The CUG-binding protein binds specifically to UG dinucleotide repeats in a yeast three-hybrid system.
The CUG-binding protein (CUG-BP) has been reported to be involved in the pathogenesis of myotonic dystrophy (DM) through binding to a CUG trinucleotide repeat located in the 3' untranslated region (3'UTR) of the DM protein kinase (DMPK) gene. We found that CUG-BP associates with long CUG trinucleotide repeats ((CUG)(11)(CUG)(12)), but not with short repeats ((CUG)(12)) in a yeast three-hybrid system. On the other hand, CUG-BP+LYLQ, an alternatively spliced isoform of CUG-BP, does not associate with CUG trinucleotide repeats regardless of the repeat length. In addition to these findings, we found that CUG-BP and CUG-BP+LYLQ strongly and specifically associate with UG dinucleotide repeats. Deletion analyse of CUG-BP revealed that the absence of the first or third RNA-binding domain (RBD I and RBD III, respectively) does not affect the interaction between CUG-BP and UG dinucleotide repeats. Loss of the second RNA-binding domain (RBD II) decreases the affinity of CUG-BP for UG dinucleotide repeats by about 40%. Unexpectedly, deletion of the linker domain most severely reduces the interaction, although this region does not contain a known RNA-binding motif. Our results suggest the possibility that both CUG-BP and CUG-BP+LYLQ associate with UG repeat-containing mRNAs and regulate such metabolic properties as mRNA localization, stability, and translation, and provide new insights into the pathogenesis of DM.
Takahashi
N
N
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
Sasagawa
N
N
Suzuki
K
K
Ishiura
S
S
D020413:3' Untranslated Regions; D017398:Alternative Splicing; D000067879:CELF1 Protein; D018900:Dinucleotide Repeats; D017353:Gene Deletion; D016297:Mutagenesis, Site-Directed; D065636:Myotonin-Protein Kinase; D009841:Oligonucleotides / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D001616:beta-Galactosidase / Q000378:metabolism
D020413:3' Untranslated Regions; D000067879:CELF1 Protein; C102843:CELF1 protein, human; C585517:DMPK protein, human; D009841:Oligonucleotides; D020033:Protein Isoforms; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases; D001616:beta-Galactosidase