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  • 1
    Electronic Resource
    Electronic Resource
    Stable Expression of the Cloned Rat Brain Neurotensin Receptor into Fibroblasts: Binding Properties, Photoaffinity Labeling, Transduction Mechanisms, and Internalization (1994)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 63 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The study of the pharmacological, biochemical, and transduction properties of the cloned rat brain neurotensin receptor was carried out in thymidine kinase mutant fibroblasts stably transfected with the receptor cDNA. The interaction of neurotensin with transfected fibroblasts leads to a concentration-dependent stimulation of phosphatidylinositol hydrolysis and intracellular calcium. These effects are totally inhibited by the nonpeptide neurotensin antagonist SR48692. By contrast, this receptor remains unable to modulate intracellular levels of cyclic nucleotides. The transfected neurotensin receptor can be solubilized in an active form by digitonin with an identical pharmacological profile, whereas the detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propane-sulfonic acid is unable to solubilize the binding activity. The binding of iodinated neurotensin to transfected fibroblasts bearing the cloned receptor remains partly undissociated even after an acid washing step, indicating that the transfected neurotensin receptor retains the capacity to be internalized according to a temperature-dependent mechanism. Indeed, the sequestration of the neurotensin-receptor complex can be blocked by phenylarsine oxide. Finally, photoaffinity labeling experiments reveal that the cloned rat brain neurotensin receptor is expressed under two forms with molecular masses of 50 and 60 kDa. Labeling and internalization of these two proteins are totally blocked by the neurotensin antagonist SR48692.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.63010019.x
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  • 2
    Electronic Resource
    Electronic Resource
    Stimulation of Inositol Phosphate Production by Neurotensin in Neuroblastoma N1E115 Cells: Implication of GTP-Binding Proteins and Relationship with the Cyclic GMP Response (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 49 (1987), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The association of neurotensin to its receptor in differentiated neuroblastoma N1E115 cells led to a fast and transitory increase of the intracellular concentration in inositol trisphosphate and inositol bisphosphate, followed by a slower and more stable increase in inositol monophosphate. The action of inositol 1,4,5-trisphosphate on digitonin-permeabilized N1E115 cells resulted in a stimulation of cyclic GMP levels that mimicked that induced by neurotensin. Therefore, the cyclic GMP stimulation is probably a consequence of the initial inositol trisphosphate formation triggered by neurotensin. Fluoroaluminate ions and pertussis toxin had the capacity to modulate positively and negatively, respectively, the formation of inositol trisphosphate induced by neurotensin, indicating that GTP-binding proteins are involved in the regulation of inositol phosphate levels by neurotensin receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1987.tb09986.x
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  • 3
    Electronic Resource
    Electronic Resource
    High-Affinity Receptor Sites and Rapid Proteolytic Inactivation of Neurotensin in Primary Cultured Neurons (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 47 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The present article describes the interaction of neurotensin with specific receptors in pure primary cultured neurons and the mechanisms by which this peptide is inactivated by these cells. Neurotensin binding sites are not detectable in nondifferentiated neurons and appear during maturation. The binding at 37°C of [monoiodo-Tyr3 neurotensin to monolayers of neurons 96 h after plating is saturable and characterized by a dissociation constant of 300 pM and a maximal binding capacity of 178 fmol/mg of protein. The binding parameters as well as the specificity of these receptors toward neurotensin analogues reveal close similarities between the binding sites present in primary cultured neurons and those described in other membrane preprations or cells. Neurotensin is rapidly degraded by primary cultured neurons. The sites of primary inactivating cleavages are the Pro7-Arg8, Arg8-Arg9, and Pro10-Tyr11 bonds. Proline endopeptidase is totally responsible for the cleavage at the Pro7-Arg8 bond and contributes to the hydrolysis mainly at the Pro10-Tyr11 site. However, the latter breakdown is also generated by a neurotensin-degrading neutral metallopeptidase. The cleavage at the Arg8-Arg9 bond is due to a peptidase that can be specifically inhibited by N-[1 (R, S)-carboxy-2-phenylethyl]-alanyl-alanyl-phenylalanyl-p-aminobenzoate. The secondary processing occurring on neurotensin degradation products are: (1) a bestatin-sensitive aminopeptidasic conversion of neurotensin, 11-13 to free Tyr11, and (2) a rapid cleavage of neurotensin8-13 by proline endopeptidase. A model for the inactivation of neurotensin in primary cultured neurons is proposed and compared to that previously described for purified rat brain synaptic membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb13083.x
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  • 4
    Electronic Resource
    Electronic Resource
    Neurotensin-Metabolizing Peptidases in Rat Fundus Plasma Membranes (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 49 (1987), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The mechanisms by which neurotensin (NT) was inactivated by rat fundus plasma membranes were characterized. Primary inactivating cleavages occurred at the Arg8-Arg9, Pro10-Tyr11, and Ile12-Leu13 peptidyl bonds. Hydrolysis at the Arg8-Arg9 bond was fully abolished by the use of N-[1 (R,S)-carboxy-2-phenylethyl]-alanyl-alanyl-phenylalanine-p-aminobenzoate, a result indicating the involvement at this site of a recently purified soluble metallopeptidase. Hydrolysis of the Pro10-Tyr11 bond was totally resistant to N-benzyloxycarbonyl-prolyl-prolinal and thiorphan, an observation suggesting that the peptidase responsible for this cleavage was different from proline endopeptidase and endopeptidase 24.11 and might correspond to a NT-degrading neutral metallopeptidase recently isolated from rat brain synaptic membranes. The enzyme acting at the Ile12-Leu13 bond has not yet been identified. Secondary cleavages occurring on NT degradation products were mainly generated by bestatin-sensitive aminopeptidases and post-proline dipeptidyl aminopeptidase. The content in NT-metabolizing peptidases present in rat fundus plasma membranes is compared with that previously established for purified rat brain synaptic membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1987.tb02893.x
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  • 5
    Electronic Resource
    Electronic Resource
    Degradation of Neurotensin by Rat Brain Synaptic Membranes: Involvement of a Thermolysin-Like Metalloendopeptidase (Enkephalinase), Angiotensin-Converting Enzyme, and Other Unidentified Peptidases (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 41 (1983), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Neurotensin was inactivated by membrane-bound and soluble degrading activities present in purified preparations of rat brain synaptic membranes. Degradation products were identified by HPLC and amino acid analysis. The major points of cleavage of neurotensin were the Arg8-Arg9, Prol0-Tyr11, and Tyr11-Ile12 peptide bonds with the membrane-bound activity and the Arg8-Arg9 and Pro10-Tyr11 bonds with the soluble activity. Several lines of evidence indicated that the cleavage of the Arg8-Arg9 bond by the membrane-bound activity resulted mainly from the conversion of neurotensin1–10 to neurotensin1–8 by a dipeptidyl carboxypeptidase. In particular, captopril inhibited this cleavage with an IC50 (5.7 nM) close to its K1 (7 nM) for angiotensin-converting enzyme. Thiorphan inhibited the cleavage at the Tyr11-−Ile12 bond by the membrane-bound activity with an IC50 (17 nM) similar to its Ks (4.7 nM) for enkephalinase. Both cleavages were inhibited by 1,10-phenanthroline. These and other data suggested that angiotensin-converting enzyme and a thermolysin-like metalloendopeptidase (enkephalinase) were the membrane-bound peptidases responsible for cleavages at the Arg8-Arg9 and Tyr11-Ile12 bonds, respectively. In contrast, captopril had no effect on the cleavage at the Arg8-Arg9 bond by the soluble activity, indicating that the enzyme responsible for this cleavage was different from angiotensin-converting enzyme. The cleavage at the Pro10-Tyr11 bond by both the membrane-bound and the soluble activities appeared to be catalyzed by an endopeptidase different from known brain proline endopeptidases. The possibility is discussed that the enzymes described here participate in physiological mechanisms of neurotensin inactivation at the synaptic level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1983.tb04753.x
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  • 6
    Electronic Resource
    Electronic Resource
    Constitutive expression of CCR2 chemokine receptor and inhibition by MCP-1/CCL2 of GABA-induced currents in spinal cord neurones (2005)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 95 (2005), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In the CNS, immune-like competent cells (microglia and astrocytes) were first described as potential sites of chemokine synthesis, but more recent evidence has indicated that neurones might also express chemokines and their receptors. The aim of the present work was to investigate further, both in vivo and in vitro, CC Chemokine Family Receptor 2 (CCR2) expression and functionality in rat spinal cord neurones. First, we demonstrated by RT–PCR and western blot analysis that CCR2 mRNA and protein were present in spinal extracts. Furthermore, we showed by immunolabelling that CCR2 was exclusively expressed by neurones in spinal sections of healthy rat. Finally, to test the functionality of CCR2, we used primary cultures of rat spinal neurones. In this model, similar to what was observed in vivo, CCR2 mRNA and protein were expressed by neurones. Cultured neurones stimulated with Monocyte Chemoattractant Protein-1 (MCP-1)/CCL2, the best characterized CCR2 agonist, showed activation of the Akt pathway. Finally, patch-clamp recording of cultured spinal neurones was used to investigate whether MCP-1/CCL2 could modulate their electrophysiological properties. MCP-1 alone did not affect the electrical properties of spinal neurones, but potently and efficiently inhibited GABAA-mediated GABAergic responses in these neurones. These data constitute the first demonstration of a modulatory role of MCP-1 on GABAergic neurotransmission and contribute to our understanding of the roles of CCR2 and MCP-1/CCL2 in spinal cord physiology, in particular with respect to nociceptive transmission, as well as the implication of this chemokine in neuronal adaptation or dysfunction during neuropathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.2005.03431.x
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  • 7
    Electronic Resource
    Electronic Resource
    High-Affinity Neurotensin Binding Sites in Differentiated Neuroblastoma N1E115 Cells (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 42 (1984), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: This paper describes the interaction of neurotensin with mouse neuroblastoma N1E115 cells. Neurotensin binding sites are undetectable in nondifferentiated neuroblastoma cells. They appear during cell differentiation in the presence of a low serum concentration and dimethyl sulfoxide, and reach a maximal level after 50–60 h of incubation under these conditions. The binding of monoiodo[Trp11]neurotensin to homogenates of differentiated N1E115 cells is specific, saturable, and reversible. The interaction is characterized by a dissociation constant of 150 pM and a maximal binding capacity of 9 fmol/mg of protein at 0°C, pH 7.5. These binding parameters, as well as the specificity toward a series of neurotensin analogues, are similar for neurotensin receptors in N1E115 cells and for the high-affinity binding sites that had been previously characterized in rat brain synaptic membranes by means of the same radiolabeled ligand. The presence of high-affinity binding sites for neurotensin in the neuroblastoma N1E115 provides a useful model to study the cellular responses that are generated by the association of neurotensin to its receptor in electrically excitable cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1984.tb12715.x
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  • 8
    Electronic Resource
    Electronic Resource
    The Arg617–Arg618 cleavage site in the C-terminal domain of PC1 plays a major role in the processing and targeting of the enzyme within the regulated secretory pathway (2003)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 85 (2003), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The C-terminal domain of the prohormone convertase PC1 is involved in targeting of the enzyme to secretory granules in neuroendocrine cells and is subsequently processed in this compartment at an Arg617-Arg618 site. Three other dibasics are found in the C-terminal domain of mouse PC1. Here, we examined the role of the four dibasics in targeting PC1 to secretory granules. All 15 possible combinations of dibasic mutations were performed. Wild-type (WT) and mutant PC1 were stably expressed in neuroendocrine PC12 cells that lacked endogenous PC1. Processing, secretion and intracellular localization of PC1 and its mutants were analyzed. Leaving intact Arg617-Arg618 and mutating any combination of the three other dibasics yielded proteins that were stored and processed in secretory granules, similarly to WT PC1. Mutating Arg617-Arg618 alone or with any one of the three remaining dibasics generated proteins that were efficiently stored in secretory granules but were not processed further. Mutating Arg617-Arg618 with more than one of the remaining dibasics produced proteins that reached the TGN but were not stored in secretory granules and exited the cells through the constitutive secretory pathway. These data demonstrate that the Arg617-Arg618 plays a prominent role in targeting PC1 to secretory granules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2003.01823.x
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  • 9
    Electronic Resource
    Electronic Resource
    Altered processing of the neurotensin/neuromedin N precursor in PC2 knock down mice: a biochemical and immunohistochemical study (2002)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 82 (2002), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neurotensin (NT) and neuromedin N (NN) are generated by endoproteolytic cleavage of a common precursor molecule, pro-NT/NN. To gain insight into the role of prohormone convertases PC1, PC2, and PC7 in this process, we investigated the maturation of pro-NT/NN in the brain of PC7 (PC7−/–), PC2 (PC2–/–), and/or PC1 (PC1+/– and PC2–/–; PC1+/–) knock down mice. Inactivation of the PC7 gene was without effect, suggesting that this convertase is not involved in the processing of pro-NT/NN. By contrast, there was a 15% decrease in NT and a 50% decrease in NN levels, as measured by radioimmunoassay, in whole brain extracts from PC2 null as compared with wild type mice. Using immunohistochemistry, we found that this decrease in pro-NT/NN maturation products was uneven and that it was most pronounced in the medial preoptic area, lateral hypothalamus, and paraventricular hypothalamic nuclei. These results suggest that PC2 plays a critical role in the processing of pro-NT/NN in mouse brain and that its deficiency may be compensated to a regionally variable extent by other convertases. Previous data have suggested that PC1 might be subserving this role. However, there was no change in the maturation of pro-NT/NN in the brain of mice in which the PC1 gene had been partially inactivated, implying that complete PC1 knock down may be required for loss of function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2002.00988.x
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  • 10
    Electronic Resource
    Electronic Resource
    Highly regionalized distribution of stromal cell-derived factor-1/CXCL12 in adult rat brain: constitutive expression in cholinergic, dopaminergic and vasopressinergic neurons (2003)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 18 (2003), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The stromal cell-derived factor-1 (SDF-1)/CXCL12 and its receptor CXCR4 are key modulators of immune functions. In the nervous system, SDF-1/CXCL12 is crucial for neuronal guidance in developing brain, intercellular communication and the neuropathogenesis of acquired immunodeficiency syndrome. However, cerebral functions of SDF-1/CXCL12 in adult brain are poorly understood. The understanding of its role in the adult brain needs a detailed neuroanatomical mapping of SDF-1/CXCL12. By dual immunohistochemistry we demonstrate that this chemokine is constitutively expressed not only in astrocytes and microglia but also in neurons, in discrete neuroanatomical regions. Indeed, neuronal expression of SDF-1/CXCL12 is mainly found in cerebral cortex, substantia innominata, globus pallidus, hippocampus, paraventricular and supraoptic hypothalamic nuclei, lateral hypothalamus, substantia nigra and oculomotor nuclei. Moreover, we provide the first evidence that SDF-1/CXCL12 is constitutively expressed in cholinergic neurons in the medial septum and substantia innominata and in dopaminergic neurons in substantia nigra pars compacta and the ventral tegmental area. Interestingly we also show, for the first time, a selective co-localization of SDF-1/CXCL12 with vasopressin-expressing neurons in the supraoptic and paraventricular hypothalamic nuclei. In addition, in the lateral hypothalamic area, SDF-1/CXCL12 was found to be located on melanin concentrating hormone-expressing neurons. Altogether, these original data suggest that SDF-1/CXCL12 could be a modulatory neuropeptide regulating both central cholinergic and dopaminergic systems. In addition, a key role for SDF-1/CXCL12 in neuroendocrine regulation of vasopressin-expressing neurons represents an exciting new field of research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2003.02893.x
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