scholarly journals Epigenomic analysis of KLF1 haploinsufficiency in primary human erythroblasts

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Steven Heshusius ◽  
Laura Grech ◽  
Nynke Gillemans ◽  
Rutger W. W. Brouwer ◽  
Xander T. den Dekker ◽  
...  
Keyword(s):  
Gene Expression Analysis ◽  
Therapeutic Strategy ◽  
Phenotypic Variability ◽  
Fetal Hemoglobin ◽  
Transcriptional Regulators ◽  
Chromatin Accessibility ◽  
Erythroid Progenitors ◽  
Wide Range ◽  
Hereditary Persistence ◽  
Variable Penetrance

AbstractHaploinsufficiency for the erythroid-specific transcription factor KLF1 is associated with hereditary persistence of fetal hemoglobin (HPFH). Increased HbF ameliorates the symptoms of β-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.

scholarly journals Molecular analysis of the erythroid phenotype of a patient with BCL11A haploinsufficiency

2021 ◽  
Vol 5 (9) ◽  
pp. 2339-2349
Author(s):  
Marja W. Wessels ◽  
Marjon H. Cnossen ◽  
Thamar B. van Dijk ◽  
Nynke Gillemans ◽  
K. L. Juliëtte Schmidt ◽  
...  
Keyword(s):  
Gene Expression ◽  
De Novo ◽  
Fetal Hemoglobin ◽  
Chromatin Accessibility ◽  
Neuronal System ◽  
Globin Genes ◽  
Erythroid Progenitors ◽  
Genome Wide ◽  
Localization Signal ◽  
Significant Expression

Abstract The BCL11A gene encodes a transcriptional repressor with essential functions in multiple tissues during human development. Haploinsufficiency for BCL11A causes Dias-Logan syndrome (OMIM 617101), an intellectual developmental disorder with hereditary persistence of fetal hemoglobin (HPFH). Due to the severe phenotype, disease-causing variants in BCL11A occur de novo. We describe a patient with a de novo heterozygous variant, c.1453G>T, in the BCL11A gene, resulting in truncation of the BCL11A-XL protein (p.Glu485X). The truncated protein lacks the 3 C-terminal DNA-binding zinc fingers and the nuclear localization signal, rendering it inactive. The patient displayed high fetal hemoglobin (HbF) levels (12.1-18.7% of total hemoglobin), in contrast to the parents who had HbF levels of 0.3%. We used cultures of patient-derived erythroid progenitors to determine changes in gene expression and chromatin accessibility. In addition, we investigated DNA methylation of the promoters of the γ-globin genes HBG1 and HBG2. HUDEP1 and HUDEP2 cells were used as models for fetal and adult human erythropoiesis, respectively. Similar to HUDEP1 cells, the patient’s cells displayed Assay for Transposase-Accessible Chromatin (ATAC) peaks at the HBG1/2 promoters and significant expression of HBG1/2 genes. In contrast, HBG1/2 promoter methylation and genome-wide gene expression profiling were consistent with normal adult erythropoiesis. We conclude that HPFH is the major erythroid phenotype of constitutive BCL11A haploinsufficiency. Given the essential functions of BCL11A in other hematopoietic lineages and the neuronal system, erythroid-specific targeting of the BCL11A gene has been proposed for reactivation of γ-globin expression in β-hemoglobinopathy patients. Our data strongly support this approach.

KLF1 Dependent Pathways In Developmental Globin Gene Switching

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 5162-5162
Author(s):  
Alexander E. Felice
Keyword(s):  
Conflicts Of Interest ◽  
Expression Profiles ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Erythroid Progenitors ◽  
Gamma Globin ◽  
Genome Wide ◽  
Hereditary Persistence ◽  
Informative Family ◽  
Gene Switching

Abstract Abstract 5162 We provide additional data on members of the family from Malta with Hereditary Persistence of Fetal Hemoglobin (HPFH) due to KLF1 haplo-insufficiency. The data indicated a possible role of additional loci in the pathway of globin gene control. We showed that KLF1 functions as a master regulator of erythropoiesis and developmental globin gene switching (Borg et al., Nature Genetics doi: 10. 1038/ng.630, 2010), at least partly through BCL11A. Given the phenoytpes of the HPFH heterozygotes, the truncating KLF1 p.K288X was best described as a dominant mutation with variable penetrance; most likely due to interplay with other regulatory factors that we have been seeking. Genome-wide association analysis, in the context of genome-wide expression profiles from cultured Human Erythroid Progenitors (HEPs) of critically informative family members, revealed additional loci of potential interest. The effect of the Hb F inducer Hydroxyurea on the gamma globin profiles of the KLF1- (p.K288X) HPFH HEPs was enhanced compared to the wild type, and 74 loci were differentially expressed. It is anticipated that extensive re-sequencing of these new targets may reveal the extent of the molecular pathways under control of KLF1 in erythropoiesis and globin gene switching, and in particular those that may be targeted for therapeutics in patients. Disclosures: No relevant conflicts of interest to declare.

scholarly journals δ-Aminolevulinate induces fetal hemoglobin expression by enhancing cellular heme biosynthesis

2019 ◽  
Vol 244 (14) ◽  
pp. 1220-1232
Author(s):  
Li Liu ◽  
Xingguo Zhu ◽  
Alexander Yu ◽  
Christina M Ward ◽  
Betty S Pace
Keyword(s):  
Therapeutic Strategy ◽  
Clinical Symptoms ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Heme Biosynthesis ◽  
Erythroid Cell ◽  
Nuclear Factor ◽  
Cell Disease ◽  
Erythroid Progenitors ◽  
Novel Therapeutic

Sickle cell disease (SCD) and β-thalassemia are inherited blood disorders caused by genetic defects in the β-globin gene on chromosome 11, producing severe disease in people worldwide. Induction of fetal hemoglobin consisting of two α-globin and two γ-globin chains ameliorates the clinical symptoms of both disorders. In the present study, we investigated the ability of δ-aminolevulinate (ALA), the heme precursor, to activate γ-globin gene expression as well as its effects on cellular functions in erythroid cell systems. We demonstrated that ALA induced γ-globin expression at both the transcriptional and protein levels in the KU812 erythroid cell line. Using inhibitors targeting two enzymes in the heme biosynthesis pathway, we showed that cellular heme biosynthesis was involved in ALA-mediated γ-globin activation. Moreover, the transcription factor NRF2 (nuclear factor [erythroid-derived 2]-like 2), a critical regulator of the cellular antioxidant response, was activated by ALA and contributed to mechanisms of γ-globin activation; ALA did not affect cell proliferation and was not toxic to cells. Subsequent studies demonstrated ALA-induced γ-globin activation in erythroid progenitors generated from normal human CD34+ stem cells. These data support future study to explore the potential of stimulating intracellular heme biosynthesis by ALA or similar compounds as a novel therapeutic strategy for treating SCD and β-thalassemia. Impact statement Inherited mutations in the β-globin-like genes result in the most common forms of genetic blood disease including sickle cell disease (SCD) and β-thalassemia worldwide. Therefore, effective inexpensive therapies that can be distributed widely are highly desirable. Currently, drug-mediated fetal hemoglobin (HbF) induction can ameliorate clinical symptoms of SCD and β-thalassemia and is the most effective strategy for developing new therapeutic options. In the current study, we confirmed that δ-Aminolevulinate (ALA), the precursor of heme, induces γ-globin expression at both the transcriptional and translational levels in primary human erythroid progenitors. Moreover, the results indicate activation of the transcription factor NRF2 (nuclear factor (erythroid-derived 2)-like 2) by ALA to enhance HbF expression. These data support future study to explore the potential of stimulating intracellular heme biosynthesis by ALA or similar compounds as a novel therapeutic strategy for treating SCD and β-thalassemia.

Gene Expression Analysis of the Brazilian Type of Hereditary Persistence of Fetal Hemoglobin: Identification of Genes that Could be Related to γ-Globin Activation

Hemoglobin ◽  
2013 ◽  
Vol 37 (6) ◽  
pp. 516-535 ◽  
Author(s):  
Fernanda Marconi Roversi ◽  
Anderson Ferreira da Cunha ◽  
Ana Flávia Brugnerotto ◽  
Marcelo Falsarella Carazzolle ◽  
Dulcinéia Martins de Albuquerque ◽  
...  
Keyword(s):  
Gene Expression ◽  
Expression Analysis ◽  
Gene Expression Analysis ◽  
Fetal Hemoglobin ◽  
Hereditary Persistence

Formation and composition of training flax collection

2020 ◽  
pp. 61-71
Author(s):  
L.M. Kryvosheieva ◽  
V.I. Chuchvaha ◽  
N.M. Kandyba
Keyword(s):  
Plant Breeding ◽  
Gene Pool ◽  
Phenotypic Variability ◽  
Plant Genetic Resources ◽  
Field Measurements ◽  
Educational Process ◽  
Educational Institutions ◽  
Economic Traits ◽  
Wide Range ◽  
History Of

Aim. Based on the results of multi-year research into the flax gene pool, to form a flax training collection to provide breeding scientific organizations and educational institutions with collection samples as well as with information about the bast crop gene pool. Results and Discussion. The studies were conducted in the crop rotation fields for breeding and seed production of the Institute of Bast Crops of the NAAS (Hlukhiv, Sumska Oblast) in 1992-2018. The field measurements and laboratory analyses were carried out in accordance with conventional methods of field and laboratory studies of collection flax samples.The article presents the results on the formation of a training collection of flax at the Institute of Bast Crops of the NAAS, which has 117 accessions (11 botanical species and three varieties) from 22 countries. In addition to species diversity, the collection includes accessions with different levels of expression of valuable economic and biological characteristics. It also includes accessions selected by phenotypic variability of individual characters or their combinations. The multi-year research into the flax collection accessions resulted in identification of sources of highly-expressed valuable economic traits, which are of interest for the plant breeding course. The history of flax breeding in Ukraine is shown, where breeding varieties that are most widespread or were significant breeding achievements in solving certain problems, are presented. The collection can be used as a visual aid for the plant breeding course in educational programs; in addition, it can provide starting material for scientific and educational institutions. The collection is registered with the National Center for Plant Genetic Resources of Ukraine (certificate No. 00273 dated 04/11/2019). Conclusions. The studies of accessions from the national flax collection allowed us to build up a training collection and register it with the NCPGRU. The collection represents a wide range of biological and economic features of the gene pool of this crop. The collection can be used in the educational process of educational agricultural and biological institutions. The multi-year research into the national flax collection resulted in identification of sources of highly-expressed valuable economic traits, which are of interest to the plant breeding course. The history of flax breeding in Ukraine got covered, and breeding varieties that are most widespread or were significant breeding achievements in solving certain problems are presented.

scholarly journals Anti-Biofilm Molecules Targeting Functional Amyloids

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 795
Author(s):  
Leticia Matilla-Cuenca ◽  
Alejandro Toledo-Arana ◽  
Jaione Valle
Keyword(s):  
Biofilm Formation ◽  
Therapeutic Strategy ◽  
Research Area ◽  
Therapeutic Strategies ◽  
Structural Components ◽  
Significant Issue ◽  
Wide Range ◽  
Effective Therapeutic Strategy ◽  
Functional Amyloids ◽  
Biofilm Matrix

The choice of an effective therapeutic strategy in the treatment of biofilm-related infections is a significant issue. Amyloids, which have been historically related to human diseases, are now considered to be prevailing structural components of the biofilm matrix in a wide range of bacteria. This assumption creates the potential for an exciting research area, in which functional amyloids are considered to be attractive targets for drug development to dissemble biofilm structures. The present review describes the best-characterized bacterial functional amyloids and focuses on anti-biofilm agents that target intrinsic and facultative amyloids. This study provides a better understanding of the different modes of actions of the anti-amyloid molecules to inhibit biofilm formation. This information can be further exploited to improve the therapeutic strategies to combat biofilm-related infections.

scholarly journals Cortical Excitability across the ALS Clinical Motor Phenotypes

2021 ◽  
Vol 11 (6) ◽  
pp. 715
Author(s):  
Thanuja Dharmadasa
Keyword(s):  
Motor Cortex ◽  
Cortical Excitability ◽  
Phenotypic Variability ◽  
Specific Treatment ◽  
Underlying Disease ◽  
Selective Vulnerability ◽  
Clinical Feature ◽  
Cortical Hyperexcitability ◽  
Wide Range

Amyotrophic lateral sclerosis (ALS) is characterized by its marked clinical heterogeneity. Although the coexistence of upper and lower motor neuron signs is a common clinical feature for most patients, there is a wide range of atypical motor presentations and clinical trajectories, implying a heterogeneity of underlying pathogenic mechanisms. Corticomotoneuronal dysfunction is increasingly postulated as the harbinger of clinical disease, and neurophysiological exploration of the motor cortex in vivo using transcranial magnetic stimulation (TMS) has suggested that motor cortical hyperexcitability may be a critical pathogenic factor linked to clinical features and survival. Region-specific selective vulnerability at the level of the motor cortex may drive the observed differences of clinical presentation across the ALS motor phenotypes, and thus, further understanding of phenotypic variability in relation to cortical dysfunction may serve as an important guide to underlying disease mechanisms. This review article analyses the cortical excitability profiles across the clinical motor phenotypes, as assessed using TMS, and explores this relationship to clinical patterns and survival. This understanding will remain essential to unravelling central disease pathophysiology and for the development of specific treatment targets across the ALS clinical motor phenotypes.

scholarly journals Fetal calf serum contains activities that induce fetal hemoglobin in adult erythroid cell cultures

Blood ◽  
1990 ◽  
Vol 75 (9) ◽  
pp. 1862-1869 ◽  
Author(s):  
P Constantoulakis ◽  
B Nakamoto ◽  
T Papayannopoulou ◽  
G Stamatoyannopoulos
Keyword(s):  
Cell Cultures ◽  
Fetal Calf Serum ◽  
Calf Serum ◽  
Fetal Hemoglobin ◽  
Erythroid Cell ◽  
Erythroid Progenitors ◽  
Globin Mrna ◽  
Erythroid Progenitor ◽  
Fetal Sheep ◽  
Gamma Globin

Abstract Cultures of peripheral blood or bone marrow erythroid progenitors display stimulated production of fetal hemoglobin. We investigated whether this stimulation is due to factors contained in the sera of the culture medium. Comparisons of gamma/gamma + beta biosynthetic ratios in erythroid colonies grown in fetal calf serum (FCS) or in charcoal treated FCS (C-FCS) showed that FCS-grown cells had significantly higher gamma/gamma + beta ratios. This increase in globin chain biosynthesis was reflected by an increase in relative amounts of steady- state gamma-globin mRNA. In contrast to its effect on adult cells, FCS failed to influence gamma-chain synthesis in fetal burst forming units- erythroid (BFU-E) colonies. There was a high correlation of gamma- globin expression in paired cultures done with C-FCS or fetal sheep serum. Dose-response experiments showed that the induction of gamma- globin expression is dependent on the concentration of FCS. These results indicate that FCS contains an activity that induces gamma- globin expression in adult erythroid progenitor cell cultures.

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