Identification and characterization of splice-altering compounds with possible therapeutic use for familial dysautonomia
Familial dysautonomia (FD) is an autosomal recessive disorder that is caused by mutations in the IKBKAP gene that result in the production of nonfunctional IKAP protein. The most common FD-causing mutation, IVS20+6T→C, changes the splice donor site of intron 20 and causes aberrant splicing that generates an IKBKAP transcript lacking exon 20. The reported ability to modulate the production of the wild-type transcript in cells bearing the splice-altering FD-causing mutation in the IKBKAP gene prompted an intensive evaluation of the impact of commonly consumed nutraceuticals and pharmaceuticals on the splicing of this transcript. High throughput screening efforts revealed the ability of the isoflavones, genistein and daidzein, and the cardiac glycoside, digoxin, to impact the splicing process and increase the production of the wild-type, exon 20-containing, IKBKAP-encoded transcript and full-length IKAP protein in FD-derived cells. Genistein and digoxin were also found to impact splicing in neuronal cells, a cell type profoundly impacted by FD. The simultaneous exposure of FD-derived cells to genistein and epigallocatechin gallate (EGCG) resulted in the almost exclusive production of the exon 20-containing transcript and the production of wild-type amounts of IKAP protein. Characterization of the digoxin-mediated effect on the RNA splicing process was enabled by the identification of several RNA splicing events in which digoxin treatment mediates the enhanced inclusion of exonic sequence. Characterization of the cis elements and trans factors involved in the digoxin-mediated effect on splicing reveals that this response is dependent on an SRp20 binding site(s) located in the intron 5' of the alternatively spliced exon and that digoxin mediates its effect by suppressing the level of the SRp20 protein. This work demonstrates that genistein and digoxin possess splice-altering capabilities that are capable of reversing the impact of the FD-causing mutation. These findings support the clinical evaluation of the therapeutic impact of these splice-altering compounds on the FD patient population.
Molecular biology|Cellular biology
Liu, Bo, "Identification and characterization of splice-altering compounds with possible therapeutic use for familial dysautonomia" (2012). ETD Collection for Fordham University. AAI3544402.