title: Impact of G-quadruplex structures and intronic polymorphisms rs17878362 and rs1642785 on basal and ionizing radiation-induced expression of alternative p53 transcripts.
abstract: G-quadruplex (G4) structures in intron 3 of the p53 pre-mRNA modulate intron 2 splicing, altering the balance between the fully spliced p53 transcript (FSp53, encoding full-length p53) and an incompletely spliced transcript retaining intron 2 (p53I2 encoding the N-terminally truncated Δ40p53 isoform). The nucleotides forming G4s overlap the polymorphism rs17878362 (A1 wild-type allele, A2 16-base pair insertion) which is in linkage disequilibrium with rs1642785 in intron 2 (c.74+38 G>C). Biophysical and biochemical analyses show rs17878362 A2 alleles form similar G4 structures as A1 alleles although their position is shifted with respect to the intron 2 splice acceptor site. In addition basal FSp53 and p53I2 levels showed allele specific differences in both p53-null cells transfected with reporter constructs or lymphoblastoid cell lines. The highest FSp53 and p53I2 levels were associated with combined rs1642785-GG/rs17878362-A1A1 alleles, whereas the presence of rs1642785-C with either rs17878362 allele was associated with lower p53 pre-mRNA, total TP53, FSp53 and p53I2 levels, due to the lower stability of transcripts containing rs1642785-C. Treatment of lymphoblastoid cell with the G4 binding ligands 360A or PhenDC3 or with ionizing radiation increased FSp53 levels only in cells with rs17878362 A1 alleles, suggesting that under this G4 configuration full splicing is favoured. These results demonstrate the complex effects of intronic TP53 polymorphisms on G4 formation and identify a new role for rs1642785 on mRNA splicing and stability, and thus on the differential expression of isoform-specific transcripts of the TP53 gene.
authors.affiliation: Institut Curie, Centre de Recherche and Inserm, U612, Bât. 110-112, Centre Universitaire, Orsay F-91405, France.
authors.forename: Laury
authors.initials: L
authors.lastname: Perriaud
authors.affiliation: Institut Curie, Centre de Recherche and Inserm, U612, Bât. 110-112, Centre Universitaire, Orsay F-91405, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Marcel
authors.affiliation: Institut Curie, Centre de Recherche and Inserm, U612, Bât. 110-112, Centre Universitaire, Orsay F-91405, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Sagne
authors.affiliation: Institut Curie, Centre de Recherche and Inserm, U612, Bât. 110-112, Centre Universitaire, Orsay F-91405, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Favaudon
authors.affiliation: Inserm U869, Institut Européen de Chimie et Biologie, Pessac F-33607, France, Univ. Bordeaux, ARNA Laboratory, Bordeaux F-33000, France.
authors.forename: Aurore
authors.initials: A
authors.lastname: Guédin
authors.affiliation: Inserm U869, Institut Européen de Chimie et Biologie, Pessac F-33607, France, Univ. Bordeaux, ARNA Laboratory, Bordeaux F-33000, France.
authors.forename: Aurore
authors.initials: A
authors.lastname: De Rache
authors.affiliation: Institut Curie, Centre de Recherche and CNRS, UMR176, Bât. 110-112, Centre Universitaire, Orsay F-91405, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Guetta
authors.affiliation: Institut Curie, Centre de Recherche and CNRS, UMR176, Bât. 110-112, Centre Universitaire, Orsay F-91405, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Hamon
authors.affiliation: Institut Curie, Centre de Recherche and CNRS, UMR176, Bât. 110-112, Centre Universitaire, Orsay F-91405, France.
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Teulade-Fichou
authors.affiliation: International Prevention Research Institute, University of Strathclyde School of Global Public Health at iPRI, Lyon F-69006, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Hainaut
authors.affiliation: Inserm U869, Institut Européen de Chimie et Biologie, Pessac F-33607, France, Univ. Bordeaux, ARNA Laboratory, Bordeaux F-33000, France.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Mergny
authors.affiliation: Institut Curie, Centre de Recherche and Inserm, U612, Bât. 110-112, Centre Universitaire, Orsay F-91405, France, janet.hall@curie.fr.
authors.forename: Janet
authors.initials: J
authors.lastname: Hall
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology / Q000532:radiotherapy; D017398:Alternative Splicing / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology / Q000532:radiotherapy; D005091:Exons; D005260:Female; D054856:G-Quadruplexes / Q000528:radiation effects*; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects*; D005838:Genotype; D006801:Humans; D007438:Introns / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000235:genetics; D011839:Radiation, Ionizing; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
chemical_list: D020033:Protein Isoforms; D012333:RNA, Messenger; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53