Gene therapy is one the most promising treatments for genetic disorders. It is usually understood as either the
replacement of a defective gene with the correct one or the expression of a transgene whose product supplants its defective counterpart.
In several forms of beta-thalassemia, mutations in the second intron of the beta-globin gene create aberrant 5' splice sites and activate a common cryptic 3' splice site upstream. As a result, the thalassemic beta-globin pre-mRNAs are spliced almost exclusively via the aberrant splice sites leading to a deficiency of correctly spliced beta-globin mRNA protein. Gorman et al. have designed a series of vectors that express modified U7 snRNAs containing antisense sequences to aberrant splice sites in the thalassemic pre-mRNA. The antisense sequences are able to block the aberrant splice sites and restore the correct splicing pattern by forcing the splicing machinery to reselect the existing correct splice sites. Transient expression of modified U7 snRNAs in a HeLa cell line stably expressing the anomalous beta-globin gene significantly restored correct splicing in a sequence-specific and dose-dependent manner. This novel approach provides a
potential alternative to gene replacement therapies. (SOURCE: Proceedings of the National Academy of Sciences USA)
REFERENCE: Gorman L, Suter D, Emerick V, Schumperli D, Kole R.1998.Stable alteration of pre-mRNA splicing patterns by
modified U7 small nuclear RNAs. Proc. Natl. Acad. Sci. U.S.A. 95(9):4929-4934
Message posted by: Frank S. Zollmann