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Molecular, Physiological, and Motor Performance Defects in DMSXL Mice Carrying > 1,000 CTG Repeats from the Human DM1 Locus

By Aline Huguet, Fadia Medja, Annie Nicole, Alban Vignaud, Celine Guiraud-Dogan, Arnaud Ferry, Valerie Decostre, Jean-Yves Hogrel, Friedrich Metzger, Andreas Hoeflich, Martin Baraibar, Mario Gomes-Pereira, Jack Puymirat, Guillaume Bassez, Denis Furling, Arnold Munnich and Genevieve Gourdon

Abstract

International audienceMyotonic dystrophy type 1 (DM1) is caused by an unstable CTG repeat expansion in the 39UTR of the DM protein kinase (DMPK) gene. DMPK transcripts carrying CUG expansions form nuclear foci and affect splicing regulation of various RNA transcripts. Furthermore, bidirectional transcription over the DMPK gene and non-conventional RNA translation of repeated transcripts have been described in DM1. It is clear now that this disease may involve multiple pathogenic pathways including changes in gene expression, RNA stability and splicing regulation, protein translation, and micro-RNA metabolism. We previously generated transgenic mice with 45-kb of the DM1 locus and >300 CTG repeats (DM300 mice). After successive breeding and a high level of CTG repeat instability, we obtained transgenic mice carrying >1,000 CTG (DMSXL mice). Here we described for the first time the expression pattern of the DMPK sense transcripts in DMSXL and human tissues. Interestingly, we also demonstrate that DMPK antisense transcripts are expressed in various DMSXL and human tissues, and that both sense and antisense transcripts accumulate in independent nuclear foci that do not co-localize together. Molecular features of DM1-associated RNA toxicity in DMSXL mice (such as foci accumulation and mild missplicing), were associated with high mortality, growth retardation, and muscle defects (abnormal histopathology, reduced muscle strength, and lower motor performances). We have found that lower levels of IGFBP-3 may contribute to DMSXL growth retardation, while increased proteasome activity may affect muscle function. These data demonstrate that the human DM1 locus carrying very large expansions induced a variety of molecular and physiological defects in transgenic mice, reflecting DM1 to a certain extent. As a result, DMSXL mice provide an animal tool to decipher various aspects of the disease mechanisms. In addition, these mice can be used to test the preclinical impact of systemic therapeutic strategies on molecular and physiological phenotypes

Topics: [SDV.BC]Life Sciences [q-bio]/Cellular Biology
Publisher: 'Public Library of Science (PLoS)'
Year: 2012
DOI identifier: 10.1371/journal.pgen.1003043
OAI identifier: oai:HAL:hal-01544072v1
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