title: The BRCA1 alternative splicing variant Δ14-15 with an in-frame deletion of part of the regulatory serine-containing domain (SCD) impairs the DNA repair capacity in MCF-7 cells.
abstract: The BRCA1 gene codes for a protein involved in the DNA double strand break (DDSB) repair. Alongside the dominant full-length splicing form of BRCA1, numerous endogenously expressed alternative splicing variants of unknown significance have been described in various tissues. Some of them retain the original BRCA1 reading frame but lack several critical BRCA1 structural domains, suggesting an altered function of the resulting protein in the BRCA1-regulated processes. To characterize the effect of the BRCA1Δ14-15 splicing variant (with an in-frame deletion affecting the regulatory serine-containing domain) on the DDSB repair, we constructed the MCF-7 clones stably expressing the analyzed variant with/without a shRNA-mediated downregulation of the endogenous full-length wild-type BRCA1 expression. Our results show that the expression of the BRCA1Δ14-15 variant delays the γ-radiation-induced DDSB repair, alters the kinetics of irradiation-induced foci formation/decomposition and reduces the non-homologous end-joining capacity in MCF-7 cells. Therefore, the BRCA1Δ14-15 is not able to functionally replace the full-length wt BRCA1 in the DDSB repair. Our findings indicate that the endogenously expressed BRCA1 alternative splicing variants may negatively influence genome stability and support the growing evidence of the pathological potential of the sequence variants generated by an altered or misregulated alternative splicing in the process of mammary malignant transformation.
authors.affiliation: Institute of Biochemistry and Experimental Oncology, First Faculty of Medicine, Charles University in Prague, U Nemocnice 5, 128 53 Prague 2, Czech Republic. jsevc@lf1.cuni.cz
authors.forename: Jan
authors.initials: J
authors.lastname: Sevcik
authors.forename: Martin
authors.initials: M
authors.lastname: Falk
authors.forename: Petra
authors.initials: P
authors.lastname: Kleiblova
authors.forename: Filip
authors.initials: F
authors.lastname: Lhota
authors.forename: Lenka
authors.initials: L
authors.lastname: Stefancikova
authors.forename: Marketa
authors.initials: M
authors.lastname: Janatova
authors.forename: Lenka
authors.initials: L
authors.lastname: Weiterova
authors.forename: Emilie
authors.initials: E
authors.lastname: Lukasova
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kozubek
authors.forename: Petr
authors.initials: P
authors.lastname: Pohlreich
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Kleibl
mesh_terms: D000595:Amino Acid Sequence; D019313:BRCA1 Protein / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001943:Breast Neoplasms; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism / Q000528:radiation effects; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D005260:Female; D005720:Gamma Rays; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016364:Reading Frames; D017384:Sequence Deletion
chemical_list: D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D020033:Protein Isoforms