1
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Shammas MK, Huang X, Wu BP, Fessler E, Song I, Randolph NP, Li Y, Bleck CK, Springer DA, Fratter C, Barbosa IA, Powers AF, Quirós PM, Lopez-Otin C, Jae LT, Poulton J, Narendra DP. OMA1 mediates local and global stress responses against protein misfolding in CHCHD10 mitochondrial myopathy. J Clin Invest 2022; 132:157504. [PMID: 35700042 PMCID: PMC9282932 DOI: 10.1172/jci157504] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 06/07/2022] [Indexed: 11/21/2022] Open
Abstract
Mitochondrial stress triggers a response in the cell’s mitochondria and nucleus, but how these stress responses are coordinated in vivo is poorly understood. Here, we characterize a family with myopathy caused by a dominant p.G58R mutation in the mitochondrial protein CHCHD10. To understand the disease etiology, we developed a knockin (KI) mouse model and found that mutant CHCHD10 aggregated in affected tissues, applying a toxic protein stress to the inner mitochondrial membrane. Unexpectedly, the survival of CHCHD10-KI mice depended on a protective stress response mediated by the mitochondrial metalloendopeptidase OMA1. The OMA1 stress response acted both locally within mitochondria, causing mitochondrial fragmentation, and signaled outside the mitochondria, activating the integrated stress response through cleavage of DAP3-binding cell death enhancer 1 (DELE1). We additionally identified an isoform switch in the terminal complex of the electron transport chain as a component of this response. Our results demonstrate that OMA1 was critical for neonatal survival conditionally in the setting of inner mitochondrial membrane stress, coordinating local and global stress responses to reshape the mitochondrial network and proteome.
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Affiliation(s)
- Mario K Shammas
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, United States of America
| | - Xiaoping Huang
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, United States of America
| | - Beverly P Wu
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, United States of America
| | - Evelyn Fessler
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Insung Song
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, United States of America
| | - Nicholas P Randolph
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, United States of America
| | - Yan Li
- Proteomics Core Facility, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, United States of America
| | - Christopher Ke Bleck
- Electron Microscopy Core Facility, National Heart, Lung, and Blood Institute, Bethesda, United States of America
| | - Danielle A Springer
- Mouse Phenotyping Core, National Heart, Lung, and Blood Institute, Bethesda, United States of America
| | - Carl Fratter
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Ines A Barbosa
- Department of Medical and Molecular Genetics, King's College London, London, United Kingdom
| | | | - Pedro M Quirós
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Oviedo, Spain
| | - Carlos Lopez-Otin
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Oviedo, Spain
| | - Lucas T Jae
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Joanna Poulton
- Nuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, United Kingdom
| | - Derek P Narendra
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, United States of America
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2
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Yamada T, Murata D, Kleiner DE, Anders R, Rosenberg AZ, Kaplan J, Hamilton JP, Aghajan M, Levi M, Wang NY, Dawson TM, Yanagawa T, Powers AF, Iijima M, Sesaki H. Prevention and regression of megamitochondria and steatosis by blocking mitochondrial fusion in the liver. iScience 2022; 25:103996. [PMID: 35310936 PMCID: PMC8927900 DOI: 10.1016/j.isci.2022.103996] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 01/06/2022] [Accepted: 02/24/2022] [Indexed: 02/07/2023] Open
Abstract
Non-alcoholic steatohepatitis (NASH) is a most common chronic liver disease that is manifested by steatosis, inflammation, fibrosis, and tissue damage. Hepatocytes produce giant mitochondria termed megamitochondria in patients with NASH. It has been shown that gene knockout of OPA1, a mitochondrial dynamin-related GTPase that mediates mitochondrial fusion, prevents megamitochondria formation and liver damage in a NASH mouse model induced by a methionine-choline-deficient (MCD) diet. However, it is unknown whether blocking mitochondrial fusion mitigates NASH pathologies. Here, we acutely depleted OPA1 using antisense oligonucleotides in the NASH mouse model before or after megamitochondria formation. When OPA1 ASOs were applied at the disease onset, they effectively prevented megamitochondria formation and liver pathologies in the MCD model. Notably, even when applied after mice robustly developed NASH pathologies, OPA1 targeting effectively regressed megamitochondria and the disease phenotypes. Thus, our data show the efficacy of mitochondrial dynamics as a unique therapy for megamitochondria-associated liver disease. A NASH mouse model induced by the MCD diet produces megamitochondria in hepatocytes Megamitochondria decrease mitophagy Blocking mitochondrial fusion by targeting OPA1 mitigates NASH pathologies Targeting OPA1 improves the SDH activity in the MCD model
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3
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Garcia DA, Powers AF, Bell TA, Guo S, Aghajan M. Antisense Oligonucleotide-Mediated Silencing of Mitochondrial Fusion and Fission Factors Modulates Mitochondrial Dynamics and Rescues Mitochondrial Dysfunction. Nucleic Acid Ther 2021; 32:51-65. [PMID: 34698563 PMCID: PMC8817704 DOI: 10.1089/nat.2021.0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Mitochondria are highly dynamic organelles that produce ATP and maintain metabolic, catabolic, and redox homeostasis. Mitochondria owe this dynamic nature to their constant fission and fusion—processes that are regulated, in part, by fusion factors (MFN1 and MFN2) and fission factors (DRP1, FIS1, MFF, MIEF1, MIEF2) located on the outer mitochondrial membrane. While mitochondrial fusion and fission are known to influence mitochondrial morphology and function, a key question is whether rebalancing mitochondrial morphology can ameliorate mitochondrial dysfunction in the context of mitochondrial pathology. In this study, we used antisense oligonucleotides (ASOs) to systematically evaluate the effects of fusion and fission factors in vitro. Free uptake by cells of fusion or fission factor ASOs caused robust decreases in target gene expression and altered a variety of mitochondrial parameters, including mitochondrial size and respiration, which were dose dependent. In Mfn1 knockout mouse embryonic fibroblasts (MEFs) and MFN2-R94Q (Charcot-Marie-Tooth Type 2 Disease-associated mutation) MEFs, two cellular models of mitochondrial dysfunction, we found that ASO-mediated silencing of only Drp1 restored mitochondrial morphology and enhanced mitochondrial respiration. Together, these data demonstrate in vitro proof-of-concept for rebalancing mitochondrial morphology to rescue function using ASOs and suggest that ASO-mediated modulation of mitochondrial dynamics may be a viable therapeutic approach to restore mitochondrial homeostasis in diseases driven by mitochondrial dysfunction.
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Affiliation(s)
| | | | - Thomas A Bell
- Ionis Pharmaceuticals, Inc., Carlsbad, California,, USA
| | - Shuling Guo
- Ionis Pharmaceuticals, Inc., Carlsbad, California,, USA
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4
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Ochaba J, Powers AF, Tremble KA, Greenlee S, Post NM, Matson JE, MacLeod AR, Guo S, Aghajan M. A novel and translational role for autophagy in antisense oligonucleotide trafficking and activity. Nucleic Acids Res 2020; 47:11284-11303. [PMID: 31612951 PMCID: PMC6868497 DOI: 10.1093/nar/gkz901] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 09/13/2019] [Accepted: 10/01/2019] [Indexed: 01/26/2023] Open
Abstract
Endocytosis is a mechanism by which cells sense their environment and internalize various nutrients, growth factors and signaling molecules. This process initiates at the plasma membrane, converges with autophagy, and terminates at the lysosome. It is well-established that cellular uptake of antisense oligonucleotides (ASOs) proceeds through the endocytic pathway; however, only a small fraction escapes endosomal trafficking while the majority are rendered inactive in the lysosome. Since these pathways converge and share common molecular machinery, it is unclear if autophagy-related trafficking participates in ASO uptake or whether modulation of autophagy affects ASO activity and localization. To address these questions, we investigated the effects of autophagy modulation on ASO activity in cells and mice. We found that enhancing autophagy through small-molecule mTOR inhibition, serum-starvation/fasting, and ketogenic diet, increased ASO-mediated target reduction in vitro and in vivo. Additionally, autophagy activation enhanced the localization of ASOs into autophagosomes without altering intracellular concentrations or trafficking to other compartments. These results support a novel role for autophagy and the autophagosome as a previously unidentified compartment that participates in and contributes to enhanced ASO activity. Further, we demonstrate non-chemical methods to enhance autophagy and subsequent ASO activity using translatable approaches such as fasting or ketogenic diet.
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Affiliation(s)
- Joseph Ochaba
- Ionis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
| | | | | | | | - Noah M Post
- Ionis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
| | - John E Matson
- Ionis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
| | | | - Shuling Guo
- Ionis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
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5
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Shen W, Taylor B, Jin Q, Nguyen-Tran V, Meeusen S, Zhang YQ, Kamireddy A, Swafford A, Powers AF, Walker J, Lamb J, Bursalaya B, DiDonato M, Harb G, Qiu M, Filippi CM, Deaton L, Turk CN, Suarez-Pinzon WL, Liu Y, Hao X, Mo T, Yan S, Li J, Herman AE, Hering BJ, Wu T, Martin Seidel H, McNamara P, Glynne R, Laffitte B. Inhibition of DYRK1A and GSK3B induces human β-cell proliferation. Nat Commun 2015; 6:8372. [PMID: 26496802 PMCID: PMC4639830 DOI: 10.1038/ncomms9372] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Accepted: 08/14/2015] [Indexed: 12/28/2022] Open
Abstract
Insufficient pancreatic β-cell mass or function results in diabetes mellitus. While significant progress has been made in regulating insulin secretion from β-cells in diabetic patients, no pharmacological agents have been described that increase β-cell replication in humans. Here we report aminopyrazine compounds that stimulate robust β-cell proliferation in adult primary islets, most likely as a result of combined inhibition of DYRK1A and GSK3B. Aminopyrazine-treated human islets retain functionality in vitro and after transplantation into diabetic mice. Oral dosing of these compounds in diabetic mice induces β-cell proliferation, increases β-cell mass and insulin content, and improves glycaemic control. Biochemical, genetic and cell biology data point to Dyrk1a as the key molecular target. This study supports the feasibility of treating diabetes with an oral therapy to restore β-cell mass, and highlights a tractable pathway for future drug discovery efforts.
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Affiliation(s)
- Weijun Shen
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Brandon Taylor
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Qihui Jin
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Van Nguyen-Tran
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Shelly Meeusen
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - You-Qing Zhang
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Anwesh Kamireddy
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Austin Swafford
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Andrew F. Powers
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - John Walker
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - John Lamb
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Badry Bursalaya
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Michael DiDonato
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - George Harb
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Minhua Qiu
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Christophe M. Filippi
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Lisa Deaton
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Carolina N. Turk
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Wilma L. Suarez-Pinzon
- Department of Surgery and Schulze Diabetes Institute, University of Minnesota, 420 Delaware Street SE, Minneapolis, Minnesota 55455, USA
| | - Yahu Liu
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Xueshi Hao
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Tingting Mo
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Shanshan Yan
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Jing Li
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Ann E. Herman
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Bernhard J. Hering
- Department of Surgery and Schulze Diabetes Institute, University of Minnesota, 420 Delaware Street SE, Minneapolis, Minnesota 55455, USA
| | - Tom Wu
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - H. Martin Seidel
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Peter McNamara
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Richard Glynne
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
| | - Bryan Laffitte
- Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, California 92121, USA
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6
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Abstract
Many proteins and protein complexes perform sophisticated, regulated functions in vivo. Many of these functions can be recapitulated using in vitro reconstitution, which serves as a means to establish unambiguous cause-effect relationships, for example, between a protein and its phosphorylating kinase. Here, we describe a protocol to purify kinetochores, the protein complexes that attach chromosomes to microtubules during mitosis, and quantitatively assay their microtubule-binding characteristics. Our assays, based on DIC imaging and laser trapping microscopy, are used to measure the attachment of microtubules to kinetochores and the load-bearing capabilities of those attachments. These assays provide a platform for studying kinase disruption of kinetochore-microtubule attachments, which is believed to be critical for correcting erroneous kinetochore-spindle attachments and thereby avoiding chromosome missegregation. The principles of our approach should be extensible to studies of a wide range of force-bearing interactions in biology.
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Affiliation(s)
- Jonathan W Driver
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington, USA
| | - Andrew F Powers
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington, USA
| | - Krishna K Sarangapani
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington, USA
| | - Sue Biggins
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington, USA
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7
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Asbury CL, Sarangapani KK, Akiyoshi B, Duggan N, Driver JW, Arellano-Santoyo H, Powers AF, Biggins S. How Kinetochores Promote Accuracy in Mitosis: Tension, Phosphoregulation, and the Chinese ‘Finger Trap’ Effect. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.1219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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8
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Asbury CL, Akiyoshi B, Sarangapani KK, Powers AF, Nelson CR, Reichow SL, Gonen T, Ranish JA, Biggins S. Tension Directly Stabilizes Reconstituted Kinetochore-Microtubule Attachments. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.3099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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9
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Franck AD, Powers AF, Gestaut DR, Davis TN, Asbury CL. Direct physical study of kinetochore-microtubule interactions by reconstitution and interrogation with an optical force clamp. Methods 2010; 51:242-50. [PMID: 20096784 PMCID: PMC2884078 DOI: 10.1016/j.ymeth.2010.01.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 01/14/2010] [Indexed: 02/01/2023] Open
Abstract
We detail our use of computer-controlled optical traps to study interactions between kinetochore components and dynamic microtubules. Over the last two decades optical traps have helped uncover the working principles of conventional molecular motors, such as kinesin and dynein, but only recently have they been applied to study kinetochore function. The most useful traps combine sensitive position detectors and servo-control, allowing them to be operated as force clamps that maintain constant loads on objects as they move. Our instrument, which is among the simplest designs that permits force clamping, relies on a computer-controlled piezoelectric stage and a single laser for trapping and position detection. We apply it in motility assays where beads coated with pure microtubule-binding kinetochore components are attached to the tips of individual dynamic microtubules. Like kinetochores in vivo, the beads remain tip-attached, undergoing movements coupled to filament assembly and disassembly. The force clamp provides many benefits over instruments that lack feedback control. It allows tension to be applied continuously during both assembly- and disassembly-driven movement, providing a close match to the physiological situation. It also enables tracking with high resolution, and simplifies data interpretation by eliminating artifacts due to molecular compliance. The formation of persistent, load-bearing attachments to dynamic microtubule tips is fundamental to all kinetochore activities. Our direct, physical study of kinetochore-microtubule coupling may therefore furnish insights into many vital kinetochore functions, including correction of aberrant attachments and generation of the 'wait-anaphase' signals that delay mitosis until all kinetochores are properly attached.
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Affiliation(s)
- Andrew D. Franck
- Department of Physiology and Biophysics, Box 357290, University of Washington, Seattle WA 98195
| | - Andrew F. Powers
- Department of Physiology and Biophysics, Box 357290, University of Washington, Seattle WA 98195
| | - Daniel R. Gestaut
- Department of Biochemistry, Box 357350, University of Washington, Seattle WA 98195
| | - Trisha N. Davis
- Department of Biochemistry, Box 357350, University of Washington, Seattle WA 98195
| | - Charles L. Asbury
- Department of Physiology and Biophysics, Box 357290, University of Washington, Seattle WA 98195
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10
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Powers AF, Franck AD, Gestaut DR, Cooper J, Gracyzk B, Wei RR, Wordeman L, Davis TN, Asbury CL. The Ndc80 kinetochore complex forms load-bearing attachments to dynamic microtubule tips via biased diffusion. Cell 2009; 136:865-75. [PMID: 19269365 DOI: 10.1016/j.cell.2008.12.045] [Citation(s) in RCA: 220] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 10/29/2008] [Accepted: 12/30/2008] [Indexed: 11/30/2022]
Abstract
Kinetochores couple chromosomes to the assembling and disassembling tips of microtubules, a dynamic behavior that is fundamental to mitosis in all eukaryotes but poorly understood. Genetic, biochemical, and structural studies implicate the Ndc80 complex as a direct point of contact between kinetochores and microtubules, but these approaches provide only a static view. Here, using techniques for manipulating and tracking individual molecules in vitro, we demonstrate that the Ndc80 complex is capable of forming the dynamic, load-bearing attachments to assembling and disassembling tips required for coupling in vivo. We also establish that Ndc80-based coupling likely occurs through a biased diffusion mechanism and that this activity is conserved from yeast to humans. Our findings demonstrate how an ensemble of Ndc80 complexes may provide the combination of plasticity and strength that allows kinetochores to maintain load-bearing tip attachments during both microtubule assembly and disassembly.
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Affiliation(s)
- Andrew F Powers
- Department of Physiology and Biophysics, University of Washington, Seattle, 98195, USA
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11
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Franck AD, Powers AF, Gestaut DR, Cooper J, Gracyzk B, Wei RR, Wordeman L, Davis TN, Asbury CL. Reconstitution Of Microtubule-driven Movement and Force Production by the Ndc80 Kinetochore Complex. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.3744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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12
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Franck AD, Powers AF, Gestaut DR, Gonen T, Davis TN, Asbury CL. Tension applied through the Dam1 complex promotes microtubule elongation providing a direct mechanism for length control in mitosis. Nat Cell Biol 2007; 9:832-7. [PMID: 17572669 PMCID: PMC2680956 DOI: 10.1038/ncb1609] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Accepted: 05/24/2007] [Indexed: 12/11/2022]
Abstract
In dividing cells, kinetochores couple chromosomes to the tips of growing and shortening microtubule fibres and tension at the kinetochore-microtubule interface promotes fibre elongation. Tension-dependent microtubule fibre elongation is thought to be essential for coordinating chromosome alignment and separation, but the mechanism underlying this effect is unknown. Using optical tweezers, we applied tension to a model of the kinetochore-microtubule interface composed of the yeast Dam1 complex bound to individual dynamic microtubule tips. Higher tension decreased the likelihood that growing tips would begin to shorten, slowed shortening, and increased the likelihood that shortening tips would resume growth. These effects are similar to the effects of tension on kinetochore-attached microtubule fibres in many cell types, suggesting that we have reconstituted a direct mechanism for microtubule-length control in mitosis.
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Affiliation(s)
- Andrew D Franck
- Department of Physiology, University of Washington, Seattle, WA 98195, USA
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13
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Mullick AE, Powers AF, Kota RS, Tetali SD, Eiserich JP, Rutledge JC. Apolipoprotein E3- and Nitric Oxide–Dependent Modulation of Endothelial Cell Inflammatory Responses. Arterioscler Thromb Vasc Biol 2007; 27:339-45. [PMID: 17138935 DOI: 10.1161/01.atv.0000253947.70438.99] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Objective—
Although apolipoprotein E3 (apoE3) is known to be atheroprotective, its mechanisms of protection in endothelial cells remain unclear.
Methods and Results—
Cultured human aortic endothelial cells were stimulated with tumor necrosis factor (TNF)-α in the presence of human recombinant apoE3 solubilized in dimyristoyl phosphatidylcholine liposomes. Using flow cytometry and real-time polymerase chain reaction, a significant increase of inflammatory cell adhesion proteins (vascular cell adhesion molecule-1 and E-Selectin), and MCP-1, interleukin-8, and intercellular adhesion molecule-1 gene expression was observed within 5 hours of TNF-α exposure, which was markedly attenuated in cells coincubated with apoE3. Treatment with apoE4 resulted in increased inflammatory gene expression relative to either TNF treatment alone or TNF + apoE3 treatment. NO synthase inhibition experiments demonstrated NO to be an active participant in the actions of both TNF and apoE. To clarify the role of NO, dose-response experiments were performed with 0.03 to 300 μmol/L DEA-NONOate. Using flow cytometry and real-time polymerase chain reaction, a modulatory role of NO in TNF-induced endothelial cell activation was observed.
Conclusions—
These data suggest a role of vascular wall apoE3 to balance the intracellular redox state in injured endothelial cells via NO-dependent pathways.
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Affiliation(s)
- Adam E Mullick
- Department of Internal Medicine, Division of Endocrinology, Clinical Nutrition, and Vascular Medicine, School of Medicine, University of California, Davis, USA.
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14
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Asbury CL, Gestaut DR, Powers AF, Franck AD, Davis TN. The Dam1 kinetochore complex harnesses microtubule dynamics to produce force and movement. Proc Natl Acad Sci U S A 2006; 103:9873-8. [PMID: 16777964 PMCID: PMC1502546 DOI: 10.1073/pnas.0602249103] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kinetochores remain attached to microtubule (MT) tips during mitosis even as the tips assemble and disassemble under their grip, allowing filament dynamics to produce force and move chromosomes. The specific proteins that mediate tip attachment are uncertain, and the mechanism of MT-dependent force production is unknown. Recent work suggests that the Dam1 complex, an essential component of kinetochores in yeast, may contribute directly to kinetochore-MT attachment and force production, perhaps by forming a sliding ring encircling the MT. To test these hypotheses, we developed an in vitro motility assay where beads coated with pure recombinant Dam1 complex were bound to the tips of individual dynamic MTs. The Dam1-coated beads remained tip-bound and underwent assembly- and disassembly-driven movement over approximately 3 microm, comparable to chromosome displacements in vivo. Dam1-based attachments to assembling tips were robust, supporting 0.5-3 pN of tension applied with a feedback-controlled optical trap as the MTs lengthened approximately 1 microm. The attachments also harnessed energy from MT disassembly to generate movement against tension. Reversing the direction of force (i.e., switching to compressive force) caused the attachments to disengage the tip and slide over the filament, but sliding was blocked by areas where the MT was anchored to a coverslip, consistent with a coupling structure encircling the filament. Our findings demonstrate how the Dam1 complex may contribute directly to MT-driven chromosome movement.
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Affiliation(s)
- Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA.
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Fitch RM, Rutledge JC, Wang YX, Powers AF, Tseng JL, Clary T, Rubanyi GM. Synergistic effect of angiotensin II and nitric oxide synthase inhibitor in increasing aortic stiffness in mice. Am J Physiol Heart Circ Physiol 2006; 290:H1190-8. [PMID: 16272204 DOI: 10.1152/ajpheart.00327.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although they are implicated on their own as risk factors for cardiovascular disease, the potential link between nitric oxide (NO) deficiency, ANG II, and vascular stiffening has not been tested before. We evaluated the role of chronic ANG II treatment and NO deficiency, alone and in combination, on aortic stiffness in mice and tested parameters contributing to increases in active or passive components of vascular stiffness, including blood pressure, vascular smooth muscle contractility, and extracellular matrix components. Untreated (control) mice and mice treated with a NO synthase (NOS) inhibitor [ Nω-nitro-l-arginine methyl ester (l-NAME), 0.5 g/l] were implanted with osmotic minipumps delivering ANG II (500 ng·kg−1·min−1) for 28 days. Aortic stiffness was then measured in vivo by pulse wave velocity (PWV) and ex vivo by load-strain analysis to obtain values of maximal passive stiffness (MPS). Blood pressure and aortic contractility ex vivo were measured. ANG II treatment or NOS inhibition with l-NAME did not independently increase vascular stiffness; however, the combined treatments worked synergistically to increase PWV and MPS. The combined treatments of ANG II + l-NAME also significantly increased aortic wall collagen content while decreasing elastin. These novel results suggest that NO deficiency and ANG II act synergistically to increase aortic stiffness in mice predominantly via changes in aortic wall collagen/elastin ratio.
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Affiliation(s)
- Richard M Fitch
- Department of Pharmacology, Berlex Biosciences, 2600 Hilltop Dr., Richmond, California 94804-0099, USA
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Tham DM, Martin-McNulty B, Wang YX, Da Cunha V, Wilson DW, Athanassious CN, Powers AF, Sullivan ME, Rutledge JC. Angiotensin II injures the arterial wall causing increased aortic stiffening in apolipoprotein E-deficient mice. Am J Physiol Regul Integr Comp Physiol 2002; 283:R1442-9. [PMID: 12388474 DOI: 10.1152/ajpregu.00295.2002] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cardiovascular diseases, such as atherosclerosis and hypertension, are associated with arterial stiffening. Previous studies showed that ANG II exacerbated atherosclerosis and induced hypertension and aneurysm formation in apolipoprotein E-deficient (apoE-KO) mice. The aim of the present study was to examine the effects of chronic treatment of ANG II on the arterial elastic properties in apoE-KO mice. We hypothesized that ANG II will injure the arterial wall resulting in increased arterial stiffening. Male apoE-KO mice were infused with either ANG II (1.44 mg. kg(-1). day(-1)) or vehicle (PBS) for 30 days. ANG II treatment accelerated atherosclerosis in the carotid artery by sixfold (P < 0.001) and increased blood pressure by 30% (P < 0.05). Additionally, our data demonstrated that ANG II increased arterial stiffening using both in vivo and in vitro methods. ANG II significantly increased pulse wave velocity by 36% (P < 0.01) and decreased arterial elasticity as demonstrated by a more than 900% increase in maximal stiffening (high strain Young's modulus) compared with vehicle (P < 0.05). These functional changes were correlated with morphological and biochemical changes as demonstrated by an increase in collagen content (60%), a decrease in elastin content (74%), and breaks in the internal elastic lamina in the aortic wall. In addition, endothelium-independent vasorelaxation to sodium nitroprusside was impaired in the aortic rings of ANG II-treated mice compared with vehicle. Thus, the present data indicate that ANG II injures the artery wall in multiple ways and arterial stiffening may be a common outcome of ANG II-induced arterial damage.
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Affiliation(s)
- Doris M Tham
- Department of Internal Medicine, School of Medicine, University of California at Davis, Davis 95616, USA.
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