Inflammatory cytokines tumor necrosis factor-␣ and interleukin-1 trigger the ceramide signaling pathway, initiated by neutral sphingomyelinase-elicited hydrolysis of cell membrane phospholipid sphingomyelin to ceramide, a new lipid second messenger. Here, we show that triggering the ceramide pathway by sphingomyelinase or C 2 -and C 6 -ceramide enhances collagenase-1 (matrix metalloproteinase-1; MMP-1) gene expression by fibroblasts. C 2 -ceramide activates three distinct mitogen-activated protein kinases (MAPKs) in dermal fibroblasts, i.e. extracellular signal-regulated kinase 1/2 (ERK1/2), stress-activated protein kinase/Jun N-terminal-kinase (SAPK/JNK), and p38. Stimulation of MMP-1 promoter activity by C 2 -ceramide is dependent on the presence of a functional AP-1 cis-element and is entirely inhibited by overexpression of MAPK inhibitor, dual specificity phosphatase CL100 (MAPK phosphatase-1). Activation of MMP-1 promoter by C 2 -ceramide is also effectively inhibited by kinase-deficient forms of ERK1/2 kinase (MEK1/2) activator Raf-1, ERK1 and ERK2, SAPK/ JNK activator SEK1, or SAPK␤. In addition, ceramidedependent induction of MMP-1 expression is potently prevented by PD 98059, a selective inhibitor of MEK1 activation, and by specific p38 inhibitor SB 203580. These results show that triggering the ceramide signaling pathway activates MMP-1 gene expression via three distinct MAPK pathways, i.e. ERK1/2, SAPK/JNK, and p38, and suggest that targeted modulation of the ceramide signaling pathway may offer a novel therapeutic approach for inhibiting collagenolytic activity, e.g. in inflammatory disorders.

Both treatments efficiently reduced menstrual bleeding. The high continuation rate suggests that the levonorgestrel intrauterine system is comparable with transcervical resection of the endometrium.

In this study we report the activation of c-Jun Nterminal kinase (JNK) in human K562 erythroleukemia cells undergoing hemin-mediated erythroid differentiation, which occurs concomitantly with activation of heat shock factor 2 (HSF2) and leads to a simultaneous in vivo phosphorylation of c-Jun. The activation of JNK occurs through activation of mitogen-activated protein kinase kinase (MKK) 4 and not by activation of MKK7 or inhibition of JNK-directed phosphatases. We have previously shown that overexpression of the HSF2-L L isoform inhibits the activation of HSF2 upon hemin-induced erythroid differentiation. Here we demonstrate that HSF2-L L overexpression blocks the hemin-induced activation of the MKK4-JNK pathway, suggesting an erythroid lineage-specific JNK activation likely to be regulated by HSF2. ß

The first `native' flatworm regulatory peptide, neuropeptide F (NPF) has recently been isolated and sequenced from the cestode Moniezia expansa (see Maule et al., 1991) and the turbellarian Artioposthia triangulata, (see Curry et al., 1992) . NPF belongs to the neuropeptide Y (NPY) superfamily and the antiserum is known to show crossreactivity to the vertebrate neuropeptides of the NPY superfamily. It terminates in RFamide, like the invertebrate neuropeptides FMRFamide and RFamide, and may cross-react with neuropeptides of the FMRFamide family . Strong immunoreactivity (IR) to FMRF-and RF-amide has been demonstrated in members of most flatworm groups . In the present study, IR to NPF (diluted 1 :1000) is demonstrated in Stenostomum leucops (Catenulida) and Microstomum lineare (Macrostomida) . The controls included : omitting primary antibody, using non-immune serum and liquid-phase absorption with the homologous antigen (1000 ng ml -1 ) . The NPF IR pattern was compared to the FMRF and RF-amide IR patterns in order to reveal differences or co-localization . In addition, the sequential appearance of NPF-positive cells in developing zooids was followed and double staining with a-5-HT made to complete the study.

No abstract

Jurkat T cells undergo rapid apoptosis upon stimulation of the Fas/APO-1 (CD95) receptor. We examined the role of the mitogen-activated protein kinase (MAPK) cascade as a negative regulator of Fas-mediated apoptosis. To this end, we used both physiologic and artificial activators of MAPK, all of which activate MAPK by distinct routes. MAPK activity could be efficiently elevated by two T cell mitogens, the lectin PHA and an agonistic Ab to the T cell receptor complex as well as by the type 1 and 2A phosphatase inhibitor, calyculin A, and the protein kinase C-activating phorbol ester, tetradecanoyl phorbol acetate. All these treatments were effective in preventing the characteristic early and late features of Fas-mediated apoptosis, including activation of caspases. Our results indicate that the elevated MAPK activities intervene upstream of caspase activation. The degree of MAPK activation by the different stimuli used in our study corresponds well to their potency to inhibit apoptosis, indicating that MAPK activation serves as an efficient modulator of Fas-mediated apoptosis. The role of MAPK in modulation of Fas-mediated apoptosis was further corroborated by transient transfection with constitutively active MAPK kinase, resulting in complete inhibition of the Fas response, whereas transfection with a dominant negative form of MAPK kinase had no effect. Furthermore, the apoptosis inhibitory effect of the MAPK activators could be abolished by the specific MAPK kinase inhibitor PD 098059. Modulation of Fas responses by MAPK signaling may determine the persistence of an immune response and may explain the insensitivity of recently activated T cells to Fas receptor stimulation.

No abstract

Two years ago the first platyhelminth regulatory peptide, neuropeptide F (NPF), was isolated from the tapeworm Moniezia expansa by Maule et al. (1991) . NPF is a 39 amino acid peptide with a C terminal phenylalaninamide . NPF is the first platyhelminth neuropeptide to be sequenced fully . Preabsorption with NPF quenches the immunostaining with anti-FMRF-amide and anti-bovine PP (Halton et al. 1992) . As the first authentic flatworm neuropeptide, the occurrence and distribution of NPF along the whole flatworm line are under investigation. Both free-living and parasitic flatworms are being studied . So far NPF-immunoreactivity has been reported from three free-living flatworms (see Grahn et al., 1995) and from four parasitic flatworms (Marks et al., 1993) .FMRF-and RF-amide immunoreactive (IR) nerve cells and fibres are common in the gull-tapeworm Diphyllobothrium dendriticum . In order to test whether the patterns for NPF-and RF-immunoreactivity co-localize in the gull-tapeworm, immunostaining with anti-NPF and anti-RF were performed . To broaden the study, adult Proteochepalus exiguus from the intestine of whitefish were included in the experiment.