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Ho CL, Lin YL, Li SF. Three toxins with phospholipase activity isolated from the yellow-legged hornet (Vespa verutina) venom. Toxicon 1999; 37:1015-24. [PMID: 10484737 DOI: 10.1016/s0041-0101(98)00229-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The yellow-legged hornet, Vespa verutina, is widely distributed in both the mountain area and the suburbs of Taiwan and possesses highly toxic venom (LD50=0.02 microl/g mouse). By gel filtration on Fractogel (TSK HW 50f) followed by cation-exchange chromatography on Mono S column, three toxins designated as verutoxin 1, 2a and 2b (VT-1, VT-2a and VT-2b) were isolated from the venom. The toxin VT-1 had a molecular mass of 34,982 Da and an LD50 value of 3.61 microg/g mouse. Toxin VT-2a and 2b were more basic and more toxic than VT-1. VT-2a and 2b were isotoxins with molecular masses differing in only 14 Da (33,360 and 33,374 Da, respectively) and had a similar toxicity in mice (LD50=0.87 microg/g mouse). All three toxins were capable of catalyzing the hydrolysis of emulsified phospholipids and lysophosphatide, but not sphingomyelin. Analysis of the hydrolyzed products (fatty acid and lyso-compound) by a liquid chromatography/mass spectrometer revealed that the toxins liberates fatty acid mainly from the 1-position of the synthetic phospholipid. This result indicates that verutoxins possess phospholipase A1 activity. Toxin VT-1 showed higher phospholipase activity than VT-2a and 2b. However, the latter toxins exhibited much higher direct hemolytic activity toward the mouse red blood cells. Vespid phospholipases are known as one of the three major venom allergens in many species of wasps. Our studies indicate that vespid phospholipases A1, in addition to acting as allergens, possess direct toxic actions that may also cause death in animals. Toxin VT-2a and 2b which possess potent hemolytic activity and high lethality in mice may act as the lethal factor of V. verutina venom.
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102
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He S, Lin YL, Liu YX. Functionally inactive protein C inhibitor in seminal plasma may be associated with infertility. Mol Hum Reprod 1999; 5:513-9. [PMID: 10340997 DOI: 10.1093/molehr/5.6.513] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Protein C inhibitor (PCI) has been found in seminal plasma and is considered to protect intact surrounding cells and seminal plasma proteins from possible proteolytic damage. In the present study, we showed that although the antigenic levels of PCI in two seminal plasma samples from patients with infertility were normal or slightly elevated, their inhibitory activities toward urokinase plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) were absent. In contrast, uPA and tPA proteolytic activities in these two samples were 20-60-fold higher than that from normal volunteers. A time-course analysis of PCI-uPA complex formation showed that >80% of the complex had been formed within 15 min in normal seminal plasma in the presence of heparin, compared with the total complex formed after 150 min incubation, whereas no response to heparin stimulation was observed in the assays with the two patient samples. Similarly, >90% of PCI-tPA complex was formed after 30 min of heparin stimulation in normal seminal plasma but no response was observed in the two patient samples. Kinetic assays of PCI inhibitory function in the presence of activated protein C (APC) showed that PCI inhibitory activity in the two patient samples was absent and not stimulated by heparin. Western blotting also showed that most of the intact PCI molecules, in normal samples, formed complexes with either uPA or tPA but there was no complex formed in one of the two patient samples and very little complex was observed in the other, suggesting that PCI in the two patient samples is inactive. These results suggest that the presence of functionally inactive PCI in seminal plasma may be associated with infertility.
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103
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Liang YC, Chen YC, Lin YL, Lin-Shiau SY, Ho CT, Lin JK. Suppression of extracellular signals and cell proliferation by the black tea polyphenol, theaflavin-3,3'-digallate. Carcinogenesis 1999; 20:733-6. [PMID: 10223207 DOI: 10.1093/carcin/20.4.733] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Previous studies in our laboratory have shown that the major green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), suppressed autophosphorylation of epidermal growth factor (EGF) receptor induced by EGF in human A431 epidermoid carcinoma cells. In this study, we examined the inhibitory effects of black tea polyphenols, including theaflavin (TF-1), a mixture (TF-2) of theaflavin-3-gallate (TF-2a) and theaflavin-3'-gallate (TF-2b), theaflavin-3,3'-digallate (TF-3) and the thearubigin fraction on the autophosphorylation of the EGF and PDGF receptors in A431 cells and mouse NIH3T3 fibroblast cells, respectively. First, we examined the effects of these polyphenols on the proliferation of A431 and NIH3T3 cells. Both EGCG and TF-3 strongly inhibited the proliferation of A431 and NIH3T3 cells more than the other theaflavins did. In cultured cells with pre-treatment of tea polyphenol, TF-3 was stronger than EGCG on the reduction of EGF receptor and PDGF receptor autophosphorylation induced by EGF and PDGF, respectively. Other theaflavins slightly reduced the autophosphorylation of the EGF and PDGF receptors; furthermore, TF-3 could reduce autophosphorylation of the EGF receptor (or PDGF receptor) even with co-treatment with EGF (or PDGF) and TF-3, but EGCG was inactive under these conditions. In addition, TF-3 was stronger than EGCG in blocking EGF binding to its receptor. These results suggest that not only the green tea polyphenol, EGCG, but also the black tea polyphenol, TF-3, have an antiproliferative activity on tumor cells, and the molecular mechanisms of antiproliferation may block the growth factor binding to its receptor and thus suppress mitogenic signal transduction.
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Chan EC, Chen CT, Lin YL, Chen KT. Signaling pathway and pepsinogen secretion in Helicobacter pylori-infected human gastric adenocarcinoma. Int J Mol Med 1999; 3:421-5. [PMID: 10085417 DOI: 10.3892/ijmm.3.4.421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Although in vitro studies have suggested that Helicobacter pylori not only attaches to cultured cells but also induces signal transduction events in host cells, the underlying mechanism of H. pylori action has yet to be fully investigated. In the present study, a cytotoxin-positive H. pylori was used to infect and examined for its effect on the stimulation of second messengers in human gastric adenocarcinoma (AGS). Results showed that H. pylori increased cytosolic free calcium concentration [Ca2+]i in host cells in a dose-dependent manner. The increase of [Ca2+]i was due to release from the intracellular Ca2+ store as well as entry to the extracellular Ca2+. H. pylori infection on host cells was also found to induce the generations of inositol phosphates, adenosine 3', 5'-cyclic monophosphate, and guanosine 3',5'-cyclic monophosphate, and to stimulate the secretion of pepsinogen.
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Lin YL, Tsai SH, Lin-Shiau SY, Ho CT, Lin JK. Theaflavin-3,3'-digallate from black tea blocks the nitric oxide synthase by down-regulating the activation of NF-kappaB in macrophages. Eur J Pharmacol 1999; 367:379-88. [PMID: 10079014 DOI: 10.1016/s0014-2999(98)00953-4] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Nitric oxide (NO) plays an important role in inflammation and also in multiple stages of carcinogenesis. We investigated the effects of various tea polyphenols, including theaflavin, a mixture of theaflavin-3-gallate and theaflavin-3'-gallate, theaflavin-3,3'-digallate, thearubigin, and (-)-epigallocatechin-3-gallate on the induction of NO synthase in lipopolysaccharide-activated murine macrophages, RAW 264.7 cells. Theaflavin-3,3'-digallate was found to be stronger than (-)-epigallocatechin-3-gallate in inhibiting NO generation and inducible NO synthase protein in activated macrophages, while theaflavin, a mixture of theaflavin-3-gallate and theaflavin-3'-gallate and thearubigin were less effective. Inhibition of NO production was observed when cells were cotreated with theaflavin-3,3'-digallate and lipopolysaccharide. Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses demonstrated that significantly reduced 130-kDa protein and mRNA levels of inducible NO synthase were expressed in lipopolysacchride-activated macrophages with theaflavin-3,3'-digallate, compared to those without theaflavin-3,3'-digallate. Electrophoretic mobility shift assay (EMSA) indicated that theaflavin-3,3'-digallate blocked the activation of nuclear factor kappaB (NF-kappaB), a transcription factor necessary for inducible NO synthase induction. Theaflavin-3,3'-digallate also blocked phosphorylation of IkappaB from cytosolic fraction and reduced lipopolysacchride-induced nuclear accumulation of transcription factor NF-kappaB p65 and p50 subunits. These results suggest that theaflavin-3,3'-digallate decreases the protein levels of inducible NO synthase by reducing the expression of inducible NO synthase mRNA, and the reduction could be via preventing the activation of NF-kappaB, thereby inhibiting the induction of inducible NO synthase transcription. It was also demonstrated that the gallic acid moiety of theaflavin-3,3'-digallate is essential for their potent anti-inflammation activity.
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106
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Wang JJ, Liao CL, Yang CI, Lin YL, Chiou CT, Chen LK. Localizations of NS3 and E proteins in mouse brain infected with mutant strain of Japanese encephalitis virus. Arch Virol 1999; 143:2353-69. [PMID: 9930192 DOI: 10.1007/s007050050466] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Infection with a mutant Japanese encephalitis virus (JEV) strain RP-2ms showed reduced neurovirulence than wild type or RP-9 strains after inoculation in BALB/c mice. However, higher intracellular viral titer was detected in Rp-2ms infected cultured cells. Localizations of non-structural 3 (NS3) and envelope (E) proteins were demonstrated by immunocytochemistry. NS3 protein was primarily found in the pyramidal neurons in cerebrum, in the molecular and granular layers of cerebellum. Neither E nor NS3 protein was detected in Purkinje cells of the cerebellum. Immunoelectron microscopic observations showed that E and NS3 proteins were positive in JEV-induced membranous systems, mainly hypertrophic rough endoplasmic reticulum (rER) and membrane vesicle structure (MVS) but not smooth membrane structure. Virus particles were seen in the Golgi apparatus, rER, nuclear envelope, MVS and cytoplasmic vacuoles. Different mechanisms of intracellular trapping in vivo provide a possible basis for attenuation of RP-2ms strains of JEV.
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MESH Headings
- Animals
- Brain/metabolism
- Brain/ultrastructure
- Brain/virology
- Cell Line
- Cricetinae
- Encephalitis Virus, Japanese/genetics
- Encephalitis Virus, Japanese/pathogenicity
- Encephalitis Virus, Japanese/ultrastructure
- Encephalitis, Japanese/metabolism
- Encephalitis, Japanese/pathology
- Encephalitis, Japanese/virology
- Endoplasmic Reticulum, Rough/metabolism
- Endoplasmic Reticulum, Rough/ultrastructure
- Endoplasmic Reticulum, Rough/virology
- Mice
- Mice, Inbred BALB C
- Microscopy, Immunoelectron
- Mutation
- RNA Helicases
- Serine Endopeptidases
- Viral Envelope Proteins/genetics
- Viral Envelope Proteins/metabolism
- Viral Nonstructural Proteins/genetics
- Viral Nonstructural Proteins/metabolism
- Virulence/genetics
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107
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Yang CY, Shieh HK, Lin YL, Chang PC. Newcastle disease virus isolated from recent outbreaks in Taiwan phylogenetically related to viruses (genotype VII) from recent outbreaks in western Europe. Avian Dis 1999; 43:125-30. [PMID: 10216769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Three major outbreaks of Newcastle disease (ND) occurred in Taiwan in the last three decades (in 1969, 1984, and 1995). Newcastle disease viruses (NDVs) isolated in the three outbreaks, together with those isolated in 1998, were sequenced between nucleotides 47 and 435 of the fusion gene. A phylogenetic tree based on sequences obtained showed that the NDV isolated in 1969 was similar to the genotype III viruses. In contrast, all isolates in 1984 and seven of the eight isolates in 1995, together with all isolates in 1998, fell into the genotype VII. These results suggest that the 1969 outbreak of ND in Taiwan was caused by the genotype III virus, whereas the 1984 and 1995 outbreaks were caused by the genotype VII viruses. To date, the genotype VII viruses have caused many outbreaks in east Asia and western Europe. We suspect that these outbreaks have constituted the fourth panzootic of ND, which is distinct from the third panzootic caused by the "pigeon PMV-1 viruses." NDV isolated in Taiwan in 1984 was the earliest isolation of the genotype VII virus.
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108
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Liao CL, Lin YL, Shen SC, Shen JY, Su HL, Huang YL, Ma SH, Sun YC, Chen KP, Chen LK. Antiapoptotic but not antiviral function of human bcl-2 assists establishment of Japanese encephalitis virus persistence in cultured cells. J Virol 1998; 72:9844-54. [PMID: 9811720 PMCID: PMC110496 DOI: 10.1128/jvi.72.12.9844-9854.1998] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/1998] [Accepted: 09/09/1998] [Indexed: 11/20/2022] Open
Abstract
Upon infection of Japanese encephalitis virus (JEV), baby hamster kidney (BHK-21) and Chinese hamster ovary (CHO) cells were killed by a mechanism involved in apoptosis. While readily established in a variety of cell lines, JEV persistence has never been successfully instituted in BHK-21 and CHO cells. Since stable expression of human bcl-2 in BHK-21 cells has been shown to delay JEV-induced apoptosis, in this study we investigated whether JEV persistence could be established in such cells. When constitutively expressing bcl-2, but not its closest homolog, bcl-XL, following a primary lytic infection, approximately 5 to 10% of BHK-21 and CHO cells became persistently JEV infected during a long-term culture. From the persistent bulks, several independent clones were selected and expanded to form stable cell lines that continuously produced infectious virus without marked cytopathic effects (CPE). Among these stable cell lines, the truncated nonstructural protein 1 (NS1) was also detected and was indistinguishable from the NS1 truncations previously observed in JEV-persistent murine neuroblastoma N18 cells. However, the stable expression of NS1 alone, regardless of whether it was truncated or full length, failed to render the engineered cells persistently infected by JEV, implying that aberrant NS1 proteins were likely a consequence of, rather than a cause for, the viral persistence. Enforced bcl-2 expression, which did not affect virus replication and spread during the early phase of cytolytic infection, appeared to attain JEV persistence by restriction of virus-induced CPE. Our results suggest that it is the antiapoptotic, rather than the antiviral, effect of cellular bcl-2 which plays a role in the establishment of JEV persistence.
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109
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Lin YL, Liao CL, Chen LK, Yeh CT, Liu CI, Ma SH, Huang YY, Huang YL, Kao CL, King CC. Study of Dengue virus infection in SCID mice engrafted with human K562 cells. J Virol 1998; 72:9729-37. [PMID: 9811707 PMCID: PMC110483 DOI: 10.1128/jvi.72.12.9729-9737.1998] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/1998] [Accepted: 09/09/1998] [Indexed: 11/20/2022] Open
Abstract
Here we report that severe combined immunodeficient (SCID) mice engrafted with human K562 cells (K562-SCID mice) can be used as an animal model to study dengue virus (DEN) infection. After intratumor injection into K562 cell masses of PL046, a Taiwanese DEN-2 human isolate, the K562-SCID mice showed neurological signs of paralysis and died at approximately 2 weeks postinfection. In addition to being detected in the tumor masses, high virus titers were detected in the peripheral blood and the brain tissues, indicating that DEN had replicated in the infected K562-SCID mice. In contrast, the SCID mice were resistant to DEN infection and the mock-infected K562-SCID mice survived for over 3 months. These data illustrate that DEN infection contributed directly to the deaths of the infected K562-SCID mice. Other serotypes of DEN were also used to infect the K562-SCID mice, and the mortality rates of the infected mice varied with different challenge strains, suggesting the existence of diverse degrees of virulence among DENs. To determine whether a neutralizing antibody against DEN in vitro was also protective in vivo, the K562-SCID mice were challenged with DEN-2 and received antibody administration at the same time or 1 day earlier. Our results revealed that the antibody-treated mice exhibited a reduction in mortality and a delay of paralysis onset after DEN infection. In contrast to K562-SCID, the persistently DEN-infected K562 cells generated in vitro invariably failed to be implanted in the mice. It seems that in the early stage of implantation, a gamma interferon activated, nitric oxide-mediated anti-DEN effect might play a role in the innate immunity against DEN-infected cells. The system described herein offers an opportunity to explore DEN replication in vivo and to test various antiviral protocols in infected hosts.
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110
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Chang MC, Lin CP, Huang TF, Lan WH, Lin YL, Hsieh CC, Jeng JH. Thrombin-induced DNA synthesis of cultured human dental pulp cells is dependent on its proteolytic activity and modulated by prostaglandin E2. J Endod 1998; 24:709-13. [PMID: 9855818 DOI: 10.1016/s0099-2399(98)80158-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
To clarify the roles of alpha-thrombin and prostaglandin E2 (PGE2) in the healing and inflammatory processes of dental pulp, their effects on the DNA synthesis of human pulp cells were investigated by measurement of [3H]thymidine incorporation. At a concentration range of 1 to 25 units/ml, alpha-thrombin stimulated DNA synthesis of the pulp cells by 1.5 to 2.6-fold. On the contrary, PGE2 (> 0.05 microgram/ml) suppressed DNA synthesis by 24 to 39%. Using reverse transcriptase-polymerase chain reaction, thrombin receptor mRNA expression was identified in the pulp cells. Furthermore, alpha-thrombin-induced DNA synthesis could be inhibited by antithrombin III (2 units/ml) with heparin (2 units/ml) or D-Phe-Pro-ArgCH2Cl (50 micrograms/ml). PGE2 (0.1 to 0.5 microgram/ml) also inhibited the thrombin-induced DNA synthesis by 39 to 64%. These results imply that pulp cells express the thrombin receptor that is activated by the serine protease activity of thrombin. Interactions of thrombin and PGE2 are important in modulating the inflammatory and healing processes of the pulp.
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111
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Qiu XB, Lin YL, Thome KC, Pian P, Schlegel BP, Weremowicz S, Parvin JD, Dutta A. An eukaryotic RuvB-like protein (RUVBL1) essential for growth. J Biol Chem 1998; 273:27786-93. [PMID: 9774387 DOI: 10.1074/jbc.273.43.27786] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A human protein (RUVBL1), consisting of 456 amino acids (50 kDa) and highly homologous to RuvB, was identified by using the 14-kDa subunit of replication protein A (hsRPA3) as bait in a yeast two-hybrid system. RuvB is a bacterial protein involved in genetic recombination that bears structural similarity to subunits of the RF-C clamp loader family of proteins. Fluorescence in situ hybridization analysis demonstrated that the RUVBL1 gene is located at 3q21, a region with frequent rearrangements in different types of leukemia and solid tumors. RUVBL1 co-immunoprecipitated with at least three other unidentified cellular proteins and was detected in the RNA polymerase II holoenzyme complex purified over multiple chromatographic steps. In addition, two yeast homologs, scRUVBL1 and scRUVBL2 with 70 and 42% identity to RUVBL1, respectively, were revealed by screening the complete Saccharomyces cerevisiae genome sequence. Yeast with a null mutation in scRUVBL1 was nonviable. Thus RUVBL1 is an eukaryotic member of the RuvB/clamp loader family of structurally related proteins from bacteria and eukaryotes that is essential for viability of yeast.
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112
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Wang CJ, Huang HP, Lee MJ, Lin YL, Lin WL, Chang WC. Promotional effect of N-nitroso-N-(3-keto-1,2-butanediol)-3'-nitrotyramine (a nitrosated Maillard reaction product) in mouse fibroblast cells. Food Chem Toxicol 1998; 36:631-6. [PMID: 9734713 DOI: 10.1016/s0278-6915(98)00033-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
N-Nitroso-N-(3-keto-1,2-butanediol)-3'-nitrotyramine (NO-NTA) is a product of model browning system generated in the presence of sodium nitrite. The chemical structure of this compound has been confirmed by UV, mass and nuclear magnetic resonance, and infrared spectroscopy in our previous study. A two-stage transformation protocol was used to chemically transform the mouse embryo fibroblasts C3H10T1/2 cells. To initiate transformation, the cells were treated with benzo[a]pyrene (BaP) (0.1 mg/ml), and NO-NTA (0.01, 0.1 and 1 mg/ml) was employed subsequently to complete the transformation process. Malignant transformed foci were formed in BaP-initiated and NO-NTA promoted C3H10T1/2 cells after 8 wk. Cells treated with NO-NTA alone failed to induce transformation. However, cells initiated with BaP and promoted by cells initiated with BaP and promoted by NO-NTA demonstrated oncogenic properties. Cell lines transformed with NO-NTA-transformed colonies exhibited enhanced growth rate, anchorage independence and tumorigenicity in animals relative to parent cells. These results indicate that NO-NTA is a new tumour promoter and may induce tumour promotion by two-stage oncogenesis. Further studies on the mechanism of action of NO-NTA are now in progress.
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113
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Lin YL, Mei CH, Huang SL, Kuo YH. Four new sesquiterpenes from Petasites formosanus. JOURNAL OF NATURAL PRODUCTS 1998; 61:887-890. [PMID: 9677269 DOI: 10.1021/np970583z] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Four new eremophilane-type sesquiterpenes, petasones A (1) and B (2), S-petasitin (3), and petasinol (4), were isolated from the aerial parts of Petasites formosanus. Their structures were elucidated by spectroscopic and chemical methods as 3alpha-[(Z)-3-methylsulfinylacryloxy]eremophila-7(11), 9-dien-8-one; 3alpha-[(E)-3-methylsulfinylacryloxy]eremophila-7(11), 9-dien-8-one; 3alpha-[(Z)-3-methylthioacryloxy]-11-hydroxyeremophila -6, 9-dien-8-one; and 3alpha-[(E)-3-methylsulfinylacryloxy]-8beta-hydroxy eremophila-9, 11-diene, respectively.
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114
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Lin YL, Chou CK. Phosphatidylinositol 3-kinase is required for the regulation of hepatitis B surface antigen production and mitogen-activated protein kinase activation by insulin but not by TPA. Biochem Biophys Res Commun 1998; 246:172-5. [PMID: 9600088 DOI: 10.1006/bbrc.1998.8488] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Insulin suppresses hepatitis B surface antigen (HBsAg) gene expression and stimulates cell proliferation in human hepatoma Hep3B cells. 12-O-tetradecanoyl phorbol-13-acetate, TPA, has been demonstrated to mimic insulin actions in these cells. We examined the role of phosphatidylinositol 3-kinase (PI 3-kinase) in the signaling pathways of insulin and TPA towards these two biological phenomena in Hep3B cells. The pre-treatment of 5 microM of wortmannin diminished insulin suppressed HBsAg production and completely abolished insulin stimulated cell proliferation. However, wortmannin had no effect on TPA actions in both HBsAg suppression and cell growth stimulation. We further investigated the effect of wortmannin in mitogen-activated protein kinases (MAPKs) activation induced by insulin or TPA. After the pretreatment of wortmannin, insulin activated MAPKs was completely blocked, but TPA was still capable to activate MAPKs. These results suggest that PI 3-kinase is involved in insulin actions but not in TPA effects, and allow us to dissociate the signaling pathways of insulin and TPA in human hepatoma Hep3B cells.
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115
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He S, Lin YL. In vitro stimulation of C1s proteolytic activities by C1s-presenting autoantibodies from patients with systemic lupus erythematosus. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 1998; 160:4641-7. [PMID: 9574573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Anti-C1s autoantibodies (IgG forms), which recognize the conjunction of C1s heavy chain and light chain (C1s-presenting autoantibodies) from patients with systemic lupus erythematosus (SLE), have been found to stimulate C1s enzymatic activities. This is due to acceleration of the proteolytic hydrolysis of the synthetic substrate C1-1 by C1s, enhancement of the complex formation of C1s with its natural pseudosubstrate, C1 inhibitor (C1 inh), and promotion of proteolytic activation of its natural substrate, C4. Seven of fifteen samples from patients with SLE were found to contain such autoantibodies. The hydrolysis of the synthetic substrate C1-1 catalyzed by C1s in 25 to 27 min in the presence of anti-C1s autoantibodies was equivalent to the hydrolysis of C1-1 catalyzed by C1s alone or C1s with control IgG from healthy sera in 110 min, approximately fourfold faster than the reaction in the absence of anti-C1s autoantibodies. Densitometry scanning data showed that the formation of the C1s-C1 inh complex in the presence of anti-C1s autoantibodies was three to four times greater than that with control IgG. It was also noticed that the autoantibodies convert almost all of the latent forms of C1s to an active form that binds to C1 inh. Another group of Western blots showed that C1s cleaved C4 alpha-chain three times faster in the presence of autoantibodies than of control IgG. It is likely that the overconsumption of complement components is common in the pathogenesis of tissue damage occurring in SLE.
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116
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Ho CL, Chen WC, Lin YL. Structures and biological activities of new wasp venom peptides isolated from the black-bellied hornet (Vespa basalis) venom. Toxicon 1998; 36:609-17. [PMID: 9643473 DOI: 10.1016/s0041-0101(97)00080-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The black-bellied hornet (Vespa basalis) is the most dangerous species of vespine wasps found in Taiwan. The hornet possesses a highly toxic venom which is rich in toxin, enzymes and biologically active peptides. Using ultrafiltration to remove the high molecular weight toxin and enzymes followed by reverse-phase HPLC, three bioactive tridecapeptides, designated "HP-1, HP-2 and HP-3" were isolated from the venom. Their amino acid sequences were determined as: HP-1: LFRLIAKTLGSLM, HP-2: LFRLLANTLGKIL, HP-3: IFGLLAKTLGNLF. The primary structures of these peptides appear to be homologous to those of chemotactic peptides isolated from other vespid venoms. However, these peptides show little chemotactic activity on human neutrophils and have distinct tripeptide sequences at the amino and carboxylic terminal sides, as compared with other hornet chemotactic peptides. The lack of Pro3 which is a characteristic structure of vespid chemotactic peptides in their sequences is most distinctive. Circular dichroism spectra of these peptides measured in 20% trifluoroethanol show a high content of alpha-helical conformation. All three peptides provoked local edema in rat hind paw, which could be inhibited by antihistamine (diphenhydramine) and drug with antiserotonin activity (cyproheptadine). These peptides also exhibited a potent hemolytic activity which was potentiated by a non-lytic dose of the hornet lethal protein, suggesting a supporting role of these peptides in the lethal effect of Vespa basalis venom.
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117
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Chu JJ, Chen KD, Lin YL, Fei CY, Chiang AS, Chiang CD, Lai YK. Taxol induces concomitant hyperphosphorylation and reorganization of vimentin intermediate filaments in 9L rat brain tumor cells. J Cell Biochem 1998; 68:472-83. [PMID: 9493910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Taxol, a microtubule stabilizing agent, has been extensively investigated for its antitumor activity. The cytotoxic effect of taxol is generally attributed to its antimicrotubule activity and is believed to be cell cycle dependent. Herein, we report that taxol induces hyperphosphorylation and reorganization of the vimentin intermediate filament in 9L rat brain tumor cells, in concentration- and time-dependent manner. Phosphorylation of vimentin was maximum at 10(-6) M of taxol treatment for 8 h and diminished at higher (10(-5) M) concentration. Enhanced phosphorylation of vimentin was detectable at 2 h treatment with 10(-6) M taxol and was maximum after 12 h of treatment. Taxol-induced phosphorylation of vimentin was largely abolished in cells pretreated with staurosporine and bisindolymaleimide but was unaffected by H-89, KT-5926, SB203580, genistein, and olomoucine. Thus, protein kinase C may be involved in this process. Hyperphosphorylation of vimentin was accompanied by rounding up of cells as revealed by scanning electron microscopy. Moreover, there was a concomitant reorganization of the vimentin intermediate filament in the taxol-treated cells, whereas the microtubules and the actin microfilaments were less affected. Taken together, our data demonstrate that taxol induces hyperphosphorylation of vimentin with concomitant reorganization of the vimentin intermediate filament and that this process may be mediated via a protein kinase C signaling pathway.
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Lin YL, Liu JS, Chen KT, Chen CT, Chan EC. Identification of neutral and acidic sphingomyelinases in Helicobacter pylori. FEBS Lett 1998; 423:249-53. [PMID: 9512367 DOI: 10.1016/s0014-5793(98)00087-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We demonstrated for the first time the presence of sphingomyelinase (SMase) in Helicobacter pylori. Activation of SMase has been implicated as the cause of elevation of cellular ceramide levels and consequently of apoptosis. The data indicate that there are two classes of SMase, defined by their optimal pHs and cellular locations, existing in H. pylori. One is an Mg(2+)-dependent membrane-bound enzyme with an optimal activity at pH 7, and the other is an Mg(2+)-independent cytosolic enzyme with an optimal activity at pH 5. Bisalumin, a bismuth salt, was found to inhibit the activities of both forms of SMase regardless of the presence of Mg2+. By Western blot analysis, the membrane-bound SMases of H. pylori and Bacillus cereus were shown to be antigenically related and to have a similar denatured molecular mass of 28 kDa.
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Lin YL, Shivji MK, Chen C, Kolodner R, Wood RD, Dutta A. The evolutionarily conserved zinc finger motif in the largest subunit of human replication protein A is required for DNA replication and mismatch repair but not for nucleotide excision repair. J Biol Chem 1998. [PMID: 9430682 DOI: 10.1074/jbc.233.3.1453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The largest subunit of the replication protein A (RPA) contains an evolutionarily conserved zinc finger motif that lies outside of the domains required for binding to single-stranded DNA or forming the RPA holocomplex. In previous studies, we showed that a point mutation in this motif (RPAm) cannot support SV40 DNA replication. We have now investigated the role of this motif in several steps of DNA replication and in two DNA repair pathways. RPAm associates with T antigen, assists the unwinding of double-stranded DNA at an origin of replication, stimulates DNA polymerases alpha and delta, and supports the formation of the initial short Okazaki fragments. However, the synthesis of a leading strand and later Okazaki fragments is impaired. In contrast, RPAm can function well during the incision step of nucleotide excision repair and in a full repair synthesis reaction, with either UV-damaged or cisplatin-adducted DNA. Two deletion mutants of the Rpa1 subunit (eliminating amino acids 1-278 or 222-411) were not functional in nucleotide excision repair. We report for the first time that wild type RPA is required for a mismatch repair reaction in vitro. Neither the deletion mutants nor RPAm can support this reaction. Therefore, the zinc finger of the largest subunit of RPA is required for a function that is essential for DNA replication and mismatch repair but not for nucleotide excision repair.
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Lin YL, Shivji MK, Chen C, Kolodner R, Wood RD, Dutta A. The evolutionarily conserved zinc finger motif in the largest subunit of human replication protein A is required for DNA replication and mismatch repair but not for nucleotide excision repair. J Biol Chem 1998; 273:1453-61. [PMID: 9430682 DOI: 10.1074/jbc.273.3.1453] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The largest subunit of the replication protein A (RPA) contains an evolutionarily conserved zinc finger motif that lies outside of the domains required for binding to single-stranded DNA or forming the RPA holocomplex. In previous studies, we showed that a point mutation in this motif (RPAm) cannot support SV40 DNA replication. We have now investigated the role of this motif in several steps of DNA replication and in two DNA repair pathways. RPAm associates with T antigen, assists the unwinding of double-stranded DNA at an origin of replication, stimulates DNA polymerases alpha and delta, and supports the formation of the initial short Okazaki fragments. However, the synthesis of a leading strand and later Okazaki fragments is impaired. In contrast, RPAm can function well during the incision step of nucleotide excision repair and in a full repair synthesis reaction, with either UV-damaged or cisplatin-adducted DNA. Two deletion mutants of the Rpa1 subunit (eliminating amino acids 1-278 or 222-411) were not functional in nucleotide excision repair. We report for the first time that wild type RPA is required for a mismatch repair reaction in vitro. Neither the deletion mutants nor RPAm can support this reaction. Therefore, the zinc finger of the largest subunit of RPA is required for a function that is essential for DNA replication and mismatch repair but not for nucleotide excision repair.
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121
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Ho CL, Lin YL, Chen WC, Rocchi R, Piek T. Comparison of the immunogenicity of wasp venom peptides with or without carbohydrate moieties. Toxicon 1998; 36:217-21. [PMID: 9604295 DOI: 10.1016/s0041-0101(97)00066-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Three synthetic vespulakinin analogues either with or without carbohydrate moieties and mastoparan B isolated from Vespa basalis venom were investigated for their immunogenic activity and solution conformation. Mice immunized with these wasp venom peptides, with the exception of (Gal alpha)Thr3, (Gal alpha)Thr4-vespulakinin 1, showed positive antibody responses. However, the response elicited by mastoparan B was much higher than those induced by vespulakinin analogues. The class of antibody induced by these peptides was identified as an IgG1 isotype with kappa-light chain, suggesting stimulation of a T-cell-dependent immune response by these peptides. According to the circular dichroism spectra of these peptides, the structures of the vespulakinin analogues in solution were largely unordered, while mastoparan B exhibited a conformation rich in alpha-helices. The presence of carbohydrate moieties and the rather random structure in vespulakinins may interfere with T-cell recognition of the peptides, leading to lower immune responses.
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Lin YL, Hsiao CK, Ma HM, Hsu HY, Wang SM, Tseng YZ. The impact of National Health Insurance on the volume and severity of emergency department use. Am J Emerg Med 1998; 16:92-4. [PMID: 9451324 DOI: 10.1016/s0735-6757(98)90075-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
National Health Insurance (NHI) was introduced in Taiwan on March 1, 1995. To evaluate the Influence of NHI on the volume and severity of emergency department (ED) visits, a retrospective analysis was conducted. The results showed that NHI did not result in a substantial increase in ED volume (P > .05), but the severity as measured by triage nurses did increase (P < .01). There was no change in the number of admissions to the intensive care units of patients transferred from smaller hospitals, but its percentage significantly decreased (P < .05), which may be a result of the significant increase in the total number of interhospital transfers. It was hypothesized that the universal coverage and a copayment contributed to these changes.
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Lin YL, Chen LK, Liao CL, Yeh CT, Ma SH, Chen JL, Huang YL, Chen SS, Chiang HY. DNA immunization with Japanese encephalitis virus nonstructural protein NS1 elicits protective immunity in mice. J Virol 1998; 72:191-200. [PMID: 9420215 PMCID: PMC109364 DOI: 10.1128/jvi.72.1.191-200.1998] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/1997] [Accepted: 10/01/1997] [Indexed: 02/05/2023] Open
Abstract
Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, is a zoonotic pathogen that is prevalent in some Southeast Asian countries and causes acute encephalitis in humans. To evaluate the potential application of gene immunization to JEV infection, we characterized the immune responses from mice intramuscularly injected with plasmid DNA encoding JEV glycoproteins, including the precursor membrane (prM) plus envelope (E) proteins and the nonstructural protein NS1. When injected with the plasmid expressing prM plus E, 70% of the immunized mice survived after a lethal JEV challenge, whereas when immunized with the plasmid expressing NS1, 90% of the mice survived after a lethal challenge. As a control, the mice immunized with the DNA vector pcDNA3 showed a low level (40%) of protection, suggesting a nonspecific adjuvant effect of the plasmid DNA. Despite having no detectable neutralizing activity, the NS1 immunization elicited a strong antibody response exhibiting cytolytic activity against JEV-infected cells in a complement-dependent manner. By contrast, immunization with a construct expressing a longer NS1 protein (NS1'), containing an extra 60-amino-acid portion from the N terminus of NS2A, failed to protect mice against a lethal challenge. Biochemical analyses revealed that when individually expressed, NS1 but not NS1' could be readily secreted as a homodimer in large quantity and could also be efficiently expressed on the cell surface. Interestingly, when NS1 and NS1' coexisted in cells, the level of NS1 cell surface expression was much lower than that in cells expressing NS1 alone. These data imply that the presence of partial NS2A might have a negative influence on an NS1-based DNA vaccine. The results herein clearly illustrate that immunization with DNA expressing NS1 alone is sufficient to protect mice against a lethal JEV challenge.
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Liu HS, Lin YL, Chen CC. Comparison of various methods of detection of different forms of dengue virus type 2 RNA in cultured cells. Acta Virol 1997; 41:317-24. [PMID: 9607089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In this report, the sensitivity of various methods of detection of dengue virus type 2 (DEN-2) sense, antisense, replicative intermediate (RI) and replicative form (RF) RNAs in infected mosquito Aedes pseudoscutellaris AP-61 and mammalian baby hamster kidney BHK-21 cells is compared. LiCl precipitation was used for separation of viral RF RNA from RI RNA. Our results show that reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern blot analysis and slot blot hybridisation of LiCl-fractionated RNA were the most sensitive methods of detection of viral RNA and determination of its single-stranded form. Northern blot analysis was the least sensitive method of detection of any form of viral RNA. Using slot blot hybridisation of LiCl-precipitated RNA, viral RI RNA containing de novo synthesised negative strand viral RNA was first detected 30 mins after virus inoculation in both cell lines. This is the earliest time of detection of DEN viral RNA synthesis in host cells so far reported. However, RF RNA could not be detected until 24 hrs post infection (p.i) in AP-61 and 2 days p.i. in BHK-21 cells, respectively. The sequential order of individual forms of viral RNA detected in the infected cells was RI, RF and genomic RNAs. Viral RNA was detected in AP-61 cells always earlier than in BHK-21 cells. Moreover, the level of viral RNA in AP-61 cells was higher than that in BHK-21 cells, suggesting that the virus replicated more actively in AP-61 cells. In conclusion, the LiCl separation of viral RNA followed by slot blot hybridisation was found to be the most sensitive and reliable method of detection of DEN virus RI, RF and genomic RNAs in the infected cells. Moreover, this method can be applied to determine the replication status of any single-stranded RNA virus in the host.
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Lin YL, Huang RL, Chang CM, Kuo YH. Two new puriniums and three new pyrimidines from Heterostemma brownii. JOURNAL OF NATURAL PRODUCTS 1997; 60:982-985. [PMID: 9358639 DOI: 10.1021/np970159y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Two new puriniums, heteromines D (4) and E (5), and three new pyrimidines, heteromines F (6), G (7), and H (8), were isolated from the aerial parts of Heterostemma brownii Hay. Their structures were determined as 7,9-dimethyl-2-(N,N-dimethylamino)guaninium chloride, 7,9-dimethyl-2-(N-methylamino)guaninium chloride, 6-methoxy-4-(N-methylamino)-2-(N,N-dimethylamino)-5- (N-methylformamido)pyrimidine, 6-methoxy-2,4-bis(N-methylamino)-5-(N-methylformamido)pyrimidine, and 2-amino-6-methoxy-4-(N-methylamino)-5-(N-methylformamido)-pyrimidi ne, respectively.
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