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 3

Misregulated alternative splicing of Tnnt2 and Fxr1h in heart expressing EpA960(R) mRNA but not EpA0(R) mRNA.

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Misregulated alternative splicing of Tnnt2 and Fxr1h in heart expressing...
(A) Alternative splicing patterns of mouse Tnnt2 exons 4 and 5 and the location of the RT-PCR primers (arrows). (B) Mice expressing EpA960(R) mRNA reverted to the embryonic splicing pattern of Tnnt2. The EpA960/MCM bitransgenic mice from 3 EpA960 lines as well as transgenic EpA960 and MCM mice were given tamoxifen (T) at a dosage of 20 mg/kg/d for 5 consecutive days, and RNA was extracted 1 week after the last injection. EpA960/MCM bitransgenic littermates treated with oil served as mock (M) controls. E18 cardiac tissue exhibited the Tnnt2 embryonic alternative splicing pattern. Percent of mRNAs containing exons 4 and 5 is shown. Asterisks denote a hybrid band of the 2 smallest PCR products. (C) Mice expressing EpA0(R) mRNA exhibited no phenotype and retained adult splicing patterns of Tnnt2 splicing both 1 week and 1 month following tamoxifen injection. (D) Decreased inclusion of exons 15 and 16 of FXR1h in mouse heart expressing EpA960(R) mRNA. Percent of mRNAs containing exons 15 and 16 is shown. (E) Decreased inclusion of exons 15 and 16 of FXR1h was also observed in individuals with DM1 (patient identification number shown in parentheses). Splicing abnormalities were not observed in tissue from unaffected individuals or individuals with non-DM1 forms of dilated cardiomyopathy (DCM).