Hyperpolarization-activated and cyclic nucleotide-gated channels are differentially expressed in juxtaglomerular cells in the olfactory bulb of mice

In the olfactory bulb, input from olfactory receptor neurons is processed by neuronal networks before it is relayed to higher brain regions. In many neurons, hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels generate and control oscillations of the membrane potential. Oscillations also appear crucial for information processing in the olfactory bulb. Four channel isoforms exist (HCN1–HCN4) that can form homo- or heteromers. Here, we describe the expression pattern of HCN isoforms in the olfactory bulb of mice by using a novel and comprehensive set of antibodies against all four isoforms. HCN isoforms are abundantly expressed in the olfactory bulb. HCN channels can be detected in most cell populations identified by commonly used marker antibodies. The combination of staining with marker and HCN antibodies has revealed at least 17 different staining patterns in juxtaglomerular cells. Furthermore, HCN isoforms give rise to an unexpected wealth of co-expression patterns but are rarely expressed in the same combination and at the same level in two given cell populations. Therefore, heteromeric HCN channels may exist in several cell populations in vivo. Our results suggest that HCN channels play an important role in olfactory information processing. The staining patterns are consistent with the possibility that both homomeric and heteromeric HCN channels are involved in oscillations of the membrane potential of juxtaglomerular cells

Doublecortin maintains bipolar shape and nuclear translocation during migration in the adult forebrain

The ability of the mature mammalian nervous system to continually produce neuronal precursors is of considerable importance, as manipulation of this process might one day permit the replacement of cells lost as a result of injury or disease. In mammals, the anterior subventricular zone (SVZa) region is one of the primary sites of adult neurogenesis. Here we show that doublecortin (DCX), a widely used marker for newly generated neurons, when deleted in mice results in a severe morphological defect in the rostral migratory stream and delayed neuronal migration that is independent of direction or responsiveness to Slit chemorepulsion. DCX is required for nuclear translocation and maintenance of bipolar morphology during migration of these cells. Our data identifies a critical function for DCX in the movement of newly generated neurons in the adult brain

TMS, lombalgies et traumatismes à l’hôpital : l’expérience d’un réseau inter-C.H.U

National audienc

Utilisation des matériels dans le milieu hospitalier

International audienc

Synthesis, molecular structure and physicochemical properties of bis(3 `-azido-3 `-deoxythymidin-5 `-yl) carbonate

3`-Azido-3`-deoxythymidine (zidovudine, AZT), a synthetic analog of natural nucleoside thymidine, has been used extensively in AIDS treatments. We report here the synthesis. X-ray crystal and molecular structure, NMR, IR and Raman spectra and the thermal behavior of a novel carbonate of AZT [(AZT-O)(2)C=O], prepared by the reaction of zidovudine with carbonyldiimidazole. The carbonate compound, C(21)H(24)N(10)O(9), crystallizes in the tetragonal space group P4(1)2(1)2 with a = b = 15.284(1), c = 21.695(1) angstrom, and Z = 8 molecules per unit cell. It consists of two AZT moieties of closely related conformations which are bridged by a carbonyl group to adopt a folded Z-like shape. (C) 2010 Elsevier B.V. All rights reserved.Fondo para la Investigacion Cientifica y Tecnologica (FONCyT)Fondo para la Investigacion Cientifica y Tecnologica (FONCyT)Secretaria de Ciencia y Tecnica de la Universidad Nacional de Cordoba (SECyT-UNC)Secretaria de Ciencia y Tecnica de la Universidad Nacional de Cordoba (SECyT-UNC)FAPESP of BrazilFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Consejo Nacional de Investigaciones Cientificas y Tecnologicas (CONICET)[PIP 1125]Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET)Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CICPBA), ArgentinaComisión de Investigaciones Científicas Provincia de Buenos Aires (CIC) - ArgentinaUNLPUNLPANPCyT of Argentina[PICT 10968]Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT

N003 Caractérisation électrophysiologique de progéniteurs cardiaques issus de cellules souches embryonnaires humaines

Les progéniteurs cardiaques issus de cellules souches embryonnaires humaines apparaissent comme de bons candidates dans la prévention et le traitement de la dysfonction cardiaque par thérapie cellulaire. Cependant, la greffe de cellules présentant des propriétés électriques indésirables pourrait prédisposer les patients à des arythmies. Il est donc important de caractériser les propriétés électrophysiologiques des progéniteurs cardiaques avant transplantation. Les cellules progénitrices cardiaques utilisées sont dérivées de la lignée HUES-24 et sélectionnées sur leur capacité à exprimer SSEA-1 après une induction de 4 jours par le BMP2. A l’aide de la technique de patch-clamp en configuration cellule entière, nous avons pu enregistrer des courants Ca2+ et K+, 24 à 48 H après la sélection. Les courants Ca2+ observés (2,22 ± 0.30 Pa/pF) sont de type L, aucun courant de type T n’ayant été détecté dans ces conditions. Ces courants sont insensibles à l’isoprotérénol (1μm) et à la forskoline (30μm) suggérant l’absence de regulation β-adrénergique. Des courants K+ activés par depolarization (6.79 ± 1.10 Pa/pF) sensibles au tétraéthylammonium (10 mM) et à la 4-aminopyridine (5 mM) ont été caractérisés. Ces courants rectifiants sortants ressemblent aux courants rectifiants sortants retardés (IKDR) déjà décrits sur des cellules souches embryonnaires murines. En revanche, aucun courant entrant activé par hyperpolarisation n’a été observé. Finalement, aucune conductance Na+ n’a pu être mise en évidence. Sur les cellules n’exprimant pas SSEA-1, utilisées comme contrôles négatifs, aucun courant Ca2+, K+ ou Na+ n’a été détecté. Le profil moléculaire des canaux ioniques exprimés par les cellules progénitrices est abordé parallèlement par une approche génomique à l’aide de la RT-PCR haut débit.En conclusion, les cellules souches embryonnaires humaines présentent les courants majeurs impliqués dans l’électrogenèse cardiaque dès 24 h après leur orientation cardiaque. Néanmoins, l’absence de régulation β-adrénergique et de courants Na+ souligne l’immaturité de ces cellules comparées aux cardiomyocytes matures. Le suivi de la genèse des propriétés électrophysiologiques de ces progéniteurs cardiaques, dans le contexte d’une thérapie cellulaire cardiovasculaire, devrait nous permettre d’explorer la capacité de ces cellules à exprimer un phénotype électrophysiologique mature et à établir des couplages excitation-contraction avec les cellules hôte

A High Throughput Phenotypic Screening reveals compounds that counteract premature osteogenic differentiation of HGPS iPS-derived mesenchymal stem cells

Hutchinson-Gilford progeria syndrome (HGPS) is a rare fatal genetic disorder that causes systemic accelerated aging in children. Thanks to the pluripotency and self-renewal properties of induced pluripotent stem cells (iPSC), HGPS iPSC-based modeling opens up the possibility of access to different relevant cell types for pharmacological approaches. In this study, 2800 small molecules were explored using high-throughput screening, looking for compounds that could potentially reduce the alkaline phosphatase activity of HGPS mesenchymal stem cells (MSCs) committed into osteogenic differentiation. Results revealed seven compounds that normalized the osteogenic differentiation process and, among these, all-trans retinoic acid and 13-cis-retinoic acid, that also decreased progerin expression. This study highlights the potential of high-throughput drug screening using HGPS iPS-derived cells, in order to find therapeutic compounds for HGPS and, potentially, for other aging-related disorders

High throughput screening for inhibitors of REST in neural derivatives of human embryonic stem cells reveals a chemical compound that promotes expression of neuronal genes

Decreased expression of neuronal genes such as brain-derived neurotrophic factor (BDNF) is associated with several neurological disorders. One molecular mechanism associated with Huntington disease (HD) is a discrete increase in the nuclear activity of the transcriptional repressor REST/NRSF binding to repressor element-1 (RE1) sequences. High-throughput screening of a library of 6,984 compounds with luciferase-assay measuring REST activity in neural derivatives of human embryonic stem cells led to identify two benzoimidazole-5-carboxamide derivatives that inhibited REST silencing in a RE1-dependent manner. The most potent compound, X5050, targeted REST degradation, but neither REST expression, RNA splicing nor binding to RE1 sequence. Differential transcriptomic analysis revealed the upregulation of neuronal genes targeted by REST in wild-type neural cells treated with X5050. This activity was confirmed in neural cells produced from human induced pluripotent stem cells derived from a HD patient. Acute intraventricular delivery of X5050 increased the expressions of BDNF and several other REST-regulated genes in the prefrontal cortex of mice with quinolinate-induced striatal lesions. This study demonstrates that the use of pluripotent stem cell derivatives can represent a crucial step toward the identification of pharmacological compounds with therapeutic potential in neurological affections involving decreased expression of neuronal genes associated to increased REST activity, such as Huntington disease

Drug screening on Hutchinson Gilford progeria pluripotent stem cells reveals aminopyrimidines as new modulators of farnesylation

International audienceHutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder characterized by a dramatic appearance of premature aging. HGPS is due to a single-base substitution in exon 11 of the LMNA gene (c.1824C>T) leading to the production of a toxic form of the prelamin A protein called progerin. Because farnesylation process had been shown to control progerin toxicity, in this study we have developed a screening method permitting to identify new pharmacological inhibitors of farnesylation. For this, we have used the unique potential of pluripotent stem cells to have access to an unlimited and relevant biological resource and test 21 608 small molecules. This study identified several compounds, called monoaminopyrimidines, which target two key enzymes of the farnesylation process, farnesyl pyrophosphate synthase and farnesyl transferase, and rescue in vitro phenotypes associated with HGPS. Our results opens up new therapeutic possibilities for the treatment of HGPS by identifying a new family of protein farnesylation inhibitors, and which may also be applicable to cancers and diseases associated with mutations that involve farnesylated proteins