• Tuan Lo, Dorothy (PI)

Project: Research project

Project Details


Gene therapy for the thalessemia syndromes requires that the
introduced globin gene mimic the function of an in situ normal
globin gene both in tissue specificity and efficiency of
transcription. DNA mediated gene transfer experiments have
shown that the human beta-globin gene with its immediate 5' and
3' flanking sequences can be expressed in a tissue and
developmental-stage specific manner. Yet high level
transcription of such a gene may require sequence elements not
residing in the globin structural gene and its immediate flanking
sequences. Comparison of the extents of DNA deletions in the
Dutch and English gamma delta beta-thalassemias suggests the
possible existence of regulatory sequences upstream of the
embryonic epsilon-globin gene, which can regulate the expression
of the far downstream beta-globin gene. A segment of DNA at
10 Kb 5' of the epsilon-globin gene has been shown to display
erythroid specific enhancer activity. It is therefore possible that
transcriptional activation of the beta-globin gene may involve at
least two synergistic activation steps, mediated respectively by
this distant enhancer sequence, and by sequences much closer to
the beta-globin gene. In DNA mediated gene transfer
experiments, the presence of this enhancer element, in cis to the
beta-globin or a test gene, may thus significantly enhance the
transcriptional efficiency of such a gene in erythroid hosts. This
proposal attempts to address this possibility. The enhancer
element with other probable regulatory sequences will be spliced
with a beta-globin or a test gene into enhancerless plasmids or
into an enhancerless retroviral vector, which will subsequently be
transiently or stably introduced into appropriate cell lines or into
mouse bone marrow cells. The transcriptional efficiency of the
test gene will be compared to that of the endogenous alpha-or
beta-globin gene of the erythroid host cells. Identification of an erythroid specific, globin gene enhancer,
understanding the molecular mechanism of its action on the beta-
like globin genes, and its possible role in the coordinated
activation of the alpha- and beta-like globin genes located on
separate chromosomes, may all aid in elucidating the regulatory
mechanism of the human beta-globin gene and thus in bringing
gene therapy for the beta-thalassemias significant steps closer to
Effective start/end date7/1/882/28/97


  • National Institutes of Health


  • Medicine(all)


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