Cytokine mRNA decay is accelerated by an inhibitor of p38-mitogen-activated protein kinase.

OBJECTIVE: To identify the site(s) in tumor necrosis factor (TNFalpha), interleukin-6 (IL-6), and macrophage inflammatory protein-1alpha (MIP-1alpha) biosynthesis that is blocked by SB202190, a selective inhibitor of p38-mitogen activated protein kinase (p38). MATERIALS: Human blood monocytes isolated by centrifugal elutriation. METHODS: Monocytes were stimulated with lipopolysaccharide in the presence of 0, 0.3, 1 and 3 microM SB202190. Induced TNFalpha, IL-6, and MIP-1alpha protein and mRNA were measured by ELISA and quantitative RT-PCR, respectively. The half-lives of cytokine mRNA levels were determined following treatment of cells with actinomycin D or SB202190. RESULTS: SB202190 suppressed >60% of lipopolysaccharide-induced TNFalpha, IL-6, and MIP-1alpha protein and mRNA expression. Suppressed mRNA levels could be attributed to a >2 to 7-fold reduction in cytokine mRNA half-lives. In contrast, SB202190 did not destabilize mRNAs encoding interferon-induced gene 15 protein and glyceraldehyde-3-phosphate dehydrogenase. CONCLUSIONS: Specific mRNA destabilization represents an important and novel site of action for the cytokine suppressive effects of p38 inhibitors.

STCP-1 (MDC) CC chemokine acts specifically on chronically activated Th2 lymphocytes and is produced by monocytes on stimulation with Th2 cytokines IL-4 and IL-13.

STCP-1 stimulated T cell chemoattractant protein-1 (STCP-1) (macrophage-derived chemokine; MDC), a recently described CC chemokine for chronically activated T lymphocytes, was found to act specifically on a subset of memory CD4 lymphocytes that displayed a Th2 cytokine profile. Also, STCP-1, thymus and activation regulated chemokine (TARC), eotaxin, and eotaxin-2 acted specifically on in vitro derived Th2 lymphocytes, while IP-10 (IFN-gamma-inducible 10-kDa protein) showed some preference for Th1 lymphocytes. The corresponding receptors for eotaxin, TARC, and IP-10 are also differentially expressed on Th1 and Th2 lymphocytes. In desensitization Ca flux experiments, TARC and STCP-1 bound to a common receptor and therefore at least one chemokine receptor for STCP-1 is CCR4. STCP-1 expression is restricted to immune cells. Dendritic cells, B cells, and macrophages produce STCP-1 constitutively, while NK cells, monocytes, and CD4 lymphocytes produce STCP-1 upon appropriate stimulation. Production of STCP-1 is positively modulated by Th2 cytokines IL-4 and IL-13 but inhibited by IL-10.

RNA aptamers that specifically bind to a K Ras-derived farnesylated peptide.

RNA aptamers were selected against an affinity column containing a farnesylated peptide modeled after the carboxyl terminus of K ras, the major oncogenic form of this small G protein family. After 10-rounds of selection, 25% of the RNA applied to the column could be specifically eluted. Sequence analysis of the binding RNA aptamers revealed two consensus sequences--GGGUGGG and GGGAGG. Quantitative fluorescence binding studies on two of the high-affinity aptamers, showed a binding affinities of 139 nM and 0.93 microM, respectively for the farnesylated peptide. Binding to the nonfarnesylated peptide was at least 10-fold weaker, showing that the aptamers can recognize the hydrophobic farnesyl moiety. High affinity aptamers could be useful in specifically interfering with oncogenic ras function in particular, and G proteins in general.