MicroRNA Profiling Identifies miR-196a as Differentially Expressed in Childhood Adrenoleukodystrophy and Adult Adrenomyeloneuropathy

Abstract

X-linked adrenoleukodystrophy (X-ALD) is a peroxisomal disorder caused by mutations in the ABCD1 gene, leading to a defect in the peroxisomal adrenoleukodystrophy protein (ALDP), which inhibits the β-oxidation of very long chain fatty acids (VLCFAs). It is a complex disease where the same mutation in the peroxisomal ABCD1 can lead to clinically diverse phenotypes ranging from the fatal disorder of cerebral ALD (cALD) to mild adult disorder of adrenomyeloneuropathy (AMN). This suggests a role of epigenetic factors/modifier genes in disease progression of X-ALD which is not understood at present. To examine the possible role of microRNA (miRNA) in X-ALD disease mechanisms for differences in cALD and AMN phenotype, we profiled 1008 known miRNA in cALD, AMN, and normal human skin fibroblasts using miScript miRNA PCR array (Qiagen) and selected miRNAs which had differential expression in cALD and AMN fibroblasts. Eleven miRNA which were differentially regulated in cALD and AMN fibroblasts were identified. miR-196a showed a significant differential expression between cALD and AMN and is further characterized for target gene regulation. The predicted role of miR-196a in inhibition of inflammatory signaling factors (IKKα and IKKβ) and ELOVL1 expression suggests the pathological role of altered expression of miR-196a. This study indicates that miR-196a participated in differential regulation of ELOVL1 and inflammatory response between cALD as compared to AMN and may be a possible biomarker to differentiate between cALD and AMN.