OBJECTIVETo study the effects of licorice on the proliferation of intestinal crypt stem cell line IEC-6 and the expression of p53.

METHODSInduced by difluoro-methylornithine (DFMO), polyamine-depleted IEC-6 cells under growth inhibition were used as the pathological cell model in this study. Cells were divided into four groups, i. e., the control group, the DFMO-treated group, the high dose licorice group, and the low dose licorice group. The control group consisted of IEC-6 cells cultured in normal condition. The other three groups were all treated with 5 mmol/L DFMO. The high dose and low dose licorice groups were supplemented with 40 and 80 microg/mL licorice granule respectively. All the groups were cultured for 6 successive days. The cell number and viability were determined using flow cytometry. The level of p53 protein was detected by Western blot. The p53 mRNA levels and stability were detected using fluorescent quantitative Real-time PCR.

RESULTSCompared with the control group, the cell growth of the DFMO group was obviously inhibited on the 4th day (P < 0.05). The cell number increased more obviously in the low dose licorice and the high dose licorice groups in a dose-dependent way on the 6th day when compared with the DFMO group (P < 0.05). When compared with the control group, significantly elevated expression levels of p53 protein and mRNA in cells of the DFMO group were detected after 6-day treatment (P < 0.05). When compared with the DFMO group, the expression levels of p53 protein and mRNA were significantly down-regulated in the low dose licorice and the high dose licorice groups (P < 0.05). The degradation of p53 mRNA was the fastest in the control group, while the degradation speed of cells in the DFMO group was the slowest.

CONCLUSIONOne of mechanisms for protective and healing effects of licorice on the intestinal mucosa was possibly through down-regulating the stability of p53 mRNA, lowering the expression of p53, thus promoting the proliferation of the intestinal crypt stem cells.

Animals ; Cell Line ; Cell Proliferation ; Glycyrrhiza ; Intestines ; cytology ; metabolism ; RNA Stability ; drug effects ; RNA, Messenger ; genetics ; Rats ; Stem Cells ; cytology ; drug effects ; metabolism ; Tumor Suppressor Protein p53 ; metabolism

The lipase labeled with the fluorescein isothiocyanat (FITC) was immobilized on the derivatives of the polyethylene glycol. The article discussed the effect of factors on the characters of lipase and analyzed the relationships among the activity of lipase, conformation, and fluorescence spectrum while the activity and the fluorescence spectrum of immobilized lipase were determined. The results demonstrated that polyethylene glycol 400-diacrylate could form appropriate network to improve the activity of enzyme. Adding ligand induced the lipase's catalytic conformation to increase the activity twice more than before. The active centre of lipase could be released by the extraction of ligand thus increasing the activity. After immobilization, the stability of labeled lipase improved greatly: immobilized lipases retained more than 70% and 60% of initial activity under conditions of 90 degrees C and strong acid or alkali, respectively. After immersing immobilized lipases into guanidine hydrochloride or urea for 15 days, the lipases retained upwards of 70% activity. The fluorescence spectrum could obviously reflect the changes of the activity and conformation of lipase. The fluorescence intensity was the minimum in the optimal pH and temperature. In the denaturing agent it declined as time passed. These results indicated that the unfolded processes of immobilized lipases are different under different conditions.
Dextrans ; chemistry ; Enzyme Stability ; Enzymes, Immobilized ; chemistry ; metabolism ; Fluorescein-5-isothiocyanate ; analogs & derivatives ; chemistry ; Fluorescent Dyes ; chemistry ; Lipase ; chemistry ; metabolism ; Polyethylene Glycols ; chemistry ; Protein Unfolding ; drug effects

According to the knowledge gained from engineering of nisinZ, using plasmid pHJ201 DNA as template, NisinZ was mutated by site-directed mutagenesis, NisinZ mutant T8S contains Serine at position 8 instead of Threonine, NisinZ mutant N27K/H31K contains Lysine at position 27 and 31, respectively, instead of Asparagine and Histidine and NisinZ mutant T2S/ H31K contains dehydrobutyrine and Lysine at position 2 and 31 instead of dehydroalanine and Histidine. They are cloned into pMG36e and expressed in L. Lactis NZ9800, the expression products of these mutants purified by Sephadex CM-25 and Sephadex G-25 chromatography, some properties of NisinZ mutants (T8S, T2S/H31K and N27K/H31K) were studied. The results showed that the spectrum of antimicrobial activity and solubility of these mutants had not been changed, their antimicrobial activities were found to be slightly lower than that of the wild-type NisinZ. but mutants T8S and T2S/H31K showed higher stability, which were significantly more stable than wild-type NisinZ at 55 approximately 100 degrees C and pH7 approximately 9.
Anti-Bacterial Agents ; metabolism ; pharmacology ; Bacteria ; drug effects ; Electrophoresis, Polyacrylamide Gel ; Mutagenesis, Site-Directed ; methods ; Nisin ; analogs & derivatives ; genetics ; metabolism ; pharmacology ; Protein Stability ; Solubility ; Temperature

Cystatin, which widely distributed in both tissues and body fluids of animal and plant, was a superfamily of cysteine proteinase inhibitors. It could form activity-inhibitor complexes with cysteine proteinases to inhibit the hydrolytic activity of proteinases. Cystatin played important roles not only in the inhibition of the proteolytic degradation of fish muscle, but also in biological defense systems against invaders. To explore the functions of fish cystatin and the potential values in fish disease prevention and cure, as well as seafood processing, the recombinant yeast strains which could express Chinese sturgeon cystatin were constructed. First, the cystatin cDNA of Chinese sturgeon, which had been PCR modified, was subcloned into yeast integrated vector pPICZaA. After extracted and purified, the recombinant plasmids were linearized by Sac I. The yeast Pichia pastoris GS115 strain was transformed by use of the Lithium Chloride transformation method, and the recombinant cystatin yeast strains got. After 0.5% methanol induction, SDS-PAGE analysis of the culture supernatant indicated that the yield of recombinant cystatin was about 215mg x L(-1) with the percentage about 73.6%. The recombinant cystatin was purified through Q-Sepharose anion-exchange chromatography, and the purity reached about 94.2%. The inhibitory activity of recombinant cystatin was measured by inhibiting the proteinase activity of papain. The results showed that about 1 microg recombinant cystatin could inhibit the activity of 15 microg papain. Heat stability assay results showed that there was a decrease in inhibitory activity of cystatin with the increasing of temperature. When solution of recombinant cystatin was kept at 70 degrees C for 5min, the inhibitory activity reduced fast. While the recombinant cystatin was heated to 90 degrees C for 5min, the inhibitory activity of recombinant cystatin was undetected. The inhibitory activity for recombinant Chinese sturgeon cystatin was higher than that of CPI (cysteine proteinase inhibitor) from seeds of corn, that about 1 microg purified CIP could inhibited the activity of 0.278 microg papain. But the heat stability of recombinant cystatin is lower than that of the corn CPI. The expression level and the activity of recombinant cystatin from yeast Pichia pastoris were higher than those from E. coli. Moreover, recombinant cystatin from Pichia pastoris was easier to separate and purify. This paper reported that recombinant fish cystatin was produced in a highly efficient expression system based on the methylotrophic yeast, further work will focus on the function of recombinant Chinese sturgeon cystatin to resist fish disease and explore the value of cystatin as a food additive to inhibit cysteine proteinases during surimi processing.
Animals ; Cystatins ; genetics ; metabolism ; pharmacology ; Cysteine Proteinase Inhibitors ; genetics ; metabolism ; pharmacology ; Enzyme Activation ; drug effects ; Fish Proteins ; genetics ; metabolism ; Pichia ; genetics ; metabolism ; Polymerase Chain Reaction ; Protein Stability ; Temperature

Phycocyanin subunits liposomes (PCS-lip) were prepared and its cellular uptake and photodynamic therapy (PDT) effect on cancer cells were studied. In the experiment, film dispersion method was used to prepare phycocyanin subunits liposomes; particle size and distribution were detected by zetasizer and transmission electric microscope; the effects of liposome as carrier on cell uptake in vitro were evaluated in S180 by using fluorescence microscope; and photodynamic therapy effect was assessed with MTT method. As shown in the results, the particle size mainly ranged from 80 nm to 160 nm, and average encapsulation rate was 42.3%. In the concentration of 100 microg x mL(-1), transfection rate reached (18.5 +/- 0.8)% at 2 h, (23.1 +/- 0.9)% at 4 h, keeping a balance in 5-6 h, and its photodynamic therapy effect in vitro improved with the increasing of concentration of phycocyanin subunits liposomes. In the concentration of 200 micro x mL(-1) cell survival rate of BGC-823 and S180 reached (45 +/- 5.2)% and (36 +/- 5.5)%, respectively, and the cell survival rate differentiation between PCS-PDT group and PCS-lip-PDT group reached 7%-11% (P < 0.05). In this study film dispersion method could keep the biological activity of phycocyanin subunits very well. Phycocyanin subunits liposomes will transfect cells more quickly than phycocyanin subunits in the same concentration, and in the same conditions, phycocyanin subunits liposomes have the better PDT effect on cancer cells as they were incubated with cells for 4 h.
Animals ; Cell Line, Tumor ; Cell Survival ; drug effects ; Drug Carriers ; Drug Stability ; Humans ; Liposomes ; chemistry ; Mice ; Particle Size ; Photochemotherapy ; methods ; Phycocyanin ; administration & dosage ; pharmacology ; Protein Subunits ; administration & dosage ; pharmacology ; Sarcoma 180 ; pathology ; Stomach Neoplasms ; pathology

Angiogenesis is critical and indispensable for tumor progression. Since VEGF is known to play a central role in angiogenesis, the disruption of VEGF-VEGF receptor system is a promising target for anti-cancer therapy. Previously, we reported that a hexapeptide (RRKRRR, RK6) blocked the growth and metastasis of tumor by inhibiting VEGF binding to its receptors. In addition, dRK6, the D-form derivative of RK6, retained its biological activity with improved serum stability. In the present study, we developed a serum-stable branched dimeric peptide (MAP2-dRK6) with enhanced anti-VEGF and anti-tumor activity. MAP2-dRK6 is more effective than dRK6 in many respects: inhibition of VEGF binding to its receptors, VEGF- and tumor conditioned medium-induced proliferation and ERK signaling of endothelial cells, and VEGF-induced migration and tube formation of endothelial cells. Moreover, MAP2-dRK6 blocks in vivo growth of VEGF-secreting colorectal cancer cells by the suppression of angiogenesis and the subsequent induction of tumor cell apoptosis. Our observations suggest that MAP2-dRK6 can be a prospective therapeutic molecule or lead compound for the development of drugs for various VEGF-related angiogenic diseases.
Amino Acid Sequence ; Angiogenesis Inhibitors/*pharmacology ; Animals ; Cell Movement/drug effects ; Cell Proliferation/drug effects ; Colorectal Neoplasms/*pathology/secretion ; Endothelial Cells/cytology/drug effects/enzymology ; Enzyme Activation/drug effects ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Humans ; Mice ; Mice, Nude ; Molecular Sequence Data ; Neovascularization, Pathologic/pathology/prevention & control ; Neovascularization, Physiologic/drug effects ; Peptides/chemistry/*pharmacology ; Protein Multimerization/*drug effects ; Protein Stability/drug effects ; Rats ; Serum ; Vascular Endothelial Growth Factor A/*antagonists & inhibitors/secretion

Mutations or inactivation of parkin, an E3 ubiquitin ligase, are associated with familial form or sporadic Parkinson's disease (PD), respectively, which manifested with the selective vulnerability of neuronal cells in substantia nigra (SN) and striatum (STR) regions. However, the underlying molecular mechanism linking parkin with the etiology of PD remains elusive. Here we report that p62, a critical regulator for protein quality control, inclusion body formation, selective autophagy and diverse signaling pathways, is a new substrate of parkin. P62 levels were increased in the SN and STR regions, but not in other brain regions in parkin knockout mice. Parkin directly interacts with and ubiquitinates p62 at the K13 to promote proteasomal degradation of p62 even in the absence of ATG5. Pathogenic mutations, knockdown of parkin or mutation of p62 at K13 prevented the degradation of p62. We further showed that parkin deficiency mice have pronounced loss of tyrosine hydroxylase positive neurons and have worse performance in motor test when treated with 6-hydroxydopamine hydrochloride in aged mice. These results suggest that, in addition to their critical role in regulating autophagy, p62 are subjected to parkin mediated proteasomal degradation and implicate that the dysregulation of parkin/p62 axis may involve in the selective vulnerability of neuronal cells during the onset of PD pathogenesis.
Adaptor Proteins, Signal Transducing ; chemistry ; metabolism ; Animals ; HEK293 Cells ; Heat-Shock Proteins ; chemistry ; metabolism ; Humans ; Lysine ; metabolism ; Mice ; Neurons ; metabolism ; pathology ; Oxidopamine ; pharmacology ; Parkinson Disease ; metabolism ; pathology ; Proteasome Endopeptidase Complex ; metabolism ; Protein Stability ; Proteolysis ; drug effects ; Sequestosome-1 Protein ; Ubiquitin-Protein Ligases ; metabolism ; Ubiquitination ; drug effects

NDM-1 (New Delhi metallo-beta-lactamase) gene encodes a metallo-beta-lactamase (MBL) with high carbapenemase activity, which makes the host bacterial strain easily dispatch the last-resort antibiotics known as carbapenems and cause global concern. Here we present the bioinformatics data showing an unexpected similarity between NDM-1 and beta-lactamase II from Erythrobacter litoralis, a marine microbial isolate. We have further expressed these two mature proteins in E. coli cells, both of which present as a monomer with a molecular mass of 25 kDa. Antimicrobial susceptibility assay reveals that they share similar substrate specificities and are sensitive to aztreonam and tigecycline. The conformational change accompanied with the zinc binding visualized by nuclear magnetic resonance, Zn(2+)-bound NDM-1, adopts at least some stable tertiary structure in contrast to the metal-free protein. Our work implies a close evolutionary relationship between antibiotic resistance genes in environmental reservoir and in the clinic, challenging the antimicrobial resistance monitoring.
Amino Acid Sequence ; Anti-Bacterial Agents ; pharmacology ; Aztreonam ; pharmacology ; Cephalosporinase ; chemistry ; genetics ; metabolism ; Computational Biology ; methods ; Drug Resistance, Bacterial ; genetics ; Enzyme Stability ; drug effects ; Evolution, Molecular ; Minocycline ; analogs & derivatives ; pharmacology ; Molecular Sequence Data ; Phylogeny ; Protein Structure, Tertiary ; drug effects ; Sequence Homology, Nucleic Acid ; Sphingomonadaceae ; drug effects ; enzymology ; genetics ; Tigecycline ; Zinc ; pharmacology ; beta-Lactamases ; chemistry ; genetics ; metabolism

OBJECTIVETo investigate the possible relationship between defects in the FA/BRCA pathway of genomic stability and potential pathogenesis of T and B cell lymphoma.

METHODSNineteen cell lines derived from diverse subtypes of lymphoma for possible FA pathway defects were screened.

RESULTSNo defect in FANCD2 ubiquitination was observed. However, the FANCN protein was absent in cell lines HT and Sudhl4. This absence was correlated with enhanced MMC-induced G2 arrest, growth inhibition and high chromosomal breakage rate in both cell lines. In addition, in exon-5a of FANCN gene, a mutation of c.1769 C>T, p. A590V was found in cell line HT, but not in cell line Sudhl4.

CONCLUSIONThis mutation may be the reason causing the absence of the FANCN protein expression or making the protein unstable and losing its function.

Animals ; Antibiotics, Antineoplastic ; pharmacology ; BRCA2 Protein ; metabolism ; Base Sequence ; Cell Cycle ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Chromosome Breakage ; drug effects ; Fanconi Anemia ; metabolism ; Fanconi Anemia Complementation Group D2 Protein ; metabolism ; Fanconi Anemia Complementation Group N Protein ; Gene Expression Regulation, Neoplastic ; Genomic Instability ; Humans ; Lymphoma ; genetics ; pathology ; Mitomycin ; pharmacology ; Molecular Sequence Data ; Mutation ; Nuclear Proteins ; chemistry ; deficiency ; genetics ; metabolism ; Protein Stability ; Sequence Analysis, DNA ; Signal Transduction ; Tumor Suppressor Proteins ; chemistry ; deficiency ; genetics ; metabolism

Hu protein R (HuR) binds to the AU-rich element (ARE) in the 3'UTR to stabilize TNF-alpha mRNA. Here, we identified chemical inhibitors of the interaction between HuR and the ARE of TNF-alpha mRNA using RNA electrophoretic mobility gel shift assay (EMSA) and filter binding assay. Of 179 chemicals screened, we identified three with a half-maximal inhibitory concentration (IC(50)) below 10 micrometer. The IC(50) of quercetin, b-40, and b-41 were 1.4, 0.38, and 6.21 micrometer, respectively, for binding of HuR protein to TNF-alpha mRNA. Quercetin and b-40 did not inhibit binding of tristetraprolin to the ARE of TNF-alpha mRNA. When LPS-treated RAW264.7 cells were treated with quercetin and b-40, we observed decreased stability of TNF-alpha mRNA and decreased levels of secreted TNF-alpha. From these results, we could find inhibitors for the TNF-alpha mRNA stability, which might be used advantageously for both the study for post-transcriptional regulation and the discovery of new anti-inflammation drugs.
*3' Untranslated Regions ; Animals ; Anti-Inflammatory Agents/*pharmacology ; Antigens, Surface/metabolism ; Antioxidants/pharmacology ; Cell Line ; Dose-Response Relationship, Drug ; Drug Evaluation, Preclinical ; Mice ; Protein Binding/drug effects ; Quercetin/*pharmacology ; RNA Stability/*drug effects ; RNA-Binding Proteins/*antagonists & inhibitors/metabolism ; Tumor Necrosis Factor-alpha/*biosynthesis