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Biomedical subjects

H Lesot

Publications and source records attributed to H Lesot.

At least 73 records · Page 4Linked to original sources
PubMed1992

Effects of dentin proteins, transforming growth factor beta 1 (TGF beta 1) and bone morphogenetic protein 2 (BMP2) on the differentiation of odontoblast in vitro.

We have studied the effects of dentin proteins, of Transforming Growth Factor beta 1 (TGF beta 1) and Bone Morphogenetic Protein (BMP2) on the differentiation of odontoblasts in vitro. The total EDTA-soluble fraction of dentin proteins, prepared from rabbit incisors was further separated by chromatography on DEAE-Cellulose and heparin-agarose columns. While the total EDTA-soluble fraction of dentin had no effect on cultured dental papillae, fractions retained on both columns were able to initiate functional differentiation of preodontoblasts of isolated day-17 first lower mouse molar dental papillae cultured in vitro. TGF beta 1 and BMP2, both stimulated the matrix secretion by dental papillae cells. TGF beta 1 and BMP2, combined with the inactive total EDTA-soluble fraction, stimulated odontoblast differentiation. An active fraction retained on DEAE-Cellulose completely lost the inductive activity after incubation with a neutralizing anti-TGF beta antibody. These results demonstrate that a TGF beta-like molecule present in dentin could interact with some component which acts as a modulator of its activity on the initiation of the cytological and functional differentiation of odontoblasts.

Animals↗
PubMed1992

[Cell-matrix interactions and odontoblast differentiation].

The terminal differentiation of odontoblasts requires the integrity of the cytoskeleton and is controlled by cell-matrix interactions. These interactions implicate both matrix molecules and matrix-associated growth factors. On the one hand, predentin-dentin constituents were found to initiate odontoblast differentiation and to allow the maintenance of this state; TGF-beta or related molecules are implicated. Fibronectin on the other hand can induce the differentiation of second generation odontoblasts and interacts with three high molecular weight proteins present in membrane prepared from dental mesenchymal cells. One of these proteins (165 kDa) was localized on the surface of odontoblasts and is involved in the organization of microfilaments. Two main axes of research will have to be developed in the future in order to understand how matrix molecules and growth factors interactions can be modulated in time and space by epithelial and mesenchymal cells, and how such modulations can affect the phenotype of these cells.

Cell Differentiation↗
PubMed1990

Effects of cerulenin, an inhibitor of fatty acid synthesis on reconstitution of the dental basement membrane.

When trypsin-dissociated enamel organs and dental papillae were recombined in the presence of cerulenin--an antibiotic which is a potent inhibitor of fatty acid synthesis--the newly synthesized basement membrane seemed defective in a dose-dependent manner. The three-dimensional relationship between the basement membrane components and the plasma membrane appears to be regulated in part by lipids.

Animals↗
PubMed1990

A 165 kDa membrane antigen mediating fibronectin-vinculin interaction is involved in murine odontoblast differentiation.

Membrane-mediated matrix-microfilament interactions are involved in odontoblast differentiation. In this study, we analyzed the interactions of vinculin and fibronectin with plasma membrane proteins separated by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis, and then transferred onto polyvinylidene-difluoride (PVDF) paper. Vinculin was found to interact with 58, 63 and 165 kDa plasma membrane proteins. Fibronectin interacted with three high molecular weight (145, 165, and 185 kDa) membrane proteins. Attempts were made to characterize the 165 kDa protein which interacted with vinculin and with fibronectin. The interaction of the 165 kDa protein with fibronectin was not competitively inhibited by synthetic peptides such as GRGDS or GRGDSP, suggesting that the protein was not related to integrins. Antibodies directed against the 165 kDa protein allowed the identification of the precise localization and biological role of this membrane antigen. The data presented in this paper and previous observations indicate that the 165 kDa protein, involved in odontoblast elongation and polarization, mediates a fibronectin-vinculin transmembrane interaction.

Actins↗
PubMed1990

Characterization of a mouse monoclonal antibody to vimentin by indirect immunofluorescence microscopy and immunoblotting.

A murine IgM monoclonal antibody, termed MC15A13G was produced after immunization of Balb/c mouse with Swiss mouse dental papillae. This antibody, characterized by immunoblotting analysis and indirect immunofluorescence microscopy, recognized a 57 Kda protein identified as vimentin in different cell types with no cross reaction with other cytoskeletal proteins.

Animals↗
PubMed1990

In vivo morphogenetic activity of dentine matrix proteins.

Matrix proteins (EDTA-soluble and collagenase-released) from rabbit dentine have been demonstrated to show in vivo morphogenetic activity in exposed pulps of ferret canine teeth. In young adult ferrets, the reparative dentine resembled normal primary tubular dentine with odontoblast-like cells lining its formative surface. The reparative response in older animals was seen as osteo-dentine deposition. In both cases, the reparative response was characterized by its intensity within a comparatively short time period and also by the low grade or complete absence of any localized inflammatory response. Dentine matrix proteins implanted in exposed pulps of teeth provide a good experimental model for analysing the cell-matrix interactions and events taking place during odontoblast differentiation and dentinogenesis.

Aging↗
PubMed1990

Preliminary studies on the in vivo morphogenetic properties of dentine matrix proteins.

Two fractions of isolated noncollagenous extracellular matrix proteins from dentine have been implanted into the base of exposed cavities in ferret canine teeth. After sealing the cavities, reparative dentinogenesis was assessed histologically after 14 and 28 days as compared to control cavities. Reparative dentinogenesis was enhanced in the presence of these matrix proteins with evidence of tubular dentine along the walls of the exposure and on the cavity floor demonstrating the in vivo morphogenetic properties of the dentine matrix proteins.

Animals↗
PubMed1989

Direct visualization of an IgM directed against a membrane antigen involved in both cell-matrix interactions and microfilament organization.

Dental mesenchymal cells were cultured in the presence of a monoclonal antibody. MC16A16, consisting of IgM and directed against a hydrophobic 165 kDa protein. Since the epitope recognized by MC16A16 was found to be at the outer cell surface, a direct visualization of IgM antibodies was used to localize the 165 kDa antigen by transmission electron microscopy. The present results demonstrate that the 165 kDa antigen is a membrane protein.

Actin Cytoskeleton↗
PubMed1989

Immunoperoxidase localization of fibronectin during odontoblast differentiation. An ultrastructural study.

Immunoperoxidase labeling of fibronectin in one-day-old mouse first lower molars allowed to visualize a striking redistribution of this glycoprotein during terminal cytodifferentiation of odontoblasts. The modifications involved both extracellular and cell surface localizations. The possible roles of these modifications in terminal differentiation of odontoblasts are discussed.

Animals↗
PubMed1988

An extracellular matrix protein of dentine, enamel, and bone shares common antigenic determinants with keratins.

EDTA-soluble proteins extracted from rabbit dentine were injected into mice and antibodies were prepared by the hybridoma technique. A monoclonal antibody, MC9B5, was found to react with a 68 kd protein, a major component of the EDTA-soluble proteins present in rabbit and rat dentine. Weston immunoblotting demonstrated that the antigen was also present in rat enamel and bone. By indirect immunofluorescence, MC9B5 was found to specifically stain epithelial filamentous cytoskeletal structures. Double staining experiments using MC9B5 and antikeratin antibodies showed extensive co-localization on the epithelial cell cytoskeleton. Furthermore, the 68 kd extracellular matrix protein was recognized in dentine, enamel, and bone extracts by antikeratin antibodies as shown by immunoblotting. These data support a structural relationship between a mineralized tissue extracellular protein and keratins.

Animals↗
PubMed1988

Membrane-cytoskeleton interactions: inhibition of odontoblast differentiation by a monoclonal antibody directed against a membrane protein.

It is known that high-molecular-weight (HMW) membrane proteins mediate interactions with constituents of the extracellular matrix and/or with cytoskeletal elements. To study participation of HMW membrane proteins in odontoblast or ameloblast differentiation, an immunological approach has been adopted. Antibodies directed against membrane proteins (Mr, 110-190) from mouse embryos have been produced by the hybridoma technique. Supernatants of hybridoma cultures were screened for their ability to stain dental tissues and also tested for their biological activities on dental cells in primary culture or on developing tooth germs in organ culture. An IgM monoclonal antibody, MC16A16, directed against a 165-kDa antigen present in plasma membrane preparations, reacted strongly with the dental epithelium and weakly with the mesenchyme. MC16A16 also reacted with the cell surface of nonpermeabilized cultured dental cells and could detach epithelial cells cultured on glass, but not mesenchymal cells which maintained vinculin-containing focal contacts. This antibody, which affected the organization of dental-cell microfilaments in primary culture, also inhibited the polarization of odontoblasts, but not that of ameloblasts.

Animals↗
PubMed1986

Cell-matrix interactions: influence of noncollagenous proteins from dentin on cultured dental cells.

Matrix-mediated epitheliomesenchymal interactions control dental cytodifferentiations. Experiments were performed in order to study the effects of noncollagenous proteins extracted from dentin on cultured enamel organs and dental papillae. Seven noncollagenous protein fractions were prepared from rabbit incisor dentin and used as substrates to coat Millipore filters. Embryonic mouse tooth germs were dissociated and the isolated tissues were cultured for 4 days on these different substrates as well as on noncoated Millipore filters. When compared to control cultures, only two protein fractions affected the behaviour of epithelial cells. A slight elongation of the cell body and a preferential localization of the nuclei at the basal pole of the cells in contact with the filter was observed with protein fractions 5 and 6. When dental papillae were cultured on Millipore filters coated either with protein fraction 2 or fraction 6, the mesenchymal cells in contact with the filter elongated, polarized and demonstrated a high metabolic activity. Such modifications in the cell organization, implying changes in the cytoskeleton organization and, or, activity, never occurred spontaneously or in the presence of isolated collagens (I-V), laminin or fibronectin.

Amino Acids↗
PubMed1985

Dental cell interaction with extracellular-matrix constituents: type-I collagen and fibronectin.

It has been suggested that, during odontoblast differentiation, the extracellular matrix present at the epitheliomesenchymal junction modulates the activity of the cytoskeleton by means of membrane constituents (proteins, proteoglycans or gangliosides). To investigate this, we studied the interaction of iodinated fibronectin and type-I collagen with dissociated dental tissues and with membrane proteins prepared from these tissues. Isolated dental papillae and enamel organs were cultured for increasing periods of time in the presence of iodinated proteins. Fibronectin and type-I collagen were preferentially bound to dental papillae; however, after 6 h of incubation, fibronectin no longer interacted with the dental papillae, and the bound radioactivity was released. In the meantime, de novo synthesized fibronectin was deposited in the extracellular matrix of the dental papillae. Membrane proteins were prepared from isolated enamel organs and dental papillae. After sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis, these proteins were transferred to nitrocellulose by electroblotting and then incubated in the presence of either 125I-labelled fibronectin or 125I-labelled type-I collagen. Autoradiography confirmed the preferential interaction of fibronectin with the dental papilla. Fibronectin interacted with three high-molecular-weight proteins (Mr, 145,000, 154,000 and 185,000), which were not detected when membranes were prepared from enamel organs. Under the same conditions, type-I collagen did not interact with membrane proteins. The known interaction of type-I collagen with the plasma membrane of dental-papilla cells might be mediated either by another constituent of the extracellular matrix or by cell-surface-associated proteoglycans.

Animals↗
PubMed1984

Behaviour of odontogenic epithelial cells in primary culture.

Odontogenic epithelial cells in primary culture easily adhere to the substratum through close and focal contacts. The adhesion processes of well-spread cells are found to be heterogeneous with respect to sensitivity to divalent cations/chelating agents. When cells are detached by mechanical forces, material remains attached to the substratum, which shows an enrichment in actin, intermediate filament components, and a protein with a MW of 130,000 daltons. The cytoskeleton is visualized after Triton-X 100 extraction. Microfilaments are abundant at the ventral side of cells in contact with the substratum. Intermediate filaments and microfilament bundles are observed close to the nuclear surface. Stress fibers end and ravel out at the ventral side of the cell in sites corresponding to focal contacts. In some regions cells in contact with the substratum deposit extracellular material with the ultrastructural aspect of a basal lamina. This material is associated to hemidesmosomes in early stages.

Animals↗
PubMed1983

Isolation of a laminin-binding protein from muscle cell membranes.

Skeletal muscle myofibers are each ensheathed by a continuous basal lamina consisting predominantly of type IV collagen, laminin and heparan sulfate proteoglycan. In order to identify laminin-binding components in the muscle cell surface, plasma membranes from mouse thigh muscle and from rat L6 myoblasts were separated by polyacrylamide gel electrophoresis and transferred to nitrocellulose paper by electroblotting. Incubation of the transferred samples with I-labelled laminin revealed a prominent band of approximate mol. wt. 68 000. A protein of this mol. wt. was isolated by affinity chromatography of muscle cell plasma membranes on laminin-Sepharose. The hydrophobic protein has an apparent mol. wt. of 68 000 and has a high content of serine, glycine and acidic amino acids. After detergent solubilization the purified protein binds to laminin-coated Sepharose beads at a higher rate than to beads coated with either fibronectin or collagen types I and IV. The interaction of the protein, called LB 68, with laminin was also studied after incorporation into synthetic lecithin vesicles. While detergent-solubilized LB 68 bound to I-labeled laminin only at lower than physiological ionic strength, liposome-incorporated LB 68 bound to laminin in the absence of detergents under physiological conditions. We propose that this protein is involved in the interaction of myoblasts with laminin substrates and thus may participate in the anchorage of the basal lamina in the plasmalemma of myotubes.

Journal Article↗