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Maintaining cholesterol homeostasis: Sterol regulatory element-binding proteins

World Journal of Gastroenterology 2004年第21期10卷 3081-3087页

作者： LutzW.Weber MeinradBoll AndreasStampfl 554MarinerPointDrive ClintonTN37716USA InstituteforToxicology GSF-NationalResearchCenterforEnvironmentandHealthMunichD85758NeuherbergGermany

The molecular mechanism of how hepatocytes maintain cholesterol homeostasis has become much more transparent with the discovery of sterol regulatory element binding proteins (SREBPs) in recent years. These membrane proteins aremembers of the basic helix-loop-helix-leucine zipper (bHLHZip) family of transcription factors. They activate the expression of at least 30 genes involved in the synthesis of cholesterol and lipids. SREBPs are synthesized as precursor proteins in the endoplasmic reticulum (ER), where they form a complex with another protein, SREBP cleavage activating protein (SCAP). The SCAP molecule contains a sterol sensory domain. In the presence of high cellular sterol concentrations SCAP confines SREBP to the ER. With low cellular concentrations, SCAP escorts SREBP to activation in the Golgi. There, SREBP undergoes two proteolytic cleavage steps to release the mature, biologically active transcription factor, nuclear SREBP (nSREBP). nSREBP translocates to the nucleus and binds to sterol response elements (SRE) in the promoter/enhancer regions of target genes. Additional transcription factors are required to activate transcription of these genes. Three different SREBPs are known, SREBPs-1a, -1c and -2. SREBP-1a and -1c are isoforms produced from a single gene by alternate splicing. SREBP-2 is encoded by a different gene and does not display any isoforms. It appears that SREBPs alone, in the sequence described above, can exert complete control over cholesterol synthesis, whereas many additional factors (hormones, cytokines, etc.) are required for complete control of lipid metabolism. Medicinal manipulation of the SREBP/SCAP system is expected to prove highly beneficial in the management of cholesterol-related disease.

关键词： Animals CCAAT-Enhancer-binding proteins Cholesterol dna-binding proteins Homeostasis Humans Sterol Regulatory Element binding Protein 1 Sterol Regulatory Element binding Protein 2 Transcription Factors

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Stress- and Pathogen-Induced Arabidopsis WRKY48 is a Transcriptional Activator that Represses Plant Basal Defense

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Molecular Plant 2008年第3期1卷 459-470页

作者： Deng-Hui Xing Zi-Bing Lai Zu-Yu Zheng K. M. Vinod Bao-Fang Fan Zhi-Xiang Chen Debarment of Botanv and Plant Patholoclv Purdue University West Lafayette Indiana 47907-2054 USA Present address: Department of Botany Miami University Oxford Ohio 45056 USA

Plant WRKY transcription factors can function as either positive or negative regulators of plant basal disease resistance. Arabidopsis WRKY48 is induced by mechanical and/or osmotic stress due to infiltration and pathogen infection and, therefore, may play a role in plant defense responses. WRKY48 is localized to the nucleus, recognizes the TTGACC W- box sequence with a high affinity in vitro and functions in plant cells as a strong transcriptional activator. To determine the biological functions directly, we have isolated loss-of-function T-dna insertion mutants and generated gain-of-function transgenic overexpression plants for WRKY48 in Arabidopsis. Growth of a virulent strain of the bacterial pathogen Pseu- domonas syringae was decreased in the wrky48 T-dna insertion mutants. The enhanced resistance of the loss-of-function mutants was associated with increased induction of salicylic acid-regulated PR1 by the bacterial pathogen. By contrast, transgenic WRKY48-overexpressing plants support enhanced growth of P. syringae and the enhanced susceptibility was associated with reduced expression of defense-related PR genes. These results suggest that WRKY48 is a negative reg- ulator of PR gene expression and basal resistance to the bacterial pathogen P. syringae.

关键词： dna-binding proteins SYSTEMIC ACQUIRED-RESISTANCE PSEUDOMONAS-SYRINGAE SALICYLIC-ACID

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Induction of apoptosis by TPA and VP-16 is through translocation of TR3

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World Journal of Gastroenterology 2002年第3期8卷 446-450页

作者： LiuS WuQ 等 KeyLaboratoryoftheMinistryofEducationforCellBiologyandTumorCellEngineering SchoolofLifeSciencesXiamenUniversityXiamen361005FujianProvinceChina KeyLaboratoryoftheMinistryofEducationforCellBiologyan

AIM: To investigate the role of TR3 in induction of apoptosis in gastric cancer cells. METHODS: Human gastric cancer cell line, MGC80-3, was used. Expression of TR3 mRNA and its protein was detected by Northern blot and Western blot. Localization of TR3 protein was showed by immunofluorescence analysis under laser-scanning confocal microscope. Apoptotic morphology was observed by DAPI fluorescence staining, and apoptotic index was counted among 1000 cells randomly. Stable transfection assay was carried out by Lipofectamine. RESULTS: Treatment of MGC80-3 cells with TPA and VP-16 resulted in apoptosis, accompanied by the repression of Bcl-2 protein in a time-dependent manner. At the same time, TPA and VP-16 also up-regulated expression level of TR3 mRNA in MGC80-3 cells that expressed TR3 mRNA. When antisense-TR3 expression vector was transfected into the cells, expression of TR3 protein was repressed. In this case, TPA and VP-16 did not induce apoptosis. In addition, TPA and VP-16-induced apoptosis involved in translocation of TR3. In MGC80-3 cells, TR3 localized concentrative in nucleus, after treatment of cells with TPA and VP-16, TR3 translocated from nucleus to cytosol obviously. However, when this nuclear translocation was blocked by LMB, apoptosis was not occurred in MGC80-3 cells even in the presence of TPA and VP-16. CONCLUSION: Induction of apoptosis by TPA and VP-16 is through induction of TR3 expression and translocation of TR3 from nucleus to cytosol, which may be a novel signal pathway for TR3, and represent the new biological function of TR3 to exert its effect on apoptosis in gastric cancer cells.

关键词： Active Transport, Cell Nucleus Apoptosis dna-binding proteins Etoposide Gene Expression RNA, Messenger RNA, Neoplasm Receptors, Cytoplasmic and Nuclear Receptors, Steroid Research Support, Non-U.S. Gov't Signal Transduction Stomach Neoplasms Tetradecanoylphorbol Acetate Transcription Factors Tumor Cells, Cultured

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Effects of histone acetylation and dna methylation on p21^(WAF1)regulation

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World Journal of Gastroenterology 2002年第3期8卷 400-405页

作者： FangJY LuYY RenjiHospital ShanghaiInstituteofDigestiveDiseaseShanghaiSecondMedicalUniversityShanghaiChina BeijingCancerInstitute BeijingUniversityBeijing100000

Cell cycle progression is regulated by interactions between cyclins and cyclin-dependent kinases (CDKs). p21(WAF1) is one of the CIP/KIP family which inhibits CDKs activity. Increased expression of p21(WAF1) may play an important role in the growth arrest induced in transformed cells. Although the stability of the p21( WAF1) mRNA could be altered by different signals, cell differentiation and numerous influencing factors. However, recent studies suggest that two known mechanisms of epigenesis, *** inactivation by methylation in promoter region and changes to an inactive chromatin by histone deacetylation, seem to be the best candidate mechanisms for inactivation of p21( WAF1). To date, almost no coding region p21(WAF1) mutations have been found in tumor cells, despite extensive screening of hundreds of various tumors. Hypermethylation of the p21(WAF1) promoter region may represent an alternative mechanism by which the p21(WAF1/CIP1) gene can be inactivated. The reduction of cellular DNMT protein levels also induces a corresponding rapid increase in the cell cycle regulator p21(WAF1) protein demonstrating a regulatory link between DNMT and p21(WAF1) which is independent of methylation of dna. Both histone hyperacetylation and hypoacetylation appear to be important in the carcinoma process, and induction of the p21(WAF1) gene by histone hyperacetylation may be a mechanism by which dietary fiber prevents carcinogenesis. Here, we review the influence of histone acetylation and dna methylation on p21(WAF1) transcription, and affection of pathways or factors associated such as p 53, E2A, Sp1 as well as several histone deacetylation inhibitors.

关键词： dna Methylation dna-binding proteins Acetylation Acetyltransferases Base Sequence Basic Helix-Loop-Helix Transcription Factors Cell Cycle proteins Cell Transformation, Neoplastic CpG Islands Cyclin-Dependent Kinase Inhibitor p21 Cyclins dna Histone Acetyltransferases Histones Humans Molecular Sequence Data Nuclear proteins Signal Transduction Sp1 Transcription Factor Trans-Activators Transcription Factors

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Experimental and clinic-opathologic study on the relationship between transcription factor Egr-1 and esophageal carcinoma

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World Journal of Gastroenterology 2001年第4期7卷 490-495页

作者： Ming-Yao Wu Mao-Huai Chen Ying-Rui Liang Guo-Zhao Meng Huan-Xing Yang Chu-Xiang Zhuang Department of Pathology,Shantou University Medical College,Shantou 515031,Guangdong Province,China Supported by the National Natural Science Foundation of China,No.39670298. Department of Pathology Shantou University Medical College 22 Xinling Road Shantou 515031 Guangdong Province China. mywu@***

AIM: To observe the growth suppression effect of exogenous introduction of early growth response gene-1 (Egr-1 gene) on esophageal carcinoma tissue as well as on esophageal carcinoma cell line Eca109 and to explore the potential application of Egr-1 gene in gene therapy of tumor. METHODS: Eukaryotic expression vector of PCMV-Egr-1 plasmid was introduced into Eca109 cell line which expressed no Egr-1 protein originally with lipofectamine transfection method. The introduction and expression of PCMV-Egr-1 plasmid into Eca109 cell line was confirmed by G418 selection culture, PCR amplification of neogene contained in the vector, Western blot analysis and immunocytochemical analysis. The cell growth curve, soft agar colony formation rate and tumorigenicity in SCID mice were examined to demonstrate the growth suppression effect of exogenous Egr-1 gene on Eca109 cell line. The Egr-1 mRNA and Egr-1 protein were also detected in 50 surgical specimens of esophageal carcinoma by in situ hybridization and immunohistochemistry. RESULTS: Exogenous Egr-1 gene was introduced successfully into Eca109 cell line and expressed Egr-1 protein stably. The transfected Eca109 cell line grew more slowly than control Eca109 as shown by cell growth curves, the soft agar colony formation rate (4.0% vs 6.9%, P < 0.01) and the average growth rate of tumor in SCID mice (35.5 +/- 7.6 vs 65.8 +/- 7.6, P < 0.05). The expression level of Egr-1 mRNA and protein significantly increased in dysplastic epithelia adjacent to cancer rather than in cancer tissues (65.8% vs 20.0% by ISH and 57.9% vs 0.01). CONCLUSION: Exogenous Egr-1 gene shows the strong effect of growth inhibition in Eca109 cell line. Egr-1 in the cancer tissue shows down-regulated expression that supports the inhibited function of Egr-1 in cancer growth and suggests Egr-1 may have an important role in gene therapy of esophageal carcinoma.

关键词： Gene Expression Regulation, Neoplastic Animals Blotting, Western Carcinogenicity Tests Cell Division dna-binding proteins Early Growth Response Protein 1 Esophageal Neoplasms Humans Immediate-Early proteins Mice Mice, SCID Plasmids Research Support, Non-U.S. Gov't Transcription Factors Transfection Tumor Cells, Cultured

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Transcription factor EGR-1 inhibits growth of hepatocellular carcinoma and esophageal carcinoma cell lines

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World Journal of Gastroenterology 2002年第2期8卷 203-207页

作者： Miao-Wang Hao Li Liu,Department of Internal Medicine,Tangdu Hospital,Xi’an 710038,Shaanxi Province,China Ying-Rui Liang Ming-Yao Wu Huan-Xing Yang,Department of Pathology,Medical College of Shantou University,Shantou 515031,Guangdong Province,China Yan-Fang Liu,Department of Pathology,Fourth Military Medical University,Xi’an 710032,Shaanxi Province,China Department of Internal Medicine Tangdu Hospital Fourth Military Medical University Xi'an 710038 Shaanxi Province China. haomwg@***

AIM: The transcription factor EGR-1 (early growth response gene-1) plays an important role in cell growth, differentiation and development. It has identified that EGR-1 has significant transformation suppression activity in some neoplasms, such as fibrosarcoma, breast carcinoma. This experiment was designed to investigate the role of egr-1 in the cancerous process of hepatocellular carcinoma (HCC) and esophageal carcinoma (EC), and then to appraise the effects of EGR-1 on the growth of these tumor cells. METHODS: Firstly, the transcription and expression of egr-1 in HCC and EC, paracancerous tissues and their normal counterpart parts were detected by in situ hybridization and immunohistochemistry, with normal human breast and mouse brain tissues as positive controls. Egr-1 gene was then transfected into HCC (HHCC, SMMC7721) and EC (ECa109) cell lines in which no egr-1 transcription and expression were present. The cell growth speed, FCM cell cycle, plate clone formation and tumorigenicity in nude mice were observed and the controls were the cell lines transfected with vector only. RESULTS: Little or no egr-1 transcription and expression were detected in HCC, EC and normal liver tissues. The expression of egr-1 were found higher in hepatocellular paracancerous tissue (transcription level P=0.000; expression level P=0.143, probably because fewer in number of cases) and dysplastic tissue of esophageal cancer (transcription level P=0.000; expression level P=0.001). The growth rate of egr-1-transfected HHCC (HCC cell line) cells and ECa109 (EC cell line) cells was much slower than that of the controls. The proportion of S phase cell, clone formation and tumorigenicity were significantly lower than these of the controls' (decreased 45.5% in HHCC cells and 34.1% in ECa109 cells; 46.6% and 41.8%; 80.4% and 72.6% respectively). There were no obvious differences between SMMC7721 (HCC) egr-1-transfected cells and the controls with regard to the above items. CONCLUSION: The dec

关键词： Animals Carcinoma, Hepatocellular Cell Division Cell Transplantation dna-binding proteins Early Growth Response Protein 1 Esophageal Neoplasms Humans Immediate-Early proteins In Situ Hybridization Liver Neoplasms Mice Mice, Nude Neoplasm Transplantation Research Support, Non-U.S. Gov't Transcription Factors Tumor Cells, Cultured

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Changes of NF-kB,p53,Bcl-2 and caspase in apoptosis induced by JTE-522 in human gastric adenocarcinoma cell line AGS cells:role of reactive oxygen species

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World Journal of Gastroenterology 2002年第3期8卷 431-435页

作者： Hong-Liang Li Xiao-Hong Li Yan-Qing L Chun-Ling Ye Xian-Da Ren,Department of Pharmacology,Jinan University Pharmacy College,Guangzhou 510632,Guangdong,China Dan-Dan Chen,Department of Cardiology,First Affiliated Hospital,Zhongshan University,Guangzhou 510089,Guangdong,China Hai-Wei Zhang,Department of Pathology,Jinan University Medical College,Guangzhou 510632,Guangdong,China Department of Pharmacology Jinan University Pharmacy College Guangzhou 510632 Guangdong China.

AIM: To identify whether JTE-522 can induce apoptosis in AGS cells and ROS also involved in the process, and to investigate the changes in NF-kB, p53, bcl-2 and caspase in the apoptosis process. METHODS: Cell culture, MTT, Electromicroscopy, agarose gel electrophoresis, lucigenin, Western blot and electrophoretic mobility shift assay (EMSA) analysis were employed to investigate the effect of JTE-522 on cell proliferation and apoptosis in AGS cells and related molecular mechanisms. RESULTS: JTE-522 inhibited the growth of AGS cells and induced the apoptosis. Lucigenin assay showed the generation of ROS in cells under incubation with JTE-522. The increased ROS generation might contribute to the induction of AGS cells to apoptosis. EMSA and Western blot revealed that NF-kB activity was almost completely inhibited by preventing the degradation of IkBalpha. Additionally, by using Western blot we confirmed that the level of bcl-2 was decreased, whereas p53 showed a great increase following JTE-522 treatment. Their changes were in a dose-dependent manner. CONCLUSION: These findings suggest that reactive oxygen species, NF-kB, p53, bcl-2 and caspase-3 may play an important role in the induction of apoptosis in AGS cells after treatment with JTE-522.

关键词： I-kappa B proteins Adenocarcinoma Apoptosis Benzenesulfonates Caspases Cell Division dna-binding proteins Humans NF-kappa B Oxazoles Proto-Oncogene proteins c-bcl-2 Reactive Oxygen Species Research Support, Non-U.S. Gov't Stomach Neoplasms Tumor Cells, Cultured Tumor Suppressor Protein p53

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Review of current progress in the structure and function of Smad proteins

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Chinese Medical Journal 2002年第3期115卷 446-450页

作者：陈伟付小兵盛志勇解放军第304医院全军创伤修复重点研究室北京100037

PURPOSE: To review the recent developments in the structure and function of Smad proteins. DATA SOURCES: Both Chinese- and English-language literatures were searched using MEDLINE/CD-ROM (1997 - 2000) and the Index of Chinese-Language Literature (1997 - 2000). STUDY SELECTION: Data from published articles about TGF-beta signal transduction in recent domestic and foreign literature were selected. DATA EXTRACTION: Data were mainly extracted from 22 articles which are listed in the reference section of this review. RESULTS: Smad proteins mediate signal transduction induced by the TGF-beta superfamily. Based on their structural and functional properties, Smad proteins are divided into three groups. The first group, receptor-regulated Smads (R-Smads), are phosphorylated by activated type I receptors and form heteromeric complexes with the second group of Smads, common mediator Smads (Co-Smads). These Smad complexes translocate into the nucleus to influence gene transcription. Inhibitory Smads (I-Smads) are the third group and these antagonize the activity of R-Smads. In the nucleus, Smads can directly contact Smad-binding elements (SBE) in target gene promoters. Through interaction with different transcription factors, transcriptional co-activators or co-repressors, Smads elicit different effects in various cell types. The aberrance of Smad proteins has been noted in several human disorders such as fibrosis, hypertrophic scarring and cancer. CONCLUSION: The structure of Smads determines their function as transcriptional factors which translocate signals from the cell surface to the nucleus where Smads regulate TGF-beta superfamily-dependent gene expression.

关键词： dna-binding proteins Humans Research Support, Non-U.S. Gov't Signal Transduction Smad proteins Trans-Activators Transcription Factors Transforming Growth Factor beta

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A novel erythroid differentiation related gene EDRF1 upregulating globin gene expression in HEL cells

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Chinese Medical Journal 2002年第11期115卷 1701-1705,154-155页

作者：王敦成黎燕沈倍奋军事医学科学院基础医学研究所北京100850

OBJECTIVE: To further characterize the differentiation inducing properties of EDRF1 and demonstrate its functional pathway involved in regulation of globin gene expression. METHODS: By transfecting EDRF1 sense and antisense constructs into HEL cells, we identified the expression of globin and erythropoietin receptor genes by Northern blot analysis. RT-PCR and EMSA (electrophoresis mobility shift assay) were performed to monitor the expression and dna-binding activity of erythroid specific transcription factors GATA-1 and NF-E2. RESULTS: It was shown that when EDRF1 was overexpressed, production of alpha-globin increased. In antisense EDRF1, overexpression of HEL cells, significant loss of alpha-, gamma-globin mRNA synthesis was observed. The transcription of endogenous GATA-1 and NF-E2 mRNA expression were maintained at the same levels compared with control experiments. However, the transcription activity of GATA-1 was severely impaired. Expression of erythropoietin receptor gene was not influenced by EDRF1 gene overexpression. CONCLUSION: The results suggested that EDRF1 regulated alpha- and gamma-globin gene synthesis by modulating dna-binding activity of GATA-1 transcription factor.

关键词： Gene Expression Regulation Cell Differentiation Cells, Cultured dna-binding proteins Erythroid-Specific dna-binding Factors Erythropoiesis GATA1 Transcription Factor Globins Humans NF-E2 Transcription Factor NF-E2 Transcription Factor, p45 Subunit RNA, Messenger Transcription Factors Up-Regulation

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Increased sensitivity of colorectal cancer cell lines with microsatellite instability to 5-fluorouracil in vitro

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Chinese Medical Journal 2002年第7期115卷 1048-1052,151-152页

作者：陈修煦来茂德黄琼浙江大学医学院病理学教研室杭州310031

OBJECTIVE: To study the relationship between sensitivity to 5-FU and the status of a panel of microsatellite loci in three human colon cancer cell lines. METHODS: Cell viability in several concentrations of 5-FU was assessed by the MTT test. Expression of hMSH2 and hMLH1 in LoVo, SW480 and SW1116 cells were analyzed by immunocytochemical *** mononucleotide and dinucleotide microsatellite loci were analyzed by the PCR-SSLP-silver staining method. RESULTS: By MTT assay, it showed that LoVo cells were more sensitive than SW480 and SW1116 cells (0.8 micromol/L,2.2 micromol/L and 1.9 micromol/L, respectively, P

关键词： dna-binding proteins Microsatellite Repeats Antimetabolites, Antineoplastic Base Pair Mismatch Carrier proteins Colorectal Neoplasms dna Repair Fluorouracil Humans Immunohistochemistry MutS Homolog 2 Protein Neoplasm proteins Nuclear proteins Polymerase Chain Reaction Proto-Oncogene proteins Tumor Cells, Cultured

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