CELF proteins regulate CFTR pre-mRNA splicing: essential role of the divergent domain of ETR-3.
Cystic fibrosis is a prominent genetic disease caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Among the many disease-causing alterations are pre-mRNA splicing defects that can hamper mandatory exon inclusion. CFTR exon 9 splicing depends in part on a polymorphic UG(m)U(n) sequence at the end of intron 8, which can be bound by TDP-43, leading to partial exon 9 skipping. CELF proteins, like CUG-BP1 and ETR-3, can also bind UG repeats and regulate splicing. We show here that ETR-3, but not CUG-BP1, strongly stimulates exon 9 skipping, although both proteins bind efficiently to the same RNA motif as TDP-43 and with higher affinity. We further show that the skipping of this exon may be due to the functional antagonism between U2AF65 and ETR-3 binding onto the polymorphic U or UG stretch, respectively. Importantly, we demonstrate that the divergent domain of ETR-3 is critical for CFTR exon 9 skipping, as shown by deletion and domain-swapping experiments. We propose a model whereby several RNA-binding events account for the complex regulation of CFTR exon 9 inclusion, with strikingly distinct activities of ETR-3 and CUG-BP1, related to the structure of their divergent domain.
Dujardin
Gwendal
G
Inserm U613-ECLA Team, Faculty of Medicine, 22 Avenue Camille Desmoulins, 29238 Brest Cedex 3, France.
Buratti
Emanuele
E
Charlet-Berguerand
Nicolas
N
Martins de Araujo
Mafalda
M
Mbopda
Annick
A
Le Jossic-Corcos
Catherine
C
Pagani
Franco
F
Ferec
Claude
C
Corcos
Laurent
L
D001665:Binding Sites; D002460:Cell Line; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D005091:Exons; D006801:Humans; D007438:Introns; D009687:Nuclear Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012322:RNA Precursors / Q000378:metabolism; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D012091:Repetitive Sequences, Nucleic Acid; D012261:Ribonucleoproteins / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism; D000072668:Splicing Factor U2AF
D009687:Nuclear Proteins; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D000072668:Splicing Factor U2AF; C000607494:U2AF2 protein, human; D019005:Cystic Fibrosis Transmembrane Conductance Regulator