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X-linked adrenoleukodystrophy (X-ALD) is a congenital metabolic disorder characterized mainly by inflammatory demyelination and adrenal insufficiency. Newborn screening using hexacosanoyl lysophosphatidylcholine (C26:0-LPC) in dried blood spots as a diagnostic marker can successfully identify potential patients with X-ALD and prevent disease onset. C26:0-LPC accumulates in patients with X-ALD, although the machinery synthesizing it has remained unclear. In this study, we focused on phosphatidylcholine (PC) with C26:0-moiety as a precursor of C26:0-LPC. We identified that lysophospholipid acyltransferase 10 (LPLAT10)/LPCAT4/LPEAT2/AGPAT7 is the responsible lysophospholipid acyltransferase that produces PC with C26:0-moiety by transferring C26:0-CoA into 2-acyl-LPC. We also found that LPLAT10 deficiency decreased the amount of C26:0-LPC in fibroblasts from X-ALD patients. Mechanistically, LPLAT10 introduced saturated fatty acids-CoA of various chain lengths as substrates into the sn -1 position of LPC, but did not transfer C26:0-CoA other lysophospholipid classes such as lysophosphatidylethanolamine. Structural analysis revealed that a trimethylamine group of PC was placed between two tryptophan residues (W242 and W244), forming a W-X-W motif, possibly through cation–π interaction. Finally, it was shown that exogenously administered C26:0 free fatty acid- d 4 was preferentially incorporated into sphingolipids in the absence of LPLAT10. These results suggest that C26:0-LPC is produced through acyl-chain remodeling of PC catalyzed by LPLAT10 and accumulates in the plasma from X-ALD patients.
Hama et al. (2025) studied this question.