The malate-aspartate shuttle is important for de novo serine biosynthesis
Melissa H. Broeks,
Nils W.F. Meijer,
Denise Westland,
Marjolein Bosma,
Johan Gerrits,
Hannah M. German,
Jolita Ciapaite,
Clara D.M. van Karnebeek,
Ronald J.A. Wanders,
Fried J.T. Zwartkruis,
Nanda M. Verhoeven-Duif,
Judith J.M. Jans
Affiliations
Melissa H. Broeks
Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands; Corresponding author
Nils W.F. Meijer
Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands
Denise Westland
Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands
Marjolein Bosma
Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands
Johan Gerrits
Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands
Hannah M. German
Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands
Jolita Ciapaite
Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands
Clara D.M. van Karnebeek
Emma Center for Personalized Medicine, Departments of Pediatrics and Human Genetics, Amsterdam University Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands; Departments of Pediatrics and Laboratory Medicine, Laboratory Genetic Metabolic Diseases, Amsterdam University Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands
Ronald J.A. Wanders
Departments of Pediatrics and Laboratory Medicine, Laboratory Genetic Metabolic Diseases, Amsterdam University Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands
Fried J.T. Zwartkruis
dLAB, Center for Molecular Medicine, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, the Netherlands
Nanda M. Verhoeven-Duif
Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands
Judith J.M. Jans
Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands; Corresponding author
Summary: The malate-aspartate shuttle (MAS) is a redox shuttle that transports reducing equivalents across the inner mitochondrial membrane while recycling cytosolic NADH to NAD+. We genetically disrupted each MAS component to generate a panel of MAS-deficient HEK293 cell lines in which we performed [U-13C]-glucose tracing. MAS-deficient cells have reduced serine biosynthesis, which strongly correlates with the lactate M+3/pyruvate M+3 ratio (reflective of the cytosolic NAD+/NADH ratio), consistent with the NAD+ dependency of phosphoglycerate dehydrogenase in the serine synthesis pathway. Among the MAS-deficient cells, those lacking malate dehydrogenase 1 (MDH1) show the most severe metabolic disruptions, whereas oxoglutarate-malate carrier (OGC)- and MDH2-deficient cells are less affected. Increasing the NAD+-regenerating capacity using pyruvate supplementation resolves most of the metabolic disturbances. Overall, we show that the MAS is important for de novo serine biosynthesis, implying that serine supplementation could be used as a therapeutic strategy for MAS defects and possibly other redox disorders.
