Epigenomics signature in X-ALD aligns with impaired oligodendrocyte differentiation

ABSTRACT: X-linked adrenoleukodystrophy (X-ALD) is an inherited disorder characterized by axonopathy and demyelination in the central nervous system and adrenal insufficiency. Main X-ALD phenotypes are: (i) an adult adrenomyeloneuropathy (AMN) with axonopathy in spinal cords, (ii) cerebral AMN with brain demyelination (cAMN) and (iii) a childhood variant, cALD, characterized by severe cerebral demyelination. Loss of function of the ABCD1 peroxisomal fatty acid transporter and subsequent accumulation of very-long-chain fatty acids (VLCFAs) are the common culprits to all forms of X-ALD, an aberrant microglial activation accounts for the cerebral forms. How same mutation in the ABCD1 gene can lead to clinically very distinct phenotypes and what factors account for the dissimilar clinical outcomes and prognosis of X-ALD variants remain elusive. We wonder whether epigenetics mechanisms could answer the lack of genotype-phenotype correlation. We employed Illumina state of the art technology to analyze the differential methylation of over 485,000 CpG sites throughout the entire human genome and used stringent statistical criteria to define differential methylation patterns between brains of cALD, cAMN and age-matched controls. We identified a common X-ALD methylation signature comprising the hypermethylation in genes harboring the trimethylated histone H3K27me3 mark in their promoters, the hypermethylation for genes driven the oligodendrocyte lineage, and the hypomethylation for immune-associated genes. We also examined the methylated differences between cALD and cAMN resulting with differential immune response pathways and concordance methylation levels with phenotype severity. The detected methylation differences correlated with transcriptional and translational consequences, as supported by Affymetrix expression arrays, quantitative PCR and WB changes. The reliability of these changes was further demonstrated by validating DNA methylation by an independent pyrosequencing assay. From these evidences, we propose the altered transcriptional programs in oligodendrocyte differentiation in X-ALD patients. These observations may provide new therapeutic epigenetic agents.

ORGANISM(S): Homo sapiens

PROVIDER: GSE78218 | GEO | 2019/02/01

REPOSITORIES: GEO