Integration And Expression Of The Human β-Globin Gene With Single Or Multiple DNase Ⅰ Hypersensitive Site Core Fragments From Locus Control Region Following Viral Vectors Mediated Gene Transfer Into Mouse Erythroid Cells

The genes encoding subunits of hemoglobin exist at distinct loci, the a-globin gene cluster and the β-globin gene cluster. The expression of functional genes of both clusters presents the characteristics of erythroid-specificity, developmental stage-specificity and final products-balance. The imbalance of expression of both clusters causes thalassemia. The decrease or absence of β polypeptide synthesis in adult erythroid cells results in β-thalassemia, one of the most common human genetic diseases. Current treatments for P-thalassemia are unsatisfactory.Gene therapy for P-thalassemia is expected to cure or have a long-term relief of clinic syndromes of β-thalassemia via the delivery and integration of human β-globin gene to hematopoietic stem cells(HSCs) from patients for the achievement of a suitable expression level of the P-globin gene in adult erythroid cells with an aim of restoring the quantitative balance between both globin polypeptides. HSCs, the target cells for P-thalassemia gene therapy, comprise a rare proportion of nucleic blood cells. Therefore, the viral-mediated efficient gene transfer has to be utilized for the introduction of the P-globin gene to HSCs. Retroviral(RV) and adeno-associated viral (AAV) vectors have become vehicles suitable for β-globin gene transfer.The correct expression of β-like globin genes depends on three regulatory elements: erythroid specific and general trans-acting factors , proximal in-cis elements( promoters) and the distal in-cis element —locus control region (LCR). LCR consists of four erythroid specific, developmental stage-stable DNase I hypersensitive sites(HS1-HS4).Each HS contains a 200-400bp core fragment which distributes binding sites for erythroid specific and general trans-acting factors and is essential for each HS activities. LCR confers the high level,...