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C Dulac

Publications and source records attributed to C Dulac.

29 records · Page 2Linked to original sources
PubMed1995

A novel family of genes encoding putative pheromone receptors in mammals.

In mammals, olfactory sensory perception is mediated by two anatomically and functionally distinct sensory organs: the main olfactory epithelium (MOE) and the vomeronasal organ (VNO). Pheromones activate the VNO and elicit a characteristic array of innate reproductive and social behaviors, along with dramatic neuroendocrine responses. Differential screening of cDNA libraries constructed from single sensory neurons from the rat VNO has led to the isolation of a family of about 30 putative receptor genes. Sequence analysis indicates that these genes comprise a novel family of seven transmembrane domain proteins unrelated to the receptors expressed in the MOE. Moreover, the expression of each member of the gene family is restricted to a small subpopulation of VNO neurons. These genes are likely to encode mammalian pheromone receptors.

Amino Acid Sequence↗
PubMed1993

Negative regulation of Schwann cell myelin protein gene expression by the dorsal root ganglionic microenvironment.

In vivo, the surface glycoprotein Schwann cell myelin protein (SMP) is expressed in the quail peripheral nervous system exclusively by Schwann cells. It is not detectable at any developmental stage either in enteric glia or in ganglionic satellite cells. We demonstrate here that the satellite glial cells of the dorsal root ganglia start to express SMP on their surface when they are dissociated into single cells and cultivated in vitro. Activation of SMP synthesis is a rapid event observed in mass cultures of dorsal root ganglia dissociated cells as soon as 4 h after the onset of the culture. Confocal microscope analysis revealed that satellite cells may acquire the Schwann cell marker when still in close contact with the neuronal soma. Clonal cultures of satellite cells from E8 dorsal root ganglia demonstrated that the progeny of these SMP-negative cells steadily express SMP. This, together with similar results previously obtained with enteric glia, suggests that the SMP-positive phenotype is a constitutive trait of the peripheral glial cell lineage which is inhibited in satellite cells in vivo by the microenvironment prevailing in the peripheral nervous system ganglia.

Animals↗
PubMed1992

Molecular characterization of the Schwann cell myelin protein, SMP: structural similarities within the immunoglobulin superfamily.

The Schwann cell myelin protein (SMP), previously defined in quail and chick by a monoclonal antibody, is in vivo exclusively expressed by myelinating and nonmyelinating Schwann cells and oligodendrocytes. The isolation of the complete nucleotide sequence of SMP is reported here. The predicted polypeptide chain reveals that SMP is a transmembrane molecule of the immunoglobulin superfamily showing sequence similarities with several surface glycoproteins expressed in the nervous and immune systems. In spite of a 43.5% overall sequence identity between rat myelin-associated glycoprotein (MAG) and quail SMP, SMP does not seem to be the avian homolog of MAG, since their expression, regulation, and functions are significantly different. Unusual sequence arrangements shared by SMP, MAG, and two lymphoid antigens suggest the existence of a particular subgroup in the immunoglobulin superfamily.

Amino Acid Sequence↗
PubMed1991

Phenotypic plasticity of Schwann cells and enteric glial cells in response to the microenvironment.

We produced earlier a monoclonal antibody against Schwann cell myelin protein (SMP), a glycoprotein expressed on Schwann cells (SC) but not on satellite cells of the ganglia or enteric glial cells. We now studied whether SMP expression is environmentally regulated in the different compartments of the peripheral nervous system. Quail neural-crest cells from either mes-metencephalic, vagal, or truncal levels of the neuraxis were heterochronically associated with gut wall, skin, or muscle tissues from embryonic day (E) 7 to E11 chickens. Coculture of these chimeric organs revealed that as in normal development glial cells, characterized by HNK1 immunoreactivity and the quail nuclear marker, expressed the SMP phenotype exclusively in skin and muscle, failing to do so in gut. However, when SMP+ SC from quail sciatic nerves were cocultured with chicken gut, these cells rapidly lost their initial SMP immunoreactivity. In contrast, when associated with muscle and skin, SC remained SMP+, even in the complete absence of neuronal cells. Enteric plexuses from E8 to E15 quail gut express SMP+ and laminin when withdrawn from the intestinal-mesenchyme environment. These results show that SMP can be expressed by enteric glial cells and that the SC SMP phenotype is strongly inhibited by the gut-wall environment. Moreover, these results strongly suggest that these two types of glial cells belong to the same lineage and that their terminal phenotype is modulated through cell-to-cell interactions.

Animals↗
PubMed1991

Glial cell lineages in the neural crest.

We have been studying how and when the different peripheral glial cell lineages individualize during avian embryonic development. Three different and complementary experimental approaches were used for this purpose: 1) the quail/chick chimera system allowed the tracing in vivo of the origin of the various types of peripheral glial cells (Schwann cells of nerves, satellite glial cells of sensory and autonomic ganglia, and enteric glial cells), and the analysis of the non-neuronal cell population of ganglia; 2) characterisation of early cell-type specific markers that discriminate between the different glial cell subpopulations; and 3) analysis of the progeny of neural crest cells in clonal cultures. As a result of these approaches, two novel glial-specific markers, expressed earlier than any previously described myelin components, have been identified and partly characterised. The divergence of glial and neuronal cell lineages is a process that is not completely terminated during the phase of neural crest migration. Whereas some cells are apparently already totally committed to a glial fate at this stage, others retain dual neuronal/glial potentialities.

Animals↗
PubMed1990

Schwann-cell differentiation in clonal cultures of the neural crest, as evidenced by the anti-Schwann cell myelin protein monoclonal antibody.

In the vertebrate embryo, Schwann cells lining the peripheral nerves originate from the neural crest (NC), a structure that also gives rise to ganglion satellite cells, most of the neurons of the peripheral nervous system, melanocytes, and part of the cranial mesenchyme. We have studied the emergence of the Schwann cell lineage in vitro in clonal cultures of quail mesencephalic NC cells by using the Schwann cell myelin protein antigen as an early and specific marker for myelinating and nonmyelinating cells. After 13-16 days in culture, numerous clones contained Schwann cell myelin protein-positive cells, sometimes isolated and sometimes associated with other NC-derived cell types. Detailed phenotypic analysis of the clones allowed us to infer the presence of differently committed Schwann-cell ancestors in the NC during the migration stage. In particular, we found evidence for the existence of a bipotent precursor of Schwann cells and nonneuronal satellite cells; a common precursor of neurons, satellite cells, and Schwann cells; and a pluripotent precursor of Schwann cells, satellite cells, neurons, and melanocytes. These founder cell types coexist in the NC with a committed Schwann cell progenitor of high-proliferative potential that differentiates in vitro in the absence of other peripheral cells and axons.

Animals↗
PubMed1988

A surface protein expressed by avian myelinating and nonmyelinating Schwann cells but not by satellite or enteric glial cells.

Searching for specific markers of neural crest-derived cell lineages, we immunized mice with glycoproteins purified from adult quail peripheral myelin. We obtained a monoclonal antibody that reacts with myelin and peripheral glial cells. This antibody, to Schwann cell myelin protein (SMP), is specific for the membranes of all Schwann cells, irrespective of whether they are associated with myelinated nerves. SMP persists on Schwann cells in long-term cultures in vitro, but is absent from satellite cells of peripheral ganglia, both in vivo and in vitro. The antigen (a protein doublet of Mr 75,000-80,000) is present in, but not restricted to, the myelin lamellae, since it is distributed along the whole myelinating Schwann cell membrane. In the CNS, SMP appears as a single band of Mr 80,000. SMP is first detectable by immunofluorescence at E6 in the quail, which is at least 6 days earlier than the first appearance of already described markers related to myelination.

Animals↗