scholarly journals Essential role of caldesmon in the actin filament reorganization induced by glucocorticoids.

1995 ◽  
Vol 131 (5) ◽  
pp. 1223-1230 ◽  
Author(s):  
F Castellino ◽  
S Ono ◽  
F Matsumura ◽  
A Luini
Keyword(s):  
Actin Cytoskeleton ◽  
A549 Cells ◽  
Cell Types ◽  
Antisense Oligodeoxynucleotide ◽  
Similar Time ◽  
Calmodulin Binding ◽  
Time Courses ◽  
Induced Changes

Glucocorticoids induce the remodeling of the actin cytoskeleton and the formation of numerous stress fibers in a protein synthesis-dependent fashion in a variety of cell types (Castellino, F., J. Heuser, S. Marchetti, B. Bruno, and A. Luini. 1992. Proc. Natl. Acad. Sci. USA. 89:3775-3779). These cells can thus be used as models to investigate the mechanisms controlling the organization of actin filaments. Caldesmon is an almost ubiquitous actin- and calmodulin-binding protein that synergizes with tropomyosin to stabilize microfilaments in vitro (Matsumura, F., and Yamashiro, S. 1993. Current Opin. Cell Biol. 5:70-76). We now report that glucocorticoids (but not other steroids) enhanced the levels of caldesmon (both protein and mRNA) and induced the reorganization of microfilaments with similar time courses and potencies in A549 cells. A caldesmon antisense oligodeoxynucleotide targeted to the most abundant caldesmon isoform in A549 cells dramatically inhibited glucocorticoid-induced caldesmon synthesis and actin reorganization with similar potencies. Several control oligonucleotides were inactive. These results demonstrate that caldesmon has a crucial role in vivo in the organization of the actin cytoskeleton and suggest that hormone-induced changes in caldesmon levels mediate microfilament remodeling.

scholarly journals ARHGAP25, a novel Rac GTPase-activating protein, regulates phagocytosis in human neutrophilic granulocytes

Blood ◽  
2012 ◽  
Vol 119 (2) ◽  
pp. 573-582 ◽  
Author(s):  
Roland Csépányi-Kömi ◽  
Gábor Sirokmány ◽  
Miklós Geiszt ◽  
Erzsébet Ligeti
Keyword(s):  
Actin Cytoskeleton ◽  
Rho Gtpases ◽  
Active Form ◽  
Cell Types ◽  
Small Gtpases ◽  
Negative Regulator ◽  
Phagocytic Cells ◽  
Rac Gtpase

Members of the Rac/Rho family of small GTPases play an essential role in phagocytic cells in organization of the actin cytoskeleton and production of toxic oxygen compounds. GTPase-activating proteins (GAPs) decrease the amount of the GTP-bound active form of small GTPases, and contribute to the control of biologic signals. The number of potential Rac/RhoGAPs largely exceeds the number of Rac/Rho GTPases and the expression profile, and their specific role in different cell types is largely unknown. In this study, we report for the first time the properties of full-length ARHGAP25 protein, and show that it is specifically expressed in hematopoietic cells, and acts as a RacGAP both in vitro and in vivo. By silencing and overexpressing the protein in neutrophil model cell lines (PLB-985 and CosPhoxFcγR, respectively) and in primary macrophages, we demonstrate that ARHGAP25 is a negative regulator of phagocytosis acting probably via modulation of the actin cytoskeleton.

scholarly journals In Situ Silver-based Electrochemical Bioreactor In Vivo

2020 ◽  
Author(s):  
Yong Huang ◽  
Liping Zhong ◽  
Zhiming Deng ◽  
Pan Wu ◽  
Jian He ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Graphene Oxide ◽  
Tumor Cells ◽  
Silver Nanoparticle ◽  
A549 Cells ◽  
Induced Apoptosis ◽  
Induced Changes

Abstract In this study we show for the first time that a reduced graphene oxide (rGO) carrier has a 15-fold higher catalysis rate than graphene oxide (GO) in Ag+ reduction. Based on this, we constructed a tumor microenvironment-enabled in situ silver-based electrochemical oncolytic bioreactor (SEOB) which unlocked an Ag+ prodrug to generate silver nanoparticles and inhibited the growth of various tumors. In this bioreactor system, intratumoral H2O2 acted as the reductant and the rGO carrier acted as the catalyst. Chelation of aptamers to this prodrug increased the production of silver nanoparticles by tumor cells, especially in the presence of Vitamin C, which broke down in tumor cells to supply massive amounts of H2O2. Consequently, highly efficient silver nanoparticle-induced apoptosis was observed in HepG2 and A549 cells in vitro and in HepG2- and A549-derived tumors in vivo. The apoptosis was associated with ROS-induced changes in mitochondrial membrane potential and DNA damage. The specific aptamer targeting and intratumoral silver nanoparticle production guaranteed excellent biosafety, with no damage to normal cells, because the Ag+ prodrug was specifically unlocked in tumors. More significantly, there was no evident tissue damage in monkeys, which greatly increases the clinical translation potential of the SEOB system.

In vitro evaluation of cobalt oxide nanoparticle-induced toxicity

2017 ◽  
Vol 33 (8) ◽  
pp. 646-654 ◽  
Author(s):  
Mahmoud Abudayyak ◽  
Tuba Altincekic Gurkaynak ◽  
Gül Özhan
Keyword(s):  
Nervous System ◽  
Cobalt Oxide ◽  
Cell Lines ◽  
Neuroblastoma Cells ◽  
A549 Cells ◽  
Cell Types ◽  
Carcinoma Cells ◽  
High Exposure

Cobalt oxide (Co3O4) nanoparticles have applications in nanomedicine and nanotechnology; therefore, any possible adverse effects require thorough investigation. The present study investigated the effects of Co3O4 nanoparticles on four different cell lines: liver, HepG2 hepatocellular carcinoma cells; lung, A549 lung carcinoma cells; gastrointestinal, Caco-2 colorectal adenocarcinoma cells; and nervous system, SH-SY5Y neuroblastoma cells. A difference was observed in cell sensitivity toward Co3O4 nanoparticles. Co3O4 nanoparticles were taken up by all the cell types. However, no cell death was observed in HepG2, Caco-2, or SH-SY5Y cells; only A549 cells showed cytotoxicity at relatively high exposure concentrations. Co3O4 nanoparticles did not induce DNA damage or apoptosis in the cell lines tested except in A549. Interestingly, Co3O4 nanoparticles induced cellular oxidative damage in all cell types except Caco-2, resulting in increased malondialdehyde and 8-hydroxydeoxyguanosine levels and decreased glutathione levels. According to our results, it could be indicated that high concentrations of Co3O4 nanoparticles affected the pulmonary system but were unlikely to affect the liver, nervous system, or gastrointestinal system. Co3O4 nanoparticles might be safely used for industrial, commercial, and nanomedical applications if dose rates are adjusted depending on the route of exposure. However, further in vivo and in vitro studies are required to confirm the safety of Co3O4 nanoparticles.

scholarly journals Dismantling Cell–Cell Contacts during Apoptosis Is Coupled to a Caspase-dependent Proteolytic Cleavage of β-Catenin

1997 ◽  
Vol 139 (3) ◽  
pp. 759-771 ◽  
Author(s):  
Claudio Brancolini ◽  
Dean Lazarevic ◽  
Joe Rodriguez ◽  
Claudio Schneider
Keyword(s):  
Cell Death ◽  
Cell Adhesion ◽  
Actin Cytoskeleton ◽  
Caspase 3 ◽  
Cell Types ◽  
Cell Contacts ◽  
Carboxy Terminal ◽  
Cell Cell

Cell death by apoptosis is a tightly regulated process that requires coordinated modification in cellular architecture. The caspase protease family has been shown to play a key role in apoptosis. Here we report that specific and ordered changes in the actin cytoskeleton take place during apoptosis. In this context, we have dissected one of the first hallmarks in cell death, represented by the severing of contacts among neighboring cells. More specifically, we provide demonstration for the mechanism that could contribute to the disassembly of cytoskeletal organization at cell–cell adhesion. In fact, β-catenin, a known regulator of cell–cell adhesion, is proteolytically processed in different cell types after induction of apoptosis. Caspase-3 (cpp32/apopain/yama) cleaves in vitro translated β-catenin into a form which is similar in size to that observed in cells undergoing apoptosis. β-Catenin cleavage, during apoptosis in vivo and after caspase-3 treatment in vitro, removes the amino- and carboxy-terminal regions of the protein. The resulting β-catenin product is unable to bind α-catenin that is responsible for actin filament binding and organization. This evidence indicates that connection with actin filaments organized at cell–cell contacts could be dismantled during apoptosis. Our observations suggest that caspases orchestrate the specific and sequential changes in the actin cytoskeleton occurring during cell death via cleavage of different regulators of the microfilament system.

scholarly journals Disruption of the actin cytoskeleton after microinjection of proteolytic fragments of alpha-actinin.

1991 ◽  
Vol 114 (3) ◽  
pp. 481-491 ◽  
Author(s):  
F M Pavalko ◽  
K Burridge
Keyword(s):  
Actin Cytoskeleton ◽  
Binding Site ◽  
Focal Adhesions ◽  
Cell Types ◽  
Cytoplasmic Domain ◽  
Stress Fibers ◽  
Actin Binding ◽  
Cell Periphery

Alpha-actinin can be proteolytically cleaved into major fragments of 27 and 53 kD using the enzyme thermolysin. The 27-kD fragment contains an actin-binding site and we have recently shown that the 53-kD fragment binds to the cytoplasmic domain of beta 1 integrin in vitro (Otey, C. A., F. M. Pavalko, and K. Burridge. 1990. J. Cell Biol. 111:721-729). We have explored the behavior of the isolated 27- and 53-kD fragments of alpha-actinin after their microinjection into living cells. Consistent with its containing a binding site for actin, the 27-kD fragment was detected along stress fibers within 10-20 min after injection into rat embryo fibroblasts (REF-52). The 53-kD fragment of alpha-actinin, however, concentrated in focal adhesions of REF-52 cells 10-20 min after injection. The association of this fragment with focal adhesions in vivo is consistent with its interaction in vitro with the cytoplasmic domain of the beta 1 subunit of integrin, which was also localized at these sites. When cells were injected with greater than 5 microM final concentration of either alpha-actinin fragment and cultured for 30-60 min, most stress fibers were disassembled. At this time, however, many of the focal adhesions, particularly those around the cell periphery, remained after most stress fibers had gone. By 2 h after injection only a few small focal adhesions persisted, yet the cells remained spread. Identical results were obtained with other cell types including primary chick fibroblasts, BSC-1, MDCK, and gerbil fibroma cells. Stress fibers and focal adhesions reformed if cells were allowed to recover for 18 h after injection. These data suggest that introduction of the monomeric 27-kD fragment of alpha-actinin into cells may disrupt the actin cytoskeleton by interfering with the function of endogenous, intact alpha-actinin molecules along stress fibers. The 53-kD fragment may interfere with endogenous alpha-actinin function at focal adhesions or by displacing some other component that binds to the rod domain of alpha-actinin and that is needed to maintain stress fiber organization.

scholarly journals The Cytoplasmic Actins in the Regulation of Endothelial Cell Function

2021 ◽  
Vol 22 (15) ◽  
pp. 7836
Author(s):  
Vera B. Dugina ◽  
Galina S. Shagieva ◽  
Anton S. Shakhov ◽  
Irina B. Alieva
Keyword(s):  
Endothelial Cells ◽  
Actin Cytoskeleton ◽  
Spatial Organization ◽  
Cell Function ◽  
Cell Types ◽  
Structural Basis ◽  
Endothelial Cell Function ◽  
Vascular Walls

The primary function of the endothelial cells (EC) lining the inner surface of all vessels is to regulate permeability of vascular walls and to control exchange between circulating blood and tissue fluids of organs. The EC actin cytoskeleton plays a crucial role in maintaining endothelial barrier function. Actin cytoskeleton reorganization result in EC contraction and provides a structural basis for the increase in vascular permeability, which is typical for many diseases. Actin cytoskeleton in non-muscle cells presented two actin isoforms: non-muscle β-cytoplasmic and γ-cytoplasmic actins (β-actins and γ-actins), which are encoded by ACTB and ACTG1 genes, respectively. They are ubiquitously expressed in the different cells in vivo and in vitro and the β/γ-actin ratio depends on the cell type. Both cytoplasmic actins are essential for cell survival, but they perform various functions in the interphase and cell division and play different roles in neoplastic transformation. In this review, we briefly summarize the research results of recent years and consider the features of the cytoplasmic actins: The spatial organization in close connection with their functional activity in different cell types by focusing on endothelial cells.

Ultrastructural observations on the in vitro cytoadherence of Plasmodium falciparum infected red blood cells

1990 ◽  
Vol 48 (3) ◽  
pp. 914-915
Author(s):  
D.J.P. Ferguson ◽  
A.R. Berendt ◽  
J. Tansey ◽  
K. Marsh ◽  
C.I. Newbold
Keyword(s):  
Plasmodium Falciparum ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Umbilical Vein ◽  
Cell Types ◽  
Amelanotic Melanoma ◽  
Cytoplasmic Process ◽  
Umbilical Vein Endothelial Cells

In human malaria, the most serious clinical manifestation is cerebral malaria (CM) due to infection with Plasmodium falciparum. The pathology of CM is thought to relate to the fact that red blood cells containing mature forms of the parasite (PRBC) cytoadhere or sequester to post capillary venules of various tissues including the brain. This in vivo phenomenon has been studied in vitro by examining the cytoadherence of PRBCs to various cell types and purified proteins. To date, three Ijiost receptor molecules have been identified; CD36, ICAM-1 and thrombospondin. The specific changes in the PRBC membrane which mediate cytoadherence are less well understood, but they include the sub-membranous deposition of electron-dense material resulting in surface deformations called knobs. Knobs were thought to be essential for cytoadherence, lput recent work has shown that certain knob-negative (K-) lines can cytoadhere. In the present study, we have used electron microscopy to re-examine the interactions between K+ PRBCs and both C32 amelanotic melanoma cells and human umbilical vein endothelial cells (HUVEC).We confirm previous data demonstrating that C32 cells possess numerous microvilli which adhere to the PRBC, mainly via the knobs (Fig. 1). In contrast, the HUVEC were relatively smooth and the PRBCs appeared partially flattened onto the cell surface (Fig. 2). Furthermore, many of the PRBCs exhibited an invagination of the limiting membrane in the attachment zone, often containing a cytoplasmic process from the endothelial cell (Fig. 2).

Epithelial Organotypic Cultures: A Viable Model to Address Mechanisms of Carcinogenesis by Epitheliotropic Viruses

2018 ◽  
Vol 18 (4) ◽  
pp. 246-255 ◽  
Author(s):  
Lara Termini ◽  
Enrique Boccardo
Keyword(s):  
Three Dimensional ◽  
Cell Types ◽  
Experimental Models ◽  
Biological Research ◽  
Specific Gene ◽  
Specific Cell ◽  
Organotypic Cultures ◽  
Skin Physiology

In vitro culture of primary or established cell lines is one of the leading techniques in many areas of basic biological research. The use of pure or highly enriched cultures of specific cell types obtained from different tissues and genetics backgrounds has greatly contributed to our current understanding of normal and pathological cellular processes. Cells in culture are easily propagated generating an almost endless source of material for experimentation. Besides, they can be manipulated to achieve gene silencing, gene overexpression and genome editing turning possible the dissection of specific gene functions and signaling pathways. However, monolayer and suspension cultures of cells do not reproduce the cell type diversity, cell-cell contacts, cell-matrix interactions and differentiation pathways typical of the three-dimensional environment of tissues and organs from where they were originated. Therefore, different experimental animal models have been developed and applied to address these and other complex issues in vivo. However, these systems are costly and time consuming. Most importantly the use of animals in scientific research poses moral and ethical concerns facing a steadily increasing opposition from different sectors of the society. Therefore, there is an urgent need for the development of alternative in vitro experimental models that accurately reproduce the events observed in vivo to reduce the use of animals. Organotypic cultures combine the flexibility of traditional culture systems with the possibility of culturing different cell types in a 3D environment that reproduces both the structure and the physiology of the parental organ. Here we present a summarized description of the use of epithelial organotypic for the study of skin physiology, human papillomavirus biology and associated tumorigenesis.

scholarly journals Heme Oxygenase-1 Deficiency and Oxidative Stress: A Review of 9 Independent Human Cases and Animal Models

2021 ◽  
Vol 22 (4) ◽  
pp. 1514 ◽  
Author(s):  
Akihiro Yachie
Keyword(s):  
Oxidative Stress ◽  
Animal Models ◽  
Heme Oxygenase ◽  
Inflammatory Diseases ◽  
Cell Types ◽  
Pharmacological Intervention ◽  
Heme Oxygenase 1 ◽  
Inflammatory Reactions

Since Yachie et al. reported the first description of human heme oxygenase (HO)-1 deficiency more than 20 years ago, few additional human cases have been reported in the literature. A detailed analysis of the first human case of HO-1 deficiency revealed that HO-1 is involved in the protection of multiple tissues and organs from oxidative stress and excessive inflammatory reactions, through the release of multiple molecules with anti-oxidative stress and anti-inflammatory functions. HO-1 production is induced in vivo within selected cell types, including renal tubular epithelium, hepatic Kupffer cells, vascular endothelium, and monocytes/macrophages, suggesting that HO-1 plays critical roles in these cells. In vivo and in vitro studies have indicated that impaired HO-1 production results in progressive monocyte dysfunction, unregulated macrophage activation and endothelial cell dysfunction, leading to catastrophic systemic inflammatory response syndrome. Data from reported human cases of HO-1 deficiency and numerous studies using animal models suggest that HO-1 plays critical roles in various clinical settings involving excessive oxidative stress and inflammation. In this regard, therapy to induce HO-1 production by pharmacological intervention represents a promising novel strategy to control inflammatory diseases.

scholarly journals MyD88 Is Not Required for Muscle Injury-Induced Endochondral Heterotopic Ossification in a Mouse Model of Fibrodysplasia Ossificans Progressiva

Biomedicines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 630
Author(s):  
Huili Lyu ◽  
Cody M. Elkins ◽  
Jessica L. Pierce ◽  
C. Henrique Serezani ◽  
Daniel S. Perrien
Keyword(s):  
Heterotopic Ossification ◽  
Muscle Injury ◽  
Cell Types ◽  
Fibrodysplasia Ossificans Progressiva ◽  
Inflammatory Signaling ◽  
Conditional Deletion ◽  
Pathway Crosstalk ◽  
Multiple Cell

Excess inflammation and canonical BMP receptor (BMPR) signaling are coinciding hallmarks of the early stages of injury-induced endochondral heterotopic ossification (EHO), especially in the rare genetic disease fibrodysplasia ossificans progressiva (FOP). Multiple inflammatory signaling pathways can synergistically enhance BMP-induced Smad1/5/8 activity in multiple cell types, suggesting the importance of pathway crosstalk in EHO and FOP. Toll-like receptors (TLRs) and IL-1 receptors mediate many of the earliest injury-induced inflammatory signals largely via MyD88-dependent pathways. Thus, the hypothesis that MyD88-dependent signaling is required for EHO was tested in vitro and in vivo using global or Pdgfrα-conditional deletion of MyD88 in FOP mice. As expected, IL-1β or LPS synergistically increased Activin A (ActA)-induced phosphorylation of Smad 1/5 in fibroadipoprogenitors (FAPs) expressing Alk2R206H. However, conditional deletion of MyD88 in Pdgfrα-positive cells of FOP mice did not significantly alter the amount of muscle injury-induced EHO. Even more surprisingly, injury-induced EHO was not significantly affected by global deletion of MyD88. These studies demonstrate that MyD88-dependent signaling is dispensable for injury-induced EHO in FOP mice.

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