Elevation of RNA-binding protein CUGBP1 is an early event in an inducible heart-specific mouse model of myotonic dystrophy
Guey-Shin Wang, … , George Taffet, Thomas A. Cooper
Guey-Shin Wang, … , George Taffet, Thomas A. Cooper
Published October 1, 2007
Citation Information: J Clin Invest. 2007;117(10):2802-2811. https://doi.org/10.1172/JCI32308.
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Research Article Cardiology

Elevation of RNA-binding protein CUGBP1 is an early event in an inducible heart-specific mouse model of myotonic dystrophy

Abstract

Myotonic dystrophy type 1 (DM1) is caused by a CTG trinucleotide expansion in the 3′ untranslated region (3′ UTR) of DM protein kinase (DMPK). The key feature of DM1 pathogenesis is nuclear accumulation of RNA, which causes aberrant alternative splicing of specific pre-mRNAs by altering the functions of CUG-binding proteins (CUGBPs). Cardiac involvement occurs in more than 80% of individuals with DM1 and is responsible for up to 30% of disease-related deaths. We have generated an inducible and heart-specific DM1 mouse model expressing expanded CUG RNA in the context of DMPK 3′ UTR that recapitulated pathological and molecular features of DM1 including dilated cardiomyopathy, arrhythmias, systolic and diastolic dysfunction, and misregulated alternative splicing. Combined in situ hybridization and immunofluorescent staining for CUGBP1 and CUGBP2, the 2 CUGBP1 and ETR-3 like factor (CELF) proteins expressed in heart, demonstrated elevated protein levels specifically in nuclei containing foci of CUG repeat RNA. A time-course study demonstrated that colocalization of MBNL1 with RNA foci and increased CUGBP1 occurred within hours of induced expression of CUG repeat RNA and coincided with reversion to embryonic splicing patterns. These results indicate that CUGBP1 upregulation is an early and primary response to expression of CUG repeat RNA.

Authors

Guey-Shin Wang, Debra L. Kearney, Mariella De Biasi, George Taffet, Thomas A. Cooper

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Figure 1

Generation of bitransgenic mouse expressing expanded CUG RNA in heart.

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Generation of bitransgenic mouse expressing expanded CUG RNA in heart. (...
(A) EpA960 and EpA0 transgene constructs. The spliced mRNA transcripts from the nonrecombined (top) and recombined alleles (bottom) are indicated in blue above the gene diagrams. The mRNAs from the recombined EpA0 and EpA960 alleles are identical except for the presence or absence of the CUG repeats. Primer pairs used for RT-PCR analysis of nonrecombined and recombined alleles are shown. The CMV enhancer and β-actin promoter drive the transcription ubiquitously. Black boxes represent segments of different exons added for splicing. The cassette containing SV40 polyadenylation sites that prevent expression of RNA from downstream gene segments is located between 2 loxP sites. (B) Relative levels of the nonrecombined transgene mRNAs in different tissues from EpA960 and EpA0 transgenic mice using real-time RT-PCR. Results are from 3 mice from each line, with the exception of the muscle sample, taken from 1 mouse in line EpA960/MCM 1332. (C) Relative expression of EpA960(R) and EpA0(R) mRNAs from the recombined alleles after Cre-mediated recombination in heart.