Antagonistic factors control the unproductive splicing of SC35 terminal intron.
Alternative splicing is regulated in part by variations in the relative concentrations of a variety of factors, including serine/arginine-rich (SR) proteins. The SR protein SC35 self-regulates its expression by stimulating unproductive splicing events in the 3' untranslated region of its own pre-mRNA. Using various minigene constructs containing the terminal retained intron and flanking exons, we identified in the highly conserved last exon a number of exonic splicing enhancer elements responding specifically to SC35, and showed an inverse correlation between affinity of SC35 and enhancer strength. The enhancer region, which is included in a long stem loop, also contains repressor elements, and is recognized by other RNA-binding proteins, notably hnRNP H protein and TAR DNA binding protein (TDP-43). Finally, in vitro and in cellulo experiments indicated that hnRNP H and TDP-43 antagonize the binding of SC35 to the terminal exon and specifically repress the use of SC35 terminal 3' splice site. Our study provides new information about the molecular mechanisms of SC35-mediated splicing activation. It also highlights the existence of a complex network of self- and cross-regulatory mechanisms between splicing regulators, which controls their homeostasis and offers many ways of modulating their concentration in response to the cellular environment.
Dreumont
Natacha
N
IGBMC Department of Functional Genomics, INSERM U964, CNRS UMR 7104, 67400 Illkirch, France.
Hardy
Sara
S
Behm-Ansmant
Isabelle
I
Kister
Liliane
L
Branlant
Christiane
C
Stévenin
James
J
Bourgeois
Cyril F
CF
D017398:Alternative Splicing; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D004268:DNA-Binding Proteins / Q000378:metabolism; D005091:Exons; D006367:HeLa Cells; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H / Q000378:metabolism; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000378:metabolism; D006801:Humans; D007438:Introns; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D022821:RNA Splice Sites; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D038621:Regulatory Sequences, Ribonucleic Acid; D000068103:Serine-Arginine Splicing Factors
D004268:DNA-Binding Proteins; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D009687:Nuclear Proteins; D022821:RNA Splice Sites; D016601:RNA-Binding Proteins; D038621:Regulatory Sequences, Ribonucleic Acid; D000068103:Serine-Arginine Splicing Factors