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G Rougon

Publications and source records attributed to G Rougon.

At least 91 records · Page 5Linked to original sources
PubMed1993

CD24, a signal-transducing molecule expressed on human B lymphocytes, is a marker for human regenerating muscle.

The expression of the CD24 molecule, a glycoprotein expressed at the surface of most B lymphocytes and differentiating neuroblasts, was studied in developing nerve and muscle (after 16 weeks of gestation), normal adult and various diseased human muscles using immunohistochemistry and Western blot analysis. Immunohistochemical studies demonstrated that: (1) in developing muscles, fibers did not express CD24, whereas only some mesenchymal areas, also expressing neural cell adhesion molecule (N.CAM) and vimentin, and developing nerves were positive; (2) in normal adult muscles, CD24 immunoreactivity was observed only in some unmyelinated nerve fibers--intra and extra fusal muscle fibers, satellite cells and neuromuscular junctions were negative; and (3) in all diseased muscles studied here, CD24 expression was always associated with a subpopulation of regenerative fibers. These fibers also expressed vimentin, desmin, developmental myosin heavy chain, N.CAM and its polysialylated isoforms (PSA-N.CAM). The number of CD24-positive fibers was always lower than that of PSA-N.CAM-positive fibers. Denervated fibers and vacuolated muscle fibers never expressed CD24. Western blot analysis indicated that the apparent molecular mass of CD24 antigen was different between muscle and developing nervous tissues, suggesting that CD24 glycosylation is tissue specific. Since the molecule was not expressed in developing human muscle fibers, it strongly suggests that regenerative and fetal myotubes are different with respect to the CD24 molecule expression.

Adult↗
PubMed1993

Are the glypiated adhesion molecules preferentially targeted to the axonal compartment?

The question of how the cell surface molecules may be specifically delivered to subdomains of neurons is of particular interest considering that polarized sorting to the axon could enable adhesion glycoproteins to induce fasciculation of axonal tracts, guidance to the target cell, and the establishment of synaptic contacts. It was recently proposed that GPI-anchored molecules undergo preferential delivery to the axonal surface, implicating a similar polarized sorting of glycoproteins in neurons and epithelial cells (Dotti and Simons, 1990; Dotti et al., 1991). This review focuses on the cellular and subcellular localization of several glypiated adhesion molecules (Thy-1, TAG-1, F3/F11, P-31) in the developing and adult cerebellar cortex of the mouse. We conclude that the cellular distribution of GPI-anchored adhesion molecules within neurons is very complex and depends on: 1. The neuronal cell types, for example, F3/F11 is localized in axons in granule cells but is present in all compartments of Golgi cells. 2. The molecule itself: Thy-1, TAG-1, and P-31 are present on the granule cell body, whereas at the same developmental stage, F3/F11 is restricted to the axon. 3. The differentiation state: Thy-1 delivery to the axon correlates with postsynaptic target maturation.

Animals↗
PubMed1993

Nerve-dependent expression of high polysialic acid neural cell adhesion molecule in neurohypophysial astrocytes of adult rats.

The adult hypothalamo-neurohypophysial system of the rat retains the capacity to express highly polysialylated isoforms of neural cell adhesion molecule normally expressed in developing tissues. Here we report that the expression of these isoforms in neurohypophysial astrocytes (pituicytes) may be regulated by neurosecretory cells. In the intact neurohypophysis a strong and homogeneously distributed immunostaining for the "embryonic", highly sialylated form of neural cell adhesion molecules was detected by light-microscopic immunocytochemistry. By electron-microscopy, both neurosecretory axons and pituicytes were immunoreactive for this isoform. However, in contrast to the rather uniform staining on nerve fibres, polysialic acid immunolabelling on glial surfaces was uneven: immunostaining could be observed on glial surfaces facing neuronal elements, but not at contact sites between pituicytes. In addition, most glial and neuronal elements were heavily and evenly labelled with the polyclonal antibody recognizing "total" neural cell adhesion molecule. Surgical transection of the hypophysial stalk, a procedure that eliminates descending neurosecretory axons from the neurohypophysis, resulted in the complete disappearance of polysialic immunoreactivity from the neurohypophysis. The electron-microscopic analysis confirmed that cell surfaces of pituicytes lacked this immunoreactivity after the lesion. When residual neurosecretory axons were observed following an incomplete lesion, immunoreactivity on axons and glial processes was maintained. Transection did not affect the distribution of "total" neural cell adhesion molecule. We postulate that the presence of neurosecretory axons in the neurohypophysis is necessary to maintain the capacity of pituicytes to express immunoreactivity for the polysialylated isoforms of neural cell adhesion molecule but not the neural cell adhesion molecule itself since immunoreactivity for "total" neural cell adhesion molecule was unaltered after hypophysial stalk transection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Development of antibodies against the rat brain somatostatin receptor.

Somatostatin (SRIF) is a neurotransmitter in the brain involved in the regulation of motor activity and cognition. It induces its physiological actions by interacting with receptors. We have developed antibodies against the receptor to investigate its structural properties. Rabbit polyclonal antibodies were generated against the rat brain SRIF receptor. These antibodies (F4) were able to immunoprecipitate solubilized SRIF receptors from rat brain and the cell line AtT-20. The specificity of the interaction of these antibodies with SRIF receptors was further demonstrated by immunoblotting. F4 detected SRIF receptors of 60 kDa from rat brain and adrenal cortex and the cell lines AtT-20, GH3, and NG-108, which express high densities of SRIF receptors. They did not detect immunoreactive material from rat liver or COS-1, HEPG, or CRL cells, which do not express functional SRIF receptors. In rat brain, 60-kDa immunoreactivity was detected by F4 in the hippocampus, cerebral cortex, and striatum, which have high densities of SRIF receptors. However, F4 did not interact with proteins from cerebellum and brain stem, which express few SRIF receptors. Immunoreactive material cannot be detected in rat pancreas or pituitary, which have been reported to express a 90-kDa SRIF receptor subtype. The selective detection of 60-kDa SRIF receptors by F4 indicates that the 60- and 90-kDa SRIF receptor subtypes are immunologically distinct. The availability of antibodies that selectively detect native and denatured brain SRIF receptors provides us with a feasible approach to clone the brain SRIF receptor gene(s).

Animals↗
PubMed1992

Isolation and characterization of a novel glycosyl-phosphatidylinositol-anchored glycoconjugate expressed by developing neurons.

In search of new markers for studying thymic and nervous system ontogeny, we raised rat monoclonal antibodies against glycosyl-phosphatidylinositol-anchored molecules among which larger groupings have been shown to be ectoenzymes and adhesion molecules. Two of these monoclonal antibodies (H193-4 and H194-563, IgG) were found to recognize glycosyl-phosphatidylinositol-anchored glycoconjugates of 28-33 kDa (P31) and 50-70 kDa in developing mouse brain and thymus respectively, when these tissues were analysed by immunoblot experiments. P31 antigen was found to be transiently expressed by neurons in neural primary cultures [Rougon, G., Alterman, L., Dennis, K., Guo, X. J. & Kinnon, K. (1991) Eur. J. Immunol. 21, 1397-1402]. We show in this report that, in developing mouse brain, a maximal expression occurred between embryonic day 17 and post-natal day 5, a period that corresponds to the formation of neuronal networks. P31 antigen was immunopurified and found to possess the following properties: (a) it was soluble in alkaline solvents; (b) it bound to DEAE-cellulose and was eluted by a salt gradient of 0-1 M NaCl; (c) it was sensitive to endoglycosidase F digestion; (d) it was insensitive to heparinase, hyaluronidase, chondroitinase ABC, endo-beta-galactosidase and sialidase treatment; (e) it was labile to mild acid hydrolysis without loss of immunoreactivity; (f) it contained phosphate; (g) it lost its immunoreactivity after treatment with phosphatidylinositol phospholipase C and treatment. These characteristics combine to suggest that P31 is an anionic glycoconjugate sharing similarities with Leishmania donovani lipophosphoglycan and with the heat-stable antigen recognized by J11d antibody on murine hematopoïetic cells. This last hypothesis was further confirmed by the observation that oligonucleotide probes derived from the heat-stable antigen-encoding cDNA detect, in developing brain, a 1.8-kb mRNA species similar in size to that reported for the heat-stable antigen mRNA and following the same developmental expression as P31 antigen.

Animals↗
PubMed1992

Expression and release of phosphatidylinositol anchored cell surface molecules by a cell line derived from sensory neurons.

Early postnatal mouse dorsal root ganglion neurons were found to express several glycosylphosphatidylinositol-anchored (GPI) molecules from the immunoglobulin superfamily (neural cell adhesion molecule 120 kD isoform, F3, Thy1) whose expression is developmentally regulated. A hybrid cell line (ND26), made by fusing postmitotic rat dorsal root ganglion (DRG) neurons with the mouse neuroblastoma N18Tg2, could be induced to differentiate by manipulating the composition of the culture medium and expressed similar GPI molecules to DRG neurons. We used this model system to investigate the metabolism of GPI-anchored molecules. We found that neural cell adhesion molecule 120 Kd isoform expression decreased upon differentiation, whereas the level of F3 and Thy1 increased, suggesting a role in neurite outgrowth processes. The ratio of molecules cleavable by exogenous phosphatidylinositol phospholipase C (PI-PLC) was similar for all the GPI-anchored molecules, which could mean that cell-specific modifications of the basic anchoring structure determine the level of potentially releasable molecules. Measurements of spontaneous release indicated that this reflected the overall level of expression of these molecules by the ND26 cell line. Finally, we observed an effect of dibutyryl cAMP on the level of expression of F3 and Thy1 but not of N-CAM. However, we could not detect any significant effect of nerve growth factor (NGF) either on the level of expression or on the amount of spontaneously released molecules.

Animals↗
PubMed1992

Expression of cell surface and cytoskeleton developmentally regulated proteins in adult centronuclear myopathies.

In order to evaluate the developmental status of myofibers in 3 cases of adult centronuclear myopathies (CNM) with type I predominance, we searched for the expression of (a) developmentally regulated cytoskeleton proteins (myosin heavy chains (MHC), vimentin, desmin), and (b) cell surface molecules (neural cell adhesion molecules isoforms, NCAM). Desmin intermediate filaments were overexpressed in some fibers with centrally located nuclei and radially organized. Muscle fibers do not express vimentin. These findings were not observed in muscle biopsies from disease controls with numerous central nuclei. Few myofibers (less than 5%) expressed developmental MHC together with either embryonic NCAM or adult NCAM and rare fibers only expressed adult NCAM. Most of the remaining fibers neither expressed NCAM nor developmental MHC but were slow MHC positive. These features do not favor the hypothesis of a general arrest of muscle fiber maturation in adult CNM. It is more likely that fibers undergo a very slow developmental process with a long delay of innervation as shown by some fibers with NCAM expression. Nevertheless, innervation appears to be successful, as suggested by the large number of NCAM negative fibers. Moreover, the abnormal myofiber distribution could be related to this functional disturbance of innervation.

Adult↗
PubMed1992

A soluble form of the F3 neuronal cell adhesion molecule promotes neurite outgrowth.

The F3 molecule is a member of the immunoglobulin superfamily anchored to membranes by a glycane-phosphatidylinositol, and is predominantly expressed on subsets of axons of the central and peripheral nervous system. In a previous paper (Gennarini, G., P. Durbec, A. Boned, G. Rougon, and C. Goridis. 1991. Neuron. 6:595-606), we have established that F3 fulfills the operational definition of a cell adhesion molecule and that it stimulates neurite outgrowth when presented to sensory neurons as a surface component of transfected CHO cells. In the present study the question as to whether soluble forms of F3 would be functionally active was addressed in vitro on cultures of mouse dorsal root ganglion neurons. We observed that preparations enriched in soluble F3 had no effect on neuron attachment but enhanced neurite initiation and neurite outgrowth in a dose-dependent manner. By contrast, soluble NCAM-120 does not have any measurable effect on these phenomena. Addition of anti-F3 monovalent antibodies reduced the number of process-bearing neurons and the neuritic output per neuron to control values. Addition of cerebrospinal fluid, a natural source of soluble F3, also stimulated neurite extension, and this effect was partially blocked by anti-F3 antibodies. Our results suggest that the soluble forms of adhesive proteins with neurite outgrowth-promoting properties could act at a distance from their site of release in a way reminiscent of growth and trophic factors.

Animals↗
PubMed1992

Expression of various NCAM isoforms in human embryonic muscles: correlation with myosin heavy chain phenotypes.

Neural cell adhesion molecules (NCAM) are known to play a pivotal role in regulating cell-cell interactions in various tissues. The diversity of NCAM is made by alternative splicing of a single gene and by post-translational modifications. The spatio-temporal expression of the various isoforms is developmentally regulated and may modulate cell interactions. We investigated the expression of NCAM isoforms, in particular polysialylated and phosphatidylinositol-anchored isoforms, in developing psoas and quadriceps human muscle from 15 weeks of gestation to term. In parallel, we examined the expression of the myosin heavy chain phenotype (another developmentally regulated system) to determine whether polysialylated-NCAM molecules (the so-called embryonic NCAM) and developmental myosin heavy chains are coexpressed. Our results showed an expression of polysialylated-NCAM and phosphatidylinositol-anchored isoforms during the early stages of myotube maturation. The expression of polysialylated-NCAM on developing myotube was always associated with the expression of developmental myosin heavy chains. However, the loss of polysialylated-NCAM from maturing myotubes was not correlated with the disappearance of the developmental myosin heavy chains, but rather with the appearance of an adult myosin heavy chain phenotype. The relationship between polysialylated-NCAM and myosin heavy chain phenotype was similar in psoas and in quadriceps muscles. We observed that maturation of quadriceps muscle takes place earlier than psoas. Biochemical analysis showed that phosphatidylinositol-anchored molecules were never polysialylated; this indicates different roles of these isoforms in muscle development.

Aging↗
PubMed1992

[Expression of adhesion molecules N.CAM, L1 and HNK1 epitope by medulloblastoma].

Twelve medulloblastomas were screened for their expression of adhesion molecules L1, N.CAM isoforms and HNK1 epitope by Western blotting and immunohistochemistry. Highly sialylated N.CAM isoforms were distinguished from total N.CAMs by using a monoclonal antibody (anti-MenB) specifically recognizing high polymers of 2-8 linked neuraminic acid. All tumors expressed HNK1 epitope, N.CAM and its highly sialylated isoforms on their surface membrane. L1 adhesion molecule was detected by immunohistochemistry in only one medulloblastoma. This spectrum of expression of cell surface adhesion molecules distinguishes medulloblastomas from other primitive neuroectodermal tumors. Medulloblastomas share some immunological features with post-mitotic cells forming the external granular layer of the cerebellum. Western blotting analysis of cerebrospinal fluid (CSF) samples with anti-MenB antibody enabled us to detect highly sialylated N.CAM in some samples. The presence of this antigen in CSF appears to correlate with meningeal spreading of medulloblastomas and could help monitoring chemotherapeutic treatment.

Antibodies, Monoclonal↗
PubMed1992

Central neurocytomas. Critical evaluation of a small-cell neuronal tumor.

We report herein the clinical and pathological features of 20 patients with central neurocytomas. Investigations for various differentiation antigens and cell type-specific markers were performed by immunohistochemistry using paraffin-embedded tissue. In addition, the expression of L1 adhesion molecule and of the various N.CAM (neural cell adhesion molecule) isoforms were investigated by immunoblotting studies in two frozen specimens. Central neurocytomas are clinically characterized by their intraventricular localization, occurrence in young adults, and good prognosis. It rarely occurs in patients over 50, but such cases have a poor prognosis. Total surgical excision is the best treatment. Radiotherapy is appropriate if surgery is incomplete or contraindicated. Histologically, central neurocytomas display the following features: an oligo-like pattern, usually associated with large fibrillary rosettes or perivascular arrangement, and a rich endocrine-type vasculature. Central neurocytomas have a remarkably homogeneous antigenic profile. GFAP expression is only found in scattered reactive astrocytes, S100 protein in reactive astrocytes and rare tumor cells. Among the pan-neuroendocrine markers, central neurocytomas always express neuron-specific enolase; they frequently express synaptophysin but never chromogranin A. Synaptophysin is the most reliable immunohistological marker for central neurocytomas; however, immunoreactivity could be lost with long formalin fixation. In these cases, electron microscopy is used to support the neuronal nature of the tumor cells. The expression of L1 adhesion molecule and the isoform 180 of N.CAM, indicates that central neurocytomas are formed by cells committed to neuronal phenotype. Nevertheless, advanced neuronal differentiation may be absent, as suggested by the persistence of embryonic N.CAM, the nonexpression of neurofilament proteins, and the absence of mature synapses in numerous cases. Central neurocytomas and neuroblastomas share some biochemical properties, but their respective clinicopathological features and biological behavior are dramatically different.

Adolescent↗
PubMed1992

The embryonic form of neural cell surface molecule (E-NCAM) in the rat hippocampus and its reexpression on glial cells following kainic acid-induced status epilepticus.

The neural cell adhesion molecule (NCAM) changes at the cell surface during development, from highly sialylated forms (embryonic or E-NCAM) to three size classes of less sialylated proteins with apparent molecular mass of 180, 140, and 120 kDa (adult NCAM). In the nervous system, E-NCAM has been localized in developing tissues, where it is thought to play a role in the structuring of neuronal groups and tissue pattern formation. In the present study a monoclonal antibody that specifically detects E-NCAM was used in immunoblot and immunohistochemical procedures. In developing rat hippocampus, E-NCAM cell expression was found to change according to a precise pattern and persisted until 1 month after birth. It was closely associated with the mossy fiber system, an area known for its sprouting propensity. In adult rats, although immunoreactivity considerably decreases and becomes undetectable by immunoblot analysis, E-NCAM was still found to be associated with a few pyramidal-shaped cells in the innermost part of the dentate gyrus. In order to acquire some insight into potential histogenetically plastic functions of E-NCAM, in another series of experiments adult rats were treated with kainic acid, a powerful excitotoxic and convulsant glutamate analog eliciting status epilepticus. When these animals were examined for E-NCAM expression, an intense labeling was found associated with glial-like cells, particularly in the hippocampal formation, and corresponding approximately to the reactive gliosis, as confirmed by staining with anti-glial fibrillary acidic protein antibodies. This expression was detectable from about 3 d following kainic acid administration and persisted for at least 12 weeks; it developed according to an observable spatiotemporal distribution pattern. In animals submitted to amygdala kindling, a nonlesional model of secondarily generalized epilepsy, no such reexpression of E-NCAM was observed. Our observations imply that polysialylation may be a means of identifying neuronal structures capable of plasticity in the CNS. Moreover, intense reexpression of E-NCAM could be a marker of reactive gliosis following brain damage.

Aging↗
PubMed1992

F3/F11 cell surface molecule expression in the developing mouse cerebellum is polarized at synaptic sites and within granule cells.

The distribution of the F3/F11 neuronal cell surface molecule was investigated in the developing and adult mouse cerebellum by immunocytochemistry at the light and electron microscopic levels. F3/F11 was confined to subsets of neuronal types, since the Purkinje cell body and dendritic arborization as well as the stellate cells were not immunoreactive. In the young developing cerebellum, the granule cell axons strongly express F3/F11 as soon as they begin to grow, consistent with a functional role in promoting directional outgrowth of neuronal processes. In 10-d-old and adult cerebella, the granule cell bodies and dendrites were not immunoreactive whereas the parallel fibers, which are the granule cell axons, were labeled including in their presynaptic varicosities. By contrast, dendrites, cell bodies, and axons of Golgi cells were labeled by anti-F3 antibodies. Hence, F3/F11 can either be expressed throughout the cell or be polarized to the axons. This raises the question of how segregation of the glypiated F3/F11 molecule between different subcellular compartments depending on the type of neuron is achieved. F3/F11 was found to be present at three types of synaptic sites, suggesting that it might play a role in the formation and maintenance of synapses. However, in each type of synpase, F3/F11 was present at only the pre- or postsynaptic site, never at both: the parallel fiber varicosities contained F3/F11 whereas the postsynaptic compartment in contact, that is, the Purkinje cell dendritic spines, did not. The granule cell dendrites were unlabeled while the mossy fiber terminals contacting them were immunoreactive, and finally, the Golgi cell dendrites and dendritic spines were labeled while the presynaptic compartment contacting them was not. If F3/F11 functions as an adhesion molecule in vivo as indicated by in vitro assays, F3/F11-mediated adhesion is likely to be heterophilic.

Animals↗
PubMed1991

Retention of embryonic features by an adult neuronal system capable of plasticity: polysialylated neural cell adhesion molecule in the hypothalamo-neurohypophysial system.

The neural cell adhesion molecule, N-CAM, changes at the cell surface during development, from a highly sialylated form [polysialic acid (PSA)-linked N-CAM, PSA-N-CAM] to several isoforms containing less sialic acid. N-CAM and its polysialic acid may serve to regulate cell apposition, thus affecting a variety of cell interactions. In the nervous system, PSA-N-CAM has until now been localized in developing tissues where it is thought to participate in the structuring of neuronal groups and tissue pattern formation. It has been proposed, however, that PSA-N-CAM may also be expressed in the adult, where it may take part in plasticity and cell reshaping. In the present study, the use of immunoblot and immunocytochemical procedures with a monoclonal antibody that specifically recognizes PSA-N-CAM revealed that the adult rat hypothalamo-neurohypophysial system, which undergoes important neuronal-glial and synaptic rearrangements in response to physiological stimuli, contains high levels of PSA-N-CAM immunoreactivity. The use of a polyclonal serum reacting with all N-CAM isoforms indicated that PSA-N-CAM is expressed together with "adult" forms of N-CAM. Light and electron microscopy demonstrated the presence of PSA-N-CAM immunoreactivity in the supraoptic and paraventricular nuclei of the hypothalamus and in the neurohypophysis; the immunoreactivity was seen in dendrites, axons, and terminals and in associated astrocytes but not in neuronal somata. We propose that the continued expression of PSA-N-CAM confers to magnocellular neurons and their astrocytes the ability to reversibly change their morphology in adulthood. In addition, our observations suggest that evidence for polysialylation may serve to identify other neuronal systems capable of morphological plasticity in the adult central nervous system.

Animals↗
PubMed1991

The murine heat-stable antigen: a differentiation antigen expressed in both the hematolymphoid and neural cell lineages.

The murine heat-stable antigen (HSA) and the p31 antigen are cell surface glycoconjugates which are transiently expressed during the development and differentiation of the hematolymphoid and neural cell lineages, respectively. We show here that monoclonal antibodies which react with these two species recognize a common antigenic determinant which is expressed on both HSA and p31, and the HSA and p31 share a common protein core. Differences in the molecular weights of the antigens most likely reflect variations in the extent of post-translational modifications. From these studies we conclude that these antigens are members of the same family of heat-stable antigens. Our results lead us to speculate on how these molecules are related, their function, and what role they play in cellular differentiation in hematolymphoid and neural cell development.

Animals↗
PubMed1991

Expression and characterization of alkaline phosphatases during differentiation of human pancreatic cancer (Capan-1) cells in culture.

Human pancreatic cells of the Capan-1 cell line differentiate in culture. During the exponential growth phase, the cells are undifferentiated, only becoming differentiated during the stationary phase. The formation of domes in this phase is related to the exchange of water and electrolytes. The present study was designed to characterize the localization and expression of alkaline phosphatases (AP) in Capan-1 cells during growth in culture. Biochemical, cytoenzymatic and immunocytochemical methods were employed combined with light and electron microscopic examination. AP essentially of the placental type were expressed progressively during the exponential growth phase, and were seen to be distributed over the surface of the Capan-1 cells. In the stationary phase, the AP became localized on the surface of microvilli. The precipitates of the enzyme reaction highlighted regular four-bodied structures. Biochemical assays showed a progressive increase in activity of this enzyme in cells during both the exponential and stationary growth phases. However, in the stationary phase between days 7 and 8, there was a fall in enzyme activity, with a corresponding increase in this activity in the culture medium. Cytological examination indicated that this fall could be accounted for by loss of AP-positive membranes by vesiculization of apical microvilli and release of microvesicles into the culture medium. Immunoblots showed that Capan-1 cells expressed two types of AP, a placental type (70 kDa) and to a lesser extent a liver type (80 kDa). Expression of the placental type was attributed to a neoplastic derepression of the coding gene, while the liver type was assumed to be a normal gene expression of human duct cells. The placental type AP might thus serve as a marker of transformation, and the liver type as a marker of differentiation.

Alkaline Phosphatase↗