MicroRNA Regulation of Proinflammatory Response in X-linked Adrenoleukodystrophy

Abstract

The underlying mechanism(s) for development of the inflammatory response in inherited, fatal neurometabolic disease X-linked adrenoleukodystrophy (X-ALD) remain completely unknown. Genetic defect (ABCD1 mutation/ deletion), common to all phenotypes of X-ALD, has failed to explain the development of inflammation only in a subset of patients. In this study we document the novel role of microRNAs (miRNAs) in the development of the inflammatory response in unstimulated ALD patient-derived lymphocytes and Abcd1-knockout (Abcd1-KO) mice mixed glial cells. The levels of proinflammatory cytokine gene expression (inducible nitric oxide synthase [iNOS]) were increased in X-ALD patient-derived lymphocytes. Predictions via the use of online bioinformatics algorithms and confirmed by using miRNA mimic of inhibitor-transfection method (gain- and loss-of-function) revealed the role of miR-323-5p in regulating iNOS expression in X-ALD patient-derived lymphocytes. Functional confirmation of the targets was obtained by using the dual-luciferase assay and western blot analysis. Abcd1-KO mice do not develop the inflammatory response characteristic of the fatal X-ALD phenotype. We recently reported that AMP-activated protein kinase (AMPKα1) deletion induced spontaneous iNOS expression in Abcd1-KO mice mixed glial cells. Here we discover the novel role of miR-323-5p regulating the iNOS response in AMPKα1-deleted Abcd1-KO mice mixed glial cells. This study demonstrated the novel role of miR-323-5p in regulating the inflammatory response in unstimulated X-ALD patient-derived cells and mixed glial cells from Abcd1-KO mice suggesting that these miRNA could function as promising novel therapeutic targets for the treatment of X-ALD.