Here, we report the identification, cloning, and functional characterization of three Caenorhabditis elegans G proteincoupled pigment dispersing factor (PDF) receptors, which we designated as Ce_PDFR-1a, -b, and -c. They represent three splice isoforms of the same gene (C13B9.4), which share a high degree of similarity with the Drosophila PDF receptor and are distantly related to the mammalian vasoactive intestinal peptide receptors (VPAC2) and calcitonin receptors. In a reverse pharmacological screen, three bioactive C. elegans neuropeptides, which were recently identified as the Drosophila PDF orthologues, were able to activate these receptors in a dose-dependent manner with nanomolar potency (isoforms a and b). Integrated green fluorescent protein reporter constructs reveal the expression of these PDF receptors in all body wall muscle cells and many head and tail neurons involved in the integration of environmental stimuli and the control of locomotion. Using a custom data analysis system, we demonstrate the involvement of this newly discovered neuropeptide signaling system in the regulation of locomotor behavior. Overexpression of PDF-2 phenocopies the locomotor defects of a PDF-1 null mutant, suggesting that they elicit opposite effects on locomotion through the identified PDF receptors. Our findings strengthen the hypothesis that the PDF signaling system, which imposes the circadian clock rhythm on behavior in Drosophila, has been functionally conserved throughout the protostomian evolutionary lineage.The neuropeptide pigment dispersing factor (PDF) 3 was initially discovered in crustaceans (as pigment-dispersing hormone), where it drives a daily rhythm of color changes (1). Thereafter, highly conserved PDF peptides were identified in many species of insects and recently also in nematodes (2). 4PDF is a crucial component of the insect circadian clock and has been characterized as a putative output factor, controlling daily rhythms in locomotor activity (3, 4). In 2005, three independent studies identified CG13758, a class B peptide G protein-coupled receptor (GPCR), as the receptor for PDF in Drosophila melanogaster (PDFR) (5-7). It is related to the mammalian VIP receptor (VPAC2) and to the calcitonin receptor, both of which are expressed in the mammalian master clock. Fly PDFR mutants and flies lacking PDF both exhibit severe deficits in free-running locomotor rhythms (4 -6). Recently, 3 endogenous PDF-like neuropeptides were discovered in the free-living nematode model organism C. elegans.4 They are expressed mainly in neurons involved in chemosensation, mechanosensation, oxygen sensing, and locomotion. Circadian analysis revealed that at least two of these peptides (e.g. PDF-1a and -b) are involved in the control of daily locomotor rhythms in C. elegans.4 Mutants lacking PDF-1 mimic the behavioral phenotype of Drosophila PDF mutants with respect to free-running locomotor rhythms. This led us to the hypothesis that the PDF signaling system, which imposes the clock rhythm on behavior, may be functionally...

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We previously demonstrated that the oral antipsoriatic dimethylfumarate is an inhibitor of cytokine-induced adhesion molecule expression in endothelial HUVEC cells. We now report the inhibitory effect of dimethylfumarate on tumor-necrosis-factor-alpha- or interleukin-1 alpha-induced intercellular adhesion molecule 1 expression in normal human dermal fibroblasts. Western blots of normal human dermal fibroblast cytoplasmic extracts showed that dimethylfumarate has minor effects on the I kappa B alpha, beta and epsilon proteins: their cytokine-induced degradation and resynthesis is only slowed down, an effect most prominently observed for I kappa B beta. No inhibitory effect of dimethylfumarate was observed on cytokine-induced RelA/p65 or c-Rel accumulation in nuclear extracts of cytokine-treated normal human dermal fibroblast cells. In contrast, cytokine-induced nuclear factor kappa B1/p50 nuclear accumulation was specifically inhibited by dimethylfumarate. This inhibitory effect on nuclear factor kappa B1 nuclear localization in normal human dermal fibroblasts proved sufficient to inhibit nuclear factor kappa B1-RelA binding to nuclear factor kappa B consensus oligonucleotides in DNA binding assays. Likewise, cytokine-induced activation of a pNF kappa B::luciferase reporter construct in transiently transfected normal human dermal fibroblasts was inhibited by dimethylfumarate. The observations support a mechanistic model for the oral antipsoriatic dimethylfumarate in which lowering of nuclear factor kappa B1 leads to changes in the nuclear factor kappa B1-RelA nuclear balance and inhibition of cytokine-induced adhesion molecule expression in normal human dermal fibroblasts.