The c.5242C>A missense variant induces exon skipping by increasing splicing repressors binding

Stefania Millevoi (1, 2) , Sandra Bernat (1, 2) , Dominique Telly (1) , Françoise Fouque (1) , Laurence Gladieff (1) , Gilles Favre (1, 2) , Stéphan Vagner (1, 2) , Christine Toulas (1, 2)

1 Institut Claudius Regaud
2 CPTP - Centre de Physiopathologie Toulouse Purpan

Several unclassified variants (UV) of can be deleterious by affecting normal pre-mRNA splicing. Here, we investigated the consequences at the mRNA level of the frequently encountered c.5242C>A UV in exon 18. We show that the c.5242C>A variant induces skipping of exon 18 in UV carriers and in vitro. This alteration predicted to disrupt the first BRCT domain of . We show that two splicing repressors, hnRNP A1 and hnRNP H/F, display a significant preference toward binding with the mutated exon 18 and assemble into a protein complex. Sequence analysis of the region surrounding the c.5242C>A change reveals the presence of hnRNP A1 and hnRNP H/F binding sites, which are modified by several UVs. Mutation of these sites alters the RNA binding ability of both splicing regulators. In conclusion, our work supports the model of the pathogenicity of the c.5242C>A variant that induces exon skipping by creating a sequence with silencer properties. We propose that other UVs in exon 18 interfere with splicing complex assembly by perturbing the binding of hnRNP A1 and hnRNP H/F to their respective -elements. RNA analysis is therefore necessary for the assessment of the consequences of UVs on splicing of disease-associated genes and to enable adequate genetic counseling for breast/ovarian cancer families.

Mots clés: Hereditary breast cancer; Unclassified variant; Splicing mutation; Aberrant splicing

Stefania Millevoi, Sandra Bernat, Dominique Telly, Françoise Fouque, Laurence Gladieff, et al.. The c.5242C>A missense variant induces exon skipping by increasing splicing repressors binding. Breast Cancer Research and Treatment, 2009, 120 (2), pp.391-399. ⟨10.1007/s10549-009-0392-3⟩. ⟨hal-00535357⟩