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1.
Int J Hematol ; 2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38814500

RESUMO

G protein pathway suppressor 2 (GPS2) has been shown to play a pivotal role in human and mouse definitive erythropoiesis in an EKLF-dependent manner. However, whether GPS2 affects human primitive erythropoiesis is still unknown. This study demonstrated that GPS2 positively regulates erythroid differentiation in K562 cells, which have a primitive erythroid phenotype. Overexpression of GPS2 promoted hemin-induced hemoglobin synthesis in K562 cells as assessed by the increased percentage of benzidine-positive cells and the deeper red coloration of the cell pellets. In contrast, knockdown of GPS2 inhibited hemin-induced erythroid differentiation of K562 cells. GPS2 overexpression also enhanced erythroid differentiation of K562 cells induced by cytosine arabinoside (Ara-C). GPS2 induced hemoglobin synthesis by increasing the expression of globin and ALAS2 genes, either under steady state or upon hemin treatment. Promotion of erythroid differentiation of K562 cells by GPS2 mainly relies on NCOR1, as knockdown of NCOR1 or lack of the NCOR1-binding domain of GPS2 potently diminished the promotive effect. Thus, our study revealed a previously unknown role of GPS2 in regulating human primitive erythropoiesis in K562 cells.

2.
Cell Death Dis ; 14(11): 743, 2023 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-37968261

RESUMO

BRISC (BRCC3 isopeptidase complex) is a deubiquitinating enzyme that has been linked with inflammatory processes, but its role in liver diseases and the underlying mechanism are unknown. Here, we investigated the pathophysiological role of BRISC in acute liver failure using a mice model induced by D-galactosamine (D-GalN) plus lipopolysaccharide (LPS). We found that the expression of BRISC components was dramatically increased in kupffer cells (KCs) upon LPS treatment in vitro or by the injection of LPS in D-GalN-sensitized mice. D-GalN plus LPS-induced liver damage and mortality in global BRISC-null mice were markedly attenuated, which was accompanied by impaired hepatocyte death and hepatic inflammation response. Constantly, treatment with thiolutin, a potent BRISC inhibitor, remarkably alleviated D-GalN/LPS-induced liver injury in mice. By using bone marrow-reconstituted chimeric mice and cell-specific BRISC-deficient mice, we demonstrated that KCs are the key effector cells responsible for protection against D-GalN/LPS-induced liver injury in BRISC-deficient mice. Mechanistically, we found that hepatic and circulating levels of TNF-α, IL-6, MCP-1, and IL-1ß, as well as TNF-α- and MCP-1-producing KCs, in BRISC-deleted mice were dramatically decreased as early as 1 h after D-GalN/LPS challenge, which occurred prior to the elevation of the liver injury markers. Moreover, LPS-induced proinflammatory cytokines production in KCs was significantly diminished by BRISC deficiency in vitro, which was accompanied by potently attenuated NF-κB activation. Restoration of NF-κB activation by two small molecular activators of NF-κB p65 effectively reversed the suppression of cytokines production in ABRO1-deficient KCs by LPS. In conclusion, BRISC is required for optimal activation of NF-κB-mediated proinflammatory cytokines production in LPS-treated KCs and contributes to acute liver injury. This study opens the possibility to develop new strategies for the inhibition of KCs-driven inflammation in liver diseases.


Assuntos
Doença Hepática Crônica Induzida por Substâncias e Drogas , Doença Hepática Induzida por Substâncias e Drogas , Animais , Camundongos , NF-kappa B/metabolismo , Lipopolissacarídeos/farmacologia , Células de Kupffer/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Fígado/metabolismo , Inflamação/metabolismo , Galactosamina , Doença Hepática Induzida por Substâncias e Drogas/genética , Doença Hepática Induzida por Substâncias e Drogas/metabolismo
3.
Adv Sci (Weinh) ; 9(5): e2103838, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34923767

RESUMO

Hematopoietic stem and progenitor cells (HSPCs) possess the remarkable ability to regenerate the whole blood system in response to ablated stress demands. Delineating the mechanisms that maintain HSPCs during regenerative stresses is increasingly important. Here, it is shown that Hemgn is significantly induced by hematopoietic stresses including irradiation and bone marrow transplantation (BMT). Hemgn deficiency does not disturb steady-state hematopoiesis in young mice. Hemgn-/- HSPCs display defective engraftment activity during BMT with reduced homing and survival and increased apoptosis. Transcriptome profiling analysis reveals that upregulated genes in transplanted Hemgn-/- HSPCs are enriched for gene sets related to interferon gamma (IFN-γ) signaling. Hemgn-/- HSPCs show enhanced responses to IFN-γ treatment and increased aging over time. Blocking IFN-γ signaling in irradiated recipients either pharmacologically or genetically rescues Hemgn-/- HSPCs engraftment defect. Mechanistical studies reveal that Hemgn deficiency sustain nuclear Stat1 tyrosine phosphorylation via suppressing T-cell protein tyrosine phosphatase TC45 activity. Spermidine, a selective activator of TC45, rescues exacerbated phenotype of HSPCs in IFN-γ-treated Hemgn-/- mice. Collectively, these results identify that Hemgn is a critical regulator for successful engraftment and reconstitution of HSPCs in mice through negatively regulating IFN-γ signaling. Targeted Hemgn may be used to improve conditioning regimens and engraftment during HSPCs transplantation.


Assuntos
Transplante de Células-Tronco Hematopoéticas , Interferon gama , Animais , Hematopoese , Transplante de Células-Tronco Hematopoéticas/métodos , Células-Tronco Hematopoéticas/metabolismo , Interferon gama/metabolismo , Camundongos , Condicionamento Pré-Transplante
4.
Front Pharmacol ; 12: 711126, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34447310

RESUMO

The compound [3-(1H-benzimidazol-2-methylene)-5-(2-methylphenylaminosulfo)-2-indolone], known as Indo5, is a novel selective inhibitor of c-Met and Trks, and it is a promising anticancer candidate against hepatocellular carcinoma (HCC). Assessing the pharmacokinetic properties, tissue distribution, and toxicity of Indo5 is critical for its medicinal evaluation. A series of sensitive and specific liquid chromatography-tandem mass spectrometry methods were developed and validated to determine the concentration of Indo5 in rat plasma and tissue homogenates. These methods were then applied to investigate the pharmacokinetics and tissue distribution of Indo5 in rats. After intravenous injection of Indo5, the maximum concentration (Cmax) and the time at which Cmax was reached (Tmax) were 1,565.3 ± 286.2 ng/ml and 1 min, respectively. After oral administration, Cmax and Tmax were 54.7 ± 10.4 ng/ml and 2.0 ± 0.48 h, respectively. We calculated the absolute oral bioavailability of Indo5 in rats to be 1.59%. Following intravenous injection, the concentrations of Indo5 in various tissues showed the following order: liver > kidney ≈ heart > lung ≈ large intestine ≈ small intestine ≈ stomach > spleen > brain ≈ testes; hence, Indo5 distributed highest in the liver and could not cross the blood-brain or blood-testes barriers. Continuous injection of Indo5 for 21 days did not lead to liver injury, considering unchanged ALT and AST levels, normal histological architecture of the liver, and normal number and frequencies of immune cells in the liver, indicating a very low toxicity of Indo5 in vivo. Collectively, our findings provide a comprehensive understanding of the biological actions of Indo5 in vivo and further support its development as an antitumor treatment for HCC patients.

5.
FASEB J ; 34(6): 8416-8427, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32350948

RESUMO

During human erythroid maturation, Hsp70 translocates into the nucleus and protects GATA-1 from caspase-3 cleavage. Failure of Hsp70 to localize to the nucleus was found in Myelodysplastic syndrome (MDS) erythroblasts and can induce dyserythropoiesis, with arrest of maturation and death of erythroblasts. However, the mechanism of the nuclear trafficking of Hsp70 in erythroblasts remains unknown. Here, we found the hematopoietic transcriptional regulator, EDAG, to be a novel binding partner of Hsp70 that forms a protein complex with Hsp70 and GATA-1 during human normal erythroid differentiation. EDAG overexpression blocked the cytoplasmic translocation of Hsp70 induced by EPO deprivation, inhibited GATA-1 degradation, thereby promoting erythroid maturation in an Hsp70-dependent manner. Furthermore, in myelodysplastic syndrome (MDS) patients with dyserythropoiesis, EDAG is dramatically down-regulated, and forced expression of EDAG has been found to restore the localization of Hsp70 in the nucleus and elevate the protein level of GATA-1 to a significant extent. In addition, EDAG rescued the dyserythropoiesis of MDS patients by increasing erythroid differentiation and decreasing cell apoptosis. This study demonstrates the molecular mechanism of Hsp70 nuclear sustaining during erythroid maturation and establishes that EDAG might be a suitable therapeutic target for dyserythropoiesis in MDS patients.


Assuntos
Núcleo Celular/metabolismo , Eritroblastos/metabolismo , Eritropoese/fisiologia , Proteínas de Choque Térmico HSP70/metabolismo , Síndromes Mielodisplásicas/metabolismo , Proteínas Nucleares/metabolismo , Apoptose/fisiologia , Caspase 3/metabolismo , Diferenciação Celular/fisiologia , Células Cultivadas , Citoplasma/metabolismo , Regulação da Expressão Gênica/fisiologia , Doenças Hematológicas/metabolismo , Humanos
6.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 27(3): 958-963, 2019 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-31204961

RESUMO

OBJECTIVE: To investigate the effects of Listeria monocytogenes infection on hematopoietic stem and progenitor cell (HSPC) composition, cell cycle and cell colony-forming ability in mouse bone marrow. METHODS: The C57BL/6J mice were divided into infected group and control group. The mice in injected group were infected intraperitoneally with 6.7×106 CFU Listeria monocytogenes,while the mice in control group were injecfed with PBS of same volume.The serum levels of IFNγ were detected at different time points. After 24 hours, the HS/PC composition, cell cycle and cell colony-forming ability in bone marrow of mice were measured, and the difference between the control group and the infected group was statistically analyzed. RESULTS: Serum IFNγ levels peaked at 24 hours after infection with Listeria monocytogenes. After 24 h, the proportion of LSK, LSK in S phase, and short-term hematopoietic stem cells (ST-HSC) in the infected group were significantly higher than those in the control group (P<0.001), long-term hematopoietic stem cells (LT-HSC) and the proportion of LT-HSC in S phase were significantly increased (P<0.01), and the cell colony-forming ability of bone marrow significantly decreased (P<0.01). [WTHZ]Conclusion: [WTB1]After infection with Listeria monocytogenes, bone marrow hematopoietic stem cells enter the proliferative state from rest, the cell colony-forming ability decreases, suggesting that Listeria monocytogenes infection can cause hematopoietic stem cell depletion.


Assuntos
Transplante de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas , Animais , Medula Óssea , Células da Medula Óssea , Diferenciação Celular , Proliferação de Células , Camundongos , Camundongos Endogâmicos C57BL
7.
J Exp Clin Cancer Res ; 38(1): 130, 2019 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-30885237

RESUMO

BACKGROUND: Human hepatocellular carcinoma (HCC) lacks effective curative therapy and there is an urgent need to develop a novel molecular-targeted therapy for HCC. Selective tyrosine kinase inhibitors have shown promise in treating cancers including HCC. Tyrosine kinases c-Met and Trks are potential therapeutic targets of HCC and strategies to interrupt c-Met and Trks cross-signaling may result in increased effects on HCC inhibition. METHODS: The effects of Indo5 on c-Met and Trks activity were determined with in vitro kinase activity assay, cell-based signaling pathway activation, and kinases-driven cell transformation. The in vivo anti-tumor activity was determined with xenograft mice and liver orthotopic mice models. The co-expression of c-Met and TrkB in 180 pairs of HCC and adjacent normal tissues were detected using immunohistochemical staining. RESULTS: Indo5, a novel lead compound displayed biochemical potency against both c-Met and Trks with selectivity over 13 human kinases. Indo5 abrogated HGF-induced c-Met signaling activation and BDNF/NGF-induced Trks signal activation, c-Met or TrkB-mediated cell transformation and migration. Furthermore, Indo5 significantly decreased the growth of HCC cells in xenograft mice and improved the survival of mice with liver orthotopic tumors. In addition, co-expression of c-Met and TrkB in HCC patients was a predictor of poor prognosis, and combined inhibition of c-Met and TrkB exerted a synergistic suppressive effect on HCC. CONCLUSIONS: These findings indicate that Indo5 is associated with marked suppression of c-Met and Trks co-expressing HCC, supporting its clinical development as an antitumor treatment for HCC patients with co-active c-Met and Trks signaling.


Assuntos
Antineoplásicos/uso terapêutico , Carcinoma Hepatocelular/tratamento farmacológico , Neoplasias Hepáticas/tratamento farmacológico , Proteínas Proto-Oncogênicas c-met/genética , Pirazóis/uso terapêutico , Pirimidinas/uso terapêutico , Animais , Antineoplásicos/farmacologia , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Modelos Animais de Doenças , Feminino , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Camundongos , Camundongos Endogâmicos BALB C , Proteínas Proto-Oncogênicas c-met/metabolismo , Pirazóis/farmacologia , Pirimidinas/farmacologia , Ensaios Antitumorais Modelo de Xenoenxerto
8.
J Org Chem ; 82(24): 13084-13092, 2017 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-29096055

RESUMO

Pyridinium aldoximes, which are best-known as therapeutic antidotes for organophosphorus chemical warfare nerve-agents and pesticides, have been found to markedly detoxify polyhalogenated quinones, which are a class of carcinogenic intermediates and recently identified disinfection byproducts in drinking water. However, the exact chemical mechanism underlying this detoxication remains unclear. Here we demonstrate that pralidoxime can remarkably facilitate the dechlorination/hydroxylation of the highly toxic tetrachloro-1,4-benzoquinone in two-consecutive steps to generate the much less toxic 2,5-dichloro-3,6-dihydroxy-1,4-benzoquonine, with rate enhancements of up to 180 000-times. On the contrary, no accelerating effect was noticed with O-methylated pralidoxime. The major reaction product from pralidoxime was identified as its corresponding nitrile (2-cyano-1-methylpyridinium chloride). Along with oxygen-18 isotope-labeling studies, a reaction mechanism was proposed in which nucleophilic substitution coupled with an unprecedented double Beckmann fragmentation reaction was responsible for the dramatic enhancement in the detoxification process. This represents the first report of an unusually mild and facile Beckmann-type fragmentation that can occur under normal physiological conditions in two-consecutive steps. The study may have broad biomedical and environmental significance for future investigations of aldoxime therapeutic agents and carcinogenic polyhalogenated quinones.


Assuntos
Desintoxicação Metabólica Fase I , Compostos de Pralidoxima/química , Estrutura Molecular
9.
Free Radic Biol Med ; 104: 54-63, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28062359

RESUMO

2,6-Dibromohydroquinone (2,6-DBrHQ) has been identified as an reactive metabolite of many brominated phenolic environmental pollutants such as tetrabromobisphenol-A (TBBPA), bromoxynil and 2,4,6-tribromophenol, and was also found as one of disinfection byproducts in drinking water. In this study, we found that the combination of 2,6-DBrHQ and Cu(II) together could induce synergistic DNA damage as measured by double strand breakage in plasmid DNA and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation, while either of them alone has no effect. 2,6-DBrHQ/Cu(II)-induced DNA damage could be inhibited by the Cu(I)-specific chelating agent bathocuproine disulfonate and catalase, but not by superoxide dismutase, nor by the typical hydroxyl radical (•OH) scavengers such as DMSO and mannitol. Interestingly, we found that Cu(II)/Cu(I) could be combined with DNA to form DNA-Cu(II)/Cu(I) complex by complementary application of low temperature direct ESR, circular dichroism, cyclic voltammetry and oxygen consumption methods; and the highly reactive •OH were produced synergistically by DNA-bound-Cu(I) with H2O2 produced by the redox reactions between 2,6-DBrHQ and Cu(II), which then immediately attack DNA in a site-specific manner as demonstrated by both fluorescent method and by ESR spin-trapping studies. Further DNA sequencing investigations provided more direct evidence that 2,6-DBrHQ/Cu(II) caused preferential cleavage at guanine, thymine and cytosine residues. Based on these data, we proposed that the synergistic DNA damage induced by 2,6-DBrHQ/Cu(II) might be due to the synergistic and site-specific production of •OH near the binding site of copper and DNA. Our findings may have broad biological and environmental implications for future research on the carcinogenic polyhalogenated phenolic compounds.


Assuntos
Cobre/toxicidade , Dano ao DNA/efeitos dos fármacos , Água Potável , Poluentes Ambientais/toxicidade , 8-Hidroxi-2'-Desoxiguanosina , Quelantes/farmacologia , Quebras de DNA de Cadeia Dupla/efeitos dos fármacos , Desoxiguanosina/análogos & derivados , Desoxiguanosina/química , Desoxiguanosina/metabolismo , Poluentes Ambientais/metabolismo , Humanos , Hidroquinonas/metabolismo , Hidroquinonas/toxicidade , Radical Hidroxila/metabolismo , Radical Hidroxila/toxicidade , Nitrilas/metabolismo , Nitrilas/toxicidade , Oxirredução , Fenantrolinas/farmacologia , Fenóis/metabolismo , Fenóis/toxicidade , Bifenil Polibromatos/metabolismo , Bifenil Polibromatos/toxicidade , Espécies Reativas de Oxigênio , Superóxido Dismutase/química
10.
Environ Sci Technol ; 49(13): 7940-7, 2015 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-26009932

RESUMO

The ubiquitous distribution coupled with their carcinogenicity has raised public concerns on the potential risks to both human health and the ecosystem posed by the halogenated aromatic compounds (XAr). Recently, advanced oxidation processes (AOPs) have been increasingly favored as an "environmentally-green" technology for the remediation of such recalcitrant and highly toxic XAr. Here, we show that AOPs-mediated degradation of the priority pollutant pentachlorophenol and all other XAr produces an intrinsic chemiluminescence that directly depends on the generation of the extremely reactive hydroxyl radicals. We propose that the hydroxyl radical-dependent formation of quinoid intermediates and electronically excited carbonyl species is responsible for this unusual chemiluminescence production. A rapid, sensitive, simple, and effective chemiluminescence method was developed to quantify trace amounts of XAr and monitor their real-time degradation kinetics. These findings may have broad biological and environmental implications for future research on this important class of halogenated persistent organic pollutants.


Assuntos
Carcinógenos/química , Hidrocarbonetos Aromáticos/análise , Hidrocarbonetos Halogenados/análise , Luminescência , Ácido Edético/química , Meio Ambiente , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Ferro/química , Cinética , Oxirredução , Ozônio/química , Pentaclorofenol/química
11.
J Pathol ; 230(4): 365-76, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23839903

RESUMO

The hepatic growth factor hepatopoietin Cn (HPPCn) prevents liver injury induced by carbon tetrachloride in rats. Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid produced by sphingosine kinase (SphK). S1P and S1P receptors (S1PRs) are involved in liver fibrogenesis and oxidative injury. This work sought to understand the mechanism by which SphK/S1P/S1PRs are involved in the protective effects of HPPCn on ethanol-induced liver injury and fibrosis. Transgenic mice with liver-specific overexpression of HPPCn (HPPCn(liver) (+/+)) were generated. Two ethanol feeding protocols were used to assess the protective effect of HPPCn on acute and chronic liver injury in mice. Specific inhibitors of S1PR1, S1PR2 and S1PR3 and siRNA were used to examine the roles of S1PRs in hepatic stellate cell (HSC) activation and hepatocyte apoptosis. Increased HPPCn expression in transgenic mice attenuated fibrosis induced by ethanol and carbon tetrachloride (CCl4). Treatment with recombinant human HPPCn prevented human hepatocyte apoptosis and HSC activation. JTE-013 or S1PR2-siRNA attenuated the effect of HPPCn on HSC activation induced by tumour necrosis factor-α (TNF-α). Consistent with the effect of N,N-dimethylsphingosine (DMS), suramin or S1PR3-siRNA treatment blocked HPPCn-induced Erk1/2 phosphorylation in human hepatocytes. This study demonstrated that HPPCn attenuated oxidative injury and fibrosis induced by ethanol feeding and that the SphK1/S1P/S1PRs signalling pathway contributes to the protective effect of HPPCn on hepatocyte apoptosis and HSC activation.


Assuntos
Etanol , Fator de Crescimento de Hepatócito/metabolismo , Cirrose Hepática Alcoólica/prevenção & controle , Fígado/enzimologia , Proteínas Nucleares/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Receptores de Lisoesfingolipídeo/metabolismo , Animais , Apoptose , Células Cultivadas , Modelos Animais de Doenças , Regulação da Expressão Gênica , Células Estreladas do Fígado/enzimologia , Células Estreladas do Fígado/patologia , Fator de Crescimento de Hepatócito/genética , Humanos , Fígado/efeitos dos fármacos , Fígado/patologia , Cirrose Hepática Alcoólica/enzimologia , Cirrose Hepática Alcoólica/etiologia , Cirrose Hepática Alcoólica/genética , Cirrose Hepática Alcoólica/patologia , Lisofosfolipídeos/metabolismo , Camundongos , Camundongos Transgênicos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Proteínas Nucleares/genética , Estresse Oxidativo , Fosforilação , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Interferência de RNA , RNA Mensageiro/metabolismo , Receptores de Lisoesfingolipídeo/antagonistas & inibidores , Receptores de Lisoesfingolipídeo/genética , Transdução de Sinais , Esfingosina/análogos & derivados , Esfingosina/metabolismo , Fatores de Tempo , Transfecção , Fator de Necrose Tumoral alfa/metabolismo
12.
World J Gastroenterol ; 11(29): 4457-60, 2005 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-16052671

RESUMO

AIM: To investigate the effect and significance of selenium in early experimental gastric carcinogenesis. METHODS: Weaning male Wistar rats were divided randomly into normal control group, experiment control group, low selenium (2 mg/L) group and high selenium (4 mg/L) group. Wistar rat gastric carcinogenesis was induced by N-methyl-N-nitro-N-nitroso guanidine (MNNG) (20 mg/kg) gavage daily for 10 d. Na2SeO3 was given by piped drinking 1 wk prior to MNNG gavage. The rats were killed at the 43rd wk. The surface characteristics of gastric mucosa were observed with naked eyes. Histopathologic changes of rat gastric mucosa were observed by HE staining and AB-PAS methods. The changes of cellular ultrastructure were observed under transmission electron microscope. Statistical analysis was carried out by SPSS. RESULTS: The incidence rate of gastric mucosa erosion, hemorrhage and intestinal metaplasia was 0, 45.5%, 66.7%, and 92.9%, respectively (92.9% vs 45.5%, P < 0.05) in the normal control group, experiment control group, low selenium group, and high selenium group. Leiomyoma formed in the process of inducement of rat gastric carcinoma. Dietary Na2SeO3 (2 and 4 mg/L) slightly increased the incidence rate of leiomyoma (0, 23%, 46.6%, and 46.6%). gastric mucosa did not change in the course of rat gastric carcinogenesis. Dietary Na2SeO3 by pipe drinking could expand the intracellular secretory canaliculus of parietal cells and increase the number of endocrine cells and lysosomes. CONCLUSION: Dietary Na2SeO3 by pipe drinking aggravates gastric erosion, hemorrhage and promotes intestinal metaplasia of gastric mucosa. The mechanism may be related with the function of parietal cells.


Assuntos
Lesões Pré-Cancerosas/patologia , Lesões Pré-Cancerosas/prevenção & controle , Selênio/farmacologia , Neoplasias Gástricas/patologia , Neoplasias Gástricas/prevenção & controle , Animais , Eosinófilos/patologia , Eosinófilos/ultraestrutura , Mucosa Gástrica/patologia , Mucosa Gástrica/ultraestrutura , Incidência , Masculino , Microscopia Eletrônica , Células Parietais Gástricas/patologia , Células Parietais Gástricas/ultraestrutura , Lesões Pré-Cancerosas/epidemiologia , Ratos , Ratos Wistar , Neoplasias Gástricas/epidemiologia
13.
Wei Sheng Wu Xue Bao ; 45(6): 821-7, 2005 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-16496684

RESUMO

Some soil samples were collected from different places in Yunnan Provinces, China. 876 bacteria or actinomycete strains were isolated using Glucose-Peptone-Yeast extract agar, Starch-Casein agar and Glycerol-Asparagine agar with these soil samples, of which about 100 strains belong to genus Streptomyces and the others belong to rare actinomycetes or bacteria. With polyketide synthesis gene screening, 75 strains were picked up as type I & II polyketide synthesis gene positive strains. Then 10 strains were chosen for 16S rDNA amplification and systematic analysis based on comparing results with their anti-bacteria activity, morphology, and physiological characteristics analysis. They were classified to be at least 7 families and 8 genera, such as genus Streptomyces of the family Streptomycetaceae, two genera Streptosporangium and Nonomuraea of the family Streptosporangiaceae, genus Mycobacterium of the family Mycobacteriaceae, genus Nocardia of the family Nocardiaceae, genus Achromobacter of the family, another two strains belong to the suborder Micrococcineae and the family Oxalobacteraceae', respectively. Eight of them were classified into six potential novel species and two new genera with polyphasic taxonomic methods. The results showed that designing new strategies for isolation and identification of microorganisms from natural environments was the key step to exploit microbial resources.


Assuntos
Actinobacteria/genética , Policetídeo Sintases/genética , Microbiologia do Solo , Actinobacteria/classificação , Actinobacteria/metabolismo , Biodiversidade , Filogenia
14.
Sheng Wu Gong Cheng Xue Bao ; 19(4): 407-11, 2003 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-15969055

RESUMO

Streptomyces hygroscopicus 17997 produces the antiviral and antitumor ansamycin antibiotic, geldanamycin. Studies on geldanamycin biosynthetic pathway will provide good tools for genetic manipulation of the antibiotic-producing strain to improve the productivity or to facilitate making novel geldanamycin analogs. The structural similarities between geldanamycin and ansamycins such as rifamycin or ansatrienin suggest that both geldanamycin and ansamycins has a closely related pathways of biosynthesis and that biosynthetic system for geldanamycin is similar to the one of type I polyketide synthase (PKS) enzyme system. To explore the possible PKS genes involved in geldanamycin biosynthesis, the degenerate primers were designed according to the conserved sequence of KS-AT region from erythromycin and oleandomycin type I PKS genes. Cosmids containing multiple PKS genes (pCGBK2,4,6,10,11,18) were obtained by hybridization with the PCR products, which were amplified from S. hygroscopisus 17997 genomic DNA. The designed primers above were used for PCR. Development of a Streptomyces temperate phage phiC31-derivative KC515( tsrR) transduction system was carried out for identification of cosmids containing the PKS gene related to biosynthesis of geldanamycin. Several factors, mainly the Ca2+ and Mg + concentrations in different culture media affecting the frequency of gene transfection, were optimized .Transfection efficiency could reach up to 10(3) /microg DNA on YMG medium supplemented with 10mmol/L MgSO4. Reversely, the transfection efficiency decreased when YMG medium was supplemented with 30mmol/L MgSO4. Gene transfection system based on the integration-defective phage KC515 had been established for S. hygroscopicus17997. Recombinant phages (ph111, 258, 287, 116, 105) were constructed by insertion of the homologous to PKS gene fragments into the KC515 phage vector. Gene disruption experiments were performed by transduction of recombinant phages into S. hygroscopicus 17997 genome, and disruption of geldanamycin production was observed as a result of homologous recombination between the cloned insert in recombinant phage and the S. hygroscopicus 17997 genome by integration. Thiostrepton resistant transductants were selected and integration event was analyzed by Southern hybridization. The fermentation broth extracts from five resistant transductants were analyzed by TLC and HPLC. The results showed that only G16 mutant failed to produce geldanamycin. This result showed that the integration of the insert DNA fragment in recombinant phage phl6 into the chromosome of S. hygroscopicus disrupted the expression of the geldanamycin biosynthetic genes. The original cosmid pCGBK10 containing this cloned insert was predicted to encode PKS genes in the geldanamycin biosynthesis. This study laid the foundation for cloning the PKS genes involved in geldanamycin biosynthetic gene cluster from S. hygroscopicus 17997.


Assuntos
Proteínas de Bactérias/metabolismo , Benzoquinonas/metabolismo , Lactamas Macrocíclicas/metabolismo , Streptomyces/metabolismo , Oxirredutases do Álcool/genética , Oxirredutases do Álcool/metabolismo , Proteínas de Bactérias/genética , Bacteriófagos/genética , Southern Blotting , Cromatografia Líquida de Alta Pressão , Cromatografia em Camada Fina , Vetores Genéticos/genética , Família Multigênica/genética , Família Multigênica/fisiologia , Reação em Cadeia da Polimerase , Streptomyces/genética
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