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Biomedical subjects

Yun Feng

Publications and source records attributed to Yun Feng.

At least 37 records · Page 2Linked to original sources
PubMed2005

[Production of HMGN2 polyclonal antibody by immunization with recombinant GST-HMGN2 fusion protein and its application to analysis of HMGN2 distribution in human monocytes].

OBJECTIVE: To prepare high mobility group chromosomal protein N2 (HMGN2) polyclonal antibodies and determine the subcellular localization of HMGN2 in human monocytes. METHODS: The recombinant prokaryotic expression vector pGEX-1lambdaT-HMGN2 was constructed and E. coli-based product of GST-HMGN2 fusion protein was prepared and used to immunize rabbit for producing the anti-serum against HMGN2. The polyclonal antibodies were partially purified by caprylic acid and ammonium sulfate precipitation. The titter of specific polyclonal antibodies against HMGN2 was detected by ELISA. The immunocytochemical staining was performed to determine the distribution of HMGN2 in THP-1 cells. RESULTS: Gel electrophoresis of the enzyme-digested recombinant plasmid and the DNA sequencing confirmed that the recombinant prokaryotic expression vector pGEX-1lambdaT-HMGN2 was correctly constructed. After IPTG induction, the recombinant-transformed E. coli produced a bulk of GST-HMGN2 fusion protein. The polyclonal antibodies to HMGN2 was obtained from the serum of rabbit immunized with GST-HMGN2 fusion protein and its ELISA titer was 1:2000. The immunocytochemistry staining indicated that when stimulated with LPS, HMGN2 was present not only in THP-1 nucleus but also in the cytoplasm. The presence of HMGN2 was also detected in the culture supernatant. CONCLUSION: This result suggests that recombinant peptide fusion protein could be used to produce peptide antibody. HMGN2 could be present in the cytoplasm of monocytes and release to the extracellular environment when stimulated with lipopolysaccharide (LPS).

Animals↗
PubMed2005

[E. coli-based production of recombinant HMG-17 and its antibacterial domain].

Total RNA was extracted from human LAK cell, and a cDNA encoding mature peptide HMG-17 and its alpha helix domain was amplified by RT-PCR. The recombinant prokaryotic expression vector pGEX-1lambdaT-HMG-17 and pGEX-1lambdaT HMG-17alpha helix was constructed. Using affinity chromatography, thrombin cleaving and AU-PAGE elution, we obtained the purified HMG-17. Analyses of MIC, MEC and MBC indicated that HMG-17 and HMG-17alpha had strong antibacterial activity. MIC of the alpha-helic domain was almost the same as that of HMG17, suggesting that the alpha-helic structure would be essential for the antibacterial activity of HMG-17.

Anti-Bacterial Agents↗
PubMed2005

[Application of HMGN2-tag constructs to analysis of HMGN2 distribution in HeLa cells].

This study sought to clarify the distribution of HMGN2 in HeLa cells. The recombinant eukaryotic expression vectors pcDNA3. 1-myc-his-HMGN2 and pEGFP-N1-HMGN2 were constructed, and then were transfected into HeLa cells. immunocytochemistry staining indicated that HMGN2 were present not only in HeLa nucleus but also in the cytoplasm. The presence of HMGN2 was also detected in the culture supernatant by ELISA with rabbit anti-serum against HMGN2 and mouse anti-His6 monoclonal antibodies. The confocal microscope observation showed the same subcellular localization as that of immunocytochemistry staining. There results suggested that HMGN2 could be present in the nucleus and cytoplasm of HeLa cell as well as in the extracellular environment.

Animals↗
PubMed2005

Vasorelaxant responses to endomorphin1[psi] and endomorphin2[psi], analogues of endomorphins, in rat aorta rings.

Endomorphin-1 (Tyr-Pro-Trp-Phe-NH2, EM1) and endomorphin-2 (Tyr-Pro-Phe-Phe-NH2, EM2), the endogenous selective mu-opioid receptor agonists, can inhibit phenylephrine (PE) induced contraction which is related to the release of nitric oxide from vascular endothelium in aorta rings of rats and rabbits. The reduced (CH2NH) amide bond is a useful peptide bond surrogate in the design of opioid mimetics because it could enhance conformational flexibility and metabolic stability. The present work was designed to investigate the vascular activities of interrelated endomorphin analogues: endomorphin-1[psi] (Tyr[psi(CH2NH)]Pro-Trp-Phe-NH2, EM1[psi]) and endomorphin-2[psi] (Tyr[psi(CH2NH)]Pro-Phe-Phe-NH2, EM2[psi]). The effect of EM1[psi] (1, 2, 3, 4, 5 microM) and EM2[psi] (0.001, 0.01, 0.1, 1, 5 microM) were evaluated on rat thoracic aortic rings pre-contracted with PE (0.1 microM). EM1[psi] and EM2[psi] both caused a concentration-dependent relaxation. The IC50 of EM1[psi] and EM2[psi] was 3.332 microM and 1.226 microM, respectively. The vasorelaxant effect of EMs[psi] is 216.9 and 237.1 fold more potent than EMs. Moreover, the vasorelaxant effect of EMs[psi] was blocked by naloxone (NaCl, 1 microM) and was reduced by N(omega)-nitro-L-arginine (L-NNA, 1 microM) and removal of endothelium. The present study demonstrated that EMs[psi] had more potent vasorelaxant effects and their activities were naloxone-sensitive and endothelium-dependent and partially NO-dependent, similar to the mechanism of parent EMs.

Animals↗
PubMed2005

[Isolation and identification of arboviruses from mosquito pools in Yunnan Province].

BACKGROUND: To survey arboviruses in Yunnan province. METHODS: Mosquitoes were collected from Yunnan Province in 2002 and 2004. Virus strains were isolated by the inoculation of homogenates of the mosquitoes onto BHK cell line. The isolated strains and their molecular biological characteristics were identified by real-time PCR, reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescent antibody technique. RESULTS: Twelve strains of viruses producing CPE in BHK cells were isolated from 4810 mosquitoes. All the 12 isolates were identified to be Japanese encephalitis viruses. Genotype analysis showed the new virus (DL-0437 strain) belonged to genotype III. CONCLUSION: Twelve strains of Japanese encephalitis viruses were isolated from mosquito pools collected in Yunnan. It was the first isolation of genotype III Japanese encephalitis viruses in Yunnan Province in recent years.

Animals↗
PubMed2005

[Research on Culex tritaeniorhynchus and Culex pipiens quinquefasciatus intrathoracically infected with attenuated Japanese encephalitis virus SA14-14-2 vaccine strain].

BACKGROUND: To determine if the attenuated Japanese encephalitis (JE) virus SA14-14-2 vaccine strain interacts efficiently with Culex tritaeniorhynchus and Culex pipiens quinquefasciatus, and further to acquire a new knowledge of its characteristics and safety for human beings. METHODS: Laboratory colonies of the two species of mosquitoes were set up and were inoculated intrathoracically with the attenuated vaccine virus and wild JE virus (Nak), both of which were used with different dilution from 10(-1) to 10(-9). Subsequently, the virus titers in the mosquitoes were detected by the plaque assay. RESULTS: Inoculated with the vaccine strain, two species of mosquitoes were infected with the titers ranged from 10(0)-10(-3), and the maximum titers in Culex tritaeniorhynchus and Culex pipiens quinquefasciatus were 4.48 logPFU/ml and 5.63 logPFU/ml, respectively. Inoculated with wild JE virus, Culex pipiens quinquefasciatus was infected with titers ranged from 10(0)-10(-5), and the maximum titer in the mosquitoes was 6.59; Culex tritaeniorhynchus was infected with titers ranged from 10(0)-10(-4) and the maximum titer was 5.74 logPFU/ml. CONCLUSION: By intrathoracic infection, the attenuated JE virus SA14-14-2 vaccine strain can replicate in both species of mosquitoes.

Animals↗
PubMed2004

Deficits in reproduction and pro-gonadotropin-releasing hormone processing in male Cpefat mice.

Cpe(fat/fat) mice are obese, diabetic, and infertile. These animals have a point mutation in carboxypeptidase E (CPE), an exopeptidase that removes C-terminal basic amino acids from peptide intermediates. The mutation renders the enzyme unstable, and it is rapidly degraded. Although the infertility of Cpe(fat/fat) mice has not been systematically investigated, it is thought to be due to a deficit in GnRH processing. We have evaluated this hypothesis and found hypothalamic GnRH levels to be reduced by 65-78% and concentrations of pro-GnRH and C-terminal-extended intermediates to be high. Basal serum gonadotropin contents are similar among wild-type, heterozygous, and homozygous mice. Testis morphology and function are abnormal in older obese Cpe(fat/fat) mice. Matings between homozygous mutants yield a 5% pregnancy rate. By comparison, when 50-d-old Cpe(fat/fat) males are paired with heterozygous females, rates increase to 43%, and they rapidly decrease to negligible levels by 120 d. As fertility declines without accompanying changes in the hypothalamic-pituitary-gonadal axis and before obesity is evident, reproduction is more complex than originally thought. This suspicion is confirmed in 90-d-old Cpe(fat/fat) males, who readily interact with females, but rarely mount and fail to show intromission or ejaculation behaviors. Together, these findings show that CPE is a key enzyme for pro-GnRH processing in vivo; however, the reproductive deficits in Cpe(fat/fat) males appear to be due primarily to abnormal sexual behavior.

Animals↗
PubMed2004

Obesity and diabetes in transgenic mice expressing proSAAS.

ProSAAS is a neuroendocrine peptide precursor that potently inhibits prohormone convertase 1 in vitro. To explore the function of proSAAS and its derived peptides, transgenic mice were created which express proSAAS using the beta-actin promoter. The body weight of transgenic mice was normal until approximately 10-12 weeks, and then increased 30-50% over wild-type littermates. Adult transgenic mice had a fat mass approximately twice that of wild-type mice, and fasting blood glucose levels were slightly elevated. In the pituitary, the levels of several fully processed peptides in transgenic mice were not reduced compared with wild-type mice, indicating that the proSAAS transgene did not affect prohormone convertase 1 activity in this tissue. Because the inhibitory potency of proSAAS-derived peptides towards prohormone convertase 1 is much greater in the absence of carboxypeptidase E activity, the proSAAS transgene was also expressed in carboxypeptidase E-deficient Cpe (fat/fat) mice. Although the transgenic mice were born in the expected frequency, 21 of 22 proSAAS transgenic Cpe (fat/fat) mice died between 11 and 26 weeks of age, presumably due to greatly elevated blood glucose. The levels of several pituitary peptides were significantly reduced in the proSAAS transgenic Cpe (fat/fat) mice relative to non-transgenic Cpe (fat/fat) mice, suggesting that the transgene inhibited prohormone convertase 1 in these mice. Taken together, these results are consistent with a role for proSAAS-derived peptides as neuropeptides that influence body weight independently of their function as inhibitors of prohormone convertase 1.

Animals↗
PubMed2004

PCR-based site-specific mutagenesis of peptide antibiotics FALL-39 and its biologic activities.

AIM AIM: To construct PGEX-1lambdaT-FALL-39 expression vector and its mutant vector, and study the relationship of function and structure. METHODS: A cDNA encoding mature FALL-39 was cloned from SPCA-1 cell mRNA and the prokaryotic expression vector PGEX-1lambdaT-FALL-39 was constructed. Two kinds of polymerase chain reaction (PCR) for the site-direction mutagenesis were used to construct FALL-39 mutant expression vector, FALL-39-Lys-32 and FALL-39-Lys-24. Minimal effective concentration, minimal inhibitory concentration, and minimal bactericidal concentration were used to assay the antibacterial activities of these peptides. Effects of different solution on the antibacterial activity of FALL-39 and FALL-39-Lys-32 were observed by CFU determination. The hemolytic effects of these peptides were also examined on human red blood cells. RESULTS: Two site-specific mutants FALL-39-Lys-32 and FALL-39-Lys24 were obtained by PCR-induced mutagenesis. In comparison with two-step PCR which required two pairs of primers, one step PCR which required one pair of primers is a simple and efficient method for the PCR based site-specific mutagenesis. Using the prokaryotic expression system, the E coli-based products of recombinant FALL39 and its mutant peptides were also obtained. The antibacterial assay showed that FALL-39-Lys-32 and FALL-39-Lys24 were more potential in the antibacterial activity against E coli ML35p and Pseudomonas aeruginosa ATCC27853 than that of FALL-39, and no increase in hemolysis was observed at the antibacterial concentrations. The antibacterial activity of FALL-39-Lys-32 against E coli was more potent than that of FALL-39 in NaCl-containing LB medium, while its activity was almost the same as FALL-39 in SO4(2-) containing Medium E. CONCLUSION: PCR-based mutagenesis is a useful model system for studying the structure and function relationship of antimicrobial peptides. Keeping a-helical conformation of FALL-39 and increasing net positive charge can increase the antibacterial activity of FALL-39 without increasing hemolysis at the antibacterial concentrations.

Amino Acid Sequence↗
PubMed2003

Neuropeptide-processing carboxypeptidases.

Neuropeptides are generally produced from precursor proteins by selective cleavage at specific sites, usually involving basic amino acids. Enzymes such as the prohormone convertases and carboxypeptidase E are highly specific for these basic amino acid-containing sites. In addition to this "traditional" pathway, several neuropeptides are known to be cleaved at non-basic sites, and the enzymes responsible for these cleavages have not been conclusively identified. In a recent search for novel members of the metallocarboxypeptidase family, we found three human genes. One of these, named "CPA-5," has a specificity for C-terminal hydrophobic amino acids and mRNA expression in brain, pituitary, and testis. To test whether CPA-5 protein has a distribution pattern in pituitary that is consistent with a role for this enzyme in the non-basic processing of proopiomelanocortin-derived peptides such as beta-endorphin and adrenocorticotropin, we examined the distribution of CPA-5 using immunocytochemistry. In the pituitary, CPA-5 is detected in the neurointermediate lobe and in scattered cells in the anterior lobe. In the AtT-20 corticotroph cell line, CPA-5 has a perinuclear distribution. Taken together, these results are consistent with a role for CPA-5 in the intracellular processing of proopiomelanocortin-derived peptides at non-basic sites.

Animals↗
PubMed2003

Expression profiling identifies a novel alpha-methylacyl-CoA racemase exon with fumarate hydratase homology.

Human alpha-methylacyl-CoA racemase (AMACR) was overexpressed in prostate cancer compared with nonmalignant tissues. The Gene Logic Inc. BioExpress database containing Affymetrix U133 GeneChip expression profiles of 4400 human normal, benign, diseased, and tumor samples from >60 tissue types was examined to determine the specificity of AMACR mRNA expression. One particular AMACR probeset was derived from an alternatively spliced exon with 88% identity to a 521-bp sequence that spans four exons of the fumarate hydratase. The predicted protein sequence revealed a novel GLGELIL peptide shared by both proteins. Whether the mitochondrial and peroxisomal AMACR described previously are distinct products from alternatively spliced transcripts remains to be determined. The determination of the cellular location and function of the altered AMACR will be critical in the elucidation of the role of AMACR in prostate cancer diagnosis and pathogenesis.

Adenocarcinoma↗
PubMed2003

The Drosophila SNR1 (SNF5/INI1) subunit directs essential developmental functions of the Brahma chromatin remodeling complex.

The Drosophila melanogaster Brahma (Brm) complex, a counterpart of the Saccharomyces cerevisiae SWI/SNF ATP-dependent chromatin remodeling complex, is important for proper development by maintaining specific gene expression patterns. The SNR1 subunit is strongly conserved with yeast SNF5 and mammalian INI1 and is required for full activity of the Brm complex. We identified a temperature-sensitive allele of snr1 caused by a single amino acid substitution in the conserved repeat 2 region, implicated in a variety of protein-protein interactions. Genetic analyses of snr1(E1) reveal that it functions as an antimorph and that snr1 has critical roles in tissue patterning and growth control. Temperature shifts show that snr1 is continuously required, with essential functions in embryogenesis, pupal stages, and adults. Allele-specific genetic interactions between snr1(E1) and mutations in genes encoding other members of the Brm complex suggest that snr1(E1) mutant phenotypes result from reduced Brm complex function. Consistent with this view, SNR1(E1) is stably associated with other components of the Brm complex at the restrictive temperature. SNR1 can establish direct contacts through the conserved repeat 2 region with the SET domain of the homeotic regulator Trithorax (TRX), and SNR1(E1) is partially defective for functional TRX association. As truncating mutations of INI1 are strongly correlated with aggressive cancers, our results support the view that SNR1, and specifically the repeat 2 region, has a critical role in mediating cell growth control functions of the metazoan SWI/SNF complexes.

Amino Acid Sequence↗
PubMed2003

[Construction of a site-directed mutant of FALL-39 and antibacterial activity of its E. coli-based product].

OBJECTIVE: Constructing a point-directed mutant of FALL-39 and prokaryotic expressive vector, and determining its antibacterial activity. METHODS: A two-step polymerase chain reaction (PCR) was used for the site-directed mutagenesis. Two sets of primers (P1, P2, P3, P4) were designed according to FALL-39 gene sequence and mismatch was introduced into P2 for a substitution of AAG for AAT at position 32. Mutagenesis was performed in a two-step PCR, the amplified fragments from the second PCR, which contain the mutation site, were subcloned into the vector PGEX lambda 1T and verified by sequencing analysis. Antibacterial activities of the E. coli-based product against E. coli and P. aeruginosa were detected by using minimal inhibitory concentration (MIC), minimal effective concentration (MEC) and minimal bactericidal concentration (MBC). RESULTS: A mutant of FALL-39, whose AAT at position 32 is substituted by AAG, was obtained by the two-step PCR. The antibacterial activities of the E. coli-based product of the recombinant FALL-39-Lys32 against E. coli ML-35p and P. aeruginosa ATCC27853 were much stronger than those of FALL-39. MIC and MBC of the FALL-39 against E. coli were 18.75 micrograms/ml and 37.50 micrograms/ml, whereas those of FALL-39-Lys32, 10.94 micrograms/ml and 21.88 micrograms/ml respectively. CONCLUSION: A point-directed FALL-39-Lys32 mutant was obtained by using two-step PCR and its antibacterial activity was increased, suggesting that increased cationic FALL-39 mutant might enhance its antibacterial activity.

Anti-Bacterial Agents↗
PubMed2003

[Isolation and purification of an antibacterial polypeptide from human cervical mucus].

OBJECTIVE: This study was made to isolate and purify antibacterial polypeptides from human cervical mucus. METHODS: Human cervical mucus was collected from human healthy subjects, and the acid-soluble extract was obtained by solving the mucus with 5% acetic acid in the presence of protease inhibitor. By using gel overlay technique, one protein band that was potently antibacterial against E. coli ML-35P was identified. To purify the antibacterial polypeptide, the preparative acid-urea gel electrophoresis and Reverse Phase HPLC were performed. RESULTS: A purified antibacterial polypeptide was obtained and named HCP-1. Tricine-SDS-PAGE indicated that the relative molecular mass of HCP-1 was around 14 x 10(3). Agar radial diffusion assay showed that the purified polypeptide had antibacterial activities against E. coli ML-35P and Pseudomanas aeruginosa ATCC65922. CONCLUSION: HCP-1 may be a new effector molecule of human cervical mucus.

Adult↗
PubMed2003

[The human beta-defensins expression in female genital tract and pregnancy-related tissues].

OBJECTIVE: Human beta-defensins (HBDs) are small, cationic endogenous antimicrobial peptides isolated from the hemodialates of patients with chronic renal failure (HBD-1) and Psoriasic skin (HBD-2). They may play an important role in mucosal innate host defense against infections. In this study, we examined their mRNAs expression in normal and pregnant women genital tract. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was performed in the detection of HBD-1 and HBD-2 mRNA expression in the samples from normal and pregnant women genital tract. beta-actin was taken as positive control. RESULTS: RT-PCR detection revealed that HBD-1 mRNA expressed in all samples of normal women taken from vagina, cervix, endometrium, fallopian tube, and ovary, and HBD-2 mRNA widely expressed in genital tract except vagina and ovary. In pregnant women, HBD-1 mRNA widely expressed in chorion, villus, placenta, and umbilical cord, but not in amnion, and HBD-2 mRNA were detected in chorion, villus and placenta tissues. CONCLUSION: The findings of this study on the wide expression of HBD-1 and HBD-2 in both the normal and the pregnant women genital tract suggest that HBDs may play an important role in human genital tract defense mechanisms.

Adult↗
PubMed2003

Mycobacterium bovis bacille Calmette-Guérin (BCG) enhances human beta-defensin-1 gene transcription in human pulmonary gland epithelial cells.

AIM: To examine the stimulatory effect of bacille Calmette-Gu rin (BCG) cell wall components on human beta-defensin-1 (hBD-1) gene expression and analyze the response element in the 5'-flanking region of the gene. METHODS: BCG cell wall proteins were fractionated by Sephadex G-150 chromatography. Using reverse-transcription polymerase chain reaction (RT-PCR) and Northern hybridization analysis, hBD-1 mRNA expression was detected in a human pulmonary gland epithelial cell line SPC-A-1 cells. Progressive deletions of 5'-flanking region of hBD-1 gene were produced by PCR and ligated into promoterless chloramphenicol acetyltransferase (CAT) expression plasmid to construct pCAT reporter plasmids. Reporter gene expression was determined by ELISA. RESULTS: There was an obvious enhancement of hBD-1 mRNA expression after stimulation with heat-inactivated BCG whole cells (50 mg/L), or the cell wall components with a molecular weight of 18-30 kDa (3 mg/L) for 8 h. The upstream sequence between -314 bp and +54 bp had the inducible activity by BCG, which contained CCAAT/enhancer binding protein-beta (C/EBP beta), activator protein-1 (AP-1), and CP2 cis element. CONCLUSION: BCG cell wall components (18-30 kDa) can stimulate hBD-1 mRNA expression in pulmonary gland epithelial cells. The sequence (-314/+54) containing C/EBP beta, AP-1, and CP2 binding sites in the upstream of hBD-1 is involved in this induction.

Adenocarcinoma↗
PubMed2003

[Effects of Fall-39 mRNA expression and antibacterial activity of human pulmonary gland epithelial cells induced by BCG].

OBJECTIVE: To disclose whether BCG can enhance Fall-39 gene expression in human pulmonary gland epithelial cells, and to isolate and identify the bioactive proteins that stimulate Fall-39 gene expression in human pulmonary gland epithelial cells. METHODS: Fall-39 mRNA expression in SPC-A-1 cells was detected by using RT-PCR. The cell wall proteins were isolated by sucrose density-gradient centrifugation and fractionated by Sephadex G-75 column chromatography. The antibacterial activity of the cell culture supernatant was determined by agarose radial diffusion assay. RESULTS: The enhanced expression of Fall-39 mRNA was dose- and time-dependent. BCG cell wall proteins fraction 4 had an activity that remarkably enhanced Fall-39 mRNA expression in SPC-A-1 cells and augmented antibacterial activity of the cell culture supernatant. CONCLUSION: These results indicated that BCG could stimulate Fall-39 mRNA expression in human pulmonary gland epithelial cells, thus providing an evidence base for shaping well a new strategy to enhance mucosa antibiotic peptide expression for the prevention and treatment of mucosal infections.

Anti-Bacterial Agents↗