Biomedical subjects

Min Wu

Publications and source records attributed to Min Wu.

At least 127 records · Page 7Linked to original sources

PubMed2004

[Analysis of partial sequence of the gene for a novel Br protein].

A strain of halophilic archaeum AB1 was isolated and purified from Aibi Lake located in the north of Xinjiang Uygur Autonomous Region. Partial DNA fragment encoding a bacteriorhodopsin (Br) protein as well as 16S rRNA of AB1 was amplified by PCR, and their nucleotide sequences were determined subsequently. On the basis of homology and phylognetic analysis about 16S rRNA gene (16S rDNA), it could be speculated that the strain AB1 is a novel member of the genus Natronococcus. The hydropathy analysis of Br fragment revealed that the AB1 Br had a transmembrane heptahelical structure similar to that of other Brs. On the other hand, homology alignment using the deduced partial amino acid sequence of Br protein of AB1 with other Br proteins showed that AB1 Br protein is obviously different to others. These facts indicated that the Br in halophilic archaeum AB1 is a new Br protein.

Amino Acid Sequence↗

PubMed2004

Treatment of anthraquinone dye wastewater by hydrolytic acidification-aerobic process.

Experiment on microbial degradation with two kinds of biological process, hydrolytic acidification-aerobic process and aerobic process was conducted to treat the anthraquinone dye wastewater with COD(Cr) concentration of 400 mg/L and chroma 800. The experimental result demonstrated that the hydrolytic-aerobic process could raise the biodegradability of anthraquinone dye wastewater effectively. The effluent COD(Cr) can reach 120-170 mg/L and chroma 150 which is superior to that from simple aerobic process.

Anthraquinones↗

PubMed2003

Gadd45a contributes to p53 stabilization in response to DNA damage.

p53 is an important molecule in cellular response to DNA damage. After genotoxic stress, p53 protein stabilizes transiently and accumulates in the nucleus, where it functions as a transcription factor and upregulates multiple downstream-targeted genes, including p21(Waf1/Cip1), Gadd45a and Bax. However, regulation of p53 stabilization is complex and may mainly involve post-translational modification of p53, such as phosphorylation and acetylation. Using mouse embryonic fibroblasts (MEFs) derived from Gadd45a knockouts, we found that disruption of Gadd45a greatly abolished p53 protein stabilization following UVB treatment. Phosphorylation of p53 at Ser-15 was substantially reduced in Gadd45a-/- MEFs. In addition, p53 induction by UVB was shown to be greatly abrogated in the presence of p38 kinase inhibitor, but not c-Jun N-terminal kinase (JNK) and extracellular-signal regulated kinase (ERK), suggesting that p38 protein kinase is involved in the regulation of p53 induction. Along with the findings presented above, inducible expression of Gadd45a enhanced p53 accumulation after cell exposure to UVB. Taken together, the current study demonstrates that Gadd45a, a conventional downstream gene of p53, may play a role as an upstream effector in p53 stabilization following DNA damage, and thus has defined a positive feedback signal in the activation of the p53 pathway.

Animals↗

PubMed2003

[Suppression of HCT116 growth of cells by Gadd45].

OBJECTIVE: To study the mechanism of suppression of growth of HCT116 human colon carcinoma cells by Gadd45 gene. METHODS: HCT116 human colon carcinoma cells were transfected with pTRE-Gadd45 vector so as to establish Gadd45-inducible cell line that was cultured in medium with tetracycline. Then tetracycline was withdrawn. The number of cell clones was counted. Flow cytometry was used to detect the percentages of cells at the G1, S, and G2-M phases. TUNEL technique was used to detect the apoptosis of cells. Western blotting was used to analyze the expression of Gadd45 protein, and apoptosis-related proteins: poly-ADP-ribose polymerase (PARP), and caspase 3 protein. RESULTS: Gadd45 protein was not expressed in the HCT116 cells cultured in the medium with tetracycline, however, it was expressed with a gradually increased level in the cells cultured in the medium from which tetracycline was withdrawn, The clone formation rate of HCT116 cells was 100% in the medium with tetracycline, however, was only 14.2% in the medium with tetracycline withdrawal, with a suppression rate of more than 85%. The percentage of cells in G(2)-M phase was significantly increased in the cells cultured in the medium with tetracycline withdrawal. 24-36 hours after the withdrawal of tetracycline, PARP and caspase 3 protein were activated remarkably. CONCLUSION: High expression of Gadd45 inhibits the growth of HCT116 cells, through inducing G2-M arrest and activating apoptotic pathway.

Blotting, Western↗

PubMed2003

Acetylcholinesterase inhibitors activate septohippocampal GABAergic neurons via muscarinic but not nicotinic receptors.

Acetylcholinesterase (AChE) inhibitors, which increase synaptic levels of available acetylcholine (ACh) by preventing its degradation, are the most extensively prescribed drugs for the treatment of Alzheimer's disease. In animals, AChE inhibitors improve learning and memory, reverse scopolamine-induced amnesia, and produce hippocampal theta rhythm. The medial septum/diagonal band of Broca (MSDB), which maintains hippocampal theta rhythm and associated mnemonic functions via the septohippocampal pathway, is considered a critical locus for mediating the effects of AChE inhibitors. Using electrophysiological recordings and fluorescent labeling techniques to identify living septohippocampal neurons in rat brain slices, we report that AChE inhibitors, in the absence of exogenous ACh, produce a profound excitation in 94% of septohippocampal GABAergic neurons and an inhibition in 24% of septohippocampal cholinergic neurons. The inhibitory and excitatory effects of AChE inhibitors, presumably, occur due to accumulation of ACh that is released locally within the MSDB via axon collaterals of septohippocampal cholinergic neurons. The excitatory effects of AChE inhibitors on septohippocampal GABAergic neurons were blocked by muscarinic but not nicotinic receptor antagonists, especially by the M3 receptor antagonist, 4-diphenylacetoxy-N-methylpiperidine mustard, and not by M1 or M2/M4 muscarinic receptor antagonists. M3 muscarinic receptor mRNA colocalized with the calcium-binding protein, parvalbumin, a marker of septohippocampal GABAergic neurons. These findings may be useful in designing therapeutic strategies that do not depend on endogenous ACh and may therefore be effective in situations where AChE inhibitors cease to be effective, such as in progressive neurodegeneration.

Animals↗

PubMed2003

The deregulation of arachidonic acid metabolism-related genes in human esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is 1 of the most common cancers worldwide. In our study, cDNA microarray comprising 14,803 genes was employed to identify gene-specific expression profile in 6 paired samples of ESCC. Nine genes identified were commonly upregulated and 36 downregulated in tumors, as compared to normal esophageal squamous epithelia. Among these genes, we found that 9 of the altered expression genes were related to arachidonic acid (AA) metabolism, such as annexin-I, annexin-II, S100A8, S100A10, S100P, glutathione peroxidase-3, phosphatidylcholine transfer protein, aldo-keto reductase family 1 and cyclooxygenase-2 (COX-2). To gain insights into the regulation of the AA metabolism pathway involved in the carcinogenesis of ESCC, we investigated the expression of 8 genes related to the AA metabolism by semiquantitative reverse transcript (RT)-PCR and/or Western blot and immunohistochemistry. These genes include annexin-I, annexin-II, COX-2, cyclooxygenase-1 (COX-1) and cytosolic phospholipase A(2) (cPLA(2)), 5-lipoxygenase (5-LOX), 5-lipoxygenase activating protein (FLAP) and 12-lipoxygenase (12-LOX) (not included in the array data). The expression level of annexin-I, annexin-II was downregulated in esophageal cancer, whereas cPLA(2), FLAP, COX-2, 5-LOX and 12-LOX were upregulated. These data suggested that AA metabolism pathway and its altered expression may contribute to esophageal squamous cell carcinogenesis.

Arachidonic Acid↗

PubMed2003

Acceptor specificity and inhibition of the bacterial cell-wall glycosyltransferase MurG.

A continuous fluorescence coupled enzyme assay was developed to study the acceptor specificity of the glycosyltransferase MurG toward different lipid I analogues with various substituents replacing the undecaprenyl moiety. It was found that most lipid I analogues are accepted as substrates and, amongst these, the saturated C14 analogue exhibits the best activity. This substrate was used to evaluate the inhibition activity of such antibiotics as moenomycin, vancomycin, and two chlorobiphenyl vancomycin derivatives. A vancomycin derivative with a chlorobiphenyl moiety on the aglycon section was identified as a potent inhibitor of MurG.

Bacterial Outer Membrane Proteins↗

PubMed2003

Rapid tau aggregation and delayed hippocampal neuronal death induced by persistent thrombin signaling.

Tau hyperphosphorylation, leading to self-aggregation, is widely held to underlie the neurofibrillary degeneration found in Alzheimer's disease (AD) and other tauopathies. However, it is unclear exactly what environmental factors may trigger this pathogenetic tau hyperphosphorylation. From several perspectives, the coagulation serine protease, thrombin, has been implicated in AD and activates several different protein kinase pathways but has not previously been shown how it may contribute to AD pathogenesis. Here we report that nanomolar thrombin induced rapid tau hyperphosphorylation and aggregation in murine hippocampal neurons via protease-activated receptors, which was followed by delayed synaptophysin reduction and apoptotic neuronal death. Mechanistic study revealed that a persistent thrombin signaling via protease-activated receptor 4 and prolonged downstream p44/42 mitogenactivated protein kinase activation are at least in part responsible. These results pathogenetically linked thrombin to subpopulations of AD and other tauopathies associated with cerebrovascular damage. Such knowledge may be instrumental in transforming therapeutic paradigms.

Animals↗

PubMed2003

Persistent protease-activated receptor 4 signaling mediates thrombin-induced microglial activation.

We have previously reported that thrombin, the ultimate serine protease in the coagulation cascades, is a proinflammatory agent that causes proliferation and activation of brain microglial cells. However, participation of its principal receptor, the protease-activated receptor 1 (PAR1) appears to be limited to promoting microglial proliferation and not induction of inflammatory mediators. In the present study, we now report that thrombin action in promoting inflammatory mediators from brain microglia is mediated through another thrombin receptor, PAR4. Here we show that the PAR4 agonist peptide (PAR4AP, GYPGKF), but not the PAR1AP (TRAP, SFLLRN), induced tumor necrosis factor-alpha (TNF-alpha) production not only in cultured murine microglial cells in vitro but also in rat cortex in vivo. Down-regulation of PAR4 expression in microglial cultures by a specific antisense, but not a sense, oligonucleotide reduced PAR4AP-induced TNF-alpha. Mechanistic studies indicated that, in comparison with PAR1 signaling, prolonged increase of [Ca2+]i and phosphorylation of p44/42 mitogen-activated protein kinases, as well as NFkappaB activation may be responsible for PAR4AP-induced TNF-alpha production in microglia. Taken together, these results demonstrate that PAR4 activation mediates the potentially detrimental effects of thrombin on microglia, implying that perspectives of exploiting PAR1 as a potential anti-inflammatory target should be shifted toward PAR4 as a much more specific therapeutic target in brain inflammatory conditions associated with neurotrauma and neurodegenerations.

Animals↗

PubMed2003

SINK is a p65-interacting negative regulator of NF-kappaB-dependent transcription.

The transcription factor NF-kappaB plays important roles in inflammation and cell survival. In this study, we identified SINK, an NF-kappaB-inducible protein. Overexpression of SINK inhibited NF-kappaB-dependent transcription induced by tumor necrosis factor (TNF) stimulation or its downstream signaling proteins but did not inhibit NF-kappaB translocation to the nucleus and binding to DNA. Co-immunoprecipitation and in vitro kinase assays indicated that SINK specifically interacted with the NF-kappaB transactivator p65 and inhibited p65 phosphorylation by the catalytic subunit of protein kinase A, which has previously been shown to regulate NF-kappaB activation. Consistent with its role in inhibition of NF-kappaB-dependent transcription, SINK also sensitized cells to apoptosis induced by TNF and TRAIL (TNF-related apoptosis-inducing ligand). Taken together, these data suggest that SINK is critically involved in a novel negative feedback control pathway of NF-kappaB-induced gene expression.

Active Transport, Cell Nucleus↗

PubMed2003

Role of base sequence context in conformational equilibria and nucleotide excision repair of benzo[a]pyrene diol epoxide-adenine adducts.

We investigate the influence of base sequence context on the conformations of the 10S (+)- and 10R (-)-trans-anti-[BP]-N(6)-dA adducts through molecular dynamics (MD) simulations with free energy calculations, and relate the structural findings to results of nucleotide excision repair (NER) assays in human cell extracts. In previous studies, these adducts were studied in the CA*A sequence context, and here we report results for the CA*C sequence. Our simulations indicate that the base sequence context affects the syn-anti conformational equilibrium in the 10S (+) adduct by modulating the barrier heights between these states on the energy surface, with a higher barrier in the CA*C case. Our nucleotide excision repair assay finds greater NER susceptibilities in the 10S (+) adduct for the CA*C sequence context. A structural rationale ties together these results. A sequence specific hydrogen bond, accompanied by a significantly increased roll and consequent bending in the 10S (+) adduct, has been found in our simulations for the CA*C sequence, which could account for the enhanced nucleotide excision repair as well as the syn-anti equilibrium difference we observe in this isomer and sequence. Such sequence specific differential repair could contribute to the existence of mutational hotspots and thereby contribute to the complexity of cancer initiation.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed2003

Cloning, functional study and comparative mapping of Luzp2 to mouse chromosome 7 and human chromosome 11p13-11p14.

A novel leucine-zipper gene, leucine zipper protein 2 (Luzp2), has been cloned as part of an aberrant deletion-fusion transcript in the chromosomal interval between Gas2 and Herc2 on mouse Chromosome 7 (Chr 7). Luzp2 is normally expressed only in brain and spinal cord. The human homolog of Luzp2 maps to Chr 11p13-11p14 by radiation-hybrid mapping and is deleted in some patients with Wilms tumor-Aniridia-Genitourinary anomalies-mental Retardation (WAGR) syndrome. Disruption of Luzp2 by gene targeting in mice did not result in any obvious abnormal phenotypes.

Amino Acid Sequence↗

PubMed2003

Simulating structural and thermodynamic properties of carcinogen-damaged DNA.

A pair of stereoisomeric covalent adducts to guanine in double-stranded DNA, derived from the reaction of mutagenic and tumorigenic metabolites of benzo[a]pyrene, have been well characterized structurally and thermodynamically. Both high-resolution NMR solution structures and an array of thermodynamic data are available for these 10S (+)- and 10R (-)-trans-anti -[BP]-N(2)-dG adducts in double-stranded deoxyoligonucleotides. The availability of experimentally well-characterized duplexes containing these two stereoisomeric guanine adducts provides an opportunity for evaluating the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method for computing thermodynamic properties from molecular dynamics ensembles. We have carried out 3-ns molecular dynamics simulations, using NMR solution structures as the starting models for the 10S (+)- and 10R (-)-trans-anti-dG adducts in a DNA duplex 11-mer using AMBER 6.0. We employed the MM-PBSA method to compute the free energies, enthalpies, and entropies of the two adducts. Our complete thermodynamic analysis agrees quite well with the full experimental thermodynamic characterization of these adducts, showing essentially equal stabilities of the two adducts. We also calculated the nuclear Overhauser effect (NOE) distances from the molecular dynamics trajectories, and compared them against the experimental NMR-derived NOE distances. Our results showed that the simulated structures are in good agreement with the NMR experimental NOE data. Furthermore, the molecular dynamics simulations provided new structural and biological insights. Specifically, the puzzling observation that the BP aromatic ring system in the 10S (+)-trans-anti-dG adduct is more exposed to the aqueous solvent than the 10R (-)-trans-anti-dG adduct, is rationalized in terms of the adduct structures. The structural and thermodynamic features of these stereoisomeric adducts are also discussed in relation to their reported low susceptibilities to nucleotide excision repair.

Base Sequence↗

PubMed2003

Enhancement of germ cell apoptosis induced by ethanol in transgenic mice overexpressing Fas Ligand.

It was suggested that chronic ethanol exposure could result in testicular germ cell apoptosis, but the mechanism is still unclear. In the present study, we use a model of transgenic mice ubiquitously overexpressing human FasL to investigate whether Fas ligand plays a role in ethanol-induced testicular germ cell apoptosis. Both wild-type (WT) mice and transgenic (TG) mice were treated with acute ethanol (20% v/v) by introperitoneal injection for five times. After ethanol injection, WT mice displayed up-regulation of Fas ligand in the testes, which was shown by FITC-conjugated flow cytometry and western blotting. Moreover, TG mice exhibited significantly more apoptotic germ cells than WT mice did after ethanol injection, which was demonstrated by DNA fragmentation, PI staining flow cytometry and TUNEL staining. In addition, histopathological examination revealed that degenerative changes of epithelial component of the tubules occurred in FasL overexpressing transgenic mice while testicular morphology was normal in wild-type mice after acute ethanol exposure, suggesting FasL expression determines the sensitivity of testes to ethanol in mice. In summary, we provide the direct evidences that Fas ligand mediates the apoptosis of testicular germ cells induced by acute ethanol using FasL transgenic mice.

Animals↗

PubMed2003

Nicotine recruits a local glutamatergic circuit to excite septohippocampal GABAergic neurons.

Tonic impulse flow in the septohippocampal GABAergic pathway is essential for normal cognitive functioning and is sustained, in part, by acetylcholine (ACh) that is released locally via axon collaterals of septohippocampal cholinergic neurons. Septohippocampal cholinergic neurons degenerate in Alzheimer's disease and other neurodegenerative disorders. While the importance of the muscarinic effects of ACh on septohippocampal GABAergic neurons is well recognized, the nicotinic effects of ACh remain unstudied despite the reported benefits of nicotine on cognitive functioning. In the present study, using electrophysiological recordings in a rat brain slice preparation, rapid applications of nicotine excited 90% of retrogradely labelled septohippocampal GABA-type neurons with an EC50 of 17 microm and increased the frequency of spontaneously occurring, impulse-dependent fast GABAergic and glutamatergic synaptic currents via the alpha4beta2-nicotinic receptor. Interestingly, tetrodotoxin blocked all effects of nicotine on septohippocampal GABAergic type neurons, suggesting involvement of indirect mechanisms. We demonstrate that the effects of nicotine on septohippocampal GABA-type neurons involve recruitment of a novel, local glutamatergic circuitry as (i). Group I metabotropic glutamatergic receptor antagonists reduced the effects of nicotine; (ii). the number of nicotine responsive neurons was significantly reduced in recordings from slices that had been trimmed so as to reduce the number of glutamate-containing neurons within the slice preparation; (iii). in light and ultrastructural double immunocytochemical labelling studies vesicular glutamate 2 transporter immunoreactive terminals made synaptic contacts with parvalbumin-immunoreactive septohippocampal GABAergic neurons. The discovery of a local glutamatergic circuit within the septum may provide another avenue for restoring septohippocampal GABAergic functions in neurodegenerative disorders associated with a loss of septohippocampal cholinergic neurons.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2003

Case report of the first Severe Acute Respiratory Syndrome patient in China: successful application of extracorporeal liver support MARS therapy in multiorgan failure possibly induced by Severe Acute Respiratory Syndrome.

A previously healthy patient was transferred to our infectious department with a 9-day-history of continued fever. The patient was placed on assisted respiration support in addition to anti-viral medication. The diagnosis of SARS (Severe Acute Respiratory Syndrome) was made in view of the severe hypoxemia and the characteristic symptoms exhibited by the patient. Despite the best intensive therapy, he clinically deteriorated into multiorgan dysfunction syndrome (MODS) including additional dysfunction of kidney, liver, and heart. We initiated MARS therapy (extracorporeal liver support utilizing albumin dialysis) with intention to positively influence the organ functions in his MODS on the basis of recently published studies which suggested a positive impact of MARS in multiorgan failure secondary to respiratory illnesses and the possible influence on inflammatory mediators and cytokines. The application of 4 intermittent MARS treatments (8 h each, mean blood flow rate 180 ml/min) on 4 consecutive days resulted in an immediate improvement of clinical conditions within the treatment days. The further improvement of organ functions allowed withdrawing the patient from ventilatory support 13 days after start of MARS, and 44 days after admission he was discharged home with completely resolved organ functions and laboratory abnormalities. SARS is a severe form of the epidemic outbreak of atypical pneumonia which remains poorly defined regarding etiology and special therapy recommendations. However, the development and aggravation of this ARDS-like severe acute respiratory syndrome is pathologically associated with the systemic inflammatory response syndrome (SIRS) which may then mediate or cause MODS. To our knowledge, this is the first report of an application of MARS therapy in MODS which was probably induced by SARS in a patient in China which improved the clinical condition of the patient in multi-organ failure secondary to respiratory failure indicating that MARS might be an additional therapeutic option in multiorgan failure induced by SARS.

China↗

PubMed2003

Gene expression profiles at different stages of human esophageal squamous cell carcinoma.

AIM: To characterize the gene expression profiles in different stages of carcinogenesis of esophageal epithelium. METHODS: A microarray containing 588 cancer related genes was employed to study the gene expression profile at different stages of esophageal squamous cell carcinoma including basal cell hyperplasia, high-grade dysplasia, carcinoma in situ, early and late cancer. Principle component analysis was performed to search the genes which were important in carcinogenesis. RESULTS: More than 100 genes were up or down regulated in esophageal epithelial cells during the stages of basal cell hyperplasia, high-grade dysplasia, carcinoma in situ, early and late cancer. Principle component analysis identified a set of genes which may play important roles in the tumor development. Comparison of expression profiles between these stages showed that some genes, such as P160ROCK, JNK2, were activated and may play an important role in early stages of carcinogenesis. CONCLUSION: These findings provided an esophageal cancer-specific and stage-specific expression profiles, showing that complex alterations of gene expression underlie the development of malignant phenotype of esophageal cancer cells.

Carcinoma, Squamous Cell↗

PubMed2003

Overexpression of ETS2 in human esophageal squamous cell carcinoma.

AIM: To study the expression pattern of ETS2 (erythroblastosis virus oncogene homolog 2) in human esophageal squamous cell carcinoma (ESCC). METHODS: Reverse transcription polymerase chain reaction (RT-PCR) and Northern blot were performed to examine the expression level of ETS2 mRNA in 37 pairs of ESCC tissue samples. Western blot and immunohistochemistry were carried out to check the expression level of ETS2 protein in 30 pairs of ESCC tissue specimens. RESULTS: RT-PCR and Northern blot analysis showed that ETS2 mRNA upregulated in 75.7 % (28/37) examined ESCC tissues relative to matched normal tissues. From those 37 cases, 14 cases were randomly selected to perform Western blot and the results revealed that ETS2 protein overexpressed in 71.4 % (10/14) checked ESCC tissues compared with the corresponding normal tissues. Moreover, the expression patterns of ETS2 protein in those 14 cases were identical to those of ETS2 mRNA displayed by RT-PCR or Northern Blot. Immunohistochemistry analysis showed that the expression level of ETS2 protein rose in 75 % (12/16) tumor epithelial cells contrasted to the normal cells. Altogether the expression level of ETS2 protein increased in 73.3 % (22/30) checked ESCC tissue samples contrary to their normal counterparts. CONCLUSION: The results suggested that ETS2 overexpressed in paired human ESCC tissue samples at both mRNA and protein levels and may be associated with the tumorigenesis of esophagus.

Blotting, Northern↗