Loss of AMP-activated protein kinase in X-linked adrenoleukodystrophy patient-derived fibroblasts and lymphocytes

Abstract

X-Adrenoleukodystrophy (X-ALD) is a peroxisomal disorder characterized by accumulation of very-long-chain (VLC) fatty acids, which induces inflammatory disease and alterations in cellular redox, both of which are reported to play a role in the pathogenesis of the severe form of the disease (childhood cerebral ALD). While the mutation defect in ABCD1 gene is common to all forms of X-ALD it fails to account for the spectrum of phenotypic variability seen in X-ALD patients, strongly suggesting a role for as yet unidentified modifier gene(s). Here we report, for the first time, loss of AMP-activated protein kinase alpha1 (AMPKα1) in patient-derived fibroblasts and lymphocytes of the severe cerebral form of X-ALD (ALD), and not in the milder adrenomyeloneuropathy (AMN) form. Decrease in AMPK was observed at both protein and mRNA levels. AMPK loss in ALD patient-derived fibroblasts was associated with increased ubiquitination. Using the Seahorse Bioscience XFe96 Flux Analyzer for measuring the mitochondrial oxygen consumption and extracellular acidification rate we show that ALD patient-derived fibroblasts have a significantly lower “metabolic state” than AMN fibroblasts. Unstimulated ALD patient-derived lymphocytes had significantly higher proinflammatory gene expression. Selective AMPK loss represents a novel physiopathogenic factor in X-ALD disease mechanism. Strategies aimed at upregulating/recovering AMPK levels might have beneficial therapeutic effects in X-ALD.