Nucleotide sequence of envelope protein of Japanese encephalitis virus SA14-14-2 adapted to vero cells

Live attenuated Japanese encephalitis (JE) virus SA(14)-14-2 produced in primary dog kidney cells (PDK) was adapted to Vero cells. In an effort to gain insight into the molecular basis of the biological characteristics of the SA14-14-2(Vero) strain, the 1500 nucleotide sequence encoding the envelope (E) gene which possesses major neutralizing epitopes was determined and compared with the sequences of two other attenuated JE virus strains, SA14-14-2(PHK) and SA14-14-2(PDK). The amino acid sequence of the C-terminal region (a.a. 280-500) was found to be identical for all three strains, while the N-terminal region (a.a. 1-279) shows sequence variation. The distribution of mutations in the N-terminal region was nearly the same among the three attenuated strains, suggesting that the N-terminal sequences might be related with virus-host cell specificity. However, it was found that Lys and Val (a.a. 138 and 176, respectively), known to be responsible for attenuation, are still conserved in SA(14)-14-2(Vero). Animal testing showed that SA(14)-14-2(Vero) has an attenuation phenotype similar to that of the parent SA(14)-14-2(PDK) strain in mice.

A novel anti-ischemic ATP-sensitive potassium channel (K(ATP)) opener without vasorelaxation: N-(6-aminobenzopyranyl)-N'-benzyl-N' '-cyanoguanidine analogue

This paper describes the design, synthesis, and biological evaluation of a novel anti-ischemic compound, (2S,3S,4R)-N-(6-amino-3,4-dihydro-2-dimethoxymethyl-3-hydroxy-2-methyl-2H-benzopyranyl)-N'-benzyl-N"-cyanoguanidine (33), and the structure-activity relationships leading to the discovery of this compound. Compound 33 significantly reduced the myocardial infarct zone to area at risk (IZ/AAR) in the ischemic myocardium rat model with high cardioselectivity. Since the cardioprotective effect of compound 33 is reversed by ATP-sensitive potassium channel (K(ATP)) blockers, its anti-ischemic effect appears to be at least mediated by K(ATP) opening. In addition, compound 33 shows good protective activity on neuronal cells against oxidative stress, and therefore it is suggested that compound 33 may have therapeutic potential both in cardio- and in neuroprotection.

Apoptosis by pan-caspase inhibitors in lipopolysaccharide-activated macrophages

Although apoptosis has been observed in macrophages during the course of infections, the mechanism of apoptosis in activated macrophages is not fully understood. This study shows that pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (ZVAD) or t-butyloxycarbonyl-Asp-fluoromethylketone (Boc-D) caused the death of lipopolysaccharide (LPS)-activated macrophages and RAW 264.7 cells with apoptotic features. The apoptosis was also observed in lipoprotein-treated bacteria but not in CpG oligonucleotide- or flagellin-treated macrophages, indicating a difference of cellular responses downstream of different Toll-like receptors. Consistent with the induction of cell death by pan-caspase inhibitors, no activation of known caspases was detected in LPS-ZVAD-treated cells, suggesting an involvement of unknown proapoptotic caspases in the cell death. ZVAD inhibited the activation of extracellular signal-regulated kinase (ERK) and p38 but not of nuclear factor (NF)-kappa B induced by LPS, suggesting that the ZVAD-sensitive molecule lies upstream of the ERK and p38 pathways but downstream of the divergent site of NF-kappa B and mitogen-activated protein kinases. Our results demonstrate that apoptosis of macrophages induced by LPS+ZVAD is independent from the known proapoptotic caspases and suggest that activity of an unidentified ZVAD-sensitive molecule(s) is involved in the survival of LPS-activated macrophages.

Monitoring of electrokinetic removal of heavy metals in tailing-soils using sequential extraction analysis

This research focused on the monitoring of the electrokinetic removal of heavy metals from tailing-soils, and emphasizes the dependency of removal efficiencies upon their physico-chemical states, as demonstrated by the different extraction methods adopted, which included aqua regia and sequential extraction. The tailing-soils examined contained high concentrations of target metal contaminants (Cd=179mgkg(-1), Cu=207mgkg(-1), Pb=5175mgkg(-1), and Zn=7600mgkg(-1)). The removal efficiencies of the different metals were significantly influenced by their speciations, mobilities and affinities (adsorption capacities) in the soil matrix. The removal efficiencies of mobile and weakly bound fractions, such as the exchangeable fraction were more than 90% by electrokinetic treatment, but strongly bound fractions, such as the organically bound species and residual fraction were not significantly removed (less than 30% removal efficiencies). In accordance with the general sequence of mobilities of heavy metals in soils, the removal efficiencies of more mobile heavy metals (Cd, Cu, and Zn) were higher than that of less mobile heavy metal (Pb).

A purified inactivated Japanese encephalitis virus vaccine made in Vero cells

A second generation, purified, inactivated vaccine (PIV) against Japanese encephalitis (JE) virus was produced and tested in mice where it was found to be highly immunogenic and protective. The JE-PIV was made from an attenuated strain of JE virus propagated in certified Vero cells, purified, and inactivated with formalin. Its manufacture followed current GMP guidelines for the production of biologicals. The manufacturing process was efficient in generating a high yield of virus, essentially free of contaminating host cell proteins and nucleic acids. The PIV was formulated with aluminum hydroxide and administered to mice by subcutaneous inoculation. Vaccinated animals developed high-titered JE virus neutralizing antibodies in a dose dependent fashion after two injections. The vaccine protected mice against morbidity and mortality after challenge with live, virulent, JE virus. Compared with the existing licensed mouse brain-derived vaccine, JE-Vax, the Vero cell-derived JE-PIV was more immunogenic and as effective as preventing encephalitis in mice. The JE-PIV is currently being tested for safety and immunogenicity in volunteers.

Profiling of protein kinases in the neoplastic transformation of human ovarian surface epithelium

OBJECTIVE

The aim of this study was to study the pattern of protein kinase expression in a culture model of epithelial ovarian carcinogenesis.

METHODS

Cultures of normal human ovarian surface epithelium (OSE), OSE from women with BRCA1 mutations, a cell culture model of preneoplastic (SV40 T-antigen-immortalized, nontumorigenic) and neoplastic (SV40-E-cadherin transfected, tumorigenic) OSE, and three ovarian cancer cell lines were used to represent OSE phenotypes of different genetic backgrounds and at different, progressive stages of neoplastic transformation. The protein kinase network signaling was studied by Western blotting, simultaneously using multiple antibodies for specific protein kinases.

RESULTS

High levels of cGMP-dependent protein kinase were found in normal and preneoplastic OSE, but were absent in neoplastic OSE. In contrast, expression of MEK6 was detected exclusively in neoplastic OSE. The expressions of casein kinase II (CK2), p38 mitogen-activated protein kinase (MAPK), cyclin-dependent kinase, and the phosphatidylinositol 3-kinase (PI3K) effectors Akt2 and p70 S6 kinase (S6K) were several-fold higher in neoplastic OSE than in normal OSE, whereas the expressions of the MAPKs extracellular signal-regulated kinases ERK1 and -2 were unchanged. Importantly, constitutive phosphorylation of Akt2 and p70 S6K, as found in neoplastic OSE, was also observed in overtly normal OSE from women with predisposing BRCA1 gene mutations.

CONCLUSIONS

These data demonstrate that different repertoires of downstream signaling proteins, particularly those of the MEK6-p38 MAPK-CK2 pathway and the PI3K pathway, are correlated with phenotypic manifestations of a cell culture model of OSE at progressive stages in the development of ovarian cancer. Changes in PI3K effectors are already found in overtly normal OSE from women with BRCA1 mutations.

Metaxin is required for tumor necrosis factor-induced cell death

We used retrovirus insertion-mediated random mutagenesis and tumor necrosis factor (TNF) selection to generate TNF-resistant lines from L929 cells. The metaxin gene, which encodes a protein located on the outer membrane of mitochondria, was identified to be the gene disrupted in one of the resistant lines. The requirement of metaxin in TNF-induced cell death of L929 was confirmed by the restoration of TNF sensitivity after ectopic reconstitution of metaxin expression. Analysis of the cell death induced by other stimuli revealed that metaxin deficiency-mediated death resistance was selective to certain stimuli. Studies using deletion mutants of metaxin showed that mitochondrial association of metaxin is required for the function of metaxin. Over-expression of truncated metaxin lacking the mitochondria anchoring sequence mimicked metaxin deficiency in wild-type cells. Interfering with metaxin prevented TNF-induced necrotic cell death in L929 cells and apoptosis in MCF-7 cells. Our work has thus defined a novel component in the death pathway used by TNF and some other death stimuli.

Phosphorylation of purified recombinant hepatitis B virus-X protein by mitogen-activated protein kinase and protein kinase C in vitro

The recombinant human hepatitis B virus-X protein (rhHBx) has been expressed as inclusion bodies in Escherichia coli and purified. By sequential dialysis of urea, rhHBx was folded into the native structure, which was demonstrated by both the efficacy of its transcriptional activation of the adenovirus major late promoter, fluorescence and circular dichroism (CD) analysis. The increase in CD values at 220 nm and a corresponding blue shift of the intrinsic fluorescence emission confirmed the ability of HBx to refold in lower concentrations of urea to produce the active protein. After purification and renaturation, the rhHBx protein was found to be phosphorylated by protein kinase C (PKC) and mitogen-activated protein kinase (MAPK). In vivo phosphorylation of HBx was also demonstrated. Although PKC and MAPK enhance the HBx phosphorylation in vitro, neither protein kinase A nor caseine kinase II (CKII) phosphorylate HBx protein, though there are possible substrate residues of both kinases in HBx protein. Phosphoamino acid analysis of the total acid hydrolyzed HBx showed that serine residues can be phosphorylated by PKC or MAPK.

Conversion of Glu-plasminogen to Lys-plasminogen is necessary for optimal stimulation of plasminogen activation on the endothelial cell surface

When Glu-plasminogen is bound to cells, plasmin (Pm) formation by plasminogen (Pg) activators is markedly enhanced compared with the reaction in solution. It is not known whether the direct activation of Glu-Pg by Pg activators is promoted on the cell surface or whether plasminolytic conversion of Glu-Pg to the more readily activated Lys-Pg is necessary for enhanced Pm formation on the cell surface. To distinguish between these potential mechanisms, we tested whether Pm formation on the cell surface could be stimulated in the absence of conversion of Glu-Pg to Lys-Pg. Rates of activation of Glu-Pg, Lys-Pg, and a mutant Glu-Pg, [D646E]Glu-Pg, by either tissue Pg activator (t-PA) or urokinase (u-PA) were compared when these Pg forms were either bound to human umbilical vein endothelial cells (HUVEC) or in solution. ([D646E]Glu-Pg can be cleaved at the Arg(561)-Val(562) bond by Pg activators but does not possess Pm activity subsequent to this cleavage because of the mutation of Asp(646) of the serine protease catalytic triad.) Glu-Pg activation by t-PA was enhanced on HUVEC compared with the solution phase by 13-fold. In contrast, much less enhancement of Pg activation was observed with [D646E]Glu-Pg ( approximately 2-fold). Although the extent of activation of Lys-Pg on cells was similar to that of Glu-Pg, the cells afforded minimal enhancement of Lys-Pg activation compared with the solution phase (1.3-fold). Similar results were obtained when u-PA was used as activator. When Glu-Pg was bound to the cell in the presence of either t-PA or u-PA, conversion to Lys-Pg was observed, but conversion of ([D646E]Glu-Pg to ([D646E]Lys-Pg was not detected, consistent with the conversion of Glu-Pg to Lys-Pg being necessary for optimal enhancement of Pg activation on cell surfaces. Furthermore, we found that conversion of [D646E]Glu-Pg to [D646E]Lys-Pg by exogenous Pm was markedly enhanced ( approximately 20-fold) on the HUVEC surface, suggesting that the stimulation of the conversion of Glu-Pg to Lys-Pg is a key mechanism by which cells enhance Pg activation.

Pulmonary vascular effects of propofol at baseline, during elevated vasomotor tone, and in response to sympathetic alpha- and beta-adrenoreceptor activation

BACKGROUND

This in vivo study had two primary objectives. The first goal was to determine whether the pulmonary vascular effects of propofol depend on the preexisting level of vasomotor tone, and the second was to investigate the effects of propofol on the pulmonary vascular responses to sympathetic alpha- and beta-adrenoreceptor activation.

METHODS

Thirty-one mongrel dogs were chronically instrumented to measure the left pulmonary vascular pressure-flow (LPQ) relation. Left lung autotransplantation (LLA) was also performed in eight additional dogs to induce a long-term increase in pulmonary vascular resistance. LPQ plots were measured on separate days in the conscious state and during propofol anesthesia. LPQ plots were measured at baseline and when vasomotor tone was acutely increased with the alpha agonist, phenylephrine, or the thromboxane mimetic, U46619. In separate experiments, cumulative dose-response curves to alpha- (phenylephrine) and beta- (isoproterenol) adrenoreceptor agonists were generated in conscious and propofol-anesthetized dogs.

RESULTS

Compared with the conscious state, propofol had no effect on the baseline LPQ relation in normal or post-LLA dogs. However, propofol caused pulmonary vasoconstriction (P < 0.05) when vasomotor tone was acutely increased with either phenylephrine or U46619 in normal or post-LLA dogs. The pulmonary vasoconstrictor response to alpha-adrenoreceptor activation was potentiated (P < 0.05) during propofol anesthesia, whereas the pulmonary vasodilator response to beta-adrenoreceptor activation was not altered.

CONCLUSION

These results indicate that the pulmonary vascular response to propofol anesthesia is tone-dependent. During sympathetic activation, propofol may favor alpha-adrenoreceptor-mediated vasoconstriction over beta-adrenoreceptor-mediated vasodilation.

Dose-dependent pharmacokinetics of a new reversible proton pump inhibitor, DBM-819, after intravenous and oral administration to rats: hepatic first-pass effect

The dose-dependent pharmacokinetic parameters of DBM-819 were evaluated after intravenous (5, 10 and 20 mg/kg) and oral (10, 20 and 50 mg/kg) administrations of the drug to rats. The hepatic first-pass effect was also measured after intravenous and intraportal administrations of the drug, 10 mg/kg, to rats. After intravenous administration, the dose-normalized (based on 5 mg/kg) area under the plasma concentration-time curve from time zero to time infinity, AUC, at 20 mg/kg (27.0 and 45.8 microg min/ml) was significantly greater than that at 5 mg/kg due to saturable metabolism. After oral administration, the dose-normalized (based on 10 mg/kg) AUC(0-12 h) at 50 mg/kg (25.1, 18.3 and 49.2 microg min/ml) was significantly greater than those at 10 and 20 mg/kg again due to saturable metabolism. After oral administration of DBM-819, 10 mg/kg, 2.86% of oral dose was not absorbed and the extent of absolute oral bioavailability (F) was estimated to be 46.7%. After intraportal administration of DBM-819, 10 mg/kg, the AUC was 51.9% of intravenous administration, suggesting that approximately 48.1% was eliminated by liver (hepatic first-pass effect). The considerable hepatic first-pass effect of DBM-819 was also supported by significantly greater AUC of M3 (3.70 and 6.86 microg min/ml), a metabolite of DBM-819, after intraportal administration. The AUCs of DBM-819 were not significantly different (comparable) between intraportal and oral administrations of the drug, 10 mg/kg, suggesting that gastrointestinal first-pass effect of DBM-819 was almost negligible in rats. At 10 mg/kg oral dose of DBM-819, the hepatic first-pass effect was approximately 48.1%, F was approximately 46.7 and 2.86% was not absorbed from gastrointestinal tract in rats.

Vitamin E improves microsomal phospholipase A2 activity and the arachidonic acid cascade in kidney of diabetic rats

The purpose of the present study was to investigate the effects of vitamin E on microsomal phospholipase A2 activity and the arachidonic acid cascade in the kidneys of streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley male rats weighing 100 +/- 10 g were randomly assigned to one normal and three STZ-induced diabetic groups. The diabetic groups were fed a vitamin E-free diet (the DM-0E group), 40 mg vitamin E/kg diet (the DM-40E group) or a 400 mg vitamin E/kg diet (the DM-400E group). The kidney vitamin E concentrations were 59 and 49% lower in the DM-0E and DM-40E groups, respectively, than in the normal group. The kidney thiobarbituric acid reactive substance concentrations in the DM-0E, DM-40E and DM-400E groups were 119, 84 and 33% greater, respectively, than that in the normal group. The concentration in the DM-400E group was 39% lower than that in the DM-0E group. The phospholipase A2 (PLA2) activity in the kidney microsomes of the DM-0E-40E and DM-400E groups were 88, 58 and 35% greater, respectively, than that in the normal group. The activity in the DM-400E group was 28% lower than that in the DM-0E group and 16% lower than that in the DM-40E group. The differences in the phospholipids in the kidney microsomes included reductions in the phosphatidylcholine and phosphatidylethanolamine compositions. Phosphatidylethanolamine hydrolysis in the kidney microsomes of the DM-0E and DM-40E groups were 84 and 64%, which did not differ from the DM-400E group. The formation of thromboxane A2 (TXA2) in the kidney microsomes was 137 and 70% greater in the DM-0E and DM-40E groups, respectively, than in the normal group. TXA2 formation did not differ between the DM-400E and normal groups. The formation of prostacyclin in the kidney microsomes was 60 and 44% lower in the DM-0E and DM-40E groups, respectively, than in the normal group, whereas the DM-400E group did not differ from that in the normal group. The ratio of prostacyclin to TXA2 was 82 and 65% lower than normal in the DM-0E and DM-40E groups, respectively. Kidney function appears to be improved by vitamin E supplementation due to its antithrombus action, which in turn controls the arachidonic acid cascade system.

High-performance liquid chromatographic analysis of a new neuroprotective agent for ischemia-reperfusion damage, KR-31378

A high-performance liquid chromatographic method was developed for the determination of a neuroprotective agent for ischemia-reperfusion damage, KR-31378, in human plasma and urine and in rat tissue homogenates. The method involved deproteinization of the the biological samples with 0.5 volumes of saturated Ba(OH)2, 0.5 volumes of 0.04 M ZnSO4 and 1 volume of acetonitrile. A 80-microl aliqout of the supernatant was injected onto a reversed-phase C18 column. The mobile phase, 50 mM triethylamine acetate : acetonitrile : tetrahydrofuran (65:30:5, v/v/v), was run at a flow rate of 1.0 ml/min. The column effluent was mornitored by a ultraviolet detector set at 310 nm. The retention time of KR-31378 was approximately 6.5 min. The detection limits of KR-31378 in human plasma and urine and rat tissue homogenates were 0.2, 0.5 and 0.5 microg/ml, respectively. The coefficients of variation (within-day and between-day) were below 13.6% for human plasma and urine and rat homogenates. No interferences from endogenous substances were found.

Hypersensitivity pneumonitis caused by Fusarium napiforme in a home environment

BACKGROUND

We report a case of hypersensitivity pneumonitis (HP) in a 17-year-old male student caused by Fusarium napiforme found in his home environment.

METHODS

The patient was diagnosed according to history, chest radiograph, spirometry, high-resolution chest CT, and transbronchial lung biopsy. To identify the causative agent, cultured aeromolds were collected by the open-plate method. From the main fungi cultured, fungal antigens were prepared, and immunoblot analysis with the patient's serum and each fungal antigen was performed.

RESULTS

Five fungal species were isolated from the patient's home. Immunoblotting analysis with the patient's serum demonstrated more than 10 IgG-binding fractions to F. napiforme extract only, while little binding was noted with the other fungal antigens.

CONCLUSIONS

We should be aware that HP may be caused by F. napiforme in the home environment.

Flavohemoglobin Hmp affords inducible protection for Escherichia coli respiration, catalyzed by cytochromes bo' or bd, from nitric oxide

Respiration of Escherichia coli catalyzed either by cytochrome bo' or bd is sensitive to micromolar extracellular NO; extensive, transient inhibition of respiration increases as dissolved oxygen tension in the medium decreases. At low oxygen concentrations (25-33 microm), the duration of inhibition of respiration by 9 microm NO is increased by mutation of either oxidase. Respiration of an hmp mutant defective in flavohemoglobin (Hmp) synthesis is extremely NO-sensitive (I(50) about 0.8 microm); conversely, cells pre-grown with sodium nitroprusside or overexpressing plasmid-borne hmp(+) are insensitive to 60 microm NO and have elevated levels of immunologically detectable Hmp. Purified Hmp consumes O(2) at a rate that is instantaneously and extensively (>10-fold) stimulated by NO due to NO oxygenase activity but, in the absence of NO, Hmp does not contribute measurably to cell oxygen consumption. Cyanide binds to Hmp (K(d) 3 microm). Concentrations of KCN (100 microm) that do not significantly inhibit cell respiration markedly suppress the protection of respiration from NO afforded by Hmp and abolish NO oxygenase activity of purified Hmp. The results demonstrate the role of Hmp in protecting respiration from NO stress and are discussed in relation to the energy metabolism of E. coli in natural O(2)-depleted environments.

Dose-dependent pharmacokinetics of a new neuroprotective agent for ischemia-reperfusion damage, KR-31378, in rats

The dose-dependent pharmacokinetic parameters of a new neuroprotective agent for ischemia-reperfusion damage, KR-31378, were evaluated after intravenous and oral administration, 10, 20, and 50 mg/kg, to rats. After intravenous administration of 50 mg/kg, the dose-normalized (10 mg/kg) AUC (994 microg min/mL) was significantly greater than that at 10 (569 microg min/ml) and 20 (660 microg min/mL) mg/kg. This could be due to slower clearance (Cl) with increasing dosage (18.5, 14.6, and 10.2 mL/min/kg for 10, 20, and 50 mg/kg, respectively). The slower Cl with increasing dosage could be due to saturable metabolism of KR-31378 in rats and this could be supported by significantly slower Cl(nr) and significantly greater 24-h urinary excretion of the drug at 50 mg/kg than those at 10 and 20 mg/kg. After oral administration of 50 mg/kg, the dose-normalized (10 mg/kg) AUC (1160 microg min/mL) was significantly greater than that at 10 (572 microg min/mL) and 20 (786 microg min/mL) mg/kg. Note that the AUCs were comparable (not significantly different) between intravenous and oral administration at each dosage, indicating that the absorption from gastrointestinal tract was almost complete and the first-pass (gastric, intestinal, and hepatic) effect was not considerable after oral administration to rats.

KR 31372, a benzopyran derivative, inhibits oxidized LDL-stimulated proliferation and migration of vascular smooth muscle cells

KR 31372 is a benzopyran derivative. Both [3H]thymidine incorporation and migrations (chemotactic and wound-edge) of cultured smooth muscle cells (SMCs) were greatly stimulated by oxidized low-density lipoprotein (LDL). These effects were significantly suppressed by KR 31372 (10(7) - 10(6) M) and PDGF-BB antibody (10(8) - 10(6) M). Preincubation with KR 31372 led to a decrease in the synthesis of PDGF-BB-like immunoreactivity (PDGF-BB-LI) that had been stimulated by oxidized LDL. Otherwise, KR 31372 and probucol strongly inhibited the production of thiobarbituric acid reactive substances (TBARS) caused by the incubation of LDL with Cu2+ ion, and significantly reduced the intracellular oxidative stress when stimulated with H,O2. Taken together, it is suggested that KR 31372 may inhibit the oxidized LDL-stimulated syntheses of DNA and PDGF-BB, and migration of the SMCs, in part, via the antioxidant activity.

Propofol selectively attenuates endothelium-dependent pulmonary vasodilation in chronically instrumented dogs

BACKGROUND

The objective was to investigate the effects of propofol anesthesia on the pulmonary vascular response to endothelium-dependent and -independent vasodilators, compared with the responses measured in the conscious state.

METHODS

Twenty-six conditioned, male, mongrel dogs were instrumented long-term to measure the left pulmonary vascular pressure-flow relation. Pressure-flow plots were measured on separate days in conscious and propofol-anesthetized (5.0 mg/kg plus 0.5 mg. kg-1. min-1 intravenously) dogs at baseline, after preconstriction with the thromboxane mimetic U46619, and during the cumulative intravenous administration of endothelium-dependent (acetylcholine and bradykinin) and -independent (proline-nitric oxide) vasodilators.

RESULTS

Propofol had no effect on the baseline pressure-flow relation compared with the conscious state. A lower (P < 0.05) dose of U46619 was necessary to achieve the same degree of preconstriction during propofol anesthesia. The pulmonary vasodilator responses to bradykinin and proline-nitric oxide were similar in the conscious and propofol-anesthetized states. In contrast, the pulmonary vasodilator response to acetylcholine was markedly attenuated (P < 0.01) during propofol anesthesia. The intralipid vehicle for propofol had no effect on the acetylcholine dose-response relation.

CONCLUSION

These results suggest that propofol causes a specific defect in the signal transduction pathway for acetylcholine-induced pulmonary vasodilation. This defect involves the endothelial and not the vascular smooth muscle component of the response.

Stress-induced activation of protein kinase CK2 by direct interaction with p38 mitogen-activated protein kinase

Protein kinase CK2 has been implicated in the regulation of a wide range of proteins that are important in cell proliferation and differentiation. Here we demonstrate that the stress signaling agents anisomycin, arsenite, and tumor necrosis factor-alpha stimulate the specific enzyme activity of CK2 in the human cervical carcinoma HeLa cells by up to 8-fold, and this could be blocked by the p38 MAP kinase inhibitor SB203580. We show that p38alpha MAP kinase, in a phosphorylation-dependent manner, can directly interact with the alpha and beta subunits of CK2 to activate the holoenzyme through what appears to be an allosteric mechanism. Furthermore, we demonstrate that anisomycin- and tumor necrosis factor-alpha-induced phosphorylation of p53 at Ser-392, which is important for the transcriptional activity of this growth suppressor protein, requires p38 MAP kinase and CK2 activities.

Cyclic GMP-dependent and -independent regulation of MAP kinases by sodium nitroprusside in isolated cardiomyocytes

Sodium nitroprusside (SNP) elicits various physiological effects, in part through generation of the membrane permeable mediator nitric oxide (NO). In the heart, besides its role in regulating contractility, NO is involved in both protection from and induction of cellular damage. The present study investigated the role of SNP in the regulation of the mitogen-activated protein kinases (MAPKs) in isolated adult rat cardiomyocytes. SNP maximally activated Erk1, Erk2, p38 MAPK and MAPKAPK2 in 5-10 min. The activation of MAPKAPK2 by SNP was blocked by the soluble guanylyl cyclase inhibitor, 1H-[1, 2,4]oxadiazolol[4,3-a]quinoxalin-1-one (ODQ) and the p38 MAPK inhibitor, SB203580. The activation of Erk1 was insensitive to ODQ but completely blocked by the Mek1 inhibitor PD98059. The membrane-permeable homologue of cGMP, 8-Br-cGMP, also activated p38 MAPK (A(0.5) approximately 50 microM) but not Erk1 and Erk2. These results indicate that p38 MAPK and MAPKAPK2 are activated by SNP in cGMP-dependent pathways, while the Erk1 activation by SNP is independent of cGMP levels.

Ischemia induced activation of heat shock protein 27 kinases and casein kinase 2 in the preconditioned rabbit heart

Protein kinase C (PKC), p38 MAP kinase, and mitogen-activated protein kinase-activated kinases 2 and 3 (MAPKAPK2 and MAPKAPK3) have been implicated in ischemic preconditioning (PC) of the heart to reduce damage following a myocardial infarct. This study examined whether extracellular signal-regulated kinase (Erk) 1, p70 ribosomal S6 kinase (p70 S6K), casein kinase 2 (CK2), and other hsp27 kinases are also activated by PC, and if they are required for protection in rabbit hearts. CK2 and hsp27 kinase activities declined during global ischemia in control hearts, whereas PC with 5 min ischemia and 10 min reperfusion increased their activities during global ischemia. Resource Q chromatography resolved two distinct peaks of hsp27 phosphotransferase activities; the first peak (at 0.36 M NaCl) appeared to correspond to the 55-kDa MAPKAPK2. Erk1 activity was elevated in both control and PC hearts after post-ischemic reperfusion, but no change was observed in p70 S6K activity. Infarct size (measured by triphenyltetrazolium staining) in isolated rabbit hearts subjected to 30 min regional ischemia and 2 h reperfusion was 31.0+/-2.6% of the risk zone in controls and was 10.3+/-2.2% in PC hearts (p<0.001). Neither the CK2 inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) nor the Mek1/2 inhibitor PD98059 infused during ischemia blocked protection by PC. The activation of CK2 and Erk1 in ischemic preconditioned hearts appear to be epiphenomena and not required for the reduction of infarction from myocardial ischemia.

Ischemic preconditioning activates MAPKAPK2 in the isolated rabbit heart: evidence for involvement of p38 MAPK

Recent studies suggest that p38 mitogen-activated protein kinase (MAPK) may be involved in ischemic preconditioning (PC). To further test this possibility, the regulation of MAPK-activated protein kinase 2 (MAPKAPK2), a kinase immediately downstream from p38 MAPK, and the activity of c-Jun NH(2)-terminal kinase (JNK), a second MAPK, were examined in preconditioned hearts. Isolated, perfused rabbit hearts were subjected to 20 to 30 minutes of global ischemia. Ventricular biopsies before treatment and after 20 minutes of ischemia were homogenized, and the activities of MAPKAPK2 and JNK were evaluated. For the MAPKAPK2 experiments, 7 groups were studied, as follows: control hearts; preconditioned hearts; hearts treated with 500 nmol/L R(-) N(6)-(2-phenylisopropyl) adenosine (PIA), an A(1)-adenosine receptor agonist; preconditioned hearts pretreated with 100 micromol/L 8-(p-sulfophenyl) theophylline (SPT), an adenosine receptor antagonist; preconditioned hearts also treated with SB 203580, a potent inhibitor of p38 MAPK activation; hearts treated with 50 ng/mL anisomycin (a p38 MAPK/JNK activator); and hearts treated with both anisomycin (50 ng/mL) and the tyrosine kinase inhibitor genistein (50 micromol/L). MAPKAPK2 activity was not altered in control hearts after 20 minutes of global ischemia. By contrast, there was a 3.8-fold increase in activity during ischemia in preconditioned hearts. Activation of MAPKAPK2 in preconditioned hearts was blocked by both SPT and SB 203580. MAPKAPK2 activity during ischemia increased 3.5-fold and 3.3-fold in hearts pretreated with PIA or anisomycin, respectively. MAPKAPK2 activation during ischemia in hearts pretreated with anisomycin was blocked by genistein. In separate hearts, anisomycin mimicked the anti-infarct effect of PC, and that protection was abolished by genistein. JNK activity was measured in control and preconditioned hearts. There was a comparable, modest decline in activity during 30 minutes of global ischemia in both groups. As a positive control, a third group of hearts was treated with anisomycin before global ischemia, and in these, JNK activity increased by 290% above baseline. These results confirm that the p38 MAPK/MAPKAPK2 pathway is activated during ischemia only if the heart is in a preconditioned state. These data further support p38 MAPK as an important signaling component in ischemic PC.

Growth hormone-induced alteration in ErbB-2 phosphorylation status in 3T3-F442A fibroblasts

The growth hormone receptor (GHR), a cytokine receptor superfamily member, requires the JAK2 tyrosine kinase for signaling. We now examine functional interactions between growth hormone (GH) and epidermal growth factor (EGF) in 3T3-F442A fibroblasts. Although EGF enhanced ErbB-2 tyrosine phosphorylation, GH, while causing retardation of its migration on SDS-polyacrylamide gel electrophoresis, decreased ErbB-2's tyrosine phosphorylation. GH-induced retardation was reversed by treatment of anti-ErbB-2 precipitates with both alkaline phosphatase and protein phosphatase 2A, suggesting that GH induced serine/threonine phosphorylation of ErbB-2. Both GH-induced shift in ErbB-2 migration and GH-induced MAP kinase activation were unaffected by a protein kinase C inhibitor but were blocked by the mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1 (MEK1) inhibitor, PD98059. Notably, leukemia inhibitory factor, but not interferon-gamma, also promoted ErbB-2 shift and mitogen-activated protein kinase activation. Cotreatment with EGF and GH versus EGF alone resulted in a 35% decline in acute ErbB-2 tyrosine 1248 autophosphorylation, a marked decline (approximately 50%) in DNA synthesis, and substantially decreased cyclin D1 expression. We conclude that in 3T3-F442A cells, 1) the GH-induced decrease in ErbB-2 tyrosine phosphorylation correlates with MEK1/mitogen-activated protein kinase activity and 2) GH antagonizes EGF-induced DNA synthesis and cyclin D1 expression in a pattern consistent with its alteration in ErbB-2 phosphorylation status.

A catalytically active Jak2 is required for the angiotensin II-dependent activation of Fyn

Recent work with interleukins has shown a convergence of tyrosine phosphorylation signal transduction cascades at the level of the Janus and Src families of tyrosine kinases. Here we demonstrate that activation of the seven-transmembrane AT(1) receptor by angiotensin II induces a physical association between Jak2 and Fyn, in vivo. This association requires the catalytic activity of Jak2 but not Fyn. Deletion studies indicate that the region of Jak2 that binds Fyn is located between amino acids 1 and 240. Studies of the Fyn SH2 and SH3 domains demonstrate that the SH2 domain plays the primary role in Jak2/Fyn association. Not surprisingly, this domain shows a marked preference for tyrosine-phosphorylated Jak2. Surface plasmon resonance estimated the dissociation equilibrium constant (K(d)) of this association to be 2.36 nM. Last, in vivo studies in vascular smooth muscle cells show that, in response to angiotensin II, Jak2 activation is required for Fyn activation and induction of the c-fos gene. The significance of these data is that Jak2, in addition to serving as a critical angiotensin II activated signal transduction kinase, also functions as a docking protein and participates in the activation of Fyn by providing phosphotyrosine residues that bind the SH2 domain of Fyn.