The DMD gene promoter: a potential role in gene therapy.
The studies I've outlined here are obviously at a preliminary stage but do offer some insight into the complexity of DMD gene regulation and do suggest that an understanding of this regulation may have some potential benefit in gene therapy for this disease. The high promoter activity found was unexpected and suggests that in vivo the activity of the endogenous gene may be repressed by elements not present within this region. Of course, other interpretations are possible. The transcripts in vivo may turn over very quickly, or the very large size of the DMD gene may in itself limit the rate of transcription. Alternatively, the gene may be actively transcribed only during the early stages of differentiation. A more detailed analysis of developmental expression and of DNA sequences surrounding exon one is required to address these alternatives, but the possibility for augmenting dystrophin synthesis during myoblast therapy clearly exists. The high level of activity and the tissue and developmental specificity exhibited by the HP2 construct suggest this may be the promoter of choice in future gene therapy experiments. The high degree of specificity shown by this promoter would reduce the need to target gene constructs to muscle cells and would reduce the potential complications of uncontrolled gene expression. Of course, before any of these benefits could be realized much more work must be done both in analysing DMD gene expression and in testing potential gene therapy constructs both in culture and in animal models of this disease.
Ray
P N
PN
Genetics Department, Hospital for Sick Children, Toronto, Canada.
Klamut
H J
HJ
Worton
R G
RG
D002874:Chromosome Mapping; D003001:Cloning, Molecular; D015870:Gene Expression; D015316:Genetic Therapy; D006801:Humans; D008297:Male; D009136:Muscular Dystrophies / Q000235:genetics* / Q000628:therapy; D011401:Promoter Regions, Genetic