Biomedical subjects

S Kuchler-Bopp

Publications and source records attributed to S Kuchler-Bopp.

14 recordsLinked to original sources

PubMed2006

Expression patterns of BMPRs in the developing mouse molar.

During development, Bone Morphogenetic Proteins (BMPs) can induce apoptosis, cell growth or differentiation. These different effects are mediated by dimers of two types of BMP-receptors (BMPRs). To identify the responding cells during tooth development and search for possible tissue-or stage-specificities in the receptors involved, the distribution patterns of BMPR-IA, -IB and -II were investigated in the mouse molar, from bud to bell stage. At the bud stage, BMP-2 was suggested to be involved in the formation of an epithelial signaling center, the primary enamel knot (PEK), while BMP-4 would mediate the condensation of the mesenchyme. Immunostaining showed the presence of BMPR-IA and -II in the epithelium instead of BMPR-IB and -II in the mesenchyme. At the cap stage, BMPR-IB was detected in the epithelium but not BMPR-II, suggesting the existence of another type II receptor to form a functional dimer. At the late cap stage in the epithelium, BMP-4, BMPR-IA and -II were restricted to the internal part of the PEK and the stalk: two apoptotic areas. The three proteins were detected in the mesenchyme, showing a strong staining where cusps were about to form. At the late bell stage, BMP-2 or -4 may induce cell differentiation. BMPR-IB and -II were detected in odontoblasts instead of BMPR-IA and -II in ameloblasts. These results provide the first evidence of multiple type I and type II BMP-receptors, expressed in the dental epithelium and mesenchyme at different stages of development, to signal different cellular activities in a time- and tissue-specific way.

Animals↗

PubMed2004

Immunolocalization of BMP-2/-4, FGF-4, and WNT10b in the developing mouse first lower molar.

Intercellular signaling controls all steps of odontogenesis. The purpose of this work was to immunolocalize in the developing mouse molar four molecules that play major roles during odontogenesis: BMP-2, -4, FGF-4, and WNT10b. BMP-2 and BMP-4 were detected in the epithelium and mesenchyme at the bud stage. Staining for BMP-2 markedly increased at the cap stage. The relative amount of BMP-4 strongly increased from E14 to E15. At E15, BMP-4 was detected in the internal part of the enamel knot where apoptosis was intense. In contrast to TGFbeta1, BMP-2 and -4 did not show accumulation at the epithelial-mesenchymal junction where the odontoblast started differentiation. When odontoblasts became functional, BMP-2 and BMP-4 were detected at the apical and basal poles of preameloblasts. BMP-2, which induces ameloblast differentiation in vitro, may also be involved physiologically. The decrease in FGF-4 from E14 to E15 supports a possible role for the growth factor in the control of mesenchymal cell proliferation. The relative amount of FGF-4 was maximal at E17. The subsequent decrease at E19 showed correlation with the withdrawal of odontoblasts and ameloblasts from the cell cycle. WNT10b might also stimulate cell proliferation. At E14-15, WNT10b was present in the mesenchyme and epithelium except for the enamel knot, where the mitotic activity was very low. At E19 there was a decreasing gradient of staining from the cervical loop where cells divide to the tip of the cusp in the inner dental epithelium where cells become postmitotic. The target cells for FGF-4 and WNT10b appeared different.

Ameloblasts↗

PubMed2000

Expression of intercellular adhesion molecule-1 in C6 glioma cells is up-regulated by thyroid hormone.

ICAM-1 is a cell surface adhesion glycoprotein playing an essential role in inflammatory responses. We have investigated the effects of the thyroid hormone T3 on the expression of the ICAM-1 gene in C6 glioma cells. In these cells, T3 stimulated the ICAM-1 protein expression significantly after 24 h of treatment. The induction of ICAM-1 by cytokines such as interleukin 1beta or tumour necrosis factor TNF as well as by lipopolysaccharide or T3 can be suppressed by the two anti-inflammatory compounds dexamethasone and parthenolide. The C6 glioma cell line could then be a useful model for studying the effect of T3 hormone on the expression of specific genes in glial cells, especially genes involved in lymphocyte-glial cell interactions.

Actins↗

PubMed2000

Receptor-mediated endocytosis of transthyretin by ependymoma cells.

Transthyretin (TTR) is involved in the transport of thyroxine (T4) and retinol-binding protein (RBP) in cerebrospinal fluid (CSF) and serum. TTR is secreted in the CSF by the epithelial cells of choroid plexus. The binding of [(125)I]TTR to cultured ependymoma cells which form the brain cerebrospinal barrier, was studied to determine whether these cells carry receptor(s) for TTR. TTR was bound by ependymoma cells in a time-dependent manner reaching equilibrium within 2 h. Scatchard analysis was consistent with a single class of high-affinity binding sites with a K(d) of approximately 18 nM. Saturable high-affinity binding of human TTR has previously been described in rat primary hepatocytes and human renal adenocarcinoma, neuroblastoma, hepatoma and astrocytoma cells, and also transformed lung cells. Endocytosis of fluorescent or biotinylated TTR was observed in ependymoma cells in cytoplasmic vesicles but TTR did not colocalize with clathrin in endocytic coated vesicles. Endocytosis of TTR was inhibited by high sucrose concentration (0.45 M). Finally, ligand blotting and chemical-linking experiments revealed the presence of a approximately 100 kDa putative TTR receptor on the ependymoma cell membrane. Receptor binding of TTR provides a potential mechanism for the delivery of T4 within the central nervous system.

Animals↗

PubMed2000

Rat oligodendrocytes express the vitamin D(3) receptor and respond to 1,25-dihydroxyvitamin D(3).

The present study investigates the presence of vitamin D receptor (VDR) in cells of the rat oligodendrocyte (OL) lineage. VDR transcripts were detected by in situ hybridization in a fraction of rat OL in secondary cultures. The VDR protein was shown to be co-localized in cells that are also recognized by an anti-myelin basic protein (MBP) antibody. Likewise, in vivo, VDR-positive cells were found in the brain white matter, such as the internal capsule of the striatum or the corpus callosum but also in the spinal cord. At least part of these positive cells in vivo correspond to OL, since they were co-stained by an anti-carbonic anhydrase II antiserum. Northern blot analyses of the CG-4 OL cell line demonstrated that the VDR transcripts are already found in the O-2A precursors. There was a two-fold increase in the relative abundance of these transcripts in differentiated OL or in type-2 astrocytes. 1, 25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] increased the pool of transcripts encoding its own receptor, the VDR. The hormone also enhanced the abundance of the mRNA of the nerve growth factor (NGF) and of its low-affinity receptor, the p75(NTR) protein. By contrast, the hormone had no effect on the levels of MBP or proteolipid protein (PLP) mRNA. This finding suggests that unlike retinoic acid (RA) or thyroid hormone, 1,25-(OH)(2)D(3) has no regulatory action on the synthesis of myelin proteins.

Animals↗

PubMed1999

Astrocytes induce several blood-brain barrier properties in non-neural endothelial cells.

The passage of immunocompetent cells across the blood-brain barrier (BBB) is regulated at the level of the cerebral capillaries which have specific morphological and biochemical properties. We have developed and characterized an in vitro model of the BBB using immortalized human endothelial cells (ECV 304) induced by rat astrocytes. In this model, endothelial cells are attached together by continuous intercellular junctions with numerous tight junctions, develop a permeability barrier having a significant transcellular electrical resistance, possess high activities of gamma-glutamyl transpeptidase (gamma-GTP) and express the brain-type glucose transporter 1 (GLUT-1). These parameters are also characteristic of brain capillary endothelial cells. Under the culture conditions used, the ECV 304 cells express the intercellular adhesion molecule-1 (ICAM-1) on the external plasma membrane at concentrations which could permit lymphocyte adhesion to be studied.

Animals↗

PubMed1999

Dexamethasone represses 3,5,3'-triiodothyronine-stimulated expression of intercellular adhesion molecule-1 in the human cell line ECV 304.

The effect of the thyroid hormone L-3,5,3'-triiodothyronine (T3) on the expression of ICAM-1, a cell surface glycoprotein playing a pivotal role in inflammatory responses, was investigated. In ECV 304 cells, T3 (30 nmol/L) markedly increased ICAM-1 protein expression, with a peak after 24 h of treatment. ECV 304 human cells express both alpha1 and beta1 T3 receptors. In an attempt to understand the molecular mechanisms leading to the induction of the ICAM-1 gene by T3, we have studied the effects of a synthetic glucocorticoid, dexamethasone, and of a sesquiterpene lactone, parthenolide, on this T3-stimulated expression of ICAM-1. Our results demonstrate a repressive effect of dexamethasone and parthenolide on the expression of the protein ICAM-1 stimulated by T3. Both anti-inflammatory compounds interfere with this T3-mediated pathway in a dose-dependent manner.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1998

The presence of transthyretin in rat ependymal cells is due to endocytosis and not synthesis.

The presence and synthesis of transthyretin, a major carrier protein of thyroxine in rat cerebrospinal fluid, was investigated in choroid plexus epithelial cells and ependymal cells by immunocytochemistry, in situ hybridization, and analysis by Northern and Western blot using a specific oligonucleotide probe and a specific polyclonal antibody to transthyretin. Choroid plexus epithelial cells expressed transthyretin at high levels in developing rat cerebral hemispheres and in cultured cells. These cells secreted transthyretin into the cerebrospinal fluid. In the developing rat brain transthyretin was present in the cytoplasm of ependymal cells, in vesicles in contact with the apical membrane and in cilia. In ependymal cell cultures this protein was particularly abundant in the cilia of these cells. In contrast, ependymal cells did not synthesize transthyretin. It is postulated that transthyretin is transported to ependymal cells from the cerebrospinal fluid by endocytosis.

Animals↗

PubMed1998

Ependymal and choroidal cells in culture: characterization and functional differentiation.

During the past 10 years, our teams developed long-term primary cultures of ependymal cells derived from ventricular walls of telencephalon and hypothalamus or choroidal cells (modified ependymal cells) derived from plexuses dissected out of fetal or newborn mouse or rat brains. Cultures were established in serum-supplemented or chemically defined media after seeding on serum-, fibronectin-, or collagen-laminin-coated plastic dishes or semipermeable inserts. To identify and characterize cell types growing in our cultures, we used morphological features provided by phase contrast, scanning, and transmission electron microscopy. We used antibodies against intermediate filament proteins (vimentin, glial fibrillary acidic protein, cytokeratin, desmin, neurofilament proteins), actin, myosin, ciliary rootlets, laminin, and fibronectin in single or double immunostaining, and monoclonal antibodies against epitopes of ependymal or endothelial cells, to recognize ventricular wall cell types with immunological criteria. Ciliated or nonciliated ependymal cells in telencephalic cultures, tanycytes and ciliated and nonciliated ependymal cells in hypothalamic cultures always exceeded 75% of the cultured cells under the conditions used. These cells were characterized by their cell shape and epithelial organization, by their apical differentiations observed by scanning and transmission electron microscopy, and by specific markers (e.g., glial fibrillary acidic protein, ciliary rootlet proteins, DARPP 32) detected by immunofluorescence. All these cultured ependymal cell types remarkably resembled in vivo ependymocytes in terms of molecular markers and ultrastructural features. Choroidal cells were also maintained for several weeks in culture, and abundantly expressed markers were detected in both choroidal tissue and culture (Na+-K+-dependent ATPase, DARPP 32, G proteins, ANP receptors). In this review, the culture models we developed (defined in terms of biological material, media, substrates, duration, and subculturing) are also compared with those developed by other investigators during the last 10 years. Focusing on morphological and functional approaches, we have shown that these culture models were suitable to investigate and provide new insights on (1) the gap junctional communication of ependymal, choroidal, and astroglial cells in long-term primary cultures by freeze-fracture or dye transfer of Lucifer Yellow CH after intracellular microinjection; (2) some ionic channels; (3) the hormone receptors to tri-iodothyronine or atrial natriuretic peptides; (4) the regulatory effect of tri-iodothyronine on glutamine synthetase expression; (5) the endocytosis and transcytosis of proteins; and (6) the morphogenetic effects of galactosyl-ceramide. We also discuss new insights provided by recent results reported on in vitro ependymal and choroidal expressions of neuropeptide-processing enzymes and neurosecretory proteins or choroidal expression of transferrin regulated through serotoninergic activation.

Animals↗

PubMed1997

Expression of thyroid hormone receptors alpha and beta-1 messenger RNAs in human endothelial cells. The T3 hormone stimulates the synthesis of the messenger RNA of the intercellular adhesion molecule-1.

A study of the effect of the L-3,5,3'-triiodothyronine hormone on the expression of the mRNA of the adhesion molecule ICAM-1 led to the observation that the mRNA level is slightly up-regulated in human umbilical-cord endothelial cells. To analyze this induction at a molecular level, the search of T3 hormone receptors was undertaken. In this paper, we show that ECV 304 endothelial cells express the mRNAs encoding two thyroid hormone receptor isoforms alpha(alpha1 and alpha2) and one beta(beta1). This is, to our knowledge, a first important step towards the demonstration of the involvement of these receptors in the induction of the expression of ICAM-1 by the T3 hormone.

Cell Line↗

PubMed1995

Human lymphocyte activation is associated with the early and high-level expression of the endogenous lectin CSL at the cell surface.

Lymphocytes undergo activation in response to antigens, cytokines, lectins and antibodies interacting with specific cell-surface molecules or through substances influencing signal transduction pathways. This study shows that human T- and B-cells stimulated using phorbol esters or plant lectins express early (2 h using phorbol esters and 24 h using plant lectins) a high level of a polyvalent carbohydrate-binding protein, the cerebellar soluble lectin (CSL), which is in part externalized. The lectin, immunologically related to CDw70, interacts with specific glycoprotein ligands of the lymphocyte surface, including CD3 on T-cells and CD24 on B-cells. Major changes in phosphorylations associated with activation appear as largely CSL-dependent since they are specifically inhibited by anti-CSL Fab fragments. It is suggested that the lectin induces the clustering of specific cell-surface glycoproteins and plays the role of an endogenous amplifier of activation signals.

Agglutination Tests↗

PubMed1995

Increased axonal regrowth of lesioned rat sciatic nerve by veratrylguanidine methane sulfonate.

Neurotrophic factors appear as essential factors for normal development and repair of the nervous tissue. Veratrylguanidine methane sulfonate, has been shown to induce important neurite outgrowth of cultured dorsal root ganglia isolated from newborn rats. Its action was similar to that of NGF and was found to be additive to that of NGF. In order to see if this compound was able to stimulate axonal growth in adult animals, we examined the effect of this substance on the regeneration of the lesioned sciatic nerve. Using histochemical, immunohistochemical and ultrastructural studies, it is shown that a single intraperitoneal injection of veratrylguanidine methane sulfonate significantly increases the axonal growth during repair of the adult rat sciatic nerve. The efficiency of this substance is explained by its good targeting and long life time in the sciatic nerve.

Animals↗

PubMed1995

An endogenous lectin and its glycoprotein ligands are triggering basal and axon-induced Schwann cell proliferation.

The proliferation of Schwann cells (the myelinating cells of the peripheral nervous system) is stimulated by the contact with axonal membranes. It is suggested that the endogenous carbohydrate-binding protein (lectin) cerebellar soluble lectin (CSL) bound to ligands at the surface of axonal preparations is mitogenic for Schwann cells. Both autocrine and axon-stimulated Schwann cell proliferations seem to be dependent on the presence of CSL and its ligands at the Schwann cell surface, as suggested by the effects of N-glycosylation inhibitors and anti-CSL Fab fragments. These data suggest that CSL regulates Schwann cell proliferation by clustering of a few glycoprotein ligands at the cell surface, consequently modulating phosphorylations.

1-Deoxynojirimycin↗

PubMed1994

Presence of anti-CSL antibodies in the cerebrospinal fluid of patients: a sensitive and specific test in the diagnosis of multiple sclerosis.

The carbohydrate-binding protein (lectin) CSL is an antigen involved in the stabilization of the myelin structure by interacting with the carbohydrate moiety of myelin glycoproteins. Since anti-CSL Fab fragments were able to produce destruction of CNS myelin in vitro, CSL was considered as a potential immunological target in multiple sclerosis. The presence of anti-CSL antibodies has been examined in the cerebrospinal fluid of 1388 different patients with various neurological diseases. It is concluded that the presence of anti-CSL antibodies in the cerebrospinal fluid of patients less than 50 years old constitutes a very sensitive and specific test for multiple sclerosis.

Antibodies↗