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:The EKLF-GATA1 fusion proteins enhances δ-globin expression through interaction with the GATA1-binding motif of the δ-globin promoter. The goal this study is to find if the fusion proteins could have a different pattern of chromatin occupation from GATA1. The alignment of ChIP-Seq peaks revealed that the binding peaks of EKLF-GATA1 fusion proteins at the β-globin cluster overlapped substantially with those of GATA1 (A), suggesting that these proteins may associate with chromatin in a similar configuration within the β-globin locus and LCR. Global analysis of EKLF-GATA1 and GATA1 ChIP-seq data sets also revealed a significant number of shared sites on the genomic scale.
Project description:Human embryonic stem cells provide an alternative to using human embryos for studying developmentally regulated gene expression. The co-expression of high levels of embryonic epsilon and fetal gamma globin by the hESC-derived erythroblasts allows the interrogation of epsilon globin regulation at the transcriptional and epigenetic level which could only be attained previously by studying cell lines or transgenic mice. In this study, we compared the histone modifications across the beta globin locus of the undifferentiated hESCs and hESC-, FL-, and mobilized PB CD34+ cells-derived erythroblasts, which have distinct globin expression patterns corresponding to their developmental stages. We demonstrated that the histone codes employed by the beta globin locus are conserved throughout development. Furthermore, in spite of the close proximity of the epsilon globin promoter, as compared to the gamma or beta globin promoter, with the LCR, a chromatin loop was also formed between the LCR and the active epsilon globin promoter, similar to the loop that forms between the gamma or beta globin promoters and the LCR, in contrary to the previously proposed tracking mechanism. Human embryonic stem cells, hESC-, FL-, and PB derived erythroblasts were studied. The enrichment of H3K4me3 and AcH3 acrossed the beta globin locus was studied using ChIP-seq.
Project description:We have identified putative repressor region (PRR) to exon-1 of β-globin (βE1) in the β-globin cluster as a core region in alll the HPFH deletions that activates fetal hemoglobin and silences adult hemoglobin. To test the impact of PRR-βE1 gene editing in β-globin cluster configuration, we employed Circular chromosome conformation capture (4C) analysis to assess the LCR interaction to the gamma-globin promoter. Using HBG2 promoter as viewpoint,4C analysis showed an increased interaction of HBG promoter to the hypersensitive (HS) sites of the LCR in HUDEP-2 clones harbouring PRR-βE1 biallelic deletions compared to control HUDEP-2 cells. Link for 4C output files Mendeley - Venkatesan, Vigneshwaran (2022), “4C data set ”, Mendeley Data, V1, doi: 10.17632/cz3thnr9kf.1
Project description:Human fetal γ-globin gene is developmentally silenced around the birth, and reactivation of γ-globin gene in adulthood sheds new light on ameliorating symptoms of hemoglobin disorders, such as sickle cell disease (SCD) and β-thalassemias. However, the precise regulation process of γ-globin remains incompletely understood. Here, we found that a new protein directly interacted with SOX6 and exerted a significant repression effect on the expression of γ-globin gene in erythroid cells. Further studies have demonstrated that it bound directly to γ-globin gene promoter via octamer binding motif, which in turn suppressed the transcriptional activity of γ-globin gene promoter. Thus, these data indicate that this new protein acts as a novel transcriptional repressor in the regulation of γ-globin gene expression through direct promoter binding, implying a potential alternative therapeutic target for the treatment of SCD and β-thalassemias.
Project description:We determined the locus-specific long-range chromatin interactions associated with the human beta-globin gene cluster in BCL11A wild-type and knockout HUDEP-2 cells
Project description:We have identified putative repressor region (PRR) to exon-1 of β-globin (βE1) in the β-globin cluster as a core region in alll the HPFH deletions that activates fetal hemoglobin and silences adult hemoglobin. Here we charactised the transcriptome of the erythroblasts derived from PRR-βE1 gene edited HSPCs. Transcriptome analysis showed an increased expression of HBG, HBBP1 and decreased expression of HBB transcripts compared to control.
Project description:It is generally believed that human mature erythrocytes do not possess functional ribosomes, and therefore cannot synthesize proteins. However, this dogma is not consistent with the long life of mature erythrocytes in the circulatory system. The mass-spectrometry analysis was done on highly pure preparation of human mature erythrocytes to identify the proteome. Results of the analysis show that there is no contamination from other cell types. We also demonstrate translation by polysome profiling, metabolic labelling and RiboPuromycylation. RNA-seq and quantitative RT-PCR assays revealed that HBA (alpha globin) and HBB (beta globin) transcripts are selectively translated. RNA-seq and translatome analyses revealed the presence of all necessary translation factors and aminoacyl tRNA synthetases.
Project description:Analyses of mutations within the a-globin cluster which downregulate a-globin expression and cause a-thalassaemia provide the basis for genetic counselling and pre-natal diagnosis of this common form of anemia. Understanding the mechanisms by which such mutations cause a-thalassemia has established many of the principles by which mammalian genes are regulated and how this goes awry in human genetic disease. ATAC-Seq and NG Capture-C data from an individual (NSE) with a unique a-globin genotype involving a deletion of the main alpha-globin enhancer on one allele and the --/SEA mutation on the other help to address how the human a-globin cluster is normally regulated.
Project description:In genomes of modern fish and amphibia α- and β- globin genes are grouped at a single locus that may resemble the ancestral one and is syntenic to α-globin locus of modern warm-blooded vertebrates. In Danio rerio, the major locus of α/β globin genes comprises two subclusters, one of them harboring genes expressed in adult and the other – genes expressed in embryonic and larval erythrocytes. The results of our previous study suggested that the adult subcluster of this locus has evolved into α-globin gene domain of vertebrate animals. Here we studied how adult and embryo-larval genes of Danio rerio major globin gene locus are repressed in fibroblasts. The results obtained suggest that that at least some of the globin genes present within the adult subcluster are repressed by Polycomb similarly to human α-globin genes. Furthermore, within two α/β gene pairs repression of α-type and β-type genes appears to be mediated by different mechanisms as increasing the level of histone acetylation can activate transcription of only β-type genes.