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Biomedical subjects

J X Lin

Publications and source records attributed to J X Lin.

50 records · Page 3Linked to original sources
PubMed1987

Tumor necrosis factor and interleukin-1 cause a rapid and transient stimulation of c-fos and c-myc mRNA levels in human fibroblasts.

Tumor necrosis factor (TNF) and interleukin-1 (IL-1) were shown previously to be mitogenic for human fibroblasts. Here we show that recombinant human TNF and recombinant human IL-1 alpha increase steady state levels of c-fos and c-myc proto-oncogene mRNAs in quiescent human FS-4 fibroblasts. Proto-oncogene mRNA levels were enhanced within 20 min of TNF or IL-1 addition, peaked at 30 min, and declined to undetectable levels (c-fos) or basal levels (c-myc) by 60 or 90 min. A similar rapid increase in c-fos and c-myc mRNA was seen in quiescent FS-4 cells exposed to cycloheximide. However, in the presence of cycloheximide, both proto-oncogene mRNA levels continued to rise for at least 90 min. The transient nature of the increase in c-myc mRNA levels appears to be a response characteristic for TNF and IL-1 because in quiescent FS-4 cells exposed to 10% fetal bovine serum, steady state levels of c-myc mRNA remained elevated for at least 4 h.

Cycloheximide↗
PubMed1986

Bacterial lipopolysaccharide-induced interferon-gamma production: roles of interleukin 1 and interleukin 2.

Bacterial lipopolysaccharide (LPS) induced human peripheral blood mononuclear cells (PBMC) to produce interferon-gamma (IFN-gamma). Monocytes play a mandatory accessory role in this process, because purified T lymphocytes failed to produce IFN-gamma in response to LPS and the addition of 2% monocytes to T cell cultures resulted in an optimal LPS-induced IFN-gamma production. IFN-gamma production was abolished in the presence of monoclonal antibodies specific for HLA-DR antigen. Addition of exogenous interleukin 2 (IL 2) markedly enhanced IFN-gamma secretion by PBMC induced with LPS. The addition of anti-Tac antibody specific for IL 2 receptors abrogated IFN-gamma production, suggesting that an interaction of IL 2 with IL 2 receptors was involved. By using a specific antibody binding assay, LPS was shown to amplify IL 2 receptor expression on PBMC, whereas exogenous IL 2 showed only a negligible enhancing effect on the expression of its own receptors. Interleukin 1 (IL 1), a product of LPS-stimulated monocytes, potentiated IL 2-induced IFN-gamma production in the absence of LPS. Neither IL 1 nor IL 2 alone induced IFN-gamma production in purified T lymphocyte cultures. When added together, however, substantial levels of IFN-gamma were induced. An enhanced IL 2 receptor expression on T cells was also demonstrated as a result of the combined action of IL 1 and IL 2. These results suggest that induction of IFN-gamma by LPS is due mainly to the generation of IL 1 and an enhanced expression of IL 2 receptors.

Animals↗
PubMed1986

Efficient expression of unfused human alpha D-interferon in Escherichia coli using overlapping termination and initiation codons (TGATG) in its signal sequence.

A plasmid carrying the lambda PL promoter was constructed to express efficiently unfused human alpha D-interferon (HuIFN-alpha D) in Escherichia coli using a TGATG site in its signal sequence, which occurs also in the lambda DNA sequence. The unfused nature of HuIFN-alpha D expressed by pBV867 in E. coli (BMH 71-18) was confirmed by the following evidence: first, the purified IFN showed a single band of 19.5K in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE); a 27K band, representing lambda N-HuIFN-alpha D fusion protein, was not detected. Second, the peak of IFN activity coincided with the 19.5K protein. Third, the peak of absorbent material for human leukocyte IFN antibody coincided with that of IFN activity. Finally, amino-terminal sequencing of purified IFN demonstrated an unfused HuIFN-alpha D. This suggests that E. coli is able to process the signal sequence of HuIFN-alpha D. Studies on the mechanism of "translational coupling" initiation of gene expression were carried out by the construction of two hybrid plasmids and titration of the IFN activities produced by them. The level of expression by the ATG-TGATG initiation mode was found to be six times higher than that of the single ATG mode.

Bacteriophage lambda↗