title: Oxidative stress and apoptosis in homocystinuria patients with genetic remethylation defects.
abstract: Oxidative stress has been described as a putative disease mechanism in pathologies associated with an elevation of homocysteine. An increased reactive oxygen species (ROS) production and apoptosis rate have been associated with several disorders of cobalamin metabolism, particularly with methylmalonic aciduria (MMA) combined with homocystinuria cblC type. In this work, we have evaluated several parameters related to oxidative stress and apoptosis in fibroblasts from patients with homocystinuria due to defects in the MTR, MTRR, and MTHFR genes involved in the remethylation pathway of homocysteine. We have also evaluated these processes by knocking down the MTRR gene in cellular models, and complementation by transducing the wild-type gene in cblE mutant fibroblasts. All cell lines showed a significant increase in ROS content and in MnSOD expression level, and also a higher rate of apoptosis with similar levels to the ones in cblC fibroblasts. The amount of the active phosphorylated forms of p38 and JNK stress-kinases was also increased. ROS content and apoptosis rate increased in control fibroblasts and in a glioblastoma cell line by shRNA-mediated silencing of MTRR gene expression. In contrast, wild-type MTRR gene corrected mutant cell lines showed a decrease in ROS and apoptosis levels. To the best of our knowledge, this study provides the first evidence that an impaired remethylation capacity due to low MTRR and MTR activity might be partially responsible for stress response.
authors.affiliation: Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa CSIC-UAM, Departamento de Biología Molecular. Universidad Autónoma de Madrid, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), IdiPAZ, Madrid, Spain. erichard@cbm.uam.es
authors.forename: Eva
authors.initials: E
authors.lastname: Richard
authors.forename: Lourdes R
authors.initials: LR
authors.lastname: Desviat
authors.forename: Magdalena
authors.initials: M
authors.lastname: Ugarte
authors.forename: Belén
authors.initials: B
authors.lastname: Pérez
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D005287:Ferredoxin-NADP Reductase / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D005786:Gene Expression Regulation; D005838:Genotype; D006710:Homocysteine / Q000378:metabolism; D006712:Homocystinuria / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism; D008745:Methylation; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D018384:Oxidative Stress / Q000235:genetics*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D006710:Homocysteine; D013482:Superoxide Dismutase; C111241:methionine synthase reductase; D005287:Ferredoxin-NADP Reductase; C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D017853:Phosphotransferases (Alcohol Group Acceptor); C021787:5-methylthioribose kinase; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4