The c.5242C>A BRCA1 missense variant induces exon skipping by increasing splicing repressors binding.
Several unclassified variants (UV) of BRCA1 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 BRCA1 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 BRCA1. 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 BRCA1 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 cis-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.
Millevoi
Stefania
S
INSERM U563, Institut Claudius Regaud, 20-24 rue du Pont St Pierre, 31052, Toulouse, France. millevoi.stefania@claudiusregaud.fr
Bernat
Sandra
S
Telly
Dominique
D
Fouque
Françoise
F
Gladieff
Laurence
L
Favre
Gilles
G
Vagner
Stéphan
S
Toulas
Christine
C
D000328:Adult; D019313:BRCA1 Protein / Q000235:genetics; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005260:Female; D019398:Genes, BRCA1; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000235:genetics; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010051:Ovarian Neoplasms / Q000235:genetics*; D010375:Pedigree; D020033:Protein Isoforms / Q000235:genetics; D012326:RNA Splicing / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D019313:BRCA1 Protein; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D020033:Protein Isoforms