Specific Recruitment of Antigen-presenting Cells by Chemerin, a Novel Processed Ligand from Human Inflammatory Fluids

Dendritic cells (DCs) and macrophages are professional antigen-presenting cells (APCs) that play key roles in both innate and adaptive immunity. ChemR23 is an orphan G protein–coupled receptor related to chemokine receptors, which is expressed specifically in these cell types. Here we present the characterization of chemerin, a novel chemoattractant protein, which acts through ChemR23 and is abundant in a diverse set of human inflammatory fluids. Chemerin is secreted as a precursor of low biological activity, which upon proteolytic cleavage of its COOH-terminal domain, is converted into a potent and highly specific agonist of ChemR23, the chemerin receptor. Activation of chemerin receptor results in intracellular calcium release, inhibition of cAMP accumulation, and phosphorylation of p42–p44 MAP kinases, through the Gi class of heterotrimeric G proteins. Chemerin is structurally and evolutionary related to the cathelicidin precursors (antibacterial peptides), cystatins (cysteine protease inhibitors), and kininogens. Chemerin was shown to promote calcium mobilization and chemotaxis of immature DCs and macrophages in a ChemR23-dependent manner. Therefore, chemerin appears as a potent chemoattractant protein of a novel class, which requires proteolytic activation and is specific for APCs

Patterns of declining zooplankton energy in the Northeast Atlantic as an indicator for marine survival of Atlantic salmon

Return rates of Atlantic salmon (Salmo salar) from the sea to European rivers have declined in recent decades. The first months at sea are critical for growth and survival; recent evidence suggests that reduced food availability may be a contributory factor to the observed declines. Here, zooplankton abundance data are used to derive a measure of prey energy available to forage fish prey of salmon during early marine migration. This zooplankton prey energy has significantly and dramatically declined over much of the Northeast Atlantic, and specifically within key salmon migration domains, over the past 60 years. Marine return rates from a set of southern European populations are found to exhibit clustering not entirely predictable from geographical proximity. Variability in grouped return rates from these populations is correlated with zooplankton energy on a range of scales, demonstrating the potential use of zooplankton energy as an indicator of salmon marine survival. Comparison with environmental variables derived from ocean model reanalysis data suggests zooplankton energy is regulated by a combination of climate change impacts on ecosystem productivity and multi-decadal variability in water mass influence along the migration routes

Profiling the alkaline membrane proteome of Caulobacter crescentus with two-dimensional electrophoresis and mass spectrometry

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Sequence dependent fragmentation of peptides generated by MALDI quadrupole time-of-flight (MALDI Q-TOF) mass spectrometry and its implications for protein identification**Dedicated to the memory of Bob Bordoli

AbstractA study has been undertaken to evaluate the usefulness of MALDI Q-TOF data for protein identification. The comparison of MS data of protein digests obtained on a conventional MALDI TOF instrument to the MS data from the MALDI Q-TOF reveal peptide patterns with similar intensity ratios. However, comparison of MS/MS Q-TOF data produced by nanoelectrospray versus MALDI reveals striking differences. Peptide fragment ions obtained from doubly charged precursors produced by nanoelectrospray are mainly y-type ions with some b-ions in the lower mass range. In contrast, peptide fragment ions produced from the singly charged ions originating from the MALDI source are a mixture of y-, b- and a-ions accompanied by ions resulting from neutral loss of ammonia or water. The ratio and intensity of these fragment ions is found to be strongly sequence dependent for MALDI generated ions. The singly charged peptides generated by MALDI show a preferential cleavage of the C-terminal bond of acidic residues aspartic and glutamic acid and the N-terminal bond of proline. This preferential cleavage can be explained by the mobile proton model and is present in peptides that contain both arginine and an acidic amino acid. The MALDI Q-TOF MS/MS data of 24 out of 26 proteolytic peptides produced by trypsin or Asp-N digestions were successfully used for protein identification via database searching, thus indicating the general usefulness of the data for protein identification. De novo sequencing using a mixture of 16O/18O water during digestion has been explored and de novo sequences for a number of peptides have been obtained

Ion mobility derived collision cross sections to support metabolomics applications.

Metabolomics is a rapidly evolving analytical approach in life and health sciences. The structural elucidation of the metabolites of interest remains a major analytical challenge in the metabolomics workflow. Here, we investigate the use of ion mobility as a tool to aid metabolite identification. Ion mobility allows for the measurement of the rotationally averaged collision cross-section (CCS), which gives information about the ionic shape of a molecule in the gas phase. We measured the CCSs of 125 common metabolites using traveling-wave ion mobility-mass spectrometry (TW-IM-MS). CCS measurements were highly reproducible on instruments located in three independent laboratories (RSD < 5% for 99%). We also determined the reproducibility of CCS measurements in various biological matrixes including urine, plasma, platelets, and red blood cells using ultra performance liquid chromatography (UPLC) coupled with TW-IM-MS. The mean RSD was < 2% for 97% of the CCS values, compared to 80% of retention times. Finally, as proof of concept, we used UPLC-TW-IM-MS to compare the cellular metabolome of epithelial and mesenchymal cells, an in vitro model used to study cancer development. Experimentally determined and computationally derived CCS values were used as orthogonal analytical parameters in combination with retention time and accurate mass information to confirm the identity of key metabolites potentially involved in cancer. Thus, our results indicate that adding CCS data to searchable databases and to routine metabolomics workflows will increase the identification confidence compared to traditional analytical approaches

The metastasis suppressor gene KiSS-1 encodes kisspeptins, the natural ligands of the orphan G protein-coupled receptor GPR54

Natural peptides displaying agonist activity on the orphan G protein-coupled receptor GPR54 were isolated from human placenta. These 54-, 14,- and 13-amino acid peptides, with a common RF-amide C terminus, derive from the product of KiSS-1, a metastasis suppressor gene for melanoma cells, and were therefore designated kisspeptins. They bound with low nanomolar affinities to rat and human GPR54 expressed in Chinese hamster ovary K1 cells and stimulated PIP(2) hydrolysis, Ca(2+) mobilization, arachidonic acid release, ERK1/2 and p38 MAP kinase phosphorylation, and stress fiber formation but inhibited cell proliferation. Human GPR54 was highly expressed in placenta, pituitary, pancreas, and spinal cord, suggesting a role in the regulation of endocrine function. Stimulation of oxytocin secretion after kisspeptin administration to rats confirmed this hypothesis.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe