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Thorax transcriptome from control and PABPN1-17ala-expressing flies

ABSTRACT: Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset syndrome characterized by progressive degeneration of particular muscles. OPMD is caused by short GCG repeat expansions within the gene encoding the nuclear poly(A)-binding protein 1 (PABPN1) that extend an N-terminal polyalanine tract in the protein. Mutant PABPN1 aggregates as nuclear inclusions in OMPD patient muscles. We have created a Drosophila model of OPMD that recapitulates the features of the human disorder: progressive muscle degeneration, with muscle defects proportional to the number of alanines in the tract, and formation of PABPN1 nuclear inclusions. Wild-type human PABPN1 contains a stretch of 10 alanines following the initial methionine, which is expanded to 12–17 alanines in OPMD patients. In Drosophila, the PABPN1 homolog is the poly(A)-binding protein 2 (PABP2), which has the same function as PABPN1 in nuclear polyadenylation but lacks a polyalanine tract at the N-terminus. We used the UAS/Gal4 system to express mammalian PABPN1 in Drosophila. An alanine-expanded PABPN1 cDNA (encoding the 17 alanine tract) was cloned downstream of UAS sequences (UAS-PABPN1). Transgenic lines containing this construct were crossed to a Mhc-Gal4 driver, leading to muscle-specific expression. To gain insight into the molecular and physiological defects in OPMD we performed a transcriptomic analysis in OPMD fly muscles. Using microarrays, thorax gene expression was compared between control flies (Mhc-Gal4/+) and flies expressing PABPN1-17ala in thoracic muscles (UAS-PABPN1-17ala/+; Mhc-Gal4/+), at three time points (days 2, 6 and 11). Transcriptome of thorax RNA samples from control (Mhc-Gal4/+) flies and flies expressing PABPN1-17ala (UAS-PABPN1-17ala/+; Mhc-Gal4/+)

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE64094 | GEO | 2014/12/12

SECONDARY ACCESSION(S): PRJNA270104

REPOSITORIES: GEO

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Project description:Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by ptosis, dysphagia and proximal limb weakness. Autosomal-dominant OPMD is caused by a short (GCG)8–13 expansions within the first exon of the poly(A)-binding protein nuclear 1 gene (PABPN1), leading to an expanded polyalanine tract in the mutated protein. Expanded PABPN1 forms insoluble aggregates in the nuclei of skeletal muscle fibres. In order to gain insight into the different physiological processes affected in OPMD muscles, we have used a transgenic mouse model of OPMD (A17.1) and performed transcriptomic studies combined with a detailed phenotypic characterization of this model at three time points. The transcriptomic analysis revealed a massive gene deregulation in the A17.1 mice, among which we identified a significant deregulation of pathways associated with muscle atrophy. Using a mathematical model for progression, we have identified that one-third of the progressive genes were also associated with muscle atrophy. Functional and histological analysis of the skeletal muscle of this mouse model confirmed a severe and progressive muscular atrophy associated with a reduction in muscle strength. Moreover, muscle atrophy in the A17.1 mice was restricted to fast glycolytic fibres, containing a large number of intranuclear inclusions (INIs). The soleus muscle and, in particular, oxidative fibres were spared, even though they contained INIs albeit to a lesser degree. These results demonstrate a fibre-type specificity of muscle atrophy in this OPMD model. This study improves our understanding of the biological pathways modified in OPMD to identify potential biomarkers and new therapeutic targets. A17.1 transgenic mice have previously been described. Male A17.1 mice and WT controls were generated by crossing the heterozygous carrier strain A17.1 obtained from Rubinsztein's group with the FvB background mice. The mice were genotyped by PCR 3–4 weeks after birth. Wild type FvB and A17.1 mice were housed in minimal disease facilities (Royal Holloway, University of London) with food and water ad libitum. Total RNA was extracted from skeletal muscles using RNA Bee (Amsbio) according to the manufacturer's instructions. RNA integration number (RIN) was determined with RNA 6000 Nano (Agilent Technologies). RNA with RIN >7 were used for subsequent steps. RNA labelling was performed with the Illumina® TotalPrep RNA Amplification kit (Ambion) according to the manufacturer's protocol, and subsequently was hybridized to Illumina Mouse v1.1 Bead arrays.

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Thorax transcriptome from control and PABPN1-17ala-expressing flies

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