1
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Mays A, Byars-Winston A, Hinton A, Marshall AG, Kirabo A, August A, Marlin BJ, Riggs B, Tolbert B, Wanjalla C, Womack C, Evans CS, Barnes C, Starbird C, Williams C, Reynolds C, Taabazuing C, Cameron CE, Murray DD, Applewhite D, Morton DJ, Lee D, Williams DW, Lynch D, Brady D, Lynch E, Rutaganira FUN, Silva GM, Shuler H, Saboor IA, Davis J, Dzirasa K, Hammonds-Odie L, Reyes L, Sweetwyne MT, McReynolds MR, Johnson MDL, Smith NA, Pittman N, Ajijola OA, Smith Q, Robinson RAS, Lewis SC, Murray SA, Black S, Neal SE, Andrisse S, Townsend S, Damo SM, Griffith TN, Lambert WM, Clemons WM. Juneteenth in STEMM and the barriers to equitable science. Cell 2023; 186:2510-2517. [PMID: 37295396 DOI: 10.1016/j.cell.2023.05.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 05/06/2023] [Accepted: 05/12/2023] [Indexed: 06/12/2023]
Abstract
We are 52 Black scientists. Here, we establish the context of Juneteenth in STEMM and discuss the barriers Black scientists face, the struggles they endure, and the lack of recognition they receive. We review racism's history in science and provide institutional-level solutions to reduce the burdens on Black scientists.
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Affiliation(s)
- Alfred Mays
- Burroughs Wellcome Fund, Durham, NC 27709, USA
| | - Angela Byars-Winston
- Department of Medicine, Institute for Diversity Science, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Antentor Hinton
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
| | - Andrea G Marshall
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Annet Kirabo
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA; Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Vanderbilt University, Nashville, TN 37232, USA
| | - Avery August
- Department of Microbiology and Immunology, Cornell University College of Veterinary Medicine, Ithaca, NY 14853, USA
| | - Bianca J Marlin
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Department of Psychology, Columbia University, New York, NY 10032, USA; Department of Neuroscience, Columbia University, New York, NY 10027, USA
| | - Blake Riggs
- Department of Biology, San Francisco State University, San Francisco, CA 94132, USA
| | - Blanton Tolbert
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Celestine Wanjalla
- Division of Infectious Diseases, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Chad Womack
- National STEM Programs and Tech Initiatives at the education philanthropic charity, UNCF, Washington, DC 20001, USA
| | - Chantell S Evans
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27708, USA
| | | | - Chrystal Starbird
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Clintoria Williams
- Department of Neuroscience, Cell Biology & Physiology, College of Science and Mathematics, Wright State University Boonshoft School of Medicine, Dayton, OH 45435, USA
| | - Corey Reynolds
- Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Mouse Phenotyping Core, Baylor College of Medicine, Houston, TX 77030, USA
| | - Cornelius Taabazuing
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Craig E Cameron
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Debra D Murray
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Derrick J Morton
- Department of Biological Sciences, University of Southern California Los Angeles, Los Angeles, CA 90089, USA
| | - Dexter Lee
- Department of Physiology and Biophysics, Howard University College of Medicine, Washington, DC 20059, USA
| | - Dionna W Williams
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Donald Lynch
- Department of Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH, USA
| | - Donita Brady
- Department of Cancer Biology, University of Pennsylvania, Philadelphia, PA 19104, USA; Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA 19104, USA; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Erin Lynch
- University of Michigan Health System, Ann Arbor, MI 48109, USA
| | - Florentine U N Rutaganira
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Gustavo M Silva
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Haysetta Shuler
- Winston-Salem State University Department of Biological Sciences, Winston-Salem, NC 27110, USA
| | - Ishmail Abdus Saboor
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
| | - Jamaine Davis
- Department of Biochemistry, Cancer Biology, Neuroscience, Pharmacology, Meharry Medical College, Nashville, TN 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Kafui Dzirasa
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA; Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710, USA; Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
| | - Latanya Hammonds-Odie
- Department of Biological Sciences before School of Science and Technology, Georgia Gwinnett College, Lawrenceville, GA 30043, USA
| | - Loretta Reyes
- Division of Pediatric Nephrology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Mariya T Sweetwyne
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
| | - Melanie R McReynolds
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA; Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Michael D L Johnson
- Department of Immunobiology, University of Arizona, Tucson, AZ 85724, USA; BIO5 Institute, University of Arizona, Tucson, AZ 85724, USA; Valley Fever Center for Excellence, University of Arizona, Tucson, AZ, USA
| | - Nathan A Smith
- Del Monte Institute for Neuroscience, Department of Neuroscience, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Nikea Pittman
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Olujimi A Ajijola
- UCLA Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Quinton Smith
- School of Engineering, University of California, Irvine, CA 92697-3975, USA
| | - Renã A S Robinson
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Samantha C Lewis
- Department of Molecular and Cellular Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Sandra A Murray
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 52013, USA.
| | - Sherilynn Black
- Office of the Provost and Division of Medical Education, Duke University, Durham, NC 27708, USA.
| | - Sonya E Neal
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Stanley Andrisse
- Department of Physiology and Biophysics, Howard University College of Medicine, Washington, DC 20059, USA; Department of Pediatrics, School of Medicine, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Steven Townsend
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Steven M Damo
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA; Department of Life and Physical Sciences, Fisk University, Nashville, TN 37208, USA.
| | - Theanne N Griffith
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA 95616, USA
| | - W Marcus Lambert
- Department of Epidemiology and Biostatistics, SUNY Downstate Health Sciences University, New York, NY 11203, USA
| | - William M Clemons
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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Bhaduri S, Aguayo A, Ohno Y, Proietto M, Jung J, Wang I, Kandel R, Singh N, Ibrahim I, Fulzele A, Bennett EJ, Kihara A, Neal SE. An ERAD-independent role for rhomboid pseudoprotease Dfm1 in mediating sphingolipid homeostasis. EMBO J 2023; 42:e112275. [PMID: 36350249 PMCID: PMC9929635 DOI: 10.15252/embj.2022112275] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/20/2022] [Accepted: 10/19/2022] [Indexed: 11/11/2022] Open
Abstract
Nearly one-third of nascent proteins are initially targeted to the endoplasmic reticulum (ER), where they are correctly folded and assembled before being delivered to their final cellular destinations. To prevent the accumulation of misfolded membrane proteins, ER-associated degradation (ERAD) removes these client proteins from the ER membrane to the cytosol in a process known as retrotranslocation. Our previous work demonstrated that rhomboid pseudoprotease Dfm1 is involved in the retrotranslocation of ubiquitinated membrane integral ERAD substrates. Herein, we found that Dfm1 associates with the SPOTS complex, which is composed of serine palmitoyltransferase (SPT) enzymes and accessory components that are critical for catalyzing the first rate-limiting step of the sphingolipid biosynthesis pathway. Furthermore, Dfm1 employs an ERAD-independent role for facilitating the ER export and endosome- and Golgi-associated degradation (EGAD) of Orm2, which is a major antagonist of SPT activity. Given that the accumulation of human Orm2 homologs, ORMDLs, is associated with various pathologies, our study serves as a molecular foothold for understanding how dysregulation of sphingolipid metabolism leads to various diseases.
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Affiliation(s)
- Satarupa Bhaduri
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Analine Aguayo
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Yusuke Ohno
- Laboratory of Biochemistry, Faculty of Pharmaceutical SciencesHokkaido UniversitySapporoJapan
| | - Marco Proietto
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Jasmine Jung
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Isabel Wang
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Rachel Kandel
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Narinderbir Singh
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Ikran Ibrahim
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Amit Fulzele
- Present address:
Institute of Molecular BiologyMainzGermany
| | - Eric J Bennett
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Akio Kihara
- Laboratory of Biochemistry, Faculty of Pharmaceutical SciencesHokkaido UniversitySapporoJapan
| | - Sonya E Neal
- Department of Cell and Developmental Biology, School of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
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3
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Bhaduri S, Scott NA, Neal SE. The Role of the Rhomboid Superfamily in ER Protein Quality Control: From Mechanisms and Functions to Diseases. Cold Spring Harb Perspect Biol 2023; 15:a041248. [PMID: 35940905 PMCID: PMC9899648 DOI: 10.1101/cshperspect.a041248] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 02/04/2023]
Abstract
The endoplasmic reticulum (ER) is an essential organelle in eukaryotic cells and is a major site for protein folding, modification, and lipid synthesis. Perturbations within the ER, such as protein misfolding and high demand for protein folding, lead to dysregulation of the ER protein quality control network and ER stress. Recently, the rhomboid superfamily has emerged as a critical player in ER protein quality control because it has diverse cellular functions, including ER-associated degradation (ERAD), endosome Golgi-associated degradation (EGAD), and ER preemptive quality control (ERpQC). This breadth of function both illustrates the importance of the rhomboid superfamily in health and diseases and emphasizes the necessity of understanding their mechanisms of action. Because dysregulation of rhomboid proteins has been implicated in various diseases, such as neurological disorders and cancers, they represent promising potential therapeutic drug targets. This review provides a comprehensive account of the various roles of rhomboid proteins in the context of ER protein quality control and discusses their significance in health and disease.
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Affiliation(s)
- Satarupa Bhaduri
- School of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093, USA
| | - Nicola A Scott
- School of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093, USA
| | - Sonya E Neal
- School of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California 92093, USA
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4
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Kandel R, Jung J, Syau D, Kuo T, Songster L, Horn C, Chapman C, Aguayo A, Duttke S, Benner C, Neal SE. Yeast derlin Dfm1 employs a chaperone-like function to resolve misfolded membrane protein stress. PLoS Biol 2023; 21:e3001950. [PMID: 36689475 PMCID: PMC9894555 DOI: 10.1371/journal.pbio.3001950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 02/02/2023] [Accepted: 12/07/2022] [Indexed: 01/24/2023] Open
Abstract
Protein aggregates are a common feature of diseased and aged cells. Membrane proteins comprise a quarter of the proteome, and yet, it is not well understood how aggregation of membrane proteins is regulated and what effects these aggregates can have on cellular health. We have determined in yeast that the derlin Dfm1 has a chaperone-like activity that influences misfolded membrane protein aggregation. We establish that this function of Dfm1 does not require recruitment of the ATPase Cdc48 and it is distinct from Dfm1's previously identified function in dislocating misfolded membrane proteins from the endoplasmic reticulum (ER) to the cytosol for degradation. Additionally, we assess the cellular impacts of misfolded membrane proteins in the absence of Dfm1 and determine that misfolded membrane proteins are toxic to cells in the absence of Dfm1 and cause disruptions to proteasomal and ubiquitin homeostasis.
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Affiliation(s)
- Rachel Kandel
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | - Jasmine Jung
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | - Della Syau
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | - Tiffany Kuo
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | - Livia Songster
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | - Casey Horn
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | - Claire Chapman
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | - Analine Aguayo
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | - Sascha Duttke
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, Washington, United States of America
| | - Christopher Benner
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Sonya E. Neal
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
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5
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Neal SE. The role of rhomboid pseudoproteases in protecting the membrane proteome. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.0i139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sonya E. Neal
- Division of Biological SciencesUniversity of California San DiegoLa JollaCA
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6
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Nejatfard A, Wauer N, Bhaduri S, Conn A, Gourkanti S, Singh N, Kuo T, Kandel R, Amaro RE, Neal SE. Derlin rhomboid pseudoproteases employ substrate engagement and lipid distortion to enable the retrotranslocation of ERAD membrane substrates. Cell Rep 2022; 38:110578. [PMID: 35320719 DOI: 10.1016/j.celrep.2022.110578] [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: 11/16/2022] Open
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7
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Bhaduri S, Nejatfard A, Liu L, Patrick G, Strisovsky K, O'Donoghue A, Neal SE. An in vitro platform enables catalytic characterization of an intramembrane rhomboid protease. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.567] [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: 11/02/2022] Open
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8
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Nejatfard A, Wauer N, Bhaduri S, Conn A, Gourkanti S, Singh N, Kuo T, Kandel R, Amaro RE, Neal SE. Derlin rhomboid pseudoproteases employ substrate engagement and lipid distortion to enable the retrotranslocation of ERAD membrane substrates. Cell Rep 2021; 37:109840. [PMID: 34686332 PMCID: PMC8641752 DOI: 10.1016/j.celrep.2021.109840] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [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: 03/12/2021] [Revised: 07/19/2021] [Accepted: 09/27/2021] [Indexed: 01/13/2023] Open
Abstract
Nearly one-third of proteins are initially targeted to the endoplasmic reticulum (ER) membrane, where they are correctly folded and then delivered to their final cellular destinations. To prevent the accumulation of misfolded membrane proteins, ER-associated degradation (ERAD) moves these clients from the ER membrane to the cytosol, a process known as retrotranslocation. Our recent work in Saccharomyces cerevisiae reveals a derlin rhomboid pseudoprotease, Dfm1, is involved in the retrotranslocation of ubiquitinated ERAD membrane substrates. In this study, we identify conserved residues of Dfm1 that are critical for retrotranslocation. We find several retrotranslocation-deficient Loop 1 mutants that display impaired binding to membrane substrates. Furthermore, Dfm1 possesses lipid thinning function to facilitate in the removal of ER membrane substrates, and this feature is conserved in its human homolog, Derlin-1, further implicating that derlin-mediated retrotranslocation is a well-conserved process. ER-associated degradation is a conserved pathway of protein quality control that requires the retrotranslocation of ubiquitinated substrates from the ER to the cytoplasm for degradation. Nejatfard et al. show that derlin rhomboid pseudoproteases mediate the retrotranslocation of misfolded membrane substrates via a mechanism that is conserved from yeast to humans.
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Affiliation(s)
- Anahita Nejatfard
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Nicholas Wauer
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093, USA
| | - Satarupa Bhaduri
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Adam Conn
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Saroj Gourkanti
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Narinderbir Singh
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Tiffany Kuo
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Rachel Kandel
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Rommie E Amaro
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093, USA
| | - Sonya E Neal
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA.
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9
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Abstract
In S. cerevisiae, we identified rhomboid pseudoprotease Dfm1 as the major mediator for removing or retrotranslocating misfolded membrane substrates from the ER (endoplasmic reticulum). Long-standing challenges with rapid suppression of dfm1-null cells have limited the biochemical study of Dfm1's role in ER protein quality control. Here, we provide a protocol for the generation and handling of dfm1-null cells and procedures for studying normal vs. suppressive alternative retrotranslocation pathways. Our methods can be utilized to study other components involved in retrotranslocation. For complete information on the generation and use of this protocol, please refer to Neal et al. (2017, 2018); Neal et al. (2019); Neal et al. (2020).
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Affiliation(s)
- Satarupa Bhaduri
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Sonya E. Neal
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
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10
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Sam PN, Calzada E, Acoba MG, Zhao T, Watanabe Y, Nejatfard A, Trinidad JC, Shutt TE, Neal SE, Claypool SM. Impaired phosphatidylethanolamine metabolism activates a reversible stress response that detects and resolves mutant mitochondrial precursors. iScience 2021; 24:102196. [PMID: 33718843 PMCID: PMC7921845 DOI: 10.1016/j.isci.2021.102196] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 01/27/2021] [Accepted: 02/10/2021] [Indexed: 02/06/2023] Open
Abstract
Phosphatidylethanolamine (PE) made in mitochondria has long been recognized as an important precursor for phosphatidylcholine production that occurs in the endoplasmic reticulum (ER). Recently, the strict mitochondrial localization of the enzyme that makes PE in the mitochondrion, phosphatidylserine decarboxylase 1 (Psd1), was questioned. Since a dual localization of Psd1 to the ER would have far-reaching implications, we initiated our study to independently re-assess the subcellular distribution of Psd1. Our results support the unavoidable conclusion that the vast majority, if not all, of functional Psd1 resides in the mitochondrion. Through our efforts, we discovered that mutant forms of Psd1 that impair a self-processing step needed for it to become functional are dually localized to the ER when expressed in a PE-limiting environment. We conclude that severely impaired cellular PE metabolism provokes an ER-assisted adaptive response that is capable of identifying and resolving nonfunctional mitochondrial precursors. Functional Psd1, the enzyme that makes PE, is mitochondrial localized When cellular PE metabolism is impaired, mutant Psd1 is also targeted to the ER Mutant Psd1 targeted to the ER is ubiquitinated and rapidly degraded Impaired PE metabolism activates a reversible stress response
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Affiliation(s)
- Pingdewinde N. Sam
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Elizabeth Calzada
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michelle Grace Acoba
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Tian Zhao
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Yasunori Watanabe
- Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata, Yamagata 990-8560, Japan
| | - Anahita Nejatfard
- Division of Biological Sciences, The Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA
| | | | - Timothy E. Shutt
- Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata, Yamagata 990-8560, Japan
| | - Sonya E. Neal
- Division of Biological Sciences, The Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA
| | - Steven M. Claypool
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Corresponding author
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11
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Neal SE, Dabir DV, Wijaya J, Boon C, Koehler CM. Osm1 facilitates the transfer of electrons from Erv1 to fumarate in the redox-regulated import pathway in the mitochondrial intermembrane space. Mol Biol Cell 2017; 28:2773-2785. [PMID: 28814504 PMCID: PMC5638582 DOI: 10.1091/mbc.e16-10-0712] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 08/10/2017] [Accepted: 08/10/2017] [Indexed: 11/18/2022] Open
Abstract
Osm1 transfers electrons from fumarate to succinate and functions with Mia40 and Erv1 in the redox-regulated import pathway for proteins that form disulfide bonds in the mitochondrial intermembrane space. Expression of Osm1 and cytochrome c is reciprocally regulated, indicating that the cell has strategies to coordinate expression of terminal electron acceptors. Prokaryotes have aerobic and anaerobic electron acceptors for oxidative folding of periplasmic proteins. The mitochondrial intermembrane space has an analogous pathway with the oxidoreductase Mia40 and sulfhydryl oxidase Erv1, termed the mitochondrial intermembrane space assembly (MIA) pathway. The aerobic electron acceptors include oxygen and cytochrome c, but an acceptor that can function under anaerobic conditions has not been identified. Here we show that the fumarate reductase Osm1, which facilitates electron transfer from fumarate to succinate, fills this gap as a new electron acceptor. In addition to microsomes, Osm1 localizes to the mitochondrial intermembrane space and assembles with Erv1 in a complex. In reconstitution studies with reduced Tim13, Mia40, and Erv1, the addition of Osm1 and fumarate completes the disulfide exchange pathway that results in Tim13 oxidation. From in vitro import assays, mitochondria lacking Osm1 display decreased import of MIA substrates, Cmc1 and Tim10. Comparative reconstitution assays support that the Osm1/fumarate couple accepts electrons with similar efficiency to cytochrome c and that the cell has strategies to coordinate expression of the terminal electron acceptors. Thus Osm1/fumarate is a new electron acceptor couple in the mitochondrial intermembrane space that seems to function in both aerobic and anaerobic conditions.
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Affiliation(s)
- Sonya E Neal
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095
| | - Deepa V Dabir
- Department of Biology, Loyola Marymount University, Los Angeles, CA 90045
| | - Juwina Wijaya
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Cennyana Boon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Carla M Koehler
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095 .,Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095.,Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, CA 90095
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Neal SE, Dabir DV, Tienson HL, Horn DM, Glaeser K, Ogozalek Loo RR, Barrientos A, Koehler CM. Mia40 Protein Serves as an Electron Sink in the Mia40-Erv1 Import Pathway. J Biol Chem 2015; 290:20804-20814. [PMID: 26085103 DOI: 10.1074/jbc.m115.669440] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Indexed: 11/06/2022] Open
Abstract
A redox-regulated import pathway consisting of Mia40 and Erv1 mediates the import of cysteine-rich proteins into the mitochondrial intermembrane space. Mia40 is the oxidoreductase that inserts two disulfide bonds into the substrate simultaneously. However, Mia40 has one redox-active cysteine pair, resulting in ambiguity about how Mia40 accepts numerous electrons during substrate oxidation. In this study, we have addressed the oxidation of Tim13 in vitro and in organello. Reductants such as glutathione and ascorbate inhibited both the oxidation of the substrate Tim13 in vitro and the import of Tim13 and Cmc1 into isolated mitochondria. In addition, a ternary complex consisting of Erv1, Mia40, and substrate, linked by disulfide bonds, was not detected in vitro. Instead, Mia40 accepted six electrons from substrates, and this fully reduced Mia40 was sensitive to protease, indicative of conformational changes in the structure. Mia40 in mitochondria from the erv1-101 mutant was also trapped in a completely reduced state, demonstrating that Mia40 can accept up to six electrons as substrates are imported. Therefore, these studies support that Mia40 functions as an electron sink to facilitate the insertion of two disulfide bonds into substrates.
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Affiliation(s)
- Sonya E Neal
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095
| | - Deepa V Dabir
- Department of Biology, Loyola Marymount University, Los Angeles, California 90045
| | - Heather L Tienson
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095
| | - Darryl M Horn
- Department of Neurology and Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida 33136
| | - Kathrin Glaeser
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095
| | - Rachel R Ogozalek Loo
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095
| | - Antoni Barrientos
- Department of Neurology and Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida 33136
| | - Carla M Koehler
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095.
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13
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Tienson HL, Dabir DV, Neal SE, Loo R, Hasson SA, Boontheung P, Kim SK, Loo JA, Koehler CM. Reconstitution of the mia40-erv1 oxidative folding pathway for the small tim proteins. Mol Biol Cell 2009; 20:3481-90. [PMID: 19477928 DOI: 10.1091/mbc.e08-10-1062] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Mia40 and Erv1 execute a disulfide relay to import the small Tim proteins into the mitochondrial intermembrane space. Here, we have reconstituted the oxidative folding pathway in vitro with Tim13 as a substrate and determined the midpoint potentials of Mia40 and Tim13. Specifically, Mia40 served as a direct oxidant of Tim13, and Erv1 was required to reoxidize Mia40. During oxidation, four electrons were transferred from Tim13 with the insertion of two disulfide bonds in succession. The extent of Tim13 oxidation was directly dependent on Mia40 concentration and independent of Erv1 concentration. Characterization of the midpoint potentials showed that electrons flowed from Tim13 with a more negative midpoint potential of -310 mV via Mia40 with an intermediate midpoint potential of -290 mV to the C130-C133 pair of Erv1 with a positive midpoint potential of -150 mV. Intermediary complexes between Tim13-Mia40 and Mia40-Erv1 were trapped. Last, mutating C133 of the catalytic C130-C133 pair or C30 of the shuttle C30-C33 pair in Erv1 abolished oxidation of Tim13, whereas mutating the cysteines in the redox-active CPC motif, but not the structural disulfide linkages of the CX(9)C motif of Mia40, prevented Tim13 oxidation. Thus, we demonstrate that Mia40, Erv1, and oxygen are the minimal machinery for Tim13 oxidation.
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Affiliation(s)
- Heather L Tienson
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, USA
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14
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Humphreys CP, Morgan SJ, Walapu M, Harrison GAJ, Keen AP, Efstratiou A, Neal SE, Salmon RL. Group A streptococcal skin infection outbreak in an abattoir: lessons for prevention. Epidemiol Infect 2007; 135:321-7. [PMID: 17291367 PMCID: PMC2870572 DOI: 10.1017/s0950268806006819] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/03/2006] [Indexed: 11/07/2022] Open
Abstract
During a group A streptococcus (GAS) outbreak 21 abattoir workers developed skin infections. The unusual outbreak strain (emm 108.1) was cultured from five workers and four persons in the community with links to the abattoir. The attack rate was 26% in the lamb line. Communal nailbrushes were neither routinely disinfected nor changed, and had high bacterial counts. A cohort study found a higher risk from working in the gutting area and getting cuts on hands more than weekly. Despite high bacterial counts daily nailbrush use had a lower risk, as did always wearing disposable gloves. Working in the gutting area (OR 11·44) and nailbrush use at least once a day (OR 0·04) were significant in the multivariate model. Transmission of infection is likely to have occurred on carcasses. GAS infection among abattoir workers was once common. Simple hygiene measures, such as nailbrush use, may reduce the impact of future outbreaks.
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Affiliation(s)
- C P Humphreys
- National Public Health Service for Wales, Mid and West Wales, Carmarthen, Carmarthenshire, UK.
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15
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Neal SE, Eccleston JF, Webb MR. Hydrolysis of GTP by p21NRAS, the NRAS protooncogene product, is accompanied by a conformational change in the wild-type protein: use of a single fluorescent probe at the catalytic site. Proc Natl Acad Sci U S A 1990; 87:3562-5. [PMID: 2185475 PMCID: PMC53942 DOI: 10.1073/pnas.87.9.3562] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
2'(3')-O-(N-Methyl)anthraniloylguanosine 5'-triphosphate (mantGTP) is a fluorescent analogue of GTP that has similar properties to the physiological substrate in terms of its binding constant and the kinetics of its interactions with p21NRAS, the NRAS protooncogene product. There is a 3-fold increase in fluorescence intensity when mantGTP binds to p21NRAS. The rate constant for the cleavage of mantGTP complexed with the protein is similar to that of GTP, and cleavage is accompanied by a fluorescence intensity change in the wild-type protein complex. A two-phase fluorescence change also occurs when the nonhydrolyzable analogue 2'(3')-O-(N-methyl)anthraniloylguanosine 5'-[beta, gamma-imido]triphosphate (mantp[NH]ppG) binds to wild-type p21NRAS. The second phase occurs at the same rate as the second phase observed after mantGTP binding. Thus this second phase is probably a conformation change of the p21NRAS nucleotiside triphosphate complex and that the change controls the rate of GTP hydrolysis on the protein. With a transforming mutant, [Asp12]-p21NRAS, there is no second phase of the fluorescence change after mantGTP or mantp[NH]ppG binding, even though mantGTP is hydrolyzed. This shows that an equivalent conformational change does not occur and thus the mutant may stay in a "GTP-like" conformation throughout the GTPase cycle. These results are discussed in terms of the proposed role of p21NRAS in signal transduction and the transforming properties of the mutant.
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Affiliation(s)
- S E Neal
- National Institute for Medical Research, Mill Hill, London, United Kingdom
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16
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Boyer CM, Dawson DV, Neal SE, Winchell LF, Leslie DS, Ring D, Bast RC. Differential induction by interferons of major histocompatibility complex-encoded and non-major histocompatibility complex-encoded antigens in human breast and ovarian carcinoma cell lines. Cancer Res 1989; 49:2928-34. [PMID: 2497969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Treatment of cancer cells with interferons can modulate expression of cell surface antigens, particularly those of the major histocompatibility complex (MHC). To examine the effect of recombinant gamma- and alpha-interferons on expression of non-MHC antigens, murine monoclonal antibodies have been used to quantitate 14 distinct tumor-associated cell surface antigens from five breast cancer cell lines and five ovarian cancer cell lines using a live cell radioimmunoassay. Both Class I and Class II MHC antigens could be augmented or induced with gamma-interferon. Significantly increased expression of MHC antigens was observed in nine of 10 cell lines with induction indices as high as 11-fold. When 17 non-MHC epitopes were measured on 10 cell lines, minimal (1.3-2.7-fold) induction was observed in 10 of the 170 instances evaluated. Expression of only two epitopes, 2G3 and 735B11, was increased on more than one cell line. On six cell lines expression of non-MHC epitopes could not be increased. Consequently, among many different cell surface determinants, interferons produced a highly selective augmentation or induction of MHC antigens, whereas augmentation or induction of other tumor-associated antigens was apparently restricted to a few epitopes.
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Affiliation(s)
- C M Boyer
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710
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17
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Neal SE, Eccleston JF, Hall A, Webb MR. Kinetic analysis of the hydrolysis of GTP by p21N-ras. The basal GTPase mechanism. J Biol Chem 1988; 263:19718-22. [PMID: 2848838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The rate constants have been determined for elementary steps in the basal GTPase mechanism of normal p21N-ras (Gly-12) and an oncogenic mutant (Asp-12): namely GTP binding, hydrolysis, phosphate release, and GDP release. By extrapolation from data at lower temperatures, the GTP association rate constant at 37 degrees C is 1.4 x 10(8) M-1 s-1 for the normal protein and 4.8 x 10(8) M-1 s-1 for the mutant. Other rate constants were measured directly at 37 degrees C, and three processes have similar slow values. GTP dissociation is at 1.0 x 10(-4) s-1 (normal) and 5.0 x 10(-4) s-1 (mutant). The hydrolysis step is at 3.4 x 10(-4) s-1 (normal) and 1.5 x 10(-4) s-1 (mutant). GDP dissociates at 4.2 x 10(-4) s-1 (normal) and 2.0 x 10(-4) s-1 (mutant). GDP association rate constants are similar to those for GTP, 0.5 x 10(8) M-1 s-1 for normal and 0.7 x 10(8) M-1 s-1 for mutant. Both hydrolysis and GDP release therefore contribute to rate limitation of the basal GTPase activity. There are distinct differences (up to 5-fold) between rate constants for the normal and mutant proteins at a number of steps. The values are consistent with the reduced GTPase activity for this mutant and suggest little difference between normal and mutant proteins in the relative steady-state concentrations of GTP and GDP complexes that may represent active and inactive states. The results are discussed in terms of the likely role of p21ras in transmembrane signalling.
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Affiliation(s)
- S E Neal
- Division of Physical Biochemistry, National Institute for Medical Research, London, United Kingdom
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