MicroRNA and mRNA Expression Changes in Steroid Naïve and Steroid Treated DMD Patients

BACKGROUND: Duchenne Muscular Dystrophy (DMD) is a recessive X-linked form of muscular dystrophy. Steroid therapy has clinical benefits for DMD patients, but the mechanism remains unclear. OBJECTIVE: This study was designed to identify mRNAs and microRNAs regulated in Duchenne Muscular Dystrophy patients prior to and after steroid therapy. METHODS: Genome wide transcriptome profiling of whole blood was performed to identify mRNAs and microRNAs regulated in DMD patients. RESULTS: The data show many regulated mRNAs and some microRNAs, including some muscle-specific microRNAs (e.g., miR-206), that were significantly altered in blood of young (age 3–10) DMD patients compared to young controls. A total of 95 microRNAs, but no mRNAs, were differentially expressed in older DMD patients compared to matched controls (age 11–20). Steroid treatment reversed expression patterns of several microRNAs (miR-206, miR-181a, miR-4538, miR-4539, miR-606, and miR-454) that were altered in the young DMD patients. As an example, the over-expression of miR-206 in young DMD patients is predicted to down-regulate a set of target genes (e.g., RHGAP31, KHSRP, CORO1B, PTBP1, C7orf58, DLG4, and KLF4) that would worsen motor function. Since steroids decreased miR-206 expression to control levels, this could provide one mechanism by which steroids improve motor function. CONCLUSIONS: These identified microRNA-mRNA alterations will help better understand the pathophysiology of DMD and the response to steroid treatment.