Cellular and Molecular Studies on Olfactory Bulb Ensheathing Cells

Olfactory bulb ensheathing cells (OBECs) are a specialised type of glial cell that reside in the outer layer of the olfactory bulb, where they are thought to play a role in the exceptional ability of this central nervous system tissue to support re-enervertion throughout life. This thesis reports on the characterisation of the antigenic expression and growth and functional properties of OBECs in vitro. OBECs were purified from perinatal rat olfactory bulbs by fluorescence activated cell sorting using the O4 antibody (Barnett et al., 1993a). Immunofluorescence labelling of the cultures and of tissue sections of the olfactory bulb with a large panel of neural marker antibodies showed that OBECs represent a heterogeneous population of cells. The antigenic profile of the sorted cell population initially correlated with their antigenic profile in vivo, although expression of some of the markers was either lost or gained during time in culture. These changes were influenced by the culture conditions, with a greater loss of "typical" OBEC markers in serum-containing medium. In serum-free medium, which maintained the cells in a phenotype that closely resembled their in vivo counterparts, two antigenically and morphologically distinct cell types were observed, reminescent of non-myelinating Schwann cells and type-1 astrocytes, respectively. Two similar phenotypes were detected in a clonal OBEC cell line generated by retroviral infection with the temperature sensitive mutant gene of the large T antigen, supporting the view that the astrocyte-like and Schwann cell-like cells belong to the same lineage. A detailed immunocytochemical analysis of the developing olfactory system suggested that the diversification of OBEC antigenic phenotype occurs prior to embryonic day 14, along both, the peripheral and central portion of the olfactory nerves, is maintained throughout development, and is controled by microenvironmental cues. Astrocyte conditioned medium (ACM) was shown to exibit potent mitogenic activity for cultured OBECs but most of the known growth factors present in ACM were not mitogenic when applyed individually using recombinant or highly purified preparations. The mitogenic activity of ACM could be reproduced with a glial growth factor (GGF)-enriched preparation of bovine pituitary extract. However, preliminary biochemical characterisation of the ACM-derived mitogenic activity did not correlate with that of any of the previously purified neuregulins and suggested that it may be confered by a novel member of this family of polypeptide growth factors. The ability of OBECs to promote neuronal attachment/survival, neurite initiation and neurite elongation was compared to that of astrocytes and Schwann cells in an in vitro system consisting of plating cerebellar granule neurons onto monolayers enriched for each glial cell type. OBEC monolayers grown in the presence or absence of serum exerted similar neurite-outgrowth promoting activity. They were similar than Schwann cells and astrocytes at supporting neuronal attachment/survival and at initiating neurite outgrowth. However, the extent of neurite elongation on OBECs was greater than on Schwann cells and smaller than on astrocytes. When neurons were plated onto sparse cultures of OBECs, neurite initiation and elongation was greater among neurons in contact with glial cells, suggesting a role for surface interactions

Neuro-glial plasticity of neuroendocrine networks

Neuro-glial plasticity of neuroendocrine networks is a major mechanism involved in key events of physiological functions such as parturition and lactation (oxytocinergic system) and preovulatory surge (GnRH system). This type of plasticity is classically described as rearrangements between glial cells and neuroendocrine neurones. Neuro-glial plasticity can occur within several hours. Cellular and molecular mechanisms involved are complex and imply an active regulation of neuroendocrine networks activity. In the present study we show that GnRH pulsatile secretion studied in vitro is regulated by gap junction communication between glial cells. Glial cells forming the microenvironment of GnRH neuronal network could represent a new system for integrating environmental cues and for regulating GnRH secretionLa plasticité neuro-gliale des réseaux neuroendocrines est un élément majeur de la régulation d’évènements clés de grandes fonctions, comme la plasticité du système ocytocinergique lors de la parturition et de la lactation et celle du système GnRH dans le déclenchement du pic pré-ovulatoire de LH. Cette plasticité est décrite par des réarrangements neuroanatomiques des cellules gliales associées aux neurones neuroendocrines. Elle peut se mettre en place en quelques heures. Les mécanismes cellulaires et moléculaires sont complexes et mettent en jeu une régulation active de l’activité des neurones par les cellules gliales. Dans l’étude présentée ici, nous montrons que la pulsatilité de sécrétion des neurones à GnRH étudiés in vitro est régulée par la communication des cellules gliales via des jonctions gap. Les cellules gliales du microenvironnement des neurones à GnRH pourraient ainsi représenter un nouveau système d’intégration des signaux environnementaux et de régulation de la sécrétion de GnR

p140Cap Controls Female Fertility in Mice Acting via Glutamatergic Afference on Hypothalamic Gonadotropin-Releasing Hormone Neurons.

p140Cap, encoded by the gene SRCIN1 (SRC kinase signaling inhibitor 1), is an adaptor/scaffold protein highly expressed in the mouse brain, participating in several pre- and post-synaptic mechanisms. p140Cap knock-out (KO) female mice show severe hypofertility, delayed puberty onset, altered estrus cycle, reduced ovulation, and defective production of luteinizing hormone and estradiol during proestrus. We investigated the role of p140Cap in the development and maturation of the hypothalamic gonadotropic system. During embryonic development, migration of Gonadotropin-Releasing Hormone (GnRH) neurons from the nasal placode to the forebrain in p140Cap KO mice appeared normal, and young p140Cap KO animals showed a normal number of GnRH-immunoreactive (-ir) neurons. In contrast, adult p140Cap KO mice showed a significant loss of GnRH-ir neurons and a decreased density of GnRH-ir projections in the median eminence, accompanied by reduced levels of GnRH and LH mRNAs in the hypothalamus and pituitary gland, respectively. We examined the number of kisspeptin (KP) neurons in the rostral periventricular region of the third ventricle, the number of KP-ir fibers in the arcuate nucleus, and the number of KP-ir punctae on GnRH neurons but we found no significant changes. Consistently, the responsiveness to exogenous KP in vivo was unchanged, excluding a cell-autonomous defect on the GnRH neurons at the level of KP receptor or its signal transduction. Since glutamatergic signaling in the hypothalamus is critical for both puberty onset and modulation of GnRH secretion, we examined the density of glutamatergic synapses in p140Cap KO mice and observed a significant reduction in the density of VGLUT-ir punctae both in the preoptic area and on GnRH neurons. Our data suggest that the glutamatergic circuitry in the hypothalamus is altered in the absence of p140Cap and is required for female fertility

Association of Forced Vital Capacity with the Developmental Gene <i>NCOR2</i>

Background Forced Vital Capacity (FVC) is an important predictor of all-cause mortality in the absence of chronic respiratory conditions. Epidemiological evidence highlights the role of early life factors on adult FVC, pointing to environmental exposures and genes affecting lung development as risk factors for low FVC later in life. Although highly heritable, a small number of genes have been found associated with FVC, and we aimed at identifying further genetic variants by focusing on lung development genes. Methods Per-allele effects of 24,728 SNPs in 403 genes involved in lung development were tested in 7,749 adults from three studies (NFBC1966, ECRHS, EGEA). The most significant SNP for the top 25 genes was followed-up in 46,103 adults (CHARGE and SpiroMeta consortia) and 5,062 chi

Genome-wide association analysis identifies six new loci associated with forced vital capacity

Forced vital capacity (FVC), a spirometric measure of pulmonary function, reflects lung volume and is used to diagnose and monitor lung diseases. We performed genome-wide association study meta-analysis of FVC in 52,253 individuals from 26 studies and followed up the top associations in 32,917 additional individuals of European ancestry. We found six new regions associated at genome-wide significance (P < 5 × 10−8) with FVC in or near EFEMP1, BMP6, MIR129-2–HSD17B12, PRDM11, WWOX and KCNJ2. Two loci previously associated with spirometric measures (GSTCD and PTCH1) were related to FVC. Newly implicated regions were followed up in samples from African-American, Korean, Chinese and Hispanic individuals. We detected transcripts for all six newly implicated genes in human lung tissue. The new loci may inform mechanisms involved in lung development and the pathogenesis of restrictive lung disease

The SIB Swiss Institute of Bioinformatics' resources: focus on curated databases

The SIB Swiss Institute of Bioinformatics (www.isb-sib.ch) provides world-class bioinformatics databases, software tools, services and training to the international life science community in academia and industry. These solutions allow life scientists to turn the exponentially growing amount of data into knowledge. Here, we provide an overview of SIB's resources and competence areas, with a strong focus on curated databases and SIB's most popular and widely used resources. In particular, SIB's Bioinformatics resource portal ExPASy features over 150 resources, including UniProtKB/Swiss-Prot, ENZYME, PROSITE, neXtProt, STRING, UniCarbKB, SugarBindDB, SwissRegulon, EPD, arrayMap, Bgee, SWISS-MODEL Repository, OMA, OrthoDB and other databases, which are briefly described in this article

La prothèse dento-implanto-portée

MONTPELLIER-BU Médecine UPM (341722108) / SudocMONTPELLIER-BU Odontologie (341722110) / SudocPARIS-BIUM (751062103) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

Development and aging of the Kisspeptin-GPR54 system in the mammalian brain: what are the impacts on female reproductive function?

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