Observations with the electron microscope on enameloid formation in the common eel ( Anguilla anguilla ; Teleostei)

1976 ◽  
Vol 194 (1115) ◽  
pp. 253-269 ◽  
Keyword(s):  
Matrix Protein ◽  
Basal Layer ◽  
Tooth Germ ◽  
Anguilla Anguilla ◽  
Cell Types ◽  
Secretory Cells ◽  
Oral Epithelium ◽  
Collagen Fibres ◽  
The Matrix ◽  
Cell Layers

In the eel, the very young tooth germ consisted of an invagination into the oral epithelium, filled with a papilla of mesenchymal cells. The basal layer of the epithelium surrounding the papilla became the inner dental epithelium (i. d. e.). Initially both the i. d. e. and the papilla cells were undifferentiated. Subsequently, the i. d. e. cells and the superficial cells of the papilla differentiated, the latter becoming odontoblasts, and the matrix of cap enameloid was laid down between the two cell layers. Differentiation of the i. d. e. cells and odontoblasts proceeded in parallel, both cell types acquiring the features of secretory cells, namely enlarged nucleoli, abundant rough endoplasmic reticulum, an active Golgi apparatus and numerous vesicles. Confluence of vesicles with the distal cell membranes was observed. These findings indicate that both the i. d. e. and odontoblasts synthesize protein and secrete it into the matrix of cap enameloid, in confirmation of previous studies with autoradiography (Shellis & Miles 1974). The matrix of cap enameloid reached its mature size and shape without becoming mineralized. It contained collagen fibres, odontoblast processes and vesicles. Mineralization of cap enameloid appeared to proceed centrifugally. The crystals were large and ribbon-like, as in enamel, and their orientation conformed with the pattern of collagen fibres of the matrix. The matrix protein, including the fibres, was, however, removed during mineralization, apparently by way of the i. d. e., which showed special features at this stage associated with transport of both protein and mineral. The collar enameloid in this fish was only about 2 μm thick and consisted of two hypermineralized layers. The inner layer appeared to be homologous with the cap enameloid, being formed by the joint activity of odontoblasts and the i. d. e. of Hertwig’s sheath. The outer, more heavily mineralized layer appeared to be produced entirely by the i. d. e. and a similar layer was laid down on the outer surface of the cap enameloid. The teeth of the eel thus bear a layer of enameloid, covered in turn by a much thinner layer which may be homologous with enamel.

scholarly journals Ameloblastin is a cell adhesion molecule required for maintaining the differentiation state of ameloblasts

2004 ◽  
Vol 167 (5) ◽  
pp. 973-983 ◽  
Author(s):  
Satoshi Fukumoto ◽  
Takayoshi Kiba ◽  
Bradford Hall ◽  
Noriyuki Iehara ◽  
Takashi Nakamura ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Adhesion Molecule ◽  
Cell Adhesion Molecule ◽  
Matrix Protein ◽  
Oral Epithelium ◽  
Enamel Matrix Protein ◽  
Mineralized Tissues ◽  
The Matrix ◽  
A Cell ◽  
Dental Epithelium

Tooth morphogenesis results from reciprocal interactions between oral epithelium and ectomesenchyme culminating in the formation of mineralized tissues, enamel, and dentin. During this process, epithelial cells differentiate into enamel-secreting ameloblasts. Ameloblastin, an enamel matrix protein, is expressed by differentiating ameloblasts. Here, we report the creation of ameloblastin-null mice, which developed severe enamel hypoplasia. In mutant tooth, the dental epithelium differentiated into enamel-secreting ameloblasts, but the cells were detached from the matrix and subsequently lost cell polarity, resumed proliferation, and formed multicell layers. Expression of Msx2, p27, and p75 were deregulated in mutant ameloblasts, the phenotypes of which were reversed to undifferentiated epithelium. We found that recombinant ameloblastin adhered specifically to ameloblasts and inhibited cell proliferation. The mutant mice developed an odontogenic tumor of dental epithelium origin. Thus, ameloblastin is a cell adhesion molecule essential for amelogenesis, and it plays a role in maintaining the differentiation state of secretory stage ameloblasts by binding to ameloblasts and inhibiting proliferation.

scholarly journals The matrix protein CCN1 (CYR61) induces apoptosis in fibroblasts

2005 ◽  
Vol 171 (3) ◽  
pp. 559-568 ◽  
Author(s):  
Viktor Todorovicç ◽  
Chih-Chiun Chen ◽  
Nissim Hay ◽  
Lester F. Lau
Keyword(s):  
Cell Adhesion ◽  
Cell Survival ◽  
Matrix Protein ◽  
De Novo ◽  
Cell Types ◽  
Cellular Interaction ◽  
Cytochrome C Release ◽  
The Matrix ◽  
Promote Cell Survival ◽  
Integrin Α6β1

Integrin-mediated cell adhesion to extracellular matrix proteins is known to promote cell survival, whereas detachment from the matrix can cause rapid apoptotic death in some cell types. Contrary to this paradigm, we show that fibroblast adhesion to the angiogenic matrix protein CCN1 (CYR61) induces apoptosis, whereas endothelial cell adhesion to CCN1 promotes cell survival. CCN1 induces fibroblast apoptosis through its adhesion receptors, integrin α6β1 and the heparan sulfate proteoglycan (HSPG) syndecan-4, triggering the transcription-independent p53 activation of Bax to render cytochrome c release and activation of caspase-9 and -3. Neither caspase-8 activity nor de novo transcription or translation is required for this process. These results show that cellular interaction with a specific matrix protein can either induce or suppress apoptosis in a cell type–specific manner and that integrin α6β1-HSPGs can function as receptors to induce p53-dependent apoptosis.

scholarly journals Evolution toward beta common chain receptor usage links the matrix proteins of HIV-1 and its ancestors to human erythropoietin

2020 ◽  
Vol 118 (2) ◽  
pp. e2021366118
Author(s):  
Francesca Caccuri ◽  
Pasqualina D’Ursi ◽  
Matteo Uggeri ◽  
Antonella Bugatti ◽  
Pietro Mazzuca ◽  
...  
Keyword(s):  
Matrix Protein ◽  
Molecular Mimicry ◽  
Cell Types ◽  
Biological Data ◽  
Matrix Proteins ◽  
Target Cells ◽  
Human Erythropoietin ◽  
The Matrix ◽  
The Difference ◽  
Hiv 1

The HIV-1 matrix protein p17 (p17) is a pleiotropic molecule impacting on different cell types. Its interaction with many cellular proteins underlines the importance of the viral protein as a major determinant of human specific adaptation. We previously showed the proangiogenic capability of p17. Here, by integrating functional analysis and receptor binding, we identify a functional epitope that displays molecular mimicry with human erythropoietin (EPO) and promotes angiogenesis through common beta chain receptor (βCR) activation. The functional EPO-like epitope was found to be present in the matrix protein of HIV-1 ancestors SIV originated in chimpanzees (SIVcpz) and gorillas (SIVgor) but not in that of HIV-2 and its ancestor SIVsmm from sooty mangabeys. According to biological data, evolution of the EPO-like epitope showed a clear differentiation between HIV-1/SIVcpz-gor and HIV-2/SIVsmm branches, thus highlighting this epitope on p17 as a divergent signature discriminating HIV-1 and HIV-2 ancestors. P17 is known to enhance HIV-1 replication. Similarly to other βCR ligands, p17 is capable of attracting and activating HIV-1 target cells and promoting a proinflammatory microenvironment. Thus, it is tempting to speculate that acquisition of an epitope on the matrix proteins of HIV-1 ancestors capable of triggering βCR may have represented a critical step to enhance viral aggressiveness and early human-to-human SIVcpz/gor dissemination. The hypothesis that the p17/βCR interaction and βCR abnormal stimulation may also play a role in sustaining chronic activation and inflammation, thus marking the difference between HIV-1 and HIV-2 in term of pathogenicity, needs further investigation.

Utilization of M06-G3 Immortalized Odontoblast Cells in Studies Regarding Dentinogenesis

2001 ◽  
Vol 15 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Mary MacDougall ◽  
Aaron Unterbrink ◽  
David Carnes ◽  
Sheela Rani ◽  
Xianhong Luan ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Cell Line ◽  
Transforming Growth Factor Beta ◽  
Matrix Protein ◽  
Transforming Growth Factor ◽  
Cell Types ◽  
Oral Epithelium ◽  
Specific Gene ◽  
Dentin Matrix Protein

Tooth formation is the result of reciprocal instructive interactions between oral epithelium and cranial neural-crest-derived ectomesenchymal tissues. These interactions lead to the cytodifferentiation of highly specialized matrix-forming cell types, the ameloblast, odontoblast, and cementoblast, that produce the mineralized tissues enamel, dentin, and cementum, respectively. Our laboratory has been developing immortalized dental cell lines representative of these various cell types to facilitate studies on gene regulation, cell differentiation, matrix formation, and mineralization. Odontoblasts are solely responsible for the synthesis and secretion of the dentin extracellular matrix bilayer that consists of non-mineralized predentin and mineralized dentin. The mouse immortalized M06-G3 cell line expresses the major matrix proteins associated with the odontoblast phenotype, producing a matrix that is capable of mineralization. This cell line serves as a useful tool in studies designed to explore the various processes of dentinogenesis. In this paper, we present studies using the mouse odontoblast cell line M06-G3 as examples of the various research applications. Studies highlighted are: in vitro promoter studies investigating the tooth-specific gene regulation of the major noncollagenous dentin matrix protein, dentin sialophosphoprotein; regulation of tertiary dentin formation by cytokines, such as transforming growth factor-Beta 1; and the utilization of dentally relevant cells in dental material biocompatibility testing

scholarly journals HIFα independent mechanisms in renal carcinoma cells modulate divergent outcomes in fibronectin assembly mediated by hypoxia and CoCl2

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Carina Magdaleno ◽  
Leah Dixon ◽  
Narendiran Rajasekaran ◽  
Archana Varadaraj
Keyword(s):  
Cell Migration ◽  
Cancer Cells ◽  
Renal Cancer ◽  
Matrix Protein ◽  
Tumor Hypoxia ◽  
Cell Types ◽  
Low Oxygen ◽  
Core Matrix ◽  
New Findings ◽  
The Matrix

Abstract Fibronectin (FN) is a core matrix protein that assembles to form a dynamic cellular scaffold, frequently perturbed during oncogenic transformation. Tumor hypoxia, characterized by low oxygen concentrations in the microenvironment of most solid tumors has been shown to accelerate FN assembly in fibroblasts and cancer-associated fibroblasts, cell types that produce abundant amounts of FN protein. Nevertheless, FN matrix regulation in epithelial cancer cells during hypoxia remains less well defined. In this study we investigate the assembly of the FN matrix during hypoxia in renal cancer epithelial cells, the cells of origin of renal cell carcinoma (RCC). We show that hypoxia (1% O2) specifically increases matrix disassembly and increases migratory propensity in renal cancer cells. However, HIFα stabilization using hypoxia mimetics, does not recapitulate the effect of hypoxia on FN matrix reorganization or cell migration. Using a combination of knockdown and inhibitor-based approaches, our work characterizes the signaling events that mediate these two disparate changes on the matrix and explores its functional significance on chemotactic cell migration. Our study systematically reexamines the role of hypoxia mimetics as experimental substitutes for hypoxia and provides new findings on HIFα stabilization and the FN matrix in the context of renal cancer.

scholarly journals Analysis of the Viral Elements Required in the Nuclear Import of HIV-1 DNA

2009 ◽  
Vol 84 (2) ◽  
pp. 729-739 ◽  
Author(s):  
Lise Rivière ◽  
Jean-Luc Darlix ◽  
Andrea Cimarelli
Keyword(s):  
Nuclear Import ◽  
Matrix Protein ◽  
Active Phase ◽  
Cell Types ◽  
Target Cells ◽  
Nuclear Pore ◽  
Viral Dna ◽  
The Matrix ◽  
Central Polypurine Tract ◽  
Hiv 1

ABSTRACT HIV-1 possesses an exquisite ability to infect cells independently from their cycling status by undergoing an active phase of nuclear import through the nuclear pore. This property has been ascribed to the presence of karyophilic elements present in viral nucleoprotein complexes, such as the matrix protein (MA); Vpr; the integrase (IN); and a cis-acting structure present in the newly synthesized DNA, the DNA flap. However, their role in nuclear import remains controversial at best. In the present study, we carried out a comprehensive analysis of the role of these elements in nuclear import in a comparison between several primary cell types, including stimulated lymphocytes, macrophages, and dendritic cells. We show that despite the fact that none of these elements is absolutely required for nuclear import, disruption of the central polypurine tract-central termination sequence (cPPT-CTS) clearly affects the kinetics of viral DNA entry into the nucleus. This effect is independent of the cell cycle status of the target cells and is observed in cycling as well as in nondividing primary cells, suggesting that nuclear import of viral DNA may occur similarly under both conditions. Nonetheless, this study indicates that other components are utilized along with the cPPT-CTS for an efficient entry of viral DNA into the nucleus.

Periodic Structure in the Matrix Protein of an Insect Virus

1982 ◽  
Vol 40 ◽  
pp. 302-303
Author(s):  
H.M. Mazzone ◽  
W.F. Engler ◽  
R. Zerillo ◽  
G.F. Bahr
Keyword(s):  
Inclusion Body ◽  
Periodic Structure ◽  
Matrix Protein ◽  
Malacosoma Disstria ◽  
Insect Virus ◽  
Virus Particles ◽  
The Matrix ◽  
Nucleopolyhedrosis Virus

The nucleopolyhedrosis virus (NPV) of the forest tent cater - pillar (Malacosoma disstria Hubner) has been analyzed in our laboratories. As a representative of the Baculovirus class, the NPV has virus particles enclosed with in a proteinaceous structure, the inclusion body.

Correlative transmission and high-resolution scanning electron microscopic studies on pituitary cells

1990 ◽  
Vol 48 (3) ◽  
pp. 20-21
Author(s):  
S. Tai
Keyword(s):  
Cell Types ◽  
Depth Of Field ◽  
Secretory Cells ◽  
Specific Cell ◽  
Pituitary Cells ◽  
Electron Microscopic ◽  
3 Dimensional ◽  
Microscopic Studies ◽  
Structure And Activity ◽  
Intracellular Structure

Extensive cytological and histological research, correlated with physiological experimental analysis, have been done on the anterior pituitaries of many different vertebrates which have provided the knowledge to create the concept that specific cell types synthesize, store and release their specific hormones. These hormones are stored in or associated with granules. Nevertheless, there are still many doubts - that need further studies, specially on the ultrastructure and physiology of these endocrine cells during the process of synthesis, transport and secretion, whereas some new methods may provide the information about the intracellular structure and activity in detail.In the present work, ultrastructural study of the hormone-secretory cells of chicken pituitaries have been done by using TEM as well as HR-SEM, to correlate the informations obtained from 2-dimensional TEM micrography with the 3-dimensional SEM topographic images, which have a continous surface with larger depth of field that - offers the adventage to interpretate some intracellular structures which were not possible to see using TEM.

scholarly journals Anaphylactic Degranulation of Mast Cells: Focus on Compound Exocytosis

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Ofir Klein ◽  
Ronit Sagi-Eisenberg
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Molecular Mechanisms ◽  
Secretory Granules ◽  
Cell Types ◽  
Secretory Cells ◽  
Regulated Exocytosis ◽  
Open Questions ◽  
Conflicting Evidence ◽  
Compound Exocytosis

Anaphylaxis is a notorious type 2 immune response which may result in a systemic response and lead to death. A precondition for the unfolding of the anaphylactic shock is the secretion of inflammatory mediators from mast cells in response to an allergen, mostly through activation of the cells via the IgE-dependent pathway. While mast cells are specialized secretory cells that can secrete through a variety of exocytic modes, the most predominant mode exerted by the mast cell during anaphylaxis is compound exocytosis—a specialized form of regulated exocytosis where secretory granules fuse to one another. Here, we review the modes of regulated exocytosis in the mast cell and focus on compound exocytosis. We review historical landmarks in the research of compound exocytosis in mast cells and the methods available for investigating compound exocytosis. We also review the molecular mechanisms reported to underlie compound exocytosis in mast cells and expand further with reviewing key findings from other cell types. Finally, we discuss the possible reasons for the mast cell to utilize compound exocytosis during anaphylaxis, the conflicting evidence in different mast cell models, and the open questions in the field which remain to be answered.

scholarly journals Signaling Control of Mucociliary Epithelia: Stem Cells, Cell Fates, and the Plasticity of Cell Identity in Development and Disease

2021 ◽  
pp. 1-18
Author(s):  
Peter Walentek
Keyword(s):  
Stem Cells ◽  
Mucociliary Clearance ◽  
Cell Types ◽  
Secretory Cells ◽  
Chronic Obstructive ◽  
Cell Identity ◽  
Obstructive Pulmonary Disease ◽  
Congenital Diseases ◽  
Inhaled Particles ◽  
Mucociliary Epithelia

Mucociliary epithelia are composed of multiciliated, secretory, and stem cells and line various organs in vertebrates such as the respiratory tract. By means of mucociliary clearance, those epithelia provide a first line of defense against inhaled particles and pathogens. Mucociliary clearance relies on the correct composition of cell types, that is, the proper balance of ciliated and secretory cells. A failure to generate and to maintain correct cell type composition and function results in impaired clearance and high risk to infections, such as in congenital diseases (e.g., ciliopathies) as well as in acquired diseases, including asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). While it remains incompletely resolved how precisely cell types are specified and maintained in development and disease, many studies have revealed important mechanisms regarding the signaling control in mucociliary cell types in various species. Those studies not only provided insights into the signaling contribution to organ development and regeneration but also highlighted the remarkable plasticity of cell identity encountered in mucociliary maintenance, including frequent trans-differentiation events during homeostasis and specifically in disease. This review will summarize major findings and provide perspectives regarding the future of mucociliary research and the treatment of chronic airway diseases associated with tissue remodeling.

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