6533b7d1fe1ef96bd125c874

RESEARCH PRODUCT

Inactivation of peroxisomal ABC transporters, ABCD1 and ABCD2 in BV-2 microglial cells : Towards a better understanding of X-linked adrenoleukodystrophy

subject

description

X-linked adrenoleukodystrophy (X-ALD) is a severe neurodegenerative disorder characterized by very-long-chain fatty acid (VLCFA) accumulation resulting from a peroxisomal β-oxidation defect. The disease is caused by mutations in the ABCD1 gene, which encodes for a peroxisomal half ABC transporter predicted, like its closest homologue ABCD2, to participate in the entry of VLCFA-CoA into the peroxisome, the unique site of their β-oxidation. Progress in understanding the physiopathogenesis of X-ALD suffers from the lack of appropriate cell and animal models. Since peroxisomal defects in microglia seem to be a key element of the onset of the disease, we generated four microglial cell lines unable to transport and/or β-oxidize VLCFA into the peroxisome. BV-2 microglial cells were engineered with CRISPR-Cas9 to generate four microglial cell lines deficient in ABCD1, ABCD2, both ABCD1 and ABCD2 or ACOX-1 (the first rate-limiting enzyme of the peroxisomal β-oxidation system). Biochemical defects and lipid content changes associated with VLCFA accumulation but also fatty acids and cholesterol changes were identified in deficient microglia. Ultrastructural investigations confirmed cytosolic lipid inclusions and an increased number of peroxisome and mitochondria. Transcriptomic profiles of deficient microglia are indicative of an impaired plasticity and an impaired capacity to operate the metabolic shift required upon an inflammatory stimulation. Peroxisomal defect is likely to affect phagocytosis and antigen presentation capacity of microglia. Peroxisomal lipid metabolism defect is also suggested to modify cell membranes organization. Altogether, these novel mutant cell lines represent a promising model that should permit identification of new therapeutic targets for this complex neurodegenerative disease.