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B Verrier

Publications and source records attributed to B Verrier.

88 records · Page 5Linked to original sources
PubMed1983

Thyroid follicular morphogenesis mechanism: organ culture of the fetal gland as an experimental approach.

The morphological and physiological changes induced by organ culture and thyroid-stimulating hormone (TSH) stimulation in the rat fetal thyroid gland were studied. Organ culture increased Golgi activity which was further enhanced by TSH, subsequently facilitating the formation of intracellular lumina. TSH also raised the intracellular cAMP level. The intracellular lumina observed during follicular morphogenesis are structurally comparable to typical intracellular cavities formed in adult thyroid cells, which are considered as being the result of increased Golgi activity. The intracellular lumen, therefore, is probably not a physiologically significant step in thyroid morphogenesis.

Animals↗
PubMed1983

Polarization of thyroid cells in culture: evidence for the basolateral localization of the iodide "pump" and of the thyroid-stimulating hormone receptor-adenyl cyclase complex.

When cultured in collagen gel-coated dishes, thyroid cells organized into polarized monolayers. The basal poles of the cells were in contact with the collagen gel, whereas the apical surfaces were facing the culture medium. Under these culture conditions, thyroid cells do not concentrate iodide nor respond to acute stimulation by thyroid-stimulating hormone (TSH). To allow the free access of medium components to the basal poles, the gel was detached from the plastic dish and allowed to float in the culture medium. After release of the gel, the iodide concentration and acute response to TSH stimulation were restored. Increased cAMP levels, iodide efflux, and formation of apical pseudopods were observed. When the thyroid cells are cultured on collagen-coated Millipore filters glued to glass rings, the cell layer separates the medium in contact with the apical domain of the plasma membrane (inside the ring) from that bathing the basolateral domain (outside the ring). Iodide present in the basal medium was concentrated in the cells, whereas no transport was observed when iodide was added to the luminal side. Similarly, an acute effect of TSH was observed only when the hormone was added to the basal medium. These results show that the iodide concentration mechanism and the TSH receptor-adenylate cyclase complex are present only on the basolateral domain of thyroid cell plasma membranes.

Adenylyl Cyclases↗
PubMed1977

Thyrotropin binding to and adenylate cyclase activity of porcine thyroid plasma membranes.

Plasma membranes have been purified from porcine thyroid gland homogenate by discontinuous sucrose gradient centrifugation. The preparations contained specific binding sites for thyrotropin but not for luteinizing hormone or the beta subunits of thyrotropin and luteinizing hormone. Optimum conditions of 125I-labeled thyrotropin binding were pH 6.0-6.5 and 37 degrees C. Thyrotropin binding was reduced by divalent (Ca2+, Mg2+) and monovalent cations (Na+, K+, Li+), 50% inhibition being obtained at 10 mM and 50 mM respectively. Displacement curves of 125I-labeled bovine or porcine thyrotropin by the unlabeled hormone from three species was in the order of increasing concentrations (bovine greater than porcine greater than human) which is the order of decreasing biological activity of these hormone preparations in the assay in vivo in the mouse. The validity of the results was established by controlling that porcine membranes bound the native and the 125I-labeled hormones with equal affinity. A single type of high-affinity (Kd = 0.28 nM) binding sites was detected for bovine and porcine thyrotropins. In contrast, porcine plasma membranes bound human thyrotropin with a lower affinity (Kd = 70 nM). A good correlation was found at equilibrium and in the conditions of the cyclase assay, between receptor occupancy and adenylate cyclase activation for the three hormones.

4-Nitrophenylphosphatase↗
PubMed1976

Endogenous cyclic AMP in thyroid cell culture. Effect of thyroid-stimulating hormone and dibutyryl cyclic AMP.

We have studied the variations of endogenous cyclic AMP levels in thyroid cells cultured over a period of 7 days in several conditions: in the presence of thyroid-stimulating hormone or dibutyryl cyclic AMP which both promote the aggregation of isolated cells into follicles, and in their absence when cells develop as a typical monolayer. In follicle-forming cells, the cyclic AMP level was found to rise during the first day of culture, then to fall rapidly. In monolayer-forming cells, the cyclic AMP content slightly increases attaining the same level as found in other cells at the fourth day, which remains stable till the seventh day. We have investigated the response of these cells cultured in the presence of dibutyryl cyclic AMP retain the capability of increasing their cyclic AMP concentration whereas monolayer-forming cells do not preserve this quality of thyroid cells.

Animals↗
PubMed1975

Thyrotropin-receptor interaction and cyclic AMP-mediated effects in thyroid cells.

Thyroid cells in culture constitute a suitable system for the study of thyroid gland function and its regulation. The natural thyroid stimulator (TSH) induces the in vitro reorganization of thyroid cells into three-dimensional follicles morphologically and metabolically similar to gland follicles. In contrast, nonstimulated cells develop as a monolayer and in a concerted manner rapidly lose the enzymes involved in iodine metabolosm and the aptitude to bind TSH to specific receptor sites. The morphogenetic action of TSH and its ability to maintain the specific metabolic properties of thyroid cells in culture are mediated by cyclic AMP via new RNA and new protein synthesis. Therefore comparison of the properties of a given cell type in morphologically and metabolically different status should provide a valuable tool for studying the TSH mechanism of action. Using 125-I-labeled TSH of high purity, high specific radioactivity, and preserved biologic potency, TSH interaction with intact cells and their derived plasma membranes was studied. At both the cellular and the sub-cellular level a very good agreement was found for the values of the rate and equilibrium constants of labeled TSH binding. A single type of high-affinity low-capacity site was revealed. In contrast, in both systems dissociation of bound labeled TSH was not of single-order kinetics and showed two kinetic components with half-lives of 3 and 30 min. An excellent correlation between half-stimulation of adenylate cyclase and iodide transport mechanism activation, and the dissociation constant of TSH binding, was found, indicating that the in vitro system studied was relevant to physiologic regulation.

Animals↗
PubMedDate not supplied

Chemical composition of porcine thyroid cell plasma membranes.

Plasma membranes were isolated from thyroid cells obtained by trypsinization of porcine glands and maintained in culture conditions in the presence or absence of thyrotropin or dibutyryl cyclic AMP. The protein, phospholipid, cholesterol and sialic acid content of the 3 types of cell plasma membranes were very similar. High cholesterol and sialic acid content characterized these membranes. The amino acid and carbohydrate composition was similar to that shown for other eukaryotic plasma membranes. Sodium dodecylsulfate-polyacrylamide gel electrophoresis disclosed the presence of more than 20 protein bands, of which six corresponded to glycoproteins.

Amino Acids↗
PubMedDate not supplied

In vitro HIV1 infection of CD34+ progenitor-derived dendritic/Langerhans cells at different stages of their differentiation in the presence of GM-CSF/TNF alpha.

Langerhans cells (LC) are antigen-presenting cells which are found in areas at risk of inoculation by the human immunodeficiency virus (HIV). LC were shown to be sensitive to in vitro infection by HIV1. They could be generated in vitro by culturing CD34+ haematopoietic progenitors with GM-CSF+TNF alpha. In this study, we tested the sensitivity to HIV1 infection of in vitro generated LC throughout their differentiation and we investigated the effect of such an infection on in vitro differentiation. Phenotypic controls were performed using FACS analysis on day 6 for the presence of a CD1a+ cell population, and differentiation was assessed by transmission electron microscopy on day 13 for the presence of Birbeck granules. CD34+ cells were purified from cord blood mononuclear cells by magnetic separation. Cell suspensions were infected with either a T-lymphotropic, syncytium-inducing isolate (HXB2) or a macrophage-tropic, non-syncytium-inducing isolate (Ba-L). Viral particle release was measured by p24 antigen production in the culture supernatant. A high level of p24 production was noted on day 13 of postinfection only when infection was carried out with Ba-L isolate on cells generated after 6 days in culture with GM/CSF+TNF alpha. No infection of CD34+ progenitor cells was obtained either with Ba-L isolate or HXB2. The sensitivity of Langerhans cell/dendritic cell (LC/DC) precursors to NSI isolate (Ba-L) seemed to coincide with the early stage of differentiation (CD1a antigen appearance). The infection did not alter the differentiation of in vitro generated LC, which presented their specific ultrastructural marker of epidermal environment, i.e. Birbeck granules from day 15 of the culture as compared to control culture. These results highlight the HIV infectibility of a differentiated population of LC/DC generated in vitro from CD34+ progenitors.

Antigens, CD1↗