PURPOSE: The role of the Ferric Uptake Regulator (FUR) in the acid resistance of Helicobacter pylori (H. pylori) has been thought to be independent of urease. However, we demonstrated in this study that Fur influences urease activity. MATERIALS AND METHODS: A fur knockout mutant of H. pylori was constructed by replacing the Fur gene with a kanamycin resistant marker gene. The wild-type H. pylori and fur mutant were compared for survival. The integrity of the inner membrane of the bacteria was evaluated by confocal microscopy using membrane-permeant and -impermeant fluorescent DNA probes. Urease activity of intact H. pylori was measured between pH 3 and 8. Real time PCR of both strains was performed for urease genes including ureI, ureE, ureF, ureG, and ureH. RESULTS: The fur deletion affected the survival of H. pylori at pH 4. The urease activity curve of the intact fur mutant showed the same shape as the wild-type but was 3-fold lower than the wild-type at a pH of less than 5. Real time PCR revealed that the expression of all genes was consistently down-regulated in the fur mutant. CONCLUSION: The results of this study showed that fur appears to be involved in acid resistant H. pylori urease activity.
Bacterial Proteins/genetics/*physiology ; Helicobacter pylori/*enzymology/genetics ; Hydrogen-Ion Concentration ; Microscopy, Confocal ; Models, Biological ; Mutation ; Repressor Proteins/genetics/*physiology ; Urease/*metabolism

BACKGROUNDBrain acid soluble protein 1 (BASP1) is identified as a novel potential tumor suppressor in several cancers. However, its role in thyroid cancer has not been investigated yet. In the present study, the antitumor activities of BASP1 against the growth and migration of thyroid cancer cells were evaluated.

METHODSBASP1 expression in thyroid cancer tissues and normal tissues were examined by immunohistochemical staining and the association between its expression and prognosis was analyzed. pcDNA-BASP1 carrying full length of BASP1 cDNA was constructed to restore the expression of BASP1 in thyroid cancer cell lines (BHT-101 and KMH-2). The cell proliferation in vitro and in vivo was evaluated by WST-1 assay and xenograft tumor models, respectively. Cell cycle distribution after transfection was analyzed using flow cytometry. Cell apoptosis after transfection was examined by annexin V/propidium iodide assay. The migration was examined using transwell assay.

RESULTSBASP1 expression was abundant in normal tissues while it is significantly decreased in cancer tissues (P = 0.000). pcDNA-BASP1 restored the expression of BASP1 and significantly inhibited the growth of BHT-101 and KMH-2 cells as well as xenograft tumors in nude mice (P = 0.000). pcDNA-BASP1 induced G1 arrest and apoptosis in BHT-101 and KMH-2 cells. In addition, pcDNA-BASP1 significantly inhibited the cell migration.

CONCLUSIONSDownregulation of BASP1 expression may play a role in the tumorigenesis of thyroid cancer. Restoration of BASP1 expression exerted extensive antitumor activities against growth and migration of thyroid cancer cells, which suggested that BASP1 gene might act as a potential therapeutic agent for the treatment of thyroid cancer.

Aged ; Animals ; Apoptosis ; genetics ; physiology ; Calmodulin-Binding Proteins ; genetics ; metabolism ; Cell Cycle ; genetics ; physiology ; Cell Line, Tumor ; Cell Movement ; genetics ; physiology ; Cell Proliferation ; genetics ; physiology ; Cytoskeletal Proteins ; genetics ; metabolism ; Female ; Gene Expression Regulation, Neoplastic ; genetics ; physiology ; Humans ; Male ; Membrane Proteins ; genetics ; metabolism ; Mice ; Mice, Nude ; Middle Aged ; Nerve Tissue Proteins ; genetics ; metabolism ; Repressor Proteins ; genetics ; metabolism ; Thyroid Neoplasms ; metabolism ; pathology ; Xenograft Model Antitumor Assays

RNA silencing is a conserved eukaryotic pathway involved in the suppression of gene expression via sequence-specific interactions that are mediated by 21-23 nt RNA molecules. During infection, RNAi can act as an innate immune system to defend against viruses. As a counter-defensive strategy, silencing suppressors are encoded by viruses to inhibit various stages of the silencing process. These suppressors are diverse in sequence and structure and act via different mechanisms. In this review, we discuss whether RNAi is a defensive strategy in mammalian host cells and whether silencing suppressors can be encoded by mammalian viruses. We also review the modes of action proposed for some silencing suppressors.
Animals ; Gene Expression Regulation, Viral ; Gene Silencing ; Host-Pathogen Interactions ; Humans ; Mammals ; virology ; MicroRNAs ; genetics ; metabolism ; Plant Viruses ; physiology ; Plants ; virology ; RNA, Small Interfering ; genetics ; metabolism ; Repressor Proteins ; genetics ; metabolism ; Viral Proteins ; genetics ; metabolism ; Viruses ; growth & development

OBJECTIVETo analyze the change of the neuronal restricted silencing factor (NRSF) gene as well as the NRSF regulation genes in beta-mercaptoethanol induction of the marrow mesenchymal stem cells (MSCs) to neurons, and to discuss the function of NRSF in neural induction of the MSCs and the mechanism of the differentiation from MSCs to neurons.

METHODWe used beta-mercaptoethanol, serum-free DMEM, and dimethyl sulfoxide to induce rat MSCs to differentiate to neurons, and then analyzed the changes of the expressions of NRSF gene and NRSF-regulated genes through real-time PCR.

RESULTSThe rat MSCs were successfully induced to differentiate into neuron-like cells. The induced neuron marker, neuron-specific enolase, was positive. Real-time PCR showed that the expression of NRSF gene remarkably declined. The expressions of neurotrophic tyrosine kinase receptor, type 3, synaptosomal-associated protein 25, L1 cell adhesion molecular,neuronal pentraxin receptor in the NRSF-regulated genes also increased at varied extents.

CONCLUSIONSThe differentiation from MSCs to neurons is relevant with the decline of NRSF expression and the increase of the expressions of NRSF-regulated genes. The NRSF may be the key gene during the differentiation from MSCs to neurons.

Animals ; Bone Marrow Cells ; cytology ; metabolism ; Cell Differentiation ; physiology ; Cells, Cultured ; Mesenchymal Stromal Cells ; cytology ; metabolism ; Neurons ; cytology ; metabolism ; Phosphopyruvate Hydratase ; genetics ; metabolism ; Rats ; Rats, Wistar ; Repressor Proteins ; metabolism ; physiology ; Synaptosomal-Associated Protein 25 ; genetics ; metabolism

Axin is a negative regulator of the Wnt/beta-catenin pathway and is involved in the regulation of axis formation and proliferation. Involvement of Axin in the regulation of other signaling pathways is poorly understood. In this study, we investigated the involvement of Akt in growth regulation by Axin in L929 fibroblasts stimulated by EGF. Akt activity was increased by EGF treatment and Ras activation, respectively. Both the EGF- and Ras-induced Akt activations were abolished by Axin induction, as revealed by both Western blot and immunocytochemical analyses. The proliferation and Akt activation induced by EGF were decreased by Axin induction, and the effects of EGF were abolished by treatment of an Akt-specific inhibitor. Therefore, Axin inhibits EGF-induced proliferation of L929 fibroblasts by blocking Akt activation.
Animals ; Cell Line ; Cell Nucleus/metabolism ; Cell Proliferation ; Epidermal Growth Factor/*pharmacology ; Fibroblasts/drug effects/physiology ; Mice ; Proto-Oncogene Proteins c-akt/antagonists & inhibitors/*metabolism ; Repressor Proteins/genetics/*physiology ; Signal Transduction ; ras Proteins/biosynthesis/genetics

Low density lipoprotein receptor (LDLR) plays an important role in the cholesterol homeostasis. We examined the possible circadian regulation of LDLR and mechanism(s) underlying it. In mice, blood glucose and plasma triglyceride, total and high density lipoprotein cholesterol varied distinctively throughout a day. In addition, LDLR mRNA oscillated in the liver in a functional clock-dependent manner. Accordingly, analysis of human LDLR promoter sequence revealed three putative E-boxes, raising the possible regulation of LDLR expression by E-box-binding transcription factors. To test this possibility, human LDLR promoter reporter constructs were transfected into HepG2 cells and the effects of CLOCK/BMAL1, Hes1, and Hes6 expression were analyzed. It was found that positive circadian transcription factor complex CLOCK/BMAL1 upregulated human LDLR promoter activity in a serum-independent manner, while Hes family members Hes1 and Hes6 downregulated it only under serum-depleted conditions. Both effects were mapped to proximal promoter region of human LDLR, where mutation or deletion of well-known sterol regulatory element (SRE) abolished only the repressive effect of Hes1. Interestingly, hes6 and hes1 mRNA oscillated in an anti-phasic manner in the wild-type but not in the per1-/-per2-/- mouse. Comparative analysis of mouse, rat and human hes6 genes revealed that three E-boxes are conserved among three species. Transfection and site-directed mutagenesis studies with hes6 reporter constructs confirmed that the third E-box in the exon IV is functionally induced by CLOCK/BMAL1. Taken together, these results suggest that LDLR expression is under circadian control involving CLOCK/BMAL1 and Hes family members Hes1 and Hes6.
ARNTL Transcription Factors/physiology ; Animals ; Base Sequence ; Basic Helix-Loop-Helix Transcription Factors/*genetics/metabolism/physiology ; CLOCK Proteins/physiology ; Cholesterol/blood ; *Circadian Rhythm ; E-Box Elements ; Exons ; *Gene Expression Regulation ; Hep G2 Cells ; Homeodomain Proteins/*genetics/metabolism/physiology ; Homeostasis ; Humans ; Liver/metabolism ; Male ; Mice ; Mice, Inbred C57BL ; *Promoter Regions, Genetic ; Receptors, LDL/*genetics/metabolism ; Repressor Proteins/*genetics/metabolism/physiology ; Transcription, Genetic

BACKGROUNDThe tendency of tumor cells to disperse throughout the liver is a distinct feature of hepatocellular carcinoma (HCC). Nck family adaptor proteins function to regulate actin cytoskeletal reorganization that leads to cell motility. We previously found that Max binding protein (MNT) was differentially expressed in HCC, and interacted with Nck1 by 2-DE. MNT is a protein member of the Myc/Max/Mad network which plays roles in cell proliferation, differentiation, and death. We investigated the effects of MNT on migration of human liver cancer SK-HEP-1 cells to study the migration regulatory role of MNT in HCC cells.

METHODSInteraction between MNT and Nck1 was further validated in hepatoma cells by GST-pull down assay and immunoprecipitation. siRNAs specific to MNT (MNT siRNA) were used to knockdown MNT expression. Western blotting, transwell assay were used to determine the migration potential of cells.

RESULTSInteraction between MNT and Nck1 was validated in hepatoma cells. MNT knockdown promoted the migration of human liver cancer SK-HEP-1 cells (P < 0.01).

CONCLUSIONThe results suggest that MNT, via interaction with Nck1, inhibits hepatoma cell migration.

Adaptor Proteins, Signal Transducing ; genetics ; metabolism ; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors ; genetics ; metabolism ; Blotting, Western ; Cell Differentiation ; genetics ; physiology ; Cell Line, Tumor ; Cell Movement ; genetics ; physiology ; Humans ; Immunoprecipitation ; Liver Neoplasms ; Oncogene Proteins ; genetics ; metabolism ; Protein Binding ; genetics ; physiology ; Repressor Proteins ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction

To investigate the effects and molecular mechanisms of the cellular repressor of E1A-stimulated genes (CREG) on the apoptosis of vascular smooth muscle cells (VSMCs), the human internal thoracic artery-Shenyang (HITASY) cells were infected with sense-CREG [pLNCX(2)(+)/CREG] and antisense-CREG [pLXSN(-)/CREG] retrovirus respectively. The stably infected cells were obtained by screening the G418-resistant clones. DAPI nuclei staining and Annexin V/PI FASC assay indicated that over-expression of CREG in HITASY cells infected with pLNCX(2) (+)/CREG inhibited VSMC apoptosis induced by serum deprivation, accompanied with decreased expression of caspase-9 mRNA detected by RT-PCR. Furthermore, Western blot analysis showed that p38 mitogen activated protein kinase (p38 MAPK) expression and activation were significantly enhanced in HITASY cells infected with pLNCX(2) (+)/CREG. The inhibition of CREG protein expression in cells infected with pLXSN(-)/CREG promoted the VSMC spontaneous apoptosis, as well as down-regulated p38 MAPK expression and activation, when cells were cultured with 10% fetal bovine serum (FBS) mediums. These results implicate that the CREG protein has the ability to regulate VSMC apoptosis in which the activation of p38 MAPK is possibly involved. To further identify the role of p38 MAPK in VSMC apoptosis, SB203580, a specific inhibitor of p38 MAPK, was used to inhibit p38 MAPK activity. When p38 MAPK signaling pathway was blocked, the effects that over-expression of CREG protein inhibited VSMC apoptosis disappeared. Taken together, the present work indicates that over-expression of CREG protein inhibits VSMC apoptosis, and this inhibitory effect is partly mediated by p38 MAPK signaling pathway.
Apoptosis ; physiology ; Caspase 9 ; metabolism ; Cells, Cultured ; Humans ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; metabolism ; Repressor Proteins ; genetics ; physiology ; Signal Transduction ; physiology ; p38 Mitogen-Activated Protein Kinases ; metabolism

BACKGROUND AND OBJECTIVEPrevious studies have shown that Bmi-1 is overexpressed in a variety of tumors, suggesting that Bmi-1 plays an important role in tumorigenesis. In this study, we investigated the effect of Bim-1 siRNA on cell proliferation, cell cycle, cell apoptosis and migration of human esophageal carcinoma EC9706 cells, and explored its potential mechanisms.

METHODSBmi-1 small interfering RNA (siRNA) was transferred into EC9706 cells. Then, cell proliferation was measured using cell counting kit-8 (CCK-8), cell cycle and cell apoptosis were analyzed by flow cytometry, cell migration ability was detected using Boyden chamber assay, and the mRNA and protein expression levels of Bmi-1, p16, Bcl-2, Bax, and MMP-2 were determined using real-time polymerase chain reaction (PCR) and Western blot analysis, respectively.

RESULTSBmi-1 siRNA treatment significantly inhibited the expression of Bmi-1 at both mRNA and protein levels in EC9706 cells. Cell proliferation rate decreased dramatically in the Bmi-1 siRNA treated group than in the untreated group and in the scrambled siRNA treated group (both P < 0.001). In Bmi-1 treated group, the percentage of cells at G(0)/G(1) stage was 71.93%, which was higher than that in the untreated group (47.36%) or scramble siRNA treated group (48.47%) (both P < 0.001). Early cell apoptosis rate also increased significantly in the Bmi-1 siRNA treated group (both 17.32%) than in the untreated group (2.61%) and in the scramble siRNA treated group (2.73%) (both P < 0.001). Further experiment suggested that downregulation of Bmi-1 led to less cell migration. In EC9706 cells transfected by Bmi-1 siRNA, the expression levels of p16 and Bax increased, while the expression level of Bcl-2 decreased.

CONCLUSIONSBmi-1 downregulation in esophageal carcinoma cells inhibits cell proliferation, cell cycle, and cell migration, while increases cell apoptosis. These results suggest that Bmi-1 is a potential molecular target of treating esophageal cancer.

Apoptosis ; Cell Cycle ; Cell Line, Tumor ; Cell Movement ; Cell Proliferation ; Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; Down-Regulation ; Esophageal Neoplasms ; metabolism ; pathology ; Gene Expression Regulation, Neoplastic ; Humans ; Nuclear Proteins ; genetics ; metabolism ; physiology ; Polycomb Repressive Complex 1 ; Proto-Oncogene Proteins ; genetics ; metabolism ; physiology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; genetics ; Repressor Proteins ; genetics ; metabolism ; physiology ; Transfection ; bcl-2-Associated X Protein ; metabolism

BACKGROUNDHepatocyte growth factor (HGF) treats ischemic disease by promoting arteriogenesis, however, its mechanism of action is not known. The notch signaling pathway plays an important role in neovascularization. The relationship between the proliferation and migration ability of artery endothelial cells and the Dll4-Notch-Hey2 signaling pathway in the process of arteriogenesis was investigated as a mechanism of action of HGF.

METHODSBased on the prophase study cells and supernatant were harvested at the indicated time after human femoral artery endothelial cells (HFAECs) were infected with adenovirus-HGF (Ad-HGF) at 200 pfu/cell. Cells were analyzed for HGF expression and Notch1, Dll4 and Hey2 expression by ELISA and reverse transcription-PCR (RT-PCR). The changes in the proliferation and migration ability of HFAECs were observed by MTT and Transwell migration experiments. Ad-GFP-infected HFAECs were used as control.

RESULTSCompared with the control group the Ad-HGF group's HGF expression was not increased with time, and the induction by HGF of Notch1, Dll4 and Hey2 gene transcription was not enhanced with an increase of HGF. The proliferation ability of Ad-HGF-transduced HFAECs was enhanced and their migration ability was also enhanced in the presence of HGF.

CONCLUSIONSThrough activating the Dll4-Notch-Hey2 signaling pathway, HGF indirectly promotes the proliferation and migration ability of cells, so that offspring artery branches are formed.

Basic Helix-Loop-Helix Transcription Factors ; genetics ; metabolism ; Cell Line ; Enzyme-Linked Immunosorbent Assay ; Hepatocyte Growth Factor ; genetics ; metabolism ; Humans ; Intercellular Signaling Peptides and Proteins ; genetics ; metabolism ; Receptors, Notch ; genetics ; metabolism ; Repressor Proteins ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Signal Transduction ; genetics ; physiology