Gene Expression In Blood From an Individual With β-Thalassemia: an RNA Sequence Analysis
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ABSTRACT: Background: The thalassemias are highly diverse at both the molecular and clinical levels. Many of the HBB mutations that result in β-thalassemia are missense mutations in the coding region of the β-globin gene, but a few cause alternative splicing, and interfere with normal processing of the β-globin transcripts. Transcriptome profiling in individuals affected with β-thalassemia, especially in individuals who carry novel mutations in the HBB, may improve our understanding of the heterogeneity and molecular mechanisms of the disease. Methods: Members of a family with a daughter affected with thalassemia intermedia, although her mother was not clinically affected, were examined for physical characteristics, hematological parameters and β-globin gene sequences. We also characterized genome-wide gene expression in the family using RT-qPCR and high-throughput RNA-sequencing mRNA expression profiling of blood. Results: Clinical findings, hematological indices, DNA and RNA sequence analysis of individuals with β-thalassemia, including the description of a novel mutation in the β-globin gene, which introduces a cryptic donor splice site. More than 300 genes are differentially expressed in β-thalassemic blood with many of the DEGs involved in pathways relevant to the clinical management of β-thalassemia. β-thalassemia shows important similarities and differences with sickle cell disease at the transcriptome level. Conclusions: We described the down-regulation of the β-globin gene in β-thalassemia by RNA-sequencing analysis using a sample from an affected individual and her mother, who have a novel mutation in the HBB that creates a cryptic donor splice site. The daughter has a typical β-thalassemia allele as well, and an unexpectedly severe phenotype. The DEGs are enriched in pathways that are directly or indirectly related to β-thalassemia such as hemopoiesis, heme biosynthesis, response to oxidative stress, inflammatory responses, immune responses, control of circadian rhythm, apoptosis, and other cellular activities. We compare our findings with published results of RNA-Sequencing analysis of sickle cell disease (SCD) and erythroblasts from a KLF1-null neonate with hydrops fetalis, and recognize similarities and differences in their transcriptional expression patterns.
Project description:β-hemoglobinopathies are the most common genetic disorders worldwide. In sickle cell disease (SCD) a single mutation (E6V) in the b-globin (HBB) gene results in dysfunctional hemoglobin protein, while in β-thalassemia, over 300 mutations distributed across the HBB gene are known to reduce the production of β-globin and cause severe anemia. A genetic engineering approach that replaces the whole HBB gene is an ideal strategy to rescue HBB expression for most genotypes but is technically challenging as the insert cannot be homologous to the endogenous gene and codon-optimized, intron-less sequences may not reconstitute adequate HBB levels. Here, we developed a novel approach for a “one-size-fits-all" HBB gene repair strategy using CRISPR-Cas9 which successfully addresses these problems. First, our DNA donor design avoids sequence homology through a diverged HBB coding sequence and second, incorporates heterologous introns from the fetal g-globin gene, further reducing homology to endogenous HBB while mimicking its intron composition. Screening DNA donors with various heterologous globin introns, polyadenylation signals and truncated sequences, identified a heterologous intron DNA donor that highly expresses β-globin and rescued β-globin expression in two in vitro hemoglobinopathy models in hematopoietic stem and progenitor cells (HSPCs). Furthermore, healthy donor HSPCs modified with this HBB gene replacement approach showed successful engraftment in immunodeficient mice at 16 weeks. In summary, we developed a universal HBB gene replacement strategy that results in physiological b-globin production, offering a potential differentiated approach for treating patients with β-thalassemia, SCD or compound heterozygous individuals.
Project description:beta-Thalassemia is a prevalent anemia caused by mutations in the HBB (beta-globin) gene. We show that the severity of beta-thalassemia in the frequently studied Hbb(th3/+) mouse model is influenced by ancestral beta-globin gene (Hbb) haplotypes that differ in common strains.
Project description:β-Thalassemia is a prevalent anemia caused by mutations in the HBB (β-globin) gene. We show that the severity of β-thalassemia in the frequently studied Hbbth3/+ mouse model is influenced by ancestral β-globin gene (Hbb) haplotypes that differ in common strains.
Project description:Sickle cell disease and Beta-thalassemia represent hemoglobinopathies arising from dysfunctional or under produced beta-globin chains, respectively. In both diseases, red blood cell injury and anemia are the impetus for end organ injury. Because persistent erythrophagocytosis is a hallmark of these genetic maladies it is critical to understand how macrophage phenotype polarizations in tissue compartments can inform on disease progression. Murine models of sickle cell disease and Beta-thalassemia allow for a basic understanding of mechanisms and provide for translation to human disease. A multi-omics approach to understanding macrophage metabolism and protein changes in two murine models of beta-globinopathy was performed on peripheral blood mononuclear cells as well as spleen and liver macrophages isolated from Berkley sickle cell disease (Berk-ss) and heterozygous B1/B2 globin gene deletion (Hbbth3/+) mice. Results from these experiments revealed the metabolome and proteome of macrophages are polarized to a distinct phenotype in Berk-ss and Hbbth3/+ compared each other and their common background mice (C57BL6/J). Further, spleen and liver macrophages revealed distinct disease specific phenotypes, suggesting macrophages become differentially polarized and reprogrammed within tissue compartments. We conclude that tissue recruitment, polarization, metabolic and proteomic reprogramming of macrophages in Berk-ss and Hbb mice may be relevant to disease to progression in other tissue.
Project description:Delta-Beta thalassemia is an unusual variant of thalassemia caused by large deletions in the β globin gene cluster involving δ- and β-globin genes. The mutations are characterized by high fetal hemoglobin with significant phenotypic diversity. Routinely used diagnostic tests targeting point mutations and small insertions, deletions of the β-globin gene are not suitable for detection of large deletion mutations. This is overcome by either direct globin chain synthesis analysis or beta-cluster gene analysis using different methods. In the current study, we use direct globin chain analysis to diagnose a family with δβ-thalassemia using high resolution mass spectrometry.
Project description:β-thalassemia major can be caused by homozygous mutations of the HBB gene, most of the cases are inherited from parents who both have β-thalassemia minor. Herein, we show that a mosaic paternal uniparental isodisomy of chromosome 11p14.3-15.5 is associated with β-thalassemia major in a patient with β-thalassemia minor-that evolved to β-thalassemia major. From this case, we suggest that analysis of HBB gene for non-hematopoietic tissues should be performed in late-onset β-thalassemia major patients. Keywords: genomic
Project description:Array-CGH used to characterize HBB deletions causing beta thalassemia and HPFH Two-color experiment comparing thalssemia/HPFH subjects with normal DNA
Project description:The benign condition Hereditary Persistence of Foetal Haemoglobin (HPFH) is known to ameliorate symptoms when co-inherited with beta-haemoglobinopathies, such as sickle cell disease and beta-thalassaemia. The condition is sometimes associated with point mutations in the foetal 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 beta-globin locus that all reside downstream of the foetal 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 foetal globin genes, including the deletion of silencer elements, of genes encoding non-coding RNA, and bringing downstream enhancer elements into proximity with the foetal globin gene promoters. Here we systematically analyse the deletions associated with both HPFH and a related condition known as beta-thalassaemia and propose a unifying mechanism. In all cases where foetal globin is up-regulated, the proximal adult beta-globin (HBB) promoter is deleted. We use CRISPR gene editing to delete or disrupt elements within the promoter and find that virtually all mutations that reduce promoter activity, result in elevated foetal globin expression. These results fit with previous models where the foetal and adult globin genes compete for the distal Locus Control Region and suggest that targeting the promoter might be explored to elevate foetal globin and reduce sickle globin expression as a treatment for beta-haemoglobinopathies.
Project description:Sickle cell disease and Beta-thalassemia represent hemoglobinopathies arising from dysfunctional or under produced beta-globin chains, respectively. In both diseases, red blood cell injury and anemia are the impetus for end organ injury. Because persistent erythrophagocytosis is a hallmark of these genetic maladies it is critical to understand how macrophage phenotype polarizations in tissue compartments can inform on disease progression. Murine models of sickle cell disease and Beta-thalassemia allow for a basic understanding of mechanisms and provide for translation to human disease. A multi-omics approach to understanding macrophage metabolism and protein changes in two murine models of beta-globinopathy was performed on peripheral blood mononuclear cells as well as spleen and liver macrophages isolated from Berkley sickle cell disease (Berk-ss) and heterozygous B1/B2 globin gene deletion (Hbbth3/+) mice. Results from these experiments revealed the metabolome and proteome of macrophages are polarized to a distinct phenotype in Berk-ss and Hbbth3/+ compared each other and their common background mice (C57BL6/J). Further, spleen and liver macrophages revealed distinct disease specific phenotypes, suggesting macrophages become differentially polarized and reprogrammed within tissue compartments. We conclude that tissue recruitment, polarization, metabolic and proteomic reprogramming of macrophages in Berk-ss and Hbb mice may be relevant to disease to progression in other tissue.