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Sample records for factor-induced cell cycle

  1. Bone morphogenetic protein-4 strongly potentiates growth factor-induced proliferation of mammary epithelial cells

    SciTech Connect

    Montesano, Roberto Sarkoezi, Rita; Schramek, Herbert

    2008-09-12

    Bone morphogenetic proteins (BMPs) are multifunctional cytokines that elicit pleiotropic effects on biological processes such as cell proliferation, cell differentiation and tissue morphogenesis. With respect to cell proliferation, BMPs can exert either mitogenic or anti-mitogenic activities, depending on the target cells and their context. Here, we report that in low-density cultures of immortalized mammary epithelial cells, BMP-4 did not stimulate cell proliferation by itself. However, when added in combination with suboptimal concentrations of fibroblast growth factor (FGF)-2, FGF-7, FGF-10, epidermal growth factor (EGF) or hepatocyte growth factor (HGF), BMP-4 potently enhanced growth factor-induced cell proliferation. These results reveal a hitherto unsuspected interplay between BMP-4 and growth factors in the regulation of mammary epithelial cell proliferation. We suggest that the ability of BMP-4 to potentiate the mitogenic activity of multiple growth factors may contribute to mammary gland ductal morphogenesis as well as to breast cancer progression.

  2. The microbial cell cycle

    SciTech Connect

    Nurse, P.; Streiblova, E.

    1984-01-01

    This book concentrates on the major problems of cell cycle control in microorganisms. A wide variety of microorganisms, ranging from bacteria and yeasts to hyphal fungi, algae, and ciliates are analyzed, with emphasis on the basic similarities among the organisms. Different ways of looking at cell cycle control which emphasize aspects of the problem such as circadian rhythms, limit cycle oscillators, and cell size models, are considered. New approaches such as the study of cell cycle mutants, and cloning of cell cycle control genes are also presented.

  3. Glial cell derived neurotrophic factor induces spermatogonial stem cell marker genes in chicken mesenchymal stem cells.

    PubMed

    Boozarpour, Sohrab; Matin, Maryam M; Momeni-Moghaddam, Madjid; Dehghani, Hesam; Mahdavi-Shahri, Naser; Sisakhtnezhad, Sajjad; Heirani-Tabasi, Asieh; Irfan-Maqsood, Muhammad; Bahrami, Ahmad Reza

    2016-06-01

    Mesenchymal stem cells (MSCs) are known with the potential of multi-lineage differentiation. Advances in differentiation technology have also resulted in the conversion of MSCs to other kinds of stem cells. MSCs are considered as a suitable source of cells for biotechnology purposes because they are abundant, easily accessible and well characterized cells. Nowadays small molecules are introduced as novel and efficient factors to differentiate stem cells. In this work, we examined the potential of glial cell derived neurotrophic factor (GDNF) for differentiating chicken MSCs toward spermatogonial stem cells. MSCs were isolated and characterized from chicken and cultured under treatment with all-trans retinoic acid (RA) or glial cell derived neurotrophic factor. Expression analysis of specific genes after 7days of RA treatment, as examined by RT-PCR, proved positive for some germ cell markers such as CVH, STRA8, PLZF and some genes involved in spermatogonial stem cell maintenance like BCL6b and c-KIT. On the other hand, GDNF could additionally induce expression of POU5F1, and NANOG as well as other genes which were induced after RA treatment. These data illustrated that GDNF is relatively more effective in diverting chicken MSCs towards Spermatogonial stem cell -like cells in chickens and suggests GDNF as a new agent to obtain transgenic poultry, nevertheless, exploitability of these cells should be verified by more experiments.

  4. Acetylation of RNA polymerase II regulates growth-factor-induced gene transcription in mammalian cells.

    PubMed

    Schröder, Sebastian; Herker, Eva; Itzen, Friederike; He, Daniel; Thomas, Sean; Gilchrist, Daniel A; Kaehlcke, Katrin; Cho, Sungyoo; Pollard, Katherine S; Capra, John A; Schnölzer, Martina; Cole, Philip A; Geyer, Matthias; Bruneau, Benoit G; Adelman, Karen; Ott, Melanie

    2013-11-07

    Lysine acetylation regulates transcription by targeting histones and nonhistone proteins. Here we report that the central regulator of transcription, RNA polymerase II, is subject to acetylation in mammalian cells. Acetylation occurs at eight lysines within the C-terminal domain (CTD) of the largest polymerase subunit and is mediated by p300/KAT3B. CTD acetylation is specifically enriched downstream of the transcription start sites of polymerase-occupied genes genome-wide, indicating a role in early stages of transcription initiation or elongation. Mutation of lysines or p300 inhibitor treatment causes the loss of epidermal growth-factor-induced expression of c-Fos and Egr2, immediate-early genes with promoter-proximally paused polymerases, but does not affect expression or polymerase occupancy at housekeeping genes. Our studies identify acetylation as a new modification of the mammalian RNA polymerase II required for the induction of growth factor response genes.

  5. [Progress of study on inhibitory effects of traditional Chinese herbs on growth factor induced proliferation of vascular smooth muscle cells].

    PubMed

    Yang, Guang; Zhang, Min-zhou; Jiang, Wei

    2005-10-01

    This paper sums up some studies in the last decade regarding the inhibitory effects of traditional Chinese herbs on growth factor induced proliferation of vascular smooth muscle cell (VSMC) via directly measuring the mRNA expression of its growth factors and the related receptors by electron microscope, immunohistochemistry, blot and hybridization in situ.

  6. Specific cell cycle synchronization with butyrate and cell cycle analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Synchronized cells have been invaluable for many kinds of cell cycle and cell proliferation studies. Butyrate induces cell cycle arrest and apoptosis in MDBK cells. To explore the possibility of using butyrate-blocked cells to obtain synchronized cells, we investigated the property of the cell cyc...

  7. Cell cycle effects of drugs

    SciTech Connect

    Dethlefsen, L.A.

    1986-01-01

    This book contains 11 chapters. Some of the chapter titles are: Cell Growth and Division Cycle; Cell Cycle Effects of Alkylating Agents; Biological Effects of Folic Acid Antagonists with Antineoplastic Activity; and Bleomycin-Mode of Action with Particular Reference to the Cell Cycle.

  8. How do prokaryotic cells cycle?

    PubMed

    Margolin, William; Bernander, Rolf

    2004-09-21

    This issue of Current Biology features five reviews covering various key aspects of the eukaryotic cell cycle. The topics include initiation of chromosome replication, assembly of the mitotic spindle, cytokinesis, the regulation of cell-cycle progression, and cell-cycle modeling, focusing mainly on budding yeast, fission yeast and animal cell model systems. The reviews underscore common themes as well as key differences in the way these processes are carried out and regulated among the different model organisms. Consequently, an important question is how cell-cycle mechanisms and controls have evolved, particularly in the broader perspective of the three domains of life.

  9. The Abbreviated Pluripotent Cell Cycle

    PubMed Central

    Kapinas, Kristina; Grandy, Rodrigo; Ghule, Prachi; Medina, Ricardo; Becker, Klaus; Pardee, Arthur; Zaidi, Sayyed K.; Lian, Jane; Stein, Janet; van Wijnen, Andre; Stein, Gary

    2013-01-01

    Human embryonic stem cells and induced pluripotent stem cells proliferate rapidly and divide symmetrically producing equivalent progeny cells. In contrast, lineage committed cells acquire an extended symmetrical cell cycle. Self-renewal of tissue-specific stem cells is sustained by asymmetric cell division where one progeny cell remains a progenitor while the partner progeny cell exits the cell cycle and differentiates. There are three principal contexts for considering the operation and regulation of the pluripotent cell cycle: temporal, regulatory andstructural. The primary temporal context that the pluripotent self-renewal cell cycle of human embryonic stem cells (hESCs) is a short G1 period without reducing periods of time allocated to S phase, G2, and mitosis. The rules that govern proliferation in hESCs remain to be comprehensively established. However, several lines of evidence suggest a key role for the naïve transcriptome of hESCs, which is competent to stringently regulate the ESC cell cycle. This supports the requirements of pluripotent cells to self propagate while suppressing expression of genes that confer lineage commitment and/or tissue specificity. However, for the first time, we consider unique dimensions to the architectural organization and assembly of regulatory machinery for gene expression in nuclear microenviornments that define parameters of pluripotency. From both fundamental biological and clinical perspectives, understanding control of the abbreviated embryonic stem cell cycle can provide options to coordinate control of proliferation versus differentiation. Wound healing, tissue engineering, and cell-based therapy to mitigate developmental aberrations illustrate applications that benefit from knowledge of the biology of the pluripotent cell cycle. PMID:22552993

  10. Sphingosine-1-phosphate mediates epidermal growth factor-induced muscle satellite cell activation

    SciTech Connect

    Nagata, Yosuke Ohashi, Kazuya; Wada, Eiji; Yuasa, Yuki; Shiozuka, Masataka; Nonomura, Yoshiaki; Matsuda, Ryoichi

    2014-08-01

    Skeletal muscle can regenerate repeatedly due to the presence of resident stem cells, called satellite cells. Because satellite cells are usually quiescent, they must be activated before participating in muscle regeneration in response to stimuli such as injury, overloading, and stretch. Although satellite cell activation is a crucial step in muscle regeneration, little is known of the molecular mechanisms controlling this process. Recent work showed that the bioactive lipid sphingosine-1-phosphate (S1P) plays crucial roles in the activation, proliferation, and differentiation of muscle satellite cells. We investigated the role of growth factors in S1P-mediated satellite cell activation. We found that epidermal growth factor (EGF) in combination with insulin induced proliferation of quiescent undifferentiated mouse myoblast C2C12 cells, which are also known as reserve cells, in serum-free conditions. Sphingosine kinase activity increased when reserve cells were stimulated with EGF. Treatment of reserve cells with the D-erythro-N,N-dimethylsphingosine, Sphingosine Kinase Inhibitor, or siRNA duplexes specific for sphingosine kinase 1, suppressed EGF-induced C2C12 activation. We also present the evidence showing the S1P receptor S1P2 is involved in EGF-induced reserve cell activation. Moreover, we demonstrated a combination of insulin and EGF promoted activation of satellite cells on single myofibers in a manner dependent on SPHK and S1P2. Taken together, our observations show that EGF-induced satellite cell activation is mediated by S1P and its receptor. - Highlights: • EGF in combination with insulin induces proliferation of quiescent C2C12 cells. • Sphingosine kinase activity increases when reserve cells are stimulated with EGF. • EGF-induced activation of reserve cells is dependent on sphingosine kinase and ERK. • The S1P receptor S1P2 is involved in EGF-induced reserve cell activation. • EGF-induced reserve cell activation is mediated by S1P and its

  11. Sphingosine-1-phosphate mediates epidermal growth factor-induced muscle satellite cell activation.

    PubMed

    Nagata, Yosuke; Ohashi, Kazuya; Wada, Eiji; Yuasa, Yuki; Shiozuka, Masataka; Nonomura, Yoshiaki; Matsuda, Ryoichi

    2014-08-01

    Skeletal muscle can regenerate repeatedly due to the presence of resident stem cells, called satellite cells. Because satellite cells are usually quiescent, they must be activated before participating in muscle regeneration in response to stimuli such as injury, overloading, and stretch. Although satellite cell activation is a crucial step in muscle regeneration, little is known of the molecular mechanisms controlling this process. Recent work showed that the bioactive lipid sphingosine-1-phosphate (S1P) plays crucial roles in the activation, proliferation, and differentiation of muscle satellite cells. We investigated the role of growth factors in S1P-mediated satellite cell activation. We found that epidermal growth factor (EGF) in combination with insulin induced proliferation of quiescent undifferentiated mouse myoblast C2C12 cells, which are also known as reserve cells, in serum-free conditions. Sphingosine kinase activity increased when reserve cells were stimulated with EGF. Treatment of reserve cells with the D-erythro-N,N-dimethylsphingosine, Sphingosine Kinase Inhibitor, or siRNA duplexes specific for sphingosine kinase 1, suppressed EGF-induced C2C12 activation. We also present the evidence showing the S1P receptor S1P2 is involved in EGF-induced reserve cell activation. Moreover, we demonstrated a combination of insulin and EGF promoted activation of satellite cells on single myofibers in a manner dependent on SPHK and S1P2. Taken together, our observations show that EGF-induced satellite cell activation is mediated by S1P and its receptor.

  12. The abbreviated pluripotent cell cycle.

    PubMed

    Kapinas, Kristina; Grandy, Rodrigo; Ghule, Prachi; Medina, Ricardo; Becker, Klaus; Pardee, Arthur; Zaidi, Sayyed K; Lian, Jane; Stein, Janet; van Wijnen, Andre; Stein, Gary

    2013-01-01

    Human embryonic stem cells (hESCs) and induced pluripotent stem cells proliferate rapidly and divide symmetrically producing equivalent progeny cells. In contrast, lineage committed cells acquire an extended symmetrical cell cycle. Self-renewal of tissue-specific stem cells is sustained by asymmetric cell division where one progeny cell remains a progenitor while the partner progeny cell exits the cell cycle and differentiates. There are three principal contexts for considering the operation and regulation of the pluripotent cell cycle: temporal, regulatory, and structural. The primary temporal context that the pluripotent self-renewal cell cycle of hESCs is a short G1 period without reducing periods of time allocated to S phase, G2, and mitosis. The rules that govern proliferation in hESCs remain to be comprehensively established. However, several lines of evidence suggest a key role for the naïve transcriptome of hESCs, which is competent to stringently regulate the embryonic stem cell (ESC) cell cycle. This supports the requirements of pluripotent cells to self-propagate while suppressing expression of genes that confer lineage commitment and/or tissue specificity. However, for the first time, we consider unique dimensions to the architectural organization and assembly of regulatory machinery for gene expression in nuclear microenviornments that define parameters of pluripotency. From both fundamental biological and clinical perspectives, understanding control of the abbreviated ESC cycle can provide options to coordinate control of proliferation versus differentiation. Wound healing, tissue engineering, and cell-based therapy to mitigate developmental aberrations illustrate applications that benefit from knowledge of the biology of the pluripotent cell cycle.

  13. Keratinocyte growth factor induces proliferation of hepatocytes and epithelial cells throughout the rat gastrointestinal tract.

    PubMed

    Housley, R M; Morris, C F; Boyle, W; Ring, B; Biltz, R; Tarpley, J E; Aukerman, S L; Devine, P L; Whitehead, R H; Pierce, G F

    1994-11-01

    Keratinocyte growth factor (KGF), a member of the fibroblast growth factor (FGF) family, was identified as a specific keratinocyte mitogen after isolation from a lung fibroblast line. Recently, recombinant (r)KGF was found to influence proliferation and differentiation patterns of multiple epithelial cell lineages within skin, lung, and the reproductive tract. In the present study, we designed experiments to identify additional target tissues, and focused on the rat gastrointestinal (GI) system, since a putative receptor, K-sam, was originally identified in a gastric carcinoma. Expression of KGF receptor and KGF mRNA was detected within the entire GI tract, suggesting the gut both synthesized and responded to KGF. Therefore, rKGF was administered to adult rats and was found to induce markedly increased proliferation of epithelial cells from the foregut to the colon, and of hepatocytes, one day after systemic treatment. Daily treatment resulted in the marked selective induction of mucin-producing cell lineages throughout the GI tract in a dose-dependent fashion. Other cell lineages were either unaffected (e.g., Paneth cells), or relatively decreased (e.g., parietal cells, enterocytes) in rKGF-treated rats. The direct effect of rKGF was confirmed by demonstrating markedly increased carcinoembryonic antigen production in a human colon carcinoma cell line, LIM1899. Serum levels of albumin were specifically and significantly elevated after daily treatment. These results demonstrate rKGF can induce epithelial cell activation throughout the GI tract and liver. Further, endogenous KGF may be a normal paracrine mediator of growth within the gut.

  14. Rat Stem-Cell Factor Induces Splenocytes Capable Of Regenerating The Thymus

    PubMed Central

    Migita, Russell T.; Trebasky, Lisa D.; Housman, Jerry M.; Elliott, Gary S.; Hendren, R. Wayne; Deprince, Randolph B.; Greiner, Dale L.

    1992-01-01

    Cytokine regulation of prethymic T-lymphoid progenitor-cell proliferation and/or differentiation has not been well-defined, although much is known of cytokine regulation of hemopoietic stem- and progenitor-cell development. Here we use a recently identified hemopoietic growth factor, stem-cell factor (SCF) (a form of the c-kit ligand), and a transplant model of thymocyte regeneration to assess the effect of SCF on the in vivo generation of prethymic, thymocyte progenitor-cell activity. We show that recombinant rat SCF (rrSCF164 administered to weanling rats selectively induces an increase in thymocyte progenitor activity in the spleens of treated rats as compared to rats treated with vehicle, polyethylene glycol (PEG)-conjugated rat albumin, or recombinant human granulocyte colony-stimulating factor (rhG-CSF). These data demonstrate that administration of SCF in vivo affects extrathymic-origin thymocyte regenerating cells and may influence, directly or indirectly, early prethymic stages of T-cell lymphopoiesis in addition to its known effect on early stages of myelopoiesis and erythropoiesis. PMID:1285280

  15. Platelet-Activating Factor Induces Epigenetic Modifications in Human Mast Cells.

    PubMed

    Damiani, Elisabetta; Puebla-Osorio, Nahum; Gorbea, Enrique; Ullrich, Stephen E

    2015-12-01

    UV radiation-induced systemic immune suppression is a major risk factor for skin cancer induction. The migration of dermal mast cells from the skin to the draining lymph nodes has a prominent role in activating systemic immune suppression. UV-induced keratinocyte-derived platelet-activating factor (PAF) activates mast cell migration, in part by upregulating the expression of CXCR4 on the surface of mast cells. Others have indicated that epigenetic mechanisms regulate CXCR4 expression; therefore, we asked whether PAF activates epigenetic mechanisms in mast cells. Human mast cells were treated with PAF, and the effect on DNA methylation and/or acetylation was measured. PAF suppressed the expression of DNA methyltransferase (DNMT) 1 and 3b. On the other hand, PAF increased p300 histone acetyltransferase expression, and the acetylation of histone H3, which coincided with a decreased expression of the histone deacetylase HDAC2. Chromatin immunoprecipitation assays indicated that PAF treatment activated the acetylation of the CXCR4 promoter. Finally, inhibiting histone acetylation blocked p300 upregulation and suppressed PAF-induced surface expression of CXCR4. Our findings suggest a novel molecular mechanism for PAF, activation of epigenetic modifications. We suggest that PAF may serve as an endogenous molecular mediator that links the environment (UV radiation) with the epigenome.

  16. Platelet-Activating Factor Induces Epigenetic Modifications in Human Mast Cells

    PubMed Central

    Gorbea, Enrique; Ullrich, Stephen E.

    2015-01-01

    Ultraviolet (UV) radiation-induced systemic immune suppression is a major risk factor for skin cancer induction. The migration of dermal mast cells from the skin to the draining lymph nodes plays a prominent role in activating systemic immune suppression. UV-induced keratinocyte-derived platelet-activating factor (PAF) activates mast cell migration, in part by up regulating the expression of CXCR4 on the surface of mast cells. Others have indicated that epigenetic mechanisms regulate CXCR4 expression, so we asked whether PAF activates epigenetic mechanisms in mast cells. Human mast cells were treated with PAF and the effect on DNA methylation and/or acetylation was measured. PAF suppressed the expression of DNA methyltransferase (DNMT) 1 and 3b. On the other hand, PAF increased p300 histone acetyltransferase expression, and the acetylation of histone H3, which coincided with a decreased expression of the histone deacetylase HDAC2. Chromatin immunoprecipitation assays indicated that PAF-treatment activated the acetylation of the CXCR4 promoter. Finally, inhibiting histone acetylation blocked p300 up-regulation and suppressed PAF-induced surface expression of CXCR4. Our findings suggest a novel molecular mechanism for PAF, activation of epigenetic modifications. We suggest that PAF may serve as an endogenous molecular mediator that links the environment (UV radiation) with the epigenome. PMID:26316070

  17. Growth factors induce monocyte binding to vascular smooth muscle cells: implications for monocyte retention in atherosclerosis.

    PubMed

    Cai, Qiangjun; Lanting, Linda; Natarajan, Rama

    2004-09-01

    Adhesive interactions between monocytes and vascular smooth muscle cells (VSMC) may contribute to subendothelial monocyte-macrophage retention in atherosclerosis. We investigated the effects of angiotensin II (ANG II) and platelet-derived growth factor (PDGF)-BB on VSMC-monocyte interactions. Treatment of human aortic VSMC (HVSMC) with ANG II or PDGF-BB significantly increased binding to human monocytic THP-1 cells and to peripheral blood monocytes. This was inhibited by antibodies to monocyte beta(1)- and beta(2)-integrins. The binding was also attenuated by blocking VSMC arachidonic acid (AA) metabolism by inhibitors of 12/15-lipoxygenase (12/15-LO) or cyclooxygenase-2 (COX-2). Conversely, binding was enhanced by overexpression of 12/15-LO or COX-2. Direct treatment of HVSMC with AA or its metabolites also increased binding. Furthermore, VSMC derived from 12/15-LO knockout mice displayed reduced binding to mouse monocytic cells relative to genetic control mice. Using specific signal transduction inhibitors, we demonstrated the involvement of Src, phosphoinositide 3-kinase, and MAPKs in ANG II- or PDGF-BB-induced binding. Interestingly, after coculture with HVSMC, THP-1 cell surface expression of the scavenger receptor CD36 was increased. These results show for the first time that growth factors may play additional roles in atherosclerosis by increasing monocyte binding to VSMC via AA metabolism and key signaling pathways. This can lead to monocyte subendothelial retention, CD36 expression, and foam cell formation.

  18. Generation and gene expression profiling of 48 transcription-factor-inducible mouse embryonic stem cell lines

    PubMed Central

    Yamamizu, Kohei; Sharov, Alexei A.; Piao, Yulan; Amano, Misa; Yu, Hong; Nishiyama, Akira; Dudekula, Dawood B.; Schlessinger, David; Ko, Minoru S. H.

    2016-01-01

    Mouse embryonic stem cells (ESCs) can differentiate into a wide range – and possibly all cell types in vitro, and thus provide an ideal platform to study systematically the action of transcription factors (TFs) in cell differentiation. Previously, we have generated and analyzed 137 TF-inducible mouse ESC lines. As an extension of this “NIA Mouse ESC Bank,” we generated and characterized 48 additional mouse ESC lines, in which single TFs in each line could be induced in a doxycycline-controllable manner. Together, with the previous ESC lines, the bank now comprises 185 TF-manipulable ESC lines (>10% of all mouse TFs). Global gene expression (transcriptome) profiling revealed that the induction of individual TFs in mouse ESCs for 48 hours shifts their transcriptomes toward specific differentiation fates (e.g., neural lineages by Myt1 Isl1, and St18; mesodermal lineages by Pitx1, Pitx2, Barhl2, and Lmx1a; white blood cells by Myb, Etv2, and Tbx6, and ovary by Pitx1, Pitx2, and Dmrtc2). These data also provide and lists of inferred target genes of each TF and possible functions of these TFs. The results demonstrate the utility of mouse ESC lines and their transcriptome data for understanding the mechanism of cell differentiation and the function of TFs. PMID:27150017

  19. PU/PTFE-stimulated monocyte-derived soluble factors induced inflammatory activation in endothelial cells.

    PubMed

    Xue, Yang; Liu, Xin; Sun, Jiao

    2010-03-01

    Polyurethane (PU) and polytetrafluoroethylene (PTFE) are two commonly used blood-contacting biomaterials. In the present study, we used a noncontact coculture model to evaluate the thrombosis-causing potential of monocyte-mediated PU and PTFE. We used human endothelial cells from umbilical cord (HUVECs) and human monocytes (THP1 cells). The THP1 cells were directly exposed to PU/PTFE, and the resultant cell-free supernatants were harvested for stimulating HUVECs. The treated HUVECs constituted the test group. HUVECs treated with supernatants of LPS-stimulated THP1 cells were used as the positive controls. To investigate the effects of the supernatant treatment on HUVECs, we measured the expression of the leukocyte-endothelial-cell adhesion molecules (CAMs) CD54 (ICAM-1), CD106 (VCAM-1), and CD62E (E-selectin) and evaluated the release of tissue factor (TF). The results demonstrated that both PU and PTFE induced the expressions of CD62E and TF. These activation effects were accompanied by activation of the NF-kappaB transcription factor. To further investigate the monocyte-derived soluble factors that might contribute to these effects, we evaluated the effects of the PU/PTFE stimulation on the expression of reactive oxygen species (ROS), TNF-alpha, IL-1beta, and IL-6 in monocyte monocultures. In comparison with the results for the negative control, both PU and PTFE significantly induced ROS release after 0.5h, while the expressions of TNF-alpha, IL-1beta, and IL-6 were variably increased after 24h. Our results suggest that the biomaterial induces monocytic activation and subsequently causes the release of soluble factors, which contribute to the inflammatory activation in HUVECs.

  20. Modulating Influence of Chemotactic Factor-Induced Cell Adhesiveness on Granulocyte Function

    PubMed Central

    Fehr, Jorg; Dahinden, Clemens

    1979-01-01

    The importance of adhesion in regulating locomotion and accumulation of polymorphonuclear leukocytes (PMN) has remained vague. We found that the chemotaxis of human PMN resuspended in heat-inactivated plasma was maximal toward 1-10 nM N-formyl-met-leu-phe (f-Met-Leu-Phe), but fell below random motility toward ≥ 100 nM. This impressive decrease of motility was paralleled by increased cell adherence on Petri dishes being minimal at 1 nM and maximal at >10 nM f-Met-Leu-Phe (6±1 and 37±2% [SE] adherent cells, respectively). Checked by phase-contrast microscopy, cells under stimulated adhesion lost the typical bipolar shape of moving PMN and became immobilized and highly flattened. PMN, preexposed to 250 nM f-Met-Leu-Phe and tested after washing, retained increased adhesiveness and showed extremely low random and chemotactic motility. In contrast, preexposure to 1 nM f-Met-Leu-Phe had no effect on chemotaxis. Supporting the concept that immobilizing hyperadhesiveness does not correspond to a general functional hyporesponsiveness of PMN, no depression of the initial ingestion rate was observed in the presence of 250 nM f-Met-Leu-Phe. Moreover, a close correlation was found between the induction of PMN adhesiveness and the stimulation of the hexose monophosphate pathway activity as well as of lysomal enzyme release (r ≥ 0.98). Thus, “chemotactic deactivation” and “high-dose inhibition of chemotaxis” by N-formyl peptides is the consequence of increased cell adhesiveness. This phenomenon provides a mechanism for cell trapping at the inflammatory site. Conversely, if operative in circulating blood, e.g., in septicemia, it may impair PMN emigration to such sites. Images PMID:447862

  1. Circulating factors induced by caloric restriction in the nonhuman primate Macaca mulatta activate angiogenic processes in endothelial cells.

    PubMed

    Csiszar, Anna; Sosnowska, Danuta; Tucsek, Zsuzsanna; Gautam, Tripti; Toth, Peter; Losonczy, Gyorgy; Colman, Ricki J; Weindruch, Richard; Anderson, Rozalyn M; Sonntag, William E; Ungvari, Zoltan

    2013-03-01

    Moderate caloric restriction (CR) without malnutrition increases healthspan in virtually every species studied, including nonhuman primates. In mice, CR exerts significant microvascular protective effects resulting in increased microvascular density in the heart and the brain, which likely contribute to enhanced tolerance to ischemia and improved cardiac performance and cognitive function. Yet, the underlying mechanisms by which CR confer microvascular protection remain elusive. To test the hypothesis that circulating factors triggered by CR regulate endothelial angiogenic capacity, we treated cultured human endothelial cells with sera derived from Macaca mulatta on long-term (over 10 years) CR. Cells treated with sera derived from ad-libitum-fed control monkeys served as controls. We found that factors present in CR sera upregulate vascular endothelial growth factor (VEGF) signaling and stimulate angiogenic processes, including endothelial cell proliferation and formation of capillary-like structures. Treatment with CR sera also tended to increase cellular migration (measured by a wound-healing assay using electric cell-substrate impedance sensing [ECIS] technology) and adhesion to collagen. Collectively, we find that circulating factors induced by CR promote endothelial angiogenic processes, suggesting that increased angiogenesis may be a potential mechanism by which CR improves cardiac function and prevents vascular cognitive impairment.

  2. The cell cycle and pluripotency.

    PubMed

    Hindley, Christopher; Philpott, Anna

    2013-04-15

    PSCs (pluripotent stem cells) possess two key properties that have made them the focus of global research efforts in regenerative medicine: they have unlimited expansion potential under conditions which favour their preservation as PSCs and they have the ability to generate all somatic cell types upon differentiation (pluripotency). Conditions have been defined in vitro in which pluripotency is maintained, or else differentiation is favoured and is directed towards specific somatic cell types. However, an unanswered question is whether or not the core cell cycle machinery directly regulates the pluripotency and differentiation properties of PSCs. If so, then manipulation of the cell cycle may represent an additional tool by which in vitro maintenance or differentiation of PSCs may be controlled in regenerative medicine. The present review aims to summarize our current understanding of links between the core cell cycle machinery and the maintenance of pluripotency in ESCs (embryonic stem cells) and iPSCs (induced PSCs).

  3. Cell Cycle Regulation by Checkpoints

    PubMed Central

    Barnum, Kevin J.; O’Connell, Matthew J.

    2016-01-01

    Cell cycle checkpoints are surveillance mechanisms that monitor the order, integrity, and fidelity of the major events of the cell cycle. These include growth to the appropriate cell size, the replication and integrity of the chromosomes, and their accurate segregation at mitosis. Many of these mechanisms are ancient in origin and highly conserved, and hence have been heavily informed by studies in simple organisms such as the yeasts. Others have evolved in higher organisms, and control alternative cell fates with significant impact on tumor suppression. Here, we consider these different checkpoint pathways and the consequences of their dysfunction on cell fate. PMID:24906307

  4. Cell cycle regulation by checkpoints.

    PubMed

    Barnum, Kevin J; O'Connell, Matthew J

    2014-01-01

    Cell cycle checkpoints are surveillance mechanisms that monitor the order, integrity, and fidelity of the major events of the cell cycle. These include growth to the appropriate cell size, the replication and integrity of the chromosomes, and their accurate segregation at mitosis. Many of these mechanisms are ancient in origin and highly conserved, and hence have been heavily informed by studies in simple organisms such as the yeasts. Others have evolved in higher organisms, and control alternative cell fates with significant impact on tumor suppression. Here, we consider these different checkpoint pathways and the consequences of their dysfunction on cell fate.

  5. Platelet factors induce chemotactic migration of murine mammary adenocarcinoma cells with different metastatic capabilities.

    PubMed Central

    Sarach, M. A.; Rovasio, R. A.; Eynard, A. R.

    1993-01-01

    The chemotactic response of neoplastic cells (NC) induced by soluble platelet factors was investigated. NC suspensions isolated from murine mammary gland adenocarcinomas having different metastatic capabilities were incubated in Boyden's chambers and challenged with (1) 'Early Platelet Factors' (EP), obtained from the soluble fraction of recently collagen-activated human platelets, and (2) 'Late Platelet Factors' (LP), isolated after 24 hours incubation of the platelet aggregates. Chemotaxis was expressed as the distance travelled by NC through nitrocellulose filters. NC isolated from M3, the tumour line having the stronger metastatic potential, showed a significant chemotactic response towards LP factors, whereas NC from the M2 line exhibiting the lower metastatic behaviour, showed a chemotactic response towards EP factors. Both tumour cell lines lacked motion capability towards the well known chemoattractant peptide N-f-Met-Leu-Phe-Phe as well as to serum, plasma, collagen type I or culture medium. The different chemotactic response of both tumour lines when they were challenged by concentration gradients of factors released by early or late collagen-activated human platelets, confirm a relationship between platelet activity and metastatic capabilities and suggests that platelet chemoattractants might play a role in the metastatic dissemination of these mammary gland adenocarcinomas. Images Figure 1 PMID:8217786

  6. Attenuation of tumor necrosis factor-induced endothelial cell cytotoxicity and neutrophil chemiluminescence

    SciTech Connect

    Zheng, H.; Crowley, J.J.; Chan, J.C.; Hoffmann, H.; Hatherill, J.R.; Ishizaka, A.; Raffin, T.A. )

    1990-11-01

    Our laboratory has previously shown that the administration of tumor necrosis factor (TNF), a cytokine produced by activated mononuclear cells, to guinea pigs produces a syndrome similar to gram-negative sepsis or ARDS. Pentoxifylline (PTX), a methylxanthine, protects against TNF-induced and sepsis-induced acute lung injury in vivo. We now report on in vitro cellular studies of PMN-mediated cellular injury and its attenuation. We studied TNF-induced bovine pulmonary artery endothelial cell (EC) cytotoxicity both with and without PMN. A 51Cr release assay was used to measure EC damage. Further, we investigated PMN function in response to TNF by measuring chemiluminescence. Agents that attenuate EC damage and PMN activation were evaluated in the above assays. Results revealed that TNF causes EC injury (p less than 0.05) and PMN increase TNF-induced EC injury. Furthermore, PTX, aminophylline (AMPH), caffeine, and forskolin attenuate TNF-induced EC cytotoxicity only in the presence of PMN (p less than 0.05). Of interest, dibutyryl cAMP (DBcAMP) protects EC from TNF-induced injury both with and without PMN. Agents that may increase cAMP levels in PMN (PTX, DBcAMP, forskolin, isobutyl methylxanthine, and terbutaline) significantly attenuate TNF-induced PMN chemiluminescence (p less than 0.05). We conclude that TNF causes EC damage and PMN increase this damage. Furthermore, PTX, AMPH, caffeine, and forskolin can attenuate TNF-induced EC injury in the presence of PMN, whereas DBcAMP attenuates TNF-induced EC injury with and without PMN. In addition, agents that may increase intracellular cAMP levels in PMN can attenuate TNF-induced PMN chemiluminescence. Thus, these agents likely attenuate TNF-induced PMN-mediated EC injury through their inhibitory effects on PMN.

  7. Trichomonas vaginalis homolog of macrophage migration inhibitory factor induces prostate cell growth, invasiveness, and inflammatory responses.

    PubMed

    Twu, Olivia; Dessí, Daniele; Vu, Anh; Mercer, Frances; Stevens, Grant C; de Miguel, Natalia; Rappelli, Paola; Cocco, Anna Rita; Clubb, Robert T; Fiori, Pier Luigi; Johnson, Patricia J

    2014-06-03

    The human-infective parasite Trichomonas vaginalis causes the most prevalent nonviral sexually transmitted infection worldwide. Infections in men may result in colonization of the prostate and are correlated with increased risk of aggressive prostate cancer. We have found that T. vaginalis secretes a protein, T. vaginalis macrophage migration inhibitory factor (TvMIF), that is 47% similar to human macrophage migration inhibitory factor (HuMIF), a proinflammatory cytokine. Because HuMIF is reported to be elevated in prostate cancer and inflammation plays an important role in the initiation and progression of cancers, we have explored a role for TvMIF in prostate cancer. Here, we show that TvMIF has tautomerase activity, inhibits macrophage migration, and is proinflammatory. We also demonstrate that TvMIF binds the human CD74 MIF receptor with high affinity, comparable to that of HuMIF, which triggers activation of ERK, Akt, and Bcl-2-associated death promoter phosphorylation at a physiologically relevant concentration (1 ng/mL, 80 pM). TvMIF increases the in vitro growth and invasion through Matrigel of benign and prostate cancer cells. Sera from patients infected with T. vaginalis are reactive to TvMIF, especially in males. The presence of anti-TvMIF antibodies indicates that TvMIF is released by the parasite and elicits host immune responses during infection. Together, these data indicate that chronic T. vaginalis infections may result in TvMIF-driven inflammation and cell proliferation, thus triggering pathways that contribute to the promotion and progression of prostate cancer.

  8. What cycles the cell? -Robust autonomous cell cycle models.

    PubMed

    Lavi, Orit; Louzoun, Yoram

    2009-12-01

    The cell cycle is one of the best studied cellular mechanisms at the experimental and theoretical levels. Although most of the important biochemical components and reactions of the cell cycle are probably known, the precise way the cell cycle dynamics are driven is still under debate. This phenomenon is not atypical to many other biological systems where the knowledge of the molecular building blocks and the interactions between them does not lead to a coherent picture of the appropriate dynamics. We here propose a methodology to develop plausible models for the driving mechanisms of embryonic and cancerous cell cycles. We first define a key property of the system (a cyclic behaviour in the case of the embryonic cell cycle) and set mathematical constraints on the types of two variable simplified systems robustly reproducing such a cyclic behaviour. We then expand these robust systems to three variables and reiterate the procedure. At each step, we further limit the type of expanded systems to fit the known microbiology until a detailed description of the system is obtained. This methodology produces mathematical descriptions of the required biological systems that are more robust to changes in the precise function and rate constants. This methodology can be extended to practically any type of subcellular mechanism.

  9. Autoradiography and the Cell Cycle.

    ERIC Educational Resources Information Center

    Jones, C. Weldon

    1992-01-01

    Outlines the stages of a cell biology "pulse-chase" experiment in which the students apply autoradiography techniques to learn about the concept of the cell cycle. Includes (1) seed germination and plant growth; (2) radioactive labeling and fixation of root tips; (3) feulgen staining of root tips; (4) preparation of autoradiograms; and…

  10. 2D protrusion but not motility predicts growth factor-induced cancer cell migration in 3D collagen.

    PubMed

    Meyer, Aaron S; Hughes-Alford, Shannon K; Kay, Jennifer E; Castillo, Amalchi; Wells, Alan; Gertler, Frank B; Lauffenburger, Douglas A

    2012-06-11

    Growth factor-induced migration is a critical step in the dissemination and metastasis of solid tumors. Although differences in properties characterizing cell migration on two-dimensional (2D) substrata versus within three-dimensional (3D) matrices have been noted for particular growth factor stimuli, the 2D approach remains in more common use as an efficient surrogate, especially for high-throughput experiments. We therefore were motivated to investigate which migration properties measured in various 2D assays might be reflective of 3D migratory behavioral responses. We used human triple-negative breast cancer lines stimulated by a panel of receptor tyrosine kinase ligands relevant to mammary carcinoma progression. Whereas 2D migration properties did not correlate well with 3D behavior across multiple growth factors, we found that increased membrane protrusion elicited by growth factor stimulation did relate robustly to enhanced 3D migration properties of the MDA-MB-231 and MDA-MB-157 lines. Interestingly, we observed this to be a more reliable relationship than cognate receptor expression or activation levels across these and two additional mammary tumor lines.

  11. Mitochondrial dynamics during cell cycling.

    PubMed

    Horbay, Rostyslav; Bilyy, Rostyslav

    2016-12-01

    Mitochondria are the cell's power plant that must be in a proper functional state in order to produce the energy necessary for basic cellular functions, such as proliferation. Mitochondria are 'dynamic' in that they are constantly undergoing fission and fusion to remain in a functional state throughout the cell cycle, as well as during other vital processes such as energy supply, cellular respiration and programmed cell death. The mitochondrial fission/fusion machinery is involved in generating young mitochondria, while eliminating old, damaged and non-repairable ones. As a result, the organelles change in shape, size and number throughout the cell cycle. Such precise and accurate balance is maintained by the cytoskeletal transporting system via microtubules, which deliver the mitochondrion from one location to another. During the gap phases G1 and G2, mitochondria form an interconnected network, whereas in mitosis and S-phase fragmentation of the mitochondrial network will take place. However, such balance is lost during neoplastic transformation and autoimmune disorders. Several proteins, such as Drp1, Fis1, Kif-family proteins, Opa1, Bax and mitofusins change in activity and might link the mitochondrial fission/fusion events with processes such as alteration of mitochondrial membrane potential, apoptosis, necrosis, cell cycle arrest, and malignant growth. All this indicates how vital proper functioning of mitochondria is in maintaining cell integrity and preventing carcinogenesis.

  12. Cell cycle regulation and regeneration.

    PubMed

    Heber-Katz, Ellen; Zhang, Yong; Bedelbaeva, Khamila; Song, Fengyu; Chen, Xiaoping; Stocum, David L

    2013-01-01

    Regeneration of ear punch holes in the MRL mouse and amputated limbs of the axolotl show a number of similarities. A large proportion of the fibroblasts of the uninjured MRL mouse ear are arrested in G2 of the cell cycle, and enter nerve-dependent mitosis after injury to form a ring-shaped blastema that regenerates the ear tissue. Multiple cell types contribute to the establishment of the regeneration blastema of the urodele limb by dedifferentiation, and there is substantial reason to believe that the cells of this early blastema are also arrested in G2, and enter mitosis under the influence of nerve-dependent factors supplied by the apical epidermal cap. Molecular analysis reveals other parallels, such as; (1) the upregulation of Evi5, a centrosomal protein that prevents mitosis by stabilizing Emi1, a protein that inhibits the degradation of cyclins by the anaphase promoting complex and (2) the expression of sodium channels by the epidermis. A central feature in the entry into the cell cycle by MRL ear fibroblasts is a natural downregulation of p21, and knockout of p21 in wild-type mice confers regenerative capacity on non-regenerating ear tissue. Whether the same is true for entry into the cell cycle in regenerating urodele limbs is presently unknown.

  13. Virus manipulation of cell cycle.

    PubMed

    Nascimento, R; Costa, H; Parkhouse, R M E

    2012-07-01

    Viruses depend on host cell resources for replication and access to those resources may be limited to a particular phase of the cell cycle. Thus manipulation of cell cycle is a commonly employed strategy of viruses for achieving a favorable cellular environment. For example, viruses capable of infecting nondividing cells induce S phase in order to activate the host DNA replication machinery and provide the nucleotide triphosphates necessary for viral DNA replication (Flemington in J Virol 75:4475-4481, 2001; Sullivan and Pipas in Microbiol Mol Biol Rev 66:179-202, 2002). Viruses have developed several strategies to subvert the cell cycle by association with cyclin and cyclin-dependent kinase complexes and molecules that regulate their activity. Viruses tend to act on cellular proteins involved in a network of interactions in a way that minimal protein-protein interactions lead to a major effect. The complex and interactive nature of intracellular signaling pathways controlling cell division affords many opportunities for virus manipulation strategies. Taking the maxim "Set a thief to catch a thief" as a counter strategy, however, provides us with the very same virus evasion strategies as "ready-made tools" for the development of novel antivirus therapeutics. The most obvious are attenuated virus vaccines with critical evasion genes deleted. Similarly, vaccines against viruses causing cancer are now being successfully developed. Finally, as viruses have been playing chess with our cell biology and immune responses for millions of years, the study of their evasion strategies will also undoubtedly reveal new control mechanisms and their corresponding cellular intracellular signaling pathways.

  14. MET inhibitor PHA-665752 suppresses the hepatocyte growth factor-induced cell proliferation and radioresistance in nasopharyngeal carcinoma cells

    SciTech Connect

    Liu, Tongxin; Li, Qi; Sun, Quanquan; Zhang, Yuqin; Yang, Hua; Wang, Rong; Chen, Longhua; Wang, Wei

    2014-06-20

    Highlights: • We demonstrated that irradiation induced MET overexpression and activation. • The aberrant MET signal mediated by HGF induced proliferation and radioresistance of NPC cells. • MET inhibitor PHA-665752 effectively suppressed HGF induced cell proliferation and radioresistance in NPC cells. • PHA-665752 suppressed the three downstream pathway of HGF/MET signal in a dose-dependent manner. - Abstract: Although ionizing radiation (IR) has provided considerable improvements in nasopharyngeal carcinoma (NPC), in subsets of patients, radioresistance is still a major problem in the treatment. In this study, we demonstrated that irradiation induced MET overexpression and activation, and the aberrant MET signal mediated by hepatocyte growth factor (HGF) induced radioresistance. We also found that MET inhibitor PHA-665752 effectively suppressed HGF induced cell proliferation and radioresistance in NPC cells. Further investigation indicated that PHA-665752 suppressed the phosphorylation of the Akt, ERK1/2, and STAT3 proteins in a dose-dependent manner. Our data indicated that the combination of IR with a MET inhibitor, such as PHA-665752, might be a promising therapeutic strategy for NPC.

  15. "Constructing" the Cell Cycle in 3D

    ERIC Educational Resources Information Center

    Koc, Isil; Turan, Merve

    2012-01-01

    The cycle of duplication and division, known as the "cell cycle," is the essential mechanism by which all living organisms reproduce. This activity allows students to develop an understanding of the main events that occur during the typical eukaryotic cell cycle mostly in the process of mitotic phase that divides the duplicated genetic material…

  16. Cytofluorometric assessment of cell cycle progression.

    PubMed

    Vitale, Ilio; Jemaà, Mohamed; Galluzzi, Lorenzo; Metivier, Didier; Castedo, Maria; Kroemer, Guido

    2013-01-01

    One of the most prominent features of cellular senescence, a stress response that prevents the propagation of cells that have accumulated potentially oncogenic alterations, is a permanent loss of proliferative potential. Thus, at odds with quiescent cells, which resume proliferation when stimulated to do so, senescent cells cannot proceed through the cell cycle even in the presence of mitogenic factors. Here, we describe a set of cytofluorometric techniques for studying how chemical and/or physical stimuli alter the cell cycle in vitro, in both qualitative and quantitative terms. Taken together, these methods allow for the identification of bona fide cytostatic effects as well as for a refined characterization of cell cycle distributions, providing information on proliferation, DNA content as well as on the presence of cell cycle phase-specific markers. At the end of the chapter, a set of guidelines is offered to assist researchers that approach the study of the cell cycle with the interpretation of results.

  17. Cell cycle control and seed development.

    PubMed

    Dante, Ricardo A; Larkins, Brian A; Sabelli, Paolo A

    2014-01-01

    Seed development is a complex process that requires coordinated integration of many genetic, metabolic, and physiological pathways and environmental cues. Different cell cycle types, such as asymmetric cell division, acytokinetic mitosis, mitotic cell division, and endoreduplication, frequently occur in sequential yet overlapping manner during the development of the embryo and the endosperm, seed structures that are both products of double fertilization. Asymmetric cell divisions in the embryo generate polarized daughter cells with different cell fates. While nuclear and cell division cycles play a key role in determining final seed cell numbers, endoreduplication is often associated with processes such as cell enlargement and accumulation of storage metabolites that underlie cell differentiation and growth of the different seed compartments. This review focuses on recent advances in our understanding of different cell cycle mechanisms operating during seed development and their impact on the growth, development, and function of seed tissues. Particularly, the roles of core cell cycle regulators, such as cyclin-dependent-kinases and their inhibitors, the Retinoblastoma-Related/E2F pathway and the proteasome-ubiquitin system, are discussed in the contexts of different cell cycle types that characterize seed development. The contributions of nuclear and cellular proliferative cycles and endoreduplication to cereal endosperm development are also discussed.

  18. Cell cycle control and seed development

    PubMed Central

    Dante, Ricardo A.; Larkins, Brian A.; Sabelli, Paolo A.

    2014-01-01

    Seed development is a complex process that requires coordinated integration of many genetic, metabolic, and physiological pathways and environmental cues. Different cell cycle types, such as asymmetric cell division, acytokinetic mitosis, mitotic cell division, and endoreduplication, frequently occur in sequential yet overlapping manner during the development of the embryo and the endosperm, seed structures that are both products of double fertilization. Asymmetric cell divisions in the embryo generate polarized daughter cells with different cell fates. While nuclear and cell division cycles play a key role in determining final seed cell numbers, endoreduplication is often associated with processes such as cell enlargement and accumulation of storage metabolites that underlie cell differentiation and growth of the different seed compartments. This review focuses on recent advances in our understanding of different cell cycle mechanisms operating during seed development and their impact on the growth, development, and function of seed tissues. Particularly, the roles of core cell cycle regulators, such as cyclin-dependent-kinases and their inhibitors, the Retinoblastoma-Related/E2F pathway and the proteasome-ubiquitin system, are discussed in the contexts of different cell cycle types that characterize seed development. The contributions of nuclear and cellular proliferative cycles and endoreduplication to cereal endosperm development are also discussed. PMID:25295050

  19. Cell cycle gene expression under clinorotation

    NASA Astrophysics Data System (ADS)

    Artemenko, Olga

    2016-07-01

    Cyclins and cyclin-dependent kinase (CDK) are main regulators of the cell cycle of eukaryotes. It's assumes a significant change of their level in cells under microgravity conditions and by other physical factors actions. The clinorotation use enables to determine the influence of gravity on simulated events in the cell during the cell cycle - exit from the state of quiet stage and promotion presynthetic phase (G1) and DNA synthesis phase (S) of the cell cycle. For the clinorotation effect study on cell proliferation activity is the necessary studies of molecular mechanisms of cell cycle regulation and development of plants under altered gravity condition. The activity of cyclin D, which is responsible for the events of the cell cycle in presynthetic phase can be controlled by the action of endogenous as well as exogenous factors, but clinorotation is one of the factors that influence on genes expression that regulate the cell cycle.These data can be used as a model for further research of cyclin - CDK complex for study of molecular mechanisms regulation of growth and proliferation. In this investigation we tried to summarize and analyze known literature and own data we obtained relatively the main regulators of the cell cycle in altered gravity condition.

  20. The peri-cell-cycle in Arabidopsis.

    PubMed

    Beeckman, T; Burssens, S; Inzé, D

    2001-03-01

    The root systems of plants proliferate via de novo formed meristems originating from differentiated pericycle cells. The identity of putative signals responsible for triggering some of the pericycle cells to re-enter the cell cycle remains unknown. Here, the cell cycle regulation in the pericycle of seedling roots of Arabidopsis thaliana (L.) HEYNH: is studied shortly after germination using various strategies. Based on the detailed analysis of the promoter-beta-glucuronidase activity of four key cell cycle regulatory genes, combined with cell length measurements, microdensitometry of DNA content, and experiments with a cell cycle-blocking agent, a model is proposed for cell cycle regulation in the pericycle at the onset of lateral root initiation. The results clearly show that before the first lateral root is initiated, the pericycle consists of dissimilar cell files in respect of their cell division history. Depending on the distance behind the root tip and on position in relation to the vascular tissue, particular pericycle cells remain in the G(2) phase of the cell cycle and are apparently more susceptible to lateral root initiation than others.

  1. Stretched cell cycle model for proliferating lymphocytes

    PubMed Central

    Dowling, Mark R.; Kan, Andrey; Heinzel, Susanne; Zhou, Jie H. S.; Marchingo, Julia M.; Wellard, Cameron J.; Markham, John F.; Hodgkin, Philip D.

    2014-01-01

    Stochastic variation in cell cycle time is a consistent feature of otherwise similar cells within a growing population. Classic studies concluded that the bulk of the variation occurs in the G1 phase, and many mathematical models assume a constant time for traversing the S/G2/M phases. By direct observation of transgenic fluorescent fusion proteins that report the onset of S phase, we establish that dividing B and T lymphocytes spend a near-fixed proportion of total division time in S/G2/M phases, and this proportion is correlated between sibling cells. This result is inconsistent with models that assume independent times for consecutive phases. Instead, we propose a stretching model for dividing lymphocytes where all parts of the cell cycle are proportional to total division time. Data fitting based on a stretched cell cycle model can significantly improve estimates of cell cycle parameters drawn from DNA labeling data used to monitor immune cell dynamics. PMID:24733943

  2. Hepatocyte growth factor/scatter factor induces a variety of tissue- specific morphogenic programs in epithelial cells

    PubMed Central

    1995-01-01

    Hepatocyte growth factor/scatter factor (HGF/SF) is the mesenchymal ligand of the epithelial tyrosine kinase receptor c-Met. In vitro, HGF/SF has morphogenic properties, e.g., induces kidney epithelial cells to form branching ducts in collagen gels. Mutation of the HGF/SF gene in mice results in embryonic lethality due to severe liver and placenta defects. Here, we have evaluated the morphogenic activity of HGF/SF with a large variety of epithelial cells grown in three- dimensional collagen matrices. We found that HGF/SF induces SW 1222 colon carcinoma cells to form crypt-like structures. In these organoids, cells exhibit apical/basolateral polarity and build a well- developed brush border towards the lumen. Capan 2 pancreas carcinoma cells, upon addition of HGF/SF, develop large hollow spheroids lined with a tight layer of polarized cells. Collagen inside the cysts is digested and the cells show features of pancreatic ducts. HGF/SF induces EpH4 mammary epithelial cells to form long branches with end- buds that resemble developing mammary ducts. pRNS-1-1 prostate epithelial cells in the presence of HGF/SF develop long ducts with distal branching as found in the prostate. Finally, HGF/SF simulates alveolar differentiation in LX-1 lung carcinoma cells. Expression of transfected HGF/SF cDNA in LX-1 lung carcinoma and EpH4 mammary epithelial cells induce morphogenesis in an autocrine manner. In the cell lines tested, HGF/SF activated the Met receptor by phosphorylation of tyrosine residues. These data show that HGF/SF induces intrinsic, tissue-specific morphogenic activities in a wide variety of epithelial cells. Apparently, HGF/SF triggers respective endogenous programs and is thus an inductive, not an instructive, mesenchymal effector for epithelial morphogenesis. PMID:8522613

  3. A minority of carcinoma cells producing acidic fibroblast growth factor induces a community effect for tumor progression.

    PubMed Central

    Jouanneau, J; Moens, G; Bourgeois, Y; Poupon, M F; Thiery, J P

    1994-01-01

    It is generally accepted that primary tumors become heterogeneous as a consequence of tumor-cell genetic instability. Clonal dominance has been shown to occur in some experimental models allowing a subpopulation of cells to overgrow the primary heterogeneous tumor and to metastasize. Alternatively, interactions among coexisting tumor subpopulations may contribute to the emergence of a malignant invasive primary solid tumor. We asked the question whether emergence of carcinoma cells producing a growth/dissociating factor within a tumor cell population may be a determinant for tumor progression and for clonal dominance. To mimic such a situation, we have investigated the impact of tumor subpopulation heterogeneity in an in vivo model in which mixtures of carcinoma cells that differ in their ability to produce acidic fibroblast growth factor are injected into nude mice. Our data indicate that a growth-factor-producing cell subpopulation can confer increased tumorigenicity to an entire cell population and subsequently elicit a shorter delay for appearance of metastasis. A community effect via cell interactions may account for a heterogeneous tumor cell population rather than clonal dominance during progression of certain tumor types. Images Fig. 3 PMID:7506417

  4. Protein tyrosine nitration in the cell cycle

    SciTech Connect

    Jia, Min; Mateoiu, Claudia; Souchelnytskyi, Serhiy

    2011-09-23

    Highlights: {yields} Enrichment of 3-nitrotyrosine containing proteins from cells synchronized in different phases of the cell cycle. {yields} Identification of 76 tyrosine nitrated proteins that change expression during the cell cycle. {yields} Nineteen identified proteins were previously described as regulators of cell proliferation. -- Abstract: Nitration of tyrosine residues in proteins is associated with cell response to oxidative/nitrosative stress. Tyrosine nitration is relatively low abundant post-translational modification that may affect protein functions. Little is known about the extent of protein tyrosine nitration in cells during progression through the cell cycle. Here we report identification of proteins enriched for tyrosine nitration in cells synchronized in G0/G1, S or G2/M phases of the cell cycle. We identified 27 proteins in cells synchronized in G0/G1 phase, 37 proteins in S phase synchronized cells, and 12 proteins related to G2/M phase. Nineteen of the identified proteins were previously described as regulators of cell proliferation. Thus, our data indicate which tyrosine nitrated proteins may affect regulation of the cell cycle.

  5. Tissue factor induces VEGF expression via activation of the Wnt/β-catenin signaling pathway in ARPE-19 cells

    PubMed Central

    Wang, Ying; Sang, Aimin; Zhu, Manhui; Zhang, Guowei; Guan, Huaijin; Ji, Min

    2016-01-01

    Purpose The purpose of the present study was to investigate the potential signal mechanism of tissue factor (TF) in the regulation of the expression of vascular endothelial growth factor (VEGF) in human retinal pigment epithelial (ARPE-19) cells. Methods An in vitro RPE cell chemical hypoxia model was established by adding cobalt chloride (CoCl2) in the culture medium. The irritative concentration of CoCl2 was determined with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay kit. VEGF production in ARPE-19 cells was measured with enzyme-linked immunosorbent assay (ELISA) and western blotting. The Wnt signaling pathway–associated molecules, including phospho-glycogen synthase kinase 3β (p-GSK3β), GSK3β, p-β-catenin and β-catenin, were detected with western blotting. pEGFP-N3-hTF was constructed and verified with digestion of the restriction enzyme and sequencing analysis. Human TF overexpression and silencing plasmids were transfected into the ARPE-19 cells to clarify the causal relationship between TF and VEGF expression. The Transwell coculture system of ARPE-19 cells and RF/6A rhesus macaque choroid–retinal endothelial cells was performed to evaluate cell invasion and tube formation ability. Results Our anoxic model of ARPE-19 cells showed that TF expression was upregulated in accordance with variations in hypoxia-inducible factor 1-alpha (HIF-1α) and VEGF levels. Silencing and overexpression of TF decreased and increased VEGF expression, respectively. The Wnt/β-catenin signaling pathway played an important role in this effect. Results from the ARPE-19 cell and RF/6A cell coculture system showed that the enhancement of TF expression in the ARPE-19 cells led to significantly faster invasion and stronger tube-forming ability of the RF/6A cells, while siRNA-mediated TF silencing caused the opposite effects. Pharmacological disruption of Wnt signaling IWR-1-endo inhibited the effects compared to the TF-overexpressing group

  6. Nucleosome architecture throughout the cell cycle.

    PubMed

    Deniz, Özgen; Flores, Oscar; Aldea, Martí; Soler-López, Montserrat; Orozco, Modesto

    2016-01-28

    Nucleosomes provide additional regulatory mechanisms to transcription and DNA replication by mediating the access of proteins to DNA. During the cell cycle chromatin undergoes several conformational changes, however the functional significance of these changes to cellular processes are largely unexplored. Here, we present the first comprehensive genome-wide study of nucleosome plasticity at single base-pair resolution along the cell cycle in Saccharomyces cerevisiae. We determined nucleosome organization with a specific focus on two regulatory regions: transcription start sites (TSSs) and replication origins (ORIs). During the cell cycle, nucleosomes around TSSs display rearrangements in a cyclic manner. In contrast to gap (G1 and G2) phases, nucleosomes have a fuzzier organization during S and M phases, Moreover, the choreography of nucleosome rearrangements correlate with changes in gene expression during the cell cycle, indicating a strong association between nucleosomes and cell cycle-dependent gene functionality. On the other hand, nucleosomes are more dynamic around ORIs along the cell cycle, albeit with tighter regulation in early firing origins, implying the functional role of nucleosomes on replication origins. Our study provides a dynamic picture of nucleosome organization throughout the cell cycle and highlights the subsequent impact on transcription and replication activity.

  7. Nucleosome architecture throughout the cell cycle

    PubMed Central

    Deniz, Özgen; Flores, Oscar; Aldea, Martí; Soler-López, Montserrat; Orozco, Modesto

    2016-01-01

    Nucleosomes provide additional regulatory mechanisms to transcription and DNA replication by mediating the access of proteins to DNA. During the cell cycle chromatin undergoes several conformational changes, however the functional significance of these changes to cellular processes are largely unexplored. Here, we present the first comprehensive genome-wide study of nucleosome plasticity at single base-pair resolution along the cell cycle in Saccharomyces cerevisiae. We determined nucleosome organization with a specific focus on two regulatory regions: transcription start sites (TSSs) and replication origins (ORIs). During the cell cycle, nucleosomes around TSSs display rearrangements in a cyclic manner. In contrast to gap (G1 and G2) phases, nucleosomes have a fuzzier organization during S and M phases, Moreover, the choreography of nucleosome rearrangements correlate with changes in gene expression during the cell cycle, indicating a strong association between nucleosomes and cell cycle-dependent gene functionality. On the other hand, nucleosomes are more dynamic around ORIs along the cell cycle, albeit with tighter regulation in early firing origins, implying the functional role of nucleosomes on replication origins. Our study provides a dynamic picture of nucleosome organization throughout the cell cycle and highlights the subsequent impact on transcription and replication activity. PMID:26818620

  8. Distinct growth factor-induced dynamic mass redistribution (DMR) profiles for monitoring oncogenic signaling pathways in various cancer cells.

    PubMed

    Du, Yuhong; Li, Zijian; Li, Lian; Chen, Zhuo Georgia; Sun, Shi-Yong; Chen, Peifang; Shin, Dong M; Khuri, Fadlo R; Fu, Haian

    2009-01-01

    Targeting dysregulated signaling pathways in tumors has led to the development of a novel class of signal transduction inhibitors, including inhibitors of the epidermal growth factor (EGF) receptor (EGFR). To dissect oncogenic pathways, identify key pathway determinants, and evaluate the efficacy of targeted agents, it is vital to develop technologies that allow the detection of temporal signaling events under physiological conditions. Here we report the application of a label-free optical biosensor to reveal the rapid response of cancer cells to EGF, expressed as a dynamic mass redistribution (DMR) signal. In response to EGF, squamous cell carcinoma of the head and neck cells exhibited a rapid rise in DMR signal, whereas lung adenocarcinoma cells showed a biphasic DMR profile, suggesting a cell type-dependent DMR response. Pharmacological studies suggested the importance of EGFR and the phosphatidylinositol-3 kinase pathway in mediating the EGF-induced DMR response. The defined DMR signatures offer a simple yet sensitive tool for evaluating EGFR-targeted agents, as shown with gefitinib and erlotinib. The assay can also be used for cell-based high-throughput screening of EGF pathway inhibitors, as demonstrated by its robust performance in a 384-well plate format (Z' > 0.5). This technology is applicable to other oncogenic pathways for the discovery of novel therapeutic agents for the treatment of various cancers.

  9. Critical role of aquaporin-3 in epidermal growth factor-induced migration of colorectal carcinoma cells and its clinical significance.

    PubMed

    Li, Ang; Lu, Dehong; Zhang, Yupeng; Li, Jia; Fang, Yu; Li, Fei; Sun, Jiabang

    2013-02-01

    Aquaporins (AQPs) are a family of small, integral membrane proteins that have been shown to play an important role in tumor development and metastasis. Several studies have demonstrated that expression of AQP3 contributes to the enhanced migration of epithelial cells and is related to differentiation, metastasis and vascular invasion in lung and gastric cancer. Therefore, we investigated whether AQP3 could enhance human colorectal carcinoma cell migration and we examined the role of AQP3 in the prognosis of colorectal carcinoma. Our results showed that human epidermal growth factor (hEGF) increased the expression of AQP3 and, subsequently, the migration ability of human colorectal carcinoma cells HCT116 in a dose- and time-dependent manner. The enhanced migration ability of HCT116 cells was blocked by the AQP3 inhibitor, CuSO(4). Overexpression of AQP3 induced by hEGF was inhibited by a PI3K/AKT inhibitor, LY294002, but the ERK inhibitor U0126 had a minor effect on the hEGF-induced AQP3 upregulation. Immunohistochemical staining of the cancer tissues and corresponding normal tissues showed that AQP3 expression in cancer tissue was higher compared to that in normal tissue. The expression intensity of AQP3 was associated with the differentiation, lymph node and distant metastasis of colorectal carcinoma patients. Our results suggest that AQP3 overexpression could facilitate colorectal carcinoma cell migration and AQP3 may be considered a potential indicator and therapeutic target for colon tumor metastasis and prognosis.

  10. HER2 mediates epidermal growth factor-induced down-regulation of E-cadherin in human ovarian cancer cells.

    PubMed

    Cheng, Jung-Chien; Qiu, Xin; Chang, Hsun-Ming; Leung, Peter C K

    2013-04-26

    Overexpression of HER2 is correlated with a poor prognosis in many types of human cancers. Due to the interaction between HER2 and other ErbB receptors, HER2 is implicated in the EGF family of ligands-regulated tumor progression. In ovarian cancer, although the relationships between HER2 amplification and patient prognosis remain controversial, the underlying molecular mechanisms of HER2-mediated tumor progression are not fully understood. Our previous studies demonstrated that EGF induces ovarian cancer cell invasion by down-regulating E-cadherin expression through the up-regulation of its transcriptional repressors, Snail and Slug. It has been shown that overexpression of HER2 down-regulates E-cadherin expression in human mammary epithelial cells. However, whether HER2 mediates EGF-induced down-regulation of E-cadherin remains unknown. In this study, we examined the potential role of HER2 in EGF-induced down-regulation of E-cadherin and increased cell invasion. We show that EGF treatment induces the interaction of EGFR with HER2 and increases the activation of HER2 in human ovarian cancer cells; we also show that these effects are diminished by knockdown of EGFR. Importantly, treatment with HER2-specific tyrosine kinase inhibitor, AG825, and HER2 siRNA diminished the up-regulation of Snail and Slug as well as the down-regulation of E-cadherin by EGF. Finally, we also show that EGF-induced cell invasion was attenuated by treatment with HER2 siRNA. This study demonstrates an important role for HER2 in mediating the effects of EGF on Snail, Slug and E-cadherin expression as well as invasiveness in human ovarian cancer cells.

  11. Transcription factor-induced activation of cardiac gene expression in human c-kit+ cardiac progenitor cells

    PubMed Central

    Vajravelu, Bathri N.; Moktar, Afsoon; Cao, Pengxiao; Moore, Joseph B.; Bolli, Roberto

    2017-01-01

    Although transplantation of c-kit+ cardiac progenitor cells (CPCs) significantly alleviates post-myocardial infarction left ventricular dysfunction, generation of cardiomyocytes by exogenous CPCs in the recipient heart has often been limited. Inducing robust differentiation would be necessary for improving the efficacy of the regenerative cardiac cell therapy. We assessed the hypothesis that differentiation of human c-kit+ CPCs can be enhanced by priming them with cardiac transcription factors (TFs). We introduced five different TFs (Gata4, MEF2C, NKX2.5, TBX5, and BAF60C) into CPCs, either alone or in combination, and then examined the expression of marker genes associated with the major cardiac cell types using quantitative RT-PCR. When introduced individually, Gata4 and TBX5 induced a subset of myocyte markers. Moreover, Gata4 alone significantly induced smooth muscle cell and fibroblast markers. Interestingly, these gene expression changes brought by Gata4 were also accompanied by morphological changes. In contrast, MEF2C and NKX2.5 were largely ineffective in initiating cardiac gene expression in CPCs. Surprisingly, introduction of multiple TFs in different combinations mostly failed to act synergistically. Likewise, addition of BAF60C to Gata4 and/or TBX5 did not further potentiate their effects on cardiac gene expression. Based on our results, it appears that GATA4 is able to potentiate gene expression programs associated with multiple cardiovascular lineages in CPCs, suggesting that GATA4 may be effective in priming CPCs for enhanced differentiation in the setting of stem cell therapy. PMID:28355297

  12. Mechano-growth factor induces migration of rat mesenchymal stem cells by altering its mechanical properties and activating ERK pathway

    SciTech Connect

    Wu, Jiamin; Wu, Kewen; Lin, Feng; Luo, Qing; Yang, Li; Shi, Yisong; Song, Guanbin; Sung, Kuo-Li Paul

    2013-11-08

    Highlights: •MGF induced the migration of rat MSC in a concentration-dependent manner. •MGF enhanced the mechanical properties of rMSC in inducing its migration. •MGF activated the ERK 1/2 signaling pathway of rMSC in inducing its migration. •rMSC mechanics may synergy with ERK 1/2 pathway in MGF-induced rMSC migration. -- Abstract: Mechano-growth factor (MGF) generated by cells in response to mechanical stimulation has been identified as a mechano effector molecule, playing a key role in regulating mesenchymal stem cell (MSC) function, including proliferation and migration. However, the mechanism(s) underlying how MGF-induced MSC migration occurs is still unclear. In the present study, MGF motivated migration of rat MSCs (rMSCs) in a concentration-dependent manner and optimal concentration of MGF at 50 ng/mL (defined as MGF treatment in this paper) was demonstrated. Notably, enhancement of mechanical properties that is pertinent to cell migration, such as cell traction force and cell stiffness were found to respond to MGF treatment. Furthermore, MGF increased phosphorylation of extracellular signal-regulated kinase (ERK), ERK inhibitor (i.e., PD98059) suppressed ERK phosphorylation, and abolished MGF-induced rMSC migration were found, demonstrating that ERK is involved molecule for MGF-induced rMSC migration. These in vitro evidences of MGF-induced rMSC migration and its direct link to altering rMSC mechanics and activating the ERK pathway, uncover the underlying biomechanical and biological mechanisms of MGF-induced rMSC migration, which may help find MGF-based application of MSC in clinical therapeutics.

  13. Heparin Inhibits Hepatocyte Growth Factor Induced Motility and Invasion of Hepatocellular Carcinoma Cells through Early Growth Response Protein 1

    PubMed Central

    Ozen, Evin; Gozukizil, Aysim; Erdal, Esra; Uren, Aykut; Bottaro, Donald P.; Atabey, Nese

    2012-01-01

    The Hepatocyte Growth Factor (HGF)/c-Met signaling pathway regulates hepatocyte proliferation, and pathway aberrations are implicated in the invasive and metastatic behaviors of hepatocellular carcinoma (HCC). In addition to c-Met, heparin acts as a co-receptor to modulate pathway activity. Recently, anti-metastatic and anti-cancer effects of heparin have been reported. However, the role of heparin in the regulation of HGF signaling remains controversial and the effects of heparin on HGF-induced biological responses during hepatocarcinogenesis is not yet defined. In this study we determined the effects of heparin on HGF-induced activities of HCC cells and the underlying molecular mechanisms. Here, we report for the first time that heparin inhibits HGF-induced adhesion, motility and invasion of HCC cells. In addition, heparin reduced HGF-induced activation of c-Met and MAPK in a dose-dependent manner, as well as decreased transcriptional activation and expression of Early growth response factor 1 (Egr1). HGF-induced MMP-2 and MMP-9 activation, and MT1-MMP expression, also were inhibited by heparin. Stable knockdown of Egr1 caused a significant decrease in HGF-induced invasion, as well as the activation and expression of MMPs. Parallel to these findings, the overexpression of Egr1 increased the invasiveness of HCC cells. Our results suggest that Egr1 activates HGF-induced cell invasion through the regulation of MMPs in HCC cells and heparin inhibits HGF-induced cellular invasion via the downregulation of Egr1. Therefore, heparin treatment might be a therapeutic approach to inhibit invasion and metastasis of HCC, especially for patients with active HGF/c-Met signaling. PMID:22912725

  14. Nerve growth factor-induced neurite sprouting in PC12 cells involves sigma-1 receptors: implications for antidepressants.

    PubMed

    Takebayashi, Minoru; Hayashi, Teruo; Su, Tsung-Ping

    2002-12-01

    One theory concerning the action of antidepressants relates to the drugs' ability to induce an adaptive plasticity in neurons such as neurite sprouting. Certain antidepressants are known to bind to sigma-1 receptors (Sig-1R) with high affinity. Sig-1R are dynamic endoplasmic reticulum proteins that are highly concentrated at the tip of growth cones in cultured cells. We therefore tested the hypotheses that Sig-1R might participate in the neurite sprouting and that antidepressants with Sig-1R affinity may promote the neuronal sprouting via Sig-1R. The prototypic Sig-1R agonist (+)-pentazocine [(+)PTZ], as well as the Sig-1R-active antidepressants imipramine and fluvoxamine, although ineffective by themselves, were found to enhance the nerve growth factor (NGF)-induced neurite sprouting in PC12 cells in a dose-dependent manner. A Sig-1R antagonist N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]-ethylamine monohydrochloride (NE100) blocked the enhancements caused by these Sig-1R agonists. In separate experiments, we found that NGF dose and time dependently increased Sig-1R in PC12 cells. Chronic treatment of cells with (+)PTZ, imipramine, or fluvoxamine also increased Sig-1R. These latter results suggested that NGF induces the neurite sprouting by increasing Sig-1R. Indeed, the overexpression of Sig-1R per se in PC12 cells enhanced the NGF-induced neurite sprouting. Furthermore, antisense deoxyoligonucleotides directed against Sig-1R attenuated the NGF-induced neurite sprouting. Thus, when taken together, our results indicate that Sig-1R play an important role in the NGF-induced neurite sprouting and that certain antidepressants may facilitate neuronal sprouting in the brain via Sig-1R.

  15. Transcription factor-induced activation of cardiac gene expression in human c-kit+ cardiac progenitor cells.

    PubMed

    Al-Maqtari, Tareq; Hong, Kyung U; Vajravelu, Bathri N; Moktar, Afsoon; Cao, Pengxiao; Moore, Joseph B; Bolli, Roberto

    2017-01-01

    Although transplantation of c-kit+ cardiac progenitor cells (CPCs) significantly alleviates post-myocardial infarction left ventricular dysfunction, generation of cardiomyocytes by exogenous CPCs in the recipient heart has often been limited. Inducing robust differentiation would be necessary for improving the efficacy of the regenerative cardiac cell therapy. We assessed the hypothesis that differentiation of human c-kit+ CPCs can be enhanced by priming them with cardiac transcription factors (TFs). We introduced five different TFs (Gata4, MEF2C, NKX2.5, TBX5, and BAF60C) into CPCs, either alone or in combination, and then examined the expression of marker genes associated with the major cardiac cell types using quantitative RT-PCR. When introduced individually, Gata4 and TBX5 induced a subset of myocyte markers. Moreover, Gata4 alone significantly induced smooth muscle cell and fibroblast markers. Interestingly, these gene expression changes brought by Gata4 were also accompanied by morphological changes. In contrast, MEF2C and NKX2.5 were largely ineffective in initiating cardiac gene expression in CPCs. Surprisingly, introduction of multiple TFs in different combinations mostly failed to act synergistically. Likewise, addition of BAF60C to Gata4 and/or TBX5 did not further potentiate their effects on cardiac gene expression. Based on our results, it appears that GATA4 is able to potentiate gene expression programs associated with multiple cardiovascular lineages in CPCs, suggesting that GATA4 may be effective in priming CPCs for enhanced differentiation in the setting of stem cell therapy.

  16. Nonsteroidal anti-inflammatory drugs attenuate proliferation of colonic carcinoma cells by blocking epidermal growth factor-induced Ca++ mobilization.

    PubMed

    Kokoska, E R; Smith, G S; Miller, T A

    2000-01-01

    Numerous studies suggest that nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit colorectal carcinogenesis. We have previously reported that NSAIDs, in human colonic carcinoma cells (Caco-2), attenuate epidermal growth factor (EGF)-induced cellular proliferation through a process independent of their inhibitory effects on prostaglandin synthesis. Furthermore, separate studies have also suggested that NSAIDs inhibit EGF-induced store-operated Ca++ influx. Thus we developed the hypothesis that NSAIDs may limit the activity of EGF by altering intracellular Ca++ ([Ca++]i) mobilization. Serum-deprived Caco-2 cells were employed for all experimentation. [Ca++]i was measured with Fluo-3 and extracellular Ca++ influx was monitored by quenching Fluo-3 fluorescence with Mn++. Proliferation was quantitated with two assays: cellular nucleic acid and total protein content. Caco-2 cells exposed to EGF demonstrated an initial increase in [Ca++]i which was blocked by neomycin, an inhibitor of IPsubscript 3 generation, and the phospholipase C inhibitor U73122 but not U73343 (inactive control). This was followed by sustained extracellular Ca++ influx, which was attenuated with calcium-free buffer (-Ca++), the store- operated Ca++ channel blocker lanthanum, indomethacin, ibuprofen, and aspirin. In subsequent studies, cells were treated with either serum-free media or EGF +/- the aforementioned inhibitors, and again serum starved. Cells exposed to EGF +/- the inactive phospholipase C inhibitor U73343 demonstrated a significant increase in nucleic acid and protein. However, proliferation induced by EGF was not observed when [Ca++]i elevation was prevented by blocking either internal Ca++ store release via phospholipase C/IPsubscript 3 or sustained Ca++ influx through store-operated Ca++ channels. Sustained [Ca++]i elevation, as induced by EGF, appears to be required for mitogenesis. These data support our premise that one mechanism whereby NSAIDs may attenuate colonic neoplasia is

  17. Interplay between cell growth and cell cycle in plants.

    PubMed

    Sablowski, Robert; Carnier Dornelas, Marcelo

    2014-06-01

    The growth of organs and whole plants depends on both cell growth and cell-cycle progression, but the interaction between both processes is poorly understood. In plants, the balance between growth and cell-cycle progression requires coordinated regulation of four different processes: macromolecular synthesis (cytoplasmic growth), turgor-driven cell-wall extension, mitotic cycle, and endocycle. Potential feedbacks between these processes include a cell-size checkpoint operating before DNA synthesis and a link between DNA contents and maximum cell size. In addition, key intercellular signals and growth regulatory genes appear to target at the same time cell-cycle and cell-growth functions. For example, auxin, gibberellin, and brassinosteroid all have parallel links to cell-cycle progression (through S-phase Cyclin D-CDK and the anaphase-promoting complex) and cell-wall functions (through cell-wall extensibility or microtubule dynamics). Another intercellular signal mediated by microtubule dynamics is the mechanical stress caused by growth of interconnected cells. Superimposed on developmental controls, sugar signalling through the TOR pathway has recently emerged as a central control point linking cytoplasmic growth, cell-cycle and cell-wall functions. Recent progress in quantitative imaging and computational modelling will facilitate analysis of the multiple interconnections between plant cell growth and cell cycle and ultimately will be required for the predictive manipulation of plant growth.

  18. Adherent cells in granulocyte-macrophage colony-stimulating factor-induced bone marrow-derived dendritic cell culture system are qualified dendritic cells.

    PubMed

    Li, Gong-Bo; Lu, Guang-Xiu

    2010-01-01

    A widely-used method for generating dendritic cell (DC) is to culture bone marrow cells in granulocyte-macrophage colony-stimulating factor (GM-CSF)-containing medium for 6-10 days. Usually, non-adherent cells are used as qualified dendritic cells while the adherent ones are discarded as "non-dendritic cells" or macrophages. In this study, we show that the adherent cells are nearly identical to the non-adherent cells in both dendritic cell surface markers expression and main dendritic cell-related functions, hence to prove that these "junk cells" are actually qualified dendritic cells.

  19. Combination of Collagen-Based Scaffold and Bioactive Factors Induces Adipose-Derived Mesenchymal Stem Cells Chondrogenic Differentiation In vitro

    PubMed Central

    Calabrese, Giovanna; Forte, Stefano; Gulino, Rosario; Cefalì, Francesco; Figallo, Elisa; Salvatorelli, Lucia; Maniscalchi, Eugenia T.; Angelico, Giuseppe; Parenti, Rosalba; Gulisano, Massimo; Memeo, Lorenzo; Giuffrida, Raffaella

    2017-01-01

    Recently, multipotent mesenchymal stem cells (MSCs) have attracted much attention in the field of regenerative medicine due to their ability to give rise to different cell types, including chondrocytes. Damaged articular cartilage repair is one of the most challenging issues for regenerative medicine, due to the intrinsic limited capability of cartilage to heal because of its avascular nature. While surgical approaches like chondral autografts and allografts provide symptoms and function improvement only for a short period, MSC based stimulation therapies, like microfracture surgery or autologous matrix-induced chondrogenesis demonstrate to be more effective. The use of adult chondrocytes, which are the main cellular constituent of cartilage, in medical practice, is indeed limited due to their instability in monolayer culture and difficulty to collect donor tissue (articular and nasal cartilage). The most recent cartilage engineering approaches combine cells, biomaterial scaffold and bioactive factors to promote functional tissue replacements. Many recent evidences demonstrate that scaffolds providing specific microenvironmental conditions can promote MSCs differentiation toward a functional phenotype. In the present work, the chondrogenic potential of a new Collagen I based 3D scaffold has been assessed in vitro, in combination with human adipose-derived MSCs which possess a higher chondrogenic potential compared to MSCs isolated from other tissues. Our data indicate that the scaffold was able to promote the early stages of chondrogenic commitment and that supplementation of specific soluble factors was able to induce the complete differentiation of MSCs in chondrocytes as demonstrated by the appearance of cartilage distinctive markers (Sox 9, Aggrecan, Matrilin-1, and Collagen II), as well as by the cartilage-specific Alcian Blue staining and by the acquisition of typical cellular morphology. Such evidences suggest that the investigated scaffold formulation could

  20. Regulation of Small RNAs and Corresponding Targets in Nod Factor-Induced Phaseolus vulgaris Root Hair Cells

    PubMed Central

    Formey, Damien; Martín-Rodríguez, José Ángel; Leija, Alfonso; Santana, Olivia; Quinto, Carmen; Cárdenas, Luis; Hernández, Georgina

    2016-01-01

    A genome-wide analysis identified the set of small RNAs (sRNAs) from the agronomical important legume Phaseolus vulgaris (common bean), including novel P. vulgaris-specific microRNAs (miRNAs) potentially important for the regulation of the rhizobia-symbiotic process. Generally, novel miRNAs are difficult to identify and study because they are very lowly expressed in a tissue- or cell-specific manner. In this work, we aimed to analyze sRNAs from common bean root hairs (RH), a single-cell model, induced with pure Rhizobium etli nodulation factors (NF), a unique type of signal molecule. The sequence analysis of samples from NF-induced and control libraries led to the identity of 132 mature miRNAs, including 63 novel miRNAs and 1984 phasiRNAs. From these, six miRNAs were significantly differentially expressed during NF induction, including one novel miRNA: miR-RH82. A parallel degradome analysis of the same samples revealed 29 targets potentially cleaved by novel miRNAs specifically in NF-induced RH samples; however, these novel miRNAs were not differentially accumulated in this tissue. This study reveals Phaseolus vulgaris-specific novel miRNA candidates and their corresponding targets that meet all criteria to be involved in the regulation of the early nodulation events, thus setting the basis for exploring miRNA-mediated improvement of the common bean–rhizobia symbiosis. PMID:27271618

  1. Factor-induced Reprogramming and Zinc Finger Nuclease-aided Gene Targeting Cause Different Genome Instability in β-Thalassemia Induced Pluripotent Stem Cells (iPSCs)*

    PubMed Central

    Ma, Ning; Shan, Yongli; Liao, Baojian; Kong, Guanyi; Wang, Cheng; Huang, Ke; Zhang, Hui; Cai, Xiujuan; Chen, Shubin; Pei, Duanqing; Chen, Nansheng; Pan, Guangjin

    2015-01-01

    The generation of personalized induced pluripotent stem cells (iPSCs) followed by targeted genome editing provides an opportunity for developing customized effective cellular therapies for genetic disorders. However, it is critical to ascertain whether edited iPSCs harbor unfavorable genomic variations before their clinical application. To examine the mutation status of the edited iPSC genome and trace the origin of possible mutations at different steps, we have generated virus-free iPSCs from amniotic cells carrying homozygous point mutations in β-hemoglobin gene (HBB) that cause severe β-thalassemia (β-Thal), corrected the mutations in both HBB alleles by zinc finger nuclease-aided gene targeting, and obtained the final HBB gene-corrected iPSCs by excising the exogenous drug resistance gene with Cre recombinase. Through comparative genomic hybridization and whole-exome sequencing, we uncovered seven copy number variations, five small insertions/deletions, and 64 single nucleotide variations (SNVs) in β-Thal iPSCs before the gene targeting step and found a single small copy number variation, 19 insertions/deletions, and 340 single nucleotide variations in the final gene-corrected β-Thal iPSCs. Our data revealed that substantial but different genomic variations occurred at factor-induced somatic cell reprogramming and zinc finger nuclease-aided gene targeting steps, suggesting that stringent genomic monitoring and selection are needed both at the time of iPSC derivation and after gene targeting. PMID:25795783

  2. Fuel cell and advanced turbine power cycle

    SciTech Connect

    White, D.J.

    1995-10-19

    Solar Turbines, Incorporated (Solar) has a vested interest in the integration of gas turbines and high temperature fuel cells and in particular, solid oxide fuel cells (SOFCs). Solar has identified a parallel path approach to the technology developments needed for future products. The primary approach is to move away from the simple cycle industrial machines of the past and develop as a first step more efficient recuperated engines. This move was prompted by the recognition that the simple cycle machines were rapidly approaching their efficiency limits. Improving the efficiency of simple cycle machines is and will become increasingly more costly. Each efficiency increment will be progressively more costly than the previous step.

  3. Immunochemical properties of antigen-specific monkey T-cell suppressor factor induced with a Streptococcus mutans antigen.

    PubMed Central

    Lamb, J R; Zanders, E D; Kontiainen, S; Lehner, T

    1980-01-01

    Antigen-specific suppressor factor could be released from monkey suppressor T cells induced in vitro with a protein antigen isolated from the carcinogenic bacterium Streptococcus mutans. The suppressor activity was due to the factor itself and not to carryover of free antigen. Characterization of the monkey factor revealed it to have a molecular weight of ca. 70,000, and to contain a constant region and determinants encoded by the major histocompatibility complex. The presence of immunoglobulin determinants could not be demonstrated. However, by virtue of its adsorption to specific antigen, an antigen-combining site was shown to be present. The possible regulatory role of streptococcal antigen-specific suppressor factor in protection against dental caries is discussed. PMID:6164645

  4. Intraocular elevation of cyclic AMP potentiates ciliary neurotrophic factor-induced regeneration of adult rat retinal ganglion cell axons.

    PubMed

    Cui, Qi; Yip, Henry K; Zhao, Robert C H; So, Kwok-Fai; Harvey, Alan R

    2003-01-01

    In vitro, cyclic AMP (cAMP) elevation alters neuronal responsiveness to diffusible growth factors and myelin-associated inhibitory molecules. Here we used an established in vivo model of adult central nervous system injury to investigate the effects of elevated cAMP on neuronal survival and axonal regeneration. We studied the effects of intraocular injections of neurotrophic factors and/or a cAMP analogue (CPT-cAMP) on the regeneration of axotomized rat retinal ganglion cell (RGC) axons into peripheral nerve autografts. Elevation of cAMP alone did not significantly increase RGC survival or the number of regenerating RGCs. Ciliary neurotrophic factor increased RGC viability and axonal regrowth, the latter effect substantially enhanced by coapplication with CPT-cAMP. Under these conditions over 60% of surviving RGCs regenerated their axons. Neurotrophin-4/5 injections also increased RGC viability, but there was reduced long-distance axonal regrowth into grafts, an effect partially ameliorated by cAMP elevation. Thus, cAMP can act cooperatively with appropriate neurotrophic factors to promote axonal regeneration in the injured adult mammalian central nervous system.

  5. Acanthamoeba induces cell-cycle arrest in host cells.

    PubMed

    Sissons, James; Alsam, Selwa; Jayasekera, Samantha; Kim, Kwang Sik; Stins, Monique; Khan, Naveed Ahmed

    2004-08-01

    Acanthamoeba can cause fatal granulomatous amoebic encephalitis (GAE) and eye keratitis. However, the pathogenesis and pathophysiology of these emerging diseases remain unclear. In this study, the effects of Acanthamoeba on the host cell cycle using human brain microvascular endothelial cells (HBMEC) and human corneal epithelial cells (HCEC) were determined. Two isolates of Acanthamoeba belonging to the T1 genotype (GAE isolate) and T4 genotype (keratitis isolate) were used, which showed severe cytotoxicity on HBMEC and HCEC, respectively. No tissue specificity was observed in their ability to exhibit binding to the host cells. To determine the effects of Acanthamoeba on the host cell cycle, a cell-cycle-specific gene array was used. This screened for 96 genes specific for host cell-cycle regulation. It was observed that Acanthamoeba inhibited expression of genes encoding cyclins F and G1 and cyclin-dependent kinase 6, which are proteins important for cell-cycle progression. Moreover, upregulation was observed of the expression of genes such as GADD45A and p130 Rb, associated with cell-cycle arrest, indicating cell-cycle inhibition. Next, the effect of Acanthamoeba on retinoblastoma protein (pRb) phosphorylation was determined. pRb is a potent inhibitor of G1-to-S cell-cycle progression; however, its function is inhibited upon phosphorylation, allowing progression into S phase. Western blotting revealed that Acanthamoeba abolished pRb phosphorylation leading to cell-cycle arrest at the G1-to-S transition. Taken together, these studies demonstrated for the first time that Acanthamoeba inhibits the host cell cycle at the transcriptional level, as well as by modulating pRb phosphorylation using host cell-signalling mechanisms. A complete understanding of Acanthamoeba-host cell interactions may help in developing novel strategies to treat Acanthamoeba infections.

  6. Cycle life test of secondary spacecraft cells

    NASA Technical Reports Server (NTRS)

    Harkness, J. D.

    1980-01-01

    The results of the life cycling program on rechargeable calls are reported. Information on required data, the use of which the data will be put, application details, including orbital description, charge control methods, load rquirements, etc., are given. Cycle tests were performed on 660 sealed, nickel cadmium cells. The cells consisted of seven sample classifications ranging form 3.0 to 20 amp. hours. Nickel cadmium, silver cadmium, and silver zinc sealed cells, excluding synchronous orbit and accelerated test packs were added. The capacities of the nickel cadmium cells, the silver cadmium and the silver zinc cells differed in range of amp hrs. The cells were cylced under different load, charge control, and temperature conditions. All cell packs are recharged by use of a pack voltage limit. All charging is constant current until the voltage limit is reached.

  7. Modeling of Sonos Memory Cell Erase Cycle

    NASA Technical Reports Server (NTRS)

    Phillips, Thomas A.; MacLeond, Todd C.; Ho, Fat D.

    2010-01-01

    Silicon-oxide-nitride-oxide-silicon (SONOS) nonvolatile semiconductor memories (NVSMS) have many advantages. These memories are electrically erasable programmable read-only memories (EEPROMs). They utilize low programming voltages, endure extended erase/write cycles, are inherently resistant to radiation, and are compatible with high-density scaled CMOS for low power, portable electronics. The SONOS memory cell erase cycle was investigated using a nonquasi-static (NQS) MOSFET model. The SONOS floating gate charge and voltage, tunneling current, threshold voltage, and drain current were characterized during an erase cycle. Comparisons were made between the model predictions and experimental device data.

  8. Glial cell line-derived neurotrophic factor induced the differentiation of amniotic fluid-derived stem cells into vascular endothelial-like cells in vitro.

    PubMed

    Zhang, Ruyu; Lu, Ying; Li, Ju; Wang, Jia; Liu, Caixia; Gao, Fang; Sun, Dong

    2016-02-01

    Amniotic fluid-derived stem cells (AFSCs) are a novel source of stem cells that are isolated and cultured from second trimester amniocentesis. Glial cell line-derived neurotrophic factor (GDNF) acts as a tissue morphogen and regulates stem cell proliferation and differentiation. This study investigated the effect of an adenovirus-mediated GDNF gene, which was engineered into AFSCs, on the cells' biological properties and whether GDNF in combination with AFSCs can be directionally differentiated into vascular endothelial-like cells in vitro. AFSCs were isolated and cultured using the plastic adherence method in vitro and identified by the transcription factor Oct-4, which is the primary marker of pluripotent stem cells. AFSCs were efficiently transfected by a GFP-labeled plasmid system of an adenovirus vector carrying the GDNF gene (Ad-GDNF-GFP). Transfected AFSCs stably expressed GDNF. Transfected AFSCs were cultured in endothelial growth medium-2 containing vascular endothelial growth factor. After 1 week, AFSCs were positive for von Willebrand factor (vWF) and CD31, which are markers of endothelial cells, and the recombinant GDNF group was significantly higher than undifferentiated controls and the GFP only group. These results demonstrated that AFSCs differentiated into vascular endothelial-like cells in vitro, and recombinant GDNF promoted differentiation. The differentiation-induced AFSCs may be used as seed cells to provide a new manner of cell and gene therapies for transplantation into the vascular injury site to promote angiogenesis.

  9. Parvovirus infection-induced cell death and cell cycle arrest

    PubMed Central

    Chen, Aaron Yun; Qiu, Jianming

    2011-01-01

    The cytopathic effects induced during parvovirus infection have been widely documented. Parvovirus infection-induced cell death is often directly associated with disease outcomes (e.g., anemia resulting from loss of erythroid progenitors during parvovirus B19 infection). Apoptosis is the major form of cell death induced by parvovirus infection. However, nonapoptotic cell death, namely necrosis, has also been reported during infection of the minute virus of mice, parvovirus H-1 and bovine parvovirus. Recent studies have revealed multiple mechanisms underlying the cell death during parvovirus infection. These mechanisms vary in different parvoviruses, although the large nonstructural protein (NS)1 and the small NS proteins (e.g., the 11 kDa of parvovirus B19), as well as replication of the viral genome, are responsible for causing infection-induced cell death. Cell cycle arrest is also common, and contributes to the cytopathic effects induced during parvovirus infection. While viral NS proteins have been indicated to induce cell cycle arrest, increasing evidence suggests that a cellular DNA damage response triggered by an invading single-stranded parvoviral genome is the major inducer of cell cycle arrest in parvovirus-infected cells. Apparently, in response to infection, cell death and cell cycle arrest of parvovirus-infected cells are beneficial to the viral cell lifecycle (e.g., viral DNA replication and virus egress). In this article, we will discuss recent advances in the understanding of the mechanisms underlying parvovirus infection-induced cell death and cell cycle arrest. PMID:21331319

  10. Cell Cycle Regulators and Cell Death in Immunity

    PubMed Central

    Zebell, Sophia G.; Dong, Xinnian

    2015-01-01

    Summary Various cell death mechanisms are integral to host defense in both plants and mammals. Plant defense against biotrophic pathogens is associated with programmed cell death (PCD) of the infected cell. This effector-triggered PCD is partly analogous to pyroptosis, an inflammatory host cell death process that plays a crucial role in defense against microbial infections in mammals. Plant effector-triggered PCD also shares with mammalian apoptosis the involvement of cell cycle regulators as signaling components. Here we explore the similarities between these different cell death programs as they relate to host defense and their relationship to the cell-cycle. PMID:26468745

  11. SAFT nickel hydrogen cell cycling status

    NASA Technical Reports Server (NTRS)

    Borthomieu, Yannick; Duquesne, Didier

    1994-01-01

    An overview of the NiH2 cell development is given. The NiH2 SAFT system is an electrochemical (single or dual) stack (IPV). The stack is mounted in an hydroformed Inconel 718 vessel operating at high pressure, equipped with 'rabbit ears' ceramic brazed electrical feedthroughs. The cell design is described: positive electrode, negative electrode, and stack configuration. Overviews of low earth orbit and geostationary earth orbit cyclings are provided. DPA results are also provided. The cycling and DPA results demonstrate that SAFT NiH2 is characterized by high reliability and very stable performances.

  12. Control of cell cycle and cell growth by molecular chaperones.

    PubMed

    Aldea, Martí; Garí, Eloi; Colomina, Neus

    2007-11-01

    Cells adapt their size to both intrinsic and extrinsic demands and, among them, those that stem from growth and proliferation rates are crucial for cell size homeostasis. Here we revisit mechanisms that regulate cell cycle and cell growth in budding yeast. Cyclin Cln3, the most upstream activator of Start, is retained at the endoplasmic reticulum in early G(1) and released by specific chaperones in late G(1) to initiate the cell cycle. On one hand, these chaperones are rate-limiting for release of Cln3 and cell cycle entry and, on the other hand, they are required for key biosynthetic processes. We propose a model whereby the competition for specialized chaperones between growth and cycle machineries could gauge biosynthetic rates and set a critical size threshold at Start.

  13. Tumor cell "dead or alive": caspase and survivin regulate cell death, cell cycle and cell survival.

    PubMed

    Suzuki, A; Shiraki, K

    2001-04-01

    Cell death and cell cycle progression are two sides of the same coin, and these two different phenomenons are regulated moderately to maintain the cellular homeostasis. Tumor is one of the disease states produced as a result of the disintegrated regulation and is characterized as cells showing an irreversible progression of cell cycle and a resistance to cell death signaling. Several investigations have been performed for the understanding of cell death or cell cycle, and cell death research has remarkably progressed in these 10 years. Caspase is a nomenclature referring to ICE/CED-3 cysteine proteinase family and plays a central role during cell death. Recently, several investigations raised some possible hypotheses that caspase is also involved in cell cycle regulation. In this issue, therefore, we review the molecular basis of cell death and cell cycle regulated by caspase in tumor, especially hepatocellular carcinoma cells.

  14. Cell cycle regulation of glucocorticoid receptor function.

    PubMed Central

    Hsu, S C; Qi, M; DeFranco, D B

    1992-01-01

    Glucocorticoid receptor (GR) nuclear translocation, transactivation and phosphorylation were examined during the cell cycle in mouse L cell fibroblasts. Glucocorticoid-dependent transactivation of the mouse mammary tumor virus promoter was observed in G0 and S phase synchronized L cells, but not in G2 synchronized cells. G2 effects were selective on the glucocorticoid hormone signal transduction pathway, since glucocorticoid but not heavy metal induction of the endogenous Metallothionein-1 gene was also impaired in G2 synchronized cells. GRs that translocate to the nucleus of G2 synchronized cells in response to dexamethasone treatment were not efficiently retained there and redistributed to the cytoplasmic compartment. In contrast, GRs bound by the glucocorticoid antagonist RU486 were efficiently retained within nuclei of G2 synchronized cells. Inefficient nuclear retention was observed for both dexamethasone- and RU486-bound GRs in L cells that actively progress through G2 following release from an S phase arrest. Finally, site-specific alterations in GR phosphorylation were observed in G2 synchronized cells suggesting that cell cycle regulation of specific protein kinases and phosphatases could influence nuclear retention, recycling and transactivation activity of the GR. Images PMID:1505524

  15. Control points within the cell cycle

    SciTech Connect

    Van't Hof, J.

    1984-01-01

    Evidence of the temporal order of chromosomal DNA replication argues favorably for the view that the cell cycle is controlled by genes acting in sequence whose time of expression is determined by mitosis and the amount of nuclear DNA (2C vs 4C) in the cell. Gl and G2 appear to be carbohydrate dependent in that cells starved of either carbohydrate of phosphate fail to make these transitions. Cells deprived of nitrate, however, fail only at Gl to S transition indicating that the controls that operate in G1 differ from those that operate in G2. 46 references, 5 figures.

  16. Dactylone inhibits epidermal growth factor-induced transformation and phenotype expression of human cancer cells and induces G1-S arrest and apoptosis.

    PubMed

    Fedorov, Sergey N; Shubina, Larisa K; Bode, Ann M; Stonik, Valentin A; Dong, Zigang

    2007-06-15

    The marine natural chamigrane-type sesquiterpenoid, dactylone, is closely related to secondary metabolites of some edible species of red algae. In the present study, the effect of dactylone was tested on the mouse skin epidermal JB6 P+ Cl41 cell line and its stable transfectants as well as on several human tumor cell lines, including lung (H460), colon (HCT-116), and skin melanomas (SK-MEL-5 and SK-MEL-28). This natural product was effective at nontoxic doses as a cancer-preventive agent, which exerted its actions, at least in part, through the inhibition of cyclin D3 and Cdk4 expression and retinoblastoma tumor suppressor protein (Rb) phosphorylation. The inhibition of these cell cycle components was followed by cell cycle arrest at the G1-S transition with subsequent p53-independent apoptosis. Therefore, these data showed that application of dactylone and related compounds may lead to decreased malignant cell transformation and/or decreased tumor cell proliferation.

  17. Somatostatin inhibits stem cell factor messenger RNA expression by Sertoli cells and stem cell factor-induced DNA synthesis in isolated seminiferous tubules.

    PubMed

    Goddard, I; Bauer, S; Gougeon, A; Lopez, F; Giannetti, N; Susini, C; Benahmed, M; Krantic, S

    2001-12-01

    Immature porcine Sertoli cells have been reported to be targets for the regulatory peptide somatostatin (SRIF), which inhibits the basal and FSH-induced proliferation of Sertoli cells through a decrease of cAMP production. In the present study, we show that SRIF inhibits both basal and FSH-stimulated expression of the stem cell factor (SCF), a Sertoli cell-specific gene. The SRIF-mediated inhibition of forskolin-triggered, but not of 8-bromoadenosine-cAMP-triggered, SCF mRNA expression demonstrates the involvement of adenylyl cyclase in underlying peptide actions. Moreover, these effects require functional coupling of specific plasma membrane receptors to adenylyl cyclase via inhibitory G proteins, because pertussis toxin prevents SRIF-mediated inhibition of SCF mRNA expression. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot assays suggest the involvement of sst2 receptors in SRIF actions on Sertoli cells. The biological relevance of these data is supported by an SRIF-mediated decrease in SCF-induced incorporation of [(3)H]thymidine in isolated seminiferous tubules. In situ hybridization and confocal microscopy show that, in seminiferous tubules only, spermatogonia display both c-kit and sst2 receptors. Taken together, these results suggest that SCF-stimulated DNA synthesis can be inhibited by SRIF in spermatogonia, but not in Sertoli and peritubular cells. Combined RT-PCR and immunohistochemical approaches point toward spermatogonia and Leydig cells as the source of testicular SRIF. These data argue in favor of paracrine/autocrine SRIF actions in testis.

  18. Mitochondrial dynamics and the cell cycle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nuclear-mitochondrial (NM) communication impacts many aspects of plant development including vigor, sterility and viability. Dynamic changes in mitochondrial number, shape, size, and cellular location takes place during the cell cycle possibly impacting the process itself and leading to distribution...

  19. Cell Cycle Progression of Human Cells Cultured in Rotating Bioreactor

    NASA Technical Reports Server (NTRS)

    Parks, Kelsey

    2009-01-01

    Space flight has been shown to alter the astronauts immune systems. Because immune performance is complex and reflects the influence of multiple organ systems within the host, scientists sought to understand the potential impact of microgravity alone on the cellular mechanisms critical to immunity. Lymphocytes and their differentiated immature form, lymphoblasts, play an important and integral role in the body's defense system. T cells, one of the three major types of lymphocytes, play a central role in cell-mediated immunity. They can be distinguished from other lymphocyte types, such as B cells and natural killer cells by the presence of a special receptor on their cell surface called T cell receptors. Reported studies have shown that spaceflight can affect the expression of cell surface markers. Cell surface markers play an important role in the ability of cells to interact and to pass signals between different cells of the same phenotype and cells of different phenotypes. Recent evidence suggests that cell-cycle regulators are essential for T-cell function. To trigger an effective immune response, lymphocytes must proliferate. The objective of this project is to investigate the changes in growth of human cells cultured in rotating bioreactors and to measure the growth rate and the cell cycle distribution for different human cell types. Human lymphocytes and lymphoblasts will be cultured in a bioreactor to simulate aspects of microgravity. The bioreactor is a cylindrical culture vessel that incorporates the aspects of clinostatic rotation of a solid fluid body around a horizontal axis at a constant speed, and compensates gravity by rotation and places cells within the fluid body into a sustained free-fall. Cell cycle progression and cell proliferation of the lymphocytes will be measured for a number of days. In addition, RNA from the cells will be isolated for expression of genes related in cell cycle regulations.

  20. FUEL CELL/MICRO-TURBINE COMBINED CYCLE

    SciTech Connect

    Larry J. Chaney; Mike R. Tharp; Tom W. Wolf; Tim A. Fuller; Joe J. Hartvigson

    1999-12-01

    A wide variety of conceptual design studies have been conducted that describe ultra-high efficiency fossil power plant cycles. The most promising of these ultra-high efficiency cycles incorporate high temperature fuel cells with a gas turbine. Combining fuel cells with a gas turbine increases overall cycle efficiency while reducing per kilowatt emissions. This study has demonstrated that the unique approach taken to combining a fuel cell and gas turbine has both technical and economic merit. The approach used in this study eliminates most of the gas turbine integration problems associated with hybrid fuel cell turbine systems. By using a micro-turbine, and a non-pressurized fuel cell the total system size (kW) and complexity has been reduced substantially from those presented in other studies, while maintaining over 70% efficiency. The reduced system size can be particularly attractive in the deregulated electrical generation/distribution environment where the market may not demand multi-megawatt central stations systems. The small size also opens up the niche markets to this high efficiency, low emission electrical generation option.

  1. Cell cycle nucleic acids, polypeptides and uses thereof

    DOEpatents

    Gordon-Kamm, William J.; Lowe, Keith S.; Larkins, Brian A.; Dilkes, Brian R.; Sun, Yuejin

    2007-08-14

    The invention provides isolated nucleic acids and their encoded proteins that are involved in cell cycle regulation. The invention further provides recombinant expression cassettes, host cells, transgenic plants, and antibody compositions. The present invention provides methods and compositions relating to altering cell cycle protein content, cell cycle progression, cell number and/or composition of plants.

  2. Modeling of SONOS Memory Cell Erase Cycle

    NASA Technical Reports Server (NTRS)

    Phillips, Thomas A.; MacLeod, Todd C.; Ho, Fat H.

    2011-01-01

    Utilization of Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) nonvolatile semiconductor memories as a flash memory has many advantages. These electrically erasable programmable read-only memories (EEPROMs) utilize low programming voltages, have a high erase/write cycle lifetime, are radiation hardened, and are compatible with high-density scaled CMOS for low power, portable electronics. In this paper, the SONOS memory cell erase cycle was investigated using a nonquasi-static (NQS) MOSFET model. Comparisons were made between the model predictions and experimental data.

  3. Solid oxide fuel cell combined cycles

    SciTech Connect

    Bevc, F.P.; Lundberg, W.L.; Bachovchin, D.M.

    1996-12-31

    The integration of the solid oxide fuel cell and combustion turbine technologies can result in combined-cycle power plants, fueled with natural gas, that have high efficiencies and clean gaseous emissions. Results of a study are presented in which conceptual designs were developed for 3 power plants based upon such an integration, and ranging in rating from 3 to 10 MW net ac. The plant cycles are described and characteristics of key components summarized. Also, plant design-point efficiency estimates are presented as well as values of other plant performance parameters.

  4. C/EBPα bypasses cell cycle-dependency during immune cell transdifferentiation.

    PubMed

    Di Tullio, Alessandro; Graf, Thomas

    2012-07-15

    Our earlier work has shown that pre-B cells can be converted into macrophage-like cells by overexpression of the transcription factor C/EBPα or C/EBPβ with high efficiency. Using inducible pre-B cell lines, we have now investigated the role of cell division during C/EBP-induced reprogramming. The majority of cells reprogrammed by C/EBPα incorporated BrdU before arresting at G(0), and all C/EBPβ-induced cells incorporated the compound. This contrasts with reports from other systems where transdifferentiating cells essentially do not divide. Although inhibition of DNA synthesis led to an impairment of C/EBPα-induced transdifferentiation, sorted G(0)/G(1) and G(2)/M fractions showed no significant differences in their reprogramming kinetics. In addition, knocking-down p53 did not accelerate the transdifferentiation frequency, as it has been described for reprogramming of induced pluripotent (iPS) cells. Time-lapse experiments showed that, after C/EBPα induction, approximately 90% of cells divide once or twice, while 8% do not divide at all before acquiring a macrophage phenotype, supporting our BrdU incorporation results. Importantly, the non-dividing cell subset expressed the highest levels of C/EBPα and was the fastest in differentiating, suggesting that high levels of C/EBPα accelerate both the switching process and the cells' growth arrest. Our data show that traversing the cell cycle is not strictly required for pre-B cell to macrophage conversion and provides new evidence for the notion that the mechanisms of transcription factor induced transdifferentiation and iPS cell reprogramming differ.

  5. Westinghouse fuel cell combined cycle systems

    SciTech Connect

    Veyo, S.

    1996-12-31

    Efficiency (voltage) of the solid oxide fuel cell (SOFC) should increase with operating pressure, and a pressurized SOFC could function as the heat addition process in a Brayton cycle gas turbine (GT) engine. An overall cycle efficiency of 70% should be possible. In cogeneration, half of the waste heat from a PSOFC/GT should be able to be captured in process steam and hot water, leading to a fuel effectiveness of about 85%. In order to make the PSOFC/GT a commercial reality, satisfactory operation of the SOFC at elevated pressure must be verified, a pressurized SOFC generator module must be designed, built, and tested, and the combined cycle and parameters must be optimized. A prototype must also be demonstrated. This paper describes progress toward making the PSOFC/GT a reality.

  6. Cell cycle regulation of hematopoietic stem or progenitor cells.

    PubMed

    Hao, Sha; Chen, Chen; Cheng, Tao

    2016-05-01

    The highly regulated process of blood production is achieved through the hierarchical organization of hematopoietic stem cell (HSC) subsets and their progenies, which differ in self-renewal and differentiation potential. Genetic studies in mice have demonstrated that cell cycle is tightly controlled by the complex interplay between extrinsic cues and intrinsic regulatory pathways involved in HSC self-renewal and differentiation. Deregulation of these cellular programs may transform HSCs or hematopoietic progenitor cells (HPCs) into disease-initiating stem cells, and can result in hematopoietic malignancies such as leukemia. While previous studies have shown roles for some cell cycle regulators and related signaling pathways in HSCs and HPCs, a more complete picture regarding the molecular mechanisms underlying cell cycle regulation in HSCs or HPCs is lacking. Based on accumulated studies in this field, the present review introduces the basic components of the cell cycle machinery and discusses their major cellular networks that regulate the dormancy and cell cycle progression of HSCs. Knowledge on this topic would help researchers and clinicians to better understand the pathogenesis of relevant blood disorders and to develop new strategies for therapeutic manipulation of HSCs.

  7. Prophylactic pretreatment of mice with hematopoietic growth factors induces expansion of primitive cell compartments and results in protection against 5-fluorouracil-induced toxicity.

    PubMed

    de Haan, G; Donte, B; Engel, C; Loeffler, M; Nijhof, W

    1996-06-01

    The aim of this study was to expand the primitive and committed hematopoietic cell compartments in vivo in order to confer resistance of the blood cell forming system against the cytotoxic, cell cycle specific drug 5-fluorouracil (5-FU). Possible chemoprotective effects of such a pretreatment could result from increased numbers of hematopoietic cells, present before 5-FU administration. In addition, we hypothesized that an enhanced number of primitive and progenitor calls would result in a reduced cycling activity, ie, 5-FU sensitivity, of these same cells, due to normal physiological feedback loops. Administration of stem cell factor (SCF) plus interleukin-11 (IL-11) to mice was shown to result in expansion of the various immature cell compartments in marrow and, in particular, spleen. The total body content of the primitive cobblestone area forming cells (CAFC)-day 28 was increased to 140%, whereas the more committed cells (CAFC-day 7, erythroid and granuloid progenitors) were increased to 500%. This in vivo expansion resulted in a decreased 5-FU sensitivity of the hematopoietic system. In particular, mice that had received 5-FU 24 hours after discontinuation of growth factor pretreatment showed significantly less toxicity of committed cell stages. Compared with mice not pretreated, it appeared that in pretreated mice, 24 hours after 5-FU administration, the absolute number, but also the fraction of surviving CAFC, was much higher in both marrow and spleen. This was caused by a decrease in the cycling activity of all primitive cell subsets. To explore the possible use of this finding in a chemotherapeutic setting, we determined the interval between two subsequent doses of 5-FU (160 mg/kg) that was required to prevent drug-induced mortality. When control mice received a second dose of 5-FU 7, 10, or 14 days after the first, respectively 0%, 20%, and 80% survived. In contrast, 40% and 100% of mice that received SCF + IL-11 before the first dose of 5-FU, survived a

  8. 4D chromatin dynamics in cycling cells

    PubMed Central

    Strickfaden, Hilmar; Zunhammer, Andreas; van Koningsbruggen, Silvana; Köhler, Daniela

    2010-01-01

    This live cell study of chromatin dynamics in four dimensions (space and time) in cycling human cells provides direct evidence for three hypotheses first proposed by Theodor Boveri in seminal studies of fixed blastomeres from Parascaris equorum embryos: (I) Chromosome territory (CT) arrangements are stably maintained during interphase. (II) Chromosome proximity patterns change profoundly during prometaphase. (III) Similar CT proximity patterns in pairs of daughter nuclei reflect symmetrical chromosomal movements during anaphase and telophase, but differ substantially from the arrangement in mother cell nucleus. Hypothesis I could be confirmed for the majority of interphase cells. A minority, however, showed complex, rotational movements of CT assemblies with large-scale changes of CT proximity patterns, while radial nuclear arrangements were maintained. A new model of chromatin dynamics is proposed. It suggests that long-range DNA-DNA interactions in cell nuclei may depend on a combination of rotational CT movements and locally constrained chromatin movements. PMID:21327076

  9. Cell cycle regulation in human embryonic stem cells: links to adaptation to cell culture.

    PubMed

    Barta, Tomas; Dolezalova, Dasa; Holubcova, Zuzana; Hampl, Ales

    2013-03-01

    Cell cycle represents not only a tightly orchestrated mechanism of cell replication and cell division but it also plays an important role in regulation of cell fate decision. Particularly in the context of pluripotent stem cells or multipotent progenitor cells, regulation of cell fate decision is of paramount importance. It has been shown that human embryonic stem cells (hESCs) show unique cell cycle characteristics, such as short doubling time due to abbreviated G1 phase; these properties change with the onset of differentiation. This review summarizes the current understanding of cell cycle regulation in hESCs. We discuss cell cycle properties as well as regulatory machinery governing cell cycle progression of undifferentiated hESCs. Additionally, we provide evidence that long-term culture of hESCs is accompanied by changes in cell cycle properties as well as configuration of several cell cycle regulatory molecules.

  10. A thermodynamic cycle for the solar cell

    NASA Astrophysics Data System (ADS)

    Alicki, Robert; Gelbwaser-Klimovsky, David; Jenkins, Alejandro

    2017-03-01

    A solar cell is a heat engine, but textbook treatments are not wholly satisfactory from a thermodynamic standpoint, since they present solar cells as directly converting the energy of light into electricity, and the current in the circuit as maintained by an electrostatic potential. We propose a thermodynamic cycle in which the gas of electrons in the p phase serves as the working substance. The interface between the p and n phases acts as a self-oscillating piston that modulates the absorption of heat from the photons so that it may perform a net positive work during a complete cycle of its motion, in accordance with the laws of thermodynamics. We draw a simple hydrodynamical analogy between this model and the ;putt-putt; engine of toy boats, in which the interface between the water's liquid and gas phases serves as the piston. We point out some testable consequences of this model.

  11. A metabolic thermodynamic theory of cell cycle

    NASA Astrophysics Data System (ADS)

    Kummer, A.; Ocone, R.

    2003-08-01

    Due to its intrinsic complexity, a complete mathematical description of the cell cycle appears a difficult task. Nevertheless, a preliminary analysis, based on molecular biology, can help in clarifying what are the reliable tools for a quantitative approach. In a previous paper [Physica A 321 (3-4) (2003) 587], the steps to be followed to formulate a metabolic statistical thermodynamics have been established. Here we present a simple mathematical model for the interaction of CyclinB and Cdh1 [The Cell Cycle. An Introduction, Oxford University Press, New York, 1993], with the aim of analysing the properties of the system from a thermodynamic viewpoint. The model is shown to define the Gibbs phase integral of the system and the general Gibbs energy function is obtained. This, together with the analogue of the temperature, defines the working tools indispensable for the formulation of a metabolic statistical thermodynamic-like theory.

  12. The cell cycle as a brake for β-cell regeneration from embryonic stem cells.

    PubMed

    El-Badawy, Ahmed; El-Badri, Nagwa

    2016-01-13

    The generation of insulin-producing β cells from stem cells in vitro provides a promising source of cells for cell transplantation therapy in diabetes. However, insulin-producing cells generated from human stem cells show deficiency in many functional characteristics compared with pancreatic β cells. Recent reports have shown molecular ties between the cell cycle and the differentiation mechanism of embryonic stem (ES) cells, assuming that cell fate decisions are controlled by the cell cycle machinery. Both β cells and ES cells possess unique cell cycle machinery yet with significant contrasts. In this review, we compare the cell cycle control mechanisms in both ES cells and β cells, and highlight the fundamental differences between pluripotent cells of embryonic origin and differentiated β cells. Through critical analysis of the differences of the cell cycle between these two cell types, we propose that the cell cycle of ES cells may act as a brake for β-cell regeneration. Based on these differences, we discuss the potential of modulating the cell cycle of ES cells for the large-scale generation of functionally mature β cells in vitro. Further understanding of the factors that modulate the ES cell cycle will lead to new approaches to enhance the production of functional mature insulin-producing cells, and yield a reliable system to generate bona fide β cells in vitro.

  13. Targeting cell cycle regulators in hematologic malignancies

    PubMed Central

    Aleem, Eiman; Arceci, Robert J.

    2015-01-01

    Hematologic malignancies represent the fourth most frequently diagnosed cancer in economically developed countries. In hematologic malignancies normal hematopoiesis is interrupted by uncontrolled growth of a genetically altered stem or progenitor cell (HSPC) that maintains its ability of self-renewal. Cyclin-dependent kinases (CDKs) not only regulate the mammalian cell cycle, but also influence other vital cellular processes, such as stem cell renewal, differentiation, transcription, epigenetic regulation, apoptosis, and DNA repair. Chromosomal translocations, amplification, overexpression and altered CDK activities have been described in different types of human cancer, which have made them attractive targets for pharmacological inhibition. Mouse models deficient for one or more CDKs have significantly contributed to our current understanding of the physiological functions of CDKs, as well as their roles in human cancer. The present review focuses on selected cell cycle kinases with recent emerging key functions in hematopoiesis and in hematopoietic malignancies, such as CDK6 and its role in MLL-rearranged leukemia and acute lymphocytic leukemia, CDK1 and its regulator WEE-1 in acute myeloid leukemia (AML), and cyclin C/CDK8/CDK19 complexes in T-cell acute lymphocytic leukemia. The knowledge gained from gene knockout experiments in mice of these kinases is also summarized. An overview of compounds targeting these kinases, which are currently in clinical development in various solid tumors and hematopoietic malignances, is presented. These include the CDK4/CDK6 inhibitors (palbociclib, LEE011, LY2835219), pan-CDK inhibitors that target CDK1 (dinaciclib, flavopiridol, AT7519, TG02, P276-00, terampeprocol and RGB 286638) as well as the WEE-1 kinase inhibitor, MK-1775. The advantage of combination therapy of cell cycle inhibitors with conventional chemotherapeutic agents used in the treatment of AML, such as cytarabine, is discussed. PMID:25914884

  14. Ionizing radiation damage to cells: effects of cell cycle redistribution.

    PubMed

    Chen, P L; Brenner, D J; Sachs, R K

    1995-04-01

    If a population of cycling cells is exposed to a fixed dose of ionizing radiation delivered over time T, it is sometimes observed that increasing T increases the amount of cell killing. This is essentially because at first the radiation preferentially kills cells in a sensitive portion of the cycle and the surviving, more resistant cells then have time to reach more sensitive stages. We refer to this effect as population resensitization, caused by redistribution within the cell cycle. We investigate the effect theoretically by employing the McKendrick-von Foerster equation for age-structured proliferating cell populations, generalized by introducing a radiation damage term. Within our formalism, we show that population resensitization occurs whenever: (a) prior to irradiation the cell population has the stable age-distribution approached asymptotically by an unirradiated population, and (b) T is sufficiently small. Examples and other cases are outlined. The methods of Volterra integral equations, renewal theory, and positive semigroup theory are applied. The effect of varying T is evaluated by considering the ultimate amplitude of the stable age-distribution population at times much greater than both the irradiation duration and the average cell-cycle time. The main biological limitations of the formalism are the following: considering only radiation damage which is not subject to enzymatic repair or quadratic misrepair, using an overly naive method of ensuring loss of cell cycle synchrony, neglecting nonlinear effects such as density inhibition of growth, and neglecting radiatively induced perturbations of the cell cycle. Possible methods for removing these limitations are briefly discussed.

  15. Proliferation and cell cycle dynamics in the developing stellate ganglion.

    PubMed

    Gonsalvez, David G; Cane, Kylie N; Landman, Kerry A; Enomoto, Hideki; Young, Heather M; Anderson, Colin R

    2013-04-03

    Cell proliferation during nervous system development is poorly understood outside the mouse neocortex. We measured cell cycle dynamics in the embryonic mouse sympathetic stellate ganglion, where neuroblasts continue to proliferate following neuronal differentiation. At embryonic day (E) 9.5, when neural crest-derived cells were migrating and coalescing into the ganglion primordium, all cells were cycling, cell cycle length was only 10.6 h, and S-phase comprised over 65% of the cell cycle; these values are similar to those previously reported for embryonic stem cells. At E10.5, Sox10(+) cells lengthened their cell cycle to 38 h and reduced the length of S-phase. As cells started to express the neuronal markers Tuj1 and tyrosine hydroxylase (TH) at E10.5, they exited the cell cycle. At E11.5, when >80% of cells in the ganglion were Tuj1(+)/TH(+) neuroblasts, all cells were again cycling. Neuroblast cell cycle length did not change significantly after E11.5, and 98% of Sox10(-)/TH(+) cells had exited the cell cycle by E18.5. The cell cycle length of Sox10(+)/TH(-) cells increased during late embryonic development, and ∼25% were still cycling at E18.5. Loss of Ret increased neuroblast cell cycle length at E16.5 and decreased the number of neuroblasts at E18.5. A mathematical model generated from our data successfully predicted the relative change in proportions of neuroblasts and non-neuroblasts in wild-type mice. Our results show that, like other neurons, sympathetic neuron differentiation is associated with exit from the cell cycle; sympathetic neurons are unusual in that they then re-enter the cell cycle before later permanently exiting.

  16. Cell cycle of globose basal cells in rat olfactory epithelium.

    PubMed

    Huard, J M; Schwob, J E

    1995-05-01

    The olfactory epithelium of adult mammals has the unique property of generating olfactory sensory neurons throughout life. Cells of the basal compartment, which include horizontal and globose basal cells, are responsible for the ongoing process of neurogenesis in this system. We report here that the globose basal cells in olfactory epithelium of rats, as in mice, are the predominant type of proliferating cell, and account for 97.6% of the actively dividing cells in the basal compartment of the normal epithelium. Globose basal cells have not been fully characterized in terms of their proliferative properties, and the dynamic aspects of neurogenesis are not well understood. As a consequence, it is uncertain whether cell kinetic properties are under any regulation that could affect the rate of neurogenesis. To address this gap in our knowledge, we have determined the duration of both the synthesis phase (S-phase) and the full cell cycle of globose basal cells in adult rats. The duration of the S-phase was found to be 9 hr in experiments utilizing sequential injections of either IdU followed by BrdU or 3H-thy followed by BrdU. The duration of the cell cycle was determined by varying the time interval between the injections of 3H-thy and BrdU and tracking the set of cells that exit S shortly after the first injection. With this paradigm, the interval required for these cells to traverse G2, M, G1, and a second S-phase, is equivalent to the duration of one mitotic cycle and equals 17 hr. These observations serve as the foundation to assess whether the cell cycle duration is subject to regulation in response to experimental injury, and whether such regulation is partly responsible for changes in the rate of neurogenesis in such settings.

  17. Mitochondrial Regulation of Cell Cycle and Proliferation

    PubMed Central

    Antico Arciuch, Valeria Gabriela; Elguero, María Eugenia; Poderoso, Juan José

    2012-01-01

    Abstract Eukaryotic mitochondria resulted from symbiotic incorporation of α-proteobacteria into ancient archaea species. During evolution, mitochondria lost most of the prokaryotic bacterial genes and only conserved a small fraction including those encoding 13 proteins of the respiratory chain. In this process, many functions were transferred to the host cells, but mitochondria gained a central role in the regulation of cell proliferation and apoptosis, and in the modulation of metabolism; accordingly, defective organelles contribute to cell transformation and cancer, diabetes, and neurodegenerative diseases. Most cell and transcriptional effects of mitochondria depend on the modulation of respiratory rate and on the production of hydrogen peroxide released into the cytosol. The mitochondrial oxidative rate has to remain depressed for cell proliferation; even in the presence of O2, energy is preferentially obtained from increased glycolysis (Warburg effect). In response to stress signals, traffic of pro- and antiapoptotic mitochondrial proteins in the intermembrane space (B-cell lymphoma-extra large, Bcl-2-associated death promoter, Bcl-2 associated X-protein and cytochrome c) is modulated by the redox condition determined by mitochondrial O2 utilization and mitochondrial nitric oxide metabolism. In this article, we highlight the traffic of the different canonical signaling pathways to mitochondria and the contributions of organelles to redox regulation of kinases. Finally, we analyze the dynamics of the mitochondrial population in cell cycle and apoptosis. Antioxid. Redox Signal. 16, 1150–1180. PMID:21967640

  18. The cell cycle rallies the transcription cycle: Cdc28/Cdk1 is a cell cycle-regulated transcriptional CDK.

    PubMed

    Chymkowitch, Pierre; Enserink, Jorrit M

    2013-01-01

    In the budding yeast Saccharomyces cerevisiae, the cyclin-dependent kinases (CDKs) Kin28, Bur1 and Ctk1 regulate basal transcription by phosphorylating the carboxyl-terminal domain (CTD) of RNA polymerase II. However, very little is known about the involvement of the cell cycle CDK Cdc28 in the transcription process. We have recently shown that, upon cell cycle entry, Cdc28 kinase activity boosts transcription of a subset of genes by directly stimulating the basal transcription machinery. Here, we discuss the biological significance of this finding and give our view of the kinase-dependent role of Cdc28 in regulation of RNA polymerase II.

  19. Ellagitannin-rich cloudberry inhibits hepatocyte growth factor induced cell migration and phosphatidylinositol 3-kinase/AKT activation in colon carcinoma cells and tumors in Min mice

    PubMed Central

    Pajari, Anne-Maria; Päivärinta, Essi; Paavolainen, Lassi; Vaara, Elina; Koivumäki, Tuuli; Garg, Ritu; Heiman-Lindh, Anu; Mutanen, Marja; Marjomäki, Varpu; Ridley, Anne J.

    2016-01-01

    Berries have been found to inhibit colon carcinogenesis in animal models, and thus represent a potential source of compounds for prevention and treatment of colorectal cancer. The mechanistic basis for their effects is not well understood. We used human colon carcinoma cells and Min mice to investigate the effects of ellagitannin-rich cloudberry (Rubus chamaemorus) extract on cancer cell migration and underlying cell signaling. Intrinsic and hepatocyte growth factor (HGF) -induced cell motility in human HT29 and HCA7 colon carcinoma cells was assessed carrying out cell scattering and scratch wound healing assays using time-lapse microscopy. Activation of Met, AKT, and ERK in cell lines and tumors of cloudberry-fed Min mice were determined using immunoprecipitation, Western blot and immunohistochemical analyses. Cloudberry extract significantly inhibited particularly HGF-induced cancer cell migration in both cell lines. Cloudberry extract inhibited the Met receptor tyrosine phosphorylation by HGF and strongly suppressed HGF-induced AKT and ERK activation in both HT29 and HCA7 cells. Consistently, cloudberry feeding (10% w/w freeze-dried berries in diet for 10 weeks) reduced the level of active AKT and prevented phosphoMet localization at the edges in tumors of Min mice. These results indicate that cloudberry reduces tumor growth and cancer cell motility by inhibiting Met signaling and consequent activation of phosphatidylinositol 3-kinase/AKT in vitro and in tumors in vivo. As the Met receptor is recognized to be a major target in cancer treatment, our results suggest that dietary phytochemicals may have therapeutic value in reducing cancer progression and metastasis. PMID:27270323

  20. BAG-1 enhances cell-cell adhesion, reduces proliferation and induces chaperone-independent suppression of hepatocyte growth factor-induced epidermal keratinocyte migration

    SciTech Connect

    Hinitt, C.A.M.; Wood, J.; Lee, S.S.; Williams, A.C.; Howarth, J.L.; Glover, C.P.; Uney, J.B.; Hague, A.

    2010-08-01

    Cell motility is important in maintaining tissue homeostasis, facilitating epithelial wound repair and in tumour formation and progression. The aim of this study was to determine whether BAG-1 isoforms regulate epidermal cell migration in in vitro models of wound healing. In the human epidermal cell line HaCaT, endogenous BAG-1 is primarily nuclear and increases with confluence. Both transient and stable p36-Bag-1 overexpression resulted in increased cellular cohesion. Stable transfection of either of the three human BAG-1 isoforms p36-Bag-1 (BAG-1S), p46-Bag-1 (BAG-1M) and p50-Bag-1 (BAG-1L) inhibited growth and wound closure in serum-containing medium. However, in response to hepatocyte growth factor (HGF) in serum-free medium, BAG-1S/M reduced communal motility and colony scattering, but BAG-1L did not. In the presence of HGF, p36-Bag-1 transfectants retained proliferative response to HGF with no change in ERK1/2 activation. However, the cells retained E-cadherin localisation at cell-cell junctions and exhibited pronounced cortical actin. Point mutations in the BAG domain showed that BAG-1 inhibition of motility is independent of its function as a chaperone regulator. These findings are the first to suggest that BAG-1 plays a role in regulating cell-cell adhesion and suggest an important function in epidermal cohesion.

  1. Pre-B cell colony enhancing factor induces Nampt-dependent translocation of the insulin receptor out of lipid microdomains in A549 lung epithelial cells.

    PubMed

    Peng, Qianyi; Jia, Song Hui; Parodo, Jean; Ai, Yuhang; Marshall, John C

    2015-02-15

    Pre-B cell colony-enhancing factor (PBEF) is a highly conserved pleiotropic protein reported to be an alternate ligand for the insulin receptor (IR). We sought to clarify the relationship between PBEF and insulin signaling by evaluating the effects of PBEF on the localization of the IRβ chain to lipid rafts in A549 epithelial cells. We isolated lipid rafts from A549 cells and detected the IR by immunoprecipitation from raft fractions or whole cell lysates. Cells were treated with rPBEF, its enzymatic product nicotinamide adenine dinucleotide (NAD), or the Nampt inhibitor daporinad to study the effect of PBEF on IRβ movement. We used coimmunoprecipitation studies in cells transfected with PBEF and IRβ constructs to detect interactions between PBEF, the IRβ, and caveolin-1 (Cav-1). PBEF was present in both lipid raft and nonraft fractions, whereas the IR was found only in lipid raft fractions of resting A549 cells. The IR-, PBEF-, and Cav-1-coimmunoprecipitated rPBEF treatment resulted in the movement of IRβ- and tyrosine-phosphorylated Cav-1 from lipid rafts to nonrafts, an effect that could be blocked by daporinad, suggesting that this effect was facilitated by the Nampt activity of PBEF. The addition of PBEF to insulin-treated cells resulted in reduced Akt phosphorylation of both Ser⁴⁷³ and Thr³⁰⁸. We conclude that PBEF can inhibit insulin signaling through the IR by Nampt-dependent promotion of IR translocation into the nonraft domains of A549 epithelial cells. PBEF-induced alterations in the spatial geometry of the IR provide a mechanistic explanation for insulin resistance in inflammatory states associated with upregulation of PBEF.

  2. T Cell Receptor-induced Activation and Apoptosis In Cycling Human T Cells Occur throughout the Cell Cycle

    PubMed Central

    Karas, Michael; Zaks, Tal Z.; JL, Liu; LeRoith, Derek

    1999-01-01

    Previous studies have found conflicting associations between susceptibility to activation-induced cell death and the cell cycle in T cells. However, most of the studies used potentially toxic pharmacological agents for cell cycle synchronization. A panel of human melanoma tumor-reactive T cell lines, a CD8+ HER-2/neu-reactive T cell clone, and the leukemic T cell line Jurkat were separated by centrifugal elutriation. Fractions enriched for the G0–G1, S, and G2–M phases of the cell cycle were assayed for T cell receptor-mediated activation as measured by intracellular Ca2+ flux, cytolytic recognition of tumor targets, and induction of Fas ligand mRNA. Susceptibility to apoptosis induced by recombinant Fas ligand and activation-induced cell death were also studied. None of the parameters studied was specific to a certain phase of the cell cycle, leading us to conclude that in nontransformed human T cells, both activation and apoptosis through T cell receptor activation can occur in all phases of the cell cycle. PMID:10588669

  3. The cell-cycle state of stem cells determines cell fate propensity.

    PubMed

    Pauklin, Siim; Vallier, Ludovic

    2013-09-26

    Self-renewal and differentiation of stem cells are fundamentally associated with cell-cycle progression to enable tissue specification, organ homeostasis, and potentially tumorigenesis. However, technical challenges have impaired the study of the molecular interactions coordinating cell fate choice and cell-cycle progression. Here, we bypass these limitations by using the FUCCI reporter system in human pluripotent stem cells and show that their capacity of differentiation varies during the progression of their cell cycle. These mechanisms are governed by the cell-cycle regulators cyclin D1-3 that control differentiation signals such as the TGF-β-Smad2/3 pathway. Conversely, cell-cycle manipulation using a small molecule directs differentiation of hPSCs and provides an approach to generate cell types with a clinical interest. Our results demonstrate that cell fate decisions are tightly associated with the cell-cycle machinery and reveal insights in the mechanisms synchronizing differentiation and proliferation in developing tissues.

  4. Fungal Cell Cycle: A Unicellular versus Multicellular Comparison.

    PubMed

    Dörter, Ilkay; Momany, Michelle

    2016-12-01

    All cells must accurately replicate DNA and partition it to daughter cells. The basic cell cycle machinery is highly conserved among eukaryotes. Most of the mechanisms that control the cell cycle were worked out in fungal cells, taking advantage of their powerful genetics and rapid duplication times. Here we describe the cell cycles of the unicellular budding yeast Saccharomyces cerevisiae and the multicellular filamentous fungus Aspergillus nidulans. We compare and contrast morphological landmarks of G1, S, G2, and M phases, molecular mechanisms that drive cell cycle progression, and checkpoints in these model unicellular and multicellular fungal systems.

  5. Hypoxia-inducible factor 1 alpha mediates epidermal growth factor-induced down-regulation of E-cadherin expression and cell invasion in human ovarian cancer cells.

    PubMed

    Cheng, Jung-Chien; Klausen, Christian; Leung, Peter C K

    2013-02-28

    Hypoxia-inducible factor 1α (HIF-1α) regulates the transcription of a number of genes under hypoxia and other extracellular stimulations. It has been shown that E-cadherin is down-regulated by epidermal growth factor receptor (EGF) stimulation, and that cells with low E-cadherin expression are more invasive. Our recent study demonstrated a novel mechanism by which EGF down-regulates E-cadherin expression through production of hydrogen peroxide (H(2)O(2)) and the activation of p38 MAPK in human ovarian cancer cells. In this study, we were interested in examining the potential role of HIF-1α in cell invasion under normoxic conditions, specifically when cells are treated with EGF, which is known to down-regulate E-cadherin and increase invasiveness. We show that EGF treatment induces HIF-1α expression in two human ovarian cancer cell lines (SKOV3 and OVCAR5), and that this effect is diminished by treatment with a membrane-permeable H(2)O(2) scavenger, PEG-catalase. However, the induction of HIF-1α by EGF did not require the activation of p38 MAPK. Treatment with siRNA targeting HIF-1α reduces both basal and EGF-induced HIF-1α levels. Importantly, treatment with HIF-1α siRNA diminishes the up-regulation of Snail and Slug as well as the down-regulation of E-cadherin by EGF. The involvement of HIF-1α in the down-regulation of E-cadherin was confirmed with cobalt chloride (CoCl(2)), a hypoxia-mimetic reagent. Finally, we also show that EGF-induced cell invasion is attenuated by treatment with HIF-1α siRNA. This study demonstrates an important role for HIF-1α in mediating the effects of EGF on Snail, Slug and E-cadherin expression as well as invasiveness in human ovarian cancer cells.

  6. Alteration of cell cycle progression by Sindbis virus infection

    SciTech Connect

    Yi, Ruirong; Saito, Kengo; Isegawa, Naohisa; Shirasawa, Hiroshi

    2015-07-10

    We examined the impact of Sindbis virus (SINV) infection on cell cycle progression in a cancer cell line, HeLa, and a non-cancerous cell line, Vero. Cell cycle analyses showed that SINV infection is able to alter the cell cycle progression in both HeLa and Vero cells, but differently, especially during the early stage of infection. SINV infection affected the expression of several cell cycle regulators (CDK4, CDK6, cyclin E, p21, cyclin A and cyclin B) in HeLa cells and caused HeLa cells to accumulate in S phase during the early stage of infection. Monitoring SINV replication in HeLa and Vero cells expressing cell cycle indicators revealed that SINV which infected HeLa cells during G{sub 1} phase preferred to proliferate during S/G{sub 2} phase, and the average time interval for viral replication was significantly shorter in both HeLa and Vero cells infected during G{sub 1} phase than in cells infected during S/G{sub 2} phase. - Highlights: • SINV infection was able to alter the cell cycle progression of infected cancer cells. • SINV infection can affect the expression of cell cycle regulators. • SINV infection exhibited a preference for the timing of viral replication among the cell cycle phases.

  7. Metabolism, cell growth and the bacterial cell cycle

    PubMed Central

    Wang, Jue D.; Levin, Petra A.

    2010-01-01

    Adaptation to fluctuations in nutrient availability is a fact of life for single-celled organisms in the ‘wild’. A decade ago our understanding of how bacteria adjust cell cycle parameters to accommodate changes in nutrient availability stemmed almost entirely from elegant physiological studies completed in the 1960s. In this Opinion article we summarize recent groundbreaking work in this area and discuss potential mechanisms by which nutrient availability and metabolic status are coordinated with cell growth, chromosome replication and cell division. PMID:19806155

  8. Capacity fade of Sony 18650 cells cycled at elevated temperatures. Part I. Cycling performance

    NASA Astrophysics Data System (ADS)

    Ramadass, P.; Haran, Bala; White, Ralph; Popov, Branko N.

    The capacity fade of Sony 18650 Li-ion cells increases with increase in temperature. After 800 cycles, the cells cycled at RT and 45 °C showed a capacity fade of 30 and 36%, respectively. The cell cycled at 55 °C showed a capacity loss of about 70% after 490 cycles. The rate capability of the cells continues to decrease with cycling. Impedance measurements showed an overall increase in the cell resistance with cycling and temperature. Impedance studies of the electrode materials showed an increased positive electrode resistance when compared to that of the negative electrode for cells cycled at RT and 45 °C. However, cells cycled at 50 and 55 °C exhibit higher negative electrode resistance. The increased capacity fade for the cells cycled at high temperatures can be explained by taking into account the repeated film formation over the surface of anode, which results in increased rate of lithium loss and also in a drastic increase in the negative electrode resistance with cycling.

  9. Cell cycle dysregulation in pituitary oncogenesis.

    PubMed

    Muşat, Madalina; Vax, Vladimir V; Borboli, Ninetta; Gueorguiev, Maria; Bonner, Sarah; Korbonits, Márta; Grossman, Ashley B

    2004-01-01

    The cell cycle is the process by which cells grow, replicate their genome and divide. The cell cycle control system is a cyclically-operating biochemical device constructed from a set of interacting proteins that induce and coordinate proper progression through the cycle, and includes cyclins, cyclin-dependent kinases (CDK) and their inhibitors (CDKI). There are mainly two families of CDKI, the INK family (INK4a/p16; INK4b/p15; INK4c/p18 and INK4d/p19) and the WAF/KIP family (WAF1/p21; KIP1/p27; KIP2/p57). Progression through the cell cycle is mainly dependent on fluctuations in the concentration of cyclins and CDKI achieved through the programmed degradation of these proteins by proteolysis within the ubiquitin-proteasome system. There is also a transcriptional regulation of cyclin expression, probably dependent on CDK phosphorylation. The p53 family--p53, p63 and p73--function as transcription factors that play a major role in regulating the response of mammalian cells to stressors and damage, in part through the transcriptional activation of genes involved in cell cycle control (e.g. p21), DNA repair, senescence, angiogenesis and apoptosis. Essential for the maintenance of euploidy during mitosis is human securin, identical to the product of the pituitary tumour-transforming gene (PTTG). Loss of regulation at the G1/S transition appears to be a common event among virtually all types of human tumours. Aberrations of one or more components of the pRb/p16/cyclin D1/CDK4 pathway seem to be a frequent event (80%) in pituitary tumours. The role of p27 is rather that of a haploinsufficient gene. p27-/- mice show an increased growth rate, due to increased cellularity, testicular and ovarian cell hyperplasia and infertility, and hyperplasia of the pituitary intermediate lobe with nearly 100% mortality caused by such a benign pituitary tumour. Although the p27 gene was not found to be mutated in human pituitary tumours and its mRNA expression was similar in tumour samples

  10. The regulatory effect of SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-l] benzenesulfonamide) on stem cell factor induced migration of mast cells

    SciTech Connect

    Kim, Su-Jin; Jeong, Hyun-Ja; Park, Rae-Kil; Lee, Kang-Min; Kim, Hyung-Min; Um, Jae-Young; Hong, Seung-Heon . E-mail: jooklim@wonkwang.ac.kr

    2007-04-15

    SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-]benzenesulfonamide; C{sub 16}H{sub 11}ClF{sub 3}N{sub 3}O{sub 2}S), is a highly selective cyclooxygenase (COX)-2 inhibitor. Recently, there have been reports that SC-236 protects against cartilage damage in addition to reducing inflammation and pain in osteoarthritis. However, the mechanism involved in the inflammatory allergic reaction has not been examined. Mast cells accumulation can be related to inflammatory conditions, including allergic rhinitis, asthma, and rheumatoid arthritis. The aim of the present study is to investigate the effects of SC-236 on stem cell factor (SCF)-induced migration, morphological alteration, and cytokine production of rat peritoneal mast cells (RPMCs). We observed that SCF significantly induced the migration and morphological alteration. The ability of SCF to enhance migration and morphological alteration was abolished by treatment with SC-236. In addition, production of tumor necrosis factor (TNF)-{alpha}, interleukin (IL)-1{beta}, and vascular endothelial growth factor (VEGF) production induced by SCF was significantly inhibited by treatment with SC-236. Previous work has demonstrated that SCF-induced migration and cytokine production of mast cells require p38 MAPK activation. We also showed that SC-236 suppresses the SCF-induced p38 MAPK activation in RPMCs. These data suggest that SC-236 inhibits migration and cytokine production through suppression of p38 MAPK activation. These results provided new insight into the pharmacological actions of SC-236 and its potential therapeutic role in the treatment of inflammatory allergic diseases.

  11. Analysis of Cell Cycle Switches in Drosophila Oogenesis.

    PubMed

    Jia, Dongyu; Huang, Yi-Chun; Deng, Wu-Min

    2015-01-01

    The study of Drosophila oogenesis provides invaluable information about signaling pathway regulation and cell cycle programming. During Drosophila oogenesis, a string of egg chambers in each ovariole progressively develops toward maturity. Egg chamber development consists of 14 stages. From stage 1 to stage 6 (mitotic cycle), main-body follicle cells undergo mitotic divisions. From stage 7 to stage 10a (endocycle), follicle cells cease mitosis but continue three rounds of endoreduplication. From stage 10b to stage 13 (gene amplification), instead of whole genome duplication, follicle cells selectively amplify specific genomic regions, mostly for chorion production. So far, Drosophila oogenesis is one of the most well studied model systems used to understand cell cycle switches, which furthers our knowledge about cell cycle control machinery and sheds new light on potential cancer treatments. Here, we give a brief summary of cell cycle switches, the associated signaling pathways and factors, and the detailed experimental procedures used to study the cell cycle switches.

  12. FGF1-mediated cardiomyocyte cell cycle reentry depends on the interaction of FGFR-1 and Fn14.

    PubMed

    Novoyatleva, Tatyana; Sajjad, Amna; Pogoryelov, Denys; Patra, Chinmoy; Schermuly, Ralph T; Engel, Felix B

    2014-06-01

    Fibroblast growth factors (FGFs) signal through FGF receptors (FGFRs) mediating a broad range of cellular functions during embryonic development, as well as disease and regeneration during adulthood. Thus, it is important to understand the underlying molecular mechanisms that modulate this system. Here, we show that FGFR-1 can interact with the TNF receptor superfamily member fibroblast growth factor-inducible molecule 14 (Fn14) resulting in cardiomyocyte cell cycle reentry. FGF1-induced cell cycle reentry in neonatal cardiomyocytes could be blocked by Fn14 inhibition, while TWEAK-induced cell cycle activation was inhibited by blocking FGFR-1 signaling. In addition, costimulation experiments revealed a synergistic effect of FGF1 and TWEAK in regard to cardiomyocyte cell cycle induction via PI3K/Akt signaling. Overexpression of Fn14 with either FGFR-1 long [FGFR-1(L)] or FGFR-1 short [FGFR-1(S)] isoforms resulted after FGF1/TWEAK stimulation in cell cycle reentry of >40% adult cardiomyocytes. Finally, coimmunoprecipitation and proximity ligation assays indicated that endogenous FGFR-1 and Fn14 interact with each other in cardiomyocytes. This interaction was strongly enhanced in the presence of their corresponding ligands, FGF1 and TWEAK. Taken together, our data suggest that FGFR-1/Fn14 interaction may represent a novel endogenous mechanism to modulate the action of these receptors and their ligands and to control cardiomyocyte cell cycle reentry.

  13. Differential Sulfation Remodelling of Heparan Sulfate by Extracellular 6-O-sulfatases Regulates Fibroblast Growth Factor-induced Boundary Formation By Glial Cells: Implications for Glial Cell Transplantation

    PubMed Central

    Higginson, Jennifer R; Thompson, Sophie M; Santos-Silva, Alessandra; Guimond, Scott E; Turnbull, Jeremy E; Barnett, Susan C

    2012-01-01

    Previously, it has been shown that rat Schwann cells (SCs), but not olfactory ensheathing cells (OECs), form a boundary with astrocytes, due to a SC-specific secreted factor. Here, we identify highly sulfated heparan sulfates (HS), and fibroblast growth factors (FGF) 1 and FGF9, as possible determinants of boundary formation induced by rat SCs. Disaccharide analysis of HS in SC and rat OEC conditioned medium showed that SCs secrete more highly sulfated HS than OECs. The dependence of the boundary-forming activity on high levels of sulfation was confirmed using a panel of semi-synthetic modified heparins with variable levels of sulfation. Furthermore, extracellular HS 6-O-endosulfatase enzymes, Sulf 1 and Sulf 2, were expressed at a significantly lower level by SCs compared to OECs and siRNA reduction of Sulfs in OECs was, in itself, sufficient to induce boundary formation. This demonstrates a key role for remodelling (reduction) of HS 6-O-sulfation by OECs to suppress boundary formation, in comparison to SCs. Furthermore, specific anti-FGF1 and FGF9 antibodies disrupted SC/astrocyte boundary formation, supporting a role for an HS sulfation-dependent FGF signalling mechanism via FGF receptors (FGFR) on astrocytes. We propose a model in which FGF1 and FGF9 signalling is differentially modulated by patterns of glial cell HS sulfation, dependent on Sulf 1 and Sulf 2 expression, to control FGFR3-IIIb mediated astrocytic responses. Moreover, these data suggest manipulation of HS sulfation after CNS injury as a potential novel approach for therapeutic intervention in CNS repair. PMID:23136428

  14. Differential sulfation remodelling of heparan sulfate by extracellular 6-O-sulfatases regulates fibroblast growth factor-induced boundary formation by glial cells: implications for glial cell transplantation.

    PubMed

    Higginson, Jennifer R; Thompson, Sophie M; Santos-Silva, Alessandra; Guimond, Scott E; Turnbull, Jeremy E; Barnett, Susan C

    2012-11-07

    Previously, it has been shown that rat Schwann cells (SCs), but not olfactory ensheathing cells (OECs), form a boundary with astrocytes, due to a SC-specific secreted factor. Here, we identify highly sulfated heparan sulfates (HSs) and fibroblast growth factors (FGFs) 1 and 9 as possible determinants of boundary formation induced by rat SCs. Disaccharide analysis of HS in SC-conditioned and rat OEC-conditioned media showed that SCs secrete more highly sulfated HS than OECs. The dependence of the boundary-forming activity on high levels of sulfation was confirmed using a panel of semisynthetic modified heparins with variable levels of sulfation. Furthermore, extracellular HS 6-O-endosulfatase enzymes, Sulf 1 and Sulf 2, were expressed at a significantly lower level by SCs compared with OECs, and siRNA reduction of Sulfs in OECs was, in itself, sufficient to induce boundary formation. This demonstrates a key role for remodelling (reduction) of HS 6-O-sulfation by OECs, compared with SCs, to suppress boundary formation. Furthermore, specific anti-FGF1 and anti-FGF9 antibodies disrupted SC-astrocyte boundary formation, supporting a role for an HS sulfation-dependent FGF signaling mechanism via FGF receptors on astrocytes. We propose a model in which FGF1 and FGF9 signaling is differentially modulated by patterns of glial cell HS sulfation, dependent on Sulf 1 and Sulf 2 expression, to control FGF receptor 3-IIIb-mediated astrocytic responses. Moreover, these data suggest manipulation of HS sulfation after CNS injury as a potential novel approach for therapeutic intervention in CNS repair.

  15. Classic "broken cell" techniques and newer live cell methods for cell cycle assessment.

    PubMed

    Henderson, Lindsay; Bortone, Dante S; Lim, Curtis; Zambon, Alexander C

    2013-05-15

    Many common, important diseases are either caused or exacerbated by hyperactivation (e.g., cancer) or inactivation (e.g., heart failure) of the cell division cycle. A better understanding of the cell cycle is critical for interpreting numerous types of physiological changes in cells. Moreover, new insights into how to control it will facilitate new therapeutics for a variety of diseases and new avenues in regenerative medicine. The progression of cells through the four main phases of their division cycle [G(0)/G(1), S (DNA synthesis), G(2), and M (mitosis)] is a highly conserved process orchestrated by several pathways (e.g., transcription, phosphorylation, nuclear import/export, and protein ubiquitination) that coordinate a core cell cycle pathway. This core pathway can also receive inputs that are cell type and cell niche dependent. "Broken cell" methods (e.g., use of labeled nucleotide analogs) to assess for cell cycle activity have revealed important insights regarding the cell cycle but lack the ability to assess living cells in real time (longitudinal studies) and with single-cell resolution. Moreover, such methods often require cell synchronization, which can perturb the pathway under study. Live cell cycle sensors can be used at single-cell resolution in living cells, intact tissue, and whole animals. Use of these more recently available sensors has the potential to reveal physiologically relevant insights regarding the normal and perturbed cell division cycle.

  16. Local circadian clock gates cell cycle progression of transient amplifying cells during regenerative hair cycling

    PubMed Central

    Plikus, Maksim V.; Vollmers, Christopher; de la Cruz, Damon; Chaix, Amandine; Ramos, Raul; Panda, Satchidananda; Chuong, Cheng-Ming

    2013-01-01

    Regenerative cycling of hair follicles offers an unique opportunity to explore the role of circadian clock in physiological tissue regeneration. We focused on the role of circadian clock in actively proliferating transient amplifying cells, as opposed to quiescent stem cells. We identified two key sites of peripheral circadian clock activity specific to regenerating anagen hair follicles, namely epithelial matrix and mesenchymal dermal papilla. We showed that peripheral circadian clock in epithelial matrix cells generates prominent daily mitotic rhythm. As a consequence of this mitotic rhythmicity, hairs grow faster in the morning than in the evening. Because cells are the most susceptible to DNA damage during mitosis, this cycle leads to a remarkable time-of-day–dependent sensitivity of growing hair follicles to genotoxic stress. Same doses of γ-radiation caused dramatic hair loss in wild-type mice when administered in the morning, during mitotic peak, compared with the evening, when hair loss is minimal. This diurnal radioprotective effect becomes lost in circadian mutants, consistent with asynchronous mitoses in their hair follicles. Clock coordinates cell cycle progression with genotoxic stress responses by synchronizing Cdc2/Cyclin B-mediated G2/M checkpoint. Our results uncover diurnal mitotic gating as the essential protective mechanism in highly proliferative hair follicles and offer strategies for minimizing or maximizing cytotoxicity of radiation therapies. PMID:23690597

  17. The Cell Cycle Switch Computes Approximate Majority

    NASA Astrophysics Data System (ADS)

    Cardelli, Luca; Csikász-Nagy, Attila

    2012-09-01

    Both computational and biological systems have to make decisions about switching from one state to another. The `Approximate Majority' computational algorithm provides the asymptotically fastest way to reach a common decision by all members of a population between two possible outcomes, where the decision approximately matches the initial relative majority. The network that regulates the mitotic entry of the cell-cycle in eukaryotes also makes a decision before it induces early mitotic processes. Here we show that the switch from inactive to active forms of the mitosis promoting Cyclin Dependent Kinases is driven by a system that is related to both the structure and the dynamics of the Approximate Majority computation. We investigate the behavior of these two switches by deterministic, stochastic and probabilistic methods and show that the steady states and temporal dynamics of the two systems are similar and they are exchangeable as components of oscillatory networks.

  18. Cell Cycle and Cell Size Dependent Gene Expression Reveals Distinct Subpopulations at Single-Cell Level

    PubMed Central

    Dolatabadi, Soheila; Candia, Julián; Akrap, Nina; Vannas, Christoffer; Tesan Tomic, Tajana; Losert, Wolfgang; Landberg, Göran; Åman, Pierre; Ståhlberg, Anders

    2017-01-01

    Cell proliferation includes a series of events that is tightly regulated by several checkpoints and layers of control mechanisms. Most studies have been performed on large cell populations, but detailed understanding of cell dynamics and heterogeneity requires single-cell analysis. Here, we used quantitative real-time PCR, profiling the expression of 93 genes in single-cells from three different cell lines. Individual unsynchronized cells from three different cell lines were collected in different cell cycle phases (G0/G1 – S – G2/M) with variable cell sizes. We found that the total transcript level per cell and the expression of most individual genes correlated with progression through the cell cycle, but not with cell size. By applying the random forests algorithm, a supervised machine learning approach, we show how a multi-gene signature that classifies individual cells into their correct cell cycle phase and cell size can be generated. To identify the most predictive genes we used a variable selection strategy. Detailed analysis of cell cycle predictive genes allowed us to define subpopulations with distinct gene expression profiles and to calculate a cell cycle index that illustrates the transition of cells between cell cycle phases. In conclusion, we provide useful experimental approaches and bioinformatics to identify informative and predictive genes at the single-cell level, which opens up new means to describe and understand cell proliferation and subpopulation dynamics. PMID:28179914

  19. SUMOylation-mediated regulation of cell cycle progression and cancer

    PubMed Central

    Eifler, Karolin; Vertegaal, Alfred C.O.

    2016-01-01

    SUMOylation plays critical roles during cell cycle progression. Many important cell cycle regulators, including many oncogenes and tumor suppressors, are functionally regulated via SUMOylation. The dynamic SUMOylation pattern observed throughout the cell cycle is ensured via distinct spatial and temporal regulation of the SUMO machinery. Additionally, SUMOylation cooperates with other post-translational modifications to mediate cell cycle progression. Deregulation of these SUMOylation and deSUMOylation enzymes causes severe defects in cell proliferation and genome stability. Different types of cancers were recently shown to be dependent on a functioning SUMOylation system, a finding that could potentially be exploited in anti-cancer therapies. PMID:26601932

  20. Indirect-fired gas turbine dual fuel cell power cycle

    DOEpatents

    Micheli, Paul L.; Williams, Mark C.; Sudhoff, Frederick A.

    1996-01-01

    A fuel cell and gas turbine combined cycle system which includes dual fuel cell cycles combined with a gas turbine cycle wherein a solid oxide fuel cell cycle operated at a pressure of between 6 to 15 atms tops the turbine cycle and is used to produce CO.sub.2 for a molten carbonate fuel cell cycle which bottoms the turbine and is operated at essentially atmospheric pressure. A high pressure combustor is used to combust the excess fuel from the topping fuel cell cycle to further heat the pressurized gas driving the turbine. A low pressure combustor is used to combust the excess fuel from the bottoming fuel cell to reheat the gas stream passing out of the turbine which is used to preheat the pressurized air stream entering the topping fuel cell before passing into the bottoming fuel cell cathode. The CO.sub.2 generated in the solid oxide fuel cell cycle cascades through the system to the molten carbonate fuel cell cycle cathode.

  1. Glyphosate-based pesticides affect cell cycle regulation.

    PubMed

    Marc, Julie; Mulner-Lorillon, Odile; Bellé, Robert

    2004-04-01

    Cell-cycle dysregulation is a hallmark of tumor cells and human cancers. Failure in the cell-cycle checkpoints leads to genomic instability and subsequent development of cancers from the initial affected cell. A worldwide used product Roundup 3plus, based on glyphosate as the active herbicide, was suggested to be of human health concern since it induced cell cycle dysfunction as judged from analysis of the first cell division of sea urchin embryos, a recognized model for cell cycle studies. Several glyphosate-based pesticides from different manufacturers were assayed in comparison with Roundup 3plus for their ability to interfere with the cell cycle regulation. All the tested products, Amega, Cargly, Cosmic, and Roundup Biovert induced cell cycle dysfunction. The threshold concentration for induction of cell cycle dysfunction was evaluated for each product and suggests high risk by inhalation for people in the vicinity of the pesticide handling sprayed at 500 to 4000 times higher dose than the cell-cycle adverse concentration.

  2. Basal p21 controls population heterogeneity in cycling and quiescent cell cycle states

    PubMed Central

    Overton, K. Wesley; Spencer, Sabrina L.; Noderer, William L.; Meyer, Tobias; Wang, Clifford L.

    2014-01-01

    Phenotypic heterogeneity within a population of genetically identical cells is emerging as a common theme in multiple biological systems, including human cell biology and cancer. Using live-cell imaging, flow cytometry, and kinetic modeling, we showed that two states—quiescence and cell cycling—can coexist within an isogenic population of human cells and resulted from low basal expression levels of p21, a Cyclin-dependent kinase (CDK) inhibitor (CKI). We attribute the p21-dependent heterogeneity in cell cycle activity to double-negative feedback regulation involving CDK2, p21, and E3 ubiquitin ligases. In support of this mechanism, analysis of cells at a point before cell cycle entry (i.e., before the G1/S transition) revealed a p21–CDK2 axis that determines quiescent and cycling cell states. Our findings suggest a mechanistic role for p21 in generating heterogeneity in both normal tissues and tumors. PMID:25267623

  3. Flow cytometry analysis of cell cycle and specific cell synchronization with butyrate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Synchronized cells have been invaluable in many kinds of cell cycle and cell proliferation studies. Butyrate induces cell cycle arrest and apoptosis in MDBK cells. The possibility of using butyrate-blocked cells to obtain synchronized cells was explored and the properties of butyrate-induced cell ...

  4. From the cell cycle to population cycles in phytoplankton-nutrient interactions

    SciTech Connect

    Pascual, M.; Caswell, H.

    1997-04-01

    The internal demographic structure of a population influences its dynamics and its response to the environment. Most models for phytoplankton ignore internal structure and group all cells in a single variable such as total biomass or density. However, a cell does have a life history, the cell division cycle. We investigate the significance of the cell cycle to phytoplankton population dynamics in a variable nutrient environment, using chemostate models. Following the transition point hypothesis, nutrient uptake affects cell development only within a limited segment of the cell cycle. Simulation results demonstrate oscillations in cell numbers and population structure generated by this interaction. When nutrient input is varied periodically, the population displays an aperiodic response with frequencies different from that of the forcing. These results also hold for a model that includes nutrient storage by the cells. These dynamics differ from those of traditional chemostate models and from cell cycle models driven by light cycles. Resource control of cell cycle progression may explain the time delays previously postulated to explain oscillatory transients in chemostate experiments. 78 refs., 22 figs.

  5. Cell cycle controls stress response and longevity in C. elegans

    PubMed Central

    Dottermusch, Matthias; Lakner, Theresa; Peyman, Tobias; Klein, Marinella; Walz, Gerd; Neumann-Haefelin, Elke

    2016-01-01

    Recent studies have revealed a variety of genes and mechanisms that influence the rate of aging progression. In this study, we identified cell cycle factors as potent regulators of health and longevity in C. elegans. Focusing on the cyclin-dependent kinase 2 (cdk-2) and cyclin E (cye-1), we show that inhibition of cell cycle genes leads to tolerance towards environmental stress and longevity. The reproductive system is known as a key regulator of longevity in C. elegans. We uncovered the gonad as the central organ mediating the effects of cell cycle inhibition on lifespan. In particular, the proliferating germ cells were essential for conferring longevity. Steroid hormone signaling and the FOXO transcription factor DAF-16 were required for longevity associated with cell cycle inhibition. Furthermore, we discovered that SKN-1 (ortholog of mammalian Nrf proteins) activates protective gene expression and induces longevity when cell cycle genes are inactivated. We conclude that both, germline absence and inhibition through impairment of cell cycle machinery results in longevity through similar pathways. In addition, our studies suggest further roles of cell cycle genes beyond cell cycle progression and support the recently described connection of SKN-1/Nrf to signals deriving from the germline. PMID:27668945

  6. The molecular basis of carcinogenesis: understanding the cell cycle clock.

    PubMed

    Weinberg, R A

    1996-06-01

    The cell cycle clock is the central controller of cell proliferation that governs the progress of the cell through its growth cycle, its exit from the active cycle, and its decision to differentiate. Components of the clock are found to be functioning in an aberrant fashion in many types of malignancies. Notable among these is the retinoblastoma protein, pRB, which acts to restrain proliferation in normal cells and suffers inactivation in many types of tumour cells. Its activity is controlled by D-type cyclins in various cell types. We have deleted one of these cyclins--cyclin D1--from the mouse germline and find that its absence leads to a limited range of defects including hypoplastic retinae and the inability of the mammary epithelium to respond to pregnancy-associated hormonal stimulation. Cyclin D1 is overexpressed in many human breast cancers, pointing to a highly specific association of this cell cycle clock component with mammary cell proliferation.

  7. Cell cycle analysis by flow cytometry: principles and applications.

    PubMed

    Jayat, C; Ratinaud, M H

    1993-01-01

    Numerous flow cytometric analyses are based on DNA content studies. We have considered firstly monoparametric cell cycle analyses, which only take DNA content into account, but are sometimes of limited interest. Then, we have presented multiparametric analyses, which can be used to improve cycle phase identification by taking simultaneously into account DNA and other cellular components, or by considering some events occurring during cell cycle. Finally, we have discussed monoparametric and multiparametric cell cycle analysis interest in various application fields, particularly in pharmacology, toxicology, tumoral pathology and higher plant system studies.

  8. Cell shape, cytoskeletal mechanics, and cell cycle control in angiogenesis

    NASA Technical Reports Server (NTRS)

    Ingber, D. E.; Prusty, D.; Sun, Z.; Betensky, H.; Wang, N.

    1995-01-01

    Capillary endothelial cells can be switched between growth and differentiation by altering cell-extracellular matrix interactions and thereby, modulating cell shape. Studies were carried out to determine when cell shape exerts its growth-regulatory influence during cell cycle progression and to explore the role of cytoskeletal structure and mechanics in this control mechanism. When G0-synchronized cells were cultured in basic fibroblast growth factor (FGF)-containing defined medium on dishes coated with increasing densities of fibronectin or a synthetic integrin ligand (RGD-containing peptide), cell spreading, nuclear extension, and DNA synthesis all increased in parallel. To determine the minimum time cells must be adherent and spread on extracellular matrix (ECM) to gain entry into S phase, cells were removed with trypsin or induced to retract using cytochalasin D at different times after plating. Both approaches revealed that cells must remain extended for approximately 12-15 h and hence, most of G1, in order to enter S phase. After this restriction point was passed, normally 'anchorage-dependent' endothelial cells turned on DNA synthesis even when round and in suspension. The importance of actin-containing microfilaments in shape-dependent growth control was confirmed by culturing cells in the presence of cytochalasin D (25-1000 ng ml-1): dose-dependent inhibition of cell spreading, nuclear extension, and DNA synthesis resulted. In contrast, induction of microtubule disassembly using nocodazole had little effect on cell or nuclear spreading and only partially inhibited DNA synthesis. Interestingly, combination of nocodazole with a suboptimal dose of cytochalasin D (100 ng ml-1) resulted in potent inhibition of both spreading and growth, suggesting that microtubules are redundant structural elements which can provide critical load-bearing functions when microfilaments are partially compromised. Similar synergism between nocodazole and cytochalasin D was observed

  9. Genetic instability in cancer cells by impaired cell cycle checkpoints.

    PubMed

    Nakanishi, Makoto; Shimada, Midori; Niida, Hiroyuki

    2006-10-01

    Cells continuously encounter DNA damage caused either by damaging agents, including oxygen radicals and DNA replication errors caused by stalled replication forks, or by extracellular environments such as ultraviolet or ionizing irradiation. Such DNA damage poses a great threat to genome stability, potentially leading to loss or amplification of chromosome activity, which may result in cellular senescence, cancer or apoptosis. The DNA damage checkpoints coordinate an arrest in cell cycle progression with the DNA repair process, suppressing either mitotic catastrophe or proliferation of cells with damaged DNA. Numerous key players have been identified in terms of damage sensor proteins, transducer kinases and effectors, but their coordination and interconnectedness in damage control have only recently become evident. In this review, we discuss changes in chromatin structure, recruitment of mediator proteins and activation of transducer kinases in response to DNA damage. These cellular responses are important for determining the potential effects of current cancer therapies in terms of toxicity and efficacy.

  10. Life cycle testing of sodium/sulfur satellite battery cells

    NASA Astrophysics Data System (ADS)

    Flake, Richard A.

    Test results on sodium sulfur cells developed presently by the Air Force for NaS rechargeable batteries for baseload power applications are summarized. Cycle life data are presented on fourteen cells, some of which have accumulated more than 1900 days on test and/or more than 6000 cycles. Results demonstrated cycle life times to be sufficient for use on satellites in high-altitude orbits.

  11. Characteristics and Behavior of Cycled Aged Lithium Ion Cells

    DTIC Science & Technology

    2010-01-01

    service cycle and provide the cornerstone for safety analysis. 18650 Cells with representative chemistry of cells contained in current Army procured...their relevance to this effort warrants inclusion. 1-3 EXPERIMENTAL Representative 18650 cells were cycled at different rates and environmental...conditions. The 18650 chemistry used in this effort is a LiCoO2 lithium ion electrochemical cell. The bulk of this effort was conducted with 1.5 Amp-hr

  12. Regulatory pathways coordinating cell cycle progression in early Xenopus development.

    PubMed

    Gotoh, Tetsuya; Villa, Linda M; Capelluto, Daniel G S; Finkielstein, Carla V

    2011-01-01

    The African clawed frog, Xenopus laevis, is used extensively as a model organism for studying both cell development and cell cycle regulation. For over 20 years now, this model organism has contributed to answering fundamental questions concerning the mechanisms that underlie cell cycle transitions--the cellular components that synthesize, modify, repair, and degrade nucleic acids and proteins, the signaling pathways that allow cells to communicate, and the regulatory pathways that lead to selective expression of subsets of genes. In addition, the remarkable simplicity of the Xenopus early cell cycle allows for tractable manipulation and dissection of the basic components driving each transition. In this organism, early cell divisions are characterized by rapid cycles alternating phases of DNA synthesis and division. The post-blastula stages incorporate gap phases, lengthening progression, and allowing more time for DNA repair. Various cyclin/Cdk complexes are differentially expressed during the early cycles with orderly progression being driven by both the combined action of cyclin synthesis and degradation and the appropriate selection of specific substrates by their Cdk components. Like other multicellular organisms, chief developmental events in early Xenopus embryogenesis coincide with profound remodeling of the cell cycle, suggesting that cell proliferation and differentiation events are linked and coordinated through crosstalk mechanisms acting on signaling pathways involving the expression of cell cycle control genes.

  13. Epidermal growth factor-induced proliferation of collecting duct cells from Oak Ridge polycystic kidney mice involves activation of Na+/H+ exchanger.

    PubMed

    Coaxum, Sonya D; Blanton, Mary G; Joyner, Alisha; Akter, Tanjina; Bell, P Darwin; Luttrell, Louis M; Raymond, John R; Lee, Mi-Hye; Blichmann, Paul A; Garnovskaya, Maria N; Saigusa, Takamitsu

    2014-09-15

    Epidermal growth factor (EGF) is linked to the pathogenesis of polycystic kidney disease (PKD). We explored signaling pathways activated by EGF in orpk cilia (-) collecting duct cell line derived from a mouse model of PKD (hypomorph of the Tg737/Ift88 gene) with severely stunted cilia, and in a control orpk cilia (+) cell line with normal cilia. RT-PCR demonstrated mRNAs for EGF receptor subunits ErbB1, ErbB2, ErbB3, ErbB4, and mRNAs for Na(+)/H(+) exchangers (NHE), NHE-1, NHE-2, NHE-3, NHE-4, and NHE-5 in both cell lines. EGF stimulated proton efflux in both cell lines. This effect was significantly attenuated by MIA, 5-(n-methyl-N-isobutyl) amiloride, a selective inhibitor of NHE-1 and NHE-2, and orpk cilia (-) cells were more sensitive to MIA than control cells (P < 0.01). EGF significantly induced extracellular signal-regulated kinase (ERK) phosphorylation in both cilia (+) and cilia (-) cells (63.3 and 123.6%, respectively), but the effect was more pronounced in orpk cilia (-) cells (P < 0.01). MIA significantly attenuated EGF-induced ERK phosphorylation only in orpk cilia (-) cells (P < 0.01). EGF increased proliferation of orpk cilia (+) cells and orpk cilia (-) cells, respectively, and MIA at 1-5 μM attenuated EGF-induced proliferation in orpk cilia (-) cells without affecting proliferation of orpk cilia (+) cells. EGF-induced proliferation of both cell lines was significantly decreased by the EGFR tyrosine kinase inhibitor AG1478 and MEK inhibitor PD98059. These results suggest that EGF exerts mitogenic effects in the orpk cilia (-) cells via activation of growth-associated amiloride-sensitive NHEs and ERK.

  14. The Cell Cycle: An Activity Using Paper Plates to Represent Time Spent in Phases of the Cell Cycle

    ERIC Educational Resources Information Center

    Scherer, Yvette D.

    2014-01-01

    In this activity, students are given the opportunity to combine skills in math and geometry for a biology lesson in the cell cycle. Students utilize the data they collect and analyze from an online onion-root-tip activity to create a paper-plate time clock representing a 24-hour cell cycle. By dividing the paper plate into appropriate phases of…

  15. Nerve growth factor induced changes in the Golgi apparatus of PC-12 rat pheochromocytoma cells as studied by ligand endocytosis, cytochemical and morphometric methods.

    PubMed

    Hickey, W F; Stieber, A; Hogue-Angeletti, R; Gonatas, J; GOnatas, N K

    1983-10-01

    Cells of the PC-12 rat pheochromocytoma cell line respond to nerve growth factor (NGF) by sprouting neurites and biochemically differentiating into sympathetic ganglion-like cells. NGF-stimulated ('differentiated') and unstimulated ('undifferentiated') cells were studied by cytochemical techniques for the localization of the enzymes acid phosphatase (ACPase) and thiamine pyrophosphatase (TPPase), and by a morphometric analysis of the distribution of endocytosed wheat-germ agglutinin labelled with horseradish peroxidase (WGA-HRP). Both cytochemical stains showed the enzymes to be distributed in lysosomes and certain cisternae of the Golgi apparatus in both NGF stimulated and unstimulated cells. ACPase was not confined to GERL (Golgi-endoplasmic reticulum-lysosome) as in certain other cells. The morphometric studies demonstrated that the reaction product of the internalized WGA-HRP occupied 4.7% of the cytoplasmic area in unstimulated cells and 4.5% in NGF-stimulated ones. Despite this similarity, the distribution of the WGA-HRP among the studied intracellular compartments in these two cell groups varied. In the NGF-stimulated cells 3.3% of the WGA-HRP reaction product was found in the innermost Golgi cisterna(e) while in unstimulated cells only 0.3% was seen in this compartment. Similarly, 4.3% of the WGA-HRP stain was found in small vesicles at the 'trans' aspect of the Golgi apparatus in stimulated cells, when only 0.3% of the stain occupied this compartment in 'undifferentiated' cells. The morphometric analysis also revealed that when the PC-12 cells were stimulated with NGF, the Golgi apparatus increased in area by approximately 70%. These findings are consistent with the hypothesis that NGF induced differentiation of PC-12 cells is coupled with enhanced endocytosis of WGA and probably of its 'receptor' to the innermost Golgi cisterna(e) and the closely associated vesicles.

  16. The epidermal growth factor-induced migration of rat liver epithelial cells is associated with a transient inhibition of DNA synthesis.

    PubMed

    Geimer, P; Bade, E G

    1991-10-01

    Epidermal growth factor (EGF) is a potent mitogen for most cultured cells and has previously been shown to induce the migration of rat liver epithelial cells. We have now demonstrated that under migration-inducing conditions EGF does not stimulate cell proliferation, but causes instead a transient inhibition of DNA synthesis. Analysis at the single-cell level by [3H]thymidine autoradiography indicated that in 40-50% of the EGF-treated cell population the entry into S phase is delayed. The simultaneous demonstration of migration tracks by laminin immunofluorescence revealed that the transient inhibition of DNA synthesis is not restricted to the migratory cells. The effect is also observed with the stationary subpopulation and appears, therefore, to be independent of the induction of migration. The independence of both processes was further supported by showing that induction of migration by EGF proceeds undisturbed in cells blocked in S phase by aphidicolin. These results indicated that for rat liver epithelial cells the induction of migration by EGF has priority over cell proliferation. The data also emphasize the need for a time-course analysis when studying factors that stimulate or inhibit DNA synthesis or cell proliferation.

  17. Cell cycle-dependent induction of autophagy, mitophagy and reticulophagy.

    PubMed

    Tasdemir, Ezgi; Maiuri, M Chiara; Tajeddine, Nicolas; Vitale, Ilio; Criollo, Alfredo; Vicencio, José Miguel; Hickman, John A; Geneste, Olivier; Kroemer, Guido

    2007-09-15

    When added to cells, a variety of autophagy inducers that operate through distinct mechanisms and target different organelles for autophagic destruction (mitochondria in mitophagy, endoplasmic reticulum in reticulophagy) rarely induce autophagic vacuolization in more than 50% or the cells. Here we show that this heterogeneity may be explained by cell cycle-specific effects. The BH3 mimetic ABT737, lithium, rapamycin, tunicamycin or nutrient depletion stereotypically induce autophagy preferentially in the G(1) and S phases of the cell cycle, as determined by simultaneous monitoring of cell cycle markers and the cytoplasmic aggregation of GFP-LC3 in autophagic vacuoles. These results point to a hitherto neglected crosstalk between autophagic vacuolization and cell cycle regulation.

  18. Brucella abortus Cell Cycle and Infection Are Coordinated.

    PubMed

    De Bolle, Xavier; Crosson, Sean; Matroule, Jean-Yves; Letesson, Jean-Jacques

    2015-12-01

    Brucellae are facultative intracellular pathogens. The recent development of methods and genetically engineered strains allowed the description of cell-cycle progression of Brucella abortus, including unipolar growth and the ordered initiation of chromosomal replication. B. abortus cell-cycle progression is coordinated with intracellular trafficking in the endosomal compartments. Bacteria are first blocked at the G1 stage, growth and chromosome replication being resumed shortly before reaching the intracellular proliferation compartment. The control mechanisms of cell cycle are similar to those reported for the bacterium Caulobacter crescentus, and they are crucial for survival in the host cell. The development of single-cell analyses could also be applied to other bacterial pathogens to investigate their cell-cycle progression during infection.

  19. Flow cytometry methods for the study of cell-cycle parameters of planarian stem cells.

    PubMed

    Kang, Hara; Sánchez Alvarado, Alejandro

    2009-05-01

    Due to their characteristic inaccessibility and low numbers, little is known about the cell-cycle dynamics of most stem cells in vivo. A powerful, established methodology to study cell-cycle dynamics is flow cytometry, which is used routinely to study the cell-cycle dynamics of proliferating cells in vitro. Its use in heterogeneous mixtures of cells obtained from whole animals, however, is complicated by the relatively low abundance of cycling to non-cycling cells. We report on flow cytometric methods that take advantage of the abundance of proliferating stem cells in the planarian Schmidtea mediterranea. The optimized protocols allow us to measure cell-cycle dynamics and follow BrdU-labeled cells specifically in complex mixtures of cells. These methods expand on the growing toolkit being developed to study stem cell biology in planarians, and open the door to detailed cytometric studies of a collectively totipotent population of adult stem cells in vivo.

  20. Erythromycin and clarithromycin modulation of growth factor-induced expression of heparanase mRNA on human lung cancer cells in vitro.

    PubMed Central

    Sasaki, M; Ito, T; Kashima, M; Fukui, S; Izumiyama, N; Watanabe, A; Sano, M; Fujiwara, Y; Miura, M

    2001-01-01

    Heparanase activity is correlated with the metastatic potential of several cancer cells and is a key enzyme in the breakdown of tissue barriers. It is also involved in the regulation of growth factor and cytokine activity. However, little is known about the factors that induce heparanase in cancer cells. We investigated the effect of three growth factors, platelet-derived growth factor (PDGF), hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF), on heparanase mRNA induction in lung cancer cells in vitro. In addition, we examined the effect of erythromycin (EM) and clarithromycin (CAM), which are 14-membered ring macrolide antibiotics that act as biological response modifiers, on the expression of heparanase mRNA induced by growth factors. PDGF, HGF and bFGF stimulated cell migration activity and enhanced the expression of heparanase mRNA in the human lung adenocarcinoma cell line A549. Via different mechanisms, EM and CAM modulate the induction by these factors of heparanase mRNA expression on A549 cells. EM also significantly suppressed A549 cell migration induced by PDGF and HGF, and CAM significantly suppressed A549cell migration induced by bFGF. The results suggest that the growth factors PDGF, HGF and bFGF are important inducers of heparanase in potentially invasive and metastatic cancer cells. The suppressive effect of heparanase mRNA expression by EM and CAM may have interestingtherapeutic applications in the prevention of metastasis. PMID:11759110

  1. Filamin B Plays a Key Role in Vascular Endothelial Growth Factor-induced Endothelial Cell Motility through Its Interaction with Rac-1 and Vav-2*

    PubMed Central

    del Valle-Pérez, Beatriz; Martínez, Vanesa Gabriela; Lacasa-Salavert, Cristina; Figueras, Agnès; Shapiro, Sandor S.; Takafuta, Toshiro; Casanovas, Oriol; Capellà, Gabriel; Ventura, Francesc; Viñals, Francesc

    2010-01-01

    Actin-binding proteins filamin A (FLNA) and B (FLNB) are expressed in endothelial cells and play an essential role during vascular development. In order to investigate their role in adult endothelial cell function, we initially confirmed their expression pattern in different adult mouse tissues and cultured cell lines and found that FLNB expression is concentrated mainly in endothelial cells, whereas FLNA is more ubiquitously expressed. Functionally, small interfering RNA knockdown of endogenous FLNB in human umbilical vein endothelial cells inhibited vascular endothelial growth factor (VEGF)-induced in vitro angiogenesis by decreasing endothelial cell migration capacity, whereas FLNA ablation did not alter these parameters. Moreover, FLNB-depleted cells increased their substrate adhesion with more focal adhesions. The molecular mechanism underlying this effect implicates modulation of small GTP-binding protein Rac-1 localization and activity, with altered activation of its downstream effectors p21 protein Cdc42/Rac-activated kinase (PAK)-4/5/6 and its activating guanine nucleotide exchange factor Vav-2. Moreover, our results suggest the existence of a signaling complex, including FLNB, Rac-1, and Vav-2, under basal conditions that would further interact with VEGFR2 and integrin αvβ5 after VEGF stimulation. In conclusion, our results reveal a crucial role for FLNB in endothelial cell migration and in the angiogenic process in adult endothelial cells. PMID:20110358

  2. Cycle life test. [of secondary spacecraft cells

    NASA Technical Reports Server (NTRS)

    Harkness, J. D.

    1977-01-01

    Statistical information concerning cell performance characteristics and limitations of secondary spacecraft cells is presented. Weaknesses in cell design as well as battery weaknesses encountered in various satellite programs are reported. Emphasis is placed on improving the reliability of space batteries.

  3. Cell cycle control, checkpoint mechanisms, and genotoxic stress.

    PubMed Central

    Shackelford, R E; Kaufmann, W K; Paules, R S

    1999-01-01

    The ability of cells to maintain genomic integrity is vital for cell survival and proliferation. Lack of fidelity in DNA replication and maintenance can result in deleterious mutations leading to cell death or, in multicellular organisms, cancer. The purpose of this review is to discuss the known signal transduction pathways that regulate cell cycle progression and the mechanisms cells employ to insure DNA stability in the face of genotoxic stress. In particular, we focus on mammalian cell cycle checkpoint functions, their role in maintaining DNA stability during the cell cycle following exposure to genotoxic agents, and the gene products that act in checkpoint function signal transduction cascades. Key transitions in the cell cycle are regulated by the activities of various protein kinase complexes composed of cyclin and cyclin-dependent kinase (Cdk) molecules. Surveillance control mechanisms that check to ensure proper completion of early events and cellular integrity before initiation of subsequent events in cell cycle progression are referred to as cell cycle checkpoints and can generate a transient delay that provides the cell more time to repair damage before progressing to the next phase of the cycle. A variety of cellular responses are elicited that function in checkpoint signaling to inhibit cyclin/Cdk activities. These responses include the p53-dependent and p53-independent induction of Cdk inhibitors and the p53-independent inhibitory phosphorylation of Cdk molecules themselves. Eliciting proper G1, S, and G2 checkpoint responses to double-strand DNA breaks requires the function of the Ataxia telangiectasia mutated gene product. Several human heritable cancer-prone syndromes known to alter DNA stability have been found to have defects in checkpoint surveillance pathways. Exposures to several common sources of genotoxic stress, including oxidative stress, ionizing radiation, UV radiation, and the genotoxic compound benzo[a]pyrene, elicit cell cycle

  4. Transcriptional mechanism of vascular endothelial growth factor-induced expression of protein kinase CβII in chronic lymphocytic leukaemia cells

    PubMed Central

    Al-Sanabra, Ola; Duckworth, Andrew D.; Glenn, Mark A.; Brown, Benjamin R. B.; Angelillo, Piera; Lee, Kelvin; Herbert, John; Falciani, Francesco; Kalakonda, Nagesh; Slupsky, Joseph R.

    2017-01-01

    A key feature of chronic lymphocytic leukaemia (CLL) cells is overexpressed protein kinase CβII (PKCβII), an S/T kinase important in the pathogenesis of this and other B cell malignancies. The mechanisms contributing to enhanced transcription of the gene coding for PKCβII, PRKCB, in CLL cells remain poorly described, but could be important because of potential insight into how the phenotype of these cells is regulated. Here, we show that SP1 is the major driver of PKCβII expression in CLL cells where enhanced association of this transcription factor with the PRKCB promoter is likely because of the presence of histone marks permissive of gene activation. We also show how vascular endothelial growth factor (VEGF) regulates PRKCB promoter function in CLL cells, stimulating PKCβ gene transcription via increased association of SP1 and decreased association of STAT3. Taken together, these results are the first to demonstrate a clear role for SP1 in the up regulation of PKCβII expression in CLL cells, and the first to link SP1 with the pathogenesis of this and potentially other B cell malignancies where PKCβII is overexpressed. PMID:28233872

  5. Nerve growth factor-induced changes in the intracellular localization of the protein kinase C substrate B-50 in pheochromocytoma PC12 cells

    PubMed Central

    1989-01-01

    High levels of the neuron-specific protein kinase C substrate, B-50 (= GAP43), are present in neurites and growth cones during neuronal development and regeneration. This suggests a hitherto nonelucidated role of this protein in neurite outgrowth. Comparable high levels of B- 50 arise in the pheochromocytoma PC12 cell line during neurite formation. To get insight in the putative growth-associated function of B-50, we compared its ultrastructural localization in naive PC12 cells with its distribution in nerve growth factor (NGF)- or dibutyryl cyclic AMP (dbcAMP)-treated PC12 cells. B-50 immunogold labeling of cryosections of untreated PC12 cells is mainly associated with lysosomal structures, including multivesicular bodies, secondary lysosomes, and Golgi apparatus. The plasma membrane is virtually devoid of label. However, after 48-h NGF treatment of the cells, B-50 immunoreactivity is most pronounced on the plasma membrane. Highest B- 50 immunoreactivity is observed on plasma membranes surrounding sprouting microvilli, lamellipodia, and filopodia. Outgrowing neurites are scattered with B-50 labeling, which is partially associated with chromaffin granules. In NGF-differentiated PC12 cells, B-50 immunoreactivity is, as in untreated cells, also associated with organelles of the lysosomal family and Golgi stacks. B-50 distribution in dbcAMP-differentiated cells closely resembles that in NGF-treated cells. The altered distribution of B-50 immunoreactivity induced by differentiating agents indicates a shift of the B-50 protein towards the plasma membrane. This translocation accompanies the acquisition of neuronal features of PC12 cells and points to a neurite growth- associated role for B-50, performed at the plasma membrane at the site of protrusion. PMID:2537833

  6. Disconnected circadian and cell cycles in a tumor-driven cell line.

    PubMed

    Pendergast, Julie S; Yeom, Mijung; Reyes, Bryan A; Ohmiya, Yoshihiro; Yamazaki, Shin

    2010-11-01

    Cell division occurs at a specific time of day in numerous species, suggesting that the circadian and cell cycles are coupled in vivo. By measuring the cell cycle rhythm in real-time, we recently showed that the circadian and cell cycles are not coupled in immortalized fibroblasts, resulting in a rapid rate of cell division even though the circadian rhythm is normal in these cells. Here we report that tumor-driven Lewis lung carcinoma (LLC) cells have perfectly temperature compensated circadian clocks, but the periods of their cell cycle gene expression rhythms are temperature-dependent, suggesting that their circadian and cell cycles are not connected. These data support our hypothesis that decoupling of the circadian and cell cycles may underlie aberrant cell division in tumor cells.

  7. Cell Cycle Related Differentiation of Bone Marrow Cells into Lung Cells

    SciTech Connect

    Dooner, Mark; Aliotta, Jason M.; Pimental, Jeffrey; Dooner, Gerri J.; Abedi, Mehrdad; Colvin, Gerald; Liu, Qin; Weier, Heinz-Ulli; Dooner, Mark S.; Quesenberry, Peter J.

    2007-12-31

    Green-fluorescent protein (GFP) labeled marrow cells transplanted into lethally irradiated mice can be detected in the lungs of transplanted mice and have been shown to express lung specific proteins while lacking the expression of hematopoietic markers. We have studied marrow cells induced to transit cell cycle by exposure to IL-3, IL-6, IL-11 and steel factor at different times of culture corresponding to different phases of cell cycle. We have found that marrow cells at the G1/S interface have a 3-fold increase in cells which assume a lung phenotype and that this increase is no longer seen in late S/G2. These cells have been characterized as GFP{sup +} CD45{sup -} and GFP{sup +} cytokeratin{sup +}. Thus marrow cells with the capacity to convert into cells with a lung phenotype after transplantation show a reversible increase with cytokine induced cell cycle transit. Previous studies have shown the phenotype of bone marrow stem cells fluctuates reversibly as these cells traverse cell cycle, leading to a continuum model of stem cell regulation. The present studies indicate that marrow stem cell production of nonhematopoietic cells also fluctuates on a continuum.

  8. The role of peroxisome proliferator-activated receptor-{beta}/{delta} in epidermal growth factor-induced HaCaT cell proliferation

    SciTech Connect

    Liang Pengfei; Jiang Bimei; Yang Xinghua; Xiao Xianzhong Huang Xu; Long Jianhong; Zhang Pihong; Zhang Minghua; Xiao Muzhang; Xie Tinghong; Huang Xiaoyuan

    2008-10-15

    Epidermal growth factor (EGF) has been shown to be a potent mitogen for epidermal cells both in vitro and in vivo, thus contributing to the development of an organism. It has recently become clear that peroxisome proliferator-activated receptor-{beta}/{delta} (PPAR{beta}/{delta}) expression and activation is involved in the cell proliferation. However, little is known about the role of PPAR{beta}/{delta} in EGF-induced proliferation of HaCaT keratinocytes. In this study, HaCaT cells were cultured in the presence and absence of EGF and we identified that EGF induced an increase of PPAR{beta}/{delta} mRNA and protein level expression in time-dependent and dose-dependent manner, and AG1487, an EGF receptor (EGFR) special inhibitor, caused attenuation of PPAR{beta}/{delta} protein expression. Electrophoretic mobility shift assay (EMSA) revealed that EGF significantly increased PPAR{beta}/{delta} binding activity in HaCaT keratinocytes. Antisense phosphorothioate oligonucleotides (asODNs) against PPAR{beta}/{delta} caused selectively inhibition of PPAR{beta}/{delta} protein content induced by EGF and significantly attenuated EGF-mediated cell proliferation. Treatment of the cells with L165041, a specific synthetic ligand for PPAR{beta}/{delta}, significantly enhanced EGF-mediated cell proliferation. Finally, c-Jun ablation inhibited PPAR{beta}/{delta} up-regulation induced by EGF, and chromatin immunoprecipitation (ChIP) showed that c-Jun bound to the PPAR{beta}/{delta} promoter and the binding increased in EGF-stimulated cells. These results demonstrate that EGF induces PPAR{beta}/{delta} expression in a c-Jun-dependent manner and PPAR{beta}/{delta} plays a vital role in EGF-stimulated proliferation of HaCaT cells.

  9. Involvement of cysteine-rich protein 61 in the epidermal growth factor-induced migration of human anaplastic thyroid cancer cells.

    PubMed

    Chin, Li-Han; Hsu, Sung-Po; Zhong, Wen-Bin; Liang, Yu-Chih

    2016-05-01

    Anaplastic thyroid cancer (ATC) is among the most aggressive types of malignant cancer. Epidermal growth factor (EGF) plays a crucial role in the pathogenesis of ATC, and patients with thyroid carcinoma typically exhibit increased cysteine-rich protein 61 (Cyr61). In this study, we found that EGF treatment induced cell migration, stress fiber formation, Cyr61 mRNA and protein expressions, and Cyr61 protein secretion in ATC cells. The recombinant Cyr61 protein significantly induced cell migration; however, inhibition of Cyr61 activity by a Cyr61-specific antibody abrogated EGF-induced cell migration. EGF treatment also affected epithelial-to-mesenchymal transition (EMT)-related marker protein expression, as evidenced by an increase in vimentin and a decrease in E-cadherin expression. Inhibition of Cyr61 expression by Cyr61 siRNA decreased cell migration and reversed the EMT-related marker protein expression. EGF treatment increased the phosphorylation of the extracellular signal-regulated kinase (ERK) and cAMP response element-binding protein (CREB), and finally activated Cyr61 promoter plasmid activity. Our results suggest that Cyr61 is induced by EGF through the ERK/CREB signal pathway and that it plays a crucial role in the migration and invasion of ATC cells; moreover, Cyr61 might be a therapeutic target for metastatic ATC.

  10. Eicosopentaneoic Acid and Other Free Fatty Acid Receptor Agonists Inhibit Lysophosphatidic Acid- and Epidermal Growth Factor-Induced Proliferation of Human Breast Cancer Cells

    PubMed Central

    Hopkins, Mandi M.; Zhang, Zhihong; Liu, Ze; Meier, Kathryn E.

    2016-01-01

    Many key actions of ω-3 (n-3) fatty acids have recently been shown to be mediated by two G protein-coupled receptors (GPCRs) in the free fatty acid receptor (FFAR) family, FFA1 (GPR40) and FFA4 (GPR120). n-3 Fatty acids inhibit proliferation of human breast cancer cells in culture and in animals. In the current study, the roles of FFA1 and FFA4 were investigated. In addition, the role of cross-talk between GPCRs activated by lysophosphatidic acid (LPA), and the tyrosine kinase receptor activated by epidermal growth factor (EGF), was examined. In MCF-7 and MDA-MB-231 human breast cancer cell lines, both LPA and EGF stimulated proliferation, Erk activation, Akt activation, and CCN1 induction. LPA antagonists blocked effects of LPA and EGF on proliferation in MCF-7 and MDA-MB-231, and on cell migration in MCF-7. The n-3 fatty acid eicosopentaneoic acid inhibited LPA- and EGF-induced proliferation in both cell lines. Two synthetic FFAR agonists, GW9508 and TUG-891, likewise inhibited LPA- and EGF-induced proliferation. The data suggest a major role for FFA1, which was expressed by both cell lines. The results indicate that n-3 fatty acids inhibit breast cancer cell proliferation via FFARs, and suggest a mechanism involving negative cross-talk between FFARS, LPA receptors, and EGF receptor. PMID:26821052

  11. Eicosopentaneoic Acid and Other Free Fatty Acid Receptor Agonists Inhibit Lysophosphatidic Acid- and Epidermal Growth Factor-Induced Proliferation of Human Breast Cancer Cells.

    PubMed

    Hopkins, Mandi M; Zhang, Zhihong; Liu, Ze; Meier, Kathryn E

    2016-01-26

    Many key actions of ω-3 (n-3) fatty acids have recently been shown to be mediated by two G protein-coupled receptors (GPCRs) in the free fatty acid receptor (FFAR) family, FFA1 (GPR40) and FFA4 (GPR120). n-3 Fatty acids inhibit proliferation of human breast cancer cells in culture and in animals. In the current study, the roles of FFA1 and FFA4 were investigated. In addition, the role of cross-talk between GPCRs activated by lysophosphatidic acid (LPA), and the tyrosine kinase receptor activated by epidermal growth factor (EGF), was examined. In MCF-7 and MDA-MB-231 human breast cancer cell lines, both LPA and EGF stimulated proliferation, Erk activation, Akt activation, and CCN1 induction. LPA antagonists blocked effects of LPA and EGF on proliferation in MCF-7 and MDA-MB-231, and on cell migration in MCF-7. The n-3 fatty acid eicosopentaneoic acid inhibited LPA- and EGF-induced proliferation in both cell lines. Two synthetic FFAR agonists, GW9508 and TUG-891, likewise inhibited LPA- and EGF-induced proliferation. The data suggest a major role for FFA1, which was expressed by both cell lines. The results indicate that n-3 fatty acids inhibit breast cancer cell proliferation via FFARs, and suggest a mechanism involving negative cross-talk between FFARS, LPA receptors, and EGF receptor.

  12. Ca2+ signaling, genes and the cell cycle

    PubMed Central

    Machaca, Khaled

    2013-01-01

    Changes in the concentration and spatial distribution of Ca2+ ions in the cytoplasm constitute a ubiquitous intracellular signaling module in cellular physiology. With the advent of Ca2+ dyes that allow direct visualization of Ca2+ transients, combined with powerful experimental tools such as electrophysiological recordings, intracellular Ca2+ transients have been implicated in practically every aspect of cellular physiology, including cellular proliferation. Ca2+ signals are associated with different phases of the cell cycle and interfering with Ca2+ signaling or downstream pathways often disrupts progression of the cell cycle. Although there exists a dependence between Ca2+ signals and the cell cycle the mechanisms involved are not well defined and given the cross-talk between Ca2+ and other signaling modules, it is difficult to assess the exact role of Ca2+ signals in cell cycle progression. Two exceptions however, include fertilization and T-cell activation, where well-defined roles for Ca2+ signals in mediating progression through specific stages of the cell cycle have been clearly established. In the case of T-cell activation Ca2+ regulates entry into the cell cycle through the induction of gene transcription. PMID:21084120

  13. Impact of the cell division cycle on gene circuits

    NASA Astrophysics Data System (ADS)

    Bierbaum, Veronika; Klumpp, Stefan

    2015-12-01

    In growing cells, protein synthesis and cell growth are typically not synchronous, and, thus, protein concentrations vary over the cell division cycle. We have developed a theoretical description of genetic regulatory systems in bacteria that explicitly considers the cell division cycle to investigate its impact on gene expression. We calculate the cell-to-cell variations arising from cells being at different stages in the division cycle for unregulated genes and for basic regulatory mechanisms. These variations contribute to the extrinsic noise observed in single-cell experiments, and are most significant for proteins with short lifetimes. Negative autoregulation buffers against variation of protein concentration over the division cycle, but the effect is found to be relatively weak. Stronger buffering is achieved by an increased protein lifetime. Positive autoregulation can strongly amplify such variation if the parameters are set to values that lead to resonance-like behaviour. For cooperative positive autoregulation, the concentration variation over the division cycle diminishes the parameter region of bistability and modulates the switching times between the two stable states. The same effects are seen for a two-gene mutual-repression toggle switch. By contrast, an oscillatory circuit, the repressilator, is only weakly affected by the division cycle.

  14. The Mammalian Cell Cycle Regulates Parvovirus Nuclear Capsid Assembly

    PubMed Central

    Riolobos, Laura; Domínguez, Carlos; Kann, Michael; Almendral, José M.

    2015-01-01

    It is unknown whether the mammalian cell cycle could impact the assembly of viruses maturing in the nucleus. We addressed this question using MVM, a reference member of the icosahedral ssDNA nuclear parvoviruses, which requires cell proliferation to infect by mechanisms partly understood. Constitutively expressed MVM capsid subunits (VPs) accumulated in the cytoplasm of mouse and human fibroblasts synchronized at G0, G1, and G1/S transition. Upon arrest release, VPs translocated to the nucleus as cells entered S phase, at efficiencies relying on cell origin and arrest method, and immediately assembled into capsids. In synchronously infected cells, the consecutive virus life cycle steps (gene expression, proteins nuclear translocation, capsid assembly, genome replication and encapsidation) proceeded tightly coupled to cell cycle progression from G0/G1 through S into G2 phase. However, a DNA synthesis stress caused by thymidine irreversibly disrupted virus life cycle, as VPs became increasingly retained in the cytoplasm hours post-stress, forming empty capsids in mouse fibroblasts, thereby impairing encapsidation of the nuclear viral DNA replicative intermediates. Synchronously infected cells subjected to density-arrest signals while traversing early S phase also blocked VPs transport, resulting in a similar misplaced cytoplasmic capsid assembly in mouse fibroblasts. In contrast, thymidine and density arrest signals deregulating virus assembly neither perturbed nuclear translocation of the NS1 protein nor viral genome replication occurring under S/G2 cycle arrest. An underlying mechanism of cell cycle control was identified in the nuclear translocation of phosphorylated VPs trimeric assembly intermediates, which accessed a non-conserved route distinct from the importin α2/β1 and transportin pathways. The exquisite cell cycle-dependence of parvovirus nuclear capsid assembly conforms a novel paradigm of time and functional coupling between cellular and virus life

  15. Mechanisms of sulindac-induced apoptosis and cell cycle arrest.

    PubMed

    Jung, Barbara; Barbier, Valerie; Brickner, Howard; Welsh, John; Fotedar, Arun; McClelland, Michael

    2005-02-28

    The mechanism underlying the chemopreventive effects of the non-steroidal anti-inflammatory drug sulindac remains unclear. Its active metabolite, sulindac sulfide, induces cell cycle arrest as well as apoptosis in mammalian cell lines. We now show that in murine thymocytes, sulindac sulfide-induced cell death is p53, bax, Fas, and FasL independent. In contrast, bcl2 transgenic thymocytes are resistant to sulindac sulfide-induced apoptosis. In addition, we demonstrate that sulindac sulfide-induced cell cycle arrest in mouse embryonic fibroblasts (MEFs) is partly mediated by the retinoblastoma tumor suppressor protein (Rb) and the cyclin kinase inhibitor p21waf1/cip1. Furthermore, MEFs deficient in p21 or Rb are more susceptible to sulindac sulfide-induced cell death. These results suggest that sulindac may selectively target premalignant cells with cell cycle checkpoint deficits.

  16. Egr-1 mediates epidermal growth factor-induced downregulation of E-cadherin expression via Slug in human ovarian cancer cells.

    PubMed

    Cheng, J-C; Chang, H-M; Leung, P C K

    2013-02-21

    Loss of the cell adhesion protein E-cadherin increases the invasive capability of ovarian cancer cells. We have previously shown that epidermal growth factor (EGF) downregulates E-cadherin and induces ovarian cancer cell invasion through the H(2)O(2)/p38 MAPK-mediated upregulation of the E-cadherin transcriptional repressor Snail. However, the molecular mechanisms underlying the EGF-induced downregulation of E-cadherin are not fully understood. In the current study, we demonstrated that treatment of two ovarian cancer cell lines, SKOV3 and OVCAR5, with EGF induced the expression of the transcription factor Egr-1, and this induction was abolished by small interfering RNA (siRNA)-mediated depletion of the EGF receptor. EGF-induced Egr-1 expression required the activation of the ERK1/2 and PI3K/Akt signaling pathways and was unrelated to EGF-induced H(2)O(2) production and activation of the p38 MAPK pathway. Moreover, depletion of Egr-1 with siRNA abolished the EGF-induced downregulation of E-cadherin and increased cell invasion. Interestingly, siRNA depletion of Egr-1 attenuated the EGF-induced expression of Slug, but not that of Snail. Moreover, chromatin immunoprecipitation (ChIP) analysis showed that Slug is a target gene of Egr-1. These results provide evidence that Egr-1 is a mediator that is involved in the EGF-induced downregulation of E-cadherin and increased cell invasion. Our results also demonstrate that EGF activates two independent signaling pathways, which are the H(2)O(2)/p38 MAPK-mediated upregulation of Snail expression and the Egr-1-mediated upregulation of Slug expression. These two signaling pathways contribute to the EGF-induced downregulation of E-cadherin, which subsequently increases the invasive capability of ovarian cancer cells.

  17. Configuration and performance of fuel cell-combined cycle options

    SciTech Connect

    Rath, L.K.; Le, P.H.; Sudhoff, F.A.

    1995-12-31

    The natural gas, indirect-fired, carbonate fuel-cell-bottomed, combined cycle (NG-IFCFC) and the topping natural-gas/solid-oxide fuel-cell combined cycle (NG-SOFCCC) are introduced as novel power-plant systems for the distributed power and on-site markets in the 20-200 mega-watt (MW) size range. The novel NG-IFCFC power-plant system configures the ambient pressure molten-carbonate fuel cell (MCFC) with a gas turbine, air compressor, combustor, and ceramic heat exchanger: The topping solid-oxide fuel-cell (SOFC) combined cycle is not new. The purpose of combining a gas turbine with a fuel cell was to inject pressurized air into a high-pressure fuel cell and to reduce the size, and thereby, to reduce the cost of the fuel cell. Today, the SOFC remains pressurized, but excess chemical energy is combusted and the thermal energy is utilized by the Carnot cycle heat engine to complete the system. ASPEN performance results indicate efficiencies and heat rates for the NG-IFCFC or NG-SOFCCC are better than conventional fuel cell or gas turbine steam-bottomed cycles, but with smaller and less expensive components. Fuel cell and gas turbine systems should not be viewed as competitors, but as an opportunity to expand to markets where neither gas turbines nor fuel cells alone would be commercially viable. Non-attainment areas are the most likely markets.

  18. Intercellular Coupling of the Cell Cycle and Circadian Clock in Adult Stem Cell Culture.

    PubMed

    Matsu-Ura, Toru; Dovzhenok, Andrey; Aihara, Eitaro; Rood, Jill; Le, Hung; Ren, Yan; Rosselot, Andrew E; Zhang, Tongli; Lee, Choogon; Obrietan, Karl; Montrose, Marshall H; Lim, Sookkyung; Moore, Sean R; Hong, Christian I

    2016-12-01

    Circadian clock-gated cell division cycles are observed from cyanobacteria to mammals via intracellular molecular connections between these two oscillators. Here we demonstrate WNT-mediated intercellular coupling between the cell cycle and circadian clock in 3D murine intestinal organoids (enteroids). The circadian clock gates a population of cells with heterogeneous cell-cycle times that emerge as 12-hr synchronized cell division cycles. Remarkably, we observe reduced-amplitude oscillations of circadian rhythms in intestinal stem cells and progenitor cells, indicating an intercellular signal arising from differentiated cells governing circadian clock-dependent synchronized cell division cycles. Stochastic simulations and experimental validations reveal Paneth cell-secreted WNT as the key intercellular coupling component linking the circadian clock and cell cycle in enteroids.

  19. Estrogen receptor alpha is cell cycle-regulated and regulates the cell cycle in a ligand-dependent fashion.

    PubMed

    JavanMoghadam, Sonia; Weihua, Zhang; Hunt, Kelly K; Keyomarsi, Khandan

    2016-06-17

    Estrogen receptor alpha (ERα) has been implicated in several cell cycle regulatory events and is an important predictive marker of disease outcome in breast cancer patients. Here, we aimed to elucidate the mechanism through which ERα influences proliferation in breast cancer cells. Our results show that ERα protein is cell cycle-regulated in human breast cancer cells and that the presence of 17-β-estradiol (E2) in the culture medium shortened the cell cycle significantly (by 4.5 hours, P < 0.05) compared with unliganded conditions. The alterations in cell cycle duration were observed in the S and G2/M phases, whereas the G1 phase was indistinguishable under liganded and unliganded conditions. In addition, ERα knockdown in MCF-7 cells accelerated mitotic exit, whereas transfection of ERα-negative MDA-MB-231 cells with exogenous ERα significantly shortened the S and G2/M phases (by 9.1 hours, P < 0.05) compared with parental cells. Finally, treatment of MCF-7 cells with antiestrogens revealed that tamoxifen yields a slower cell cycle progression through the S and G2/M phases than fulvestrant does, presumably because of the destabilizing effect of fulvestrant on ERα protein. Together, these results show that ERα modulates breast cancer cell proliferation by regulating events during the S and G2/M phases of the cell cycle in a ligand-dependent fashion. These results provide the rationale for an effective treatment strategy that includes a cell cycle inhibitor in combination with a drug that lowers estrogen levels, such as an aromatase inhibitor, and an antiestrogen that does not result in the degradation of ERα, such as tamoxifen.

  20. Brain-derived neurotrophic factor induces migration of endothelial cells through a TrkB-ERK-integrin αVβ3-FAK cascade.

    PubMed

    Matsuda, Shinji; Fujita, Tsuyoshi; Kajiya, Mikihito; Takeda, Katsuhiro; Shiba, Hideki; Kawaguchi, Hiroyuki; Kurihara, Hidemi

    2012-05-01

    Brain-derived neurotrophic factor (BDNF) promotes the regeneration of periodontal tissue. Since angiogenesis is important for tissue regeneration, investigating effect of BDNF on endothelial cell function may help to reveal its mechanism, whereby, BDNF promotes periodontal tissue regeneration. In this study, we examined the influence of BDNF on migration in human microvascular endothelial cells (HMVECs), focusing on the effects on extracellular signal-regulated kinase (ERK), integrin α(V)β(3), and focal adhesion kinase (FAK). The migration of endothelial cells was assessed with a modified Boyden chamber and a wound healing assay. The expression of integrin α(V)β(3) and the phosphorylation of ERK and FAK were analyzed by immunoblotting and immunofluorescence microscopy. BDNF (25 ng/ml) induced cell migration. PD98059, an ERK inhibitor, K252a, a specific inhibitor for TrkB, a high affinity receptor of BDNF, and an anti-integrin α(V)β(3) antibody suppressed the BDNF-induced migration. BDNF increased the levels of integrin α(V)β(3) and phosphorylated ERK1/2 and FAK. The ERK inhibitor and TrkB inhibitor also reduced levels of integrin α(V)β(3) and phosphorylated FAK. We propose that BDNF stimulates endothelial cell migration by a process involving TrkB/ERK/integrin α(V)β(3)/FAK, and this may help to enhance the regeneration of periodontal tissue.

  1. Apicomplexan cell cycle flexibility: centrosome controls the clutch

    PubMed Central

    Chen, Chun-Ti; Gubbels, Marc-Jan

    2015-01-01

    The centrosome serves as a central hub coordinating multiple cellular events in eukaryotes. A recent study in Toxoplasma gondii revealed a unique bipartite structure of the centrosome, which coordinates the nuclear cycle (S-phase and mitosis) and budding cycle (cytokinesis) of the parasite, and deciphers the principle behind flexible apicomplexan cell division modes. PMID:25899747

  2. BMI1 Polycomb Group Protein Acts as a Master Switch for Growth and Death of Tumor Cells: Regulates TCF4-Transcriptional Factor-Induced BCL2 Signaling

    PubMed Central

    Siddique, Hifzur Rahman; Parray, Aijaz; Tarapore, Rohinton S.; Wang, Lei; Mukhtar, Hasan; Karnes, R. Jeffery; Deng, Yibin; Konety, Badrinath R.; Saleem, Mohammad

    2013-01-01

    For advanced prostate cancer (CaP), the progression of tumors to the state of chemoresistance and paucity of knowledge about the mechanism of chemoresistance are major stumbling blocks in the management of this disease. Here, we provide compelling evidence that BMI1 polycomb group protein and a stem cell factor plays a crucial role in determining the fate of tumors vis-à-vis chemotherapy. We show that progressive increase in the levels of BMI1 occurs during the progression of CaP disease in humans. We show that BMI1-rich tumor cells are non-responsive to chemotherapy whereas BMI1-silenced tumor cells are responsive to therapy. By employing microarray, ChIP, immunoblot and Luciferase reporter assays, we identified a unique mechanism through which BMI1 rescues tumor cells from chemotherapy. We found that BMI1 regulates (i) activity of TCF4 transcriptional factor and (ii) binding of TCF4 to the promoter region of anti-apoptotic BCL2 gene. Notably, an increased TCF4 occupancy on BCL2 gene was observed in prostatic tissues exhibiting high BMI1 levels. Using tumor cells other than CaP, we also showed that regulation of TCF4-mediated BCL2 by BMI1 is universal. It is noteworthy that forced expression of BMI1 was observed to drive normal cells to hyperproliferative mode. We show that targeting BMI1 improves the outcome of docetaxel therapy in animal models bearing chemoresistant prostatic tumors. We suggest that BMI1 could be exploited as a potential molecular target for therapeutics to treat chemoresistant tumors. PMID:23671559

  3. BMI1 polycomb group protein acts as a master switch for growth and death of tumor cells: regulates TCF4-transcriptional factor-induced BCL2 signaling.

    PubMed

    Siddique, Hifzur Rahman; Parray, Aijaz; Tarapore, Rohinton S; Wang, Lei; Mukhtar, Hasan; Karnes, R Jeffery; Deng, Yibin; Konety, Badrinath R; Saleem, Mohammad

    2013-01-01

    For advanced prostate cancer (CaP), the progression of tumors to the state of chemoresistance and paucity of knowledge about the mechanism of chemoresistance are major stumbling blocks in the management of this disease. Here, we provide compelling evidence that BMI1 polycomb group protein and a stem cell factor plays a crucial role in determining the fate of tumors vis-à-vis chemotherapy. We show that progressive increase in the levels of BMI1 occurs during the progression of CaP disease in humans. We show that BMI1-rich tumor cells are non-responsive to chemotherapy whereas BMI1-silenced tumor cells are responsive to therapy. By employing microarray, ChIP, immunoblot and Luciferase reporter assays, we identified a unique mechanism through which BMI1 rescues tumor cells from chemotherapy. We found that BMI1 regulates (i) activity of TCF4 transcriptional factor and (ii) binding of TCF4 to the promoter region of anti-apoptotic BCL2 gene. Notably, an increased TCF4 occupancy on BCL2 gene was observed in prostatic tissues exhibiting high BMI1 levels. Using tumor cells other than CaP, we also showed that regulation of TCF4-mediated BCL2 by BMI1 is universal. It is noteworthy that forced expression of BMI1 was observed to drive normal cells to hyperproliferative mode. We show that targeting BMI1 improves the outcome of docetaxel therapy in animal models bearing chemoresistant prostatic tumors. We suggest that BMI1 could be exploited as a potential molecular target for therapeutics to treat chemoresistant tumors.

  4. Regulation of the Chlamydomonas cell cycle by light and dark

    PubMed Central

    1980-01-01

    By growing cells in alternating periods of light and darkness, we have found that the synchronization of phototrophically grown Chlamydomonas populations is regulated at two specific points in the cell cycle: the primary arrest (A) point, located in early G1, and the transition (T) point, located in mid-G1. At the A point, cell cycle progression becomes light dependent. At the T point, completion of the cycle becomes independent of light. Cells transferred from light to dark at cell cycle position between the two regulatory points enter a reversible resting state in which they remain viable and metabolically active, but do not progress through their cycles. The photosystem II inhibitor dichlorophenyldimethylurea (DCMU) mimics the A point block induced by darkness. This finding indicates that the A point block is mediated by a signal that operates through photosynthetic electron transport. Cells short of the T point will arrest in darkness although they contain considerable carbohydrate reserves. After the T point, a sharp increase occurs in starch degradation and in the endogenous respiration rate, indicating that some internal block to the availability of stored energy reserves has now been released, permitting cell cycle progression. PMID:6767730

  5. miR-503 inhibits platelet-derived growth factor-induced human aortic vascular smooth muscle cell proliferation and migration through targeting the insulin receptor.

    PubMed

    Bi, Rui; Ding, Fangbao; He, Yi; Jiang, Lianyong; Jiang, Zhaolei; Mei, Ju; Liu, Hao

    2016-12-01

    Abnormal proliferation and migration of vascular smooth muscle cells (VSMC) is a common feature of disease progression in atherosclerosis. Here, we investigated the potential role of miR-503 in platelet-derived growth factor (PDGF)-induced proliferation and migration of human aortic smooth muscle cells and the underlying mechanisms of action. miR-503 expression was significantly downregulated in a dose- and time-dependent manner following PDGF treatment. Introduction of miR-503 mimics into cultured SMCs significantly attenuated cell proliferation and migration induced by PDGF. Bioinformatics analyses revealed that the insulin receptor (INSR) is a target candidate of miR-503. miR-503 suppressed luciferase activity driven by a vector containing the 3'-untranslated region of INSR in a sequence-specific manner. Downregulation of INSR appeared critical for miR-503-mediated inhibitory effects on PDGF-induced cell proliferation and migration in human aortic SMCs. Based on the collective data, we suggest a novel role of miR-503 as a regulator of VSMC proliferation and migration through modulating INSR.

  6. Tumor necrosis factor induces phosphorylation of a 28-kDa mRNA cap-binding protein in human cervical carcinoma cells.

    PubMed Central

    Marino, M W; Pfeffer, L M; Guidon, P T; Donner, D B

    1989-01-01

    Tumor necrosis factor alpha (TNF-alpha) stimulated the phosphorylation of a 28-kDa protein (p28) in the ME-180 line of human cervical carcinoma cells. The effect of TNF-alpha on the phosphorylation state of p28 was rapid (4-fold increase within 15 min) and persistent, remaining above the basal level for at least 2 hr. The specific binding of 125I-labeled TNF-alpha to cell-surface binding sites, the stimulation of p28 phosphorylation by TNF-alpha, and the inhibition of cell proliferation by TNF-alpha occurred with nearly identical dose-response relationships. Two-dimensional SDS/PAGE resolved p28 into two isoforms having pI values of 6.2 and 6.1. A phosphorylated cap-binding protein was substantially enriched from lysates of control or TNF-alpha-treated ME-180 cells by affinity chromatography with 7-methylguanosine 5'-triphosphate-Sepharose. The phosphoprotein recovered from this procedure was the substrate for TNF-alpha-promoted phosphorylation, p28. Thus, TNF-alpha stimulates the phosphorylation of this mRNA cap-binding protein, which may be involved in the transduction of TNF-alpha-receptor binding into cellular responses. Images PMID:2813400

  7. Tumor necrosis factor induces phosphorylation of a 28-kDa mRNA cap-binding protein in human cervical carcinoma cells.

    PubMed

    Marino, M W; Pfeffer, L M; Guidon, P T; Donner, D B

    1989-11-01

    Tumor necrosis factor alpha (TNF-alpha) stimulated the phosphorylation of a 28-kDa protein (p28) in the ME-180 line of human cervical carcinoma cells. The effect of TNF-alpha on the phosphorylation state of p28 was rapid (4-fold increase within 15 min) and persistent, remaining above the basal level for at least 2 hr. The specific binding of 125I-labeled TNF-alpha to cell-surface binding sites, the stimulation of p28 phosphorylation by TNF-alpha, and the inhibition of cell proliferation by TNF-alpha occurred with nearly identical dose-response relationships. Two-dimensional SDS/PAGE resolved p28 into two isoforms having pI values of 6.2 and 6.1. A phosphorylated cap-binding protein was substantially enriched from lysates of control or TNF-alpha-treated ME-180 cells by affinity chromatography with 7-methylguanosine 5'-triphosphate-Sepharose. The phosphoprotein recovered from this procedure was the substrate for TNF-alpha-promoted phosphorylation, p28. Thus, TNF-alpha stimulates the phosphorylation of this mRNA cap-binding protein, which may be involved in the transduction of TNF-alpha-receptor binding into cellular responses.

  8. A Taenia crassiceps factor induces apoptosis of spleen CD4+T cells and TFG-β and Foxp3 gene expression in mice.

    PubMed

    Zepeda, N; Tirado, R; Copitin, N; Solano, S; Fernández, A M; Tato, P; Molinari, J L

    2016-03-01

    This study was undertaken to determine whether a parasite substance produces structural pathology in the mouse spleen. A low-molecular-weight Taenia crassiceps metacestode factor (MF) isolated from the peritoneal fluid of female mice infected with T. crassiceps metacestodes induced pathological and immunological changes in mouse spleen cells in vivo. Electron microscopy and confocal microscopy revealed severe changes in the spleen histoarchitecture of T. crassiceps-infected and MF-treated mice. Apoptotic degenerated spleen cells were observed in the white and red pulps and were more conspicuous in the white pulp of the spleen from the T. crassiceps-infected mice than in that of the MF-treated mice. Flow cytometry analysis revealed that the numbers of spleen CD4+T cells were significantly lower in both experimental groups than in control mice. The ex vivo expression of transforming growth factor (TGF)-β and factor Foxp3 were significantly higher in splenocytes of the experimental mice than the basal expression observed in the control cells. These findings may have potential applications for a better understanding of the host-parasite relationship in human neurocysticercosis.

  9. Genome-wide examination of myoblast cell cycle withdrawal duringdifferentiation

    SciTech Connect

    Shen, Xun; Collier, John Michael; Hlaing, Myint; Zhang, Leanne; Delshad, Elizabeth H.; Bristow, James; Bernstein, Harold S.

    2002-12-02

    Skeletal and cardiac myocytes cease division within weeks of birth. Although skeletal muscle retains limited capacity for regeneration through recruitment of satellite cells, resident populations of adult myocardial stem cells have not been identified. Because cell cycle withdrawal accompanies myocyte differentiation, we hypothesized that C2C12 cells, a mouse myoblast cell line previously used to characterize myocyte differentiation, also would provide a model for studying cell cycle withdrawal during differentiation. C2C12 cells were differentiated in culture medium containing horse serum and harvested at various time points to characterize the expression profiles of known cell cycle and myogenic regulatory factors by immunoblot analysis. BrdU incorporation decreased dramatically in confluent cultures 48 hr after addition of horse serum, as cells started to form myotubes. This finding was preceded by up-regulation of MyoD, followed by myogenin, and activation of Bcl-2. Cyclin D1 was expressed in proliferating cultures and became undetectable in cultures containing 40 percent fused myotubes, as levels of p21(WAF1/Cip1) increased and alpha-actin became detectable. Because C2C12 myoblasts withdraw from the cell cycle during myocyte differentiation following a course that recapitulates this process in vivo, we performed a genome-wide screen to identify other gene products involved in this process. Using microarrays containing approximately 10,000 minimally redundant mouse sequences that map to the UniGene database of the National Center for Biotechnology Information, we compared gene expression profiles between proliferating, differentiating, and differentiated C2C12 cells and verified candidate genes demonstrating differential expression by RT-PCR. Cluster analysis of differentially expressed genes revealed groups of gene products involved in cell cycle withdrawal, muscle differentiation, and apoptosis. In addition, we identified several genes, including DDAH2 and Ly

  10. Large scale spontaneous synchronization of cell cycles in amoebae

    NASA Astrophysics Data System (ADS)

    Segota, Igor; Boulet, Laurent; Franck, Carl

    2014-03-01

    Unicellular eukaryotic amoebae Dictyostelium discoideum are generally believed to grow in their vegetative state as single cells until starvation, when their collective aspect emerges and they differentiate to form a multicellular slime mold. While major efforts continue to be aimed at their starvation-induced social aspect, our understanding of population dynamics and cell cycle in the vegetative growth phase has remained incomplete. We show that substrate-growtn cell populations spontaneously synchronize their cell cycles within several hours. These collective population-wide cell cycle oscillations span millimeter length scales and can be completely suppressed by washing away putative cell-secreted signals, implying signaling by means of a diffusible growth factor or mitogen. These observations give strong evidence for collective proliferation behavior in the vegetative state and provide opportunities for synchronization theories beyond classic Kuramoto models.

  11. Grow₂: the HIF system, energy homeostasis and the cell cycle.

    PubMed

    Moniz, Sónia; Biddlestone, John; Rocha, Sónia

    2014-05-01

    Cell cycle progression is an energy demanding process and requires fine-tuned metabolic regulation. Cells must overcome an energy restriction checkpoint before becoming committed to progress through the cell cycle. Aerobic organisms need oxygen for the metabolic conversion of nutrients into energy. As such, environmental oxygen is a critical signalling molecule regulating cell fate. The Hypoxia Inducible Factors (HIFs) are a family of transcription factors that respond to changes in environmental oxygen and cell energy and coordinate a transcriptional program which forms an important part of the cellular response to a hostile environment. A significant proportion of HIF-dependent transcriptional target genes, code for proteins that are involved in energy homeostasis. In this review we discuss the role of the HIF system in the regulation of energy homeostasis in response to changes in environmental oxygen and the impact on cell cycle control, and address the implications of the deregulation of this effect in cancer.

  12. Variety in intracellular diffusion during the cell cycle.

    PubMed

    Selhuber-Unkel, Christine; Yde, Pernille; Berg-Sørensen, Kirstine; Oddershede, Lene B

    2009-07-01

    During the cell cycle, the organization of the cytoskeletal network undergoes dramatic changes. In order to reveal possible changes of the viscoelastic properties in the intracellular space during the cell cycle we investigated the diffusion of endogenous lipid granules within the fission yeast Schizosaccharomyces Pombe using optical tweezers. The cell cycle was divided into interphase and mitotic cell division, and the mitotic cell division was further subdivided in its stages. During all stages of the cell cycle, the granules predominantly underwent subdiffusive motion, characterized by an exponent alpha that is also linked to the viscoelastic moduli of the cytoplasm. The exponent alpha was significantly smaller during interphase than during any stage of the mitotic cell division, signifying that the cytoplasm was more elastic during interphase than during division. We found no significant differences in the subdiffusive exponents from granules measured in different stages of cell division. Also, our results for the exponent displayed no significant dependence on the position of the granule within the cell. The observation that the cytoplasm is more elastic during interphase than during mitotic cell division is consistent with the fact that elastic cytoskeletal elements such as microtubules are less abundantly present during cell division than during interphase.

  13. Granulocyte Colony-Stimulating Factor Induces Osteoblast Inhibition by B Lymphocytes and Osteoclast Activation by T Lymphocytes during Hematopoietic Stem/Progenitor Cell Mobilization.

    PubMed

    Li, Sidan; Li, Tianshou; Chen, Yongbing; Nie, Yinchao; Li, Changhong; Liu, Lanting; Li, Qiaochuan; Qiu, Lugui

    2015-08-01

    In the bone marrow (BM), hematopoietic stem and progenitor cells (HSPCs) reside in specialized niches near osteoblast cells at the endosteum. HSPCs that egress to peripheral blood are widely used for transplant, and mobilization is most commonly performed with recombinant human granulocyte colony-stimulating factor (G-CSF). However, the cellular targets of G-CSF that initiate the mobilization cascade and bone remodeling are not completely understood. Here, we examined whether T and B lymphocytes modulate the bone niche and influence HSPC mobilization. We used T and B defective mice to show that G-CSF-induced mobilization of HSPCs correlated with B lymphocytes but poorly with T lymphocytes. In addition, we found that defective B lymphocytes prevent G-CSF-mediated osteoblast disruption, and further study showed BM osteoblasts were reduced coincident with mobilization, induced by elevated expression of dickkopf1 of BM B lymphocytes. BM T cells were also involved in G-CSF-induced osteoclast activation by regulating the Receptor Activator of Nuclear Factor-κ B Ligand/Osteoprotegerin (RANKL/OPG) axis. These data provide evidence that BM B and T lymphocytes play a role in G-CSF-induced HSPC mobilization by regulating bone remodeling.

  14. Gelsolin-mediated activation of PI3K/Akt pathway is crucial for hepatocyte growth factor-induced cell scattering in gastric carcinoma

    PubMed Central

    Huang, Baohua; Deng, Shuo; Loo, Ser Yue; Datta, Arpita; Yap, Yan Lin; Yan, Benedict; Ooi, Chia Huey; Dinh, Thuy Duong; Zhuo, Jingli; Tochhawng, Lalchhandami; Gopinadhan, Suma; Jegadeesan, Tamilarasi; Tan, Patrick; Salto-Tellez, Manuel; Yong, Wei Peng; Soong, Richie; Yeoh, Khay Guan; Goh, Yaw Chong; Lobie, Peter E.; Yang, Henry; Kumar, Alan Prem; Maciver, Sutherland K.; So, Jimmy B.Y.; Yap, Celestial T.

    2016-01-01

    In gastric cancer (GC), the main subtypes (diffuse and intestinal types) differ in pathological characteristics, with diffuse GC exhibiting early disseminative and invasive behaviour. A distinctive feature of diffuse GC is loss of intercellular adhesion. Although widely attributed to mutations in the CDH1 gene encoding E-cadherin, a significant percentage of diffuse GC do not harbor CDH1 mutations. We found that the expression of the actin-modulating cytoskeletal protein, gelsolin, is significantly higher in diffuse-type compared to intestinal-type GCs, using immunohistochemical and microarray analysis. Furthermore, in GCs with wild-type CDH1, gelsolin expression correlated inversely with CDH1 gene expression. Downregulating gelsolin using siRNA in GC cells enhanced intercellular adhesion and E-cadherin expression, and reduced invasive capacity. Interestingly, hepatocyte growth factor (HGF) induced increased gelsolin expression, and gelsolin was essential for HGF-medicated cell scattering and E-cadherin transcriptional repression through Snail, Twist and Zeb2. The HGF-dependent effect on E-cadherin was found to be mediated by interactions between gelsolin and PI3K-Akt signaling. This study reveals for the first time a function of gelsolin in the HGF/cMet oncogenic pathway, which leads to E-cadherin repression and cell scattering in gastric cancer. Our study highlights gelsolin as an important pro-disseminative factor contributing to the aggressive phenotype of diffuse GC. PMID:27058427

  15. Gelsolin-mediated activation of PI3K/Akt pathway is crucial for hepatocyte growth factor-induced cell scattering in gastric carcinoma.

    PubMed

    Huang, Baohua; Deng, Shuo; Loo, Ser Yue; Datta, Arpita; Yap, Yan Lin; Yan, Benedict; Ooi, Chia Huey; Dinh, Thuy Duong; Zhuo, Jingli; Tochhawng, Lalchhandami; Gopinadhan, Suma; Jegadeesan, Tamilarasi; Tan, Patrick; Salto-Tellez, Manuel; Yong, Wei Peng; Soong, Richie; Yeoh, Khay Guan; Goh, Yaw Chong; Lobie, Peter E; Yang, Henry; Kumar, Alan Prem; Maciver, Sutherland K; So, Jimmy B Y; Yap, Celestial T

    2016-05-03

    In gastric cancer (GC), the main subtypes (diffuse and intestinal types) differ in pathological characteristics, with diffuse GC exhibiting early disseminative and invasive behaviour. A distinctive feature of diffuse GC is loss of intercellular adhesion. Although widely attributed to mutations in the CDH1 gene encoding E-cadherin, a significant percentage of diffuse GC do not harbor CDH1 mutations. We found that the expression of the actin-modulating cytoskeletal protein, gelsolin, is significantly higher in diffuse-type compared to intestinal-type GCs, using immunohistochemical and microarray analysis. Furthermore, in GCs with wild-type CDH1, gelsolin expression correlated inversely with CDH1 gene expression. Downregulating gelsolin using siRNA in GC cells enhanced intercellular adhesion and E-cadherin expression, and reduced invasive capacity. Interestingly, hepatocyte growth factor (HGF) induced increased gelsolin expression, and gelsolin was essential for HGF-medicated cell scattering and E-cadherin transcriptional repression through Snail, Twist and Zeb2. The HGF-dependent effect on E-cadherin was found to be mediated by interactions between gelsolin and PI3K-Akt signaling. This study reveals for the first time a function of gelsolin in the HGF/cMet oncogenic pathway, which leads to E-cadherin repression and cell scattering in gastric cancer. Our study highlights gelsolin as an important pro-disseminative factor contributing to the aggressive phenotype of diffuse GC.

  16. Asarone from Acori Tatarinowii Rhizoma Potentiates the Nerve Growth Factor-Induced Neuronal Differentiation in Cultured PC12 Cells: A Signaling Mediated by Protein Kinase A

    PubMed Central

    Lam, Kelly Y. C.; Chen, Jianping; Lam, Candy T. W.; Wu, Qiyun; Yao, Ping; Dong, Tina T. X.; Lin, Huangquan; Tsim, Karl W. K.

    2016-01-01

    Acori Tatarinowii Rhizoma (ATR), the rhizome of Acorus tatarinowii Schott, is being used clinically to treat neurological disorders. The volatile oil of ATR is being considered as an active ingredient. Here, α-asarone and β-asarone, accounting about 95% of ATR oil, were evaluated for its function in stimulating neurogenesis. In cultured PC12 cells, application of ATR volatile oil, α-asarone or β-asarone, stimulated the expression of neurofilaments, a bio-marker for neurite outgrowth, in a concentration-dependent manner. The co-treatment of ATR volatile oil, α-asarone or β-asarone, with low concentration of nerve growth factor (NGF) potentiated the NGF-induced neuronal differentiation in cultured PC12 cells. In addition, application of protein kinase A inhibitors, H89 and KT5720, in cultures blocked the ATR-induced neurofilament expression, as well as the phosphorylation of cAMP-responsive element binding protein (CREB). In the potentiation of NGF-induced signaling in cultured PC12 cells, α-asarone and β-asarone showed synergistic effects. These results proposed the neurite-promoting asarone, or ATR volatile oil, could be useful in finding potential drugs for treating various neurodegenerative diseases, in which neurotrophin deficiency is normally involved. PMID:27685847

  17. Corticotropin-releasing factor induces phosphorylation of phospholipase C-gamma at tyrosine residues via its receptor 2beta in human epidermoid A-431 cells.

    PubMed

    Kiang, J G; Ding, X Z; Gist, I D; Jones, R R; Tsokos, G C

    1998-12-18

    This laboratory previously reported that corticotropin-releasing factor (CRF) increased intracellular free calcium concentrations, cellular cAMP, inositol 1,4,5-trisphosphate, protein kinase C activity, and protein phosphorylation in human A-431 cells. The increase was blocked by CRF receptor antagonist. In this study, we identified the type of CRF receptors present and investigated whether CRF induced tyrosine phosphorylation of phospholipase C-gamma via CRF receptors. Using novel primers in reverse transcriptase-polymerase chain reaction, we determined the CRF receptor type to be that of 2beta. The levels of the CRF receptor type 2beta were not altered in cells treated with activators of protein kinase C, Ca2+ ionophore, or cells overexpressing heat shock protein 70 kDa. Cells treated with CRF displayed increases in protein tyrosine phosphorylation approximately at 150 kDa as detected by immunoblotting using an antibody against phosphotyrosine. Immunoprecipitation with antibodies directed against phospholipase C-beta3, -gamma1, or -gamma2 isoforms (which have molecular weights around 150 kDa) followed by Western blotting using an anti-phosphotyrosine antibody showed that only phospholipase C-gamma1 and -gamma2 were phosphorylated. The increase in phospholipase C-gamma phosphorylation was concentration-dependent with an EC50 of 4.2+/-0.1 pM. The maximal phosphorylation by CRF at 1 nM occurred by 5 min. The CRF-induced phosphorylation was inhibited by the protein tyrosine kinase inhibitors genistein and herbimycin A, suggesting that CRF activates protein tyrosine kinases. Treatment of cells with CRF receptor antagonist, but not pertussis toxin, prior to treatment with CRF inhibited the CRF-induced phosphorylation, suggesting it is mediated by the CRF receptor type 2beta that is not coupled to pertussis toxin-sensitive G-proteins. Treatment with 1,2-bis(2iminophenoxy)ethane-N,N,N',N'-tetraacetic acid attenuated the phospholipase C-gamma phosphorylation. In summary

  18. Cell cycle deregulation by methyl isocyanate: Implications in liver carcinogenesis.

    PubMed

    Panwar, Hariom; Raghuram, Gorantla V; Jain, Deepika; Ahirwar, Alok K; Khan, Saba; Jain, Subodh K; Pathak, Neelam; Banerjee, Smita; Maudar, Kewal K; Mishra, Pradyumna K

    2014-03-01

    Liver is often exposed to plethora of chemical toxins. Owing to its profound physiological role and central function in metabolism and homeostasis, pertinent succession of cell cycle in liver epithelial cells is of prime importance to maintain cellular proliferation. Although recent evidence has displayed a strong association between exposures to methyl isocyanate (MIC), one of the most toxic isocyanates, and neoplastic transformation, molecular characterization of the longitudinal effects of MIC on cell cycle regulation has never been performed. Here, we sequentially delineated the status of different proteins arbitrating the deregulation of cell cycle in liver epithelial cells treated with MIC. Our data reaffirms the oncogenic capability of MIC with elevated DNA damage response proteins pATM and γ-H2AX, deregulation of DNA damage check point genes CHK1 and CHK2, altered expression of p53 and p21 proteins involved in cell cycle arrest with perturbation in GADD-45 expression in the treated cells. Further, alterations in cyclin A, cyclin E, CDK2 levels along with overexpression of mitotic spindle checkpoints proteins Aurora A/B, centrosomal pericentrin protein, chromosomal aberrations, and loss of Pot1a was observed. Thus, MIC impacts key proteins involved in cell cycle regulation to trigger genomic instability as a possible mechanism of developmental basis of liver carcinogenesis.

  19. Duplication of the genome in normal and cancer cell cycles.

    PubMed

    Bandura, Jennifer L; Calvi, Brian R

    2002-01-01

    It is critical to discover the mechanisms of normal cell cycle regulation if we are to fully understand what goes awry in cancer cells. The normal eukaryotic cell tightly regulates the activity of origins of DNA replication so that the genome is duplicated exactly once per cell cycle. Over the last ten years much has been learned concerning the cell cycle regulation of origin activity. It is now clear that the proteins and cell cycle mechanisms that control origin activity are largely conserved from yeast to humans. Despite this conservation, the composition of origins of DNA replication in higher eukaryotes remains ill defined. A DNA consensus for predicting origins has yet to emerge, and it is of some debate whether primary DNA sequence determines where replication initiates. In this review we outline what is known about origin structure and the mechanism of once per cell cycle DNA replication with an emphasis on recent advances in mammalian cells. We discuss the possible relevance of these regulatory pathways for cancer biology and therapy.

  20. Hematopoietic factor-induced synthesis of von Willebrand factor by the Dami human megakaryoblastic cell line and by normal human megakaryocytes.

    PubMed

    Greenberg, S M; Chandrasekhar, C

    1991-01-01

    Identification of hemopoietic factors and the molecular mechanisms by which they regulate the various stages of megakaryocyte development and platelet protein expression has been hampered by the lack of a purified, self-renewing, and responsive biological assay system. Previously, the human megakaryocytic Dami cell line has been shown to differentiate in response to phorbol ester by increasing the expression of platelet membrane glycoproteins Ib, IIb/IIIa, and the platelet protein, von Willebrand Factor (vWF). In this report, we demonstrate that this cell line is a suitable model for investigating the effects of specific cytokines and hemopoietic factors on the terminal differentiation of megakaryocytes as measured by the stimulated biosynthesis of vWF in serum-free culture. Although a low concentration (10 U/ml) of purified recombinant interleukin 3 (IL-3) had no effect, a higher concentration (100 U/ml) stimulated a three- to four fold increase in vWF synthesis. Purified thrombopoiesis-stimulating factor (TSF) alone induced a two- to threefold increase, and when used in combination with 10 U/ml IL-3, TSF induced a synergistic five- to sixfold increase in vWF synthesis. Recombinant erythropoietin (EPO) and human interleukin 6 (IL-6) each induced a twofold increase in vWF, and each acted additively with 10 U/ml IL-3. IL-3 and TSF stimulated similar increases in vWF expression by human megakaryocytes contained in nonadherent bone marrow preparations. These results demonstrate the usefulness of the Dami cell line as a serum-free culture system in which to study the direct effects of purified humoral factors on megakaryocyte and platelet protein synthesis during megakaryocyte maturation.

  1. Combined cycle phosphoric acid fuel cell electric power system

    SciTech Connect

    Mollot, D.J.; Micheli, P.L.

    1995-12-31

    By arranging two or more electric power generation cycles in series, combined cycle systems are able to produce electric power more efficiently than conventional single cycle plants. The high fuel to electricity conversion efficiency results in lower plant operating costs, better environmental performance, and in some cases even lower capital costs. Despite these advantages, combined cycle systems for the 1 - 10 megawatt (MW) industrial market are rare. This paper presents a low noise, low (oxides of nitrogen) NOx, combined cycle alternative for the small industrial user. By combining a commercially available phosphoric acid fuel cell (PAFC) with a low-temperature Rankine cycle (similar to those used in geothermal applications), electric conversion efficiencies between 45 and 47 percent are predicted. While the simple cycle PAFC is competitive on a cost of energy basis with gas turbines and diesel generators in the 1 to 2 MW market, the combined cycle PAFC is competitive, on a cost of energy basis, with simple cycle diesel generators in the 4 to 25 MW market. In addition, the efficiency and low-temperature operation of the combined cycle PAFC results in a significant reduction in carbon dioxide emissions with NO{sub x} concentration on the order of 1 parts per million (per weight) (ppmw).

  2. Distinctive effect on nerve growth factor-induced PC12 cell neurite outgrowth by two unique neolignan enantiomers from Illicium merrillianum

    NASA Astrophysics Data System (ADS)

    Tian, Xinhui; Yue, Rongcai; Zeng, Huawu; Li, Honglin; Shan, Lei; He, Weiwei; Shen, Yunheng; Zhang, Weidong

    2015-11-01

    Merrillianoid (1), a racemic neolignan possessing the characteristic benzo-2,7-dioxabicyclo[3.2.1]octane moiety, was isolated from the branches and leaves of Illicium merrillianum. Chiral separation of 1 gave two enantiomers (+)-1 and (-)-1. The structure of 1 was established by comprehensive spectroscopic analysis and single crystal X-ray diffraction. The absolute configurations of enantiomers were determined by quantum mechanical calculation. Compound (+)-1 exhibited a better neurotrophic activity than racemate 1 by promoting nerve growth factor (NGF) induced PC12 cell neurite outgrowth, while (-)-1 showed a distinctive inhibitory effect. Furthermore, a mechanism study indicated that the two enantiomers influenced NGF-induced neurite outgrowth of PC12 cells possibly by interacting with the trkA receptor, and extracellular signal regulated kinases 1/2 (ERK1/2) and mitogen-activated protein kinase (MEK) in Ras/ERK signal cascade. But the phosphorylation level of serine/threonine kinase Akt1 and Akt2 in PI3K/Akt signal pathway showed no significant difference between (+)-1 and (-)-1.

  3. UAP56 is an important mediator of Angiotensin II/platelet derived growth factor induced vascular smooth muscle cell DNA synthesis and proliferation

    SciTech Connect

    Sahni, Abha; Wang, Nadan; Alexis, Jeffrey

    2013-02-15

    Highlights: ► Knockdown of UAP56 inhibits Angiotensin II/PDGF induced vascular smooth muscle cell proliferation. ► UAP56 is a positive regulator of E2F transcriptional activation. ► UAP56 is present in the vessel wall of low flow carotid arteries. -- Abstract: Angiotensin (Ang) II and platelet-derived growth factor (PDGF) are important mediators of pathologic vascular smooth muscle cell (VSMC) proliferation. Identifying downstream mediators of Ang II and PDGF signaling may provide insights for therapies to improve vascular proliferative diseases. We have previously demonstrated that breakpoint cluster region (Bcr) is an important mediator of Ang II/PDGF signaling in VSMC. We have recently reported that the DExD/H box protein UAP56 is an interacting partner of Bcr in regulating VSMC DNA synthesis. We hypothesized that UAP56 itself is an important regulator of VSMC proliferation. In this report we demonstrate that knockdown of UAP56 inhibits Ang II/PDGF induced VSMC DNA synthesis and proliferation, and inhibits E2F transcriptional activity. In addition, we demonstrate that UAP56 is present in the vessel wall of low-flow carotid arteries. These findings suggest that UAP56 is a regulator of VSMC proliferation and identify UAP56 as a target for preventing vascular proliferative disease.

  4. Dihydroartemisinin inhibits vascular endothelial growth factor-induced endothelial cell migration by a p38 mitogen-activated protein kinase-independent pathway.

    PubMed

    Guo, Ling; Dong, Fengyun; Hou, Yinglong; Cai, Weidong; Zhou, Xia; Huang, Ai-Ling; Yang, Min; Allen, Thaddeus D; Liu, Ju

    2014-12-01

    Dihydroartemisinin (DHA), a semi-synthetic derivative of artemisinin, has been demonstrated to possess a strong antiangiogenic activity. However, the molecular mechanisms underlying this effect remain unclear. Endothelial cell (EC) migration is an essential component of angiogenesis, and the p38 mitogen-activated protein kinase (MAPK) signaling pathway plays a key role in the regulation of migration induced by vascular endothelial growth factor (VEGF). The aim of the present study was to investigate the effects of DHA on EC migration and the p38 MAPK signaling pathway. Human umbilical vein ECs (HUVECs) were treated with DHA and VEGF-induced migration was analyzed. The activation of p38 MAPK was detected by western blot analysis, and the migration assays were performed with a p38-specific inhibitor, SB203850. It was revealed that 20 μM DHA significantly reduced EC migration in the transwell migration assay, wound healing assay and electrical cell-substrate impedance sensing real-time analysis. However, DHA did not affect p38 MAPK phosphorylation or expression. In the absence or presence of SB203850, DHA induced a similar proportional reduction of EC migration in the three migration assays. Therefore, the present study demonstrated that DHA inhibits VEGF-induced EC migration via a p38 MAPK-independent pathway.

  5. Distinctive effect on nerve growth factor-induced PC12 cell neurite outgrowth by two unique neolignan enantiomers from Illicium merrillianum

    PubMed Central

    Tian, Xinhui; Yue, Rongcai; Zeng, Huawu; Li, Honglin; Shan, Lei; He, Weiwei; Shen, Yunheng; Zhang, Weidong

    2015-01-01

    Merrillianoid (1), a racemic neolignan possessing the characteristic benzo-2,7-dioxabicyclo[3.2.1]octane moiety, was isolated from the branches and leaves of Illicium merrillianum. Chiral separation of 1 gave two enantiomers (+)−1 and (−)−1. The structure of 1 was established by comprehensive spectroscopic analysis and single crystal X-ray diffraction. The absolute configurations of enantiomers were determined by quantum mechanical calculation. Compound (+)−1 exhibited a better neurotrophic activity than racemate 1 by promoting nerve growth factor (NGF) induced PC12 cell neurite outgrowth, while (−)−1 showed a distinctive inhibitory effect. Furthermore, a mechanism study indicated that the two enantiomers influenced NGF-induced neurite outgrowth of PC12 cells possibly by interacting with the trkA receptor, and extracellular signal regulated kinases 1/2 (ERK1/2) and mitogen-activated protein kinase (MEK) in Ras/ERK signal cascade. But the phosphorylation level of serine/threonine kinase Akt1 and Akt2 in PI3K/Akt signal pathway showed no significant difference between (+)−1 and (−)−1. PMID:26585042

  6. The Timing of T Cell Priming and Cycling

    PubMed Central

    Obst, Reinhard

    2015-01-01

    The proliferation of specific lymphocytes is the central tenet of the clonal selection paradigm. Antigen recognition by T cells triggers a series of events that produces expanded clones of differentiated effector cells. TCR signaling events are detectable within seconds and minutes and are likely to continue for hours and days in vivo. Here, I review the work done on the importance of TCR signals in the later part of the expansion phase of the primary T cell response, primarily regarding the regulation of the cell cycle in CD4+ and CD8+ cells. The results suggest a degree of programing by early signals for effector differentiation, particularly in the CD8+ T cell compartment, with optimal expansion supported by persistent antigen presentation later on. Differences to CD4+ T cell expansion and new avenues toward a molecular understanding of cell cycle regulation in lymphocytes are discussed. PMID:26594213

  7. Global Dynamical Properties of the Yeast Cell Cycle Network

    NASA Astrophysics Data System (ADS)

    Tang, Chao

    2004-03-01

    The interactions between proteins, DNA, and RNA in living cells constitute molecular networks that govern various cellular functions. To investigate the global dynamical properties and stabilities of such networks, we studied the network regulating the cell division (cell cycle) of the budding yeast. With the use of both discrete (Boolean) and continuous (ODEs) dynamical models, it was demonstrated that the cell-cycle network is extremely stable and robust for its function. The biological stationary state--the G1 state--is a global attractor of the dynamics. The biological pathway--the cell-cycle sequence of protein states--is a globally attracting trajectory of the dynamics. These properties are largely preserved with respect to small perturbations to the network. These results suggest that cellular regulatory networks are robustly designed for their functions.

  8. Bax alpha perturbs T cell development and affects cell cycle entry of T cells.

    PubMed Central

    Brady, H J; Gil-Gómez, G; Kirberg, J; Berns, A J

    1996-01-01

    Bax alpha can heterodimerize with Bcl-2 and Bcl-X(L), countering their effects, as well as promoting apoptosis on overexpression. We show that bax alpha transgenic mice have greatly reduced numbers of mature T cells, which results from an impaired positive selection in the thymus. This perturbation in positive selection is accompanied by an increase in the number of cycling thymocytes. Further to this, mature T cells overexpressing Bax alpha have lower levels of p27Kip1 and enter S phase more rapidly in response to interleukin-2 stimulation than do control T cells, while the converse is true of bcl-2 transgenic T cells. These data indicate that apoptotic regulatory proteins can modulate the level of cell cycle-controlling proteins and thereby directly impact on the cell cycle. Images PMID:9003775

  9. NONO couples the circadian clock to the cell cycle.

    PubMed

    Kowalska, Elzbieta; Ripperger, Juergen A; Hoegger, Dominik C; Bruegger, Pascal; Buch, Thorsten; Birchler, Thomas; Mueller, Anke; Albrecht, Urs; Contaldo, Claudio; Brown, Steven A

    2013-01-29

    Mammalian circadian clocks restrict cell proliferation to defined time windows, but the mechanism and consequences of this interrelationship are not fully understood. Previously we identified the multifunctional nuclear protein NONO as a partner of circadian PERIOD (PER) proteins. Here we show that it also conveys circadian gating to the cell cycle, a connection surprisingly important for wound healing in mice. Specifically, although fibroblasts from NONO-deficient mice showed approximately normal circadian cycles, they displayed elevated cell doubling and lower cellular senescence. At a molecular level, NONO bound to the p16-Ink4A cell cycle checkpoint gene and potentiated its circadian activation in a PER protein-dependent fashion. Loss of either NONO or PER abolished this activation and circadian expression of p16-Ink4A and eliminated circadian cell cycle gating. In vivo, lack of NONO resulted in defective wound repair. Because wound healing defects were also seen in multiple circadian clock-deficient mouse lines, our results therefore suggest that coupling of the cell cycle to the circadian clock via NONO may be useful to segregate in temporal fashion cell proliferation from tissue organization.

  10. NONO couples the circadian clock to the cell cycle

    PubMed Central

    Kowalska, Elzbieta; Ripperger, Juergen A.; Hoegger, Dominik C.; Bruegger, Pascal; Buch, Thorsten; Birchler, Thomas; Mueller, Anke; Albrecht, Urs; Contaldo, Claudio; Brown, Steven A.

    2013-01-01

    Mammalian circadian clocks restrict cell proliferation to defined time windows, but the mechanism and consequences of this interrelationship are not fully understood. Previously we identified the multifunctional nuclear protein NONO as a partner of circadian PERIOD (PER) proteins. Here we show that it also conveys circadian gating to the cell cycle, a connection surprisingly important for wound healing in mice. Specifically, although fibroblasts from NONO-deficient mice showed approximately normal circadian cycles, they displayed elevated cell doubling and lower cellular senescence. At a molecular level, NONO bound to the p16-Ink4A cell cycle checkpoint gene and potentiated its circadian activation in a PER protein-dependent fashion. Loss of either NONO or PER abolished this activation and circadian expression of p16-Ink4A and eliminated circadian cell cycle gating. In vivo, lack of NONO resulted in defective wound repair. Because wound healing defects were also seen in multiple circadian clock-deficient mouse lines, our results therefore suggest that coupling of the cell cycle to the circadian clock via NONO may be useful to segregate in temporal fashion cell proliferation from tissue organization. PMID:23267082

  11. Post-transcriptional RNA Regulons Affecting Cell Cycle and Proliferation

    PubMed Central

    Blackinton, Jeff G.

    2014-01-01

    The cellular growth cycle is initiated and maintained by punctual, yet agile, regulatory events involving modifications of cell cycle proteins as well as coordinated gene expression to support cyclic checkpoint decisions. Recent evidence indicates that post-transcriptional partitioning of messenger RNA subsets by RNA-binding proteins help physically localize, temporally coordinate, and efficiently translate cell cycle proteins. This dynamic organization of mRNAs encoding cell cycle components contributes to the overall economy of the cell cycle consistent with the post-transcriptional RNA regulon model of gene expression. This review examines several recent studies demonstrating the coordination of mRNA subsets encoding cell cycle proteins during nuclear export and subsequent coupling to protein synthesis, and discusses evidence for mRNA coordination of p53 targets and the DNA damage response pathway. We consider how these observations may connect to upstream and downstream post-transcriptional coordination and coupling of splicing, export, localization, and translation. Published examples from yeast, nematode, insect, and mammalian systems are discussed, and we consider genetic evidence supporting the conclusion that dysregulation of RNA regulons may promote pathogenic states of growth such as carcinogenesis. PMID:24882724

  12. The Dynamical Mechanisms of the Cell Cycle Size Checkpoint

    NASA Astrophysics Data System (ADS)

    Feng, Shi-Fu; Yan, Jie; Liu, Zeng-Rong; Yang, Ling

    2012-10-01

    Cell division must be tightly coupled to cell growth in order to maintain cell size, whereas the mechanisms of how initialization of mitosis is regulated by cell size remain to be elucidated. We develop a mathematical model of the cell cycle, which incorporates cell growth to investigate the dynamical properties of the size checkpoint in embryos of Xenopus laevis. We show that the size checkpoint is naturally raised from a saddle-node bifurcation, and in a mutant case, the cell loses its size control ability due to the loss of this saddle-node point.

  13. Scatter Factor Induces Blood Vessel Formation in vivo

    NASA Astrophysics Data System (ADS)

    Grant, Derrick S.; Kleinman, Hynda K.; Goldberg, Itzhak D.; Bhargava, Mahdu M.; Nickoloff, Brian J.; Kinsella, James L.; Polverini, Peter; Rosen, Eliot M.

    1993-03-01

    Scatter factor (also known as hepatocyte growth factor) is a glycoprotein secreted by stromal cells that stimulates cell motility and proliferation. In vitro, scatter factor stimulates vascular endothelial cell migration, proliferation, and organization into capillary-like tubes. Using two different in vivo assays, we showed that physiologic quantities of purified native mouse scatter factor and recombinant human hepatocyte growth factor induce angiogenesis (the formation of new blood vessels). The angiogenic activity was blocked by specific anti-scatter factor antibodies. Scatter factor induced cultured microvascular endothelial cells to accumulate and secrete significantly increased quantities of urokinase, an enzyme associated with development of an invasive endothelial phenotype during angiogenesis. We further showed that immunoreactive scatter factor is present surrounding sites of blood vessel formation in psoriatic skin. These findings suggest that scatter factor may act as a paracrine mediator in pathologic angiogenesis associated with human inflammatory disease.

  14. Scatter factor induces blood vessel formation in vivo.

    PubMed Central

    Grant, D S; Kleinman, H K; Goldberg, I D; Bhargava, M M; Nickoloff, B J; Kinsella, J L; Polverini, P; Rosen, E M

    1993-01-01

    Scatter factor (also known as hepatocyte growth factor) is a glycoprotein secreted by stromal cells that stimulates cell motility and proliferation. In vitro, scatter factor stimulates vascular endothelial cell migration, proliferation, and organization into capillary-like tubes. Using two different in vivo assays, we showed that physiologic quantities of purified native mouse scatter factor and recombinant human hepatocyte growth factor induce angiogenesis (the formation of new blood vessels). The angiogenic activity was blocked by specific anti-scatter factor antibodies. Scatter factor induced cultured microvascular endothelial cells to accumulate and secrete significantly increased quantities of urokinase, an enzyme associated with development of an invasive endothelial phenotype during angiogenesis. We further showed that immunoreactive scatter factor is present surrounding sites of blood vessel formation in psoriatic skin. These findings suggest that scatter factor may act as a paracrine mediator in pathologic angiogenesis associated with human inflammatory disease. Images Fig. 1 Fig. 2 Fig. 3 Fig. 5 PMID:7680481

  15. Nanosecond pulsed electric fields and the cell cycle

    NASA Astrophysics Data System (ADS)

    Mahlke, Megan A.

    Exposure to nanosecond pulsed electrical fields (nsPEFs) can cause poration of external and internal cell membranes, DNA damage, and disassociation of cytoskeletal components, all of which are capable of disrupting a cell's ability to replicate. The phase of the cell cycle at the time of exposure is linked to differential sensitivities to nsPEFs across cell lines, as DNA structure, membrane elasticity, and cytoskeletal structure change dramatically during the cell cycle. Additionally, nsPEFs are capable of activating cell cycle checkpoints, which could lead to apoptosis or slow population growth. NsPEFs are emerging as a method for treating tumors via apoptotic induction; therefore, investigating the relevance of nsPEFs and the cell cycle could translate into improved efficacy in tumor treatment. Populations of Jurkat and Chinese Hamster Ovary (CHO) cells were examined post-exposure (10 ns pulse trains at 150kV/cm) by analysis of DNA content via propidium iodide staining and flow cytometric analysis at various time points (1, 6, and 12h post-exposure) to determine population distribution in cell cycle phases. Additionally, CHO and Jurkat cells were synchronized in G1/S and G2/M phases, pulsed, and analyzed to evaluate the role of cell cycle phase in survival of nsPEFs. CHO populations appeared similar to sham populations post-nsPEFs but exhibited arrest in the G1 phase at 6h after exposure. Jurkat cells exhibited increased cell death after nsPEFs compared to CHO cells but did not exhibit checkpoint arrest at any observed time point. The G1/S phase checkpoint is partially controlled by the action of p53; the lack of an active p53 response in Jurkat cells could contribute to their ability to pass this checkpoint and resist cell cycle arrest. Both cell lines exhibited increased sensitivity to nsPEFs in G2/M phase. Live imaging of CHO cells after nsPEF exposure supports the theory of G1/S phase arrest, as a reduced number of cells undergo mitosis within 24 h when

  16. Cell cycles and proliferation patterns in Haematococcus pluvialis

    NASA Astrophysics Data System (ADS)

    Zhang, Chunhui; Liu, Jianguo; Zhang, Litao

    2016-09-01

    Most studies on Haematococcus pluvialis have been focused on cell growth and astaxanthin accumulation; far less attention has been paid to cell cycles and proliferation patterns. The purpose of this study was to clarify cell cycles and proliferation patterns in H. pluvialis microscopically using a camera and video recorder system. The complicated life history of H. pluvialis can be divided into two stages: the motile stage and the non-motile stage. All the cells can be classified into forms as follows: motile cell, non-motile cell, zoospore and aplanospore. The main cell proliferation, both in the motile phase and non-motile phase in H. pluvialis, is by asexual reproduction. Under normal growth conditions, a motile cell usually produces two, sometimes four, and exceptionally eight zoospores. Under unfavorable conditions, the motile cell loses its flagella and transforms into a non-motile cell, and the non-motile cell usually produces 2, 4 or 8 aplanospores, and occasionally 20-32 aplanospores, which further develop into non-motile cells. Under suitable conditions, the non-motile cell is also able to release zoospores. The larger non-motile cells produce more than 16 zoospores, and the smaller ones produce 4 or 8 zoospores. Vegetative reproduction is by direct cell division in the motile phase and by occasional cell budding in the non-motile phase. There is, as yet, no convincing direct evidence for sexual reproduction.

  17. Primary Tumor-Secreted Lymphangiogenic Factors Induce Pre-Metastatic Lymphvascular Niche Formation at Sentinel Lymph Nodes in Oral Squamous Cell Carcinoma

    PubMed Central

    Wakisaka, Naohiro; Hasegawa, Yasuhisa; Yoshimoto, Seiichi; Miura, Kouki; Shiotani, Akihiro; Yokoyama, Junkichi; Sugasawa, Masashi; Moriyama-Kita, Makiko; Endo, Kazuhira; Yoshizaki, Tomokazu

    2015-01-01

    Objectives The objectives of this study were to evaluate the formation of lymphvascular niches in lymph nodes of patients with oral squamous cell carcinoma (OSCC), and investigate the roles of lymphangiogenic and angiogenic factors, such as vascular endothelial growth factor (VEGF)-A, VEGF-C, and VEGF-D, expressed in the primary tumors. Materials and Methods Forty-four patients with previously untreated clinically late T2 or T3 OSCC of cN0 were evaluated for primary tumors and 166 sentinel lymph nodes (SLNs). Primary tumors were immunohistochemically analyzed for expressions of VEGFs. Densities of lymphatic vessels (LVDpodoplanin) and high endothelial venules (HEVD) in the SLNs were also calculated using antibodies for each marker, podoplanin and MECA-79, respectively. Results In 25 patients, all lymph nodes were metastasis-negative, whereas, in 19 patients, metastasis was positive for at least one lymph node (either at SLN, non-SLN, or nodal recurrence). From the analyses of 140 SLNs without metastasis, LVDpodoplanin in 50 SLNs of metastasis-positive cases was significantly higher than that in 90 SLNs of metastasis-negative cases (p = 0.0025). HEVD was not associated with lymph node metastasis. The patients with VEGF-A-High or VEGF-D-High tumors had significantly higher LVDpodoplanin than patients with their Low counterparts (p = 0.0233 and p = 0.0209, respectively). In cases with lymph node metastasis, the VEGF-D-expression score was significantly higher than in those without lymph node metastasis (p = 0.0006). Conclusions These results suggest that lymph node lymphangiogenesis occurs before metastasis in OSCC. VEGF-A and VEGF-D play critical roles in this process. VEGF-D is a potential predictive marker of positive lymph node metastasis in cN0 patients. PMID:26630663

  18. The inhibitory effect of dexamethasone on platelet-derived growth factor-induced vascular smooth muscle cell migration through up-regulating PGC-1{alpha} expression

    SciTech Connect

    Xu, Wei; Guo, Ting; Zhang, Yan; Jiang, Xiaohong; Zhang, Yongxian; Zen, Ke; Yu, Bo; Zhang, Chen-Yu

    2011-05-01

    Dexamethasone has been shown to inhibit vascular smooth muscle cell (VSMC) migration, which is required for preventing restenosis. However, the mechanism underlying effect of dexamethasone remains unknown. We have previously demonstrated that peroxisome proliferator-activated receptor gamma (PPAR{gamma}) coactivator-1 alpha (PGC-1{alpha}) can inhibit VSMC migration and proliferation. Here, we investigated the role of PGC-1{alpha} in dexamethasone-reduced VSMC migration and explored the possible mechanism. We first examined PGC-1{alpha} expression in cultured rat aortic VSMCs. The results revealed that incubation of VSMCs with dexamethasone could significantly elevate PGC-1{alpha} mRNA expression. In contrast, platelet-derived growth factor (PDGF) decreased PGC-1{alpha} expression while stimulating VSMC migration. Mechanistic study showed that suppression of PGC-1{alpha} by small interfering RNA strongly abrogated the inhibitory effect of dexamethasone on VSMC migration, whereas overexpression of PGC-1{alpha} had the opposite effect. Furthermore, an analysis of MAPK signal pathways showed that dexamethasone inhibited ERK and p38 MAPK phosphorylation in VSMCs. Overexpression of PGC-1{alpha} decreased both basal and PDGF-induced p38 MAPK phosphorylation, but it had no effect on ERK phosphorylation. Finally, inhibition of PPAR{gamma} activation by a PPAR{gamma} antagonist GW9662 abolished the suppressive effects of PGC-1{alpha} on p38 MAPK phosphorylation and VSMC migration. These effects of PGC-1{alpha} were enhanced by a PPAR{gamma} agonist troglitazone. Collectively, our data indicated for the first time that one of the anti-migrated mechanisms of dexamethasone is due to the induction of PGC-1{alpha} expression. PGC-1{alpha} suppresses PDGF-induced VSMC migration through PPAR{gamma} coactivation and, consequently, p38 MAPK inhibition.

  19. Cycle life characteristics of Li-TiS2 cells

    NASA Technical Reports Server (NTRS)

    Deligiannis, Frank; Shen, D.; Huang, C. K.; Surampudi, S.

    1991-01-01

    The development of lithium ambient temperature rechargeable cells is discussed. During the development process, we hope to gain a greater understanding of the materials and the properties of the Li-TiS2 cell and its components. The design will meet the requirements of 100 Wh/Kg and 1000 cycles, at 50 percent depth-of-discharge, by 1995.

  20. Cyclin and DNA Distributed Cell Cycle Model for GS-NS0 Cells

    PubMed Central

    García Münzer, David G.; Kostoglou, Margaritis; Georgiadis, Michael C.; Pistikopoulos, Efstratios N.; Mantalaris, Athanasios

    2015-01-01

    Mammalian cell cultures are intrinsically heterogeneous at different scales (molecular to bioreactor). The cell cycle is at the centre of capturing heterogeneity since it plays a critical role in the growth, death, and productivity of mammalian cell cultures. Current cell cycle models use biological variables (mass/volume/age) that are non-mechanistic, and difficult to experimentally determine, to describe cell cycle transition and capture culture heterogeneity. To address this problem, cyclins—key molecules that regulate cell cycle transition—have been utilized. Herein, a novel integrated experimental-modelling platform is presented whereby experimental quantification of key cell cycle metrics (cell cycle timings, cell cycle fractions, and cyclin expression determined by flow cytometry) is used to develop a cyclin and DNA distributed model for the industrially relevant cell line, GS-NS0. Cyclins/DNA synthesis rates were linked to stimulatory/inhibitory factors in the culture medium, which ultimately affect cell growth. Cell antibody productivity was characterized using cell cycle-specific production rates. The solution method delivered fast computational time that renders the model’s use suitable for model-based applications. Model structure was studied by global sensitivity analysis (GSA), which identified parameters with a significant effect on the model output, followed by re-estimation of its significant parameters from a control set of batch experiments. A good model fit to the experimental data, both at the cell cycle and viable cell density levels, was observed. The cell population heterogeneity of disturbed (after cell arrest) and undisturbed cell growth was captured proving the versatility of the modelling approach. Cell cycle models able to capture population heterogeneity facilitate in depth understanding of these complex systems and enable systematic formulation of culture strategies to improve growth and productivity. It is envisaged that this

  1. The yeast cell-cycle network is robustly designed

    NASA Astrophysics Data System (ADS)

    Li, Fangting; Long, Tao; Lu, Ying; Ouyang, Qi; Tang, Chao

    2004-04-01

    The interactions between proteins, DNA, and RNA in living cells constitute molecular networks that govern various cellular functions. To investigate the global dynamical properties and stabilities of such networks, we studied the cell-cycle regulatory network of the budding yeast. With the use of a simple dynamical model, it was demonstrated that the cell-cycle network is extremely stable and robust for its function. The biological stationary state, the G1 state, is a global attractor of the dynamics. The biological pathway, the cell-cycle sequence of protein states, is a globally attracting trajectory of the dynamics. These properties are largely preserved with respect to small perturbations to the network. These results suggest that cellular regulatory networks are robustly designed for their functions.

  2. Cell cycling with the SEB: a personal view.

    PubMed

    Bryant, John

    2014-06-01

    This review, written from a personal perspective, traces firstly the development of plant cell cycle research from the 1970s onwards, with some focus on the work of the author and of Dr Dennis Francis. Secondly there is a discussion of the support for and discussion of plant cell cycle research in the SEB, especially through the activities of the Cell Cycle Group within the Society's Cell Biology Section. In the main part of the review, selected aspects of DNA replication that have of been of special interest to the author are discussed. These are DNA polymerases and associated proteins, pre-replication events, regulation of enzymes and other proteins, nature and activation of DNA replication origins, and DNA endoreduplication. For all these topics, there is mention of the author's own work, followed by a brief synthesis of current understanding and a look to possible future developments.

  3. Digital Holographic Microscopy for Non-Invasive Monitoring of Cell Cycle Arrest in L929 Cells

    PubMed Central

    Falck Miniotis, Maria; Mukwaya, Anthonny; Gjörloff Wingren, Anette

    2014-01-01

    Digital holographic microscopy (DHM) has emerged as a powerful non-invasive tool for cell analysis. It has the capacity to analyse multiple parameters simultaneously, such as cell- number, confluence and phase volume. This is done while cells are still adhered and growing in their culture flask. The aim of this study was to investigate whether DHM was able to monitor drug-induced cell cycle arrest in cultured cells and thus provide a non-disruptive alternative to flow cytometry. DHM parameters from G1 and G2/M cell cycle arrested L929 mouse fibroblast cells were collected. Cell cycle arrest was verified with flow cytometry. This study shows that DHM is able to monitor phase volume changes corresponding to either a G1 or G2/M cell cycle arrest. G1-phase arrest with staurosporine correlated with a decrease in the average cell phase volume and G2/M-phase arrest with colcemid and etoposide correlated with an increase in the average cell phase volume. Importantly, DHM analysis of average cell phase volume was of comparable accuracy to flow cytometric measurement of cell cycle phase distribution as recorded following dose-dependent treatment with etoposide. Average cell phase volume changes in response to treatment with cell cycle arresting compounds could therefore be used as a DHM marker for monitoring cell cycle arrest in cultured mammalian cells. PMID:25208094

  4. Cell cycle regulation by the bacterial nucleoid.

    PubMed

    Adams, David William; Wu, Ling Juan; Errington, Jeff

    2014-12-01

    Division site selection presents a fundamental challenge to all organisms. Bacterial cells are small and the chromosome (nucleoid) often fills most of the cell volume. Thus, in order to maximise fitness and avoid damaging the genetic material, cell division must be tightly co-ordinated with chromosome replication and segregation. To achieve this, bacteria employ a number of different mechanisms to regulate division site selection. One such mechanism, termed nucleoid occlusion, allows the nucleoid to protect itself by acting as a template for nucleoid occlusion factors, which prevent Z-ring assembly over the DNA. These factors are sequence-specific DNA-binding proteins that exploit the precise organisation of the nucleoid, allowing them to act as both spatial and temporal regulators of bacterial cell division. The identification of proteins responsible for this process has provided a molecular understanding of nucleoid occlusion but it has also prompted the realisation that substantial levels of redundancy exist between the diverse systems that bacteria employ to ensure that division occurs in the right place, at the right time.

  5. CIRCADIAN CLOCK AND CELL CYCLE GENE EXPRESSION

    PubMed Central

    Metz, Richard P.; Qu, Xiaoyu; Laffin, Brian; Earnest, David; Porter, Weston W.

    2009-01-01

    Mouse mammary epithelial cells (HC-11) and mammary tissues were analyzed for developmental changes in circadian clock, cellular proliferation and differentiation marker genes. Expression of the clock genes, Per1 and Bmal1, were elevated in differentiated HC-11 cells whereas Per2 mRNA levels were higher in undifferentiated cells. This differentiation-dependent profile of clock gene expression was consistent with that observed in mouse mammary glands as Per1 and Bmal1 mRNA levels were elevated in late pregnant and lactating mammary tissues, while Per2 expression was higher in proliferating virgin and early pregnant glands. In both HC-11 cells and mammary glands, elevated Per2 expression was positively correlated with c-Myc and Cyclin D1 mRNA levels while Per1 and Bmal1 expression changed in conjunction with ß-casein mRNA levels. Interestingly, developmental stage had differential effects on rhythms of clock gene expression in the mammary gland. These data suggest that circadian clock genes may play a role in mouse mammary gland development and differentiation. PMID:16261617

  6. Alteration of Cell Cycle Mediated by Zinc in Human Bronchial ...

    EPA Pesticide Factsheets

    Zinc (Zn2+), a ubiquitous ambient air contaminant, presents an oxidant challenge to the human lung and is linked to adverse human health effects. To further elucidate the adaptive and apoptotic cellular responses of human airway cells to Zn2+, we performed pilot studies to examine cell cycle perturbation upon exposure using a normal human bronchial epithelial cell culture (BEAS-2B). BEAS-2B cells were treated with low (0, 1, 2 µM) and apoptotic (3 µM) doses of Zn2+ plus 1 µM pyrithione, a Zn2+-specific ionophore facilitating cellular uptake, for up to 24 h. Fixed cells were then stained with propidium iodine (PI) and cell cycle phase was determined by fluorescent image cytometry. Initial results report the percentage of cells in the S phase after 18 h exposure to 1, 2, and 3 µM Zn2+ were similar (8%, 7%, and 12%, respectively) compared with 7% in controls. Cells exposed to 3 µM Zn2+ increased cell populations in G2/M phase (76% versus 68% in controls). Interestingly, exposure to 1 µM Zn2+ resulted in decreased (59%) cells in G2/M. While preliminary, these pilot studies suggest Zn2+ alters cell cycle in BEAS-2B cells, particularly in the G2/M phase. The G2/M checkpoint maintains DNA integrity by enabling initiation of DNA repair or apoptosis. Our findings suggest that the adaptive and apoptotic responses to Zn2+ exposure may be mediated via perturbation of the cell cycle at the G2/M checkpoint. This work was a collaborative summer student project. The st

  7. Establishment of Human Papillomavirus Infection Requires Cell Cycle Progression

    PubMed Central

    Pyeon, Dohun; Pearce, Shane M.; Lank, Simon M.; Ahlquist, Paul; Lambert, Paul F.

    2009-01-01

    Human papillomaviruses (HPVs) are DNA viruses associated with major human cancers. As such there is a strong interest in developing new means, such as vaccines and microbicides, to prevent HPV infections. Developing the latter requires a better understanding of the infectious life cycle of HPVs. The HPV infectious life cycle is closely linked to the differentiation state of the stratified epithelium it infects, with progeny virus only made in the terminally differentiating suprabasal compartment. It has long been recognized that HPV must first establish its infection within the basal layer of stratified epithelium, but why this is the case has not been understood. In part this restriction might reflect specificity of expression of entry receptors. However, this hypothesis could not fully explain the differentiation restriction of HPV infection, since many cell types can be infected with HPVs in monolayer cell culture. Here, we used chemical biology approaches to reveal that cell cycle progression through mitosis is critical for HPV infection. Using infectious HPV16 particles containing the intact viral genome, G1-synchronized human keratinocytes as hosts, and early viral gene expression as a readout for infection, we learned that the recipient cell must enter M phase (mitosis) for HPV infection to take place. Late M phase inhibitors had no effect on infection, whereas G1, S, G2, and early M phase cell cycle inhibitors efficiently prevented infection. We conclude that host cells need to pass through early prophase for successful onset of transcription of the HPV encapsidated genes. These findings provide one reason why HPVs initially establish infections in the basal compartment of stratified epithelia. Only this compartment of the epithelium contains cells progressing through the cell cycle, and therefore it is only in these cells that HPVs can establish their infection. By defining a major condition for cell susceptibility to HPV infection, these results also have

  8. Choreography of the Mycobacterium Replication Machinery during the Cell Cycle

    PubMed Central

    Trojanowski, Damian; Ginda, Katarzyna; Pióro, Monika; Hołówka, Joanna; Skut, Partycja; Jakimowicz, Dagmara

    2015-01-01

    ABSTRACT It has recently been demonstrated that bacterial chromosomes are highly organized, with specific positioning of the replication initiation region. Moreover, the positioning of the replication machinery (replisome) has been shown to be variable and dependent on species-specific cell cycle features. Here, we analyzed replisome positions in Mycobacterium smegmatis, a slow-growing bacterium that exhibits characteristic asymmetric polar cell extension. Time-lapse fluorescence microscopy analyses revealed that the replisome is slightly off-center in mycobacterial cells, a feature that is likely correlated with the asymmetric growth of Mycobacterium cell poles. Estimates of the timing of chromosome replication in relation to the cell cycle, as well as cell division and chromosome segregation events, revealed that chromosomal origin-of-replication (oriC) regions segregate soon after the start of replication. Moreover, our data demonstrate that organization of the chromosome by ParB determines the replisome choreography. PMID:25691599

  9. Neuronal cell cycle: the neuron itself and its circumstances.

    PubMed

    Frade, José M; Ovejero-Benito, María C

    2015-01-01

    Neurons are usually regarded as postmitotic cells that undergo apoptosis in response to cell cycle reactivation. Nevertheless, recent evidence indicates the existence of a defined developmental program that induces DNA replication in specific populations of neurons, which remain in a tetraploid state for the rest of their adult life. Similarly, de novo neuronal tetraploidization has also been described in the adult brain as an early hallmark of neurodegeneration. The aim of this review is to integrate these recent developments in the context of cell cycle regulation and apoptotic cell death in neurons. We conclude that a variety of mechanisms exists in neuronal cells for G1/S and G2/M checkpoint regulation. These mechanisms, which are connected with the apoptotic machinery, can be modulated by environmental signals and the neuronal phenotype itself, thus resulting in a variety of outcomes ranging from cell death at the G1/S checkpoint to full proliferation of differentiated neurons.

  10. Changing gears in the cell cycle: histoblasts and beyond.

    PubMed

    Ninov, Nikolay; Martín-Blanco, Enrique

    2009-01-01

    Although the molecular elements controlling cell cycle progression are well established, the mechanisms regulating how cell proliferation is triggered in response to extrinsic stimuli and how cell divisions change speed, particularly in stem or tumor cells or regenerative tissues, are poorly understood. One exceptional model system in which these events are precisely defined is Drosophila abdominal morphogenesis, in which stem-like histoblasts build the adult epidermis at metamorphosis by undergoing a series of sequential transitions from a non-proliferative to a growing, and finally to an invasive epithelium. We have recently uncovered in histoblasts an internal logic modulating cell cycle transitions that should constitute a reference paradigm for the study of other equivalent processes in stem cell, cancer or developmental biology.

  11. Cell Cycle Regulation of Estrogen and Androgen Receptor

    DTIC Science & Technology

    2002-07-01

    Estrogen and Androgen Receptor PRINCIPAL INVESTIGATOR: Elisabeth D. Martinez CONTRACTING ORGANIZATION: Georgetown University Medical Center...Cycle Regulation of Estrogen and Androgen DAMD17-99-1-9199 Receptor 6. AUTHOR(S) Elisabeth D. Martinez 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES...with androgens. 14. SUBJECT TERMS 15. NUMBER OF PAGES breast cancer, cell cycle, androgen receptor, estrogen receptor, non- 66 steroidal activators, L

  12. Bcl-2 delays cell cycle through mitochondrial ATP and ROS.

    PubMed

    Du, Xing; Fu, Xufeng; Yao, Kun; Lan, Zhenwei; Xu, Hui; Cui, Qinghua; Yang, Elizabeth

    2017-02-22

    Bcl-2 inhibits cell proliferation by delaying G0/G1 to S phase entry. We tested the hypothesis that Bcl-2 regulates S phase entry through mitochondrial pathways. Existing evidence indicates mitochondrial adenosine tri-phosphate (ATP) and reactive oxygen species (ROS) are important signals in cell survival and cell death, however, the molecular details of how these 2 processes are linked remain unknown. In this study, 2 cell lines stably expressing Bcl-2, 3T3Bcl-2 and C3HBcl-2, and vector-alone PB controls were arrested in G0/G1 phase by serum starvation and contact inhibition, and ATP and ROS were measured during re-stimulation of cell cycle entry. Both ATP and ROS levels were decreased in G0/G1 arrested cells compared with normal growing cells. In addition, ROS levels were significant lower in synchronized Bcl-2 cells than those in PB controls. After re-stimulation, ATP levels increased with time, reaching peak value 1-3 hours ahead of S phase entry for both Bcl-2 cells and PB controls. Consistent with 2 hours of S phase delay, Bcl-2 cells reached ATP peaks 2 hours later than PB control, which suggests a rise in ATP levels is required for S phase entry. To examine the role of ATP and ROS in cell cycle regulation, ATP and ROS level were changed. We observed that elevation of ATP accelerated cell cycle progression in both PB and Bcl-2 cells, and decrease of ATP and ROS to the level equivalent to Bcl-2 cells delayed S phase entry in PB cells. Our results support the hypothesis that Bcl-2 protein regulates mitochondrial metabolism to produce less ATP and ROS, which contributes to S phase entry delay in Bcl-2 cells. These findings reveal a novel mechanistic basis for understanding the link between mitochondrial metabolism and tumor-suppressive function of Bcl-2.

  13. Life-cycle costs of high-performance cells

    NASA Technical Reports Server (NTRS)

    Daniel, R.; Burger, D.; Reiter, L.

    1985-01-01

    A life cycle cost analysis of high efficiency cells was presented. Although high efficiency cells produce more power, they also cost more to make and are more susceptible to array hot-spot heating. Three different computer analysis programs were used: SAMICS (solar array manufacturing industry costing standards), PVARRAY (an array failure mode/degradation simulator), and LCP (lifetime cost and performance). The high efficiency cell modules were found to be more economical in this study, but parallel redundancy is recommended.

  14. A combined gas cooled nuclear reactor and fuel cell cycle

    NASA Astrophysics Data System (ADS)

    Palmer, David J.

    Rising oil costs, global warming, national security concerns, economic concerns and escalating energy demands are forcing the engineering communities to explore methods to address these concerns. It is the intention of this thesis to offer a proposal for a novel design of a combined cycle, an advanced nuclear helium reactor/solid oxide fuel cell (SOFC) plant that will help to mitigate some of the above concerns. Moreover, the adoption of this proposal may help to reinvigorate the Nuclear Power industry while providing a practical method to foster the development of a hydrogen economy. Specifically, this thesis concentrates on the importance of the U.S. Nuclear Navy adopting this novel design for its nuclear electric vessels of the future with discussion on efficiency and thermodynamic performance characteristics related to the combined cycle. Thus, the goals and objectives are to develop an innovative combined cycle that provides a solution to the stated concerns and show that it provides superior performance. In order to show performance, it is necessary to develop a rigorous thermodynamic model and computer program to analyze the SOFC in relation with the overall cycle. A large increase in efficiency over the conventional pressurized water reactor cycle is realized. Both sides of the cycle achieve higher efficiencies at partial loads which is extremely important as most naval vessels operate at partial loads as well as the fact that traditional gas turbines operating alone have poor performance at reduced speeds. Furthermore, each side of the cycle provides important benefits to the other side. The high temperature exhaust from the overall exothermic reaction of the fuel cell provides heat for the reheater allowing for an overall increase in power on the nuclear side of the cycle. Likewise, the high temperature helium exiting the nuclear reactor provides a controllable method to stabilize the fuel cell at an optimal temperature band even during transients helping

  15. Computation Molecular Kinetics Model of HZE Induced Cell Cycle Arrest

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Ren, Lei

    2004-01-01

    Cell culture models play an important role in understanding the biological effectiveness of space radiation. High energy and charge (HZE) ions produce prolonged cell cycle arrests at the G1/S and G2/M transition points in the cell cycle. A detailed description of these phenomena is needed to integrate knowledge of the expression of DNA damage in surviving cells, including the determination of relative effectiveness factors between different types of radiation that produce differential types of DNA damage and arrest durations. We have developed a hierarchical kinetics model that tracks the distribution of cells in various cell phase compartments (early G1, late G1, S, G2, and M), however with transition rates that are controlled by rate-limiting steps in the kinetics of cyclin-cdk's interactions with their families of transcription factors and inhibitor molecules. The coupling of damaged DNA molecules to the downstream cyclin-cdk inhibitors is achieved through a description of the DNA-PK and ATM signaling pathways. For HZE irradiations we describe preliminary results, which introduce simulation of the stochastic nature of the number of direct particle traversals per cell in the modulation of cyclin-cdk and cell cycle population kinetics. Comparison of the model to data for fibroblast cells irradiated photons or HZE ions are described.

  16. Labeling of lectin receptors during the cell cycle.

    PubMed

    Garrido, J

    1976-12-01

    Labeling of lectin receptors during the cell cycle. (Localizabión de receptores para lectinas durante el ciclo celular). Arch. Biol. Med. Exper. 10: 100-104, 1976. The topographic distribution of specific cell surface receptors for concanavalin A and wheat germ agglutinin was studied by ultrastructural labeling in the course of the cell cycle. C12TSV5 cells were synchronized by double thymidine block or mechanical selection (shakeoff). They were labeled by means of lectin-peroxidase techniques while in G1 S, G2 and M phases of the cycle. The results obtained were similar for both lectins employed. Interphase cells (G1 S, G2) present a stlihtly discontinous labeling pattern that is similar to the one observed on unsynchronized cells of the same line. Cells in mitosis, on the contrary, present a highly discontinous distribution of reaction product. This pattern disappears after the cells enters G1 and is not present on mitotic cells fixed in aldehyde prior to labeling.

  17. Thermal stress cycling of GaAs solar cells

    NASA Astrophysics Data System (ADS)

    Janousek, B. K.; Francis, R. W.; Wendt, J. P.

    A thermal cycling experiment was performed on GaAs solar cells to establish the electrical and structural integrity of these cells under the temperature conditions of a simulated low-Earth orbit of 3-year duration. Thirty single junction GaAs cells were obtained and tests were performed to establish the beginning-of-life characteristics of these cells. The tests consisted of cell I-V power output curves, from which were obtained short-circuit current, open circuit voltage, fill factor, and cell efficiency, and optical micrographs, spectral response, and ion microprobe mass analysis (IMMA) depth profiles on both the front surfaces and the front metallic contacts of the cells. Following 5,000 thermal cycles, the performance of the cells was reexamined in addition to any factors which might contribute to performance degradation. It is established that, after 5,000 thermal cycles, the cells retain their power output with no loss of structural integrity or change in physical appearance.

  18. Entrainability of cell cycle oscillator models with exponential growth of cell mass.

    PubMed

    Nakao, Mitsuyuki; Enkhkhudulmur, Tsog-Erdene; Katayama, Norihiro; Karashima, Akihiro

    2014-01-01

    Among various aspects of cell cycle, understanding synchronization mechanism of cell cycle is important because of the following reasons. (1)Cycles of cell assembly should synchronize to form an organ. (2) Synchronizing cell cycles are required to experimental analysis of regulatory mechanisms of cell cycles. (3) Cell cycle has a distinct phase relationship with the other biological rhythms such as circadian rhythm. However, forced as well as mutual entrainment mechanisms are not clearly known. In this study, we investigated entrainability of cell cycle models of yeast cell under the periodic forcing to both of the cell mass and molecular dynamics. Dynamics of models under study involve the cell mass growing exponentially. In our result, they are shown to allow only a limited frequency range for being entrained by the periodic forcing. In contrast, models with linear growth are shown to be entrained in a wider frequency range. It is concluded that if the cell mass is included in the cell cycle regulation, its entrainability is sensitive to a shape of growth curve assumed in the model.

  19. Environmental Factors Inducing Human Cancers

    PubMed Central

    Parsa, N

    2012-01-01

    Background An explosion of research has been done in discovering how human health is affected by environmental factors. I will discuss the impacts of environmental cancer causing factors and how they continue to cause multiple disruptions in cellular networking. Some risk factors may not cause cancer. Other factors initiate consecutive genetic mutations that would eventually alter the normal pathway of cellular proliferations and differentiation. Genetic mutations in four groups of genes; (Oncogenes, Tumor suppressor genes, Apoptosis genes and DNA repairing genes) play a vital role in altering the normal cell division. In recent years, molecular genetics have greatly increased our understanding of the basic mechanisms in cancer development and utilizing these molecular techniques for cancer screening, diagnosis, prognosis and therapies. Inhibition of carcinogenic exposures wherever possible should be the goal of cancer prevention programs to reduce exposures from all environmental carcinogens. PMID:23304670

  20. Coordinating cell polarity and cell cycle progression: what can we learn from flies and worms?

    PubMed

    Noatynska, Anna; Tavernier, Nicolas; Gotta, Monica; Pintard, Lionel

    2013-08-07

    Spatio-temporal coordination of events during cell division is crucial for animal development. In recent years, emerging data have strengthened the notion that tight coupling of cell cycle progression and cell polarity in dividing cells is crucial for asymmetric cell division and ultimately for metazoan development. Although it is acknowledged that such coupling exists, the molecular mechanisms linking the cell cycle and cell polarity machineries are still under investigation. Key cell cycle regulators control cell polarity, and thus influence cell fate determination and/or differentiation, whereas some factors involved in cell polarity regulate cell cycle timing and proliferation potential. The scope of this review is to discuss the data linking cell polarity and cell cycle progression, and the importance of such coupling for asymmetric cell division. Because studies in model organisms such as Caenorhabditis elegans and Drosophila melanogaster have started to reveal the molecular mechanisms of this coordination, we will concentrate on these two systems. We review examples of molecular mechanisms suggesting a coupling between cell polarity and cell cycle progression.

  1. Coordinating cell polarity and cell cycle progression: what can we learn from flies and worms?

    PubMed Central

    Noatynska, Anna; Tavernier, Nicolas; Gotta, Monica; Pintard, Lionel

    2013-01-01

    Spatio-temporal coordination of events during cell division is crucial for animal development. In recent years, emerging data have strengthened the notion that tight coupling of cell cycle progression and cell polarity in dividing cells is crucial for asymmetric cell division and ultimately for metazoan development. Although it is acknowledged that such coupling exists, the molecular mechanisms linking the cell cycle and cell polarity machineries are still under investigation. Key cell cycle regulators control cell polarity, and thus influence cell fate determination and/or differentiation, whereas some factors involved in cell polarity regulate cell cycle timing and proliferation potential. The scope of this review is to discuss the data linking cell polarity and cell cycle progression, and the importance of such coupling for asymmetric cell division. Because studies in model organisms such as Caenorhabditis elegans and Drosophila melanogaster have started to reveal the molecular mechanisms of this coordination, we will concentrate on these two systems. We review examples of molecular mechanisms suggesting a coupling between cell polarity and cell cycle progression. PMID:23926048

  2. High efficiency fuel cell/advanced turbine power cycles

    SciTech Connect

    Morehead, H.

    1995-10-19

    An outline of the Westinghouse high-efficiency fuel cell/advanced turbine power cycle is presented. The following topics are discussed: The Westinghouse SOFC pilot manufacturing facility, cell scale-up plan, pressure effects on SOFC power and efficiency, sureCell versus conventional gas turbine plants, sureCell product line for distributed power applications, 20 MW pressurized-SOFC/gas turbine power plant, 10 MW SOFC/CT power plant, sureCell plant concept design requirements, and Westinghouse SOFC market entry.

  3. Vertebrate Cell Cycle Modulates Infection by Protozoan Parasites

    NASA Astrophysics Data System (ADS)

    Dvorak, James A.; Crane, Mark St. J.

    1981-11-01

    Synchronized HeLa cell populations were exposed to Trypanosoma cruzi or Toxoplasma gondii, obligate intracellular protozoan parasites that cause Chagas' disease and toxoplasmosis, respectively, in humans. The ability of the two parasites to infect HeLa cells increased as the HeLa cells proceeded from the G1 phase to the S phase of their growth cycle and decreased as the cells entered G2-M. Characterization of the S-phase cell surface components responsible for this phenomenon could be beneficial in the development of vaccines against these parasitic diseases.

  4. The reproductive-cell cycle theory of aging: an update.

    PubMed

    Atwood, Craig S; Bowen, Richard L

    2011-01-01

    The Reproductive-Cell Cycle Theory posits that the hormones that regulate reproduction act in an antagonistic pleiotrophic manner to control aging via cell cycle signaling; promoting growth and development early in life in order to achieve reproduction, but later in life, in a futile attempt to maintain reproduction, become dysregulated and drive senescence. Since reproduction is the most important function of an organism from the perspective of the survival of the species, if reproductive-cell cycle signaling factors determine the rate of growth, determine the rate of development, determine the rate of reproduction, and determine the rate of senescence, then by definition they determine the rate of aging and thus lifespan. The theory is able to explain: 1) the simultaneous regulation of the rate of aging and reproduction as evidenced by the fact that environmental conditions and experimental interventions known to extend longevity are associated with decreased reproductive-cell cycle signaling factors, thereby slowing aging and preserving fertility in a hostile reproductive environment; 2) two phenomena that are closely related to species lifespan-the rate of growth and development and the ultimate size of the animal; 3). the apparent paradox that size is directly proportional to lifespan and inversely proportional to fertility between species but vice versa within a species; 4). how differing rates of reproduction between species is associated with differences in their lifespan; 5). why we develop aging-related diseases; and 6). an evolutionarily credible reason for why and how aging occurs-these hormones act in an antagonistic pleiotrophic manner via cell cycle signaling; promoting growth and development early in life in order to achieve reproduction, but later in life, in a futile attempt to maintain reproduction, become dysregulated and drive senescence (dyosis). In essence, the Reproductive-Cell Cycle Theory can explain aging in all sexually reproductive life

  5. Modelling cell cycle synchronisation in networks of coupled radial glial cells.

    PubMed

    Barrack, Duncan S; Thul, Rüdiger; Owen, Markus R

    2015-07-21

    Radial glial cells play a crucial role in the embryonic mammalian brain. Their proliferation is thought to be controlled, in part, by ATP mediated calcium signals. It has been hypothesised that these signals act to locally synchronise cell cycles, so that clusters of cells proliferate together, shedding daughter cells in uniform sheets. In this paper we investigate this cell cycle synchronisation by taking an ordinary differential equation model that couples the dynamics of intracellular calcium and the cell cycle and extend it to populations of cells coupled via extracellular ATP signals. Through bifurcation analysis we show that although ATP mediated calcium release can lead to cell cycle synchronisation, a number of other asynchronous oscillatory solutions including torus solutions dominate the parameter space and cell cycle synchronisation is far from guaranteed. Despite this, numerical results indicate that the transient and not the asymptotic behaviour of the system is important in accounting for cell cycle synchronisation. In particular, quiescent cells can be entrained on to the cell cycle via ATP mediated calcium signals initiated by a driving cell and crucially will cycle in near synchrony with the driving cell for the duration of neurogenesis. This behaviour is highly sensitive to the timing of ATP release, with release at the G1/S phase transition of the cell cycle far more likely to lead to near synchrony than release during mid G1 phase. This result, which suggests that ATP release timing is critical to radial glia cell cycle synchronisation, may help us to understand normal and pathological brain development.

  6. FOXM1 participates in PLK1-regulated cell cycle progression in renal cell cancer cells

    PubMed Central

    ZHANG, ZHE; ZHANG, GUOJUN; KONG, CHUIZE

    2016-01-01

    The regulation of entry into and progression through mitosis is important for cell proliferation. Polo-like kinase 1 (PLK1) is involved in multiple stages of mitosis. Forkhead box protein M1 (FOXM1) has multiple functions in tumorigenesis and, in elevated levels, is frequently associated with cancer progression. The present study reports that FOXM1, a substrate of PLK1, controls the transcription mechanism that mediates the PLK1-dependent regulation of the cell cycle. The present study investigated the expression of PLK1 and FOXM1 in the clear renal cell carcinoma 769-P and ACHN cell lines, and indicated that the expression of PLK1 and FOXM1 are correlated in human renal cell cancer cell lines and that the suppression of PLK1 may decrease the expression of FOXM1. The knockdown of FOXM1 or PLK1 in renal cell cancer cell lines caused cell cycle progression to be blocked. As a result, the present study indicated the involvement of FOXM1 in PLK1-regulated cell cycle progression. PMID:27073539

  7. Regulated protein kinases and phosphatases in cell cycle decisions.

    PubMed

    Novak, Bela; Kapuy, Orsolya; Domingo-Sananes, Maria Rosa; Tyson, John J

    2010-12-01

    Many aspects of cell physiology are controlled by protein kinases and phosphatases, which together determine the phosphorylation state of targeted substrates. Some of these target proteins are themselves kinases or phosphatases or other components of a regulatory network characterized by feedback and feed-forward loops. In this review we describe some common regulatory motifs involving kinases, phosphatases, and their substrates, focusing particularly on bistable switches involved in cellular decision processes. These general principles are applied to cell cycle transitions, with special emphasis on the roles of regulated phosphatases in orchestrating progression from one phase to the next of the DNA replication-division cycle.

  8. Impact of cell cycle delay on micronucleus frequency in TK6 cells.

    PubMed

    Sobol, Zhanna; Spellman, Richard A; Thiffeault, Catherine; Dobo, Krista L; Schuler, Maik

    2014-01-01

    Previous studies with TK6 cells have shown that extending the recovery period after pulse treatment allows for greater micronucleus expression for some compounds. This study explores the role of cell cycle delay in micronucleus expression after pulse treatment with three model genotoxins [mitomycin C, etoposide (ETOP), vinblastine]. Cells were treated for 4 hr and allowed to recover for 36 hr with samples removed at various time points during the recovery period and analyzed for cell cycle distribution, apoptosis and micronucleus frequency. Our results show that mitomycin C causes cell cycle delay for 20 hr after pulse treatment and cell cycle perturbation is no longer evident after 36 hr of recovery. The micronucleus frequency of cells sampled at 36 hr is doubled when compared with cells sampled at 20 hr after mitomycin C removal. When cells were treated with indirect acting genotoxins (ETOP, vinblastine), cell cycle perturbation was not observed at the 20 hr time point. Micronucleus frequency after treatment with either ETOP or vinblastine did not differ between the 20 hr and the 36 hr time point. All three compounds induced similar levels of apoptosis ranging from 4.5 to 5.6% with maximum induction occurring at the 36-hr time point. We conclude that TK6 cells exhibit extended cell cycle arrest after exposure to MMC and can go on to express micronuclei, after overcoming cell cycle arrest.

  9. Visualisation of cell cycle modifications by X-ray irradiation of single HeLa cells using fluorescent ubiquitination-based cell cycle indicators.

    PubMed

    Kaminaga, K; Noguchi, M; Narita, A; Sakamoto, Y; Kanari, Y; Yokoya, A

    2015-09-01

    To explore the effects of X-ray irradiation on mammalian cell cycle dynamics, single cells using the fluorescent ubiquitination-based cell cycle indicator (Fucci) technique were tracked. HeLa cells expressing Fucci were used to visualise cell cycle modifications induced by irradiation. After cultured HeLa-Fucci cells were exposed to 5 Gy X-rays, fluorescent cell images were captured every 20 min for 48 h using a fluorescent microscope. Time dependence of the fluorescence intensity of S/G2 cells was analysed to examine the cell cycle dynamics of irradiated and non-irradiated control cells. The results showed that irradiated cells could be divided into two populations: one with similar cell cycle dynamics to that of non-irradiated cells, and another displaying a prolonged G2 phase. Based on these findings, it is proposed in this article that an underlying switch mechanism is involved in cell cycle regulation and the G2/M checkpoint of HeLa cells.

  10. UV-induced changes in cell cycle and gene expression within rabbit lens epithelial cells

    SciTech Connect

    Sidjanin, D.; Grdina, D.; Woloschak, G.E.

    1994-11-01

    Damage to lens epithelial cells is a probable initiation process in cataract formation induced by ultraviolet radiation. These experiments investigated the ability of 254 nm radiation on cell cycle progression and gene expression in rabbit lens epithelial cell line N/N1003A. No changes in expression of c-fos, c-jun, alpha- tubulin, or vimentin was observed following UV exposure. Using flow cytometry, an accumulation of cells in G1/S phase of the cell cycle 1 hr following exposure. The observed changes in gene expression, especially the decreased histone transcripts reported here may play a role in UV induced inhibition of cell cycle progression.

  11. DREAMs make plant cells to cycle or to become quiescent.

    PubMed

    Magyar, Zoltán; Bögre, László; Ito, Masaki

    2016-12-01

    Cell cycle phase specific oscillation of gene transcription has long been recognized as an underlying principle for ordered processes during cell proliferation. The G1/S-specific and G2/M-specific cohorts of genes in plants are regulated by the E2F and the MYB3R transcription factors. Mutant analysis suggests that activator E2F functions might not be fully required for cell cycle entry. In contrast, the two activator-type MYB3Rs are part of positive feedback loops to drive the burst of mitotic gene expression, which is necessary at least to accomplish cytokinesis. Repressor MYB3Rs act outside the mitotic time window during cell cycle progression, and are important for the shutdown of mitotic genes to impose quiescence in mature organs. The two distinct classes of E2Fs and MYB3Rs together with the RETINOBLATOMA RELATED are part of multiprotein complexes that may be evolutionary related to what is known as DREAM complex in animals. In plants, there are multiple such complexes with distinct compositions and functions that may be involved in the coordinated cell cycle and developmental regulation of E2F targets and mitotic genes.

  12. Histone supply regulates S phase timing and cell cycle progression

    PubMed Central

    Günesdogan, Ufuk; Jäckle, Herbert; Herzig, Alf

    2014-01-01

    Eukaryotes package DNA into nucleosomes that contain a core of histone proteins. During DNA replication, nucleosomes are disrupted and re-assembled with newly synthesized histones and DNA. Despite much progress, it is still unclear why higher eukaryotes contain multiple core histone genes, how chromatin assembly is controlled, and how these processes are coordinated with cell cycle progression. We used a histone null mutation of Drosophila melanogaster to show that histone supply levels, provided by a defined number of transgenic histone genes, regulate the length of S phase during the cell cycle. Lack of de novo histone supply not only extends S phase, but also causes a cell cycle arrest during G2 phase, and thus prevents cells from entering mitosis. Our results suggest a novel cell cycle surveillance mechanism that monitors nucleosome assembly without involving the DNA repair pathways and exerts its effect via suppression of CDC25 phosphatase String expression. DOI: http://dx.doi.org/10.7554/eLife.02443.001 PMID:25205668

  13. RAD001 (everolimus) induces dose-dependent changes to cell cycle regulation and modifies the cell cycle response to vincristine.

    PubMed

    Saunders, P O; Weiss, J; Welschinger, R; Baraz, R; Bradstock, K F; Bendall, L J

    2013-10-01

    More than 50% of adults and ~20% of children with pre-B acute lymphoblastic leukemia (ALL) relapse following treatment. Dismal outcomes for patients with relapsed or refractory disease mandate novel approaches to therapy. We have previously shown that the combination of the mTOR inhibitor RAD001 (everolimus) and the chemotherapeutic agent vincristine increases the survival of non-obese diabetic/severe combined immuno-deficient (NOD/SCID) mice bearing human ALL xenografts. We have also shown that 16 μM RAD001 synergized with agents that cause DNA damage or microtubule disruption in pre-B ALL cells in vitro. Here, we demonstrate that RAD001 has dose-dependent effects on the cell cycle in ALL cells, with 1.5 μM RAD001 inhibiting pRb, Ki67 and PCNA expression and increasing G0/1 cell cycle arrest, whereas 16 μM RAD001 increases pRb, cyclin D1, Ki67 and PCNA, with no evidence of an accumulation of cells in G0/1. Transition from G2 into mitosis was promoted by 16 μM RAD001 with reduced phosphorylation of cdc2 in cells with 4 N DNA content. However, 16 μM RAD001 preferentially induced cell death in cells undergoing mitosis. When combined with vincristine, 16 μM RAD001 reduced the vincristine-induced accumulation of cells in mitosis, probably as a result of increased death in this population. Although 16 μM RAD001 weakly activated Chk1 and Chk2, it suppressed strong vincristine-induced activation of these cell cycle checkpoint regulators. We conclude that RAD001 enhances chemosensitivity at least in part through suppression of cell cycle checkpoint regulation in response to vincristine and increased progression from G2 into mitosis.

  14. High-resolution timing of cell cycle-regulated gene expression

    PubMed Central

    Rowicka, Maga; Kudlicki, Andrzej; Tu, Benjamin P.; Otwinowski, Zbyszek

    2007-01-01

    The eukaryotic cell division cycle depends on an intricate sequence of transcriptional events. Using an algorithm based on maximum-entropy deconvolution, and expression data from a highly synchronized yeast culture, we have timed the peaks of expression of transcriptionally regulated cell cycle genes to an accuracy of 2 min (≈1% of the cell cycle time). The set of 1,129 cell cycle-regulated genes was identified by a comprehensive analysis encompassing all available cell cycle yeast data sets. Our results reveal distinct subphases of the cell cycle undetectable by morphological observation, as well as the precise timeline of macromolecular complex assembly during key cell cycle events. PMID:17827275

  15. The Effect of Spaceflight on Cartilage Cell Cycle and Differentiation

    NASA Technical Reports Server (NTRS)

    Doty, Stephen B.; Stiner, Dalina; Telford, William G.

    2000-01-01

    In vivo studies have shown that spaceflight results in loss of bone and muscle. In an effort to understand the mechanisms of these changes, cell cultures of cartilage, bone and muscle have been subjected to spaceflight to study the microgravity effects on differentiated cells. However it now seems possible that the cell differentiation process itself may be the event(s) most affected by spaceflight. For example, osteoblast-like cells have been shown to have reduced cellular activity in microgravity due to an underdifferentiated state (Carmeliet, et al, 1997). And reduced human lymphocyte growth in spaceflight was related to increased apoptosis (Lewis, et al, 1998). Which brings us to the question of whether reduced cellular activity in space is due to an effect on the differentiated cell, an effect on the cell cycle and cell proliferation, or an effect on cell death. This question has not been specifically addressed on previous flights and was the question behind die present study.

  16. α-Mangostin Induces Apoptosis and Cell Cycle Arrest in Oral Squamous Cell Carcinoma Cell

    PubMed Central

    Kwak, Hyun-Ho; Park, Bong-Soo

    2016-01-01

    Mangosteen has long been used as a traditional medicine and is known to have antibacterial, antioxidant, and anticancer effects. Although the effects of α-mangostin, a natural compound extracted from the pericarp of mangosteen, have been investigated in many studies, there is limited data on the effects of the compound in human oral squamous cell carcinoma (OSCC). In this study, α-mangostin was assessed as a potential anticancer agent against human OSCC cells. α-Mangostin inhibited cell proliferation and induced cell death in OSCC cells in a dose- and time-dependent manner with little to no effect on normal human PDLF cells. α-Mangostin treatment clearly showed apoptotic evidences such as nuclear fragmentation and accumulation of annexin V and PI-positive cells on OSCC cells. α-Mangostin treatment also caused the collapse of mitochondrial membrane potential and the translocation of cytochrome c from the mitochondria into the cytosol. The expressions of the mitochondria-related proteins were activated by α-mangostin. Treatment with α-mangostin also induced G1 phase arrest and downregulated cell cycle-related proteins (CDK/cyclin). Hence, α-mangostin specifically induces cell death and inhibits proliferation in OSCC cells via the intrinsic apoptosis pathway and cell cycle arrest at the G1 phase, suggesting that α-mangostin may be an effective agent for the treatment of OSCC. PMID:27478478

  17. Effects of cell cycle noise on excitable gene circuits

    NASA Astrophysics Data System (ADS)

    Veliz-Cuba, Alan; Gupta, Chinmaya; Bennett, Matthew R.; Josić, Krešimir; Ott, William

    2016-12-01

    We assess the impact of cell cycle noise on gene circuit dynamics. For bistable genetic switches and excitable circuits, we find that transitions between metastable states most likely occur just after cell division and that this concentration effect intensifies in the presence of transcriptional delay. We explain this concentration effect with a three-states stochastic model. For genetic oscillators, we quantify the temporal correlations between daughter cells induced by cell division. Temporal correlations must be captured properly in order to accurately quantify noise sources within gene networks.

  18. Cell cycle-arrested tumor cells exhibit increased sensitivity towards TRAIL-induced apoptosis

    PubMed Central

    Ehrhardt, H; Wachter, F; Grunert, M; Jeremias, I

    2013-01-01

    Resting tumor cells represent a huge challenge during anticancer therapy due to their increased treatment resistance. TNF-related apoptosis-inducing ligand (TRAIL) is a putative future anticancer drug, currently in phases I and II clinical studies. We recently showed that TRAIL is able to target leukemia stem cell surrogates. Here, we tested the ability of TRAIL to target cell cycle-arrested tumor cells. Cell cycle arrest was induced in tumor cell lines and xenografted tumor cells in G0, G1 or G2 using cytotoxic drugs, phase-specific inhibitors or RNA interference against cyclinB and E. Biochemical or molecular arrest at any point of the cell cycle increased TRAIL-induced apoptosis. Accordingly, when cell cycle arrest was disabled by addition of caffeine, the antitumor activity of TRAIL was reduced. Most important for clinical translation, tumor cells from three children with B precursor or T cell acute lymphoblastic leukemia showed increased TRAIL-induced apoptosis upon knockdown of either cyclinB or cyclinE, arresting the cell cycle in G2 or G1, respectively. Taken together and in contrast to most conventional cytotoxic drugs, TRAIL exerts enhanced antitumor activity against cell cycle-arrested tumor cells. Therefore, TRAIL might represent an interesting drug to treat static-tumor disease, for example, during minimal residual disease. PMID:23744361

  19. Cell-cycle synchronisation of bloodstream forms of Trypanosoma brucei using Vybrant DyeCycle Violet-based sorting.

    PubMed

    Kabani, Sarah; Waterfall, Martin; Matthews, Keith R

    2010-01-01

    Studies on the cell-cycle of Trypanosoma brucei have revealed several unusual characteristics that differ from the model eukaryotic organisms. However, the inability to isolate homogenous populations of parasites in distinct cell-cycle stages has limited the analysis of trypanosome cell division and complicated the understanding of mutant phenotypes with possible impact on cell-cycle related events. Although hydroxyurea-induced cell-cycle arrest in procyclic and bloodstream forms has been applied recently with success, such block-release protocols can complicate the analysis of cell-cycle regulated events and have the potential to disrupt important cell-cycle checkpoints. An alternative approach based on flow cytometry of parasites stained with Vybrant DyeCycle Orange circumvents this problem, but is restricted to procyclic form parasites. Here, we apply Vybrant Dyecycle Violet staining coupled with flow cytometry to effectively select different cell-cycle stages of bloodstream form trypanosomes. Moreover, the sorted parasites remain viable, although synchrony is rapidly lost. This method enables cell-cycle enrichment of populations of trypanosomes in their mammal infective stage, particularly at the G1 phase.

  20. An adaptor hierarchy regulates proteolysis during a bacterial cell cycle

    PubMed Central

    Joshi, Kamal Kishore; Bergé, Matthieu; Radhakrishnan, Sunish Kumar; Viollier, Patrick Henri; Chien, Peter

    2015-01-01

    Summary Regulated protein degradation is essential. The timed destruction of crucial proteins by the ClpXP protease drives cell-cycle progression in the bacterium Caulobacter crescentus. Although ClpXP is active alone, additional factors are inexplicably required for cell-cycle dependent proteolysis. Here, we show that these factors constitute an adaptor hierarchy where different substrates are destroyed based on the degree of adaptor assembly. The hierarchy builds upon priming of ClpXP by the adaptor CpdR, which promotes degradation of one class of substrates and also recruits the adaptor RcdA to degrade a second class of substrates. Adding the PopA adaptor promotes destruction of a third class of substrates, while inhibiting degradation of the second class. We dissect RcdA to generate bespoke adaptors, identifying critical substrate elements needed for RcdA recognition and uncovering additional cell-cycle dependent ClpXP substrates. Our work reveals how hierarchical adaptors and primed proteases orchestrate regulated proteolysis during bacterial cell-cycle progression. PMID:26451486

  1. Evaluation program for secondary spacecraft cells: Cycle life test

    NASA Technical Reports Server (NTRS)

    Harkness, J. D.

    1979-01-01

    The service life and storage stability for several storage batteries were determined. The batteries included silver-zinc batteries, nickel-cadmium batteries, and silver-cadmium batteries. The cell performance characteristics and limitations are to be used by spacecraft power systems planners and designers. A statistical analysis of the life cycle prediction and cause of failure versus test conditions is presented.

  2. Hydrogenosome behavior during the cell cycle in Tritrichomonas foetus.

    PubMed

    Benchimol, Marlene; Engelke, Flávio

    2003-07-01

    The hydrogenosome is an unusual organelle found in several trichomonad species and other protists living in oxygen poor or anoxic environments. The hydrogenosome behavior in the protist Tritrichomonas foetus, parasite of the urogenital tract of cattle, is reported here. The hydrogenosomes were followed by light and transmission electron microscopy during the whole cell cycle. Videomicroscopy, immunofluorescence microscopy, and immunocytochemistry were also used. It is shown that the hydrogenosomes divide at any phase of the cell cycle and that the organellar division is not synchronized. During the interphase the hydrogenosomes are distributed mainly along the axostyle and costa, and at the beginning of mitosis migrate to around the nucleus. Three forms of hydrogenosome division were seen: (1). segmentation, where elongated hydrogenosomes are further separated by external membranous profiles; (2). partition, where rounded hydrogenosomes, in a bulky form, are further separated by a membranous internal septum and, (3). a new dividing form: heart-shaped hydrogenosomes, which gradually present a membrane invagination leading to the organelle division. The hydrogenosomes divide at any phase of the cell cycle. A necklace of intramembranous particles delimiting the outer hydrogenosomal membrane in the region of organelle division was observed by freeze-etching. Similarities between hydrogenosomes and mitochondria behavior during the cell cycle are discussed.

  3. Cycle life status of SAFT VOS nickel-cadmium cells

    NASA Technical Reports Server (NTRS)

    Goualard, Jacques

    1993-01-01

    The SAFT prismatic VOS Ni-Cd cells have been flown in geosynchronous orbit since 1977 and in low earth orbit since 1983. Parallel cycling tests are performed by several space agencies in order to determine the cycle life for a wide range of temperature and depth of discharge (DOD). In low Earth orbit (LEO), the ELAN program is conducted on 24 Ah cells by CNES and ESA at the European Battery Test Center at temperatures ranging from 0 to 27 C and DOD from 10 to 40 percent. Data are presented up to 37,000 cycles. One pack (X-80) has achieved 49,000 cycles at 10 C and 23 percent DOD. The geosynchronous orbit simulation of a high DOD test is conducted by ESA on 3 batteries at 10 C and 70, 90, and 100 percent DOD. Thirty-one eclipse seasons are completed, and no signs of degradation have been found. The Air Force test at CRANE on 24 Ah and 40 Ah cells at 20 C and 80 percent DOD has achieved 19 shadow periods. Life expectancy is discussed. The VOS cell technology could be used for the following: (1) in geosynchronous conditions--15 yrs at 10-15 C and 80 percent DOD; and (2) in low earth orbit--10 yrs at 5-15 C and 25-30 percent DOD.

  4. Visualizing cell-cycle kinetics after hypoxia/reoxygenation in HeLa cells expressing fluorescent ubiquitination-based cell cycle indicator (Fucci).

    PubMed

    Goto, Tatsuaki; Kaida, Atsushi; Miura, Masahiko

    2015-12-10

    Hypoxia induces G1 arrest in many cancer cell types. Tumor cells are often exposed to hypoxia/reoxygenation, especially under acute hypoxic conditions in vivo. In this study, we investigated cell-cycle kinetics and clonogenic survival after hypoxia/reoxygenation in HeLa cells expressing fluorescent ubiquitination-based cell cycle indicator (Fucci). Hypoxic treatment halted cell-cycle progression during mid-S to G2 phase, as determined by the cell cycle-regulated E3 ligase activities of SCF(Skp2) and APC/C(Cdh1), which are regulators of the Fucci probes; however, the DNA content of the arrested cells was equivalent to that in G1 phase. After reoxygenation, time-lapse imaging and DNA content analysis revealed that all cells reached G2 phase, and that Fucci fluorescence was distinctly separated into two fractions 24h after reoxygenation: red cells that released from G2 arrest after repairing DNA double-strand breaks (DSBs) exhibited higher clonogenic survival, whereas most cells that stayed green contained many DSBs and exhibited lower survival. We conclude that hypoxia disrupts coordination of DNA synthesis and E3 ligase activities associated with cell-cycle progression, and that DSB repair could greatly influence cell-cycle kinetics and clonogenic survival after hypoxia/reoxygenation.

  5. Cell cycle-dependent radiosensitivity in two-cell mouse embryos in culture

    SciTech Connect

    Domon, M.

    1980-02-01

    The radiosensitivity in embryo systems varies depending on factors such as genetic background, oxygen environment, developmental stage, and age of the embryo in cell cycle. This paper is concerned with the involvement of cell cycle age in radiosensitivity of two-cell mouse embryos. Thus the doses needed for 50% killing of blastocyst formation in vitro (LD/sub 50/) of X rays for the two-cell mouse embryos in culture were measured during their cell cycle. The cell cycle in the two-cell embryos was quite peculiar; the cell cycle time of 18 h was divided into a long DNA post synthesis phase (G/sub 2/) plus mitosis (M) of 14 h and a short DNA synthesis phase (S) of 4 h. Results indicate that the LD/sub 50/ varies roughly from 100 to 600 rad within the cell cycle. Thus a major factor in determining the sensitivity to ionizing radiation of two-cell mouse embryos in vitro and perhaps in vivo is their position in the cell division cycle at the time of irradiation.

  6. Cell cycle analysis of fetal germ cells during sex differentiation in mice

    PubMed Central

    Spiller, Cassy; Wilhelm, Dagmar; Koopman, Peter

    2009-01-01

    Background information. Primordial germ cells in developing male and female gonads are responsive to somatic cell cues that direct their sex-specific differentiation into functional gametes. The first divergence of the male and female pathways is a change in cell cycle state observed from 12.5 dpc (days post coitum) in mice. At this time XY and XX germ cells cease mitotic division and enter G1/G0 arrest and meiosis prophase I respectively. Aberrant cell cycle regulation at this time can lead to disrupted ovarian development, germ cell apoptosis, reduced fertility and/or the formation of germ cell tumours. Results. In order to unravel the mechanisms utilized by germ cells to achieve and maintain the correct cell cycle states, we analysed the expression of a large number of cell cycle genes in purified germ cells across the crucial time of sex differentiation. Our results revealed common signalling for both XX and XY germ cell survival involving calcium signalling. A robust mechanism for apoptosis and checkpoint control was observed in XY germ cells, characterized by p53 and Atm (ataxia telangiectasia mutated) expression. Additionally, a member of the retinoblastoma family and p21 were identified, linking these factors to XY germ cell G1/G0 arrest. Lastly, in XX germ cells we observed a down-regulation of genes involved in both G1- and G2-phases of the cell cycle consistent with their entry into meiosis. Conclusion. The present study has provided a detailed analysis of cell cycle gene expression during fetal germ cell development and identified candidate factors warranting further investigation in order to understand cases of aberrant cell cycle control in these specialized cells. PMID:19419345

  7. Protein turnover in the cell cycle of Escherichia coli.

    PubMed

    Nishi, A; Kogoma, T

    1965-10-01

    Nishi, Arasuke (University of Tokyo, Tokyo, Japan), and Tokio Kogoma. Protein turnover in the cell cycle of Escherichia coli. J. Bacteriol. 90:884-890. 1965.-Protein metabolism and enzyme formation throughout the cell cycle were investigated in synchronized cultures of Escherichia coli. The cells showed a temporary cessation of the net increase of bulk protein and of constitutive beta-galactosidase activity during the division period. By contrast, when tested by short-term experiments performed with cells at different growth stages, the bacteria displayed a constant incorporation of labeled protein precursors into the protein fraction, even during the fission period. Similar results were obtained with respect to the capacities for induced enzyme formation. On the other hand, when the cells were previously labeled and then subjected to synchronization in a nonradioactive medium, the radioactivity of the protein fraction decreased temporarily by nearly 10% during the fission period and then regained its previous level at the beginning of the ensuing phase of growth. This indicates that the products of partial degradation of protein were again utilized for protein synthesis in the next cell cycle. It was concluded that the temporary lagging of net increase of bulk protein may be due to the partial breakdown of protein occurring during the fission period.

  8. Cell-cycle quiescence maintains Caenorhabditis elegans germline stem cells independent of GLP-1/Notch.

    PubMed

    Seidel, Hannah S; Kimble, Judith

    2015-11-09

    Many types of adult stem cells exist in a state of cell-cycle quiescence, yet it has remained unclear whether quiescence plays a role in maintaining the stem cell fate. Here we establish the adult germline of Caenorhabditis elegans as a model for facultative stem cell quiescence. We find that mitotically dividing germ cells--including germline stem cells--become quiescent in the absence of food. This quiescence is characterized by a slowing of S phase, a block to M-phase entry, and the ability to re-enter M phase rapidly in response to re-feeding. Further, we demonstrate that cell-cycle quiescence alters the genetic requirements for stem cell maintenance: The signaling pathway required for stem cell maintenance under fed conditions--GLP-1/Notch signaling--becomes dispensable under conditions of quiescence. Thus, cell-cycle quiescence can itself maintain stem cells, independent of the signaling pathway otherwise essential for such maintenance.

  9. Single cell studies of the cell cycle and some models

    PubMed Central

    Mitchison, JM

    2005-01-01

    Analysis of growth and division often involves measurements made on cell populations, which tend to average data. The value of single cell analysis needs to be appreciated, and models based on findings from single cells should be taken into greater consideration in our understanding of the way in which cell size and division are co-ordinated. Examples are given of some single cell analyses in mammalian cells, yeast and other microorganisms. There is also a short discussion on how far the results are in accord with simple models. PMID:15703075

  10. Instructive simulation of the bacterial cell division cycle.

    PubMed

    Zaritsky, Arieh; Wang, Ping; Vischer, Norbert O E

    2011-07-01

    The coupling between chromosome replication and cell division includes temporal and spatial elements. In bacteria, these have globally been resolved during the last 40 years, but their full details and action mechanisms are still under intensive study. The physiology of growth and the cell cycle are reviewed in the light of an established dogma that has formed a framework for development of new ideas, as exemplified here, using the Cell Cycle Simulation (CCSim) program. CCSim, described here in detail for the first time, employs four parameters related to time (replication, division and inter-division) and size (cell mass at replication initiation) that together are sufficient to describe bacterial cells under various conditions and states, which can be manipulated environmentally and genetically. Testing the predictions of CCSim by analysis of time-lapse micrographs of Escherichia coli during designed manipulations of the rate of DNA replication identified aspects of both coupling elements. Enhanced frequencies of cell division were observed following an interval of reduced DNA replication rate, consistent with the prediction of a minimum possible distance between successive replisomes (an eclipse). As a corollary, the notion that cell poles are not always inert was confirmed by observed placement of division planes at perpendicular planes in monstrous and cuboidal cells containing multiple, segregating nucleoids.

  11. Autophagy and the Cell Cycle: A Complex Landscape

    PubMed Central

    Mathiassen, Søs Grønbæk; De Zio, Daniela; Cecconi, Francesco

    2017-01-01

    Autophagy is a self-degradation pathway, in which cytoplasmic material is sequestered in double-membrane vesicles and delivered to the lysosome for degradation. Under basal conditions, autophagy plays a homeostatic function. However, in response to various stresses, the pathway can be further induced to mediate cytoprotection. Defective autophagy has been linked to a number of human pathologies, including neoplastic transformation, even though autophagy can also sustain the growth of tumor cells in certain contexts. In recent years, a considerable correlation has emerged between autophagy induction and stress-related cell-cycle responses, as well as unexpected roles for autophagy factors and selective autophagic degradation in the process of cell division. These advances have obvious implications for our understanding of the intricate relationship between autophagy and cancer. In this review, we will discuss our current knowledge of the reciprocal regulation connecting the autophagy pathway and cell-cycle progression. Furthermore, key findings involving nonautophagic functions for autophagy-related factors in cell-cycle regulation will be addressed.

  12. Cell Cycle Programs of Gene Expression Control Morphogenetic Protein Localization

    PubMed Central

    Lord, Matthew; Yang, Melody C.; Mischke, Michelle; Chant, John

    2000-01-01

    Genomic studies in yeast have revealed that one eighth of genes are cell cycle regulated in their expression. Almost without exception, the significance of cell cycle periodic gene expression has not been tested. Given that many such genes are critical to cellular morphogenesis, we wanted to examine the importance of periodic gene expression to this process. The expression profiles of two genes required for the axial pattern of cell division, BUD3 and BUD10/AXL2/SRO4, are strongly cell cycle regulated. BUD3 is expressed close to the onset of mitosis. BUD10 is expressed in late G1. Through promotor-swap experiments, the expression profile of each gene was altered and the consequences examined. We found that an S/G2 pulse of BUD3 expression controls the timing of Bud3p localization, but that this timing is not critical to Bud3p function. In contrast, a G1 pulse of BUD10 expression plays a direct role in Bud10p localization and function. Bud10p, a membrane protein, relies on the polarized secretory machinery specific to G1 to be delivered to its proper location. Such a secretion-based targeting mechanism for membrane proteins provides cells with flexibility in remodeling their architecture or evolving new forms. PMID:11134078

  13. Cell-cycle analyses using thymidine analogues in fission yeast.

    PubMed

    Anda, Silje; Boye, Erik; Grallert, Beata

    2014-01-01

    Thymidine analogues are powerful tools when studying DNA synthesis including DNA replication, repair and recombination. However, these analogues have been reported to have severe effects on cell-cycle progression and growth, the very processes being investigated in most of these studies. Here, we have analyzed the effects of 5-ethynyl-2'-deoxyuridine (EdU) and 5-Chloro-2'-deoxyuridine (CldU) using fission yeast cells and optimized the labelling procedure. We find that both analogues affect the cell cycle, but that the effects can be mitigated by using the appropriate analogue, short pulses of labelling and low concentrations. In addition, we report sequential labelling of two consecutive S phases using EdU and 5-bromo-2'-deoxyuridine (BrdU). Furthermore, we show that detection of replicative DNA synthesis is much more sensitive than DNA-measurements by flow cytometry.

  14. Dynamics of gene regulatory networks with cell division cycle

    NASA Astrophysics Data System (ADS)

    Chen, Luonan; Wang, Ruiqi; Kobayashi, Tetsuya J.; Aihara, Kazuyuki

    2004-07-01

    This paper focuses on modeling and analyzing the nonlinear dynamics of gene regulatory networks with the consideration of a cell division cycle with duplication process of DNA , in particular for switches and oscillators of synthetic networks. We derive two models that may correspond to the eukaryotic and prokaryotic cells, respectively. A biologically plausible three-gene model ( lac,tetR , and cI ) and a repressilator as switch and oscillator examples are used to illustrate our theoretical results. We show that the cell cycle may play a significant role in gene regulation due to the nonlinear dynamics of a gene regulatory network although gene expressions are usually tightly controlled by transcriptional factors.

  15. Piperlongumine Suppresses Proliferation of Human Oral Squamous Cell Carcinoma through Cell Cycle Arrest, Apoptosis and Senescence.

    PubMed

    Chen, San-Yuan; Liu, Geng-Hung; Chao, Wen-Ying; Shi, Chung-Sheng; Lin, Ching-Yen; Lim, Yun-Ping; Lu, Chieh-Hsiang; Lai, Peng-Yeh; Chen, Hau-Ren; Lee, Ying-Ray

    2016-04-23

    Oral squamous cell carcinoma (OSCC), an aggressive cancer originating in the oral cavity, is one of the leading causes of cancer deaths in males worldwide. This study investigated the antitumor activity and mechanisms of piperlongumine (PL), a natural compound isolated from Piper longum L., in human OSCC cells. The effects of PL on cell proliferation, the cell cycle, apoptosis, senescence and reactive oxygen species (ROS) levels in human OSCC cells were investigated. PL effectively inhibited cell growth, caused cell cycle arrest and induced apoptosis and senescence in OSCC cells. Moreover, PL-mediated anti-human OSCC behavior was inhibited by an ROS scavenger N-acetyl-l-cysteine (NAC) treatment, suggesting that regulation of ROS was involved in the mechanism of the anticancer activity of PL. These findings suggest that PL suppresses tumor growth by regulating the cell cycle and inducing apoptosis and senescence and is a potential chemotherapy agent for human OSCC cells.

  16. NSA2, a novel nucleolus protein regulates cell proliferation and cell cycle

    SciTech Connect

    Zhang, Heyu; Ma, Xi; Shi, Taiping; Song, Quansheng; Zhao, Hongshan; Ma, Dalong

    2010-01-01

    NSA2 (Nop seven-associated 2) was previously identified in a high throughput screen of novel human genes associated with cell proliferation, and the NSA2 protein is evolutionarily conserved across different species. In this study, we revealed that NSA2 is broadly expressed in human tissues and cultured cell lines, and located in the nucleolus of the cell. Both of the putative nuclear localization signals (NLSs) of NSA2, also overlapped with nucleolar localization signals (NoLSs), are capable of directing nucleolar accumulation. Moreover, over-expression of the NSA2 protein promoted cell growth in different cell lines and regulated the G1/S transition in the cell cycle. SiRNA silencing of the NSA2 transcript attenuated the cell growth and dramatically blocked the cell cycle in G1/S transition. Our results demonstrated that NSA2 is a nucleolar protein involved in cell proliferation and cell cycle regulation.

  17. Relation Between the Cell Volume and the Cell Cycle Dynamics in Mammalian cell

    NASA Astrophysics Data System (ADS)

    Magno, A. C. G.; Oliveira, I. L.; Hauck, J. V. S.

    2016-08-01

    The main goal of this work is to add and analyze an equation that represents the volume in a dynamical model of the mammalian cell cycle proposed by Gérard and Goldbeter (2011) [1]. The cell division occurs when the cyclinB/Cdkl complex is totally degraded (Tyson and Novak, 2011)[2] and it reaches a minimum value. At this point, the cell is divided into two newborn daughter cells and each one will contain the half of the cytoplasmic content of the mother cell. The equations of our base model are only valid if the cell volume, where the reactions occur, is constant. Whether the cell volume is not constant, that is, the rate of change of its volume with respect to time is explicitly taken into account in the mathematical model, then the equations of the original model are no longer valid. Therefore, every equations were modified from the mass conservation principle for considering a volume that changes with time. Through this approach, the cell volume affects all model variables. Two different dynamic simulation methods were accomplished: deterministic and stochastic. In the stochastic simulation, the volume affects every model's parameters which have molar unit, whereas in the deterministic one, it is incorporated into the differential equations. In deterministic simulation, the biochemical species may be in concentration units, while in stochastic simulation such species must be converted to number of molecules which are directly proportional to the cell volume. In an effort to understand the influence of the new equation a stability analysis was performed. This elucidates how the growth factor impacts the stability of the model's limit cycles. In conclusion, a more precise model, in comparison to the base model, was created for the cell cycle as it now takes into consideration the cell volume variation

  18. Effects of c-myc expression on cell cycle progression.

    PubMed Central

    Hanson, K D; Shichiri, M; Follansbee, M R; Sedivy, J M

    1994-01-01

    We used targeted homologous recombination to disrupt one c-myc gene copy in a diploid fibroblast cell line and found that a twofold reduction in Myc expression resulted in lower exponential growth rates and a lengthening of the G0-to-S-phase transition (M. Shichiri, K. D. Hanson and J. M. Sedivy, Cell Growth Differ. 4:93-104, 1993). Myc is a transcription factor, and the number of target genes whose regulation could result in differential growth rates may be very large. We have approached this problem by examining effects of reduced c-myc expression in three broad areas: (i) secretion of growth factors, (ii) expression of growth factor receptors, and (iii) intracellular signal transduction between Myc and components of the intrinsic cell cycle clock. We have found no evidence that differential medium conditioning can account for the growth phenotypes. Likewise, the expression of receptors for platelet-derived growth factor, epidermal growth factor, basic fibroblast growth factor, and insulin-like growth factor I was the same in diploid and heterozygous cells (platelet-derived growth factor, epidermal growth factor, fibroblast growth factor, and insulin-like growth factor are the sole growth factors required by these cells for growth in serum-free medium). In contrast, expression of cyclin E, cyclin A, and Rb phosphorylation were delayed when quiescent c-myc heterozygous cells were stimulated to enter the cell cycle. Expression of cyclin D1, cyclin D3, and Cdk2 was not affected. The timing of cyclin E induction was the earliest observable effect of reduced Myc expression. Our data indicate that Myc contributes to regulation of proliferation by a cell-autonomous mechanism that involves the modulation of cyclin E expression and, consequently, progression through the restriction point of the cell cycle. Images PMID:8065309

  19. High efficiency carbonate fuel cell/turbine hybrid power cycles

    SciTech Connect

    Steinfeld, G.

    1995-10-19

    Carbonate fuel cells developed by Energy Research Corporation, in commercial 2.85 MW size, have an efficiency of 57.9 percent. Studies of higher efficiency hybrid power cycles were conducted in cooperation with METC to identify an economically competitive system with an efficiency in excess of 65 percent. A hybrid power cycle was identified that includes a direct carbonate fuel cell, a gas turbine and a steam cycle, which generates power at a LHV efficiency in excess of 70 percent. This new system is called a Tandem Technology Cycle (TTC). In a TTC operating on natural gas fuel, 95 percent of the fuel is mixed with recycled fuel cell anode exhaust, providing water for the reforming of the fuel, and flows to a direct carbonate fuel cell system which generates 72 percent of the power. The portion of the fuel cell anode exhaust which is not recycled, is burned and heat is transferred to the compressed air from a gas turbine, raising its temperature to 1800{degrees}F. The stream is then heated to 2000{degrees}F in the gas turbine burner and expands through the turbine generating 13 percent of the power. Half the exhaust from the gas turbine flows to the anode exhaust burner, and the remainder flows to the fuel cell cathodes providing the O{sub 2} and CO{sub 2} needed in the electrochemical reaction. Exhaust from the fuel cells flows to a steam system which includes a heat recovery steam generator and stages steam turbine which generates 15 percent of the TTC system power. Studies of the TTC for 200-MW and 20-MW size plants quantified performance, emissions and cost-of-electricity, and compared the characteristics of the TTC to gas turbine combined cycles. A 200-MW TTC plant has an efficiency of 72.6 percent, and is relatively insensitive to ambient temperature, but requires a heat exchanger capable of 2000{degrees}F. The estimated cost of electricity is 45.8 mills/kWhr which is not competitive with a combined cycle in installations where fuel cost is under $5.8/MMBtu.

  20. Modeling circadian clock-cell cycle interaction effects on cell population growth rates.

    PubMed

    El Cheikh, R; Bernard, S; El Khatib, N

    2014-12-21

    The circadian clock and the cell cycle are two tightly coupled oscillators. Recent analytical studies have shown counter-intuitive effects of circadian gating of the cell cycle on growth rates of proliferating cells which cannot be explained by a molecular model or a population model alone. In this work, we present a combined molecular-population model that studies how coupling the circadian clock to the cell cycle, through the protein WEE1, affects a proliferating cell population. We show that the cell cycle can entrain to the circadian clock with different rational period ratios and characterize multiple domains of entrainment. We show that coupling increases the growth rate for autonomous periods of the cell cycle around 24 h and above 48 h. We study the effect of mutation of circadian genes on the growth rate of cells and show that disruption of the circadian clock can lead to abnormal proliferation. Particularly, we show that Cry 1, Cry 2 mutations decrease the growth rate of cells, Per 2 mutation enhances it and Bmal 1 knockout increases it for autonomous periods of the cell cycle less than 21 h and decreases it elsewhere. Combining a molecular model to a population model offers new insight on the influence of the circadian clock on the growth of a cell population. This can help chronotherapy which takes benefits of physiological rhythms to improve anti-cancer efficacy and tolerance to drugs by administering treatments at a specific time of the day.

  1. CELL CYCLE SYNCHRONIZATION OF MOUSE LIVER EPITHELIAL CELLS BY ELUTRIATION CENTRIFUGATION

    SciTech Connect

    Pearlman, Andrew L.; Bartholomew, James C.

    1980-06-01

    Detailed methods are described for the sorting and cell cycle synchronization by means of centrifugal elutriation of an established mouse liver epithelial cell line(NMuLi). In a comparison between three different elutriation media and between two different temperatures(4° and 20° C), the NMuLi cells were found to be most reproducibly sorted in the cell cycle when run in growth medium in the absence of serum and at the lower temperature. Under these conditions. and using decrements of rotor speed calculated from an empirically derived algorithm as described in the text an initially asynchronous population (38% G{sub 1}, 36% S, and 28% G{sub 2}M) was sorted into fractions enriched to 60% G{sub 1}, 75% S, and 50% G{sub 2}M. Of the cells loaded into the rotor, 30% were lost in the elutriation process, and about 20% recovered as aggregates. The remainder appeared in the various synchronized fractions. Epithelial cells sorted in this manner demonstrated no loss of viability, and upon replating showed significant movement in the cell cycle by 6 hrs post elutriation. The degree of synchronous movement through the cell cycle achieved by elutriation depended on the part of the cell cycle from which the original elutriated fraction came. Cells collected as late S and G{sub 2}M moved through the cell cycle with the tightest sychrony.

  2. Short-Stalked Prosthecomicrobium hirschii Cells Have a Caulobacter-Like Cell Cycle

    PubMed Central

    Williams, Michelle; Hoffman, Michelle D.; Daniel, Jeremy J.; Madren, Seth M.; Dhroso, Andi; Korkin, Dmitry; Givan, Scott A.; Jacobson, Stephen C.

    2016-01-01

    ABSTRACT The dimorphic alphaproteobacterium Prosthecomicrobium hirschii has both short-stalked and long-stalked morphotypes. Notably, these morphologies do not arise from transitions in a cell cycle. Instead, the maternal cell morphology is typically reproduced in daughter cells, which results in microcolonies of a single cell type. In this work, we further characterized the short-stalked cells and found that these cells have a Caulobacter-like life cycle in which cell division leads to the generation of two morphologically distinct daughter cells. Using a microfluidic device and total internal reflection fluorescence (TIRF) microscopy, we observed that motile short-stalked cells attach to a surface by means of a polar adhesin. Cells attached at their poles elongate and ultimately release motile daughter cells. Robust biofilm growth occurs in the microfluidic device, enabling the collection of synchronous motile cells and downstream analysis of cell growth and attachment. Analysis of a draft P. hirschii genome sequence indicates the presence of CtrA-dependent cell cycle regulation. This characterization of P. hirschii will enable future studies on the mechanisms underlying complex morphologies and polymorphic cell cycles. IMPORTANCE Bacterial cell shape plays a critical role in regulating important behaviors, such as attachment to surfaces, motility, predation, and cellular differentiation; however, most studies on these behaviors focus on bacteria with relatively simple morphologies, such as rods and spheres. Notably, complex morphologies abound throughout the bacteria, with striking examples, such as P. hirschii, found within the stalked Alphaproteobacteria. P. hirschii is an outstanding candidate for studies of complex morphology generation and polymorphic cell cycles. Here, the cell cycle and genome of P. hirschii are characterized. This work sets the stage for future studies of the impact of complex cell shapes on bacterial behaviors. PMID:26833409

  3. Astaxanthin Inhibits Proliferation and Induces Apoptosis and Cell Cycle Arrest of Mice H22 Hepatoma Cells

    PubMed Central

    Shao, Yiye; Ni, Yanbo; Yang, Jing; Lin, Xutao; Li, Jun; Zhang, Lixia

    2016-01-01

    Background It is widely recognized that astaxanthin (ASX), a member of the carotenoid family, has strong biological activities including antioxidant, anti-inflammation, and immune-modulation activities. Previous studies have confirmed that ASX can effectively inhibit hepatoma cells in vitro. Material/Methods MTT was used to assay proliferation of mice H22 cells, and flow cytometry was used to determine apoptosis and cell cycle arrest of H22 cells in vitro and in vivo. Moreover, anti-tumor activity of ASX was observed in mice. Results ASX inhibited the proliferation of H22 cells, promoted cell necrosis, and induced cell cycle arrest in G2 phase in vitro and in vivo. Conclusions This study indicated that ASX can inhibit proliferation and induce apoptosis and cell cycle arrest in mice H22 hepatoma cells in vitro and in vivo. PMID:27333866

  4. Molecular ties between the cell cycle and differentiation in embryonic stem cells.

    PubMed

    Li, Victor C; Kirschner, Marc W

    2014-07-01

    Attainment of the differentiated state during the final stages of somatic cell differentiation is closely tied to cell cycle progression. Much less is known about the role of the cell cycle at very early stages of embryonic development. Here, we show that molecular pathways involving the cell cycle can be engineered to strongly affect embryonic stem cell differentiation at early stages in vitro. Strategies based on perturbing these pathways can shorten the rate and simplify the lineage path of ES differentiation. These results make it likely that pathways involving cell proliferation intersect at various points with pathways that regulate cell lineages in embryos and demonstrate that this knowledge can be used profitably to guide the path and effectiveness of cell differentiation of pluripotent cells.

  5. SAMHD1 controls cell cycle status, apoptosis and HIV-1 infection in monocytic THP-1 cells.

    PubMed

    Bonifati, Serena; Daly, Michele B; St Gelais, Corine; Kim, Sun Hee; Hollenbaugh, Joseph A; Shepard, Caitlin; Kennedy, Edward M; Kim, Dong-Hyun; Schinazi, Raymond F; Kim, Baek; Wu, Li

    2016-08-01

    SAMHD1 limits HIV-1 infection in non-dividing myeloid cells by decreasing intracellular dNTP pools. HIV-1 restriction by SAMHD1 in these cells likely prevents activation of antiviral immune responses and modulates viral pathogenesis, thus highlighting a critical role of SAMHD1 in HIV-1 physiopathology. Here, we explored the function of SAMHD1 in regulating cell proliferation, cell cycle progression and apoptosis in monocytic THP-1 cells. Using the CRISPR/Cas9 technology, we generated THP-1 cells with stable SAMHD1 knockout. We found that silencing of SAMHD1 in cycling cells stimulates cell proliferation, redistributes cell cycle population in the G1/G0 phase and reduces apoptosis. These alterations correlated with increased dNTP levels and more efficient HIV-1 infection in dividing SAMHD1 knockout cells relative to control. Our results suggest that SAMHD1, through its dNTPase activity, affects cell proliferation, cell cycle distribution and apoptosis, and emphasize a key role of SAMHD1 in the interplay between cell cycle regulation and HIV-1 infection.

  6. SAMHD1 controls cell cycle status, apoptosis and HIV-1 infection in monocytic THP-1 cells

    SciTech Connect

    Bonifati, Serena; Daly, Michele B.; St Gelais, Corine; Kim, Sun Hee; Hollenbaugh, Joseph A.; Shepard, Caitlin; Kennedy, Edward M.; Kim, Dong-Hyun; Schinazi, Raymond F.; Kim, Baek; Wu, Li

    2016-08-15

    SAMHD1 limits HIV-1 infection in non-dividing myeloid cells by decreasing intracellular dNTP pools. HIV-1 restriction by SAMHD1 in these cells likely prevents activation of antiviral immune responses and modulates viral pathogenesis, thus highlighting a critical role of SAMHD1 in HIV-1 physiopathology. Here, we explored the function of SAMHD1 in regulating cell proliferation, cell cycle progression and apoptosis in monocytic THP-1 cells. Using the CRISPR/Cas9 technology, we generated THP-1 cells with stable SAMHD1 knockout. We found that silencing of SAMHD1 in cycling cells stimulates cell proliferation, redistributes cell cycle population in the G{sub 1}/G{sub 0} phase and reduces apoptosis. These alterations correlated with increased dNTP levels and more efficient HIV-1 infection in dividing SAMHD1 knockout cells relative to control. Our results suggest that SAMHD1, through its dNTPase activity, affects cell proliferation, cell cycle distribution and apoptosis, and emphasize a key role of SAMHD1 in the interplay between cell cycle regulation and HIV-1 infection.

  7. Size sensors in bacteria, cell cycle control, and size control.

    PubMed

    Robert, Lydia

    2015-01-01

    Bacteria proliferate by repetitive cycles of cellular growth and division. The progression into the cell cycle is admitted to be under the control of cell size. However, the molecular basis of this regulation is still unclear. Here I will discuss which mechanisms could allow coupling growth and division by sensing size and transmitting this information to the division machinery. Size sensors could act at different stages of the cell cycle. During septum formation, mechanisms controlling the formation of the Z ring, such as MinCD inhibition or Nucleoid Occlusion (NO) could participate in the size-dependence of the division process. In addition or alternatively, the coupling of growth and division may occur indirectly through the control of DNA replication initiation. The relative importance of these different size-sensing mechanisms could depend on the environmental and genetic context. The recent demonstration of an incremental strategy of size control in bacteria, suggests that DnaA-dependent control of replication initiation could be the major size control mechanism limiting cell size variation.

  8. Bioelectrical regulation of cell cycle and the planarian model system.

    PubMed

    Barghouth, Paul G; Thiruvalluvan, Manish; Oviedo, Néstor J

    2015-10-01

    Cell cycle regulation through the manipulation of endogenous membrane potentials offers tremendous opportunities to control cellular processes during tissue repair and cancer formation. However, the molecular mechanisms by which biophysical signals modulate the cell cycle remain underappreciated and poorly understood. Cells in complex organisms generate and maintain a constant voltage gradient across the plasma membrane known as the transmembrane potential. This potential, generated through the combined efforts of various ion transporters, pumps and channels, is known to drive a wide range of cellular processes such as cellular proliferation, migration and tissue regeneration while its deregulation can lead to tumorigenesis. These cellular regulatory events, coordinated by ionic flow, correspond to a new and exciting field termed molecular bioelectricity. We aim to present a brief discussion on the biophysical machinery involving membrane potential and the mechanisms mediating cell cycle progression and cancer transformation. Furthermore, we present the planarian Schmidtea mediterranea as a tractable model system for understanding principles behind molecular bioelectricity at both the cellular and organismal level. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

  9. Size sensors in bacteria, cell cycle control, and size control

    PubMed Central

    Robert, Lydia

    2015-01-01

    Bacteria proliferate by repetitive cycles of cellular growth and division. The progression into the cell cycle is admitted to be under the control of cell size. However, the molecular basis of this regulation is still unclear. Here I will discuss which mechanisms could allow coupling growth and division by sensing size and transmitting this information to the division machinery. Size sensors could act at different stages of the cell cycle. During septum formation, mechanisms controlling the formation of the Z ring, such as MinCD inhibition or Nucleoid Occlusion (NO) could participate in the size-dependence of the division process. In addition or alternatively, the coupling of growth and division may occur indirectly through the control of DNA replication initiation. The relative importance of these different size-sensing mechanisms could depend on the environmental and genetic context. The recent demonstration of an incremental strategy of size control in bacteria, suggests that DnaA-dependent control of replication initiation could be the major size control mechanism limiting cell size variation. PMID:26074903

  10. Bioelectrical Regulation of Cell Cycle and the Planarian Model System

    PubMed Central

    Barghouth, Paul G.; Thiruvalluvan, Manish; Oviedo, Néstor J.

    2015-01-01

    Cell cycle regulation through the manipulation of endogenous membrane potentials offers tremendous opportunities to control cellular processes during tissue repair and cancer formation. However, the molecular mechanisms by which biophysical signals modulate the cell cycle remain underappreciated and poorly understood. Cells in complex organisms generate and maintain a constant voltage gradient across the plasma membrane known as the transmembrane potential. This potential, generated through the combined efforts of various ion transporters, pumps and channels, is known to drive a wide range of cellular processes such as cellular proliferation, migration and tissue regeneration while its deregulation can lead to tumorigenesis. These cellular regulatory events, coordinated by ionic flow, correspond to a new and exciting field termed molecular bioelectricity. We aim to present a brief discussion on the biophysical machinery involving membrane potential and the mechanisms mediating cell cycle progression and cancer transformation. Furthermore, we present the planarian Schmidtea mediterranea as a tractable model system for understanding principles behind molecular bioelectricity at both the cellular and organismal level. PMID:25749155

  11. Cell Cycle Dependence of TRAIL Sensitivity in Prostate Cancer Cells

    DTIC Science & Technology

    2006-11-01

    or presence of proteasome inhibitors and measured HIF-1α levels by immunoblotting. We also incubated cells in cobalt chloride (to mimic hypoxia) in...Indistinguishable results were obtained in cells exposed to cobalt chloride . Figure 5: Effects of proteasome inhibitors on HIF- 1α promoter activity (LNCaP...havegenerated luciferase-transduced variants of our human prostate cancer cell lines in order touse them to generate orthotopic tumors in nude mice that can

  12. Tangeretin induces cell cycle arrest and apoptosis through upregulation of PTEN expression in glioma cells.

    PubMed

    Ma, Li-Li; Wang, Da-Wei; Yu, Xu-Dong; Zhou, Yan-Ling

    2016-07-01

    Tangeretin (TANG), present in peel of citrus fruits, has been shown to various medicinal properties such as chemopreventive and neuroprotective. However, the chemopreventive effect of TANG on glioblastoma cells has not been examined. The present study was designed to explore the anticancer potential of TANG in glioblastoma cells and to investigate the related mechanism. Human glioblastoma U-87MG and LN-18 cells were treated with 45μM concentration of TANG and cell growth was measured by MTT assay. The cell cycle distribution and cell death were measured by flow cytometry. The expression of cell cycle and apoptosis related genes were analyzed by quantitative RT-PCR and western blot. The cells treated with TANG were significantly increased cell growth suppression and cell death effects than vehicle treated cells. Further, TANG treatment increases G2/M arrest and apoptosis by modulating PTEN and cell-cycle regulated genes such as cyclin-D and cdc-2 mRNA and protein expressions. Moreover, the ability of TANG to decrease cell growth and to induce cell death was compromised when PTEN was knockdown by siRNA. Taken together, the chemopreventive effect of TANG is associated with regulation of cell-cycle and apoptosis in glioblastoma, thereby attenuating glioblastoma cell growth. Hence, the present findings suggest that TANG may be a therapeutic agent for glioblastoma treatment.

  13. Differential expression and alternative splicing of cell cycle genes in imatinib-treated K562 cells.

    PubMed

    Liu, Jing; Lin, Jin; Huang, Lin-Feng; Huang, Bo; Xu, Yan-Mei; Li, Jing; Wang, Yan; Zhang, Jing; Yang, Wei-Ming; Min, Qing-Hua; Wang, Xiao-Zhong

    2015-09-01

    Cancer progression often involves the disorder of the cell cycle, and a number of effective chemotherapeutic drugs have been shown to induce cell cycle arrest. The purpose of this study was to comprehensively investigate the effects of imatinib on the expression profile of cell cycle genes in the chronic myeloid leukemia (CML) K562 cell line. In addition, we also investigated alternative splicing of the cell cycle genes affected by imatinib, since an important relationship has been shown to exist between RNA splicing and cell cycle progression. Exon array analysis was performed using total RNA purified from normal and imatinib-treated K562 cells. We identified 185 differentially expressed genes and 277 alternative splicing events between the two cell groups. A detailed analysis by reverse transcription-PCR (RT-PCR) of key genes confirmed the experimental results of the exon array. These results suggested that treatment of K562 cells with imatinib shifts the expression and alternative splicing profiles of several cell cycle-related genes. Importantly, these findings may help improve imatinib treatment strategies in patients with CML and may be useful for imatinib resistance research and CML drug development.

  14. Live fast, die soon: cell cycle progression and lifespan in yeast cells

    PubMed Central

    Jiménez, Javier; Bru, Samuel; Ribeiro, Mariana; Clotet, Josep

    2015-01-01

    Our understanding of lifespan has benefited enormously from the study of a simple model, the yeast Saccharomyces cerevisiae. Although a unicellular organism, yeasts undergo many of the processes directly related with aging that to some extent are conserved in mammalian cells. Nutrient-limiting conditions have been involved in lifespan extension, especially in the case of caloric restriction, which also has a direct impact on cell cycle progression. In fact, other environmental stresses (osmotic, oxidative) that interfere with normal cell cycle progression also influence the lifespan of cells, indicating a relationship between lifespan and cell cycle control. In the present review we compile and discuss new findings related to how cell cycle progression is regulated by other nutrients. We centred this review on the analysis of phosphate, also give some attention to nitrogen, and the impact of these nutrients on lifespan. PMID:28357278

  15. Pharmacodynamic Modeling of Cell Cycle Effects for Gemcitabine and Trabectedin Combinations in Pancreatic Cancer Cells

    PubMed Central

    Miao, Xin; Koch, Gilbert; Ait-Oudhia, Sihem; Straubinger, Robert M.; Jusko, William J.

    2016-01-01

    Combinations of gemcitabine and trabectedin exert modest synergistic cytotoxic effects on two pancreatic cancer cell lines. Here, systems pharmacodynamic (PD) models that integrate cellular response data and extend a prototype model framework were developed to characterize dynamic changes in cell cycle phases of cancer cell subpopulations in response to gemcitabine and trabectedin as single agents and in combination. Extensive experimental data were obtained for two pancreatic cancer cell lines (MiaPaCa-2 and BxPC-3), including cell proliferation rates over 0–120 h of drug exposure, and the fraction of cells in different cell cycle phases or apoptosis. Cell cycle analysis demonstrated that gemcitabine induced cell cycle arrest in S phase, and trabectedin induced transient cell cycle arrest in S phase that progressed to G2/M phase. Over time, cells in the control group accumulated in G0/G1 phase. Systems cell cycle models were developed based on observed mechanisms and were used to characterize both cell proliferation and cell numbers in the sub G1, G0/G1, S, and G2/M phases in the control and drug-treated groups. The proposed mathematical models captured well both single and joint effects of gemcitabine and trabectedin. Interaction parameters were applied to quantify unexplainable drug-drug interaction effects on cell cycle arrest in S phase and in inducing apoptosis. The developed models were able to identify and quantify the different underlying interactions between gemcitabine and trabectedin, and captured well our large datasets in the dimensions of time, drug concentrations, and cellular subpopulations. PMID:27895579

  16. Local administration of granulocyte macrophage colony-stimulating factor induces local accumulation of dendritic cells and antigen-specific CD8+ T cells and enhances dendritic cell cross-presentation.

    PubMed

    Lee, Sung-Jong; Song, Liwen; Yang, Ming-Chieh; Mao, Chih-Ping; Yang, Benjamin; Yang, Andrew; Jeang, Jessica; Peng, Shiwen; Wu, T-C; Hung, Chien-Fu

    2015-03-24

    Immunotherapy has emerged as a promising treatment strategy for the control of HPV-associated malignancies. Various therapeutic HPV vaccines have elicited potent antigen-specific CD8+ T cell mediated antitumor immune responses in preclinical models and are currently being tested in several clinical trials. Recent evidence indicates the importance of local immune activation, and higher number of immune cells in the site of lesion correlates with positive prognosis. Granulocyte macrophage colony-stimulating factor (GMCSF) has been reported to posses the ability to induce migration of antigen presentation cells and CD8+ T cells. Therefore, in the current study, we employ a combination of systemic therapeutic HPV DNA vaccination with local GMCSF application in the TC-1 tumor model. We show that intramuscular vaccination with CRT/E7 DNA followed by GMCSF intravaginal administration effectively controls cervicovaginal TC-1 tumors in mice. Furthermore, we observe an increase in the accumulation of E7-specific CD8+ T cells and dendritic cells in vaginal tumors following the combination treatment. In addition, we show that GMCSF induces activation and maturation in dendritic cells and promotes antigen cross-presentation. Our results support the clinical translation of the combination treatment of systemic therapeutic vaccination followed by local GMCSF administration as an effective strategy for tumor treatment.

  17. Evidence for an interplay between cell cycle progression and the initiation of differentiation between life cycle forms of African trypanosomes

    PubMed Central

    1994-01-01

    Successful transmission of the African trypanosome between the mammalian host blood-stream and the tsetse fly vector involves dramatic alterations in the parasite's morphology and biochemistry. This differentiation through to the tsetse midgut procyclic form is accompanied by re-entry into a proliferative cell cycle. Using a synchronous differentiation model and a variety of markers diagnostic for progress through both differentiation and the cell cycle, we have investigated the interplay between these two processes. Our results implicate a relationship between the trypanosome cell cycle position and the perception of the differentiation signal and demonstrate that irreversible commitment to the differentiation occurs rapidly after induction. Furthermore, we show that re-entry into the cell cycle in the differentiating population is synchronous, and that once initiated, progress through the differentiation pathway can be uncoupled from progress through the cell cycle. PMID:8195296

  18. Computational analysis of mammalian cell division gated by a circadian clock: quantized cell cycles and cell size control.

    PubMed

    Zámborszky, Judit; Hong, Christian I; Csikász Nagy, Attila

    2007-12-01

    Cell cycle and circadian rhythms are conserved from cyanobacteria to humans with robust cyclic features. Recently, molecular links between these two cyclic processes have been discovered. Core clock transcription factors, Bmal1 and Clock (Clk), directly regulate Wee1 kinase, which inhibits entry into the mitosis. We investigate the effect of this connection on the timing of mammalian cell cycle processes with computational modeling tools. We connect a minimal model of circadian rhythms, which consists of transcription-translation feedback loops, with a modified mammalian cell cycle model from Novak and Tyson (2004). As we vary the mass doubling time (MDT) of the cell cycle, stochastic simulations reveal quantized cell cycles when the activity of Wee1 is influenced by clock components. The quantized cell cycles disappear in the absence of coupling or when the strength of this link is reduced. More intriguingly, our simulations indicate that the circadian clock triggers critical size control in the mammalian cell cycle. A periodic brake on the cell cycle progress via Wee1 enforces size control when the MDT is quite different from the circadian period. No size control is observed in the absence of coupling. The issue of size control in the mammalian system is debatable, whereas it is well established in yeast. It is possible that the size control is more readily observed in cell lines that contain circadian rhythms, since not all cell types have a circadian clock. This would be analogous to an ultradian clock intertwined with quantized cell cycles (and possibly cell size control) in yeast. We present the first coupled model between the mammalian cell cycle and circadian rhythms that reveals quantized cell cycles and cell size control influenced by the clock.

  19. [Integrins and cell cycle control by the environment].

    PubMed

    Bernard, A; Bernard, G

    2000-04-01

    Integrins insure cell adhesion to extra-cellular matrix components; they are thus involved in tissue architecture. They also can insure intercellular adhesions by binding to surface molecules from the immunoglobulin superfamily. Integrins binding to their ligands induce cytoskeleton reorganisation and, consequently, they gather into focal adhesion contacts. This greatly strenghthens mechanical forces. Nevertheless, integrins can also participate in cell locomotion and, moreover, tranduce within cells signals that can extensively influence cell metabolism, cell cycle and apoptosis. Doing so, they can interact with signals from other cellular receptors, such as soluble growth factors. They are therefore key molecules to integrate intrinsic and extrinsic events of the cellular behavior. They profoundly influence oncogenesis and the metastatic process.

  20. Cell cycle dependent changes in the plasma membrane organization of mammalian cells.

    PubMed

    Denz, Manuela; Chiantia, Salvatore; Herrmann, Andreas; Mueller, Peter; Korte, Thomas; Schwarzer, Roland

    2017-03-01

    Lipid membranes are major structural elements of all eukaryotic and prokaryotic organisms. Although many aspects of their biology have been studied extensively, their dynamics and lateral heterogeneity are still not fully understood. Recently, we observed a cell-to-cell variability in the plasma membrane organization of CHO-K1 cells (Schwarzer et al., 2014). We surmised that cell cycle dependent changes of the individual cells from our unsynchronized cell population account for this phenomenon. In the present study, this hypothesis was tested. To this aim, CHO-K1 cells were arrested in different cell cycle phases by chemical treatments, and the order of their plasma membranes was determined by various fluorescent lipid analogues using fluorescence lifetime imaging microscopy. Our experiments exhibit significant differences in the membrane order of cells arrested in the G2/M or S phase compared to control cells. Our single-cell analysis also enabled the specific selection of mitotic cells, which displayed a significant increase of the membrane order compared to the control. In addition, the lipid raft marker GPImYFP was used to study the lateral organization of cell cycle arrested cells as well as mitotic cells and freely cycling samples. Again, significant differences were found between control and arrested cells and even more pronounced between control and mitotic cells. Our data demonstrate a direct correlation between cell cycle progression and plasma membrane organization, underlining that cell-to-cell heterogeneities of membrane properties have to be taken into account in cellular studies especially at the single-cell level.

  1. Lineage correlations of single cell division time as a probe of cell-cycle dynamics.

    PubMed

    Sandler, Oded; Mizrahi, Sivan Pearl; Weiss, Noga; Agam, Oded; Simon, Itamar; Balaban, Nathalie Q

    2015-03-26

    Stochastic processes in cells are associated with fluctuations in mRNA, protein production and degradation, noisy partition of cellular components at division, and other cell processes. Variability within a clonal population of cells originates from such stochastic processes, which may be amplified or reduced by deterministic factors. Cell-to-cell variability, such as that seen in the heterogeneous response of bacteria to antibiotics, or of cancer cells to treatment, is understood as the inevitable consequence of stochasticity. Variability in cell-cycle duration was observed long ago; however, its sources are still unknown. A central question is whether the variance of the observed distribution originates from stochastic processes, or whether it arises mostly from a deterministic process that only appears to be random. A surprising feature of cell-cycle-duration inheritance is that it seems to be lost within one generation but to be still present in the next generation, generating poor correlation between mother and daughter cells but high correlation between cousin cells. This observation suggests the existence of underlying deterministic factors that determine the main part of cell-to-cell variability. We developed an experimental system that precisely measures the cell-cycle duration of thousands of mammalian cells along several generations and a mathematical framework that allows discrimination between stochastic and deterministic processes in lineages of cells. We show that the inter- and intra-generation correlations reveal complex inheritance of the cell-cycle duration. Finally, we build a deterministic nonlinear toy model for cell-cycle inheritance that reproduces the main features of our data. Our approach constitutes a general method to identify deterministic variability in lineages of cells or organisms, which may help to predict and, eventually, reduce cell-to-cell heterogeneity in various systems, such as cancer cells under treatment.

  2. Adolescent binge alcohol exposure alters hippocampal progenitor cell proliferation in rats: effects on cell cycle kinetics.

    PubMed

    McClain, Justin A; Hayes, Dayna M; Morris, Stephanie A; Nixon, Kimberly

    2011-09-01

    Binge alcohol exposure in adolescent rats potently inhibits adult hippocampal neurogenesis by altering neural progenitor cell (NPC) proliferation and survival; however, it is not clear whether alcohol results in an increase or decrease in net proliferation. Thus, the effects of alcohol on hippocampal NPC cell cycle phase distribution and kinetics were assessed in an adolescent rat model of an alcohol use disorder. Cell cycle distribution was measured using a combination of markers (Ki-67, bromodeoxyuridine incorporation, and phosphohistone H3) to determine the proportion of NPCs within G1, S, and G2/M phases of the cell cycle. Cell cycle kinetics were calculated using a cumulative bromodeoxyuridine injection protocol to determine the effect of alcohol on cell cycle length and S-phase duration. Binge alcohol exposure reduced the proportion of NPCs in S-phase, but had no effect on G1 or G2/M phases, indicating that alcohol specifically targets S-phase of the cell cycle. Cell cycle kinetics studies revealed that alcohol reduced NPC cell cycle duration by 36% and shortened S-phase by 62%, suggesting that binge alcohol exposure accelerates progression through the cell cycle. This effect would be expected to increase NPC proliferation, which was supported by a slight, but significant increase in the number of Sox-2+ NPCs residing in the hippocampal subgranular zone following binge alcohol exposure. These studies suggest the mechanism of alcohol inhibition of neurogenesis and also reveal the earliest evidence of the compensatory neurogenesis reaction that has been observed a week after binge alcohol exposure.

  3. Cell cycle in the fucus zygote parallels a somatic cell cycle but displays a unique translational regulation of cyclin-dependent kinases.

    PubMed

    Corellou, F; Brownlee, C; Detivaud, L; Kloareg, B; Bouget, F Y

    2001-03-01

    In eukaryotic cells, the basic machinery of cell cycle control is highly conserved. In particular, many cellular events during cell cycle progression are controlled by cyclin-dependent kinases (CDKs). The cell cycle in animal early embryos, however, differs substantially from that of somatic cells or yeasts. For example, cell cycle checkpoints that ensure that the sequence of cell cycle events is correct have been described in somatic cells and yeasts but are largely absent in embryonic cells. Furthermore, the regulation of CDKs is substantially different in the embryonic and somatic cells. In this study, we address the nature of the first cell cycle in the brown alga Fucus, which is evolutionarily distant from the model systems classically used for cell cycle studies in embryos. This cycle consists of well-defined G1, S, G2, and M phases. The purine derivative olomoucine inhibited CDKs activity in vivo and in vitro and induced different cell cycle arrests, including at the G1/S transition, suggesting that, as in somatic cells, CDKs tightly control cell cycle progression. The cell cycle of Fucus zygotes presented the other main features of a somatic cell cycle, such as a functional spindle assembly checkpoint that targets CDKs and the regulation of the early synthesis of two PSTAIRE CDKs, p32 and p34, and the associated histone H1 kinase activity as well as the regulation of CDKs by tyrosine phosphorylation. Surprisingly, the synthesis after fertilization of p32 and p34 was translationally regulated, a regulation not described previously for CDKs. Finally, our results suggest that the activation of mitotic CDKs relies on an autocatalytic amplification mechanism.

  4. Myricetin inhibits proliferation and induces apoptosis and cell cycle arrest in gastric cancer cells.

    PubMed

    Feng, Jianfang; Chen, Xiaonan; Wang, Yuanyuan; Du, Yuwen; Sun, Qianqian; Zang, Wenqiao; Zhao, Guoqiang

    2015-10-01

    Myricetin is a flavonoid that is abundant in fruits and vegetables and has protective effects against cancer and diabetes. However, the mechanism of action of myricetin against gastric cancer (GC) is not fully understood. We researched myricetin on the proliferation, apoptosis, and cell cycle in GC HGC-27 and SGC7901 cells, to explore the underlying mechanism of action. Cell Counting Kit (CCK)-8 assay, Western blotting, cell cycle analysis, and apoptosis assay were used to evaluate the effects of myricetin on cell proliferation, apoptosis, and the cell cycle. To analyze the binding properties of ribosomal S6 kinase 2 (RSK2) with myricetin, surface plasmon resonance (SPR) analysis was performed. CCK8 assay showed that myricetin inhibited GC cell proliferation. Flow cytometry analysis showed that myricetin induces apoptosis and cell cycle arrest in GC cells. Western blotting indicated that myricetin influenced apoptosis and cell cycle arrest of GC cells by regulating related proteins. SPR analysis showed strong binding affinity of RSK2 and myricetin. Myricetin bound to RSK2, leading to increased expression of Mad1, and contributed to inhibition of HGC-27 and SGC7901 cell proliferation. Our results suggest the therapeutic potential of myricetin in GC.

  5. Coherent regulation in yeast’s cell-cycle network

    NASA Astrophysics Data System (ADS)

    Aral, Neşe; Kabakçıoğlu, Alkan

    2015-05-01

    We define a measure of coherent activity for gene regulatory networks, a property that reflects the unity of purpose between the regulatory agents with a common target. We propose that such harmonious regulatory action is desirable under a demand for energy efficiency and may be selected for under evolutionary pressures. We consider two recent models of the cell-cycle regulatory network of the yeast, Saccharomyces cerevisiae as a case study and calculate their degree of coherence. A comparison with random networks of similar size and composition reveals that the yeast’s cell-cycle regulation is wired to yield an exceptionally high level of coherent regulatory activity. We also investigate the mean degree of coherence as a function of the network size, connectivity and the fraction of repressory/activatory interactions.

  6. Circular piecewise regression with applications to cell-cycle data.

    PubMed

    Rueda, Cristina; Fernández, Miguel A; Barragán, Sandra; Mardia, Kanti V; Peddada, Shyamal D

    2016-12-01

    Applications of circular regression models appear in many different fields such as evolutionary psychology, motor behavior, biology, and, in particular, in the analysis of gene expressions in oscillatory systems. Specifically, for the gene expression problem, a researcher may be interested in modeling the relationship among the phases of cell-cycle genes in two species with differing periods. This challenging problem reduces to the problem of constructing a piecewise circular regression model and, with this objective in mind, we propose a flexible circular regression model which allows different parameter values depending on sectors along the circle. We give a detailed interpretation of the parameters in the model and provide maximum likelihood estimators. We also provide a model selection procedure based on the concept of generalized degrees of freedom. The model is then applied to the analysis of two different cell-cycle data sets and through these examples we highlight the power of our new methodology.

  7. Mitochondria. Cell cycle-dependent regulation of mitochondrial preprotein translocase.

    PubMed

    Harbauer, Angelika B; Opalińska, Magdalena; Gerbeth, Carolin; Herman, Josip S; Rao, Sanjana; Schönfisch, Birgit; Guiard, Bernard; Schmidt, Oliver; Pfanner, Nikolaus; Meisinger, Chris

    2014-11-28

    Mitochondria play central roles in cellular energy conversion, metabolism, and apoptosis. Mitochondria import more than 1000 different proteins from the cytosol. It is unknown if the mitochondrial protein import machinery is connected to the cell division cycle. We found that the cyclin-dependent kinase Cdk1 stimulated assembly of the main mitochondrial entry gate, the translocase of the outer membrane (TOM), in mitosis. The molecular mechanism involved phosphorylation of the cytosolic precursor of Tom6 by cyclin Clb3-activated Cdk1, leading to enhanced import of Tom6 into mitochondria. Tom6 phosphorylation promoted assembly of the protein import channel Tom40 and import of fusion proteins, thus stimulating the respiratory activity of mitochondria in mitosis. Tom6 phosphorylation provides a direct means for regulating mitochondrial biogenesis and activity in a cell cycle-specific manner.

  8. [Cell cycle arrest at M phase induced by vinblastine in MOLT-4 cells].

    PubMed

    Zhong, Yi-Sheng; Pan, Chang-Chuan; Jin, Chang-Nan; Li, Jian-Jun; Xiong, Gong-Peng; Zhang, Jian-Xi; Gong, Jian-Ping

    2009-04-01

    This study was purposed to investigate the biological effect of vinblastine (VLS), usually known as inductor of mitotic arrest, on MOLT-4 of ALL cells and to evaluate its significance. The cell arrest in M phase and/or cell apoptosis were induced by treatment of MOLT-4 cells with 0.05 microg/ml VLS for 0 - 12 hours; the DNA histogram was detected by flow cytometry; the morphological changes of cells were observed by confocal microscopy; the cell cycle distribution, cell apoptosis and morphological changes of cells before and after arrest were analyzed by using arrest increasing rate (AIR), arrest efficiency (AE), apoptosis rate (AR) and morphologic parameters respectively. The results indicated that the cell arrest did not accompanied by significant increase of apoptosis rate; the DNA histogram of cell arrest showed dynamic change of cell cycle in time-dependent manner; the arrest efficiency could be quantified. The cell arrest at M phase was accompanied by cell stack in S phase, the cell proliferation rate dropped after cell arrest occurred. The cells arrested at M phase possessed of characteristic morphologic features in cell mitosis. It is concluded that the vinblastine can solely induce arrest of MOLT-4 cells at M phase. This study provides experimental basis for further investigating the relation of cell cycle arrest to apoptosis, mechanism of checkpoint and development of new anticancer drugs.

  9. Local homogeneity of cell cycle length in developing mouse cortex

    NASA Technical Reports Server (NTRS)

    Cai, L.; Hayes, N. L.; Nowakowski, R. S.

    1997-01-01

    We have measured the amount of variation in the length of the cell cycle for cells in the pseudostratified ventricular epithelium (PVE) of the developing cortex of mice on embryonic day 14. Our measurements were made in three cortical regions (i.e., the neocortex, archicortex, and periarchicortex) using three different methods: the cumulative labeling method (CLM), the percent labeled mitoses (PLM) method, and a comparison of the time needed for the PLM to ascend from 0 to 100% with the time needed for the PLM to descend from 100 to 0%. These 3 different techniques provide different perspectives on the cytokinetic parameters. Theoretically, CLM gives an estimate for a maximum value of the total length of the cell cycle (TC), whereas PLM gives an estimate of a minimum value of TC. The difference between these two estimates indicates that the range for TC is +/-1% of the mean TC for periarchicortex, +/-7% for neocortex, and +/-8% for archicortex. This was confirmed by a lengthening of the PLM descent time in comparison with its ascent time. The sharpness of the transitions and the flatness of the plateau of the PLM curves indicate that 99% of the proliferating cells are within this narrow estimated range for TC; hence, only approximately 1% deviate outside of a relatively restricted range from the average TC of the population. In the context of the possible existence within the cortical PVE of two populations with markedly dissimilar cell cycle kinetics from the mean, one such population must comprise approximately 99% of the total population, and the other, if it exists, is only approximately 1% of the total. This seems to be true for all three cortical regions. The narrow range of TC indicates a homogeneity in the cell cycle length for proliferating cells in three different cortical regions, despite the fact that progenitor cells of different lineages may be present. It further predicts the existence of almost synchronous interkinetic nuclear movements of the

  10. Ecdysone signaling induces two phases of cell cycle exit in Drosophila cells

    PubMed Central

    Guo, Yongfeng; Flegel, Kerry; Kumar, Jayashree; McKay, Daniel J.

    2016-01-01

    ABSTRACT During development, cell proliferation and differentiation must be tightly coordinated to ensure proper tissue morphogenesis. Because steroid hormones are central regulators of developmental timing, understanding the links between steroid hormone signaling and cell proliferation is crucial to understanding the molecular basis of morphogenesis. Here we examined the mechanism by which the steroid hormone ecdysone regulates the cell cycle in Drosophila. We find that a cell cycle arrest induced by ecdysone in Drosophila cell culture is analogous to a G2 cell cycle arrest observed in the early pupa wing. We show that in the wing, ecdysone signaling at the larva-to-puparium transition induces Broad which in turn represses the cdc25c phosphatase String. The repression of String generates a temporary G2 arrest that synchronizes the cell cycle in the wing epithelium during early pupa wing elongation and flattening. As ecdysone levels decline after the larva-to-puparium pulse during early metamorphosis, Broad expression plummets, allowing String to become re-activated, which promotes rapid G2/M progression and a subsequent synchronized final cell cycle in the wing. In this manner, pulses of ecdysone can both synchronize the final cell cycle and promote the coordinated acquisition of terminal differentiation characteristics in the wing. PMID:27737823

  11. Predicting cell cycle regulated genes by causal interactions.

    PubMed

    Emmert-Streib, Frank; Dehmer, Matthias

    2009-08-18

    The fundamental difference between classic and modern biology is that technological innovations allow to generate high-throughput data to get insights into molecular interactions on a genomic scale. These high-throughput data can be used to infer gene networks, e.g., the transcriptional regulatory or signaling network, representing a blue print of the current dynamical state of the cellular system. However, gene networks do not provide direct answers to biological questions, instead, they need to be analyzed to reveal functional information of molecular working mechanisms. In this paper we propose a new approach to analyze the transcriptional regulatory network of yeast to predict cell cycle regulated genes. The novelty of our approach is that, in contrast to all other approaches aiming to predict cell cycle regulated genes, we do not use time series data but base our analysis on the prior information of causal interactions among genes. The major purpose of the present paper is to predict cell cycle regulated genes in S. cerevisiae. Our analysis is based on the transcriptional regulatory network, representing causal interactions between genes, and a list of known periodic genes. No further data are used. Our approach utilizes the causal membership of genes and the hierarchical organization of the transcriptional regulatory network leading to two groups of periodic genes with a well defined direction of information flow. We predict genes as periodic if they appear on unique shortest paths connecting two periodic genes from different hierarchy levels. Our results demonstrate that a classical problem as the prediction of cell cycle regulated genes can be seen in a new light if the concept of a causal membership of a gene is applied consequently. This also shows that there is a wealth of information buried in the transcriptional regulatory network whose unraveling may require more elaborate concepts than it might seem at first.

  12. Cell cycle and centromere FISH studies in premature centromere division

    PubMed Central

    Corona-Rivera, Alfredo; Salamanca-Gomez, Fabio; Bobadilla-Morales, Lucina; Corona-Rivera, Jorge R; Palomino-Cueva, Cesar; Garcia-Cobian, Teresa A; Corona-Rivera, Enrique

    2005-01-01

    Background Mitotic configurations consistent in split centromeres and splayed chromatids in all or most of the chromosomes or premature centromere division (PCD) have been described in three categories. (1) Low frequency of PCD observed in colchicines-treated lymphocyte cultures from normal individuals. (2) High frequency of PCD with mosaic variegated aneuploidy. (3) High frequency of PCD as a sole chromosome abnormality observed in individuals with no recognizable clinical pattern. We report four members of a family with the third category of PCD. Methods Cell cycle duration assessed by average generation time using differential sister chromatid stain analysis and FISH studies of DNA centromere sequences in PCD individuals, are included and compared with previously reported PCD individuals from 9 families. Results We observed PCD in colchicine-treated cultures from the propositus, his father, and two paternal aunts but not in his mother and four other paternal and maternal family members, as well as in untreated cultures from the propositus and his father. We observed cytological evidence of active centromeres by Cd stain. Significative cell cycle time reduction in anaphases of PCD individuals (average generation time of 21.8 h;SD 0.4) with respect to individuals without PCD (average generation time of 31.8 h;SD 3.9) was observed (P < 0.005, Student t-test for independent samples). Increased cell proliferation kinetics was observed in anaphasic cells of individuals with PCD, by differential sister chromatid stain analysis. FISH studies revealed the presence of alpha satellite DNA from chromosomes 1, 13, 21/18, X, all centromeres, and CENP-B box sequences in metaphasic and anaphasic cells from PCD individuals. Conclusion This report examines evidences of a functional relationship between PCD and cell cycle impairment. It seems that essential centromere integrity is present in these cases. PMID:16174301

  13. The Cell Cycle Timing of Human Papillomavirus DNA Replication.

    PubMed

    Reinson, Tormi; Henno, Liisi; Toots, Mart; Ustav, Mart; Ustav, Mart

    2015-01-01

    Viruses manipulate the cell cycle of the host cell to optimize conditions for more efficient viral genome replication. One strategy utilized by DNA viruses is to replicate their genomes non-concurrently with the host genome; in this case, the viral genome is amplified outside S phase. This phenomenon has also been described for human papillomavirus (HPV) vegetative genome replication, which occurs in G2-arrested cells; however, the precise timing of viral DNA replication during initial and stable replication phases has not been studied. We developed a new method to quantitate newly synthesized DNA levels and used this method in combination with cell cycle synchronization to show that viral DNA replication is initiated during S phase and is extended to G2 during initial amplification but follows the replication pattern of cellular DNA during S phase in the stable maintenance phase. E1 and E2 protein overexpression changes the replication time from S only to both the S and G2 phases in cells that stably maintain viral episomes. These data demonstrate that the active synthesis and replication of the HPV genome are extended into the G2 phase to amplify its copy number and the duration of HPV genome replication is controlled by the level of the viral replication proteins E1 and E2. Using the G2 phase for genome amplification may be an important adaptation that allows exploitation of changing cellular conditions during cell cycle progression. We also describe a new method to quantify newly synthesized viral DNA levels and discuss its benefits for HPV research.

  14. Tracking of Normal and Malignant Progenitor Cell Cycle Transit in a Defined Niche

    PubMed Central

    Pineda, Gabriel; Lennon, Kathleen M.; Delos Santos, Nathaniel P.; Lambert-Fliszar, Florence; Riso, Gennarina L.; Lazzari, Elisa; Marra, Marco A.; Morris, Sheldon; Sakaue-Sawano, Asako; Miyawaki, Atsushi; Jamieson, Catriona H. M.

    2016-01-01

    While implicated in therapeutic resistance, malignant progenitor cell cycle kinetics have been difficult to quantify in real-time. We developed an efficient lentiviral bicistronic fluorescent, ubiquitination-based cell cycle indicator reporter (Fucci2BL) to image live single progenitors on a defined niche coupled with cell cycle gene expression analysis. We have identified key differences in cell cycle regulatory gene expression and transit times between normal and chronic myeloid leukemia progenitors that may inform cancer stem cell eradication strategies. PMID:27041210

  15. Cell cycle arrest induced by MPPa-PDT in MDA-MB-231 cells

    NASA Astrophysics Data System (ADS)

    Liang, Liming; Bi, Wenxiang; Tian, Yuanyuan

    2016-05-01

    Photodynamic therapy (PDT) is a medical treatment using a photosensitizing agent and light source to treat cancers. Pyropheophorbidea methyl ester (MPPa), a derivative of chlorophyll, is a novel potent photosensitizer. To learn more about this photosensitizer, we examined the cell cycle arrest in MDA-MB-231. Cell cycle and apoptosis were measured by flow cytometer. Checkpoints of the cell cycle were measured by western blot. In this study, we found that the expression of Cyclin D1 was obviously decreased, while the expression of Chk2 and P21 was increased after PDT treatment. This study showed that MPPa-PDT affected the checkpoints of the cell cycle and led the cells to apoptosis.

  16. Nuclear incorporation of iron during the eukaryotic cell cycle

    PubMed Central

    Robinson, Ian; Yang, Yang; Zhang, Fucai; Lynch, Christophe; Yusuf, Mohammed; Cloetens, Peter

    2016-01-01

    Scanning X-ray fluorescence microscopy has been used to probe the distribution of S, P and Fe within cell nuclei. Nuclei, which may have originated at different phases of the cell cycle, are found to show very different levels of Fe present with a strongly inhomogeneous distribution. P and S signals, presumably from DNA and associated nucleosomes, are high and relatively uniform across all the nuclei; these agree with X-ray phase contrast projection microscopy images of the same samples. Possible reasons for the Fe incorporation are discussed. PMID:27787255

  17. Nuclear incorporation of iron during the eukaryotic cell cycle

    DOE PAGES

    Robinson, Ian; Yang, Yang; Zhang, Fucai; ...

    2016-10-18

    Scanning X-ray fluorescence microscopy has been used to probe the distribution of S, P and Fe within cell nuclei. Nuclei, which may have originated at different phases of the cell cycle, are found to show very different levels of Fe present with a strongly inhomogeneous distribution. P and S signals, presumably from DNA and associated nucleosomes, are high and relatively uniform across all the nuclei; these agree with X-ray phase contrast projection microscopy images of the same samples. Finally, we discuss possible reasons for the Fe incorporation.

  18. Nuclear incorporation of iron during the eukaryotic cell cycle

    SciTech Connect

    Robinson, Ian; Yang, Yang; Zhang, Fucai; Lynch, Christophe; Yusuf, Mohammed; Cloetens, Peter

    2016-10-18

    Scanning X-ray fluorescence microscopy has been used to probe the distribution of S, P and Fe within cell nuclei. Nuclei, which may have originated at different phases of the cell cycle, are found to show very different levels of Fe present with a strongly inhomogeneous distribution. P and S signals, presumably from DNA and associated nucleosomes, are high and relatively uniform across all the nuclei; these agree with X-ray phase contrast projection microscopy images of the same samples. Finally, we discuss possible reasons for the Fe incorporation.

  19. Allyl isothiocyanate affects the cell cycle of Arabidopsis thaliana

    PubMed Central

    Åsberg, Signe E.; Bones, Atle M.; Øverby, Anders

    2015-01-01

    Isothiocyanates (ITCs) are degradation products of glucosinolates present in members of the Brassicaceae family acting as herbivore repellents and antimicrobial compounds. Recent results indicate that allyl ITC (AITC) has a role in defense responses such as glutathione depletion, ROS generation and stomatal closure. In this study we show that exposure to non-lethal concentrations of AITC causes a shift in the cell cycle distribution of Arabidopsis thaliana leading to accumulation of cells in S-phases and a reduced number of cells in non-replicating phases. Furthermore, transcriptional analysis revealed an AITC-induced up-regulation of the gene encoding cyclin-dependent kinase A while several genes encoding mitotic proteins were down-regulated, suggesting an inhibition of mitotic processes. Interestingly, visualization of DNA synthesis indicated that exposure to AITC reduced the rate of DNA replication. Taken together, these results indicate that non-lethal concentrations of AITC induce cells of A. thaliana to enter the cell cycle and accumulate in S-phases, presumably as a part of a defensive response. Thus, this study suggests that AITC has several roles in plant defense and add evidence to the growing data supporting a multifunctional role of glucosinolates and their degradation products in plants. PMID:26042144

  20. Cell-cycle research with synchronous cultures: an evaluation

    NASA Technical Reports Server (NTRS)

    Helmstetter, C. E.; Thornton, M.; Grover, N. B.

    2001-01-01

    The baby-machine system, which produces new-born Escherichia coli cells from cultures immobilized on a membrane, was developed many years ago in an attempt to attain optimal synchrony with minimal disturbance of steady-state growth. In the present article, we put forward a model to describe the behaviour of cells produced by this method, and provide quantitative evaluation of the parameters involved, at each of four different growth rates. Considering the high level of selection achievable with this technique and the natural dispersion in interdivision times, we believe that the output of the baby machine is probably close to optimal in terms of both quality and persistence of synchrony. We show that considerable information on events in the cell cycle can be obtained from populations with age distributions very much broader than those achieved with the baby machine and differing only modestly from steady state. The data presented here, together with the long and fruitful history of findings employing the baby-machine technique, suggest that minimisation of stress on cells is the single most important factor for successful cell-cycle analysis.

  1. Cell Cycle Characteristics of Crenarchaeota: Unity among Diversity▿

    PubMed Central

    Lundgren, Magnus; Malandrin, Laurence; Eriksson, Stefan; Huber, Harald; Bernander, Rolf

    2008-01-01

    The hyperthermophilic archaea Acidianus hospitalis, Aeropyrum pernix, Pyrobaculum aerophilum, Pyrobaculum calidifontis, and Sulfolobus tokodaii representing three different orders in the phylum Crenarchaeota were analyzed by flow cytometry and combined phase-contrast and epifluorescence microscopy. The overall organization of the cell cycle was found to be similar in all species, with a short prereplicative period and a dominant postreplicative period that accounted for 64 to 77% of the generation time. Thus, in all Crenarchaeota analyzed to date, cell division and initiation of chromosome replication occur in close succession, and a long time interval separates termination of replication from cell division. In Pyrobaculum, chromosome segregation overlapped with or closely followed DNA replication, and further genome separation appeared to occur concomitant with cellular growth. Cell division in P. aerophilum took place without visible constriction. PMID:18502873

  2. Cell cycle characteristics of crenarchaeota: unity among diversity.

    PubMed

    Lundgren, Magnus; Malandrin, Laurence; Eriksson, Stefan; Huber, Harald; Bernander, Rolf

    2008-08-01

    The hyperthermophilic archaea Acidianus hospitalis, Aeropyrum pernix, Pyrobaculum aerophilum, Pyrobaculum calidifontis, and Sulfolobus tokodaii representing three different orders in the phylum Crenarchaeota were analyzed by flow cytometry and combined phase-contrast and epifluorescence microscopy. The overall organization of the cell cycle was found to be similar in all species, with a short prereplicative period and a dominant postreplicative period that accounted for 64 to 77% of the generation time. Thus, in all Crenarchaeota analyzed to date, cell division and initiation of chromosome replication occur in close succession, and a long time interval separates termination of replication from cell division. In Pyrobaculum, chromosome segregation overlapped with or closely followed DNA replication, and further genome separation appeared to occur concomitant with cellular growth. Cell division in P. aerophilum took place without visible constriction.

  3. Single-cell dynamics of the chromosome replication and cell division cycles in mycobacteria.

    PubMed

    Santi, Isabella; Dhar, Neeraj; Bousbaine, Djenet; Wakamoto, Yuichi; McKinney, John D

    2013-01-01

    During the bacterial cell cycle, chromosome replication and cell division must be coordinated with overall cell growth in order to maintain the correct ploidy and cell size. The spatial and temporal coordination of these processes in mycobacteria is not understood. Here we use microfluidics and time-lapse fluorescence microscopy to measure the dynamics of cell growth, division and chromosome replication in single cells of Mycobacterium smegmatis. We find that single-cell growth is size-dependent (large cells grow faster than small cells), which implicates a size-control mechanism in cell-size homoeostasis. Asymmetric division of mother cells gives rise to unequally sized sibling cells that grow at different velocities but show no differential sensitivity to antibiotics. Individual cells are restricted to one round of chromosome replication per cell division cycle, although replication usually initiates in the mother cell before cytokinesis and terminates in the daughter cells after cytokinesis. These studies reveal important differences between cell cycle organization in mycobacteria compared with better-studied model organisms.

  4. Effects of mimosine on Wolbachia in mosquito cells: cell cycle suppression reduces bacterial abundance.

    PubMed

    Fallon, Ann M

    2015-10-01

    The plant allelochemical L-mimosine (β-[N-(3-hydroxy-4-pyridone)]-α-aminopropionic acid; leucenol) resembles the nonessential amino acid, tyrosine. Because the obligate intracellular alphaproteobacterium, Wolbachia pipientis, metabolizes amino acids derived from host cells, the effects of mimosine on infected and uninfected mosquito cells were investigated. The EC50 for mimosine was 6-7 μM with Aedes albopictus C7-10 and C/wStr cell lines, and was not influenced by infection status. Mosquito cells responded to concentrations of mimosine substantially lower than those used to synchronize the mammalian cell cycle; at concentrations of 30-35 μM, mimosine reversibly arrested the mosquito cell cycle at the G1/S boundary and inhibited growth of Wolbachia strain wStr. Although lower concentrations of mimosine slightly increased wStr abundance, concentrations that suppressed the cell cycle reduced Wolbachia levels.

  5. Effects of trichostatin A on HDAC8 expression, proliferation and cell cycle of Molt-4 cells.

    PubMed

    He, Jing; Liu, Hongli; Chen, Yan

    2006-01-01

    The effects of Trichostatin A (TSA) on histone deacetylase 8 (HDAC8) expression, proliferation and cell cycle arrest in T-lymphoblastic leukemia cell line Molt-4 cells in vitro were investigated. The effect of TSA on the growth of Molt-4 cells was studied by MTT assay. Flow cytometry was used to examine the cell cycle. The expression of HDAC8 was detected by using immunocytochemistry and Western blot. The results showed that proliferation of Molt-4 cells was inhibited in TSA-treated group in a time- and dose-dependent manner. The IC50 of TSA exposures for 24 h and 36 h were 254.3236 and 199.257 microg/L respectively. The cell cycle analysis revealed that Molt-4 was mostly in G0/G1 phase, and after treatment with TSA from 50 to 400 microg/L for 24 h, the percents of G0/G1 cells were decreased and cells were arrested in G2/M phase. Treatment of TSA for 24 h could significantly inhibit the expression of HDAC8 protein in Molt-4 cells (P<0.01). It was concluded that TSA could decrease the expression of HDAC8 in Molt-4 cells, which contributed to the inhibition of proliferation and induction of cell cycle arrest in Molt-4 cells.

  6. Linalool Induces Cell Cycle Arrest and Apoptosis in Leukemia Cells and Cervical Cancer Cells through CDKIs

    PubMed Central

    Chang, Mei-Yin; Shieh, Den-En; Chen, Chung-Chi; Yeh, Ching-Sheng; Dong, Huei-Ping

    2015-01-01

    Plantaginaceae, a popular traditional Chinese medicine, has long been used for treating various diseases from common cold to cancer. Linalool is one of the biologically active compounds that can be isolated from Plantaginaceae. Most of the commonly used cytotoxic anticancer drugs have been shown to induce apoptosis in susceptible tumor cells. However, the signaling pathway for apoptosis remains undefined. In this study, the cytotoxic effect of linalool on human cancer cell lines was investigated. Water-soluble tetrazolium salts (WST-1) based colorimetric cellular cytotoxicity assay, was used to test the cytotoxic ability of linalool against U937 and HeLa cells, and flow cytometry (FCM) and genechip analysis were used to investigate the possible mechanism of apoptosis. These results demonstrated that linalool exhibited a good cytotoxic effect on U937 and HeLa cells, with the IC50 value of 2.59 and 11.02 μM, respectively, compared with 5-FU with values of 4.86 and 12.31 μM, respectively. After treating U937 cells with linalool for 6 h, we found an increased sub-G1 peak and a dose-dependent phenomenon, whereby these cells were arrested at the G0/G1 phase. Furthermore, by using genechip analysis, we observed that linalool can promote p53, p21, p27, p16, and p18 gene expression. Therefore, this study verified that linalool can arrest the cell cycle of U937 cells at the G0/G1 phase and can arrest the cell cycle of HeLa cells at the G2/M phase. Its mechanism facilitates the expression of the cyclin-dependent kinases inhibitors (CDKIs) p53, p21, p27, p16, and p18, as well as the non-expression of cyclin-dependent kinases (CDKs) activity. PMID:26703569

  7. Dopamine Modulates Cell Cycle in the Lateral Ganglionic Eminence

    PubMed Central

    Ohtani, Nobuyo; Goto, Tomohide; Waeber, Christian; Bhide, Pradeep G.

    2005-01-01

    Dopamine is a neuromodulator the functions of which in the regulation of complex behaviors such as mood, motivation, and attention are well known. Dopamine appears in the brain early in the embryonic period when none of those behaviors is robust, raising the possibility that dopamine may influence brain development. The effects of dopamine on specific developmental processes such as neurogenesis are not fully characterized. The neostriatum is a dopamine-rich region of the developing and mature brain. If dopamine influenced neurogenesis, the effects would likely be pronounced in the neostriatum. Therefore, we examined whether dopamine influenced neostriatal neurogenesis by influencing the cell cycle of progenitor cells in the lateral ganglionic eminence (LGE), the neuroepithelial precursor of the neostriatum. We show that dopamine arrives in the LGE via the nigrostriatal pathway early in the embryonic period and that neostriatal neurogenesis progresses in a dopamine-rich milieu. Dopamine D1-like receptor activation reduces entry of progenitor cells from the G1-to S-phase of the cell cycle, whereas D2-like receptor activation produces the opposite effects by promoting G1- to S-phase entry. D1-like effects are prominent in the ventricular zone, and D2-like effects are prominent in the subventricular zone. The overall effects of dopamine on the cell cycle are D1-like effects, most likely because of the preponderance of D1-like binding sites in the embryonic neostriatum. These data reveal a novel developmental role for dopamine and underscore the relevance of dopaminergic signaling in brain development. PMID:12684471

  8. Model scenarios for evolution of the eukaryotic cell cycle.

    PubMed Central

    Novak, B; Csikasz-Nagy, A; Gyorffy, B; Nasmyth, K; Tyson, J J

    1998-01-01

    Progress through the division cycle of present day eukaryotic cells is controlled by a complex network consisting of (i) cyclin-dependent kinases (CDKs) and their associated cyclins, (ii) kinases and phosphatases that regulate CDK activity, and (iii) stoichiometric inhibitors that sequester cyclin-CDK dimers. Presumably regulation of cell division in the earliest ancestors of eukaryotes was a considerably simpler affair. Nasmyth (1995) recently proposed a mechanism for control of a putative, primordial, eukaryotic cell cycle, based on antagonistic interactions between a cyclin-CDK and the anaphase promoting complex (APC) that labels the cyclin subunit for proteolysis. We recast this idea in mathematical form and show that the model exhibits hysteretic behaviour between alternative steady states: a Gl-like state (APC on, CDK activity low, DNA unreplicated and replication complexes assembled) and an S/M-like state (APC off, CDK activity high, DNA replicated and replication complexes disassembled). In our model, the transition from G1 to S/M ('Start') is driven by cell growth, and the reverse transition ('Finish') is driven by completion of DNA synthesis and proper alignment of chromosomes on the metaphase plate. This simple and effective mechanism for coupling growth and division and for accurately copying and partitioning a genome consisting of numerous chromosomes, each with multiple origins of replication, could represent the core of the eukaryotic cell cycle. Furthermore, we show how other controls could be added to this core and speculate on the reasons why stoichiometric inhibitors and CDK inhibitory phosphorylation might have been appended to the primitive alternation between cyclin accumulation and degradation. PMID:10098216

  9. A conserved DNA damage response pathway responsible for coupling the cell division cycle to the circadian and metabolic cycles.

    PubMed

    Chen, Zheng; McKnight, Steven L

    2007-12-01

    The circadian clock drives endogenous oscillations of cellular and physiological processes with a periodicity of approximately 24 h. Progression of the cell division cycle (CDC) has been found to be coupled to the circadian clock, and it has been postulated that gating of the CDC by the circadian cycle may have evolved to protect DNA from the mutagenic effects of ultraviolet light. When grown under nutrient-limiting conditions in a chemostat, prototrophic strains of budding yeast, Saccharomyces cerevisiae, adopt a robust metabolic cycle of ultradian dimensions that temporally compartmentalizes essential cellular events. The CDC is gated by this yeast metabolic cycle (YMC), with DNA replication strictly segregated away from the oxidative phase when cells are actively respiring. Mutants impaired in such gating allow DNA replication to take place during the respiratory phase of the YMC and have been found to suffer significantly elevated rates of spontaneous mutation. Analogous to the circadian cycle, the YMC also employs the conserved DNA checkpoint kinase Rad53/Chk2 to facilitate coupling with the CDC. These studies highlight an evolutionarily conserved mechanism that seems to confine cell division to particular temporal windows to prevent DNA damage. We hypothesize that DNA damage itself might constitute a "zeitgeber", or time giver, for both the circadian cycle and the metabolic cycle. We discuss these findings in the context of a unifying theme underlying the circadian and metabolic cycles, and explore the relevance of cell cycle gating to human diseases including cancer.

  10. Hubble Space Telescope solar cell module thermal cycle test

    NASA Technical Reports Server (NTRS)

    Douglas, Alexander; Edge, Ted; Willowby, Douglas; Gerlach, Lothar

    1992-01-01

    The Hubble Space Telescope (HST) solar array consists of two identical double roll-out wings designed after the Hughes flexible roll-up solar array (FRUSA) and was developed by the European Space Agency (ESA) to meet specified HST power output requirements at the end of 2 years, with a functional lifetime of 5 years. The requirement that the HST solar array remain functional both mechanically and electrically during its 5-year lifetime meant that the array must withstand 30,000 low Earth orbit (LEO) thermal cycles between approximately +100 and -100 C. In order to evaluate the ability of the array to meet this requirement, an accelerated thermal cycle test in vacuum was conducted at NASA's Marshall Space Flight Center (MSFC), using two 128-cell solar array modules which duplicated the flight HST solar array. Several other tests were performed on the modules. The thermal cycle test was interrupted after 2,577 cycles, and a 'cold-roll' test was performed on one of the modules in order to evaluate the ability of the flight array to survive an emergency deployment during the dark (cold) portion of an orbit. A posttest static shadow test was performed on one of the modules in order to analyze temperature gradients across the module. Finally, current in-flight electrical performance data from the actual HST flight solar array will be tested.

  11. Preparative electrophoresis of cultured human cells: Effect of cell cycle phase

    NASA Technical Reports Server (NTRS)

    Kunze, M. E.; Todd, P. W.; Goolsby, C. L.; Walker, J. T.

    1985-01-01

    Human epithelioid T-1E cells were cultured in suspension and subjected to density gradient electrophoresis upward in a vertical column. It is indicated that the most rapidly migrating cells were at the beginning of the cell cycle and the most slowly migrating cells were at the end of the cell cycle. The fastest migrating cells divided 24 hr later than the slowest migrating cells. Colonies developing from slowly migrating cells had twice as many cells during exponential growth as did the most rapidly migrating cells, and the numbers of cells per colony at any time was inversely related to the electrophoretic migration rate. The DNA measurements by fluorescence flow cytometry indicates that the slowest migrating cell populations are enriched in cells that have twice as much DNA as the fastest migrating cells. It is concluded that electrophoretic mobility of these cultured human cells declines steadily through the cell cycle and that the mobility is lowest at the end of G sub 2 phase and highest at the beginning of G sub 1 phase.

  12. HDAC2 regulates cell proliferation, cell cycle progression and cell apoptosis in esophageal squamous cell carcinoma EC9706 cells

    PubMed Central

    Li, Shenglei; Wang, Feng; Qu, Yunhui; Chen, Xiaoqi; Gao, Ming; Yang, Jianping; Zhang, Dandan; Zhang, Na; Li, Wencai; Liu, Hongtao

    2017-01-01

    Increasing evidence has demonstrated that histone deacetylase 2 (HDAC2) participates in the regulation of a variety of biological processes in numerous tumors. However, the potential role of HDAC2 in the development and progression of esophageal squamous cell carcinoma (ESCC) remains elusive. Immunohistochemistry was utilized to detect the expression of HDAC2, Cell Counting Kit-8 was used to determine the cell proliferation, and flow cytometry was employed to investigate cell cycle and cell apoptosis. Finally, western blotting was employed to detect the protein expression of cyclin D1, p21, B cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax). The present study found that expression of HDAC2 protein in ESCC tissues was significantly increased compared with atypical hyperplasia tissues and normal esophageal mucosa (P<0.001). The expression of HDAC2 was not associated with the age or gender of patients (P>0.05), but was closely associated with the histological grade, invasion depth, tumor-node-metastasis stage and lymph node metastasis, respectively (all P<0.001). HDAC2 small interfering RNA effectively downregulated the expression of HDAC2 protein in ESCC EC9706 cells. Downregulation of HDAC2 expression evidently inhibited cell proliferation, arrested cell cycle at the G0/G1 phase and induced cell apoptosis in ESCC EC9706 cells, coupled with increased expression of p21 and Bax proteins and decreased expression of cyclin D1 and Bcl-2 proteins. Overall, the present findings suggest that HDAC2 may play an important role in the development and progression of ESCC and be considered as a novel molecular target for the treatment of ESCC. PMID:28123574

  13. Exosomes Secreted by Toxoplasma gondii-Infected L6 Cells: Their Effects on Host Cell Proliferation and Cell Cycle Changes.

    PubMed

    Kim, Min Jae; Jung, Bong-Kwang; Cho, Jaeeun; Song, Hyemi; Pyo, Kyung-Ho; Lee, Ji Min; Kim, Min-Kyung; Chai, Jong-Yil

    2016-04-01

    Toxoplasma gondii infection induces alteration of the host cell cycle and cell proliferation. These changes are not only seen in directly invaded host cells but also in neighboring cells. We tried to identify whether this alteration can be mediated by exosomes secreted by T. gondii-infected host cells. L6 cells, a rat myoblast cell line, and RH strain of T. gondii were selected for this study. L6 cells were infected with or without T. gondii to isolate exosomes. The cellular growth patterns were identified by cell counting with trypan blue under confocal microscopy, and cell cycle changes were investigated by flow cytometry. L6 cells infected with T. gondii showed decreased proliferation compared to uninfected L6 cells and revealed a tendency to stay at S or G2/M cell phase. The treatment of exosomes isolated from T. gondii-infected cells showed attenuation of cell proliferation and slight enhancement of S phase in L6 cells. The cell cycle alteration was not as obvious as reduction of the cell proliferation by the exosome treatment. These changes were transient and disappeared at 48 hr after the exosome treatment. Microarray analysis and web-based tools indicated that various exosomal miRNAs were crucial for the regulation of target genes related to cell proliferation. Collectively, our study demonstrated that the exosomes originating from T. gondii could change the host cell proliferation and alter the host cell cycle.

  14. Flow cytometric analysis of the cell cycle in chronic gastritis.

    PubMed

    Guerci, A; Chambre, J F; Franck, P; Floquet, J; Gaucher, P; Guerci, O

    1992-09-01

    Flow cytometric cell cycle analysis was recorded in gastric biopsy specimens from patients with normal gastric mucosa (GM), superficial gastritis (SG) and chronic atrophic gastritis (CAG). Cell-cycle analysis showed significantly higher percentages of cells in S- and S+G2/M-phase in CAG than in SG and normal GM (P < 0.0001). Moreover, CAG with severe or moderate atrophy showed significantly higher percentages of cells in S-phase (P < 0.05) and S+G2/M-phase (P < 0.02) than CAG with mild atrophy in antrum. In fundus, even if this increase was observed, it did not reach statistical significance. Consideration of concomitant pathologic findings such as oesophagite, gastric or duodenal ulcer, duodenite or benign polyp allowed a better differentiation of CAG both in antrum and in fundus. Significantly higher S-phase was observed in CAG with severe or moderate atrophy than in CAG with mild atrophy (P < 0.05). No statistically significant results were observed in patients with normal gastric mucosa or chronic gastritis and a concomitant pathologic finding.

  15. Modeling cell-cycle synchronization during embryogenesis in Xenopus laevis

    NASA Astrophysics Data System (ADS)

    McIsaac, R. Scott; Huang, K. C.; Sengupta, Anirvan; Wingreen, Ned

    2010-03-01

    A widely conserved aspect of embryogenesis is the ability to synchronize nuclear divisions post-fertilization. How is synchronization achieved? Given a typical protein diffusion constant of 10 μm^2sec, and an embryo length of 1mm, it would take diffusion many hours to propagate a signal across the embryo. Therefore, synchrony cannot be attained by diffusion alone. We hypothesize that known autocatalytic reactions of cell-cycle components make the embryo an ``active medium'' in which waves propagate much faster than diffusion, enforcing synchrony. We report on robust spatial synchronization of components of the core cell cycle circuit based on a mathematical model previously determined by in vitro experiments. In vivo, synchronized divisions are preceded by a rapid calcium wave that sweeps across the embryo. Experimental evidence supports the hypothesis that increases in transient calcium levels lead to derepression of a negative feedback loop, allowing cell divisions to start. Preliminary results indicate a novel relationship between the speed of the initial calcium wave and the ability to achieve synchronous cell divisions.

  16. Cell and nuclei separation from tissue and from various phases of the cell cycle. Final report

    SciTech Connect

    Pipkin, J.

    1982-05-01

    The Cell Biology laboratory has developed practical methods for routine electrostatic separation of nuclei. Specially designed collection chambers facilitate the capture of sufficient numbers of cells and/or nuclei from precise areas of the cell cycle for biochemical analysis. These analyses include: one- and two-dimensional gel electrophoresis, isoelectric focusing, amino acid analysis and capillary isotachophoretic techniques that are used to demonstrate nuclear regulatory protein synthesis during the in vivo cell cycle after administration of various compounds. Separation of nuclei into homogeneous populations simplifies the detection of biochemical events that transpire in both cycling and non-cycling tissue into more discrete stages for analysis, thus uncluttering the more complex overall picture seen so commonly in generalized proliferating tissue.

  17. Effects of suppressed autophagy on mitochondrial dynamics and cell cycle of N2a cells.

    PubMed

    Gui, Meng-cui; Chen, Bo; Yu, Shan-shan; Bu, Bi-tao

    2014-04-01

    Autophagy dysregulation, mitochondrial dynamic abnormality and cell cycle re-entry are implicated in the vulnerable neurons of patients with Alzheimer's disease. This study was designed to testify the association among autophagy, mitochondrial dynamics and cell cycle in dividing neuroblastoma (N2a) cells. The N2a cells were cultured in vitro and treated with different concentrations of 3-methyladenine (3-MA). The cell viability was detected by methyl thiazolyl tetrazolium (MTT) assay. They were randomly divided into control group (cells cultured in normal culture medium) and 3-MA group (cells treated with 10 mmol/L 3-MA). The cell cycle was analyzed in the two groups 3, 6, 12, and 24 h after treatment by flow cytometry. Western blotting was used to evaluate the expression levels of mitofission 1 (Fis1), mitofusin 2 (Mfn2), microtubule-associated protein 1 light chain 3 (LC3), cell cycle-dependent kinase 4 (CDK4) and cdc2. The flow cytometry revealed that the proportion of cells in G(2)/M was significantly increased, and that in G0/G1 was significantly reduced in the 3-MA group as compared with the control group. Western blotting showed that the expression levels of Fis1, LC3, and CDK4 were significantly up-regulated in the 3-MA group at the four indicated time points as compared with the control group. Mfn2 was initially decreased in the 3-MA group, and then significantly increased at 6 h or 12 h. Cdc2 was significantly increased in the 3-MA group at 3 h and 6 h, and then dropped significantly at 12 h and 24 h. Our data indicated that 3-MA-induced suppressed autophagy may interfere with the cell cycle progression and mitochondrial dynamics, and cause cell death. There are interactions among cell cycle, mitochondrial dynamics and autophagy in neurons.

  18. Maintenance of imprinting and nuclear architecture in cycling cells.

    PubMed

    Teller, Kathrin; Solovei, Irina; Buiting, Karin; Horsthemke, Bernhard; Cremer, Thomas

    2007-09-18

    Dynamic gene repositioning has emerged as an additional level of epigenetic gene regulation. An early example was the report of a transient, spatial convergence (< or =2 microm) of oppositely imprinted regions ("kissing"), including the Angelman syndrome/Prader-Willi syndrome (AS/PWS) locus and the Beckwith-Wiedemann syndrome locus in human lymphocytes during late S phase. It was argued that kissing is required for maintaining opposite imprints in cycling cells. Employing 3D-FISH with a BAC contig covering the AS/PWS region, light optical, serial sectioning, and quantitative 3D-image analysis, we observed that both loci always retained a compact structure and did not form giant loops. Three-dimensional distances measured among various, homologous AS/PWS segments in 393 human lymphocytes, 132 human fibroblasts, and 129 lymphoblastoid cells from Gorilla gorilla revealed a wide range of distances at any stage of interphase and in G(0). At late S phase, 4% of nuclei showed distances < or =2 microm, 49% showed distances >6 microm, and 18% even showed distances >8 microm. A similar distance variability was found for Homo sapiens (HSA) 15 centromeres in a PWS patient with a deletion of the maternal AS/PWS locus and for the Beckwith-Wiedemann syndrome loci in human lymphocytes. A transient kiss during late S phase between loci widely separated at other stages of the cell cycle seems incompatible with known global constraints of chromatin movements in cycling cells. Further experiments suggest that the previously observed convergence of AS/PWS loci during late S phase was most likely a side effect of the convergence of nucleolus organizer region-bearing acrocentric human chromosomes, including HSA 15.

  19. Cell-cycle-independent transitions in temporal identity of mammalian neural progenitor cells.

    PubMed

    Okamoto, Mayumi; Miyata, Takaki; Konno, Daijiro; Ueda, Hiroki R; Kasukawa, Takeya; Hashimoto, Mitsuhiro; Matsuzaki, Fumio; Kawaguchi, Ayano

    2016-04-20

    During cerebral development, many types of neurons are sequentially generated by self-renewing progenitor cells called apical progenitors (APs). Temporal changes in AP identity are thought to be responsible for neuronal diversity; however, the mechanisms underlying such changes remain largely unknown. Here we perform single-cell transcriptome analysis of individual progenitors at different developmental stages, and identify a subset of genes whose expression changes over time but is independent of differentiation status. Surprisingly, the pattern of changes in the expression of such temporal-axis genes in APs is unaffected by cell-cycle arrest. Consistent with this, transient cell-cycle arrest of APs in vivo does not prevent descendant neurons from acquiring their correct laminar fates. Analysis of cultured APs reveals that transitions in AP gene expression are driven by both cell-intrinsic and -extrinsic mechanisms. These results suggest that the timing mechanisms controlling AP temporal identity function independently of cell-cycle progression and Notch activation mode.

  20. Cell Cycle Dependence of TRIAL Sensitivity in Prostate Cancer Cells

    DTIC Science & Technology

    2007-11-01

    Fig. 1: Effects of the autophagy inhibitor hydroxychloroquine (CQ) on PI-induced downregulation of HIF-1α. Cells were preincubated with CoCl2...of the mice (5 per group) survived therapy and displayed minimal weight loss. Therefore, it appears that a biologically effective dose of TRAIL can...be administered with an MTD dose of bortezomib without excessive toxicity. Fig. 5: Effects of an agonistic anti-DR5 antibody on apoptosis in PC

  1. Effects of simulated microgravity on cell cycle in human endothelial cells

    NASA Astrophysics Data System (ADS)

    Sokolovskaya, Alisa A.; Ignashkova, Tatiana I.; Bochenkova, Anna V.; Moskovtsev, Aleksey A.; Baranov, Victor M.; Kubatiev, Aslan A.

    2014-06-01

    The aim of the current study is to investigate effects of simulated microgravity on the cell cycle of endothelial cells. We analyze changes in the cell cycle after exposure of endothelial-like EA.hy 926 cells to simulated microgravity using a Desktop random positioning machine (RPM). Cell cycle profiles determined by flow cytometry show, that the percentage of the cells in the G0/G1 phase after 24 and 96 h of RPM-simulated microgravity is significantly increased as compared to the control group. However, no significant difference is observed after 120 h of RPM-simulated microgravity. In regard to S phase, the percentage of cells is significantly decreased after 24 and 96 h of RPM, respectively; whereas 120 h later, the number of S-phase cells is comparable to the control group. Thus, we show that simulated microgravity inhibits cell cycle progression of human EA.hy 926 cells from the G0/G1 phase to the S phase. We observe an effect of a hibernation-like state, when the growth of the cells in the RPM group slows down, but does not stop. Our results further show that simulated microgravity can affect adhesion of endothelial cells, and alpha-tubulin expression, as most cells begin to detach from the surface of OptiCell unit after 24 h, form aggregates after 48 h, and exhibit accumulation of alpha-tubulin around the nucleus after 48 h of exposure to simulated microgravity conditions. Our results demonstrate a chance in the cell cycle in a low gravitational field.

  2. Monitoring of dynamin during the Toxoplasma gondii cell cycle.

    PubMed

    Caldas, Lucio Ayres; Soares, Leandro Lemgruber; Henrique Seabra, Sergio; Attias, Marcia; de Souza, Wanderley

    2016-12-01

    The obligate intracellular protozoan parasite Toxoplasma gondii actively invades virtually all warm-blooded nucleated cells. This process results in a non-fusogenic vacuole, inside which the parasites replicate continuously until egress signaling is triggered. In this work, we investigated the role of the large GTPase dynamin in the interaction of T. gondii with the host cell by using laser and electron microscopy during three key stages: invasion, development and egress. The detection of dynamin during invasion indicates the occurrence of endocytosis, while T. gondii egress appeared to be independent of dynamin participation. However, the presence of dynamin during T. gondii development suggests that this molecule plays undescribed roles in the tachyzoite's cell cycle.

  3. Cell cycle RNA regulons coordinating early lymphocyte development.

    PubMed

    Galloway, Alison; Turner, Martin

    2017-02-23

    Lymphocytes undergo dynamic changes in gene expression as they develop from progenitor cells lacking antigen receptors, to mature cells that are prepared to mount immune responses. While transcription factors have established roles in lymphocyte development, they act in concert with post-transcriptional and post-translational regulators to determine the proteome. Furthermore, the post-transcriptional regulation of RNA regulons consisting of mRNAs whose protein products act cooperatively allows RNA binding proteins to exert their effects at multiple points in a pathway. Here, we review recent evidence demonstrating the importance of RNA binding proteins that control the cell cycle in lymphocyte development and discuss the implications for tumorigenesis. For further resources related to this article, please visit the WIREs website.

  4. Oscillatory Dynamics of Cell Cycle Proteins in Single Yeast Cells Analyzed by Imaging Cytometry

    PubMed Central

    Ball, David A.; Marchand, Julie; Poulet, Magaly; Baumann, William T.; Chen, Katherine C.; Tyson, John J.; Peccoud, Jean

    2011-01-01

    Progression through the cell division cycle is orchestrated by a complex network of interacting genes and proteins. Some of these proteins are known to fluctuate periodically during the cell cycle, but a systematic study of the fluctuations of a broad sample of cell-cycle proteins has not been made until now. Using time-lapse fluorescence microscopy, we profiled 16 strains of budding yeast, each containing GFP fused to a single gene involved in cell cycle regulation. The dynamics of protein abundance and localization were characterized by extracting the amplitude, period, and other indicators from a series of images. Oscillations of protein abundance could clearly be identified for Cdc15, Clb2, Cln1, Cln2, Mcm1, Net1, Sic1, and Whi5. The period of oscillation of the fluorescently tagged proteins is generally in good agreement with the inter-bud time. The very strong oscillations of Net1 and Mcm1 expression are remarkable since little is known about the temporal expression of these genes. By collecting data from large samples of single cells, we quantified some aspects of cell-to-cell variability due presumably to intrinsic and extrinsic noise affecting the cell cycle. PMID:22046265

  5. Coupling between the Circadian Clock and Cell Cycle Oscillators: Implication for Healthy Cells and Malignant Growth.

    PubMed

    Feillet, Celine; van der Horst, Gijsbertus T J; Levi, Francis; Rand, David A; Delaunay, Franck

    2015-01-01

    Uncontrolled cell proliferation is one of the key features leading to cancer. Seminal works in chronobiology have revealed that disruption of the circadian timing system in mice, either by surgical, genetic, or environmental manipulation, increased tumor development. In humans, shift work is a risk factor for cancer. Based on these observations, the link between the circadian clock and cell cycle has become intuitive. But despite identification of molecular connections between the two processes, the influence of the clock on the dynamics of the cell cycle has never been formally observed. Recently, two studies combining single live cell imaging with computational methods have shed light on robust coupling between clock and cell cycle oscillators. We recapitulate here these novel findings and integrate them with earlier results in both healthy and cancerous cells. Moreover, we propose that the cell cycle may be synchronized or slowed down through coupling with the circadian clock, which results in reduced tumor growth. More than ever, systems biology has become instrumental to understand the dynamic interaction between the circadian clock and cell cycle, which is critical in cellular coordination and for diseases such as cancer.

  6. Selection of mammalian cells based on their cell-cycle phase using dielectrophoresis

    PubMed Central

    Kim, Unyoung; Shu, Chih-Wen; Dane, Karen Y.; Daugherty, Patrick S.; Wang, Jean Y. J.; Soh, H. T.

    2007-01-01

    An effective, noninvasive means of selecting cells based on their phase within the cell cycle is an important capability for biological research. Current methods of producing synchronous cell populations, however, tend to disrupt the natural physiology of the cell or suffer from low synchronization yields. In this work, we report a microfluidic device that utilizes the dielectrophoresis phenomenon to synchronize cells by exploiting the relationship between the cell's volume and its phase in the cell cycle. The dielectrophoresis activated cell synchronizer (DACSync) device accepts an asynchronous mixture of cells at the inlet, fractionates the cell populations according to the cell-cycle phase (G1/S and G2/M), and elutes them through different outlets. The device is gentle and efficient; it utilizes electric fields that are 1–2 orders of magnitude below those used in electroporation and enriches asynchronous tumor cells in the G1 phase to 96% in one round of sorting, in a continuous flow manner at a throughput of 2 × 105 cells per hour per microchannel. This work illustrates the feasibility of using laminar flow and electrokinetic forces for the efficient, noninvasive separation of living cells. PMID:18093921

  7. Effects of cell cycle on the uptake of water soluble quantum dots by cells

    NASA Astrophysics Data System (ADS)

    Zheng, Shen; Chen, Ji-Yao; Wang, Jun-Yong; Zhou, Lu-Wei; Peng, Qian

    2011-12-01

    Quantum dots (QDs) with excellent optical properties have become powerful candidates for cell imaging. Although numerous reports have studied the uptake of QDs by cells, little information exists on the effects of cell cycle on the cellular QD uptake. In this report, the effects of cell cycle on the uptake of water soluble thiol-capped CdTe QDs by the human cervical carcinoma Hela cell line, human hepatocellular carcinoma QGY7701 cell line, and human embryonic kidney 293T cell line were studied by means of laser scanning confocal microscopy and flow cytometry. All three cell lines show to take up CdTe QDs via endocytosis. After arresting cells at specific phases with pharmacological agents, the cells in G2/M phase take up the most CdTe QDs, probably due to an increased membrane expansion during mitosis; whereas the cells in G1 phase do the least. A mathematical physics model was built to calculate the relative uptake rates of CdTe QDs by cells in different phases of the cell cycle, with the result as the uptake rate in G2/M phase is 2-4 times higher than that in G1 phase for these three cell lines. The results obtained from this study may provide the information useful for intracellular delivery of QDs.

  8. Impairment of cell cycle progression by sterigmatocystin in human pulmonary cells in vitro.

    PubMed

    Huang, Shujuan; Wang, Juan; Xing, Lingxiao; Shen, Haitao; Yan, Xia; Wang, Junling; Zhang, Xianghong

    2014-04-01

    Sterigmatocystin (ST) is a carcinogenic mycotoxin that is commonly found in human food, animal feed and in the indoor environment. Although the correlation between ST exposure and lung cancer has been widely reported in many studies, the cytotoxicity of ST on human pulmonary cells is not yet fully understood. In the current study, we found that ST could induce DNA double-strand breaks in a human immortalized bronchial epithelial cell line (BEAS-2B cells) and a human lung cancer cell line (A549 cells). In addition, the effects of ST on cell cycle arrest were complex and dependent on the tested ST concentration and cell type. Low concentrations of ST arrested cells in the G2/M phase in BEAS-2B cells and in the S phase in A549 cells, while at high concentration both cells lines were arrested in S and G2/M phases. Furthermore, we observed that the modulation of cyclins and CDK expression showed concomitant changes with cell cycle arrest upon ST exposure in BEAS-2B and A549 cells. In conclusion, ST induced DNA damage and affected key proteins involved in cell cycle regulation to trigger genomic instability, which may be a potential mechanism underlying the developmental basis of lung carcinogenesis.

  9. Effects of heavy ions on cycling stem cells

    NASA Astrophysics Data System (ADS)

    Hagan, Michael P.; Holahan, E. Vincent; Ainsworth, E. John

    Murine marrow stem cells assayed with the spleen colony assay have been shown to be largely in a noncycling state, Go. In the unirradiated animal where these spleen-colony forming units (CFUs) transit normally between a non-proliferative state and active proliferation, exposure to a sufficient dose of ionizing radiation increases the frequency (probability) of this transition. For low-LET irradiation, marrow stem cells are not induced into cycle until a threshold dose is achieved. This dose appears to be in the range 50 to 100 cGy, inducing proliferation in an all-or-nothing manner. For irradiation with heavy charged-particles, however, the threshold dose is dependent on mass and energy. Irradiation with particles of sufficient mass and energy stimulates active proliferation even at the smallest doses tested, 5 cGy. Further, this response does not appear to result from an all-or-nothing effect. Rather, individual animals with intermediate levels of stem cell cycling have been observed. These data support the notion that locally controlled hemopoiesis can be affected by local deposition of radiation damage.

  10. Naphthazarin enhances ionizing radiation-induced cell cycle arrest and apoptosis in human breast cancer cells.

    PubMed

    Kim, Min Young; Park, Seong-Joon; Shim, Jae Woong; Yang, Kwangmo; Kang, Ho Sung; Heo, Kyu

    2015-04-01

    Naphthazarin (Naph, DHNQ, 5,8-dihydroxy-l,4-naphthoquinone) is one of the naturally available 1,4-naphthoquinone derivatives that are well-known for their anti-inflammatory, antioxidant, antibacterial and antitumor cytotoxic effects in cancer cells. Herein, we investigated whether Naph has effects on cell cycle arrest and apoptosis in MCF-7 human breast cancer cells exposed to ionizing radiation (IR). Naph reduced the MCF-7 cell viability in a dose-dependent manner. We also found that Naph and/or IR increased the p53-dependent p21 (CIP/WAF1) promoter activity. Noteworthy, our ChIP assay results showed that Naph and IR combined treatment activated the p21 promoter via inhibition of binding of multi-domain proteins, DNMT1, UHRF1 and HDAC1. Apoptosis and cell cycle analyses demonstrated that Naph and IR combined treatment induced cell cycle arrest and apoptosis in MCF-7 cells. Herein, we showed that Naph treatment enhances IR-induced cell cycle arrest and death in MCF-7 human breast cancer cells through the p53-dependent p21 activation mechanism. These results suggest that Naph might sensitize breast cancer cells to radiotherapy by enhancing the p53-p21 mechanism activity.

  11. Smoc2 potentiates proliferation of hepatocellular carcinoma cells via promotion of cell cycle progression

    PubMed Central

    Su, Jing-Ran; Kuai, Jing-Hua; Li, Yan-Qing

    2016-01-01

    AIM To determine the influence of Smoc2 on hepatocellular carcinoma (HCC) cell proliferation and to find a possible new therapeutic target for preventing HCC progression. METHODS We detected expression of Smoc2 in HCC tissues and corresponding non-tumor liver (CNL) tissues using PCR, western blot, and immunohistochemistry methods. Subsequently, we down-regulated and up-regulated Smoc2 expression using siRNA and lentivirus transfection assay, respectively. Then, we identified the effect of Smoc2 on cell proliferation and cell cycle using CCK-8 and flow cytometry, respectively. The common cell growth signaling influenced by Smoc2 was detected by western blot assay. RESULTS The expression of Smoc2 was significantly higher in HCC tissues compared with CNL tissues. Overexpression of Smoc2 promoted HCC cell proliferation and cell cycle progression. Down-regulation of Smoc2 led to inhibition of cell proliferation and cell cycle progression. Smoc2 had positive effect on ERK and AKT signaling. CONCLUSION Smoc2 promotes the proliferation of HCC cells through accelerating cell cycle progression and might act as an anti-cancer therapeutic target in the future. PMID:28018113

  12. Chemosensitization of Cancer Cells via Gold Nanoparticle-Induced Cell Cycle Regulation

    PubMed Central

    Mackey, Megan A.; El-Sayed, Mostafa A.

    2015-01-01

    We have previously shown that plasmonic nanoparticles conjugated with nuclear-targeting and cytoplasm-targeting peptides (NLS and RGD, respectively) are capable of altering the cell cycle of human oral squamous carcinoma cells (HSC-3). In the present work, we show that this regulation of the cell cycle can be exploited to enhance the efficacy of a common chemotherapeutic agent, 5-Fluorouracil, by pre-treating cells with gold nanoparticles. Utilizing flow cytometry cell cycle analysis, we were able to quantify the 5-Fluorouracil efficacy as an accumulation of cells in the S phase with a depletion of cells in the G2/M phase. Two gold nanoparticle sizes were tested in this work; 30 nm with a surface plasmon resonance at 530 nm and 15 nm with a surface plasmon resonance at 520 nm. The 30 nm nuclear-targeted gold nanoparticles (NLS-AuNPs) showed the greatest 5-Fluorouracil efficacy enhancement when 5-Fluorouracil treatment (500 μM, 48 h) is preceded by a 24 h treatment with nanoparticles. In conclusion, we show that nuclear-targeted 30 nm gold nanoparticles enhance 5-Fluorouracil drug efficacy in HSC-3 cells via regulation of the cell cycle, a chemosensitization technique that could potentially be expanded to different cell lines and different chemotherapies. PMID:24329577

  13. Salidroside induces cell-cycle arrest and apoptosis in human breast cancer cells

    SciTech Connect

    Hu, Xiaolan; Zhang, Xianqi; Qiu, Shuifeng; Yu, Daihua; Lin, Shuxin

    2010-07-16

    Research highlights: {yields} Salidroside inhibits the growth of human breast cancer cells. {yields} Salidroside induces cell-cycle arrest of human breast cancer cells. {yields} Salidroside induces apoptosis of human breast cancer cell lines. -- Abstract: Recently, salidroside (p-hydroxyphenethyl-{beta}-D-glucoside) has been identified as one of the most potent compounds isolated from plants of the Rhodiola genus used widely in traditional Chinese medicine, but pharmacokinetic data on the compound are unavailable. We were the first to report the cytotoxic effects of salidroside on cancer cell lines derived from different tissues, and we found that human breast cancer MDA-MB-231 cells (estrogen receptor negative) were sensitive to the inhibitory action of low-concentration salidroside. To further investigate the cytotoxic effects of salidroside on breast cancer cells and reveal possible ER-related differences in response to salidroside, we used MDA-MB-231 cells and MCF-7 cells (estrogen receptor-positive) as models to study possible molecular mechanisms; we evaluated the effects of salidroside on cell growth characteristics, such as proliferation, cell cycle duration, and apoptosis, and on the expression of apoptosis-related molecules. Our results demonstrated for the first time that salidroside induces cell-cycle arrest and apoptosis in human breast cancer cells and may be a promising candidate for breast cancer treatment.

  14. MYC-repressed long noncoding RNAs antagonize MYC-induced cell proliferation and cell cycle progression

    PubMed Central

    Jeon, Young-Jun; Fadda, Paolo; Alder, Hansjuerg; Croce, Carlo M.

    2015-01-01

    The transcription factor MYC is a proto-oncogene regulating cell proliferation, cell cycle, apoptosis and metabolism. The recent identification of MYC-regulated long noncoding RNAs (lncRNAs) expands our knowledge of the role of lncRNAs in MYC functions. Here, we identify MYC-repressed lncRNAs named MYCLo-4, -5 and -6 by comparing 3 categories of lncRNAs (downregulated in highly MYC-expressing colorectal cancer, up-regulated by MYC knockdown in HCT116, upregulated by MYC knockdown in RKO). The MYC-repressed MYCLos are implicated in MYC-modulated cell proliferation through cell cycle regulation. By screening cell cycle-related genes regulated by MYC and the MYC-repressed MYCLos, we identified the MYC-repressed gene GADD45A as a target gene of the MYC-repressed MYCLos such as MYCLo-4 and MYCLo-6. PMID:26003165

  15. Pathobiology of Pneumocystis pneumonia: life cycle, cell wall and cell signal transduction.

    PubMed

    Skalski, Joseph H; Kottom, Theodore J; Limper, Andrew H

    2015-09-01

    Pneumocystis is a genus of ascomycetous fungi that are highly morbid pathogens in immunosuppressed humans and other mammals. Pneumocystis cannot easily be propagated in culture, which has greatly hindered understanding of its pathobiology. The Pneumocystis life cycle is intimately associated with its mammalian host lung environment, and life cycle progression is dependent on complex interactions with host alveolar epithelial cells and the extracellular matrix. The Pneumocystis cell wall is a varied and dynamic structure containing a dominant major surface glycoprotein, β-glucans and chitins that are important for evasion of host defenses and stimulation of the host immune system. Understanding of Pneumocystis cell signaling pathways is incomplete, but much has been deduced by comparison of the Pneumocystis genome with homologous genes and proteins in related fungi. In this mini-review, the pathobiology of Pneumocystis is reviewed, with particular focus on the life cycle, cell wall components and cell signal transduction.

  16. Forty-five years of cell-cycle genetics

    PubMed Central

    Reid, Brian J.; Culotti, Joseph G.; Nash, Robert S.; Pringle, John R.

    2015-01-01

    In the early 1970s, studies in Leland Hartwell’s laboratory at the University of Washington launched the genetic analysis of the eukaryotic cell cycle and set the path that has led to our modern understanding of this centrally important process. This 45th-anniversary Retrospective reviews the steps by which the project took shape, the atmosphere in which this happened, and the possible morals for modern times. It also provides an up-to-date look at the 35 original CDC genes and their human homologues. PMID:26628751

  17. Distinct modes of centromere protein dynamics during cell cycle progression in Drosophila S2R+ cells.

    PubMed

    Lidsky, Peter V; Sprenger, Frank; Lehner, Christian F

    2013-10-15

    Centromeres are specified epigenetically in animal cells. Therefore, faithful chromosome inheritance requires accurate maintenance of epigenetic centromere marks during progression through the cell cycle. Clarification of the mechanisms that control centromere protein behavior during the cell cycle should profit from the relatively simple protein composition of Drosophila centromeres. Thus we have analyzed the dynamics of the three key players Cid/Cenp-A, Cenp-C and Cal1 in S2R+ cells using quantitative microscopy and fluorescence recovery after photobleaching, in combination with novel fluorescent cell cycle markers. As revealed by the observed protein abundances and mobilities, centromeres proceed through at least five distinct states during the cell cycle, distinguished in part by unexpected Cid behavior. In addition to the predominant Cid loading onto centromeres during G1, a considerable but transient increase was detected during early mitosis. A low level of Cid loading was detected in late S and G2, starting at the reported time of centromere DNA replication. Our results reveal the complexities of Drosophila centromere protein dynamics and its intricate coordination with cell cycle progression.

  18. Magnolol causes alterations in the cell cycle in androgen insensitive human prostate cancer cells in vitro by affecting expression of key cell cycle regulatory proteins.

    PubMed

    McKeown, Brendan T; McDougall, Luke; Catalli, Adriana; Hurta, Robert A R

    2014-01-01

    Prostate cancer, one of the most common cancers in the Western world, affects many men worldwide. This study investigated the effects of magnolol, a compound found in the roots and bark of the magnolia tree Magnolia officinalis, on the behavior of 2 androgen insensitive human prostate cancer cell lines, DU145 and PC3, in vitro. Magnolol, in a 24-h exposure at 40 and 80 μM, was found to be cytotoxic to cells. Magnolol also affected cell cycle progression of DU145 and PC3 cells, resulting in alterations to the cell cycle and subsequently decreasing the proportion of cells entering the G2/M-phase of the cell cycle. Magnolol inhibited the expression of cell cycle regulatory proteins including cyclins A, B1, D1, and E, as well as CDK2 and CDK4. Protein expression levels of pRBp107 decreased and pRBp130 protein expression levels increased in response to magnolol exposure, whereas p16(INK4a), p21, and p27 protein expression levels were apparently unchanged post 24-h exposure. Magnolol exposure at 6 h did increase p27 protein expression levels. This study has demonstrated that magnolol can alter the behavior of androgen insensitive human prostate cancer cells in vitro and suggests that magnolol may have potential as a novel anti-prostate cancer agent.

  19. Berberine induces cell cycle arrest and apoptosis in human gastric carcinoma SNU-5 cell line

    PubMed Central

    Lin, Jing-Pin; Yang, Jai-Sing; Lee, Jau-Hong; Hsieh, Wen-Tsong; Chung, Jing-Gung

    2006-01-01

    AIM: To investigate the relationship between the inhibited growth (cytotoxic activity) of berberine and apoptotic pathway with its molecular mechanism of action. METHODS: The in vitro cytotoxic techniques were complemented by cell cycle analysis and determination of sub-G1 for apoptosis in human gastric carcinoma SNU-5 cells. Percentage of viable cells, cell cycle, and sub-G1 group (apoptosis) were examined and determined by the flow cytometric methods. The associated proteins for cell cycle arrest and apoptosis were examined by Western blotting. RESULTS: For SNU-5 cell line, the IC (50) was found to be 48 μmol/L of berberine. In SNU-5 cells treated with 25-200 μmol/L berberine, G2/M cell cycle arrest was observed which was associated with a marked increment of the expression of p53, Wee1 and CDk1 proteins and decreased cyclin B. A concentration-dependent decrease of cells in G0/G1 phase and an increase in G2/M phase were detected. In addition, apoptosis detected as sub-G0 cell population in cell cycle measurement was proved in 25-200 μmol/L berberine-treated cells by monitoring the apoptotic pathway. Apoptosis was identified by sub-G0 cell population, and upregulation of Bax, downregulation of Bcl-2, release of Ca2+, decreased the mitochondrial membrane potential and then led to the release of mitochondrial cytochrome C into the cytoplasm and caused the activation of caspase-3, and finally led to the occurrence of apoptosis. CONCLUSION: Berberine induces p53 expression and leads to the decrease of the mitochondrial membrane potential, Cytochrome C release and activation of caspase-3 for the induction of apoptosis. PMID:16440412

  20. Ethanol Metabolism Activates Cell Cycle Checkpoint Kinase, Chk2

    PubMed Central

    Clemens, Dahn L.; Mahan Schneider, Katrina J.; Nuss, Robert F.

    2011-01-01

    Chronic ethanol abuse results in hepatocyte injury and impairs hepatocyte replication. We have previously shown that ethanol metabolism results in cell cycle arrest at the G2/M transition, which is partially mediated by inhibitory phosphorylation of the cyclin-dependent kinase, Cdc2. To further delineate the mechanisms by which ethanol metabolism mediates this G2/M arrest, we investigated the involvement of upstream regulators of Cdc2 activity. Cdc2 is activated by the phosphatase Cdc25C. The activity of Cdc25C can, in turn, be regulated by the checkpoint kinase, Chk2, which is regulated by the kinase ataxia telangiectasia mutated (ATM). To investigate the involvement of these regulators of Cdc2 activity, VA-13 cells, which are Hep G2 cells modified to efficiently express alcohol dehydrogenase, were cultured in the presence or absence of 25 mM ethanol. Immunoblots were performed to determine the effects of ethanol metabolism on the activation of Cdc25C, Chk2, and ATM. Ethanol metabolism increased the active forms of ATM, and Chk2, as well as the phosphorylated form of Cdc25C. Additionally, inhibition of ATM resulted in approximately 50% of the cells being rescued from the G2/M cell cycle arrest, and ameliorated the inhibitory phosphorylation of Cdc2. Our findings demonstrate that ethanol metabolism activates ATM. ATM can activate the checkpoint kinase Chk2, resulting in phosphorylation of Cdc25C, and ultimately in the accumulation of inactive Cdc2. This may, in part, explain the ethanol metabolism-mediated impairment in hepatocyte replication, which may be important in the initiation and progression of alcoholic liver injury. PMID:21924579

  1. American cranberry (Vaccinium macrocarpon) extract affects human prostate cancer cell growth via cell cycle arrest by modulating expression of cell cycle regulators.

    PubMed

    Déziel, Bob; MacPhee, James; Patel, Kunal; Catalli, Adriana; Kulka, Marianna; Neto, Catherine; Gottschall-Pass, Katherine; Hurta, Robert

    2012-05-01

    Prostate cancer is one of the most common cancers in the world, and its prevalence is expected to increase appreciably in the coming decades. As such, more research is necessary to understand the etiology, progression and possible preventative measures to delay or to stop the development of this disease. Recently, there has been interest in examining the effects of whole extracts from commonly harvested crops on the behaviour and progression of cancer. Here, we describe the effects of whole cranberry extract (WCE) on the behaviour of DU145 human prostate cancer cells in vitro. Following treatment of DU145 human prostate cancer cells with 10, 25 and 50 μg ml⁻¹ of WCE, respectively for 6 h, WCE significantly decreased the cellular viability of DU145 cells. WCE also decreased the proportion of cells in the G2-M phase of the cell cycle and increased the proportion of cells in the G1 phase of the cell cycle following treatment of cells with 25 and 50 μg ml⁻¹ treatment of WCE for 6 h. These alterations in cell cycle were associated with changes in cell cycle regulatory proteins and other cell cycle associated proteins. WCE decreased the expression of CDK4, cyclin A, cyclin B1, cyclin D1 and cyclin E, and increased the expression of p27. Changes in p16(INK4a) and pRBp107 protein expression levels also were evident, however, the changes noted in p16(INK4a) and pRBp107 protein expression levels were not statistically significant. These findings demonstrate that phytochemical extracts from the American cranberry (Vaccinium macrocarpon) can affect the behaviour of human prostate cancer cells in vitro and further support the potential health benefits associated with cranberries.

  2. INTEGRATED GASIFICATION COMBINED CYCLE PROJECT 2 MW FUEL CELL DEMONSTRATION

    SciTech Connect

    FuelCell Energy

    2005-05-16

    With about 50% of power generation in the United States derived from coal and projections indicating that coal will continue to be the primary fuel for power generation in the next two decades, the Department of Energy (DOE) Clean Coal Technology Demonstration Program (CCTDP) has been conducted since 1985 to develop innovative, environmentally friendly processes for the world energy market place. The 2 MW Fuel Cell Demonstration was part of the Kentucky Pioneer Energy (KPE) Integrated Gasification Combined Cycle (IGCC) project selected by DOE under Round Five of the Clean Coal Technology Demonstration Program. The participant in the CCTDP V Project was Kentucky Pioneer Energy for the IGCC plant. FuelCell Energy, Inc. (FCE), under subcontract to KPE, was responsible for the design, construction and operation of the 2 MW fuel cell power plant. Duke Fluor Daniel provided engineering design and procurement support for the balance-of-plant skids. Colt Engineering Corporation provided engineering design, fabrication and procurement of the syngas processing skids. Jacobs Applied Technology provided the fabrication of the fuel cell module vessels. Wabash River Energy Ltd (WREL) provided the test site. The 2 MW fuel cell power plant utilizes FuelCell Energy's Direct Fuel Cell (DFC) technology, which is based on the internally reforming carbonate fuel cell. This plant is capable of operating on coal-derived syngas as well as natural gas. Prior testing (1992) of a subscale 20 kW carbonate fuel cell stack at the Louisiana Gasification Technology Inc. (LGTI) site using the Dow/Destec gasification plant indicated that operation on coal derived gas provided normal performance and stable operation. Duke Fluor Daniel and FuelCell Energy developed a commercial plant design for the 2 MW fuel cell. The plant was designed to be modular, factory assembled and truck shippable to the site. Five balance-of-plant skids incorporating fuel processing, anode gas oxidation, heat recovery, water

  3. Methods of Synchronization of Yeast Cells for the Analysis of Cell Cycle Progression.

    PubMed

    Juanes, M Angeles

    2017-01-01

    Cell division is a fascinating and fundamental process that sustains life. By this process, unicellular organisms reproduce and multicellular organisms sustain development, growth, and tissue repair. Division of a mother cell gives rise to two daughter cells according to an ordered set of events within four successive phases called G1 (gap1), S (DNA Synthesis), G2 (gap2), and M (Mitosis) phase. How these different phases are orchestrated to ensure the physical separation of the two daughter cells is a tightly regulated process. Indeed, inappropriate cell division could lead to uncontrolled cell proliferation and ultimately to cancer. Saccharomyces cerevisiae is an excellent model system for unraveling the secrets of cell division. A large community of researchers has chosen budding yeast as a model because of its advantages: rapid growth in simple and economical media, tractable genetics, powerful biochemistry, cell biology, and proteomics approaches. Furthermore, the cell cycle mechanisms, as elucidated in yeast, are conserved in higher eukaryotes. The ability to synchronize and get large numbers of cells in a particular stage of the cell cycle is crucial to properly explore the mechanisms of the cell cycle. An overview of the most common yeast synchronization techniques has been compiled in this chapter.

  4. Pulmonary IL-17E (IL-25) production and IL-17RB+ myeloid cell-derived Th2 cytokine production are dependent upon stem cell factor-induced responses during chronic allergic pulmonary disease.

    PubMed

    Dolgachev, Vladislav; Petersen, Bryan C; Budelsky, Alison L; Berlin, Aaron A; Lukacs, Nicholas W

    2009-11-01

    In the present studies local neutralization of allergen-induced stem cell factor (SCF) leads to decreased production of Th2 cytokines, a reduction in inflammation, allergen-specific serum IgE/IgG1, and attenuation of severe asthma-like responses. The local blockade of pulmonary SCF also resulted in a significant reduction of IL-17E (IL-25). Sorted cell populations from the lung indicated that IL-25 was produced from c-kit(+) cells, whereas Th2 cytokine production was primarily from c-kit(-) cell populations. SCF stimulated c-kit(+) eosinophils produced IL-25, whereas bone marrow-derived mast cells did not. Using 4get mice that contain a IL-4-IRES-eGFP that when transcribed coexpress GFP and IL-4, our studies identified cells that comprised a CD11b(+), GR1(+), Ly6C(+/-), c-kit(-), CD4(-), CD11c(-), MHC class II(low) cell population as a source of IL-4 in the lung after chronic allergen challenge. In the bone marrow a similar cell was identified with approximately a third of the IL-4(+) cells also expressing c-kit(+). The pulmonary and bone marrow IL-4(+) cell populations were significantly reduced upon local pulmonary anti-SCF treatment. Subsequently, when IL-25R was examined during the chronic allergen responses the expression was found on the IL-4(+) myeloid cell population that expressed CD11b(+)GR1(+). Interestingly, the IL-25R(+) cells in the bone marrow were also all CD11b(+)GR1(+), similar to the lung cells, but they were also all c-kit(+), potentially suggesting a maturation of the bone marrow cell once it enters the lung and/or is stimulated by SCF. Overall, these studies suggest a complex relationship between SCF, bone marrow-derived IL-25-responsive myeloid cells, Th2 cytokines, and chronic allergic disease.

  5. A genetic interaction map of cell cycle regulators

    PubMed Central

    Billmann, Maximilian; Horn, Thomas; Fischer, Bernd; Sandmann, Thomas; Huber, Wolfgang; Boutros, Michael

    2016-01-01

    Cell-based RNA interference (RNAi) is a powerful approach to screen for modulators of many cellular processes. However, resulting candidate gene lists from cell-based assays comprise diverse effectors, both direct and indirect, and further dissecting their functions can be challenging. Here we screened a genome-wide RNAi library for modulators of mitosis and cytokinesis in Drosophila S2 cells. The screen identified many previously known genes as well as modulators that have previously not been connected to cell cycle control. We then characterized ∼300 candidate modifiers further by genetic interaction analysis using double RNAi and a multiparametric, imaging-based assay. We found that analyzing cell cycle–relevant phenotypes increased the sensitivity for associating novel gene function. Genetic interaction maps based on mitotic index and nuclear size grouped candidates into known regulatory complexes of mitosis or cytokinesis, respectively, and predicted previously uncharacterized components of known processes. For example, we confirmed a role for the Drosophila CCR4 mRNA processing complex component l(2)NC136 during the mitotic exit. Our results show that the combination of genome-scale RNAi screening and genetic interaction analysis using process-directed phenotypes provides a powerful two-step approach to assigning components to specific pathways and complexes. PMID:26912791

  6. Stochastic model of yeast cell-cycle network

    NASA Astrophysics Data System (ADS)

    Zhang, Yuping; Qian, Minping; Ouyang, Qi; Deng, Minghua; Li, Fangting; Tang, Chao

    2006-07-01

    Biological functions in living cells are controlled by protein interaction and genetic networks. These molecular networks should be dynamically stable against various fluctuations which are inevitable in the living world. In this paper, we propose and study a stochastic model for the network regulating the cell cycle of the budding yeast. The stochasticity in the model is controlled by a temperature-like parameter β. Our simulation results show that both the biological stationary state and the biological pathway are stable for a wide range of “temperature”. There is, however, a sharp transition-like behavior at βc, below which the dynamics are dominated by noise. We also define a pseudo energy landscape for the system in which the biological pathway can be seen as a deep valley.

  7. Microarray Analysis of Cell Cycle Gene Expression in Adult Human Corneal Endothelial Cells

    PubMed Central

    Ha Thi, Binh Minh; Campolmi, Nelly; He, Zhiguo; Pipparelli, Aurélien; Manissolle, Chloé; Thuret, Jean-Yves; Piselli, Simone; Forest, Fabien; Peoc'h, Michel; Garraud, Olivier; Gain, Philippe; Thuret, Gilles

    2014-01-01

    Corneal endothelial cells (ECs) form a monolayer that controls the hydration of the cornea and thus its transparency. Their almost nil proliferative status in humans is responsible, in several frequent diseases, for cell pool attrition that leads to irreversible corneal clouding. To screen for candidate genes involved in cell cycle arrest, we studied human ECs subjected to various environments thought to induce different proliferative profiles compared to ECs in vivo. Donor corneas (a few hours after death), organ-cultured (OC) corneas, in vitro confluent and non-confluent primary cultures, and an immortalized EC line were compared to healthy ECs retrieved in the first minutes of corneal grafts. Transcriptional profiles were compared using a cDNA array of 112 key genes of the cell cycle and analysed using Gene Ontology classification; cluster analysis and gene map presentation of the cell cycle regulation pathway were performed by GenMAPP. Results were validated using qRT-PCR on 11 selected genes. We found several transcripts of proteins implicated in cell cycle arrest and not previously reported in human ECs. Early G1-phase arrest effectors and multiple DNA damage-induced cell cycle arrest-associated transcripts were found in vivo and over-represented in OC and in vitro ECs. Though highly proliferative, immortalized ECs also exhibited overexpression of transcripts implicated in cell cycle arrest. These new effectors likely explain the stress-induced premature senescence that characterizes human adult ECs. They are potential targets for triggering and controlling EC proliferation with a view to increasing the cell pool of stored corneas or facilitating mass EC culture for bioengineered endothelial grafts. PMID:24747418

  8. Robust synchronization of coupled circadian and cell cycle oscillators in single mammalian cells.

    PubMed

    Bieler, Jonathan; Cannavo, Rosamaria; Gustafson, Kyle; Gobet, Cedric; Gatfield, David; Naef, Felix

    2014-07-15

    Circadian cycles and cell cycles are two fundamental periodic processes with a period in the range of 1 day. Consequently, coupling between such cycles can lead to synchronization. Here, we estimated the mutual interactions between the two oscillators by time-lapse imaging of single mammalian NIH3T3 fibroblasts during several days. The analysis of thousands of circadian cycles in dividing cells clearly indicated that both oscillators tick in a 1:1 mode-locked state, with cell divisions occurring tightly 5 h before the peak in circadian Rev-Erbα-YFP reporter expression. In principle, such synchrony may be caused by either unidirectional or bidirectional coupling. While gating of cell division by the circadian cycle has been most studied, our data combined with stochastic modeling unambiguously show that the reverse coupling is predominant in NIH3T3 cells. Moreover, temperature, genetic, and pharmacological perturbations showed that the two interacting cellular oscillators adopt a synchronized state that is highly robust over a wide range of parameters. These findings have implications for circadian function in proliferative tissues, including epidermis, immune cells, and cancer.

  9. Control of sleep by a network of cell cycle genes.

    PubMed

    Afonso, Dinis J S; Machado, Daniel R; Koh, Kyunghee

    2015-01-01

    Sleep is essential for health and cognition, but the molecular and neural mechanisms of sleep regulation are not well understood. We recently reported the identification of TARANIS (TARA) as a sleep-promoting factor that acts in a previously unknown arousal center in Drosophila. tara mutants exhibit a dose-dependent reduction in sleep amount of up to ∼60%. TARA and its mammalian homologs, the Trip-Br (Transcriptional Regulators Interacting with PHD zinc fingers and/or Bromodomains) family of proteins, are primarily known as transcriptional coregulators involved in cell cycle progression, and contain a conserved Cyclin-A (CycA) binding homology domain. We found that tara and CycA synergistically promote sleep, and CycA levels are reduced in tara mutants. Additional data demonstrated that Cyclin-dependent kinase 1 (Cdk1) antagonizes tara and CycA to promote wakefulness. Moreover, we identified a subset of CycA expressing neurons in the pars lateralis, a brain region proposed to be analogous to the mammalian hypothalamus, as an arousal center. In this Extra View article, we report further characterization of tara mutants and provide an extended discussion of our findings and future directions within the framework of a working model, in which a network of cell cycle genes, tara, CycA, and Cdk1, interact in an arousal center to regulate sleep.

  10. Control of sleep by a network of cell cycle genes

    PubMed Central

    Afonso, Dinis J. S.; Machado, Daniel R.; Koh, Kyunghee

    2015-01-01

    ABSTRACT Sleep is essential for health and cognition, but the molecular and neural mechanisms of sleep regulation are not well understood. We recently reported the identification of TARANIS (TARA) as a sleep-promoting factor that acts in a previously unknown arousal center in Drosophila. tara mutants exhibit a dose-dependent reduction in sleep amount of up to ∼60%. TARA and its mammalian homologs, the Trip-Br (Transcriptional Regulators Interacting with PHD zinc fingers and/or Bromodomains) family of proteins, are primarily known as transcriptional coregulators involved in cell cycle progression, and contain a conserved Cyclin-A (CycA) binding homology domain. We found that tara and CycA synergistically promote sleep, and CycA levels are reduced in tara mutants. Additional data demonstrated that Cyclin-dependent kinase 1 (Cdk1) antagonizes tara and CycA to promote wakefulness. Moreover, we identified a subset of CycA expressing neurons in the pars lateralis, a brain region proposed to be analogous to the mammalian hypothalamus, as an arousal center. In this Extra View article, we report further characterization of tara mutants and provide an extended discussion of our findings and future directions within the framework of a working model, in which a network of cell cycle genes, tara, CycA, and Cdk1, interact in an arousal center to regulate sleep. PMID:26925838

  11. Valproic acid induces apoptosis and cell cycle arrest in poorly differentiated thyroid cancer cells.

    PubMed

    Catalano, Maria G; Fortunati, Nicoletta; Pugliese, Mariateresa; Costantino, Lucia; Poli, Roberta; Bosco, Ornella; Boccuzzi, Giuseppe

    2005-03-01

    Poorly differentiated thyroid carcinoma is an aggressive human cancer that is resistant to conventional therapy. Histone deacetylase inhibitors are a promising class of drugs, acting as antiproliferative agents by promoting differentiation, as well as inducing apoptosis and cell cycle arrest. Valproic acid (VPA), a class I selective histone deacetylase inhibitor widely used as an anticonvulsant, promotes differentiation in poorly differentiated thyroid cancer cells by inducing Na(+)/I(-) symporter and increasing iodine uptake. Here, we show that it is also highly effective at suppressing growth in poorly differentiated thyroid cancer cell lines (N-PA and BHT-101). Apoptosis induction and cell cycle arrest are the underlying mechanisms of VPA's effect on cell growth. It induces apoptosis by activating the intrinsic pathway; caspases 3 and 9 are activated but not caspase 8. Cell cycle is selectively arrested in G(1) and is associated with the increased expression of p21 and the reduced expression of cyclin A. Both apoptosis and cell cycle arrest are induced by treatment with 1 mm VPA, a dose that promotes cell redifferentiation and that is slightly above the serum concentration reached in patients treated for epilepsy. These multifaceted properties make VPA of clinical interest as a new approach to treating poorly differentiated thyroid cancer.

  12. Hesa-A Effects on Cell Cycle Signaling in Esophageal Carcinoma Cell Line

    PubMed Central

    Ahmadian, Nasser; Pashaei-Asl, Roghiyeh; Samadi, Nasser; Rahmati-yamchi, Mohammad; Rashidi, Mohammad-Reza; Ahmadian, Masomeh; Esmaeili, Moosa; Salamat, Faezeh; Besharat, Sima; Joshaghani, Hamid Reza

    2016-01-01

    BACKGROUND Hesa-A is a natural compound with anticancer properties. The exact mechanism of its action in esophageal cancer is not clear, yet. The aim of this study was to evaluate the cell toxicity effect of Hesa-A on the esophageal carcinoma cell lines, KYSE-30, and cell cycle genes expression. METHODS In this study, we tested cell toxicity with MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay and flow cytometry to evaluatet he cell cycle arrest. Real time polymerase chain reaction was used to assess the expression of P53, P16, P21, cyclin D1, and cyclin B1 genes. RESULTS Our results showed that Hesa-A is effective in the expression of cell cycling check point proteins. Hesa-A induced an arrest in G2 phase of esophageal cell cycle. The levels of P53 (>13 times), P21 (>21 times), P16, cyclin B1, and cyclin D1 genes were increased 48 hours after Hesa-A treatment. CONCLUSION P21 and P16 expression were the potential mechanisms for G2 arrest of KYSE-30 esophageal cancer cell line by Hesa-A. PMID:27957293

  13. Induction of cell cycle arrest in prostate cancer cells by the dietary compound isoliquiritigenin.

    PubMed

    Lee, Yeo Myeong; Lim, Do Young; Choi, Hyun Ju; Jung, Jae In; Chung, Won-Yoon; Park, Jung Han Yoon

    2009-02-01

    Isoliquiritigenin (ISL), a flavonoid chalcone that is present in licorice, shallot, and bean sprouts, is known to have antitumorigenic activities. The present study examined whether ISL alters prostate cancer cell cycle progression. DU145 human and MatLyLu (MLL) rat prostate cancer cells were cultured with various concentrations of ISL. In both DU145 and MLL cells treated with ISL, the percentage of cells in the G1 phase increased, and the incorporation of [(3)H]thymidine decreased. ISL decreased the protein levels of cyclin D1, cyclin E, and cyclin-dependent kinase (CDK) 4, whereas cyclin A and CDK2 expressions were unaltered in cells treated with ISL. The expression of the CDK inhibitor p27(KIP1) was increased in cells treated with 20 micromol/L ISL. In addition, treatment of cells with 20 micromol/L ISL for 24 hours led to G2/M cell cycle arrest. Cell division control (CDC) 2 protein levels remained unchanged. The protein levels of phospho-CDC2 (Tyr15) and cyclin B1 were increased, and the CDC25C level was decreased by ISL dose-dependently. We demonstrate that ISL promotes cell cycle arrest in DU145 and MLL cells, thereby providing insights into the mechanisms underlying its antitumorigenic activities.

  14. Sphingosine-1-phosphate receptor 3 influences cell cycle progression in muscle satellite cells.

    PubMed

    Fortier, Mathieu; Figeac, Nicolas; White, Robert B; Knopp, Paul; Zammit, Peter S

    2013-10-15

    Skeletal muscle retains a resident stem cell population called satellite cells, which are mitotically quiescent in mature muscle, but can be activated to produce myoblast progeny for muscle homeostasis, hypertrophy and repair. We have previously shown that satellite cell activation is partially controlled by the bioactive phospholipid, sphingosine-1-phosphate, and that S1P biosynthesis is required for muscle regeneration. Here we investigate the role of sphingosine-1-phosphate receptor 3 (S1PR3) in regulating murine satellite cell function. S1PR3 levels were high in quiescent myogenic cells before falling during entry into cell cycle. Retrovirally-mediated constitutive expression of S1PR3 led to suppressed cell cycle progression in satellite cells, but did not overtly affect the myogenic program. Conversely, satellite cells isolated from S1PR3-null mice exhibited enhanced proliferation ex-vivo. In vivo, acute cardiotoxin-induced muscle regeneration was enhanced in S1PR3-null mice, with bigger muscle fibres compared to control mice. Importantly, genetically deleting S1PR3 in the mdx mouse model of Duchenne muscular dystrophy produced a less severe muscle dystrophic phenotype, than when signalling though S1PR3 was operational. In conclusion, signalling though S1PR3 suppresses cell cycle progression to regulate function in muscle satellite cells.

  15. Andrographolide inhibits hepatoma cells growth and affects the expression of cell cycle related proteins.

    PubMed

    Shen, Kai-Kai; Liu, Tian-Yu; Xu, Chong; Ji, Li-Li; Wang, Zheng-Tao

    2009-09-01

    The present study is aimed to investigate the toxic effects of andrographolide (Andro) on hepatoma cells and elucidate its preliminary mechanisms. After cells were treated with different concentrations of Andro (0-50 micromol x L(-1)) for 24 h, cell viability was evaluated with 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay. Furthermore, after hepatoma cells (Hep3B and HepG2) were treated with different concentrations of Andro (0-30 micromol x L(-1)) for 14 d, the number of colony formation was accounted under microscope. Cell cycle related proteins such as Cdc-2, phosphorylated-Cdc-2, Cyclin B and Cyclin D1 were detected with Western blotting assay and the cell cycle was analyzed by flow cytometry using propidium iodide staining. MTT results showed that Andro induced growth inhibition of hepatoma cells in a concentration-dependent manner but had no significant effects on human normal liver L-02 cells. Andro dramatically decreased the colony formation of hepatoma cells in the concentration-dependent manner. Moreover, Andro induced a decrease of Hep3B cells at the G0-G1 phase and a concomitant accumulation of cells at G2-M phase. At the molecular level, Western blotting results showed that Andro decreased the expression of Cdc-2, phosphorylated-Cdc-2, Cyclin D1 and Cyclin B proteins in a time-dependent manner, which are all cell cycle related proteins. Taken together, the results demonstrated that Andro specifically inhibited the growth of hepatoma cells and cellular cell cycle related proteins were possibly involved in this process.

  16. Effects of cell-cycle-dependent expression on random fluctuations in protein levels

    PubMed Central

    Soltani, Mohammad

    2016-01-01

    Expression of many genes varies as a cell transitions through different cell-cycle stages. How coupling between stochastic expression and cell cycle impacts cell-to-cell variability (noise) in the level of protein is not well understood. We analyse a model where a stable protein is synthesized in random bursts, and the frequency with which bursts occur varies within the cell cycle. Formulae quantifying the extent of fluctuations in the protein copy number are derived and decomposed into components arising from the cell cycle and stochastic processes. The latter stochastic component represents contributions from bursty expression and errors incurred during partitioning of molecules between daughter cells. These formulae reveal an interesting trade-off: cell-cycle dependencies that amplify the noise contribution from bursty expression also attenuate the contribution from partitioning errors. We investigate the existence of optimum strategies for coupling expression to the cell cycle that minimize the stochastic component. Intriguingly, results show that a zero production rate throughout the cell cycle, with expression only occurring just before cell division, minimizes noise from bursty expression for a fixed mean protein level. By contrast, the optimal strategy in the case of partitioning errors is to make the protein just after cell division. We provide examples of regulatory proteins that are expressed only towards the end of the cell cycle, and argue that such strategies enhance robustness of cell-cycle decisions to the intrinsic stochasticity of gene expression. PMID:28083102

  17. Effects of cell-cycle-dependent expression on random fluctuations in protein levels.

    PubMed

    Soltani, Mohammad; Singh, Abhyudai

    2016-12-01

    Expression of many genes varies as a cell transitions through different cell-cycle stages. How coupling between stochastic expression and cell cycle impacts cell-to-cell variability (noise) in the level of protein is not well understood. We analyse a model where a stable protein is synthesized in random bursts, and the frequency with which bursts occur varies within the cell cycle. Formulae quantifying the extent of fluctuations in the protein copy number are derived and decomposed into components arising from the cell cycle and stochastic processes. The latter stochastic component represents contributions from bursty expression and errors incurred during partitioning of molecules between daughter cells. These formulae reveal an interesting trade-off: cell-cycle dependencies that amplify the noise contribution from bursty expression also attenuate the contribution from partitioning errors. We investigate the existence of optimum strategies for coupling expression to the cell cycle that minimize the stochastic component. Intriguingly, results show that a zero production rate throughout the cell cycle, with expression only occurring just before cell division, minimizes noise from bursty expression for a fixed mean protein level. By contrast, the optimal strategy in the case of partitioning errors is to make the protein just after cell division. We provide examples of regulatory proteins that are expressed only towards the end of the cell cycle, and argue that such strategies enhance robustness of cell-cycle decisions to the intrinsic stochasticity of gene expression.

  18. Live-cell monitoring of periodic gene expression in synchronous human cells identifies Forkhead genes involved in cell cycle control.

    PubMed

    Grant, Gavin D; Gamsby, Joshua; Martyanov, Viktor; Brooks, Lionel; George, Lacy K; Mahoney, J Matthew; Loros, Jennifer J; Dunlap, Jay C; Whitfield, Michael L

    2012-08-01

    We developed a system to monitor periodic luciferase activity from cell cycle-regulated promoters in synchronous cells. Reporters were driven by a minimal human E2F1 promoter with peak expression in G1/S or a basal promoter with six Forkhead DNA-binding sites with peak expression at G2/M. After cell cycle synchronization, luciferase activity was measured in live cells at 10-min intervals across three to four synchronous cell cycles, allowing unprecedented resolution of cell cycle-regulated gene expression. We used this assay to screen Forkhead transcription factors for control of periodic gene expression. We confirmed a role for FOXM1 and identified two novel cell cycle regulators, FOXJ3 and FOXK1. Knockdown of FOXJ3 and FOXK1 eliminated cell cycle-dependent oscillations and resulted in decreased cell proliferation rates. Analysis of genes regulated by FOXJ3 and FOXK1 showed that FOXJ3 may regulate a network of zinc finger proteins and that FOXK1 binds to the promoter and regulates DHFR, TYMS, GSDMD, and the E2F binding partner TFDP1. Chromatin immunoprecipitation followed by high-throughput sequencing analysis identified 4329 genomic loci bound by FOXK1, 83% of which contained a FOXK1-binding motif. We verified that a subset of these loci are activated by wild-type FOXK1 but not by a FOXK1 (H355A) DNA-binding mutant.

  19. Glucose capped silver nanoparticles induce cell cycle arrest in HeLa cells.

    PubMed

    Panzarini, Elisa; Mariano, Stefania; Vergallo, Cristian; Carata, Elisabetta; Fimia, Gian Maria; Mura, Francesco; Rossi, Marco; Vergaro, Viviana; Ciccarella, Giuseppe; Corazzari, Marco; Dini, Luciana

    2017-02-20

    This study aims to determine the interaction (uptake and biological effects on cell viability and cell cycle progression) of glucose capped silver nanoparticles (AgNPs-G) on human epithelioid cervix carcinoma (HeLa) cells, in relation to amount, 2×10(3) or 2×10(4) NPs/cell, and exposure time, up to 48h. The spherical and well dispersed AgNPs (30±5nm) were obtained by using glucose as reducing agent in a green synthesis method that ensures to stabilize AgNPs avoiding cytotoxic soluble silver ions Ag(+) release. HeLa cells take up abundantly and rapidly AgNPs-G resulting toxic to cells in amount and incubation time dependent manner. HeLa cells were arrested at S and G2/M phases of the cell cycle and subG1 population increased when incubated with 2×10(4) AgNPs-G/cell. Mitotic index decreased accordingly. The dissolution experiments demonstrated that the observed effects were due only to AgNPs-G since glucose capping prevents Ag(+) release. The AgNPs-G influence on HeLa cells viability and cell cycle progression suggest that AgNPs-G, alone or in combination with chemotherapeutics, may be exploited for the development of novel antiproliferative treatment in cancer therapy. However, the possible influence of the cell cycle on cellular uptake of AgNPs-G and the mechanism of AgNPs entry in cells need further investigation.

  20. Cell cycle synchronization of canine ear fibroblasts for somatic cell nuclear transfer.

    PubMed

    Koo, Ok Jae; Hossein, Mohammad Shamim; Hong, So Gun; Martinez-Conejero, Jose A; Lee, Byeong Chun

    2009-02-01

    Cycle synchronization of donor cells in the G0/G1 stage is a crucial step for successful somatic cell nuclear transfer. In the present report, we evaluated the effects of contact inhibition, serum starvation and the reagents - dimethyl sulphoxide (DMSO), roscovitine and cycloheximide (CHX) - on synchronization of canine fibroblasts at the G0/G1 stage. Ear fibroblast cells were collected from a beagle dog, placed into culture and used for analysis at passages three to eight. The population doubling time was 36.5 h. The proportion of G0/G1 cells was significantly increased by contact inhibition (77.1%) as compared with cycling cells (70.1%); however, extending the duration of culture did not induce further synchronization. After 24 h of serum starvation, cells were effectively synchronized at G0/G1 (77.1%). Although synchronization was further increased gradually after 24 h and even showed significant difference after 72 h (82.8%) of starvation, the proportion of dead cells also significantly increased after 24 h. The percentage of cells at the G0/G1 phase was increased (as compared with controls) after 72 h treatment with DMSO (76.1%) and after 48 h treatment with CHX (73.0%) or roscovitine (72.5%). However, the rate of cell death was increased after 24 and 72 h of treatment with DMSO and CHX, respectively. Thus, we recommend the use of roscovitine for cell cycle synchronization of canine ear fibroblasts as a preparatory step for SCNT.

  1. Stromal interaction molecule 1 regulates growth, cell cycle, and apoptosis of human tongue squamous carcinoma cells.

    PubMed

    Cui, Xiaobo; Song, Laixiao; Bai, Yunfei; Wang, Yaping; Wang, Boqian; Wang, Wei

    2017-04-30

    Oral tongue squamous cell carcinoma (OTSCC) is the most common type of oral carcinomas. However, the molecular mechanism by which OTSCC developed is not fully identified. Stromal interaction molecule 1 (STIM1) is a transmembrane protein, mainly located in the endoplasmic reticulum (ER). STIM1 is involved in several types of cancers. Here, we report that STIM1 contributes to the development of human OTSCC. We knocked down STIM1 in OTSCC cell line Tca-8113 with lentivirus-mediated shRNA and found that STIM1 knockdown repressed the proliferation of Tca-8113 cells. In addition, we also showed that STIM1 deficiency reduced colony number of Tca-8113 cells. Knockdown of STIM1 repressed cells to enter M phase of cell cycle and induced cellular apoptosis. Furthermore, we performed microarray and bioinformatics analysis and found that STIM1 was associated with p53 and MAPK pathways, which may contribute to the effects of STIM1 on cell growth, cell cycle, and apoptosis. Finally, we confirmed that STIM1 controlled the expression of MDM2, cyclin-dependent kinase 4 (CDK4), and growth arrest and DNA damage inducible α (GADD45A) in OTSCC cells. In conclusion, we provide evidence that STIM1 contributes to the development of OTSCC partially through regulating p53 and MAPK pathways to promote cell cycle and survival.

  2. Cycle life test and failure model of nickel-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Smithrick, J. J.

    1983-01-01

    Six ampere hour individual pressure vessel nickel hydrogen cells were charge/discharge cycled to failure. Failure as used here is defined to occur when the end of discharge voltage degraded to 0.9 volts. They were cycled under a low earth orbit cycle regime to a deep depth of discharge (80 percent of rated ampere hour capacity). Both cell designs were fabricated by the same manufacturer and represent current state of the art. A failure model was advanced which suggests both cell designs have inadequate volume tolerance characteristics. The limited existing data base at a deep depth of discharge (DOD) was expanded. Two cells of each design were cycled. One COMSAT cell failed at cycle 1712 and the other failed at cycle 1875. For the Air Force/Hughes cells, one cell failed at cycle 2250 and the other failed at cycle 2638. All cells, of both designs, failed due to low end of discharge voltage (0.9 volts). No cell failed due to electrical shorts. After cell failure, three different reconditioning tests (deep discharge, physical reorientation, and open circuit voltage stand) were conducted on all cells of each design. A fourth reconditioning test (electrolyte addition) was conducted on one cell of each design. In addition post cycle cell teardown and failure analysis were performed on the one cell of each design which did not have electrolyte added after failure.

  3. Cycle life test and failure model of nickel-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Smithrick, J. J.

    1983-01-01

    Six ampere hour individual pressure vessel nickel hydrogen cells were charge/discharge cycled to failure. Failure as used here is defined to occur when the end of discharge voltage degraded to 0.9 volts. They were cycled under a low earth orbit cycle regime to a deep depth of discharge (80 percent of rated ampere hour capacity). Both cell designs were fabricated by the same manufacturer and represent current state of the art. A failure model was advanced which suggests both cell designs have inadequate volume tolerance characteristics. The limited existing data base at a deep depth of discharge (DOD) was expanded. Two cells of each design were cycled. One COMSAT cell failed at cycle 1712 and the other failed at cycle 1875. For the Air Force/Hughes cells, one cell failed at cycle 2250 and the other failed at cycle 2638. All cells, of both designs, failed due to low end of discharge voltage (0.9 volts). No cell failed due to electrical shorts. After cell failure, three different reconditioning tests (deep discharge, physical reorientation, and open circuit voltage stand) were conducted on all cells of each design. A fourth reconditioning test (electrolyte addition) was conducted on one cell of each design. In addition post cycle cell teardown and failure analysis were performed on the one cell of each design which did not have electrolyte added after failure. Previously announced in STAR as N83-25038

  4. Cell cycle progression dictates the requirement for BCL2 in natural killer cell survival.

    PubMed

    Viant, Charlotte; Guia, Sophie; Hennessy, Robert J; Rautela, Jai; Pham, Kim; Bernat, Claire; Goh, Wilford; Jiao, Yuhao; Delconte, Rebecca; Roger, Michael; Simon, Vanina; Souza-Fonseca-Guimaraes, Fernando; Grabow, Stephanie; Belz, Gabrielle T; Kile, Benjamin T; Strasser, Andreas; Gray, Daniel; Hodgkin, Phillip D; Beutler, Bruce; Vivier, Eric; Ugolini, Sophie; Huntington, Nicholas D

    2017-02-01

    Natural killer (NK) cells are innate lymphoid cells with antitumor functions. Using an N-ethyl-N-nitrosourea (ENU)-induced mutagenesis screen in mice, we identified a strain with an NK cell deficiency caused by a hypomorphic mutation in the Bcl2 (B cell lymphoma 2) gene. Analysis of these mice and the conditional deletion of Bcl2 in NK cells revealed a nonredundant intrinsic requirement for BCL2 in NK cell survival. In these mice, NK cells in cycle were protected against apoptosis, and NK cell counts were restored in inflammatory conditions, suggesting a redundant role for BCL2 in proliferating NK cells. Consistent with this, cycling NK cells expressed higher MCL1 (myeloid cell leukemia 1) levels in both control and BCL2-null mice. Finally, we showed that deletion of BIM restored survival in BCL2-deficient but not MCL1-deficient NK cells. Overall, these data demonstrate an essential role for the binding of BCL2 to BIM in the survival of noncycling NK cells. They also favor a model in which MCL1 is the dominant survival protein in proliferating NK cells.

  5. Gold nanoparticle sensitize radiotherapy of prostate cancer cells by regulation of the cell cycle

    NASA Astrophysics Data System (ADS)

    Roa, Wilson; Zhang, Xiaojing; Guo, Linghong; Shaw, Andrew; Hu, Xiuying; Xiong, Yeping; Gulavita, Sunil; Patel, Samir; Sun, Xuejun; Chen, Jie; Moore, Ronald; Xing, James Z.

    2009-09-01

    Glucose-capped gold nanoparticles (Glu-GNPs) have been used to improve cellular targeting and radio-sensitization. In this study, we explored the mechanism of Glu-GNP enhanced radiation sensitivity in radiation-resistant human prostate cancer cells. Cell survival and proliferation were measured using MTT and clonogenic assay. Flow cytometry with staining by propidium iodide (PI) was performed to study the cell cycle changes induced by Glu-GNPs, and western blotting was used to determine the expression of p53 and cyclin proteins that correlated to cell cycle regulation. With 2 Gy of ortho-voltage irradiation, Glu-GNP showed a 1.5-2.0 fold enhancement in growth inhibition when compared to x-rays alone. Comparing the cell cycle change, Glu-GNPs induced acceleration in the G0/G1 phase and accumulation of cells in the G2/M phase at 29.8% versus 18.4% for controls at 24 h. G2/M arrest was accompanied by decreased expression of p53 and cyclin A, and increased expression of cyclin B1 and cyclin E. In conclusion, Glu-GNPs trigger activation of the CDK kinases leading to cell cycle acceleration in the G0/G1 phase and accumulation in the G2/M phase. This activation is accompanied by a striking sensitization to ionizing radiation, which may have clinical implications.

  6. Changes in microtubule phosphorylation during cell cycle of HeLa cells.

    PubMed Central

    Piras, R; Piras, M M

    1975-01-01

    The phosphorylation in vitro and in vivo of tubulin isolated from HeLa cells has been examined during the cell cylce. The results obtained indicate that: (a) the protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) activity present in the microtubules, and measured in vitro with exogenous casein as substrate, is maximal in M cells, whereas that present in the cytosol is nearly constant during the S, G-2, and M stages, and decreases during G-1; (b) the patterns through the cell cycle of the maximal number of tubulin sites phosphorylated in vitro and of the microtubular protein kinase activity are similar; (c) the degree of tubulin phosphorylation in vivo is 2- to 3-fold higher in the microtubules isolated from the S and M stages of the cell cycle, than those from G-1 and G-2. This variable phosphate content of tubulin through the cell cycle suggests that such covalent modification might be important to enable tubulin to carry over some of its functions during the cell cycle. Images PMID:1055373

  7. Lineage-specific interface proteins match up the cell cycle and differentiation in embryo stem cells.

    PubMed

    Re, Angela; Workman, Christopher T; Waldron, Levi; Quattrone, Alessandro; Brunak, Søren

    2014-09-01

    The shortage of molecular information on cell cycle changes along embryonic stem cell (ESC) differentiation prompts an in silico approach, which may provide a novel way to identify candidate genes or mechanisms acting in coordinating the two programs. We analyzed germ layer specific gene expression changes during the cell cycle and ESC differentiation by combining four human cell cycle transcriptome profiles with thirteen in vitro human ESC differentiation studies. To detect cross-talk mechanisms we then integrated the transcriptome data that displayed differential regulation with protein interaction data. A new class of non-transcriptionally regulated genes was identified, encoding proteins which interact systematically with proteins corresponding to genes regulated during the cell cycle or cell differentiation, and which therefore can be seen as interface proteins coordinating the two programs. Functional analysis gathered insights in fate-specific candidates of interface functionalities. The non-transcriptionally regulated interface proteins were found to be highly regulated by post-translational ubiquitylation modification, which may synchronize the transition between cell proliferation and differentiation in ESCs.

  8. Ectopic cell cycle proteins predict the sites of neuronal cell death in Alzheimer's disease brain.

    PubMed

    Busser, J; Geldmacher, D S; Herrup, K

    1998-04-15

    Alzheimer's disease (AD) is a major dementing illness characterized by regional concentrations of senile plaques, neurofibrillary tangles, and extensive neuronal cell death. Although cell and synaptic loss is most directly linked to the severity of symptoms, the mechanisms leading to the neuronal death remain unclear. Based on evidence linking neuronal death during development to unexpected reappearance of cell cycle events, we investigated the brains of 12 neuropathologically verified cases of Alzheimer's disease and eight age-matched, disease-free controls for the presence of cell cycle proteins. Aberrant expression of cyclin D, cdk4, proliferating cell nuclear antigen, and cyclin B1 were identified in the hippocampus, subiculum, locus coeruleus, and dorsal raphe nuclei, but not inferotemporal cortex or cerebellum of AD cases. With only one exception, control subjects showed no significant expression of cell cycle markers in any of the six regions. We propose that disregulation of various components of the cell cycle is a significant contributor to regionally specific neuronal death in AD.

  9. G1 to S phase cell cycle transition in somatic and embryonic stem cells

    PubMed Central

    Neganova, Irina; Lako, Majlinda

    2008-01-01

    It is well known that G1 to S phase transition is tightly regulated by the expression and phosphorylation of a number of well-characterized cyclins, cyclin-dependent kinases and members of the retinoblastoma gene family. In this review we discuss the role of these components in regulation of G1 to S phase transition in somatic cells and human embryonic stem cells. Most importantly, we discuss some new tenable links between maintenance of pluripotency and cell cycle regulation in embryonic stem cells by describing the role that master transcription factors play in this process. Finally, the differences in cell cycle regulation between murine and human embryonic stem cells are highlighted, raising interesting questions regarding their biology and stages of embryonic development from which they have been derived. PMID:18638068

  10. Cell cycle specificity of Fas-mediated apoptosis in WIL-2 cells.

    PubMed

    Beletskaya, I V; Nikonova, L V; Beletsky, I P

    1997-07-21

    Antibodies to Fas/APO1 receptor induce effective apoptosis in WIL-2 cells of the human B-lymphoid line. Quantitative assessment of the extent of the death in cells synchronized by thymidine block revealed a significant increase in their sensitivity to the cytocidal effect mediated by Fas/APO1 during the G1 phase of the cell cycle. Western analysis of the content of the p53 antigen in the cytoplasm and nuclei of the cells showed that the Fas/APO1-induced death is accompanied by massive translocation of the p53 from the cytoplasm to the nucleus. These findings suggest that cell vulnerability to the Fas/APO1-mediated apoptosis is subjected to regulation by cell cycle-dependent mechanisms, one of which is probably the function of the p53 antigen.

  11. Cell cycle regulation of embryonic stem cells and mouse embryonic fibroblasts lacking functional Pax7

    PubMed Central

    Czerwinska, Areta M.; Nowacka, Joanna; Aszer, Magdalena; Fogtman, Anna; Iwanicka-Nowicka, Roksana; Jańczyk-Ilach, Katarzyna; Ciemerych, Maria A.; Grabowska, Iwona

    2016-01-01

    ABSTRACT The transcription factor Pax7 plays a key role during embryonic myogenesis and in adult organisms in that it sustains the proper function of satellite cells, which serve as adult skeletal muscle stem cells. Recently we have shown that lack of Pax7 does not prevent the myogenic differentiation of pluripotent stem cells. In the current work we show that the absence of functional Pax7 in differentiating embryonic stem cells modulates cell cycle facilitating their proliferation. Surprisingly, deregulation of Pax7 function also positively impacts at the proliferation of mouse embryonic fibroblasts. Such phenotypes seem to be executed by modulating the expression of positive cell cycle regulators, such as cyclin E. PMID:27610933

  12. Discovery of a Splicing Regulator Required for Cell Cycle Progression

    SciTech Connect

    Suvorova, Elena S.; Croken, Matthew; Kratzer, Stella; Ting, Li-Min; Conde de Felipe, Magnolia; Balu, Bharath; Markillie, Lye Meng; Weiss, Louis M.; Kim, Kami; White, Michael W.

    2013-02-01

    In the G1 phase of the cell division cycle, eukaryotic cells prepare many of the resources necessary for a new round of growth including renewal of the transcriptional and protein synthetic capacities and building the machinery for chromosome replication. The function of G1 has an early evolutionary origin and is preserved in single and multicellular organisms, although the regulatory mechanisms conducting G1 specific functions are only understood in a few model eukaryotes. Here we describe a new G1 mutant from an ancient family of apicomplexan protozoans. Toxoplasma gondii temperature-sensitive mutant 12-109C6 conditionally arrests in the G1 phase due to a single point mutation in a novel protein containing a single RNA-recognition-motif (TgRRM1). The resulting tyrosine to asparagine amino acid change in TgRRM1 causes severe temperature instability that generates an effective null phenotype for this protein when the mutant is shifted to the restrictive temperature. Orthologs of TgRRM1 are widely conserved in diverse eukaryote lineages, and the human counterpart (RBM42) can functionally replace the missing Toxoplasma factor. Transcriptome studies demonstrate that gene expression is downregulated in the mutant at the restrictive temperature due to a severe defect in splicing that affects both cell cycle and constitutively expressed mRNAs. The interaction of TgRRM1 with factors of the tri-SNP complex (U4/U6 & U5 snRNPs) indicate this factor may be required to assemble an active spliceosome. Thus, the TgRRM1 family of proteins is an unrecognized and evolutionarily conserved class of splicing regulators. This study demonstrates investigations into diverse unicellular eukaryotes, like the Apicomplexa, have the potential to yield new insights into important mechanisms conserved across modern eukaryotic kingdoms.

  13. TRPC6 regulates cell cycle progression by modulating membrane potential in bone marrow stromal cells

    PubMed Central

    Ichikawa, Jun; Inoue, Ryuji

    2014-01-01

    Background and Purpose Ca2+ influx is important for cell cycle progression, but the mechanisms involved seem to vary. We investigated the potential roles of transient receptor potential (TRP) channels and store-operated Ca2+ entry (SOCE)-related molecules STIM (stromal interaction molecule)/Orai in the cell cycle progression of rat bone marrow stromal cells (BMSCs), a reliable therapeutic resource for regenerative medicine. Experimental Approach PCR and immunoblot analyses were used to examine mRNA and protein levels, fluorescence imaging and patch clamping for Ca2+ influx and membrane potential measurements, and flow cytometry for cell cycle analysis. Key Results Cell cycle synchronization of BMSCs revealed S phase-specific enhancement of TRPC1, STIM and Orai mRNA and protein expression. In contrast, TRPC6 expression decreased in the S phase and increased in the G1 phase. Resting membrane potential (RMP) of BMSCs was most negative and positive in the S and G1 phases, respectively, and was accompanied by an enhancement and attenuation of SOCE respectively. Chemically depolarizing/hyperpolarizing the membrane erased these differences in SOCE magnitude during the cell cycle. siRNA knockdown of TRPC6 produced a negative shift in RMP, increased SOCE and caused redistribution of BMSCs with increased populations in the S and G2/M phases and accumulation of cyclins A2 and B1. A low concentration of Gd3+ (1 μM) suppressed BMSC proliferation at its concentration to inhibit SOC channels relatively specifically. Conclusions and Implications TRPC6, by changing the membrane potential, plays a pivotal role in controlling the SOCE magnitude, which is critical for cell cycle progression of BMSCs. This finding provides a new therapeutic strategy for regulating BMSC proliferation. PMID:25041367

  14. The Yeast Cyclin-Dependent Kinase Routes Carbon Fluxes to Fuel Cell Cycle Progression.

    PubMed

    Ewald, Jennifer C; Kuehne, Andreas; Zamboni, Nicola; Skotheim, Jan M

    2016-05-19

    Cell division entails a sequence of processes whose specific demands for biosynthetic precursors and energy place dynamic requirements on metabolism. However, little is known about how metabolic fluxes are coordinated with the cell division cycle. Here, we examine budding yeast to show that more than half of all measured metabolites change significantly through the cell division cycle. Cell cycle-dependent changes in central carbon metabolism are controlled by the cyclin-dependent kinase (Cdk1), a major cell cycle regulator, and the metabolic regulator protein kinase A. At the G1/S transition, Cdk1 phosphorylates and activates the enzyme Nth1, which funnels the storage carbohydrate trehalose into central carbon metabolism. Trehalose utilization fuels anabolic processes required to reliably complete cell division. Thus, the cell cycle entrains carbon metabolism to fuel biosynthesis. Because the oscillation of Cdk activity is a conserved feature of the eukaryotic cell cycle, we anticipate its frequent use in dynamically regulating metabolism for efficient proliferation.

  15. Quantitative imaging with Fucci and mathematics to uncover temporal dynamics of cell cycle progression.

    PubMed

    Saitou, Takashi; Imamura, Takeshi

    2016-01-01

    Cell cycle progression is strictly coordinated to ensure proper tissue growth, development, and regeneration of multicellular organisms. Spatiotemporal visualization of cell cycle phases directly helps us to obtain a deeper understanding of controlled, multicellular, cell cycle progression. The fluorescent ubiquitination-based cell cycle indicator (Fucci) system allows us to monitor, in living cells, the G1 and the S/G2/M phases of the cell cycle in red and green fluorescent colors, respectively. Since the discovery of Fucci technology, it has found numerous applications in the characterization of the timing of cell cycle phase transitions under diverse conditions and various biological processes. However, due to the complexity of cell cycle dynamics, understanding of specific patterns of cell cycle progression is still far from complete. In order to tackle this issue, quantitative approaches combined with mathematical modeling seem to be essential. Here, we review several studies that attempted to integrate Fucci technology and mathematical models to obtain quantitative information regarding cell cycle regulatory patterns. Focusing on the technological development of utilizing mathematics to retrieve meaningful information from the Fucci producing data, we discuss how the combined methods advance a quantitative understanding of cell cycle regulation.

  16. Effects of flavonoids on the growth and cell cycle of cancer cells.

    PubMed

    Choi, S U; Ryu, S Y; Yoon, S K; Jung, N P; Park, S H; Kim, K H; Choi, E J; Lee, C O

    1999-01-01

    In this study, we investigated the cytotoxicities of flavone (F01), 3-hydroxyflavone (F02), 6- hydroxyflavone (F03), 7-hydroxyflavone (F04), 3,6-dihydroxyflavone (F05), 5,7-dihydroxyflavone (F06) and 5,6,7-trihydroxyflavone (F07) to human cancer cells including P- glycoprotein (Pgp)-expressing HCT15 cells and its multidrug resistant subline, HCT15/CL02 cells. We also examined the effects of those flavonoids on the cell cycle of these cancer cells. HCT15/CL02 cells did not reveal resistance to all the flavonoids tested in comparison with HCT15 cells. In cell cycle analysis, all the flavonoids tested, except F01 and F04, reduced the G0/G1 population of SF295 cells at growth inhibitory concentrations, and increased G2/M (F02, F03 and F06) or S (F05 and F07) populations. In addition, F02 and F03 decreased the G2/M and G0/G1 population, and increased the S and G2/M population in HCT15 cells, respectively. Meanwhile, in HCT15/CL02 cells, F02 and F03 decreased the G0/G1 populations and increased the S population. In conclusion, we deemed that the flavonoids tested had diverse cytotoxic mechanisms, and exerted their cell growth inhibitory or killing activity by distinctive ways in different cells.

  17. Cell-cycle quiescence maintains Caenorhabditis elegans germline stem cells independent of GLP-1/Notch

    PubMed Central

    Seidel, Hannah S; Kimble, Judith

    2015-01-01

    Many types of adult stem cells exist in a state of cell-cycle quiescence, yet it has remained unclear whether quiescence plays a role in maintaining the stem cell fate. Here we establish the adult germline of Caenorhabditis elegans as a model for facultative stem cell quiescence. We find that mitotically dividing germ cells—including germline stem cells—become quiescent in the absence of food. This quiescence is characterized by a slowing of S phase, a block to M-phase entry, and the ability to re-enter M phase rapidly in response to re-feeding. Further, we demonstrate that cell-cycle quiescence alters the genetic requirements for stem cell maintenance: The signaling pathway required for stem cell maintenance under fed conditions—GLP-1/Notch signaling—becomes dispensable under conditions of quiescence. Thus, cell-cycle quiescence can itself maintain stem cells, independent of the signaling pathway otherwise essential for such maintenance. DOI: http://dx.doi.org/10.7554/eLife.10832.001 PMID:26551561

  18. Proteomic analysis of the response to cell cycle arrests in human myeloid leukemia cells

    PubMed Central

    Ly, Tony; Endo, Aki; Lamond, Angus I

    2015-01-01

    Abstract Previously, we analyzed protein abundance changes across a ‘minimally perturbed’ cell cycle by using centrifugal elutriation to differentially enrich distinct cell cycle phases in human NB4 cells (Ly et al., 2014). In this study, we compare data from elutriated cells with NB4 cells arrested at comparable phases using serum starvation, hydroxyurea, or RO-3306. While elutriated and arrested cells have similar patterns of DNA content and cyclin expression, a large fraction of the proteome changes detected in arrested cells are found to reflect arrest-specific responses (i.e., starvation, DNA damage, CDK1 inhibition), rather than physiological cell cycle regulation. For example, we show most cells arrested in G2 by CDK1 inhibition express abnormally high levels of replication and origin licensing factors and are likely poised for genome re-replication. The protein data are available in the Encyclopedia of Proteome Dynamics (http://www.peptracker.com/epd/), an online, searchable resource. DOI: http://dx.doi.org/10.7554/eLife.04534.001 PMID:25555159

  19. Tcf3 and cell cycle factors contribute to butyrate resistance in colorectal cancer cells

    SciTech Connect

    Chiaro, Christopher; Lazarova, Darina L.; Bordonaro, Michael

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer We investigate mechanisms responsible for butyrate resistance in colon cancer cells. Black-Right-Pointing-Pointer Tcf3 modulates butyrate's effects on Wnt activity and cell growth in resistant cells. Black-Right-Pointing-Pointer Tcf3 modulation of butyrate's effects differ by cell context. Black-Right-Pointing-Pointer Cell cycle factors are overexpressed in the resistant cells. Black-Right-Pointing-Pointer Reversal of altered gene expression can enhance the anti-cancer effects of butyrate. -- Abstract: Butyrate, a fermentation product of dietary fiber, inhibits clonal growth in colorectal cancer (CRC) cells dependent upon the fold induction of Wnt activity. We have developed a CRC cell line (HCT-R) that, unlike its parental cell line, HCT-116, does not respond to butyrate exposure with hyperactivation of Wnt signaling and suppressed clonal growth. PCR array analyses revealed Wnt pathway-related genes, the expression of which differs between butyrate-sensitive HCT-116 CRC cells and their butyrate-resistant HCT-R cell counterparts. We identified overexpression of Tcf3 as being partially responsible for the butyrate-resistant phenotype, as this DNA-binding protein suppresses the hyperinduction of Wnt activity by butyrate. Consequently, Tcf3 knockdown in HCT-R cells restores their sensitivity to the effects of butyrate on Wnt activity and clonal cell growth. Interestingly, the effects of overexpressed Tcf3 differ between HCT-116 and HCT-R cells; thus, in HCT-116 cells Tcf3 suppresses proliferation without rendering the cells resistant to butyrate. In HCT-R cells, however, the overexpression of Tcf3 inhibits Wnt activity, and the cells are still able to proliferate due to the higher expression levels of cell cycle factors, particularly those driving the G{sub 1} to S transition. Knowledge of the molecular mechanisms determining the variable sensitivity of CRC cells to butyrate may assist in developing approaches that prevent or

  20. Imaging Nuclear Morphology and Organization in Cleared Plant Tissues Treated with Cell Cycle Inhibitors.

    PubMed

    de Souza Junior, José Dijair Antonino; de Sa, Maria Fatima Grossi; Engler, Gilbert; Engler, Janice de Almeida

    2016-01-01

    Synchronization of root cells through chemical treatment can generate a large number of cells blocked in specific cell cycle phases. In plants, this approach can be employed for cell suspension cultures and plant seedlings. To identify plant cells in the course of the cell cycle, especially during mitosis in meristematic tissues, chemical inhibitors can be used to block cell cycle progression. Herein, we present a simplified and easy-to-apply protocol to visualize mitotic figures, nuclei morphology, and organization in whole Arabidopsis root apexes. The procedure is based on tissue clearing, and fluorescent staining of nuclear DNA with DAPI. The protocol allows carrying out bulk analysis of nuclei and cell cycle phases in root cells and will be valuable to investigate mutants like overexpressing lines of genes disturbing the plant cell cycle.

  1. SPARC expression induces cell cycle arrest via STAT3 signaling pathway in medulloblastoma cells

    SciTech Connect

    Chetty, Chandramu; Dontula, Ranadheer; Gujrati, Meena; Lakka, Sajani S.

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer Ectopic expression of SPARC impaired cell proliferation in medulloblastoma cells. Black-Right-Pointing-Pointer SPARC expression induces STAT3 mediated cell cycle arrest in medulloblastoma cells. Black-Right-Pointing-Pointer SPARC expression significantly inhibited pre-established tumor growth in nude-mice. -- Abstract: Dynamic cell interaction with ECM components has profound influence in cancer progression. SPARC is a component of the ECM, impairs the proliferation of different cell types and modulates tumor cell aggressive features. We previously reported that SPARC expression significantly impairs medulloblastoma tumor growth in vivo. In this study, we demonstrate that expression of SPARC inhibits medulloblastoma cell proliferation. MTT assay indicated a dose-dependent reduction in tumor cell proliferation in adenoviral mediated expression of SPARC full length cDNA (Ad-DsRed-SP) in D425 and UW228 cells. Flow cytometric analysis showed that Ad-DsRed-SP-infected cells accumulate in the G2/M phase of cell cycle. Further, immunoblot and immunoprecipitation analyses revealed that SPARC induced G2/M cell cycle arrest was mediated through inhibition of the Cyclin-B-regulated signaling pathway involving p21 and Cdc2 expression. Additionally, expression of SPARC decreased STAT3 phosphorylation at Tyr-705; constitutively active STAT3 expression reversed SPARC induced G2/M arrest. Ad-DsRed-SP significantly inhibited the pre-established orthotopic tumor growth and tumor volume in nude-mice. Immunohistochemical analysis of tumor sections from mice treated with Ad-DsRed-SP showed decreased immunoreactivity for pSTAT3 and increased immunoreactivity for p21 compared to tumor section from mice treated with mock and Ad-DsRed. Taken together our studies further reveal that STAT3 plays a key role in SPARC induced G2/M arrest in medulloblastoma cells. These new findings provide a molecular basis for the mechanistic understanding of the

  2. Measuring cell cycle progression kinetics with metabolic labeling and flow cytometry.

    PubMed

    Fleisig, Helen; Wong, Judy

    2012-05-22

    Precise control of the initiation and subsequent progression through the various phases of the cell cycle are of paramount importance in proliferating cells. Cell cycle division is an integral part of growth and reproduction and deregulation of key cell cycle components have been implicated in the precipitating events of carcinogenesis. Molecular agents in anti-cancer therapies frequently target biological pathways responsible for the regulation and coordination of cell cycle division. Although cell cycle kinetics tend to vary according to cell type, the distribution of cells amongst the four stages of the cell cycle is rather consistent within a particular cell line due to the consistent pattern of mitogen and growth factor expression. Genotoxic events and other cellular stressors can result in a temporary block of cell cycle progression, resulting in arrest or a temporary pause in a particular cell cycle phase to allow for instigation of the appropriate response mechanism. The ability to experimentally observe the behavior of a cell population with reference to their cell cycle progression stage is an important advance in cell biology. Common procedures such as mitotic shake off, differential centrifugation or flow cytometry-based sorting are used to isolate cells at specific stages of the cell cycle. These fractionated, cell cycle phase-enriched populations are then subjected to experimental treatments. Yield, purity and viability of the separated fractions can often be compromised using these physical separation methods. As well, the time lapse between separation of the cell populations and the start of experimental treatment, whereby the fractionated cells can progress from the selected cell cycle stage, can pose significant challenges in the successful implementation and interpretation of these experiments. Other approaches to study cell cycle stages include the use of chemicals to synchronize cells. Treatment of cells with chemical inhibitors of key

  3. Dynamical Modeling of the Cell Cycle and Cell Fate Emergence in Caulobacter crescentus

    PubMed Central

    Quiñones-Valles, César; Sánchez-Osorio, Ismael; Martínez-Antonio, Agustino

    2014-01-01

    The division of Caulobacter crescentus, a model organism for studying cell cycle and differentiation in bacteria, generates two cell types: swarmer and stalked. To complete its cycle, C. crescentus must first differentiate from the swarmer to the stalked phenotype. An important regulator involved in this process is CtrA, which operates in a gene regulatory network and coordinates many of the interactions associated to the generation of cellular asymmetry. Gaining insight into how such a differentiation phenomenon arises and how network components interact to bring about cellular behavior and function demands mathematical models and simulations. In this work, we present a dynamical model based on a generalization of the Boolean abstraction of gene expression for a minimal network controlling the cell cycle and asymmetric cell division in C. crescentus. This network was constructed from data obtained from an exhaustive search in the literature. The results of the simulations based on our model show a cyclic attractor whose configurations can be made to correspond with the current knowledge of the activity of the regulators participating in the gene network during the cell cycle. Additionally, we found two point attractors that can be interpreted in terms of the network configurations directing the two cell types. The entire network is shown to be operating close to the critical regime, which means that it is robust enough to perturbations on dynamics of the network, but adaptable to environmental changes. PMID:25369202

  4. Mast cells as modulators of hair follicle cycling.

    PubMed

    Maurer, M; Paus, R; Czarnetzki, B M

    1995-08-01

    While the central role of mast cells (MC) in allergy and inflammation is well-appreciated, much less is known about their physiological functions. The impressive battery of potent growth modulatory MC products, and increasing evidence of MC involvement in hyperproliferative and fibrotic disorders suggest that tissue remodelling may be one of those, namely in the skin. Here, we delineate why this may best be studied by analysing the potential role of MC in hair growth regulation. On the background of numerous, yet widely under-appreciated hints from the older literature, we summarize and discuss our recent observations from the C57BL/6 mouse model for hair research which support the concept that MC are functionally important modulators of hair follicle cycling, specifically during anagen development. This invites to exploit the murine hair cycle as a model for dissecting the physiological growth modulatory functions of MC and encourages the exploration of MC-targeting pharmaceutical strategies for the treatment of hair growth disorders.

  5. Pterostilbene induces apoptosis and cell cycle arrest in diffuse large B-cell lymphoma cells

    PubMed Central

    Kong, Yuanyuan; Chen, Gege; Xu, Zhijian; Yang, Guang; Li, Bo; Wu, Xiaosong; Xiao, Wenqin; Xie, Bingqian; Hu, Liangning; Sun, Xi; Chang, Gaomei; Gao, Minjie; Gao, Lu; Dai, Bojie; Tao, Yi; Zhu, Weiliang; Shi, Jumei

    2016-01-01

    Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL). Pterostilbene, a natural dimethylated analog of resveratrol, has been shown to possess diverse pharmacological activities, including anti-inflammatory, antioxidant and anticancer properties. However, to the best of our knowledge, there has been no study of the effects of pterostilbene upon hematological malignancies. Herein, we report the antitumor activity and mechanism of pterostilbene against DLBCL cells both in vitro and in vivo. We found that pterostilbene treatment resulted in a dose-dependent inhibition of cell viability. In addition, pterostilbene exhibited a strong cytotoxic effect, as evidenced not only by reductions of mitochondrial membrane potential (MMP) but also by increases in cellular apoptotic index and reactive oxygen species (ROS) levels, leading to arrest in the S-phase of the cell cycle. Furthermore, pterostilbene treatment directly up-regulated p-p38MAPK and down-regulated p-ERK1/2. In vivo, intravenous administration of pterostilbene inhibited tumor development in xenograft mouse models. Overall, the results suggested that pterostilbene is a potential anti-cancer pharmaceutical against human DLBCL by a mechanism involving the suppression of ERK1/2 and activation of p38MAPK signaling pathways. PMID:27869173

  6. Cold Nights Impair Leaf Growth and Cell Cycle Progression in Maize through Transcriptional Changes of Cell Cycle Genes1[W][OA

    PubMed Central

    Rymen, Bart; Fiorani, Fabio; Kartal, Fatma; Vandepoele, Klaas; Inzé, Dirk; Beemster, Gerrit T.S.

    2007-01-01

    Low temperature inhibits the growth of maize (Zea mays) seedlings and limits yield under field conditions. To study the mechanism of cold-induced growth retardation, we exposed maize B73 seedlings to low night temperature (25°C /4°C, day/night) from germination until the completion of leaf 4 expansion. This treatment resulted in a 20% reduction in final leaf size compared to control conditions (25°C/18°C, day/night). A kinematic analysis of leaf growth rates in control and cold-treated leaves during daytime showed that cold nights affected both cell cycle time (+65%) and cell production (−22%). In contrast, the size of mature epidermal cells was unaffected. To analyze the effect on cell cycle progression at the molecular level, we identified through a bioinformatics approach a set of 43 cell cycle genes and analyzed their expression in proliferating, expanding, and mature cells of leaves exposed to either control or cold nights. This analysis showed that: (1) the majority of cell cycle genes had a consistent proliferation-specific expression pattern; and (2) the increased cell cycle time in the basal meristem of leaves exposed to cold nights was associated with differential expression of cell cycle inhibitors and with the concomitant down-regulation of positive regulators of cell division. PMID:17208957

  7. Dihydroartemisinin (DHA) induces ferroptosis and causes cell cycle arrest in head and neck carcinoma cells.

    PubMed

    Lin, Renyu; Zhang, Ziheng; Chen, Lingfeng; Zhou, Yunfang; Zou, Peng; Feng, Chen; Wang, Li; Liang, Guang

    2016-10-10

    Head and neck cancer is the sixth most common cancer worldwide. Dihydroartemisinin (DHA), a semi-synthetic derivative of artemisinin, exhibits a wide range of biological roles including a highly efficient and specific anti-tumor activity. Here, we aimed to examine the effect of DHA on head and neck carcinoma cells and elucidate the potential mechanisms. We used five head and neck carcinoma cell lines and two non-tumorigenic normal epithelial cell lines to achieve our goals. Cells were exposed to DHA and subjected to cellular activity assays including viability, cell cycle analysis, cell death, and angiogenic phenotype. Our results show that DHA causes cell cycle arrest which is mediated through Forkhead box protein M1 (FOXM1). We also demonstrate that DHA induces ferroptosis and apoptosis in head and neck carcinoma cells. Lastly, our results show that DHA alters the angiogenic phenotype of cancer cells by reducing the expression of angiogenic factors and the ability of cancer cells to support endothelial cell tubule formation. Our study suggests that DHA specifically causes head and neck cancer cell death through contribution from both ferroptosis and apoptosis. DHA may represent an effective strategy in head and neck cancer treatment.

  8. Global analysis of cell cycle gene expression of the legume symbiont Sinorhizobium meliloti.

    PubMed

    De Nisco, Nicole J; Abo, Ryan P; Wu, C Max; Penterman, Jon; Walker, Graham C

    2014-03-04

    In α-proteobacteria, strict regulation of cell cycle progression is necessary for the specific cellular differentiation required for adaptation to diverse environmental niches. The symbiotic lifestyle of Sinorhizobium meliloti requires a drastic cellular differentiation that includes genome amplification. To achieve polyploidy, the S. meliloti cell cycle program must be altered to uncouple DNA replication from cell division. In the α-proteobacterium Caulobacter crescentus, cell cycle-regulated transcription plays an important role in the control of cell cycle progression but this has not been demonstrated in other α-proteobacteria. Here we describe a robust method for synchronizing cell growth that enabled global analysis of S. meliloti cell cycle-regulated gene expression. This analysis identified 462 genes with cell cycle-regulated transcripts, including several key cell cycle regulators, and genes involved in motility, attachment, and cell division. Only 28% of the 462 S. meliloti cell cycle-regulated genes were also transcriptionally cell cycle-regulated in C. crescentus. Furthermore, CtrA- and DnaA-binding motif analysis revealed little overlap between the cell cycle-dependent regulons of CtrA and DnaA in S. meliloti and C. crescentus. The predicted S. meliloti cell cycle regulon of CtrA, but not that of DnaA, was strongly conserved in more closely related α-proteobacteria with similar ecological niches as S. meliloti, suggesting that the CtrA cell cycle regulatory network may control functions of central importance to the specific lifestyles of α-proteobacteria.

  9. Effect of sesamin on apoptosis and cell cycle arrest in human breast cancer mcf-7 cells.

    PubMed

    Siao, An-Ci; Hou, Chien-Wei; Kao, Yung-Hsi; Jeng, Kee-Ching

    2015-01-01

    Dietary prevention has been known to reduce breast cancer risk. Sesamin is one of the major components in sesame seeds and has been widely studied and proven to have anti-proliferation and anti-angiogenic effects on cancer cells. In this study, the influence of sesamin was tested in the human breast cancer MCF-7 cell line for cell viability (MTT assay) and cell cycling (flow cytometry). Results showed that sesamin dose-dependently (1, 10 and 50 μM) reduced the cell viability and increased LDH release and apoptosis (TUNEL assay). In addition, there was a significant increase of sub-G1 phase arrest in the cell cycle after sesamin treatment. Furthermore, sesamin increased the expression of apoptotic markers of Bax, caspase-3, and cell cycle control proteins, p53 and checkpoint kinase 2. Taken together, these results suggested that sesamin might be used as a dietary supplement for prevention of breast cancer by modulating apoptotic signal pathways and inhibiting tumor cell growth.

  10. Single-cell analysis of transcription kinetics across the cell cycle.

    PubMed

    Skinner, Samuel O; Xu, Heng; Nagarkar-Jaiswal, Sonal; Freire, Pablo R; Zwaka, Thomas P; Golding, Ido

    2016-01-29

    Transcription is a highly stochastic process. To infer transcription kinetics for a gene-of-interest, researchers commonly compare the distribution of mRNA copy-number to the prediction of a theoretical model. However, the reliability of this procedure is limited because the measured mRNA numbers represent integration over the mRNA lifetime, contribution from multiple gene copies, and mixing of cells from different cell-cycle phases. We address these limitations by simultaneously quantifying nascent and mature mRNA in individual cells, and incorporating cell-cycle effects in the analysis of mRNA statistics. We demonstrate our approach on Oct4 and Nanog in mouse embryonic stem cells. Both genes follow similar two-state kinetics. However, Nanog exhibits slower ON/OFF switching, resulting in increased cell-to-cell variability in mRNA levels. Early in the cell cycle, the two copies of each gene exhibit independent activity. After gene replication, the probability of each gene copy to be active diminishes, resulting in dosage compensation.

  11. Glucose-ABL1-TOR Signaling Modulates Cell Cycle Tuning to Control Terminal Appressorial Cell Differentiation

    PubMed Central

    2017-01-01

    The conserved target of rapamycin (TOR) pathway integrates growth and development with available nutrients, but how cellular glucose controls TOR function and signaling is poorly understood. Here, we provide functional evidence from the devastating rice blast fungus Magnaporthe oryzae that glucose can mediate TOR activity via the product of a novel carbon-responsive gene, ABL1, in order to tune cell cycle progression during infection-related development. Under nutrient-free conditions, wild type (WT) M. oryzae strains form terminal plant-infecting cells (appressoria) at the tips of germ tubes emerging from three-celled spores (conidia). WT appressorial development is accompanied by one round of mitosis followed by autophagic cell death of the conidium. In contrast, Δabl1 mutant strains undergo multiple rounds of accelerated mitosis in elongated germ tubes, produce few appressoria, and are abolished for autophagy. Treating WT spores with glucose or 2-deoxyglucose phenocopied Δabl1. Inactivating TOR in Δabl1 mutants or glucose-treated WT strains restored appressorium formation by promoting mitotic arrest at G1/G0 via an appressorium- and autophagy-inducing cell cycle delay at G2/M. Collectively, this work uncovers a novel glucose-ABL1-TOR signaling axis and shows it engages two metabolic checkpoints in order to modulate cell cycle tuning and mediate terminal appressorial cell differentiation. We thus provide new molecular insights into TOR regulation and cell development in response to glucose. PMID:28072818

  12. Identifying and removing the cell-cycle effect from single-cell RNA-Sequencing data

    PubMed Central

    Barron, Martin; Li, Jun

    2016-01-01

    Single-cell RNA-Sequencing (scRNA-Seq) is a revolutionary technique for discovering and describing cell types in heterogeneous tissues, yet its measurement of expression often suffers from large systematic bias. A major source of this bias is the cell cycle, which introduces large within-cell-type heterogeneity that can obscure the differences in expression between cell types. The current method for removing the cell-cycle effect is unable to effectively identify this effect and has a high risk of removing other biological components of interest, compromising downstream analysis. We present ccRemover, a new method that reliably identifies the cell-cycle effect and removes it. ccRemover preserves other biological signals of interest in the data and thus can serve as an important pre-processing step for many scRNA-Seq data analyses. The effectiveness of ccRemover is demonstrated using simulation data and three real scRNA-Seq datasets, where it boosts the performance of existing clustering algorithms in distinguishing between cell types. PMID:27670849

  13. Single-cell analysis of transcription kinetics across the cell cycle

    PubMed Central

    Skinner, Samuel O; Xu, Heng; Nagarkar-Jaiswal, Sonal; Freire, Pablo R; Zwaka, Thomas P; Golding, Ido

    2016-01-01

    Transcription is a highly stochastic process. To infer transcription kinetics for a gene-of-interest, researchers commonly compare the distribution of mRNA copy-number to the prediction of a theoretical model. However, the reliability of this procedure is limited because the measured mRNA numbers represent integration over the mRNA lifetime, contribution from multiple gene copies, and mixing of cells from different cell-cycle phases. We address these limitations by simultaneously quantifying nascent and mature mRNA in individual cells, and incorporating cell-cycle effects in the analysis of mRNA statistics. We demonstrate our approach on Oct4 and Nanog in mouse embryonic stem cells. Both genes follow similar two-state kinetics. However, Nanog exhibits slower ON/OFF switching, resulting in increased cell-to-cell variability in mRNA levels. Early in the cell cycle, the two copies of each gene exhibit independent activity. After gene replication, the probability of each gene copy to be active diminishes, resulting in dosage compensation. DOI: http://dx.doi.org/10.7554/eLife.12175.001 PMID:26824388

  14. Glucose-ABL1-TOR Signaling Modulates Cell Cycle Tuning to Control Terminal Appressorial Cell Differentiation.

    PubMed

    Marroquin-Guzman, Margarita; Sun, Guangchao; Wilson, Richard A

    2017-01-01

    The conserved target of rapamycin (TOR) pathway integrates growth and development with available nutrients, but how cellular glucose controls TOR function and signaling is poorly understood. Here, we provide functional evidence from the devastating rice blast fungus Magnaporthe oryzae that glucose can mediate TOR activity via the product of a novel carbon-responsive gene, ABL1, in order to tune cell cycle progression during infection-related development. Under nutrient-free conditions, wild type (WT) M. oryzae strains form terminal plant-infecting cells (appressoria) at the tips of germ tubes emerging from three-celled spores (conidia). WT appressorial development is accompanied by one round of mitosis followed by autophagic cell death of the conidium. In contrast, Δabl1 mutant strains undergo multiple rounds of accelerated mitosis in elongated germ tubes, produce few appressoria, and are abolished for autophagy. Treating WT spores with glucose or 2-deoxyglucose phenocopied Δabl1. Inactivating TOR in Δabl1 mutants or glucose-treated WT strains restored appressorium formation by promoting mitotic arrest at G1/G0 via an appressorium- and autophagy-inducing cell cycle delay at G2/M. Collectively, this work uncovers a novel glucose-ABL1-TOR signaling axis and shows it engages two metabolic checkpoints in order to modulate cell cycle tuning and mediate terminal appressorial cell differentiation. We thus provide new molecular insights into TOR regulation and cell development in response to glucose.

  15. Effect of hormonal manipulation and doxorubicin administration on cell cycle kinetics of human breast cancer cells.

    PubMed Central

    Bontenbal, M.; Sieuwerts, A. M.; Klijn, J. G.; Peters, H. A.; Krijnen, H. L.; Sonneveld, P.; Foekens, J. A.

    1989-01-01

    Dual-parameter flow cytometry, following bromodeoxyuridine (BrdUrd) incorporation and propidium iodide (PI) uptake into DNA, was used to study the effects of oestradiol and/or insulin on cell cycle kinetics of human breast cancer cells in vitro. After a lag-period of 6-12 h, an optimum in the percentage of S-phase cells was reached between 18 and 24 h after hormone administration. A 1 h pulse of oestradiol was as effective as the continuous presence of oestradiol in pushing the cells from quiescent growing cultures into the cell cycle. A 1 h pulse of insulin was less effective than continuous administration. The addition of doxorubicin resulted in an accumulation of the cells in the late S/G2M-phases. It is concluded that dual-parameter flow cytometry allows accurate assessment of the effects of hormones and chemotherapy on the cell cycle. Therefore this method is very suitable for studying the interaction of hormones and chemotherapy on cell growth. Images Figure 1 Figure 2 Figure 4 PMID:2679851

  16. Simvastatin induces cell cycle arrest and inhibits proliferation of bladder cancer cells via PPARγ signalling pathway

    PubMed Central

    Wang, Gang; Cao, Rui; Wang, Yongzhi; Qian, Guofeng; Dan, Han C.; Jiang, Wei; Ju, Lingao; Wu, Min; Xiao, Yu; Wang, Xinghuan

    2016-01-01

    Simvastatin is currently one of the most common drugs for old patients with hyperlipidemia, hypercholesterolemia and atherosclerotic diseases by reducing cholesterol level and anti-lipid properties. Importantly, simvastatin has also been reported to have anti-tumor effect, but the underlying mechanism is largely unknown. We collected several human bladder samples and performed microarray. Data analysis suggested bladder cancer (BCa) was significantly associated with fatty acid/lipid metabolism via PPAR signalling pathway. We observed simvastatin did not trigger BCa cell apoptosis, but reduced cell proliferation in a dose- and time-dependent manner, accompanied by PPARγ-activation. Moreover, flow cytometry analysis indicated that simvastatin induced cell cycle arrest at G0/G1 phase, suggested by downregulation of CDK4/6 and Cyclin D1. Furthermore, simvastatin suppressed BCa cell metastasis by inhibiting EMT and affecting AKT/GSK3β. More importantly, we found that the cell cycle arrest at G0/G1 phase and the alterations of CDK4/6 and Cyclin D1 triggered by simvastatin could be recovered by PPARγ-antagonist (GW9662), whereas the treatment of PPARα-antagonist (GW6471) shown no significant effects on the BCa cells. Taken together, our study for the first time revealed that simvastatin inhibited bladder cancer cell proliferation and induced cell cycle arrest at G1/G0 phase via PPARγ signalling pathway. PMID:27779188

  17. The Integrins Involved in Soybean Agglutinin-Induced Cell Cycle Alterations in IPEC-J2

    PubMed Central

    Pan, Li; Zhao, Yuan; Yuan, Zhijie; Farouk, Mohammed Hamdy; Zhang, Shiyao; Bao, Nan; Qin, Guixin

    2017-01-01

    Soybean agglutinin (SBA) is an anti-nutritional factor of soybean, affecting cell proliferation and inducing cytotoxicity. Integrins are transmembrane receptors, mediating a variety of cell biological processes. This research aims to study the effects of SBA on cell proliferation and cell cycle progression of the intestinal epithelial cell line from piglets (IPEC-J2), to identify the integrin subunits especially expressed in IPEC-J2s, and to analyze the functions of these integrins on IPEC-J2 cell cycle progression and SBA-induced IPEC-J2 cell cycle alteration. The results showed that SBA lowered cell proliferation rate as the cell cycle progression from G0/G1 to S phase (P < 0.05) was inhibited. Moreover, SBA lowered mRNA expression of cell cycle-related gene CDK4, Cyclin E and Cyclin D1 (P < 0.05). We successfully identified integrins α2, α3, α6, β1, and β4 in IPEC-J2s. These five subunits were crucial to maintain normal cell proliferation and cell cycle progression in IPEC-J2s. Restrain of either these five subunits by their inhibitors, lowered cell proliferation rate, and arrested the cells at G0/G1 phase of cell cycle (P < 0.05). Further analysis indicated that integrin α2, α6, and β1 were involved in the blocking of G0/G1 phase induced by SBA. In conclusion, these results suggested that SBA lowered the IPEC-J2 cell proliferation rate through the perturbation of cell cycle progression. Furthermore, integrins were important for IPEC-J2 cell cycle progression, and they were involved in the process of SBA-induced cell cycle progression alteration, which provide a basis for further revealing SBA anti-proliferation and anti-nutritional mechanism. PMID:28222496

  18. Differences in CART expression and cell cycle behavior discriminate sympathetic neuroblast from chromaffin cell lineages in mouse sympathoadrenal cells.

    PubMed

    Chan, Wing Hei; Gonsalvez, David G; Young, Heather M; Southard-Smith, E Michelle; Cane, Kylie N; Anderson, Colin R

    2016-02-01

    Adrenal medullary chromaffin cells and peripheral sympathetic neurons originate from a common sympathoadrenal (SA) progenitor cell. The timing and phenotypic changes that mark this lineage diversification are not fully understood. The present study investigated the expression patterns of phenotypic markers, and cell cycle dynamics, in the adrenal medulla and the neighboring suprarenal ganglion of embryonic mice. The noradrenergic marker, tyrosine hydroxylase (TH), was detected in both presumptive adrenal medulla and sympathetic ganglion cells, but with significantly stronger immunostaining in the former. There was intense cocaine and amphetamine-regulated transcript (CART) peptide immunostaining in most neuroblasts, whereas very few adrenal chromaffin cells showed detectable CART immunostaining. This phenotypic segregation appeared as early as E12.5, before anatomical segregation of the two cell types. Cell cycle dynamics were also examined. Initially, 88% of Sox10 positive (+) neural crest progenitors were proliferating at E10.5. Many SA progenitor cells withdrew from the cell cycle at E11.5 as they started to express TH. Whereas 70% of neuroblasts (TH+/CART+ cells) were back in the cell cycle at E12.5, only around 20% of chromaffin (CART negative) cells were in the cell cycle at E12.5 and subsequent days. Thus, chromaffin cell and neuroblast lineages showed differences in proliferative behavior from their earliest appearance. We conclude that the intensity of TH immunostaining and the expression of CART permit early discrimination of chromaffin cells and sympathetic neuroblasts, and that developing chromaffin cells exhibit significantly lower proliferative activity relative to sympathetic neuroblasts.

  19. Quantitation of alpha-factor internalization and response during the Saccharomyces cerevisiae cell cycle.

    PubMed Central

    Zanolari, B; Riezman, H

    1991-01-01

    The alpha-factor pheromone binds to specific cell surface receptors on Saccharomyces cerevisiae a cells. The pheromone is then internalized, and cell surface receptors are down-regulated. At the same time, a signal is transmitted that causes changes in gene expression and cell cycle arrest. We show that the ability of cells to internalize alpha-factor is constant throughout the cell cycle, a cells are also able to respond to pheromone throughout the cycle even though there is cell cycle modulation of the expression of two pheromone-inducible genes, FUS1 and STE2. Both of these genes are expressed less efficiently near or just after the START point of the cell cycle in response to alpha-factor. For STE2, the basal level of expression is modulated in the same manner. Images PMID:1656226

  20. Impaired cell cycle regulation of osteoblast-related transcription factor Runx2/Cbfa1 in osteosarcoma cells

    PubMed Central

    San Martin, Inga; Varela, Nelson; Gaete, Marcia; Villegas, Karina; Osorio, Mariana; Tapia, Julio C.; Antonelli, Marcelo; Mancilla, Edna; Lian, Jane B.; Stein, Janet L.; Stein, Gary S; van Wijnen, Andre J.; Galindo, Mario

    2011-01-01

    In mammals, bone differentiation requires the functional expression of the Runx2/Cbfβ heterodimeric complex. Our previous results indicate that Runx2 is also a suppressor of pre-osteoblast proliferation by affecting cell cycle progression at G1. Runx2 levels are cell cycle regulated, oscillating from a maximum during early G1 to a minimum during late G1, S and mitosis phases in proliferating pre-osteoblasts Nevertheless, there is no information concerning Cbfβ gene expression during the cell cycle nor on Runx2 cell cycle expression in bone cancer cells. We analyzed Runx2 and Cbfβ gene expression during cell cycle progression in the pre-osteoblast MC3T3 and osteosarcoma ROS and SaOS cell lines. The expected reduction of Runx2 protein level was observed in MC3T3 cells arrested in late G1 or M phase using mimosine or nocodazole, respectively. However, this reduction was not observed in the cell cycle arrested osteosarcoma cells. Cbfβ protein levels were not regulated during the cell cycle in pre-osteoblasts and osteosarcoma cells. Using cells synchronized in late G1 and mitosis we found that Runx2 levels, but not Cbfβ levels, were cell cycle regulated in MC3T3 osteoblasts. Interestingly, both factors showed a constitutively elevated expression throughout the cell cycle in osteosarcoma cells. Proteasome inhibition by MG132 prevented cell cycle-dependent downregulation of Runx2 protein levels in osteoblasts, but not in osteosarcoma. We propose that Runx2 is involved in tumoral osteosarcoma progression. Altogether, deregulated Runx2 expression throughout the cell cycle seems to constitute a central mechanism in the pathogenesis of osteosarcoma. PMID:19739101

  1. Position in cell cycle controls the sensitivity of colon cancer cells to nitric oxide-dependent programmed cell death.

    PubMed

    Jarry, Anne; Charrier, Laetitia; Bou-Hanna, Chantal; Devilder, Marie-Claire; Crussaire, Véronique; Denis, Marc G; Vallette, Geneviève; Laboisse, Christian L

    2004-06-15

    Mounting evidence suggests that the position in the cell cycle of cells exposed to an oxidative stress could determine their survival or apoptotic cell death. This study aimed at determining whether nitric oxide (NO)-induced cell death in colon cancer cells might depend on their position in the cell cycle, based on a clone of the cancer cell line HT29 exposed to an NO donor, in combination with the manipulation of the cell entry into the cell cycle. We show that PAPA NONOate (pNO), from 10(-4) m to 10(-3) m, exerted early and reversible cytostatic effects through ribonucleotide reductase inhibition, followed by late resumption of cell growth at 5 x 10(-4) m pNO. In contrast, 10(-3) m pNO led to late programmed cell death that was accounted for by the progression of cells into the cell cycle as shown by (a) the accumulation of apoptotic cells in the G(2)-M phase at 10(-3) m pNO treatment; and (b) the prevention of cell death by inhibiting the entry of cells into the cell cycle. The entry of pNO-treated cells into the G(2)-M phase was associated with actin depolymerization and its S-glutathionylation in the same way as in control cells. However, the pNO treatment interfered with the build-up of a high reducing power, associated in control cells with a dramatic increase in reduced glutathione biosynthesis in the G(2)-M phase. This oxidative stress prevented the exit from the G(2)-M phase, which requires a high reducing power for actin deglutathionylation and its repolymerization. Finally, our demonstration that programmed cell death occurred through a caspase-independent pathway is in line with the context of a nitrosative/oxidative stress. In conclusion, this work, which deciphers the connection between the position of colonic cancer cells in the cell cycle and their sensitivity to NO-induced stress and their programmed cell death, could help optimize anticancer protocols based on NO-donating compounds.

  2. Quantitative Proteomic Analysis of Cell Cycle of the Dinoflagellate Prorocentrum donghaiense (Dinophyceae)

    PubMed Central

    Wang, Da-Zhi; Zhang, Ying-Jiao; Zhang, Shu-Fei; Lin, Lin; Hong, Hua-Sheng

    2013-01-01

    Dinoflagellates are the major causative agents of harmful algal blooms in the coastal zone, which has resulted in adverse effects on the marine ecosystem and public health, and has become a global concern. Knowledge of cell cycle regulation in proliferating cells is essential for understanding bloom dynamics, and so this study compared the protein profiles of Prorocentrum donghaiense at different cell cycle phases and identified differentially expressed proteins using 2-D fluorescence difference gel electrophoresis combined with MALDI-TOF-TOF mass spectrometry. The results showed that the synchronized cells of P. donghaiense completed a cell cycle within 24 hours and cell division was phased with the diurnal cycle. Comparison of the protein profiles at four cell cycle phases (G1, S, early and late G2/M) showed that 53 protein spots altered significantly in abundance. Among them, 41 were identified to be involved in a variety of biological processes, e.g. cell cycle and division, RNA metabolism, protein and amino acid metabolism, energy and carbon metabolism, oxidation-reduction processes, and ABC transport. The periodic expression of these proteins was critical to maintain the proper order and function of the cell cycle. This study, to our knowledge, for the first time revealed the major biological processes occurring at different cell cycle phases which provided new insights into the mechanisms regulating the cell cycle and growth of dinoflagellates. PMID:23691081

  3. Abnormal mitosis triggers p53-dependent cell cycle arrest in human tetraploid cells.

    PubMed

    Kuffer, Christian; Kuznetsova, Anastasia Yurievna; Storchová, Zuzana

    2013-08-01

    Erroneously arising tetraploid mammalian cells are chromosomally instable and may facilitate cell transformation. An increasing body of evidence shows that the propagation of mammalian tetraploid cells is limited by a p53-dependent arrest. The trigger of this arrest has not been identified so far. Here we show by live cell imaging of tetraploid cells generated by an induced cytokinesis failure that most tetraploids arrest and die in a p53-dependent manner after the first tetraploid mitosis. Furthermore, we found that the main trigger is a mitotic defect, in particular, chromosome missegregation during bipolar mitosis or spindle multipolarity. Both a transient multipolar spindle followed by efficient clustering in anaphase as well as a multipolar spindle followed by multipolar mitosis inhibited subsequent proliferation to a similar degree. We found that the tetraploid cells did not accumulate double-strand breaks that could cause the cell cycle arrest after tetraploid mitosis. In contrast, tetraploid cells showed increased levels of oxidative DNA damage coinciding with the p53 activation. To further elucidate the pathways involved in the proliferation control of tetraploid cells, we knocked down specific kinases that had been previously linked to the cell cycle arrest and p53 phosphorylation. Our results suggest that the checkpoint kinase ATM phosphorylates p53 in tetraploid cells after abnormal mitosis and thus contributes to proliferation control of human aberrantly arising tetraploids.

  4. Laser phase microscopy and functional imaging of living human cancer cells during the cell cycle

    NASA Astrophysics Data System (ADS)

    Perevedentseva, Elena V.; Graschew, Georgi; Balanos, Evangelos; Dressler, Cathrin; Beuthan, Juergen; Schlag, Peter M.

    2000-05-01

    The purpose of the investigation was to elaborate a new method of functional imaging of living tumor cells. Human colon carcinoma cells HCT116 were investigated with a conventional light microscope, confocal laser scanning microscope and with a laser phase microscope (LPM). The LPM is a functional imaging technique providing information about cell morphology which is imposed by the physiological inhomogeneity of the refractive index. The phase of the light wave passing through an object contains quantitative information about the object thickness, the shape, and the spatial distribution of the refractive index varying with morphology and chemical composition inhomogeneity inside the object. The new method of investigation of the cells in different stages of the cell cycle is developed. Every phase image of the investigated cells has been compared with conventional light microscopic and confocal microscopic images of the same cell. the relation between the cell state, their morphological peculiarities and the phase characteristics of the measured cell is determined. Data thus acquired, quantitatively characterizing intra- and intercellular processes during the cell cycle, and the method of measurements can be used to investigate with high optic resolution the mechanisms of different physical, chemical and biomolecular interactions with the tumor cells.

  5. The DOF transcription factor OBP1 is involved in cell cycle regulation in Arabidopsis thaliana.

    PubMed

    Skirycz, Aleksandra; Radziejwoski, Amandine; Busch, Wolfgang; Hannah, Matthew A; Czeszejko, Joanna; Kwaśniewski, Mirosław; Zanor, Maria-Inès; Lohmann, Jan U; De Veylder, Lieven; Witt, Isabell; Mueller-Roeber, Bernd

    2008-12-01

    In contrast to animal growth, plant growth is largely post-embryonic. Therefore plants have developed new mechanisms to precisely regulate cell proliferation by means of internal and external stimuli whilst the general core cell cycle machinery is conserved between eukaryotes. In this work we demonstrate a role for the Arabidopsis thaliana DNA-binding-with-one-finger (DOF) transcription factor OBP1 in the control of cell division upon developmental signalling. Inducible overexpression of OBP1 resulted in a significant overrepresentation of cell cycle genes among the upregulated transcripts. Direct targets of OBP1, as verified by chromatin immunoprecipitation, include at least the core cell cycle gene CYCD3;3 and the replication-specific transcription factor gene AtDOF2;3. Consistent with our molecular data, short-term activation of OBP1 in cell cultures affected cell cycle re-entry, shortening the duration of the G(1) phase and the overall length of the cell cycle, whilst constitutive overexpression of OBP1 in plants influenced cell size and cell number, leading to a dwarfish phenotype. Expression during embryogenesis, germination and lateral root initiation suggests an important role for OBP1 in cell cycle re-entry, operating as a transcriptional regulator of key cell cycle genes. Our findings provide significant input into our understanding of how cell cycle activity is incorporated into plant growth and development.

  6. Chloroplast dysfunction causes multiple defects in cell cycle progression in the Arabidopsis crumpled leaf mutant.

    PubMed

    Hudik, Elodie; Yoshioka, Yasushi; Domenichini, Séverine; Bourge, Mickaël; Soubigout-Taconnat, Ludivine; Mazubert, Christelle; Yi, Dalong; Bujaldon, Sandrine; Hayashi, Hiroyuki; De Veylder, Lieven; Bergounioux, Catherine; Benhamed, Moussa; Raynaud, Cécile

    2014-09-01

    The majority of research on cell cycle regulation is focused on the nuclear events that govern the replication and segregation of the genome between the two daughter cells. However, eukaryotic cells contain several compartmentalized organelles with specialized functions, and coordination among these organelles is required for proper cell cycle progression, as evidenced by the isolation of several mutants in which both organelle function and overall plant development were affected. To investigate how chloroplast dysfunction affects the cell cycle, we analyzed the crumpled leaf (crl) mutant of Arabidopsis (Arabidopsis thaliana), which is deficient for a chloroplastic protein and displays particularly severe developmental defects. In the crl mutant, we reveal that cell cycle regulation is altered drastically and that meristematic cells prematurely enter differentiation, leading to reduced plant stature and early endoreduplication in the leaves. This response is due to the repression of several key cell cycle regulators as well as constitutive activation of stress-response genes, among them the cell cycle inhibitor SIAMESE-RELATED5. One unique feature of the crl mutant is that it produces aplastidic cells in several organs, including the root tip. By investigating the consequence of the absence of plastids on cell cycle progression, we showed that nuclear DNA replication occurs in aplastidic cells in the root tip, which opens future research prospects regarding the dialogue between plastids and the nucleus during cell cycle regulation in higher plants.

  7. Proteolytic enzyme levels are increased during granulocyte colony-stimulating factor-induced hematopoietic stem cell mobilization in human donors but do not predict the number of mobilized stem cells.

    PubMed

    van Os, R; van Schie, M L J; Willemze, R; Fibbe, W E

    2002-06-01

    Previous studies from our laboratory indicate that functional, mature neutrophils are essential for interleukin-8 (IL-8)-induced stem cell mobilization. To study a possible role of neutrophils in granulocyte colony-stimulating factor (G-CSF) induced hematopoietic mobilization, we assessed the number of circulating CD34+ cells in healthy allogeneic stem cell donors on days 3, 4, and 5 of mobilization for comparison with the number of peripheral blood neutrophils and the plasma levels of IL-8, Flt3 ligand (FL), matrix metalloproteinase-9 (MMP-9), and human neutrophil elastase (HNE). Thirty-seven of 45 donors required 1 day of apheresis to obtain 5 x 10(6) CD34+/kg recipient body weight (high responders), the remaining 8 donors required 1 extra day of apheresis on day 6 (low responders). On day 5, CD34+ numbers in the blood were significantly highe in high responders (116 x 10(3) +/- 10.4/ml) than in low responders (54.1 x 10(3) +/- 10.3, p < 0.001). In all donors, MMP-9 and HNE levels were increased compared to nonmobilized individuals, but in high responders, plasma MMP-9 levels on days 3-5 of mobilization were substantially higher than in low responders (p < or = 0.02 for MMP-9 and p = 0.89, p = 0.05 and p = 0.52 for HNE on days 3, 4, and 5, respectively). These results are in accordance with the hypothesis that neutrophils play a role in G-CSF-induced mobilization through the release of proteases such as MMP-9 and elastase. No change in plasma levels of IL-8 or Flt3 ligand was observed, suggesting that these cytokines do not play a role in stem cell mobilization. However, because stem cell numbers could not be predicted by proteolytic enzyme levels and/or neutrophil numbers, other undefined factors may be more important.

  8. Propionibacterium acnes inhibits FOXM1 and induces cell cycle alterations in human primary prostate cells.

    PubMed

    Sayanjali, Behnam; Christensen, Gitte J M; Al-Zeer, Munir A; Mollenkopf, Hans-Joachim; Meyer, Thomas F; Brüggemann, Holger

    2016-11-01

    Propionibacterium acnes has been detected in diseased human prostate tissue, and cell culture experiments suggest that the bacterium can establish a low-grade inflammation. Here, we investigated its impact on human primary prostate epithelial cells. Microarray analysis confirmed the inflammation-inducing capability of P. acnes but also showed deregulation of genes involved in the cell cycle. qPCR experiments showed that viable P. acnes downregulates a master regulator of cell cycle progression, FOXM1. Flow cytometry experiments revealed that P. acnes increases the number of cells in S-phase. We tested the hypothesis that a P. acnes-produced berninamycin-like thiopeptide is responsible for this effect, since it is related to the FOXM1 inhibitor siomycin. The thiopeptide biosynthesis gene cluster was strongly expressed; it is present in subtype IB of P. acnes, but absent from type IA, which is most abundant on human skin. A knock-out mutant lacking the gene encoding the berninamycin-like peptide precursor was unable to downregulate FOXM1 and to halt the cell cycle. Our study reveals a novel host cell-interacting activity of P. acnes.

  9. Expected cycle life versus depth of discharge relationships of well behaved single cells and cell strings

    NASA Technical Reports Server (NTRS)

    Thaller, L. H.

    1982-01-01

    The factors that might influence the cycle life vs. depth of discharge relationship are examined. This is done first at the single cell level using a progressively more complex cell life model. This is then extended to multicell battery strings where the stochastic aspects associated with groupings of cells are introduced. These relationships are important when considering the weight, cost, and life of battery packs. The results of this theoretical study are compared with a recent review of actual cell cycling data. The factors examined are the rate of capacity loss, the amount of excess capacity built into the cells, and the penalty in capacity loss resulting from the use of deep depths of discharge. This study suggests that the relationship between cycle life and depth of discharge is not one that can be varied of significantly improved by cell research. The relationship appears to be determined by certain more or less fixed cell parameters. Among multicell strings, the standard deviation, as expected, plays an important role in determining overall battery life.

  10. Heterochronic misexpression of Ascl1 in the Atoh7 retinal cell lineage blocks cell cycle exit.

    PubMed

    Hufnagel, Robert B; Riesenberg, Amy N; Quinn, Malgorzata; Brzezinski, Joseph A; Glaser, Tom; Brown, Nadean L

    2013-05-01

    Retinal neurons and glia arise from a common progenitor pool in a temporal order, with retinal ganglion cells (RGCs) appearing first, and Müller glia last. The transcription factors Atoh7/Math5 and Ascl1/Mash1 represent divergent bHLH clades, and exhibit distinct spatial and temporal retinal expression patterns, with little overlap during early development. Here, we tested the ability of Ascl1 to change the fate of cells in the Atoh7 lineage when misexpressed from the Atoh7 locus, using an Ascl1-IRES-DsRed2 knock-in allele. In Atoh7(Ascl1KI/+) and Atoh7(Ascl1KI/Ascl1KI) embryos, ectopic Ascl1 delayed cell cycle exit and differentiation, even in cells coexpressing Atoh7. The heterozygous retinas recovered, and eventually produced a normal complement of RGCs, while homozygous substitution of Ascl1 for Atoh7 did not promote postnatal retinal fates precociously, nor rescue Atoh7 mutant phenotypes. However, our analyses revealed two unexpected findings. First, ectopic Ascl1 disrupted cell cycle progression within the marked Atoh7 lineage, but also nonautonomously in other retinal cells. Second, the size of the Atoh7 retinal lineage was unaffected, supporting the idea of a compensatory shift of the non-proliferative cohort to maintain lineage size. Overall, we conclude that Ascl1 acts dominantly to block cell cycle exit, but is incapable of redirecting the fates of early RPCs.

  11. Videomicrofluorometry on living cells and discriminant factorial analysis to study cell cycle distributions.

    PubMed

    Savatier, J; Gbankoto, A; Vigo, J; Salmon, J M

    2004-01-01

    After a rapid overview of the approaches used to study cell cycle, a fluorescent digital imaging microscopy method is proposed. This method is improved by a factorial analysis relying on the evaluation of several parameters recorded on each living cell. Single lympho-blastoid living cells are labeled with three fluorescent markers: Hoechst 33342 for nuclear DNA, Rhodamine 123 for mitochondria and Nile Red for plasma membrane. For each cell, morphological and functional information parameters are obtained. A typological analysis is used to separate control cells into four groups: G0-G1, S, G2+M and polyploid cells Gn. These control cells define a learning population used to analyze untreated and adriamycine treated cells as supplementary individuals in a discriminant factorial analysis. Such an approach allows to accurately evidence the change of the values of some cellular parameters.

  12. Coordinating cell proliferation and differentiation: Antagonism between cell cycle regulators and cell type-specific gene expression

    PubMed Central

    Ruijtenberg, Suzan; van den Heuvel, Sander

    2016-01-01

    ABSTRACT Cell proliferation and differentiation show a remarkable inverse relationship. Precursor cells continue division before acquiring a fully differentiated state, while terminal differentiation usually coincides with proliferation arrest and permanent exit from the division cycle. Mechanistic insight in the temporal coordination between cell cycle exit and differentiation has come from studies of cells in culture and genetic animal models. As initially described for skeletal muscle differentiation, temporal coordination involves mutual antagonism between cyclin-dependent kinases that promote cell cycle entry and transcription factors that induce tissue-specific gene expression. Recent insights highlight the contribution of chromatin-regulating complexes that act in conjunction with the transcription factors and determine their activity. In particular SWI/SNF chromatin remodelers contribute to dual regulation of cell cycle and tissue-specific gene expression during terminal differentiation. We review the concerted regulation of the cell cycle and cell type-specific transcription, and discuss common mutations in human cancer that emphasize the clinical importance of proliferation versus differentiation control. PMID:26825227

  13. Influence of lycopene on cell viability, cell cycle, and apoptosis of human prostate cancer and benign hyperplastic cells.

    PubMed

    Soares, Nathalia da Costa Pereira; Teodoro, Anderson Junger; Oliveira, Felipe Leite; Santos, Carlos Antonio do Nascimento; Takiya, Christina Maeda; Junior, Oswaldo Saback; Bianco, Mario; Junior, Antonio Palumbo; Nasciutti, Luiz Eurico; Ferreira, Luciana Bueno; Gimba, Etel Rodrigues Pereira; Borojevic, Radovan

    2013-01-01

    Prostate cancer is the most common malignancy in men and the second leading cause of cancer-related mortality in men of the Western world. Lycopene has received attention because of its expcted potential to prevent cancer. In the present study, we evaluated the influence of lycopene on cell viability, cell cycle, and apoptosis of human prostate cancer cells and benign prostate hyperplastic cells. Using MTT assay, we observed a decrease of cell viability in all cancer cell lines after treatment with lycopene, which decreased the percentage of cells in G0/G1 phase and increased in S and G2/M phases after 96 h of treatment in metastatic prostate cancer cell lineages. Flow citometry analysis of cell cycle revealed lycopene promoted cell cycle arrest in G0/G1 phase after 48 and 96 h of treatment in a primary cancer cell line. Using real time PCR assay, lycopene also induced apoptosis in prostate cancer cells with altered gene expression of Bax and Bcl-2. No effect was observed in benign prostate hyperplasia cells. These results suggest an effect of lycopene on activity of human prostate cancer cells.

  14. Mps1 is SUMO-modified during the cell cycle

    PubMed Central

    Chen, Changyan; Lu, Lou; Dai, Wei

    2016-01-01

    Mps1 is a dual specificity protein kinase that regulates the spindle assembly checkpoint and mediates proper microtubule attachment to chromosomes during mitosis. However, the molecular mechanism that controls Mps1 protein level and its activity during the cell cycle remains unclear. Given that sumoylation plays an important role in mitotic progression, we investigated whether Mps1 was SUMO-modified and whether sumoylation affects its activity in mitosis. Our results showed that Mps1 was sumoylated in both asynchronized and mitotic cell populations. Mps1 was modified by both SUMO-1 and SUMO-2. Our further studies revealed that lysine residues including K71, K287, K367 and K471 were essential for Mps1 sumoylation. Sumoylation appeared to play a role in mediating kinetochore localization of Mps1, thus affecting normal mitotic progression. Furthermore, SUMO-resistant mutants of Mps1 interacted with BubR1 more efficiently than it did with the wild-type control. Combined, our results indicate that Mps1 is SUMO-modified that plays an essential role in regulating Mps1 functions during mitosis. PMID:26675261

  15. A Dynamic Gene Regulatory Network Model That Recovers the Cyclic Behavior of Arabidopsis thaliana Cell Cycle.

    PubMed

    Ortiz-Gutiérrez, Elizabeth; García-Cruz, Karla; Azpeitia, Eugenio; Castillo, Aaron; Sánchez, María de la Paz; Álvarez-Buylla, Elena R

    2015-09-01

    Cell cycle control is fundamental in eukaryotic development. Several modeling efforts have been used to integrate the complex network of interacting molecular components involved in cell cycle dynamics. In this paper, we aimed at recovering the regulatory logic upstream of previously known components of cell cycle control, with the aim of understanding the mechanisms underlying the emergence of the cyclic behavior of such components. We focus on Arabidopsis thaliana, but given that many components of cell cycle regulation are conserved among eukaryotes, when experimental data for this system was not available, we considered experimental results from yeast and animal systems. We are proposing a Boolean gene regulatory network (GRN) that converges into only one robust limit cycle attractor that closely resembles the cyclic behavior of the key cell-cycle molecular components and other regulators considered here. We validate the model by comparing our in silico configurations with data from loss- and gain-of-function mutants, where the endocyclic behavior also was recovered. Additionally, we approximate a continuous model and recovered the temporal periodic expression profiles of the cell-cycle molecular components involved, thus suggesting that the single limit cycle attractor recovered with the Boolean model is not an artifact of its discrete and synchronous nature, but rather an emergent consequence of the inherent characteristics of the regulatory logic proposed here. This dynamical model, hence provides a novel theoretical framework to address cell cycle regulation in plants, and it can also be used to propose novel predictions regarding cell cycle regulation in other eukaryotes.

  16. Thoc1 inhibits cell growth via induction of cell cycle arrest and apoptosis in lung cancer cells.

    PubMed

    Wan, Jianmei; Zou, Shitao; Hu, Mengshang; Zhu, Ran; Xu, Jiaying; Jiao, Yang; Fan, Saijun

    2014-06-01

    THO complex 1 (Thoc1) is a human nuclear matrix protein that binds to the retinoblastoma tumor suppressor retinoblastoma protein (pRb). While some studies suggest that Thoc1 has characteristics of a tumor suppressor protein, whether Thoc1 can inhibit lung cancer cell growth is not clear. In the present study, we observed that Thoc1 is lowly expressed in the lung cancer cell lines SPC-A1 and NCI-H1975. Then, we investigated the potential effects of Thoc1 on lung cancer cell proliferation, cell cycle and apoptosis after stable transfection of these lines with a Thoc1 expression vector. We found that overexpression of Thoc1 can inhibit cell proliferation, induce G2/M cell cycle arrest and promote apoptosis. Further investigation indicated that overexpression of Thoc1 is involved in the inhibition of cell cycle-related proteins cyclin A1 and B1 and of pro-apoptotic factors Bax and caspase-3. In vivo experiments showed that tumors overexpressing Thoc1 display a slower growth rate than the control xenografts and show reduced expression of the protein Ki-67, which localized on the nuclear membrane. Taken together, our data show that in lung cancer cells, Thoc1 inhibits cell growth through induction of cell cycle arrest and apoptosis. These results indicate that Thoc1 may be used as a novel therapeutic target for human lung cancer treatment.

  17. Rhizoma Paridis Saponins Induces Cell Cycle Arrest and Apoptosis in Non-Small Cell Lung Carcinoma A549 Cells

    PubMed Central

    Zhang, Jue; Yang, Yixi; Lei, Lei; Tian, Mengliang

    2015-01-01

    Background As a traditional Chinese medicine herb, Chonglou (Paris polyphylla var. chinensis) has been used as anticancer medicine in China in recent decades, as it can induce cell cycle arrest and apoptosis in numerous cancer cells. The saponins extract from the rhizoma of Chonglou [Rhizoma Paridis saponins (RPS)] is known as the main active component for anticancer treatment. However, the molecular mechanism of the anticancer effect of RPS is unknown. Material/Methods The present study evaluated the effect of RPS in non-small-cell lung cancer (NSCLC) A549 cells using the 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry. Subsequently, the expression of several genes associated with cell cycle and apoptosis were detected by reverse transcription-quantitative polymerase chain reaction (qRT-PCR) and Western blotting. Results RPS was revealed to inhibit cell growth, causing a number of cells to accumulate in the G 1 phase of the cell cycle, leading to apoptosis. In addition, the effect was dose-dependent. Moreover, the results of qRT-PCR and Western blotting showed that p53 and cyclin-dependent kinase 2 (CDK2) were significantly downregulated, and that BCL2, BAX, and p21 were upregulated, by RPS treatment. Conclusions We speculated that the RPS could act on a pathway, including p53, p21, BCL2, BAX, and CDK2, and results in G1 cell cycle arrest and apoptosis in NSCLC cells. PMID:26311066

  18. Myc/Max/Mad regulate the frequency but not the duration of productive cell cycles

    PubMed Central

    Hölzel, Michael; Kohlhuber, Franz; Schlosser, Isabel; Hölzel, Dieter; Lüscher, Bernhard; Eick, Dirk

    2001-01-01

    Upregulation of the proto-oncoprotein Myc, a basic, helix–loop–helix, leucin zipper domain transcription factor has profound consequences on cell proliferation, cell growth and apoptosis. Cell cultures of somatic c-myc–/– rat fibroblasts show extremely prolonged doubling times of 52 h. Using time-lapse microscopy, we show here that individual c-myc–/– cells proceeded within ∼24 h through the cell cycle as fast as c-myc+/+ cells. However, c-myc–/– cells were highly sensitive to contact inhibition and readily arrested in the cell cycle already at low density. Activation of conditional MycER overcame cell cycle arrest in c-myc–/– cells and led to continuous proliferation at the expense of increased apoptosis at high cell density. Conditional expression of Mad1, a Myc antagonist, represses proliferation of different cell types including U2OS cells. In analogy to the effect of Myc, this occurs mainly by reducing the probability of cells remaining in the cycle. Our data demonstrate that the Myc/Max/Mad network does not regulate the duration of the cell cycle, but the decision of cells to enter or exit the cell cycle. PMID:11743027

  19. Test summary for advanced H2 cycle NI-CD cell

    NASA Technical Reports Server (NTRS)

    Miller, Lee

    1987-01-01

    To improve operational tolerances and mass, the H2 gas recombination design provisions of the Ni-H2 system were incorporated into the sealed Ni-Cd system. Produced is a cell design capable of operating on the H2 cycle versus the normal O2 cycle. Three test cells have now completed approximately 4,330 LEO (90 minute) cycles at 20 percent depth of discharge (DOD). Performance remains stable although one cell exhibited a temporary pressure anomaly.

  20. Methamphetamine is not Toxic but Disrupts the Cell Cycle of Blood-Brain Barrier Endothelial Cells.

    PubMed

    Fisher, D; Gamieldien, K; Mafunda, P S

    2015-07-01

    The cytotoxic effects of methamphetamine (MA) are well established to be caused via induced oxidative stress which in turn compromises the core function of the blood-brain barrier (BBB) by reducing its ability to regulate the homeostatic environment of the brain. While most studies were conducted over a period of 24-48 h, this study investigated the mechanisms by which chronic exposure of MA adversely affect the endothelial cells of BBB over an extended period of 96 h. MA induced significant depression of cell numbers at 96 h. This result was supported by flow cytometric data on the cell cycle which showed that brain endothelial cells (bEnd5) at 96 h were significantly suppressed in the S-phase of the cell cycle. In contrast, at 24-72 h control cell numbers for G1, S and G2-M phases were similar to MA-exposed cells. MA (0-1,000 µM) did not, however, statistically affect the viability and cytotoxicity of the bEnd5 cells, and the profile of ATP production and DNA synthesis (BrdU) across 96 h did not provide a rationale for the suppression of cell division. Our study reports for the first time that chronic exposure to MA results in long-term disruption of the cell cycle phases which eventuates in the attenuation of brain capillary endothelial cell growth after 96 h, compounding and contributing to the already well-known adverse short-term permeability effects of MA exposure on the BBB.

  1. Arctigenin induces cell cycle arrest by blocking the phosphorylation of Rb via the modulation of cell cycle regulatory proteins in human gastric cancer cells.

    PubMed

    Jeong, Jin Boo; Hong, Se Chul; Jeong, Hyung Jin; Koo, Jin Suk

    2011-10-01

    Gastric cancer is a leading cause of cancer-related deaths, worldwide being second only to lung cancer as a cause of death. Arctigenin, a representative dibenzylbutyrolactone lignan, occurs in a variety of plants. However, the molecular mechanisms of arctigenin for anti-tumor effect on gastric cancer have not been examined. This study examined the biological effects of arctigenin on the human gastric cancer cell line SNU-1 and AGS. Cell proliferation was determined by MTT assay. In MTT assay, the proliferation of SNU-1 and AGS cells was significantly inhibited by arctigenin in a time and dose dependent manner, as compared with SNU-1 and AGS cells cultured in the absence of arctigenin. Inhibition of cell proliferation by arctigenin was in part associated with apoptotic cell death, as shown by changes in the expression ratio of Bcl-2 to Bax by arctigenin. Also, arctigenin blocked cell cycle arrest from G(1) to S phase by regulating the expression of cell cycle regulatory proteins such as Rb, cyclin D1, cyclin E, CDK4, CDK2, p21Waf1/Cip1 and p15 INK4b. The antiproliferative effect of arctigenin on SNU-1 and AGS gastric cancer cells revealed in this study suggests that arctigenin has intriguing potential as a chemopreventive or chemotherapeutic agent.

  2. DNA Damage, Cell Cycle Arrest, and Apoptosis Induction Caused by Lead in Human Leukemia Cells.

    PubMed

    Yedjou, Clement G; Tchounwou, Hervey M; Tchounwou, Paul B

    2015-12-22

    In recent years, the industrial use of lead has been significantly reduced from paints and ceramic products, caulking, and pipe solder. Despite this progress, lead exposure continues to be a significant public health concern. The main goal of this research was to determine the in vitro mechanisms of lead nitrate [Pb(NO₃)₂] to induce DNA damage, apoptosis, and cell cycle arrest in human leukemia (HL-60) cells. To reach our goal, HL-60 cells were treated with different concentrations of Pb(NO₃)₂ for 24 h. Live cells and necrotic death cells were measured by the propidium idiode (PI) assay using the cellometer vision. Cell apoptosis was measured by the flow cytometry and DNA laddering. Cell cycle analysis was evaluated by the flow cytometry. The result of the PI demonstrated a significant (p < 0.05) increase of necrotic cell death in Pb(NO₃)₂-treated cells, indicative of membrane rupture by Pb(NO₃)₂ compared to the control. Data generated from the comet assay indicated a concentration-dependent increase in DNA damage, showing a significant increase (p < 0.05) in comet tail-length and percentages of DNA cleavage. Data generated from the flow cytometry assessment indicated that Pb(NO₃)₂ exposure significantly (p < 0.05) increased the proportion of caspase-3 positive cells (apoptotic cells) compared to the control. The flow cytometry assessment also indicated Pb(NO₃)₂ exposure caused cell cycle arrest at the G₀/G₁ checkpoint. The result of DNA laddering assay showed presence of DNA smear in the agarose gel with little presence of DNA fragments in the treated cells compared to the control. In summary, Pb(NO₃)₂ inhibits HL-60 cells proliferation by not only inducing DNA damage and cell cycle arrest at the G₀/G₁ checkpoint but also triggering the apoptosis through caspase-3 activation and nucleosomal DNA fragmentation accompanied by secondary necrosis. We believe that our study provides a new insight into the mechanisms of Pb

  3. DNA Damage, Cell Cycle Arrest, and Apoptosis Induction Caused by Lead in Human Leukemia Cells

    PubMed Central

    Yedjou, Clement G.; Tchounwou, Hervey M.; Tchounwou, Paul B.

    2015-01-01

    In recent years, the industrial use of lead has been significantly reduced from paints and ceramic products, caulking, and pipe solder. Despite this progress, lead exposure continues to be a significant public health concern. The main goal of this research was to determine the in vitro mechanisms of lead nitrate [Pb(NO3)2] to induce DNA damage, apoptosis, and cell cycle arrest in human leukemia (HL-60) cells. To reach our goal, HL-60 cells were treated with different concentrations of Pb(NO3)2 for 24 h. Live cells and necrotic death cells were measured by the propidium idiode (PI) assay using the cellometer vision. Cell apoptosis was measured by the flow cytometry and DNA laddering. Cell cycle analysis was evaluated by the flow cytometry. The result of the PI demonstrated a significant (p < 0.05) increase of necrotic cell death in Pb(NO3)2-treated cells, indicative of membrane rupture by Pb(NO3)2 compared to the control. Data generated from the comet assay indicated a concentration-dependent increase in DNA damage, showing a significant increase (p < 0.05) in comet tail-length and percentages of DNA cleavage. Data generated from the flow cytometry assessment indicated that Pb(NO3)2 exposure significantly (p < 0.05) increased the proportion of caspase-3 positive cells (apoptotic cells) compared to the control. The flow cytometry assessment also indicated Pb(NO3)2 exposure caused cell cycle arrest at the G0/G1 checkpoint. The result of DNA laddering assay showed presence of DNA smear in the agarose gel with little presence of DNA fragments in the treated cells compared to the control. In summary, Pb(NO3)2 inhibits HL-60 cells proliferation by not only inducing DNA damage and cell cycle arrest at the G0/G1 checkpoint but also triggering the apoptosis through caspase-3 activation and nucleosomal DNA fragmentation accompanied by secondary necrosis. We believe that our study provides a new insight into the mechanisms of Pb(NO3)2 exposure and its associated adverse health

  4. Single-cell analysis of transcription kinetics across the cell cycle

    NASA Astrophysics Data System (ADS)

    Skinner, Samuel; Xu, Heng; Jaiswal, Sonal; Freire, Pablo; Zwaka, Thomas; Golding, Ido

    2015-03-01

    Transcription is a highly stochastic process. A common way of inferring transcription kinetics is to measure mRNA abundance in individual cells and compare the observed copy-number statistics to the prediction of a theoretical stochastic model. However, the reliability of this procedure is hampered by the fact that the measured mRNA numbers represent integration over the finite lifetime of mRNA, over multiple copies of the same gene, and the mixing of cells from different phases of the cell cycle. Here we address these limitations by simultaneously quantifying nascent and mature mRNA in individual cells, and incorporating gene-copy and cell-cycle effects in the analysis of mRNA statistics. We demonstrate this approach on Oct4 and Nanog, two key players in the mouse pluripotency network. We find that both genes are well described by a two-state stochastic model for transcription initiation. The difference in their expression characteristics is attributed to a 2.6-fold difference in the probability of switching to an active transcriptional state. Early in the cell cycle, the two copies of each gene exhibit independent activity. However, after gene replication, the probability of each gene copy to be active diminishes, resulting in dosage compensation.

  5. Cell-cycle-independent transitions in temporal identity of mammalian neural progenitor cells

    PubMed Central

    Okamoto, Mayumi; Miyata, Takaki; Konno, Daijiro; Ueda, Hiroki R.; Kasukawa, Takeya; Hashimoto, Mitsuhiro; Matsuzaki, Fumio; Kawaguchi, Ayano

    2016-01-01

    During cerebral development, many types of neurons are sequentially generated by self-renewing progenitor cells called apical progenitors (APs). Temporal changes in AP identity are thought to be responsible for neuronal diversity; however, the mechanisms underlying such changes remain largely unknown. Here we perform single-cell transcriptome analysis of individual progenitors at different developmental stages, and identify a subset of genes whose expression changes over time but is independent of differentiation status. Surprisingly, the pattern of changes in the expression of such temporal-axis genes in APs is unaffected by cell-cycle arrest. Consistent with this, transient cell-cycle arrest of APs in vivo does not prevent descendant neurons from acquiring their correct laminar fates. Analysis of cultured APs reveals that transitions in AP gene expression are driven by both cell-intrinsic and -extrinsic mechanisms. These results suggest that the timing mechanisms controlling AP temporal identity function independently of cell-cycle progression and Notch activation mode. PMID:27094546

  6. Cell cycle control in the early embryonic development of aquatic animal species.

    PubMed

    Siefert, Joseph C; Clowdus, Emily A; Sansam, Christopher L

    2015-12-01

    The cell cycle is integrated with many aspects of embryonic development. Not only is proper control over the pace of cell proliferation important, but also the timing of cell cycle progression is coordinated with transcription, cell migration, and cell differentiation. Due to the ease with which the embryos of aquatic organisms can be observed and manipulated, they have been a popular choice for embryologists throughout history. In the cell cycle field, aquatic organisms have been extremely important because they have played a major role in the discovery and analysis of key regulators of the cell cycle. In particular, the frog Xenopus laevis has been instrumental for understanding how the basic embryonic cell cycle is regulated. More recently, the zebrafish has been used to understand how the cell cycle is remodeled during vertebrate development and how it is regulated during morphogenesis. This review describes how some of the unique strengths of aquatic species have been leveraged for cell cycle research and suggests how species such as Xenopus and zebrafish will continue to reveal the roles of the cell cycle in human biology and disease.

  7. Cell cycle progression and de novo centriole assembly after centrosomal removal in untransformed human cells

    PubMed Central

    Uetake, Yumi; Lončarek, Jadranka; Nordberg, Joshua J.; English, Christopher N.; La Terra, Sabrina; Khodjakov, Alexey; Sluder, Greenfield

    2007-01-01

    How centrosome removal or perturbations of centrosomal proteins leads to G1 arrest in untransformed mammalian cells has been a mystery. We use microsurgery and laser ablation to remove the centrosome from two types of normal human cells. First, we find that the cells assemble centrioles de novo after centrosome removal; thus, this phenomenon is not restricted to transformed cells. Second, normal cells can progress through G1 in its entirety without centrioles. Therefore, the centrosome is not a necessary, integral part of the mechanisms that drive the cell cycle through G1 into S phase. Third, we provide evidence that centrosome loss is, functionally, a stress that can act additively with other stresses to arrest cells in G1 in a p38-dependent fashion. PMID:17227892

  8. Nuclear cathepsin L activity is required for cell cycle progression of colorectal carcinoma cells.

    PubMed

    Tamhane, Tripti; Lllukkumbura, Rukshala; Lu, Shiying; Maelandsmo, Gunhild M; Haugen, Mads H; Brix, Klaudia

    2016-03-01

    Prominent tasks of cysteine cathepsins involve endo-lysosomal proteolysis and turnover of extracellular matrix constituents or plasma membrane proteins for maintenance of intestinal homeostasis. Here we report on enhanced levels and altered subcellular localization of distinct cysteine cathepsins in adenocarcinoma tissue in comparison to adjacent normal colon. Immunofluorescence and immunoblotting investigations revealed the presence of cathepsin L in the nuclear compartment in addition to its expected endo-lysosomal localization in colorectal carcinoma cells. Cathepsin L was represented as the full-length protein in the nuclei of HCT116 cells from which stefin B, a potent cathepsin L inhibitor, was absent. Fluorescence activated cell sorting analyses with synchronized cell cultures revealed deceleration of cell cycle progression of HCT116 cells upon inhibition of cathepsin L activity, while expression of cathepsin L-enhanced green fluorescent protein chimeras accelerated S-phase entry. We conclude that the activity of cathepsin L is high in the nucleus of colorectal carcinoma cells because of lacking stefin B inhibitory activity. Furthermore, we hypothesize that nuclear cathepsin L accelerates cell cycle progression of HCT116 cells thereby supporting the notion that cysteine cathepsins may play significant roles in carcinogenesis due to deregulated trafficking.

  9. Mitochondrial growth and division during the cell cycle in HeLa cells

    PubMed Central

    Posakony, JW; England, JM; Attardi, G

    1977-01-01

    The growth and division of mitochondria during the cell cycle was investigated by a morphometric analysis of electron micrographs of synchronized HeLa cells. The ratio of total outer membrane contour length to cytoplasmic area did not vary significantly during the cell cycle, implying a continuous growth of the mitochondrial outer membrane. The mean fraction of cytoplasmic area occupied by mitochondrial profiles was likewise found to remain constant, indicating that the increase in total mitochondrial volume per cell occurs continuously during interphase, in such a way that the mitochondrial complement occupies a constant fraction( approximately 10-11(percent)) of the volume of the cytoplasm. The mean area, outer membrane contour length, and axis ratio of the mitochondrial profiles also did not vary appreciably during the cell cycle; furthermore, the close similarity of the frequency distributions of these parameters for the six experimental time-points suggested a stable mitochondrial shape distribution. The constancy of both the mean mitochondrial profile area and the number of mitochondrial profiles per unit of cytoplasmic area was interpreted to indicate the continuous division of mitochondria at the level of the cell population. Furthermore, no evidence was found for the occurrence of synchronous mitochondrial growth and division within individual cells. Thus, it appears that, in HeLa cells, there is no fixed temporal relationship between the growth and division of mitochondria and the events of the cell cycle. A number of statistical methods were developed for the purpose of making numerical estimates of certain three-dimensional cellular and mitochondrial parameters. Mean cellular and cytoplasmic volumes were calculated for the six time-points; both exhibited a nonlinear, approx. twofold increase. A comparison of the axis ratio distributions of the mitochondrial profiles with theoretical distributions expected from random sectioning of bodies of various

  10. KOH concentration effect on cycle life of nickel-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Lim, Hong S.; Verzwyvelt, S. A.

    1987-01-01

    A cycle life test of Ni/H2 cells containing electrolytes of various KOH concentrations and a sintered type nickel electrode was carried out at 23 C using a 45 min accelerated low Earth orbit (LEO) cycle regime at 80 percent depth of discharge. One of three cells containing 26 percent KOH has achieved over 28,000 cycles, and the other two 19,000 cycles, without a sign of failure. Two other cells containing 31 percent KOH electrolyte, which is the concentration presently used in aerospace cells, failed after 2,979 and 3,620 cycles. This result indicates that the cycle life of the present type of Ni/H2 cells may be extended by a factor of 5 to 10 simply by lowering the KOH concentration. Long cycle life of a Ni/H2 battery at high depth-of-discharge operation is desired, particularly for an LEO spacecraft application. Typically, battery life of about 30,000 cycles is required for a five year mission in an LEO. Such a cycle life with presently available cells can be assured only at a very low depth-of-discharge operation. Results of testing already show that the cycle life of an Ni/H2 cell is tremendously improved by simply using an electrolyte of low KOH concentration.

  11. Cell cycle alterations, apoptosis, and response to low-dose-rate radioimmunotherapy in lymphoma cells

    SciTech Connect

    Macklis, R.M.; Beresford, B.A.; Palayoor, S.; Sweeney, S.; Humm, J.L.

    1993-10-20

    In an attempt to elucidate some aspects of the radiobiological basis of radioimmunotherapy, we have evaluated the in vitro cellular response patterns for malignant lymphoma cell lines exposed to high- and low-dose-rate radiation administered within the physiological context of antibody cell-surface binding. We used two different malignant lymphoma cell lines, a Thy1.2{sup +} murine T-lymphoma line called EL-4 and a CD20{sup +} human B-lymphoma line called Raji. Irradiated cells were evaluated for viability, cell-cycle changes, patterns of post-radiation morphologic changes, and biochemical hallmarks of radiation-associated necrosis and programmed cell death. The EL-4 line was sensitive to both high-dose-rate and low-dose-rate irradiation, while the Raji showed efficient cell kill only after high-dose-rate irradiation. Studies of radiation-induced cell cycle changes demonstrated that both cell lines were efficiently blocked at the G2/M interface by high-dose-rate irradiation, with the Raji cells appearing somewhat more susceptible than the EL-4 cells to low-dose-rate radiation-induced G2/M block. Electron microscopy and DNA gel electrophoresis studies showed that a significant proportion of the EL-4 cells appeared to be dying by radiation-induced programmed cell death (apoptosis) while the Raji cells appeared to be dying primarily by classical radiation-induced cellular necrosis. We propose that the unusual clinical responsiveness of some high and low grade lymphomas to modest doses of low-dose-rate radioimmunotherapy may be explained in part by the induction of apoptosis. The unusual dose-response characteristics observed in some experimental models of radiation-induced apoptosis may require a reappraisal of standard linear quadratic and alpha/beta algorithms used to predict target tissue cytoreduction after radioimmunotheraphy. 34 refs., 4 figs.

  12. Cell cycle synchronization of skin fibroblast cells in four species of family Felidae.

    PubMed

    Wittayarat, M; Thongphakdee, A; Saikhun, K; Chatdarong, K; Otoi, T; Techakumphu, M

    2013-04-01

    This study was examined whether the species of felid affects synchronization accuracy at the G0/G1 stage of the cell cycle and the occurrence of apoptosis by different protocols, such as serum starvation, confluent and roscovitine treatment. Skin fibroblast cells were obtained from the Asian golden cat, marbled cat, leopard and Siamese cat. The cells from each animal were treated with either serum starvation for 1-5 days, cell confluency-contact inhibition for 5 days or roscovitine at various concentrations (7.5-30 μm). Flow cytometric analysis revealed that serum starvation for 3 days provided the highest cell population arrested at the G0/G1 stage, irrespective of the felid species. In all species, 100% confluency gave a significantly higher percentage of cells arrested at the G0/G1 stage compared with the non-treated control cells. The effects of roscovitine treatment and the appropriate concentration on the rates of G0/G1 cells differed among the felid species. Serum starvation for more than 4 days in the marbled cat and Siamese cat and roscovitine treatment with 30 μm in the Asian golden cat and leopard increased the rates of apoptosis. In conclusion, different felid species responded to different methods of cell cycle synchronization. Asian golden cat and Siamese cat fibroblast cells were successfully synchronized to G0/G1 stage using the serum starvation and roscovitine treatment, whereas only confluency-contact inhibition treatment induced cell synchronization in the leopard. Moreover, these three methods did not successfully induce cell synchronization of the marbled cat. These findings may be valuable for preparing their donor cells for somatic cell nuclear transfer in the future.

  13. Apoptosis and cell-cycle arrest in human and murine tumor cells are initiated by isoprenoids.

    PubMed

    Mo, H; Elson, C E

    1999-04-01

    Diverse classes of phytochemicals initiate biological responses that effectively lower cancer risk. One class of phytochemicals, broadly defined as pure and mixed isoprenoids, encompasses an estimated 22,000 individual components. A representative mixed isoprenoid, gamma-tocotrienol, suppresses the growth of murine B16(F10) melanoma cells, and with greater potency, the growth of human breast adenocarcinoma (MCF-7) and human leukemic (HL-60) cells. beta-Ionone, a pure isoprenoid, suppresses the growth of B16 cells and with greater potency, the growth of MCF-7, HL-60 and human colon adenocarcinoma (Caco-2) cells. Results obtained with diverse cell lines differing in ras and p53 status showed that the isoprenoid-mediated suppression of growth is independent of mutated ras and p53 functions. beta-Ionone suppressed the growth of human colon fibroblasts (CCD-18Co) but only when present at three-fold the concentration required to suppress the growth of Caco-2 cells. The isoprenoids initiated apoptosis and, concomitantly arrested cells in the G1 phase of the cell cycle. Both suppress 3-hydroxy-3-methylglutaryl CoA reductase activity. beta-Ionone and lovastatin interfered with the posttranslational processing of lamin B, an activity essential to assembly of daughter nuclei. This interference, we postulate, renders neosynthesized DNA available to the endonuclease activities leading to apoptotic cell death. Lovastatin-imposed mevalonate starvation suppressed the glycosylation and translocation of growth factor receptors to the cell surface. As a consequence, cells were arrested in the G1 phase of the cell cycle. This rationale may apply to the isoprenoid-mediated G1-phase arrest of tumor cells. The additive and potentially synergistic actions of these isoprenoids in the suppression of tumor cell proliferation and initiation of apoptosis coupled with the mass action of the diverse isoprenoid constituents of plant products may explain, in part, the impact of fruit, vegetable

  14. Complex regulatory pathways coordinate cell cycle progression and development in Caulobacter crescentus

    PubMed Central

    Brown, Pamela J.B.; Hardy, Gail G.; Trimble, Michael J.; Brun, Yves V.

    2008-01-01

    Caulobacter crescentus has become the predominant bacterial model system to study the regulation of cell cycle progression. Stage specific processes such as chromosome replication and segregation, and cell division are coordinated with the development of four polar structures: the flagellum, pili, stalk, and holdfast. The production, activation, localization, and proteolysis of specific regulatory proteins at precise times during the cell cycle culminate in the ability of the cell to produce two physiologically distinct daughter cells. We examine the recent advances that have enhanced our understanding of the mechanisms of temporal and spatial regulation that occur during cell cycle progression. PMID:18929067

  15. Cell cycle regulation of the c-Myc transcriptional activation domain.

    PubMed Central

    Seth, A; Gupta, S; Davis, R J

    1993-01-01

    The product of the c-myc gene (c-Myc) is a sequence-specific DNA-binding protein that has previously been demonstrated to be required for cell cycle progression. Here we report that the c-Myc DNA binding site confers cell cycle regulation to a reporter gene in Chinese hamster ovary cells. The observed transactivation was biphasic with a small increase in G1 and a marked increase during the S-to-G2/M transition of the cell cycle. This cell cycle regulation of transactivation potential is accounted for, in part, by regulatory phosphorylation of the c-Myc transactivation domain. Together, these data demonstrate that c-Myc may have an important role in the progression of cells through both the G1 and G2 phases of the cell cycle. Images PMID:8321217

  16. Inositol pyrophosphates modulate cell cycle independently of alteration in telomere length.

    PubMed

    Banfic, Hrvoje; Crljen, Vladiana; Lukinovic-Skudar, Vesna; Dembitz, Vilma; Lalic, Hrvoje; Bedalov, Antonio; Visnjic, Dora

    2016-01-01

    Synthesis of inositol pyrophosphates through activation of Kcs1 plays an important role in the signalling response required for cell cycle progression after mating pheromone arrest. Overexpression of Kcs1 doubled the level of inositol pyrophosphates when compared to wild type cells and 30 min following the release from α-factor block further increase in inositol pyrophosphates was observed, which resulted that cells overexpressing Kcs1 reached G2/M phase earlier than wild type cells. Similar effect was observed in ipk1Δ cells, which are unable to synthesize IP6-derived inositol pyrophosphates (IP7 and IP8) but will synthesize IP5-derived inositol pyrophosphates (PP-IP4 and (PP)2-IP3). Although ipk1Δ cells have shorter telomeres than wild type cells, overexpression of Kcs1 in both strains have similar effect on cell cycle progression. As it is known that PP-IP4 regulates telomere length through Tel1, inositol polyphosphates, cell cycle and telomere length were determined in tel1Δ cells. The release of the cells from α-factor block and overexpression of Kcs1 in tel1Δ cells produced similar effects on inositol pyrophosphates level and cell cycle progression when compared to wild type cells, although tel1Δ cells possesses shorter telomeres than wild type cells. It can be concluded that telomere length does not affect cell cycle progression, since cells with short telomeres (ipk1Δ and tel1Δ) progress through cell cycle in a similar manner as wild type cells and that overexpression of Kcs1 in cells with either short or normal telomeres will increase S phase progression without affecting telomere length. Furthermore, IP5-derived inositol pyrophosphates can compensate for the loss of IP6-derived inositol pyrophosphates, in modulating S phase progression of the cell cycle.

  17. Dietary estrogens stimulate human breast cells to enter the cell cycle.

    PubMed Central

    Dees, C; Foster, J S; Ahamed, S; Wimalasena, J

    1997-01-01

    It has been suggested that dietary estrogens neutralize the effect of synthetic chemicals that mimic the effects of estrogen (i.e., xenoestrogens, environmental estrogens). Genistein, a dietary estrogen, inhibits the growth of breast cancer cells at high doses but additional studies have suggested that at low doses, genistein stimulates proliferation of breast cancer cells. Therefore, if dietary estrogens are estrogenic at low doses, one would predict that they stimulate estrogen-receptor positive breast cancer cells to enter the cell cycle. Genistein and the fungal toxin zearalenone were found to increase the activity of cyclin dependent kinase 2 (Cdk2) and cyclin D1 synthesis and stimulate the hyperphosphorylation of the retinoblastoma susceptibility gene product pRb105 in MCF-7 cells. The steroidal antiestrogen ICI 182,780 suppressed dietary estrogen-mediated activation of Cdk2. Dietary estrogens not only failed to suppress DDT-induced Cdk2 activity, but were found to slightly increase enzyme activity. Both zearalenone and genistein were found to stimulate the expression of a luciferase reporter gene under the control of an estrogen response element in MVLN cells. Our findings are consistent with a conclusion that dietary estrogens at low concentrations do not act as antiestrogens, but act like DDT and estradiol to stimulate human breast cancer cells to enter the cell cycle. Images Figure 2. Figure 3. A Figure 3. B Figure 4. Figure 5. PMID:9168007

  18. Microsporidia infection impacts the host cell's cycle and reduces host cell apoptosis.

    PubMed

    Martín-Hernández, Raquel; Higes, Mariano; Sagastume, Soledad; Juarranz, Ángeles; Dias-Almeida, Joyce; Budge, Giles E; Meana, Aránzazu; Boonham, Neil

    2017-01-01

    Intracellular parasites can alter the cellular machinery of host cells to create a safe haven for their survival. In this regard, microsporidia are obligate intracellular fungal parasites with extremely reduced genomes and hence, they are strongly dependent on their host for energy and resources. To date, there are few studies into host cell manipulation by microsporidia, most of which have focused on morphological aspects. The microsporidia Nosema apis and Nosema ceranae are worldwide parasites of honey bees, infecting their ventricular epithelial cells. In this work, quantitative gene expression and histology were studied to investigate how these two parasites manipulate their host's cells at the molecular level. Both these microsporidia provoke infection-induced regulation of genes involved in apoptosis and the cell cycle. The up-regulation of buffy (which encodes a pro-survival protein) and BIRC5 (belonging to the Inhibitor Apoptosis protein family) was observed after infection, shedding light on the pathways that these pathogens use to inhibit host cell apoptosis. Curiously, different routes related to cell cycle were modified after infection by each microsporidia. In the case of N. apis, cyclin B1, dacapo and E2F2 were up-regulated, whereas only cyclin E was up-regulated by N. ceranae, in both cases promoting the G1/S phase transition. This is the first report describing molecular pathways related to parasite-host interactions that are probably intended to ensure the parasite's survival within the cell.

  19. Microsporidia infection impacts the host cell's cycle and reduces host cell apoptosis

    PubMed Central

    Higes, Mariano; Sagastume, Soledad; Juarranz, Ángeles; Dias-Almeida, Joyce; Budge, Giles E.; Meana, Aránzazu; Boonham, Neil

    2017-01-01

    Intracellular parasites can alter the cellular machinery of host cells to create a safe haven for their survival. In this regard, microsporidia are obligate intracellular fungal parasites with extremely reduced genomes and hence, they are strongly dependent on their host for energy and resources. To date, there are few studies into host cell manipulation by microsporidia, most of which have focused on morphological aspects. The microsporidia Nosema apis and Nosema ceranae are worldwide parasites of honey bees, infecting their ventricular epithelial cells. In this work, quantitative gene expression and histology were studied to investigate how these two parasites manipulate their host’s cells at the molecular level. Both these microsporidia provoke infection-induced regulation of genes involved in apoptosis and the cell cycle. The up-regulation of buffy (which encodes a pro-survival protein) and BIRC5 (belonging to the Inhibitor Apoptosis protein family) was observed after infection, shedding light on the pathways that these pathogens use to inhibit host cell apoptosis. Curiously, different routes related to cell cycle were modified after infection by each microsporidia. In the case of N. apis, cyclin B1, dacapo and E2F2 were up-regulated, whereas only cyclin E was up-regulated by N. ceranae, in both cases promoting the G1/S phase transition. This is the first report describing molecular pathways related to parasite-host interactions that are probably intended to ensure the parasite’s survival within the cell. PMID:28152065

  20. Cytoplasmic sequestration of cyclin D1 associated with cell cycle withdrawal of neuroblastoma cells

    SciTech Connect

    Sumrejkanchanakij, Piyamas; Eto, Kazuhiro; Ikeda, Masa-Aki . E-mail: mikeda.emb@tmd.ac.jp

    2006-02-03

    The regulation of D-type cyclin-dependent kinase activity is critical for neuronal differ