Long-term combined administration of quercetin and daidzein inhibits quercetin-induced suppression of glutathione antioxidant defenses

In this study, we investigated the effects of long-term administration of quercetin with or without daidzein on glutathione and the enzymes involved in its metabolism in rat liver in vivo. Male Sprague-Dawley rats were divided randomly into four groups and given oral quercetin (20 mg/day) and daidzein (20 mg/day) alone or in combination, or vehicle alone for six weeks. The serum and liver alpha-tocopherol concentrations were significantly increased following administration of quercetin and daidzein alone or in combination. Glutathione concentration and glutathione reductase activity was significantly (p < 0.05) decreased with quercetin treatment, while no such effect was observed with daidzein treatment. Interestingly, decrease in glutathione concentration and glutathione reductase activity by quercetin treatment was inhibited by combined administration of daidzein and quercetin. The malondialdehyde concentration was significantly decreased following administration of quercetin and daidzein alone or in combination. These results suggest that quercetin, but not daidzein, acts as a pro-oxidant agent by decreasing glutathione concentration and glutathione reductase activity. Interestingly, this pro-oxidant effect of quercetin was inhibited by the combined administration of quercetin and daidzein.

Evidence for genistein mediated cytotoxicity and apoptosis in rat brain

The effects of chronic treatment with high doses of genistein, a major isoflavone of soybeans and soy-based products, have yet to be determined and what is known remains controversial. The present study was undertaken to investigate the cytotoxic effects of chronic ingestion of genistein on rat brain in vivo and the observations were compared with results from in vitro studies with primary cultures of cortical neurons. Sprague-Dawley rats were given 2 or 20 mg/day genistein (p.o.) for four weeks. The high dose of genistein (20 mg/day) significantly increased lactate dehydrogenase (LDH) in rat brain tissue homogenates, whereas the low dose of genistein (2 mg/day) decreased LDH. In addition, DNA fragmentation was detected in homogenates of brain tissue from rats receiving either dose of genistein. These results are consistent with those of in vitro studies indicating that high concentrations of genistein caused cytotoxicity and DNA ladder formation in primary cultures of cortical neurons. Genistein decreased the expression of the 32 kDa caspase-3 precursor and increased the levels of cleaved caspase-3 (18 kDa) in both rat brain tissue homogenates and in primary cultures of cortical neurons. Furthermore, expression of poly (ADP-ribose) polymerase (PARP) was also decreased in both experimental systems. These results suggest that chronic administration of genistein at high doses may induce cytotoxicity and apoptosis in the rat brain.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-induced activation of mitogen-activated protein kinase signaling pathway in Jurkat T cells

The present study was performed to examine mitogen-activated protein kinase associated pathways in mediation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced cell apoptosis in cultured Jurkat T cells. TCDD significantly decreased cell viability in a concentration-dependent manner (P<0.05 at 10-300 nM). TCDD (10 nM) also time-dependently decreased cell viability (P<0.05 at 12-48 hr). c-Jun NH2-terminal kinase was significantly phosphorylated with TCDD treatment in a time dependent manner. p38 Mitogen-activated protein kinase was not significantly changed with TCDD treatment. Extracellular signal-regulated protein kinase was significantly phosphorylated with TCDD treatment for 8 hr and gradually returned to baseline. TCDD induced up-regulation of ASK1 and C-Jun, which are up- and down-stream of JNK, respectively, and up-regulation of cytosolic cytochrome c and caspase-3. These results demonstrate that MAPK signaling pathways including JNK and ERK 1/2, are activated with the treatment of TCDD in Jurkat T cells, which suggest that MAPK pathways may be involved in TCDD-induced cell death.

Fluorescence in situ hybridization analysis of nitrifiers in piggery wastewater treatment reactors

Fluorescence in situ hybridization (FISH) was performed to analyze the nitrifying microbial communities in an activated sludge reactor (ASR) and a fixed biofilm reactor (FBR) for piggery wastewater treatment. Heterotrophic oxidation and nitrification were occurring simultaneously in the ASR and the COD and nitrification efficiencies depend on the loads. In the FBR nitrification efficiency also depends on ammonium load to the reactor and nitrite was accumulated when free ammonia concentration was higher than 0.2 mg NH3-N/L. FISH analysis showed that ammonia-oxidizing bacteria (NSO1225) and denitrifying bacteria (RRP1088) were less abundant than other bacteria (EUB338) in ASR. Further analysis on nitrifying bacteria in the FBR showed that Nitrosomonas species (NSM156) and Nitrospira species (NSR1156) were the dominant ammonia-oxidizing and nitrite-oxidizing bacteria, respectively, in the piggery wastewater nitrification system.

Anti- and prooxidant effects of chronic quercetin administration in rats

The present study was performed to investigate the effects of chronic administration of quercetin on lipid peroxidation and glutathione concentration in rat liver. Male Sprague-Dawley rats were divided into two groups, one of which was fed a normal diet and the other a vitamin E-free diet. Each of these groups was divided further into three subgroups and treated with quercetin administered orally at either 2 or 20 mg/day or with vehicle for 4 weeks. The concentrations of alpha-tocopherol in serum and liver increased following quercetin treatment, and these increases were significantly greater in rats maintained on a vitamin E-free diet. Quercetin significantly decreased the concentration of malondialdehyde (an indicator of lipid peroxidation) in the liver and this decrease was more pronounced in vitamin E-deprived rats than in those maintained on a normal diet (55-60% and 25-35% decrease in malondialdehyde concentrations, respectively). Quercetin treatment decreased the glutathione concentration and glutathione reductase activity (40 and 34%, respectively) in the liver significantly and to a similar extent in vitamin E-deprived and -undeprived rats. Collectively, these results suggest that quercetin may act not only as an antioxidant, but also as a prooxidant in rats.

Nonviral vector for efficient gene transfer to human ovarian adenocarcinoma cells

OBJECTIVE

Various strategies have been attempted to design efficient protocols for ovarian cancer gene therapy but there has been little progress in their clinical application. In this study, we formulated and evaluated a new cationic liposome prepared with dioleoyltrimethylaminopropane (DOTAP), 1,2-dioleoyl-3-phosphophatidylethanolamine (DOPE), and cholesterol (Chol) (DDC) for plasmid DNA transfer into ovarian cancer cells.

METHOD

The DDC liposome was prepared by mixing the DOTAP:DOPE:Cholin a 1:0.7:0.3 molar ratio using the extrusion method. Plasmid DNA (pEGFP-C1) and DDC were complexed at various weight ratios to find the optimum condition and the percentage of transfected cells was determined by selecting a green fluorescence protein (GFP) expressing cells in flow cytometry. The transfection efficiency of the DDC liposome was compared with 3[N-(N,N-dimethylaminoethylene) carbamoyl] cholesterol (DC-Chol)/DOPE liposome and commercially available lifopectin.

RESULTS

The optimal transfection of plasmid DNA was achieved at a 1:4 (w/w) ratio of DDC to DNA. The DDC/DNA complex exhibited higher transfection efficiency in human ovarian cancer cells (OVCAR-3 and SK-OV-3 cells) compared to that in other types of cell lines (NCI-NIH:522 and HepG2 cells). Flow cytometric analysis revealed that the DDC/DNA complex exhibited an over fourfold increase in GFP expression levels compared with DC-Chol/DOPE or lipofectin in OVCAR-3 cells. This result was further confirmed by confocal microscopy and RT-PCR analysis.

CONCLUSION

These results suggest that our newly formulated cationic liposome (DDC) appears to be a promising nonviral vector for treating ovarian adenocarcinoma because of its selective high gene transfer ability in ovarian cancer cells.

A divalent recombinant immunotoxin formed by a disulfide bond between the extension peptide chains

Recombinant immunotoxin for the treatment of cancer was made by connecting toxins to 'carcinoma-specific' antibodies that selectively bind to cancer cells, then kills them without harming the normal cells. The divalent recombinant immunotoxin, [B3(Fab)-ext-PE38]2, is a derivative of B3(Fab)-PE38. B3(Fab)-PE38 was made by fusing the Fab domain of the monoclonal antibody (MAb) B3 to PE38, a truncated mutant form of Pseudomonas exotoxin (PE). In this study, B3(Fab)-ext-PE38 was constructed, which has the hinge region of the B3(Fab)-PE38 extended with the peptide extension, G4C(G4S)2, and connected to the C3 connector. The Cys residue of the extension peptide chain makes the disulfide bond between the two Fab domains. The extension sequence (ext) makes the dimerization of B3(Fab)-ext-PE38 easier to form the divalent immunotoxin, because it decreases the steric hindrance between the two PE38s. The constructed genes were expressed in E. coli as inclusion bodies. Polypeptides that were obtained from the inclusion body were refolded, and the active forms were purified. The ID50 values of the divalent molecule, [B3(Fab)-ext-PE38]2, were about 4 ng/ml on A431 cell lines, about 1 ng/ml on CRL1739 cell lines, and 5 ng/ml on MCF-7 cell lines. The [B3(Fab)-ext-PE38]2 showed about a 12-fold higher cytotoxicity on CRL1739 cell lines than B3(scFv)-PE40 did.

Low-density cDNA array-coupled to PCR differential display identifies new estrogen-responsive genes during the postnatal differentiation of the rat hypothalamus

To identify estrogen (E)-responsive genes that may play important roles in the sexual differentiation and maturation of the neuroendocrine hypothalamus, we used mRNA differential display PCR to analyze hypothalamic RNA derived from estrogen-sterilized rats (ESRs). Neonatal rats were s.c.-injected with 100 microg of 17 beta-estradiol-benzoate (EB) for 5 days. Approximately 300 out of more than 2000 RNAs examined displayed a differential expression pattern between hypothalami of the ESR females compared to their 60-day-old controls. EB-dependent expression of these genes was further analyzed by low-density cDNA array using cDNA probe sets reverse-transcribed from the same groups; 98 genes were confirmed to be differentially expressed. We selected 41 clones that showed higher density differences between the two probe sets than mean density difference in control cyclophilin cDNA blots in the cDNA array. After being cloned into pGEM-T vectors, their sequences were analyzed. Homology searches identified four genes as a protein kinase C (PKC)-binding protein, NELL2 (clone 6-1), a thyroid nuclear factor, TTF-1 (9-1), Munc18-1 (17-6), and leuserpin-2 (18-5). The other 22 genes were similar to reported genes or cDNAs such as mouse kinesin-associated protein 3 (KAP3, 8b), mouse IgE binding lectin (15-1), normalized rat brain cDNA (5-1), rat cDNA (8-1) and rat embryonic cDNA (17-1). Fifteen clones such as clone 7-3 showed no match in the GenBank Database. Further characterization of eight clones (17-1, 7-3, 8-1, 5-1, NELL2, KAP3 homolog, IgE binding lectin homolog, and TTF-1) showed that their expression in the adult female rat hypothalamus is sensitive to neonatal treatment with EB. They showed brain-specific expression and moreover, showed an increase in their mRNA level before the initiation of puberty. Some of them showed gender differences in their different postnatal expression pattern. We speculate that further study will demonstrate that many of the E-regulated genes identified in the present study play important roles in the regulation of the sexual differentiation and E-dependent maturation of the hypothalamus.

Implication of co-measured platelet factor 4 in the reliability of the results of the plasma transforming growth factor-beta 1 measurement

We examined the possible alteration of circulating transforming growth factor-beta1 (TGF-beta1) concentrations in a time-dependent fashion in human plasma. Plasma TGF-beta1 was measured three times at 2 week-intervals from each of 12 healthy participants. Platelet factor 4 (PF4) was measured in parallel with TGF-beta1 to estimate the degree of platelet degranulation. TGF-beta1 levels of the second and third plasma samples, in which PF4s were measured as < approximately 1000 IU/ml, were relatively low and fell in a narrow range. However, TGF-beta1 levels of the first samples, in most of which PF4s were > approximately 1000 IU/ml, appeared much higher and more variable than those of the second or third samples. These results indicate that the platelet degranulation accounted for the higher TGF-beta1 levels in the first samples, and thus did not support our initial assumption. We, nevertheless, could propose a useful guidance in the assessment of TGF-beta1 levels in plasma. When the PF4 level is measured as < approximately 1000 IU/ml under our assay conditions, the TGF-beta1 level in a given plasma sample might be accepted as a reliable value considering the effect of platelet degranulation on TGF-beta1 level.

Apoptosis signal-regulating kinase 1 controls the proapoptotic function of death-associated protein (Daxx) in the cytoplasm

Although Daxx (death-associated protein) was first reported to mediate the apoptotic signal from Fas to JNK in the cytoplasm, other data suggested that Daxx is mainly located in the nucleus as a transcriptional regulator. Here, we demonstrated that cellular localization of Daxx could be determined by the relative concentration of a proapoptotic kinase, apoptosis signal-regulating kinase 1 (ASK1) by using immunofluorescence and transcriptional reporter assay. ASK1 sequestered Daxx in the cytoplasm and inhibited the repressive activity of Daxx in transcription. In addition, Daxx was bound to the activated Fas only in the presence of ASK1, accelerating the Fas-mediated apoptosis. These results suggest that Daxx requires ASK1 for its cytoplasmic localization and Fas-mediated signaling. Taken together, we could conclude that ASK1 controls the dual function of Daxx as a transcriptional repressor in the nucleus and as a proapoptotic signal mediator in the cytoplasm.

Thyroxine treatment induces upregulation of renin-angiotensin-aldosterone system due to decreasing effective plasma volume in patients with primary myxoedema

BACKGROUND

In experimental animals and humans, hypothyroidism is associated with fluid retention and generalized oedema, increased antidiuretic hormone (ADH), decreased atrial natriuretic hormone (ANH), and decreased renin-angiotensin-aldosterone system (RAAS), which subsequently can be corrected by thyroid hormone replacement. The purpose of this study was to determine the effect of thyroxine therapy on RAAS and neurohormones affecting water and electrolyte metabolism and the reason for these changes in patients with primary myxoedema.

METHODS

We measured changes in the plasma renin activity (PRA), serum aldosterone (Aldo), ADH, ANH levels, serum and 24 h urinary electrolytes and osmolalities, and cardiac function in 22 female patients with primary myxoedema before and after correction of hypothyroidism. We also evaluated age-, sex-, and BMI-matched 15 healthy control subjects (Cont).

RESULTS

It took an average of 4.3 months (range, 3-9 months) to normalize thyroid function. The mean reductions of body weight and estimated plasma volume were 1.8+/-1.0 kg (P=0.002) and 8.5% (P<0.001), respectively. In addition, serum Na+ and osmolality and the haematocrit were significantly elevated after correction of hypothyroidism (P<0.01 and P<0.001, respectively). Increased F(E)Na and C(OSM) (P<0.05) levels in patients with hypothyroidism (Ho) compared with those in Cont did not change after thyroxine therapy (Eu). However, C(H(2)O), U(E)K, F(E)K, and TTKG levels as well as creatinine clearance (Ccr) were markedly increased in Eu compared with Ho and Cont (P<0.01, respectively). Increased plasma ADH concentration and decreased plasma ANH concentration were normalized compared to Cont after thyroxine therapy (P<0.001 and P<0.01, respectively). Low PRA and serum Aldo concentration in Ho were significantly increased in Eu (P<0.001 and P<0.01, respectively). In addition, increased left ventricular mass index and decreased cardiac output in Ho were normalized compared to Cont after thyroxine therapy (P<0.01, respectively)

CONCLUSIONS

These findings suggest that the exaggerated upregulation of RAAS after correction of hypothyroidism in patients with primary myxoedema is associated with an increase in Ccr and a decrease in plasma volume resulting from water diuresis, natriuresis, osmotic diuresis and inappropriate changes in plasma ADH and ANH levels. The improved renal function coincided with an amelioration of cardiac function. These changes seem to be an adaptive response for preventing excessive plasma volume and weight loss after thyroxine therapy.

Kaposi's sarcoma-associated herpesvirus open reading frame 50 represses p53-induced transcriptional activity and apoptosis

Kaposi's sarcoma-associated herpesvirus (KSHV) open reading frame 50 (ORF50) encodes a viral transcriptional activator which stimulates the transcription of viral early and late genes of KSHV. Here we show that ORF50 represses transcriptional activity of p53 and p53-induced apoptosis through interaction with CREB binding protein (CBP). This inhibitory effect of ORF50 on the transcriptional activity of p53 was relieved by the addition of CBP. ORF50 mutants, which are defective in interaction with CBP, lost the inhibitory effects on p53. Our data provide a framework for delineating the regulatory mechanisms used by KSHV to modulate cellular transcription and the cell cycle.

Role of Receptor-interacting Protein in Tumor Necrosis Factor-α-dependent MEKK1 Activation

Receptor-interacting protein (RIP), a death domain serine/threonine kinase, has been shown to play a critical role in tumor necrosis factor-alpha (TNF-alpha)-induced activation of the nuclear factor-kappaB signaling pathway. We demonstrate here that ectopically expressed RIP induces I-kappaB kinase-beta (IKKbeta) activation in intact cells and that RIP-induced IKKbeta activation can be blocked by a kinase-inactive form of MEKK1, MEKK1(K1253M). Interestingly, RIP physically associated with MEKK1 both in vitro and in vivo. RIP phosphorylated MEKK1 at Ser-957 and Ser-994. Our data also indicate that RIP induced the stimulation of MEKK1 but not MEKK1(S957A/S994A) in transfected cells. Furthermore, overexpressed MEKK1(S957A/S994A) inhibited the RIP-induced activation of both IKKbeta and nuclear factor-kappaB. We also demonstrated that the TNF-alpha-induced MEKK1 activation was defective in RIP-deficient Jurkat cells. Taken together, our results suggest that RIP phosphorylates and activates MEKK1 and that RIP is involved in TNF-alpha-induced MEKK1 activation.

Zn(2+) induces stimulation of the c-Jun N-terminal kinase signaling pathway through phosphoinositide 3-Kinase

Zn(2+), one of the most abundant trace metal ions in mammalian cells, modulates the functions of many regulatory proteins associated with a variety of cellular activities. In the central nervous system, Zn(2+) is highly localized in the cerebral cortex and hippocampus. It has been proposed to play a role in normal brain function as well as in the pathophysiology of certain neurodegenerative disorders. We here report that Zn(2+) induced stimulation of the c-Jun N-terminal kinase (JNK) pathway in mouse primary cortical cells and in various cell lines. Exposure of cells to Zn(2+) resulted in the stimulation of JNK and its upstream kinases including stress-activated protein kinase kinase and mitogen-activated protein kinase kinase kinase. Zn(2+) also induced stimulation of phosphoinositide 3-kinase (PI3K) The Zn(2+)-induced JNK stimulation was blocked by LY294002, a PI3K inhibitor, or by a dominant-negative mutant of PI3Kgamma. Furthermore, overexpression of Rac1N17, a dominant negative mutant of Rac1, suppressed the Zn(2+)- and PI3Kgamma-induced JNK stimulation. The stimulatory effect of Zn(2+) on both PI3K and JNK was repressed by the free-radical scavenging agent N-acetylcysteine. Taken together, our data suggest that Zn(2+) induces stimulation of the JNK signaling pathway through PI3K-Rac1 signals and that the free-radical generation may be an important step in the Zn(2+) induction of the JNK stimulation.

Glutathione S-transferase mu modulates the stress-activated signals by suppressing apoptosis signal-regulating kinase 1

Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase that can activate the c-Jun N-terminal kinase and the p38 signaling pathways. It plays a critical role in cytokine- and stress-induced apoptosis. To further characterize the mechanism of the regulation of the ASK1 signal, we searched for ASK1-interacting proteins employing the yeast two-hybrid method. The yeast two-hybrid assay indicated that mouse glutathione S-transferase Mu 1-1 (mGSTM1-1), an enzyme involved in the metabolism of drugs and xenobiotics, interacted with ASK1. We subsequently confirmed that mGSTM1-1 physically associated with ASK1 both in vivo and in vitro. The in vitro binding assay indicated that the C-terminal portion of mGSTM1-1 and the N-terminal region of ASK1 were crucial for binding one another. Furthermore, mGSTM1-1 suppressed stress-stimulated ASK1 activity in cultured cells. mGSTM1-1 also blocked ASK1 oligomerization. The ASK1 inhibition by mGSTM1-1 occurred independently of the glutathione-conjugating activity of mGSTM1-1. Moreover, mGSTM1-1 repressed ASK1-dependent apoptotic cell death. Taken together, our findings suggest that mGSTM1-1 functions as an endogenous inhibitor of ASK1. This highlights a novel function for mGSTM1-1 insofar as mGSTM1-1 may modulate stress-mediated signals by repressing ASK1, and this activity occurs independently of its well-known catalytic activity in intracellular glutathione metabolism.

Role of phospholipase C-gamma1 in insulin-like growth factor I-induced muscle differentiation of H9c2 cardiac myoblasts

Insulin-like growth factor-I (IGF-I) regulates muscle differentiation through phosphatidylinositol 3-kinase (PI 3-kinase). Also it was recently reported that PI 3-kinase is involved in the activation of phospholipase C-gamma1 (PLC-gamma1). We investigated whether PLC-gamma1 therefore plays a role in IGF-I-induced muscle differentiation using H9c2 rat cardiac myoblasts as a model. IGF-I was able to activate PLC-gamma1 via both PI 3-kinase-dependent and tyrosine phosphorylation-dependent mechanisms in this model. However, PI 3-kinase appeared to play a more important role than tyrosine phosphorylation in IGF-I activation of PLC-gamma1. In addition, PLC-gamma1 activation was independent of Akt/protein kinase B (Akt/PKB). Importantly, PLC-gamma1 was involved in IGF-I-induced muscle differentiation in parallel with Akt/PKB. Taken together, these results suggest that IGF-I regulation of muscle differentiation is dependent on the activation of PLC-gamma1 and Akt/PKB, both of which are downstream mediators of PI 3-kinase.

Glutamine-dependent antiapoptotic interaction of human glutaminyl-tRNA synthetase with apoptosis signal-regulating kinase 1

Glutamine has been known to be an apoptosis suppressor, since it blocks apoptosis induced by heat shock, irradiation, and c-Myc overexpression. Here, we demonstrated that HeLa cells were susceptible to Fas-mediated apoptosis under the condition of glutamine deprivation. Fas ligation activated apoptosis signal-regulating kinase 1 (ASK1) and c-Jun N-terminal kinase (JNK; also known as stress-activated protein kinase (SAPK)) in Gln-deprived cells but not in normal cells, suggesting that Gln might be involved in the activity control of ASK1 and JNK/SAPK. As one of the possible mechanisms for the suppressive effect of Gln on ASK1, we investigated the molecular interaction between human glutaminyl-tRNA synthetase (QRS) and ASK1 and found the Gln-dependent association of the two molecules. While their association was enhanced by the elevation of Gln concentration, they were dissociated by Fas ligation within 5 min. The association involved the catalytic domains of the two enzymes. The ASK1 activity was inhibited by the interaction with QRS as determined by in vitro kinase and transcription assays. Finally, we have shown that QRS inhibited the cell death induced by ASK1, and this antiapoptotic function of QRS was weakened by the deprivation of Gln. Thus, the antiapoptotic interaction of QRS with ASK1 is controlled positively by the cellular concentration of Gln and negatively by Fas ligation. The results of this work provide one possible explanation for the working mechanism of the antiapoptotic activity of Gln and suggest a novel function of mammalian ARSs.

Nitric oxide negatively regulates c-Jun N-terminal kinase/stress-activated protein kinase by means of S-nitrosylation

NO, produced from l-arginine in a reaction catalyzed by NO synthase, is an endogenous free radical with multiple functions in mammalian cells. Here, we demonstrate that endogenously produced NO can suppress c-Jun N-terminal kinase (JNK) activation in intact cells. Treatment of BV-2 murine microglial cells with IFN-gamma induced endogenous NO production, concomitantly suppressing JNK1 activation. Similarly, IFN-gamma induced suppression of JNK1 activation in RAW264.7 murine macrophage cells and rat alveolar macrophages. The IFN-gamma-induced suppression of JNK1 activation in BV-2, RAW264.7, or rat alveolar macrophage cells was completely prevented by N(G)-nitro-l-arginine, a NO synthase inhibitor. Interestingly, the IFN-gamma-induced suppression of JNK1 activation was not affected by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, an inhibitor of guanylyl cyclase. 8-Bromo-cGMP, a membrane-permeant analogue of cGMP, did not change JNK1 activation in intact cells either. In contrast, S-nitro-N-acetyl-dl-penicillamine (SNAP), a NO donor, inhibited JNK1 activity in vitro. Furthermore, a thiol reducing agent, DTT, reversed not only the in vitro inhibition of JNK1 activity by SNAP but also the in vivo suppression of JNK1 activity by IFN-gamma. Substitution of serine for cysteine-116 in JNK1 abolished the inhibitory effect of IFN-gamma or SNAP on JNK1 activity in vivo or in vitro, respectively. Moreover, IFN-gamma enhanced endogenous S-nitrosylation of JNK1 in RAW264.7 cells. Collectively, our data suggest that endogenous NO mediates the IFN-gamma-induced suppression of JNK1 activation in macrophage cells by means of a thiol-redox mechanism.

Structural and functional dissection of human cytomegalovirus US3 in binding major histocompatibility complex class I molecules

The human cytomegalovirus US3, an endoplasmic reticulum (ER)-resident transmembrane glycoprotein, forms a complex with major histocompatibility complex (MHC) class I molecules and retains them in the ER, thereby preventing cytolysis by cytotoxic T lymphocytes. To identify which parts of US3 confine the protein to the ER and which parts are responsible for the association with MHC class I molecules, we constructed truncated mutant and chimeric forms in which US3 domains were exchanged with corresponding domains of CD4 and analyzed them for their intracellular localization and the ability to associate with MHC class I molecules. All of the truncated mutant and chimeric proteins containing the luminal domain of US3 were retained in the ER, while replacement of the US3 luminal domain with that of CD4 led to cell surface expression of the chimera. Thus, the luminal domain of US3 was sufficient for ER retention. Immunolocalization of the US3 glycoprotein after nocodazole treatment and the observation that the carbohydrate moiety of the US3 glycoprotein was not modified by Golgi enzymes indicated that the ER localization of US3 involved true retention, without recycling through the Golgi. Unlike the ER retention signal, the ability to associate with MHC class I molecules required the transmembrane domain in addition to the luminal domain of US3. Direct interaction between US3 and MHC class I molecules could be demonstrated after in vitro translation by coimmunoprecipitation. Together, the present data indicate that the properties that allow US3 to be localized in the ER and bind MHC class I molecules are located in different parts of the molecule.

High glucose-induced intercellular adhesion molecule-1 (ICAM-1) expression through an osmotic effect in rat mesangial cells is PKC-NF-kappa B-dependent

AIMS/HYPOTHESIS

Infiltration of mononuclear cells and glomerular enlargement accompanied by glomerular cell proliferation are very early characteristics of the pathophysiology of diabetes. To clarify the mechanism of early diabetic nephropathy, we measured [3H]-thymidine incorporation and cell numbers to show the influence of a high ambient glucose concentration and the osmotic effect on rat mesangial cell proliferation. We also measured the effect of high glucose on the expression of intercellular adhesion molecule-1 and vascular adhesion molecule-1 by flow cytometry and semiquantitative RT-PCR in mesangial cells and the adhesion of leukocytes to mesangial cells.

METHODS/RESULTS

Cells exposed to high D-glucose (30 mmol/l) caused an increase in [3H]-thymidine incorporation and cell numbers at 24 and 48 h and normalized at 72 h (p < 0.05), whereas these changes were not found in high mannitol (30 mmol/l), IL-1 beta, or TNF alpha-stimulated mesangial cells. Cells exposed to high-glucose (15, 30, or 60 mmol/l) or osmotic agents (L-glucose, raffinose and mannitol) showed that intercellular adhesion molecule-1 expression began to increase after 24 h, reached its maximum at 24 and 48 h and gradually decreased afterwards. The stimulatory effects of high glucose and high mannitol on mRNA expression were observed as early as 6 h and reached its maximum at 12 h. Up-regulation of ICAM-1 protein and mRNA was also found in IL-1-beta and TNF-alpha-stimulated mesangial cells. Neither vascular adhesion molecule-1 protein nor mRNA expression was, however, affected by high glucose and high mannitol. Notably, the protein kinase C inhibitors calphostin C and staurosporine reduced high glucose- or high mannitol-induced intercellular adhesion molecule-1 mRNA expression and high glucose-induced proliferation. Furthermore, the NF-kappa B inhibitor N-tosyl-L-phenylalanine chloromethyl ketone reduced high glucose- or high mannitol-induced intercellular adhesion molecule-1 mRNA expression and high glucose-induced proliferation. Results showed that high glucose (15, 30 mmol/l) or high concentrations of osmotic agents remarkably increased the number of adherent leukocytes to mesangial cells (p < 0.01) compared with control cells (5 mmol/l D-glucose). Functional blocking of intercellular adhesion molecule-1 on mesangial cells with rat intercellular adhesion molecule-1 monoclonal antibody, calphostin C, staurosporine, or N-tosyl-L-phenylalanine chloromethyl ketone significantly inhibited high glucose- or high mannitol-induced increase in leukocyte adhesion (p << 0.05).

CONCLUSION/INTERPRETATION

These results suggest that high glucose can upregulate intercellular adhesion molecule-1 protein and mRNA expression but not vascular adhesion molecule-1 expression in mesangial cells and promote leukocyte adhesion through up-regulation of intercellular adhesion molecule-1 through osmotic effect, possibly depending on the protein kinase C nuclear factor-kappa B (PKC-NF-kappa B) pathway. High glucose itself can also promote mesangial cell proliferation through the PKC-NF-kappa B pathways. We conclude that hyperglycaemia in itself seems to be an important factor in the development of early diabetic nephropathy.

Urinary soluble HLA class I antigen in patients with minimal change disease: a predictor of steroid response

In primary minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS), increased lymphocyte reactivity to renal antigens has been defined. Soluble HLA class I antigen (sHLA-I) is actively secreted by T and B lymphocytes when they are stimulated by mitogens, antigens and lymphokines. To determine if serum and urine sHLA-I levels could predict steroid response in patients with MCD and differentiate those from FSGS, we have investigated 45 healthy controls, biopsy-proven 17 patients with MCD (edema and 24-hour urine protein > 3.5 g/day), 8 patients with FSGS (24-hour urine protein > 1 g/day) and 10 patients with membranous nephropathy (MGN) (24-hour urine protein > 1 g/day). Before and after prednisone therapy (1 mg/kg/day or 2 mg/kg/EOD for 8 weeks), the levels of serum and urinary sHLA-I were measured by ELISA (sHLA-STAT; Sangstat Co., Calif., USA). After 8 weeks of treatment, 10 patients with MCD were responders (MCD-CR) while the other 7 patients with MCD were nonresponders (MCD-NR). Three of 7 patients with MCD-NR were re-biopsied and finally diagnosed as FSGS. They were included in the data of patients with FSGS. In healthy controls, serum sHLA-I was detected (415 +/- 256 ng/ml), but urinary sHLA-I was not. At entry, there were no differences in age, sex, serum Cr and 24-hour urine protein among the patients with MCD-CR, MCD-NR and FSGS, but serum albumin was significantly elevated in patients with FSGS and MGN (p < 0.05). Serum sHLA-I levels were notably elevated in MCD-CR (1,040 +/- 1,066 ng/ ml), in MCD-NR (668 +/- 315 ng/ml) and in FSGS (713 +/- 790 ng/ml), but not in patients with MGN (444 +/- 86 ng/ml) when compared with controls (p < 0.05). On the other hand, urinary sHLA-I levels in MCD-NR (541 +/- 239 ng/mg Cr) and in FSGS (457 +/- 239 ng/mg Cr) were significantly higher than those in MGN (125 +/- 28 ng/mg Cr) and in MCD-CR(100 +/- 42 ng/mg Cr, p < 0.05) and these substantial differences were maintained for 8 weeks. In all patients, serum and urinary sHLA-I levels were not reduced during 8 weeks of steroid therapy. We conclude that elevated serum and urinary sHLA-I levels reflect increased cellular immune response and disease activity in patients with MCD and FSGS. In patients with MCD, urinary sHLA-I may be an easily measurable indicator of predicting steroid response, while MCD-NR with high urinary sHLA-I levels might be re-evaluated for the possibility of FSGS.

Intestinal protein loss in patients with haemorrhagic fever with renal syndrome

BACKGROUND

In haemorrhagic fever with renal syndrome (HFRS) vascular dysfunction has been observed in various organs, but the involvement of the intestine has not yet been reported. This study was performed to evaluate the association of intestinal protein loss in this disease with other clinical parameters reflecting vascular permeability or disease severity.

METHODS

Twenty patients with HFRS were included in this study. Intestinal protein loss was measured by (99m)Tc-human serum albumin ((99m)Tc-HSA) scintigraphy in the acute stage, and quantitative analysis of protein loss was measured by the faecal clearance of alpha 1-antitrypsin (C(AT)) in the acute and the recovery stages. C(AT) was then compared with clinical parameters reflecting disease activity and vascular permeability.

RESULTS

(99m)Tc-HSA scintigraphy was positive in 13 (65%) patients, and C(AT) in the acute stage was significantly increased as compared with C(AT) in the recovery stage (40.5+/-24.1 vs 9.2+/-4.2 ml/day, P<0.001). C(AT) was associated with serum albumin levels, frequency of hypotensive episodes, severity of acute renal failure, and degree of thrombocytopenia.

CONCLUSIONS

Our data suggest that the increased vascular permeability of HFRS is associated with the increased intestinal loss of plasma proteins, which might represent one of the parameters of disease severity in HFRS.

Stereoscopic visual impairment in vascular dementia

Binocular depth perception is mediated by neural pathways that involve thalamic nuclei, the posterior parietal lobe and adjacent gyri, and white matter projections connecting these regions. Vascular dementia results from a variety of pathologic syndromes that can affect these areas, and in the current study is shown to produce associated impairment of stereoacuity or complete stereoblindness. Stereoacuity was relatively more impaired by right than left hemisphere pathology, by cortical than subcortical vascular processes, and by lesions that involved the parietal lobe. The extent of impairment was related to dementia severity as reflected by measures of intelligence, memory, and visual-spatial function. Stereoacuity was unimpaired in age-matched patients with depressive disorders.

Activation of death-inducing signaling complex (DISC) by pro-apoptotic C-terminal fragment of RIP

The two opposite signaling pathways that stimulate NF-kappaB activation and apoptosis are both mediated by tumor necrosis factor receptor 1 (TNFR1) and its cytosolic associated proteins. In this study, we demonstrate that the proteolytic cleavage of receptor interacting protein (RIP) by caspase-8 during TNF-induced apoptosis abrogates the stimulatory role of RIP on TNF-induced NF-kappaB activation. The uncleavable RIPD324A mutant was less apoptotic, but its ability to activate NF-kappaB activation was greater than the wild type counterpart. Ectopic expression of the pro-apoptotic C-terminal fragment of RIP inhibited TNF-induced NF-kappaB activation by suppressing the activity of I-kappaB kinasebeta (IKKbeta) which phosphorylates I-kB, an inhibitor of NF-kappaB, and triggers its ubiquitin-mediated degradation. The C-terminal fragment of RIP also enhanced the association between TNFR1 and death domain proteins including TNFR1 associated death domain (TRADD) and Fas associated death domain (FADD), resulting in the activation of caspase-8 and stimulation of apoptosis. The present study suggest that the C-terminal fragment of RIP produced by caspase-8 activates death-inducing signaling complex (DISC), attenuates NF-kappaB activation, and thereby amplifies the activation of caspase-8 which initiates the downstream apoptotic events. Oncogene (2000) 19, 4491 - 4499.

Central administration of an antisense oligodeoxynucleotide against type I pituitary adenylate cyclase-activating polypeptide receptor suppresses synthetic activities of LHRH-LH axis during the pubertal process

Central administration of an antisense oligodeoxynucleotide against type I pituitary adenylate cyclase-activating polypeptide receptor suppresses synthetic activities of LHRH-LH axis during the pubertal process In the present study, we determined the expression of pituitary adenylate cyclase-activating polypeptide (PACAP) and PACAP receptor type I (PAC1) genes during juvenile development and the pubertal process. Female rats were assigned--based on uterine weights, the presence and abundance of uterine fluid, and their vaginal patency--to one of the following: anestrus (AE), early proestrus (EP), late proestrus (LP) or first estrus (E). The hypothalami from 22-, 24- and 26-day-old animals and from those in the peripubertal phases of AE, EP, LP and E were collected, and the content of PACAP and PAC1 mRNA was assessed. These levels were found to decrease in EP and LP. To determine the effect of PACAP on prepubertal luteinizing hormone-releasing hormone (LHRH) and LH synthesis through PAC1, a PAC1 antisense oligodeoxynucleotide (ODN) was i.c.v.-administered, and mRNA levels of LHRH, LH beta, and LHRH receptor (LHRH-R) were determined. Prepubertal increases in LHRH, LH beta, and LHRH-R mRNA levels were markedly suppressed, and the onset of puberty was delayed by the i.c.v. injection of the antisense PAC1 ODN. These data suggest that PACAP may play a role in the regulation of hypothalamic LHRH neurons, through which it regulates synthetic machinery of pituitary LH, during the pubertal process.

Tissue-specificity, functional characterization and subcellular localization of a rat ubiquitin-specific processing protease, UBP109, whose mRNA expression is developmentally regulated

A cDNA encoding an ubiquitin-specific processing protease, UBP109, in rat skeletal muscle was cloned and its product was characterized. Northern analysis revealed that UBP109 mRNA is highly expressed in testis and spleen, compared with other tissues. Furthermore, in situ hybridization showed that the level of UBP109 mRNA in liver, spinal cord and brain dramatically changed during embryonic development, indicating that the expression of UBP109 mRNA is developmentally regulated. UBP109 was expressed in Escherichia coli and purified to apparent homogeneity using a (125)I-labelled ubiquitin-peptide fusion as a substrate. The purified enzyme cleaved at the C-terminus of the ubiquitin moiety in natural and engineered fusions irrespective of their sizes. UBP109 also released free ubiquitin from poly-His-tagged penta-ubiquitin. Moreover, it released free ubiquitin from poly-ubiquitinated protein conjugates of rabbit reticulocytes. In addition, UBP109 localized to both the cytoplasm and the nucleus and, among three putative nuclear localization sequences, only the one located near the C-terminus is responsible for nuclear localization. These results suggest that UBP109 may play an important role in generation of free ubiquitin from its precursors and its recycling from poly-ubiquitinated protein conjugates, and hence in regulation of ubiquitin-mediated cellular processes, particularly related to embryonic development.

Progesterone increases mRNA levels of pituitary adenylate cyclase-activating polypeptide (PACAP) and type I PACAP receptor (PAC(1)) in the rat hypothalamus

Pituitary adenylate cyclase-activating polypeptide (PACAP) regulates pituitary hormone biosynthesis and secretion through its cognate receptors. PACAP also plays an important role in the regulation of ovarian steroid biosynthesis. If so, there might be a feedback regulation of hypothalamic PACAP synthesis by the pituitary and by ovarian steroids. In the present study, we used RNase protection assays to determine changes in mRNA levels of PACAP and type I PACAP receptor (PAC(1)) under the conditions of ovariectomy and replacement with ovarian steroids. Progesterone (P) alone or in combination with estradiol (E) induced significant increases in PACAP mRNA level in the medial basal hypothalamus (MBH) and PAC(1) mRNA levels in MBH and the preoptic area (POA). This finding suggests that feedback regulation takes place between the ovary and hypothalamic PACAP neurons. P is known to be a major regulatory feedback factor for hypothalamic luteinizing hormone-releasing hormone (LHRH) neurons, but P receptor is not present in these neurons. Therefore, we examined a possible involvement of PACAP in the feedback regulatory pathway of P to LHRH neurons. After an antisense PAC(1) oligodeoxynucleotide (ODN) was i.c.v.-injected into the third ventricle of E and P-treated rats, LHRH mRNA levels were determined. The ODN markedly decreased the P-induced increase in the LHRH mRNA level. Taken together, the present data suggest that PACAP may play a role as a mediator in the regulation of LHRH synthetic machinery by stimulatory feedback of P.

Rb protein down-regulates the stress-activated signals through inhibiting c-Jun N-terminal kinase/stress-activated protein kinase

The Rb protein is the product of the retinoblastoma susceptibility gene and loss of Rb function is detected in many types of human cancers. Rb plays important roles in the regulation of cell proliferation, differentiation, senescence, and apoptotic cell death. Here we show that Rb can physically interact with c-Jun NH(2)-terminal kinase/stress-activated protein kinase (JNK/SAPK), thereby inhibiting intracellular signals mediated by JNK/SAPK. Both in vitro binding and in vitro kinase studies suggest that a carboxyl-terminal domain of Rb containing amino acids 768-928 might be crucial for inhibiting JNK/SAPK. In comparison, Rb did not affect enzymatic activity of either extracellular signal-regulated kinase 1 or p38. Ectopically expressed Rb also abrogated the apoptotic cell death induced by ultraviolet radiation or the activation of MEKK1, an upstream kinase that can stimulate the JNK/SAPK cascade. JNK/SAPK inhibition highlights a novel function of Rb, which may provide a new mechanism by which Rb regulates cell death. JNK/SAPK is a major protein kinase that can be stimulated in response to a variety of cellular stresses. Our results, therefore, suggest that Rb, by inhibiting JNK/SAPK, may act as a negative regulator in stress-activated intracellular signaling cascades.

Correlation between structure of Bcl-2 and its inhibitory function of JNK and caspase activity in dopaminergic neuronal apoptosis

To examine the correlation between the structure of Bcl-2 and its inhibitory function of c-Jun N-terminal kinase (JNK) and caspase activity, we established a dopaminergic neuronal cell line, MN9D overexpressing Bcl-2 (MN9D/Bcl-2) or its structural mutants. The mutants comprised a point mutation in the BH1 (G145A; MN9D/BH1) or BH2 (W188A; MN9D/BH2) domain and a deletion mutation in the C-terminal (MN9D/C22), BH3 (MN9D/BH3), or BH4 (MN9D/BH4) domain. As determined by the TUNEL (terminal deoxynucleotidyltransferase nick end-labeling) and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] reduction assay, apoptotic death of MN9D/Neo cells reached 80-90% within 24 h in response to 1 microM staurosporine. Upon staurosporine treatment, JNK activity increased six- to sevenfold over the basal level within 2-4 h. Treatment of MN9D/Neo with both staurosporine and a caspase inhibitor, Z-VAD, attenuated cell death without suppressing JNK activation. Both staurosporine-induced cell death and JNK activation were attenuated in MN9D/Bcl-2. As determined by cleavage of poly(ADP-ribose) polymerase into 85 kDa, Bcl-2 blocked caspase activity as well. When cells overexpressing one of the Bcl-2 mutants were treated with staurosporine, death was attenuated in MN9D/BH1, MN9D/BH2, and MN9D/C22 but not in MN9D/BH3 and MN9D/BH4. Similarly, both JNK and caspase activation were blocked in MN9D/BH1, MN9D/BH2, and MN9D/C22, whereas they were not suppressed in MN9D/BH3 and MN9D/BH4. Taken together, our data indicate that there exists a close structural and functional correlation of Bcl-2 to JNK and caspase activity in staurosporine-induced dopaminergic neuronal cell death.

Selenite negatively regulates caspase-3 through a redox mechanism

Selenium, an essential biological trace element, exerts its modulatory effects in a variety of cellular events including cell survival and death. In our study we observed that selenite protects HEK293 cells from cell death induced by ultraviolet B radiation (UVB). Exposure of HEK293 cells to UVB radiation resulted in the activation of caspase-3-like protease activity, and pretreatment of the cells with z-DEVD-fmk (N-benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone), a caspase-3 inhibitor, prevented UVB-induced cell death. Interestingly, enzymatic activity of caspase-3-like protease in cell lysates of UVB-exposed cells was repressed in vitro by the presence of selenite. Selenite also inhibited the in vitro activity of purified recombinant caspase-3 in cleaving Ac-DEVD-pNA (N-acetyl-Asp-Glu-Asp-p-nitroanilide) or ICAD(L) (inhibitor of a caspase-activated deoxyribonuclease) and in the induction of DNA fragmentation. The inhibitory action of selenite on a recombinant active caspase-3 could be reversed by sulfhydryl reducing agents, such as dithiothreitol and beta-mercaptoethanol. Furthermore, pretreatment of cells with selenite suppressed the stimulation of the caspase-3-like protease activity in UVB-exposed cells, whereas dithiothreitol and beta-mercaptoethanol reversed this suppression of the enzymatic activity. Taken together, our data suggest that selenite inhibits caspase-3-like protease activity through a redox mechanism and that inhibition of caspase-3-like protease activity may be the mechanism by which selenite exerts its protective effect against UVB-induced cell death.

Role of cytosolic phospholipase A(2) as a downstream mediator of Rac in the signaling pathway to JNK stimulation

Rac is an important regulatory molecule implicated in c-jun N-terminal kinase (JNK) activation in response to stress and cytokines. However, the signaling events that mediate the activation of JNK by Rac are not yet well characterized. To broaden our understanding of downstream mediators that link Rac signals to the JNK pathway, we investigated whether cytosolic phospholipase A(2) (cPLA(2)) is involved in Rac activation of JNK. In this report we demonstrate that either co-transfection with antisense cPLA(2) oligonucleotide or pretreatment with arachidonyltrifluoromethyl ketone (AACOCF3), a potent and specific inhibitor of cPLA(2), inhibits Rac-mediated JNK activation, implying a potential role of cPLA(2) in Rac-signaling to JNK activation. In accordance with this observation, we demonstrate that the addition of exogenous arachidonic acid (AA), a principal product of Rac-activated cPLA(2), or leukotrienes, products of 5-lipoxygenase (5-LO) of AA, caused a specific stimulation of JNK. Together, our findings suggest that cPLA(2) mediates, at least partly, the signaling cascade by which Rac stimulates JNK.

Selenite inhibits the c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) through a thiol redox mechanism

Selenium, an essential biological trace element, has been shown to modulate functions of many regulatory proteins involved in signal transduction and to affect a variety of cellular activities including cell growth, survival, and death. The molecular mechanism by which selenium exerts its action on the cellular events, however, remains unclear. In our present study, we observed that selenite suppresses both the c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) and the p38 mitogen-activated protein kinase pathway in 293T cells. In contrast, selenite had little effect on the extracellular signal-regulated kinase pathway. Furthermore, selenite directly inhibited JNK/SAPK activity in vitro but not the p38 activity. The in vitro inhibition of JNK/SAPK by selenite was reversed by the addition of reducing agents such as dithiothreitol and beta-mercaptoethanol. Replacement of cysteine 116 in JNK1 by serine abolished the inhibitory effect of selenite on JNK1 activity both in vitro and in vivo. Selenite also suppressed a c-Jun-dependent luciferase reporter activity stimulated through the JNK signaling pathway. Taken together, our findings strongly suggest that selenite differentially modulates the mammalian mitogen-activated protein kinase pathways and that it can repress the JNK/SAPK signaling pathway by inhibiting JNK/SAPK through a thiol redox mechanism.

Expression of major piroplasm protein (p33) of Theileria sergenti (Korean isolate) and its immunogenicity in guinea pigs

To investigate the development of a subunit vaccine against theileriosis in cattle, the DNA fragments encoding piroplasm surface protein (p33) of Theileria sergenti of a Korean isolate were expressed in baculoviruses. The expressed p33 was characterized by indirect fluorescent antibody (IFA) and western blotting analysis. The expression of p33 was mainly detected on the surface of infected Sf21 cells by IFA. The immunoblotting analysis revealed the presence of a same molecular weight protein band of p33. The antigenicity of expressed polypeptide was further examined through the inoculation of a guinea pig. The sera of guinea pigs immunized with p33 expressed cell lysate showed similar fluorescent antibody patterns and reacted with the same molecular weight protein of T. sergenti in immunoblotting analysis, thus indicating that this protein can be a promising candidate for a subunit vaccine in the future.

Effects of flavonoids on the growth and cell cycle of cancer cells

In this study, we investigated the cytotoxicities of flavone (F01), 3-hydroxyflavone (F02), 6- hydroxyflavone (F03), 7-hydroxyflavone (F04), 3,6-dihydroxyflavone (F05), 5,7-dihydroxyflavone (F06) and 5,6,7-trihydroxyflavone (F07) to human cancer cells including P- glycoprotein (Pgp)-expressing HCT15 cells and its multidrug resistant subline, HCT15/CL02 cells. We also examined the effects of those flavonoids on the cell cycle of these cancer cells. HCT15/CL02 cells did not reveal resistance to all the flavonoids tested in comparison with HCT15 cells. In cell cycle analysis, all the flavonoids tested, except F01 and F04, reduced the G0/G1 population of SF295 cells at growth inhibitory concentrations, and increased G2/M (F02, F03 and F06) or S (F05 and F07) populations. In addition, F02 and F03 decreased the G2/M and G0/G1 population, and increased the S and G2/M population in HCT15 cells, respectively. Meanwhile, in HCT15/CL02 cells, F02 and F03 decreased the G0/G1 populations and increased the S population. In conclusion, we deemed that the flavonoids tested had diverse cytotoxic mechanisms, and exerted their cell growth inhibitory or killing activity by distinctive ways in different cells.

The possible role of c-fos protein in hypothalamus in sleep disturbance in chronic uremic rats

Sleep disturbance is very common in patients with chronic renal failure, but its mechanism is not clear. The activity of c-fos protein (FOS) in ventrolateral preoptic neurons (VLPO) is associated with the sleep pattern. The purpose of this study was to evaluate the relationship between sleep disturbance and the expression of FOS in VLPO of chronic uremic rats. Chronic uremia was induced by the 5/6 nephrectomized model. The movements of the rats were measured with infrared monitoring during the daytime (8.00-20.00) and nighttime (20.00-8.00). Rats were killed at 10.00 or 16.00 h for the daytime (uremic rats 7, control 8) and at 22.00 h for the nighttime (uremic rats 7, control 9). The expression of FOS in VLPO was examined with the immunohistochemical method. The number of recorded daytime movements in uremic rats was significantly higher than in control rats (458 +/- 185 vs. 222 +/- 41, p < 0.001), but the number of recorded nighttime movements in uremic rats was lower than in control rats (949 +/- 430 vs. 1,618 +/- 261, p < 0.001). In the daytime, the number of FOS immunoreactive cells in uremic rats was lower than in control rats (18.4 +/- 5.3 vs. 42.8 +/- 6.3, p < 0. 001), but there was no difference between two groups in the nighttime (10.8 +/- 8.4 vs. 12.5 +/- 5.1, p = 0.62). There was a strong negative correlation between the number of recorded movements and the number of FOS immunoreactive cells in VLPO (r = -0.700, p < 0.001). This finding suggests that sleep disturbances in chronic uremic rats might be related to the decreased expression of FOS in VLPO.

Oligogalacturonic acid and chitosan reduce stomatal aperture by inducing the evolution of reactive oxygen species from guard cells of tomato and Commelina communis

Stomatal opening provides access to inner leaf tissues for many plant pathogens, so narrowing stomatal apertures may be advantageous for plant defense. We investigated how guard cells respond to elicitors that can be generated from cell walls of plants or pathogens during pathogen infection. The effect of oligogalacturonic acid (OGA), a degradation product of the plant cell wall, and chitosan (beta-1,4-linked glucosamine), a component of the fungal cell wall, on stomatal movements were examined in leaf epidermis of tomato (Lycopersicon esculentum L.) and Commelina communis L. These elicitors reduced the size of the stomatal aperture. OGA not only inhibited light-induced stomatal opening, but also accelerated stomatal closing in both species; chitosan inhibited light-induced stomatal opening in tomato epidermis. The effects of OGA and chitosan were suppressed when EGTA, catalase, or ascorbic acid was present in the medium, suggesting that Ca(2+) and H(2)O(2) mediate the elicitor-induced decrease of stomatal apertures. We show that the H(2)O(2) that is involved in this process is produced by guard cells in response to elicitors. Our results suggest that guard cells infected by pathogens may close their stomata via a pathway involving H(2)O(2) production, thus interfering with the continuous invasion of pathogens through the stomatal pores.

Fetal mouse selenophosphate synthetase 2 (SPS2): biological activities of mutant forms in Escherichia coli

A novel gene, sps2, detected in mouse embryo at the early stages of development has been identified as an analog of the E. coli selenophosphate synthetase gene. Unlike the E. coli enzyme, the presence of selenocysteine in the mouse enzyme is indicated by a TGA codon in the open reading frame of the cDNA. Using an N-FLAG monoclonal antibody, it was shown that the full length N-FLAG-sps2 gene product was expressed in COS-7 cells. To investigate the biological activity of the sps2 gene product in vivo, the mutated sps2 gene, which contains cysteine in the place of the TGA encoded selenocysteine in the wild type, was expressed in the E. coli selD deficient mutant, MB08. Like the E. coli wild type selD gene, the mutant sps2 gene complemented the selD mutation. However, replacement of Cys with either Ala, Ser, or Thr resulted in a loss of ability to complement the selD mutation. The SPS2-CYS protein expressed in E. coli was purified and its catalytic activity was determined. The Km value for ATP was 0.75 mM and Vmax was 9.23 nmole/min/mg protein. These results confirm that the mouse embryonic sps2 gene encodes an eukaryotic selenophosphate synthetase, and that availability of selenophosphate as a selenium donor compound is widespread.

Two distinct mechanisms are involved in 6-hydroxydopamine- and MPP+-induced dopaminergic neuronal cell death: role of caspases, ROS, and JNK

In this study, we examined the possibility that MPTP and 6-hydroxydopamine (6-OHDA) act on distinct cell death pathways in a murine dopaminergic neuronal cell line, MN9D. First, we found that cells treated with 6-OHDA accompanied ultrastructural changes typical of apoptosis, whereas MPP+ treatment induced necrotic manifestations. Proteolytic cleavage of poly-(ADP-ribose)polymerase by caspase was induced by 6-OHDA, whereas it remained uncleaved up to 32 h after MPP+ treatment and subsequently disappeared. Accordingly, 6-OHDA- but not MPP(+)-induced cell death was significantly attenuated in the presence of a broad-spectrum caspase inhibitor, N-benzyloxy-carbonyl-Val-Ala-Asp-fluomethylketone (Z-VAD-fmk). As measured by fluorometric probes, the level of reactive oxygen species (ROS) significantly increased after 6-OHDA treatment. In contrast, the level of dihydroethidium-sensitive ROS following MPP+ treatment remained unchanged while a slight increase in dichlorofluorescin-sentive ROS was temporarily observed. As demonstrated by immunoblot analysis, the level of superoxide dismutase was down-regulated following 6-OHDA treatment, whereas it remained unchanged after MPP+ treatment. Cotreatment of cells with antioxidants such as N-acetylcysteine or Mn(III)tetrakis(4-benzoic acid)porphyrin chloride (MnTBAP, cell-permeable superoxide dismutase mimetic) rescued 6-OHDA- but not MPP(+)-induced cell death, whereas inclusion of catalase or N(G)-nitro-L-arginine had no effect in both cases. In addition, 6-OHDA induced ROS-mediated c-Jun N-terminal kinase (JNK) activation that was attenuated in the presence of N-acetylcysteine or MnTBAP but not catalase or Z-VAD-fmk. In contrast, MPP+ has little effect on JNK activity, indicating that ROS and/or ROS-induced cell death signaling pathway seems to play an essential role in 6-OHDA-mediated apoptosis but not in MPP(+)-induced necrosis in a mesencephalon-derived, dopaminergic neuronal cell line.

Anti-allergic actions of the leaves of Castanea crenata and isolation of an active component responsible for the inhibition of mast cell degranulation

The anti-allergic actions of the leaves of Castanea crenata (Fagaceae) were studied. The water extract demonstrated potent anti-allergic actions in in vivo and in vitro experiments. The oral or intraperitoneal administration of the extract (100 or 200 mg/kg) caused a significant inhibition of the 48 hr-PCA (up to 90%) and the vascular permeability induced by histamine or serotonin in rats (about 80%). The anaphylactic release of beta-hexosaminidase from RBL-2H3 cells was also significantly inhibited by the extract in a dose-dependent manner with an IC50 value of 230 microg/ml. The activity-guided fractionation of the extract, based on the determination of inhibitory effect upon the release of beta-hexosaminidase, led to the isolation of quercetin as an active principle responsible for the inhibition of degranulation.

P-glycoprotein (Pgp) does not affect the cytotoxicity of flavonoids from Sophora flavescens, which also have no effects on Pgp action

Sophoraflavanone, kurarinone (GS08), norkurarinol (GS11), kurarinol (GS12) and kushenol K are cytotoxic flavonoids isolated from Sophora flavescens. In this study, we tested the cytotoxicity of those flavonoids to human cancer cells including P-glycoprotein (Pgp)-expressing HCT15 cells and its multidrug resistant subline, HCT15/CL02 cells. HCT15/CL02 cells revealed resistance to GS08, GS11 and GS12 about 2 fold in comparison with HCT15 cells. Nonetheless, verapamil, a Pgp inhibitor, could not increase the cytotoxicity of all the flavonoids tested. We also investigated that the flavonoids could modulate the Pgp action. At nontoxic concentrations, the flavonoids could not effect on the cytotoxicity of paclitaxel, a well-known Pgp-substrate. The flavonoids also had no effects on the accumulation of rhodamine 123 in all the cells tested at 10 microM. From the results, we concluded that Pgp had no effect on the cytotoxicity of the flavonoids, and the flavonoids also had no effect on the action of Pgp. Our results also suggested that HCT15/CL02 cells had additional mechanisms for drug resistance distinct from Pgp overexpression.

Bovine herpes virus expressing envelope protein (E2) of bovine viral diarrhea virus as a vaccine candidate

The gene encoding the envelope protein (E2) of bovine viral diarrhea virus (BVDV) was expressed under the thymidine kinase (TK) promoter of Korean bovine herpesvirus 1 (BHV-1) isolate. Thymidine kinase negative (TK-) BHV-1 recombinants expressing E2 of BVDV were constructed and the expression of E2 was identified by immunofluorescence and Western blotting. Compared to wild type BHV-1, the recombinant BHV-1 had a delayed cytopathogenic effect in cells. The immunogenicity of the recombinant BHV-1 was examined in guinea pigs and cattle. Although an increase in body temperature was detected for a few days, the inoculated cattle returned to normal temperature with the development of neutralizing antibodies to BVDV.

Cytotoxicity of two novel cisplatin analogues, (CPA)2Pt[DOLYM] and (DACH)Pt[DOLYM], to human cancer cells in vitro

Despite the impressive antitumor activity of cisplatin, two major limitations of the drug, that is severe side effects and drug-resistance of cancer cells, make its use difficult for cancer therapy. These limitations have resulted in a great deal of effort having been expended into structural modifications of cisplatin. In this study, we tested two novel cisplatin analogues, (CPA)2Pt [DOLYM] (COMP-I) and (DACH)Pt[DOLYM] (COMP-II), for the mode of cytotoxic action against human tumor cells comparing with cisplatin and carboplatin in vitro. These two novel analogues had considerable cytotoxic activities against five kinds of human solid tumor cells, and especially COMP-II was more effective on HCT15 colon cancer cells than other compounds. In addition, COMP-II had cytostatic activity at low concentrations (10-0.3 microgram/ml), but other compounds revealed little effect on tumor growth at the low concentration.

Molecular cloning of multiple splicing variants of JIP-1 preferentially expressed in brain

Stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) is activated by a variety of cellular or environmental stresses. Proper regulation of the SAPK/JNK pathway may be critical for cell survival or death under various conditions. In this study, we report the molecular cloning of novel isoforms of JIP-1, which harbor a putative phosphotyrosine interaction domain and a helix-loop-helix domain, as well as an SH3 homologous region in the C terminus. Northern analysis indicates that transcription variant jip-1 is expressed in brain and kidney and transcription variants jip-2 and jip-3 are specifically expressed in brain. In situ hybridization data showed that the hybridized jip messages were heavily concentrated in adult brain, and were particularly enriched in the cerebral cortex and hippocampus, the brain regions vulnerable to pathological states such as hypoxia-ischemia, epilepsy, and Alzheimer's disease. All the deduced protein products of the jip transcription variants appear to have a similar property in that they inhibit the SAPK/JNK stimulation when overexpressed. Inhibition of SAPK activation by overexpression of the novel isoform JIP-2a resulted in suppression of etoposide-induced cell death in a neuroglioma cell line, N18TG. These findings suggest that JIP may play an important role in regulation of the SAPK pathway that is involved in stress-induced cellular responses.

Intravenous calcitriol regresses myocardial hypertrophy in hemodialysis patients with secondary hyperparathyroidism

To evaluate the response of circulating intact parathyroid hormone (iPTH) on myocardial hypertrophy in hemodialysis (HD) patients with secondary hyperparathyroidism (SHPT), echocardiographic and neurohormonal assessments were performed over a 15-week period in 15 HD patients with SHPT before and after calcitriol treatment and 10 HD control patients with SHPT not receiving calcitriol therapy. We prospectively studied a group of 15 patients with significantly elevated iPTH levels (iPTH >450 pg/mL) receiving calcitriol (2 microg after dialysis twice weekly). Clinical assessment, medication status, and biochemical and hematological measurements were performed once a month. Throughout the study, calcium carbonate levels were modified to maintain serum phosphate levels at less than 6 mg/dL, but body weight, antihypertensive medication, and ultrafiltration dose remained constant. In patients treated with calcitriol, an adequate reduction of iPTH levels was found (1,112 +/- 694 v 741 +/- 644 pg/mL; P < 0.05) without changes in values of serum ionized calcium (iCa++), phosphate, or hematocrit. Blood pressure (BP), cardiac output (CO), and total peripheral resistance (TPR) did not significantly change. After 15 weeks of treatment with calcitriol, M-mode echocardiograms showed pronounced reductions in interventricular wall thickness (13.9 +/- 3.6 v 12.8 +/- 3.10 mm; P = 0.01), left ventricular posterior wall thickness (12.5 +/- 2.4 v 11.3 +/- 1.8 mm; P < 0.05), and left ventricle mass index (LVMi; 178 +/- 73 v 155 +/- 61 g/m2; P < 0.01). However, in control patients, these changes were not found after the treatment period. In addition, sequential measurements of neurohormonal mediator levels in patients receiving calcitriol showed that plasma renin (18.5 +/- 12.7 v 12.3 +/- 11.0 pg/mL; P = 0.007), angiotensin II (AT II; 79.7 +/- 48.6 v 47.2 +/- 45.7 pg/mL; P = 0.001), and atrial natriuretic peptide (ANP; 16.6 +/- 9.7 v 12.2 +/- 4.4 pg/mL; P = 0.03) levels significantly decreased, whereas antidiuretic hormone (ADH), epinephrine, and norepinephrine levels did not change significantly. The percent change in LVMi associated with calcitriol therapy had a strong correlation with the percent change in iPTH (r = 0.52; P < 0.05) and AT II (r = 0.47; P < 0.05) levels. We conclude that the partial correction of SHPT with intravenous calcitriol causes a regression in myocardial hypertrophy without biochemical or hemodynamic changes, such as heart rate, BP, and TPR. The changes in plasma levels of iPTH and, secondarily, plasma levels of neurohormones (especially AT II) after calcitriol therapy may have a key role in attenuating ventricular hypertrophy in SHPT.

Ca2+-mediated activation of c-Jun N-terminal kinase and nuclear factor kappa B by NMDA in cortical cell cultures

We examined the possibility that c-Jun N-terminal kinase (JNK) and nuclear factor kappaB (NF-kappaB) might be involved in intracellular signaling cascades that mediate NMDA-initiated neuronal events. Exposure of cortical neurons to 100 microM NMDA induced activation of JNK within 1 min. Activity of JNK was further increased over the next 5 min and then declined by 30 min. Similarly, ionomycin, a selective Ca2+ ionophore, induced activation of JNK. The NMDA-induced activation of JNK was abrogated in the absence of extracellular Ca2+, suggesting that Ca2+ entry is necessary and sufficient for the JNK activation. Immunohistochemistry with anti-NF-kappaB antibody demonstrated nuclear translocation of NF-kappaB within 5 min following NMDA treatment. NMDA treatment also enhanced the DNA binding activity of nuclear NF-kappaB in a Ca2+-dependent manner. Treatment with 3 mM aspirin blocked the NMDA-induced activation of JNK and NF-kappaB. Neuronal death following a brief exposure to 100 microM NMDA was Ca2+ dependent and attenuated by addition of aspirin or sodium salicylate. The present study suggests that Ca2+ influx is required for NMDA-induced activation of JNK and NF-kappaB as well as NMDA neurotoxicity. This study also implies that aspirin may exert its neuroprotective action against NMDA through blocking the NMDA-induced activation of NF-kappaB and JNK.