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Biomedical subjects

Jun Cheng

Publications and source records attributed to Jun Cheng.

At least 19 recordsLinked to original sources
PubMed2006

Screening of genes for proteins interacting with the PS1TP5 protein of hepatitis B virus: probing a human leukocyte cDNA library using the yeast two-hybrid system.

BACKGROUND: The hepatitis B virus (HBV) genome includes S, C, P and X regions. The S region is divided into four subregions of pre-pre-S, pre-S1, pre-S2 and S. PS1TP5 (human gene 5 transactivated by pre-S1 protein of HBV) is a novel target gene transactivated by the pre-S1 protein that has been screened with a suppression subtractive hybridization technique in our laboratory (GenBank accession: AY427953). In order to investigate the biological function of the PS1TP5 protein, we performed a yeast two-hybrid system 3 to screen proteins from a human leukocyte cDNA library interacting with the PS1TP5 protein. METHODS: The reverse transcription polymerase chain reaction (RT-PCR) was performed to amplify the gene of PS1TP5 from the mRNA of HepG2 cells and the gene was then cloned into the pGEM-T vector. After being sequenced and analyzed with Vector NTI 9.1 and NCBI BLAST software, the target gene of PS1TP5 was cut from the pGEM-T vector and cloned into a yeast expression plasmid pGBKT7, then "bait" plasmid pGBKT7-PS1TP5 was transformed into the yeast strain AH109. The yeast protein was isolated and analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting hybridization. After expression of the pGBKT7-PS1TP5 fusion protein in the AH109 yeast strain was accomplished, a yeast two-hybrid screening was performed by mating AH109 with Y187 containing a leukocyte cDNA library plasmid. The mated yeast was plated on quadruple dropout medium and assayed for alpha-gal activity. The interaction between the PS1TP5 protein and the proteins obtained from positive colonies was further confirmed by repeating the yeast two-hybrid screen. After extracting and sequencing of plasmids from blue colonies we carried out a bioinformatic analysis. RESULTS: Forty true positive colonies were selected and sequenced, full length sequences were obtained and we searched for homologous DNA sequences from GenBank. Among the 40 positive colonies, 23 coding genes with known functions were obtained, including Homo sapien leukocyte adhesion protein p150, 95, interleukin 2 receptor gamma chain, PALM2-AKAP2 protein (PALM2-AKAP2), eukaryotic translation initiation factor 4A, beta-2-microglobin, solute carrier family 9 (sodium/hydrogen exchanger), calreticulin, asialoglycoprotein receptor 1 (ASGR1), MHC class II lymphocyte antigen, cytochrome c oxidase subunit 1, lymphocyte antigen 86 (LY86) and lymphocyte cytosolic protein 1. One novel gene with unknown function was found and named as PS1TP5BP1. After being electronically spliced, it was deposited in GenBank (accession number: DQ471327). CONCLUSIONS: Genes of proteins interacting with PS1TP5 were successfully screened from leukocyte cDNA library. These results suggested that PS1TP5 was closely correlated with immunoregulation, carbohydrate metabolism, signal transduction, the formation of hepatic fibrosis and initiation and development of tumors and also brought some new clues for further studying the biological functions of the pre-S1 protein.

Amino Acid Sequence↗
PubMed2006

Foxo transcription factors blunt cardiac hypertrophy by inhibiting calcineurin signaling.

BACKGROUND: Cellular hypertrophy requires coordinated regulation of progrowth and antigrowth mechanisms. In cultured neonatal cardiomyocytes, Foxo transcription factors trigger an atrophy-related gene program that counters hypertrophic growth. However, downstream molecular events are not yet well defined. METHODS AND RESULTS: Here, we report that expression of either Foxo1 or Foxo3 in cardiomyocytes attenuates calcineurin phosphatase activity and inhibits agonist-induced hypertrophic growth. Consistent with these results, Foxo proteins decrease calcineurin phosphatase activity and repress both basal and hypertrophic agonist-induced expression of MCIP1.4, a direct downstream target of the calcineurin/NFAT pathway. Furthermore, hearts from Foxo3-null mice exhibit increased MCIP1.4 abundance and a hypertrophic phenotype with normal systolic function at baseline. Together, these results suggest that Foxo proteins repress cardiac growth at least in part through inhibition of the calcineurin/NFAT pathway. Given that hypertrophic growth of the heart occurs in multiple contexts, our findings also suggest that certain hypertrophic signals are capable of overriding the antigrowth program induced by Foxo. Consistent with this, multiple hypertrophic agonists triggered inactivation of Foxo proteins in cardiomyocytes through a mechanism requiring the PI3K/Akt pathway. In addition, both Foxo1 and Foxo3 are phosphorylated and consequently inactivated in hearts undergoing hypertrophic growth induced by hemodynamic stress. CONCLUSIONS: This study suggests that inhibition of the calcineurin/NFAT signaling cascade by Foxo and release of this repressive action by the PI3K/Akt pathway are important mechanisms whereby Foxo factors govern cell growth in the heart.

Angiotensin II↗
PubMed2006

Design, synthesis, and antifungal activities in vitro of novel tetrahydroisoquinoline compounds based on the structure of lanosterol 14alpha-demethylase (CYP51) of fungi.

Novel tetrahydroisoquinoline compounds were designed by coupling structure-based de novo design based on the structure of lanosterol 14alpha-demethylase (CYP51). The chemical synthesis and the antifungal activities in vitro of them were reported. The results exhibited that all of the lead compounds showed potent antifungal activities, in which compounds 6 and 7 had equal or stronger antifungal activities against five test fungi than that of fluconazole. The studies presented here provided the antifungal lead compounds. The affinity of the lead molecules for CYP51 was mainly attributed to their non-bonding interaction with the apoprotein, which was different from the azole antifungal agents.

Antifungal Agents↗
PubMed2006

Connexin 26 regulates epidermal barrier and wound remodeling and promotes psoriasiform response.

Inflammatory skin disorders result in significant epidermal changes, including keratinocyte hyperproliferation, incomplete differentiation, and impaired barrier. Here we test whether, conversely, an impaired epidermal barrier can promote an inflammatory response. Mice lacking the transcription factor Kruppel-like factor 4 (Klf4) have a severe defect in epidermal barrier acquisition. Transcription profiling of Klf4(-/-) newborn skin revealed similar changes in gene expression to involved psoriatic plaques, including a significant upregulation of the gap junction protein connexin 26 (Cx26). Ectopic expression of Cx26 from the epidermis-specific involucrin (INV) promoter (INV-Cx26) demonstrated that downregulation of Cx26 is required for barrier acquisition during development. In juvenile and adult mice, persistent Cx26 expression kept wounded epidermis in a hyperproliferative state, blocked the transition to remodeling, and led to an infiltration of immune cells. Mechanistically, ectopic expression of Cx26 in keratinocytes resulted in increased ATP release, which delayed epidermal barrier recovery and promoted an inflammatory response in resident immune cells. These results provide a molecular link between barrier acquisition in utero and epidermal remodeling after wounding. More generally, these studies suggest that the most effective treatments for inflammatory skin disorders might concomitantly suppress the immune response and enhance epidermal differentiation to restore the barrier.

Animals↗
PubMed2006

Remodeling of early-phase repolarization: a mechanism of abnormal impulse conduction in heart failure.

BACKGROUND: The early phase of action potential (AP) repolarization is critical to impulse conduction in the heart because it provides current for charging electrically coupled cells. In the present study we tested the impact of heart failure-associated electrical remodeling on AP propagation. METHODS AND RESULTS: Subepicardial, midmyocardial, and subendocardial myocytes were enzymatically dissociated from control and pressure-overload failing left ventricle (LV), and APs were recorded. A unique coupling-clamp technique was used to electrically couple 2 isolated myocytes with a controlled value of coupling conductance (Gc). In sham-operated mice, AP duration manifested a clear transmural gradient, with faster repolarization in subepicardial myocytes than in subendocardial myocytes. AP propagation from subendocardial to subepicardial myocytes required less Gc compared with conduction in the opposite direction. In failing heart, AP morphology was dramatically altered, with a significantly elevated plateau potential and prolonged AP duration. Spatially nonuniform alteration of AP duration in failing heart blunted the transmural gradient of repolarization. Furthermore, increased pacing rate prolonged AP duration exclusively in myocytes from failing heart, and the critical conductance required for successful AP propagation decreased significantly at high frequencies. Finally, in failing heart, asymmetry of transmural electrical propagation was abolished. CONCLUSIONS: In failing heart, preferential conduction from subendocardial to subepicardial myocytes is lost, and failing myocytes manifest facilitated AP propagation at fast rates. Together, these electrical remodeling responses may promote conduction of premature impulses and heighten the risk of malignant arrhythmia, a prominent feature of heart failure.

Action Potentials↗
PubMed2006

Progressive vascular smooth muscle cell defects in a mouse model of Hutchinson-Gilford progeria syndrome.

Children with Hutchinson-Gilford progeria syndrome (HGPS) suffer from dramatic acceleration of some symptoms associated with normal aging, most notably cardiovascular disease that eventually leads to death from myocardial infarction and/or stroke usually in their second decade of life. For the vast majority of cases, a de novo point mutation in the lamin A (LMNA) gene is the cause of HGPS. This missense mutation creates a cryptic splice donor site that produces a mutant lamin A protein, termed "progerin," which carries a 50-aa deletion near its C terminus. We have created a mouse model for progeria by generating transgenics carrying a human bacterial artificial chromosome that harbors the common HGPS mutation. These mice develop progressive loss of vascular smooth muscle cells in the medial layer of large arteries, in a pattern very similar to that seen in children with HGPS. This mouse model should prove valuable for testing experimental therapies for this devastating disorder and for exploring cardiovascular disease in general.

Animals↗
PubMed2006

Screening and identification of interacting proteins with hepatitis B virus core protein in leukocytes and cloning of new gene C1.

AIM: To investigate the biological function of HBcAg in pathogenesis of HBV replication in peripheral blood mononuclear cells (PBMCs). METHODS: HBcAg region was amplified by polymerase chain reaction (PCR) and HBV HBcAg bait plasmid pGBKT7-HBcAg was constructed by routine molecular biological methods. Then the recombinant plasmid DNA was transformed into yeast AH109. After the HBV core protein was expressed in AH109 yeast strains (Western blot analysis), yeast-two hybrid screening was performed by mating AH109 with Y187 containing leukocyte cDNA library plasmid. Diploid yeast cells were plated on synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) (QDO) and synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) (TDO). The second screening was performed with the LacZ report gene ( yeast cells were grown in QDO medium containing X-alpha-gal). The interaction between HBV core protein and the protein obtained from positive colonies was further confirmed by repeating yeast-two hybrid. After plasmid DNA was extracted from blue colonies and sequenced, the results were analyzed by bioinformatic methods. RESULTS: Eighteen colonies were obtained and sequenced, including hypermethylated in cancer 2 (3 colones), eukaryotic translation elongation factor 2 (2 colones), acetyl-coenzyme A synthetase 3 (1 colone), DNA polymerase gamma (1 colone), putative translation initiation factor (1 colone), chemokine (C-C motif) receptor 5 (1 colone), mitochondrial ribosomal protein L41 (1 colone), kyot binding protein genes (1 colone), RanBPM (1 colone), HBeAg-binding protein 3 (1 colone), programmed cell death 2 (1 colone). Four new genes with unknown function were identified. CONCLUSION: Successful cloning of genes of HBV core protein interacting proteins in leukocytes may provide some new clues for studying the biological functions of HBV core protein.

Amino Acid Sequence↗
PubMed2006

Genetic evidence does not support direct regulation of EDNRB by SOX10 in migratory neural crest and the melanocyte lineage.

Mutations in the transcription factor Sox10 or Endothelin Receptor B (Ednrb) result in Waardenburg Syndrome Type IV (WS-IV), which presents with deficiencies of neural crest derived melanocytes (hypopigmentation) and enteric ganglia (hypoganglionosis). As Sox10 and Ednrb are expressed in mouse migratory neural crest cells and melanoblasts, we investigated the possibility that SOX10 and EDNRB function through a hierarchical relationship during melanocyte development. However, our results support a distinct rather than hierarchical relationship. First, SOX10 expression continues in Ednrb null melanoblasts, demonstrating that SOX10 expression is not dependent on EDNRB function. Second, Ednrb expression persists in E10.5 Sox10null embryos, demonstrating that Ednrb is not dependent on SOX10 for expression in migratory neural crest cells. Third, over-expression of SOX10 in melanoblasts of mice that harbor null or hypomorphic Ednrb alleles does not rescue hypopigmentation, suggesting that SOX10 overexpression can neither complement a lack of EDNRB function nor increase Ednrb expression. Fourth, mice that are double heterozygous for loss-of-function mutations in Sox10 and Ednrb do not demonstrate synergistically increased hypopigmentation compared to mice that are single heterozygotes for either mutation alone, suggesting a lack of direct genetic interaction between these genes. Our results suggest that SOX10 does not directly activate Ednrb transcription in the melanocyte lineage. Given that SOX10 directly activates Ednrb in the enteric nervous system, our results suggest that SOX10 may differentially activate target genes based on the particular cellular context.

Animals↗
PubMed2006

Horseradish peroxidase immobilized on aluminium-pillared inter-layered clay for the catalytic oxidation of phenolic wastewater.

Horseradish peroxidase (HRP) was successfully immobilized on aluminum-pillared inter-layered clay (Al-PILC) to obtain enzyme-clay complex for the treatment of wastewater polluted with phenolic compounds. The immobilized HRP exerted a perfect phenol removal by precipitation or transforming to other products over a broader pH range from 4.5 to 9.3. The addition of polyethylene glycol (PEG) could significantly enhance the phenol removal efficiency, and reduce the amount of immobilized enzyme required to achieve a high removal efficiency of over 90%. When the mass ratio of PEG/phenol and the molar ratio of hydrogen peroxide/phenol were 0.4 and 1.5, respectively, the oxidation of phenol could be completed within short retention time after the initiation of reaction in the absence of buffer. HRP immobilized on Al-PILC had better storage stability compared with free enzyme. However, the re-usability of the immobilized enzyme was not very satisfactory. In the fourth repeated test, the immobilized enzyme lost its catalytic performance. Further research should focus on the improvement of re-usability.

Aluminum↗
PubMed2006

Transient-outward K+ channel inhibition facilitates L-type Ca2+ current in heart.

BACKGROUND: Transient outward current (I(to)) and L-type calcium current (I(Ca)) are important repolarization currents in cardiac myocytes. These two currents often undergo disease-related remodeling while other currents are spared, suggesting a functional coupling between them. Here, we investigated the effects of I(to) channel blockers, 4-aminopyridine (4-AP) and heteropodatoxin-2 (HpTx2), on I(Ca) in cardiac ventricular myocytes. METHODS AND RESULTS: I(Ca) was recorded in enzymatically dissociated mouse and guinea pig ventricular myocytes using the whole-cell voltage clamp method. In mouse ventricular myocytes, 4-AP (2 mM) significantly facilitated I(Ca) by increasing current amplitude and slowing inactivation. These effects were not voltage-dependent. Similar facilitating effects were seen when equimolar Ba2+ was substituted for external Ca2+, indicating that Ca2+ influx is not required. Measurements of Ca2+/calmodulin-dependent protein kinase (CaMKII) activity revealed significant increases in cells treated with 4-AP. Pretreatment of cells with 10 microM KN93, a specific inhibitor of CaMKII, abolished the effects of 4-AP on I(Ca.) To test the requirement of I(to), we studied guinea pig ventricular myocytes, which do not express I(to) channels. In these cells, 2 mM 4-AP had no effect on I(Ca) amplitude or kinetics. In both cell types, Ca2+-induced I(Ca) facilitation, a CaMKII-dependent process, was observed. However, 4-AP abolished Ca2+-induced I(Ca) facilitation exclusively in mouse ventricular myocytes. CONCLUSION: 4-AP, an I(to) blocker, facilitates L-type Ca2+ current through a mechanism involving the I(to) channel and CaMKII activation. These data indicate a functional association of I(Ca) and I(to) in cardiac myocytes.

4-Aminopyridine↗
PubMed2006

Calcium channel blocking activity of calycosin, a major active component of Astragali Radix, on rat aorta.

AIM: To investigate the vasoactivity of calycosin, a major active component of Astragali Radix. METHODS: Experiments were performed on isolated rat thoracic aortic rings pre-contracted with phenylephrine (PHE) or KCl. RESULTS: Calycosin produced a concentration-dependent relaxation on the tissue pre-contracted using PHE with 4.46+/-0.13 of pD(2) and 95.85%+/-2.67% of E(max); or using KCl with 4.27+/-0.05 of pD2 and 99.06%+/-2.15% of Emax, and displaced downwards the concentration-response curves of aortic rings to PHE or KCl. The relaxant effect of calycosin on denuded endothelium aortic rings was the same as on intact endothelium aortic rings, and its vasorelaxant effect was not influenced by L-NAME or indomethacin. In Ca(2+)-free solution, calycosin (30 micromol/L) did not have an effect on PHE (1 micromol/L)-induced aortic ring contraction. The effects of calycosin and nifedipine where somewhat different; calycosin decreased aortic ring contractions induced by the two agonists, but nifedipine displayed a more potent inhibitory effect on KCl-induced contractions than on PHE-induced contractions, and the vascular relaxing effects of calycosin and nifidipine were additive on PHE-induced contraction but not KCl-induced. CONCLUSION: Calycosin is a vasorelaxant. Its action is endothelium-independent and is unrelated to intracellular Ca(2+) release. It is a noncompetitive Ca(2+) channel blocker. The effect of calycosin on Ca(2+) channel blockade may be different from that of dihydropyridines. This study demonstrated a novel pharmacological activity of calycosin, and supplied a theoretic foundation for Astragali Radix application.

Animals↗
PubMed2006

[Study on quasispecies of hepatitis B virus and the clinical manifestation of their infection by melt curve analysis].

OBJECTIVES: To study the relationship between quasispecies of hepatitis B virus and the clinical manifestations of their infection, and to find the answer of why different quasispecies of HBV with the same genotype can induce different clinical situations. METHODS: Sixty serum samples, in all of which HBVs of genotype B exist, taken from 32 chronic asymptomatic carriers and 28 severe chronic hepatitis patients, were collected to detect quasispecies of HBV DNA by melt curve approach. Then the relationship between quasispecies of HBV of the same genotype and the clinical situation of their infection was studied by comparing the wave crests of the two sample groups. RESULTS: The data of the 60 serum samples of HBV of genotype B detected by melt curve showed that HBV DNA in severe chronic hepatitis patients had more wave crests than that in chronic asymptomatic carriers (P < 0.05), suggesting that HBV in severe chronic hepatitis patients had more quasispecies than in the chronic asymptomatic carriers. CONCLUSION: The numbers of quasispecies of HBV correlate with the clinical situations of their infection. In the patients infected by HBV of the same genotype, those who have more HBV quasispecies would have more severe clinical manifestations.

Adolescent↗
PubMed2006

[Identification and evaluation promoter sequence and the transcription activation of Hcbp6 interaction with core protein of hepatitis C virus].

OBJECTIVE: To clarify the expression and regulation mechanism of the new target gene (human hepatitis C virus binding protein 6, Hcbp6) interaction with the core protein of hepatitis C virus (HCV). METHODS: Referring to the prediction online of the promoter region, 3256 base pairs (bp) upstream and downstream of the translation start site were selected as 5 putative promoter sequences which were amplified from the hepatoblastoma cell line-HepG2 cell genomic DNA by polymerase chain reaction (PCR). The amplified products were cloned into a pCAT3 vector. The HepG2 and NIH3T3 cell lines were transfected by pCAT3-Hcbp6-promoters. The CAT activity was detected using an enzyme-linked immunoassay (ELISA) kit. RESULTS: We found that 2 kinds of pCAT3-Hcbp6-promoters (1066 and 240) could direct the reporter gene expression. The expression of CAT was 3.1 times and 6.4 times higher than that of the pCAT3-basic control vector. CONCLUSION: These results indicated that pCAT3-Hcbp6-promoters have promoter activity.

3T3 Cells↗
PubMed2006

[The association of cardiovascular risk factors and prevalence of carotid atherosclerosis at 10 years].

OBJECTIVE: To explore the association of cardiovascular disease (CVD) risk factors and its impact on the 10-year prevalence of carotid atherosclerosis. METHODS: Two surveys for CVD risk factors were carried out in a population consisting of 1323 subjects in Beijing in both 1992 and 2002 and a direct measurement of carotid arteries with B-mode ultrasound imaging were performed in 2002. Intima-media thickness (IMT) and plaque of carotid arteries were regarded as the indicators of carotid atherosclerosis and main CVD risk factors were treated as the impact factors. RESULTS: (1) 10-year prevalence of carotid atherosclerosis continually increased with elevated baseline risk factors levels. Age, smoking, hypertension and hypercholesterolemia were found to be independently associated with carotid atherosclerosis. (2) 10-year prevalence of carotid atherosclerosis increased with the elevated number of risk factors clustering in individuals. (3) The prevalence of IMT and plaque were 67.1% and 42.6% in subjects with CVD risk factors in both 1992 and 2002 surveys with Odds Ratios being 1.7 and 3.1 times as those without risk factors. CONCLUSION: Traditional CVD risk factors exert impact on CVD and carotid atherosclerosis with different degrees and carotid atherosclerosis can be regarded as an early evaluation indicator for risk of atherosclerotic diseases.

Aged↗