scholarly journals Growth of mammalian cells on substrates coated with cellular microexudates. I. Effect on cell growth at low population densities.

1975 ◽  
Vol 64 (1) ◽  
pp. 135-145 ◽  
Author(s):  
L Weiss ◽  
G Poste ◽  
A MacKearnin ◽  
K Willett
Keyword(s):  
Mammalian Cells ◽  
Cell Types ◽  
Cell Populations ◽  
Growth Enhancement ◽  
Plastic Substrates ◽  
Embryo Cells ◽  
Cell Layers ◽  
Feeder Cell Layers ◽  
Different Cell Types ◽  
Macromolecular Composition

Mammalian and avian cells cultured on glass or plastic substrates produce microexudates of cellular macromolecules which remain bound to the substrate when the cells are detached. The gross macromolecular composition of microexudates from a range of diploid, heteroploid, and virus-transformed cells was determined with cells labeled with radioisotopes. Significant differences in the amounts of cellular glycoproteins, proteins, and RNA present in microexudates were found between different cell types and between cells of the same type at different stages of growth. Inoculation of cells onto substrates "coated" with microexudates altered their growth behavior. Microexudates from exponentially growing subconfluent homotypic and heterotypic cell populations enhanced the growth of mouse and chick embryo cells seeded at very low densities, but similar microexudates had no effect on the proliferation of cells seeded at higher densities. The enhanced growth of low-density cell populations seeded on microexudates was compared with the growth enhancement produced by feeder cell layers and conditioned medium.

scholarly journals A Fresh Look at the Structure, Regulation, and Functions of Fodrin

2020 ◽  
Vol 40 (17) ◽  
Author(s):  
Jamuna S. Sreeja ◽  
Rince John ◽  
Dhrishya Dharmapal ◽  
Rohith Kumar Nellikka ◽  
Suparna Sengupta
Keyword(s):  
Posttranslational Modifications ◽  
Mammalian Cells ◽  
Structural Integrity ◽  
Cell Function ◽  
Cell Types ◽  
Erythroid Cell ◽  
Structural Variations ◽  
Neuronal Tissues ◽  
Different Cell Types ◽  
Neuronal Disorders

ABSTRACT Fodrin and its erythroid cell-specific isoform spectrin are actin-associated fibrous proteins that play crucial roles in the maintenance of structural integrity in mammalian cells, which is necessary for proper cell function. Normal cell morphology is altered in diseases such as various cancers and certain neuronal disorders. Fodrin and spectrin are two-chain (αβ) molecules that are encoded by paralogous genes and share many features but also demonstrate certain differences. Fodrin (in humans, typically a heterodimer of the products of the SPTAN1 and SPTBN1 genes) is expressed in nearly all cell types and is especially abundant in neuronal tissues, whereas spectrin (in humans, a heterodimer of the products of the SPTA1 and SPTB1 genes) is expressed almost exclusively in erythrocytes. To fulfill a role in such a variety of different cell types, it was anticipated that fodrin would need to be a more versatile scaffold than spectrin. Indeed, as summarized here, domains unique to fodrin and its regulation by Ca2+, calmodulin, and a variety of posttranslational modifications (PTMs) endow fodrin with additional specific functions. However, how fodrin structural variations and misregulated PTMs may contribute to the etiology of various cancers and neurodegenerative diseases needs to be further investigated.

scholarly journals Reticulon 4a promotes exocytosis in mammalian cells

2019 ◽  
Vol 30 (18) ◽  
pp. 2349-2357 ◽  
Author(s):  
Richik Nilay Mukherjee ◽  
Daniel L. Levy
Keyword(s):  
Cell Surface ◽  
Protein Trafficking ◽  
Mammalian Cells ◽  
Cell Types ◽  
Vesicular Trafficking ◽  
Secreted Proteins ◽  
Mammalian Cell Lines ◽  
Rough Er ◽  
Different Cell Types ◽  
Functional Output

Endoplasmic reticulum (ER) tubules and sheets conventionally correspond to smooth and rough ER, respectively. The ratio of ER tubules-to-sheets varies in different cell types and changes in response to cellular conditions, potentially impacting the functional output of the ER. To directly test whether ER morphology impacts vesicular trafficking, we increased the tubule-to-sheet ratio in three different ways, by overexpressing Rtn4a, Rtn4b, or REEP5. Only Rtn4a overexpression increased exocytosis, but not overall levels, of several cell surface and secreted proteins. Furthermore, Rtn4a depletion reduced cell surface trafficking without affecting ER morphology. Similar results were observed in three different mammalian cell lines, suggesting that Rtn4a generally enhances exocytosis independently of changes in ER morphology. Finally, we show that Rtn4a levels modulate cell adhesion, possibly by regulating trafficking of integrins to the cell surface. Taking the results together, we find that altering ER morphology does not necessarily affect protein trafficking, but that Rtn4a specifically enhances exocytosis.

scholarly journals S100A6 and Its Brain Ligands in Neurodegenerative Disorders

2020 ◽  
Vol 21 (11) ◽  
pp. 3979
Author(s):  
Anna Filipek ◽  
Wiesława Leśniak
Keyword(s):  
Mammalian Cells ◽  
Brain Structures ◽  
Cell Types ◽  
Cytoskeletal Organization ◽  
High Level ◽  
S100a6 Protein ◽  
Different Cell Types ◽  
The Brain ◽  
Lateral Sclerosis

The S100A6 protein is present in different mammalian cells and tissues including the brain. It binds Ca2+ and Zn2+ and interacts with many target proteins/ligands. The best characterized ligands of S100A6, expressed at high level in the brain, include CacyBP/SIP and Sgt1. Research concerning the functional role of S100A6 and these two ligands indicates that they are involved in various signaling pathways that regulate cell proliferation, differentiation, cytoskeletal organization, and others. In this review, we focused on the expression/localization of these proteins in the brain and on their possible role in neurodegenerative diseases. Published results demonstrate that S100A6, CacyBP/SIP, and Sgt1 are expressed in various brain structures and in the spinal cord and can be found in different cell types including neurons and astrocytes. When it comes to their possible involvement in nervous system pathology, it is evident that their expression/level and/or subcellular localization is changed when compared to normal conditions. Among diseases in which such changes have been observed are Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), epileptogenesis, Parkinson’s disease (PD), Huntington’s disease (HD), and others.

scholarly journals Mitofusin 2 ablation increases endoplasmic reticulum–mitochondria coupling

2015 ◽  
Vol 112 (17) ◽  
pp. E2174-E2181 ◽  
Author(s):  
Riccardo Filadi ◽  
Elisa Greotti ◽  
Gabriele Turacchio ◽  
Alberto Luini ◽  
Tullio Pozzan ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Morphological Analysis ◽  
Cell Types ◽  
Mitofusin 2 ◽  
Electron And Fluorescence Microscopy ◽  
Microscopy Data ◽  
Key Aspects ◽  
Different Cell Types ◽  
Close Contacts

The organization and mutual interactions between endoplasmic reticulum (ER) and mitochondria modulate key aspects of cell pathophysiology. Several proteins have been suggested to be involved in keeping ER and mitochondria at a correct distance. Among them, in mammalian cells, mitofusin 2 (Mfn2), located on both the outer mitochondrial membrane and the ER surface, has been proposed to be a physical tether between the two organelles, forming homotypic interactions and heterocomplexes with its homolog Mfn1. Recently, this widely accepted model has been challenged using quantitative EM analysis. Using a multiplicity of morphological, biochemical, functional, and genetic approaches, we demonstrate that Mfn2 ablation increases the structural and functional ER–mitochondria coupling. In particular, we show that in different cell types Mfn2 ablation or silencing increases the close contacts between the two organelles and strengthens the efficacy of inositol trisphosphate (IP3)-induced Ca2+ transfer from the ER to mitochondria, sensitizing cells to a mitochondrial Ca2+ overload-dependent death. We also show that the previously reported discrepancy between electron and fluorescence microscopy data on ER–mitochondria proximity in Mfn2-ablated cells is only apparent. By using a different type of morphological analysis of fluorescent images that takes into account (and corrects for) the gross modifications in mitochondrial shape resulting from Mfn2 ablation, we demonstrate that an increased proximity between the organelles is also observed by confocal microscopy when Mfn2 levels are reduced. Based on these results, we propose a new model for ER–mitochondria juxtaposition in which Mfn2 works as a tethering antagonist preventing an excessive, potentially toxic, proximity between the two organelles.

scholarly journals TAPping into the treasures of tubulin using novel protein production methods

2018 ◽  
Vol 62 (6) ◽  
pp. 781-792
Author(s):  
Nuo Yu ◽  
Niels Galjart
Keyword(s):  
Mammalian Cells ◽  
Gene Families ◽  
Cell Types ◽  
Cellular Functions ◽  
Tubulin Isotypes ◽  
Associated Proteins ◽  
Cytoskeletal Elements ◽  
Different Cell Types ◽  
Β Tubulin

Microtubules are cytoskeletal elements with important cellular functions, whose dynamic behaviour and properties are in part regulated by microtubule-associated proteins (MAPs). The building block of microtubules is tubulin, a heterodimer of α- and β-tubulin subunits. Longitudinal interactions between tubulin dimers facilitate a head-to-tail arrangement of dimers into protofilaments, while lateral interactions allow the formation of a hollow microtubule tube that mostly contains 13 protofilaments. Highly homologous α- and β-tubulin isotypes exist, which are encoded by multi-gene families. In vitro studies on microtubules and MAPs have largely relied on brain-derived tubulin preparations. However, these consist of an unknown mix of tubulin isotypes with undefined post-translational modifications. This has blocked studies on the functions of tubulin isotypes and the effects of tubulin mutations found in human neurological disorders. Fortunately, various methodologies to produce recombinant mammalian tubulins have become available in the last years, allowing researchers to overcome this barrier. In addition, affinity-based purification of tagged tubulins and identification of tubulin-associated proteins (TAPs) by mass spectrometry has revealed the ‘tubulome’ of mammalian cells. Future experiments with recombinant tubulins should allow a detailed description of how tubulin isotype influences basic microtubule behaviour, and how MAPs and TAPs impinge on tubulin isotypes and microtubule-based processes in different cell types.

Na+-K+-ATPase gene expression in the avian eggshell gland: distinct regulation in different cell types

2001 ◽  
Vol 281 (4) ◽  
pp. R1169-R1176 ◽  
Author(s):  
Irena Lavelin ◽  
Noam Meiri ◽  
Olga Genina ◽  
Rosaly Alexiev ◽  
Mark Pines
Keyword(s):  
Gene Expression ◽  
Mechanical Strain ◽  
Cell Types ◽  
Regulate Gene Expression ◽  
Eggshell Formation ◽  
Atpase Gene ◽  
Pseudostratified Epithelium ◽  
Cell Layers ◽  
Different Cell Types ◽  
Rna Fingerprinting

The avian eggshell gland (ESG) is a tissue specialized in transporting the Ca2+ required for eggshell formation and represents a unique biological system in which the calcification process takes place in a circadian fashion. With the use of RNA fingerprinting, a set of genes differentially induced at the time of calcification was detected, one of which was identified as the α1-subunit of Na+-K+-ATPase. The gene was expressed in a circadian manner in both cell types populating the ESG, but in different temporal patterns, suggesting distinct mechanisms of regulation. Ca2+ flux and mechanical strain were found to regulate gene expression in the inner glandular epithelium and the pseudostratified epithelium facing the lumen, respectively. Mechanical strain also affected gene expression in cell layers facing the lumen in other parts of the oviduct. Only the α1-isoform, not the α2- or α3-isoform, of Na+-K+-ATPase was expressed in the ESG. In summary, we demonstrate that the α1-subunit Na+-K+-ATPase gene is expressed in different epithelial cell types in the ESG and is regulated by various mechanisms, which may reflect the disparity in the physiological roles of the cells in the process of eggshell formation.

scholarly journals Lentoidogenesis from neural retina cells in culture is affected by interactive relationships between different cell types

Development ◽  
1983 ◽  
Vol 73 (1) ◽  
pp. 97-109
Author(s):  
Shin Takagi ◽  
Hisato Kondoh ◽  
Kazuya Nomura ◽  
T. S. Okada
Keyword(s):  
Cell Types ◽  
Neural Retina ◽  
Cell Populations ◽  
Neural Cells ◽  
Percoll Gradient ◽  
Cell Fractions ◽  
Different Cell Types ◽  
Fraction Addition ◽  
Choline Acetyltransferase Activity

By centrifugation in a Percoll gradient, two cell fractions were separated from cell populations harvested from 8-day cultures of neural retina cells of 3·5-day-old quail embryos. The heavy (H-) fraction contained mostly N-cells, which are considered to be putative neuronal cells, while the light (L-) fraction contained both E-cells, putative retinal glial cells, and Ncells. Determination of choline acetyltransferase activity in both fractions suggested that this enzyme is predominantly localised in N-cells. After replating the separated L-fraction for further culturing, frequent lentoidogenesis occurred from clusters of N-cells which, though few in number, were included in this fraction. Addition of H-fraction to L-fraction cells caused a significant increase in lentoidogenesis up to a ratio of N- to E-cells of 3:1. However, addition of excess H-fraction cells beyond this ratio inhibited lens differentiation. This difference in the expression of lens phenotypes resulting from the different ratios of H- and L-fraction was confirmed by monitoring the level of δ-crystallin in cultures. These results are discussed in the light of interactive relationships between N- and E-cells in the transdifferentiation of neural cells into lens in cell culture

scholarly journals A minibead method for detection of membrane lectins.

1989 ◽  
Vol 37 (1) ◽  
pp. 91-96 ◽  
Author(s):  
T Matsuoka ◽  
M Tavassoli
Keyword(s):  
Soluble Sugar ◽  
Cell Types ◽  
Cell Populations ◽  
Morphological Identification ◽  
Cell Systems ◽  
Biological Phenomena ◽  
Homogeneous Cell ◽  
Different Cell Types ◽  
Derivatives Of ◽  
Scanning Electron

Membrane lectins are being increasingly implicated in many biological phenomena. Previous methods for detection of these substances are applicable only to homogeneous cell populations. We have now developed a method that permits morphological identification of lectin-bearing cells in heterogeneous cell populations. Amide-modified latex minibeads (0.345 or 0.532 micron) were activated with glutaraldehyde and then covalently bound to p-aminophenyl derivatives of various sugars. When the probe thus constructed was incubated with cell systems known to bear well-defined membrane lectins (galactosyl receptors in hepatocytes, mannosyl receptors in macrophages), binding occurred and could be visualized by scanning electron microscopy. Binding was inhibited in the presence of excess soluble sugar, indicating the specificity of reaction. Incubation of a mixture of two different-sized probes with two different cell types led to segregation of the probes. This method also permits semiquantification of binding.

scholarly journals A comparative study of the coats of chimaeric mice and those of heterozygotes for X-linked genes

1972 ◽  
Vol 19 (3) ◽  
pp. 213-228 ◽  
Author(s):  
B. M. Cattanach ◽  
H. G. Wolfe ◽  
M. F. Lyon
Keyword(s):  
Comparative Study ◽  
Hair Follicle ◽  
Cell Types ◽  
Structural Effect ◽  
Follicle Cells ◽  
Cell Populations ◽  
Autosome Translocation ◽  
The One ◽  
Different Cell Types ◽  
Colour Effect

SUMMARYThe coats of Ta–Ta+ and c–c+ chimaeric mice have been compared with those of Ta heterozygotes and animals heterozygous for an X-autosome translocation which causes c-variegation. With one exception all those features typical of the heterozygotes were found in their chimaeric counterparts, thus showing that the creation of two cell populations by X-inactivation can ultimately lead to the observed heterozygous phenotypes. The one exceptional feature not found in c-variegated chimaeric mice was the progessive increase in the proportion of pigmented hairs in c areas with age which occurs in X-autosome translocation heterozygotes.The coat of a Modp / + – Ta chimaeric animal was also investigated. Ta hairs showing only the colour effect of Modp were numerous, suggesting that Modp and Ta affect different cell populations. However, Ta hairs showing the structural effect of Modp were very rare. The two observations suggest Modp can operate independently upon two different cell types – melanocytes and hair follicle cells.

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