title: Molecular, physiological, and motor performance defects in DMSXL mice carrying >1,000 CTG repeats from the human DM1 locus.
abstract: Myotonic dystrophy type 1 (DM1) is caused by an unstable CTG repeat expansion in the 3'UTR 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.
authors.affiliation: Inserm U781, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, Hôpital Necker-Enfants Malades, Paris, France.
authors.forename: Aline
authors.initials: A
authors.lastname: Huguet
authors.forename: Fadia
authors.initials: F
authors.lastname: Medja
authors.forename: Annie
authors.initials: A
authors.lastname: Nicole
authors.forename: Alban
authors.initials: A
authors.lastname: Vignaud
authors.forename: Céline
authors.initials: C
authors.lastname: Guiraud-Dogan
authors.forename: Arnaud
authors.initials: A
authors.lastname: Ferry
authors.forename: Valérie
authors.initials: V
authors.lastname: Decostre
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Hogrel
authors.forename: Friedrich
authors.initials: F
authors.lastname: Metzger
authors.forename: Andreas
authors.initials: A
authors.lastname: Hoeflich
authors.forename: Martin
authors.initials: M
authors.lastname: Baraibar
authors.forename: Mário
authors.initials: M
authors.lastname: Gomes-Pereira
authors.forename: Jack
authors.initials: J
authors.lastname: Puymirat
authors.forename: Guillaume
authors.initials: G
authors.lastname: Bassez
authors.forename: Denis
authors.initials: D
authors.lastname: Furling
authors.forename: Arnold
authors.initials: A
authors.lastname: Munnich
authors.forename: Geneviève
authors.initials: G
authors.lastname: Gourdon
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000254:growth & development / Q000503:physiopathology; D009223:Myotonic Dystrophy / Q000235:genetics / Q000503:physiopathology; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D012326:RNA Splicing; D019680:Trinucleotide Repeat Expansion / Q000235:genetics
chemical_list: C585517:DMPK protein, human; C585516:DMPK protein, mouse; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases; D010450:Endopeptidases; C080473:insulin-like growth factor binding protein-3 protease