Dorfin prevents cell death by reducing mitochondrial localizing mutant superoxide dismutase 1 in a neuronal cell model of familial amyotrophic lateral sclerosis

Abstract Dorfin is a RING-finger type ubiquitin ligase for mutant superoxide dismutase 1 (SOD1) that enhances its degradation. Mutant SOD1s cause familial amyotrophic lateral sclerosis (FALS) through the gain of unelucidated toxic properties. We previously showed that the accumulation of mutant SOD1 in the mitochondria triggered the release of cytochrome c, followed by the activation of the caspase cascade and induction of neuronal cell death. In the present study, therefore, we investigated whether Dorfin can modulate the level of mutant SOD1 in the mitochondria and subsequent caspase activation. We showed that Dorfin significantly reduced the amount of mutant SOD1 in the mitochondria, the release of cytochrome c and the activation of the following caspase cascade, thereby preventing eventual neuronal cell death in a neuronal cell model of FALS. These results suggest that reducing the accumulation of mutant SOD1 in the mitochondria may be a new therapeutic strategy for mutant SOD1-associated FALS, and that Dorfin may play a significant role in this.     

Purine base pattern of camellia irrawadiensis

Theobromine and caffeine in the flush shoot leaves of hybrids of tea and other camellia plants were assayed by HPLC. In C. sinensis and C. taliensis of section Thea the caffeine content exceeded 2% and the theobromine content was below 0.2%. However, in C. irrawadiensis of the same section, the theobromine content was more than 0.5% while the caffeine content was below 0.02%. The theobromine content of tea hybrids was also below 0.2%. In sections other than Thea, C. sasanqua, C. japonica and C. vernalis did not contain detectable amounts of theobromine or caffeine.     

Facile synthesis of peptide–porphyrin conjugates: Towards artificial catalase

A facile synthetic method for peptide–porphyrin conjugates containing four peptide units on one porphyrin was developed using chemoselective reactions. The key building blocks, 5,10,15,20-tetrakis(3-azidophenyl)porphyrin 1 and 5,10,15,20-tetrakis(5-azido-3-pyridyl)porphyrin 2, were efficiently synthesized and used as substrates for two well-known chemoselective reactions, traceless Staudinger ligation and copper-catalyzed azide alkyne cycloaddition (so-called click chemistry). Both reactions gave the desired compounds, and click chemistry was superior for our purpose. To confirm the value of the established methodology, nine peptide–porphyrin conjugates were synthesized, and their catalase- and peroxidase-like activity in water was evaluated. Our synthetic strategy is expected to be valuable for the preparation of artificial heme protein models.     

Isolation of a peptide containing d-amino acid residues that inhibits the α-helix-mediated p53–MDM2 interaction from a one-bead one-compound library

α-Helix-mediated protein–protein interactions (PPIs) are important targets in biological research and drug development. Peptides containing d-amino acid residues are attractive molecules for inhibiting α-helix-mediated PPIs because of their wide surface area and high protease resistance. In this study, a peptide library was constructed using a one-bead one-compound format designed to isolate left-handed α-helical peptides, which are promising molecules as inhibitors of α-helix-mediated PPIs. Screening of the library against an α-helix-mediated PPI between MDM2 and p53 yielded an inhibitor of the PPI. Design and screening of the library, and biochemical and spectroscopic studies of the discovered peptide are presented.