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1.
Cell ; 185(8): 1261-1265, 2022 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-35385685

RESUMO

Through studies in mice and in humans, Stuart Orkin showed that GATA-1 is a master transcriptional regulator of hematopoiesis. He has highlighted the role of BCL11A in the fetal-adult hemoglobin switch. The Gairdner Foundation Award recognizes Orkin's contribution to the development of gene therapy of sickle cell disease.


Assuntos
Anemia Falciforme , Distinções e Prêmios , Terapia Genética , Anemia Falciforme/genética , Anemia Falciforme/terapia , Animais , Modelos Animais de Doenças , Hemoglobina Fetal/genética , Hematopoese/genética , Humanos , Camundongos , Proteínas Repressoras/genética
2.
Pediatr Blood Cancer ; 69(6): e29607, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35373884

RESUMO

BACKGROUND: Hydroxyurea is the primary treatment for sickle cell anemia (SCA), yet real-world implementation in high-income settings is suboptimal. Variation in prescribed hydroxyurea dose and patient adherence in these settings can both affect actual exposure to hydroxyurea. Quantifying the contributions of hydroxyurea dose and medication adherence to the relationship between hydroxyurea exposure and hematologic parameters could inform strategies to optimize exposure and improve outcomes. PROCEDURE: We evaluated the relationship between hydroxyurea exposure, defined by average prescribed dose and adherence, and hematologic parameters using data from children with SCA who were enrolled in two prospective hydroxyurea adherence studies. Hydroxyurea adherence was assessed by video directly observed therapy or electronic pill bottle and medication administration record. Average prescribed dose was abstracted from prescriptions in patients' electronic medical record. Participants with a hydroxyurea exposure >20 mg/kg/day and ≤20 mg/kg/day were included in the higher and lower exposure groups, respectively. RESULTS: Forty-five participants were included in the analysis (56% male; median age 12 years [range 2-19]; 98% Black). Higher exposed participants (n = 23) were prescribed a higher dose (27.2 vs. 24.4 mg/kg/day, p = .002) and had better adherence (0.92 vs. 0.71, p ≤ .001) compared to lower exposed participants (n = 22). Higher exposure was associated with higher fetal hemoglobin (p = .04) and mean corpuscular volume (p = .02). CONCLUSIONS: Higher hydroxyurea exposure is associated with improved hematologic parameters in the high-income setting and is affected by both prescribed dose and adherence. Future studies are needed to optimize both adherence and hydroxyurea prescribing and confirm that increasing exposure improves clinical outcomes in this setting.


Assuntos
Anemia Falciforme , Antidrepanocíticos , Hidroxiureia , Adolescente , Anemia Falciforme/tratamento farmacológico , Antidrepanocíticos/uso terapêutico , Criança , Pré-Escolar , Feminino , Hemoglobina Fetal , Humanos , Hidroxiureia/uso terapêutico , Masculino , Adesão à Medicação , Estudos Prospectivos , Adulto Jovem
3.
Expert Opin Ther Targets ; 26(4): 347-359, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35418266

RESUMO

INTRODUCTION: Sickle cell disease and ß thalassemia are the principal ß hemoglobinopathies. The complex pathophysiology of sickle cell disease is initiated by sickle hemoglobin polymerization. In ß thalassemia, insufficient ß-globin synthesis results in excessive free α globin, ineffective erythropoiesis, and severe anemia. Fetal hemoglobin (HbF) prevents sickle hemoglobin polymerization; in ß thalassemia HbF compensates for the deficit of normal hemoglobin. When HbF constitutes about a third of total cell hemoglobin, the complications of sickle cell disease are nearly totally prevented. Similarly, sufficient HbF in ß thalassemia diminishes or prevents ineffective erythropoiesis and hemolysis. AREAS COVERED: This article examines the pathophysiology of ß hemoglobinopathies, the physiology of HbF, intracellular distribution, and the regulation of HbF expression. Inducing high levels of HbF by targeting its regulatory pathways pharmacologically or with cell-based therapeutics provides major clinical benefit and perhaps a 'cure.' EXPERT OPINION: Erythrocytes must contain about 10 pg of HbF to 'cure' sickle cell disease. If HbF is the only hemoglobin present, much higher levels are needed to 'cure' ß thalassemia. These levels of HbF can be obtained by different iterations of gene therapy. Small molecule drugs that can achieve even modest pancellular HbF concentrations are a major unmet need.


Assuntos
Anemia Falciforme , Hemoglobinopatias , Talassemia beta , Anemia Falciforme/tratamento farmacológico , Proteínas de Transporte/genética , Hemoglobina Fetal/genética , Hemoglobina Fetal/metabolismo , Hemoglobina Falciforme/metabolismo , Hemoglobina Falciforme/uso terapêutico , Hemoglobinopatias/terapia , Hemoglobinas/metabolismo , Hemoglobinas/uso terapêutico , Humanos , Talassemia beta/tratamento farmacológico , Talassemia beta/genética
4.
Curr Res Transl Med ; 70(3): 103335, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35303690

RESUMO

PURPOSE OF THE STUDY: Fetal hemoglobin (HbF) is a modifier of the clinical and hematologic phenotype of sickle cell anemia (SCA). Three quantitative trait loci (QTL) modulate HbF expression. The neurocognitive effects of variants in these QTL have yet to be explored. We evaluated the relation between 11 SNPs in the three HbF QTL: BCL11A, MYB, the HBB gene cluster, and full-scale intelligence (IQ) in SCA. PATIENTS AND METHODS: The prospective longitudinal cohort study, Sickle Cell Clinical Research and Intervention Program, was used as a discovery cohort (n = 166). The genotypes for 11 SNPs were extracted through whole genome sequencing and were analyzed using an additive model. A polygenic score for HbF (PGSHbF) integrating the numbers of low HbF alleles from 11 SNPs was analyzed as a continuous variable. The Cooperative Study of Sickle Cell Disease (n = 156) and the Silent Cerebral Infarction Transfusion (n = 114) Trial were used as two independent replication cohorts. Benjamini and Hochberg approach was used to calculate false discovery rate adjusted p-value (pFDR). RESULTS: HbF was positively associated with IQ (minimum raw p = 0·0018) at pFDR<0·05. HbF mediated the relationship between two BCL11A SNPs, rs1427407 and rs7606173, HBS1L-MYB: rs9494142, and PGSHbF with IQ (minimum raw p = 0·0035) at pFDR<0·05. CONCLUSION: As the major modulator of the severity of SCA, HbF also influences neurocognition, which is done through mediation of its QTL. These findings have implications for early identification of neurocognitive risk and targeted intervention.


Assuntos
Anemia Falciforme , Hemoglobina Fetal , Anemia Falciforme/complicações , Anemia Falciforme/genética , Hemoglobina Fetal/análise , Hemoglobina Fetal/genética , Hemoglobina Fetal/metabolismo , Humanos , Estudos Longitudinais , Estudos Prospectivos , Proteínas Repressoras/genética
5.
6.
Sci Rep ; 12(1): 4952, 2022 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-35322124

RESUMO

Reactivating of fetal hemoglobin (HbF; α2γ2) can ameliorate the severity of ß-thalassemia disease by compensating for adult hemoglobin deficiency in patients. Previously, microarray analysis revealed that zinc finger protein (ZNF)802 (also known as Juxta-posed with another zinc finger gene-1 (JAZF1)) was upregulated in human erythroblasts derived from adult peripheral blood compared with fetal liver-derived cells, implying a potential role as a HbF repressor. However, deficiency in ZNF802 induced by lentiviral shRNA in ß0-thalassemia/hemoglobinE erythroblasts had no effect on erythroblast proliferation and differentiation. Remarkably, the induction of HBG expression was observed at the transcriptional and translational levels resulting in an increase of HbF to 35.0 ± 3.5%. Interestingly, the embryonic globin transcripts were also upregulated but the translation of embryonic globin was not detected. These results suggest ZNF802 might be a transcriptional repressor of the γ-globin gene in adult erythroid cells.


Assuntos
Talassemia , Talassemia beta , Adulto , Proteínas Correpressoras/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação para Baixo/genética , Eritroblastos/metabolismo , Hemoglobina Fetal/genética , Hemoglobina Fetal/metabolismo , Humanos , Fatores de Transcrição/metabolismo , gama-Globinas/genética , gama-Globinas/metabolismo
7.
Br J Haematol ; 197(1): 97-109, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35118652

RESUMO

Sickle cell disease (SCD) is a genetic disorder that affects millions around the world. Enhancement of fetal γ-globin levels and fetal haemoglobin (HbF) production in SCD patients leads to diminished severity of many clinical features of the disease. We recently identified the transcriptional co-activator PGC-1α as a new protein involved in the regulation of the globin genes. Here, we report that upregulation of PGC-1α by infection with a lentivirus expressing PGC-1α or by the small-molecule PGC-1α agonist ZLN005 in human primary erythroid progenitor CD34+ cells induces both fetal γ-globin mRNA and protein expression as well as the percentage of HbF-positive cell (F cells) without significantly affecting cell proliferation and differentiation. We further found that the combination of ZLN005 and hydroxyurea (hydroxycarbamide) exhibited an additive effect on the expression of γ-globin and the generation of F cells from cultured CD34+ cells. In addition, ZLN005 induced robust expression of the murine embryonic ßh1-globin gene and to a lesser extent, human γ-globin gene expression in sickle mice. These findings suggest that activation of PGC-1α by ZLN005 might provide a new path for modulating HbF levels with potential therapeutic benefit in ß-hemoglobinopathies.


Assuntos
Anemia Falciforme , Hemoglobinopatias , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Anemia Falciforme/tratamento farmacológico , Anemia Falciforme/genética , Animais , Hemoglobina Fetal/metabolismo , Expressão Gênica , Regulação da Expressão Gênica , Humanos , Camundongos , gama-Globinas/genética
8.
Expert Rev Hematol ; 15(2): 107-116, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35143361

RESUMO

INTRODUCTION: The hematological and clinical features vary markedly between the different genotypes of sickle cell disease. Even within the single genotype of homozygous sickle cell disease (HbSS), there is marked variability that is presumed to result from interacting genetic and environmental factors. AREAS COVERED: The classification of the different genotypes of sickle cell disease with approximate prevalence at birth in different communities and some of the major clinical and hematological differences. This assessment includes three potential genetic factors influencing hematology and clinical outcome in HbSS, the beta globin haplotype, alpha thalassemia, and persistence of fetal hemoglobin (HbF). EXPERT OPINION: The author is a clinician with experience of sickle cell disease primarily in Jamaica but also in Greece, Uganda, Saudi Arabia, and India. It is therefore necessarily an account of clinical data and does not address current debates on molecular mechanisms. Most data derive from Jamaica where efforts have been made to reduce any symptomatic bias by long-term follow-up of patients all over the Island and further reduced by a cohort study based on newborn screening, which has been in operation for over 48 years.


Assuntos
Anemia Falciforme , Talassemia alfa , Anemia Falciforme/diagnóstico , Anemia Falciforme/epidemiologia , Anemia Falciforme/genética , Variação Biológica da População , Estudos de Coortes , Hemoglobina Fetal/genética , Haplótipos , Hemoglobina Falciforme/genética , Humanos , Recém-Nascido , Talassemia alfa/epidemiologia , Talassemia alfa/genética , Globinas beta/genética
9.
Elife ; 112022 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-35147495

RESUMO

Naturally occurring point mutations in the HBG promoter switch hemoglobin synthesis from defective adult beta-globin to fetal gamma-globin in sickle cell patients with hereditary persistence of fetal hemoglobin (HPFH) and ameliorate the clinical severity. Inspired by this natural phenomenon, we tiled the highly homologous HBG proximal promoters using adenine and cytosine base editors that avoid the generation of large deletions and identified novel regulatory regions including a cluster at the -123 region. Base editing at -123 and -124 bp of HBG promoter induced fetal hemoglobin (HbF) to a higher level than disruption of well-known BCL11A binding site in erythroblasts derived from human CD34+ hematopoietic stem and progenitor cells (HSPC). We further demonstrated in vitro that the introduction of -123T > C and -124T > C HPFH-like mutations drives gamma-globin expression by creating a de novo binding site for KLF1. Overall, our findings shed light on so far unknown regulatory elements within the HBG promoter and identified additional targets for therapeutic upregulation of fetal hemoglobin.


Assuntos
Anemia Falciforme/genética , Sistemas CRISPR-Cas , Hemoglobina Fetal/genética , Edição de Genes/métodos , Adenina/metabolismo , Linhagem Celular , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Citosina/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Humanos , Mutação Puntual , Regiões Promotoras Genéticas , Globinas beta/genética , Talassemia beta/genética , gama-Globinas/genética
11.
Eur J Obstet Gynecol Reprod Biol ; 271: 93-96, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35180513

RESUMO

OBJECTIVE: Hemolytic disease of the fetus and newborn is characterized by fetal anemia, secondary to maternal alloantibody-mediated fetal erythrocyte destruction. Despite our reliance on intrauterine blood transfusion (IUT) to maintain severely affected pregnancies, it remains difficult to predict the fetal response to an infusion of donor blood. Our objective was to determine the daily rate of decline in fetal hemoglobin following one, two, and three transfusions. We also evaluated the relationship between the fetal hemoglobin level and the corresponding doppler measurement of the fetal middle cerebral artery peak systolic velocity (MCA-PSV). STUDY DESIGN: A prospective observational study of all singleton pregnancies treated with intrauterine transfusion for fetal anemia secondary to maternal alloimmunization at the National Maternity Hospital, a tertiary referral centre, was conducted over a 10-year period (2011-2020). Demographic and clinical data was obtained from the electronic patient records. Ethical approval was granted by the Ethics and Research Committee of the National Maternity Hospital. RESULTS: A total of 90 intrauterine blood transfusions were performed in 41 fetuses affected by maternal alloimmunization, of which 70% (n = 29), 34% (n = 14) and 15% (n = 6) required a 2nd, 3rd, and 4th transfusion, respectively. The mean rate of decline in fetal hemoglobin following the first transfusion was 0.4 g/dl/day (range, 0.12-0.64 g/dl/day). The mean rate of decline was lower after repeat transfusions at 0.27 g/dl/day (range, 0.16-0.45 g/dl/day). The sensitivity of MCA-PSV threshold of 1.5 Multiples of the Median (MoM) to detect moderate-severe anaemia declined with rank of IUT, from 82% after one previous transfusion, to 75% after two or more previous transfusions. No fetal mortality was seen in our series. CONCLUSION: Knowledge of the expected rate of decline in fetal hemoglobin following an IUT aids in the determination of appropriate timing of subsequent transfusions in a fetus affected by red cell alloimmunization. We observed a reducing rate of daily decline in hemoglobin in fetuses requiring successive transfusions. Our findings suggest a reduced accuracy of the MCA-PSV threshold of 1.5 MoM in determining the optimal timing of 2nd, 3rd, and 4th transfusions.


Assuntos
Transfusão de Sangue Intrauterina , Isoimunização Rh , Velocidade do Fluxo Sanguíneo , Eritrócitos/química , Feminino , Hemoglobina Fetal/análise , Humanos , Recém-Nascido , Artéria Cerebral Média/diagnóstico por imagem , Gravidez , Isoimunização Rh/complicações , Isoimunização Rh/terapia , Ultrassonografia Pré-Natal
12.
Gene ; 820: 146289, 2022 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-35143940

RESUMO

Reactivation of fetal hemoglobin by editing the B-cell lymphoma/leukemia 11A (BCL11A) erythroid enhancer is an effective gene therapy for ß-thalassemia. Using the CRISPR/Cas9 system, fetal γ-globin expression can be robustly reactivated to mitigate the clinical course of ß-thalassemia. In our study, we found that the transfection efficiencies of CD34+ hematopoietic stem/progenitor cells (HSPCs) were significantly and negatively correlated with the length of plasmids and greatly affected by the linearization of plasmids. Furthermore, the transgene expression of minicircles (MC) without plasmid backbone sequences was better both in vitro and in vivo compared with conventional plasmids. Thus, MC DNA was used to deliver the cassette of Staphylococcus aureus Cas9 (SaCas9) into HSPCs, and a single-guide RNA targeting the erythroid enhancer region of BCL11A was selected. After electroporation with MC DNA, an evident efficiency of gene editing and reactivation of γ-globin expression in erythroblasts derived from unsorted HSPCs was acquired. No significant off-target effects were found by deep sequencing. Furthermore, fragments derived from lentiviral vectors, but not MC DNA, were highly enriched in promoter, exon, intron, distal-intergenic, and cancer-associated genes, indicating that MC DNA provided a relatively safe and efficient vector for delivering transgenes. The developed MC DNA vector provided a potential approach for the delivery of SaCas9 cassette and the reactivation of γ-globin expression for ameliorating syndromes of ß-thalassemia.


Assuntos
DNA Circular/uso terapêutico , Hemoglobina Fetal/metabolismo , Proteínas Repressoras/metabolismo , Talassemia beta/genética , Talassemia beta/terapia , gama-Globinas/genética , gama-Globinas/metabolismo , Animais , Proteínas de Bactérias/metabolismo , Proteína 9 Associada à CRISPR/metabolismo , Sistemas CRISPR-Cas , DNA Circular/metabolismo , Edição de Genes , Terapia Genética/métodos , Vetores Genéticos , Células-Tronco Hematopoéticas/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Plasmídeos , Regiões Promotoras Genéticas , RNA Guia/metabolismo , RNA Guia/uso terapêutico
13.
Sci Rep ; 12(1): 2752, 2022 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-35177777

RESUMO

Hydroxyurea is an antimetabolite drug that induces fetal haemoglobin in sickle cell disease. However, its clinical usefulness in ß-thalassaemia is unproven. We conducted a randomised, double-blind, placebo-controlled clinical trial to evaluate the efficacy and safety of hydroxyurea in transfusion-dependent ß-thalassaemia. Sixty patients were assigned 1:1 to oral hydroxyurea 10-20 mg/kg/day or placebo for 6 months by stratified block randomisation. Hydroxyurea treatment did not alter the blood transfusion volume overall. However, a significantly higher proportion of patients on hydroxyurea showed increases in fetal haemoglobin percentage (89% vs. 59%; p < 0.05) and reductions in erythropoietic stress as measured by soluble transferrin receptor concentration (79% vs. 40%; p < 0.05). Based on fetal haemoglobin induction (> 1.5%), 44% of patients were identified as hydroxyurea-responders. Hydroxyurea-responders, required significantly lower blood volume (77 ± SD27ml/kg) compared to hydroxyurea-non-responders (108 ± SD24ml/kg; p < 0.01) and placebo-receivers (102 ± 28ml/kg; p < 0.05). Response to hydroxyurea was significantly higher in patients with HbE ß-thalassaemia genotype (50% vs. 0%; p < 0.01) and Xmn1 polymorphism of the γ-globin gene (67% vs. 27%; p < 0.05). We conclude that oral hydroxyurea increased fetal haemoglobin percentage and reduced erythropoietic stress of ineffective erythropoiesis in patients with transfusion-dependent ß-thalassaemia. Hydroxyurea reduced the transfusion burden in approximately 40% of patients. Response to hydroxyurea was higher in patients with HbE ß-thalassaemia genotype and Xmn1 polymorphism of the γ-globin gene.


Assuntos
Hidroxiureia/administração & dosagem , Talassemia beta/tratamento farmacológico , Administração Oral , Adolescente , Adulto , Transfusão de Sangue , Método Duplo-Cego , Feminino , Hemoglobina Fetal/genética , Hemoglobina Fetal/metabolismo , Humanos , Masculino , Polimorfismo Genético , Talassemia beta/sangue , Talassemia beta/genética
14.
BMC Pregnancy Childbirth ; 22(1): 160, 2022 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-35220948

RESUMO

BACKGROUND: The guidelines of National Health Service(NHS, the United Kingdom) recommended for use in obstetrics at increased risk of bleeding, requiring two suction devices to reduce amniotic fluid contamination, however, when comes to massive hemorrhage, it is may difficult to operate because the complex operation may delay time. The aim of the study was to detect the effect of amniotic fluid recovery on intraoperative cell salvage in obstetrics and provide evidence for clinical applications. METHOD: Thirty-four patients undergoing elective cesarean section were randomly divided into two groups. In group 1, the cumulative blood from the operation field, including the amniotic fluid, was collected using a single suction device for processing. In group 2, after suctioning away the amniotic fluid using another suction device for the cumulative blood from the operation field. From each group, four samples were taken, including maternal venous blood (sample I), blood before washing (sample II), blood after washing (sample III) and blood after filtration with a leukocyte filter (sample IV), to detect serum potassium (K +), hemoglobin (Hb), white blood cell (WBC), fetal hemoglobin (HbF), alpha fetoprotein (AFP) and squamous cell (SC) levels. RESULTS: The AFP, K + and WBC levels of sample III and sample IV were significantly lower than sample I in group 1 and group 2 (P < 0.05). Significantly more SCs were found in sample III than in sample I in group 1 and group 2 (P < 0.05), but SCs of sample IV had no statistical difference compared to sample I in group 1 and group 2 (P > 0.05). There was no significant difference in the K + , Hb, WBC, AFP and SC levels of sample IV between group 1 and group 2 (P > 0.05). The HbF levels of sample III and sample IV were significantly higher in group 1 than in group 2 (P < 0.05). CONCLUSION: There is little or no possibility for AF contamination to enter the re-infusion system when used in conjunction with a leucodepletion filter. For maternal with Rh-negative blood, we recommend two suction devices to reduce HbF pollution. TRIAL REGISTRATION: ChiCTR1800015684 , 2018.4.15.


Assuntos
Líquido Amniótico , Análise Química do Sangue , Cesárea , Recuperação de Sangue Operatório/métodos , Adulto , Células Epiteliais , Feminino , Hemoglobina Fetal/análise , Hemoglobinas/análise , Humanos , Leucócitos , Potássio/análise , Gravidez , Sucção/métodos , alfa-Fetoproteínas/análise
15.
Ann Hematol ; 101(3): 541-548, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35039901

RESUMO

The presence of leg ulcers in individuals with sickle cell disease often represents an early sign of vasculopathy and future end organ damage. Pathophysiological mechanisms of formation and evolution of leg ulcers are poorly understood; nevertheless, HbF has been associated with lower incidence of leg ulcers, while hydroxyurea has been correlated with high risk of leg ulcers. As a result, there is hesitation regarding hydroxyurea use in patients with SCD and leg ulcers. In this study, we aim to define (1) a target of HbF that offers protection against leg ulcer development and (2) the impact of hydroxyurea therapy on leg ulcer prevalence. Our study demonstrated that in order to reduce leg ulcer incidence by one-third, a HbF > 25% is needed, a threshold not commonly reached and maintained in the adult SCD population. Importantly, leg ulcer incidence appears to be independent of HU use (p = 0.50). Our interpretation of this data is that the use of HU in a patient with SCD and leg ulcers should be guided by a careful assessment of risks and benefits of this therapeutic modality.


Assuntos
Anemia Falciforme/tratamento farmacológico , Antidrepanocíticos/uso terapêutico , Hemoglobina Fetal/análise , Hidroxiureia/uso terapêutico , Úlcera da Perna/etiologia , Adulto , Anemia Falciforme/sangue , Anemia Falciforme/complicações , Antidrepanocíticos/efeitos adversos , Feminino , Humanos , Hidroxiureia/efeitos adversos , Incidência , Úlcera da Perna/sangue , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Adulto Jovem
17.
Blood ; 139(14): 2107-2118, 2022 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-35090172

RESUMO

The benign condition hereditary persistence of fetal hemoglobin (HPFH) is known to ameliorate symptoms of co-inherited ß-hemoglobinopathies, such as sickle cell disease and ß-thalassemia. The condition is sometimes associated with point mutations in the fetal globin promoters that disrupt the binding of the repressors BCL11A or ZBTB7A/LRF, which have been extensively studied. HPFH is also associated with a range of deletions within the ß-globin locus that all reside downstream of the fetal HBG2 gene. These deletional forms of HPFH are poorly understood and are the focus of this study. Numerous different mechanisms have been proposed to explain how downstream deletions can boost the expression of the fetal globin genes, including the deletion of silencer elements, of genes encoding noncoding RNA, and bringing downstream enhancer elements into proximity with the fetal globin gene promoters. Here we systematically analyze the deletions associated with both HPFH and a related condition known as δß-thalassemia and propose a unifying mechanism. In all cases where fetal globin is upregulated, the proximal adult ß-globin (HBB) promoter is deleted. We use clustered regularly interspaced short palindromic repeats-mediated gene editing to delete or disrupt elements within the promoter and find that virtually all mutations that reduce ΗΒΒ promoter activity result in elevated fetal globin expression. These results fit with previous models where the fetal and adult globin genes compete for the distal locus control region and suggest that targeting the ΗΒΒ promoter might be explored to elevate fetal globin and reduce sickle globin expression as a treatment of ß-hemoglobinopathies.


Assuntos
Globinas , Talassemia beta , Proteínas de Transporte/genética , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/genética , Hemoglobina Fetal/genética , Hemoglobina Fetal/metabolismo , Expressão Gênica , Globinas/metabolismo , Humanos , Fatores de Transcrição/genética , Globinas beta/genética , Globinas beta/metabolismo , Talassemia beta/genética , Talassemia beta/terapia
18.
Sci Rep ; 12(1): 336, 2022 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-35013432

RESUMO

Haploinsufficiency for the erythroid-specific transcription factor KLF1 is associated with hereditary persistence of fetal hemoglobin (HPFH). Increased HbF ameliorates the symptoms of ß-hemoglobinopathies and downregulation of KLF1 activity has been proposed as a potential therapeutic strategy. However, the feasibility of this approach has been challenged by the observation that KLF1 haploinsufficient individuals with the same KLF1 variant, within the same family, display a wide range of HbF levels. This phenotypic variability is not readily explained by co-inheritance of known HbF-modulating variants in the HBB, HBS1L-MYB and/or BCL11A loci. We studied cultured erythroid progenitors obtained from Maltese individuals in which KLF1 p.K288X carriers display HbF levels ranging between 1.3 and 12.3% of total Hb. Using a combination of gene expression analysis, chromatin accessibility assays and promoter activity tests we find that variation in expression of the wildtype KLF1 allele may explain a significant part of the variability in HbF levels observed in KLF1 haploinsufficiency. Our results have general bearing on the variable penetrance of haploinsufficiency phenotypes and on conflicting interpretations of pathogenicity of variants in other transcriptional regulators such as EP300, GATA2 and RUNX1.


Assuntos
Epigênese Genética , Epigenoma , Epigenômica , Eritroblastos/metabolismo , Haploinsuficiência , Hemoglobinopatias/genética , Fatores de Transcrição Kruppel-Like/genética , Células Cultivadas , Sequenciamento de Cromatina por Imunoprecipitação , Eritroblastos/patologia , Eritropoese/genética , Hemoglobina Fetal/genética , Hemoglobina Fetal/metabolismo , Predisposição Genética para Doença , Hemoglobinopatias/sangue , Hemoglobinopatias/diagnóstico , Humanos , Fatores de Transcrição Kruppel-Like/metabolismo , Malta , Penetrância , Fenótipo , Cultura Primária de Células , RNA-Seq
19.
Blood Adv ; 6(6): 1827-1843, 2022 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-34714913

RESUMO

The transcriptional repressor BCL11A is involved in hematological malignancies, B-cell development, and fetal-to-adult hemoglobin switching. However, the molecular mechanism by which it promotes the development of myeloid leukemia remains largely unknown. We find that Bcl11a cooperates with the pseudokinase Trib1 in the development of acute myeloid leukemia (AML). Bcl11a promotes the proliferation and engraftment of Trib1-expressing AML cells in vitro and in vivo. Chromatin immunoprecipitation sequencing analysis showed that, upon DNA binding, Bcl11a is significantly associated with PU.1, an inducer of myeloid differentiation, and that Bcl11a represses several PU.1 target genes, such as Asb2, Clec5a, and Fcgr3. Asb2, as a Bcl11a target gene that modulates cytoskeleton and cell-cell interaction, plays a key role in Bcl11a-induced malignant progression. The repression of PU.1 target genes by Bcl11a is achieved by sequence-specific DNA-binding activity and recruitment of corepressors by Bcl11a. Suppression of the corepressor components HDAC and LSD1 reverses the repressive activity. Moreover, treatment of AML cells with the HDAC inhibitor pracinostat and the LSD1 inhibitor GSK2879552 resulted in growth inhibition in vitro and in vivo. High BCL11A expression is associated with worse prognosis in humans with AML. Blocking of BCL11A expression upregulates the expression of PU.1 target genes and inhibits the growth of HL-60 cells and their engraftment to the bone marrow, suggesting that BCL11A is involved in human myeloid malignancies via the suppression of PU.1 transcriptional activity.


Assuntos
Leucemia Mieloide Aguda , Adulto , DNA , Hemoglobina Fetal , Histona Desmetilases , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Lectinas Tipo C , Leucemia Mieloide Aguda/patologia , Receptores de Superfície Celular , Proteínas Repressoras
20.
Mol Biol Rep ; 49(3): 2359-2373, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34822068

RESUMO

Beta-hemoglobinopathies exhibit a heterogeneous clinical picture with varying degrees of clinical severity. Pertaining to the limited treatment options available, where blood transfusion still remains the commonest mode of treatment, pharmacological induction of fetal hemoglobin (HbF) has been a lucrative therapeutic intervention. Till now more than 70 different HbF inducers have been identified. The practical usage of many pharmacological drugs has been limited due to safety concerns. Natural compounds, like Resveratrol, Ripamycin and Bergaptene, with limited cytotoxicity and high efficacy have started capturing the attention of researchers. In this review, we have summarized pharmacological drugs and bioactive compounds isolated from natural sources that have been shown to increase HbF significantly. It primarily discusses recently identified synthetic and natural compounds, their mechanism of action, and their suitable screening platforms, including high throughput drug screening technology and biosensors. It also delves into the topic of combinatorial therapy and drug repurposing for HbF induction. Overall, we aim to provide insights into where we stand in HbF induction strategies for treating ß-hemoglobinopathies.


Assuntos
Produtos Biológicos , Hemoglobinopatias , Produtos Biológicos/farmacologia , Produtos Biológicos/uso terapêutico , Hemoglobina Fetal , Hemoglobinopatias/tratamento farmacológico , Humanos
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