1014-1014
Author(s):  
Alisa Cheung Dong ◽  
Valentina Ghiaccio ◽  
Irene Motta ◽  
Shuling Guo ◽  
Raechel Peralta ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Globin Gene ◽  
Model System ◽  
Beta Thalassemia ◽  
Beta Globin ◽  
Advisory Committees ◽  
Beta Globin Gene ◽  
Cd34 Cells ◽  
Adult Hemoglobin

Abstract Hemoglobinopathies are the most common inherited blood disorders. World Health Organization statistics show that in the Mediterranean, Eastern European, and Middle Eastern regions, frequencies range from 0.1 to 4.9/1000 of live births. The mutation known as IVS2-745 is relatively common in the regions of Spain, Jordan, Romania, and Serbia (Ithanet Database, http://www.ithanet.eu/db/ithamaps), reaching as high as 15-20% of beta-thalassemia mutations in these regions. The IVS2-745 is a splicing mutation that occurs in intron 2 of the beta-globin gene and results in an aberrantly spliced mRNA that incorporates an extra exon and premature stop codon. Here we report novel uniform 2'-O-methoxyethyl (2'-MOE) splice switching oligos (SSOs) that reverse the aberrant splicing and restore up to 80% adult hemoglobin (HbA) production in vitro. Uniform 2'-MOE SSOs do not mediate RNase H degradation when they bind their targets; therefore, they can be used to redirect the splicing machinery and restore WT splicing. After generating mouse erythroleukemia cells that carry the human IVS2-745 mutated beta-globin gene, lead 2'-MOE SSOs targeting the 745 mRNA were raised against these cell lines. With these lead SSOs we have demonstrated aberrant 745 to WT splice switching in 5 patient samples. CD34+ cells were isolated from the blood of four 745/β0 compound heterozygotes and one 745/ 745 homozygote (Breda et al, PloS One 2012). After CD34+ expansion, cells were differentiated to the red cell lineage and treated via syringe loading or lipofectamine transfection with 2'-MOE SSOs. Up to 80% HbA protein production was restored with 2'MOE-SSO treatment in the 745 homozygote patient sample (Figure 1), and up to 60% HbA in multiple 745 compound heterozygote specimens. Compared to 3-6% HbA in scramble treated controls, this represents up to a 20-fold increase in HbA with treatment. In addition to HbA production, we have shown improvement in other parameters characteristic in beta-thalassemia, such as the imbalance of alpha and beta chains and the accumulation of toxic alpha-only homotetramers. 2'MOE SSOs are able to reinstate balance of beta- to alpha-like chains, which resulted in a near elimination of toxic alpha-only homotetramers in the homozygote cell lysate as detected by HPLC (Figure 1). We further proved the benefit of 2'MOE SSOs in a 745/Sickle model system, where in vitro sickling was significantly reduced as a result of increased levels of HbA. To create this model system, we transduced CD34+ cells from a homozygous sickle patient specimen with a lentivirus expressing human IVS2-745 beta-globin. With vector copy numbers ~2, this system replicates what a single allele would do, as the 2 endogenous sickle alleles are equally matched. Upon differentiation and exposure to hypoxia, in vitro sickling was reduced by 50% in 2'MOE-SSO treated samples as compared to scramble controls (Figure 2). In summary, 2'MOE-SSOs are a promising therapy for certain splicing forms of beta-thalassemia. Their ability to correct the underlying splicing cause offers a pharmacological treatment that is both direct and specific. As such, this therapy could help patients reduce their transfusion dependence or even reach transfusion independence. Disclosures Guo: Ionis Pharmaceuticals: Employment, Equity Ownership. Peralta:Ionis Pharmacueticals: Employment. Cappellini:Celgene: Membership on an entity's Board of Directors or advisory committees; Genzyme-Sanofi: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees.

scholarly journals Molecular analysis of beta zero-thalassemia intermedia in Sardinia

Blood ◽  
1989 ◽  
Vol 74 (2) ◽  
pp. 823-827 ◽  
Author(s):  
R Galanello ◽  
E Dessi ◽  
MA Melis ◽  
M Addis ◽  
MA Sanna ◽  
...  
Keyword(s):  
Nonsense Mutation ◽  
Frameshift Mutation ◽  
Globin Gene ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Beta Globin ◽  
Thalassemia Intermedia ◽  
Mild Phenotype ◽  
Beta Globin Gene ◽  
Alpha Thalassemia

In this study we have carried out alpha- and beta-globin gene analysis and defined the beta-globin gene polymorphisms in a group of patients with thalassemia intermedia of Sardinian descent. A group of patients (109) with thalassemia major of the same origin served as control. Characterization of the beta-thalassemia mutation showed either a frameshift mutation at codon 6 or a codon 39 nonsense mutation. We found that homozygotes for the frameshift mutation at codon 6 or compound heterozygotes for this mutation and for the codon 39 nonsense mutation develop thalassemia intermedia more frequently than thalassemia major. The frameshift mutation at codon 6 was associated with haplotype IX that contains the C-T change at position -158 5′ to the G gamma globin gene implicated in high gamma chain production and thus the mild phenotype. In patients' homozygotes for codon 39 nonsense mutation, those with thalassemia intermedia more frequently had the two- gene deletion form of alpha-thalassemia, or functional loss of the alpha 2 gene as compared with those with thalassemia major. In a few siblings with thalassemia major and intermedia, the thalassemia intermedia syndrome correlated with the presence of the -alpha/-alpha genotype. No cause for the mild phenotype was detected in the majority of patients who had not inherited either haplotype IX or alpha- thalassemia.

scholarly journals Current Perspective of Beta Thalassemia and Its Treatment Strategies

2019 ◽  
Author(s):  
Shaukat Ali ◽  
Shumaila Mumtaz ◽  
Hafiz Abdullah Shakir ◽  
Hafiz Muhammad Tahir ◽  
Tafail Akbar Mughal
Keyword(s):  
Genetic Testing ◽  
Blood Transfusion ◽  
Dna Analysis ◽  
Complete Blood Count ◽  
Globin Gene ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Beta Globin ◽  
Hematopoietic Stem ◽  
Thalassemia Minor

Thalassemia is genetic blood disease cause by absence or decrease of one or more of the globin chain synthesis. Beta thalassemia is characterized by one or more mutations in beta globin gene. Absence or reduced amount the of beta globin chains cause ineffective erythropoiesis which leads to anemia. Beta thalassemia has been further divided into three main forms: Thalassemia minor/silent carrier, major and intermedia. More severe form is thalassemia major in which patients depend upon blood transfusion for survival and high level of iron occur as a consequence of consistent blood transfusion. Over loaded iron invokes the synthesis of reactive oxygen species that are toxic in redundancy and triggering the impairment to vascular, endocrine and hepatic system. Thalassemia can be diagnosed and detected through various laboratory tests such as blood smear, prenatal testing (genetic testing of amniotic fluid), DNA analysis (genetic testing) and complete blood count. Treatment of thalassemia intermedia is symptomatic but it can also be managed by splenectomy and folic supplementation. While thalassemia major can be treated by transplantation of bone marrow, regular transfusion of blood and iron chelation treatment, stimulation of fetal hemoglobin production, hematopoietic stem cell transplantation and gene therapy.

scholarly journals A first case of hemoglobin Castilla [Beta 32(B14) Leu>Arg; HBB: c.98T>G] associated with [IVS-I-1 (G>A); HBB:c.92+1G>A] mutation found in a Syrian betathalassemia patient

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ahmad Shoujaa ◽  
Yasser Mukhalalaty ◽  
Hossam Murad ◽  
Faizeh Al-Quobaili
Keyword(s):  
Molecular Analysis ◽  
Clinical Case ◽  
Globin Gene ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Blood Transfusions ◽  
Beta Globin ◽  
First Report ◽  
Beta Thalassemia Major ◽  
First Case

Beta thalassemia (β-thal) is one of the most common worldwide inherited hemoglobinopathies. Proper identification and diagnosis of hemoglobin (Hb) variants provide a major challenge. In this report, we describe a 1-year-old boy, presented with the diagnosis of β-TM (beta thalassemia major), has received regular blood transfusions. The molecular analysis revealed the presence of rare Hb Castilla [Beta 32(B14) Leu>Arg; HBB: c.98T>G] variant associated with β0 [IVS-I-1 (G>A); AG^GTTGGT- >AGATTGGT beta0] (HBB:c.92+1G>A) Mutation in beta-globin (β-globin) gene. To our knowledge, this is the first report of Hb Castilla [Beta 32(B14) Leu>Arg] in ExonII of β-globin gene which were found in Syrian male proband. However, we should investigate abnormal hemoglobins in patients with beta thalassemia to determine whether they have involvement with β-thalassemia mutations in the clinical case of the patients or not.

scholarly journals Thalassemia intermedia resulting from a mild beta-thalassemia mutation

Blood ◽  
1989 ◽  
Vol 73 (2) ◽  
pp. 601-605 ◽  
Author(s):  
MC Rosatelli ◽  
L Oggiano ◽  
G Battista Leoni ◽  
T Tuveri ◽  
A Di Tucci ◽  
...  
Keyword(s):  
Nonsense Mutation ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Compound Heterozygous ◽  
Beta Globin ◽  
Promoter Mutation ◽  
Mild Phenotype ◽  
Alpha Globin ◽  
Definition Of ◽  
Thalassemia Mutation

Abstract We investigated the molecular basis for a mild phenotype in a group of patients with beta + thalassemia originating from Northern Sardinia by definition of the beta-thalassemia mutation, alpha-globin mapping and beta-globin haplotype determination. In nine patients, we detected the compound heterozygous state for the -87 promoter mutation and the codon 39 nonsense mutation; in one patient, we detected the combination of the codon 39 nonsense mutation and beta + IVS-1 nt 6 mutation. These patients were either nontransfusion dependent for survival or became transfusion dependent later. We did not detect the -87 promoter mutation in any of 115 thalassemia major patients originating from the same part of Sardinia, investigated as controls. Heterozygotes for the - 87 promoter mutation showed statistically higher hemoglobin (Hb) levels and larger and better hemoglobinized RBCs as compared with heterozygotes for the codon 39 nonsense mutation. From these data, we conclude that the -87 promoter mutation is a mild thalassemia allele, able to produce a phenotype of intermediate severity even in combination with a beta degree-thalassemia mutant. The coinheritance of alpha-thalassemia or the -++-- 5′ subhaplotype in several cases may have contributed to development of the mild clinical picture. Characterization of the beta-thalassemia mutation in combination with alpha-globin mapping and haplotype analysis may allow a better estimate of the probability of a given clinical phenotype, thus permitting more accurate counseling.

scholarly journals Hypomethylation of DNA derived from purified human erythroid cells correlates with gene activity of the beta-globin cluster

Blood ◽  
1985 ◽  
Vol 66 (5) ◽  
pp. 1202-1207 ◽  
Author(s):  
A Oppenheim ◽  
Y Katzir ◽  
E Fibach ◽  
A Goldfarb ◽  
E Rachmilewitz
Keyword(s):  
Peripheral Blood ◽  
Globin Gene ◽  
Genetic Regulation ◽  
Inverse Correlation ◽  
Thalassemia Major ◽  
Gene Activity ◽  
Beta Thalassemia ◽  
Globin Genes ◽  
Beta Globin ◽  
A Site

Abstract Analysis of methylation at the beta-globin gene cluster was carried out on DNA derived from nucleated RBCs (orthochromatic normoblasts) isolated from peripheral blood of patients with beta-thalassemia major or other congenital hemolytic anemia after splenectomy. A procedure to separate these normoblasts from the other nucleated cells of the peripheral blood was developed, providing us with a convenient source of DNA for investigating parameters related to human erythroid differentiation. Blood samples were obtained from six adult patients who express their gamma-globin genes at different levels. Inverse correlation between methylation and gene activity was consistently observed for five of the eight sites analyzed. A site 3′ to the beta gene was always unmethylated, two sites flanking the epsilon gene were always found to be methylated, and two sites 5′ to the two gamma genes, G gamma and A gamma, were hypomethylated in correlation with gamma gene activity of the individual patients. A site 5′ to the delta gene was unmethylated in normoblasts as well as in WBC. No apparent relation between hypomethylation and gene activity was observed for two additional sites. The results suggest that methylation at specific chromosomal locations participate in genetic regulation of the beta- like globin genes in humans.

Ineffective Erythropoiesis and Production of Normoblasts with a Beta Thalassemia Major Phenotype Using CD34+ Cells From Healthy Donors

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1085-1085
Author(s):  
Y.Terry Lee ◽  
Colleen Byrnes ◽  
Emily Riehm Meier ◽  
Antoinette Rabel ◽  
Jeffery L. Miller
Keyword(s):  
Ex Vivo ◽  
Globin Gene ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Beta Globin ◽  
Ineffective Erythropoiesis ◽  
Globin Mrna ◽  
Cell Counts ◽  
Cd34 Cells ◽  
Gene And Protein Expression

Abstract Abstract 1085 Reversal of anemia is the major target of thalassemia research, but studies of the molecular and cellular basis of the ineffective erythropoiesis of thalassemia are limited by access to donor progenitor cells. Here we demonstrate that thalassemic erythropoiesis may be recapitulated ex vivo by reducing the expression of hemoglobin in cultured CD34+ cells. Using lentiviral transduction of progenitor cells obtained from three healthy adult human donors, shRNA molecules were screened for their ability to reduce beta-globin gene and protein expression over 21 days in culture. Cells transduced with a scrambled vector served as donor-matched controls. Among the screened shRNA, one named HBB caused a consistent and significant reduction in beta-globin mRNA and protein. Beta-globin mRNA was reduced to levels <10% (p<0.001) compared to that of the controls (day14/21), while maintaining expression of gamma- and alpha-globin mRNA. HPLC was performed on an equivalent number of cells sampled on culture day 21 for hemoglobin type (HbA vs. HbF) and quantitation (area under each HPLC peak). The HbA peak was reduced by 96%, and there was a minor increase in the HbF peak (1.6 fold) after HBB transduction. Based upon these quantitative changes in hemoglobin, HbF represented 49.3±9.3% in the HBB transduced population compared with 2.9±0.7% (p<0.01) in controls. On culture day 14, there was no significant difference in glycophorin A (CD235), transferrin receptor (CD71), or cellular morphology despite the reduction in beta-globin mRNA. However, impaired terminal differentiation was detected by retainment of surface CD71 and a lack of enucleation during the third week of culture. Cell counts were lower in HBB transduced cells during the final stages of erythroid differentiation with a 61% (p=0.03) reduction in total cell counts by day 21 when compared to controls. Annexin V assay on day 21 also demonstrated increased phosphatidylserine expression in the HBB transduced cells [HBB=55.7±14.4% vs. Control=25.0±3.0%] in association with the decreased terminal differentiation. GDF15 quantitation demonstrated a significant (p=0.006) increase in the culture supernatants of HBB transduced cells. Sorted cytospin preparations revealed a distinct population of mature normoblasts containing a highly condensed nucleus surrounded by a thin ring of hypochromic cytoplasm. Reduction of erythroblast beta-globin gene and protein expression to levels associated with beta thalassemia major in humans causes ineffective erythropoiesis ex vivo by reducing cell production, increasing surface expression of phosphatidylserine, and impairing enucleation during terminal maturation. Efforts are now underway to use the culture system to explore mechanisms whereby reduced hemoglobin synthesis causes normoblast defects, and for screening of chemical and genetic rescue therapies for the thalassemic erythroid phenotype. Disclosures: No relevant conflicts of interest to declare.

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