Journal Article

Muscleblind protein, MBNL1/EXP, binds specifically to CHHG repeats

Yoshihiro Kino, Daisuke Mori, Yoko Oma, Yuya Takeshita, Noboru Sasagawa and Shoichi Ishiura

in Human Molecular Genetics

Volume 13, issue 5, pages 495-507
Published in print March 2004 | ISSN: 0964-6906
Published online January 2004 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/ddh056
Muscleblind protein, MBNL1/EXP, binds specifically to CHHG repeats

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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.

Journal Article.  10178 words.  Illustrated.

Subjects: Genetics and Genomics

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