st-638 and staurosporine-aglycone

Bafilomycin A1, a selective inhibitor of vacuolar H+-ATPase, time- and dose-dependently induced the differentiation of M1 cells, a murine myeloid leukemic cell line, into macrophage-like cells as revealed by the phagocytosis of polystyrene latex particles. This differentiation was inhibited not only by actinomycin D and cycloheximide but also by ST-638 (an inhibitor of tyrosine kinase). However, it was affected neither by K-252a (an inhibitor of C-kinase) nor by H-89 (an inhibitor of A-kinase), in contrast to the M1 cell differentiation induced by leukemia inhibitory factor (LIF). Okadaic acid inhibited both the bafilomycin A1-induced and LIF-induced differentiation of M1 cells.

Topics: Animals; Anti-Bacterial Agents; Carbazoles; Cinnamates; Ethers, Cyclic; Growth Inhibitors; Indole Alkaloids; Interleukin-6; Isoquinolines; Leukemia Inhibitory Factor; Leukemia, Myeloid; Lymphokines; Macrolides; Macrophages; Mice; Okadaic Acid; Phagocytosis; Phosphoprotein Phosphatases; Phosphorylation; Protein Biosynthesis; Protein Kinase C; Protein Kinase Inhibitors; Proton-Translocating ATPases; RNA; Sulfides; Sulfonamides; Tumor Cells, Cultured; Vacuoles

Human neutrophils (PMN) respond to tumor necrosis factor (TNF) by releasing their granules, reorganizing their cytoskeleton, and massively secreting hydrogen peroxide. This response is dependent on adhesion to extracellular matrix proteins and expression of CD11b/CD18 integrins (Nathan, C., S. Srimal, C. Farber, E. Sanchez, L. Kabbash, A. Asch, J. Gailit, and S. D. Wright. 1989. J. Cell Biol. 109:1341-1349). We investigated the role of tyrosine phosphorylation in the response of PMN to TNF. PMN adherent to protein-coated surfaces but not suspended PMN showed tyrosine phosphorylation of several proteins (approximately 150, approximately 115, approximately 75, and approximately 65 kD) in response to TNF. Tyrosine phosphorylation was evident 5 min after addition of TNF and lasted at least 2 h. The tyrosine kinase inhibitors K252a, genistein and ST638 suppressed tyrosine phosphorylation and blocked hydrogen peroxide production in a reversible manner at low concentrations. Tyrosine kinase inhibitors also blocked the spreading of PMN in response to TNF. Dihydrocytochalasin B did not inhibit tyrosine phosphorylation, but in its presence phosphorylation was rapidly reversed. By immunocytochemistry, the majority of tyrosine phosphoproteins were localized to focal adhesions. Thus TNF-induced tyrosine phosphorylation depends on adhesion of PMN to extracellular matrix proteins, and participates in the transduction of the signals that direct the cells to spread on a biological surface and undergo a respiratory burst.

Topics: Carbazoles; Cell Adhesion; Cinnamates; Extracellular Matrix Proteins; Genistein; Humans; Hydrogen Peroxide; In Vitro Techniques; Indole Alkaloids; Isoflavones; Kinetics; Molecular Weight; Neutrophils; Phosphoproteins; Protein-Tyrosine Kinases; Recombinant Proteins; Sulfides; Time Factors; Tumor Necrosis Factor-alpha