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  • 1
    Keywords: brain ; RECEPTOR ; CELLS ; Germany ; NETWORKS ; SYSTEM ; TOOL ; DISTINCT ; PROTEIN ; PROTEINS ; TRANSDUCTION ; COMPLEX ; MESSENGER-RNA ; RAT ; signal transduction ; MEMBRANE ; SIGNAL-TRANSDUCTION ; mass spectrometry ; MASS-SPECTROMETRY ; CHROMATOGRAPHY ; PROTEOMIC ANALYSIS ; glutathione-S-transferase ; BINDING PROTEIN ; signaling ; molecular ; NEURONS ; analysis ; cilia ; ENGLAND ; XENOBIOTIC-METABOLIZING ENZYMES ; affinity chromatography ; calcium-calmodulin ; CHEMOSENSORY CILIA ; NUCLEOTIDE-GATED CHANNEL ; olfaction ; olfactory receptor neurons ; PHOSPHOLIPID-BINDING ; SENSORY NEURONS
    Abstract: The olfactory neuroepithelium represents a unique interface between the brain and the external environment. Olfactory function comprises a distinct set of molecular tasks: sensory signal transduction, cytoprotection and adult neurogenesis. A multitude of biochemical studies has revealed the central role of Ca2+ signaling in the function of olfactory receptor neurons (ORNs). We set out to establish Ca2+-dependent signaling networks in ORN cilia by proteomic analysis. We subjected a ciliary membrane preparation to Ca2+/calmodulin-affinity chromatography using mild detergent conditions in order to maintain functional protein complexes involved in olfactory Ca2+ signaling. Thus, calmodulin serves as a valuable tool to gain access to novel Ca2+-regulated protein complexes. Tandem mass spectrometry (nanoscale liquid-chromatography-electrospray injection) identified 123 distinct proteins. Ninety-seven proteins (79%) could be assigned to specific olfactory functions, including 32 to sensory signal transduction and 40 to cytoprotection. We point out novel perspectives for research on the Ca2+-signaling networks in the olfactory system of the rat. (C) 2007 IBRO. Published by Elsevier Ltd. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 18155848
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  • 2
    Keywords: INHIBITION ; PROTEIN ; ACTIVATION ; MECHANISM ; BINDING ; SUBUNIT ; MODULATION ; CALCIUM ; ion channels ; STOICHIOMETRY ; olfactory receptor neurons ; CA2+-DEPENDENT INTERACTIONS ; CNG CHANNELS ; ODOR ADAPTATION ; TERMINAL REGIONS
    Abstract: Cyclic nucleotide-gated (CNG) channels operate as transduction channels in photoreceptors and olfactory receptor neurons. Direct binding of cGMP or cAMP opens these channels which conduct a mixture of monovalent cations and Ca2+. Upon activation, CNG channels generate intracellular Ca2+ signals that play pivotal roles in the transduction cascades of the visual and olfactory systems. Channel activity is controlled by negative feedback mechanisms that involve Ca2+-calmodulin, for which all CNG channels possess binding sites. Here we compare the binding properties of the two LQ-type calmodulin binding sites, both of which are thought to be involved in channel regulation. They reside on the isoforms CNGB1 and CNGA4. The CNGB1 subunit is present in rod photoreceptors and olfactory receptor neurons. The CNGA4 subunit is only expressed in olfactory receptor neurons, and there are conflicting results as to its role in calmodulin-mediated feedback inhibition. We examined the interaction of Ca2+-calmodulin with two recombinant proteins that encompass either of the two LQ sites. Comparing binding properties, we found that the LQ site of CNGB1 binds Ca2+-calmodulin at 10-fold lower Ca2+ levels than the LQ site of CNGA4. Our data provide biochemical evidence against a contribution of CNGA4 to feedback inhibition. In accordance with previous work on photoreceptor CNG channels, our results indicate that feedback control is the exclusive role of the B-subunits in photoreceptors and olfactory receptor neurons
    Type of Publication: Journal article published
    PubMed ID: 21413724
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  • 3
    Keywords: CELLS ; EXPRESSION ; CELL ; Germany ; human ; COMMON ; SYSTEM ; GENE ; PROTEIN ; PROTEINS ; MOLECULAR CHARACTERIZATION ; FAMILY ; PROTEIN FAMILIES ; PROTEIN FAMILY ; CYCLE ; NERVOUS-SYSTEM ; HUMANS ; EVOLUTION ; LOCALIZATION ; STEM-CELLS ; NETHERLANDS ; OF-FUNCTION ; ORIGIN ; PATTERN ; CIRCADIAN OUTPUT ; ECHINATA ; FMR1 ; FMRP ; FXR ; FXR2 ; Hydractinia ; HYDROID HYDRACTINIA ; hydrozoa ; LIFE-CYCLE ; NEURONS ; RIBOSOMES ; RNA-BINDING ; RNA-BINDING PROTEIN ; TRANSLATION
    Abstract: The fragile X mental retardation syndrome in humans is caused by a mutational loss of function of the fragile X mental retardation gene 1 (FMR1). FMR1 is an RNA-binding protein, involved in the development and function of the nervous system. Despite of its medical significance, the evolutionary origin of FMR1 has been unclear. Here, we report the molecular characterization of HyFMR1, an FMR1 orthologue, from the cnidarian hydroid Hydractinia echinata. Cnidarians are the most basal metazoans possessing neurons. HyFMR1 is expressed throughout the life cycle of Hydractinia. Its expression pattern correlates to the position of neurons and their precursor stem cells in the animal. Our data indicate that the origin of the fraxile X related (FXR) protein family dates back at least to the common ancestor of cnidarians and bilaterians. The lack of FXR proteins in other invertebrates may have been due to gene loss in particular lineages. (C) 2004 Elsevier B.V. All rights reserved
    Type of Publication: Journal article published
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  • 4
    Keywords: EXPRESSION ; Germany ; CLASSIFICATION ; CDNA ; ENZYMES ; HYBRIDIZATION ; TISSUE ; FAMILY ; primary ; TISSUES ; STAGE ; IN-SITU ; RT-PCR ; IMMUNITY ; HOST-DEFENSE ; in situ hybridization ; DEFENSE ; pathogen ; PATHOGENS ; ECHINATA ; Hydractinia ; HYDROID HYDRACTINIA ; chitin ; allorecognition ; GLYCOSYL HYDROLASES ; periderm
    Abstract: Chitinases are enzymes that degrade chitin, the second most abundant polymer in nature. They are ubiquitous among living organisms where they play a role in development, food-digestion and innate immunity. We have cloned and characterized the first cnidarian chitinase cDNA from the hydroid Hydractinia. The Hydractinia chitinase exhibits a typical secreted family 18 hydrolases primary structure. In situ hybridization and RT-PCR experiments showed that it is exclusively expressed in ectodermal tissues of the animal, only following metamorphosis while undetectable in embryonic and larval stages. Most prominent expression was observed in the stolonal compartment of colonies, structures that are covered by a chitinous periderm. Chitinase mRNA was detected in new branching points along stolons and in hyperplastic stolons indicating a role of the enzyme in pattern formation and allorecognition. It was also expressed in polyps where it was mostly restricted to their basal portion. This expression pattern suggests that HyChitI also fulfills a role in host defense, probably against fungal and nematode pathogens. Endodermal expression of HyChitI has never been observed, suggesting that the enzyme does not participate in food-digestion. (C) 2004 Elsevier Ltd. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 15236928
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  • 5
    Keywords: CELLS ; EXPRESSION ; DISTINCT ; GENE ; GENES ; PROTEIN ; PROTEINS ; FAMILY ; DOMAIN ; IDENTIFICATION ; EVOLUTION ; CLUSTER ; Hydractinia ; function ; CNIDARIAN ; HYDRA ; CATALYTIC DOMAIN ; HATCHING ENZYME ; MEPRIN ; ORYZIAS-LATIPES ; PROCOLLAGEN C-PROTEINASE ; ZINC-ENDOPEPTIDASE
    Abstract: Astacin-like metalloproteases are ubiquitous in the animal kingdom but their phylogenetic relationships and ancient functions within the Metazoa are unclear. We have cloned and characterized four astacin-like cDNAs from the marine hydroid Hydractinia echinata and performed a database search for related genes in the draft genome sequence of the sea anemone Nematostella vectensis. These sequences and those of higher animals' astacins were subjected to phylogenetic analysis revealing five clusters within the Eumetazoa. The bone morphogenetic protein-1/tolloid-like astacins were represented in all eumetazoan phyla studied. The meprins were only found in vertebrates and cnidarians. Two clusters were taxon-specific, and one cluster represented astacins, which probably evolved after the split of the Cnidaria. Interestingly, grouping of astacins according to the protease catalytic domain alone resulted in clusters of proteins with similar overall domain architecture. The Hydractinia astacins were expressed in distinct cells during metamorphosis and some also during wound healing. Previously characterized cnidarian astacins also act during development. Based on our phylogeny, however, we propose that the developmental function of most of them is not homologous to the developmental function assigned to higher animals' astacins
    Type of Publication: Journal article published
    PubMed ID: 16509900
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  • 6
    Keywords: RECEPTOR ; Germany ; PATHWAY ; PROTEIN ; PROTEINS ; COMPLEX ; RAT ; signal transduction ; SIGNAL ; MOUSE ; MEMBRANE ; SIGNAL-TRANSDUCTION ; mass spectrometry ; PROTEOMIC ANALYSIS ; signaling ; NEURONS ; EPITHELIUM ; NUCLEOTIDE-GATED CHANNEL ; olfactory receptor neurons ; sensory cilia ; ADENYLYL-CYCLASE ; CHLORIDE ACCUMULATION ; MAMMALIAN ODORANT RECEPTORS ; ORGANELLAR PROTEOMICS
    Abstract: Olfactory sensory neurons expose to the inhaled air chemosensory cilia which bind odorants and operate as transduction organelles. Odorant receptors in the ciliary membrane activate a transduction cascade which uses cAMP and Ca2+ for sensory signaling in the ciliary lumen. Although the canonical transduction pathway is well established, molecular components for more complex aspects of sensory transduction, like adaptation, regulation, and termination of the receptor response have not been systematically identified. Moreover, open questions in olfactory physiology include how the cilia exchange solutes with the surrounding mucus, assemble their highly polarized set of proteins, and cope with noxious substances in the ambient air. A specific ciliary proteome would promote research efforts in all of these fields. We have improved a method to detach cilia from rat olfactory sensory neurons and have isolated a preparation specifically enriched in ciliary membrane proteins. Using LC-ESI-MS/MS analysis, we identified 377 proteins which constitute the olfactory cilia proteome. These proteins represent a comprehensive data set for olfactory research since more than 80% can be attributed to the characteristic functions of olfactory sensory neurons and their cilia: signal processing, protein targeting, neurogenesis, solute transport, and cytoprotection. Organellar proteomics thus yielded decisive information about the diverse physiological functions of a sensory organelle
    Type of Publication: Journal article published
    PubMed ID: 19086097
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