Myotonic dystrophy CTG expansion affects synaptic vesicle proteins, neurotransmission and mouse behaviour.

Myotonic dystrophy type 1 is a complex multisystemic inherited disorder, which displays multiple debilitating neurological manifestations. Despite recent progress in the understanding of the molecular pathogenesis of myotonic dystrophy type 1 in skeletal muscle and heart, the pathways affected in the central nervous system are largely unknown. To address this question, we studied the only transgenic mouse line expressing CTG trinucleotide repeats in the central nervous system. These mice recreate molecular features of RNA toxicity, such as RNA foci accumulation and missplicing. They exhibit relevant behavioural and cognitive phenotypes, deficits in short-term synaptic plasticity, as well as changes in neurochemical levels. In the search for disease intermediates affected by disease mutation, a global proteomics approach revealed RAB3A upregulation and synapsin I hyperphosphorylation in the central nervous system of transgenic mice, transfected cells and post-mortem brains of patients with myotonic dystrophy type 1. These protein defects were associated with electrophysiological and behavioural deficits in mice and altered spontaneous neurosecretion in cell culture. Taking advantage of a relevant transgenic mouse of a complex human disease, we found a novel connection between physiological phenotypes and synaptic protein dysregulation, indicative of synaptic dysfunction in myotonic dystrophy type 1 brain pathology.

TGFß receptor gene variants in systemic sclerosis-related pulmonary arterial hypertension: results from a multicentre EUSTAR study of European Caucasian patients.

INTRODUCTION: Systemic sclerosis (SSc)-related pulmonary arterial hypertension (PAH) has emerged as a major mortality prognostic factor. Mutations of transforming growth factor beta (TGFß) receptor genes strongly contribute to idiopathic and familial PAH. OBJECTIVE: To explore the genetic bases of SSc-PAH, we combined direct sequencing and genotyping of candidate genes encoding TGFß receptor family members. MATERIALS AND METHODS: TGFß receptor genes, BMPR2, ALK1, TGFR2 and ENG, were sequenced in 10 SSc-PAH patients, nine SSc and seven controls. In addition, 22 single-nucleotide polymorphisms (SNP) of these four candidate genes were tested for association in a first set of 824 French Caucasian SSc patients (including 54 SSc-PAH) and 939 controls. The replication set consisted of 1516 European SSc (including 219 SSc-PAH) and 3129 controls from the European League Against Rheumatism Scleroderma Trials and Research group network. RESULTS: No mutation was identified by direct sequencing. However, two repertoried SNP, ENG rs35400405 and ALK1 rs2277382, were found in SSc-PAH patients only. The genotyping of 22 SNP including the latter showed that only rs2277382 was associated with SSc-PAH (p=0.0066, OR 2.13, 95% CI 1.24 to 3.65). Nevertheless, this was not replicated with the following result in combined analysis: p=0.123, OR 0.79, 95% CI 0.59 to 1.07. CONCLUSIONS: This study demonstrates the lack of association between these TGFß receptor gene polymorphisms and SSc-PAH using both sequencing and genotyping methods.

A genetic variation located in the promoter region of the UPAR (CD87) gene is associated with the vascular complications of systemic sclerosis.

OBJECTIVE: The UPAR gene encodes a pleiotropic receptor (urokinase-type plasminogen activator receptor [uPAR]) involved in fibrosis, immunity, angiogenesis, and vascular remodeling. Previous studies have implicated uPAR in systemic sclerosis (SSc) vasculopathy and impaired angiogenesis. We undertook this study to investigate whether UPAR gene promoter polymorphisms might be associated with SSc phenotypes in the European Caucasian population. METHODS: We studied a total population of 1,339 individuals. The Italian discovery cohort comprised 388 SSc patients and 391 healthy controls. The French replication cohort consisted of 344 SSc patients and 216 healthy controls. The UPAR rs344781 and rs4251805 single-nucleotide polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism assay. RESULTS: In the Italian cohort, the rs344781 G allele was associated with SSc-related digital ulceration (odds ratio [OR] 1.39), pulmonary arterial hypertension (PAH) (OR 1.81), anticentromere antibody (ACA) positivity (OR 1.45), and limited cutaneous SSc (lcSSc) (OR 1.37). The rs344781 GG genotype was associated with SSc-related (OR 3.79), ACA-positive SSc (OR 2.17), and lcSSc (OR 1.96). Allelic and genotypic associations with SSc-related digital ulceration and ACA-positive SSc were replicated in the French sample. Combined analyses showed an association of the rs344781 G allele and GG genotype with SSc-related digital ulceration (allele OR 1.41, genotype OR 2.15), SSc-related PAH (allele OR 1.65, genotype OR 3.16), ACA-positive SSc (allele OR 1.47, genotype OR 2.40), and lcSSc (allele OR 1.34, genotype OR 1.77). In a multivariate logistic regression analysis model including the above associated phenotypes of SSc patients, the rs344781 GG genotype remained an independent risk factor for SSc-related digital ulceration (OR 1.96) and SSc-related PAH (OR 2.68). CONCLUSION: The UPAR rs344781 gene variant is associated with the SSc vascular phenotype.

Peptide-conjugated oligonucleotides evoke long-lasting myotonic dystrophy correction in patient-derived cells and mice.

Antisense oligonucleotides (ASOs) targeting pathologic RNAs have shown promising therapeutic corrections for many genetic diseases including myotonic dystrophy (DM1). Thus, ASO strategies for DM1 can abolish the toxic RNA gain-of-function mechanism caused by nucleus-retained mutant DMPK (DM1 protein kinase) transcripts containing CUG expansions (CUGexps). However, systemic use of ASOs for this muscular disease remains challenging due to poor drug distribution to skeletal muscle. To overcome this limitation, we test an arginine-rich Pip6a cell-penetrating peptide and show that Pip6a-conjugated morpholino phosphorodiamidate oligomer (PMO) dramatically enhanced ASO delivery into striated muscles of DM1 mice following systemic administration in comparison with unconjugated PMO and other ASO strategies. Thus, low-dose treatment with Pip6a-PMO-CAG targeting pathologic expansions is sufficient to reverse both splicing defects and myotonia in DM1 mice and normalizes the overall disease transcriptome. Moreover, treated DM1 patient-derived muscle cells showed that Pip6a-PMO-CAG specifically targets mutant CUGexp-DMPK transcripts to abrogate the detrimental sequestration of MBNL1 splicing factor by nuclear RNA foci and consequently MBNL1 functional loss, responsible for splicing defects and muscle dysfunction. Our results demonstrate that Pip6a-PMO-CAG induces long-lasting correction with high efficacy of DM1-associated phenotypes at both molecular and functional levels, and strongly support the use of advanced peptide conjugates for systemic corrective therapy in DM1.