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W Yang

Publications and source records attributed to W Yang.

At least 289 records · Page 16Linked to original sources

Synthesis and activity of bivalent FKBP12 ligands for the regulated dimerization of proteins.

The total synthesis and in vitro activities of a series of chemical inducers of dimerization (CIDs) is described. The use of small-molecule CIDs to control the dimerization of engineered FKBP12-containing fusion proteins has been demonstrated to have broad utility in biological research as well as potential medical applications in gene and cell therapies. The facility and flexibility of preparation make this new class of wholly synthetic compounds exceptionally versatile tools for the study of intracellular signaling events mediated by protein-protein interactions or protein localization. While some congeners possess potency comparable to or better than the first generation natural product-derived CID, FK1012, structure-activity relationships are complex and underscore the need for application-specific compound optimizations.

Apoptosis↗

Correlation of endothelium-dependent and -independent vasodilatation with liver function tests during prolonged perfusion of the rat liver.

Twelve male Wistar rats were anaesthetized with pentobarbitone (3 mg 100g(-1) i.p.), the livers were excised and perfused in vitro through the hepatic artery and portal vein at constant flow rates of 0.32+/-0.01 (mean+/-S.E.) and 0.98+/-0.03 ml min(-1) g liver(-1), respectively. The tone of the preparation was raised by methoxamine (7.5 x 10(-6) M). Responses to mid-range doses of acetylcholine (-11 log mol) and sodium nitroprusside (-9 log mol) produced submaximal degrees of vasodilatation (-log mol ED50 = 12.18+/-0.08) and (-log mol ED50 = 9.95+/-0.23), respectively, which did not subside until 5.5 h of perfusion. These did not coincide with the increase in activities of lactic acid dehydrogenase (LDH) and aspartate serine transaminase (AST) activity at 2.5 h, which were indicative of hepatocellular mitochondrial and cytoplasmic damage, respectively. Vascular responses suggested that there was little deterioration in endothelial or smooth muscle function in the hepatic artery up to 5 h perfusion. This model can be reliably used to investigate endothelium-dependent and -independent vasodilators in vascular pharmacological studies of the rat liver although some minimal increases may occur in AST and LDH activity before hemodynamic changes appear at 5.5 h.

Acetylcholine↗

New methods for three dimensional mapping of brain waves.

The representation of spatiotemporal pattern of brain electrical activity is an important issue in the research of neural assemblies. This paper describes methods of parametric 3D head or brain modeling and its corresponding interpolation for functional imaging based on brain waves. The 3D interpolation method is an extension of cortical imaging technique. It can be used with features of either transformed domains or higher order statistics of brain waves on realistic head or brain models. The simulating result suggests that it is a better method in comparison with the global nearest neighbor technique. With those techniques, an example of brainwave imaging was given using partial coherence of event-related potentials estimated by multivariate autoregressive model.

Brain Mapping↗

Paraquat-induced free radical reaction in mouse brain microsomes.

Paraquat has been implicated as an environmental toxin which may induce the syndrome of Parkinson's disease after exposure to this agent. However, the biochemical mechanism by which paraquat causes cell death and neurodegeneration has not been extensively studied. Paraquat was rapidly taken up by nerve terminals isolated from mouse cerebral cortices. It induced lipid peroxidation in a concentration dependent manner in the presence of NADPH and ferrous ion. The maximal stimulation effect was obtained at a paraquat concentration around 100 microM and the Km value for paraquat was 46.7 microM. The lipid peroxidation required microsomal enzymes. Antioxidants, such as superoxide dismutase, catalase and promethazine significantly inhibited paraquat-induced lipid peroxidation. Due to its structural similarity to the pyridinium compound MPP+ (N-methyl-4-phenyl pyridium ion), it may be taken up by dopamine neurons and cause lipid peroxidation and cell death resulting in the manifestation of Parkinsonian syndrome.

Animals↗

Reduced Tyk2/SHP-1 interaction and lack of SHP-1 mutation in a kindred of familial hemophagocytic lymphohistiocytosis.

Familial hemophagocytic lymphohistiocytosis (FHLH) is an autosomal recessive disease with features similar to those of the murine motheaten phenotype resulting from mutations of protein tyrosine phosphatase SHP-1. This has raised the possibility that defects in SHP-1 or SHP-1-regulated signaling molecules may be present in FHLH. In this study, we examined SHP-1 protein and transcript in the peripheral blood mononuclear cells (PBMC) of an FHLH family. Our results show that the FHLH patient and the parents express comparable levels of a single SHP-1 protein and that the SHP-1 cDNA clone from the patient contains no mutation in the coding region. Interestingly, a reduced association of SHP-1 with the Jak family kinase Tyk2 was detected in the patient and the defect appears to have been inherited from one of the parents. This reduced SHP-1/Tyk2 association is likely due to a defect in Tyk2 or in cellular factors regulating Tyk2, because we found no abnormalities in SHP-1 or in SHP-1 association with the other Jak kinases. These data demonstrate that the SHP-1 gene is intact in FHLH and that the defect in some cases with this disease may involve signaling molecules regulated by SHP-1.

Adult↗

Differential antigen-stimulated proliferation of human mononuclear cells by recombinant Schistosoma japonicum antigens in a Chinese population.

Peripheral blood mononuclear cells (PBMC) from 117 individuals living on two islands in an area (Dongting Lake) endemic for schistosomiasis japonica in China, and 15 control individuals from a non-endemic area of China, were assessed for antigen-stimulated proliferation against five recombinant Schistosoma japonicum antigens of recognized interest in the development of immunity to schistosomiasis. Two recombinant antigens, paramyosin and 28-kD glutathione-S-transferase, stimulated cellular proliferation (stimulation index > or = 3.0) in 38.5% and 42.5% of subjects, respectively, a level similar to that induced by a soluble whole parasite extract (51.3%). In contrast, three other recombinant antigens tested--a fatty acid binding protein, 22-kD tegumental membrane-associated antigen, and glyceraldehyde-3-phosphate dehydrogenase--stimulated PBMC proliferation in only 3-8% of subjects. Moreover, we also identified a positive association between the degree of exposure, and cellular proliferation following stimulation with recombinant paramyosin or whole parasite extract. Highly significant differences in antigen-stimulated proliferation were also observed between the two islands, Niangashan and Qingshan. The whole parasite extract stimulated proliferation in 90% of subjects from Niangashan island compared with only 42.1% of subjects from Qingshan island (chi2 = 16.88, P = 0.00004), while glutathione-S-transferase stimulated proliferation in 77.3% of subjects from Niangashan island compared with only 34.7% of subjects from Qingshan island (chi2 = 13.09, P = 0.003). A similar, but not significant, trend was observed for paramyosin and the fatty-acid binding protein. The identification of differential cellular proliferative responses to specific schistosome antigens within an infected human population may have important practical implications for vaccine development against schistosomiasis japonica.

Adult↗

Characterization of the geranylgeranyl transferase type I from Schizosaccharomyces pombe.

The Schizosaccharomyces pombe cwg2+ gene encodes the beta-subunit of geranylgeranyl transferase I (GGTase I), which participates in the post-translational C-terminal modification of several small GTPases, allowing their targeting to the membrane. Using the two-hybrid system, we have identified the cwp1+ gene that encodes the alpha-subunit of the GGTase I. cwp1p interaction with cwg2p was mapped to amino acids 1-244 or 137-294 but was not restricted to amino acids 137-244. The genomic cwp1+ was isolated and sequenced. It has two putative open reading frames of 677 and 218 bp, separated by a 51 bp intron. The predicted amino acid sequence shows significant similarity to GGTase I alpha-subunits from different species. However, complementation of Saccharomyces cerevisiae ram2-1 mutant by overexpressing the cwp1+ gene was not possible. Expression of both cwg2+ and cwp1+ in Escherichia coli allowed 'in vitro' reconstitution of the GGTase I activity. S. pombe cells expressing the mutant enzyme containing the cwg2-1 mutation do not grow at 37 degrees C, but the growth defect can be suppressed by the addition of sorbitol. Actin immunostaining of the cwg2-1 mutant strain grown at 37 degrees C showed an abnormal distribution of actin patches. The cwg2-1 mutation was identified as a guanine to adenine substitution at nucleotide 604 of the coding region, originating the change A202T in the cwg2p. Deletion of the cwg2 gene is lethal; delta cwg2 spores can divide two or three times before losing viability. Most cells have aberrant morphology and septation defects. Overexpression of the rho1G15VC199R double-mutant allele in S. pombe caused loss of polarity but was not lethal and did not render the (1-3)beta-D-glucan synthase activity independent of GTP. Therefore, geranylgeranylation of rho1p is required for the appropriate function of this GTPase.

Actins↗

Effects of impulse noise on cortical response threshold and inner ear activity of succinic dehydrogenase and acetylcholinesterase in guinea pigs.

The effects of impulse noise (firecrackers at 170 dB SPL, 1, 10, 20 rounds) on auditory cortical response threshold (CRT) and activity of succinic dehydrogenase (SDH) and acetylcholinesterase (AchE) in the inner ear were studied in 37 guinea pigs. The results showed that extent of damage in the cochlea was related to amount of exposure to the noise. Exposure to 10 rounds resulted in temporal threshold shift (TTS); to 20 rounds the result was permanent threshold shift (PTS). For the period when TTS existed, inverse correlation was noticed between enzyme activity change and CRT shift. The correlation could not be established when PTS was induced. The results suggest that the pathomechanism of PTS was more complex than that of TTS. The significance of the results is discussed.

Acetylcholinesterase↗

Scattered Golgi elements during microtubule disruption are initially enriched in trans-Golgi proteins.

We have addressed the question of whether or not Golgi fragmentation, as exemplified by that occurring during drug-induced microtubule depolymerization, is accompanied by the separation of Golgi subcompartments one from another. Scattering kinetics of Golgi subcompartments during microtubule disassembly and reassembly following reversible nocodazole exposure was inferred from multimarker analysis of protein distribution. Stably expressed alpha-2,6-sialyltransferase and N-acetylglucosaminyltransferase-I (NAGT-I), both C-terminally tagged with the myc epitope, provided markers for the trans-Golgi/trans-Golgi network (TGN) and medial-Golgi, respectively, in Vero cells. Using immunogold labeling, the chimeric proteins were polarized within the Golgi stack. Total cellular distributions of recombinant proteins were assessed by immunofluorescence (anti-myc monoclonal antibody) with respect to the endogenous protein, beta-1,4-galactosyltransferase (GalT, trans-Golgi/TGN, polyclonal antibody). ERGIC-53 served as a marker for the intermediate compartment). In HeLa cells, distribution of endogenous GalT was compared with transfected rat alpha-mannosidase II (medial-Golgi, polyclonal antibody). After a 1-h nocodazole treatment, Vero alpha-2,6-sialyltransferase and GalT were found in scattered cytoplasmic patches that increased in number over time. Initially these structures were often negative for NAGT-I, but over a two- to threefold slower time course, NAGT-I colocalized with alpha-2,6-sialyltransferase and GalT. Scattered Golgi elements were located in proximity to ERGIC-53-positive structures. Similar trans-first scattering kinetics was seen with the HeLa GalT/alpha-mannosidase II pairing. Following nocodazole removal, all cisternal markers accumulated at the same rate in a juxtanuclear Golgi. Accumulation of cisternal proteins in scattered Golgi elements was not blocked by microinjected GTPgammaS at a concentration sufficient to inhibit secretory processes. Redistribution of Golgi proteins from endoplasmic reticulum to scattered structures following brefeldin A removal in the presence of nocodazole was not blocked by GTPgammaS. We conclude that Golgi subcompartments can separate one from the other. We discuss how direct trafficking of Golgi proteins from the TGN/trans-Golgi to endoplasmic reticulum may explain the observed trans-first scattering of Golgi transferases in response to microtubule depolymerization.

Animals↗

Opposing effects of low and high molecular weight kininogens on cell adhesion.

High molecular weight kininogen (HK) blocks cell spreading but not cell attachment to surfaces coated with vitronectin and other ligands of beta3 integrins. We sought to learn the structural basis of this phenomenon. Monoclonal antibodies against the histidine-rich D5 domain in the light chain of 2-chain HK abolished the inhibitory effect of 2-chain HK on spreading of MG-63 osteosarcoma cells on vitronectin-coated tissue-culture plastic. The antibodies were effective only if incubated with 2-chain HK in solution and did not abolish the anti-cell-spreading effect of 2-chain HK that was pre-adsorbed to tissue-culture plastic. Exposure of an epitope in the histidine-rich domain was less when HK was adsorbed to tissue-culture plastic (oxidized polystyrene) than when it was adsorbed to ELISA plastic (untreated polystyrene). Loss of the epitope correlated with increased anti-cell-spreading activity of HK on tissue-culture plastic. The light chain of 2-chain HK containing D5 and that containing recombinant D5 both had anti-cell-spreading activity, but only when present in solution during adhesion assays. Pre-adsorption of recombinant D5 to tissue-culture plastic resulted in a surface on which adsorbed 2-chain HK had little anti-cell-spreading activity. Binding study revealed that HKa bound to immobilized vitronectin. The histidine-rich D5 domain of light chain of HK was identified as one of the binding sites of vitronectin, suggesting that the masking of the RGD cell-binding site of immobilized vitronectin is the molecular mechanism of anti-cell-spreading effect of HKa. In contrast, low molecular weight kininogen (LK), which lacks D5, augmented cell spreading on vitronectin-coated tissue-culture plastic. Thus, HK and LK have opposing effects on VN-dependent cell adhesion. The augmenting effect of LK was greater if LK was preincubated with cells or adsorbed to the surface at pH>7.0. Analysis of fragments of LK and antibody inhibition studies localized the cell-adhesion activity to the D3 domain that is common to LK and HK. These findings indicate that the D5 domain mediates the adsorption of HK or 2-chain HK to vitronectin substratum in anti-adhesive conformations, i.e., masking of the RGD cell-binding site of vitronectin. Such conformers inhibit cell spreading on vitronectin even though a cell-adhesion site is present in D3.

Antibodies, Monoclonal↗

Infection of ducklings with virus particles containing linear double-stranded duck hepatitis B virus DNA: illegitimate replication and reversion.

Double-stranded linear DNA is synthesized as a minor viral DNA species by all hepadnaviruses. In a previous study (W. Yang and J. Summers, J. Virol. 69:4029-4036, 1995) we showed that virus particles containing linear DNA of the duck hepatitis B virus (DHBV) could initiate an infection of primary duck hepatocytes. In cells infected by linear DNA containing viruses the transcriptional template, covalently closed circular DNA, was formed by circularization of linear DNA by nonhomologous recombination between the two ends. This process was shown to result in viral DNA replication through multiple generations of linear DNA intermediates, a process we called illegitimate replication. In this study we showed that viruses containing linear DHBV DNA produced by engineered insertions in the r sequence, which encodes the 5' end of the pregenome, could infect hepatocytes in vivo, and these hepatocytes proceeded to carry out illegitimate replication. Nonhomologous recombination quickly produced revertants and partial revertants in which all or part of the insertion was deleted. One such partial revertant that replicated primarily through circular DNA intermediates, but which synthesized elevated levels of linear DNA, could be sustained for several days as the predominant genotype in vivo, but this mutant was eventually displaced by variants showing full reversion to legitimate replication and that synthesized normal low levels of linear DNA. Full revertants did not necessarily contain the wild-type r sequence. The results suggest that the linear DNA produced during DHBV infection initiates cycles of illegitimate replication by generating mutants with altered r sequences. Some r sequence mutants carry out a mixture of legitimate and illegitimate replication that can contribute to elevated production of linear DNA in individual cells.

Animals↗

An ATF/CRE element mediates both EBNA2-dependent and EBNA2-independent activation of the Epstein-Barr virus LMP1 gene promoter.

The Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) is a viral oncogene whose expression is regulated by both viral and cellular factors. EBV nuclear antigen 2 (EBNA2) is a potent transactivator of LMP1 expression in human B cells, and several EBNA2 response elements have been identified in the promoter regulatory sequence (LRS). We have previously shown that an activating transcription factor/cyclic AMP response element (ATF/CRE) site in LRS is involved in EBNA2 responsiveness. We now establish the importance of the ATF/CRE element by mutational analysis and show that both EBNA2-dependent activation and EBNA2-independent activation of the promoter occur via this site but are mediated by separate sets of factors. An electrophoretic mobility shift assay (EMSA) with specific antibodies showed that the ATF-1, CREB-1, ATF-2 and c-Jun factors bind to the site as ATF-1/CREB-1 and ATF-2/c-Jun heterodimers whereas the Sp1 and Sp3 factors bind to an adjacent Sp site. Overexpression of ATF-1 and CREB-1 in the cells by expression vectors demonstrated that homodimeric as well as heterodimeric forms of the factors transactivate the LMP1 promoter in an EBNA2-independent manner. The homodimers of ATF-2 and c-Jun did not significantly stimulate promoter activity. In contrast, the ATF-2/c-Jun heterodimer had only a minor stimulatory effect in the absence of EBNA2 but induced a strong transactivation of the LMP1 promoter when coexpressed with this protein. Evidence for a direct interaction between the ATF-2/c-Jun heterodimeric complex and EBNA2 was obtained by EMSA and coimmunoprecipitation experiments. Thus, our results suggest that EBNA2-induced transactivation via the ATF/CRE site occurs through a direct contact between EBNA2 and an ATF-2/c-Jun heterodimer. EBNA2-independent promoter activation via this site, on the other hand, is mediated by a heterodimeric complex between the ATF-1 and CREB-1 factors.

Activating Transcription Factor 1↗

Regulation of Na+/H+ exchanger gene expression: mitogenic stimulation increases NHE1 promoter activity.

We examined factors important in regulation of expression of the Na+/H+ exchanger gene in NIH/3T3 cells. A stable fibroblast cell line was generated that contained a 1.1-kb proximal fragment of the mouse NHE1 promoter. The addition of serum to serum-starved cells resulted in an increase in activity of the NHE1 promoter. The mitogenic agonists insulin, thrombin, and epidermal growth factor also increased transcription from the NHE1 promoter. Phorbol esters also increased NHE1 promoter-directed transcription, whereas the serine/threonine protein kinase inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine inhibited this stimulation. The protein kinase inhibitors GF-109203X, PD-98059, and genistein all stimulated promoter activity. Promoter deletion analysis and gel mobility shift assays showed that a region between 0.9 and 1.1 kb from the start site was involved in mediating the effect of mitogenic stimulation. The results show that a variety of mitogenic factors can activate the NHE1 promoter during cell growth and proliferation.

3T3 Cells↗

Alternative promoters and cardiac muscle cell-specific expression of the Na+/Ca2+ exchanger gene.

Many studies have investigated the regulation of the Na+/ Ca2+ exchanger, NCX1, but limited data exist on transcriptional regulation of the NCX1 gene. We have identified the transcription start sites of three tissue-specific alternative promoters of NCX1 transcripts from rat heart, kidney, and brain. We have characterized the cardiac NCX1 promoter, from which the most abundant quantities of NCX1 transcripts are expressed. Transfection of primary cardiac myocytes, CHO cells, and COS-7 cells with overlapping genomic DNA fragments spanning the NCX1 cardiac transcription start site has uncovered a cardiac cell-specific minimum promoter from -137 to +85. The cardiac NCX1 promoter is TATA-less but has putative binding sites for cardiac-specific GATA factors, an E box, and an Inr as well as multiple active enhancers. The kidney NCX1 promoter has a typical TATA box and binding sites for several tissue-specific factors. The brain NCX1 promoter is very GC-rich and possesses several Sp-1 binding sites consistent with its ubiquitous expression.

Alternative Splicing↗

Sulfate content and specific glycosaminoglycan backbone of perlecan are critical for perlecan's enhancement of islet amyloid polypeptide (amylin) fibril formation.

Islet amyloidosis is characterized by the deposition and accumulation of amylin in pancreatic beta-cells and is observed in 90% of patients with type 2 diabetes. Previous studies have also revealed the presence of the specific heparan sulfate proteoglycan, perlecan, colocalized to islet amyloid deposits, similar to perlecan's known involvement with other amyloid proteins. In the present study, perlecan purified from the Engelbreth-Holm-Swarm (EHS) tumor was used to define perlecan's interactions with amylin (i.e., islet amyloid polypeptide) and its effects on amylin fibril formation. Using a solid phase-binding immunoassay, human amylin, but not rat amylin, bound immobilized EHS perlecan with a single dissociation constant (Kd) = 2.75 x 10(-6) mol/l. The binding of human amylin to perlecan was similarly observed using perlecan heparan sulfate glycosaminoglycans (GAGs), and was completely abolished by 10 micromol/l heparin. Using thioflavin T fluorometry, Congo red staining, and electron microscopy methodology, intact perlecan was found to enhance amylin fibril formation in a dosage-dependent manner, with the majority of these effects attributed to the heparan sulfate GAG chains of perlecan. Other sulfated GAGs and related macromolecules were also effective in the enhancement of amylin fibril formation in the order of heparin > heparan sulfate > chondroitin-4-sulfate = dermatan sulfate = dextran sulfate > pentosan polysulfate, implicating the importance of the specific GAG/carbohydrate backbone. The sulfate content of heparin/heparan sulfate was also important for the enhancement of amylin fibril formation in the order of heparin > N-desulfated N-acetylated heparin > completely desulfated N-sulfated heparin > completely desulfated N-acetylated heparin. These studies suggest that the enhancement effects of perlecan on amylin fibril formation are mediated primarily by both specific GAG chain backbone and GAG sulfate content, and implicate perlecan as an important macromolecule that is likely involved in the pathogenesis of islet amyloidosis.

Amyloid↗

What is anatomy for? Considerations on the body as a whole and whole anatomy.

In anatomy today, construction of the body is devoid of the water element, and the framework of the discipline is sectionalized (segmented, specialized, and divided), so that the body is not described in an integrated, harmonious manner. In this paper, the present authors selected the body, body water, and skin as objects of contemplation and deliberated on the history, significance, and resuscitation of anatomy. (1) Living things are dependent on water, and water is a vital component of the body. Therefore, greater consideration should be given to the presence of body water in morphological description of the body. (2) Since anatomy is sectionalized, understanding of the body is dwarfed and distorted. Whole anatomy, which described the body as a whole is the ideal style. (3) The body as a whole should always be placed in the center of anatomy. This should be the ultimate form of teaching anatomy.

Anatomy↗

A comparative observation on treatment of heart failure due to diastolic insufficiency of the left ventricle--a report of 43 cases.

43 cases of heart failure due to diastolic insufficiency of the left ventricle were treated with TCM differential treatment as the treatment group, the total effective rate being 86.0%. Statistically significant difference (P < 0.05) in the therapeutic effects was found between the treatment group and control (25 cases) group. Improvement of the left ventricular diastole in the treatment group was more obvious than that of the control group (P < 0.01), while contractility of the left ventricle was also improved to a certain extent.

Adult↗

[Schistosoma japonicum ferritin: cloning, nucleotide sequencing, expression, and purification].

Our previous work showed that immunization of mice with Schistosoma japonicum (Sj) immature eggs induced significant immunity against fecundity and embryonation of the parasite. The Sj adult cDNA library was screened by sera from rabbits against Sj immature egg antigen (RASjIEA). The genes encoding molecules which may induce immunity against fecundity/embryonation were chosen for further cloning and expression. First of all, RASjIEA was absorbed with E. coli lysate to remove cross reactive antibodies. The cDNA library was then immunoscreened using the routine method. The resulted positive plaques were rescreened till individual clones were confirmed. Phagemids were obtained using in vivo excision. The positive clones were amplified using PCR. The sizes of the genes were determined by agarose gel electrophoresis. After DNA sequencing of the genes cloned, Gene bank was searched and six different genes were identified from a total of 102 positive clones. One of six identified genes, Sj ferritin (SjFer) was chosen to subclone into pGMC vector. According to DNA sequences of Sj Fer and MCS (multiple cloning site) of the vector, forward primer (Fer/GMC1) and reverse primer (Fer/GMC2) were designed and used to amplify Sj Fer by PCR. The Sj Fer cDNA and expression vector pGMC were digested with BamHI and XhoI. The digested cDNA and pGMC were ligased by T4 DNA ligase to construct a recombinant which was then used to transform E. coli strain ER2566. The fusion protein GMCSF-Sj Ferritin was expressed in insoluble form, the inclusion body. Pellets were harvested and resolved in Tris-HCl buffer containing 8M urea. GMCSF-Sj Ferritin was purified by affinity chromatography using Ni-NTA resin. The molecular weight was determined by SDS-PAGE. This study first reports the gene encoding S. japonicum ferritin as a new candidate for schistosome vaccine.

Animals↗