Muscleblind protein, MBNL1/EXP, binds specifically to CHHG repeats.
Myotonic dystrophy (DM) type 1 is caused by an expansion of a CTG repeat in the DMPK gene and type 2 by a CCTG repeat in the ZNF9 gene. Previous reports have suggested that transcripts containing expanded CUG/CCUG repeats might have toxic gain-of-function effects, probably affecting the function of RNA-binding proteins in the pathogenesis of DM. Here, it was attempted to compare the RNA-binding properties of three proteins, CUG-BP, MBNL1/EXP and PKR, which have previously been suggested to interact with CUG repeats. MBNL1, but not CUG-BP or PKR, interacted with both CUG and CCUG repeats in a yeast three-hybrid system. By using various synthetic RNAs, it was found that MBNL1 specifically interacts with repetitive sequences summarized as CHHG and CHG repeats, where H is A, U or C. Interestingly, MBNL1 did not interact with a genuine double-stranded RNA comprising CAG/CUG repeats, suggesting that MBNL1 prefers bulge-containing double-stranded RNAs. Deletion analysis indicates a difference in RNA-binding abilities among splice variants of MBNL1. It was also found that MBNL1 can bind to repetitive motifs in ZNF9, which contain a minimal length of CCUG repeats with non-CCUG insertions.
Kino
Yoshihiro
Y
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan.
Mori
Daisuke
D
Oma
Yoko
Y
Takeshita
Yuya
Y
Sasagawa
Noboru
N
Ishiura
Shoichi
S
D017398:Alternative Splicing / Q000235:genetics; D000067878:CELF Proteins; D017931:DNA Primers; D024202:Electrophoretic Mobility Shift Assay; D040461:Gene Components; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D009223:Myotonic Dystrophy / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics* / Q000502:physiology; D014169:Transformation, Bacterial; D020798:Two-Hybrid System Techniques; D019892:eIF-2 Kinase / Q000378:metabolism
D000067878:CELF Proteins; C422242:CELF3 protein, human; C433227:CNBP protein, human; D017931:DNA Primers; C493663:MBNL1 protein, human; D016601:RNA-Binding Proteins; D005982:Glutathione Transferase; D019892:eIF-2 Kinase