1
|
Reinhard J, Starke L, Klose C, Haberkant P, Hammarén H, Stein F, Klein O, Berhorst C, Stumpf H, Sáenz JP, Hub J, Schuldiner M, Ernst R. MemPrep, a new technology for isolating organellar membranes provides fingerprints of lipid bilayer stress. EMBO J 2024; 43:1653-1685. [PMID: 38491296 PMCID: PMC11021466 DOI: 10.1038/s44318-024-00063-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 02/16/2024] [Accepted: 02/26/2024] [Indexed: 03/18/2024] Open
Abstract
Biological membranes have a stunning ability to adapt their composition in response to physiological stress and metabolic challenges. Little is known how such perturbations affect individual organelles in eukaryotic cells. Pioneering work has provided insights into the subcellular distribution of lipids in the yeast Saccharomyces cerevisiae, but the composition of the endoplasmic reticulum (ER) membrane, which also crucially regulates lipid metabolism and the unfolded protein response, remains insufficiently characterized. Here, we describe a method for purifying organelle membranes from yeast, MemPrep. We demonstrate the purity of our ER membrane preparations by proteomics, and document the general utility of MemPrep by isolating vacuolar membranes. Quantitative lipidomics establishes the lipid composition of the ER and the vacuolar membrane. Our findings provide a baseline for studying membrane protein biogenesis and have important implications for understanding the role of lipids in regulating the unfolded protein response (UPR). The combined preparative and analytical MemPrep approach uncovers dynamic remodeling of ER membranes in stressed cells and establishes distinct molecular fingerprints of lipid bilayer stress.
Collapse
Affiliation(s)
- John Reinhard
- Saarland University, Medical Biochemistry and Molecular Biology, Homburg, Germany
- Saarland University, Preclinical Center for Molecular Signaling (PZMS), Homburg, Germany
| | - Leonhard Starke
- Saarland University, Theoretical Physics and Center for Biophysics, Saarbrücken, Germany
| | | | - Per Haberkant
- EMBL Heidelberg, Proteomics Core Facility, Heidelberg, Germany
| | | | - Frank Stein
- EMBL Heidelberg, Proteomics Core Facility, Heidelberg, Germany
| | - Ofir Klein
- Weizmann Institute of Science, Department of Molecular Genetics, Rehovot, Israel
| | - Charlotte Berhorst
- Saarland University, Medical Biochemistry and Molecular Biology, Homburg, Germany
- Saarland University, Preclinical Center for Molecular Signaling (PZMS), Homburg, Germany
| | - Heike Stumpf
- Saarland University, Medical Biochemistry and Molecular Biology, Homburg, Germany
- Saarland University, Preclinical Center for Molecular Signaling (PZMS), Homburg, Germany
| | - James P Sáenz
- Technische Universität Dresden, B CUBE, Dresden, Germany
| | - Jochen Hub
- Saarland University, Theoretical Physics and Center for Biophysics, Saarbrücken, Germany
| | - Maya Schuldiner
- Weizmann Institute of Science, Department of Molecular Genetics, Rehovot, Israel
| | - Robert Ernst
- Saarland University, Medical Biochemistry and Molecular Biology, Homburg, Germany.
- Saarland University, Preclinical Center for Molecular Signaling (PZMS), Homburg, Germany.
| |
Collapse
|
2
|
Renne MF, Ernst R. ERMES - from myths to molecules. Nat Rev Mol Cell Biol 2024; 25:161. [PMID: 37857894 DOI: 10.1038/s41580-023-00677-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Affiliation(s)
- Mike F Renne
- Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany.
| | - Robert Ernst
- Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany.
| |
Collapse
|
3
|
Moller E, Britt M, Zhou F, Yang H, Anshkin A, Ernst R, Sukharev S, Matthies D. Polymer-extracted structure of the mechanosensitive channel MscS reveals the role of protein-lipid interactions in the gating cycle. bioRxiv 2024:2024.01.22.576751. [PMID: 38328078 PMCID: PMC10849555 DOI: 10.1101/2024.01.22.576751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Membrane protein structure determination is not only technically challenging but is further complicated by the removal or displacement of lipids, which can result in non-native conformations or a strong preference for certain states at the exclusion of others. This is especially applicable to mechanosensitive channels (MSC's) that evolved to gate in response to subtle changes in membrane tension transmitted through the lipid bilayer. E. coli MscS, a model bacterial system, is an ancestral member of the large family of MSCs found across all phyla of walled organisms. As a tension sensor, MscS is very sensitive and highly adaptive; it readily opens under super-threshold tension and closes under no tension, but under lower tensions, it slowly inactivates and can only recover when tension is released. However, existing cryo-EM structures do not explain the entire functional gating cycle of open, closed, and inactivated states. A central question in the field has been the assignment of the frequently observed non-conductive conformation to either a closed or inactivated state. Here, we present a 3 Å MscS structure in native nanodiscs obtained with Glyco-DIBMA polymer extraction, eliminating the lipid removal step that is common to all previous structures. Besides the protein in the non-conductive conformation, we observe well-resolved densities of four endogenous phospholipid molecules intercalating between the lipid-facing and pore-lining helices in preferred orientations. Mutations of positively charged residues coordinating these lipids inhibit MscS inactivation, whereas removal of a negative charge near the lipid-filled crevice increases inactivation. The functional data allows us to assign this class of structures to the inactivated state. This structure reveals preserved lipids in their native locations, and the functional effects of their destabilization illustrate a novel inactivation mechanism based on an uncoupling of the peripheral tension-sensing helices from the gate.
Collapse
|
4
|
Ernst R, Renne MF, Jain A, von der Malsburg A. Endoplasmic Reticulum Membrane Homeostasis and the Unfolded Protein Response. Cold Spring Harb Perspect Biol 2024:a041400. [PMID: 38253414 DOI: 10.1101/cshperspect.a041400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The endoplasmic reticulum (ER) is the key organelle for membrane biogenesis. Most lipids are synthesized in the ER, and most membrane proteins are first inserted into the ER membrane before they are transported to their target organelle. The composition and properties of the ER membrane must be carefully controlled to provide a suitable environment for the insertion and folding of membrane proteins. The unfolded protein response (UPR) is a powerful signaling pathway that balances protein and lipid production in the ER. Here, we summarize our current knowledge of how aberrant compositions of the ER membrane, referred to as lipid bilayer stress, trigger the UPR.
Collapse
Affiliation(s)
- Robert Ernst
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, 66421 Homburg, Germany
- Preclinical Center for Molecular Signaling (PZMS), Medical Faculty, Saarland University, 66421 Homburg, Germany
| | - Mike F Renne
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, 66421 Homburg, Germany
- Preclinical Center for Molecular Signaling (PZMS), Medical Faculty, Saarland University, 66421 Homburg, Germany
| | - Aamna Jain
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, 66421 Homburg, Germany
- Preclinical Center for Molecular Signaling (PZMS), Medical Faculty, Saarland University, 66421 Homburg, Germany
| | - Alexander von der Malsburg
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, 66421 Homburg, Germany
- Preclinical Center for Molecular Signaling (PZMS), Medical Faculty, Saarland University, 66421 Homburg, Germany
| |
Collapse
|
5
|
Renne MF, Ernst R. Membrane homeostasis beyond fluidity: control of membrane compressibility. Trends Biochem Sci 2023; 48:963-977. [PMID: 37652754 PMCID: PMC10580326 DOI: 10.1016/j.tibs.2023.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 09/02/2023]
Abstract
Biomembranes are complex materials composed of lipids and proteins that compartmentalize biochemistry. They are actively remodeled in response to physical and metabolic cues, as well as during cell differentiation and stress. The concept of homeoviscous adaptation has become a textbook example of membrane responsiveness. Here, we discuss limitations and common misconceptions revolving around it. By highlighting key moments in the life cycle of a transmembrane protein, we illustrate that membrane thickness and a finely regulated membrane compressibility are crucial to facilitate proper membrane protein insertion, function, sorting, and inheritance. We propose that the unfolded protein response (UPR) provides a mechanism for endoplasmic reticulum (ER) membrane homeostasis by sensing aberrant transverse membrane stiffening and triggering adaptive responses that re-establish membrane compressibility.
Collapse
Affiliation(s)
- Mike F Renne
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany; PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany.
| | - Robert Ernst
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany; PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany.
| |
Collapse
|
6
|
Harms FL, Dingemans AJM, Hempel M, Pfundt R, Bierhals T, Casar C, Müller C, Niermeijer JMF, Fischer J, Jahn A, Hübner C, Majore S, Agolini E, Novelli A, van der Smagt J, Ernst R, van Binsbergen E, Mancini GMS, van Slegtenhorst M, Barakat TS, Wakeling EL, Kamath A, Downie L, Pais L, White SM, de Vries BBA, Kutsche K. De novo PHF5A variants are associated with craniofacial abnormalities, developmental delay, and hypospadias. Genet Med 2023; 25:100964. [PMID: 37728613 DOI: 10.1016/j.gim.2023.100964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2023] Open
Affiliation(s)
- Frederike L Harms
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Alexander J M Dingemans
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Maja Hempel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Institute of Human Genetics, University Hospital Heidelberg, Heidelberg, Germany
| | - Rolph Pfundt
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Tatjana Bierhals
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Casar
- Bioinformatics Core, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Müller
- Bioinformatics Core, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Jan Fischer
- Institute for Clinical Genetics, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Arne Jahn
- Institute for Clinical Genetics, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Christoph Hübner
- Department of Neuropaediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Silvia Majore
- Division of Medical Genetics, Department of Experimental Medicine, San Camillo-Forlanini Hospital, Sapienza University, Rome, Italy
| | - Emanuele Agolini
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children Hospital, IRCCS, Rome, Italy
| | - Antonio Novelli
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children Hospital, IRCCS, Rome, Italy
| | - Jasper van der Smagt
- Department of Genetics, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Robert Ernst
- Department of Genetics, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Ellen van Binsbergen
- Department of Genetics, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands; Discovery Unit, Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Emma L Wakeling
- North East Thames Regional Genetic Service, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, United Kingdom
| | - Arveen Kamath
- All Wales Medical Genomics Service/Pennaeth Labordy Genomeg Cymru Gyfan, University Hospital of Wales, Heath Park, Cardiff, United Kingdom
| | - Lilian Downie
- Victorian Clinical Genetics Service, Murdoch Children's Research Institute, Victoria, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Lynn Pais
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
| | - Susan M White
- Victorian Clinical Genetics Service, Murdoch Children's Research Institute, Victoria, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Bert B A de Vries
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| |
Collapse
|
7
|
Harms FL, Dingemans AJM, Hempel M, Pfundt R, Bierhals T, Casar C, Müller C, Niermeijer JMF, Fischer J, Jahn A, Hübner C, Majore S, Agolini E, Novelli A, van der Smagt J, Ernst R, van Binsbergen E, Mancini GMS, van Slegtenhorst M, Barakat TS, Wakeling EL, Kamath A, Downie L, Pais L, White SM, de Vries BBA, Kutsche K. De novo PHF5A variants are associated with craniofacial abnormalities, developmental delay, and hypospadias. Genet Med 2023; 25:100927. [PMID: 37422718 DOI: 10.1016/j.gim.2023.100927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 06/30/2023] [Accepted: 07/02/2023] [Indexed: 07/10/2023] Open
Abstract
PURPOSE The SF3B splicing complex is composed of SF3B1-6 and PHF5A. We report a developmental disorder caused by de novo variants in PHF5A. METHODS Clinical, genomic, and functional studies using subject-derived fibroblasts and a heterologous cellular system were performed. RESULTS We studied 9 subjects with congenital malformations, including preauricular tags and hypospadias, growth abnormalities, and developmental delay who had de novo heterozygous PHF5A variants, including 4 loss-of-function (LOF), 3 missense, 1 splice, and 1 start-loss variant. In subject-derived fibroblasts with PHF5A LOF variants, wild-type and variant PHF5A mRNAs had a 1:1 ratio, and PHF5A mRNA levels were normal. Transcriptome sequencing revealed alternative promoter use and downregulated genes involved in cell-cycle regulation. Subject and control fibroblasts had similar amounts of PHF5A with the predicted wild-type molecular weight and of SF3B1-3 and SF3B6. SF3B complex formation was unaffected in 2 subject cell lines. CONCLUSION Our data suggest the existence of feedback mechanisms in fibroblasts with PHF5A LOF variants to maintain normal levels of SF3B components. These compensatory mechanisms in subject fibroblasts with PHF5A or SF3B4 LOF variants suggest disturbed autoregulation of mutated splicing factor genes in specific cell types, that is, neural crest cells, during embryonic development rather than haploinsufficiency as pathomechanism.
Collapse
Affiliation(s)
- Frederike L Harms
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Alexander J M Dingemans
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Maja Hempel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Institute of Human Genetics, University Hospital Heidelberg, Heidelberg, Germany
| | - Rolph Pfundt
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Tatjana Bierhals
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Casar
- Bioinformatics Core, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Müller
- Bioinformatics Core, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Jan Fischer
- Institute for Clinical Genetics, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Arne Jahn
- Institute for Clinical Genetics, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Christoph Hübner
- Department of Neuropaediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Silvia Majore
- Division of Medical Genetics, Department of Experimental Medicine, San Camillo-Forlanini Hospital, Sapienza University, Rome, Italy
| | - Emanuele Agolini
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children Hospital, IRCCS, Rome, Italy
| | - Antonio Novelli
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children Hospital, IRCCS, Rome, Italy
| | - Jasper van der Smagt
- Department of Genetics, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Robert Ernst
- Department of Genetics, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Ellen van Binsbergen
- Department of Genetics, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands; Discovery Unit, Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Emma L Wakeling
- North East Thames Regional Genetic Service, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, United Kingdom
| | - Arveen Kamath
- All Wales Medical Genomics Service/ Pennaeth Labordy Genomeg Cymru Gyfan, University Hospital of Wales, Heath Park, Cardiff, United Kingdom
| | - Lilian Downie
- Victorian Clinical Genetics Service, Murdoch Children's Research Institute, VIC; Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Lynn Pais
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
| | - Susan M White
- Victorian Clinical Genetics Service, Murdoch Children's Research Institute, VIC; Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Bert B A de Vries
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| |
Collapse
|
8
|
Traub R, Mekonen H, Hernandez L, Da Silva JT, Hanson S, Scott A, Ernst R, Seminowicz D, Melemedjian O. Referred Pain As A Measure Of Visceral Hypersensitivity In A Rat Model Of Comorbid Pain. The Journal of Pain 2023. [DOI: 10.1016/j.jpain.2023.02.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
|
9
|
Reinhard J, Leveille CL, Cornell CE, Merz AJ, Klose C, Ernst R, Keller SL. Remodeling of yeast vacuole membrane lipidomes from the log (one phase) to stationary stage (two phases). Biophys J 2023; 122:1043-1057. [PMID: 36635960 PMCID: PMC10111276 DOI: 10.1016/j.bpj.2023.01.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 01/03/2023] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
Upon nutrient limitation, budding yeast of Saccharomyces cerevisiae shift from fast growth (the log stage) to quiescence (the stationary stage). This shift is accompanied by liquid-liquid phase separation in the membrane of the vacuole, an endosomal organelle. Recent work indicates that the resulting micrometer-scale domains in vacuole membranes enable yeast to survive periods of stress. An outstanding question is which molecular changes might cause this membrane phase separation. Here, we conduct lipidomics of vacuole membranes in both the log and stationary stages. Isolation of pure vacuole membranes is challenging in the stationary stage, when lipid droplets are in close contact with vacuoles. Immuno-isolation has previously been shown to successfully purify log-stage vacuole membranes with high organelle specificity, but it was not previously possible to immuno-isolate stationary-stage vacuole membranes. Here, we develop Mam3 as a bait protein for vacuole immuno-isolation, and demonstrate low contamination by non-vacuolar membranes. We find that stationary-stage vacuole membranes contain surprisingly high fractions of phosphatidylcholine lipids (∼40%), roughly twice as much as log-stage membranes. Moreover, in the stationary stage, these lipids have higher melting temperatures, due to longer and more saturated acyl chains. Another surprise is that no significant change in sterol content is observed. These lipidomic changes, which are largely reflected on the whole-cell level, fit within the predominant view that phase separation in membranes requires at least three types of molecules to be present: lipids with high melting temperatures, lipids with low melting temperatures, and sterols.
Collapse
Affiliation(s)
- John Reinhard
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany; PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | | | | | - Alexey J Merz
- Department of Biochemistry, University of Washington, Seattle, WA
| | | | - Robert Ernst
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany; PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany.
| | - Sarah L Keller
- Department of Chemistry, University of Washington, Seattle, WA.
| |
Collapse
|
10
|
Keller S, Leveille C, Reinhard J, Cornell CE, Rayermann GE, Rayermann SP, Klose C, Ernst R, Merz AJ. Reversible, large-scale, liquid-liquid phase separation in living yeast membranes. Biophys J 2023; 122:8a. [PMID: 36785073 DOI: 10.1016/j.bpj.2022.11.273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
| | | | | | | | | | | | | | - Robert Ernst
- Medical Biochemistry, University of Saarland, Homburg, Germany
| | - Alexey J Merz
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| |
Collapse
|
11
|
Kassam Z, Lang R, Bates DDB, Chang KJ, Fraum TJ, Friedman KA, Golia Pernicka JS, Gollub MJ, Harisinghani M, Khatri G, Lall C, Lee S, Magnetta M, Nougaret S, Paspulati RM, Paroder V, Shaish H, Kim DH, Baheti A, Beets-Tan R, dePrisco G, Ernst R, Ganeshan D, Hope T, Horvat N, Jhaveri K, Kaur H, Korngold E, Lalwani N, Moreno C, Petkovska I, Pickhardt PJ, Rauche G, Sheedy S. Correction: SAR user guide to the rectal MR synoptic report (primary staging). Abdom Radiol (NY) 2023; 48:200. [PMID: 36114288 DOI: 10.1007/s00261-022-03656-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Z Kassam
- Western University, London, Canada
| | - R Lang
- Western University, London, Canada
| | | | | | - T J Fraum
- Mallinckrodt Institute of Radiology, St. Louis, USA
| | - K A Friedman
- University Hospitals Cleveland Medical Center, Cleveland, USA
| | | | | | | | - G Khatri
- University of Texas Southwestern, Dallas, USA
| | - C Lall
- University of Florida-Jacksonville, Jacksonville, USA
| | - S Lee
- University of California, Irvine, USA
| | | | - S Nougaret
- Montpellier Cancer Institute, U1194, Montpellier University, Montpellier, France
| | - R M Paspulati
- University Hospital, Case Western Reserve University, Cleveland, USA
| | - V Paroder
- Memorial Sloan Kettering, New York, USA
| | - H Shaish
- Columbia University Medical Center, New York, USA
| | - D H Kim
- Department of Radiology, University of Wisconsin Medical School, University of Wisconsin, E3/311 Clinical Science Center, 600 Highland Ave., Madison, WI, 53792-3252, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Castro IG, Shortill SP, Dziurdzik SK, Cadou A, Ganesan S, Valenti R, David Y, Davey M, Mattes C, Thomas FB, Avraham RE, Meyer H, Fadel A, Fenech EJ, Ernst R, Zaremberg V, Levine TP, Stefan C, Conibear E, Schuldiner M. Systematic analysis of membrane contact sites in Saccharomyces cerevisiae uncovers modulators of cellular lipid distribution. eLife 2022; 11:74602. [DOI: 10.7554/elife.74602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 10/19/2022] [Indexed: 11/11/2022] Open
Abstract
Actively maintained close appositions between organelle membranes, also known as contact sites, enable the efficient transfer of biomolecules between cellular compartments. Several such sites have been described as well as their tethering machineries. Despite these advances we are still far from a comprehensive understanding of the function and regulation of most contact sites. To systematically characterize contact site proteomes, we established a high-throughput screening approach in Saccharomyces cerevisiae based on co-localization imaging. We imaged split fluorescence reporters for six different contact sites, several of which are poorly characterized, on the background of 1165 strains expressing a mCherry-tagged yeast protein that has a cellular punctate distribution (a hallmark of contact sites), under regulation of the strong TEF2 promoter. By scoring both co-localization events and effects on reporter size and abundance, we discovered over 100 new potential contact site residents and effectors in yeast. Focusing on several of the newly identified residents, we identified three homologs of Vps13 and Atg2 that are residents of multiple contact sites. These proteins share their lipid transport domain, thus expanding this family of lipid transporters. Analysis of another candidate, Ypr097w, which we now call Lec1 (Lipid-droplet Ergosterol Cortex 1), revealed that this previously uncharacterized protein dynamically shifts between lipid droplets and the cell cortex, and plays a role in regulation of ergosterol distribution in the cell. Overall, our analysis expands the universe of contact site residents and effectors and creates a rich database to mine for new functions, tethers, and regulators.
Collapse
Affiliation(s)
| | - Shawn P Shortill
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Samantha Katarzyna Dziurdzik
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Angela Cadou
- Laboratory for Molecular Cell Biology, University College London
| | | | - Rosario Valenti
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Yotam David
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Michael Davey
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
| | - Carsten Mattes
- Medical Biochemistry and Molecular Biology, PZMS, Medical Faculty, Saarland University
| | - Ffion B Thomas
- Laboratory for Molecular Cell Biology, University College London
| | | | - Hadar Meyer
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Amir Fadel
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Emma J Fenech
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Robert Ernst
- Medical Biochemistry and Molecular Biology, PZMS, Medical Faculty, Saarland University
| | | | - Tim P Levine
- UCL Institute of Ophthalmology, University College London
| | | | - Elizabeth Conibear
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science
| |
Collapse
|
13
|
Alsayyah C, Ernst R. A lipid hydrolase and a ubiquitin ligase play hide-and-seek in the ER membrane. EMBO J 2022; 41:e112384. [PMID: 36059256 PMCID: PMC9531298 DOI: 10.15252/embj.2022112384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 08/25/2022] [Indexed: 11/09/2022] Open
Abstract
Complex metabolic diseases such as diabetes and non-alcoholic fatty liver disease have been associated with aberrant lipid metabolism and lipotoxicity. To maintain lipid homeostasis and escape lipotoxicity, cells deploy a plethora of mechanisms, the most fascinating of which relying on a sense-and-response circuit. New work by Volkmar et al reveals an auto-regulated pathway formed by a lipid hydrolase and a lipid-sensitive E3 ubiquitin ligase playing hide-and-seek to warrant membrane function in stressed cells.
Collapse
Affiliation(s)
- Cynthia Alsayyah
- Medical Faculty, Medical Biochemistry and Molecular BiologySaarland UniversityHomburgGermany
- Medical Faculty, Preclinical Center for Molecular Signaling (PZMS)Saarland UniversityHomburgGermany
| | - Robert Ernst
- Medical Faculty, Medical Biochemistry and Molecular BiologySaarland UniversityHomburgGermany
- Medical Faculty, Preclinical Center for Molecular Signaling (PZMS)Saarland UniversityHomburgGermany
| |
Collapse
|
14
|
Hofstaedter C, Chandler C, Kim P, Gillespie J, Rasko D, Harro J, Ernst R. 413: Coordinated lipid A 2-hydroxylation in Pseudomonas aeruginosa by evolutionarily distinct acyltransferase-dioxygenase enzyme pairs. J Cyst Fibros 2021. [DOI: 10.1016/s1569-1993(21)01837-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
15
|
Hofstaedter C, Rasko D, Harro J, Ernst R. 427: Investigating the role of Pseudomonas aeruginosa lipid A deacylase PagL in cystic fibrosis airway infection. J Cyst Fibros 2021. [DOI: 10.1016/s1569-1993(21)01851-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
16
|
Kujawski SA, Lu X, Schneider E, Blythe D, Boktor S, Farrehi J, Haupt T, McBride D, Stephens E, Sakthivel SK, Bachaus B, Waller K, Bauman L, Marconi A, Lewis R, Dettinger L, Ernst R, Kinsey W, Lindstrom S, Gerber SI, Watson JT, Biggs HM. Outbreaks of Adenovirus-associated Respiratory Illness on 5 College Campuses in the United States, 2018-2019. Clin Infect Dis 2021; 72:1992-1999. [PMID: 32322889 DOI: 10.1093/cid/ciaa465] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 04/21/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Human adenoviruses (HAdVs) are commonly associated with acute respiratory illness. HAdV outbreaks are well documented in congregate military training settings, but less is known about outbreaks on college campuses. During fall 2018 and spring 2019, 5 United States (US) colleges reported increases in HAdV-associated respiratory illness. Investigations were performed to better understand HAdV epidemiology in this setting. METHODS A case was defined as a student at one of the 5 colleges, with acute respiratory illness and laboratory-confirmed HAdV infection during October 2018-December 2018 or March-May 2019. Available respiratory specimens were typed by HAdV type-specific real-time polymerase chain reaction assays, and for a subset, whole genome sequencing was performed. We reviewed available medical records and cases were invited to complete a questionnaire, which included questions on symptom presentation, social history, and absenteeism. RESULTS We identified 168 HAdV cases. Median age was 19 (range, 17-22) years and 102 cases (61%) were male. Eleven cases were hospitalized, 10 with pneumonia; 2 cases died. Among questionnaire respondents, 80% (75/94) missed ≥ 1 day of class because of their illness. Among those with a type identified (79%), HAdV types 4 and 7 were equally detected, with frequency of each varying by site. Genome types 4a1 and 7d were identified, respectively, by whole genome sequence analysis. CONCLUSIONS HAdV respiratory illness was associated with substantial morbidity and missed class time among young, generally healthy adults on 5 US college campuses. HAdVs should be considered a cause of respiratory illness outbreaks in congregate settings such as college campuses.
Collapse
Affiliation(s)
- Stephanie A Kujawski
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.,Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Xiaoyan Lu
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Eileen Schneider
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - David Blythe
- Maryland Department of Health Prevention and Health Promotion, Baltimore, Maryland, USA
| | - Sameh Boktor
- Pennsylvania Department of Health, Harrisburg, Pennsylvania, USA
| | - Janice Farrehi
- University Health Service, University of Michigan, Ann Arbor, Michigan, USA
| | - Thomas Haupt
- Wisconsin Department of Health Services, Madison, Wisconsin, USA
| | - David McBride
- University Health Center, University of Maryland, College Park, Maryland, USA
| | | | - Senthilkumar K Sakthivel
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Brian Bachaus
- Maryland Department of Health Prevention and Health Promotion, Baltimore, Maryland, USA
| | - Kirsten Waller
- Pennsylvania Department of Health, Harrisburg, Pennsylvania, USA
| | - Laura Bauman
- Washtenaw County Health Department, Ypsilanti, Michigan, USA
| | - Agustina Marconi
- University Health Services, University of Wisconsin, Madison, Wisconsin, USA
| | - Rebecca Lewis
- Henrico County Health Department, Virginia Department of Health, Richmond, Virginia, USA
| | - Lisa Dettinger
- Pennsylvania Department of Health, Harrisburg, Pennsylvania, USA
| | - Robert Ernst
- University Health Service, University of Michigan, Ann Arbor, Michigan, USA
| | - William Kinsey
- University Health Services, University of Wisconsin, Madison, Wisconsin, USA
| | - Stephen Lindstrom
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Susan I Gerber
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - John T Watson
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Holly M Biggs
- Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| |
Collapse
|
17
|
Väth K, Mattes C, Reinhard J, Covino R, Stumpf H, Hummer G, Ernst R. Cysteine cross-linking in native membranes establishes the transmembrane architecture of Ire1. J Cell Biol 2021; 220:212449. [PMID: 34196665 PMCID: PMC8256922 DOI: 10.1083/jcb.202011078] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 04/28/2021] [Accepted: 05/19/2021] [Indexed: 02/06/2023] Open
Abstract
The ER is a key organelle of membrane biogenesis and crucial for the folding of both membrane and secretory proteins. Sensors of the unfolded protein response (UPR) monitor the unfolded protein load in the ER and convey effector functions for maintaining ER homeostasis. Aberrant compositions of the ER membrane, referred to as lipid bilayer stress, are equally potent activators of the UPR. How the distinct signals from lipid bilayer stress and unfolded proteins are processed by the conserved UPR transducer Ire1 remains unknown. Here, we have generated a functional, cysteine-less variant of Ire1 and performed systematic cysteine cross-linking experiments in native membranes to establish its transmembrane architecture in signaling-active clusters. We show that the transmembrane helices of two neighboring Ire1 molecules adopt an X-shaped configuration independent of the primary cause for ER stress. This suggests that different forms of stress converge in a common, signaling-active transmembrane architecture of Ire1.
Collapse
Affiliation(s)
- Kristina Väth
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,Preclinical Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Carsten Mattes
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,Preclinical Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - John Reinhard
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,Preclinical Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Roberto Covino
- Frankfurt Institute of Advanced Sciences, Goethe-University, Frankfurt, Germany
| | - Heike Stumpf
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,Preclinical Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany.,Institute of Biophysics, Goethe-University, Frankfurt, Germany
| | - Robert Ernst
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,Preclinical Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| |
Collapse
|
18
|
Spector A, Wadhawan A, Constantine N, Ryan K, Mohyuddin I, Dagdag A, Brenner L, Daue M, Schifferle R, Ernst R, Mitchell B, Reynolds M, Postolache T. 136 Sleep and Porphyromonas gingivalis K-Capsular IgG Serotypes: A Study in the Old Order Amish. Sleep 2021. [DOI: 10.1093/sleep/zsab072.135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Introduction
Sleep problems and periodontal disease have a bidirectional relationship and are independently linked with depression, dementia, and metabolic disease. Inadequate sleep can worsen inflammation, a hallmark of periodontal disease, and the activation of the immune system can alter sleep/wake cycles. A key player in periodontal disease is Porphyromonas gingivalis, a bacteria that can translocate to the brain and induce miRNA’s. Antibodies to P. gingivalis capsular virulence factors, K1-7, have been used to estimate P. gingivalis virulence. This study was conducted to explore cross-sectional associations between seropositivity of K serotypes of P. gingivalis and measures of self-reported impairment in sleep. If identified, these links would provide a rationale to initiate causality and mediation studies. We hypothesized that sleep impairment is positively associated with P. gingivalis K IgG serointensity.
Methods
880 Old Order Amish aged 44.8 (SD: 17.2 years); 360 men (40.91%), 520 women (59.09%) responded to an adapted Pittsburgh-Sleep-Quality-Index questionnaire. IgG serointensity to 7 K-capsular P. gingivalis serotypes were measured with ELISAs. We tested for the association of log-transformed serotype IgG intensity and positivity (successively defined as within the top 5% and 25% for each serotype) with sleep parameters (as binary and continuous variables) using linear and logistic regressions, adjusting for age and sex.
Results
We confirmed no hypothesized associations between any of the sleep problems on the PSQI and K serotype serointensity and seropositivity. Exploratory analysis returned a negative association of log-transformed K3 IgG with daytime sleepiness (p=0.01); however, this did not resist adjustment for multiple comparisons and was inconsistent with the direction of the hypothesis.
Conclusion
Strengths of the study include the reduced smoking prevalence in the Amish and the relatively homogenous lifestyle, reducing confounding. The results imply P. gingivalis serotypes are not associated with sleep disturbance. Limitations are self-reporting of sleep, cross-sectional approach and limited generalizability. Results do not support an association between P. gingivalis K serotypes and sleep-problems.
Support (if any)
MVM-CoRE
Collapse
Affiliation(s)
| | | | - Niel Constantine
- Institute of Human Virology and Department of Pathology, University of Maryland School of Medicine
| | - Kathy Ryan
- University of Maryland School of Medicine, Division of Endocrinology, Diabetes and Nutrition
| | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Ernst R. Emerging role of the unfolded protein response in ER membrane homeostasis. FASEB J 2021. [DOI: 10.1096/fasebj.2021.35.s1.00088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Robert Ernst
- Medical Biochemistry and Molecular BiologySaarland UniversityHomburg
| |
Collapse
|
20
|
Ernst R, Linxweiler M, Rink KA, Rothe H, Lecomte G, Bozzato A, Hecker D. [Neurophysiological parameters for speech recognition in patients with cochlear implants]. Laryngorhinootologie 2021; 101:216-227. [PMID: 33836549 DOI: 10.1055/a-1399-9540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
OBJECTIVES Cochlea Implants (CI) are the preferred treatment for deaf and highly hearing imparied people. While deaf people already profit enormously from any regained hearing perception, it is not as easy to predict a profitable outcome for people with a remaining sense of hearing. To provide patients the best possible outcome in speech understanding, a lot of parameters have to be identified and adjusted. The aim of this study is to show the influence of objective parameters on classified speech understanding using collected data. MATERIAL AND METHODS A total of 52 patients and 65 ears aged between 18 and 80 years were included in this study. ECAP-thresholds from intraoperative measurements and impedance were used as objective parameters. T- and C/M-levels were defined as subjective parameters. To classify the performance the value of speech understanding was used. RESULTS Differences between both groups (age, time after implantation) were not significant. The gained word scores at 500 Hz correlated significantly with the results of the speech perception threshold on two-digit numbers. The electrode impedances correlated on average with speech understanding with constant variability. The distributions of objective and subjective parameters showed partially significant differences. Many distributions showed significant differences to the normal distribution. Accordingly, the overlapping areas of the significance levels are very narrow. CONCLUSION Higher impedances and incorrectly adjusted T-levels resulted in a worse speech understanding. Relation of C/M-levels to ECAP thresholds seem to be crucial for good speech understanding.
Collapse
Affiliation(s)
- Robert Ernst
- Hals-, Nasen- und Ohrenklinik, Universitätsklinikum des Saarlandes, Homburg, Germany
| | - Maximilian Linxweiler
- Hals-, Nasen- und Ohrenklinik, Universitätsklinikum des Saarlandes, Homburg, Germany
| | - Katharina Anna Rink
- Hals-, Nasen- und Ohrenklinik, Universitätsklinikum des Saarlandes, Homburg, Germany
| | - Heike Rothe
- Hals-, Nasen- und Ohrenklinik, Universitätsklinikum des Saarlandes, Homburg, Germany
| | - Gregory Lecomte
- Hals-, Nasen- und Ohrenklinik, Universitätsklinikum des Saarlandes, Homburg, Germany
| | - Alessandro Bozzato
- Hals-, Nasen- und Ohrenklinik, Universitätsklinikum des Saarlandes, Homburg, Germany
| | - Dietmar Hecker
- Klinik für Hals-, Nasen- und Ohrenheilkunde, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg, Germany
| |
Collapse
|
21
|
Martínez-Limón A, Calloni G, Ernst R, Vabulas RM. Flavin dependency undermines proteome stability, lipid metabolism and cellular proliferation during vitamin B2 deficiency. Cell Death Dis 2020; 11:725. [PMID: 32895367 PMCID: PMC7477094 DOI: 10.1038/s41419-020-02929-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 07/30/2020] [Accepted: 07/30/2020] [Indexed: 12/13/2022]
Abstract
Tumor cells adapt their metabolism to meet the energetic and anabolic requirements of high proliferation and invasiveness. The metabolic addiction has motivated the development of therapies directed at individual biochemical nodes. However, currently there are few possibilities to target multiple enzymes in tumors simultaneously. Flavin-containing enzymes, ca. 100 proteins in humans, execute key biotransformations in mammalian cells. To expose metabolic addiction, we inactivated a substantial fraction of the flavoproteome in melanoma cells by restricting the supply of the FMN and FAD precursor riboflavin, the vitamin B2. Vitamin B2 deficiency affected stability of many polypeptides and thus resembled the chaperone HSP90 inhibition, the paradigmatic multiple-target approach. In support of this analogy, flavin-depleted proteins increasingly associated with a number of proteostasis network components, as identified by the mass spectrometry analysis of the FAD-free NQO1 aggregates. Proteome-wide analysis of the riboflavin-starved cells revealed a profound inactivation of the mevalonate pathway of cholesterol synthesis, which underlines the manifold cellular vulnerability created by the flavoproteome inactivation. Cell cycle-arrested tumor cells became highly sensitive to alkylating chemotherapy. Our data suggest that the flavoproteome is well suited to design synthetic lethality protocols combining proteostasis manipulation and metabolic reprogramming.
Collapse
Affiliation(s)
- Adrían Martínez-Limón
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany.,Institute of Biophysical Chemistry, Goethe University Frankfurt, Frankfurt am Main, Germany.,Institute for Research in Biomedicine (IRB), Barcelona, Spain
| | - Giulia Calloni
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany.,Institute of Biophysical Chemistry, Goethe University Frankfurt, Frankfurt am Main, Germany.,AB SCIEX Germany GmbH, Darmstadt, Germany
| | - Robert Ernst
- Center for Molecular Signaling (PZMS), Institute of Medical Biochemistry and Molecular Biology, Medical Faculty, University of Saarland, Homburg, Germany
| | - R Martin Vabulas
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany. .,Institute of Biophysical Chemistry, Goethe University Frankfurt, Frankfurt am Main, Germany. .,Charité - Universitätsmedizin Berlin, Institute of Biochemistry, Berlin, Germany.
| |
Collapse
|
22
|
Reinhard J, Mattes C, Väth K, Radanović T, Surma MA, Klose C, Ernst R. A Quantitative Analysis of Cellular Lipid Compositions During Acute Proteotoxic ER Stress Reveals Specificity in the Production of Asymmetric Lipids. Front Cell Dev Biol 2020; 8:756. [PMID: 32850859 PMCID: PMC7417482 DOI: 10.3389/fcell.2020.00756] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/20/2020] [Indexed: 12/12/2022] Open
Abstract
The unfolded protein response (UPR) is central to endoplasmic reticulum (ER) homeostasis by controlling its size and protein folding capacity. When activated by unfolded proteins in the ER-lumen or aberrant lipid compositions, the UPR adjusts the expression of hundreds of target genes to counteract ER stress. The proteotoxic drugs dithiothreitol (DTT) and tunicamycin (TM) are commonly used to induce misfolding of proteins in the ER and to study the UPR. However, their potential impact on the cellular lipid composition has never been systematically addressed. Here, we report the quantitative, cellular lipid composition of Saccharomyces cerevisiae during acute, proteotoxic stress in both rich and synthetic media. We show that DTT causes rapid remodeling of the lipidome when used in rich medium at growth-inhibitory concentrations, while TM has only a marginal impact on the lipidome under our conditions of cultivation. We formulate recommendations on how to study UPR activation by proteotoxic stress without interferences from a perturbed lipid metabolism. Furthermore, our data suggest an intricate connection between the cellular growth rate, the abundance of the ER, and the metabolism of fatty acids. We show that Saccharomyces cerevisiae can produce asymmetric lipids with two saturated fatty acyl chains differing substantially in length. These observations indicate that the pairing of saturated fatty acyl chains is tightly controlled and suggest an evolutionary conservation of asymmetric lipids and their biosynthetic machineries.
Collapse
Affiliation(s)
- John Reinhard
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Carsten Mattes
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Kristina Väth
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | - Toni Radanović
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | | | | | - Robert Ernst
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany.,PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| |
Collapse
|
23
|
Ernst R, Ballweg S, Levental I. Corrigendum to "Cellular mechanisms of physicochemical membrane homeostasis" [Curr Opin Cell Biol (2018) 44-51]. Curr Opin Cell Biol 2020; 63:212. [PMID: 32446588 DOI: 10.1016/j.ceb.2020.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Robert Ernst
- Department of Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg 66421, Germany.
| | - Stephanie Ballweg
- Department of Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg 66421, Germany
| | - Ilya Levental
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Science Center, Houston, TX, USA.
| |
Collapse
|
24
|
Ernst R. Emerging role of the unfolded protein response in ER membrane homeostasis. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.00119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
25
|
Levental KR, Malmberg E, Symons JL, Fan YY, Chapkin RS, Ernst R, Levental I. Lipidomic and biophysical homeostasis of mammalian membranes counteracts dietary lipid perturbations to maintain cellular fitness. Nat Commun 2020; 11:1339. [PMID: 32165635 PMCID: PMC7067841 DOI: 10.1038/s41467-020-15203-1] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 02/21/2020] [Indexed: 11/29/2022] Open
Abstract
Proper membrane physiology requires maintenance of biophysical properties, which must be buffered from external perturbations. While homeostatic adaptation of membrane fluidity to temperature variation is a ubiquitous feature of ectothermic organisms, such responsive membrane adaptation to external inputs has not been directly observed in mammals. Here, we report that challenging mammalian membranes by dietary lipids leads to robust lipidomic remodeling to preserve membrane physical properties. Specifically, exogenous polyunsaturated fatty acids are rapidly incorporated into membrane lipids, inducing a reduction in membrane packing. These effects are rapidly compensated both in culture and in vivo by lipidome-wide remodeling, most notably upregulation of saturated lipids and cholesterol, resulting in recovery of membrane packing and permeability. Abrogation of this response results in cytotoxicity when membrane homeostasis is challenged by dietary lipids. These results reveal an essential mammalian mechanism for membrane homeostasis wherein lipidome remodeling in response to dietary lipid inputs preserves functional membrane phenotypes. Proper membrane physiology requires maintenance of a narrow range of physicochemical properties, which must be buffered from external perturbations. Here, authors report lipidomic remodeling to preserve membrane physical properties upon exogenous polyunsaturated fatty acids exposure.
Collapse
Affiliation(s)
- Kandice R Levental
- Department of Integrative Biology & Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA.
| | - Eric Malmberg
- Department of Integrative Biology & Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Jessica L Symons
- Department of Integrative Biology & Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Yang-Yi Fan
- Program in Integrative Nutrition & Complex Diseases and Department of Nutrition, Texas A&M University, College Station, TX, USA
| | - Robert S Chapkin
- Program in Integrative Nutrition & Complex Diseases and Department of Nutrition, Texas A&M University, College Station, TX, USA
| | - Robert Ernst
- Department of Medical Biochemistry & Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany
| | - Ilya Levental
- Department of Integrative Biology & Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA.
| |
Collapse
|
26
|
Ballweg S, Sezgin E, Doktorova M, Covino R, Reinhard J, Wunnicke D, Hänelt I, Levental I, Hummer G, Ernst R. Regulation of lipid saturation without sensing membrane fluidity. Nat Commun 2020; 11:756. [PMID: 32029718 PMCID: PMC7005026 DOI: 10.1038/s41467-020-14528-1] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 01/14/2020] [Indexed: 12/22/2022] Open
Abstract
Cells maintain membrane fluidity by regulating lipid saturation, but the molecular mechanisms of this homeoviscous adaptation remain poorly understood. We have reconstituted the core machinery for regulating lipid saturation in baker’s yeast to study its molecular mechanism. By combining molecular dynamics simulations with experiments, we uncover a remarkable sensitivity of the transcriptional regulator Mga2 to the abundance, position, and configuration of double bonds in lipid acyl chains, and provide insights into the molecular rules of membrane adaptation. Our data challenge the prevailing hypothesis that membrane fluidity serves as the measured variable for regulating lipid saturation. Rather, we show that Mga2 senses the molecular lipid-packing density in a defined region of the membrane. Our findings suggest that membrane property sensors have evolved remarkable sensitivities to highly specific aspects of membrane structure and dynamics, thus paving the way toward the development of genetically encoded reporters for such properties in the future. Cells maintain membrane fluidity by regulating lipid saturation, but the molecular mechanisms of this homeoviscous adaptation remain poorly understood. Here authors reconstituted the core machinery for regulating lipid saturation in baker’s yeast to directly characterize its response to defined membrane environments and uncover its mode-of-action.
Collapse
Affiliation(s)
- Stephanie Ballweg
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Kirrberger Strasse 100, Building 61.4, 66421, Homburg, Germany.,PZMS, Center for Molecular Signaling (PZMS), Medical Faculty, Saarland University, 66421, Homburg, Germany
| | - Erdinc Sezgin
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Milka Doktorova
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Science Center, Houston, Texas, USA
| | - Roberto Covino
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438, Frankfurt, Germany
| | - John Reinhard
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Kirrberger Strasse 100, Building 61.4, 66421, Homburg, Germany.,PZMS, Center for Molecular Signaling (PZMS), Medical Faculty, Saarland University, 66421, Homburg, Germany
| | - Dorith Wunnicke
- Institute of Biochemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany
| | - Inga Hänelt
- Institute of Biochemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany
| | - Ilya Levental
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Science Center, Houston, Texas, USA
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438, Frankfurt, Germany.,Institute of Biophysics, Goethe University Frankfurt, 60438, Frankfurt, Germany
| | - Robert Ernst
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Kirrberger Strasse 100, Building 61.4, 66421, Homburg, Germany. .,PZMS, Center for Molecular Signaling (PZMS), Medical Faculty, Saarland University, 66421, Homburg, Germany.
| |
Collapse
|
27
|
Radanovic T, Gecht M, Covino R, Hummer G, Niwa M, Ernst R. Mechanistic Dissection of Sphingolipid Binding to the ER Stress Transducer ATF6 - Insights into the Coordination of Sphingolipid and Protein Production. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
|
28
|
Ernst R, Covino R, Hummer G, Reinhard J, Mattes C, Väth K, Hach J. A Biophysical Basis for Chronic Diseases Associated with ER Stress - Ire1 is Activated by Lipid Bilayer Stress and Perpetuates the Unfolded Protein Response. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
29
|
Covino R, Hummer G, Ernst R. Integrated Functions of Membrane Property Sensors and a Hidden Side of the Unfolded Protein Response. Mol Cell 2019; 71:458-467. [PMID: 30075144 DOI: 10.1016/j.molcel.2018.07.019] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 07/09/2018] [Accepted: 07/17/2018] [Indexed: 12/26/2022]
Abstract
Eukaryotic cells face the challenge of maintaining the complex composition of several coexisting organelles. The molecular mechanisms underlying the homeostasis of subcellular membranes and their adaptation during stress are only now starting to emerge. Here, we discuss three membrane property sensors of the endoplasmic reticulum (ER), namely OPI1, MGA2, and IRE1, each controlling a large cellular program impacting the lipid metabolic network. OPI1 coordinates the production of membrane and storage lipids, MGA2 regulates the production of unsaturated fatty acids required for membrane biogenesis, and IRE1 controls the unfolded protein response (UPR) to adjust ER size, protein folding, and the secretory capacity of the cell. Although these proteins use remarkably distinct sensing mechanisms, they are functionally connected via the ER membrane and cooperate to maintain membrane homeostasis. As a rationalization of the recently described mechanism of UPR activation by lipid bilayer stress, we propose that IRE1 can sense the protein-to-lipid ratio in the ER membrane to ensure a balanced production of membrane proteins and lipids.
Collapse
Affiliation(s)
- Roberto Covino
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany; Institute of Biophysics, Goethe University, 60438 Frankfurt am Main, Germany
| | - Robert Ernst
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Kirrberger Str. 100, Gebäude 61.4, 66421 Homburg, Germany.
| |
Collapse
|
30
|
Hofbauer HF, Gecht M, Fischer SC, Seybert A, Frangakis AS, Stelzer EHK, Covino R, Hummer G, Ernst R. The molecular recognition of phosphatidic acid by an amphipathic helix in Opi1. J Cell Biol 2018; 217:3109-3126. [PMID: 29941475 PMCID: PMC6122994 DOI: 10.1083/jcb.201802027] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 05/28/2018] [Accepted: 06/18/2018] [Indexed: 01/09/2023] Open
Abstract
Phosphatidic acid (PA) lipids have a dual role as building blocks for membrane biogenesis and as active signaling molecules. This study establishes the molecular details of selective PA recognition by the transcriptional regulator Opi1 from baker’s yeast. A key event in cellular physiology is the decision between membrane biogenesis and fat storage. Phosphatidic acid (PA) is an important intermediate at the branch point of these pathways and is continuously monitored by the transcriptional repressor Opi1 to orchestrate lipid metabolism. In this study, we report on the mechanism of membrane recognition by Opi1 and identify an amphipathic helix (AH) for selective binding of PA over phosphatidylserine (PS). The insertion of the AH into the membrane core renders Opi1 sensitive to the lipid acyl chain composition and provides a means to adjust membrane biogenesis. By rational design of the AH, we tune the membrane-binding properties of Opi1 and control its responsiveness in vivo. Using extensive molecular dynamics simulations, we identify two PA-selective three-finger grips that tightly bind the PA phosphate headgroup while interacting less intimately with PS. This work establishes lipid headgroup selectivity as a new feature in the family of AH-containing membrane property sensors.
Collapse
Affiliation(s)
- Harald F Hofbauer
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany .,Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Frankfurt, Germany.,Institute of Medical Biochemistry and Molecular Biology, School of Medicine, University of Saarland, Homburg, Germany
| | - Michael Gecht
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany.,Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Frankfurt, Germany.,Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Sabine C Fischer
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany.,Physical Biology, Interdisciplinary Center for Neuroscience, Goethe University Frankfurt, Frankfurt, Germany
| | - Anja Seybert
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
| | - Achilleas S Frangakis
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
| | - Ernst H K Stelzer
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany.,Physical Biology, Interdisciplinary Center for Neuroscience, Goethe University Frankfurt, Frankfurt, Germany
| | - Roberto Covino
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany.,Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Robert Ernst
- Institute of Medical Biochemistry and Molecular Biology, School of Medicine, University of Saarland, Homburg, Germany
| |
Collapse
|
31
|
Ernst R, Ballweg S, Levental I. Cellular mechanisms of physicochemical membrane homeostasis. Curr Opin Cell Biol 2018; 53:44-51. [PMID: 29787971 DOI: 10.1016/j.ceb.2018.04.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/19/2018] [Accepted: 04/29/2018] [Indexed: 12/11/2022]
Abstract
Biological membranes are vital, active contributors to cell function. In addition to specific interactions of individual lipid molecules and lateral organization produced by membrane domains, the bulk physicochemical properties of biological membranes broadly regulate protein structure and function. Therefore, these properties must be homeostatically maintained within a narrow range that is compatible with cellular physiology. Although such adaptiveness has been known for decades, recent observations have dramatically expanded its scope by showing the breadth of membrane properties that must be maintained, and revealing the remarkable diversity of biological membranes, both within and between cell types. Cells have developed a broad palette of sense-and-respond machineries to mediate physicochemical membrane homeostasis, and the molecular mechanisms of these are being discovered through combinations of cell biology, biophysical approaches, and computational modeling.
Collapse
Affiliation(s)
- Robert Ernst
- Department of Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, 66421 Homburg, Germany.
| | - Stephanie Ballweg
- Department of Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, 66421 Homburg, Germany
| | - Ilya Levental
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Science Center, Houston, TX, USA.
| |
Collapse
|
32
|
Radanović T, Reinhard J, Ballweg S, Pesek K, Ernst R. An Emerging Group of Membrane Property Sensors Controls the Physical State of Organellar Membranes to Maintain Their Identity. Bioessays 2018; 40:e1700250. [PMID: 29574931 DOI: 10.1002/bies.201700250] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 02/06/2018] [Indexed: 11/06/2022]
Abstract
The biological membranes of eukaryotic cells harbor sensitive surveillance systems to establish, sense, and maintain characteristic physicochemical properties that ultimately define organelle identity. They are fundamentally important for membrane homeostasis and play active roles in cellular signaling, protein sorting, and the formation of vesicular carriers. Here, we compare the molecular mechanisms of Mga2 and Ire1, two sensors involved in the regulation of fatty acid desaturation and the response to unfolded proteins and lipid bilayer stress in order to identify their commonalities and specializations. We will speculate on the cellular significance of membrane property sensors in other organelles and discuss their putative mechanisms. Based on these findings, we propose membrane property sensors as an emerging class of proteins with wide implications for organelle communication and function.
Collapse
Affiliation(s)
- Toni Radanović
- Medical Faculty, Department of Medical Biochemistry and Molecular Bioloy, Saarland University, 66421 Homburg, Germany
| | - John Reinhard
- Medical Faculty, Department of Medical Biochemistry and Molecular Bioloy, Saarland University, 66421 Homburg, Germany
| | - Stephanie Ballweg
- Medical Faculty, Department of Medical Biochemistry and Molecular Bioloy, Saarland University, 66421 Homburg, Germany
| | - Kristina Pesek
- Medical Faculty, Department of Medical Biochemistry and Molecular Bioloy, Saarland University, 66421 Homburg, Germany
| | - Robert Ernst
- Medical Faculty, Department of Medical Biochemistry and Molecular Bioloy, Saarland University, 66421 Homburg, Germany
| |
Collapse
|
33
|
Kopp Y, Lang WH, Schuster TB, Martínez-Limón A, Hofbauer HF, Ernst R, Calloni G, Vabulas RM. CHIP as a membrane-shuttling proteostasis sensor. eLife 2017; 6:e29388. [PMID: 29091030 PMCID: PMC5665643 DOI: 10.7554/elife.29388] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 10/22/2017] [Indexed: 12/12/2022] Open
Abstract
Cells respond to protein misfolding and aggregation in the cytosol by adjusting gene transcription and a number of post-transcriptional processes. In parallel to functional reactions, cellular structure changes as well; however, the mechanisms underlying the early adaptation of cellular compartments to cytosolic protein misfolding are less clear. Here we show that the mammalian ubiquitin ligase C-terminal Hsp70-interacting protein (CHIP), if freed from chaperones during acute stress, can dock on cellular membranes thus performing a proteostasis sensor function. We reconstituted this process in vitro and found that mainly phosphatidic acid and phosphatidylinositol-4-phosphate enhance association of chaperone-free CHIP with liposomes. HSP70 and membranes compete for mutually exclusive binding to the tetratricopeptide repeat domain of CHIP. At new cellular locations, access to compartment-specific substrates would enable CHIP to participate in the reorganization of the respective organelles, as exemplified by the fragmentation of the Golgi apparatus (effector function).
Collapse
Affiliation(s)
- Yannick Kopp
- Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtFrankfurt am MainGermany
- Institute of Biophysical ChemistryGoethe University FrankfurtFrankfurt am MainGermany
| | - Wei-Han Lang
- Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtFrankfurt am MainGermany
- Institute of Biophysical ChemistryGoethe University FrankfurtFrankfurt am MainGermany
| | - Tobias B Schuster
- Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtFrankfurt am MainGermany
- Institute of Biophysical ChemistryGoethe University FrankfurtFrankfurt am MainGermany
| | - Adrián Martínez-Limón
- Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtFrankfurt am MainGermany
- Institute of Biophysical ChemistryGoethe University FrankfurtFrankfurt am MainGermany
| | - Harald F Hofbauer
- Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtFrankfurt am MainGermany
- Institute of BiochemistryGoethe University FrankfurtFrankfurt am MainGermany
| | - Robert Ernst
- Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtFrankfurt am MainGermany
- Institute of BiochemistryGoethe University FrankfurtFrankfurt am MainGermany
| | - Giulia Calloni
- Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtFrankfurt am MainGermany
- Institute of Biophysical ChemistryGoethe University FrankfurtFrankfurt am MainGermany
| | - R Martin Vabulas
- Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtFrankfurt am MainGermany
- Institute of Biophysical ChemistryGoethe University FrankfurtFrankfurt am MainGermany
| |
Collapse
|
34
|
Cohen N, Breker M, Bakunts A, Pesek K, Chas A, Argemí J, Orsi A, Gal L, Chuartzman S, Wigelman Y, Jonas F, Walter P, Ernst R, Aragón T, van Anken E, Schuldiner M. Iron affects Ire1 clustering propensity and the amplitude of endoplasmic reticulum stress signaling. J Cell Sci 2017; 130:3222-3233. [PMID: 28794014 PMCID: PMC5665437 DOI: 10.1242/jcs.201715] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 08/02/2017] [Indexed: 01/10/2023] Open
Abstract
The unfolded protein response (UPR) allows cells to adjust secretory pathway capacity according to need. Ire1, the endoplasmic reticulum (ER) stress sensor and central activator of the UPR is conserved from the budding yeast Saccharomyces cerevisiae to humans. Under ER stress conditions, Ire1 clusters into foci that enable optimal UPR activation. To discover factors that affect Ire1 clustering, we performed a high-content screen using a whole-genome yeast mutant library expressing Ire1–mCherry. We imaged the strains following UPR induction and found 154 strains that displayed alterations in Ire1 clustering. The hits were enriched for iron and heme effectors and binding proteins. By performing pharmacological depletion and repletion, we confirmed that iron (Fe3+) affects UPR activation in both yeast and human cells. We suggest that Ire1 clustering propensity depends on membrane composition, which is governed by heme-dependent biosynthesis of sterols. Our findings highlight the diverse cellular functions that feed into the UPR and emphasize the cross-talk between organelles required to concertedly maintain homeostasis. Highlighted Article: To respond to folding stress in the ER, cells activate the conserved sensor Ire1. We show that iron is required for optimal Ire1 activation and suggest this is because iron is required for ergosterol biosynthesis.
Collapse
Affiliation(s)
- Nir Cohen
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Michal Breker
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.,The Rockefeller University, New York, NY 10065, USA
| | - Anush Bakunts
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Ospedale San Raffaele, Via Olgettina 58, 20132, Milan, Italy
| | - Kristina Pesek
- Institute of Biochemistry and Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue Str. 15, 60438 Frankfurt, Germany
| | - Ainara Chas
- Center for Applied Medical Research, Department of Gene Therapy and Regulation of Gene Expression. University of Navarra, 55 Pio XII St. 31008 Pamplona, Spain
| | - Josepmaria Argemí
- Center for Applied Medical Research, Department of Gene Therapy and Regulation of Gene Expression. University of Navarra, 55 Pio XII St. 31008 Pamplona, Spain
| | - Andrea Orsi
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Ospedale San Raffaele, Via Olgettina 58, 20132, Milan, Italy
| | - Lihi Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Silvia Chuartzman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yoav Wigelman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Peter Walter
- Department of Biochemistry & Biophysics, University of California San Francisco and Howard Hughes Medical Institute, San Francisco, CA 94143, USA
| | - Robert Ernst
- Center for Molecular Signaling, Institute of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Tomás Aragón
- Center for Applied Medical Research, Department of Gene Therapy and Regulation of Gene Expression. University of Navarra, 55 Pio XII St. 31008 Pamplona, Spain
| | - Eelco van Anken
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Ospedale San Raffaele, Via Olgettina 58, 20132, Milan, Italy
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| |
Collapse
|
35
|
Halbleib K, Pesek K, Covino R, Hofbauer HF, Wunnicke D, Hänelt I, Hummer G, Ernst R. Activation of the Unfolded Protein Response by Lipid Bilayer Stress. Mol Cell 2017; 67:673-684.e8. [PMID: 28689662 DOI: 10.1016/j.molcel.2017.06.012] [Citation(s) in RCA: 200] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 05/15/2017] [Accepted: 06/13/2017] [Indexed: 11/29/2022]
Abstract
The unfolded protein response (UPR) is a conserved homeostatic program that is activated by misfolded proteins in the lumen of the endoplasmic reticulum (ER). Recently, it became evident that aberrant lipid compositions of the ER membrane, referred to as lipid bilayer stress, are equally potent in activating the UPR. The underlying molecular mechanism, however, remained unclear. We show that the most conserved transducer of ER stress, Ire1, uses an amphipathic helix (AH) to sense membrane aberrancies and control UPR activity. In vivo and in vitro experiments, together with molecular dynamics (MD) simulations, identify the physicochemical properties of the membrane environment that control Ire1 oligomerization. This work establishes the molecular mechanism of UPR activation by lipid bilayer stress.
Collapse
Affiliation(s)
- Kristina Halbleib
- Institute of Biochemistry and Buchmann Institute for Molecular Life Sciences, Goethe-University, Frankfurt, Max-von-Laue-Strasse 15, 60438 Frankfurt, Germany
| | - Kristina Pesek
- Institute of Biochemistry and Buchmann Institute for Molecular Life Sciences, Goethe-University, Frankfurt, Max-von-Laue-Strasse 15, 60438 Frankfurt, Germany
| | - Roberto Covino
- Department of Theoretical Biophysics, Max-Planck-Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt, Germany
| | - Harald F Hofbauer
- Institute of Biochemistry and Buchmann Institute for Molecular Life Sciences, Goethe-University, Frankfurt, Max-von-Laue-Strasse 15, 60438 Frankfurt, Germany
| | - Dorith Wunnicke
- Institute of Biochemistry, Goethe-University, Frankfurt, Max-von-Laue-Strasse 9, 60438 Frankfurt, Germany
| | - Inga Hänelt
- Institute of Biochemistry, Goethe-University, Frankfurt, Max-von-Laue-Strasse 9, 60438 Frankfurt, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max-Planck-Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt, Germany; Institute of Biophysics, Goethe-University, 60438 Frankfurt, Germany
| | - Robert Ernst
- Institute of Biochemistry and Buchmann Institute for Molecular Life Sciences, Goethe-University, Frankfurt, Max-von-Laue-Strasse 15, 60438 Frankfurt, Germany; Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany.
| |
Collapse
|
36
|
Abstract
Abstract
The maintenance of a fluid lipid bilayer is key for membrane integrity and cell viability. We are only beginning to understand how eukaryotic cells sense and maintain the characteristic lipid compositions and bulk membrane properties of their organelles. One of the key factors determining membrane fluidity and phase behavior is the proportion of saturated and unsaturated acyl chains in membrane lipids. Saccharomyces cerevisiae is an ideal model organism to study the regulation of the lipid acyl chain composition via the OLE pathway. The OLE pathway comprises all steps involved in the regulated mobilization of the transcription factors Mga2 and Spt23 from the endoplasmic reticulum (ER), which then drive the expression of OLE1 in the nucleus. OLE1 encodes for the essential Δ9-fatty acid desaturase Ole1 and is crucial for de novo biosynthesis of unsaturated fatty acids (UFAs) that are used as lipid building blocks. This review summarizes our current knowledge of the OLE pathway, the best-characterized, eukaryotic sense-and-control system regulating membrane lipid saturation, and identifies open questions to indicate future directions.
Collapse
|
37
|
Covino R, Ballweg S, Stordeur C, Michaelis J, Puth K, Wernig F, Bahrami A, Ernst A, Hummer G, Ernst R. A Eukaryotic Sensor for Membrane Lipid Saturation. Mol Cell 2016; 63:49-59. [DOI: 10.1016/j.molcel.2016.05.015] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 04/12/2016] [Accepted: 05/11/2016] [Indexed: 12/22/2022]
|
38
|
Ernst R, Zwimpfer F, Dual J. One sensor acoustic emission localization in plates. Ultrasonics 2016; 64:139-150. [PMID: 26372509 DOI: 10.1016/j.ultras.2015.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 07/21/2015] [Accepted: 08/25/2015] [Indexed: 06/05/2023]
Abstract
Acoustic emissions are elastic waves accompanying damage processes and are therefore used for monitoring the health state of structures. Most of the traditional acoustic emission techniques use a trilateration approach requiring at least three sensors on a 2D domain in order to localize sources of acoustic emission events. In this paper, we present a new approach which requires only a single sensor to identify and localize the source of acoustic emissions in a finite plate. The method proposed makes use of the time reversal principle and the dispersive nature of the flexural wave mode in a suitable frequency band. The signal shape of the transverse velocity response contains information about the propagated paths of the incoming elastic waves. This information is made accessible by a numerical time reversal simulation. The effect of dispersion is reversed and the original shape of the flexural wave is restored at the origin of the acoustic emission. The time reversal process is analyzed first for an infinite Mindlin plate, then by a 3D FEM simulation which in combination results in a novel acoustic emission localization process. The process is experimentally verified for different aluminum plates for artificially generated acoustic emissions (Hsu-Nielsen source). Good and reliable localization was achieved for a homogeneous quadratic aluminum plate with only one measurement.
Collapse
Affiliation(s)
- R Ernst
- Institute of Mechanical Systems, Swiss Federal Institute of Technology, ETH Zurich, Switzerland.
| | - F Zwimpfer
- Institute of Mechanical Systems, Swiss Federal Institute of Technology, ETH Zurich, Switzerland
| | - J Dual
- Institute of Mechanical Systems, Swiss Federal Institute of Technology, ETH Zurich, Switzerland.
| |
Collapse
|
39
|
Ernst R, Morici E, Estelrich H, Muiño W, Ruiz MA. Efecto de la quema controlada sobre el banco de semillas de gramíneas en diferentes parches del bosque de caldén en la región semiárida central Argentina. ARCH ZOOTEC 2015. [DOI: 10.21071/az.v64i247.404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
El banco de semillas del suelo es la principal reserva de propágulos con que cuenta una comunidad vegetal para su mantenimiento, regeneración y perpetuación. Las quemas controladas pueden producir cambios en su composición y distribución. El objetivo del presente trabajo fue evaluar y comparar el comportamiento del banco de semillas germinable de gramíneas en una región del caldenal antes y después de producida una quema controlada. Se delimitaron 5 parches de vegetación dominados por gramíneas de porte bajo (parches forrajeros), 5 parches dominados por gramíneas de porte intermedio (parches no forrajeros) y otros 5 por arbustos (parches arbustivos). A su vez mediante muestreos al azar se tomaron 5 muestras de suelo por parche, las que fueron extraídas por medio de un cilindro metálico de 7 cm de diámetro y 4 cm de profundidad, permitiendo dividir a la muestra en estratos: broza, 0-2 y 2-4 cm de profundidad. Los estratos se colocaron en bandejas de plástico sobre una cama de siembra esterilizada y se regaron periódicamente en invernáculo. Una vez germinadas las semillas se identificaron, contabilizaron y extrajeron las plántulas, reconociéndose para todas las profundidades 8 gramíneas. Luego de la quema Piptochaetium napostaense mostró un aumento en su germinación en 0-2 cm en los parches forrajeros y no forrajeros (P
Collapse
|
40
|
Puth K, Hofbauer HF, Sáenz JP, Ernst R. Homeostatic control of biological membranes by dedicated lipid and membrane packing sensors. Biol Chem 2015; 396:1043-58. [DOI: 10.1515/hsz-2015-0130] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 03/31/2015] [Indexed: 11/15/2022]
Abstract
Abstract
Biological membranes are dynamic and complex assemblies of lipids and proteins. Eukaryotic lipidomes encompass hundreds of distinct lipid species and we have only begun to understand their role and function. This review focuses on recent advances in the field of lipid sensors and discusses methodical approaches to identify and characterize putative sensor domains. We elaborate on the role of integral and conditionally membrane-associated sensor proteins, their molecular mechanisms, and identify open questions in the emerging field of membrane homeostasis.
Collapse
|
41
|
Mehla J, Ernst R, Moore R, Wakschlag A, Marquis MK, Ambudkar SV, Golin J. Evidence for a molecular diode-based mechanism in a multispecific ATP-binding cassette (ABC) exporter: SER-1368 as a gatekeeping residue in the yeast multidrug transporter Pdr5. J Biol Chem 2014; 289:26597-26606. [PMID: 25112867 DOI: 10.1074/jbc.m114.586032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
ATP-binding cassette multidrug efflux pumps transport a wide range of substrates. Current models suggest that a drug binds relatively tightly to a transport site in the transmembrane domains when the protein is in the closed inward facing conformation. Upon binding of ATP, the transporter can switch to an outward facing (drug off or drug releasing) structure of lower affinity. ATP hydrolysis is critically important for remodeling the drug-binding site to facilitate drug release and to reset the transporter for a new transport cycle. We characterized the novel phenotype of an S1368A mutant that lies in the putative drug-binding pocket of the yeast multidrug transporter Pdr5. This substitution created broad, severe drug hypersensitivity, although drug binding, ATP hydrolysis, and intradomain signaling were indistinguishable from the wild-type control. Several different rhodamine 6G efflux and accumulation assays yielded evidence consistent with the possibility that Ser-1368 prevents reentry of the excluded drug.
Collapse
Affiliation(s)
- Jitender Mehla
- Department of Biology, Catholic University of America, Washington, D. C. 20064
| | - Robert Ernst
- Institute of Biochemistry, Biocenter of the Goethe University, Frankfurt, Germany 60438, and
| | - Rachel Moore
- Department of Biology, Catholic University of America, Washington, D. C. 20064
| | - Adina Wakschlag
- Department of Biology, Catholic University of America, Washington, D. C. 20064
| | - Mary Kate Marquis
- Department of Biology, Catholic University of America, Washington, D. C. 20064
| | - Suresh V Ambudkar
- Laboratory of Cell Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - John Golin
- Department of Biology, Catholic University of America, Washington, D. C. 20064,.
| |
Collapse
|
42
|
Ernst R, Dual J. Acoustic emission localization in beams based on time reversed dispersion. Ultrasonics 2014; 54:1522-1533. [PMID: 24794505 DOI: 10.1016/j.ultras.2014.04.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 04/07/2014] [Accepted: 04/08/2014] [Indexed: 06/03/2023]
Abstract
The common approach for the localization of acoustic emission sources in beams requires at least two measurements at different positions on the structure. The acoustic emission event is then located by evaluating the difference of the arrival times of the elastic waves. Here a new method is introduced, which allows the detection and localization of multiple acoustic emission sources with only a single, one point, unidirectional measurement. The method makes use of the time reversal principle and the dispersive behavior of the flexural wave mode. Whereas time-of-arrival (TOA) methods struggle with the distortion of elastic waves due to phase dispersion, the method presented uses the dispersive behavior of guided waves to locate the origin of the acoustic emission event. Therefore, the localization algorithm depends solely on the measured wave form and not on arrival time estimation. The method combines an acoustic emission experiment with a numerical simulation, in which the measured and time reversed displacement history is set as the boundary condition. In this paper, the method is described in detail and the feasibility is experimentally demonstrated by breaking pencil leads on aluminum beams and pultruded carbon fiber reinforced plastic beams according to ASTM E976 (Hsu-Nielsen source). It will be shown, that acoustic emissions are successfully localized even on anisotropic structures and in the case of geometrical complexities such as notches, which lead to reflections, and cross sectional changes, which affect the wave speed. The overall relative error in localizing the acoustic emission sources was found to be below 5%.
Collapse
Affiliation(s)
- R Ernst
- Institute of Mechanical Systems, Swiss Federal Institute of Technology, ETH Zurich, Switzerland.
| | - J Dual
- Institute of Mechanical Systems, Swiss Federal Institute of Technology, ETH Zurich, Switzerland.
| |
Collapse
|
43
|
Richard K, Mann B, Stocker L, Barry E, Qin A, Cole L, Hurley M, Ernst R, Michalek S, Stein D, DeShong P, Vogel S. Novel vaccination strategy: Francisella tularensis vaccines based on functionalized catanionic vesicles (VAC7P.963). The Journal of Immunology 2014. [DOI: 10.4049/jimmunol.192.supp.141.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Francisella tularensis (Ft) is a Gram-negative, immune-evasive coccobacillus that causes tularemia for which there is no FDA-approved vaccine. We have utilized a novel vaccine approach using synthetic nanoparticles made from catanionic surfactant vesicles (V), functionalized by incorporation of either Ft type B Live Vaccine Strain (Ft LVS) or Ft type A Schu S4 strain (Ft Schu S4) components (i.e., LVS-V and Schu S4-V, respectively). Immunization of C57BL/6 mice with bare V partially protected against Ft LVS, presumably through activation of an innate immune response, yet failed to protect against Ft Schu S4. In contrast, immunization with LVS-V fully protected mice against intraperitoneal (i.p.) Ft LVS challenge, while immunization of mice with either LVS-V or Schu S4-V partially protected C57BL/6 mice against an intranasal (i.n.) Ft Schu S4 challenge. LVS-V-immunization, but not immunization with V, elicited high levels of IgG against non-LPS epitopes and these antisera conferred passive protection against challenge with Ft LVS. Our recently published and ongoing studies aim to identify the protein targets of mouse antisera, study the mechanism of non-specific protection gained by immunization with this nanoparticle vaccine platform (adjuvant effect) in Ft LVS challenge, and enhance protection in Ft Schu S4 challenge. Our data extend the utility of functionalized catanionic surfactant vesicles as a vaccine platform for pathogens.
Collapse
Affiliation(s)
- Katharina Richard
- 1Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD
| | - Barbara Mann
- 2Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA
| | - Lenea Stocker
- 3Chemistry and Biochemistry, University of Maryland - College Park, College Park, MD
| | - Eileen Barry
- 4Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD
| | - Aiping Qin
- 2Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA
| | - Leah Cole
- 1Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD
- 8Sanofi Pasteur Biologics Co., Cambridge, MA
| | - Matthew Hurley
- 3Chemistry and Biochemistry, University of Maryland - College Park, College Park, MD
| | - Robert Ernst
- 5Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD
| | | | - Daniel Stein
- 7Cell Biology and Molecular Genetics, University of Maryland - College Park, College Park, MD
| | - Philip DeShong
- 3Chemistry and Biochemistry, University of Maryland - College Park, College Park, MD
| | - Stefanie Vogel
- 1Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD
| |
Collapse
|
44
|
Miao E, Hagar J, Powell D, Aachoui Y, Ernst R. Cytoplasmic LPS activates caspase-11: implications in TLR4-independent endotoxic shock (INM6P.406). The Journal of Immunology 2014. [DOI: 10.4049/jimmunol.192.supp.122.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Inflammatory caspases, such as caspase-1 and -11, mediate innate immune detection of pathogens. Caspase-11 induces pyroptosis, a form of programmed cell death, and specifically defends against bacterial pathogens that invade the cytosol. During endotoxemia, however, excessive caspase-11 activation causes shock. We report that contamination of the cytoplasm by lipopolysaccharide (LPS) is the signal that triggers caspase-11 activation in mice. Specifically, caspase-11 responds to penta- and hexa-acylated lipid A, whereas tetra-acylated lipid A is not detected, providing a mechanism of evasion for cytosol-invasive Francisella. Priming the caspase-11 pathway in vivo resulted in extreme sensitivity to subsequent LPS challenge in both wild type and Tlr4-deficient mice, whereas caspase 11-deficient mice were relatively resistant. Together, our data reveal a new pathway for detecting cytoplasmic LPS.
Collapse
Affiliation(s)
- Edward Miao
- 1Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Jon Hagar
- 1Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Daniel Powell
- 2Department of Microbial Pathogenesis, University of Maryland, Baltimore, MD
| | - Youssef Aachoui
- 1Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Robert Ernst
- 2Department of Microbial Pathogenesis, University of Maryland, Baltimore, MD
| |
Collapse
|
45
|
Spragg K, Letout S, Ernst R, Sneyd A, Fautrelle Y. Instabilities in electromagnetic quasilevitation. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 89:053014. [PMID: 25353887 DOI: 10.1103/physreve.89.053014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Indexed: 06/04/2023]
Abstract
We investigate free-surface instabilities occurring in various industrial processes involving liquid metal. Of particular interest is the behavior of the free surface of a pool of liquid metal when it is submitted to an alternating magnetic field. Experimentally, we study the effect of a vertical alternating medium-frequency magnetic field on an initially circular pool. We observe various types of behavior according to magnetic field amplitude, e.g., axisymmetric deformations, azimuthal mode structures, slow radial oscillation of the pool perimeter, and random rotation of the pool around its center. Drop rotation could be attributed to nonsymmetric shape deformations. The effect of oxidation leads to drastic changes in pool behavior. The experimental results are then compared to a linear stability analysis of the free surface of a circular liquid drop.
Collapse
Affiliation(s)
- Kirk Spragg
- Department of Mathematics, University of Waikato, Hamilton, New Zealand and SIMAP/EPM Laboratory, Grenoble Polytechnic Institute, Grenoble, France
| | - Sebastien Letout
- SIMAP/EPM Laboratory, Grenoble Polytechnic Institute, Grenoble, France
| | - R Ernst
- SIMAP/EPM Laboratory, Grenoble Polytechnic Institute, Grenoble, France
| | - Alfred Sneyd
- Department of Mathematics, University of Waikato, Hamilton, New Zealand
| | - Yves Fautrelle
- SIMAP/EPM Laboratory, Grenoble Polytechnic Institute, Grenoble, France
| |
Collapse
|
46
|
Tennant S, Simon R, Wang J, Pasetti M, Ernst R, Lees A, Galen J, Levine M. Bivalent vaccine strategies for invasive non-typhoidal Salmonella infections. Int J Infect Dis 2014. [DOI: 10.1016/j.ijid.2014.03.426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
|
47
|
Stordeur C, Puth K, Sáenz JP, Ernst R. Crosstalk of lipid and protein homeostasis to maintain membrane function. Biol Chem 2014; 395:313-26. [DOI: 10.1515/hsz-2013-0235] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/21/2013] [Indexed: 01/22/2023]
Abstract
Abstract
Biological membranes are a defining feature of cellular life. They serve as selective diffusion barriers, compartmentalize biochemical processes and protect the cellular milieu. We are only beginning to understand the principles underlying their homeostasis and the functional relevance of their complex compositions. Here, we summarize some recent evidences that suggest an intense crosstalk between the pathways of protein quality control and lipid homeostasis. We discuss paradigms of lipid regulation by protein degradation machineries and highlight the intricate connections between lipid droplet morphology, membrane biogenesis and ER-stress.
Collapse
|
48
|
de Jongh A, Ernst R, Marques L, Hornsveld H. The impact of eye movements and tones on disturbing memories involving PTSD and other mental disorders. J Behav Ther Exp Psychiatry 2013; 44:477-83. [PMID: 23892070 DOI: 10.1016/j.jbtep.2013.07.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 06/23/2013] [Accepted: 07/05/2013] [Indexed: 11/26/2022]
Abstract
BACKGROUND A wide array of experimental studies are supportive of a working memory explanation for the effects of eye movements in EMDR therapy. The working memory account predicts that, as a consequence of competition in working memory, traumatic memories lose their emotional charge. METHOD This study was aimed at investigating (1) the effects of taxing the working memory, as applied in EMDR, during recall of negative memories in 32 patients with posttraumatic stress disorder (PTSD), and 32 patients with other mental disorders, and (2) whether the results would differ between both groups. In a therapeutic session patients were asked to recollect a crucial upsetting memory while, in counterbalanced order (a) performing eye movements, (b) listening to tones and (c) watching a blank wall ('recall only'), each episode lasting 6 min. RESULTS Eye movements were found to be more effective in diminishing the emotionality of the memory than 'recall only'. There was a trend showing that tones were less effective than eye movements, but more effective than 'recall only'. The majority of patients (64%) preferred tones to continue with. The effects of taxing working memory on disturbing memories did not differ between PTSD patients and those diagnosed with other conditions. CONCLUSIONS The findings provide further evidence for the value of employing eye movements in EMDR treatments. The results also support the notion that EMDR is a suitable option for resolving disturbing memories underlying a broader range of mental health problems than PTSD alone.
Collapse
Affiliation(s)
- Ad de Jongh
- Department of Behavioural Sciences, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, The Netherlands.
| | | | | | | |
Collapse
|
49
|
Surma MA, Klose C, Peng D, Shales M, Mrejen C, Stefanko A, Braberg H, Gordon DE, Vorkel D, Ejsing CS, Farese R, Simons K, Krogan NJ, Ernst R. A lipid E-MAP identifies Ubx2 as a critical regulator of lipid saturation and lipid bilayer stress. Mol Cell 2013; 51:519-30. [PMID: 23891562 DOI: 10.1016/j.molcel.2013.06.014] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 05/30/2013] [Accepted: 06/20/2013] [Indexed: 11/17/2022]
Abstract
Biological membranes are complex, and the mechanisms underlying their homeostasis are incompletely understood. Here, we present a quantitative genetic interaction map (E-MAP) focused on various aspects of lipid biology, including lipid metabolism, sorting, and trafficking. This E-MAP contains ∼250,000 negative and positive genetic interaction scores and identifies a molecular crosstalk of protein quality control pathways with lipid bilayer homeostasis. Ubx2p, a component of the endoplasmic-reticulum-associated degradation pathway, surfaces as a key upstream regulator of the essential fatty acid (FA) desaturase Ole1p. Loss of Ubx2p affects the transcriptional control of OLE1, resulting in impaired FA desaturation and a severe shift toward more saturated membrane lipids. Both the induction of the unfolded protein response and aberrant nuclear membrane morphologies observed in cells lacking UBX2 are suppressed by the supplementation of unsaturated FAs. Our results point toward the existence of dedicated bilayer stress responses for membrane homeostasis.
Collapse
Affiliation(s)
- Michal A Surma
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Chiu CS, Peekhaus N, Weber H, Adamski S, Murray EM, Zhang HZ, Zhao JZ, Ernst R, Lineberger J, Huang L, Hampton R, Arnold BA, Vitelli S, Hamuro L, Wang WR, Wei N, Dillon GM, Miao J, Alves SE, Glantschnig H, Wang F, Wilkinson HA. Increased Muscle Force Production and Bone Mineral Density in ActRIIB-Fc-Treated Mature Rodents. J Gerontol A Biol Sci Med Sci 2013; 68:1181-92. [DOI: 10.1093/gerona/glt030] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
|