stigmatellin and pyridaben

How genetic and environmental factors interact in Parkinson disease is poorly understood. We have now compared the patterns of vulnerability and rescue of Caenorhabditis elegans with genetic modifications of three different genetic factors implicated in Parkinson disease (PD). We observed that expressing alpha-synuclein, deleting parkin (K08E3.7), or knocking down DJ-1 (B0432.2) or parkin produces similar patterns of pharmacological vulnerability and rescue. C. elegans lines with these genetic changes were more vulnerable than nontransgenic nematodes to mitochondrial complex I inhibitors, including rotenone, fenperoximate, pyridaben, or stigmatellin. In contrast, the genetic manipulations did not increase sensitivity to paraquat, sodium azide, divalent metal ions (Fe(II) or Cu(II)), or etoposide compared with the nontransgenic nematodes. Each of the PD-related lines was also partially rescued by the antioxidant probucol, the mitochondrial complex II activator, D-beta-hydroxybutyrate, or the anti-apoptotic bile acid tauroursodeoxycholic acid. Complete protection in all lines was achieved by combining d-beta-hydroxybutyrate with tauroursodeoxycholic acid but not with probucol. These results show that diverse PD-related genetic modifications disrupt the mitochondrial function in C. elegans, and they raise the possibility that mitochondrial disruption is a pathway shared in common by many types of familial PD.

Topics: 3-Hydroxybutyric Acid; alpha-Synuclein; Amino Acid Sequence; Animals; Animals, Genetically Modified; Antioxidants; Apoptosis; Benzoates; Benzothiazoles; Bile Acids and Salts; Caenorhabditis elegans; Cholagogues and Choleretics; Copper; Disease Models, Animal; Electron Transport Complex I; Gene Deletion; Gene Expression Regulation; Gene Library; Genetic Techniques; Humans; Immunoblotting; Intracellular Signaling Peptides and Proteins; Ions; Iron; Mitochondria; Molecular Sequence Data; Mutagenesis; Mutation; Neurons; Oncogene Proteins; Oxygen Consumption; Paraquat; Parkinson Disease; Polyenes; Probucol; Protein Deglycase DJ-1; Pyrazoles; Pyridazines; RNA, Small Interfering; Rotenone; Sequence Homology, Amino Acid; Sodium Azide; Taurochenodeoxycholic Acid; Thiazoles; Time Factors; Transgenes; Ubiquitin-Protein Ligases

NADH:ubiquinone oxidoreductase (complex I) is the first, largest and most complicated enzyme of the mitochondrial electron transport chain. Photoaffinity labeling with the highly potent and specific inhibitor trifluoromethyldiazirinyl-[(3)H]pyridaben ([(3)H]TDP) labels only the PSST and ND1 subunits of complex I in electron transport particles. PSST is labeled at a high-affinity site responsible for inhibition of enzymatic activity while ND1 is labeled at a low-affinity site not related to enzyme inhibition. In this study we found, as expected, that 13 complex I inhibitors decreased labeling at the PSST site without effect on ND1 labeling. However, there were striking exceptions where an apparent interaction was found between the PSST and ND1 subunits: preincubation with NADH increases PSST labeling and decreases ND1 labeling; the very weak complex I inhibitor 1-methyl-4-phenylpyridinium ion (MPP(+)) and the semiquinone analogue stigmatellin show the opposite effect with increased labeling at ND1 coupled to decreased labeling at PSST in a concentration- and time-dependent manner. MPP(+), stigmatellin and ubisemiquinone have similarly positioned centers of highly negative and positive electrostatic potential surfaces. Perhaps the common action of MPP(+) and stigmatellin on the functional coupling of the PSST and ND1 subunits is initiated by binding at a semiquinone binding site in complex I.

Topics: 1-Methyl-4-phenylpyridinium; Binding Sites; Electron Transport Complex I; Enzyme Inhibitors; Enzyme Stability; Hot Temperature; Molecular Structure; Multienzyme Complexes; NAD; NADH, NADPH Oxidoreductases; Photoaffinity Labels; Polyenes; Pyridazines; Rotenone; Structure-Activity Relationship; Tritium; Ubiquinone