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The subcommissural organ and the Reissner fiber: old friends revisited. Cell Tissue Res 2018; 375:507-529. [PMID: 30259139 DOI: 10.1007/s00441-018-2917-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 07/17/2018] [Indexed: 12/11/2022]
Abstract
The subcommissural organ (SCO) is an ancient and conserved brain gland secreting into cerebrospinal fluid (CSF) glycoproteins that form the Reissner fiber (RF). The present investigation was designed to further investigate the dynamic of the biosynthetic process of RF glycoproteins prior and after their release into the CSF, to identify the RF proteome and N-glycome and to clarify the mechanism of assembly of RF glycoproteins. Various methodological approaches were used: biosynthetic labelling injecting 35S-cysteine and 3H-galactose into the CSF, injection of antibodies against galectin-1 into the cerebrospinal fluid, light and electron microscopical methods; isolated bovine RF was used for proteome analyses by mass spectrometry and glycome analysis by xCGE-LIF. The biosynthetic labelling study further supported that a small pool of SCO-spondin molecules rapidly enter the secretory pathways after its synthesis, while most of the SCO-spondin molecules are stored in the rough endoplasmic reticulum for hours or days before entering the secretory pathway and being released to assemble into RF. The proteomic analysis of RF revealed clusterin and galectin-1 as partners of SCO-spondin; the in vivo use of anti-galectin-1 showed that this lectin is essential for the assembly of RF. Galectin-1 is not secreted by the SCO but evidence was obtained that it would be secreted by multiciliated ependymal cells lying close to the SCO. Further, a surprising variety and complexity of glycan structures were identified in the RF N-glycome that further expands the potential functions of RF to a level not previously envisaged. A model of the macromolecular organization of Reissner fiber is proposed.
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Abstract
The concept of cell signaling in the context of nonenzyme-assisted protein modifications by reactive electrophilic and oxidative species, broadly known as redox signaling, is a uniquely complex topic that has been approached from numerous different and multidisciplinary angles. Our Review reflects on five aspects critical for understanding how nature harnesses these noncanonical post-translational modifications to coordinate distinct cellular activities: (1) specific players and their generation, (2) physicochemical properties, (3) mechanisms of action, (4) methods of interrogation, and (5) functional roles in health and disease. Emphasis is primarily placed on the latest progress in the field, but several aspects of classical work likely forgotten/lost are also recollected. For researchers with interests in getting into the field, our Review is anticipated to function as a primer. For the expert, we aim to stimulate thought and discussion about fundamentals of redox signaling mechanisms and nuances of specificity/selectivity and timing in this sophisticated yet fascinating arena at the crossroads of chemistry and biology.
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Affiliation(s)
- Saba Parvez
- Department of Pharmacology and Toxicology, College of
Pharmacy, University of Utah, Salt Lake City, Utah, 84112, USA
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
| | - Marcus J. C. Long
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
| | - Jesse R. Poganik
- Ecole Polytechnique Fédérale de Lausanne,
Institute of Chemical Sciences and Engineering, 1015, Lausanne, Switzerland
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
| | - Yimon Aye
- Ecole Polytechnique Fédérale de Lausanne,
Institute of Chemical Sciences and Engineering, 1015, Lausanne, Switzerland
- Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York, 14853, USA
- Department of Biochemistry, Weill Cornell Medicine, New
York, New York, 10065, USA
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Unfolding the Endoplasmic Reticulum of a Social Amoeba: Dictyostelium discoideum as a New Model for the Study of Endoplasmic Reticulum Stress. Cells 2018; 7:cells7060056. [PMID: 29890774 PMCID: PMC6025073 DOI: 10.3390/cells7060056] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 05/28/2018] [Accepted: 06/05/2018] [Indexed: 01/19/2023] Open
Abstract
The endoplasmic reticulum (ER) is a membranous network with an intricate dynamic architecture necessary for various essential cellular processes. Nearly one third of the proteins trafficking through the secretory pathway are folded and matured in the ER. Additionally, it acts as calcium storage, and it is a main source for lipid biosynthesis. The ER is highly connected with other organelles through regions of membrane apposition that allow organelle remodeling, as well as lipid and calcium traffic. Cells are under constant changes due to metabolic requirements and environmental conditions that challenge the ER network’s maintenance. The unfolded protein response (UPR) is a signaling pathway that restores homeostasis of this intracellular compartment upon ER stress conditions by reducing the load of proteins, and by increasing the processes of protein folding and degradation. Significant progress on the study of the mechanisms that restore ER homeostasis was achieved using model organisms such as yeast, Arabidopsis, and mammalian cells. In this review, we address the current knowledge on ER architecture and ER stress response in Dictyostelium discoideum. This social amoeba alternates between unicellular and multicellular phases and is recognized as a valuable biomedical model organism and an alternative to yeast, particularly for the presence of traits conserved in animal cells that were lost in fungi.
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Steiger D, Yokota T, Li J, Ren S, Minamisawa S, Wang Y. The serine/threonine-protein kinase/endoribonuclease IRE1α protects the heart against pressure overload-induced heart failure. J Biol Chem 2018; 293:9652-9661. [PMID: 29769316 DOI: 10.1074/jbc.ra118.003448] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 05/04/2018] [Indexed: 12/26/2022] Open
Abstract
Heart failure is associated with induction of endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). The serine/threonine protein kinase/endoribonuclease IRE1α is a key protein in ER stress signal transduction. IRE1α activity can induce both protective UPR and apoptotic downstream signaling events, but the specific role for IRE1α activity in the heart is unknown. A major aim of this study was to characterize the specific contribution of IRE1α in cardiac physiology and pathogenesis. We used both cultured myocytes and a transgenic mouse line with inducible and cardiomyocyte-specific IRE1α overexpression as experimental models to achieve targeted IRE1α activation. IRE1α expression induced a potent but transient ER stress response in cardiomyocytes and did not cause significant effects in the intact heart under normal physiological conditions. Furthermore, the IRE1α-activated transgenic heart responding to pressure overload exhibited preserved function and reduced fibrotic area, associated with increased adaptive UPR signaling and with blunted inflammatory and pathological gene expression. Therefore, we conclude that IRE1α induces transient ER stress signaling and confers a protective effect against pressure overload-induced pathological remodeling in the heart. To our knowledge, this report provides first direct evidence of a specific and protective role for IRE1α in the heart and reveals an interaction between ER stress signaling and inflammatory regulation in the pathologically stressed heart.
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Affiliation(s)
- DeAnna Steiger
- From the Departments of Anesthesiology, Physiology, and Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095 and
| | - Tomohiro Yokota
- From the Departments of Anesthesiology, Physiology, and Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095 and
| | - Jin Li
- From the Departments of Anesthesiology, Physiology, and Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095 and
| | - Shuxun Ren
- From the Departments of Anesthesiology, Physiology, and Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095 and
| | - Susumu Minamisawa
- the Department of Cell Physiology, Jikei University School of Medicine, Tokyo 105-8461, Japan
| | - Yibin Wang
- From the Departments of Anesthesiology, Physiology, and Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California 90095 and
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Singh SK, Tiendrebeogo RW, Chourasia BK, Kana IH, Singh S, Theisen M. Lactococcus lactis provides an efficient platform for production of disulfide-rich recombinant proteins from Plasmodium falciparum. Microb Cell Fact 2018; 17:55. [PMID: 29618355 PMCID: PMC5885415 DOI: 10.1186/s12934-018-0902-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 03/27/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The production of recombinant proteins with proper conformation, appropriate post-translational modifications in an easily scalable and cost-effective system is challenging. Lactococcus lactis has recently been identified as an efficient Gram positive cell factory for the production of recombinant protein. We and others have used this expression host for the production of selected malaria vaccine candidates. The safety of this production system has been confirmed in multiple clinical trials. Here we have explored L. lactis cell factories for the production of 31 representative Plasmodium falciparum antigens with varying sizes (ranging from 9 to 90 kDa) and varying degree of predicted structural complexities including eleven antigens with multiple predicted structural disulfide bonds, those which are considered difficult-to-produce proteins. RESULTS Of the 31 recombinant constructs attempted in the L. lactis expression system, the initial expression efficiency was 55% with 17 out of 31 recombinant gene constructs producing high levels of secreted recombinant protein. The majority of the constructs which failed to produce a recombinant protein were found to consist of multiple intra-molecular disulfide-bonds. We found that these disulfide-rich constructs could be produced in high yields when genetically fused to an intrinsically disorder protein domain (GLURP-R0). By exploiting the distinct biophysical and structural properties of the intrinsically disordered protein region we developed a simple heat-based strategy for fast purification of the disulfide-rich protein domains in yields ranging from 1 to 40 mg/l. CONCLUSIONS A novel procedure for the production and purification of disulfide-rich recombinant proteins in L. lactis is described.
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Affiliation(s)
- Susheel K Singh
- Department for Congenital Disorders, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen S, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Régis Wendpayangde Tiendrebeogo
- Department for Congenital Disorders, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen S, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Bishwanath Kumar Chourasia
- Department for Congenital Disorders, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen S, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Ikhlaq Hussain Kana
- Department for Congenital Disorders, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen S, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Subhash Singh
- Indian Institute of Integrative Medicine, Jammu, India
| | - Michael Theisen
- Department for Congenital Disorders, Statens Serum Institut, Artillerivej 5, 2300, Copenhagen S, Denmark. .,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark. .,Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
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56
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Kumar V, Sharma AK, Rajput SK, Pal M, Dhiman N. Pharmacognostic and pharmacological evaluation of Eulaliopsis binata plant extracts by measuring in vitro/ in vivo safety profile and anti-microbial potential. Toxicol Res (Camb) 2018; 7:454-464. [PMID: 30090595 DOI: 10.1039/c8tx00017d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 03/09/2018] [Indexed: 11/21/2022] Open
Abstract
The present investigation emphasizes the pharmacognostic and phytochemical screening of Eulaliopsis binata and further evaluates the extracts of this plant for toxicological profile and anti-bacterial potential based on in vivo/in vitro assays. Microscopy, powder characteristics of the leaf material, and physicochemical and phytochemical screening were assessed for pharmacognostic evaluation. Dry leaves of Eulaliopsis binata were extracted using different solvents (methanol, ethyl acetate, and hexane), and the extracts obtained were further investigated for in vitro/in vivo toxicological study. Moreover, acute toxicity was assessed by evaluating the anti-oxidant defense system and anatomical damage in vital organs. In addition, anti-bacterial activity of all the extracts was assessed by the Kirby-Bauer method. Physicochemical and microscopic observations showed the unique identification mark for leaf powder and leaf transverse section. Phytochemical investigation evidenced the presence of flavonoids and phenolic contents in the methanolic extract. All extracts were found to be hemocompatible and exhibited no induction of behavioral alteration and no alteration in the anti-oxidant potential and anatomical structure of the vital organs. On the other hand, the methanolic extract showed a significant upsurge in the reduced glutathione level, whereas all extracts showed significant anti-bacterial potential in a dose-dependent manner. Eulaliopsis binata has inimitable pharmacognostical characteristics, good safety profile and significant anti-oxidant and anti-bacterial potential that show immense possibility for its further investigation for pharmacological use.
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Affiliation(s)
- Vinod Kumar
- Department of Pharmaceutical Chemistry , Amity University , Noida , Uttar Pradesh-201303 , India . ; Tel: +91 120 4392498, ext: 5557
| | - Arun K Sharma
- Department of Pharmacology , Amity University , Noida , Uttar Pradesh-201303 , India
| | - Satyendra K Rajput
- Department of Pharmacology , Amity University , Noida , Uttar Pradesh-201303 , India
| | - Mahesh Pal
- Phytochemistry Division , CSIR-National Botanical Research Institute , Lucknow , Uttar Pradesh-226001 , India
| | - Neerupma Dhiman
- Department of Pharmaceutical Chemistry , Amity University , Noida , Uttar Pradesh-201303 , India . ; Tel: +91 120 4392498, ext: 5557
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Lewandowska H, Męczyńska-Wielgosz S, Sikorska K, Sadło J, Dudek J, Kruszewski M. LDL dinitrosyl iron complex: A new transferrin-independent route for iron delivery in hepatocytes. Biofactors 2018; 44:192-201. [PMID: 29399922 DOI: 10.1002/biof.1412] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 12/09/2017] [Accepted: 12/29/2017] [Indexed: 12/14/2022]
Abstract
In view of the interrelations between NO, Fe, and LDL in the cardiovascular system it appears interesting to find out, if the lipoprotein particles undergo the process of iron-nitrosylation, commonly observed for other proteins and what is the biological fate of iron-nitrosylated LDL particles. Iron-nitrosylated LDL preparation containing Fe(NO)2 motif (DNICLDL) was obtained and characterized for the first time. In order to test its interactions with potential target cells, DNICLDL was administered to the hepatoma HepG2 cells. The effects were referred to those induced by native LDL (nLDL) and oxidized LDL (oxLDL) particles. DNICLDL administration considerably increased total iron content in the studied cell line, but did not influence the level of calcein-chelatable ions. DNICLDL was found to be low toxic to cells. The study suggests that DNICLDL might be a potential transducer of iron. © 2017 BioFactors, 44(2):192-201, 2018.
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Affiliation(s)
- Hanna Lewandowska
- Institute of Nuclear Chemistry and Technology, 16 Dorodna Str, Warsaw, 03-195, Poland
| | | | - Katarzyna Sikorska
- Institute of Nuclear Chemistry and Technology, 16 Dorodna Str, Warsaw, 03-195, Poland
| | - Jarosław Sadło
- Institute of Nuclear Chemistry and Technology, 16 Dorodna Str, Warsaw, 03-195, Poland
| | - Jakub Dudek
- Institute of Nuclear Chemistry and Technology, 16 Dorodna Str, Warsaw, 03-195, Poland
| | - Marcin Kruszewski
- Institute of Nuclear Chemistry and Technology, 16 Dorodna Str, Warsaw, 03-195, Poland
- Faculty of Medicine, University of Information Technology and Management in Rzeszów, ul. Sucharskiego 2, Rzeszów, 35-225, Poland
- Department of Molecular Biology and Translational Research, Institute of Rural Health, Jaczewskiego 2, Lublin, 20-090, Poland
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58
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Biosynthesis of human myeloperoxidase. Arch Biochem Biophys 2018; 642:1-9. [PMID: 29408362 DOI: 10.1016/j.abb.2018.02.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 01/31/2018] [Accepted: 02/02/2018] [Indexed: 01/30/2023]
Abstract
Members of Chordata peroxidase subfamily [1] expressed in mammals, including myeloperoxidase (MPO), eosinophil peroxidase (EPO), lactoperoxidase (LPO), and thyroid peroxidase (TPO), express conserved motifs around the heme prosthetic group essential for their activity, a calcium-binding site, and at least two covalent bonds linking the heme group to the protein backbone. Although most studies of the biosynthesis of these peroxidases have focused on MPO, many of the features described occur during biosynthesis of other members of the protein subfamily. Whereas MPO biosynthesis includes events typical for proteins generated in the secretory pathway, the importance and consequences of heme insertion are events uniquely associated with peroxidases. This Review summarizes decades of work elucidating specific steps in the biosynthetic pathway of human MPO. Discussion includes cotranslational glycosylation and subsequent modifications of the N-linked carbohydrate sidechains, contributions by molecular chaperones in the endoplasmic reticulum, cleavage of the propeptide from proMPO, and proteolytic processing of protomers and dimerization to yield mature MPO. Parallels between the biosynthesis of MPO and TPO as well as the impact of inherited mutations in the MPO gene on normal biosynthesis will be summarized. Lastly, specific gaps in our knowledge revealed by this review of our current understanding will be highlighted.
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59
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Non-equilibrium coupling of protein structure and function to translation-elongation kinetics. Curr Opin Struct Biol 2018; 49:94-103. [PMID: 29414517 DOI: 10.1016/j.sbi.2018.01.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/21/2017] [Accepted: 01/02/2018] [Indexed: 01/23/2023]
Abstract
Protein folding research has been dominated by the assumption that thermodynamics determines protein structure and function. And that when the folding process is compromised in vivo the proteostasis machinery-chaperones, deaggregases, the proteasome-work to restore proteins to their soluble, functional form or degrade them to maintain the cellular pool of proteins in a quasi-equilibrium state. During the past decade, however, more and more proteins have been identified for which altering only their speed of synthesis alters their structure and function, the efficiency of the down-stream processes they take part in, and cellular phenotype. Indeed, evidence has emerged that evolutionary selection pressures have encoded translation-rate information into mRNA molecules to coordinate diverse co-translational processes. Thus, non-equilibrium physics can play a fundamental role in influencing nascent protein behavior, mRNA sequence evolution, and disease. Here, we discuss how our understanding of this phenomenon is being advanced by the application of theoretical tools from the physical sciences.
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60
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Abstract
The endoplasmic reticulum (ER) is a key site for lipid biosynthesis and folding of nascent transmembrane and secretory proteins. These processes are maintained by careful homeostatic control of the environment within the ER lumen. Signalling sensors within the ER detect perturbations within the lumen (ER stress) and employ downstream signalling cascades that engage effector mechanisms to restore homeostasis. The most studied signalling mechanism that the ER employs is the unfolded protein response (UPR), which is known to increase a number of effector mechanisms, including autophagy. In this chapter, we will discuss the emerging role of autophagy as a UPR effector pathway. We will focus on the recently discovered selective autophagy pathway for ER, ER-phagy, with particular emphasis on the structure and function of known mammalian ER-phagy receptors, namely FAM134B, SEC62, RTN3 and CCPG1. Finally, we conclude with our view of where the future of this field can lead our understanding of the involvement of ER-phagy in ER homeostasis.
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61
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Schito L, Rey S. Cell-Autonomous Metabolic Reprogramming in Hypoxia. Trends Cell Biol 2017; 28:128-142. [PMID: 29191366 DOI: 10.1016/j.tcb.2017.10.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 10/25/2017] [Accepted: 10/25/2017] [Indexed: 12/31/2022]
Abstract
Molecular oxygen (O2) is a universal electron acceptor that enables ATP synthesis through mitochondrial respiration in all metazoans. Consequently, hypoxia (low O2) has arisen as an organizing principle for cellular evolution, metabolism, and (patho)biology, eliciting a remarkable panoply of metabolic adaptations that trigger transcriptional, translational, post-translational, and epigenetic responses to determine cellular fitness. In this review we summarize current and emerging cell-autonomous molecular mechanisms that induce hypoxic metabolic reprogramming in health and disease.
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Affiliation(s)
- Luana Schito
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada.
| | - Sergio Rey
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 1L7, Canada.
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62
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Sepúlveda-Salinas KJ, Ramos-Castañeda J. Participation of dengue virus NS4B protein in the modulation of immune effectors dependent on ER stress in insect cells. Cell Stress Chaperones 2017; 22:799-810. [PMID: 28755304 PMCID: PMC5655368 DOI: 10.1007/s12192-017-0810-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/11/2017] [Accepted: 05/15/2017] [Indexed: 12/15/2022] Open
Abstract
Organisms' reactions to adverse events result in the generation of immune effectors, which, in the case of insects, may be produced from the direct activation of pathways such as Toll, Jak-STAT, Imd, or RNAi or may be derived from the crosstalk of different intracellular pathways. One such pathway, the unfolded protein response (UPR), has the primary objective of restoring homeostasis in the endoplasmic reticulum. In addition, the UPR participates in signaling crosstalk with the immune pathways, generating protection against pathogenic organisms. Dengue virus is a plus-strand RNA virus belonging to the Flavivirus genus that uses the ER as a replication site; during the infection, there are indicators of the activation of the UPR, which in turn, induces the synthesis of internal membranes and preferential translation of viral proteins enhancing the replication. One of the dengue virus proteins, the NS4B can block the pathway of α/β interferon in mammals. However, what happen in insects is interesting because the lack of the main antiviral pathway, the interferon and the role of the NS4B protein in the UPR-immunity relationship can be better understood. Thus, in this study, we demonstrated that the DENV2/16681 NS4B protein is capable of modulating the immune effectors that result from the activation of the UPR in insect cells.
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Affiliation(s)
- Karla J Sepúlveda-Salinas
- CISEI (Centro de Investigación Sobre Enfermedades Infeciosas), Instituto Nacional de Salud Pública, Universidad No. 655 Colonia Santa María Ahuacatitlán, Cerrada Los Pinos y Caminera, 62100, Cuernavaca, Morelos, Mexico
| | - José Ramos-Castañeda
- CISEI (Centro de Investigación Sobre Enfermedades Infeciosas), Instituto Nacional de Salud Pública, Universidad No. 655 Colonia Santa María Ahuacatitlán, Cerrada Los Pinos y Caminera, 62100, Cuernavaca, Morelos, Mexico.
- Center for Tropical Diseases, University of Texas-Medical Branch, Galveston, TX, USA.
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63
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Beilhartz GL, Sugiman-Marangos SN, Melnyk RA. Repurposing bacterial toxins for intracellular delivery of therapeutic proteins. Biochem Pharmacol 2017; 142:13-20. [DOI: 10.1016/j.bcp.2017.04.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 04/07/2017] [Indexed: 01/02/2023]
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64
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Maes E, Dyer JM, McKerchar HJ, Deb-Choudhury S, Clerens S. Protein-protein cross-linking and human health: the challenge of elucidating with mass spectrometry. Expert Rev Proteomics 2017; 14:917-929. [PMID: 28759730 DOI: 10.1080/14789450.2017.1362336] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
INTRODUCTION In several biomedical research fields, the cross-linking of peptides and proteins has an important impact on health and wellbeing. It is therefore of crucial importance to study this class of post-translational modifications in detail. The huge potential of mass spectrometric technologies in the mapping of these protein-protein cross-links is however overshadowed by the challenges that the field has to overcome. Areas covered: In this review, we summarize the different pitfalls and challenges that the protein-protein cross-linking field is confronted with when using mass spectrometry approaches. We additionally focus on native disulfide bridges as an example and provide some examples of cross-links that are important in the biomedical field. Expert commentary: The current flow of methodological improvements, mainly from the chemical cross-linking field, has delivered a significant contribution to deciphering native and insult-induced cross-links. Although an automated data analysis of proteome-wide peptide cross-linking is currently only possible in chemical cross-linking experiments, the field is well on the way towards a more automated analysis of native and insult-induced cross-links in raw mass spectrometry data that will boost its potential in biomedical applications.
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Affiliation(s)
- Evelyne Maes
- a Food & Bio-Based Products, AgResearch Ltd ., Lincoln , New Zealand
| | - Jolon M Dyer
- a Food & Bio-Based Products, AgResearch Ltd ., Lincoln , New Zealand.,b Biomolecular Interaction Centre , University of Canterbury , Christchurch , New Zealand.,c Riddet Institute, Massey University , Palmerston North , New Zealand.,d Wine, Food & Molecular Biosciences , Lincoln University , Lincoln , New Zealand
| | - Hannah J McKerchar
- a Food & Bio-Based Products, AgResearch Ltd ., Lincoln , New Zealand.,b Biomolecular Interaction Centre , University of Canterbury , Christchurch , New Zealand
| | | | - Stefan Clerens
- a Food & Bio-Based Products, AgResearch Ltd ., Lincoln , New Zealand.,b Biomolecular Interaction Centre , University of Canterbury , Christchurch , New Zealand
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65
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Lopez CE, Sheehan HC, Vierra DA, Azzinaro PA, Meedel TH, Howlett NG, Irvine SQ. Proteomic responses to elevated ocean temperature in ovaries of the ascidian Ciona intestinalis. Biol Open 2017; 6:943-955. [PMID: 28500033 PMCID: PMC5550911 DOI: 10.1242/bio.024786] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 05/10/2017] [Indexed: 11/21/2022] Open
Abstract
Ciona intestinalis, a common sea squirt, exhibits lower reproductive success at the upper extreme of the water temperatures it experiences in coastal New England. In order to understand the changes in protein expression associated with elevated temperatures, and possible response to global temperature change, we reared C. intestinalis from embryos to adults at 18°C (a temperature at which they reproduce normally at our collection site in Rhode Island) and 22°C (the upper end of the local temperature range). We then dissected ovaries from animals at each temperature, extracted protein, and measured proteomic levels using shotgun mass spectrometry (LC-MS/MS). 1532 proteins were detected at a 1% false discovery rate present in both temperature groups by our LC-MS/MS method. 62 of those proteins are considered up- or down-regulated according to our statistical criteria. Principal component analysis shows a clear distinction in protein expression pattern between the control (18°C) group and high temperature (22°C) group. Similar to previous studies, cytoskeletal and chaperone proteins are upregulated in the high temperature group. Unexpectedly, we find evidence that proteolysis is downregulated at the higher temperature. We propose a working model for the high temperature response in C. intestinalis ovaries whereby increased temperature induces upregulation of signal transduction pathways involving PTPN11 and CrkL, and activating coordinated changes in the proteome especially in large lipid transport proteins, cellular stress responses, cytoskeleton, and downregulation of energy metabolism.
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Affiliation(s)
- Chelsea E Lopez
- Departments of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | - Hannah C Sheehan
- Departments of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | - David A Vierra
- Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Paul A Azzinaro
- Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Thomas H Meedel
- Biology Department, Rhode Island College, Providence, RI 02908, USA
| | - Niall G Howlett
- Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Steven Q Irvine
- Departments of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
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Lian J, Nelson R, Lehner R. Carboxylesterases in lipid metabolism: from mouse to human. Protein Cell 2017; 9:178-195. [PMID: 28677105 PMCID: PMC5818367 DOI: 10.1007/s13238-017-0437-z] [Citation(s) in RCA: 155] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 05/31/2017] [Indexed: 12/12/2022] Open
Abstract
Mammalian carboxylesterases hydrolyze a wide range of xenobiotic and endogenous compounds, including lipid esters. Physiological functions of carboxylesterases in lipid metabolism and energy homeostasis in vivo have been demonstrated by genetic manipulations and chemical inhibition in mice, and in vitro through (over)expression, knockdown of expression, and chemical inhibition in a variety of cells. Recent research advances have revealed the relevance of carboxylesterases to metabolic diseases such as obesity and fatty liver disease, suggesting these enzymes might be potential targets for treatment of metabolic disorders. In order to translate pre-clinical studies in cellular and mouse models to humans, differences and similarities of carboxylesterases between mice and human need to be elucidated. This review presents and discusses the research progress in structure and function of mouse and human carboxylesterases, and the role of these enzymes in lipid metabolism and metabolic disorders.
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Affiliation(s)
- Jihong Lian
- Group on Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada. .,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.
| | - Randal Nelson
- Group on Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada.,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Richard Lehner
- Group on Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada.,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.,Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
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67
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Gąciarz A, Khatri NK, Velez-Suberbie ML, Saaranen MJ, Uchida Y, Keshavarz-Moore E, Ruddock LW. Efficient soluble expression of disulfide bonded proteins in the cytoplasm of Escherichia coli in fed-batch fermentations on chemically defined minimal media. Microb Cell Fact 2017; 16:108. [PMID: 28619018 PMCID: PMC5471842 DOI: 10.1186/s12934-017-0721-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 06/06/2017] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The production of recombinant proteins containing disulfide bonds in Escherichia coli is challenging. In most cases the protein of interest needs to be either targeted to the oxidizing periplasm or expressed in the cytoplasm in the form of inclusion bodies, then solubilized and re-folded in vitro. Both of these approaches have limitations. Previously we showed that soluble expression of disulfide bonded proteins in the cytoplasm of E. coli is possible at shake flask scale with a system, known as CyDisCo, which is based on co-expression of a protein of interest along with a sulfhydryl oxidase and a disulfide bond isomerase. With CyDisCo it is possible to produce disulfide bonded proteins in the presence of intact reducing pathways in the cytoplasm. RESULTS Here we scaled up production of four disulfide bonded proteins to stirred tank bioreactors and achieved high cell densities and protein yields in glucose fed-batch fermentations, using an E. coli strain (BW25113) with the cytoplasmic reducing pathways intact. Even without process optimization production of purified human single chain IgA1 antibody fragment reached 139 mg/L and hen avidin 71 mg/L, while purified yields of human growth hormone 1 and interleukin 6 were around 1 g/L. Preliminary results show that human growth hormone 1 was also efficiently produced in fermentations of W3110 strain and when glucose was replaced with glycerol as the carbon source. CONCLUSIONS Our results show for the first time that efficient production of high yields of soluble disulfide bonded proteins in the cytoplasm of E. coli with the reducing pathways intact is feasible to scale-up to bioreactor cultivations on chemically defined minimal media.
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Affiliation(s)
- Anna Gąciarz
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, 90014 Oulu, Finland
| | - Narendar Kumar Khatri
- The Department of Process and Environment Engineering, University of Oulu, P.O. Box 8000, 90014 Oulu, Finland
| | - M. Lourdes Velez-Suberbie
- The Advanced Center for Biochemical Engineering, Department of Biochemical Engineering, University College London, Bernard Katz Building, Gower Street, London, WC1E 6BT UK
| | - Mirva J. Saaranen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, 90014 Oulu, Finland
| | - Yuko Uchida
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, 90014 Oulu, Finland
| | - Eli Keshavarz-Moore
- The Advanced Center for Biochemical Engineering, Department of Biochemical Engineering, University College London, Bernard Katz Building, Gower Street, London, WC1E 6BT UK
| | - Lloyd W. Ruddock
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, 90014 Oulu, Finland
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68
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Gutiérrez T, Simmen T. Endoplasmic reticulum chaperones tweak the mitochondrial calcium rheostat to control metabolism and cell death. Cell Calcium 2017; 70:64-75. [PMID: 28619231 DOI: 10.1016/j.ceca.2017.05.015] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/24/2017] [Accepted: 05/24/2017] [Indexed: 12/16/2022]
Abstract
The folding of secretory proteins is a well-understood mechanism, based on decades of research on endoplasmic reticulum (ER) chaperones. These chaperones interact with newly imported polypeptides close to the ER translocon. Classic examples for these proteins include the immunoglobulin binding protein (BiP/GRP78), and the lectins calnexin and calreticulin. Although not considered chaperones per se, the ER oxidoreductases of the protein disulfide isomerase (PDI) family complete the folding job by catalyzing the formation of disulfide bonds through cysteine oxidation. Research from the past decade has demonstrated that ER chaperones are multifunctional proteins. The regulation of ER-mitochondria Ca2+ crosstalk is one of their additional functions, as shown for calnexin, BiP/GRP78 or the oxidoreductases Ero1α and TMX1. This function depends on interactions of this group of proteins with the ER Ca2+ handling machinery. This novel function makes perfect sense for two reasons: i. It allows ER chaperones to control mitochondrial apoptosis instantly without a lengthy bypass involving the upregulation of pro-apoptotic transcription factors via the unfolded protein response (UPR); and ii. It allows the ER protein folding machinery to fine-tune ATP import via controlling the speed of mitochondrial oxidative phosphorylation. Therefore, the role of ER chaperones in regulating ER-mitochondria Ca2+ flux identifies the progression of secretory protein folding as a central regulator of cell survival and death, at least in cell types that secrete large amount of proteins. In other cell types, ER protein folding might serve as a sentinel mechanism that monitors cellular well-being to control cell metabolism and apoptosis. The selenoprotein SEPN1 is a classic example for such a role. Through the control of ER-mitochondria Ca2+-flux, ER chaperones and folding assistants guide cellular apoptosis and mitochondrial metabolism.
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Affiliation(s)
- Tomas Gutiérrez
- Faculty of Medicine and Dentistry, Department of Cell Biology, University of Alberta, Edmonton, T6G2H7, Canada
| | - Thomas Simmen
- Faculty of Medicine and Dentistry, Department of Cell Biology, University of Alberta, Edmonton, T6G2H7, Canada,.
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69
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Robinson PJ, Pringle MA, Woolhead CA, Bulleid NJ. Folding of a single domain protein entering the endoplasmic reticulum precedes disulfide formation. J Biol Chem 2017; 292:6978-6986. [PMID: 28298446 PMCID: PMC5409466 DOI: 10.1074/jbc.m117.780742] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 03/09/2017] [Indexed: 12/31/2022] Open
Abstract
The relationship between protein synthesis, folding, and disulfide formation within the endoplasmic reticulum (ER) is poorly understood. Previous studies have suggested that pre-existing disulfide links are absolutely required to allow protein folding and, conversely, that protein folding occurs prior to disulfide formation. To address the question of what happens first within the ER, that is, protein folding or disulfide formation, we studied folding events at the early stages of polypeptide chain translocation into the mammalian ER using stalled translation intermediates. Our results demonstrate that polypeptide folding can occur without complete domain translocation. Protein disulfide isomerase (PDI) interacts with these early intermediates, but disulfide formation does not occur unless the entire sequence of the protein domain is translocated. This is the first evidence that folding of the polypeptide chain precedes disulfide formation within a cellular context and highlights key differences between protein folding in the ER and refolding of purified proteins.
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Affiliation(s)
- Philip J Robinson
- From the Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Marie Anne Pringle
- From the Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Cheryl A Woolhead
- From the Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Neil J Bulleid
- From the Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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70
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Bowley SR, Fang C, Merrill-Skoloff G, Furie BC, Furie B. Protein disulfide isomerase secretion following vascular injury initiates a regulatory pathway for thrombus formation. Nat Commun 2017; 8:14151. [PMID: 28218242 PMCID: PMC5321760 DOI: 10.1038/ncomms14151] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 12/02/2016] [Indexed: 01/15/2023] Open
Abstract
Protein disulfide isomerase (PDI), secreted by platelets and endothelial cells on vascular injury, is required for thrombus formation. Using PDI variants that form mixed disulfide complexes with their substrates, we identify by kinetic trapping multiple substrate proteins, including vitronectin. Plasma vitronectin does not bind to αvβ3 or αIIbβ3 integrins on endothelial cells and platelets. The released PDI reduces disulfide bonds on plasma vitronectin, enabling vitronectin to bind to αVβ3 and αIIbβ3. In vivo studies of thrombus generation in mice demonstrate that vitronectin rapidly accumulates on the endothelium and the platelet thrombus following injury. This process requires PDI activity and promotes platelet accumulation and fibrin generation. We hypothesize that under physiologic conditions in the absence of secreted PDI, thrombus formation is suppressed and maintains a quiescent, patent vasculature. The release of PDI during vascular injury may serve as a regulatory switch that allows activation of proteins, among them vitronectin, critical for thrombus formation.
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Affiliation(s)
- Sheryl R Bowley
- Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Chao Fang
- Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Glenn Merrill-Skoloff
- Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Barbara C Furie
- Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Bruce Furie
- Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
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71
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Fedoseev SV, Belikov MY, Ershov OV, Tafeenko VA. Reductive alkylation of disulfides. Synthesis of 2-(alkylsulfanyl)-1H-pyrrole-3-carbonitriles. RUSSIAN JOURNAL OF ORGANIC CHEMISTRY 2017. [DOI: 10.1134/s1070428016120125] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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72
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Thulasitha WS, Umasuthan N, Jayasooriya RGPT, Noh JK, Park HC, Lee J. A thioredoxin domain-containing protein 12 from black rockfish Sebastes schlegelii: Responses to immune challenges and protection from apoptosis against oxidative stress. Comp Biochem Physiol C Toxicol Pharmacol 2016; 185-186:29-37. [PMID: 26945103 DOI: 10.1016/j.cbpc.2016.02.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/19/2016] [Accepted: 02/28/2016] [Indexed: 01/15/2023]
Abstract
Thioredoxin (TXN) superfamily proteins are identified by the presence of a thioredoxin active site with a conserved CXXC active motif. TXN members are involved in a wide range of biochemical and biological functions including redox regulation, refolding of disulfide containing proteins, and regulation of transcription factors. In the present study, a thioredoxin domain-containing protein 12 was identified and characterized from black rockfish, Sebastes schlegelii (RfTXNDC12). The full length of RfTXNDC12 consists of a 522-bp coding region encoding a 173-amino acid protein. It has a 29-amino acid signal peptide and a single TXN active site with a consensus atypical WCGAC active motif. Multiple sequence alignment revealed that the active site is conserved among vertebrates. RfTXNDC12 shares highest identity with its Epinephelus coioides homolog. Transcriptional analysis revealed its ubiquitous expression in a wide range of tissues with the highest expression in the ovary. Immune challenges conducted with Streptococcus iniae and poly I:C caused upregulation of RfTXNDC12 transcript levels in gills and peripheral blood cells (PBCs), while lipopolysaccharide injection caused downregulation of RfTXNDC12 in gills and upregulation in PBCs. Similar to TXN, RfTXNDC12 exhibited insulin disulfide reducing activity. Interestingly, the recombinant protein showed significant protection of LNCaP cells against apoptosis induced by H2O2-mediated oxidative stress in a concentration dependent manner. Collectively, the present data indicate that RfTXNDC12 is a TXN superfamily member, which could function as a potential antioxidant enzyme and be involved in a defense mechanism against immune challenges.
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Affiliation(s)
- William Shanthakumar Thulasitha
- Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Development Center, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea
| | - Navaneethaiyer Umasuthan
- Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Development Center, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea
| | - R G P T Jayasooriya
- Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea
| | - Jae Koo Noh
- Genetics & Breeding Research Center, National Institute of Fisheries Science, Geoje 656-842, Republic of Korea
| | - Hae-Chul Park
- Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea.
| | - Jehee Lee
- Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Development Center, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea.
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73
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Ravindran MS, Bagchi P, Cunningham CN, Tsai B. Opportunistic intruders: how viruses orchestrate ER functions to infect cells. Nat Rev Microbiol 2016; 14:407-420. [PMID: 27265768 PMCID: PMC5272919 DOI: 10.1038/nrmicro.2016.60] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Viruses exploit the functions of the endoplasmic reticulum (ER) to promote both early and later stages of their life cycle, including entry, translation, replication, assembly, morphogenesis and egress. This observation reveals a shared principle that underlies virus–host cell relationships. Viral entry often requires disassembly of the incoming virus particle. This is best exemplified in the case of polyomavirus entry, in which ER-associated machineries are hijacked to disassemble the virus and promote entry to the cytosol en route to the nucleus. Many enveloped viruses, such as HIV and influenza virus, co-opt the ER-associated protein biosynthetic machinery to translate their genome and produce structural proteins that are necessary for the formation of virus particles and non-structural proteins that are essential during genome replication. Replication of the viral genome, particularly for positive-sense RNA ((+)RNA) viruses including hepatitis C virus (HCV), dengue virus (DENV) and West Nile virus (WNV), occurs in virus-induced membranous structures that are most often derived from the ER. The formation of these structures requires morphological changes to the ER membrane, involving membrane rearrangements that are induced by viral non-structural proteins that are targeted to the ER. As virus assembly is often coupled to genome replication, the assembly process frequently relies on the ER membrane. This strategy is seen for both RNA and DNA viruses. Morphogenesis of assembled virus particles can also take advantage of the ER. This is best observed in the non-enveloped rotavirus, for which a transient enveloped intermediate is converted to the mature and infectious particle in the lumen of the ER. After maturation in the ER, progeny virus particles egress the host through the ER-dependent secretory pathway, which provides a physical conduit to the extracellular environment. The overall observations that the ER actively promotes all steps of viral infection have therapeutic implications. The development of chemical inhibitors of selective ER-associated components is emerging as a potential avenue of antiviral therapy, provided that these inhibitors have minimal toxicity to the host cell.
Many host structures are vital for viral infection and the endoplasmic reticulum (ER), in particular, is essential. In this Review, Tsai and colleagues highlight examples of subversion of the ER by diverse viruses to promote all stages of their life cycle, from entry to egress. Viruses subvert the functions of their host cells to replicate and form new viral progeny. The endoplasmic reticulum (ER) has been identified as a central organelle that governs the intracellular interplay between viruses and hosts. In this Review, we analyse how viruses from vastly different families converge on this unique intracellular organelle during infection, co-opting some of the endogenous functions of the ER to promote distinct steps of the viral life cycle from entry and replication to assembly and egress. The ER can act as the common denominator during infection for diverse virus families, thereby providing a shared principle that underlies the apparent complexity of relationships between viruses and host cells. As a plethora of information illuminating the molecular and cellular basis of virus–ER interactions has become available, these insights may lead to the development of crucial therapeutic agents.
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Affiliation(s)
- Madhu Sudhan Ravindran
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Room 3043, Ann Arbor, Michigan 48109, USA
| | - Parikshit Bagchi
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Room 3043, Ann Arbor, Michigan 48109, USA
| | - Corey Nathaniel Cunningham
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Room 3043, Ann Arbor, Michigan 48109, USA
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Room 3043, Ann Arbor, Michigan 48109, USA
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74
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Joedicke L, Trenker R, Langer JD, Michel H, Preu J. Cell-free synthesis of isotopically labelled peptide ligands for the functional characterization of G protein-coupled receptors. FEBS Open Bio 2015; 6:90-102. [PMID: 27047736 PMCID: PMC4794788 DOI: 10.1002/2211-5463.12008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 12/03/2015] [Accepted: 12/04/2015] [Indexed: 11/24/2022] Open
Abstract
Cell‐free systems exploit the transcription and translation machinery of cells from different origins to produce proteins in a defined chemical environment. Due to its open nature, cell‐free protein production is a versatile tool to introduce specific labels such as heavy isotopes, non‐natural amino acids and tags into the protein while avoiding cell toxicity. In particular, radiolabelled peptides and proteins are valuable tools for the functional characterization of protein–protein interactions and for studying binding kinetics. In this study we evaluated cell‐free protein production for the generation of radiolabelled ligands for G protein‐coupled receptors (GPCRs). These receptors are seven‐transmembrane‐domain receptors activated by a plethora of extracellular stimuli including peptide ligands. Many GPCR peptide ligands contain disulphide bonds and are thus inherently difficult to produce in bacterial expression hosts or in Escherichia coli‐based cell‐free systems. Here, we established an adapted E. coli‐based cell‐free translation system for the production of disulphide bond‐containing GPCR peptide ligands and specifically introduce tritium labels for detection. The bacterial oxidoreductase DsbA is used as a chaperone to favour the formation of disulphide bonds and to enhance the yield of correctly folded proteins and peptides. We demonstrate the correct folding and formation of disulphide bonds and show high‐affinity ligand binding of the produced radio peptide ligands to the respective receptors. Thus, our system allows the fast, cost‐effective and reliable synthesis of custom GPCR peptide ligands for functional and structural studies.
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Affiliation(s)
- Lisa Joedicke
- Department of Molecular Membrane Biology Max Planck Institute of Biophysics Frankfurt am Main Germany
| | - Raphael Trenker
- Department of Molecular Membrane Biology Max Planck Institute of Biophysics Frankfurt am Main Germany
| | - Julian D Langer
- Department of Molecular Membrane Biology Max Planck Institute of Biophysics Frankfurt am Main Germany
| | - Hartmut Michel
- Department of Molecular Membrane Biology Max Planck Institute of Biophysics Frankfurt am Main Germany
| | - Julia Preu
- Department of Molecular Membrane Biology Max Planck Institute of Biophysics Frankfurt am Main Germany
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75
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Pisoni GB, Ruddock LW, Bulleid N, Molinari M. Division of labor among oxidoreductases: TMX1 preferentially acts on transmembrane polypeptides. Mol Biol Cell 2015; 26:3390-400. [PMID: 26246604 PMCID: PMC4591685 DOI: 10.1091/mbc.e15-05-0321] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 07/29/2015] [Indexed: 01/18/2023] Open
Abstract
The mammalian ER contains 23 members of the PDI superfamily. Their substrate specificity is largely unknown. TMX1 shows a preference for membrane-bound, cysteine-containing polypeptides. The endoplasmic reticulum (ER) is the site of maturation for secretory and membrane proteins in eukaryotic cells. The lumen of the mammalian ER contains >20 members of the protein disulfide isomerase (PDI) superfamily, which ensure formation of the correct set of intramolecular and intermolecular disulfide bonds as crucial, rate-limiting reactions of the protein folding process. Components of the PDI superfamily may also facilitate dislocation of misfolded polypeptides across the ER membrane for ER-associated degradation (ERAD). The reasons for the high redundancy of PDI family members and the substrate features required for preferential engagement of one or the other are poorly understood. Here we show that TMX1, one of the few transmembrane members of the family, forms functional complexes with the ER lectin calnexin and preferentially intervenes during maturation of cysteine-containing, membrane-associated proteins while ignoring the same cysteine-containing ectodomains if not anchored at the ER membrane. As such, TMX1 is the first example of a topology-specific client protein redox catalyst in living cells.
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Affiliation(s)
- Giorgia Brambilla Pisoni
- Institute for Research in Biomedicine, CH-6500 Bellinzona, Switzerland Università della Svizzera Italiana, CH-6900 Lugano, Switzerland
| | - Lloyd W Ruddock
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, 90014 Oulu, Finland
| | - Neil Bulleid
- Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Maurizio Molinari
- Institute for Research in Biomedicine, CH-6500 Bellinzona, Switzerland Università della Svizzera Italiana, CH-6900 Lugano, Switzerland Ecole Polytechnique Fédérale de Lausanne, School of Life Sciences, CH-1015 Lausanne, Switzerland
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76
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Lortz S, Lenzen S, Mehmeti I. Impact of scavenging hydrogen peroxide in the endoplasmic reticulum for β cell function. J Mol Endocrinol 2015; 55:21-9. [PMID: 26108484 DOI: 10.1530/jme-15-0132] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/15/2015] [Indexed: 12/19/2022]
Abstract
Oxidative folding of nascent proteins in the endoplasmic reticulum (ER), catalysed by one or more members of the protein disulfide isomerase family and the sulfhydryl oxidase ER oxidoreductin 1 (ERO1), is accompanied by generation of hydrogen peroxide (H2O2). Because of the high rate of insulin biosynthesis and the low expression of H2O2-inactivating enzymes in pancreatic β cells, it has been proposed that the luminal H2O2 concentration might be very high. As the role of this H2O2 in ER stress and proinsulin processing is still unsolved, an ER-targeted and luminal-active catalase variant, ER-Catalase N244, was expressed in insulin-secreting INS-1E cells. In these cells, the influence of ER-specific H2O2 removal on cytokine-mediated cytotoxicity and ER stress, insulin gene expression, insulin content and secretion was analysed. The expression of ER-Catalase N244 reduced the toxicity of exogenously added H2O2 significantly with a threefold increase of the EC50 value for H2O2. However, the expression of cytokine-induced ER stress genes and viability after incubation with β cell toxic cytokines (IL1β alone or together with TNFα+IFNγ) was not affected by ER-Catalase N244. In control and ER-Catalase N244 expressing cells, insulin secretion and proinsulin content was identical, while removal of luminal H2O2 reduced insulin gene expression and insulin content in ER-Catalase N244 expressing cells. These data show that ER-Catalase N244 reduced H2O2 toxicity but did not provide protection against pro-inflammatory cytokine-mediated toxicity and ER stress. Insulin secretion was not affected by decreasing H2O2 in the ER in spite of a reduced insulin transcription and processing.
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Affiliation(s)
- S Lortz
- Hannover Medical SchoolInstitute of Clinical Biochemistry, 30623 Hannover, Germany
| | - S Lenzen
- Hannover Medical SchoolInstitute of Clinical Biochemistry, 30623 Hannover, Germany
| | - I Mehmeti
- Hannover Medical SchoolInstitute of Clinical Biochemistry, 30623 Hannover, Germany
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77
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Thiol-disulfide exchange between the PDI family of oxidoreductases negates the requirement for an oxidase or reductase for each enzyme. Biochem J 2015; 469:279-88. [PMID: 25989104 PMCID: PMC4613490 DOI: 10.1042/bj20141423] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 05/19/2015] [Indexed: 01/20/2023]
Abstract
The PDI family form disulfide bridges in substrates via thiol-disulfide exchange reactions. We show in the present study that disulfide exchange can occur directly between individual PDI proteins. Implication is that only certain members need to be oxidized or reduced to maintain function. The formation of disulfides in proteins entering the secretory pathway is catalysed by the protein disulfide isomerase (PDI) family of enzymes. These enzymes catalyse the introduction, reduction and isomerization of disulfides. To function continuously they require an oxidase to reform the disulfide at their active site. To determine how each family member can be recycled to catalyse disulfide exchange, we have studied whether disulfides are transferred between individual PDI family members. We studied disulfide exchange either between purified proteins or by identifying mixed disulfide formation within cells grown in culture. We show that disulfide exchange occurs efficiently and reversibly between specific PDIs. These results have allowed us to define a hierarchy for members of the PDI family, in terms of ability to act as electron acceptors or donors during thiol-disulfide exchange reactions and indicate that there is no kinetic barrier to the exchange of disulfides between several PDI proteins. Such promiscuous disulfide exchange negates the necessity for each enzyme to be oxidized by Ero1 (ER oxidoreductin 1) or reduced by a reductive system. The lack of kinetic separation of the oxidative and reductive pathways in mammalian cells contrasts sharply with the equivalent systems for native disulfide formation within the bacterial periplasm.
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78
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Sun J, Cui J, He Q, Chen Z, Arvan P, Liu M. Proinsulin misfolding and endoplasmic reticulum stress during the development and progression of diabetes. Mol Aspects Med 2015; 42:105-18. [PMID: 25579745 PMCID: PMC4404191 DOI: 10.1016/j.mam.2015.01.001] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 12/31/2014] [Accepted: 01/02/2015] [Indexed: 02/06/2023]
Abstract
To maintain copious insulin granule stores in the face of ongoing metabolic demand, pancreatic beta cells must produce large quantities of proinsulin, the insulin precursor. Proinsulin biosynthesis can account for up to 30-50% of total cellular protein synthesis of beta cells. This puts pressure on the beta cell secretory pathway, especially the endoplasmic reticulum (ER), where proinsulin undergoes its initial folding, including the formation of three evolutionarily conserved disulfide bonds. In normal beta cells, up to 20% of newly synthesized proinsulin may fail to reach its native conformation, suggesting that proinsulin is a misfolding-prone protein. Misfolded proinsulin molecules can either be refolded to their native structure or degraded through ER associated degradation (ERAD) and autophagy. These degraded molecules decrease proinsulin yield but do not otherwise compromise beta cell function. However, under certain pathological conditions, proinsulin misfolding increases, exceeding the genetically determined threshold of beta cells to handle the misfolded protein load. This results in accumulation of misfolded proinsulin in the ER - a causal factor leading to beta cell failure and diabetes. In patients with Mutant INS-gene induced diabetes of Youth (MIDY), increased proinsulin misfolding due to insulin gene mutations is the primary defect operating as a "first hit" to beta cells. Additionally, increased proinsulin misfolding can be secondary to an unfavorable ER folding environment due to genetic and/or environmental factors. Under these conditions, increased wild-type proinsulin misfolding becomes a "second hit" to the ER and beta cells, aggravating beta cell failure and diabetes. In this article, we describe our current understanding of the normal proinsulin folding pathway in the ER, and then review existing links between proinsulin misfolding, ER dysfunction, and beta cell failure in the development and progression of type 2, type 1, and some monogenic forms of diabetes.
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Affiliation(s)
- Jinhong Sun
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan, Ann Arbor, MI 48105, USA
| | - Jingqiu Cui
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Qing He
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Zheng Chen
- School of Life Sciences, Northeast Normal University, Changchun, Jilin 130024, China
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan, Ann Arbor, MI 48105, USA.
| | - Ming Liu
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan, Ann Arbor, MI 48105, USA; Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China.
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79
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Patil NA, Tailhades J, Hughes RA, Separovic F, Wade JD, Hossain MA. Cellular disulfide bond formation in bioactive peptides and proteins. Int J Mol Sci 2015; 16:1791-805. [PMID: 25594871 PMCID: PMC4307334 DOI: 10.3390/ijms16011791] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/02/2015] [Indexed: 11/16/2022] Open
Abstract
Bioactive peptides play important roles in metabolic regulation and modulation and many are used as therapeutics. These peptides often possess disulfide bonds, which are important for their structure, function and stability. A systematic network of enzymes--a disulfide bond generating enzyme, a disulfide bond donor enzyme and a redox cofactor--that function inside the cell dictates the formation and maintenance of disulfide bonds. The main pathways that catalyze disulfide bond formation in peptides and proteins in prokaryotes and eukaryotes are remarkably similar and share several mechanistic features. This review summarizes the formation of disulfide bonds in peptides and proteins by cellular and recombinant machinery.
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Affiliation(s)
- Nitin A Patil
- Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Victoria 3010, Australia.
| | - Julien Tailhades
- Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Victoria 3010, Australia.
| | - Richard Anthony Hughes
- Department of Pharmacology and Therapeutics, the University of Melbourne, Victoria 3010, Australia.
| | - Frances Separovic
- School of Chemistry, the University of Melbourne, Victoria 3010, Australia.
| | - John D Wade
- Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Victoria 3010, Australia.
| | - Mohammed Akhter Hossain
- Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Victoria 3010, Australia.
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80
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Abstract
In mammalian cells, the rough endoplasmic reticulum or ER plays a central role in the biogenesis of most extracellular plus many organellar proteins and in cellular calcium homeostasis. Therefore, this organelle comprises molecular chaperones that are involved in import, folding/assembly, export, and degradation of polypeptides in millimolar concentrations. In addition, there are calcium channels/pumps and signal transduction components present in the ER membrane that affect and are affected by these processes. The ER lumenal Hsp70, termed immunoglobulin-heavy chain binding protein or BiP, is the central player in all these activities and involves up to seven different co-chaperones, i.e. ER-membrane integrated as well as ER-lumenal Hsp40s, which are termed ERj or ERdj, and two nucleotide exchange factors.
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81
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Liu M, Sun J, Cui J, Chen W, Guo H, Barbetti F, Arvan P. INS-gene mutations: from genetics and beta cell biology to clinical disease. Mol Aspects Med 2014; 42:3-18. [PMID: 25542748 DOI: 10.1016/j.mam.2014.12.001] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 12/02/2014] [Accepted: 12/04/2014] [Indexed: 02/06/2023]
Abstract
A growing list of insulin gene mutations causing a new form of monogenic diabetes has drawn increasing attention over the past seven years. The mutations have been identified in the untranslated regions of the insulin gene as well as the coding sequence of preproinsulin including within the signal peptide, insulin B-chain, C-peptide, insulin A-chain, and the proteolytic cleavage sites both for signal peptidase and the prohormone convertases. These mutations affect a variety of different steps of insulin biosynthesis in pancreatic beta cells. Importantly, although many of these mutations cause proinsulin misfolding with early onset autosomal dominant diabetes, some of the mutant alleles appear to engage different cellular and molecular mechanisms that underlie beta cell failure and diabetes. In this article, we review the most recent advances in the field and discuss challenges as well as potential strategies to prevent/delay the development and progression of autosomal dominant diabetes caused by INS-gene mutations. It is worth noting that although diabetes caused by INS gene mutations is rare, increasing evidence suggests that defects in the pathway of insulin biosynthesis may also be involved in the progression of more common types of diabetes. Collectively, the (pre)proinsulin mutants provide insightful molecular models to better understand the pathogenesis of all forms of diabetes in which preproinsulin processing defects, proinsulin misfolding, and ER stress are involved.
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Affiliation(s)
- Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, 300052, China; Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, 48105, USA.
| | - Jinhong Sun
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, 48105, USA
| | - Jinqiu Cui
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Wei Chen
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, 48105, USA
| | - Huan Guo
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, 48105, USA
| | - Fabrizio Barbetti
- Department of Experimental Medicine, University of Tor Vergata, Rome and Bambino Gesù Children's Hospital, Rome, Italy
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, 48105, USA.
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82
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Fox RM, Andrew DJ. Transcriptional regulation of secretory capacity by bZip transcription factors. ACTA ACUST UNITED AC 2014; 10:28-51. [PMID: 25821458 PMCID: PMC4374484 DOI: 10.1007/s11515-014-1338-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cells of specialized secretory organs expand their secretory pathways to accommodate the increased protein load necessary for their function. The endoplasmic reticulum (ER), the Golgi apparatus and the secretory vesicles, expand not only the membrane components but also the protein machinery required for increased protein production and transport. Increased protein load causes an ER stress response akin to the Unfolded Protein Response (UPR). Recent work has implicated several bZip transcription factors in the regulation of protein components of the early secretory pathway necessary to alleviate this stress. Here, we highlight eight bZip transcription factors in regulating secretory pathway component genes. These include components of the three canonical branches of the UPR-ATF4, XBP1, and ATF6, as well as the five members of the Creb3 family of transcription factors.We review findings from both invertebrate and vertebrate model systems suggesting that all of these proteins increase secretory capacity in response to increased protein load. Finally, we propose that the Creb3 family of factors may have a dual role in secretory cell differentiation by also regulating the pathways necessary for cell cycle exit during terminal differentiation.
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Affiliation(s)
- Rebecca M Fox
- The Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Deborah J Andrew
- The Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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83
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Abstract
The endoplasmic reticulum (ER) is a cellular compartment that has a key function in protein translation and folding. Maintaining its integrity is of fundamental importance for organism's physiology and viability. The dynamic regulation of intraluminal ER Ca(2+) concentration directly influences the activity of ER-resident chaperones and stress response pathways that balance protein load and folding capacity. We review the emerging evidence that microRNAs play important roles in adjusting these processes to frequently changing intracellular and environmental conditions to modify ER Ca(2+) handling and storage and maintain ER homeostasis.
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Affiliation(s)
- Fabian Finger
- Institute for Genetics and Cologne Cluster of Excellence Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Thorsten Hoppe
- Institute for Genetics and Cologne Cluster of Excellence Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany.
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84
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Regulating the level of intracellular hydrogen peroxide: the role of peroxiredoxin IV. Biochem Soc Trans 2014; 42:42-6. [PMID: 24450625 DOI: 10.1042/bst20130168] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Hydrogen peroxide (H2O2) can act as a signalling molecule affecting the cell cycle as well as contributing towards the oxidative stress response. The primary target of this molecule is oxidation-sensitive cysteine residues in proteins such as protein tyrosine phosphatases. The cell has robust mechanisms to remove H2O2 that need to be regulated for H2O2 to react with and modify protein thiols. In particular, the family of peroxiredoxins are capable of the rapid removal of even trace amounts of this molecule. It has been suggested that the inactivation of peroxiredoxins by hyperoxidation may allow H2O2 levels to increase in cells and thereby modify critical thiol groups in proteins. We have been studying how the H2O2 produced during disulfide formation in the ER (endoplasmic reticulum) is metabolized and have shown that ER-resident peroxiredoxin IV not only can remove H2O2, but also contributes to de novo disulfide formation. In the present article, we review recent data on the structure and function of this enzyme as well as its sensitivity to hyperoxidation.
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85
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Reissner C, Stahn J, Breuer D, Klose M, Pohlentz G, Mormann M, Missler M. Dystroglycan binding to α-neurexin competes with neurexophilin-1 and neuroligin in the brain. J Biol Chem 2014; 289:27585-603. [PMID: 25157101 PMCID: PMC4183798 DOI: 10.1074/jbc.m114.595413] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
α-Neurexins (α-Nrxn) are mostly presynaptic cell surface molecules essential for neurotransmission that are linked to neuro-developmental disorders as autism or schizophrenia. Several interaction partners of α-Nrxn are identified that depend on alternative splicing, including neuroligins (Nlgn) and dystroglycan (αDAG). The trans-synaptic complex with Nlgn1 was extensively characterized and shown to partially mediate α-Nrxn function. However, the interactions of α-Nrxn with αDAG, neurexophilins (Nxph1) and Nlgn2, ligands that occur specifically at inhibitory synapses, are incompletely understood. Using site-directed mutagenesis, we demonstrate the exact binding epitopes of αDAG and Nxph1 on Nrxn1α and show that their binding is mutually exclusive. Identification of an unusual cysteine bridge pattern and complex type glycans in Nxph1 ensure binding to the second laminin/neurexin/sex hormone binding (LNS2) domain of Nrxn1α, but this association does not interfere with Nlgn binding at LNS6. αDAG, in contrast, interacts with both LNS2 and LNS6 domains without inserts in splice sites SS#2 or SS#4 mostly via LARGE (like-acetylglucosaminyltransferase)-dependent glycans attached to the mucin region. Unexpectedly, binding of αDAG at LNS2 prevents interaction of Nlgn at LNS6 with or without splice insert in SS#4, presumably by sterically hindering each other in the u-form conformation of α-Nrxn. Thus, expression of αDAG and Nxph1 together with alternative splicing in Nrxn1α may prevent or facilitate formation of distinct trans-synaptic Nrxn·Nlgn complexes, revealing an unanticipated way to contribute to the identity of synaptic subpopulations.
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Affiliation(s)
- Carsten Reissner
- From the Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Vesaliusweg 2-4, 48149 Münster, Germany
| | - Johanna Stahn
- From the Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Vesaliusweg 2-4, 48149 Münster, Germany
| | - Dorothee Breuer
- From the Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Vesaliusweg 2-4, 48149 Münster, Germany
| | - Martin Klose
- From the Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Vesaliusweg 2-4, 48149 Münster, Germany
| | - Gottfried Pohlentz
- Institute of Medical Physics and Biophysics, Westfälische Wilhelms-University, Robert-Koch Strasse 31, 48149 Münster, Germany, and
| | - Michael Mormann
- Institute of Medical Physics and Biophysics, Westfälische Wilhelms-University, Robert-Koch Strasse 31, 48149 Münster, Germany, and
| | - Markus Missler
- From the Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, Vesaliusweg 2-4, 48149 Münster, Germany, Cluster of Excellence EXC 1003, Cells in Motion, 48149 Münster, Germany
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86
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Haßdenteufel S, Klein MC, Melnyk A, Zimmermann R. Protein transport into the human ER and related diseases, Sec61-channelopathies. Biochem Cell Biol 2014; 92:499-509. [PMID: 24934166 DOI: 10.1139/bcb-2014-0043] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Protein transport into the human endoplasmic reticulum (ER) is relevant to the biogenesis of most soluble and membrane proteins of organelles, which are involved in endo- or exo-cytsosis. It involves amino-terminal signal peptides in the precursor polypeptides and various transport components in the cytosol plus the ER, and can occur co- or post-translationally. The two mechanisms merge at the level of the ER membrane, specifically at the level of the heterotrimeric Sec61 complex, which forms a dynamic polypeptide-conducting channel in the ER membrane. Since the mammalian ER is also the main intracellular calcium storage organelle, and the Sec61 complex is calcium permeable, the Sec61 complex is tightly regulated in its equilibrium between the closed and open conformations, or "gated", by ligands, such as signal peptides of the transport substrates and the ER lumenal Hsp70-type molecular chaperone BiP. Furthermore, BiP binding to the incoming polypeptide contributes to the efficiency and unidirectionality of transport. Recent insights into the structure and dynamic equilibrium of the Sec61 complex have various mechanistic as well as medical implications.
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Affiliation(s)
- Sarah Haßdenteufel
- Medical Biochemistry & Molecular Biology, Saarland University, Building 44, Kirrbergerstr, D-66421 Homburg, Germany
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87
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Frump AL, Lowery JW, Hamid R, Austin ED, de Caestecker M. Abnormal trafficking of endogenously expressed BMPR2 mutant allelic products in patients with heritable pulmonary arterial hypertension. PLoS One 2013; 8:e80319. [PMID: 24224048 PMCID: PMC3818254 DOI: 10.1371/journal.pone.0080319] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/07/2013] [Indexed: 12/28/2022] Open
Abstract
More than 200 heterozygous mutations in the type 2 BMP receptor gene, BMPR2, have been identified in patients with Heritable Pulmonary Arterial Hypertension (HPAH). More severe clinical outcomes occur in patients with BMPR2 mutations by-passing nonsense-mediated mRNA decay (NMD negative mutations). These comprise 40% of HPAH mutations and are predicted to express BMPR2 mutant products. However expression of endogenous NMD negative BMPR2 mutant products and their effect on protein trafficking and signaling function have never been described. Here, we characterize the expression and trafficking of an HPAH-associated NMD negative BMPR2 mutation that results in an in-frame deletion of BMPR2 EXON2 (BMPR2ΔEx2) in HPAH patient-derived lymphocytes and in pulmonary endothelial cells (PECs) from mice carrying the same in-frame deletion of Exon 2 (Bmpr2 (ΔEx2/+) mice). The endogenous BMPR2ΔEx2 mutant product does not reach the cell surface and is retained in the endoplasmic reticulum. Moreover, chemical chaperones 4-PBA and TUDCA partially restore cell surface expression of Bmpr2ΔEx2 in PECs, suggesting that the mutant product is mis-folded. We also show that PECs from Bmpr2 (ΔEx2/+) mice have defects in the BMP-induced Smad1/5/8 and Id1 signaling axis, and that addition of chemical chaperones restores expression of the Smad1/5/8 target Id1. These data indicate that the endogenous NMD negative BMPRΔEx2 mutant product is expressed but has a folding defect resulting in ER retention. Partial correction of this folding defect and restoration of defective BMP signaling using chemical chaperones suggests that protein-folding agents could be used therapeutically in patients with these NMD negative BMPR2 mutations.
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Affiliation(s)
- Andrea L. Frump
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jonathan W. Lowery
- Department of Developmental Biology, Harvard University School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Rizwan Hamid
- Department of Pediatrics, Division of Molecular Genetics and Genomic Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Eric D. Austin
- Department of Pediatrics, Division of Pediatric Pulmonary Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Mark de Caestecker
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- *E-mail:
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88
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ERdj5 is the ER reductase that catalyzes the removal of non-native disulfides and correct folding of the LDL receptor. Mol Cell 2013; 50:793-804. [PMID: 23769672 PMCID: PMC3906653 DOI: 10.1016/j.molcel.2013.05.014] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 04/03/2013] [Accepted: 05/08/2013] [Indexed: 02/08/2023]
Abstract
ERdj5 is a member of the protein disulfide isomerase family of proteins localized to the endoplasmic reticulum (ER) of mammalian cells. To date, only a limited number of substrates for ERdj5 are known. Here we identify a number of endogenous substrates that form mixed disulfides with ERdj5, greatly expanding its client repertoire. ERdj5 previously had been thought to exclusively reduce disulfides in proteins destined for dislocation to the cytosol for degradation. However, we demonstrate here that for one of the identified substrates, the low-density lipoprotein receptor (LDLR), ERdj5 is required not for degradation, but rather for efficient folding. Our results demonstrate that the crucial role of ERdj5 is to reduce non-native disulfides formed during productive folding and that this requirement is dependent on its interaction with BiP. Hence, ERdj5 acts as the ER reductase, both preparing misfolded proteins for degradation and catalyzing the folding of proteins that form obligatory non-native disulfides. Several endogenous substrates for ERdj5 have been identified ERdj5 is required for efficient folding and secretion, but not degradation, of LDLR Knockdown of ERdj5 prevents the removal of non-native disulfides ERdj5 needs to interact with BiP to carry out its function during protein folding
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89
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Abstract
In this article, we will cover the folding of proteins in the lumen of the endoplasmic reticulum (ER), including the role of three types of covalent modifications: signal peptide removal, N-linked glycosylation, and disulfide bond formation, as well as the function and importance of resident ER folding factors. These folding factors consist of classical chaperones and their cochaperones, the carbohydrate-binding chaperones, and the folding catalysts of the PDI and proline cis-trans isomerase families. We will conclude with the perspective of the folding protein: a comparison of characteristics and folding and exit rates for proteins that travel through the ER as clients of the ER machinery.
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Affiliation(s)
- Ineke Braakman
- Cellular Protein Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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90
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Ron D, Harding HP. Protein-folding homeostasis in the endoplasmic reticulum and nutritional regulation. Cold Spring Harb Perspect Biol 2012; 4:a013177. [PMID: 23209157 PMCID: PMC3504434 DOI: 10.1101/cshperspect.a013177] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The flux of newly synthesized proteins entering the endoplasmic reticulum (ER) is under negative regulation by the ER-localized PKR-like ER kinase (PERK). PERK is activated by unfolded protein stress in the ER lumen and inhibits new protein synthesis by the phosphorylation of translation initiation factor eIF2α. This homeostatic mechanism, shared by all animal cells, has proven to be especially important to the well-being of professional secretory cells, notably the endocrine pancreas. PERK, its downstream effectors, and the allied branches of the unfolded protein response intersect broadly with signaling pathways that regulate nutrient assimilation, and ER stress and the response to it have been implicated in the development of the metabolic syndrome accompanying obesity in mammals. Here we review our current understanding of the cell biology underlying these relationships.
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Affiliation(s)
- David Ron
- Metabolic Research Laboratories, University of Cambridge, and NIHR Cambridge Biomedical Research Centre, Addenbrookes Hospital, Cambridge CB2 0QQ, United Kingdom.
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