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Biomedical subjects

Jing Han

Publications and source records attributed to Jing Han.

33 records · Page 2Linked to original sources
PubMed2005

G protein beta2 subunit-derived peptides for inhibition and induction of G protein pathways. Examination of voltage-gated Ca2+ and G protein inwardly rectifying K+ channels.

Voltage-gated Ca2+ channels of the N-, P/Q-, and R-type and G protein inwardly rectifying K+ channels (GIRK) are modulated via direct binding of G proteins. The modulation is mediated by G protein betagamma subunits. By using electrophysiological recordings and fluorescence resonance energy transfer, we characterized the modulatory domains of the G protein beta subunit on the recombinant P/Q-type channel and GIRK channel expressed in HEK293 cells and on native non-L-type Ca2+ currents of cultured hippocampal neurons. We found that Gbeta2 subunit-derived deletion constructs and synthesized peptides can either induce or inhibit G protein modulation of the examined ion channels. In particular, the 25-amino acid peptide derived from the Gbeta2 N terminus inhibits G protein modulation, whereas a 35-amino acid peptide derived from the Gbeta2 C terminus induced modulation of voltage-gated Ca2+ channels and GIRK channels. Fluorescence resonance energy transfer (FRET) analysis of the live action of these peptides revealed that the 25-amino acid peptide diminished the FRET signal between G protein beta2gamma3 subunits, indicating a reorientation between G protein beta2gamma3 subunits in the presence of the peptide. In contrast, the 35-amino acid peptide increased the FRET signal between GIRK1,2 channel subunits, similarly to the Gbetagamma-mediated FRET increase observed for this GIRK subunit combination. Circular dichroism spectra of the synthesized peptides suggest that the 25-amino acid peptide is structured. These results indicate that individual G protein beta subunit domains can act as independent, separate modulatory domains to either induce or inhibit G protein modulation for several effector proteins.

Amino Acid Sequence↗
PubMed2005

Production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from gluconate and glucose by recombinant Aeromonas hydrophila and Pseudomonas putida.

Aeromonas hydrophila 4AK4 and Pseudomonas putida GPp104 were genetically engineered to synthesize poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) using gluconate and glucose rather than fatty acids. A truncated tesA gene, encoding cytosolic thioesterase I of Escherichia coli which catalyzes the conversion of acyl-ACP into free fatty acids, was introduced into A. hydrophila 4AK4. When grown in gluconate, the recombinant A. hydrophila 4AK4 synthesized 10% (w/w) PHBHHx containing 14% (mol/mol) 3-hydroxyhexanoate. If additional PHBHHx synthesis genes, phaPCJ, were over-expressed with the truncated tesA in A. hydrophila 4AK4, the PHBHHx content increased to 15% (w/w) and contained 19% (mol/mol) 3-hydroxyhexanoate. Recombinant P. putida GPp104 harboring phaC encoding PHBHHx synthase of A. hydrophila, phaB encoding acetoacetyl-CoA reductase of Wautersia eutropha and phaG encoding 3-hydroxyacyl-ACP-CoA transferase of P. putida, synthesized 19% (w/w) PHBHHx containing 5% (mol/mol) 3-hydroxyhexanoate from glucose. The results suggest that the engineered pathways were applicable to synthesize PHBHHx from unrelated carbon sources such as gluconate and glucose.

3-Hydroxybutyric Acid↗
PubMed2005

Analysis of target genes induced by IL-13 cytotoxin in human glioblastoma cells.

IL-13 cytotoxin comprised of IL-13 and a mutated form of Pseudomonas exotoxin (fusion protein termed IL-13-PE38QQR) has been shown to inhibit protein synthesis leading to necrotic and apoptotic cell death in glioblastoma cells that express high levels of interleukin-13 receptors (IL-13R). To identify target genes of cell death and other cellular genes with IL-13 receptors in glioblastoma cells, we utilized the cDNA microarrays to analyze global gene expression profiles after IL-13 cytotoxin and IL-13 treatment. IL-13 cytotoxin mediated cytotoxicity to U251 cells in a dose-dependent manner. Hierarchical cluster analysis of differentially expressed genes in U251 glioma cells at different time points after IL-13 cytotoxin treatment showed three major groups, each representing a specific expression pattern. Randomly selected differentially expressed genes from each group were confirmed by RT-PCR analysis. Most down-regulated genes belong to cell adhesion, motility, angiogenesis, DNA repair, and metabolic pathways. While up-regulated genes belong to cell cycle arrest, apoptosis, signaling and various metabolic pathways. Unexpectedly, at early time points, both IL-13 and IL-13 cytotoxin induced several genes belonging to different pathways most notably IL-8, DIO2, END1, and ALDH1A3 indicating that these genes are early response genes and their products may be associated with IL-13R. In addition, IL-13 cytotoxin induced IL-13Ralpha2 mRNA expression during the treatment in glioma cells. Our results indicate that novel cellular genes are involved with IL-13 receptors and that IL-13 cytotoxin induced cell death involves various target genes in human glioblastoma cells. On going studies will determine the role of associated genes and their products in the IL-13R functions in glioma cells.

ADP Ribose Transferases↗
PubMed2005

Novel multiple 5'-amino-modified primer for DNA microarrays.

For DNA microarray analysis, total RNA is reverse-transcribed, labeled by incorporating fluorescent dye into the cDNA, and used to hybridize microarray. This protocol requires a minimum of 20 microg of total RNA. To overcome the sample limitation, an RNA amplification technique has been developed. Although it needs less RNA, this amplification technique is relatively expensive, time consuming, and, unfortunately, has been found to introduce bias. In this study, we designed a novel 5'-amino-modified primer and used it for priming cDNA synthesis. The novel primer has a special structure that contains four Uni-Link molecules with two nucleotide (thymine) residues inserted between them as spacers. This novel primer is used in the reverse-transcription reaction for cDNA synthesis. Using the novel 5'-modified primer combined with indirect labeling method, cDNA probes can be prepared with much less total RNA (5 microg or less) without amplification producing optimal results after hybridization of arrays. This primer can also be used to label nucleotides for other purposes.

Cell Line, Tumor↗
PubMed2005

Development of a focused microarray to assess human embryonic stem cell differentiation.

Human embryonic stem cells (hESC) must be differentiated before clinical use. In addition, the extent of contamination of undifferentiated cells and the efficiency of differentiation must also be assessed prior to clinical application. In this manuscript, we describe the development of a focused microarray that may be used to discriminate between hESC and their differentiated progeny. This array contains 755 genes including embryonic stem cell markers as well as markers of differentiation into neural, mesodermal, and endodermal phenotypes. In addition, we have included candidate genes belonging to families of cytokines, chemokines, receptors, signaling pathways, and homeodomain proteins that are likely to be important in the process of differentiation. Testing and validation of the focused array was performed using RNA from hESC, human embryoid body (hEB) outgrowths, and a human embryonal carcinoma (hEC) cell line. We have compared gene expression with negative background, GAPDH, beta-actin positive controls, and human universal RNA (hURNA), showing that such an array can rapidly distinguish between undifferentiated and differentiated hESC-derived cell populations. We expect that the described array will be extremely useful in evaluating the extent of differentiation and the state of the hESC-derived population utilized for therapeutic purposes.

Cell Differentiation↗
PubMed2005

[Retinoic acid induced cell cycle arrest and apoptosis in mouse embryonic palatal mesenchymal cells].

OBJECTIVES: To investigate the effect of all-trans retinoic acid (atRA) on proliferation activity and cell cycle distribution in mouse embryonic palatal mesenchymal (MEPM) cells and the underlying molecular mechanisms. METHODS: MEPM cells were prepared from palate shelves of mouse fetal on gestation day 13. Cell viability was determined by MTI assay. Cell cycle distribution and subdiploid population were analyzed by cytometry. The expression of cyclin D and E and phosphorylation of retinoblastoma protein was examined using Western-blot. RESULTS: atRA remarkably inhibited the growth of MEPM cells in a dose-dependent manner. atRA also caused an increase in the proportion of cells in G0/G1 and a decrease in the proportion of cells in S phase. atRA inhibited expression of cyclins D and E at protein level. Furthermore, atRA treatment reduced phosphorylated Rb. CONCLUSION: These data suggested that atRA had antiproliferative activity by modulating G1/S cell cycle regulators and by inhibition of Rb phosphorylation in MEPM cells, which might account for the pathogenesis of cleft palate induced by retinoic acid.

Animals↗
PubMed2004

Induction of cell-cycle arrest by all-trans retinoic acid in mouse embryonic palatal mesenchymal (MEPM) cells.

all-trans retinoic acid (atRA), the oxidative metabolite of vitamin A, is essential for normal embryonic development. Also, high levels of atRA are teratogenic in many species and can effectively induce cleft palate in the mouse. Most cleft palate resulted from the failed fusion of secondary palate shelves, and maintenance of the normal cell proliferation is important in this process of shelf growth. To clarify the mechanism by which atRA causes cleft palate, we investigated the effect of atRA on proliferation activity and cell cycle distribution in mouse embryonic palatal mesenchymal (MEPM) cells. atRA inhibited the growth of MEPM cells by inducing apoptosis in a dose-dependent manner. atRA also caused a G1 block in the cell cycle with an increase in the proportion of cells in G0/G1 and a decrease in the proportion of cells in S phase, as determined by flow cytometry. We next investigated the effects of atRA on molecules that regulate the G1 to S phase transition. These studies demonstrated that atRA inhibited expression of cyclins D and E at the protein level. Furthermore, atRA treatment reduced phosphorylated Rb and decreased cdk2 and cdk4 kinase activity. These data suggest that atRA had antiproliferative activity by modulating G1/S cell cycle regulators and by inhibition of Rb phosphorylation in MEPM cells, which might account for the pathogenesis of cleft palate induced by retinoic acid.

Animals↗
PubMed2004

Engineered Aeromonas hydrophila for enhanced production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) with alterable monomers composition.

Aeromonas hydrophila 4AK4 produces poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) containing 3-hydroxybutyrate (3HB) and about 15 mol% 3-hydroxyhexanoate (3HHx) from dodecanoate. To study the factors affecting the monomer composition and PHBHHx content, genes encoding phasin (phaP), PHA synthase (phaC) and (R)-specific enoyl-CoA hydratase (phaJ) from Aeromonas punctata (formerly named Aeromonas caviae) were introduced individually or jointly into A. hydrophila 4AK4. The phaC gene increased 3HHx fraction more significantly than phaP, while phaJ had little effect. Expression of phaC alone increased the 3HHx fraction from 14 to 22 mol%. When phaC was co-expressed with phaP and phaJ, the 3HHx fraction increased from 14 to 34 mol%. Expression of phaP or phaC alone or with another gene enhanced PHBHHx content up to 64%, cell dry weight (CDW) as much as 4.4 gL(-1) and PHBHHx concentration to 2.7 gL(-1) after 48 h in shake flask culture. The results suggest that a higher PHA synthase activity could lead to a higher 3HHx fraction and PHBHHx content. Co-expression of phaJ with phaC or phaP would favor PHA accumulation, although over-expression of phaJ did not affect PHA synthesis much. In addition, inhibition of beta-oxidation by acrylate in A. hydrophila 4AK4 enhanced PHBHHx content. However, no monomers longer than 3HHx were detected. The results show that genetic modification of A. hydrophila 4AK4 enhanced PHBHHx production and altered monomer composition of the polymer.

3-Hydroxybutyric Acid↗
PubMed2004

[Preparation of the 5-Fu floating sustained release tablet for gastric retention].

OBJECTIVE: To develop a pH independent floating sustained release tablet for gastric retention using 5-Fluorouracil (5-Fu) as a model drug. METHODS: According to the theory of the Hydro-dynamically Balanced System, the granules for the floating and drug loading layer were prepared separately and pressed together to make two-layer floating tablets for gastric retention. The floating kinetics indexes were measured and the data about drug release studied with media of different pH values. RESULTS: An excellent floating ability was observed in the media of different acidity for the gastric retentive tablet prepared according to the optimum formulation. The in vitro drug release can be modified by the regulation of the formulation ingredients. At the rotating speed of 100 r/min and in 0.1 mol/L HCl, the drug release was found to conform to first-class dynamics rule. CONCLUSION: The two-layer floating tablet made in this experiment,whose floating ability is independent of the gastric acidity variation, is of the possibility to be used for the auxiliary treatment of gastric carcinoma because of its prolonged gastric retention.

Antimetabolites, Antineoplastic↗
PubMed2004

Endoplasmic reticulum stress as a correlate of cytotoxicity in human tumor cells exposed to diindolylmethane in vitro.

The dietary phytochemical indole-3-carbinol (I3C) protects against cervical cancer in animal model studies and in human clinical trials. I3C and its physiologic condensation product diindolylmethane (DIM) also induce apoptosis of tumor cells in vitro and in vivo, suggesting that these phytochemicals might be useful as therapeutic agents as well as for cancer prevention. Deoxyribonucleic acid microarray studies on transformed keratinocytes and tumor cell lines exposed to pharmacologic concentrations of DIM in vitro are consistent with a cellular response to nutritional deprivation or disruptions in protein homeostasis such as endoplasmic reticulum (ER) stress. In this report we investigate whether specific stress response pathways are activated in tumor cells exposed to DIM and whether the ER stress response might contribute to DIM's cytotoxicity. Induction of the stress response genes GADD153, GADD34 and GADD45A, XBP-1, GRP78, GRP94, and asparagine synthase was documented by Western blot and real-time reverse transcriptase-polymerase chain reaction in C33A cervical cancer cells, and induction of a subset of these was also observed in cancer cell lines from breast (MCF-7) and prostate (DU145). The results are consistent with activation of more than 1 stress response pathway in C33A cells exposed to 75 microM DIM. Phosphorylation elF2alpha was rapidly and transiently increased, followed by elevated levels of ATF4 protein. Activation of IRE1alpha was indicated by a rapid increase in the stress-specific spliced form of XBP-1 messenger ribonucleic acid and a rapid and persistent phosphorylation of JNK1 and JNK2. Transcriptional activation dependent on an ATF6-XBP-1 binding site was detected by transient expression in MCF-7, C33A, and a transformed epithelial cell line (HaCaT); induction of the GADD153 (CHOP) promoter was also confirmed by transient expression. Cleavage of caspase 12 was observed in both DIM-treated and untreated C33A cells but did not correlate with cytotoxicity, whereas caspase 7 was cleaved at later times, coinciding with the onset of apoptosis. The results support the hypothesis that cytotoxic concentrations of DIM can activate cellular stress response pathways in vitro, including the ER stress response. Conversely, DIM was especially cytotoxic to stressed cells. Thapsigargin and tunicamycin, agents that induce ER stress, sensitized cells to the cytotoxic effects of DIM to differing degrees; nutrient limitation had a similar, but even more pronounced, effect. Because DIM toxicity in vitro is enhanced in cells undergoing nutritional deprivation and ER stress, it is possible that stressed cells in vivo, such as those within developing solid tumors, also have increased sensitivity to killing by DIM.

Activating Transcription Factor 4↗
PubMed2004

[Effect of puerarin and daidzein on proliferating vascular smooth muscle cells].

OBJECTIVE: To observe the different effects of Puerarin and Daidzein on the expression of proliferating vascular smooth muscle cells, and to discuss the mechanism. METHOD: MT was used to detect the state of VSMC (vascular smooth muscle cell) activity. The expression levels of Survivin, Bcl-xl, Bax and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) messenger RNA (mRNA) were analyzed quantitatively by reverse transcriptase polymerase chain reaction (Rt-PCR). RESULT: Compared with Puerarin groups, VSMC activity in daidzein groups was lower, and the ratio of Bax/Gapdh/Bcl-xl/Gapdh was higher. CONCLUSION: The inhibition effect of daidzein on VSMC proliferation is stronger than that of puerarin.

Cells, Cultured↗
PubMed2003

Coupling development and elution, a new thin-layer chromatography technique.

Three methods of coupling development and elution were studied in this paper. (1) A new mode of solvent supplementation and eluate collection was developed for descending development. By using a new distributor and collector in descending development, components can be separated and eluted continuously. (2) The same effect can be realized with a slope distributor [Su et al., J. Planar Chromatogr. 14 (2001) 203] and a collector by horizontal development. (3) In-situ elution can be used to treat a developed silica plate, which can elute the separated components to the receptor without scraping them off. These three methods can be used individually, and the in-situ elution can be used with other modes of development.

Chromatography, Thin Layer↗
PubMed2003

Leukemia inhibitory factor is a key signal for injury-induced neurogenesis in the adult mouse olfactory epithelium.

The mammalian olfactory epithelium (OE) is composed of primary olfactory sensory neurons (OSNs) that are renewed throughout adulthood by local, restricted neuronal progenitor cells. The molecular signals that control this neurogenesis in vivo are unknown. Using olfactory bulb ablation (OBX) in adult mice to trigger synchronous mitotic stimulation of neuronal progenitors in the OE, we show the in vivo involvement of a cytokine in the cellular events leading to the regeneration of the OE. We find that, of many potential mitogenic signals, only leukemia inhibitory factor (LIF) is induced before the onset of neuronal progenitor proliferation. The rise in LIF mRNA expression peaks at 8 hr after OBX, and in situ RT-PCR and immunocytochemistry indicate that LIF is upregulated, in part, in the injured neurons themselves. This rise in LIF is necessary for injury-induced neurogenesis, as OBX in the LIF knock-out mouse fails to stimulate cell proliferation in the OE. Moreover, delivery of exogenous LIF to the intact adult OE using an adenoviral vector stimulates BrdU labeling in the apical OE. Taken together, these results suggest that injured OSNs release LIF as a stimulus to initiate their own replacement.

Animals↗
PubMed2003

Targeting mechanisms of high voltage-activated Ca2+ channels.

Functional voltage-dependent Ca2+ channel complexes are assembled by three to four subunits: alpha1, beta, alpha2delta subunits (C. Leveque et al., 1994, J. Biol Chem. 269, 6306-6312; M. W. McEnery et al., 1991, Proc. Natl. Acad. Sci. U.S.A. 88, 11095-11099) and at least in muscle cells also y subunits (B. M. Curtis and W. A. Catterall, 1984, Biochemistry 23, 2113-2118). Ca2+ channels mediate the voltage-dependent Ca2+ influx in subcellular compartments, triggering such diverse processes as neurotransmitter release, dendritic action potentials, excitation-contraction, and excitation-transcription coupling. The targeting of biophysically defined Ca2+ channel complexes to the correct subcellular structures is, thus, critical to proper cell and physiological functioning. Despite their importance, surprisingly little is known about the targeting mechanisms by which Ca2+ channel complexes are transported to their site of function. Here we summarize what we know about the targeting of Ca2+ channel complexes through the cell to the plasma membrane and subcellular structures.

Amino Acid Sequence↗