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Biomedical subjects

Ping Wei

Publications and source records attributed to Ping Wei.

At least 37 records · Page 2Linked to original sources

Expression of adipose differentiation-related protein (ADRP) is conjointly regulated by PU.1 and AP-1 in macrophages.

ADRP is associated with intracellular lipid droplets. We demonstrate the regulatory mechanism for ADRP expression in RAW264.7 macrophages. The ADRP mRNA expression was stimulated by PMA, and synergistically enhanced in association with its protein level in the presence of lipids. A proteasome inhibitor protected the protein from degradation under the lipid-free conditions. One of the possible sites of the PMA action was proved to be an Ets/AP-1 element in the promoter, since mutations of this site reduced the PMA-induced promoter activity, and ligation of this element led to a significant increase in the PMA-responsiveness of homologous or heterologous promoters. Mutations of this site diminished the synergistic effect on the promoter activity induced by PMA and oleic acid, suggesting a possible interaction between this site and the downstream PPARdelta site. EMSA revealed that PU.1 and AP-1 conjointly bound to this site. The juxtaposition of the two sequences was requisite for full activity, since spacer sequences between them decreased the PMA-induced activity. PI3 kinase inhibitor was found to reduce the PMA-induced mRNA expression and promoter activity in parallel with PU.1/AP-1 complex formation on EMSA. From these results, we concluded that the Ets/AP-1 site is an important cis-acting element that regulates the ADRP gene expression in macrophages.

Adipose Tissue↗

[Utilization of compressed Chinese fir thinning wood].

With Chinese fir thinnings as raw material, and through measuring the physical-mechanical indices of its compressed wood, observing the variation of its microstructure and using IR analysis, an optimized technique of compressing Chinese fir thinnings was established. The technique was: compression ratio 50%-60%, thickness after compression 20 mm, moisture content before compression 50%, compressing time 20-30 minutes, and hot compressing temperature 180-200 degrees C. CH, an environmentally friendly cooking additive, had positive effects on softening the wood. During compressing, only the cells of fast-growing Chinese fir were extruded, their cavity became smaller, while the cell wall was not destroyed. The thickness reversion ratio of compressed wood was 2.68%, and its size stability and mechanical quality were as good as hardwoods (Betula lumninifera).

Cunninghamia↗

Pharmacokinetics and in vitro and in vivo anti-tumor response of an interleukin-2-human serum albumin fusion protein in mice.

PURPOSE: Albuleukin fusion protein is a recombinant human interleukin-2 (rIL-2) genetically fused to recombinant human serum albumin (rHSA). The pharmacokinetics and pharmacologic activity of Albuleukin were examined in mice to determine whether the fusion protein had the immunomodulatory and anti-tumor properties of rIL-2 as well as a prolonged serum half-life due to the rHSA. METHODS: The effect of Albuleukin on lymphocyte proliferation, IL-2 receptor binding, and release of IFN-gamma from human NK cells were examined in vitro. For the pharmacokinetic analysis, Albuleukin and rIL-2 were administered intravenously (i.v.) and subcutaneously (s.c.) to BALB/c mice, both at a single dose of 500 microg/kg. The anti-tumor properties of Albuleukin were evaluated in a Renca tumor model in BALB/c mice and in a metastatic liver model of B16F10 melanoma in C57B1/6 mice. In the Renca tumor model, BALB/c mice were dosed intraperitoneally (i.p.) and s.c. with Albuleukin on days 12, 14, 16, 19, 21, and 23 and i.p. with rIL-2 daily for two periods of 5 days (days 10-14 and 17-21). In the B16 melanoma model, C57B1/6 mice were dosed s.c. with rIL-2 twice daily or Albuleukin every 48 h for 14 days. RESULTS: In vitro, Albuleukin induced the proliferation of primary human and mouse T cells and B cells and primary human NK cells, competed with rIL-2 for binding to the IL-2 receptors, and induced the production of IFN-gamma from primary human NK cells. The s.c. bioavailability of Albuleukin was about 45% relative to the i.v. dose. Plasma half-life was prolonged and ranged from 6 to 8 h with Albuleukin, compared to 19-57 min with rIL-2. Total clearance of Albuleukin was about 50-fold slower than that of rIL-2 after i.v. dosing. In vivo, Albuleukin suppressed the growth of Renca tumors and induced a dense infiltration of CD4+ and CD8+ T cells. Both Albuleukin and rIL-2 significantly reduced the tumor burden in mice with hepatic B16F10 metastases. Albuleukin significantly reduced the incidence of residual macroscopic hepatic tumors, resulting in improved survival relative to controls and rIL-2. CONCLUSION: Results from these studies suggest that the therapeutic efficacy of rIL-2 is improved in mice by prolonging its in vivo half-life through genetic fusion to albumin. Albuleukin, the fusion protein, had pronounced anti-tumor effects in Renca and hepatic melanoma tumor models without an increase in mortality. On the basis of its preclinical effects, Albuleukin was brought to the clinic to assess its therapeutic benefit in a variety of cancers.

Animals↗

Meclizine is an agonist ligand for mouse constitutive androstane receptor (CAR) and an inverse agonist for human CAR.

The constitutive androstane receptor (CAR, NR1I3) is a key regulator of xenobiotic and endobiotic metabolism. The ligand-binding domains of murine (m) and human (h) CAR are divergent relative to other nuclear hormone receptors, resulting in species-specific differences in xenobiotic responses. Here we identify the widely used antiemetic meclizine (Antivert; Bonine) as both an agonist ligand for mCAR and an inverse agonist for hCAR. Meclizine increases mCAR transactivation in a dose-dependent manner. Like the mCAR agonist 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene, meclizine stimulates binding of steroid receptor coactivator 1 to the murine receptor in vitro. Meclizine administration to mice increases expression of CAR target genes in a CAR-dependent manner. In contrast, meclizine suppresses hCAR transactivation and inhibits the phenobarbital-induced expression of the CAR target genes, cytochrome p450 monooxygenase (CYP)2B10, CYP3A11, and CYP1A2, in primary hepatocytes derived from mice expressing hCAR, but not mCAR. The inhibitory effect of meclizine also suppresses acetaminophen-induced liver toxicity in humanized CAR mice. These results demonstrate that a single compound can induce opposite xenobiotic responses via orthologous receptors in rodents and humans.

Animals↗

Enhanced axonal growth into a spinal cord contusion injury site in a strain of mouse (129X1/SvJ) with a diminished inflammatory response.

After injury in the adult central nervous system, invading and intrinsic cells contribute to the formation of a lesion site that is refractory to axonal growth. To test the hypothesis that the inflammatory response to trauma dictates the extent of axonal growth after spinal cord injury, the time course of lesion evolution was compared in two mouse strains with contrasting cellular responses to peripheral inflammatory challenge. Adult C57Bl/6 and 129X1/SvJ mice received identical contusion injuries to the mid-thoracic spinal cord and were allowed to recover for 6 hours to 9 weeks. Both strains responded with a rapid, transient increase in chemokine expression, but the magnitude of this early response was slightly reduced in the 129X1/SvJ mice. Morphological indicators of inflammation were similar during the first week postinjury. After 7 days postinjury, however, the cellular responses differed between strains. The C57Bl/6 lesion core was chronically occupied by macrophages, devoid of astrocytes, and contained few axonal profiles. In contrast, as the macrophage density decreased a network of astrocytic processes and axons of central and peripheral origin invaded the center of the lesion site in 129X1Sv/J mice. Growth of axons in the 129X1Sv/J mice was accompanied by increased extravascular laminin in the lesion core and a reduced expression of chondroitin sulfate proteoglycan glycosaminoglycan sidechains in the periphery of the lesion. These results demonstrate that the diminished chronic inflammatory response in 129X1/SvJ mice is associated with enhanced cellular repair and increased axonal growth after spinal cord injury.

Animals↗

Regulation of PPARgamma coactivator 1alpha (PGC-1alpha) signaling by an estrogen-related receptor alpha (ERRalpha) ligand.

Peroxisome proliferator-activated receptor gamma (PPARgamma) coactivator 1alpha (PGC-1alpha) is a transcriptional coactivator that is a key component in the regulation of energy production and utilization in metabolic tissues. Recent work has identified PGC-1alpha as a strong coactivator of the orphan nuclear receptor estrogen-related receptor alpha (ERRalpha), implicating ERRalpha as a potential mediator of PGC-1alpha action. To understand the role of ERRalpha in PGC-1alpha signaling, a parallel approach of high-throughput screening and gene-expression analysis was used to identify ERRalpha small-molecule regulators and target genes. We report here the identification of a potent and selective ERRalpha inverse agonist that interferes effectively with PGC-1alpha/ERRalpha-dependent signaling. This inverse agonist inhibits the constitutive activity of ERRalpha in both biochemical and cell-based assays. Also, we demonstrate that monoamine oxidase B is an ERRalpha target gene whose expression is regulated by PGC-1alpha and ERRalpha and inhibited by the ERRalpha inverse agonist. The discovery of potent and selective ERRalpha modulators and their effect on PGC-1alpha signaling provides mechanistic insight into gene regulation by PGC-1alpha. These findings validate ERRalpha as a promising therapeutic target in the treatment of metabolic disorders, including diabetes and obesity.

Animals↗

TL1A synergizes with IL-12 and IL-18 to enhance IFN-gamma production in human T cells and NK cells.

TL1A, a recently described TNF-like cytokine that interacts with DR3, costimulates T cells and augments anti-CD3 plus anti-CD28 IFN-gamma production. In the current study we show that TL1A or an agonistic anti-DR3 mAb synergize with IL-12/IL-18 to augment IFN-gamma production in human peripheral blood T cells and NK cells. TL1A also enhanced IFN-gamma production by IL-12/IL-18 stimulated CD56(+) T cells. When expressed as fold change, the synergistic effect of TL1A on cytokine-induced IFN-gamma production was more pronounced on CD4(+) and CD8(+) T cells than on CD56(+) T cells or NK cells. Intracellular cytokine staining showed that TL1A significantly enhanced both the percentage and the mean fluorescence intensity of IFN-gamma-producing T cells in response to IL-12/IL-18. The combination of IL-12 and IL-18 markedly up-regulated DR3 expression in NK cells, whereas it had minimal effect in T cells. Our data suggest that TL1A/DR3 pathway plays an important role in the augmentation of cytokine-induced IFN-gamma production in T cells and that DR3 expression is differentially regulated by IL-12/IL-18 in T cells and NK cells.

CD56 Antigen↗

3C-like proteinase from SARS coronavirus catalyzes substrate hydrolysis by a general base mechanism.

SARS 3C-like proteinase has been proposed to be a key enzyme for drug design against SARS. Lack of a suitable assay has been a major hindrance for enzyme kinetic studies and a large-scale inhibitor screen for SARS 3CL proteinase. Since SARS 3CL proteinase belongs to the cysteine protease family (family C3 in clan CB) with a chymotrypsin fold, it is important to understand the catalytic mechanism of SARS 3CL proteinase to determine whether the proteolysis proceeds through a general base catalysis mechanism like chymotrypsin or an ion pair mechanism like papain. We have established a continuous colorimetric assay for SARS 3CL proteinase and applied it to study the enzyme catalytic mechanism. The proposed catalytic residues His41 and Cys145 were confirmed to be critical for catalysis by mutating to Ala, while the Cys145 to Ser mutation resulted in an active enzyme with a 40-fold lower activity. From the pH dependency of catalytic activity, the pK(a)'s for His41 and Cys145 in the wild-type enzyme were estimated to be 6.38 and 8.34, while the pK(a)'s for His41 and Ser145 in the C145S mutant were estimated to be 6.15 and 9.09, respectively. The C145S mutant has a normal isotope effect in D(2)O for general base catalysis, that is, reacts slower in D(2)O, while the wild-type enzyme shows an inverse isotope effect which may come from the lower activation enthalpy. The pK(a) values measured for the active site residues and the activity of the C145S mutant are consistent with a general base catalysis mechanism and cannot be explained by a thiolate-imidazolium ion pair model.

Alanine↗

Potential role for TL1A, the new TNF-family member and potent costimulator of IFN-gamma, in mucosal inflammation.

TNF can potentiate IFN-gamma production by activated T cells and other members of the TNF-superfamily play key roles in this effect. A newly discovered TNF-superfamily cytokine (TL1A) could also be involved in initiating or promoting the Th1 response by enhancing IFN-gamma production. The purpose of this study was to assess the role of recombinant TL1A on IFN-gamma production by cultured PBMC and lamina propria LPMC and to determine whether TL1A expression is altered in inflammatory bowel disease. IFN-gamma, but not IL-4 or IL-10 production by PBMC and LPL, was dose-dependently augmented by TL1A (or by activation of its receptor, death domain receptor 3 [DR3], with specific mAb) independently of, but in synergy with, IL-12 and IL-18. T cell activating stimuli induced expression of TL1A on the cell membrane (mb-TL1A) in a fraction of peripheral blood (PB) T cells. In the intestinal mucosa, a fraction of lamina propria (LP) T cells, especially CD4+ cells, constitutively expressed mb-TL1A, and the fraction increased in mucosal inflammation. A higher fraction of cells also express the TL1A receptor DR3 in ulcerative colitis and Crohn's disease. TL1A transcript was several times more abundant in RNA from mucosal biopsies taken from inflamed Crohn's disease lesions than in those taken from uninvolved areas. Expression of TL1A and its receptor DR3 by lamina propria mononuclear cells (LPMC) could have significant influence on the severity of mucosal inflammation.

Biopsy↗

Alterations in the distribution and orexigenic effects of dexamethasone in CAR-null mice.

The constitutive androstane receptor (CAR, NR1I3) has emerged as an important regulator of drug metabolism. CAR responds to a wide spectrum of xenobiotics by inducing expression of cytochrome P450 (CYP) enzymes and a number of other proteins responsible for drug metabolism in the liver. The xenosensor function of CAR overlaps with that of the pregnane X receptor (PXR), another xenobiotic receptor that belongs to the nuclear hormone superfamily. We observed that injection of dexamethasone (Dex), a ligand for the glucocorticoid receptor (GR) and PXR but not CAR, results in an unexpected twofold increase in the stomach weight of CAR-null animals relative to wild-type animals. Here, we show that CAR knockout mice have elevated levels of Dex in the brain, resulting in a more rapid and robust increase in the hypothalamic expression of the GR-responsive target genes encoding neuropeptide Y (NPY) and neuropeptide Y receptor subtype 1 (NPY-R1). As expected, this is accompanied by a higher increase in the food intake of the CAR-null animals. The data described here highlight the complexity of the overlapping functions of CAR and PXR.

Animals↗

Expression, localization, and functional activity of TL1A, a novel Th1-polarizing cytokine in inflammatory bowel disease.

TL1A is a novel TNF-like factor that acts as a costimulator of IFN-gamma secretion through binding to the death domain-containing receptor, DR3. The aim of this study was to test the hypothesis that TL1A may play an important role in inflammatory bowel disease (IBD) by functioning as a Th1-polarizing cytokine. The expression, cellular localization, and functional activity of TL1A and DR3 were studied in intestinal tissue specimens as well as isolated lamina propria mononuclear cells from IBD patients and controls. TL1A mRNA and protein expression was up-regulated in IBD, particularly in involved areas of Crohn's disease (CD; p < 0.03 vs control). TL1A production was localized to the intestinal lamina propria in macrophages and CD4(+) and CD8(+) lymphocytes from CD patients as well as in plasma cells from ulcerative colitis patients. The amount of TL1A protein and the number of TL1A-positive cells correlated with the severity of inflammation, most significantly in CD. Increased numbers of immunoreactive DR3-positive T lymphocytes were detected in the intestinal lamina propria from IBD patients. Addition of recombinant human TL1A to cultures of PHA-stimulated lamina propria mononuclear from CD patients significantly augmented IFN-gamma production by 4-fold, whereas a minimal effect was observed in control patients. Our study provides evidence for the first time that the novel cytokine TL1A may play an important role in a Th1-mediated disease such as CD.

Blotting, Western↗

Biosynthesis, purification, and substrate specificity of severe acute respiratory syndrome coronavirus 3C-like proteinase.

The 3C-like proteinase of severe acute respiratory syndrome (SARS) coronavirus has been proposed to be a key target for structural-based drug design against SARS. In order to understand the active form and the substrate specificity of the enzyme, we have cloned, expressed, and purified SARS 3C-like proteinase. Analytic gel filtration shows a mixture of monomer and dimer at a protein concentration of 4 mg/ml and mostly monomer at 0.2 mg/ml, which correspond to the concentration used in the enzyme assays. The linear decrease of the enzymatic-specific activity with the decrease of enzyme concentration revealed that only the dimeric form is active and the dimeric interface could be targeted for structural-based drug design against SARS 3C-like proteinase. By using a high pressure liquid chromatography assay, SARS 3C-like proteinase was shown to cut the 11 peptides covering all of the 11 cleavage sites on the viral polyprotein with different efficiency. The two peptides corresponding to the two self-cleavage sites are the two with highest cleavage efficiency, whereas peptides with non-canonical residues at P2 or P1' positions react slower. The P2 position of the substrates seems to favor large hydrophobic residues. Secondary structure studies for the peptide substrates revealed that substrates with more beta-sheetlike structure tend to react fast. This study provides a basic understanding of the enzyme catalysis and a full substrate specificity spectrum for SARS 3C-like proteinase, which are helpful for structural-based inhibitor design against SARS and other coronavirus.

Catalysis↗

TL1A-induced NF-kappaB activation and c-IAP2 production prevent DR3-mediated apoptosis in TF-1 cells.

We recently identified TL1A, an endothelium-derived T cell costimulator and a ligand for tumor necrosis factor receptor superfamily members DR3 and decoy receptor 3. To elucidate the signaling events triggered by TL1A-DR3 interaction and to understand the molecular mechanisms regulating DR3-mediated apoptosis, we have studied the effect of TL1A and an agonistic DR3 monoclonal antibody in human erythroleukemic TF-1 cells, which express DR3 endogenously. TL1A induced the formation of a DR3 signaling complex containing TRADD, TRAF2, and RIP and activated the NF-kappaB and the ERK, JNK, and p38 mitogen-activated protein kinase pathways. However, TL1A or an agonistic DR3 monoclonal antibody did not induce apoptosis in these cells nor were there detectable levels of FADD or procaspase-8 seen in the signaling complex. Interestingly, DR3-mediated apoptosis was induced in TF-1 cells in the presence of a NF-kappaB pathway-specific inhibitor but not in the presence of mitogen-activated protein kinase inhibitors, either alone or in combination, suggesting that DR3-induced NF-kappaB activation was responsible for resistance to apoptosis in these cells. Consistent with this, we found that TL1A significantly increased the production of c-IAP2, a known NF-kappaB-dependent anti-apoptotic protein, and that the NF-kappaB inhibitor or cycloheximide prevented its synthesis. Furthermore, inhibition of c-IAP2 production by RNA interference significantly sensitized TF-1 cells to TL1A-induced apoptosis. Our study identifies a molecular mechanism by which TL1A and DR3 regulate cell fate in TF-1 cells.

Antibodies, Monoclonal↗

Quantification of 8-iso-prostaglandin-F(2alpha) and 2,3-dinor-8-iso-prostaglandin-F(2alpha) in human urine using liquid chromatography-tandem mass spectrometry.

Quantification of 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) has been suggested to be a reliable indicator of lipid peroxidation that may be related to in vivo free radical generation, oxidative damage, and antioxidant deficiency. We have developed a LC-MS/MS method to quantify 8-iso- PGF(2alpha) and its dinor metabolite, 2,3-dinor-8-iso-prostaglandin F(2alpha) (2,3-dinor-8-iso-PGF(2alpha)), in human urine samples. After an initial purification step using an automated C18 solid phase extraction procedure, the urine sample was injected directly into a liquid chromatography (LC) system and detected with tandem mass spectrometry. The detection limit of the assay was 9 pg for 8-iso-PGF(2alpha) and 3 pg for 2,3-dinor-8-iso-PGF(2alpha) with both inter- and intraday variations of less than 12%. The inaccuracies were less than 3% for both analytes at three different levels. The urinary excretion rate of 2,3-dinor-8-iso-PGF(2alpha) was higher than that of 8-iso-PGF(2alpha), and changed in proportion to the parent compound (R = 0.70, n = 60). Values obtained with this method showed good linear correlation to duplicate 8-iso-PGF(2alpha) measurements performed with GCMS (R = 0.97, n = 15). The mean excretion rates of 8-iso-PGF(2alpha) and 2,3-dinor-8-iso-PGF(2alpha) were significantly higher in smokers than in nonsmokers (0.53 +/- 0.37 vs. 0.25 +/- 0.15 microg/g creatinine, p = 0.002 for 8-iso-PGF(2alpha) and 8.9 +/- 3.8 vs. 4.6 +/- 2.6 microg/g creatinine, p = 0.003 for 2,3-dinor-8-iso-PGF(2alpha), respectively). The excellent accuracy, reproducibility, and high throughput of this method should permit it to be used in large clinical studies and standard clinical laboratories.

Chromatography, High Pressure Liquid↗

Concordant down-regulation of proto-oncogene PML and major histocompatibility antigen HLA class I expression in high-grade prostate cancer.

Recognition of tumor cells by cytolytic T lymphocytes depends on cell surface MHC class I expression. As a mechanism to evade T cell recognition, many malignant cancer cells, including those of prostate cancer, down-regulate MHC class I. For the majority of human cancers, the molecular mechanism of MHC class I down regulation is unclear, although it is well established that MHC class I down-regulation is often associated with the down-regulation of multiple genes devoted to antigen presentation. Since the promyelocytic leukemia (PML) proto-oncogene controls multiple antigen-presentation genes in some murine cancer cells, we analyzed the expression of proto-oncogene PML and MHC class I in high-grade prostate cancer. We found that 30 of 37 (81%) prostate adenocarcinoma cases with a Gleason grade of 7-8 had more than 50% down-regulation of HLA class I expression. Among these, 22 cases (73.3%) had no detectable PML protein, while 4 cases (13.3%) showed partial PML down-regulation. In contrast, all 7 cases of prostate cancer with high expression of cell surface HLA class I had high levels of PML expression. Concordant down-regulation of HLA and PML was observed in different histological patterns of prostate adenocarcinoma. These results suggest that in high-grade prostate cancer, malfunction of proto-oncogene PML is a major factor in the down-regulation of cell surface HLA class I molecules, the target molecules essential for the direct recognition of cancer cells by cytolytic T lymphocytes.

Adenocarcinoma↗

Modulation of acetaminophen-induced hepatotoxicity by the xenobiotic receptor CAR.

We have identified the xenobiotic receptor CAR (constitutive androstane receptor) as a key regulator of acetaminophen metabolism and hepatotoxicity. Known CAR activators as well as high doses of acetaminophen induced expression of three acetaminophen-metabolizing enzymes in wild-type but not in CAR null mice, and the CAR null mice were resistant to acetaminophen toxicity. Inhibition of CAR activity by administration of the inverse agonist ligand androstanol 1 hour after acetaminophen treatment blocked hepatotoxicity in wild type but not in CAR null mice. These results suggest an innovative therapeutic approach for treating the adverse effects of acetaminophen and potentially other hepatotoxic agents.

Acetaminophen↗

A chimeric open reading frame associated with cytoplasmic male sterility in alloplasmic wheat with Triticum timopheevi mitochondria is present in several Triticum and Aegilops species, barley, and rye.

Mitochondrial DNA from Triticum timopheevi has a chimeric gene, orf256, upstream of coxI. This gene is cotranscribed with coxI in cytoplasmic male sterile plants and produces a 7-kDa protein which is not produced in fertile or fertility-restored plants. T. aestivum, the nuclear donor in sterile plants, does not have orf256. Analysis by polymerase chain reaction of DNA from barley, rye, Aegilops bicornis, Ae. searsii, Ae. sharonensis, Ae. speltoides, Ae. tauschii, T. monococcum, and T. turgidum was done with oligonucleotide primers designed to detect orf256 or coxI sequences. Except for T. turgidum, these plants have various elements of the orf256 sequence over a 1-kb length of DNA immediately upstream of coxI in exactly the same arrangement as is found in the coxI region of T. timopheevi. Only T. timopheevi and Ae. speltoides have orf256 transcripts, and only cytoplasmic male-sterile plants involving these two species as maternal donors produce a protein from orf256. Part of an orf256-like sequence is present in T. turgidum but is at least slightly different in arrangement relative to coxI, as compared with the sequence in T. timopheevi. Neither maize nor sorghum have the orf256 sequence.

Cell Nucleus↗