Effect of dexamethasone treatment on the transcriptome of injured mouse hamstring muscle

Healthy muscle heals and repairs after injury. However, when mice are treated with dexamethasone, an agonist of glucocorticoid receptors, heterotopic ossifications (HO) develop in the injured muscle within fibrotic areas that fail to fully regenerate functional muscle. To understand the mechanisms driving heterotopic ossification in response to glucocorticoid receptor agonists, we performed RNA seqencing analysis on injured muscle. Mice underwent muscle injuries by intramuscular injection of cardiotoxin (CDTX). All mice were treated with either vehicle or dexamethasone (10mg/kg, intraperitoneal injection) daily from day 0-4. polyA+ RNA was isolated from whole muscle 4 days post injury, libraries generated and sequenced. Mice underwent muscle injuries by intramuscular injection of cardiotoxin (CDTX). All mice were injected intraperitoneally daily for 4 days with either saline (group C) or 10mg/kg dexamethasone (group D). RNA was isolated from whole CDTX-injured hindlimb muscle on 4 days post injury. Just prior to tissue harvest, heterotopic ossification development quantified in CDTX-injured muscles by micro computed tomography (µCT). Only 1 mouse (mouse C4) out of 5 in saline group developed heterotopic ossification (0.67mm3) and mouse C4 therefore was excluded in further analysis. On the other hand, all mice in dexamethasone-treated mice developed HO (2.40±5.42 mm3). PolyA+ RNA was then purfied before library construction and sequencing. contributor: UQ Sequencing Facility