The prevalent deep intronic c. 639+919 G>A GLA mutation causes pseudoexon activation and Fabry disease by abolishing the binding of hnRNPA1 and hnRNP A2/B1 to a splicing silencer.
Fabry disease is an X-linked recessive inborn disorder of the glycosphingolipid metabolism, caused by total or partial deficiency of the lysosomal α-galactosidase A enzyme due to mutations in the GLA gene. The prevalent c.639+919 G>A mutation in GLA leads to pathogenic insertion of a 57bp pseudoexon sequence from intron 4, which is responsible for the cardiac variant phenotype. In this study we investigate the splicing regulatory mechanism leading to GLA pseudoexon activation. Splicing analysis of GLA minigenes revealed that pseudoexon activation is influenced by cell-type. We demonstrate that the wild-type sequence harbors an hnRNP A1 and hnRNP A2/B1-binding exonic splicing silencer (ESS) overlapping the 5'splice site (5'ss) that prevents pseudoexon inclusion. The c.639+919 G>A mutation disrupts this ESS allowing U1 snRNP recognition of the 5'ss. We show that the wild-type GLA 5'ss motif with the ESS is also able to inhibit inclusion of an unrelated pseudoexon in the FGB gene, and that also in the FGB context inactivation of the ESS by the c.639+919 G>A mutation causes pseudoexon activation, underscoring the universal nature of the ESS. Finally, we demonstrate that splice switching oligonucleotide (SSO) mediated blocking of the pseudoexon 3'ss and 5'ss effectively restores normal GLA splicing. This indicates that SSO based splicing correction may be a therapeutic alternative in the treatment of Fabry disease.
Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark.
Bruno
B
Palhais
Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark.
Maja
M
Dembic
Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark.
Rugivan
R
Sabaratnam
Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark.
Kira S
KS
Nielsen
Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark.
Thomas Koed
TK
Doktor
Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark.
Gitte Hoffmann
GH
Bruun
Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark. Electronic address: bragea@bmb.sdu.dk.
Brage Storstein
BS
Andresen
D005091:Exons / Q000235:genetics; D000795:Fabry Disease / Q000235:genetics* / Q000473:pathology; D006367:HeLa Cells; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1 / Q000235:genetics*; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000235:genetics*; D006801:Humans; D007438:Introns; D009154:Mutation; D022821:RNA Splice Sites; D012326:RNA Splicing / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D037941:Silencer Elements, Transcriptional / Q000235:genetics; D000519:alpha-Galactosidase / Q000235:genetics*
D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D022821:RNA Splice Sites; D012333:RNA, Messenger; C000619656:hnRNPA1 protein, human; C576330:GLA protein, human; D000519:alpha-Galactosidase
ESE; ESS; Fabry disease; GLA; Pseudoexon; Splice switching oligonucleotide (SSO); hnRNP A1 hnRNP A2/B1; hnRNP F/H