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Patel DS, Bharatam PV. Divalent N(I) compounds with two lone pairs on nitrogen. J Phys Chem A 2011; 115:7645-55. [PMID: 21650162 DOI: 10.1021/jp111017u] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Carbon with the C(0) state has been reported recently, examples of which were known for the past decades. Silicon in the Si(0) state and phosphorus in the P(I) state are also known experimentally. This prompted us to search for divalent N(I) compounds, which resulted in the identification of ::N(←L)(2)(⊕) systems with bicoordinated nitrogen in the N(I) formal oxidation state. It was found that several biguanide derivatives (especially in their protonated state) belong to this class. Quantum chemical analysis provided the structural details, molecular orbitals, charge localization (vs delocalization) trends, etc. This class of compounds has been found to be characterized by two lone pairs on the central nitrogen, very similar to the central carbon in divalent C(0) compounds (::C(←L)(2)). The new bonding environment for nitrogen reported in this article, divalent nitrogen N(I), is clearly different from the nitrenium ions NR(2)(⊕). The electronic structure and reactivity of representative examples of this novel class of divalent nitrogen N(I) systems (::N(←L)(2)(⊕)) have been analyzed in detail, in terms of molecular orbitals, atomic charges, protonation energies, complexation energies with Lewis acids like BH(3), AlCl(3), and AuCl and compared with those of divalent C(0) systems.
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Affiliation(s)
- Dhilon S Patel
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S. A. S. Nagar (Mohali), Punjab 160 062, India
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Benardais K, Kasem B, Couegnas A, Samama B, Fernandez S, Schaeffer C, Antal MC, Job D, Schweitzer A, Andrieux A, Giersch A, Nehlig A, Boehm N. Loss of STOP protein impairs peripheral olfactory neurogenesis. PLoS One 2010; 5:e12753. [PMID: 20856814 PMCID: PMC2939889 DOI: 10.1371/journal.pone.0012753] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 08/18/2010] [Indexed: 11/19/2022] Open
Abstract
Background STOP (Stable Tubulin-Only Polypeptide) null mice show behavioral deficits, impaired synaptic plasticity, decrease in synaptic vesicular pools and disturbances in dopaminergic transmission, and are considered a neurodevelopmental model of schizophrenia. Olfactory neurons highly express STOP protein and are continually generated throughout life. Experimentally-induced loss of olfactory neurons leads to epithelial regeneration within two months, providing a useful model to evaluate the role played by STOP protein in adult olfactory neurogenesis. Methodology/Principal Findings Immunocytochemistry and electron microscopy were used to study the structure of the glomerulus in the main olfactory bulb and neurogenesis in the neurosensorial epithelia. In STOP null mice, olfactory neurons showed presynaptic swellings with tubulovesicular profiles and autophagic-like structures. In olfactory and vomeronasal epithelia, there was an increase in neurons turnover, as shown by the increase in number of proliferating, apoptotic and immature cells with no changes in the number of mature neurons. Similar alterations in peripheral olfactory neurogenesis have been previously described in schizophrenia patients. In STOP null mice, regeneration of the olfactory epithelium did not modify these anomalies; moreover, regeneration resulted in abnormal organisation of olfactory terminals within the olfactory glomeruli in STOP null mice. Conclusions/Significance In conclusion, STOP protein seems to be involved in the establishment of synapses in the olfactory glomerulus. Our results indicate that the olfactory system of STOP null mice is a well-suited experimental model (1) for the study of the mechanism of action of STOP protein in synaptic function/plasticity and (2) for pathophysiological studies of the mechanisms of altered neuronal connections in schizophrenia.
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Affiliation(s)
- Karelle Benardais
- INSERM U666, Strasbourg, France
- Université de Strasbourg, Faculté de Médecine, Institut d'Histologie, Strasbourg, France
| | - Basem Kasem
- INSERM U666, Strasbourg, France
- Université de Strasbourg, Faculté de Médecine, Institut d'Histologie, Strasbourg, France
| | - Alice Couegnas
- INSERM U666, Strasbourg, France
- Université de Strasbourg, Faculté de Médecine, Institut d'Histologie, Strasbourg, France
| | - Brigitte Samama
- INSERM U666, Strasbourg, France
- Université de Strasbourg, Faculté de Médecine, Institut d'Histologie, Strasbourg, France
- Hôpitaux Universitaires de Strasbourg, Strasbourg, France
- * E-mail:
| | - Sebastien Fernandez
- Université de Strasbourg, Faculté de Médecine, Institut d'Histologie, Strasbourg, France
| | - Christiane Schaeffer
- INSERM U666, Strasbourg, France
- Université de Strasbourg, Faculté de Médecine, Institut d'Histologie, Strasbourg, France
- Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Maria-Cristina Antal
- INSERM U666, Strasbourg, France
- Université de Strasbourg, Faculté de Médecine, Institut d'Histologie, Strasbourg, France
- Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Didier Job
- INSERM U836, Grenoble Institut of Neurosciences, Grenoble, France; iRTSV-GPC, CEA-Grenoble, France; Université Joseph Fourrier, Grenoble, France
| | - Annie Schweitzer
- INSERM U836, Grenoble Institut of Neurosciences, Grenoble, France; iRTSV-GPC, CEA-Grenoble, France; Université Joseph Fourrier, Grenoble, France
| | - Annie Andrieux
- INSERM U836, Grenoble Institut of Neurosciences, Grenoble, France; iRTSV-GPC, CEA-Grenoble, France; Université Joseph Fourrier, Grenoble, France
| | | | | | - Nelly Boehm
- INSERM U666, Strasbourg, France
- Université de Strasbourg, Faculté de Médecine, Institut d'Histologie, Strasbourg, France
- Hôpitaux Universitaires de Strasbourg, Strasbourg, France
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Thompson CJ, Schilling T, Howard MR, Genever PG. SNARE-dependent glutamate release in megakaryocytes. Exp Hematol 2010; 38:504-15. [PMID: 20347926 PMCID: PMC2877886 DOI: 10.1016/j.exphem.2010.03.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 03/12/2010] [Accepted: 03/17/2010] [Indexed: 02/06/2023]
Abstract
Objective The identification of signaling pathways involved in megakaryocytopoiesis is essential for development of novel therapeutics to treat hematological disorders. Following our previous findings that megakaryocytes express functional channel-forming N-methyl-D-aspartate-type glutamate receptors, here we aimed to determine the glutamate release capacity in undifferentiated and differentiated megakaryocytes and the role of soluble N-ethyl maleimide-sensitive factor attachment protein receptor (SNARE) proteins that are known to be associated with vesicular exocytosis. Materials and Methods Using the megakaryocytic cell line MEG-01, primary megakaryocytes, and tissue sections of bone marrow, reverse transcription polymerase chain reaction, Western blot analysis, and immunolocalization were employed to detect factors required for vesicular glutamate release. Vesicle recycling was monitored by acridine orange and FM1-43 staining and glutamate release activity was assessed by an enzyme-linked fluorimetric assay. Genetically modified MEG-01 cells, with deletion or overexpression of SNARE and vesicular proteins, were also examined for glutamate release activity. Results We demonstrated that megakaryocytes express numerous proteins required for vesicular glutamate release, including core SNARE proteins, vesicle-associated membrane protein, soluble N-ethyl maleimide-sensitive factor attachment protein−23, and syntaxin, as well as specific glutamate-loading vesicle proteins, VGLUT1 and VGLUT2. Moreover, active vesicle recycling and differentiation-dependent glutamate release were observed in megakaryocytes. Vesicle-associated membrane protein−deficient MEG-01 cells, which are impaired in vesicle recycling, showed a 30% decrease in released glutamate, whereas overexpression of VGLUT1 exhibited up to a 2.2-fold increase in glutamate release. Conclusion These data show that glutamate release from megakaryocytes occurs in a SNARE-dependent, exocytotic manner and is increased during differentiation, suggesting that manipulation of glutamate signaling could influence megakaryocytopoiesis and, therefore, offer a suitable target for the treatment of thrombosis and other hematological disorders.
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