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Zhu Q, Zhu X, Zhang L. ER membrane complex (EMC): Structure, functions, and roles in diseases. FASEB J 2024; 38:e23539. [PMID: 38498340 DOI: 10.1096/fj.202302266r] [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: 11/02/2023] [Revised: 01/22/2024] [Accepted: 02/21/2024] [Indexed: 03/20/2024]
Abstract
The endoplasmic reticulum (ER) is the largest membrane system in eukaryotic cells and is the primary site for the biosynthesis of lipids and carbohydrates, as well as for the folding, assembly, modification, and transport of secreted and integrated membrane proteins. The ER membrane complex (EMC) on the ER membrane is an ER multiprotein complex that affects the quality control of membrane proteins, which is abundant and widely preserved. Its disruption has been found to affect a wide range of processes, including protein and lipid synthesis, organelle communication, endoplasmic reticulum stress, and viral maturation, and may lead to neurodevelopmental disorders and cancer. Therefore, EMC has attracted the attention of many scholars and become a hot field. In this paper, we summarized the main contributions of the research of EMC in the past nearly 15 years, and reviewed the structure and function of EMC as well as its related diseases. We hope this review will promote further progress of research on EMC.
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Affiliation(s)
- Qi Zhu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Xianjun Zhu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Lin Zhang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
- Qinghai Provincial Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai, China
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Mavuduru VA, Vadupu L, Ghosh KK, Chakrabortty S, Gulyás B, Padmanabhan P, Ball WB. Mitochondrial phospholipid transport: Role of contact sites and lipid transport proteins. Prog Lipid Res 2024; 94:101268. [PMID: 38195013 DOI: 10.1016/j.plipres.2024.101268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 01/03/2024] [Accepted: 01/05/2024] [Indexed: 01/11/2024]
Abstract
One of the major constituents of mitochondrial membranes is the phospholipids, which play a key role in maintaining the structure and the functions of the mitochondria. However, mitochondria do not synthesize most of the phospholipids in situ, necessitating the presence of phospholipid import pathways. Even for the phospholipids, which are synthesized within the inner mitochondrial membrane (IMM), the phospholipid precursors must be imported from outside the mitochondria. Therefore, the mitochondria heavily rely on the phospholipid transport pathways for its proper functioning. Since, mitochondria are not part of a vesicular trafficking network, the molecular mechanisms of how mitochondria receive its phospholipids remain a relevant question. One of the major ways that hydrophobic phospholipids can cross the aqueous barrier of inter or intraorganellar spaces is by apposing membranes, thereby decreasing the distance of transport, or by being sequestered by lipid transport proteins (LTPs). Therefore, with the discovery of LTPs and membrane contact sites (MCSs), we are beginning to understand the molecular mechanisms of phospholipid transport pathways in the mitochondria. In this review, we will present a brief overview of the recent findings on the molecular architecture and the importance of the MCSs, both the intraorganellar and interorganellar contact sites, in facilitating the mitochondrial phospholipid transport. In addition, we will also discuss the role of LTPs for trafficking phospholipids through the intermembrane space (IMS) of the mitochondria. Mechanistic insights into different phospholipid transport pathways of mitochondria could be exploited to vary the composition of membrane phospholipids and gain a better understanding of their precise role in membrane homeostasis and mitochondrial bioenergetics.
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Affiliation(s)
- Vijay Aditya Mavuduru
- Department of Biological Sciences, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur, Andhra Pradesh 522240, India
| | - Lavanya Vadupu
- Department of Biological Sciences, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur, Andhra Pradesh 522240, India
| | - Krishna Kanta Ghosh
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore, 636921, Singapore
| | - Sabyasachi Chakrabortty
- Department of Chemistry, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur, Andhra Pradesh 522502, India
| | - Balázs Gulyás
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore, 636921, Singapore; Cognitive Neuroimaging Centre, Nanyang Technological University, Singapore, 59 Nanyang Drive, 636921, Singapore; Department of Clinical Neuroscience, Karolinska Institute, Stockholm 17176, Sweden
| | - Parasuraman Padmanabhan
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, 59 Nanyang Drive, Singapore, 636921, Singapore; Cognitive Neuroimaging Centre, Nanyang Technological University, Singapore, 59 Nanyang Drive, 636921, Singapore.
| | - Writoban Basu Ball
- Department of Biological Sciences, School of Engineering and Sciences, SRM University AP Andhra Pradesh, Guntur, Andhra Pradesh 522240, India.
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Wu H, Hegde RS. Mechanism of signal-anchor triage during early steps of membrane protein insertion. Mol Cell 2023; 83:961-973.e7. [PMID: 36764302 PMCID: PMC10155758 DOI: 10.1016/j.molcel.2023.01.018] [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: 10/03/2022] [Revised: 12/08/2022] [Accepted: 01/18/2023] [Indexed: 02/11/2023]
Abstract
Most membrane proteins use their first transmembrane domain, known as a signal anchor (SA), for co-translational targeting to the endoplasmic reticulum (ER) via the signal recognition particle (SRP). The SA then inserts into the membrane using either the Sec61 translocation channel or the ER membrane protein complex (EMC) insertase. How EMC and Sec61 collaborate to ensure SA insertion in the correct topology is not understood. Using site-specific crosslinking, we detect a pre-insertion SA intermediate adjacent to EMC. This intermediate forms after SA release from SRP but before ribosome transfer to Sec61. The polypeptide's N-terminal tail samples a cytosolic vestibule bordered by EMC3, from where it can translocate across the membrane concomitant with SA insertion. The ribosome then docks on Sec61, which has an opportunity to insert those SAs skipped by EMC. These results suggest that EMC acts between SRP and Sec61 to triage SAs for insertion during membrane protein biogenesis.
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Affiliation(s)
- Haoxi Wu
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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Tang X, Wei W, Snowball JM, Nakayasu ES, Bell SM, Ansong C, Lin X, Whitsett JA. EMC3 regulates mesenchymal cell survival via control of the mitotic spindle assembly. iScience 2022; 26:105667. [PMID: 36624844 PMCID: PMC9823123 DOI: 10.1016/j.isci.2022.105667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 08/15/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022] Open
Abstract
Eukaryotic cells transit through the cell cycle to produce two daughter cells. Dysregulation of the cell cycle leads to cell death or tumorigenesis. Herein, we found a subunit of the ER membrane complex, EMC3, as a key regulator of cell cycle. Conditional deletion of Emc3 in mouse embryonic mesoderm led to reduced size and patterning defects of multiple organs. Emc3 deficiency impaired cell proliferation, causing spindle assembly defects, chromosome mis-segregation, cell cycle arrest at G2/M, and apoptosis. Upon entry into mitosis, mesenchymal cells upregulate EMC3 protein levels and localize EMC3 to the mitotic centrosomes. Further analysis indicated that EMC3 works together with VCP to tightly regulate the levels and activity of Aurora A, an essential factor for centrosome function and mitotic spindle assembly: while overexpression of EMC3 or VCP degraded Aurora A, their loss led to increased Aurora A stability but reduced Aurora A phosphorylation in mitosis.
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Affiliation(s)
- Xiaofang Tang
- Perinatal Institute, Divisions of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 7029, Cincinnati, OH 45229, USA,Greater Bay Area Institute of Precision Medicine (Guangzhou), Fudan University, 2nd Nanjiang Rd, Nansha District, Guangzhou 511458, China
| | - Wei Wei
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, No. 2005 Songhu Rd, Shanghai 200438, China
| | - John M. Snowball
- Perinatal Institute, Divisions of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 7029, Cincinnati, OH 45229, USA
| | - Ernesto S. Nakayasu
- Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99354, USA
| | - Sheila M. Bell
- Perinatal Institute, Divisions of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 7029, Cincinnati, OH 45229, USA
| | - Charles Ansong
- Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99354, USA
| | - Xinhua Lin
- Greater Bay Area Institute of Precision Medicine (Guangzhou), Fudan University, 2nd Nanjiang Rd, Nansha District, Guangzhou 511458, China,State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, No. 2005 Songhu Rd, Shanghai 200438, China,Corresponding author
| | - Jeffrey A. Whitsett
- Perinatal Institute, Divisions of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 7029, Cincinnati, OH 45229, USA,Corresponding author
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Monzon V, Paysan-Lafosse T, Wood V, Bateman A. Reciprocal best structure hits: using AlphaFold models to discover distant homologues. Bioinform Adv 2022; 2:vbac072. [PMID: 36408459 PMCID: PMC9666668 DOI: 10.1093/bioadv/vbac072] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 09/16/2022] [Accepted: 10/05/2022] [Indexed: 11/17/2022]
Abstract
Motivation The conventional methods to detect homologous protein pairs use the comparison of protein sequences. But the sequences of two homologous proteins may diverge significantly and consequently may be undetectable by standard approaches. The release of the AlphaFold 2.0 software enables the prediction of highly accurate protein structures and opens many opportunities to advance our understanding of protein functions, including the detection of homologous protein structure pairs. Results In this proof-of-concept work, we search for the closest homologous protein pairs using the structure models of five model organisms from the AlphaFold database. We compare the results with homologous protein pairs detected by their sequence similarity and show that the structural matching approach finds a similar set of results. In addition, we detect potential novel homologs solely with the structural matching approach, which can help to understand the function of uncharacterized proteins and make previously overlooked connections between well-characterized proteins. We also observe limitations of our implementation of the structure-based approach, particularly when handling highly disordered proteins or short protein structures. Our work shows that high accuracy protein structure models can be used to discover homologous protein pairs, and we expose areas for improvement of this structural matching approach. Availability and Implementation Information to the discovered homologous protein pairs can be found at the following URL: https://doi.org/10.17863/CAM.87873. The code can be accessed here: https://github.com/VivianMonzon/Reciprocal_Best_Structure_Hits. Supplementary information Supplementary data are available at Bioinformatics Advances online.
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Affiliation(s)
- Vivian Monzon
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton CB21 4HH, UK
| | - Typhaine Paysan-Lafosse
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton CB21 4HH, UK
| | - Valerie Wood
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Alex Bateman
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton CB21 4HH, UK
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Whittsette AL, Wang YJ, Mu TW. The endoplasmic reticulum membrane complex promotes proteostasis of GABA A receptors. iScience 2022; 25:104754. [PMID: 35938049 PMCID: PMC9352529 DOI: 10.1016/j.isci.2022.104754] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 06/30/2022] [Accepted: 07/07/2022] [Indexed: 11/29/2022] Open
Abstract
The endoplasmic reticulum membrane complex (EMC) plays a critical role in the biogenesis of tail-anchored proteins and a subset of multi-pass membrane proteins in the endoplasmic reticulum (ER). However, because of nearly exclusive expression of neurotransmitter-gated ion channels in the central nervous system (CNS), the role of the EMC in their biogenesis is not well understood. In this study, we demonstrated that the EMC positively regulates the surface trafficking and thus function of endogenous γ-aminobutyric acid type A (GABAA) receptors, the primary inhibitory ion channels in the mammalian brain. Moreover, among ten EMC subunits, EMC3 and EMC6 have the most prominent effect, and overexpression of EMC3 or EMC6 is sufficient to restore the function of epilepsy-associated GABAA receptor variants. In addition, EMC3 and EMC6 demonstrate endogenous interactions with major neuroreceptors, which depends on their transmembrane domains, suggesting a general role of the EMC in the biogenesis of neuroreceptors.
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Affiliation(s)
- Angela L. Whittsette
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Ya-Juan Wang
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Ting-Wei Mu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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Ovciarikova J, Oliveira Souza RO, Arrizabalaga G, Sheiner L. Protein control of membrane and organelle dynamics: Insights from the divergent eukaryote Toxoplasma gondii. Curr Opin Cell Biol 2022; 76:102085. [PMID: 35569259 PMCID: PMC9586877 DOI: 10.1016/j.ceb.2022.102085] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 03/28/2022] [Accepted: 04/01/2022] [Indexed: 11/26/2022]
Abstract
Integral membrane protein complexes control key cellular functions in eukaryotes by defining membrane-bound spaces within organelles and mediating inter-organelles contacts. Despite the critical role of membrane complexes in cell biology, most of our knowledge is from a handful of model systems, primarily yeast and mammals, while a full functional and evolutionary understanding remains incomplete without the perspective from a broad range of divergent organisms. Apicomplexan parasites are single-cell eukaryotes whose survival depends on organelle compartmentalisation and communication. Studies of a model apicomplexan, Toxoplasma gondii, reveal unexpected divergence in the composition and function of complexes previously considered broadly conserved, such as the mitochondrial ATP synthase and the tethers mediating ER–mitochondria membrane contact sites. Thus, Toxoplasma joins the repertoire of divergent model eukaryotes whose research completes our understanding of fundamental cell biology.
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Abstract
The endoplasmic reticulum (ER) is the site of membrane protein insertion, folding, and assembly in eukaryotes. Over the past few years, a combination of genetic and biochemical studies have implicated an abundant factor termed the ER membrane protein complex (EMC) in several aspects of membrane protein biogenesis. This large nine-protein complex is built around a deeply conserved core formed by the EMC3-EMC6 subcomplex. EMC3 belongs to the universally conserved Oxa1 superfamily of membrane protein transporters, whereas EMC6 is an ancient, widely conserved obligate partner. EMC has an established role in the insertion of transmembrane domains (TMDs) and less understood roles during the later steps of membrane protein folding and assembly. Several recent structures suggest hypotheses about the mechanism(s) of TMD insertion by EMC, with various biochemical and proteomics studies beginning to reveal the range of EMC's membrane protein substrates. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Ramanujan S Hegde
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom;
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9
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Whitley P, Grau B, Gumbart JC, Martínez-Gil L, Mingarro I. Folding and Insertion of Transmembrane Helices at the ER. Int J Mol Sci 2021; 22:ijms222312778. [PMID: 34884581 PMCID: PMC8657811 DOI: 10.3390/ijms222312778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 10/14/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 01/16/2023] Open
Abstract
In eukaryotic cells, the endoplasmic reticulum (ER) is the entry point for newly synthesized proteins that are subsequently distributed to organelles of the endomembrane system. Some of these proteins are completely translocated into the lumen of the ER while others integrate stretches of amino acids into the greasy 30 Å wide interior of the ER membrane bilayer. It is generally accepted that to exist in this non-aqueous environment the majority of membrane integrated amino acids are primarily non-polar/hydrophobic and adopt an α-helical conformation. These stretches are typically around 20 amino acids long and are known as transmembrane (TM) helices. In this review, we will consider how transmembrane helices achieve membrane integration. We will address questions such as: Where do the stretches of amino acids fold into a helical conformation? What is/are the route/routes that these stretches take from synthesis at the ribosome to integration through the ER translocon? How do these stretches ‘know’ to integrate and in which orientation? How do marginally hydrophobic stretches of amino acids integrate and survive as transmembrane helices?
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Affiliation(s)
- Paul Whitley
- Department of Biology and Biochemistry, Centre for Regenerative Medicine, University of Bath, Bath BA2 7AY, UK;
| | - Brayan Grau
- Department of Biochemistry and Molecular Biology, Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain; (B.G.); (L.M.-G.)
| | - James C. Gumbart
- School of Physics, School of Chemistry and Biochemistry, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Luis Martínez-Gil
- Department of Biochemistry and Molecular Biology, Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain; (B.G.); (L.M.-G.)
| | - Ismael Mingarro
- Department of Biochemistry and Molecular Biology, Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain; (B.G.); (L.M.-G.)
- Correspondence: ; Tel.: +34-963543796
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Pacheco Y, Valeyre D, El Jammal T, Vallee M, Chevalier F, Lamartine J, Sigaudo-Roussel D, Verrier B, Israel-Biet D, Freymond N, Cottin V, Calender A. Autophagy and Mitophagy-Related Pathways at the Crossroads of Genetic Pathways Involved in Familial Sarcoidosis and Host-Pathogen Interactions Induced by Coronaviruses. Cells 2021; 10:1995. [PMID: 34440765 DOI: 10.3390/cells10081995] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/16/2021] [Accepted: 07/29/2021] [Indexed: 12/12/2022] Open
Abstract
Sarcoidosis is a multisystem disease characterized by the development and accumulation of granulomas, the hallmark of an inflammatory process induced by environmental and/or infectious and or genetic factors. This auto-inflammatory disease mainly affects the lungs, the gateway to environmental aggressions and viral infections. We have shown previously that genetic predisposition to sarcoidosis occurring in familial cases is related to a large spectrum of pathogenic variants with, however, a clustering around mTOR (mammalian Target Of Rapamycin)-related pathways and autophagy regulation. The context of the COVID-19 pandemic led us to evaluate whether such genetic defects may increase the risk of a severe course of SARS-CoV2 infection in patients with sarcoidosis. We extended a whole exome screening to 13 families predisposed to sarcoidosis and crossed the genes sharing mutations with the list of genes involved in the SARS-CoV2 host-pathogen protein-protein interactome. A similar analysis protocol was applied to a series of 100 healthy individuals. Using ENRICH.R, a comprehensive gene set enrichment web server, we identified the functional pathways represented in the set of genes carrying deleterious mutations and confirmed the overrepresentation of autophagy- and mitophagy-related functions in familial cases of sarcoidosis. The same protocol was applied to the set of genes common to sarcoidosis and the SARS-CoV2-host interactome and found a significant enrichment of genes related to mitochondrial factors involved in autophagy, mitophagy, and RIG-I-like (Retinoic Acid Inducible Gene 1) Receptor antiviral response signaling. From these results, we discuss the hypothesis according to which sarcoidosis is a model for studying genetic abnormalities associated with host response to viral infections as a consequence of defects in autophagy and mitophagy processes.
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Evers F, Cabrera-Orefice A, Elurbe DM, Kea-Te Lindert M, Boltryk SD, Voss TS, Huynen MA, Brandt U, Kooij TWA. Composition and stage dynamics of mitochondrial complexes in Plasmodium falciparum. Nat Commun 2021; 12:3820. [PMID: 34155201 PMCID: PMC8217502 DOI: 10.1038/s41467-021-23919-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 05/21/2021] [Indexed: 12/19/2022] Open
Abstract
Our current understanding of mitochondrial functioning is largely restricted to traditional model organisms, which only represent a fraction of eukaryotic diversity. The unusual mitochondrion of malaria parasites is a validated drug target but remains poorly understood. Here, we apply complexome profiling to map the inventory of protein complexes across the pathogenic asexual blood stages and the transmissible gametocyte stages of Plasmodium falciparum. We identify remarkably divergent composition and clade-specific additions of all respiratory chain complexes. Furthermore, we show that respiratory chain complex components and linked metabolic pathways are up to 40-fold more prevalent in gametocytes, while glycolytic enzymes are substantially reduced. Underlining this functional switch, we find that cristae are exclusively present in gametocytes. Leveraging these divergent properties and stage dynamics for drug development presents an attractive opportunity to discover novel classes of antimalarials and increase our repertoire of gametocytocidal drugs.
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Affiliation(s)
- Felix Evers
- Department of Medical Microbiology, Radboudumc Center for Infectious Diseases, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Alfredo Cabrera-Orefice
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Dei M Elurbe
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Mariska Kea-Te Lindert
- Electron Microscopy Center, RTC Microscopy, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
- Department of Cell Biology, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Sylwia D Boltryk
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Martijn A Huynen
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Ulrich Brandt
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Taco W A Kooij
- Department of Medical Microbiology, Radboudumc Center for Infectious Diseases, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands.
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12
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Yu R, Shen X, Liu M, Liu X, Yin Z, Li X, Feng W, Hu J, Zhang H, Zheng X, Wang P, Zhang Z. The rice blast fungus MoRgs1 functioning in cAMP signaling and pathogenicity is regulated by casein kinase MoCk2 phosphorylation and modulated by membrane protein MoEmc2. PLoS Pathog 2021; 17:e1009657. [PMID: 34133468 PMCID: PMC8208561 DOI: 10.1371/journal.ppat.1009657] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [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: 01/22/2021] [Accepted: 05/19/2021] [Indexed: 12/31/2022] Open
Abstract
GTP-binding protein (G-protein) and regulator of G-protein signaling (RGS) mediated signal transduction are critical in the growth and virulence of the rice blast pathogen Magnaporthe oryzae. We have previously reported that there are eight RGS and RGS-like proteins named MoRgs1 to MoRgs8 playing distinct and shared regulatory functions in M. oryzae and that MoRgs1 has a more prominent role compared to others in the fungus. To further explore the unique regulatory mechanism of MoRgs1, we screened a M. oryzae cDNA library for genes encoding MoRgs1-interacting proteins and identified MoCkb2, one of the two regulatory subunits of the casein kinase (CK) 2 MoCk2. We found that MoCkb2 and the sole catalytic subunit MoCka1 are required for the phosphorylation of MoRgs1 at the plasma membrane (PM) and late endosome (LE). We further found that an endoplasmic reticulum (ER) membrane protein complex (EMC) subunit, MoEmc2, modulates the phosphorylation of MoRgs1 by MoCk2. Interestingly, this phosphorylation is also essential for the GTPase-activating protein (GAP) function of MoRgs1. The balance among MoRgs1, MoCk2, and MoEmc2 ensures normal operation of the G-protein MoMagA-cAMP signaling required for appressorium formation and pathogenicity of the fungus. This has been the first report that an EMC subunit is directly linked to G-protein signaling through modulation of an RGS-casein kinase interaction. G-proteins play a significant role in signal perception and transduction during pathogen and host interactions. In the rice blast fungus M. oryzae, previous studies demonstrated that G-protein/cAMP signaling are important for appressorium formation and pathogenicity. One of the eight regulator of G-protein signaling (RGS) and RGS-like proteins, MoRgs1, targets G-protein MoMagA to regulate cAMP levels and growth and virulence of the fungus; however, how MoRgs1 exhibits this function and its own regulation indifferent from other RGS and RGS-like proteins are not clear. We here demonstrated that MoRgs1 is subject to regulation by the casein kinase 2 MoCk2 through protein phosphorylation, and this regulation is also essential for the GTPase-activating protein (GAP) function of MoRgs1. We also showed that the endoplasmic reticulum (ER) membrane complex (EMC) subunit MoEmc2 modulates MoCk2-mediated MoRgs1 phosphorylation. Balanced interactions among MoRgs1, MoEmc2, and MoCk2 ensure normal appressorium formation and pathogenicity of M. oryzae.
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Affiliation(s)
- Rui Yu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Xuetong Shen
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Muxing Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Xinyu Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Ziyi Yin
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Xiao Li
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Wanzhen Feng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Jiexiong Hu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Xiaobo Zheng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Ping Wang
- Departments of Microbiology, Immunology, and Parasitology, and Pediatrics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China, The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
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13
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Yang M, Li S, Liu W, Li X, He Y, Yang Y, Sun K, Zhang L, Tian W, Duan L, Chen H, Yao D, Yang Z, Zhu X. The ER membrane protein complex subunit Emc3 controls angiogenesis via the FZD4/WNT signaling axis. Sci China Life Sci 2021. [PMID: 34128175 DOI: 10.1007/s11427-021-1941-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/29/2021] [Indexed: 02/08/2023]
Abstract
The endoplasmic reticulum (ER) membrane protein complex (EMC) regulates the synthesis and quality control of membrane proteins with multiple transmembrane domains. One of the membrane spanning subunits, EMC3, is a core member of the EMC complex that provides essential hydrophilic vestibule for substrate insertion. Here, we show that the EMC subunit Emc3 plays critical roles in the retinal vascular angiogenesis by regulating Norrin/Wnt signaling. Postnatal endothelial cell (EC)-specific deletion of Emc3 led to retarded retinal vascular development with a hyperpruned vascular network, the appearance of blunt-ended, aneurysm-like tip endothelial cells (ECs) with reduced numbers of filopodia and leakage of erythrocytes at the vascular front. Diminished tube formation and cell proliferation were also observed in EMC3 depleted human retinal endothelial cells (HRECs). We then discovered a critical role for EMC3 in expression of FZD4 receptor of β-catenin signaling using RNA sequencing, real-time quantitative PCR (RT-qPCR) and luciferase reporter assay. Moreover, augmentation of Wnt activity via lithium chloride (LiCl) treatment remarkably enhanced β-catenin signaling and cell proliferation of HRECs. Additionally, LiCl partially reversed the angiogenesis defects in Emc3-cKO mice. Our data reveal that Emc3 plays essential roles in angiogenesis through direct control of FZD4 expression and Norrin/β-catenin signaling.
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14
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Shao DD, Straussberg R, Ahmed H, Khan A, Tian S, Hill RS, Smith RS, Majmundar AJ, Ameziane N, Neil JE, Yang E, Al Tenaiji A, Jamuar SS, Schlaeger TM, Al-Saffar M, Hovel I, Al-Shamsi A, Basel-Salmon L, Amir AZ, Rento LM, Lim JY, Ganesan I, Shril S, Evrony G, Barkovich AJ, Bauer P, Hildebrandt F, Dong M, Borck G, Beetz C, Al-Gazali L, Eyaid W, Walsh CA. A recurrent, homozygous EMC10 frameshift variant is associated with a syndrome of developmental delay with variable seizures and dysmorphic features. Genet Med 2021; 23:1158-1162. [PMID: 33531666 PMCID: PMC8187145 DOI: 10.1038/s41436-021-01097-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 12/28/2020] [Accepted: 01/04/2021] [Indexed: 01/10/2023] Open
Abstract
PURPOSE The endoplasmic reticulum membrane complex (EMC) is a highly conserved, multifunctional 10-protein complex related to membrane protein biology. In seven families, we identified 13 individuals with highly overlapping phenotypes who harbor a single identical homozygous frameshift variant in EMC10. METHODS Using exome, genome, and Sanger sequencing, a recurrent frameshift EMC10 variant was identified in affected individuals in an international cohort of consanguineous families. Multiple families were independently identified and connected via Matchmaker Exchange and internal databases. We assessed the effect of the frameshift variant on EMC10 RNA and protein expression and evaluated EMC10 expression in normal human brain tissue using immunohistochemistry. RESULTS A homozygous variant EMC10 c.287delG (Refseq NM_206538.3, p.Gly96Alafs*9) segregated with affected individuals in each family, who exhibited a phenotypic spectrum of intellectual disability (ID) and global developmental delay (GDD), variable seizures and variable dysmorphic features (elongated face, curly hair, cubitus valgus, and arachnodactyly). The variant arose on two founder haplotypes and results in significantly reduced EMC10 RNA expression and an unstable truncated EMC10 protein. CONCLUSION We propose that a homozygous loss-of-function variant in EMC10 causes a novel syndromic neurodevelopmental phenotype. Remarkably, the recurrent variant is likely the result of a hypermutable site and arose on distinct founder haplotypes.
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Affiliation(s)
- Diane D Shao
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
| | - Rachel Straussberg
- Neurogenetics Clinic, Neurology Unit, Schneider Children Medical Center, Petah Tikvah, Israel
- Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel
| | - Hind Ahmed
- Genetics Division, Department of Pediatrics, King Abdullah International Medical Research Centre, King Saud bin Abdulaziz University for Health Science, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia
| | - Amjad Khan
- Genetics Division, Department of Pediatrics, King Abdullah International Medical Research Centre, King Saud bin Abdulaziz University for Health Science, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia
| | - Songhai Tian
- Department of Urology, Boston Children's Hospital, and Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - R Sean Hill
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
- Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA
| | - Richard S Smith
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
| | - Amar J Majmundar
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
| | | | - Jennifer E Neil
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
- Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA
| | - Edward Yang
- Department of Radiology, Boston Children's Hospital, Boston, MA, USA
| | - Amal Al Tenaiji
- Medical Institute of Medical Affairs, Sheikh Khalifa Medica City, Abu Dhabi, UAE
| | - Saumya S Jamuar
- Department of Pediatrics, KK Women's and Children's Hospital, Ramat Aviv, Israel
- SingHealth Duke-NUS Genomic Medicine Centre, Singapore, Singapore
| | - Thorsten M Schlaeger
- Stem Cell Program, Boston Children's Hospital, Harvard Medical School, and Harvard Stem Cell Institute, Harvard University, Boston, MA, USA
| | - Muna Al-Saffar
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatrics, United Arab Emirates University, Abu Dhabi, UAE
| | | | - Aisha Al-Shamsi
- Division of Genetics, Department of Pediatrics, Tawam Hospital, Al Ain, UAE
| | - Lina Basel-Salmon
- Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel
- Raphael Recanati Genetic Institute, Rabin Medical Center-Beilinson Hospital and Pediatric Genetics Clinic, Schneider Children's Medical Center, and Felsenstein Medical Research Center, Petah Tikvah, Israel
| | - Achiya Z Amir
- Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel
- Pediatric Gastroenterology, Hepatology and Nutrition Clinic, Dana-Dwek Children's Hospital, Tel Aviv Medical Center, Ramat Aviv, Israel
| | - Lariza M Rento
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
- Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA
| | - Jiin Ying Lim
- Department of Pediatrics, KK Women's and Children's Hospital, Ramat Aviv, Israel
- SingHealth Duke-NUS Genomic Medicine Centre, Singapore, Singapore
| | - Indra Ganesan
- Department of Pediatrics, KK Women's and Children's Hospital, Ramat Aviv, Israel
| | - Shirlee Shril
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
| | - Gilad Evrony
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
- New York University School of Medicine, Center for Human Genetics & Genomics, New York, NY, USA
| | - A James Barkovich
- Neuroradiology, University of California at San Francisco, San Francisco, CA, USA
| | | | - Friedhelm Hildebrandt
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
| | - Min Dong
- Department of Urology, Boston Children's Hospital, and Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Guntram Borck
- Center for Rare Diseases (ZSE Ulm), Ulm University Medical Center, Ulm, Germany
- genetikum, Neu-Ulm, Germany
| | | | - Lihadh Al-Gazali
- Department of Pediatrics, United Arab Emirates University, Al Ain, UAE
| | - Wafaa Eyaid
- Genetics Division, Department of Pediatrics, King Abdullah International Medical Research Centre, King Saud bin Abdulaziz University for Health Science, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia
| | - Christopher A Walsh
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA.
- Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA.
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15
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Pleiner T, Hazu M, Tomaleri GP, Januszyk K, Oania RS, Sweredoski MJ, Moradian A, Guna A, Voorhees RM. WNK1 is an assembly factor for the human ER membrane protein complex. Mol Cell 2021; 81:2693-2704.e12. [PMID: 33964204 DOI: 10.1016/j.molcel.2021.04.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 03/02/2021] [Accepted: 04/14/2021] [Indexed: 12/13/2022]
Abstract
The assembly of nascent proteins into multi-subunit complexes is a tightly regulated process that must occur at high fidelity to maintain cellular homeostasis. The ER membrane protein complex (EMC) is an essential insertase that requires seven membrane-spanning and two soluble cytosolic subunits to function. Here, we show that the kinase with no lysine 1 (WNK1), known for its role in hypertension and neuropathy, functions as an assembly factor for the human EMC. WNK1 uses a conserved amphipathic helix to stabilize the soluble subunit, EMC2, by binding to the EMC2-8 interface. Shielding this hydrophobic surface prevents promiscuous interactions of unassembled EMC2 and directly competes for binding of E3 ubiquitin ligases, permitting assembly. Depletion of WNK1 thus destabilizes both the EMC and its membrane protein clients. This work describes an unexpected role for WNK1 in protein biogenesis and defines the general requirements of an assembly factor that will apply across the proteome.
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Affiliation(s)
- Tino Pleiner
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Masami Hazu
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Giovani Pinton Tomaleri
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Kurt Januszyk
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Robert S Oania
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Michael J Sweredoski
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Annie Moradian
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Alina Guna
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Rebecca M Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA.
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16
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Santos HJ, Nozaki T. Interorganellar communication and membrane contact sites in protozoan parasites. Parasitol Int 2021; 83:102372. [PMID: 33933652 DOI: 10.1016/j.parint.2021.102372] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [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: 01/06/2021] [Revised: 04/21/2021] [Accepted: 04/27/2021] [Indexed: 12/29/2022]
Abstract
A key characteristic of eukaryotic cells is the presence of organelles with discrete boundaries and functions. Such subcellular compartmentalization into organelles necessitates platforms for communication and material exchange between each other which often involves vesicular trafficking and associated processes. Another way is via the close apposition between organellar membranes, called membrane contact sites (MCSs). Apart from lipid transfer, MCSs have been implicated to mediate in various cellular processes including ion transport, apoptosis, and organelle dynamics. In mammalian and yeast cells, contact sites have been reported between the membranes of the following: the endoplasmic reticulum (ER) and the plasma membrane (PM), ER and the Golgi apparatus, ER and endosomes (i.e., vacuoles, lysosomes), ER and lipid droplets (LD), the mitochondria and vacuoles, the nucleus and vacuoles, and the mitochondria and lipid droplets, whereas knowledge of MCSs in non-model organisms such as protozoan parasites is extremely limited. Growing evidence suggests that MCSs play more general and conserved roles in cell physiology. In this mini review, we summarize and discuss representative MCSs in divergent parasitic protozoa, and highlight the universality, diversity, and the contribution of MCSs to parasitism.
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Affiliation(s)
- Herbert J Santos
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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17
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Abstract
Protein synthesis is an energetically costly, complex and risky process. Aberrant protein biogenesis can result in cellular toxicity and disease, with membrane-embedded proteins being particularly challenging for the cell. In order to protect the cell from consequences of defects in membrane proteins, quality control systems act to maintain protein homeostasis. The majority of these pathways act post-translationally; however, recent evidence reveals that membrane proteins are also subject to co-translational quality control during their synthesis in the endoplasmic reticulum (ER). This newly identified quality control pathway employs components of the cytosolic ribosome-associated quality control (RQC) machinery but differs from canonical RQC in that it responds to biogenesis state of the substrate rather than mRNA aberrations. This ER-associated RQC (ER-RQC) is sensitive to membrane protein misfolding and malfunctions in the ER insertion machinery. In this Review, we discuss the advantages of co-translational quality control of membrane proteins, as well as potential mechanisms of substrate recognition and degradation. Finally, we discuss some outstanding questions concerning future studies of ER-RQC of membrane proteins.
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Affiliation(s)
- Ben P Phillips
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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18
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Miller-Vedam LE, Bräuning B, Popova KD, Schirle Oakdale NT, Bonnar JL, Prabu JR, Boydston EA, Sevillano N, Shurtleff MJ, Stroud RM, Craik CS, Schulman BA, Frost A, Weissman JS. Structural and mechanistic basis of the EMC-dependent biogenesis of distinct transmembrane clients. eLife 2020; 9:e62611. [PMID: 33236988 PMCID: PMC7785296 DOI: 10.7554/elife.62611] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [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: 08/30/2020] [Accepted: 11/17/2020] [Indexed: 12/11/2022] Open
Abstract
Membrane protein biogenesis in the endoplasmic reticulum (ER) is complex and failure-prone. The ER membrane protein complex (EMC), comprising eight conserved subunits, has emerged as a central player in this process. Yet, we have limited understanding of how EMC enables insertion and integrity of diverse clients, from tail-anchored to polytopic transmembrane proteins. Here, yeast and human EMC cryo-EM structures reveal conserved intricate assemblies and human-specific features associated with pathologies. Structure-based functional studies distinguish between two separable EMC activities, as an insertase regulating tail-anchored protein levels and a broader role in polytopic membrane protein biogenesis. These depend on mechanistically coupled yet spatially distinct regions including two lipid-accessible membrane cavities which confer client-specific regulation, and a non-insertase EMC function mediated by the EMC lumenal domain. Our studies illuminate the structural and mechanistic basis of EMC's multifunctionality and point to its role in differentially regulating the biogenesis of distinct client protein classes.
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Affiliation(s)
- Lakshmi E Miller-Vedam
- Molecular, Cellular, and Computational Biophysics Graduate Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Bastian Bräuning
- Department of Molecular Machines and Signaling, Max Planck Institute of BiochemistryMartinsriedGermany
| | - Katerina D Popova
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Biomedical Sciences Graduate Program, University of California, San FranciscoSan FranciscoUnited States
| | - Nicole T Schirle Oakdale
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Jessica L Bonnar
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Jesuraj R Prabu
- Department of Molecular Machines and Signaling, Max Planck Institute of BiochemistryMartinsriedGermany
| | - Elizabeth A Boydston
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Natalia Sevillano
- Department of Pharmaceutical Chemistry, University of California, San FranciscoSan FranciscoUnited States
| | - Matthew J Shurtleff
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Charles S Craik
- Department of Pharmaceutical Chemistry, University of California, San FranciscoSan FranciscoUnited States
| | - Brenda A Schulman
- Department of Molecular Machines and Signaling, Max Planck Institute of BiochemistryMartinsriedGermany
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Jonathan S Weissman
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Howard Hughes Medical InstituteChevy ChaseUnited States
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19
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Tan JH, Cao RC, Zhou L, Zhou ZT, Chen HJ, Xu J, Chen XM, Jin YC, Lin JY, Qi ZC, Zeng JL, Li SJ, Luo M, Hu GD, Jin J, Zhang GW. EMC6 regulates acinar apoptosis via APAF1 in acute and chronic pancreatitis. Cell Death Dis 2020; 11:966. [PMID: 33177505 PMCID: PMC7658364 DOI: 10.1038/s41419-020-03177-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 10/24/2020] [Accepted: 10/27/2020] [Indexed: 02/07/2023]
Abstract
Treatment of acute pancreatitis (AP) and chronic pancreatitis (CP) remains problematic due to a lack of knowledge about disease-specific regulatory targets and mechanisms. The purpose of this study was to screen proteins related to endoplasmic reticulum (ER) stress and apoptosis pathways that may play a role in pancreatitis. Human pancreatic tissues including AP, CP, and healthy volunteers were collected during surgery. Humanized PRSS1 (protease serine 1) transgenic (PRSS1Tg) mice were constructed and treated with caerulein to mimic the development of human AP and CP. Potential regulatory proteins in pancreatitis were identified by proteomic screen using pancreatic tissues of PRSS1Tg AP mice. Adenoviral shRNA-mediated knockdown of identified proteins, followed by functional assays was performed to validate their roles. Functional analyses included transmission electron microscopy for ultrastructural analysis; qRT-PCR, western blotting, co-immunoprecipitation, immunohistochemistry, and immunofluorescence for assessment of gene or protein expression, and TUNEL assays for assessment of acinar cell apoptosis. Humanized PRSS1Tg mice could mimic the development of human pancreatic inflammatory diseases. EMC6 and APAF1 were identified as potential regulatory molecules in AP and CP models by proteomic analysis. Both EMC6 and APAF1 regulated apoptosis and inflammatory injury in pancreatic inflammatory diseases. Moreover, APAF1 was regulated by EMC6, induced apoptosis to injure acinar cells and promoted inflammation. In the progression of pancreatitis, EMC6 was activated and then upregulated APAF1 to induce acinar cell apoptosis and inflammatory injury. These findings suggest that EMC6 may be a new therapeutic target for the treatment of pancreatic inflammatory diseases.
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Affiliation(s)
- Jie-Hui Tan
- Division of Hepatobiliopancreatic Surgery, Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Rong-Chang Cao
- Division of Hepatobiliopancreatic Surgery, Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Lei Zhou
- Division of Hepatobiliopancreatic Surgery, Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Zhi-Tao Zhou
- Department of the Electronic Microscope Room, Central Laboratory, Southern Medical University, Guangzhou, China
| | - Huo-Ji Chen
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
| | - Jia Xu
- Department of Pathophysiology, Southern Medical University, Guangzhou, China
| | - Xue-Mei Chen
- Department of Occupational Health and Medicine, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
| | - Yang-Chen Jin
- The First Clinical Medical College, Southern Medical University, Guangzhou, China
| | - Jia-Yu Lin
- The First Clinical Medical College, Southern Medical University, Guangzhou, China
| | - Zhao-Chang Qi
- The First Clinical Medical College, Southern Medical University, Guangzhou, China
| | - Jun-Ling Zeng
- Laboratory Animal Research Center of Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Shu-Ji Li
- Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou, China
| | - Min Luo
- Department of Laboratory Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Guo-Dong Hu
- Department of Respiratory and Crit Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Jin Jin
- Department of Gynaecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Guo-Wei Zhang
- Division of Hepatobiliopancreatic Surgery, Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China.
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20
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Tian S, Wu Q, Zhou B, Choi MY, Ding B, Yang W, Dong M. Proteomic Analysis Identifies Membrane Proteins Dependent on the ER Membrane Protein Complex. Cell Rep 2020; 28:2517-2526.e5. [PMID: 31484065 PMCID: PMC6749609 DOI: 10.1016/j.celrep.2019.08.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/18/2019] [Accepted: 07/30/2019] [Indexed: 02/04/2023] Open
Abstract
The endoplasmic reticulum (ER) membrane protein complex (EMC) is a key contributor to biogenesis and membrane integration of transmembrane proteins, but our understanding of its mechanisms and the range of EMC-dependent proteins remains incomplete. Here, we carried out an unbiased mass spectrometry (MS)-based quantitative proteomic analysis comparing membrane proteins in EMC-deficient cells to wild-type (WT) cells and identified 36 EMC-dependent membrane proteins and 171 EMC-independent membrane proteins. Of these, six EMC-dependent and six EMC-independent proteins were further independently validated. We found that a common feature among EMC-dependent proteins is that they contain transmembrane domains (TMDs) with polar and/or charged residues. Mutagenesis studies demonstrate that EMC dependency can be converted in cells by removing or introducing polar and/or charged residues within TMDs. Our studies expand the list of validated EMC-dependent and EMC-independent proteins and suggest that the EMC is involved in handling TMDs with residues challenging for membrane integration. The endoplasmic reticulum membrane protein complex (EMC) contributes to the biogenesis of transmembrane proteins. Using mass spectrometry-based quantitative proteomic analysis, Tian et al. identify EMC-dependent and EMC-independent proteins. The authors find evidence that the EMC is involved in handling transmembrane domains with polar and/or charged residues that are challenging for membrane integration.
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Affiliation(s)
- Songhai Tian
- Department of Urology, Boston Children's Hospital, and Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Quan Wu
- Department of Urology, Boston Children's Hospital, and Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Central Laboratory of Medical Research Centre, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, People's Republic of China
| | - Bo Zhou
- Division of Cancer Biology and Therapeutics, Departments of Surgery and Biomedical Sciences, Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Mei Yuk Choi
- Division of Genetics, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA
| | - Bo Ding
- Bonacept LLC, San Diego, CA 92122, USA
| | - Wei Yang
- Division of Cancer Biology and Therapeutics, Departments of Surgery and Biomedical Sciences, Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Min Dong
- Department of Urology, Boston Children's Hospital, and Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA.
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21
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Marquez J, Criscione J, Charney RM, Prasad MS, Hwang WY, Mis EK, García-Castro MI, Khokha MK. Disrupted ER membrane protein complex-mediated topogenesis drives congenital neural crest defects. J Clin Invest 2020; 130:813-826. [PMID: 31904590 DOI: 10.1172/jci129308] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 10/22/2019] [Indexed: 12/20/2022] Open
Abstract
Multipass membrane proteins have a myriad of functions, including transduction of cell-cell signals, ion transport, and photoreception. Insertion of these proteins into the membrane depends on the endoplasmic reticulum (ER) membrane protein complex (EMC). Recently, birth defects have been observed in patients with variants in the gene encoding a member of this complex, EMC1. Patient phenotypes include congenital heart disease, craniofacial malformations, and neurodevelopmental disease. However, a molecular connection between EMC1 and these birth defects is lacking. Using Xenopus, we identified defects in neural crest cells (NCCs) upon emc1 depletion. We then used unbiased proteomics and discovered a critical role for emc1 in WNT signaling. Consistent with this, readouts of WNT signaling and Frizzled (Fzd) levels were reduced in emc1-depleted embryos, while NCC defects could be rescued with β-catenin. Interestingly, other transmembrane proteins were mislocalized upon emc1 depletion, providing insight into additional patient phenotypes. To translate our findings back to humans, we found that EMC1 was necessary for human NCC development in vitro. Finally, we tested patient variants in our Xenopus model and found the majority to be loss-of-function alleles. Our findings define molecular mechanisms whereby EMC1 dysfunction causes disease phenotypes through dysfunctional multipass membrane protein topogenesis.
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Affiliation(s)
- Jonathan Marquez
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - June Criscione
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Rebekah M Charney
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, California, USA
| | - Maneeshi S Prasad
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, California, USA
| | - Woong Y Hwang
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Emily K Mis
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Martín I García-Castro
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, California, USA
| | - Mustafa K Khokha
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
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22
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Abstract
The ER membrane complex (EMC) cooperates with the Sec61 translocon to co-translationally insert a transmembrane helix (TMH) of many multi-pass integral membrane proteins into the ER membrane, and it is also responsible for inserting the TMH of some tail-anchored proteins 1–3. How EMC accomplishes this feat has been unclear. Here we report the first cryo-EM structure of the eukaryotic EMC. We found that the Saccharomyces cerevisiae EMC contains eight subunits (Emc1–6, 7, and 10); has a large lumenal region and a smaller cytosolic region; and has a transmembrane region formed by Emc4, 5, and 6 plus the transmembrane domains (TMDs) of Emc1 and 3. We identified a 5-TMH fold centered around Emc3 that resembles the prokaryotic insertase YidC and that delineates a largely hydrophilic client pocket. The TMD of Emc4 tilts away from the main transmembrane region of EMC and is partially mobile. Mutational studies demonstrated that Emc4 flexibility and the hydrophilicity of the client pocket are required for EMC function. The EMC structure reveals a remarkable evolutionary conservation with the prokaryotic insertases 4,5; suggests a similar mechanism of TMH insertion; and provides a framework for detailed understanding of membrane insertion for numerous eukaryotic integral membrane proteins and tail-anchored proteins.
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Affiliation(s)
- Lin Bai
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA.
| | - Qinglong You
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Xiang Feng
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Amanda Kovach
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Huilin Li
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA.
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23
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O'Donnell JP, Phillips BP, Yagita Y, Juszkiewicz S, Wagner A, Malinverni D, Keenan RJ, Miller EA, Hegde RS. The architecture of EMC reveals a path for membrane protein insertion. eLife 2020; 9:e57887. [PMID: 32459176 PMCID: PMC7292650 DOI: 10.7554/elife.57887] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [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: 04/15/2020] [Accepted: 05/26/2020] [Indexed: 12/29/2022] Open
Abstract
Approximately 25% of eukaryotic genes code for integral membrane proteins that are assembled at the endoplasmic reticulum. An abundant and widely conserved multi-protein complex termed EMC has been implicated in membrane protein biogenesis, but its mechanism of action is poorly understood. Here, we define the composition and architecture of human EMC using biochemical assays, crystallography of individual subunits, site-specific photocrosslinking, and cryo-EM reconstruction. Our results suggest that EMC's cytosolic domain contains a large, moderately hydrophobic vestibule that can bind a substrate's transmembrane domain (TMD). The cytosolic vestibule leads into a lumenally-sealed, lipid-exposed intramembrane groove large enough to accommodate a single substrate TMD. A gap between the cytosolic vestibule and intramembrane groove provides a potential path for substrate egress from EMC. These findings suggest how EMC facilitates energy-independent membrane insertion of TMDs, explain why only short lumenal domains are translocated by EMC, and constrain models of EMC's proposed chaperone function.
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Affiliation(s)
| | - Ben P Phillips
- MRC Laboratory of Molecular BiologyCambridgeUnited Kingdom
| | - Yuichi Yagita
- MRC Laboratory of Molecular BiologyCambridgeUnited Kingdom
| | | | | | | | - Robert J Keenan
- Department of Biochemistry and Molecular Biology, The University of ChicagoChicagoUnited States
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24
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Pleiner T, Tomaleri GP, Januszyk K, Inglis AJ, Hazu M, Voorhees RM. Structural basis for membrane insertion by the human ER membrane protein complex. Science 2020; 369:433-436. [PMID: 32439656 DOI: 10.1126/science.abb5008] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 05/12/2020] [Indexed: 12/23/2022]
Abstract
A defining step in the biogenesis of a membrane protein is the insertion of its hydrophobic transmembrane helices into the lipid bilayer. The nine-subunit endoplasmic reticulum (ER) membrane protein complex (EMC) is a conserved co- and posttranslational insertase at the ER. We determined the structure of the human EMC in a lipid nanodisc to an overall resolution of 3.4 angstroms by cryo-electron microscopy, permitting building of a nearly complete atomic model. We used structure-guided mutagenesis to demonstrate that substrate insertion requires a methionine-rich cytosolic loop and occurs via an enclosed hydrophilic vestibule within the membrane formed by the subunits EMC3 and EMC6. We propose that the EMC uses local membrane thinning and a positively charged patch to decrease the energetic barrier for insertion into the bilayer.
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Affiliation(s)
- Tino Pleiner
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Giovani Pinton Tomaleri
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Kurt Januszyk
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Alison J Inglis
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Masami Hazu
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Rebecca M Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA.
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25
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Kohler V, Aufschnaiter A, Büttner S. Closing the Gap: Membrane Contact Sites in the Regulation of Autophagy. Cells 2020; 9:E1184. [PMID: 32397538 PMCID: PMC7290522 DOI: 10.3390/cells9051184] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [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: 04/17/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 12/14/2022] Open
Abstract
In all eukaryotic cells, intracellular organization and spatial separation of incompatible biochemical processes is established by individual cellular subcompartments in form of membrane-bound organelles. Virtually all of these organelles are physically connected via membrane contact sites (MCS), allowing interorganellar communication and a functional integration of cellular processes. These MCS coordinate the exchange of diverse metabolites and serve as hubs for lipid synthesis and trafficking. While this of course indirectly impacts on a plethora of biological functions, including autophagy, accumulating evidence shows that MCS can also directly regulate autophagic processes. Here, we focus on the nexus between interorganellar contacts and autophagy in yeast and mammalian cells, highlighting similarities and differences. We discuss MCS connecting the ER to mitochondria or the plasma membrane, crucial for early steps of both selective and non-selective autophagy, the yeast-specific nuclear-vacuolar tethering system and its role in microautophagy, the emerging function of distinct autophagy-related proteins in organellar tethering as well as novel MCS transiently emanating from the growing phagophore and mature autophagosome.
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Affiliation(s)
- Verena Kohler
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden;
| | - Andreas Aufschnaiter
- Department of Biochemistry and Biophysics, Stockholm University, 106 91 Stockholm, Sweden;
| | - Sabrina Büttner
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden;
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
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26
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Volkmar N, Christianson JC. Squaring the EMC - how promoting membrane protein biogenesis impacts cellular functions and organismal homeostasis. J Cell Sci 2020; 133:133/8/jcs243519. [PMID: 32332093 PMCID: PMC7188443 DOI: 10.1242/jcs.243519] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [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] [Indexed: 12/13/2022] Open
Abstract
Integral membrane proteins play key functional roles at organelles and the plasma membrane, necessitating their efficient and accurate biogenesis to ensure appropriate targeting and activity. The endoplasmic reticulum membrane protein complex (EMC) has recently emerged as an important eukaryotic complex for biogenesis of integral membrane proteins by promoting insertion and stability of atypical and sub-optimal transmembrane domains (TMDs). Although confirmed as a bona fide complex almost a decade ago, light is just now being shed on the mechanism and selectivity underlying the cellular responsibilities of the EMC. In this Review, we revisit the myriad of functions attributed the EMC through the lens of these new mechanistic insights, to address questions of the cellular and organismal roles the EMC has evolved to undertake. Summary: The EMC is an important factor facilitating membrane protein biogenesis. Here we discuss the broad cellular and organismal responsibilities overseen by client proteins requiring the EMC for maturation.
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Affiliation(s)
- Norbert Volkmar
- Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - John C Christianson
- Oxford Centre for Translational Myeloma Research, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Headington, Oxford OX3 7LD, UK
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27
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Abstract
Due to their topology tail-anchored (TA) proteins must target to the membrane independently of the co-translational route defined by the signal sequence recognition particle (SRP), its receptor and the translocon Sec61. More than a decade of work has extensively characterized a highly conserved pathway, the yeast GET or mammalian TRC40 pathway, which is capable of countering the biogenetic challenge posed by the C-terminal TA anchor. In this review we briefly summarize current models of this targeting route and focus on emerging aspects such as the intricate interplay with the proteostatic network of cells and with other targeting pathways. Importantly, we consider the lessons provided by the in vivo analysis of the pathway in different model organisms and by the consideration of its full client spectrum in more recent studies. This analysis of the state of the field highlights directions in which the current models may be experimentally probed and conceptually extended.
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Affiliation(s)
- Nica Borgese
- Institute of Neuroscience and BIOMETRA Department, Consiglio Nazionale delle Ricerche and Università degli Studi di Milano, via Vanvitelli 32, 20129, Milan, Italy.
| | - Javier Coy-Vergara
- Department of Molecular Biology, University of Göttingen Medical Centre, Humboldtallee 23, 37073, Göttingen, Germany
| | - Sara Francesca Colombo
- Institute of Neuroscience and BIOMETRA Department, Consiglio Nazionale delle Ricerche and Università degli Studi di Milano, via Vanvitelli 32, 20129, Milan, Italy
| | - Blanche Schwappach
- Department of Molecular Biology, University of Göttingen Medical Centre, Humboldtallee 23, 37073, Göttingen, Germany.
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28
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Lakshminarayan R, Phillips BP, Binnian IL, Gomez-Navarro N, Escudero-Urquijo N, Warren AJ, Miller EA. Pre-emptive Quality Control of a Misfolded Membrane Protein by Ribosome-Driven Effects. Curr Biol 2020; 30:854-864.e5. [PMID: 31956032 PMCID: PMC7063571 DOI: 10.1016/j.cub.2019.12.060] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [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: 07/05/2019] [Revised: 12/02/2019] [Accepted: 12/19/2019] [Indexed: 12/13/2022]
Abstract
Cells possess multiple mechanisms that protect against the accumulation of toxic aggregation-prone proteins. Here, we identify a pre-emptive pathway that reduces synthesis of membrane proteins that have failed to properly assemble in the endoplasmic reticulum (ER). We show that loss of the ER membrane complex (EMC) or mutation of the Sec61 translocon causes reduced synthesis of misfolded forms of the yeast ABC transporter Yor1. Synthesis defects are rescued by various ribosomal mutations, as well as by reducing cellular ribosome abundance. Genetic and biochemical evidence point to a ribosome-associated quality-control pathway triggered by ribosome collisions when membrane domain insertion and/or folding fails. In support of this model, translation initiation also contributes to synthesis defects, likely by modulating ribosome abundance on the message. Examination of translation efficiency across the yeast membrane proteome revealed that polytopic membrane proteins have relatively low ribosome abundance, providing evidence for translational tuning to balance protein synthesis and folding. We propose that by modulating translation rates of poorly folded proteins, cells can pre-emptively protect themselves from potentially toxic aberrant transmembrane proteins. Yor1-ΔF shows synthesis defects when Sec61 or EMC function is compromised Synthesis defects are suppressed by ribosomal and RQC mutants Translation initiation is a second point of potential regulation Pre-emptive quality control on the ER might protect the cell from aberrant proteins
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Affiliation(s)
- Ramya Lakshminarayan
- Department of Biological Sciences, Columbia University, 1212 Amsterdam Ave., New York, NY 10027, USA
| | - Ben P Phillips
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Ave., Cambridge CB2 0QH, UK
| | - Imogen L Binnian
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Ave., Cambridge CB2 0QH, UK
| | - Natalia Gomez-Navarro
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Ave., Cambridge CB2 0QH, UK
| | - Norberto Escudero-Urquijo
- Cambridge Institute for Medical Research, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Haematology, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Puddicomb Way, Cambridge CB2 0AW, UK
| | - Alan J Warren
- Cambridge Institute for Medical Research, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Haematology, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Puddicomb Way, Cambridge CB2 0AW, UK
| | - Elizabeth A Miller
- Department of Biological Sciences, Columbia University, 1212 Amsterdam Ave., New York, NY 10027, USA; Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Ave., Cambridge CB2 0QH, UK.
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29
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Talbot BE, Vandorpe DH, Stotter BR, Alper SL, Schlondorff JS. Transmembrane insertases and N-glycosylation critically determine synthesis, trafficking, and activity of the nonselective cation channel TRPC6. J Biol Chem 2019; 294:12655-12669. [PMID: 31266804 PMCID: PMC6709635 DOI: 10.1074/jbc.ra119.008299] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [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: 03/04/2019] [Revised: 06/28/2019] [Indexed: 12/12/2022] Open
Abstract
Transient receptor potential cation channel subfamily C member 6 (TRPC6) is a widely expressed ion channel. Gain-of-function mutations in the human TRPC6 channel cause autosomal-dominant focal segmental glomerulosclerosis, but the molecular components involved in disease development remain unclear. Here, we found that overexpression of gain-of-function TRPC6 channel variants is cytotoxic in cultured cells. Exploiting this phenotype in a genome-wide CRISPR/Cas screen for genes whose inactivation rescues cells from TRPC6-associated cytotoxicity, we identified several proteins essential for TRPC6 protein expression, including the endoplasmic reticulum (ER) membrane protein complex transmembrane insertase. We also identified transmembrane protein 208 (TMEM208), a putative component of a signal recognition particle-independent (SND) ER protein-targeting pathway, as being necessary for expression of TRPC6 and several other ion channels and transporters. TRPC6 expression was also diminished by loss of the previously uncharacterized WD repeat domain 83 opposite strand (WDR83OS), which interacted with both TRPC6 and TMEM208. Additionally enriched among the screen hits were genes involved in N-linked protein glycosylation. Deletion of the mannosyl (α-1,3-)-glycoprotein β-1,2-N-acetylglucosaminyltransferase (MGAT1), necessary for the generation of complex N-linked glycans, abrogated TRPC6 gain-of-function variant-mediated Ca2+ influx and extracellular signal-regulated kinase activation in HEK cells, but failed to diminish cytotoxicity in cultured podocytes. However, mutating the two TRPC6 N-glycosylation sites abrogated the cytotoxicity of mutant TRPC6 and reduced its surface expression. These results expand the targets of TMEM208-mediated ER translocation to include multipass transmembrane proteins and suggest that TRPC6 N-glycosylation plays multiple roles in modulating channel trafficking and activity.
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Affiliation(s)
- Brianna E Talbot
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - David H Vandorpe
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Brian R Stotter
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
- Division of Nephrology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Seth L Alper
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Johannes S Schlondorff
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
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30
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Barrows NJ, Anglero-Rodriguez Y, Kim B, Jamison SF, Le Sommer C, McGee CE, Pearson JL, Dimopoulos G, Ascano M, Bradrick SS, Garcia-Blanco MA. Dual roles for the ER membrane protein complex in flavivirus infection: viral entry and protein biogenesis. Sci Rep 2019; 9:9711. [PMID: 31273220 PMCID: PMC6609633 DOI: 10.1038/s41598-019-45910-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [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: 01/04/2019] [Accepted: 05/27/2019] [Indexed: 12/16/2022] Open
Abstract
Hundreds of cellular host factors are required to support dengue virus infection, but their identity and roles are incompletely characterized. Here, we identify human host dependency factors required for efficient dengue virus-2 (DENV2) infection of human cells. We focused on two, TTC35 and TMEM111, which we previously demonstrated to be required for yellow fever virus (YFV) infection and others subsequently showed were also required by other flaviviruses. These proteins are components of the human endoplasmic reticulum membrane protein complex (EMC), which has roles in ER-associated protein biogenesis and lipid metabolism. We report that DENV, YFV and Zika virus (ZIKV) infections were strikingly inhibited, while West Nile virus infection was unchanged, in cells that lack EMC subunit 4. Furthermore, targeted depletion of EMC subunits in live mosquitoes significantly reduced DENV2 propagation in vivo. Using a novel uncoating assay, which measures interactions between host RNA-binding proteins and incoming viral RNA, we show that EMC is required at or prior to virus uncoating. Importantly, we uncovered a second and important role for the EMC. The complex is required for viral protein accumulation in a cell line harboring a ZIKV replicon, indicating that EMC participates in the complex process of viral protein biogenesis.
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Affiliation(s)
- Nicholas J Barrows
- Department of Microbiology and Molecular Genetics, and Center for RNA Biology, Duke University, Durham, USA.,Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, USA
| | - Yesseinia Anglero-Rodriguez
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, USA
| | - Byungil Kim
- Department of Biochemistry, Vanderbilt University, Nashville, USA
| | - Sharon F Jamison
- Department of Microbiology and Molecular Genetics, and Center for RNA Biology, Duke University, Durham, USA
| | - Caroline Le Sommer
- Department of Microbiology and Molecular Genetics, and Center for RNA Biology, Duke University, Durham, USA
| | | | - James L Pearson
- Department of Microbiology and Molecular Genetics, and Center for RNA Biology, Duke University, Durham, USA
| | - George Dimopoulos
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, USA
| | - Manuel Ascano
- Department of Biochemistry, Vanderbilt University, Nashville, USA
| | - Shelton S Bradrick
- Department of Microbiology and Molecular Genetics, and Center for RNA Biology, Duke University, Durham, USA. .,Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, USA.
| | - Mariano A Garcia-Blanco
- Department of Microbiology and Molecular Genetics, and Center for RNA Biology, Duke University, Durham, USA. .,Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, USA. .,Programme of Emerging Infectious Diseases, Duke-NUS Medical School, Singapore, Singapore.
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31
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Li R, Wang X, Zhang X, Yu J, Feng J, Lv P, Lou Y, Chen Y. Ad5-EMC6 mediates antitumor activity in gastric cancer cells through the mitochondrial apoptosis pathway. Biochem Biophys Res Commun 2019; 513:663-668. [PMID: 30982575 DOI: 10.1016/j.bbrc.2019.04.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [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: 03/21/2019] [Accepted: 04/03/2019] [Indexed: 12/30/2022]
Abstract
Endoplasmic reticulum membrane protein complex subunit 6 (EMC6), also known as transmembrane protein 93 (transmembrane protein 93, TMEM93), is an autophagy-related protein. EMC6 overexpression inhibits cancer cell growth and induces apoptosis, but the interaction partners of EMC6 and its cellular responsibilities remain incompletely understood. In this study, we report that adenovirus-mediated ectopic overexpression of EMC6 (Ad5-EMC6) in BGC823 and SGC7901 gastric cancer cells decreases the activity of ERK1/2, down-regulates the levels of BCL-2 protein and phosphorylated BCL-2, increases the expression of tBID and BAX, and decreases mitochondrial membrane potential and subsequently leading to cell apoptosis. In a xenograft tumor model, we found that Ad5-EMC6 impairs the tumorigenesis of SGC7901 gastric cancer cells in nude mice. Additionally, Ad5-EMC6 enhances the sensitivity of gastric cancer cells to the chemotherapeutic drug etoposide. Collectively, these results demonstrate that EMC6-induced apoptosis of gastric cancer cells occurs at least partially through the mitochondrial-mediated apoptosis pathway. Our study suggests a rational basis for the potential clinical application of Ad5-EMC6 in gastric cancer.
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Affiliation(s)
- Riyong Li
- Department of Immunology, Peking University School of Basic Medical Sciences, NHC Key Laboratory of Medical Immunology, Peking University, Beijing, 100191, China
| | - Xiaokun Wang
- Functional Testing of Fuwai Hospital, Chinese Academy of Medical Sciences, Beijing, 100037, China
| | - Xuan Zhang
- Department of Immunology, Peking University School of Basic Medical Sciences, NHC Key Laboratory of Medical Immunology, Peking University, Beijing, 100191, China
| | - Jiahong Yu
- Department of Immunology, Peking University School of Basic Medical Sciences, NHC Key Laboratory of Medical Immunology, Peking University, Beijing, 100191, China
| | - Jinqiu Feng
- Department of Immunology, Peking University School of Basic Medical Sciences, NHC Key Laboratory of Medical Immunology, Peking University, Beijing, 100191, China
| | - Ping Lv
- Department of Immunology, Peking University School of Basic Medical Sciences, NHC Key Laboratory of Medical Immunology, Peking University, Beijing, 100191, China
| | - Yaxin Lou
- Medical and Healthy Analytical Center, Peking University, Beijing, 100191, China.
| | - Yingyu Chen
- Department of Immunology, Peking University School of Basic Medical Sciences, NHC Key Laboratory of Medical Immunology, Peking University, Beijing, 100191, China.
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32
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Chitwood PJ, Hegde RS. The Role of EMC during Membrane Protein Biogenesis. Trends Cell Biol 2019; 29:371-384. [PMID: 30826214 DOI: 10.1016/j.tcb.2019.01.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [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: 01/03/2019] [Revised: 01/27/2019] [Accepted: 01/28/2019] [Indexed: 12/11/2022]
Abstract
Ten years ago, high-throughput genetic interaction analyses revealed an abundant and widely conserved protein complex residing in the endoplasmic reticulum (ER) membrane. Dubbed the ER membrane protein complex (EMC), its disruption has since been found to affect wide-ranging processes, including protein trafficking, organelle communication, ER stress, viral maturation, lipid homeostasis, and others. However, its molecular function has remained enigmatic. Recent studies suggest a role for EMC during membrane protein biogenesis. Biochemical reconstitution experiments show that EMC can directly mediate the insertion of transmembrane domains (TMDs) into the lipid bilayer. Given the large proportion of genes encoding membrane proteins, a central role for EMC as a TMD insertion factor can explain its high abundance, wide conservation, and pleiotropic phenotypes.
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Affiliation(s)
- Patrick J Chitwood
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB20QH, UK
| | - Ramanujan S Hegde
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB20QH, UK.
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33
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Coelho JPL, Stahl M, Bloemeke N, Meighen-Berger K, Alvira CP, Zhang ZR, Sieber SA, Feige MJ. A network of chaperones prevents and detects failures in membrane protein lipid bilayer integration. Nat Commun 2019; 10:672. [PMID: 30737405 PMCID: PMC6368539 DOI: 10.1038/s41467-019-08632-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [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: 10/25/2018] [Accepted: 01/22/2019] [Indexed: 12/20/2022] Open
Abstract
A fundamental step in membrane protein biogenesis is their integration into the lipid bilayer with a defined orientation of each transmembrane segment. Despite this, it remains unclear how cells detect and handle failures in this process. Here we show that single point mutations in the membrane protein connexin 32 (Cx32), which cause Charcot-Marie-Tooth disease, can cause failures in membrane integration. This leads to Cx32 transport defects and rapid degradation. Our data show that multiple chaperones detect and remedy this aberrant behavior: the ER-membrane complex (EMC) aids in membrane integration of low-hydrophobicity transmembrane segments. If they fail to integrate, these are recognized by the ER-lumenal chaperone BiP. Ultimately, the E3 ligase gp78 ubiquitinates Cx32 proteins, targeting them for degradation. Thus, cells use a coordinated system of chaperones for the complex task of membrane protein biogenesis, which can be compromised by single point mutations, causing human disease.
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Affiliation(s)
- João P L Coelho
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Matthias Stahl
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
- SciLifeLab, Department of Oncology-Pathology, Karolinska Institutet, Box 1031, 171 21 Solna, Stockholm, Sweden
| | - Nicolas Bloemeke
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Kevin Meighen-Berger
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Carlos Piedrafita Alvira
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Zai-Rong Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 201210, China
| | - Stephan A Sieber
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Matthias J Feige
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany.
- Institute for Advanced Study, Technical University of Munich, Lichtenbergstr. 2a, 85748, Garching, Germany.
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34
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Carlin AF, Shresta S. Genome-wide approaches to unravelling host-virus interactions in Dengue and Zika infections. Curr Opin Virol 2019; 34:29-38. [PMID: 30576956 PMCID: PMC6476700 DOI: 10.1016/j.coviro.2018.11.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/08/2018] [Accepted: 11/30/2018] [Indexed: 12/16/2022]
Abstract
Genomics approaches are increasingly utilized to probe host-viral interactions and identify mechanisms of viral pathogenesis and host-subversion. Here we review recent studies that utilize Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9 screens, transcriptomics and epigenomics to gain insight into Dengue and Zika virus infections in humans. We discuss the benefits and limitations of recently utilized techniques that separate virally infected cells from neighboring uninfected cells to identify the mechanisms by which these viruses regulate host responses. We conclude by discussing how these approaches can best advance our understanding of Dengue and Zika virus pathogenesis in humans.
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Affiliation(s)
- Aaron F Carlin
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States.
| | - Sujan Shresta
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States; Division of Inflammation Biology, La Jolla Institute for Immunology, La Jolla, CA, United States.
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35
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Volkmar N, Thezenas ML, Louie SM, Juszkiewicz S, Nomura DK, Hegde RS, Kessler BM, Christianson JC. The ER membrane protein complex promotes biogenesis of sterol-related enzymes maintaining cholesterol homeostasis. J Cell Sci 2019; 132:jcs.223453. [PMID: 30578317 PMCID: PMC6362398 DOI: 10.1242/jcs.223453] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [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: 08/07/2018] [Accepted: 12/03/2018] [Indexed: 12/24/2022] Open
Abstract
The eukaryotic endoplasmic reticulum (ER) membrane contains essential complexes that oversee protein biogenesis and lipid metabolism, impacting nearly all aspects of cell physiology. The ER membrane protein complex (EMC) is a newly described transmembrane domain (TMD) insertase linked with various phenotypes, but whose clients and cellular responsibilities remain incompletely understood. We report that EMC deficiency limits the cellular boundaries defining cholesterol tolerance, reflected by diminished viability with limiting or excessive extracellular cholesterol. Lipidomic and proteomic analyses revealed defective biogenesis and concomitant loss of the TMD-containing ER-resident enzymes sterol-O-acyltransferase 1 (SOAT1) and squalene synthase (SQS, also known as FDFT1), which serve strategic roles in the adaptation of cells to changes in cholesterol availability. Insertion of the weakly hydrophobic tail-anchor (TA) of SQS into the ER membrane by the EMC ensures sufficient flux through the sterol biosynthetic pathway while biogenesis of polytopic SOAT1 promoted by the EMC provides cells with the ability to store free cholesterol as inert cholesteryl esters. By facilitating insertion of TMDs that permit essential mammalian sterol-regulating enzymes to mature accurately, the EMC is an important biogenic determinant of cellular robustness to fluctuations in cholesterol availability. This article has an associated First Person interview with the first author of the paper. Highlighted Article: The ER membrane protein complex promotes biogenesis of key membrane-bound enzymes responsible for regulation of cholesterol biosynthesis and storage, an important determinant of mammalian cell viability.
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Affiliation(s)
- Norbert Volkmar
- Ludwig Institute for Cancer Research, University of Oxford, ORCRB, Headington, Oxford, OX3 7DQ, UK
| | - Maria-Laetitia Thezenas
- Target Discovery Institute (TDI) Mass Spectrometry Laboratory, Nuffield Department of Medicine, University of Oxford, Headington, Oxford, OX3 7DQ, UK
| | - Sharon M Louie
- Dept. of Chemistry, Molecular and Cell Biology, and Nutritional Sciences and Toxicology, University of California-Berkeley, Berkeley, CA, 94720, USA
| | - Szymon Juszkiewicz
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Daniel K Nomura
- Dept. of Chemistry, Molecular and Cell Biology, and Nutritional Sciences and Toxicology, University of California-Berkeley, Berkeley, CA, 94720, USA
| | - Ramanujan S Hegde
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Benedikt M Kessler
- Target Discovery Institute (TDI) Mass Spectrometry Laboratory, Nuffield Department of Medicine, University of Oxford, Headington, Oxford, OX3 7DQ, UK
| | - John C Christianson
- Ludwig Institute for Cancer Research, University of Oxford, ORCRB, Headington, Oxford, OX3 7DQ, UK .,Oxford Centre for Translational Myeloma Research, NDORMS, University of Oxford, Botnar Research Centre, Headington, Oxford, OX3 7LD, UK
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Chitwood PJ, Juszkiewicz S, Guna A, Shao S, Hegde RS. EMC Is Required to Initiate Accurate Membrane Protein Topogenesis. Cell 2018; 175:1507-1519.e16. [PMID: 30415835 DOI: 10.1016/j.cell.2018.10.009] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 08/15/2018] [Accepted: 10/01/2018] [Indexed: 12/21/2022]
Abstract
Mammals encode ∼5,000 integral membrane proteins that need to be inserted in a defined topology at the endoplasmic reticulum (ER) membrane by mechanisms that are incompletely understood. Here, we found that efficient biogenesis of β1-adrenergic receptor (β1AR) and other G protein-coupled receptors (GPCRs) requires the conserved ER membrane protein complex (EMC). Reconstitution studies of β1AR biogenesis narrowed the EMC requirement to the co-translational insertion of the first transmembrane domain (TMD). Without EMC, a proportion of TMD1 inserted in an inverted orientation or failed altogether. Purified EMC and SRP receptor were sufficient for correctly oriented TMD1 insertion, while the Sec61 translocon was necessary for insertion of the next TMD. Enforcing TMD1 topology with an N-terminal signal peptide bypassed the EMC requirement for insertion in vitro and restored efficient biogenesis of multiple GPCRs in EMC-knockout cells. Thus, EMC inserts TMDs co-translationally and cooperates with the Sec61 translocon to ensure accurate topogenesis of many membrane proteins. Efficient biogenesis of many GPCRs requires EMC, the ER membrane protein complex Without EMC, correct topology and insertion of the first transmembrane domain fails Purified EMC is sufficient for insertion of the first transmembrane domain of GPCRs The Sec61 complex is required for insertion of subsequent transmembrane domains
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37
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D'Alessandro M, Richard M, Stigloher C, Gache V, Boulin T, Richmond JE, Bessereau JL. CRELD1 is an evolutionarily-conserved maturational enhancer of ionotropic acetylcholine receptors. eLife 2018; 7:39649. [PMID: 30407909 PMCID: PMC6245729 DOI: 10.7554/elife.39649] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [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: 07/12/2018] [Accepted: 11/05/2018] [Indexed: 12/22/2022] Open
Abstract
The assembly of neurotransmitter receptors in the endoplasmic reticulum limits the number of receptors delivered to the plasma membrane, ultimately controlling neurotransmitter sensitivity and synaptic transfer function. In a forward genetic screen conducted in the nematode C. elegans, we identified crld-1 as a gene required for the synaptic expression of ionotropic acetylcholine receptors (AChR). We demonstrated that the CRLD-1A isoform is a membrane-associated ER-resident protein disulfide isomerase (PDI). It physically interacts with AChRs and promotes the assembly of AChR subunits in the ER. Mutations of Creld1, the human ortholog of crld-1a, are responsible for developmental cardiac defects. We showed that Creld1 knockdown in mouse muscle cells decreased surface expression of AChRs and that expression of mouse Creld1 in C. elegans rescued crld-1a mutant phenotypes. Altogether these results identify a novel and evolutionarily-conserved maturational enhancer of AChR biogenesis, which controls the abundance of functional receptors at the cell surface.
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Affiliation(s)
- Manuela D'Alessandro
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Magali Richard
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Christian Stigloher
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Vincent Gache
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Thomas Boulin
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, United States
| | - Jean-Louis Bessereau
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
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38
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Kudze T, Mendez-Dorantes C, Jalloh CS, McClellan AJ. Evidence for interaction between Hsp90 and the ER membrane complex. Cell Stress Chaperones 2018; 23:1101-1115. [PMID: 29808299 PMCID: PMC6111080 DOI: 10.1007/s12192-018-0908-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 04/24/2018] [Accepted: 05/27/2018] [Indexed: 01/04/2023] Open
Abstract
Numerous putative heat shock protein 90 (Hsp90)-interacting proteins, which could represent novel folding clients or co-chaperones, have been identified in recent years. Two separate high-throughput screens in yeast uncovered genetic effects between Hsp90 and components of the ER membrane complex (EMC), which is required for tolerance to unfolded protein response stress in yeast. Herein, we provide the first experimental evidence supporting that there is a genuine interaction of Hsp90 with the EMC. We demonstrate genetic interactions between EMC2 and the known Hsp90 co-chaperone encoded by STI1, as well as Hsp90 point mutant allele-specific differences in inherent growth and Hsp90 inhibitor tolerance in the absence and presence of EMC2. In co-precipitation experiments, Hsp90 interacts with Emc2p, whether or not Emc2p contains amino acid sequences designated as a tetratricopeptide repeat motif. Yeast with multiple EMC gene deletions exhibit increased sensitivity to Hsp90 inhibitor as well as defective folding of the well-established Hsp90 folding client, the glucocorticoid receptor. Altogether, our evidence of physical, genetic, and functional interaction of Hsp90 with the EMC, as well as bioinformatic analysis of shared interactors, supports that there is a legitimate interaction between them in vivo.
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Affiliation(s)
- Tambudzai Kudze
- Division of Science and Mathematics, Bennington College, Bennington, VT, USA
| | | | | | - Amie J McClellan
- Division of Science and Mathematics, Bennington College, Bennington, VT, USA.
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39
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Odeh HM, Coyaud E, Raught B, Matunis MJ. The SUMO-specific isopeptidase SENP2 is targeted to intracellular membranes via a predicted N-terminal amphipathic α-helix. Mol Biol Cell 2018; 29:1878-1890. [PMID: 29874116 PMCID: PMC6085828 DOI: 10.1091/mbc.e17-07-0445] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [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] [Indexed: 11/11/2022] Open
Abstract
Sumoylation regulates a wide range of essential cellular functions, many of which are associated with activities in the nucleus. Although there is also emerging evidence for the involvement of the small ubiquitin-related modifier (SUMO) at intracellular membranes, the mechanisms by which sumoylation is regulated at membranes is largely unexplored. In this study, we report that the SUMO-specific isopeptidase, SENP2, uniquely associates with intracellular membranes. Using in vivo analyses and in vitro binding assays, we show that SENP2 is targeted to intracellular membranes via a predicted N-terminal amphipathic α-helix that promotes direct membrane binding. Furthermore, we demonstrate that SENP2 binding to intracellular membranes is regulated by interactions with the nuclear import receptor karyopherin-α. Consistent with membrane association, biotin identification (BioID) revealed interactions between SENP2 and endoplasmic reticulum, Golgi, and inner nuclear membrane-associated proteins. Collectively, our findings indicate that SENP2 binds to intracellular membranes where it interacts with membrane-associated proteins and has the potential to regulate their sumoylation and membrane-associated functions.
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Affiliation(s)
- Hana M Odeh
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205
| | - Etienne Coyaud
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 2C4, Canada
| | - Brian Raught
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 2C4, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Michael J Matunis
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205
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40
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Kramer NJ, Haney MS, Morgens DW, Jovičić A, Couthouis J, Li A, Ousey J, Ma R, Bieri G, Tsui CK, Shi Y, Hertz NT, Tessier-Lavigne M, Ichida JK, Bassik MC, Gitler AD. CRISPR-Cas9 screens in human cells and primary neurons identify modifiers of C9ORF72 dipeptide-repeat-protein toxicity. Nat Genet 2018; 50:603-612. [PMID: 29507424 PMCID: PMC5893388 DOI: 10.1038/s41588-018-0070-7] [Citation(s) in RCA: 148] [Impact Index Per Article: 24.7] [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: 05/03/2017] [Accepted: 01/24/2018] [Indexed: 12/13/2022]
Abstract
Hexanucleotide repeat expansions in the C9orf72 gene are the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia (c9FTD/ALS). The nucleotide repeat expansions are translated into dipeptide repeat (DPR) proteins, which are aggregation-prone and may contribute to neurodegeneration. We used the CRISPR-Cas9 system to perform genome-wide gene knockout screens for suppressors and enhancers of C9orf72 DPR toxicity in human cells. We validated hits by performing secondary CRISPR-Cas9 screens in primary mouse neurons. We uncovered potent modifiers of DPR toxicity whose gene products function in nucleocytoplasmic transport, the endoplasmic reticulum (ER), proteasome, RNA processing pathways, and in chromatin modification. One modifier, TMX2, modulated the ER-stress signature elicited by C9orf72 DPRs in neurons, and improved survival of human induced motor neurons from C9orf72 ALS patients. Together, this work demonstrates the promise of CRISPR-Cas9 screens to define mechanisms of neurodegenerative diseases.
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Affiliation(s)
- Nicholas J Kramer
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA.,Neurosciences Graduate Program, Stanford University School of Medicine, Stanford, CA, USA
| | - Michael S Haney
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - David W Morgens
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Ana Jovičić
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA.,Department of Molecular Biology, Genentech, South San Francisco, CA, USA
| | - Julien Couthouis
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Amy Li
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - James Ousey
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Rosanna Ma
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Gregor Bieri
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA.,Neurosciences Graduate Program, Stanford University School of Medicine, Stanford, CA, USA
| | - C Kimberly Tsui
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Yingxiao Shi
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | | | | | - Justin K Ichida
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | - Michael C Bassik
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA.
| | - Aaron D Gitler
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA.
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42
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Petko J, Tranchina T, Patel G, Levenson R, Justice-Bitner S. Identifying novel members of the Wntless interactome through genetic and candidate gene approaches. Brain Res Bull 2018; 138:96-105. [PMID: 28734904 DOI: 10.1016/j.brainresbull.2017.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/26/2017] [Accepted: 07/06/2017] [Indexed: 02/07/2023]
Abstract
Wnt signaling is an important pathway that regulates several aspects of embryogenesis, stem cell maintenance, and neural connectivity. We have recently determined that opioids decrease Wnt secretion, presumably by inhibiting the recycling of the Wnt trafficking protein Wntless (Wls). This effect appears to be mediated by protein-protein interaction between Wls and the mu-opioid receptor (MOR), the primary cellular target of opioid drugs. The goal of this study was to identify novel protein interactors of Wls that are expressed in the brain and may also play a role in reward or addiction. Using genetic and candidate gene approaches, we show that among a variety of protein, Wls interacts with the dopamine transporter (target of cocaine), cannabinoid receptors (target of THC), Adenosine A2A receptor (target of caffeine), and SGIP1 (endocytic regulator of cannabinoid receptors). Our study shows that aside from opioid receptors, Wntless interacts with additional proteins involved in reward and/or addiction. Future studies will determine whether Wntless and WNT signaling play a more universal role in these processes.
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Eisenberg-Bord M, Schuldiner M. Mitochatting - If only we could be a fly on the cell wall. Biochim Biophys Acta Mol Cell Res 2017; 1864:1469-1480. [PMID: 28433686 DOI: 10.1016/j.bbamcr.2017.04.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 04/12/2017] [Accepted: 04/18/2017] [Indexed: 12/24/2022]
Abstract
Mitochondria, cellular metabolic hubs, perform many essential processes and are required for the production of metabolites such as ATP, iron-sulfur clusters, heme, amino acids and nucleotides. To fulfill their multiple roles, mitochondria must communicate with all other organelles to exchange small molecules, ions and lipids. Since mitochondria are largely excluded from vesicular trafficking routes, they heavily rely on membrane contact sites. Contact sites are areas of close proximity between organelles that allow efficient transfer of molecules, saving the need for slow and untargeted diffusion through the cytosol. More globally, multiple metabolic pathways require coordination between mitochondria and additional organelles and mitochondrial activity affects all other cellular entities and vice versa. Therefore, uncovering the different means of mitochondrial communication will allow us a better understanding of mitochondria and may illuminate disease processes that occur in the absence of proper cross-talk. In this review we focus on how mitochondria interact with all other organelles and emphasize how this communication is essential for mitochondrial and cellular homeostasis. This article is part of a Special Issue entitled: Membrane Contact Sites edited by Christian Ungermann and Benoit Kornmann.
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Affiliation(s)
- Michal Eisenberg-Bord
- Department of Molecular Genetics, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, 7610001 Rehovot, Israel.
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Abstract
Viruses are obligate intracellular pathogens that depend on host cellular components for replication. Genetic screens are an unbiased and comprehensive method to uncover host cellular components that are critical for the infection with viruses. Loss-of-function screens result in the genome-wide disruption of gene expression, whereas gain-of-function screens rely on large-scale overexpression of host genes. Genetic knockout screens can be conducted using haploid insertional mutagenesis or the CRISPR–Cas system. Genetic screens using the CRISPR–Cas system have provided crucial insights in the host determinants of infections with important human pathogens such as dengue virus, West Nile virus, Zika virus and hepatitis C virus. CRISPR–Cas-based techniques additionally provide ways to generate both in vitro and in vivo models to study viral pathogenesis, to manipulate viral genomes, to eradicate viral disease vectors using gene drive systems and to advance the development of antiviral therapeutics.
In this Review, Puschnik and colleagues discuss the technical aspects of using CRISPR–Cas technology in genome-scale knockout screens to study virus–host interactions, and they compare these screens with alternative genetic screening technologies. Viruses depend on their hosts to complete their replication cycles; they exploit cellular receptors for entry and hijack cellular functions to replicate their genome, assemble progeny virions and spread. Recently, genome-scale CRISPR–Cas screens have been used to identify host factors that are required for virus replication, including the replication of clinically relevant viruses such as Zika virus, West Nile virus, dengue virus and hepatitis C virus. In this Review, we discuss the technical aspects of genome-scale knockout screens using CRISPR–Cas technology, and we compare these screens with alternative genetic screening technologies. The relative ease of use and reproducibility of CRISPR–Cas make it a powerful tool for probing virus–host interactions and for identifying new antiviral targets.
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Affiliation(s)
- Andreas S Puschnik
- Department of Microbiology and Immunology, Stanford University, Stanford, California 94305, USA
| | - Karim Majzoub
- Department of Microbiology and Immunology, Stanford University, Stanford, California 94305, USA
| | - Yaw Shin Ooi
- Department of Microbiology and Immunology, Stanford University, Stanford, California 94305, USA
| | - Jan E Carette
- Department of Microbiology and Immunology, Stanford University, Stanford, California 94305, USA
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Voleman L, Najdrová V, Ástvaldsson Á, Tůmová P, Einarsson E, Švindrych Z, Hagen GM, Tachezy J, Svärd SG, Doležal P. Giardia intestinalis mitosomes undergo synchronized fission but not fusion and are constitutively associated with the endoplasmic reticulum. BMC Biol 2017; 15:27. [PMID: 28372543 DOI: 10.1186/s12915-017-0361-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 03/01/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mitochondria of opisthokonts undergo permanent fission and fusion throughout the cell cycle. Here, we investigated the dynamics of the mitosomes, the simplest forms of mitochondria, in the anaerobic protist parasite Giardia intestinalis, a member of the Excavata supergroup of eukaryotes. The mitosomes have abandoned typical mitochondrial traits such as the mitochondrial genome and aerobic respiration and their single role known to date is the formation of iron-sulfur clusters. RESULTS In live experiments, no fusion events were observed between the mitosomes in G. intestinalis. Moreover, the organelles were highly prone to becoming heterogeneous. This suggests that fusion is either much less frequent or even absent in mitosome dynamics. Unlike in mitochondria, division of the mitosomes was absolutely synchronized and limited to mitosis. The association of the nuclear and the mitosomal division persisted during the encystation of the parasite. During the segregation of the divided mitosomes, the subset of the organelles between two G. intestinalis nuclei had a prominent role. Surprisingly, the sole dynamin-related protein of the parasite seemed not to be involved in mitosomal division. However, throughout the cell cycle, mitosomes associated with the endoplasmic reticulum (ER), although none of the known ER-tethering complexes was present. Instead, the ER-mitosome interface was occupied by the lipid metabolism enzyme long-chain acyl-CoA synthetase 4. CONCLUSIONS This study provides the first report on the dynamics of mitosomes. We show that together with the loss of metabolic complexity of mitochondria, mitosomes of G. intestinalis have uniquely streamlined their dynamics by harmonizing their division with mitosis. We propose that this might be a strategy of G. intestinalis to maintain a stable number of organelles during cell propagation. The lack of mitosomal fusion may also be related to the secondary reduction of the organelles. However, as there are currently no reports on mitochondrial fusion in the whole Excavata supergroup, it is possible that the absence of mitochondrial fusion is an ancestral trait common to all excavates.
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Abstract
The past decade has seen dramatic progress in our understanding of membrane contact sites (MCS). Important examples of these are endoplasmic reticulum (ER)-mitochondria contact sites. ER-mitochondria contacts have originally been discovered in mammalian tissue, where they have been designated as mitochondria-associated membranes (MAMs). It is also in this model system, where the first critical MAM proteins have been identified, including MAM tethering regulators such as phospho-furin acidic cluster sorting protein 2 (PACS-2) and mitofusin-2. However, the past decade has seen the discovery of the MAM also in the powerful yeast model system Saccharomyces cerevisiae. This has led to the discovery of novel MAM tethers such as the yeast ER-mitochondria encounter structure (ERMES), absent in the mammalian system, but whose regulators Gem1 and Lam6 are conserved. While MAMs, sometimes referred to as mitochondria-ER contacts (MERCs), regulate lipid metabolism, Ca2+ signaling, bioenergetics, inflammation, autophagy and apoptosis, not all of these functions exist in both systems or operate differently. This biological difference has led to puzzling discrepancies on findings obtained in yeast or mammalian cells at the moment. Our review aims to shed some light onto mechanistic differences between yeast and mammalian MAM and their underlying causes. Reviewers: This article was reviewed by Paola Pizzo (nominated by Luca Pellegrini), Maya Schuldiner and György Szabadkai (nominated by Luca Pellegrini).
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Affiliation(s)
- Maria Sol Herrera-Cruz
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G2H7, Canada
| | - Thomas Simmen
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G2H7, Canada.
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Filadi R, Theurey P, Pizzo P. The endoplasmic reticulum-mitochondria coupling in health and disease: Molecules, functions and significance. Cell Calcium 2017; 62:1-15. [PMID: 28108029 DOI: 10.1016/j.ceca.2017.01.003] [Citation(s) in RCA: 154] [Impact Index Per Article: 22.0] [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: 12/05/2016] [Revised: 01/09/2017] [Accepted: 01/09/2017] [Indexed: 12/14/2022]
Abstract
The close apposition between endoplasmic reticulum (ER) and mitochondria represents a key platform, capable to regulate different fundamental cellular pathways. Among these, Ca2+ signaling and lipid homeostasis have been demonstrated over the last years to be deeply modulated by ER-mitochondria cross-talk. Given its importance in cell life/death decisions, increasing evidence suggests that alterations of the ER-mitochondria axis could be responsible for the onset and progression of several diseases, including neurodegeneration, cancer and obesity. However, the molecular identity of the proteins controlling this inter-organelle apposition is still debated. In this review, we summarize the main cellular pathways controlled by ER-mitochondria appositions, focusing on the principal molecules reported to be involved in this interplay and on those diseases for which alterations in organelles communication have been reported.
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Affiliation(s)
- Riccardo Filadi
- Department of Biomedical Sciences, University of Padova, Italy
| | - Pierre Theurey
- Department of Biomedical Sciences, University of Padova, Italy
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padova, Italy; Neuroscience Institute, National Research Council (CNR), Padova, Italy.
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Fernández-Murray JP, McMaster CR. Lipid synthesis and membrane contact sites: a crossroads for cellular physiology. J Lipid Res 2016; 57:1789-1805. [PMID: 27521373 DOI: 10.1194/jlr.r070920] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [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: 07/19/2016] [Indexed: 12/17/2022] Open
Abstract
Membrane contact sites (MCSs) are regions of close apposition between different organelles that contribute to the functional integration of compartmentalized cellular processes. In recent years, we have gained insight into the molecular architecture of several contact sites, as well as into the regulatory mechanisms that underlie their roles in cell physiology. We provide an overview of two selected topics where lipid metabolism intersects with MCSs and organelle dynamics. First, the role of phosphatidic acid phosphatase, Pah1, the yeast homolog of metazoan lipin, toward the synthesis of triacylglycerol is outlined in connection with the seipin complex, Fld1/Ldb16, and lipid droplet formation. Second, we recapitulate the different contact sites connecting mitochondria and the endomembrane system and emphasize their contribution to phospholipid synthesis and their coordinated regulation. A comprehensive view is emerging where the multiplicity of contact sites connecting different cellular compartments together with lipid transfer proteins functioning at more than one MCS allow for functional redundancy and cross-regulation.
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Pérez-Sancho J, Tilsner J, Samuels AL, Botella MA, Bayer EM, Rosado A. Stitching Organelles: Organization and Function of Specialized Membrane Contact Sites in Plants. Trends Cell Biol 2016; 26:705-717. [PMID: 27318776 DOI: 10.1016/j.tcb.2016.05.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [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: 03/04/2016] [Revised: 05/17/2016] [Accepted: 05/20/2016] [Indexed: 01/05/2023]
Abstract
The coordination of multiple metabolic activities in plants relies on an interorganelle communication network established through membrane contact sites (MCS). The MCS are maintained in transient or durable configurations by tethering structures which keep the two membranes in close proximity, and create chemical microdomains that allow localized and targeted exchange of small molecules and possibly proteins. The past few years have witnessed a dramatic increase in our understanding of the structural and molecular organization of plant interorganelle MCS, and their crucial roles in plant specialized functions including stress responses, cell to cell communication, and lipid transport. In this review we summarize recent advances in understanding the molecular components, structural organization, and functions of different plant-specific MCS architectures.
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Affiliation(s)
- Jessica Pérez-Sancho
- Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Departamento de Biología Molecular y Bioquímica, Universidad de Málaga, 29071 Malaga, Spain; Department of Botany, Faculty of Science, University of British Columbia, Vancouver V6T 1Z4, Canada
| | - Jens Tilsner
- Biomedical Sciences Research Complex, University of St Andrews, BMS Building, North Haugh, St Andrews, Fife KY16 9ST, UK; Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
| | - A Lacey Samuels
- Department of Botany, Faculty of Science, University of British Columbia, Vancouver V6T 1Z4, Canada
| | - Miguel A Botella
- Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Departamento de Biología Molecular y Bioquímica, Universidad de Málaga, 29071 Malaga, Spain
| | - Emmanuelle M Bayer
- Laboratory of Membrane Biogenesis (LBM), Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 5200, University of Bordeaux, 71 Avenue Edouard Bourlaux, 33883 Villenave d'Ornon CEDEX, France
| | - Abel Rosado
- Department of Botany, Faculty of Science, University of British Columbia, Vancouver V6T 1Z4, Canada.
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Abstract
Over the last several years a wealth of transformative human–virus interaction discoveries have been produced using loss-of-function functional genomics. These insights have greatly expanded our understanding of how human pathogenic viruses exploit our cells to replicate. Two technologies have been at the forefront of this genetic revolution, RNA interference (RNAi) and random retroviral insertional mutagenesis using haploid cell lines (haploid cell screening), with the former technology largely predominating. Now the cutting edge gene editing of the CRISPR/Cas9 system has also been harnessed for large-scale functional genomics and is poised to possibly displace these earlier methods. Here we compare and contrast these three screening approaches for elucidating host–virus interactions, outline their key strengths and weaknesses including a comparison of an arrayed multiple orthologous RNAi reagent screen to a pooled CRISPR/Cas9 human rhinovirus 14–human cell interaction screen, and recount some notable insights made possible by each. We conclude with a brief perspective on what might lie ahead for the fast evolving field of human–virus functional genomics.
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