Activation of a PP2A-like phosphatase and dephosphorylation of tau protein characterize onset of the execution phase of apoptosis

1998 ◽  
Vol 111 (5) ◽  
pp. 625-636 ◽  
Author(s):  
J.C. Mills ◽  
V.M. Lee ◽  
R.N. Pittman
Keyword(s):  
Okadaic Acid ◽  
Time Course ◽  
Chromatin Condensation ◽  
Cell Types ◽  
Biochemical Changes ◽  
Reporter Protein ◽  
Execution Phase ◽  
A Cell ◽  
Characteristic Features ◽  
Different Cell Types

The execution phase is an evolutionarily conserved stage of apoptosis that occurs with remarkable temporal and morphological uniformity in most if not all cell types regardless of the condition used to induce death. Characteristic features of apoptosis such as membrane blebbing, DNA fragmentation, chromatin condensation, and cell shrinkage occur during the execution phase; therefore, there is considerable interest in defining biochemical changes and signaling events early in the execution phase. Since onset of the execution phase is asynchronous across a population with only a small fraction of cells in this stage at any given time, characterizing underlying biochemical changes is difficult. An additional complication is recent evidence suggesting that the execution phase occurs after cells commit to die; thus, agents that modulate events in the execution phase may alter the morphological progression of apoptosis but will not affect the time-course of death. In the present study, we use a single cell approach to study and temporally order biochemical and cytoskeletal events that occur specifically in the execution phase. Microtubules de-acetylate and disassemble as terminally differentiated PC12 cells enter the execution phase following removal of nerve growth factor. Using phosphorylation sensitive antibodies to tau, we show that this microtubule-stabilizing protein becomes dephosphorylated near the onset of the execution phase. Low concentrations of okadaic acid inhibit dephosphorylation suggesting a PP2A-like phosphatase is responsible. Transfecting (tau) into CHO cells to act as a ‘reporter’ protein shows a similar dephosphorylation of (tau) by a PP2A-like phosphatase during the execution phase following induction of apoptosis with UV irradiation. Therefore, activation of PP2A phosphatase occurs at the onset of the execution phase in two very different cell types following different initiators of apoptosis which is consistent with activation of PP2A phosphatase being a common feature of the execution phase of apoptosis. Experiments using either taxol to inhibit microtubule disassembly or okadaic acid to inhibit tau dephosphorylation suggest that microtubule disassembly is necessary for tau dephosphorylation to occur. Thus, we propose that an early step in the execution phase (soon after a cell commits to die) is microtubule disassembly which frees or activates PP2A to dephosphorylate tau as well as other substrates.

In Vitro Analysis of Early Genotoxic and Cytotoxic Effects of Okadaic Acid in Different Cell Types of the MusselMytilus galloprovincialis

2015 ◽  
Vol 78 (13-14) ◽  
pp. 814-824 ◽  
Author(s):  
María Verónica Prego-Faraldo ◽  
Vanessa Valdiglesias ◽  
Blanca Laffon ◽  
José M. Eirín-López ◽  
Josefina Méndez
Keyword(s):  
Okadaic Acid ◽  
Cell Types ◽  
Cytotoxic Effects ◽  
Vitro Analysis ◽  
Different Cell Types ◽  
In Vitro Analysis

scholarly journals The complement of desmosomal plaque proteins in different cell types.

1985 ◽  
Vol 101 (4) ◽  
pp. 1442-1454 ◽  
Author(s):  
P Cowin ◽  
H P Kapprell ◽  
W W Franke
Keyword(s):  
Guinea Pig ◽  
Cell Types ◽  
Cardiac Cells ◽  
Myocardial Tissue ◽  
Cell Type ◽  
Wide Range ◽  
Specific Manner ◽  
A Cell ◽  
Cell Type Specific ◽  
Different Cell Types

Desmosomal plaque proteins have been identified in immunoblotting and immunolocalization experiments on a wide range of cell types from several species, using a panel of monoclonal murine antibodies to desmoplakins I and II and a guinea pig antiserum to desmosomal band 5 protein. Specifically, we have taken advantage of the fact that certain antibodies react with both desmoplakins I and II, whereas others react only with desmoplakin I, indicating that desmoplakin I contains unique regions not present on the closely related desmoplakin II. While some of these antibodies recognize epitopes conserved between chick and man, others display a narrow species specificity. The results show that proteins whose size, charge, and biochemical behavior are very similar to those of desmoplakin I and band 5 protein of cow snout epidermis are present in all desmosomes examined. These include examples of simple and pseudostratified epithelia and myocardial tissue, in addition to those of stratified epithelia. In contrast, in immunoblotting experiments, we have detected desmoplakin II only among cells of stratified and pseudostratified epithelial tissues. This suggests that the desmosomal plaque structure varies in its complement of polypeptides in a cell-type specific manner. We conclude that the obligatory desmosomal plaque proteins, desmoplakin I and band 5 protein, are expressed in a coordinate fashion but independently from other differentiation programs of expression such as those specific for either epithelial or cardiac cells.

TEMPLATE-BASED ISOCONTOURING

2006 ◽  
Vol 06 (02) ◽  
pp. 187-204 ◽  
Author(s):  
JAGANNATHAN LAKSHMIPATHY ◽  
WIESLAW L. NOWINSKI ◽  
ERIC A. WERNERT
Keyword(s):  
Linear Time ◽  
Cell Types ◽  
Extraction Process ◽  
Extraction Methods ◽  
Lookup Table ◽  
Graphics Hardware ◽  
A Cell ◽  
Triangle Strips ◽  
Different Cell Types

Different isocontour extraction methods use different cell types (tetrahedral, hexahedral, etc.) depending on the nature of the acquisition grids (structured, unstructured, etc.). The existing isocontouring methods have the following pre-steps for the actual extraction process: (a) identification of cell types, (b) identification of topologically independent instances for each cell type, (c) determination of surface primitives contained in the topologically independent instances and (d) generation of a lookup table such that the name of the entry is an instance of a cell and the entry is the triangle set for that instance. The extraction process outputs the triangles from the lookup table. In this paper we present a novel generic method that enables us to list topologically independent surface primitives called "templates" within any n-polytope cell namely tetrahedra, hexahedra etc. We have also modified the traditional lookup table such that name is the cell instance and the entry is face index representations of all template instances contained in that cell. To show an example, we have applied this approach on a hexahedron and listed the templates and subsequently we have showed how to construct a lookup table. Most modern graphics hardware render triangles faster if they are rendered collectively as triangle strips as opposed to individual triangles. With our modified lookup table approach we can identify triangles in the neighboring cell in a linear time and hence we are able to connect two triangle strips into a longer triangle strip on the fly during the extraction process. We have compared our approach with some existing methods. The following are some of the important features of the method: (1) Simplicity, (2) procedural triangulation and (3) face-index representation.

scholarly journals Complex regulation and functional versatility of mammalian alpha- and beta-tubulin isotypes during the differentiation of testis and muscle cells.

1988 ◽  
Vol 106 (6) ◽  
pp. 2023-2033 ◽  
Author(s):  
S A Lewis ◽  
N J Cowan
Keyword(s):  
Cell Types ◽  
Beta Tubulin ◽  
Specific Expression ◽  
Alpha Tubulin ◽  
Tubulin Isotypes ◽  
Tubulin Isotype ◽  
A Cell ◽  
Complex Regulation ◽  
Carboxy Terminal ◽  
Different Cell Types

In the accompanying paper (Gu, W., S. A. Lewis, and N. J. Cowan. 1988. J. Cell Biol. 106: 2011-2022), we report the generation of three antisera, each of which uniquely recognizes a different mammalian alpha-tubulin isotype, plus a fourth antibody that distinguishes between microtubules containing the tyrosinated and nontyrosinated form of the only known mammalian alpha-tubulin gene product that lacks an encoded carboxy-terminal tyrosine residue. These sera, together with five sera we raised that distinguish among the known mammalian beta-tubulin isotypes, have been used to study patterns of tubulin isotype-specific expression in muscle and testis, two tissues in which characteristic developmental changes are accompanied by dramatic rearrangements in microtubule structures. As in the case of cells in culture, there is no evidence to suggest that there is subcellular sorting of different tubulin isotypes among different kinds of microtubule, even in a cell type (the developing spermatid) that simultaneously contains such functionally distinct structures as the manchette and the flagellum. On the other hand, the patterns of expression of the various tubulin isotypes show marked and distinctive differences in different cell types and, in at least one case, evidence is presented for regulation at the translational or posttranslational level. The significance of these observations is discussed in terms of the existence of the mammalian alpha- and beta-tubulin multigene families.

scholarly journals Transient nuclear lamin A/C accretion aids in recovery from vapor nanobubble-induced permeabilisation of the plasma membrane

2022 ◽  
Vol 79 (1) ◽  
Author(s):  
Gaëlle Houthaeve ◽  
Gerardo García-Díaz Barriga ◽  
Stephan Stremersch ◽  
Herlinde De Keersmaecker ◽  
Juan Fraire ◽  
...  
Keyword(s):  
Chromatin Condensation ◽  
Physical Method ◽  
Cell Types ◽  
Molecular Features ◽  
Nuclear Lamin ◽  
Selective Depletion ◽  
Pharmacological Stimulation ◽  
Sequencing Experiment ◽  
Transcriptional Rewiring ◽  
Different Cell Types

AbstractVapor nanobubble (VNB) photoporation is a physical method for intracellular delivery that has gained significant interest in the past decade. It has successfully been used to introduce molecular cargo of diverse nature into different cell types with high throughput and minimal cytotoxicity. For translational purposes, it is important to understand whether and how photoporation affects cell homeostasis. To obtain a comprehensive view on the transcriptional rewiring that takes place after VNB photoporation, we performed a longitudinal shotgun RNA-sequencing experiment. Six hours after photoporation, we found a marked upregulation of LMNA transcripts as well as their protein products, the A-type lamins. At the same time point, we observed a significant increase in several heterochromatin marks, suggesting a global stiffening of the nucleus. These molecular features vanished 24 h after photoporation. Since VNB-induced chromatin condensation was prolonged in LMNA knockout cells, A-type lamins may be required for restoring the nucleus to its original state. Selective depletion of A-type lamins reduced cell viability after VNB photoporation, while pharmacological stimulation of LMNA transcription increased the percentage of successfully transfected cells that survived after photoporation. Therefore, our results suggest that cells respond to VNB photoporation by temporary upregulation of A-type lamins to facilitate their recovery.

scholarly journals Intervertebral disc decellularisation: progress and challenges

2021 ◽  
Vol 42 ◽  
pp. 196-219
Author(s):  
MF Fiordalisi ◽  
◽  
AJ Silva ◽  
M Barbosa ◽  
RM Gonçalves ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Life Quality ◽  
Cell Types ◽  
Host Cells ◽  
Low Back ◽  
Therapeutic Success ◽  
A Cell ◽  
Antigen Removal ◽  
Ivd Degeneration ◽  
Different Cell Types

Intervertebral disc (IVD) degeneration and the consequent low-back pain (LBP) affect over 80 % of people in western societies, constituting a tremendous socio-economic burden worldwide and largely impairing patients’ life quality. Extracellular matrix (ECM)-based scaffolds, derived from decellularised tissues, are being increasingly explored in regenerative medicine for tissue repair. Decellularisation plays an essential role for host cells and antigen removal, while maintaining native microenvironmental signals, including ECM structure, composition and mechanical properties, which are essential for driving tissue regeneration. With the lack of clinical solutions for IVD repair/regeneration, implantation of decellularised IVD tissues has been explored to halt and/or revert the degenerative cascade and the associated LBP symptoms. Over the last few years, several researchers have focused on the optimisation of IVD decellularisation methods, combining physical, chemical and enzymatic treatments, in order to successfully develop a cell-free matrix. Recellularisation of IVD-based scaffolds with different cell types has been attempted and numerous methods have been explored to address proper IVD regeneration. Herein, the advances in IVD decellularisation methods, sterilisation procedures, repopulation and biocompatibility tests are reviewed. Additionally, the importance of the donor profile for therapeutic success is also addressed. Finally, the perspectives and major hurdles for clinical use of the decellularised ECM-based biomaterials for IVD are discussed. The studies reviewed support the notion that tissue-engineering-based strategies resorting to decellularised IVD may represent a major advancement in the treatment of disc degeneration and consequent LBP.

Biophotons, hallucinogens, and fluorescence

2011 ◽  
Vol 26 (S2) ◽  
pp. 1202-1202
Author(s):  
F. Grass
Keyword(s):  
Thermal Noise ◽  
Signal To Noise Ratio ◽  
Cell Communication ◽  
Cell Types ◽  
Ambient Light ◽  
A Cell ◽  
Inner Diameter ◽  
Different Cell Types ◽  
Light Guidance ◽  
Baby Hamster Kidney Cells

Several experiments show that there is a cell to cell communicaton by light in different cell types. The most convincing experiment shows that baby hamster kidney cells can communicate their spatial orientation through a glass film, this can only happen by photon signals. If so, it can be assumed that the cells with the highest differentiation, the neurons also use this mechanism. The nervous system would have excellent conditions for a cell to cell communication by light. Neurons are large, metabolically very active (lightproducing) cells with wide arborisation, contain little pigment and are protected from ambient light by bone and connective tissue. Signal to noise ratio should be high for photon signals. It has been shown that light can be propagated along the axis tracts. Also the hollow microtubules (neurofibrillae) could act as light guiding structures. According to Jibu et al. their inner diameter of 15 nm is ideal for light guidance free of thermal noise and loss. Other findings that may be of importance in this context, are the strong flurescence properties of the major hallucinogens: LSD, bufetonine, dimethyl-tryptamine, psilocybine, psilocin, iboguanin, harmine, cannabidinol and mescaline. Furthermore it has been shown that hallucinogenic properties of these substances have a direct correlation to their fluorescence properties and their readyness to donate electrons. As hypothesis we propose that the fluorescence interacts physically with the proposed Biophoton mediated cell to cell communication thus producing hallucinations. This would be an easy and plausible explanation for the strong hallucinogenic properties of these fluorescent substances.

scholarly journals Host and Tissue Specificity of Trichomonas vaginalis Is Not Mediated by Its Known Adhesion Proteins

2000 ◽  
Vol 68 (7) ◽  
pp. 4358-4360 ◽  
Author(s):  
Maria Filippa Addis ◽  
Paola Rappelli ◽  
Pier Luigi Fiori
Keyword(s):  
Trichomonas Vaginalis ◽  
Tissue Specificity ◽  
Mycoplasma Hominis ◽  
Cell Types ◽  
Adhesion Proteins ◽  
Vaginal Epithelial Cells ◽  
A Cell ◽  
Specific Receptors ◽  
The Subject ◽  
Different Cell Types

ABSTRACT Adhesion of Trichomonas vaginalis is believed to be dependent on four adhesion proteins, which are thought to bind to vaginal epithelial cells in a specific manner with a ligand-receptor type of interaction. However, the specific receptors on the host cell have not yet been identified. In this work, the ability of the T. vaginalis adhesins to bind to cells of different histologic derivations and from different species has been studied. HeLa, CHO, and Vero cell lines; erythrocytes from different species; and a prokaryote without a cell wall, Mycoplasma hominis, were employed in order to investigate the cell specificity of the T. vaginalis adhesins. We observed that the T. vaginalisadhesins are able to bind to the different cell types to the same extent, suggesting that the host and tissue specificity of T. vaginalis adhesion should not be due to specificity of the parasite adhesins. Our results suggest that the data published to date on the subject are probably artifactual and that the experiments reported in the literature are not appropriate for identification of protozoan adhesins.

scholarly journals Clonal culturing of human embryonic stem cells on laminin-521/E-cadherin matrix in defined and xeno-free environment

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Sergey Rodin ◽  
Liselotte Antonsson ◽  
Colin Niaudet ◽  
Oscar E. Simonson ◽  
Elina Salmela ◽  
...  
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Embryonic Stem ◽  
Cell Types ◽  
A Cell ◽  
Hes Cells ◽  
Free Environment ◽  
Different Cell Types ◽  
E Cadherin

Abstract Lack of robust methods for establishment and expansion of pluripotent human embryonic stem (hES) cells still hampers development of cell therapy. Laminins (LN) are a family of highly cell-type specific basement membrane proteins important for cell adhesion, differentiation, migration and phenotype stability. Here we produce and isolate a human recombinant LN-521 isoform and develop a cell culture matrix containing LN-521 and E-cadherin, which both localize to stem cell niches in vivo. This matrix allows clonal derivation, clonal survival and long-term self-renewal of hES cells under completely chemically defined and xeno-free conditions without ROCK inhibitors. Neither LN-521 nor E-cadherin alone enable clonal survival of hES cells. The LN-521/E-cadherin matrix allows hES cell line derivation from blastocyst inner cell mass and single blastomere cells without a need to destroy the embryo. This method can facilitate the generation of hES cell lines for development of different cell types for regenerative medicine purposes.

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