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The adverse effects of lipopolysaccharide (LPS) are mediated primarily by tumor necrosis factor alpha (TNF-alpha). TNF-alpha production by LPS-stimulated macrophages is regulated at the levels of both transcription and translation. It has previously been shown that several mitogen-activated protein kinases (MAPKs) are activated in response to LPS. We set(More)
Extracellular signal-regulated protein kinases (ERK) 1 and 2 and mutants of each were expressed in bacteria with a hexahistidine tag and purified using nickel-chelate chromatography. Basal activity of wild type ERK2 was approximately 2 nmol/min/mg. Self-catalyzed phosphorylation occurred in vitro on the major physiological site of tyrosine phosphorylation(More)
The effect of interferon-gamma (IFN-gamma) on endothelial cell (EC) and fibroblast (FB) class II major histocompatibility complex (MHC) gene product expression and antigen presenting ability was examined. Control FB did not express class II MHC gene products, whereas a small (less than 1%) population of passaged EC expressed class II gene products.(More)
The role of ERK-1 and ERK-2 in wild-type (wt) Ha-Ras, phorbol 12-myristate 13-acetate (PMA), and serum-induced AP-1 activity was studied. Microinjection of ERK-specific substrate peptides inhibited the induction of AP-1 activity by all three stimuli, whereas a control peptide had no effect. By using eukaryotic expression constructs encoding wt ERK-1 and(More)
BACKGROUND Lipopolysaccharide (LPS) is known to activate macrophages, causing the release of toxic cytokines that may provoke inflammation and shock. One of the most important and best studied of these cytokines is tumor necrosis factor (TNF). Details of the signaling pathway leading to TNF biosynthesis remain unclear. The pathway is branched in the sense(More)
The association of various surface molecules with the cytoskeleton in resting peripheral blood T cells was examined by assaying the capacity of detergent to solubilize them. Cytoskeletal association was assessed by staining T cells with a fluorescein-conjugated mAb, resuspending the cells in buffer with or without the nonionic detergent, NP-40, and(More)
TCR engagement stimulates the activation of the protein kinase Raf-1. Active Raf-1 phosphorylates and activates the mitogen-activated protein (MAP) kinase/extracellular signal-regulated kinase kinase 1 (MEK1), which in turn phosphorylates and activates the MAP kinases/extracellular signal regulated kinases, ERK1 and ERK2. Raf-1 activity promotes IL-2(More)
The introduction of antigen into tissues can induce an inflammatory response initiated by antigen-specific T lymphocytes. Central to this process is the recognition of antigen by specific T cells that cannot respond to intact antigen directly, but rather recognize antigenic fragments in association with gene products of the major histocompatibility complex(More)
Deletion of the amino-terminal domain of Raf-1, which contains the Ras-binding region, results in the constitutive activation of the liberated Raf-1 catalytic domain in fibroblast cell lines. We demonstrate that the MEK kinase activity of the isolated Raf-1 catalytic domain, Raf-BXB, is not constitutively active, but is regulated in Jurkat T cells. Raf-BXB(More)