Mutations of ATIC and ADSL affect purinosome assembly in cultured skin fibroblasts from patients with AICA-ribosiduria and ADSL deficiency
Abstract
The purinosome is a multienzyme complex composed by the enzymes active in de novo purine synthesis (DNPS) that cells transiently assemble in their cytosol upon depletion or increased demand of purines. Using parallel immunolabeling of various DNPS enzymes and confocal fluorescent microscopy, we proved purinosome assembly in HeLa, HepG2, Saos-2, HEK293, human skin fibroblasts and primary human keratinocytes cultured in purine-depleted media.
Using the identical approach, we proved in cultured skin fibroblasts from patients with AICA-ribosiduria and ADSL deficiency that various mutations of ATIC and ADSL destabilize to various degrees of purinosome assembly and found that the ability to form purinosomes correlates with clinical phenotypes of individual ADSL patients. Our results thus shown that the assembly of functional purinosomes is fully dependent on the presence of structurally unaffected ATIC and ADSL complexes and presumably also on the presence of all the other DNPS proteins.