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Peng Liang

Publications and source records attributed to Peng Liang.

34 records · Page 2Linked to original sources
PubMed2004

NDRG1 is necessary for p53-dependent apoptosis.

Although a number of target genes for the tumor suppressor p53 have been described, the mechanism of p53-dependent apoptosis is incompletely understood. Thus, it is essential to identify and characterize additional target genes that could mediate apoptosis. In the study reported here, we isolated a p53-regulated gene named NDRG1 (N-Myc down-regulated gene 1). Its expression is induced by DNA damage in a p53-dependent fashion. The promoter region of the NDRG1 gene contains a p53 binding site that confers p53-dependent transcriptional activation via a heterologous reporter. RNA interference and inducible gene expression approaches suggest that NDRG1 is necessary but not sufficient for p53-mediated caspase activation and apoptosis. This report further supports the notion that p53 controls a network of genes that are required for its apoptotic function.

Amino Acid Sequence↗
PubMed2004

[Labeling neural stem cells with superparamagnetic iron oxide in vitro and tracking after implantation with MRI in vivo].

OBJECTIVE: To evaluate the feasibility of monitoring the neural stem cells implanted into the brain by the technique of labeling with superparamagnetic iron oxide (SPIO). METHODS: Neural stem cells were isolated from the cerebral cortex of newborn Wister rats and cultured. SPIO particles and poly-L-lysine were added into the medium to be co-cultured foe one hour. After the formation of neurospheres, Prussian blue staining was conducted and transmission electron microscopy was used to identify the iron particles in these neural stem cells. Sixteen adult female Wistar rats underwent transplantation of labeled neural stem cells into the right side of brain and non-labeled cells were transplanted into the contralateral part as controls. 1, 2, 4, 6, and 7 weeks after the transplantation, MRI examination with the scanning sequences of SE T2WI, FSE T2WI, and GRE T2 * respectively was conducted on the brains of the rats. Four rats at each time point were killed and their brains were taken out to undergo HE staining and Prussian blue staining to track the presence of labeled-cells. RESULTS: After the addition of SPIO the neurospheres continued to proliferate and differentiate normally. Electron microscopy showed vacuolar structures of different sizes under the cytoplasma membrane within and outside which there were high-density iron particles. Prussian blue staining showed numerous blue stained particles in the cytoplasm of the labeled cells. Remarkable low signal change was seen in the right brain transplanted with labeled cells, especially in the condition of scanning sequence of GRET2. Such change could be seen up to 7 weeks after the transplantation. No signal change was found in the left brain. CONCLUSION: SPIO labeling technique is useful in monitoring the outcome of transplanted neural stem cells.

Animals↗
PubMed2004

Differential expression of pentraxin 3 in fibroblasts from patients with major depression.

In this study, differential display technology was used to compare gene expression in cultured fibroblasts from patients with major depression, melancholic subtype vs nonmelancholic depressives and normal volunteer controls. Genes differentially expressed in depressives and normals included an overexpressed 269 bp sequence tag showing approximately 95% identity with the Homo sapiens long pentraxin 3 (PTX3) gene sequence in the 3' noncoding region. The 269 bp complimentary DNA probe hybridized with the 1.9 kb PTX3 mRNA. The densitometric analysis of slot blots showed that the mean steady-state mRNA level of PTX3 was 3.5-fold higher in the melancholic group as compared to that in normal controls and in nonmelancholic depressives (n=8, all groups). Incubation experiments were then conducted: confluent fibroblasts from melancholics and normal volunteers were incubated with isoproterenol 1 microM, dexamethasone (DEX) 500 nM, and interleukin 1beta (IL-1beta) 50 ng/ml, for 0, 0.5, 1, 4, and 24 h. mRNA was isolated and quantitated using Northern blot analysis. Isoproterenol produced no significant change in PTX3 expression; DEX produced a significant increase at 4 and 24 h; IL-1beta induced an increase in both the groups that peaked at 4 h, declining to near basal levels at 24 h. There were no differences between melancholics or controls in mean change or maximum response with either DEX or IL-1beta. The results are consistent with the reported effects of IL-1beta on PTX3 expression in mouse brain. The results are of potential importance because PTX3 is a member of the long pentraxin subfamily of acute-phase proteins, which is inducible by IL-1beta, and may play roles in neuroimmunity and neuroprotection.

Adrenergic beta-Agonists↗
PubMed2004

Global analysis of gene expression by differential display: a mathematical model.

Differential display (DD) is one of the most commonly used approaches for identifying differentially expressed genes. However, there has been lack of an accurate guidance on how many DD polymerase chain reaction (PCR) primer combinations are needed to display most of the genes expressed in a eukaryotic cell. This study critically evaluated the gene coverage by DD as a function of the number of arbitrary primers, the number of 3' bases of an arbitrary primer required to completely match an mRNA target sequence, the additional 5' base match(s) of arbitrary primers in first-strand cDNA recognition, and the length of mRNA tails being analyzed. The resulting new DD mathematical model predicts that 80 to 160 arbitrary 13mers, when used in combinations with 3 one-base anchored oligo-dT primers, would allow any given mRNA within a eukaryotic cell to be detected with a 74% to 93% probability, respectively. The prediction was supported by both computer simulation of the DD process and experimental data from a comprehensive fluorescent DD screening for target genes of tumor-suppressor p53. Thus, this work provides a theoretical foundation upon which global analysis of gene expression by DD can be pursued.

Algorithms↗
PubMed2004

[Effect of sucrose concentration on the growth and production of secondary metabolites in Pueraria phaseoloides hairy roots].

Effects of sucrose concentrations on the growth and production of puerarin and isoflavones compounds in Pueraria phaseoloides hairy roots induced by Agrobacterium rhizogenes ATCC15834 were investigated. Changes of sucrose consumption in the medium during liquid culture were also determined. The results showed cultured for 16 days in MS medium with 5%, 4%, 3% and 2% sucrose, the proliferation times of dry weight of hairy roots were 11.7, 11.9, 10.1 and 5.9, respectively. 3% sucrose concentration in liquid medium was the best for accumulation of puerarin and isoflavones in the hairy roots. The highest content of puerarin, 5.147 mg/g DW, was obtained after 12 days of liquid culturing while the highest content of isoflavones, about 27.76 mg.g.DW, was gained after 16 days in culturing. Sucrose concentration decreased as hairy root growth proceeded. The growth rate and the content of soluble sugar in hairy roots of P. phaseoloides was directly proportional to the rate of sucrose utilization in the liquid medium during the whole culture. It was observed that the highest content of soluble sugar in hairy roots was at day 12 of liquid culture and sucrose in the liquid medium was used up at the end of 16 days of culture.

Plant Roots↗
PubMed2003

Inclusion complexation behavior of dyestuff guest molecules by a bridged bis(cyclomaltoheptaose)[bis(beta-cyclodextrin)] with a pyromellitic acid diamide tether.

A novel bridged bis(beta-cyclodextrin) with a pyromellitic acid 2,5-diamide tether (2) has been synthesized by reaction of 6(I)-(2-aminoethyleneamino)-6-deoxycyclomaltoheptaose [mono 6-(2-aminoethyleneamino)-6-deoxy-beta-cyclodextrin] with 1,2,4,5-benzenetetracarboxylic dianhydride. Its inclusion complexation behavior with some representative dyestuffs, i.e., Acridine Red (AR), Rhodamine B (RhB), Neutral Red (NR), Brilliant Green (BG), was studied by using UV-absorption, fluorescence, and 2D NMR spectroscopy. Fluorescence titrations have been performed at 25 degrees C in pH 7.2 buffer solution to calculate the binding constants of resulting complexes. These results obtained indicated that bis(beta-cyclodextrin) 2 exhibits the strongly enhanced binding ability with all dye molecules examined compared with natural cyclodextrins. The binding modes of 2 with dye molecules have been deduced by 2D NMR experiments to establish the correlations between molecular conformations and binding constants of inclusion complexation. It is found that the improved binding ability and molecular selectivity of 2 could be attributed to double-cavity cooperative inclusion interaction and the size/shape matching between the host and guest.

Amides↗
PubMed2003

Neuronal and glial differentiation following culture of the human embryonic cortical stem cells.

OBJECTIVE: To set up long-term in vitro culture system of the human neural stem cells (hNSC) and to study their biological properties. METHODS: Human fetuses aged about 20 weeks following spontaneous abortion were adopted. A serum-free medium containing basic fibroblast growth factor and epidermal growth factor was used to make the hNSCs divide continuously in the culture. The growth curve of continually passaged cells was examined. The effects of long-term culture on the cell cycle, cell differentiation were analyzed. The cell cycles of these cells were analyzed using flow cytometry. RESULTS: The cells from the human embryonic cortical tissue could be maintained and propagated in the presence of growth factors. Neurospheres were generated continually. Only one month after the primary culture, the precursors could be effectively discarded. The cells could be cultured for ten months. The cells had an exponential, consistent growth. The cell cycle analysis indicated that the hNSCs maintained remarkable proliferation. Upon differentiation, the hNSCs gave rise to mature cells. The multi-lineage potential of differentiation after different passages remained unchanged. CONCLUSION: The hNSCs isolated from the human embryonic tissues retained their biological features after long-term culture in vitro.

Cell Differentiation↗
PubMed2003

Identification of p53 target genes by fluorescent differential display.

Differential display (DD) is a method used worldwide for identifying differentially expressed genes in eukaryotic cells. The mRNA DD technology works by systematic amplification of the 3' terminal regions of mRNAs. Using anchored primers designed to bind 5' boundary of the polyA tails for reverse transcription, followed by polymerase chain reaction (PCR) amplification with additional upstream primers of arbitrary sequences, mRNA subpopulations are separated by denaturing polyacrylamide electrophoresis. This allows direct side-by-side comparison of most of the mRNAs between or among related cells. Because of its simplicity, sensitivity, and reproducibility, the mRNA DD method is finding wide-ranging and rapid applications in developmental biology, cancer research, neuroscience, pathology, endocrinology, plant physiology, and many other areas. Since the recent development of the fluorescent differential display (FDD), the first nonradioactive DD system with equivalent sensitivity to the original 33P isotopic labeling method, it is now possible with this technology to automate, which can greatly increase the throughput and accuracy of mRNA DD.

Cells, Cultured↗
PubMed2003

[Culture of hairy roots in Pueraria phaseoloides and its puerarin production].

An efficient transformation system for genetic transformation of medicinal plant, Pueraria phaseoloides was developed, by using agropine-type Agrobacterium rhizogenes ATCC15834. Hairy roots could be obtained via callus from the cut edges of leaf explants of P. phaseoloides 20 days after inoculation with agrobacterium. 35 days after infection, the percentage of rooted leaf explants was about 85%. Hairy roots could have an autonomous growth on solid or liquid growth regulator-free MS medium but grew more rapidly and formed no callus during culture in liquid medium. The transformation of hairy roots was confirmed by PCR amplification of rolB and rolC genes of Ri plasmid from A. rhizogenes. To investigate the physiological difference between solid and liquid culture, the mitochondrial membrane potential in hairy roots cultured for 15 days in solid and liquid medium were also detected by the method of fluorescence labeling of 3,3'-dipropylthiadicarbocyanide iodide. The results showed mitochondrial membrane potential of hairy roots in liquid medium was 11.8 times higher than that on solid medium. The content of puerarin in hairy roots reached a level of 1.190 mg/g.dry.wt and was 2.5 times as much as that in the roots of P. phaseoloides seedlings and was also 1.067 times as much as that in the crude drug of several year-old Pueraria roots. Our experiments have laid a foundation for large-scale production of puerarin in P. phaseoloides hairy roots.

Culture Media↗
PubMed2003

[Induction and culture of hairy boots in Phytolacca esculenta and its saponin production].

Hairy roots appeared in vitro 20 days after inoculation of Phytolacca esculenta leaf explants with the strain of Agrobacterium rhizogenes R1601. The frequency of leaf explants transformed by R1601 was up to 70%. Hairy roots can be incited directly from the veins of explants or via callus. Hairy roots induced by R1601 grew rapidly on medium MS without hormone and were 85.6% higher in respiration rate than control roots. Transformation was confirmed by opine detection and the amplification of rol B and rol C genes from the hairy roots of P. esculenta. The total saponin content in hairy roots of P. esculenta was about 1.54 times as much as in natural roots whereas polysaccharides content was about 70% times as much as in the natural roots.

Phytolacca↗
PubMed2002

Systematic analysis of intrinsic factors affecting differential display.

Differential display (DD) is a widely used method for identifying differentially expressed genes. To improve further the efficiency and reproducibility of the method, this report systematically examines four critical parameters of standard DD-PCR. Specifically, the study determined the optimal annealing temperature, elongation time, dNTP concentration, and arbitrary primer concentration. By using a thermal cycler that was capable of displaying a temperature gradient across a PCR plate, it was possible to determine (in a single experiment) the effect of different annealing temperatures. The optimal annealing temperaturefor a 13-mer arbitrary primer fell within a broad range of 40 degrees C-50 degrees C. Elongation times over a range of 30-120 s worked best. The optimal concentration for dNTPs was within a very broad range of 2-50 microM, with higher amounts allowing for greater pipetting accuracy. The most favorable concentration for the arbitrary primer was also within a broad range of 0.1-2.0 microM. A primer concentration below this range greatly reduced the efficiency of the amplification process. In conclusion, the experimental findings delineated the best possible DD conditions for a more reliable assessment of differential gene expression.

Animals↗
PubMed2002

A decade of differential display.

It has been 10 years since the invention of differential display (DD), a conceptually simple methodology that allows the detection and identification of differentially expressed genes. In the past decade, the number of publications describing successful applications of DD has outnumbered those using any other competing methodologies, including subtractive hybridization, representational difference analysis, serial analysis of gene expression, and DNA microarrays. This review will provide a glimpse of the current progress made in DD technological development, refinement, and automation. Excellent examples of DD applications in studying a variety of biological problems, in such diverse biological systems as bacteria, yeast, flies, plants, and higher mammals, are presented to provide a roadmap for those who would like to pursue a fruitful gene "fishing" expedition. Some of the fundamental differences between DD and DNA microarrays are also discussed.

Animals↗
PubMed2001

Interleukin 24 (MDA-7/MOB-5) signals through two heterodimeric receptors, IL-22R1/IL-20R2 and IL-20R1/IL-20R2.

Interleukin 24 (IL-24) encodes a secreted protein that exhibits significant homology to the interleukin 10 (IL-10) family of cytokines. Here we show that the human IL-24 is secreted by activated peripheral blood mononuclear cells and is the ligand for two heterodimeric receptors, IL-22R1/IL-20R2 and IL-20R1/IL-20R2. The latter is also the receptor for IL-20. COS cells transfected with either IL-24 receptor heterodimers bind the ligand with similar saturation kinetics. IL-24 binding to either its endogenous receptors on human keratinocytes or to ectopically expressed receptors on baby hamster kidney cells leads to activation of the signal transducers and activators of transcription. Taken together, these results provide compelling evidence for IL-24 being the fourth member of IL-10 family of cytokines to which their specific receptors have been identified.

Alkaline Phosphatase↗