S14-95, a novel inhibitor of the JAK/STAT pathway from a Penicillium species.

In a search for new inhibitors of the IFN-γ mediated signal transduction in HeLa S3 cells using secreted alkaline phosphatase (SEAP) as reporter gene, a novel compound, designated as S14-95 was isolated from fermentations of the imperfect fungus Penicillium sp. 14-95. The compound inhibits the IFN-γ mediated expression of the reporter gene with IC50 values of 2.5~5μg/ml (5.4~10.8μM). Furthermore the compound inhibited the expression of the proinflammatory enzymes COX-2 and NOS II at 5μg/ml (10.8μM) in LPS/IFN-γ stimulated J774 mouse macrophages. Studies on the mode of action of the compound revealed that the inhibition of the IFN-γ dependent signaling pathway is caused by an inhibition of the phosphorylation of the STAT1α transcription factor. In addition, S14-95 inhibited the activation of the p38 MAP kinase, which is involved in the inducible expression of many proinflammatory genes

Inhibition of TNF-alpha promoter activity and synthesis by A11-99-1, a new cyclopentenone from the ascomycete Mollisia melaleuca

In a search for inhibitors of the inducible tumor necrosis factor-alpha (TNF-alpha) promoter activity and synthesis, a new chlorinated cyclopentenone was isolated from fermentations of the ascomycete Mollisia melaleuca. The structure was determined by a combination of spectroscopic techniques. The compound blocked the inducible human TNF-alpha promoter activity and synthesis with IC50-values of 2.5-5 mu g/ml (8.1-16.1 mu M). Studies on the mode of action of the compound revealed that the inhibition of TNF-alpha promoter activity is caused by an inhibition of the phosphorylation of the I kappa B protein which prevents the activation of the transcription factor NF-kappa B. No cytotoxic, antibacterial and antifungal activities could be observed up to 100 mu g/ml (323 mu m) of the compound

Oxaspirodion, a new inhibitor of inducible TNF-alpha expression from the ascomycete Chaetomium subspirale

In a search for new inhibitors of the TNF-alpha promoter activity, a new spiro-compound, designated oxaspirodion, was obtained as a mixture of four isomers from fermentations of the ascomycete Chaetomium subspirale. The structure was determined by a combination of spectroscopic techniques

Enrichment and characterization of the mRNAs of four aminoacyl-tRNA synthetases from yeast.

We have partially purified the messenger RNAs for yeast arginyl-, aspartyl-, valyl-, alpha and beta subunits of phenylalanyl-tRNA synthetases in order to study their biosynthesis and ultimately, to isolate their genes. Sucrose gradient fractionation of poly U-Sepharose selected mRNAs resulted in a ten fold enrichment of the in vitro translation activity of these mRNAs. The translation products of messenger RNAs for arginyl- and valyl-tRNA synthetases have the same molecular weight as the purified enzymes; translation of aspartyl-tRNA synthetase messenger RNA yielded a 68 kD molecular weight polypeptide (while the purified cristallisable enzyme appears as a 64-66 kD doublet, which, as we showed is a proteolysis product). The translation of the mRNAs for alpha and beta phenylalanyl-tRNA synthetase gave polypeptides having the same molecular weight as those obtained from the purified enzyme, but the major translation products are slightly heavier, indicating that they may be translated as precursors. As estimated from centrifugation experiments mRNAs of arginyl-, aspartyl-, alpha and beta subunits of phenylalanyl-tRNA synthetase were 1700-2000 nucleotides long, indicating that alpha and beta are translated from two different mRNAs