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

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/+) Total RNA was isolated from 50 adult thoraxes per genotype (WT=Mhc-Gal4/+ and OPMD=UAS-PABPN1-17ala/+; Mhc-Gal4/+), per time-point (day 2, 6 and 11), in triplicates.