RNA-seq of skeletal muscle model for myotonic dystrophy type 1 (DM1)

We have developed an inducible, skeletal muscle-specific mouse model of DM1 (CUG960) that expresses 960 CUG repeat-expressing animals (CUG960) in the context of human DMPK exons 11-15. CUG960 RNA-expressing mice induced at postnatal day 1, as well as adult-onset animals, show clear, measurable muscle wasting accompanied by severe histological defects including central myonuclei, reduced fiber cross-sectional area, increased percentage of oxidative myofibers, the presence of nuclear RNA foci that colocalize with Mbnl1 protein, and increased Celf1 protein in severely affected muscles. Importantly, muscle loss, histological abnormalities and RNA foci are reversible, demonstrating recovery upon removal of toxic RNA. RNA-seq and protein array analysis indicate that the balance between anabolic and catabolic pathways that normally regulate muscle mass may be disrupted by deregulation of platelet derived growth factor receptor beta signaling and the PI3K/AKT pathways, along with prolonged activation of AMP-activated protein kinase alpha signaling. Similar changes were detected in DM1 skeletal muscle compared with unaffected controls. RNA was isolated from gastrocnemius or quadriceps muscles. Animals were induced to express expanded CUG repeats using doxycycline (dox) or no dox controls at PN1 and tissues were collected at the indicated time points. The Genomic and RNA Profiling Core (GARP) at Baylor College of Medicine (BCM) performed HiSeq library preparation and Illumina sequencing of 100-bp paired-end reads on a HiSeq 2500 sequencer. RNA was poly-A selected, barcoded and run in eight lanes.