Regulation of Mechanisms underlying signal transduction via sigma-1 receptor and activity of Tyrosine Hydroxylase.

(1)。Mechanism underlying signal transduction via intracelluar sigma-1 receptors。Expression cloning of sigma-1 receptor(SR1)in Xenopus oocytes showed a binding ability for NE-100，a ligand of sR1，as observed in native tissues.Site-directed mutagenesis in the putative transmembrane(TN)domain of sR1 did not alter expression levels of mutant sR1.NE-100binding was abolished by the double mutation(S99！And LL105-106AA)or by the single mutation(Y103F)。Scatchard analysis using[ii D13齐埃D1H]()pentazocine as a ligand demonstrated that the single mutation(Y103F)resulted in low affinity，however，the double mutation(S99A，LL105-106AA)had no effect。These findings provide evidence that the putative TM domain of sR1 plays a critical role in ligand-binding.(2)。Kinetic Characterization of the nitric oxide(NO)toxicity for PC12cells：effects of half-life time of NO release。Effects of low concentrations of nitric oxide(NO)on cell viability using NO donors.Exposure of…More undifferentiated PC12cells to low concentrations of NO donors resulted in cell death in a dose-and time-dependent manner.The NO-induced cell death was characterized as apoptosis-like cell death。Pretreatment with an antioxidant ascorbic acid completely prevented the cell death.These findings suggest that the cell toxicity induced by NO at low concentrations strongly depends upon the duration of expose to NO from NO-donors.(3)。A novel protein containing cdc10/SWI6 motifs regulates expression of mRNA encoding catecholamine biosynthesizing enzymes.Mechanisms that control expression of catecholaminergic biosynthesizing enzymes in a transmitter phenotype-specific manner，are poorly understood.We provide evidence that overexpression of a novel cdc10SWI6motif-containing protein，V-1，elicits the coordinate up-regulation of above enzymes in PC12D，and catecholamine levels are increased。Furthermore，V-1is strongly expressed in the cytoplasm of rat chromaffin cells of adrenal medulla.Thus，V-1may act as a cytoplasmic protein/protein adapter and be involved in control of the catecholaminergic phenotype expression via an intracellular pathway signaling to the nucleus.Less：Less

(1). Mechanism underlying signal transduction via intracelluar sigma-1 receptors. Expression cloning of sigma-1 receptor (sR1) in Xenopus oocytes showed a binding ability for NE-100, a ligand of sR1, as observed in native tissues. Site-directed mutagenesis in the putative transmembrane (TN) domain of sR1 did not alter expression levels of mutant sR1. [ィイD13ィエD1H]NE-100 binding was abolished by the double mutation (S99! and LL105-106AA) or by the single mutation (Y103F). Scatchard analysis using [ィイD13ィエD1H](+)pentazocine as a ligand demonstrated that the single mutation (Y103F) resulted in low affinity, however, the double mutation (S99A, LL105-106AA) had no effect. These findings provide evidence that the putative TM domain of sR1 plays a critical role in ligand-binding.(2). Kinetic Characterization of the nitric oxide (NO) toxicity for PC12 cells: effects of half-life time of NO release. Effects of low concentrations of nitric oxide (NO) on cell viability using NO donors. Exposure of … More undifferentiated PC12 cells to low concentrations of NO donors resulted in cell death in a dose- and time-dependent manner. The NO-induced cell death was characterized as apoptosis-like cell death. Pretreatment with an antioxidant ascorbic acid completely prevented the cell death. These findings suggest that the cell toxicity induced by NO at low concentrations strongly depends upon the duration of expose to NO from NO-donors.(3). A novel protein containing cdc 10/SWI6 motifs regulates expression of mRNA encoding catecholamine biosynthesizing enzymes. Mechanisms that control expression of catecholaminergic biosynthesizing enzymes in a transmitter phenotype-specific manner, are poorly understood. We provide evidence that overexpression of a novel cdc10SWI6 motif-containing protein, V-1, elicits the coordinate up-regulation of above enzymes in PC12D, and catecholamine levels are increased. Furthermore, V-1 is strongly expressed in the cytoplasm of rat chromaffin cells of adrenal medulla. Thus, V-1 may act as a cytoplasmic protein/protein adapter and be involved in control of the catecholaminergic phenotype expression via an intracellular pathway signaling to the nucleus. Less