Biomedical subjects

Yun Feng

Publications and source records attributed to Yun Feng.

45 records · Page 3Linked to original sources

PubMed2003

[Bifidobacterium cell wall proteins induced beta-defensin 2 mRNA expression in human intestinal epithelial cells].

OBJECTIVE: To examine Bifidobacterium mediated induction of human defensin 2 mRNA expression in human intestinal epithelial cells and define the bioactive components of Bifidobacterium. METHODS: Bifidobacterium was cultured in MRS medium in anaerobic incubator and its cell wall was isolated by sonication and centrifugation. The cell wall proteins of Bifidobacteria were extracted with 2% SDS. The level of hBD-2 mRNA in HT-29 cells was detected by reverse-transcription PCR and Northern blot analysis. RESULTS: There was no detectable signal of hBD-2 mRNA in the unstimulated HT-29 cells. However, the heat-killed Bifidobacteria, cell wall of Bifidobacteria, and cell wall proteins remarkably induced hBD-2 mRNA expression in HT-29. CONCLUSION: Bifidobacterium or its cell wall proteins can induce hBD-2 gene expression in human intestinal epithelial cells, which may play a role in the mechanisms of innate defense against pathogens in the intestine.

Bacterial Proteins↗

PubMed2003

[E. coli-based production of recombinant FALL-39].

This study was aimed at constructing a prokaryotic expression system to resolve the difficulties in acquiring antibacterial peptide and to meet the needs of research and drug development. Total RNA was extracted from human pulmonary gland epithelial cell line SPC-A-1, and a cDNA encoding mature FALL-39 peptide was amplified by RT-PCR. The recombinant prokaryotic expression vector pGEX-1 lambda T-FALL-39 was constructed. Using affinity chromatography, thrombin cleaving and AU-PAGE elution, we obtained the purified FALL-39. MIC, MEC, MBC analyses demonstrated that the FALL-39 had strong antibacterial activity.

Antimicrobial Cationic Peptides↗

PubMed2002

Association of the ADAM33 gene with asthma and bronchial hyperresponsiveness.

Asthma is a common respiratory disorder characterized by recurrent episodes of coughing, wheezing and breathlessness. Although environmental factors such as allergen exposure are risk factors in the development of asthma, both twin and family studies point to a strong genetic component. To date, linkage studies have identified more than a dozen genomic regions linked to asthma. In this study, we performed a genome-wide scan on 460 Caucasian families and identified a locus on chromosome 20p13 that was linked to asthma (log(10) of the likelihood ratio (LOD), 2.94) and bronchial hyperresponsiveness (LOD, 3.93). A survey of 135 polymorphisms in 23 genes identified the ADAM33 gene as being significantly associated with asthma using case-control, transmission disequilibrium and haplotype analyses (P = 0.04 0.000003). ADAM proteins are membrane-anchored metalloproteases with diverse functions, which include the shedding of cell-surface proteins such as cytokines and cytokine receptors. The identification and characterization of ADAM33, a putative asthma susceptibility gene identified by positional cloning in an outbred population, should provide insights into the pathogenesis and natural history of this common disease.

ADAM Proteins↗

PubMed2002

Identification and characterization of three members of the human metallocarboxypeptidase gene family.

Amino acid homology searches of the human genome revealed three members of the metallocarboxypeptidase (metallo-CP) family that had not been described in the literature in addition to the 14 known genes. One of these three, named CPA5, is present in a gene cluster with CPA1, CPA2, and CPA4 on chromosome 7. The cDNA encoding a mouse homolog of human CPA5 was isolated from a testis library and sequenced. The deduced amino acid sequence of human CPA5 has highest amino acid sequence identity (60%) to CPA1. Modeling analysis shows the overall structure to be very similar to that of other members of the A/B subfamily of metallocarboxypeptidases. The active site of CPA5 is predicted to cleave substrates with C-terminal hydrophobic residues, as do CPA1, -2, and -3. Using Northern blot analysis, CPA5 mRNA is detected in testis but not in kidney, liver, brain, or lung. In situ hybridization analysis shows that CPA5 is localized to testis germ cells. Mouse pro-CPA5 protein expressed in Sf9 cells using the baculovirus system was retained in the particulate fraction of the cells and was not secreted into the media. Pro-CPA5 was not enzymatically active toward standard CPA substrates, but after incubation with prohormone convertase 4 the resulting protein was able to cleave furylacryloyl-Gly-Leu, with 3-4-fold greater activity at pH 7.4 than at 5.6. Two additional members of the human CP gene family were also studied. Modeling analysis indicates that both contain the necessary amino acids required for enzymatic activity. The CP on chromosome 8 is predicted to have a CPA-like specificity for C-terminal hydrophobic residues and was named CPA6. The CP on chromosome 2 is predicted to cleave substrates with C-terminal acidic residues and was named CPO.

Amino Acid Sequence↗

PubMed2002

Processing of proSAAS in neuroendocrine cell lines.

ProSAAS, a recently discovered granin-like protein, potently inhibits prohormone convertase (PC)1, and might also perform additional functions. In the present study, the processing of proSAAS was compared in two neuroendocrine cell lines overexpressing this protein: the AtT-20 mouse pituitary corticotrophic line and the PC12 rat adrenal phaeochromocytoma line. The processing of proSAAS was examined by pulse-chase analysis using [(3)H]leucine, by MS, and by chromatography and radioimmunoassay. Various smaller forms of proSAAS were detected, including peptides designated as little SAAS, PEN and big LEN. Because the PC-12 cells used in the present study do not express either PC1 or PC2, the finding that these cells efficiently cleave proSAAS indicates that these cleavages do not require either enzyme. Two of the peptides identified in AtT-20 media represent novel C-terminally truncated forms of PEN. In both cell lines, the secretion of the small proSAAS-derived peptides is stimulated by secretagogues. However, long-term treatment of wild-type AtT-20 cells with two different secretagogues (8-bromo-cAMP and a phorbol ester) does not affect levels of proSAAS mRNA; this treatment significantly increases PC1 mRNA by approx. 60-80%. The lack of co-regulation of proSAAS and PC1 mRNA implies that enzyme activity can be induced without an accompanying increase in the inhibitor. In addition, the finding that the peptides are secreted via the regulated pathway is consistent with the proposal that they may function as neuropeptides.

Animals↗

PubMed2002

ProSAAS and prohormone convertase 1 are broadly expressed during mouse development.

ProSAAS (encoded by mouse gene Pcsk1n) is a recently described neuroendocrine secretory pathway protein that is cleaved into smaller peptides that may function in cell-cell signalling. ProSAAS and its processing intermediates are also potent inhibitors of prohormone convertase 1 (PC1), which is encoded by mouse gene Pcsk1. In order to gain insight into the function of proSAAS, we have examined the distribution of several proSAAS-derived peptides and PC1 by immunohistochemistry throughout mouse development. The distribution patterns of both SAAS and PC1 are broad from E9 to E11, with some enrichment in neural tube-derived tissues. By E15, the expression of SAAS is largely restricted to neuroendocrine tissues known to produce bioactive peptides. In general, the expression pattern of PC1 overlaps with that of SAAS and other proSAAS-derived peptides, consistent with the hypothesis that proSAAS functions as an endogenous PC1 inhibitor.

Animals↗

PubMed2002

Studies on adjuvanticity of sodium houttuyfonate and its mechanism.

The adjuvanticity of sodium houttuyfonate (SH) and its mechanism were studied in this research. Significant enhancement of antibody production was observed when co-injected with antigen. The levels of anti-BSA antibodies were measured by enzyme-linked immunosorbent assay (ELISA). The possible mechanism of this phenomenon was also investigated in this research, which included the effects of SH on the phagocytosis of macrophages, the production of lysozyme, acid phosphotase and IL-1beta generated by macrophages, the proliferation of the lymphocytes in spleen and the production of IL-2 generated by lymphocytes. IL-1beta is a co-stimulator in activating Th cells, which manifests its activity together with LFA-1, ICAM-1 and ICAM-2. These observations suggested that SH could be used as a new adjuvant.

Adjuvants, Immunologic↗

PubMed2002

Genetic and molecular analysis of region 88E9;88F2 in Drosophila melanogaster, including the ear gene related to human factors involved in lineage-specific leukemias.

We identified and characterized the Drosophila gene ear (ENL/AF9-related), which is closely related to mammalian genes that have been implicated in the onset of acute lymphoblastic and myelogenous leukemias when their products are fused as chimeras with those of human HRX, a homolog of Drosophila trithorax. The ear gene product is present in all early embryonic cells, but becomes restricted to specific tissues in late embryogenesis. We mapped the ear gene to cytological region 88E11-13, near easter, and showed that it is deleted by Df(3R)ea(5022rx1), a small, cytologically invisible deletion. Annotation of the completed Drosophila genome sequence suggests that this region might contain as many as 26 genes, most of which, including ear, are not represented by mutant alleles. We carried out a large-scale noncomplementation screen using Df(3R)ea(5022rx1) and chemical (EMS) mutagenesis from which we identified seven novel multi-allele recessive lethal complementation groups in this region. An overlapping deficiency, Df(3R)Po(4), allowed us to map several of these groups to either the proximal or the distal regions of Df(3R)ea(5022rx1). One of these complementation groups likely corresponds to the ear gene as judged by map location, terminal phenotype, and reduction of EAR protein levels.

Animals↗

PubMed2002

[Culture and identification of dendritic cells from the peripheral blood of patients with laryngeal squamous cell carcinoma in vitro].

OBJECTIVE: To culture dendritic cells (DC) from peripheral blood of patients with laryngeal carcinoma for therapeutic aid. METHODS: Adherent peripheral blood mononuclear cells from peripheral blood were cultured with 15 ng/ml rhGM-CSF and 7 ng/ml rhIL-4 for one or two weeks. The purity of DC was detected by immunocytochemistry method. The mixed leukocyte reactions stimulated by DC loaded with laryngeal carcinoma antigen were tested by measuring 3H-TdR uptake. RESULTS: A considerable number of suspended cells with spicular or dendritic appearance were observed after 1 week of culture, and their mitochondria were rich in cytoplasm. The positivity of DC was about 30%-60%. DC loaded with laryngeal antigen could induce proliferation of syngeneic T lymphocytes. CONCLUSION: A large number of DC with high purity can be cultured from peripheral blood of patients with laryngeal carcinoma in vitro. It may be used in further experimental studies for clinical applications.

Carcinoma, Squamous Cell↗