Christopher Bryce Johnson1, Peter Pediaditakis1, Andrey Tikunov1, Douglas Romney2, Haakil Lee1, Ekhson Holmuhamedov2,3, Mike Gamcsik4, Jeffrey MacDonald1
1Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; 2Cell Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; 3The Center of Theoretical Problems of Physico-Chemical Pharmacology, Moscow, Russian Federation; 4Biomedical Engineering, North Carolina State University, Raleigh, NC, USA
The glycine cleavage system (GCS), which is found exclusively in mitochondria, converts glycine to methylene tetrahydrofolate (mTHF), and serine hydroxymethyltransferase (SHMT) uses the mTHF to form serine. A SHMT isoform also exists in the cytosol. When 2-13C glycine is used in place of unlabeled glycine, two pools of serine are formed, a 3-C labeled serine from the mitochondria and a 2-C labeled serine from the cytosolic. We show that MRS can detect the resulting serine pools, and we hypothesize that by analyzing these pools this method can be uses as a non invasive, in vivo detection system of mitochondrial function.