The correction of mutant beta-globin genes has long been a therapeutic goal for patients with beta-thalassemia or hemoglobinopathies. The use of homologous recombination (HR) to achieve this goal is an attractive approach because it eliminates the need to include regulatory sequences in the therapeutic construct, and it eliminates mutagenesis induced by random integration. However, HR is a very...

Changes in gamma-globin gene methylation accompany the fetal to adult globin switch in man. Using somatic cell hybrids made by fusing mouse erythroleukemia and human fetal erythroid cells, we asked whether methylation is a cause or a consequence of gamma-gene inactivation during development. These hybrids initially express human gamma-globin but switch with time in culture to adult globin gene ...

Chromatin in the 5' flanking region of the transcriptionally active chicken adult beta(beta A) globin gene is hypersensitive to nuclease digestion. When plasmids carrying this gene are combined with histones in the presence of extracts from 9-day-old chicken erythrocyte nuclei, the resultant complex displays hypersensitive behavior in the same region. No such behavior is observed with extracts ...

To study epigenetic regulation of the human beta-globin locus during hematopoiesis, we investigated patterns of histone modification and chromatin accessibility along this locus in hematopoietic progenitor cells (HPCs) derived from both humans and transgenic mice. We demonstrate that the developmentally related activation of human beta-like globin genes in humans and transgenic mice HPCs is pre...

Posttranslational modifications of transcription factors provide alternate protein interaction platforms that lead to varied downstream effects. We have investigated how the acetylation of EKLF plays a role in its ability to alter the beta-like globin locus chromatin structure and activate transcription of the adult beta-globin gene. By establishing an EKLF-null erythroid line whose closed beta...

The base composition around a recently detected deletion in the human beta-globin gene was determined by direct DNA sequencing of an enzymatically amplified DNA segment. The deletion removes 290 base pairs (bp), including the entire exon 1 and the mRNA cap site. In the vicinity of the deletion endpoints, the normal beta-globin gene contains direct and inverted repeats which may have taken part ...

As initial human gene therapy trials for beta-thalassemia are contemplated, 2 critical questions important to trial design and planning have emerged. First, what proportion of genetically corrected hematopoietic stem cells (HSCs) will be needed to achieve a therapeutic benefit? Second, what level of expression of a transferred globin gene will be required to improve beta-thalassemic erythropoie...

Mice lacking the erythroid Kruppel-like factor (EKLF) die in utero at embryonic day 15 (E15) from severe anemia. EKLF(-/-) embryos display a marked deficit in beta-globin gene expression. To test whether beta-globin deficiency was solely responsible for the anemia and intrauterine death, we corrected the globin chain imbalance in EKLF(-/-) embryos by breeding with a strain of mice that express ...

Normal expression of the human beta-globin domain genes is dependent on at least three types of regulatory elements located within the beta-globin domain: the locus control region (LCR), globin enhancer elements (3'beta and 3'Agamma), and the individual globin gene promoter and upstream regions. It has been postulated that regulation occurs through physical interactions between factors bound to...

Characterization of the mechanism(s) of action of trans-acting factors in higher eukaryotes requires the establishment of cellular models that test their function at endogenous target gene regulatory elements. Erythroid Krüppel-like factor (EKLF) is essential for beta-globin gene transcription. To elucidate the in vivo determinants leading to transcription of the adult beta-globin gene, functio...