The neurofibromatosis type I pre-mRNA is a novel target of CELF protein-mediated splicing regulation.
The CUG-BP and ETR-3 like factors (CELF) are a family of six highly conserved RNA-binding proteins that preferentially bind to UG-rich sequences. One of the key functions of these proteins is to mediate alternative splicing in a number of tissues, including brain, heart and muscle. To fully understand the function of CELF proteins, it is important to identify downstream targets of CELF proteins. In this communication, we report that neurofibromatosis type I (NF1) exon 23a is a novel target of CELF protein-mediated splicing regulation in neuron-like cells. NF1 regulates Ras signaling, and the isoform that excludes exon 23a shows 10 times greater ability to down-regulate Ras signaling than the isoform that includes exon 23a. Five of the six CELF proteins strongly suppress the inclusion of NF1 exon 23a. Over-expression or siRNA knockdown of these proteins in cell transfection experiments altered the levels of NF1 exon 23a inclusion. In vitro binding and splicing analyses demonstrate that CELF proteins block splicing through interfering with binding of U2AF(65). These studies, combined with our previous investigations demonstrating a role for Hu proteins and TIA-1/TIAR in controlling NF1 exon 23a inclusion, highlight the complex nature of regulation of this important alternative splicing event.
Department of Genetics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
Victoria A
VA
Barron
Hui
H
Zhu
Melissa N
MN
Hinman
Andrea N
AN
Ladd
Hua
H
Lou
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D051743:CCAAT-Enhancer-Binding Protein-delta / Q000378:metabolism*; D045744:Cell Line, Tumor; D005091:Exons; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D025542:Neurofibromin 1 / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D012322:RNA Precursors / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D012261:Ribonucleoproteins / Q000378:metabolism; D000072668:Splicing Factor U2AF
C497252:CEBPD protein, human; C497254:Cebpd protein, rat; D025542:Neurofibromin 1; D009687:Nuclear Proteins; D012322:RNA Precursors; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D000072668:Splicing Factor U2AF; C000607494:U2AF2 protein, human; D051743:CCAAT-Enhancer-Binding Protein-delta