DOCSLIB.ORG

Selective Role for Superoxide in Insp3 Receptor-Mediated Mitochondrial Dysfunction and Endothelial Apoptosis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Selective Role for Superoxide in Insp3 Receptor-Mediated Mitochondrial Dysfunction and Endothelial Apoptosis Thomas Jefferson University Jefferson Digital Commons Department of Pathology, Anatomy, and Cell Department of Pathology, Anatomy, and Cell Biology Faculty Papers Biology 9-26-2005 Selective role for superoxide in InsP3 receptor-mediated mitochondrial dysfunction and endothelial apoptosis. Muniswamy Madesh University of Pennsylvania Brian J Hawkins University of Pennsylvania Tatyana Milovanova University of Pennsylvania CunnigaiperFollow this and D additionalBhanumathy works at: https://jdc.jefferson.edu/pacbfp Thomas Part ofJeff theerson Medical Univ Anatersityomy Commons, Medical Cell Biology Commons, and the Medical Pathology SurCommonsesh K Joseph LetThomas us Jeff knowerson Univ howersity access to this document benefits ouy SeeRecommended next page for Citation additional authors Madesh, Muniswamy; Hawkins, Brian J; Milovanova, Tatyana; Bhanumathy, Cunnigaiper D; Joseph, Suresh K; Ramachandrarao, Satish P; Sharma, Kumar; Kurosaki, Tomohiro; and Fisher, Aron B, "Selective role for superoxide in InsP3 receptor-mediated mitochondrial dysfunction and endothelial apoptosis." (2005). Department of Pathology, Anatomy, and Cell Biology Faculty Papers. Paper 115. https://jdc.jefferson.edu/pacbfp/115 This Article is brought to you for free and open access by the Jefferson Digital Commons. The Jefferson Digital Commons is a service of Thomas Jefferson University's Center for Teaching and Learning (CTL). The Commons is a showcase for Jefferson books and journals, peer-reviewed scholarly publications, unique historical collections from the University archives, and teaching tools. The Jefferson Digital Commons allows researchers and interested readers anywhere in the world to learn about and keep up to date with Jefferson scholarship. This article has been accepted for inclusion in Department of Pathology, Anatomy, and Cell Biology Faculty Papers by an authorized administrator of the Jefferson Digital Commons. For more information, please contact: [email protected]. Authors Muniswamy Madesh, Brian J Hawkins, Tatyana Milovanova, Cunnigaiper D Bhanumathy, Suresh K Joseph, Satish P Ramachandrarao, Kumar Sharma, Tomohiro Kurosaki, and Aron B Fisher This article is available at Jefferson Digital Commons: https://jdc.jefferson.edu/pacbfp/115 JCB: ARTICLE Selective role for superoxide in InsP3 receptor–mediated mitochondrial dysfunction and endothelial apoptosis Muniswamy Madesh,1,2 Brian J. Hawkins,1 Tatyana Milovanova,1 Cunnigaiper D. Bhanumathy,3 Suresh K. Joseph,3 Satish P. RamachandraRao,4 Kumar Sharma,4 Tomohiro Kurosaki,5 and Aron B. Fisher1 1Institute for Environmental Medicine and 2Department of Cancer Biology, University of Pennsylvania, Philadelphia, PA 19104 3Department of Pathology, Anatomy, and Cell Biology and 4Dorrance Hamilton Research Laboratories, Thomas Jefferson University, Philadelphia, PA 19107 5Laboratory for Lymphocyte Differentiation, Institute of Physical and Chemical Research, Research Center for Allergy and Immunology, Turumi-ku, Yokohama 230-0045, Japan eactive oxygen species (ROS) play a divergent pendent, and cells lacking the three InsP3 receptor 2ϩ role in both cell survival and cell death during is- (InsP3R) isoforms failed to display the [Ca ]i transient. .Ϫ 2ϩ R chemia/reperfusion (I/R) injury and associated Importantly, the O2 -triggered Ca mobilization pre- inflammation. In this study, ROS generation by activated ceded a loss in mitochondrial membrane potential that 2ϩ 2ϩ macrophages evoked an intracellular Ca ([Ca ]i) was independent of other oxidants and mitochondrially transient in endothelial cells that was ablated by a com- derived ROS. Activation of apoptosis occurred selec- .Ϫ bination of superoxide dismutase and an anion channel tively in response to O2 and could be prevented by 2ϩ 2ϩ .Ϫ blocker. [Ca ]i store depletion, but not extracellular [Ca ]i buffering. This study provides evidence that O2 2ϩ 2ϩ Ca chelation, prevented [Ca ]i elevation in response facilitates an InsP3R-linked apoptotic cascade and may Ϫ . to O2 that was inositol 1,4,5-trisphosphate (InsP3) de- serve a critical function in I/R injury and inflammation. Introduction Receptor-mediated generation of reactive oxygen species iron leads to hydroxyl radical formation via Fenton chemistry. .Ϫ (ROS) is necessary for signal transduction, gene expression, During I/R injury, O2 production in the vasculature is sub- and cell proliferation in smooth muscle cells, T and B lympho- stantially increased (Wei et al., 1999) and is accompanied by cytes, and fibroblasts (Devadas et al., 2002). Conversely, ROS endothelial cytotoxicity (for review see Li and Shah, 2004). produced under pathological conditions such as ischemia/re- However, the molecular mechanisms by which ROS lead to perfusion (I/R) or inflammation are associated with cellular organ damage are poorly understood. dysfunction and apoptosis (Davies, 1995). Endothelial cells In pathological conditions, cell death is facilitated by an THE JOURNAL OF CELL BIOLOGY 2ϩ respond to numerous external stimuli by producing the super- elevation in intracellular calcium ([Ca ]i; Hajnoczky et al., .Ϫ oxide anion (O2 ). In physiological conditions, mitochondrial 2003; Orrenius et al., 2003) via inositol 1,4,5-trisphosphate .Ϫ respiratory chain proteins produce O2 , which can be dismu- (InsP3). InsP3 is a second messenger produced by the hydrolysis tated into hydrogen peroxide (H2O2) or react with nitric oxide of phosphatidylinositol-4,5-bisphosphate by PLC. InsP3 receptor 2ϩ to produce peroxynitrite. In addition, reaction of H2O2 with (InsP3R)–mediated [Ca ]i changes are associated with a rapid, transient Ca2ϩ release from Ca2ϩ stores in the ER followed by Ca2ϩ entry through slow-activating plasma membrane store- Correspondence to Muniswamy Madesh: [email protected] operated channels (Putney and Bird, 1993; Parekh and Penner, 2ϩ Abbreviations used in this paper: 2-APB, 2-aminoethoxydiphenyl borate; BAPTA, 1997; Berridge et al., 1998). InsP3 [Ca ]i signals control a Ј Ј 2ϩ 1,2-bis(2-aminophenoxy)ethane-N,N,N ,N -tetracetate; [Ca ]i, intracellular ⌬⌿ wide range of cellular functions, including cell proliferation calcium; m, mitochondrial membrane potential; DCF, dichlorofluorescein; DPI, diphenyleneiodonium; ECM, extracellular medium; GPCR, G protein–coupled re- and apoptosis (Berridge et al., 2000; Orrenius et al., 2003). ceptor; InsP3, inositol 1,4,5-trisphosphate; InsP3R, InsP3 receptor; I/R, ischemia/ Apoptosis is reduced in cells lacking all three InsP R isoforms reperfusion; KO, knockout; LPS, lipopolysaccharide; MPTP, mitochondrial perme- 3 ability transition pore; PI, propidium iodide; PMVEC, pulmonary microvascular (DT40 avian B cells) and after selective suppression of InsP3R-3 endothelial cell; ROS, reactive oxygen species; SOD, superoxide dismutase; (Jayaraman and Marks, 1997; Sugawara et al., 1997), indicat- t-BuOOH, tert-butyl hydroperoxide; Tg, thapsigargin; TKO, triple KO; TMRE, tetramethylrhodamine, ethyl ester, perchlorate. ing the important role of InsP3 in cell death mechanisms (Pan et 2ϩ The online version of this article contains supplemental material. al., 2001). Alterations in [Ca ]i after oxidative stress facilitate © The Rockefeller University Press $8.00 The Journal of Cell Biology, Vol. 170, No. 7, September 26, 2005 1079–1090 http://www.jcb.org/cgi/doi/10.1083/jcb.200505022 JCB 1079 activation of the mitochondrial permeability transition pore (MPTP), which releases cytochrome c from the mitochondrial intermembrane space, leading to mitochondrial membrane po- tential (⌬⌿m) loss, assembly of the apoptosome, and activation of downstream caspases (Crompton, 1999). Recent evidence suggested that cytochrome c transiently released from mito- 2ϩ chondria interacts with InsP3R and amplifies Ca -mediated apoptosis (Boehning et al., 2003). Endothelial cells subjected to oxidative stress undergo apoptosis (Warren et al., 2000). Although there is evidence that 2ϩ 2ϩ perturbations of cellular Ca homeostasis (including [Ca ]i elevation, ER Ca2ϩ depletion, and mitochondrial Ca2ϩ in- creases) occur, the mechanisms by which oxidative stress me- diates endothelial apoptosis remain unclear. Events in the early 2ϩ stages of stress signaling include the mobilization of [Ca ]i (Patterson et al., 2004), the generation of ROS, and the forma- tion of lipid peroxides. However, it is unclear whether radical formation is a consequence of Ca2ϩ mobilization or a parallel event in early stress signaling. The proximity between mito- chondria and the ER facilitates a higher Ca2ϩ exposure in mito- chondria relative to the cytosol when released from the ER (Rizzuto et al., 1998). During pathological situations, excess ER-released Ca2ϩ may be detrimental to mitochondrial func- tion and may trigger mitochondrial fragmentation and apopto- sis. Previously, Bcl-2 family proteins have been implicated in apoptosis by affecting cellular Ca2ϩ homeostasis (Pinton et al., 2000; Pan et al., 2001; Li et al., 2002). A recent study reported 2؉ that a functional interaction of Bcl-2 with InsP3R attenuated Figure 1. Endothelial cell Ca mobilization in response to activated 2ϩ macrophage-derived ROS. (A) J774A.1 murine macrophages were acti- InsP3R activation, which in turn controlled InsP3-evoked Ca vated by 1 ␮g/ml LPS for 3 h in the presence or absence of the flavoprotein release (Chen et al., 2004), in contrast to our findings that Bcl-XL inhibitor DPI for 1 h. Cells were incubated with 10 ␮M of the ROS-sensitive activates InsP3R (White et al., 2005). In addition, ER-localized dye H2DCF-DA
Load more

Recommended publications
  • Ultrastructure in Ochromonas Danica
    EFFECTS OF CHLORAMPHENICOL ON CHLOROPLAST AND MITOCHONDRIAL ULTRASTRUCTURE IN OCHROMONAS DANICA HEIDI SMITH-JOHANNSEN and SARAH P . GIBBS From the Department of Biology, McGill University, Montreal 110, P. Q., Canada ABSTRACT The effect of chloramphenicol (CAP) on cell division and organelle ultrastructure was studied during light-induced chloroplast development in the Chrysophyte alga, Ochromonas danica . Since the growth rate of the CAP-treated cells is the same as that of the control cells for the first 12 hr in the light, CAP is presumed to be acting during that interval solely by inhibiting protein synthesis on chloroplast and mitochondrial ribosomes. CAP markedly inhibits chloroplast growth and differentiation . During the first 12 hr in the light, chloro- phyll synthesis is inhibited by 9317/c , the formation of new thylakoid membranes is reduced by 91 70, and the synthesis of chloroplast ribosomes is inhibited by 81 %. Other chloroplast- associated abnormalities which occur during the first 12 hr and become more pronounced with extended CAP treatment are the presence of prolamellar bodies and of abnormal stacks of thylakoids, the proliferation of the perinuclear reticulum, and the accumulation of dense granular material between the chloroplast envelope and the chloroplast endo- plasmic reticulum . CAP also causes a progressive loss of the mitochondrial cristae, which is paralleled by a decline in the growth rate of the cells, but it has no effect on the synthesis of mitochondrial ribosomes. We postulate that one or more chloroplast ribosomal proteins are synthesized on chloroplast ribosomes, whereas mitochondrial ribosomal pro- teins are synthesized on cytoplasmic ribosomes. INTRODUCTION Both chloroplasts and mitochondria are known insoluble inner membrane proteins, are believed to contain DNA and RNA and to have all the to be synthesized on mitochondrial ribosomes (3) .
    [Show full text]
  • Reporterseq Reveals Genome-Wide Dynamic Modulators of the Heat
    RESEARCH ARTICLE ReporterSeq reveals genome-wide dynamic modulators of the heat shock response across diverse stressors Brian D Alford1†, Eduardo Tassoni-Tsuchida1,2†, Danish Khan1, Jeremy J Work1, Gregory Valiant3, Onn Brandman1* 1Department of Biochemistry, Stanford University, Stanford, United States; 2Department of Biology, Stanford University, Stanford, United States; 3Department of Computer Science, Stanford University, Stanford, United States Abstract Understanding cellular stress response pathways is challenging because of the complexity of regulatory mechanisms and response dynamics, which can vary with both time and the type of stress. We developed a reverse genetic method called ReporterSeq to comprehensively identify genes regulating a stress-induced transcription factor under multiple conditions in a time- resolved manner. ReporterSeq links RNA-encoded barcode levels to pathway-specific output under genetic perturbations, allowing pooled pathway activity measurements via DNA sequencing alone and without cell enrichment or single-cell isolation. We used ReporterSeq to identify regulators of the heat shock response (HSR), a conserved, poorly understood transcriptional program that protects cells from proteotoxicity and is misregulated in disease. Genome-wide HSR regulation in budding yeast was assessed across 15 stress conditions, uncovering novel stress-specific, time- specific, and constitutive regulators. ReporterSeq can assess the genetic regulators of any transcriptional pathway with the scale of pooled genetic screens and the precision of pathway- specific readouts. *For correspondence: [email protected] †These authors contributed equally to this work Introduction Competing interests: The The heat shock response (HSR) is a conserved stress response that shields cells from cytoplasmic authors declare that no proteotoxicity by increasing the expression of protective proteins (Lindquist, 1986; Mori- competing interests exist.
    [Show full text]
  • Live Cell Imaging of Meiosis in Arabidopsis Thaliana
    TOOLS AND RESOURCES Live cell imaging of meiosis in Arabidopsis thaliana Maria A Prusicki1, Emma M Keizer2†, Rik P van Rosmalen2†, Shinichiro Komaki1‡, Felix Seifert1§, Katja Mu¨ ller1, Erik Wijnker3, Christian Fleck2#*, Arp Schnittger1* 1Department of Developmental Biology, University of Hamburg, Hamburg, Germany; 2Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen, The Netherlands; 3Department of Plant Science, Laboratory of Genetics, Wageningen University and Research, Wageningen, The Netherlands Abstract To follow the dynamics of meiosis in the model plant Arabidopsis, we have established a live cell imaging setup to observe male meiocytes. Our method is based on the concomitant visualization of microtubules (MTs) and a meiotic cohesin subunit that allows following five cellular *For correspondence: parameters: cell shape, MT array, nucleus position, nucleolus position, and chromatin condensation. [email protected] (CF); [email protected] We find that the states of these parameters are not randomly associated and identify 11 cellular (AS) states, referred to as landmarks, which occur much more frequently than closely related ones, indicating that they are convergence points during meiotic progression. As a first application of our †These authors contributed system, we revisited a previously identified mutant in the meiotic A-type cyclin TARDY equally to this work ASYNCHRONOUS MEIOSIS (TAM). Our imaging system enabled us to reveal both qualitatively and Present address: ‡Plant Cell
    [Show full text]
  • Communications Between Mitochondria and Endoplasmic Reticulum in the Regulation of Metabolic Homeostasis
    cells Review Communications between Mitochondria and Endoplasmic Reticulum in the Regulation of Metabolic Homeostasis Pengcheng Zhang, Daniels Konja, Yiwei Zhang and Yu Wang * The State Key Laboratory of Pharmaceutical Biotechnology, Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong SAR, China; [email protected] (P.Z.); [email protected] (D.K.); [email protected] (Y.Z.) * Correspondence: [email protected] Abstract: Mitochondria associated membranes (MAM), which are the contact sites between en- doplasmic reticulum (ER) and mitochondria, have emerged as an important hub for signaling molecules to integrate the cellular and organelle homeostasis, thus facilitating the adaptation of energy metabolism to nutrient status. This review explores the dynamic structural and functional features of the MAM and summarizes the various abnormalities leading to the impaired insulin sensitivity and metabolic diseases. Keywords: mitochondria; endoplasmic reticulum; MAM; energy metabolism 1. Introduction Citation: Zhang, P.; Konja, D.; Zhang, In mammalian cells, the mitochondrion is the organelle specialized for energy produc- Y.; Wang, Y. Communications tion through the processes of oxidative phosphorylation, tricarboxylic acid (TCA) cycle between Mitochondria and and fatty acid β-oxidation [1]. Approximately 90% of cellular reactive oxygen species Endoplasmic Reticulum in the (ROS) are produced from mitochondria during the reactions of oxidative phosphorylation Regulation of Metabolic Homeostasis. (OXPHOS)
    [Show full text]
  • Advanced Cellular Biochemistry
    University of Montana ScholarWorks at University of Montana Syllabi Course Syllabi Spring 2-1-2007 BMED 600.01: Advanced Cellular Biochemistry Mark L. Grimes University of Montana - Missoula, [email protected] Scott Samuels University of Montana, Missoula, [email protected] Follow this and additional works at: https://scholarworks.umt.edu/syllabi Let us know how access to this document benefits ou.y Recommended Citation Grimes, Mark L. and Samuels, Scott, "BMED 600.01: Advanced Cellular Biochemistry" (2007). Syllabi. 11120. https://scholarworks.umt.edu/syllabi/11120 This Syllabus is brought to you for free and open access by the Course Syllabi at ScholarWorks at University of Montana. It has been accepted for inclusion in Syllabi by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. Advanced Cellular Biochemistry Bioc/Phar 600 Spring 2007 Instructors M. Grimes Scott Samuels 243-4977; HS 112 243-6145; Clapp 207 [email protected] [email protected] Class 8:40 am - 10:00 am MF Skaggs Building 336 Jan 22, 2007 - May 4, 2007 Class 8:40 am - 10:00 am W Skaggs Building 114 Jan 22, 2007 - May 4, 2007 Catalog course description (4 cr.) Exploration on a molecular level the regulation of structure, function, and dynamics of eukaryotic cells. Topics include membranes, cytoskeleton, transcription, translation, signal transduction, cell motility, cell proliferation, and programmed cell death. Overview Cell Biology is vast and dense and encompasses biochemistry, biophysics, molecular biology, microscopy, genetics, physiology, computer science, and developmental biology. This course will use as a main text Alberts, et al., Molecular Biology of the Cell, 4th ed.
    [Show full text]
  • Keith Roberts Porter: 1912–1997
    Keith Roberts Porter: 1912–1997 eith Roberts Porter died on May 2, 1997, just over a month short of his 85th birthday. He had the K perspicacity, good fortune, and patience to take advantage of the fast moving frontier of analytical biology after the Second World War to provide many of the tech- niques and experimental approaches that established the new field of biomedical research now known as cell biol- ogy. He was renowned for taking the first electron micro- graph of an intact cell, but his contributions went far be- yond that seminal instance. They ranged from technical developments, such as the roller flask for cell culture and the Porter-Blum ultramicrotome, to experimental and ob- servational achievements, such as studies on the synthesis and assembly of collagen, on the role of coated vesicles in endocytosis, on lipid digestion in the intestine, and on the universality of the 9 1 2 axoneme in cilia. The initial ultra- structure descriptions of the endoplasmic reticulum and the sarcoplasmic reticulum, identification of the role of T-tubules in excitation–contraction coupling in muscle and the role of the cytoskeleton in cell transformation and shape change, were his, as were many other contributions, described in some detail elsewhere (Peachey and Brinkley, 1983; Moberg, 1996). Absent from this list are his early pi- oneering work establishing the androgenetic haploid in frogs, an exercise in nuclear transplantation with conse- quences for the recent cloning of mammals, and his later ad- ventures with pigment migration in fish chromatophores. In addition to his specific scientific contributions, Keith Porter also made more important philosophical contribu- tions to the field that he helped to shape.
    [Show full text]
  • Cromartie a Comparison of the Films Contagion and the Band Played On
    CURRICULUM VITAE Gregory J. Cole Present Position: Professor Department of Biological and Biomedical Sciences Julius L. Chambers Biomedical/Biotechnology Research Institute North Carolina Central University 700 George Street Durham, NC 27707 Voice: 919-530-6034 Fax: 919-530-7760 e-mail: [email protected] Webpage: https://sites.google.com/site/colelabpage Education: 1973-1976 B.A., Biology, State University of New York, Plattsburgh, NY 1978-1982 Ph.D., Biological Science (Program in Neuroscience), Florida State University, Tallahassee, Florida Post-doctoral Experience: 1982-1985 Department of Biological Chemistry, Washington University School of Medicine, St. Louis, MO Professional Experience: 1985-1986 Instructor, Department of Biological Chemistry, Washington University School of Medicine, St. Louis, MO 1986-1987 Research Assistant Professor, Department of Biochemistry, University of Miami School of Medicine, Miami, FL 1987-1991 Assistant Professor, Department of Anatomy and Cell Biology, Medical University of South Carolina, Charleston, SC 1 1991-1993 Associate Professor, Department of Anatomy and Cell Biology, Medical University of South Carolina, Charleston, SC 1993-1998 Associate Professor, Neurobiotechnology Center, The Ohio State University, Columbus, OH 1993-1998 Associate Professor, Department of Cell Biology, Neurobiology, & Anatomy, The Ohio State University, Columbus, OH 1998-1999 Professor, Department of Cell Biology, Neurobiology, & Anatomy, The Ohio State University, Columbus, OH 1998-2000 Professor, Neurobiotechnology Center,
    [Show full text]
  • Over a Century of Quality Scientific Publishing
    OVER A CENTURY OF QUALITY SCIENTIFIC PUBLISHING Rockefeller University Press (RUP) is committed scientists who actively contribute to their fields, appreciate to quality and integrity in scientific publishing. We use the the value of peer review, and desire a better publication latest technologies and carry out rigorous peer review, experience for all. applying the highest standards of novelty, mechanistic Rockefeller University Press journals are indispensable insight, data integrity, and general interest to fulfill our mission of publishing excellent science. Our nonprofit assets to comprehensive life sciences collections at journals were established by the research community, and institutions that are engaged in cutting-edge research editorial decisions and policies continue to be driven by and train future generations of capable scientists. Journal of Cell Biology (JCB) Journal of Cell Biology publishes advances in any area of basic cell VOL 219 • NO 6 • JUNE 2020 WWW.JCB.ORG biology as well as applied cellular advances in fields such as immunology, neurobiology, JCB Editor-in-Chief: Jodi Nunnari, Chair of the Department of Molecular and metabolism, microbiology, developmental Cellular Biology, College of Biological Sciences, at University of California, Davis; biology, and plant biology. Est. 1955 Executive Editor: Tim Spencer, PhD 2021 | Vol. 220 Total publications: ~27,000 / total citations: ~2.6M 12 print and online issues | Articles published daily Impact Factor (IF): 8.811 Print ISSN: 0021-9525 | Online ISSN: 1540-8140 5-Year IF: 9.058 www.jcb.org IF rank in Cell Biology among primary research journals: 21 Journal of Experimental Medicine (JEM) Journal of Experimental publishes papers providing novel conceptual Editorial Board Co-Chairs: Carl Nathan, R.A.
    [Show full text]
  • February 8, 2019 To: Coalition S Science Europe AISBL Rue De La
    February 8, 2019 To: cOAlition S Science Europe AISBL Rue de la Science, 14 1040 Brussels, Belgium From: Susan King, PhD Executive Director Rockefeller University Press 950 Third Avenue, Floor 2 New York, NY 10022 Subject: Public Feedback on the Guidance on the Implementation of Plan S Rockefeller University Press (RUP) welcomes the opportunity to respond to the cOAlition S consultation on Plan S. RUP publishes the Journal of Cell Biology (JCB), Journal of Experimental Medicine (JEM), and Journal of General Physiology (JGP) and co-publishes Life Science Alliance (LSA). RUP’s nonprofit journals were established by the research community, and editorial decisions and policies continue to be driven by scientists who actively contribute to their fields, appreciate the value of peer review, and desire a better publication experience for all. RUP is a department of The Rockefeller University, and it is reflective of the university’s commitment to high-quality research to improve the understanding of life for the benefit of humanity. RUP is committed to quality and integrity in scientific publishing. Our goal is to publish excellent science using the latest technologies. In collaboration with academic editors based at leading institutions, we carry out rigorous peer review, applying the highest standards of novelty, mechanistic insight, data integrity, and general interest. For JCB, JEM and LSA, editorial decisions on research manuscripts are made through collaborative consultation between in-house professional scientific editors and research- active academic editors. The final decision on submissions rests with our academic editors at each of our journals. All digital images are examined before publication for evidence of inappropriate manipulation.
    [Show full text]
  • Structural Differentiation of Stacked and Unstacked Chloroplast Membranes
    STRUCTURAL DIFFERENTIATION OF STACKED AND UNSTACKED CHLOROPLAST MEMBRANES Freeze-Etch Electron Microscopy of Wild-Type and Mutant Strains of Chlamydomonas URSULA W . GOODENOUGH and L . ANDREW STAEHELIN From The Biological Laboratories, Harvard University, Cambridge, Massachusetts 0138 . Dr. Staehelin's present address is the Department of Molecular, Cellular and Developmental Downloaded from Biology, The University of Colorado, Boulder, Colorado 80302 ABSTRACT Wild-type chloroplast membranes from Chlamydomonas reinhardi exhibit four faces in freeze- etchreplicas : the complementary Bs and Cs faces are found where the membranes are stacked jcb.rupress.org together ; the complementary Bu and Cu faces are found in unstacked membranes . The Bs face carries a dense population of regularly spaced particles containing the large, 160 f 10 A particles that appear to be unique to chloroplast membranes . Under certain growth con- ditions, membrane stacking does not occur in the ac-5 strain . When isolated, these mem- branes remain unstacked, exhibit only Bu and Cu faces, and retain the ability to carry out normal photosynthesis . Membrane stacking is also absent in the ac-31 strain, and, when on August 28, 2017 isolated in a low-salt medium, these membranes remain unstacked and exhibit only Bu and Cu faces . When isolated in a high-salt medium, however, they stack normally, and Bs and Cs faces are produced by this in vitro stacking process . We conclude that certain particle distributions in the chloroplast membrane are created as a consequence of the stacking process, and that the ability of membranes to stack can be modified both by gene mutation and by the ionic environment in which the membranes are found .
    [Show full text]
  • Perspectives
    PERSPECTIVES fractionation of liver homogenates. The TIMELINE emphasis was on the quantitative monitoring of the distribution of the chemical con- stituents of the cell, rather than organelle George Emil Palade: charismatic purity5–8. Trial and error must have been the norm, and cold-room stamina a prerequisite, virtuoso of cell biology but this early period ultimately established the procedures that allowed organelles to remain intact without agglutination or lysis. Many Alan M. Tartakoff obstacles confronted these investigators, including a “…biochemical Zeitgeist that par- George Palade has created, shared and on the state of knowledge at that time in his ticles were a nuisance and stood in the way passed on a multidisciplinary view of the Nobel lecture,“…biologists [had been] in the of purification of … enzymes.”9 Whereas functional organization, biogenesis and same situation as astronomers and astro- biochemistry was developing rapidly, the dynamics of organelles. His open- physicists, who were permitted to see the understanding of the compartmentalization mindedness and tenacity, along with his objects of their interest, but not to touch of subcellular activities and the significance of rigour and sense of intellectual elegance, them; the cell was as distant from us as the organelles was still in its infancy. have been remarkable. This focus on the stars and galaxies were from them. More dra- Claude returned to his native Belgium in logic of organelles defined a crucial turning matic and frustrating was that we knew that 1949, but not before he and his colleagues point in biomedical science. The following the instrument at our disposal, the micro- had systematized the use of differential sedi- article sketches Palade’s research, as part scope … had … reached, irremediably, the mentation to isolate a comprehensive set of of a larger community that flourished after theoretical limits of its resolving power.”4 fractions from tissue homogenates using the Second World War.
    [Show full text]
  • Microtubule Polarity Confers Direction to Pigment Transport in Chromatophores Mark A
    Microtubule Polarity Confers Direction to Pigment Transport in Chromatophores Mark A. McNiven and Keith R. Porter Department of Biological Sciences, University of Maryland Baltimore County, Catonsville, Maryland 21228 Abstract. The cellular mechanisms used to direct toward a new focal point located at the arm centers. In translocating organdies are poorly understood. It is this study we monitored pigment movement in isolated believed that the intrinsic structural polarity of arms containing taxol-stabilized microtubules to test if microtubules may play a role in this process. We have the reversal in direction of pigment transport is depen- examined the effects that differently oriented microtu- dent upon the repolarization of microtubules. We re- bules have upon the direction of pigment transport in port that taxol delays both the microtubule reorienta- surgically severed melanophore arms. In a previous tion and reversal in transport direction in a paper (McNiven, M. A., M. Wang, and K. R. Porter, concentration-dependent manner. These and other 1984, Cell, 37:753-765) we reported that after isola- presented data suggest that the polarity of the microtu- tion, arms repolarized and reoriented their microtu- bule population within a melanophore confers direc- bules outward from their centers as if to form new tion on pigment transport. "microcellsY Pigment aggregation in these arms was HE directed translocation of organelles and trophic filaments (38, 39). The ability of a microtubule to confer di- substances within cells is an important physiological rection on transport is less defined. Several models have im- T process. Although a few types of intracellular particle plicated microtubule polarity in directing mitotic events (6, movement have been termed "random" or "saltatory-like" (9, 22, 23) and axoplasmic transport (27); however, the influ- 31, 32), there are many instances in which cells specifically ence of microtubule polarity on orienting organelle transport transport organelles from one location to another.
    [Show full text]