Involvement of c-Jun N-terminal kinase in amyloid precursor protein-mediated neuronal cell death

Amyloid precursor protein (APP), the precursor of Abeta, has been shown to function as a cell surface receptor that mediates neuronal cell death by anti-APP antibody. The c-Jun N-terminal kinase (JNK) can mediate various neurotoxic signals, including Abeta neurotoxicity. However, the relationship of APP-mediated neurotoxicity to JNK is not clear, partly because APP cytotoxicity is Abeta independent. Here we examined whether JNK is involved in APP-mediated neuronal cell death and found that: (i) neuronal cell death by antibody-bound APP was inhibited by dominant-negative JNK, JIP-1b and SP600125, the specific inhibitor of JNK, but not by SB203580 or PD98059; (ii) constitutively active (ca) JNK caused neuronal cell death and (iii) the pharmacological profile of caJNK-mediated cell death closely coincided with that of APP-mediated cell death. Pertussis toxin (PTX) suppressed APP-mediated cell death but not caJNK-induced cell death, which was suppressed by Humanin, a newly identified neuroprotective factor which inhibits APP-mediated cytotoxicity. In the presence of PTX, the PTX-resistant mutant of Galphao, but not that of Galphai, recovered the cytotoxic action of APP. These findings demonstrate that JNK is involved in APP-mediated neuronal cell death as a downstream signal transducer of Go.     

Daily expression of clock genes in whole blood cells in healthy subjects and a patient with circadian rhythm sleep disorder

In recent years, circadian rhythm sleep disorders in humans have been increasing. Clinical features characteristic of this disorder are well known, but the specific causes remain unknown. However, various derangements of circadian expression of the clock gene are a probable cause of this disease. We have attempted to elucidate the relationship between the expression of the clock genes in whole blood cells and the clinical features characteristic of this disorder. In this study, we indicate the daily expression of clock genes period (Per) 1, 2, 3, Bmal1, and Clock in whole blood cells in 12 healthy male subjects. The peak phase of Per1, Per2, and Per3 appeared in the early morning, whereas that of Bmal1 and Clock appeared in the midnight hours. Furthermore, in one patient case with circadian rhythm sleep disorder, we observed variations of the peak phase in clock genes by treatments such as light therapy, exercise therapy, and medicinal therapy. This study suggested that the monitoring of human clock genes in whole blood cells, which may be functionally important for the molecular control of the circadian pacemaker as well as in suprachiasmatic nucleus, might be useful to evaluate internal synchronization.     

Suppression of oxidative stress in aging NZB/NZW mice: effect of fish oil feeding on hepatic antioxidant status and guanidino compounds

Oxidative stress caused by excessive reactive species (RS) and lipid peroxidation is known to be casually linked to age-related inflammation. To test the hypothesis that fish oil (FO) intake has a beneficial effect on nephritis due to its suppressive action of oxidative stress and the enhancement of antioxidant defenses, we examined the effect of dietary FO on various oxidative stress-related parameters and guanidino compound (GC) levels using (NZB × NZW) F₁ (B/W) mice. These mice were fed diets supplemented with either 5% corn oil (control) or 5% FO. At 4 and 9 months of age, the hepatic oxidative status was estimated by assessing RS generation produced from xanthine oxidase, the prostaglandin pathway and lipid peroxidation. To evaluate the effect of FO on redox status, including antioxidant defenses, GSH and GSSG levels and antioxidant enzyme activities were measured. To correlate the extent of oxidative status with the nephritic condition, creatinine, guanidino acetic acid and arginine levels were measured. Results indicated that increased levels of lipid peroxidation, RS generation and xanthine oxidase activity with age were all significantly suppressed by FO feeding. Furthermore, reduced GSH levels, GSH/GSSG ratio and antioxidant enzyme activities in the FO-fed mice were effectively enhanced compared to the corn oil-fed mice. Among several GCs, the age-related increase of creatinine level was blunted by FO. Based on these results, we propose that dietary FO exerts beneficial effects in aged, nephritic mice by suppressing RS, superoxide and lipid peroxidation, and by maintaining a higher GSH/GSSG ratio and antioxidant enzyme activities.     

Structure-activity relationships of 2-, 4-, or 6-substituted estrogens as aromatase inhibitors

Aromatase, which is responsible for the conversion of androgens to estrogens, is a potential therapeutic target for the selective lowering of estrogen levels in patients with estrogen-dependent breast cancer. To develop a novel class of aromatase inhibitors, we tested series of 2- and 4-substituted (halogeno, methyl, formyl, methoxy, nitro, and amino) estrones (7 and 9), as well as series of 6alpha- and 6beta-substituted (alkyl, phenalkyl, and alkoxy) estrones (13 and 14), and their estradiol analogs (8, 10, 11, and 12) as aromatase inhibitors. All of the inhibitors examined blocked the androstenedione aromatization in a competitive manner. Introduction of halogeno and methyl functions at C-2 of estrone as well as that of a phenalkyl or methyl function at the C-6alpha or C-6beta position markedly increased affinity to aromatase (apparent K(i) value=0.10-0.66 microM for the inhibitors versus 2.5 microM for estrone). 6alpha-Phenylestrone (13c) was the most powerful inhibitor among the estrogens studied, and its affinity was comparable to that of the androgen substrate androstenedione. Estradiol analogs were much weaker inhibitors than the corresponding estrone compounds in each series, indicating that the 17-carbonyl group plays a critical role in the formation of a thermodynamically stable enzyme-inhibitor complex.     

Luteolin inhibits endothelin-1 secretion in cultured endothelial cells

We discovered that luteolin, a typical flavonoid contained in various kinds of plants, inhibits the secretion and gene expression of endothelin-1 (ET-1), a potent vasoconstrictor regulating blood pressure, in porcine aortic endothelial cells. Its ED50 was about 10 microM. In addition, the inhibition of ET-1 by a glycoside compound of luteolin (luteolin-6-C-glucoside) was weak.     

Plankton richness in a eutrophic reservoir (Barra Bonita Reservoir,SP, Brazil)

Species richness of plankton was studied in a eutrophic reservoir (Barra Bonita Reservoir) of the Middle Tietê River, São Paulo State, Brazil, during the period 1985–1986. This reservoir is formed by two rivers: the Tietê and the Piracicaba (the main tributaries), of which the Tiête is more eutrophic, having conductivity and nutrient concentration values twice those of the Piracicaba. In addition, the reservoir is fed by 114 smaller tributaries. Monthly sampling was carried out at three stations representing different environmental conditions: St1 on the Tietê, S2 on the Piracicaba, and St3 at the confluence of the two rivers. For the phytoplankton community, the Piracicaba River (St2) proved the richest site, with a listed 72 species with abundance of Chlorophyta, while St1 and St3 registered 59 and 50 species, respectively, with abundance of Cyanophyta. For the zooplankton community a great difference was not registered in species number at the three stations but the species composition and dominant species of rotifers and copepods were quite different. The occurrence of Mesocyclops meridianus and Metacyclops mendocinus, specific for St2;Mesocyclops ogunnus and Notodiaptomus iheringi, specific for St1, and that of these two species plus Mesocyclops meridianusat St3 shows that the conditions combining at this station were favorable to Mesocyclops meridianus but not to Metacyclops mendocinus. Both for phytoplankton and zooplankton, high values found of species richness were compared to species richness of natural lakes, e.g., Dom Helvecio, a monomictic stable lake in eastern Brazil, and another fifteen lakes in the same region.In conclusion, this work shows that environmental gradients are strong selective factors that enhance plankton richness in eutrophic reservoirs exhibiting environmental instability. This fact could explain the presence of a high number of plankton species associated with a high number of individuals in Barra Bonita Reservoir, supporting the effects of the intermediate disturbance hypothesis.     

Disruption of perlecan binding and matrix assembly by post-translational or genetic disruption of dystroglycan function

Dystroglycan is a cell-surface matrix receptor that requires LARGE-dependent glycosylation for laminin binding. Although the interaction of dystroglycan with laminin has been well characterized, less is known about the role of dystroglycan glycosylation in the binding and assembly of perlecan. We report reduced perlecan-binding activity and mislocalization of perlecan in the LARGE-deficient Large(myd) mouse. Cell-surface ligand clustering assays show that laminin polymerization promotes perlecan assembly. Solid-phase binding assays provide evidence for the first time of a trimolecular complex formation of dystroglycan, laminin and perlecan. These data suggest functional disruption of the trimolecular complex in glycosylation-deficient muscular dystrophy.     

Exacerbation of experimental allergic asthma by augmented Th2 responses in WSX-1-deficient mice

WSX-1 (IL-27R) is a class I cytokine receptor with homology to gp130 and IL-12 receptors and is typically expressed on CD4+ T lymphocytes. Although previous reports have clarified that IL-27/WSX-1 signaling plays critical roles in both Th1 differentiation and attenuation of cell activation and proinflammatory cytokine production during some bacterial or protozoan infections, little is known about the importance of WSX-1 in cytokine-mediated diseases of allergic origin. To this aim, we took advantage of WSX-1-deficient (WSX-1(-/-)) mice and induced experimental asthma, in which Th2 cytokines are central modulators of the pathology. OVA-challenged WSX-1(-/-) mice showed marked enhancement of airway responsiveness with goblet cell hyperplasia, pulmonary eosinophil infiltration, and increased serum IgE levels compared with wild-type mice. Production of Th2 cytokines, which are largely responsible for the pathogenesis of asthma, was augmented in the lung or in the culture supernatants of peribronchial lymph node CD4+ T cells from WSX-1(-/-) mice compared with those from wild-type mice. Surprisingly, IFN-gamma production was also enhanced in WSX-1(-/-) mice, albeit at a low concentration. The cytokine overproduction, thus, seems independent from the Th1-promoting property of WSX-1. These results demonstrated that IL-27/WSX-1 also plays an important role in the down-regulation of airway hyper-reactivity and lung inflammation during the development of allergic asthma through its suppressive effect on cytokine production.