DOCSLIB.ORG

Radiosensitivity and Cell Age in the Mitotic Cycle

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Radiosensitivity and Cell Age in the Mitotic Cycle Introduction • Mammalian cells propagate by mitosis • The cell cycle in all dividing mammalian Radiosensitivity and Cell Age in cells is divided into four phases: – M phase can be identified through the light the Mitotic Cycle microscope – After the cells pass through M, there is a period of apparent inactivity, termed G1 (the first "gap" in activity in the cell cycle) Chapter 4 – Next, the cells actively synthesize DNA during the S phase, identified through labeling – Between the S phase and the onset of the next Eric J. Hall., Amato Giaccia, mitosis, there is another gap in activity, G2 • The time between successive divisions Radiobiology for the Radiologist defines the cell cycle time TC Cell labeling techniques Cell labeling techniques • Cell visualization during the S phase is based on feeding the cells with radioactive labels or fluorescent dyes, which are incorporated into duplicating chromosomes • The medium is flushed after a short time period • Cells are fixed and stained for ease of viewing after varying time interval • Tritiated thymidine (3HTdR) incorporated into chromosomes emits b- particles forming a latent image on a layer of photo-emulsion coated over the • Labeled cells are counted sample (takes ~3-4 weeks) • Labeling with dyes (e.g., BrdU) is more convinient; use fluorochrome-tagged antibody to BrdU, observable under a fluorescence microscope Cell labeling techniques Cell labeling techniques • BrdU labeling movie: • To ensure free access of the antibody to its http://academics.wellesley.edu/Biology/Concepts/Html/brdu.html antigen, the cells must be fixed and permeabilized • Antibodies are extremely sensitive to location of a • Sample preparation entails fixing the target cells cellular component or a specific molecule (a tissue to the substrate (microscope slide) antigen) • Perfect fixation immobilizes the antigens, while – Target can be inside or on the surface of a cell retaining authentic cellular and subcellular – Antibody is tagged with a fluorescing dye molecule architecture and permitting access of antibodies to all cells and subcellular compartments 1 Cell labeling techniques Flow cytometry • Only a small portion • A biophysical technique that allows counting and of cells in a sample sorting cells in a sample based on their size, uptakes the label structure, and functionality • The technique is very – Functionality is determined through labeling with antigen- labor-intensive, specific fluorescent dyes relying on the manual cell counting • Can discriminate cells at speeds up to 70,000 • New automated cells/second (compare to 200 cells/min manually) approaches • Flow cytometry tutorials: significantly speed up https://www.youtube.com/watch?v=EQXPJ7eeesQ https://www.youtube.com/watch?x-yt-cl=84838260&feature=player_embedded&v=sfWWxFBltpQ&x-yt-ts=1422327029 characterization The cell cycle times Cyclins and protein kinases • Based on the number of counted labeled • Cyclins and cyclin-dependent kinases were discovered by mitosis and varying the time between Hartwell, Hunt, and Nurse, who thus won the 2001 Nobel labeling and counting, can characterize Prize in Physiology or Medicine "for their discoveries of the temporal transitions within a cycle key regulators of the cell cycle" • The difference among mammalian cell • Cyclins are a group of regulatory proteins that control the cycle times, varying from ~10 to 100 progression of cells through the cell cycle by activating hours among different cells in different cyclin-dependent kinase (CDK) enzymes circumstances, is the result of a dramatic • Protein kinases are enzymes that modify the function of variation in the length of the G1 period other proteins by attaching phosphate groups (PO4-) to them (phosphorylate proteins) • The remaining components of the cell – They are key controllers of most biochemical pathways and cycle vary comparatively little important in health and disease Origin of HeLa cells: http://www.youtube.com/watch?v=0gF8bCE4wqA Progression through the cell cycle Synchronizing cells within cycle • Each cyclin protein is • Survival curves are collected with the assumption synthesized at a discrete that the population of irradiated cells is phase of the cycle: cyclin D and E in G , cyclin A in S asynchronous: cells distributed throughout all 1 phases of the cycle and G2, and cyclin B in G2 and M. Transitions in the • Study of the variation of radiosensitivity with the cycle occur only if a given kinase activates the proteins position or age of the cell in the cell cycle was made block required for progression possible only by the development of techniques to • Tumor suppressor genes produce synchronously dividing cell cultures: (p53, Rb) can block cell populations of cells in which all of the cells occupy division if DNA is damaged the same phase of the cell cycle at a given time Current concept of the cell cycle and its regulation by protein kinases, activated by cyclins 2 Effect of x-rays on synchronously Synchronizing cells within cycle dividing cell cultures • Two principal techniques of cell synchronization: • The proportion of cells – Mitotic harvest: physical separation of cells preparing for that survive the dose in- mitosis (works only on monolayer cell cultures) creases rapidly with time – Use of a drug, eliminating all cells in S phase, and as the cells move into S imposing a block on cells at the end of G1 (works for cell phase and tissue samples) • When the cells move out of S into G1 phase and subsequently to a second mitosis, the proportion of surviving cells decreases again Effect of x-rays on synchronously Variation of radiosensitivity dividing cell cultures with cell age in the mitotic cycle • Cells are the most sensitive in • Cells are most sensitive at or close to mitosis Calculated for M and G2: survival curves are M phase under steep and have no shoulder • Resistance is usually greatest in the latter part of S phase. The hypoxia • Cells in the latter part of S increased resistance is thought to be caused by homologous phase (LS) exhibit a survival recombination repair between sister chromatids that is curve that is less steep, but more likely to occur after the DNA has replicated has a very broad shoulder • If G1 phase has an appreciable length, a resistant period is • The range of sensitivity evident early in G1, followed by a sensitive period toward the between the most sensitive end of G1 cells (mitotic) and the most resistant cells (late S) is of the • G2 phase is almost as sensitive as M phase same order of magnitude as • Exceptions to these generalizations have been noted for some Cell survival curves for Chinese hamster cells at various stages of the cell cycle the oxygen effect cell lines Molecular checkpoint genes Molecular checkpoint genes • Mammalian cells exposed to radiation tend to • Mutant cells that lose this G2 checkpoint gene function experience a block in the G2 phase move directly into mitosis • In several strains of yeast, mutants have been with damaged chromosomes isolated that are more sensitive than the wild type – They are at a higher risk of dying - hence their greater to both ionizing radiation and UV light by a factor sensitivity to radiation and other between 10 and 100 DNA-damaging agents • The mutant gene has been cloned and sequenced – Cells that survive mitosis are likely to give rise to errors in and found to be a “G2 molecular checkpoint gene" chromosome segregation - hence more prone to carcinogenesis 3 The age-response function for a Effect of oxygen tissue in vivo • Effect of oxygen on cell survival curves is • The pattern of response in characterized by oxygen enhancement ratio this organized normal tissue, with a sensitive period D ( hypoxic ) OER % S between G1 and S and D ( aerated ) % S maximum radioresistance • The OER was measured at 2.3 to 2.4 for G2 phase late in S, is very similar to cells, compared with 2.8 to 2.9 for S phase, with G1 that characteristic of many cell lines cultured in vitro phase cells showing an intermediate value (label uptake) • This small variation of oxygenation through the • High LET radiation cycle is of little clinical significance in radiation decreases the variation of The survival of jejunal crypt cells exposed to g- radiosensitivity through the therapy rays or neutrons as they pass through the cell cycle after synchronization with hydroxyurea cell cycle Mechanisms for the age- The implications of the age- response function response function in radiotherapy • The patterns of radiosensitivity and radio- • Since general population of cells in tissues is resistance correlate with the mechanism of asynchronous, cells in more sensitive phases of the repair of DNA DSBs: cycle are preferentially killed – Radiosensitivity correlates with nonhomologous end joining, which dominates early in the cell cycle and is • Variations in sensitivity through the cell cycle error prone may be important in radiation therapy because – Radioresistance correlates with homologous they lead to "sensitization resulting from recombinational repair, which occurs after replication reassortment" in a fractionated regimen (in S phase) and is more faithful • Not fully understood • Reassortment is one of the “4 R’s of radiobiology” Introduction • Radiation damage to mammalian cells can Fractionated Radiation and the operationally be divided into three categories: – (1) lethal damage, which is irreversible and irreparable Dose-Rate Effect and, by definition, leads irrevocably to cell death – (2) potentially lethal damage (PLD), the component of Chapter 5 radiation damage
Load more

Recommended publications
  • DNA Damage Checkpoint Dynamics Drive Cell Cycle Phase Transitions
    bioRxiv preprint doi: https://doi.org/10.1101/137307; this version posted August 4, 2017. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. DNA damage checkpoint dynamics drive cell cycle phase transitions Hui Xiao Chao1,2, Cere E. Poovey1, Ashley A. Privette1, Gavin D. Grant3,4, Hui Yan Chao1, Jeanette G. Cook3,4, and Jeremy E. Purvis1,2,4,† 1Department of Genetics 2Curriculum for Bioinformatics and Computational Biology 3Department of Biochemistry and Biophysics 4Lineberger Comprehensive Cancer Center University of North Carolina, Chapel Hill 120 Mason Farm Road Chapel Hill, NC 27599-7264 †Corresponding Author: Jeremy Purvis Genetic Medicine Building 5061, CB#7264 120 Mason Farm Road Chapel Hill, NC 27599-7264 [email protected] ABSTRACT DNA damage checkpoints are cellular mechanisms that protect the integrity of the genome during cell cycle progression. In response to genotoxic stress, these checkpoints halt cell cycle progression until the damage is repaired, allowing cells enough time to recover from damage before resuming normal proliferation. Here, we investigate the temporal dynamics of DNA damage checkpoints in individual proliferating cells by observing cell cycle phase transitions following acute DNA damage. We find that in gap phases (G1 and G2), DNA damage triggers an abrupt halt to cell cycle progression in which the duration of arrest correlates with the severity of damage. However, cells that have already progressed beyond a proposed “commitment point” within a given cell cycle phase readily transition to the next phase, revealing a relaxation of checkpoint stringency during later stages of certain cell cycle phases.
    [Show full text]
  • Cell Cycle Arrest and DNA Endoreduplication Following P21waf1/Cip1 Expression
    Oncogene (1998) 17, 1691 ± 1703 1998 Stockton Press All rights reserved 0950 ± 9232/98 $12.00 http://www.stockton-press.co.uk/onc Cell cycle arrest and DNA endoreduplication following p21Waf1/Cip1 expression Stewart Bates, Kevin M Ryan, Andrew C Phillips and Karen H Vousden ABL Basic Research Program, NCI-FCRDC, Building 560, Room 22-96, West 7th Street, Frederick, Maryland 21702-1201, USA p21Waf1/Cip1 is a major transcriptional target of p53 and there are an increasing number of regulatory mechan- has been shown to be one of the principal mediators of isms that serve to inhibit cdk activity. Primary amongst the p53 induced G1 cell cycle arrest. We show that in these is the expression of cdk inhibitors (CDKIs) that addition to the G1 block, p21Waf1/Cip1 can also contribute can bind to and inhibit cyclin/cdk complexes (Sherr to a delay in G2 and expression of p21Waf1/Cip1 gives rise and Roberts, 1996). These fall into two classes, the to cell cycle pro®les essentially indistinguishable from INK family which bind to cdk4 and cdk6 and inhibit those obtained following p53 expression. Arrest of cells complex formation with D-cyclins, and the p21Waf1/Cip1 in G2 likely re¯ects an inability to induce cyclin B1/cdc2 family that bind to cyclin/cdk complexes and inhibit kinase activity in the presence of p21Waf1/Cip1, although the kinase activity. inecient association of p21Waf1/Cip1 and cyclin B1 The p21Waf1/Cip1 family of CDKIs include p21Waf1/Cip1, suggests that the mechanism of inhibition is indirect. p27 and p57 and are broad range inhibitors of cyclin/ Cells released from an S-phase block were not retarded cdk complexes (Gu et al., 1993; Harper et al., 1993; in their ability to progress through S-phase by the Xiong et al., 1993; Firpo et al., 1994; Polyak et al., presence of p21Waf1/Cip1, despite ecient inhibition of 1994; Toyoshima and Hunter, 1994; Lee et al., 1995; cyclin E, A and B1 dependent kinase activity, suggesting Matsuoka et al., 1995).
    [Show full text]
  • Mitosis Vs. Meiosis
    Mitosis vs. Meiosis In order for organisms to continue growing and/or replace cells that are dead or beyond repair, cells must replicate, or make identical copies of themselves. In order to do this and maintain the proper number of chromosomes, the cells of eukaryotes must undergo mitosis to divide up their DNA. The dividing of the DNA ensures that both the “old” cell (parent cell) and the “new” cells (daughter cells) have the same genetic makeup and both will be diploid, or containing the same number of chromosomes as the parent cell. For reproduction of an organism to occur, the original parent cell will undergo Meiosis to create 4 new daughter cells with a slightly different genetic makeup in order to ensure genetic diversity when fertilization occurs. The four daughter cells will be haploid, or containing half the number of chromosomes as the parent cell. The difference between the two processes is that mitosis occurs in non-reproductive cells, or somatic cells, and meiosis occurs in the cells that participate in sexual reproduction, or germ cells. The Somatic Cell Cycle (Mitosis) The somatic cell cycle consists of 3 phases: interphase, m phase, and cytokinesis. 1. Interphase: Interphase is considered the non-dividing phase of the cell cycle. It is not a part of the actual process of mitosis, but it readies the cell for mitosis. It is made up of 3 sub-phases: • G1 Phase: In G1, the cell is growing. In most organisms, the majority of the cell’s life span is spent in G1. • S Phase: In each human somatic cell, there are 23 pairs of chromosomes; one chromosome comes from the mother and one comes from the father.
    [Show full text]
  • Low Dose and Low Dose-Rate Radiation Effects and Models
    Forty-Fourth Annual Meeting Program Low Dose and Low Dose-Rate Radiation Effects and Models April 14–15, 2008 Bethesda North Marriott Hotel & Conference Center 5701 Marinelli Road North Bethesda, MD 20852 On the cover: • top: Two nuclei have each been “hit” by three alpha particles from a microbeam and show activated γH2AX foci at the site of the traversal. • center: Chromosome painting technology makes it possible to identify each human chromosome and characterize the number, location and types of aberrations produced by ionizing radiation. • bottom: Measuring the frequency of micronuclei provides a rapid measure of cytogenetic damage, which increases as a function of radiation dose. Introduction Low Dose and Low Dose-Rate Radiation Effects and Models Forty-Fourth Annual Meeting of the National Council on Radiation Protection and Measurements (NCRP) Potential human health effects of low doses of ionizing models of the biological responses and human health radiation such as those experienced in occupational impacts of exposure to low doses of radiation. The and medical exposures are of great contemporary meeting will feature presentations by international interest. Considerable debate exists over the applica- experts on the topics of (1) molecular, cellular, tissue, bility of a linear-nonthreshold model for characterizing and laboratory animal studies on the effects of expo- the biological responses and health effects of expo- sure to low dose and low dose-rate radiation, (2) sure to low radiation doses, and alternative models results of epidemiological studies on human health have been proposed. A related subject of interest and effects of low radiation doses in occupational, medical debate is the effect of the rate of delivery of radiation and other exposure scenarios, (3) potential impacts of doses on the biological and health outcomes of expo- these findings on future regulatory guidance and pub- sure.
    [Show full text]
  • Role of Cyclin-Dependent Kinase 1 in Translational Regulation in the M-Phase
    cells Review Role of Cyclin-Dependent Kinase 1 in Translational Regulation in the M-Phase Jaroslav Kalous *, Denisa Jansová and Andrej Šušor Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Rumburska 89, 27721 Libechov, Czech Republic; [email protected] (D.J.); [email protected] (A.Š.) * Correspondence: [email protected] Received: 28 April 2020; Accepted: 24 June 2020; Published: 27 June 2020 Abstract: Cyclin dependent kinase 1 (CDK1) has been primarily identified as a key cell cycle regulator in both mitosis and meiosis. Recently, an extramitotic function of CDK1 emerged when evidence was found that CDK1 is involved in many cellular events that are essential for cell proliferation and survival. In this review we summarize the involvement of CDK1 in the initiation and elongation steps of protein synthesis in the cell. During its activation, CDK1 influences the initiation of protein synthesis, promotes the activity of specific translational initiation factors and affects the functioning of a subset of elongation factors. Our review provides insights into gene expression regulation during the transcriptionally silent M-phase and describes quantitative and qualitative translational changes based on the extramitotic role of the cell cycle master regulator CDK1 to optimize temporal synthesis of proteins to sustain the division-related processes: mitosis and cytokinesis. Keywords: CDK1; 4E-BP1; mTOR; mRNA; translation; M-phase 1. Introduction 1.1. Cyclin Dependent Kinase 1 (CDK1) Is a Subunit of the M Phase-Promoting Factor (MPF) CDK1, a serine/threonine kinase, is a catalytic subunit of the M phase-promoting factor (MPF) complex which is essential for cell cycle control during the G1-S and G2-M phase transitions of eukaryotic cells.
    [Show full text]
  • Radioresistance of Brain Tumors
    cancers Review Radioresistance of Brain Tumors Kevin Kelley 1, Jonathan Knisely 1, Marc Symons 2,* and Rosamaria Ruggieri 1,2,* 1 Radiation Medicine Department, Hofstra Northwell School of Medicine, Northwell Health, Manhasset, NY 11030, USA; [email protected] (K.K.); [email protected] (J.K.) 2 The Feinstein Institute for Molecular Medicine, Hofstra Northwell School of Medicine, Northwell Health, Manhasset, NY 11030, USA * Correspondence: [email protected] (M.S.); [email protected] (R.R.); Tel.: +1-516-562-1193 (M.S.); +1-516-562-3410 (R.R.) Academic Editor: Zhe-Sheng (Jason) Chen Received: 17 January 2016; Accepted: 24 March 2016; Published: 30 March 2016 Abstract: Radiation therapy (RT) is frequently used as part of the standard of care treatment of the majority of brain tumors. The efficacy of RT is limited by radioresistance and by normal tissue radiation tolerance. This is highlighted in pediatric brain tumors where the use of radiation is limited by the excessive toxicity to the developing brain. For these reasons, radiosensitization of tumor cells would be beneficial. In this review, we focus on radioresistance mechanisms intrinsic to tumor cells. We also evaluate existing approaches to induce radiosensitization and explore future avenues of investigation. Keywords: radiation therapy; radioresistance; brain tumors 1. Introduction 1.1. Radiotherapy and Radioresistance of Brain Tumors Radiation therapy is a mainstay in the treatment of the majority of primary tumors of the central nervous system (CNS). However, the efficacy of this therapeutic approach is significantly limited by resistance to tumor cell killing after exposure to ionizing radiation. This phenomenon, termed radioresistance, can be mediated by factors intrinsic to the cell or by the microenvironment.
    [Show full text]
  • Interferon-A-Induced G1 Phase Arrest Through Up-Regulated Expression of CDK Inhibitors, P19ink4d and P21cip1 in Mouse Macrophages
    Oncogene (1998) 16, 2075 ± 2086 1998 Stockton Press All rights reserved 0950 ± 9232/98 $12.00 http://www.stockton-press.co.uk/onc Interferon-a-induced G1 phase arrest through up-regulated expression of CDK inhibitors, p19Ink4D and p21Cip1 in mouse macrophages Masaaki Matsuoka, Kenzaburo Tani and Shigetaka Asano Department of Hematology and Oncology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108, Japan The mechanism of cell cycle arrest induced by interferon-a dependent kinases or cdks (reviewed by Sherr, 1993). (IFN-a) was analysed using a mouse macrophage cell line, D-type cyclins (Lew et al., 1991; Matsushime et al., 1991) BAC1.2F5A. IFN-a added in media before mid-G1 and cyclin E (Ko et al., 1991; Lew et al., 1991) govern the prohibited cells from entering S phase. The blockage of G1/S transition in association with their proper G1/S transition was associated with diminuition of both physiological partners, cdk4 (Matsushime et al., 1992) cyclin D1/cdk4- and cyclin E/cdk2-associated kinase or cdk6 (Meyerson and Harlow, 1994), and cdk2 (Dulic et activities. G1 cyclin-associated kinase activities were al., 1992; Ko et al., 1992), respectively. When cells enter down-regulated quickly after the addition of IFN-a. Cells G1 phase with mitogenic stimuli, the synthesis and the treated with IFN-a contained excess amounts of cdk active complex formation of D-type cyclins and cdk4 are inhibitors which down-regulated G1 cyclin/cdk-associated induced in early to middle G1 phase, and their complex kinase activities in the proliferating cells and this action formation and activities reach maximal levels at late G1 was counteracted by exogenously-supplied recombinant (Matsushime et al., 1992, 1994).
    [Show full text]
  • Targeting the WEE1 Kinase As a Molecular Targeted Therapy for Gastric Cancer
    www.impactjournals.com/oncotarget/ Oncotarget, Vol. 7, No. 31 Research Paper Targeting the WEE1 kinase as a molecular targeted therapy for gastric cancer Hye-Young Kim1,2, Yunhee Cho1,3, HyeokGu Kang1,3, Ye-Seal Yim1,3, Seok-Jun Kim1,3, Jaewhan Song2, Kyung-Hee Chun1,3 1Department of Biochemistry & Molecular Biology, Yonsei University College of Medicine, Seodaemun-gu, Seoul 03722, Korea 2Department of Biochemistry, College of Life Science and Biotechnology, Seodaemun-gu, Seoul 03722, Korea 3Brain Korea 21 PlusProject for Medical Science, Yonsei University, Seodaemun-gu, Seoul 03722, Korea Correspondence to: Kyung-Hee Chun, email: [email protected] Keywords: WEE1, AZD1775 (MK-1775), 5-FU, Paclitaxel, gastric cancer Received: September 07, 2015 Accepted: May 28, 2016 Published: June 23, 2016 ABSTRACT Wee1 is a member of the Serine/Threonine protein kinase family and is a key regulator of cell cycle progression. It has been known that WEE1 is highly expressed and has oncogenic functions in various cancers, but it is not yet studied in gastric cancers. In this study, we investigated the oncogenic role and therapeutic potency of targeting WEE1 in gastric cancer. At first, higher expression levels of WEE1 with lower survival probability were determined in stage 4 gastric cancer patients or male patients with accompanied lymph node metastasis. To determine the function of WEE1 in gastric cancer cells, we determined that WEE1 ablation decreased the proliferation, migration, and invasion, while overexpression of WEE1 increased these effects in gastric cancer cells. We also validated the clinical application of WEE1 targeting by a small molecule, AZD1775 (MK-1775), which is a WEE1 specific inhibitor undergoing clinical trials.
    [Show full text]
  • The Cell Cycle & Mitosis
    The Cell Cycle & Mitosis Cell Growth The Cell Cycle is G1 phase ___________________________________ _______________________________ During the Cell Cycle, a cell ___________________________________ ___________________________________ Anaphase Cell Division ___________________________________ Mitosis M phase M ___________________________________ S phase replication DNA Interphase Interphase is ___________________________ ___________________________________ G2 phase Interphase is divided into three phases: ___, ___, & ___ G1 Phase S Phase G2 Phase The G1 phase is a period of The S phase replicates During the G2 phase, many of activity in which cells _______ ________________and the organelles and molecules ____________________ synthesizes _______ molecules. required for ____________ __________ Cells will When DNA replication is ___________________ _______________ and completed, _____________ When G2 is completed, the cell is synthesize new ___________ ____________________ ready to enter the ____________________ ____________________ ____________________ ____________________ ____________________ Mitosis are divided into four phases: _____________, ______________, _____________, & _____________ Below are cells in two different phases of the cell cycle, fill in the blanks using the word bank: Chromatin Nuclear Envelope Chromosome Sister Chromatids Nucleolus Spinder Fiber Centrosome Centrioles 5.._________ 1.__________ v 6..__________ 2.__________ 7.__________ 3.__________ 8..__________ 4.__________ v The Cell Cycle & Mitosis Microscope Lab:
    [Show full text]
  • Loss of P21 Disrupts P14arf-Induced G1 Cell Cycle Arrest but Augments P14arf-Induced Apoptosis in Human Carcinoma Cells
    Oncogene (2005) 24, 4114–4128 & 2005 Nature Publishing Group All rights reserved 0950-9232/05 $30.00 www.nature.com/onc Loss of p21 disrupts p14ARF-induced G1 cell cycle arrest but augments p14ARF-induced apoptosis in human carcinoma cells Philipp G Hemmati1,3, Guillaume Normand1,3, Berlinda Verdoodt1, Clarissa von Haefen1, Anne Hasenja¨ ger1, DilekGu¨ ner1, Jana Wendt1, Bernd Do¨ rken1,2 and Peter T Daniel*,1,2 1Department of Hematology, Oncology and Tumor Immunology, University Medical Center Charite´, Campus Berlin-Buch, Berlin-Buch, Germany; 2Max-Delbru¨ck-Center for Molecular Medicine, Berlin-Buch, Germany The human INK4a locus encodes two structurally p16INK4a and p14ARF (termed p19ARF in the mouse), latter unrelated tumor suppressor proteins, p16INK4a and p14ARF of which is transcribed in an Alternative Reading Frame (p19ARF in the mouse), which are frequently inactivated in from a separate exon 1b (Duro et al., 1995; Mao et al., human cancer. Both the proapoptotic and cell cycle- 1995; Quelle et al., 1995; Stone et al., 1995). P14ARF is regulatory functions of p14ARF were initially proposed to usually expressed at low levels, but rapid upregulation be strictly dependent on a functional p53/mdm-2 tumor of p14ARF is triggered by various stimuli, that is, suppressor pathway. However, a number of recent reports the expression of cellular or viral oncogenes including have implicated p53-independent mechanisms in the E2F-1, E1A, c-myc, ras, and v-abl (de Stanchina et al., regulation of cell cycle arrest and apoptosis induction by 1998; Palmero et al., 1998; Radfar et al., 1998; Zindy p14ARF. Here, we show that the G1 cell cycle arrest et al., 1998).
    [Show full text]
  • Regulation of P27kip1 and P57kip2 Functions by Natural Polyphenols
    biomolecules Review Regulation of p27Kip1 and p57Kip2 Functions by Natural Polyphenols Gian Luigi Russo 1,* , Emanuela Stampone 2 , Carmen Cervellera 1 and Adriana Borriello 2,* 1 National Research Council, Institute of Food Sciences, 83100 Avellino, Italy; [email protected] 2 Department of Precision Medicine, University of Campania “Luigi Vanvitelli”, 81031 Napoli, Italy; [email protected] * Correspondence: [email protected] (G.L.R.); [email protected] (A.B.); Tel.: +39-0825-299-331 (G.L.R.) Received: 31 July 2020; Accepted: 9 September 2020; Published: 13 September 2020 Abstract: In numerous instances, the fate of a single cell not only represents its peculiar outcome but also contributes to the overall status of an organism. In turn, the cell division cycle and its control strongly influence cell destiny, playing a critical role in targeting it towards a specific phenotype. Several factors participate in the control of growth, and among them, p27Kip1 and p57Kip2, two proteins modulating various transitions of the cell cycle, appear to play key functions. In this review, the major features of p27 and p57 will be described, focusing, in particular, on their recently identified roles not directly correlated with cell cycle modulation. Then, their possible roles as molecular effectors of polyphenols’ activities will be discussed. Polyphenols represent a large family of natural bioactive molecules that have been demonstrated to exhibit promising protective activities against several human diseases. Their use has also been proposed in association with classical therapies for improving their clinical effects and for diminishing their negative side activities. The importance of p27Kip1 and p57Kip2 in polyphenols’ cellular effects will be discussed with the aim of identifying novel therapeutic strategies for the treatment of important human diseases, such as cancers, characterized by an altered control of growth.
    [Show full text]
  • The Cell Cycle Coloring Worksheet
    Name: Date: Period: The Cell Cycle Coloring Worksheet Label the diagram below with the following labels: Anaphase Interphase Mitosis Cell division (M Phase) Interphase Prophase Cytokinesis Interphase S-DNA replication G1 – cell grows Metaphase Telophase G2 – prepares for mitosis Then on the diagram, lightly color the G1 phase BLUE, the S phase YELLOW, the G2 phase RED, and the stages of mitosis ORANGE. Color the arrows indicating all of the interphases in GREEN. Color the part of the arrow indicating mitosis PURPLE and the part of the arrow indicating cytokinesis YELLOW. M-PHASE YELLOW: GREEN: CYTOKINESIS INTERPHASE PURPLE: TELOPHASE MITOSIS ANAPHASE ORANGE METAPHASE BLUE: G1: GROWS PROPHASE PURPLE MITOSIS RED:G2: PREPARES GREEN: FOR MITOSIS INTERPHASE YELLOW: S PHASE: DNA REPLICATION GREEN: INTERPHASE Use the diagram and your notes to answer the following questions. 1. What is a series of events that cells go through as they grow and divide? CELL CYCLE 2. What is the longest stage of the cell cycle called? INTERPHASE 3. During what stage does the G1, S, and G2 phases happen? INTERPHASE 4. During what phase of the cell cycle does mitosis and cytokinesis occur? M-PHASE 5. During what phase of the cell cycle does cell division occur? MITOSIS 6. During what phase of the cell cycle is DNA replicated? S-PHASE 7. During what phase of the cell cycle does the cell grow? G1,G2 8. During what phase of the cell cycle does the cell prepare for mitosis? G2 9. How many stages are there in mitosis? 4 10. Put the following stages of mitosis in order: anaphase, prophase, metaphase, and telophase.
    [Show full text]