Molecular cloning and tissue distribution of rat sarcosine dehydrogenase

Abstract

Sarcosine dehydrogenase (SarDH) is a mitochondrial flavoenzyme involved in the oxidative degradation of choline to glycine. The absence of SarDH activity in humans is genetically transmitted and is the cause of an amino acid metabolism disorder called sarcosinemia. Tryptic fragments of the purified enzyme from rat liver were subjected to Edman degradation and the sequences obtained were used to clone the cDNA encoding the full length protein. The deduced amino acid sequence of SarDH shares an overall similarity of 47% with dimethylglycine dehydrogenase (Me 2 GlyDH), another flavoenzyme involved in the mitochondrial choline catabolism with a similar FAD-binding domain. Covalent binding of FAD to SarDH was demonstrated by the observation of strong fluorescence at 530 nm under excitation at 450 nm of the enzyme immunoprecipitated under denaturing conditions from liver extracts. The localization of SarDH immunoreactivity in the mitochondrial matrix was confirmed by Western-blot analysis of purified mitochondrial fractions. Finally, the tissue distribution of SarDH was investigated by Northern-blot analysis of total RNA and Western-blot analysis of total protein from several rat tissues. A strong expression in the liver, but also in the lung, pancreas, kidney, thymus, and oviduct was observed. We therefore suggest that the enzymes of the choline catabolism pathway are important also for metabolism in nonhepatic tissues.

The Tumor Suppressor Activity of the Transmembrane Protein with Epidermal Growth Factor and Two Follistatin Motifs 2 (TMEFF2) Correlates with Its Ability to Modulate Sarcosine Levels

“…S4). Confirming published observations, SARDH mainly localized to the mitochondria (36), with less fluorescence detected in the cytoplasm (Fig. 4A and supplemental Fig.…”

“…This vesicle-like immunoreactivity has also been described in neurons (34,35), and it has been proposed to correspond to vesicles translocating newly synthesized TMEFF2 to the cell surface and/or cleaved TMEFF2 to the nucleus. SARDH has been described essentially as a mitochondrial enzyme (36); however, our results suggest that it can also be found in the cytosol and/or the Golgi apparatus, where it could be interacting with TMEFF2 during trafficking. We predict that this interaction modifies the activity of SARDH and, ultimately, the mitochondrial and/or cytosolic levels of sarcosine.…”

Mammalian MTHFD2L Encodes a Mitochondrial Methylenetetrahydrofolate Dehydrogenase Isozyme Expressed in Adult Tissues

“…Given the membrane association of MTHFD1L and MTHFD2L, it is likely that folate-dependent 1-carbon metabolism occurs at the inner mitochondrial membrane. Mitochondrial serine hydroxymethyltransferase, glycine cleavage system, sarcosine dehydrogenase, and dimethylglycine dehydrogenase have all been reported to be associated with the inner membrane in rat liver mitochondria (55)(56)(57). These enzymes each produce CH 2 -THF from their respective substrates, which can be oxidized by the CH 2 -THF dehydrogenase activity of MTHFD2L.…”

Preclinical Evaluation of 11C-Sarcosine as a Substrate of Proton-Coupled Amino Acid Transporters and First Human Application in Prostate Cancer

“…Briefly, the organ distribution of 11 C-sarcosine was determined in 2 male and 2 female Sprague-Dawley rats at 5 time points (5,15,30,60, and 90 min) using injected doses of 7.4-28 MBq of 11 C-sarcosine. Groups of animals were sacrificed while under isoflurane anesthesia.…”

“…We further determined the volatile 11 C-CO 2 fraction of radioactivity within blood, pancreas, and prostate in 1 animal per time point (15,30, and 60 min after administration). The 11 C-CO 2 fraction ranged from 14% to 21% in blood, 9% to 23% in prostate, and 12% to 24% in pancreas.…”