title: Glutaric acid and its metabolites cause apoptosis in immature oligodendrocytes: a novel mechanism of white matter degeneration in glutaryl-CoA dehydrogenase deficiency.
abstract: Glutaryl-CoA dehydrogenase deficiency is an inherited metabolic disease characterized by elevated concentrations of glutaric acid (GA) and its metabolites glutaconic acid (GC) and 3-hydroxy-glutaric acid (3-OH-GA). Its hallmarks are striatal and cortical degeneration, which have been linked to excitotoxic neuronal cell death. However, magnetic resonance imaging studies have also revealed widespread white matter disease. Correspondingly, we decided to investigate the effects of GA, GC, and 3-OH-GA on the rat immature oligodendroglia cell line, OLN-93. For comparison, we also exposed the neuroblastoma line SH-SY5Y and the microglia line BV-2 to GA, GC, and 3-OH-GA. Cell viability was measured by metabolism of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium. Flow cytometry was used to assess apoptosis via annexin-V, anti-active caspase-3 antibody, and propidium iodide staining. GA, GC, and 3-OH-GA reduced OLN-93 oligodendroglia cell viability in a dose-dependent manner. Toxicity of GA, GC, and 3-OH-GA was abrogated by preincubation with the pan-caspase inhibitor z-VAD-fmk. Apoptosis but not necrosis was detected at various stages (early: annexin-V; effector: caspase-3) after 24-48 h of incubation with GA, GC, or 3-OH-GA in OLN-93 but not in neuroblastoma or microglia cells. OLN-93 lacked expression of N-methyl-d-aspartate receptors, making classical glutamatergic excitotoxicity an unlikely explanation for the selective toxicity of GA, GC, and 3-OH-GA for OLN-93 cells. GA, GC, and 3-OH-GA directly initiate the apoptotic cascade in oligodendroglia cells. This mechanism may contribute to the white matter damage observed in glutaryl-CoA dehydrogenase deficiency.
authors.affiliation: Department of Neonatology, Charité Campus Virchow-Klinikum, D-13353 Berlin, Germany. bettina.gerstner@charite.de
authors.forename: Bettina
authors.initials: B
authors.lastname: Gerstner
authors.forename: Alexander
authors.initials: A
authors.lastname: Gratopp
authors.forename: Monika
authors.initials: M
authors.lastname: Marcinkowski
authors.forename: Marco
authors.initials: M
authors.lastname: Sifringer
authors.forename: Michael
authors.initials: M
authors.lastname: Obladen
authors.forename: Christoph
authors.initials: C
authors.lastname: Bührer
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D020739:Brain Diseases, Metabolic, Inborn / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D061945:Caspase Inhibitors; D002454:Cell Differentiation; D002460:Cell Line; D005977:Glutarates / Q000378:metabolism / Q000633:toxicity*; D050770:Glutaryl-CoA Dehydrogenase; D006801:Humans; D009410:Nerve Degeneration / Q000139:chemically induced / Q000378:metabolism; D009836:Oligodendroglia / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000172:deficiency* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017470:Receptors, Glutamate / Q000235:genetics / Q000378:metabolism
chemical_list: C108959:3-hydroxyglutaric acid; D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D005977:Glutarates; D012333:RNA, Messenger; D017470:Receptors, Glutamate; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C010971:glutaconic acid; D044925:Oxidoreductases Acting on CH-CH Group Donors; D050770:Glutaryl-CoA Dehydrogenase; C035736:glutaric acid