Skin fibroblasts from pantothenate kinase-associated neurodegeneration patients show altered cellular oxidative status and have defective iron-handling properties

• Published in: Human molecular genetics 2012-09, Vol.21 (18), p.4049-4059
• Main Authors: CAMPANELLA, Alessandro, PRIVITERA, Daniela, GUARALDO, Michela, ROVELLI, Elisabetta, BARZAGHI, Chiara, GARAVAGLIA, Barbara, SANTAMBROGIO, Paolo, COZZI, Anna, LEVI, Sonia
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Case-Control Studies; Catalase - metabolism; Cells, Cultured; Ferritins - metabolism; Fibroblasts - enzymology; Fibroblasts - metabolism; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Humans; Iron - metabolism; Iron-Regulatory Proteins - metabolism; Molecular and cellular biology; Mutation, Missense; Oxidation-Reduction; Oxidative Stress; Pantothenate Kinase-Associated Neurodegeneration - metabolism; Pantothenate Kinase-Associated Neurodegeneration - pathology; Phosphotransferases (Alcohol Group Acceptor) - deficiency; Phosphotransferases (Alcohol Group Acceptor) - genetics; Protein Binding; Protein Carbonylation; Skin - pathology; Superoxide Dismutase - metabolism; Superoxide Dismutase-1
• ISSN: 0964-6906; 1460-2083
• DOI: 10.1093/hmg/dds229

Pantothenate kinase-associated neurodegeneration (PKAN) is a neurodegenerative disease belonging to the group of neurodegeneration with brain iron accumulation disorders. It is characterized by progressive impairments in movement, speech and cognition. The disease is inherited in a recessive manner due to mutations in the Pantothenate Kinase-2 (PANK2) gene that encodes a mitochondrial protein involved in Coenzyme A synthesis. To investigate the link between a PANK2 gene defect and iron accumulation, we analyzed primary skin fibroblasts from three PKAN patients and three unaffected subjects. The oxidative status of the cells and their ability to respond to iron were analyzed in both basal and iron supplementation conditions. In basal conditions, PKAN fibroblasts show an increase in carbonylated proteins and altered expression of antioxidant enzymes with respect to the controls. After iron supplementation, the PKAN fibroblasts had a defective response to the additional iron. Under these conditions, ferritins were up-regulated and Transferrin Receptor 1 (TfR1) was down-regulated to a minor extent in patients compared with the controls. Analysis of iron regulatory proteins (IRPs) reveals that, with respect to the controls, PKAN fibroblasts have a reduced amount of membrane-associated mRNA-bound IRP1, which responds imperfectly to iron. This accounts for the defective expression of ferritin and TfR1 in patients' cells. The inaccurate quantity of these proteins produced a higher bioactive labile iron pool and consequently increased iron-dependent reactive oxygen species formation. Our results suggest that Pank2 deficiency promotes an increased oxidative status that is further enhanced by the addition of iron, potentially causing damage in cells.