A Potential Citrate Shunt in Erythrocytes of PKAN Patients Caused by Mutations in Pantothenate Kinase 2
- Author(s)
- Maike Werning, Martin Brenner, Verena Dobretzberger, Ernst Müllner, Georg Mlynek, Kristina Djinovic-Carugo, David M. Baron, Lena Fragner, Almut Bischoff, Boriana Büchner, Thomas Klopstock, Wolfram Weckwerth, Ulrich Salzer
- Abstract
Pantothenate kinase-associated neurodegeneration (PKAN) is a progressive neurodegenerative disease caused by mutations in the pantothenate kinase 2 (PANK2) gene and associated with iron deposition in basal ganglia. Pantothenate kinase isoforms catalyze the first step in coenzyme A (CoA) biosynthesis. Since PANK2 is the only isoform in erythrocytes, these cells are an excellent ex vivo model to study the effect of PANK2 point mutations on expression/stability and activity of the protein as well as on the downstream molecular consequences. PKAN erythrocytes containing the T528M PANK2 mutant had residual enzyme activities but variable PANK2 abundances indicating an impaired regulation of the protein. Patients with G521R/G521R, G521R/G262R, and R264N/L275fs PANK2 mutants had no residual enzyme activity and strongly reduced PANK2 abundance. G521R inactivates the catalytic activity of the enzyme, whereas G262R and the R264N point mutations impair the switch from the inactive to the active conformation of the PANK2 dimer. Metabolites in cytosolic extracts were analyzed by gas chromatography–mass spectrometry and multivariate analytic methods revealing changes in the carboxylate metabolism of erythrocytes from PKAN patients as compared to that of the carrier and healthy control. Assuming low/absent CoA levels in PKAN erythrocytes, changes are consistent with a model of altered citrate channeling where citrate is preferentially converted to α-ketoglutarate and α-hydroxyglutarate instead of being used for de novo acetyl-CoA generation. This finding hints at the importance of carboxylate metabolism in PKAN pathology with potential links to reduced cytoplasmic acetyl-CoA levels in neurons and to aberrant brain iron regulation.
- Organisation(s)
- Functional and Evolutionary Ecology, Department of Pharmaceutical Sciences, Department of Biochemistry and Cell Biology, Department of Structural and Computational Biology
- External organisation(s)
- Medizinische Universität Wien, St. Anna Kinderkrebsforschung, Boehringer Ingelheim Austria, Veterinärmedizinische Universität Wien, Max F. Perutz Laboratories GmbH (MFPL), Ludwig-Maximilians-Universität München, Deutsches Zentrum für neurodegenerative Erkrankungen
- Journal
- Biomolecules
- Volume
- 12
- DOI
- https://doi.org/10.3390/biom12020325
- Publication date
- 02-2022
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 106002 Biochemistry, 301114 Cell biology
- Keywords
- ASJC Scopus subject areas
- Molecular Biology, Biochemistry
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/a-potential-citrate-shunt-in-erythrocytes-of-pkan-patients-caused-by-mutations-in-pantothenate-kinase-2(ee21e896-c092-48db-8961-dc4252d3c06d).html