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

• Published in: Human molecular genetics Vol. 13; no. 5; pp. 495 - 507
• Main Authors: Kino, Yoshihiro, Mori, Daisuke, Oma, Yoko, Takeshita, Yuya, Sasagawa, Noboru, Ishiura, Shoichi
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.03.2004; Oxford Publishing Limited (England)
• Subjects: Alternative Splicing - genetics; Biological and medical sciences; CELF Proteins; Classical genetics, quantitative genetics, hybrids; CUG-BP protein; DNA Primers; eIF-2 Kinase - metabolism; Electrophoretic Mobility Shift Assay; EXP protein; Fundamental and applied biological sciences. Psychology; Gene Components; Genetics of eukaryotes. Biological and molecular evolution; Glutathione Transferase - metabolism; Human; Humans; MBNL1 protein; Molecular and cellular biology; Myotonic dystrophy; Myotonic Dystrophy - genetics; Myotonic Dystrophy - metabolism; PKR protein; Repetitive Sequences, Nucleic Acid - genetics; Repetitive Sequences, Nucleic Acid - physiology; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; Transformation, Bacterial; Two-Hybrid System Techniques; ZNF9 gene; Genetics; Protein
• ISSN: 0964-6906; 1460-2083; 1460-2083
• DOI: 10.1093/hmg/ddh056

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.