Biomedical subjects

Wei Zhang

Publications and source records attributed to Wei Zhang.

At least 127 records · Page 7Linked to original sources

PubMed2006

Phenol red interacts with the protofibril-like oligomers of an amyloidogenic hexapeptide NFGAIL through both hydrophobic and aromatic contacts.

Amyloid-associated diseases affect millions of people worldwide. Phenol red exhibits modest inhibition toward fibril formation of human Islet amyloid polypeptide (hIAPP) and its toxicity, which is associated with type II diabetes mellitus. However, the molecular level mechanisms of interactions remain elusive. The binding of phenol red molecules to the protofibrils of an amyloidogenic fragment (NFGAIL) of hIAPP has been investigated by molecular dynamics simulations with explicit solvent. The phenol red molecules were observed to bind primarily along either beta-sheet stacking or beta-strand directions. Through its three aromatic rings, the phenol red molecule preferentially interacted with the hydrophobic side chains of Phe, Leu, and Ile; and the polar sulfone and hydroxyl groups were mainly exposed in solvent. Thus, phenol red improves the solubility of the early protofibrils and represses further growth. Interestingly, there was no obvious preference toward the aromatic Phe residue in comparison to the hydrophobic Leu or Ile residues. The lack of binding along the hydrogen bond direction indicates that phenol red does not directly block the beta-sheet extension. Further free energy analysis suggested that a phenol red analog may potentially improve the binding affinity.

Amyloid↗

PubMed2006

Casq2 deletion causes sarcoplasmic reticulum volume increase, premature Ca2+ release, and catecholaminergic polymorphic ventricular tachycardia.

Cardiac calsequestrin (Casq2) is thought to be the key sarcoplasmic reticulum (SR) Ca2+ storage protein essential for SR Ca2+ release in mammalian heart. Human CASQ2 mutations are associated with catecholaminergic ventricular tachycardia. However, homozygous mutation carriers presumably lacking functional Casq2 display surprisingly normal cardiac contractility. Here we show that Casq2-null mice are viable and display normal SR Ca2+ release and contractile function under basal conditions. The mice exhibited striking increases in SR volume and near absence of the Casq2-binding proteins triadin-1 and junctin; upregulation of other Ca2+ -binding proteins was not apparent. Exposure to catecholamines in Casq2-null myocytes caused increased diastolic SR Ca2+ leak, resulting in premature spontaneous SR Ca2+ releases and triggered beats. In vivo, Casq2-null mice phenocopied the human arrhythmias. Thus, while the unique molecular and anatomic adaptive response to Casq2 deletion maintains functional SR Ca2+ storage, lack of Casq2 also causes increased diastolic SR Ca2+ leak, rendering Casq2-null mice susceptible to catecholaminergic ventricular arrhythmias.

Alleles↗

PubMed2006

Inhibition of CD147 gene expression via RNA interference reduces tumor cell invasion, tumorigenicity and increases chemosensitivity to paclitaxel in HO-8910pm cells.

Overexpression of extracellular matrix metalloproteinase inducer (EMMPRIN or CD147), a member of the immunoglobulin family and a glycoprotein enriched on the surface of tumor cells, promotes invasion, metastasis, growth and survival of malignant cells, and confers resistance to some chemotherapeutic drugs. Here, we used a human U6 promoter-driven DNA template approach to induce short hairpin RNA (shRNA)-triggered RNA interference (RNAi) to block CD147 gene expression in the human ovarian cancer cell line HO-8910pm. Knockdown of CD147 by shRNA resulted in decrease of the HO-8910pm invasion activity in vitro and tumorigenicity in nude mice. The suppression of CD147 expression also sensitized cells to be more sensitive to paclitaxel. These results suggested that CD147 was an ovarian cancer-related gene and CD147 might be a potential target for therapeutic anti-cancer drugs.

Animals↗

PubMed2006

Treatment of alternated water-electrolyte balance and endocrine status after removal of craniopharyngioma in adults.

BACKGROUND: Water-electrolyte disturbance and endocrine alterations are common complications of adult patients with craniopharygioma in the postoperative period and may affect their recovery and prognosis. Some of these complications even lead to death. Appropriate remedy based upon the status of water-electrolyte balance and the endocrine system is essential to good therapeutic results of adult patients with craniopharyngioma. METHODS: The alterations in water-electrolyte balance (117 patients) and endocrine status (42) of adult patients with craniopharyngioma after surgery were analyzed retrospectively. RESULTS: Most patients with craniopharyngioma experienced postoperative water-electrolyte disturbances and hypotonic dehydration. Moreover, the incidences of hypothyroidism and hypoadrenocorticism were relatively high. CONCLUSION: It is critical to deal with dehydration and endocrine disorders for a sound outcome of craniopharyngioma surgery.

Adolescent↗

PubMed2006

Quantitative analysis of lovastatin in capsule of Chinese medicine monascus by capillary zone electrophoresis with UV-vis detector.

A capillary zone electrophoresis (CZE) method was developed for the quantitative analysis of lovastatin (Lvt) in capsule of monascus-Chinese medicine. Lvt in the capsule was separated using an electrolyte system consisting of 16% ethanol (v/v) in 60 mM Gly-sodium hydroxide buffer, pH 10.5, 16 kV applied voltage, 238 nm detection wavelength with a capillary of 51 cm x 75 microm i.d (43 cm to detector). Under the optimized conditions, the linear response of Lvt concentration ranges from 4.0 to 240 microg/mL with high correlation coefficient (r=0.9998, n=9), the limits of detection (LOD) and quantification (LOQ) for Lvt are 0.73 and 2.42 microg/mL, the precision values (expressed as R.S.D.) of intra-day and inter-day are 1.40-2.12% and 1.47-3.88%, respectively. The recoveries of the analyte at three concentration levels are 90.28-100.71%. The developed method can be well used for the quantification of Lvt in the drug in commercial formulations.

Buffers↗

PubMed2006

West Nile virus in complex with the Fab fragment of a neutralizing monoclonal antibody.

Flaviviruses, such as West Nile virus (WNV), are significant human pathogens. The humoral immune response plays an important role in the control of flavivirus infection and disease. The structure of WNV complexed with the Fab fragment of the strongly neutralizing mAb E16 was determined to 14.5-Angstrom resolution with cryo-electron microscopy. E16, an antibody with therapeutic potential, binds to domain III of the WNV envelope glycoprotein. Because of steric hindrance, Fab E16 binds to only 120 of the 180 possible binding sites on the viral surface. Fitting of the previously determined x-ray structure of the Fab-domain III complex into the cryo-electron microscopy density required a change of the elbow angle between the variable and constant domains of the Fab. The structure suggests that the E16 antibody neutralizes WNV by blocking the initial rearrangement of the E glycoprotein before fusion with a cellular membrane.

Animals↗

PubMed2006

Coimmunization with IL-15 plasmid enhances the longevity of CD8 T cells induced by DNA encoding hepatitis B virus core antigen.

AIM: To test the feasibility of delivering a plasmid encoding IL-15 as a DNA vaccine adjuvant for improving the immune responses induced by hepatitis B virus core gene DNA vaccine. METHODS: We used RT-PCR based strategies to develop IL-15 expression constructs. We first confirmed that the gene could be expressed in Escherichia coli due to the poor expression of IL-15. Then the bioactivity of IL-15 plasmid expression product was identified by CTLL-2 proliferation assay. One hundred micrograms of DNA from each of the IL-15 eukaryotic expressed plasmid and the recombinant plasmid harboring DNA encoding the 144 amino acids of the N-terminus of HBV core gene (abbreviated pHBc144) was used to co-immunize C57 BL/6 mice. The titer of anti-HBcIgG was detected by ELISA and the antigen-specific CD8(+) T cells (CD8(+)IFN-gamma(+) T cells) were detected by intracellular cytokine staining at different time points. RESULTS: After co-immunization by pIL-15 and pHBc144 DNA vaccine the antigen-specific CD8(+) cells of mice increased gradually, the first peak of immune response appeared 14 d later, then the number of antigen-specific CD8(+) Ts cells decreased gradually and maintained at a steady level in 3 mo. After boosting, the number of antigen-specific CD8(+) T cells reached the second peak 10 d later with a double of the 1st peak, then the number of antigen-specific CD8(+) T cells decreased slowly. IL-15 as a gene adjuvant had no significant effect on humoral immune responses induced by hepatitis B virus core gene DNA vaccine, but increased the memory antigen-specific CD8(+) T cells induced by hepatitis B virus core gene DNA vaccine. CONCLUSION: DNA vaccine constructed by HBc Ag 1-144 amino acid induces effective cell immunity, and cytokine plasmid-delivered IL-15 enhances the longevity of CD8(+) T cells.

Adjuvants, Immunologic↗

PubMed2006

Rapporteur report: Epidemiology.

Three talks were presented in the session on "Epidemiology". The first talk was a review of prenatal studies. The second talk presented epidemiological evidence from prenatal studies. The third talk presented general issues regarding the planning of an epidemiological study. It was noted that epidemiological studies of prenatal exposures use data from the early 1980s when ultrasound was first introduced for foetal scans. These studies did not show associations between prenatal ultrasound scanning and childhood cancer, reduced birth weight, impaired childhood growth or neurological development in childhood. However, there was a possible association between prenatal ultrasound scanning and left-handedness in boys. The aetiology of this association remains uncertain.

Epidemiologic Methods↗

PubMed2006

Single nucleotide polymorphism C677T in the methylenetetrahydrofolate reductase gene might be a genetic risk factor for infertility for Chinese men with azoospermia or severe oligozoospermia.

AIM: To analyze the distribution of the single nucleotide polymorphism (SNP) C677T in the methylenetetrahydrofolate reductase (MTHFR) gene in 355 infertile Chinese patients with idiopathic azoospermia or severe oligozoospermia and 252 fertile Chinese men as controls to explore the possible association of the SNP and male infertility. METHODS: Using the polymerase chain reaction (PCR)-restriction fragment length polymorphism technique, the allele and genotype distribution of SNP C677T in the MTHFR gene were investigated in both patients and controls. RESULTS: The frequencies of allele T (40.9% vs 30.4%, P = 0.002, odds ration [OR] = 1.58, 95% confidence interval [CI]: 1.24-2.02) and mutant homozygote (TT) (18.3% vs. 11.5%, P=0.023, OR=1.72, 95% CI: 1.07-2.76) as well as carrier with allele (TT + CT) (63.4% vs. 49.2%, P = 0.0005, OR = 1.79, 95% CI: 1.29-2.48) in infertile patients were significantly higher than those in controls. After patient stratification, the significant differences in distribution of the SNP between each patient subgroup and control group still remained. CONCLUSION: Our findings indicate that there is an association of SNP C677T in the MTHFR gene with male infertility, suggesting that this polymorphism might be a genetic risk factor for male infertility in Chinese men.

Adult↗

PubMed2006

Pituitary adenylate cyclase-activating polypeptide (PACAP) 38 and PACAP4-6 are neuroprotective through inhibition of NADPH oxidase: potent regulators of microglia-mediated oxidative stress.

Microglial activation is implicated in the progressive nature of numerous neurodegenerative diseases, including Parkinson's disease. Using primary rat mesencephalic neuron-glia cultures, we found that pituitary adenylate cyclase-activating polypeptide (PACAP) 38, PACAP27, and its internal peptide, Gly-Ile-Phe (GIF; PACAP4-6), are neuroprotective at 10(-13) M against lipopolysaccharide (LPS)-induced dopaminergic (DA) neurotoxicity, as determined by [(3)H]DA uptake and the number of tyrosine hydroxylase-immunoreactive neurons. PACAP38 and GIF also protected against 1-methyl-4-phenylpyridinium(+)-induced neurotoxicity but only in cultures containing microglia. PACAP38 and GIF ameliorated the production of microglia-derived reactive oxygen species (ROS), where both LPS- and phorbol 12-myristate 13-acetate-induced superoxide and intracellular ROS were inhibited. The critical role of NADPH oxidase for GIF and PACAP38 neuroprotection against LPS-induced DA neurotoxicity was demonstrated using neuron-glia cultures from mice deficient in NADPH oxidase (PHOX(-/-)), where PACAP38 and GIF reduced tumor necrosis factor alpha production and were neuroprotective only in PHOX(+/+) cultures and not in PHOX(-/-) cultures. Pretreatment with PACAP6-38 (3 microM; PACAP-specific receptor antagonist) was unable to attenuate PACAP38, PACAP27, or GIF (10(-13) M) neuroprotection. PACAP38 and GIF (10(-13) M) failed to induce cAMP in neuronglia cultures, supporting that the neuroprotective effect was independent of traditional high-affinity PACAP receptors. Pharmacophore analysis revealed that GIF shares common chemical properties (hydrogen bond acceptor, positive ionizable, and hydrophobic regions) with other subpicomolar-acting compounds known to inhibit NADPH oxidase: naloxone, dextromethorphan, and Gly-Gly-Phe. These results indicate a common high-affinity site of action across numerous diverse peptides and compounds, revealing a basic neuropeptide regulatory mechanism that inhibits microglia-derived oxidative stress and promotes neuron survival.

Animals↗

PubMed2006

Characteristics of bone marrow-derived endothelial progenitor cells in aged mice.

Evidence for dysfunction of endothelial repair in aged mice was sought by studying the pattern of induced differentiation, quantity, and function of bone marrow-derived endothelial progenitor cells (EPCs) in aged mice. The CD117-positive stem cell population was separated from bone marrow by magnetic activated cell-sorting system (MACS), and EPCs were defined by demonstrating the expression of CD117+CD34+Flk-1+ by flow cytometry. After 7 days of culture, the number of clones formed was counted, and proliferation and migration of EPCs were analyzed by MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] assay and modified Boyden chamber assay. The results demonstrated that compared to the control group, the quantity of bone marrow-derived CD117+ stem cells and EPCs, as well as the proliferation, migration, the number of clones formed, and phagocytotic function of EPCs were significantly reduced in aged mice. There were no significant differences in the morphology and induced differentiation pattern of EPCs between the aged mouse group and the control group. Authors suggest that the dysfunction of EPCs may serve as a surrogate parameter of vascular function in old mice.

Age Factors↗

PubMed2006

Progestagenic effects of tibolone are target gene-specific in human endometrial cells.

OBJECTIVES: Tibolone (Tib) exhibits progestagenic activities in addition to its tissue-specific estrogenic activities. The purpose of the current study was to determine the progestagenic actions of Tib and its metabolites using target genes known to be regulated by progestins in human endometrial glandular and stromal cells. METHODS: Human endometrial glandular and stromal cells were isolated from endometrial tissue fragments and separately incubated with Tib and its metabolites. Real-time polymerase chain reaction (PCR) was used to determine the mRNA content of 17betahydroxy steroid dehydrogenase (17betaHSD, type 2) and sulfotransferase (SULT1E1) in endometrial glandular cells, and prolactin (PRL) and insulin-like growth factor binding protein-1 (IGFBP1) in endometrial stromal cells. RESULTS: In glandular cells, Tib and Delta4-tibolone (Delta4Tib) significantly increased the content of 17betaHSD and SULT1E1 mRNA. In stromal cells, Tib and Delta4Tib increased PRL mRNA ( approximately 30% of the capacity compared to progesterone) and had little effect on IGFBP1 mRNA. Anti-progestin, RU486, reversed the induction of SULT1E1 and PRL by progesterone or Tib. Also, the two 3 hydroxyl tobolone metabolites, especially 3betaOHTib, showed some progestagenic effects. CONCLUSIONS: The data showed that Tib and Delta4Tib exhibited clear progestagenic effects in endometrial glandular cells by inducing 17betaHSD and SULT1E1, while in stromal cells the response was weaker in the induction of PRL and had little effect on IGFBP1. In addition, the 3betaOHTib metabolite expressed progestagenic activity. These disparate effects in two types of cells may be beneficial for maintaining endometrial cells in a quiescent state.

17-Hydroxysteroid Dehydrogenases↗

PubMed2006

An adaptive dose-finding design incorporating both toxicity and efficacy.

Novel therapies are challenging the standards of drug development. Agents with specific biologic targets and limited toxicity require novel designs to determine doses to be taken forward into larger studies. In this paper, we describe an approach that incorporates both toxicity and efficacy data into the estimation of the biologically optimal dose of an agent in a phase I trial. The approach is based on the flexible continuation-ratio model, and uses straightforward optimal dose selection criteria. Dose selection is based on all patients treated up until that time point, using a continual reassessment method approach. Dose-outcome curves considered include monotonically increasing, monotonically decreasing, and unimodal curves. Our simulation studies demonstrate that the proposed design, which we call TriCRM, has favourable operating characteristics.

Algorithms↗

PubMed2006

Berberine inhibits 3T3-L1 adipocyte differentiation through the PPARgamma pathway.

Berberine (BBR), a compound purified from Cortidis rhizoma, reduces serum cholesterol, triglycerides, and LDL-cholesterol of hypercholesterolemic patients and high fat diet fed animals, and increases hepatic LDLR mRNA and protein levels through a post-transcriptional mechanism. BBR also enhances the hypoglycemic action of insulin in diabetic animal models. Here, we show that BBR inhibits the differentiation of 3T3-L1 preadipocytes induced by DM and suppresses the mitotic clonal expansion of 3T3-L1 preadipocytes in a time- and dose-dependent manner. Gene expression analysis and Western blot analysis reveal that the BBR inhibits the mRNA and protein levels of adipogenesis related transcription factors PPARgamma and C/EBPalpha and their upstream regulator, C/EBPbeta. Reporter gene assays demonstrate that the full-length PPARgamma and alpha transcription activities are inhibited by BBR. Using real-time PCR, we have also found that the PPAR target genes that are involved in adipocyte differentiation, such as aP2, CD36, ACO, LPL, and other adipocyte markers, are suppressed by BBR. These studies suggest that BBR works on multiple molecular targets as an inhibitor of PPARgamma and alpha, and is a potential weight reducing, hypolipidemic, and hypoglycemic drug.

1-Methyl-3-isobutylxanthine↗

PubMed2006

Culturable actinobacteria from the marine sponge Hymeniacidon perleve: isolation and phylogenetic diversity by 16S rRNA gene-RFLP analysis.

A total of 106 actinobacteria associated with the marine sponge Hymeniacidon perleve collected from the Yellow Sea, China were isolated using eight different media. The number of species and genera of actinobacteria recovered from the different media varied significantly, underlining the importance of optimizing the isolation conditions. The phylogenetic diversity of the actinobacteria isolates was assessed using 16S rRNA gene amplification-restriction fragment length polymorphism (RFLP) analysis of the 106 strains with different morphologies. The RFLP fingerprinting of selected strains by HhaI-digestion of the 16S rRNA genes resulted in 11 different patterns. The HhaI-RFLP analysis gave good resolution for the identification of the actinobacteria isolates at the genus level. A phylogenetic analysis using 16S rRNA gene sequences revealed that the isolates belonged to seven genera of culturable actinobacteria including Actinoalloteichus, Micromonospora, Nocardia, Nocardiopsis, Pseudonocardia, Rhodococcus, and Streptomyces. The dominant genus was Streptomyces, which represented 74% of the isolates. Three of the strains identified are candidates for new species.

Actinobacteria↗

PubMed2006

Mice with the R176Q cardiac ryanodine receptor mutation exhibit catecholamine-induced ventricular tachycardia and cardiomyopathy.

Mutations in the cardiac ryanodine receptor 2 (RyR2) have been associated with catecholaminergic polymorphic ventricular tachycardia and a form of arrhythmogenic right ventricular dysplasia. To study the relationship between RyR2 function and these phenotypes, we developed knockin mice with the human disease-associated RyR2 mutation R176Q. Histologic analysis of hearts from RyR2(R176Q/+) mice revealed no evidence of fibrofatty infiltration or structural abnormalities characteristic of arrhythmogenic right ventricular dysplasia, but right ventricular end-diastolic volume was decreased in RyR2(R176Q/+) mice compared with controls, indicating subtle functional impairment due to the presence of a single mutant allele. Ventricular tachycardia (VT) was observed after caffeine and epinephrine injection in RyR2(R176Q/+), but not in WT, mice. Intracardiac electrophysiology studies with programmed stimulation also elicited VT in RyR2(R176Q/+) mice. Isoproterenol administration during programmed stimulation increased both the number and duration of VT episodes in RyR2(R176Q/+) mice, but not in controls. Isolated cardiomyocytes from RyR2(R176Q/+) mice exhibited a higher incidence of spontaneous Ca(2+) oscillations in the absence and presence of isoproterenol compared with controls. Our results suggest that the R176Q mutation in RyR2 predisposes the heart to catecholamine-induced oscillatory calcium-release events that trigger a calcium-dependent ventricular arrhythmia.

Animals↗

PubMed2006

New insights from the structure-function analysis of the catalytic region of human platelet phosphodiesterase 3A: a role for the unique 44-amino acid insert.

Human phosphodiesterase 3A (PDE3A) degrades cAMP, the major inhibitor of platelet function, thus potentiating platelet function. Of the 11 human PDEs, only PDE3A and 3B have 44-amino acid inserts in the catalytic domain. Their function is not clear. Incubating Sp-adenosine-3',5'-cyclic-S-(4-bromo-2,3-di-oxobutyl) monophosphorothioate (Sp-cAMPS-BDB) with PDE3A irreversibly inactivates the enzyme. High pressure liquid chromatography (HPLC) analysis of a tryptic digest yielded an octapeptide within the insert of PDE3A ((K)T(806)YNVTDDK(813)), suggesting that a substrate-binding site exists within the insert. Because Sp-cAMPS-BDB reacts with nucleophilic residues, mutants Y807A, D811A, and D812A were produced. Sp-cAMPS-BDB inactivates D811A and D812A but not Y807A. A docking model showed that Tyr(807) is 3.3 angstroms from the reactive carbon, whereas Asp(811) and Asp(812) are >15 angstroms away from Sp-cAMPS-BDB. Y807A has an altered K(m) but no change in k(cat). Activity of wild type but not Y807A is inhibited by an anti-insert antibody. These data suggest that Tyr(807) is modified by Sp-cAMPS-BDB and involved in substrate binding. Because the homologous amino acid in PDE3B is Cys(792), we prepared the mutant Y807C and found that its K(m) and k(cat) were similar to the wild type. Moreover, Sp-cAMPS-BDB irreversibly inactivates Y807C with similar kinetics to wild type, suggesting that the tyrosine may, like the cysteine, serve as a H donor. Kinetic analyses of nine additional insert mutants reveal that H782A, T810A, Y814A, and C816S exhibit an altered k(cat) but not K(m), indicating that catalysis is modulated. We document a new functional role for the insert in which substrate binding may produce a conformational change. This change would allow the substrate to bind to Tyr(807) and other amino acids in the insert to interact with residues important for catalysis in the active site cleft.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2006

The positive feedback role of arachidonic acid in the platelet-derived growth factor-induced signaling in lens epithelial cells.

PURPOSE: Platelet-derived growth factor (PDGF)-stimulated cell proliferation has been associated with reactive oxygen species (ROS)-mediated redox signaling. This study examined the role of arachidonic acid (AA) in PDGF-stimulated ROS generation in human lens epithelial B3 cells (HLE B3). METHODS: PDGF (1 ng/ml)-stimulated ROS generation was examined using dichlorofluorescein (DCFH)-activated fluorescence by laser confocal microscopy while AA (30-150 muM)-stimulated superoxide anion production was measured using lucigenin-amplified chemiluminescence in serum-starved HLE B3 cells. PDGF-stimulated AA release was quantified by cells prelabeled with (3)H-AA with and without the presence of cytosolic phospholipase A(2) (cPLA(2)) inhibitor (AACOCF(3)) and mitogen-activated protein (MAP) kinases (MEK) inhibitor (U0126). Western blot analysis was used to characterize the activated MAP kinase components in cell lysates or protein kinase C (PKC) translocation in isolated cytosolic and membrane fractions. Specific inhibitors to various enzymes were used in the study, including GF109203X for pan protein kinase C (PKC), AACOCF3 for cytosolic phospholipase A2 (cPLA(2)), U0126 for MEK, and DPI for NADPH oxidase. Inhibitors for AA metabolism were also used to examine the role of AA in PDGF-stimulated ROS generation, including CDC and NDGA for pan lipoxygenase, AA861 for 5-lipoxygenase, indomethacin for cycloxygenase, and ketoconazole for cytochrome p450. RESULTS: We found that PDGF-stimulated ROS was eradicated by inhibitors to MEK, cPLA(2), 5-lipoxygenase, NADPH oxidase, or PKC. PDGF-stimulated AA release depended on both active cPLA(2) and ERK1/2. Exogenous AA showed a concentration-dependent ROS generation via NADPH oxidase activation that was insensitive to MEK inhibitor, but sensitive to PKC inhibitor, and could be attenuated by superoxide dismutase (SOD), mannitol, or DPI. This effect of AA was specific as other long chain fatty acids (leinoleic acid, stearic acid), or AA derivatives (eicosa-11Z, 14Z, 17Z-trienoic acid (20:3) and eicosa-11Z, 14Z-dienoic acid (20:2)) were ineffective. Inhibitor to lipoxygenase, in particular the 5-isoform, but not cycloxygenase or cytochrome p450, could diminish AA-stimulated luminescence generation. Western blot analysis showed that AA-treated cells transiently activated ERK1/2 and JNK, but not p38, in a time- and dose-dependent manner that was similar to that of PDGF. Finally, PDGF-stimulated PKC translocation depended on AA release while AA-stimulated PKC translocation was eradicated by lipoxygenase inhibition. CONCLUSIONS: We conclude that PDGF signaling in HLE B3 cells is mediated by AA and its lipoxygenase metabolites, which provide a positive feedback loop for PDGF action, as AA and its metabolites can mobilize PKC and other factors needed for NADPH oxidase assembly and activation for ROS generation to facilitate cell proliferation. We further propose the role of AA in PDGF signaling.

Animals↗