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Laframboise SJ, Deneault LF, Denoncourt A, Downey M, Baetz K. Uncovering the Role of the Yeast Lysine Acetyltransferase NuA4 in the Regulation of Nuclear Shape and Lipid Metabolism. Mol Cell Biol 2024; 44:273-288. [PMID: 38961766 PMCID: PMC11253884 DOI: 10.1080/10985549.2024.2366206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 05/19/2024] [Indexed: 07/05/2024] Open
Abstract
Here, we report a novel role for the yeast lysine acetyltransferase NuA4 in regulating phospholipid availability for organelle morphology. Disruption of the NuA4 complex results in 70% of cells displaying nuclear deformations and nearly 50% of cells exhibiting vacuolar fragmentation. Cells deficient in NuA4 also show severe defects in the formation of nuclear-vacuole junctions (NJV), as well as a decrease in piecemeal microautophagy of the nucleus (PMN). To determine the cause of these defects we focused on Pah1, an enzyme that converts phosphatidic acid into diacylglycerol, favoring accumulation of lipid droplets over phospholipids that are used for membrane expansion. NuA4 subunit Eaf1 was required for Pah1 localization to the inner nuclear membrane and artificially tethering of Pah1 to the nuclear membrane rescued nuclear deformation and vacuole fragmentation defects, but not defects related to the formation of NVJs. Mutation of a NuA4-dependent acetylation site on Pah1 also resulted in aberrant Pah1 localization and defects in nuclear morphology and NVJ. Our work suggests a critical role for NuA4 in organelle morphology that is partially mediated through the regulation of Pah1 subcellular localization.
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Affiliation(s)
- Sarah Jane Laframboise
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
| | - Lauren F. Deneault
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
| | - Alix Denoncourt
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Michael Downey
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Kristin Baetz
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Ottawa Institute of Systems Biology, Ottawa, Ontario, Canada
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, Alberta, Canada
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2
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Kuchitsu Y, Taguchi T. Lysosomal microautophagy: an emerging dimension in mammalian autophagy. Trends Cell Biol 2024; 34:606-616. [PMID: 38104013 DOI: 10.1016/j.tcb.2023.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/08/2023] [Accepted: 11/13/2023] [Indexed: 12/19/2023]
Abstract
Autophagy is a self-catabolic process through which cellular components are delivered to lysosomes for degradation. There are three types of autophagy, i.e., macroautophagy, chaperone-mediated autophagy (CMA), and microautophagy. In macroautophagy, a portion of the cytoplasm is wrapped by the autophagosome, which then fuses with lysosomes and delivers the engulfed cytoplasm for degradation. In CMA, the translocation of cytosolic substrates to the lysosomal lumen is directly across the limiting membrane of lysosomes. In microautophagy, lytic organelles, including endosomes or lysosomes, take up a portion of the cytoplasm directly. Although macroautophagy has been investigated extensively, microautophagy has received much less attention. Nonetheless, it has become evident that microautophagy plays a variety of cellular roles from yeast to mammals. Here we review the very recent updates of microautophagy. In particular, we focus on the feature of the degradative substrates and the molecular machinery that mediates microautophagy.
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Affiliation(s)
- Yoshihiko Kuchitsu
- Laboratory of Organelle Pathophysiology, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
| | - Tomohiko Taguchi
- Laboratory of Organelle Pathophysiology, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
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3
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Prokisch S, Büttner S. Partitioning into ER membrane microdomains impacts autophagic protein turnover during cellular aging. Sci Rep 2024; 14:13653. [PMID: 38871812 DOI: 10.1038/s41598-024-64493-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 06/09/2024] [Indexed: 06/15/2024] Open
Abstract
Eukaryotic membranes are compartmentalized into distinct micro- and nanodomains that rearrange dynamically in response to external and internal cues. This lateral heterogeneity of the lipid bilayer and associated clustering of distinct membrane proteins contribute to the spatial organization of numerous cellular processes. Here, we show that membrane microdomains within the endoplasmic reticulum (ER) of yeast cells are reorganized during metabolic reprogramming and aging. Using biosensors with varying transmembrane domain length to map lipid bilayer thickness, we demonstrate that in young cells, microdomains of increased thickness mainly exist within the nuclear ER, while progressing cellular age drives the formation of numerous microdomains specifically in the cortical ER. Partitioning of biosensors with long transmembrane domains into these microdomains increased protein stability and prevented autophagic removal. In contrast, reporters with short transmembrane domains progressively accumulated at the membrane contact site between the nuclear ER and the vacuole, the so-called nucleus-vacuole junction (NVJ), and were subjected to turnover via selective microautophagy occurring specifically at these sites. Reporters with long transmembrane domains were excluded from the NVJ. Our data reveal age-dependent rearrangement of the lateral organization of the ER and establish transmembrane domain length as a determinant of membrane contact site localization and autophagic degradation.
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Affiliation(s)
- Simon Prokisch
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691, Stockholm, Sweden
| | - Sabrina Büttner
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691, Stockholm, Sweden.
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4
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Domingues N, Pires J, Milosevic I, Raimundo N. Role of lipids in interorganelle communication. Trends Cell Biol 2024:S0962-8924(24)00095-3. [PMID: 38866684 DOI: 10.1016/j.tcb.2024.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 04/26/2024] [Accepted: 04/29/2024] [Indexed: 06/14/2024]
Abstract
Cell homeostasis and function rely on well-orchestrated communication between different organelles. This communication is ensured by signaling pathways and membrane contact sites between organelles. Many players involved in organelle crosstalk have been identified, predominantly proteins and ions. The role of lipids in interorganelle communication remains poorly understood. With the development and broader availability of methods to quantify lipids, as well as improved spatiotemporal resolution in detecting different lipid species, the contribution of lipids to organelle interactions starts to be evident. However, the specific roles of various lipid molecules in intracellular communication remain to be studied systematically. We summarize new insights in the interorganelle communication field from the perspective of organelles and discuss the roles played by lipids in these complex processes.
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Affiliation(s)
- Neuza Domingues
- Multidisciplinary Institute of Ageing, University of Coimbra, Coimbra, Portugal
| | - Joana Pires
- Multidisciplinary Institute of Ageing, University of Coimbra, Coimbra, Portugal
| | - Ira Milosevic
- Multidisciplinary Institute of Ageing, University of Coimbra, Coimbra, Portugal; Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Nuno Raimundo
- Multidisciplinary Institute of Ageing, University of Coimbra, Coimbra, Portugal; Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA; Penn State Cancer Institute, Hershey, PA, USA.
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5
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Zung N, Aravindan N, Boshnakovska A, Valenti R, Preminger N, Jonas F, Yaakov G, Willoughby MM, Homberg B, Keller J, Kupervaser M, Dezorella N, Dadosh T, Wolf SG, Itkin M, Malitsky S, Brandis A, Barkai N, Fernández-Busnadiego R, Reddi AR, Rehling P, Rapaport D, Schuldiner M. The molecular mechanism of on-demand sterol biosynthesis at organelle contact sites. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.09.593285. [PMID: 38766039 PMCID: PMC11100823 DOI: 10.1101/2024.05.09.593285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Contact-sites are specialized zones of proximity between two organelles, essential for organelle communication and coordination. The formation of contacts between the Endoplasmic Reticulum (ER), and other organelles, relies on a unique membrane environment enriched in sterols. However, how these sterol-rich domains are formed and maintained had not been understood. We found that the yeast membrane protein Yet3, the homolog of human BAP31, is localized to multiple ER contact sites. We show that Yet3 interacts with all the enzymes of the post-squalene ergosterol biosynthesis pathway and recruits them to create sterol-rich domains. Increasing sterol levels at ER contacts causes its depletion from the plasma membrane leading to a compensatory reaction and altered cell metabolism. Our data shows that Yet3 provides on-demand sterols at contacts thus shaping organellar structure and function. A molecular understanding of this protein's functions gives new insights into the role of BAP31 in development and pathology.
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Affiliation(s)
- Naama Zung
- Department of Molecular Genetics, Weizmann Institute of Science, Israel
| | - Nitya Aravindan
- Interfaculty Institute of Biochemistry, University of Tuebingen, Germany
| | - Angela Boshnakovska
- Department of Cellular Biochemistry, University Medical Center Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Translational Neuroinflammation and Automated Microscopy, Germany
- Max Planck Institute for Multidisciplinary Sciences, D-37077, Germany
| | - Rosario Valenti
- Department of Molecular Genetics, Weizmann Institute of Science, Israel
| | - Noga Preminger
- Department of Molecular Genetics, Weizmann Institute of Science, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Israel
| | - Gilad Yaakov
- Department of Molecular Genetics, Weizmann Institute of Science, Israel
| | - Mathilda M Willoughby
- School of Chemistry and Biochemistry, Georgia Institute of Technology, USA
- Biochemistry and Molecular Biology Department, University of Nebraska Medical Center, USA
| | - Bettina Homberg
- Department of Cellular Biochemistry, University Medical Center Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Translational Neuroinflammation and Automated Microscopy, Germany
- Max Planck Institute for Multidisciplinary Sciences, D-37077, Germany
| | - Jenny Keller
- University Medical Center Göttingen, Institute for Neuropathology, 37077, Germany
- Collaborative Research Center 1190 "Compartmental Gates and Contact Sites in Cells", University of Göttingen, Germany
| | - Meital Kupervaser
- The De Botton Protein Profiling institute of the Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Israel
| | - Nili Dezorella
- Electron Microscopy Unit, Chemical Research Support, Weizmann Institute of Science, Israel
| | - Tali Dadosh
- Electron Microscopy Unit, Chemical Research Support, Weizmann Institute of Science, Israel
| | - Sharon G Wolf
- Electron Microscopy Unit, Chemical Research Support, Weizmann Institute of Science, Israel
| | - Maxim Itkin
- Life Sciences Core Facilities, Weizmann Institute of Science, Israel
| | - Sergey Malitsky
- Life Sciences Core Facilities, Weizmann Institute of Science, Israel
| | - Alexander Brandis
- Life Sciences Core Facilities, Weizmann Institute of Science, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Israel
| | - Rubén Fernández-Busnadiego
- University Medical Center Göttingen, Institute for Neuropathology, 37077, Germany
- Collaborative Research Center 1190 "Compartmental Gates and Contact Sites in Cells", University of Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37077, Germany
- Faculty of Physics, University of Göttingen, 37077, Germany
| | - Amit R Reddi
- School of Chemistry and Biochemistry, Georgia Institute of Technology, USA
| | - Peter Rehling
- Department of Cellular Biochemistry, University Medical Center Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Translational Neuroinflammation and Automated Microscopy, Germany
- Max Planck Institute for Multidisciplinary Sciences, D-37077, Germany
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tuebingen, Germany
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Israel
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6
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Álvarez-Guerra I, Block E, Broeskamp F, Gabrijelčič S, Infant T, de Ory A, Habernig L, Andréasson C, Levine TP, Höög JL, Büttner S. LDO proteins and Vac8 form a vacuole-lipid droplet contact site to enable starvation-induced lipophagy in yeast. Dev Cell 2024; 59:759-775.e5. [PMID: 38354739 DOI: 10.1016/j.devcel.2024.01.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 11/15/2023] [Accepted: 01/18/2024] [Indexed: 02/16/2024]
Abstract
Lipid droplets (LDs) are fat storage organelles critical for energy and lipid metabolism. Upon nutrient exhaustion, cells consume LDs via gradual lipolysis or via lipophagy, the en bloc uptake of LDs into the vacuole. Here, we show that LDs dock to the vacuolar membrane via a contact site that is required for lipophagy in yeast. The LD-localized LDO proteins carry an intrinsically disordered region that directly binds vacuolar Vac8 to form vCLIP, the vacuolar-LD contact site. Nutrient limitation drives vCLIP formation, and its inactivation blocks lipophagy, resulting in impaired caloric restriction-induced longevity. We establish a functional link between lipophagy and microautophagy of the nucleus, both requiring Vac8 to form respective contact sites upon metabolic stress. In sum, we identify the tethering machinery of vCLIP and find that Vac8 provides a platform for multiple and competing contact sites associated with autophagy.
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Affiliation(s)
- Irene Álvarez-Guerra
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Emma Block
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Filomena Broeskamp
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Sonja Gabrijelčič
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Terence Infant
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Ana de Ory
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Lukas Habernig
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Claes Andréasson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Tim P Levine
- UCL Institute of Ophthalmology, Bath Street, London EC1V 9EL, UK
| | - Johanna L Höög
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Sabrina Büttner
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden.
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7
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Diep DTV, Collado J, Hugenroth M, Fausten RM, Percifull L, Wälte M, Schuberth C, Schmidt O, Fernández-Busnadiego R, Bohnert M. A metabolically controlled contact site between vacuoles and lipid droplets in yeast. Dev Cell 2024; 59:740-758.e10. [PMID: 38367622 DOI: 10.1016/j.devcel.2024.01.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 11/17/2023] [Accepted: 01/18/2024] [Indexed: 02/19/2024]
Abstract
The lipid droplet (LD) organization proteins Ldo16 and Ldo45 affect multiple aspects of LD biology in yeast. They are linked to the LD biogenesis machinery seipin, and their loss causes defects in LD positioning, protein targeting, and breakdown. However, their molecular roles remained enigmatic. Here, we report that Ldo16/45 form a tether complex with Vac8 to create vacuole lipid droplet (vCLIP) contact sites, which can form in the absence of seipin. The phosphatidylinositol transfer protein (PITP) Pdr16 is a further vCLIP-resident recruited specifically by Ldo45. While only an LD subpopulation is engaged in vCLIPs at glucose-replete conditions, nutrient deprivation results in vCLIP expansion, and vCLIP defects impair lipophagy upon prolonged starvation. In summary, Ldo16/45 are multifunctional proteins that control the formation of a metabolically regulated contact site. Our studies suggest a link between LD biogenesis and breakdown and contribute to a deeper understanding of how lipid homeostasis is maintained during metabolic challenges.
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Affiliation(s)
- Duy Trong Vien Diep
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany
| | - Javier Collado
- Institute of Neuropathology, University Medical Center Göttingen, 37099 Göttingen, Germany
| | - Marie Hugenroth
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany
| | - Rebecca Martina Fausten
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany
| | - Louis Percifull
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany
| | - Mike Wälte
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany
| | - Christian Schuberth
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany
| | - Oliver Schmidt
- Institute of Cell Biology, Biocenter Innsbruck, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Rubén Fernández-Busnadiego
- Institute of Neuropathology, University Medical Center Göttingen, 37099 Göttingen, Germany; Cluster of Excellence "Multiscale Imaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany; Faculty of Physics, University of Göttingen, Göttingen 37077, Germany
| | - Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany.
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8
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Ersoy U, Kanakis I, Alameddine M, Pedraza-Vazquez G, Ozanne SE, Peffers MJ, Jackson MJ, Goljanek-Whysall K, Vasilaki A. Lifelong dietary protein restriction accelerates skeletal muscle loss and reduces muscle fibre size by impairing proteostasis and mitochondrial homeostasis. Redox Biol 2024; 69:102980. [PMID: 38064763 PMCID: PMC10755587 DOI: 10.1016/j.redox.2023.102980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/27/2023] [Accepted: 11/27/2023] [Indexed: 01/01/2024] Open
Abstract
The early life environment significantly affects the development of age-related skeletal muscle disorders. However, the long-term effects of lactational protein restriction on skeletal muscle are still poorly defined. Our study revealed that male mice nursed by dams fed a low-protein diet during lactation exhibited skeletal muscle growth restriction. This was associated with a dysregulation in the expression levels of genes related to the ribosome, mitochondria and skeletal muscle development. We reported that lifelong protein restriction accelerated loss of type-IIa muscle fibres and reduced muscle fibre size by impairing mitochondrial homeostasis and proteostasis at 18 months of age. However, feeding a normal-protein diet following lactational protein restriction prevented accelerated fibre loss and fibre size reduction in later life. These findings provide novel insight into the mechanisms by which lactational protein restriction hinders skeletal muscle growth and includes evidence that lifelong dietary protein restriction accelerated skeletal muscle loss in later life.
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Affiliation(s)
- Ufuk Ersoy
- Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical Sciences (ILCaMS), The MRC - Versus Arthritis Centre for Integrated Research Into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK
| | - Ioannis Kanakis
- Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical Sciences (ILCaMS), The MRC - Versus Arthritis Centre for Integrated Research Into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK; Chester Medical School, Faculty of Medicine and Life Sciences, University of Chester, Chester, UK
| | - Moussira Alameddine
- Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical Sciences (ILCaMS), The MRC - Versus Arthritis Centre for Integrated Research Into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK
| | - Gibran Pedraza-Vazquez
- Department of Physiology, School of Medicine and REMEDI, CMNHS, University of Galway, Galway, Ireland
| | - Susan E Ozanne
- MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Treatment Centre, Addenbrooke's Hospital, University of Cambridge Metabolic Research Laboratories, Cambridge, UK
| | - Mandy Jayne Peffers
- Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical Sciences (ILCaMS), The MRC - Versus Arthritis Centre for Integrated Research Into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK
| | - Malcolm J Jackson
- Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical Sciences (ILCaMS), The MRC - Versus Arthritis Centre for Integrated Research Into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK
| | - Katarzyna Goljanek-Whysall
- Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical Sciences (ILCaMS), The MRC - Versus Arthritis Centre for Integrated Research Into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK; Department of Physiology, School of Medicine and REMEDI, CMNHS, University of Galway, Galway, Ireland
| | - Aphrodite Vasilaki
- Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical Sciences (ILCaMS), The MRC - Versus Arthritis Centre for Integrated Research Into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, UK.
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9
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Strawn G, Wong RWK, Young BP, Davey M, Nislow C, Conibear E, Loewen CJR, Mayor T. Genome-wide screen identifies new set of genes for improved heterologous laccase expression in Saccharomyces cerevisiae. Microb Cell Fact 2024; 23:36. [PMID: 38287338 PMCID: PMC10823697 DOI: 10.1186/s12934-024-02298-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 01/04/2024] [Indexed: 01/31/2024] Open
Abstract
The yeast Saccharomyces cerevisiae is widely used as a host cell for recombinant protein production due to its fast growth, cost-effective culturing, and ability to secrete large and complex proteins. However, one major drawback is the relatively low yield of produced proteins compared to other host systems. To address this issue, we developed an overlay assay to screen the yeast knockout collection and identify mutants that enhance recombinant protein production, specifically focusing on the secretion of the Trametes trogii fungal laccase enzyme. Gene ontology analysis of these mutants revealed an enrichment of processes including vacuolar targeting, vesicle trafficking, proteolysis, and glycolipid metabolism. We confirmed that a significant portion of these mutants also showed increased activity of the secreted laccase when grown in liquid culture. Notably, we found that the combination of deletions of OCA6, a tyrosine phosphatase gene, along with PMT1 or PMT2, two genes encoding ER membrane protein-O-mannosyltransferases involved in ER quality control, and SKI3, which encode for a component of the SKI complex responsible for mRNA degradation, further increased secreted laccase activity. Conversely, we also identified over 200 gene deletions that resulted in decreased secreted laccase activity, including many genes that encode for mitochondrial proteins and components of the ER-associated degradation pathway. Intriguingly, the deletion of the ER DNAJ co-chaperone gene SCJ1 led to almost no secreted laccase activity. When we expressed SCJ1 from a low-copy plasmid, laccase secretion was restored. However, overexpression of SCJ1 had a detrimental effect, indicating that precise dosing of key chaperone proteins is crucial for optimal recombinant protein expression. This study offers potential strategies for enhancing the overall yield of recombinant proteins and provides new avenues for further research in optimizing protein production systems.
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Affiliation(s)
- Garrett Strawn
- Department of Biochemistry and Molecular Biology, Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - Ryan W K Wong
- Department of Biochemistry and Molecular Biology, Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - Barry P Young
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Michael Davey
- Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Corey Nislow
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Elizabeth Conibear
- Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Christopher J R Loewen
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Thibault Mayor
- Department of Biochemistry and Molecular Biology, Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.
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10
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Veldsink AC, Gallardo P, Lusk CP, Veenhoff LM. Changing the guard-nuclear pore complex quality control. FEBS Lett 2023; 597:2739-2749. [PMID: 37715940 DOI: 10.1002/1873-3468.14739] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/31/2023] [Accepted: 08/31/2023] [Indexed: 09/18/2023]
Abstract
The integrity of the nuclear envelope depends on the function of nuclear pore complexes (NPCs), transport channels that control macromolecular traffic between the nucleus and cytosol. The central importance of NPCs suggests the existence of quality control (QC) mechanisms that oversee their assembly and function. In this perspective, we emphasize the challenges associated with NPC assembly and the need for QC mechanisms that operate at various stages of an NPC's life. This includes cytosolic preassembly QC that helps enforce key nucleoporin-nucleoporin interactions and their ultimate stoichiometry in the NPC in addition to mechanisms that monitor aberrant fusion of the inner and outer nuclear membranes. Furthermore, we discuss whether and how these QC mechanisms may operate to sense faulty mature NPCs to facilitate their repair or removal. The so far uncovered mechanisms for NPC QC provide fertile ground for future research that not only benefits a better understanding of the vital role that NPCs play in cellular physiology but also how loss of NPC function and/or these QC mechanisms might be an input to aging and disease.
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Affiliation(s)
- Annemiek C Veldsink
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen, 9713 AV, The Netherlands
| | - Paola Gallardo
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen, 9713 AV, The Netherlands
| | - C Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, CT, New Haven, USA
| | - Liesbeth M Veenhoff
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, Groningen, 9713 AV, The Netherlands
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11
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Boyle E, Wilfling F. Autophagy as a caretaker of nuclear integrity. FEBS Lett 2023; 597:2728-2738. [PMID: 37567863 DOI: 10.1002/1873-3468.14719] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/31/2023] [Accepted: 08/02/2023] [Indexed: 08/13/2023]
Abstract
Due to their essential functions, dysregulation of nuclear pore complexes (NPCs) is strongly associated with numerous human diseases, including neurodegeneration and cancer. On a cellular level, longevity of scaffold nucleoporins in postmitotic cells of both C. elegans and mammals renders them vulnerable to age-related damage, which is associated with an increase in pore leakiness and accumulation of intranuclear aggregates in rat brain cells. Thus, understanding the mechanisms which underpin the homeostasis of this complex, as well as other nuclear proteins, is essential. In this review, autophagy-mediated degradation pathways governing nuclear components in yeast will be discussed, with a particular focus on NPCs. Furthermore, the various nuclear degradation mechanisms identified thus far in diverse eukaryotes will also be highlighted.
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Affiliation(s)
- Emily Boyle
- Mechanisms of Cellular Quality Control, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Florian Wilfling
- Mechanisms of Cellular Quality Control, Max Planck Institute of Biophysics, Frankfurt, Germany
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12
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Hitomi K, Kotani T, Noda NN, Kimura Y, Nakatogawa H. The Atg1 complex, Atg9, and Vac8 recruit PI3K complex I to the pre-autophagosomal structure. J Cell Biol 2023; 222:e202210017. [PMID: 37436710 PMCID: PMC10337603 DOI: 10.1083/jcb.202210017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 03/31/2023] [Accepted: 05/18/2023] [Indexed: 07/13/2023] Open
Abstract
In macroautophagy, cellular components are sequestered within autophagosomes and transported to lysosomes/vacuoles for degradation. Although phosphatidylinositol 3-kinase complex I (PI3KCI) plays a pivotal role in the regulation of autophagosome biogenesis, little is known about how this complex localizes to the pre-autophagosomal structure (PAS). In Saccharomyces cerevisiae, PI3KCI is composed of PI3K Vps34 and conserved subunits Vps15, Vps30, Atg14, and Atg38. In this study, we discover that PI3KCI interacts with the vacuolar membrane anchor Vac8, the PAS scaffold Atg1 complex, and the pre-autophagosomal vesicle component Atg9 via the Atg14 C-terminal region, the Atg38 C-terminal region, and the Vps30 BARA domain, respectively. While the Atg14-Vac8 interaction is constitutive, the Atg38-Atg1 complex interaction and the Vps30-Atg9 interaction are enhanced upon macroautophagy induction depending on Atg1 kinase activity. These interactions cooperate to target PI3KCI to the PAS. These findings provide a molecular basis for PAS targeting of PI3KCI during autophagosome biogenesis.
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Affiliation(s)
- Kanae Hitomi
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Tetsuya Kotani
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Nobuo N. Noda
- Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
| | - Yayoi Kimura
- Advanced Medical Research Center, Yokohama City University, Yokohama, Japan
| | - Hitoshi Nakatogawa
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
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13
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Bâcle J, Groizard L, Kumanski S, Moriel-Carretero M. Nuclear envelope-remodeling events as models to assess the potential role of membranes on genome stability. FEBS Lett 2023; 597:1946-1956. [PMID: 37339935 DOI: 10.1002/1873-3468.14688] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/31/2023] [Accepted: 05/31/2023] [Indexed: 06/22/2023]
Abstract
The nuclear envelope (NE) encloses the genetic material and functions in chromatin organization and stability. In Saccharomyces cerevisiae, the NE is bound to the ribosomal DNA (rDNA), highly repeated and transcribed, thus prone to genetic instability. While tethering limits instability, it simultaneously triggers notable NE remodeling. We posit here that NE remodeling may contribute to genome integrity maintenance. The NE importance in genome expression, structure, and integrity is well recognized, yet studies mostly focus on peripheral proteins and nuclear pores, not on the membrane itself. We recently characterized a NE invagination drastically obliterating the rDNA, which we propose here as a model to probe if and how membranes play an active role in genome stability preservation.
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Affiliation(s)
- Janélie Bâcle
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Centre National de la Recherche Scientifique, Université de Montpellier, France
| | - Léa Groizard
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Centre National de la Recherche Scientifique, Université de Montpellier, France
| | - Sylvain Kumanski
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Centre National de la Recherche Scientifique, Université de Montpellier, France
| | - María Moriel-Carretero
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Centre National de la Recherche Scientifique, Université de Montpellier, France
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14
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Del Vecchio M, Amado L, Cogan AP, Meert E, Rosseels J, Franssens V, Govers SK, Winderickx J, Montoro AG. Multiple tethers of organelle contact sites are involved in α-synuclein toxicity in yeast. Mol Biol Cell 2023; 34:ar84. [PMID: 37074954 PMCID: PMC10398879 DOI: 10.1091/mbc.e23-01-0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/05/2023] [Accepted: 04/12/2023] [Indexed: 04/20/2023] Open
Abstract
The protein α-synuclein (α-syn) is one of the major factors linked to Parkinson's disease, yet how its misfolding and deposition contribute to the pathology remains largely elusive. Recently, contact sites among organelles were implicated in the development of this disease. Here, we used the budding yeast Saccharomyces cerevisiae, in which organelle contact sites have been characterized extensively, as a model to investigate their role in α-syn cytotoxicity. We observed that lack of specific tethers that anchor the endoplasmic reticulum to the plasma membrane resulted in cells with increased resistance to α-syn expression. Additionally, we found that strains lacking two dual-function proteins involved in contact sites, Mdm10 and Vps39, were resistant to the expression of α-syn. In the case of Mdm10, we found that this is related to its function in mitochondrial protein biogenesis and not to its role as a contact site tether. In contrast, both functions of Vps39, in vesicular transport and as a tether of the vacuole-mitochondria contact site, were required to support α-syn toxicity. Overall, our findings support that interorganelle communication through membrane contact sites is highly relevant for α-syn-mediated toxicity.
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Affiliation(s)
- Mara Del Vecchio
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
- Department of Biology, Microbial Systems Cell Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Lucia Amado
- Department of Biology/Chemistry, Cellular Communication Laboratory, Osnabrück University, 49076 Osnabrück, Germany
| | - Alexandra P. Cogan
- Department of Biology/Chemistry, Cellular Communication Laboratory, Osnabrück University, 49076 Osnabrück, Germany
| | - Els Meert
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Joelle Rosseels
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Vanessa Franssens
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Sander K. Govers
- Department of Biology, Microbial Systems Cell Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Joris Winderickx
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Ayelén González Montoro
- Department of Biology/Chemistry, Cellular Communication Laboratory, Osnabrück University, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics Osnabrück, 49076 Osnabrück, Germany
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15
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Santana-Sosa S, Matos-Perdomo E, Ayra-Plasencia J, Machín F. A Yeast Mitotic Tale for the Nucleus and the Vacuoles to Embrace. Int J Mol Sci 2023; 24:9829. [PMID: 37372977 DOI: 10.3390/ijms24129829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/02/2023] [Accepted: 06/03/2023] [Indexed: 06/29/2023] Open
Abstract
The morphology of the nucleus is roughly spherical in most eukaryotic cells. However, this organelle shape needs to change as the cell travels through narrow intercellular spaces during cell migration and during cell division in organisms that undergo closed mitosis, i.e., without dismantling the nuclear envelope, such as yeast. In addition, the nuclear morphology is often modified under stress and in pathological conditions, being a hallmark of cancer and senescent cells. Thus, understanding nuclear morphological dynamics is of uttermost importance, as pathways and proteins involved in nuclear shaping can be targeted in anticancer, antiaging, and antifungal therapies. Here, we review how and why the nuclear shape changes during mitotic blocks in yeast, introducing novel data that associate these changes with both the nucleolus and the vacuole. Altogether, these findings suggest a close relationship between the nucleolar domain of the nucleus and the autophagic organelle, which we also discuss here. Encouragingly, recent evidence in tumor cell lines has linked aberrant nuclear morphology to defects in lysosomal function.
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Affiliation(s)
- Silvia Santana-Sosa
- Research Unit, University Hospital Ntra Sra de Candelaria, Ctra del Rosario 145, 38010 Santa Cruz de Tenerife, Spain
- Institute of Biomedical Technologies, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Emiliano Matos-Perdomo
- Research Unit, University Hospital Ntra Sra de Candelaria, Ctra del Rosario 145, 38010 Santa Cruz de Tenerife, Spain
- Institute of Biomedical Technologies, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Jessel Ayra-Plasencia
- Research Unit, University Hospital Ntra Sra de Candelaria, Ctra del Rosario 145, 38010 Santa Cruz de Tenerife, Spain
- Institute of Biomedical Technologies, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Félix Machín
- Research Unit, University Hospital Ntra Sra de Candelaria, Ctra del Rosario 145, 38010 Santa Cruz de Tenerife, Spain
- Institute of Biomedical Technologies, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
- Faculty of Health Sciences, Fernando Pessoa Canarias University, 35450 Santa María de Guía, Spain
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16
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Kim H, Park J, Kim H, Ko N, Park J, Jang E, Yoon S, Diaz J, Lee C, Jun Y. Structures of Vac8-containing protein complexes reveal the underlying mechanism by which Vac8 regulates multiple cellular processes. Proc Natl Acad Sci U S A 2023; 120:e2211501120. [PMID: 37094131 PMCID: PMC10161063 DOI: 10.1073/pnas.2211501120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 03/30/2023] [Indexed: 04/26/2023] Open
Abstract
Vac8, a yeast vacuolar protein with armadillo repeats, mediates various cellular processes by changing its binding partners; however, the mechanism by which Vac8 differentially regulates these processes remains poorly understood. Vac8 interacts with Nvj1 to form the nuclear-vacuole junction (NVJ) and with Atg13 to mediate cytoplasm-to-vacuole targeting (Cvt), a selective autophagy-like pathway that delivers cytoplasmic aminopeptidase I directly to the vacuole. In addition, Vac8 associates with Myo2, a yeast class V myosin, through its interaction with Vac17 for vacuolar inheritance from the mother cell to the emerging daughter cell during cell divisions. Here, we determined the X-ray crystal structure of the Vac8-Vac17 complex and found that its interaction interfaces are bipartite, unlike those of the Vac8-Nvj1 and Vac8-Atg13 complexes. When the key amino acids present in the interface between Vac8 and Vac17 were mutated, vacuole inheritance was severely impaired in vivo. Furthermore, binding of Vac17 to Vac8 prevented dimerization of Vac8, which is required for its interactions with Nvj1 and Atg13, by clamping the H1 helix to the ARM1 domain of Vac8 and thereby preventing exposure of the binding interface for Vac8 dimerization. Consistently, the binding affinity of Vac17-bound Vac8 for Nvj1 or Atg13 was markedly lower than that of free Vac8. Likewise, free Vac17 had no affinity for the Vac8-Nvj1 and Vac8-Atg13 complexes. These results provide insights into how vacuole inheritance and other Vac8-mediated processes, such as NVJ formation and Cvt, occur independently of one another.
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Affiliation(s)
- Hyejin Kim
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, South Korea
| | - Jihyeon Park
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
| | - Hyunwoo Kim
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, South Korea
| | - Naho Ko
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
| | - Jumi Park
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, South Korea
| | - Eunhong Jang
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
| | - So Young Yoon
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
| | - Joyce Anne R. Diaz
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
| | - Changwook Lee
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan44919, South Korea
| | - Youngsoo Jun
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju61005, South Korea
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17
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Sontag EM, Morales-Polanco F, Chen JH, McDermott G, Dolan PT, Gestaut D, Le Gros MA, Larabell C, Frydman J. Nuclear and cytoplasmic spatial protein quality control is coordinated by nuclear-vacuolar junctions and perinuclear ESCRT. Nat Cell Biol 2023; 25:699-713. [PMID: 37081164 DOI: 10.1038/s41556-023-01128-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 03/14/2023] [Indexed: 04/22/2023]
Abstract
Effective protein quality control (PQC), essential for cellular health, relies on spatial sequestration of misfolded proteins into defined inclusions. Here we reveal the coordination of nuclear and cytoplasmic spatial PQC. Cytoplasmic misfolded proteins concentrate in a cytoplasmic juxtanuclear quality control compartment, while nuclear misfolded proteins sequester into an intranuclear quality control compartment (INQ). Particle tracking reveals that INQ and the juxtanuclear quality control compartment converge to face each other across the nuclear envelope at a site proximal to the nuclear-vacuolar junction marked by perinuclear ESCRT-II/III protein Chm7. Strikingly, convergence at nuclear-vacuolar junction contacts facilitates VPS4-dependent vacuolar clearance of misfolded cytoplasmic and nuclear proteins, the latter entailing extrusion of nuclear INQ into the vacuole. Finding that nuclear-vacuolar contact sites are cellular hubs of spatial PQC to facilitate vacuolar clearance of nuclear and cytoplasmic inclusions highlights the role of cellular architecture in proteostasis maintenance.
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Affiliation(s)
- Emily M Sontag
- Department of Biology, Stanford University, Stanford, CA, USA.
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA.
| | | | - Jian-Hua Chen
- Department of Anatomy, School of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Gerry McDermott
- Department of Anatomy, School of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Patrick T Dolan
- Department of Biology, Stanford University, Stanford, CA, USA
- Quantitative Virology and Evolution Unit, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Daniel Gestaut
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Mark A Le Gros
- Department of Anatomy, School of Medicine, University of California San Francisco, San Francisco, CA, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Carolyn Larabell
- Department of Anatomy, School of Medicine, University of California San Francisco, San Francisco, CA, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Judith Frydman
- Department of Biology, Stanford University, Stanford, CA, USA.
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18
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Reinhard J, Leveille CL, Cornell CE, Merz AJ, Klose C, Ernst R, Keller SL. Remodeling of yeast vacuole membrane lipidomes from the log (one phase) to stationary stage (two phases). Biophys J 2023; 122:1043-1057. [PMID: 36635960 PMCID: PMC10111276 DOI: 10.1016/j.bpj.2023.01.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 01/03/2023] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
Upon nutrient limitation, budding yeast of Saccharomyces cerevisiae shift from fast growth (the log stage) to quiescence (the stationary stage). This shift is accompanied by liquid-liquid phase separation in the membrane of the vacuole, an endosomal organelle. Recent work indicates that the resulting micrometer-scale domains in vacuole membranes enable yeast to survive periods of stress. An outstanding question is which molecular changes might cause this membrane phase separation. Here, we conduct lipidomics of vacuole membranes in both the log and stationary stages. Isolation of pure vacuole membranes is challenging in the stationary stage, when lipid droplets are in close contact with vacuoles. Immuno-isolation has previously been shown to successfully purify log-stage vacuole membranes with high organelle specificity, but it was not previously possible to immuno-isolate stationary-stage vacuole membranes. Here, we develop Mam3 as a bait protein for vacuole immuno-isolation, and demonstrate low contamination by non-vacuolar membranes. We find that stationary-stage vacuole membranes contain surprisingly high fractions of phosphatidylcholine lipids (∼40%), roughly twice as much as log-stage membranes. Moreover, in the stationary stage, these lipids have higher melting temperatures, due to longer and more saturated acyl chains. Another surprise is that no significant change in sterol content is observed. These lipidomic changes, which are largely reflected on the whole-cell level, fit within the predominant view that phase separation in membranes requires at least three types of molecules to be present: lipids with high melting temperatures, lipids with low melting temperatures, and sterols.
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Affiliation(s)
- John Reinhard
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany; PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany
| | | | | | - Alexey J Merz
- Department of Biochemistry, University of Washington, Seattle, WA
| | | | - Robert Ernst
- Medical Biochemistry and Molecular Biology, Medical Faculty, Saarland University, Homburg, Germany; PZMS, Center for Molecular Signaling, Medical Faculty, Saarland University, Homburg, Germany.
| | - Sarah L Keller
- Department of Chemistry, University of Washington, Seattle, WA.
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19
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Satoh AO, Fujioka Y, Kashiwagi S, Yoshida A, Fujioka M, Sasajima H, Nanbo A, Amano M, Ohba Y. Interaction between PI3K and the VDAC2 channel tethers Ras-PI3K-positive endosomes to mitochondria and promotes endosome maturation. Cell Rep 2023; 42:112229. [PMID: 36906852 DOI: 10.1016/j.celrep.2023.112229] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/01/2023] [Accepted: 02/21/2023] [Indexed: 03/13/2023] Open
Abstract
Intracellular organelles of mammalian cells communicate with one another during various cellular processes. The functions and molecular mechanisms of such interorganelle association remain largely unclear, however. We here identify voltage-dependent anion channel 2 (VDAC2), a mitochondrial outer membrane protein, as a binding partner of phosphoinositide 3-kinase (PI3K), a regulator of clathrin-independent endocytosis downstream of the small GTPase Ras. VDAC2 tethers endosomes positive for the Ras-PI3K complex to mitochondria in response to cell stimulation with epidermal growth factor and promotes clathrin-independent endocytosis, as well as endosome maturation at membrane association sites. With an optogenetics system to induce mitochondrion-endosome association, we find that, in addition to its structural role in such association, VDAC2 is functionally implicated in the promotion of endosome maturation. The mitochondrion-endosome association thus plays a role in the regulation of clathrin-independent endocytosis and endosome maturation.
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Affiliation(s)
- Aya O Satoh
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-ku, Sapporo 060-8638, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Kita-ku, Sapporo 060-8638, Japan
| | - Yoichiro Fujioka
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-ku, Sapporo 060-8638, Japan; Global Station for Biosurfaces and Drug Discovery, Hokkaido University, N12W6, Kita-ku, Sapporo 060-0812, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Kita-ku, Sapporo 060-8638, Japan
| | - Sayaka Kashiwagi
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-ku, Sapporo 060-8638, Japan; Global Station for Biosurfaces and Drug Discovery, Hokkaido University, N12W6, Kita-ku, Sapporo 060-0812, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Kita-ku, Sapporo 060-8638, Japan
| | - Aiko Yoshida
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-ku, Sapporo 060-8638, Japan; Global Station for Biosurfaces and Drug Discovery, Hokkaido University, N12W6, Kita-ku, Sapporo 060-0812, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Kita-ku, Sapporo 060-8638, Japan
| | - Mari Fujioka
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-ku, Sapporo 060-8638, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Kita-ku, Sapporo 060-8638, Japan
| | - Hitoshi Sasajima
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-ku, Sapporo 060-8638, Japan
| | - Asuka Nanbo
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-ku, Sapporo 060-8638, Japan
| | - Maho Amano
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-ku, Sapporo 060-8638, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Kita-ku, Sapporo 060-8638, Japan
| | - Yusuke Ohba
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-ku, Sapporo 060-8638, Japan; Global Station for Biosurfaces and Drug Discovery, Hokkaido University, N12W6, Kita-ku, Sapporo 060-0812, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Kita-ku, Sapporo 060-8638, Japan.
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20
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Park JW, Lee EJ, Moon E, Kim HL, Kim IB, Hodzic D, Kim N, Kweon HS, Kim JW. Orthodenticle homeobox 2 is transported to lysosomes by nuclear budding vesicles. Nat Commun 2023; 14:1111. [PMID: 36849521 PMCID: PMC9971051 DOI: 10.1038/s41467-023-36697-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 02/08/2023] [Indexed: 03/01/2023] Open
Abstract
Transcription factors (TFs) are transported from the cytoplasm to the nucleus and disappear from the nucleus after they regulate gene expression. Here, we discover an unconventional nuclear export of the TF, orthodenticle homeobox 2 (OTX2), in nuclear budding vesicles, which transport OTX2 to the lysosome. We further find that torsin1a (Tor1a) is responsible for scission of the inner nuclear vesicle, which captures OTX2 using the LINC complex. Consistent with this, in cells expressing an ATPase-inactive Tor1aΔE mutant and the LINC (linker of nucleoskeleton and cytoskeleton) breaker KASH2, OTX2 accumulated and formed aggregates in the nucleus. Consequently, in the mice expressing Tor1aΔE and KASH2, OTX2 could not be secreted from the choroid plexus for transfer to the visual cortex, leading to failed development of parvalbumin neurons and reduced visual acuity. Together, our results suggest that unconventional nuclear egress and secretion of OTX2 are necessary not only to induce functional changes in recipient cells but also to prevent aggregation in donor cells.
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Affiliation(s)
- Jun Woo Park
- Department of Biological Sciences and Stem Cell Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
| | - Eun Jung Lee
- Department of Biological Sciences and Stem Cell Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
| | - Eunyoung Moon
- Electron Microscopy Research Center, Korea Basic Science Institute, Cheongju, 28119, South Korea
| | - Hong-Lim Kim
- Integrative Research Support Center, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - In-Beom Kim
- Integrative Research Support Center, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Didier Hodzic
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Namsuk Kim
- Department of Biological Sciences and Stem Cell Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea.,Neurovascular Unit, Korea Brain Research Institute, Daegu, 41062, South Korea
| | - Hee-Seok Kweon
- Electron Microscopy Research Center, Korea Basic Science Institute, Cheongju, 28119, South Korea
| | - Jin Woo Kim
- Department of Biological Sciences and Stem Cell Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea.
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21
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Capitanio C, Bieber A, Wilfling F. How Membrane Contact Sites Shape the Phagophore. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2023; 6:25152564231162495. [PMID: 37366413 PMCID: PMC10243513 DOI: 10.1177/25152564231162495] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 02/15/2023] [Accepted: 02/18/2023] [Indexed: 06/28/2023]
Abstract
During macroautophagy, phagophores establish multiple membrane contact sites (MCSs) with other organelles that are pivotal for proper phagophore assembly and growth. In S. cerevisiae, phagophore contacts have been observed with the vacuole, the ER, and lipid droplets. In situ imaging studies have greatly advanced our understanding of the structure and function of these sites. Here, we discuss how in situ structural methods like cryo-CLEM can give unprecedented insights into MCSs, and how they help to elucidate the structural arrangements of MCSs within cells. We further summarize the current knowledge of the contact sites in autophagy, focusing on autophagosome biogenesis in the model organism S. cerevisiae.
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Affiliation(s)
- Cristina Capitanio
- Department of Molecular Machines and
Signaling, Max Planck Institute of Biochemistry, Martinsried, Germany
- Aligning Science Across Parkinson's (ASAP)
Collaborative Research Network, Chevy Chase, MD, USA
| | - Anna Bieber
- Department of Molecular Machines and
Signaling, Max Planck Institute of Biochemistry, Martinsried, Germany
- Aligning Science Across Parkinson's (ASAP)
Collaborative Research Network, Chevy Chase, MD, USA
| | - Florian Wilfling
- Mechanisms of Cellular Quality Control, Max Planck Institute of Biophysics, Frankfurt a. M., Germany
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22
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Huet D, Moreno SNJ. Interorganellar Communication Through Membrane Contact Sites in Toxoplasma Gondii. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2023; 6:25152564231189064. [PMID: 37560622 PMCID: PMC10408353 DOI: 10.1177/25152564231189064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 08/11/2023]
Abstract
Apicomplexan parasites are a group of protists that cause disease in humans and include pathogens like Plasmodium spp., the causative agent of malaria, and Toxoplasma gondii, the etiological agent of toxoplasmosis and one of the most ubiquitous human parasites in the world. Membrane contact sites (MCSs) are widespread structures within eukaryotic cells but their characterization in apicomplexan parasites is only in its very beginnings. Basic biological features of the T. gondii parasitic cycle support numerous organellar interactions, including the transfer of Ca2+ and metabolites between different compartments. In T. gondii, Ca2+ signals precede a series of interrelated molecular processes occurring in a coordinated manner that culminate in the stimulation of key steps of the parasite life cycle. Calcium transfer from the endoplasmic reticulum to other organelles via MCSs would explain the precision, speed, and efficiency that is needed during the lytic cycle of T. gondii. In this short review, we discuss the implications of these structures in cellular signaling, with an emphasis on their potential role in Ca2+ signaling.
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Affiliation(s)
- Diego Huet
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
- Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA
| | - Silvia N. J. Moreno
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
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23
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Kümmel D, Herrmann E, Langemeyer L, Ungermann C. Molecular insights into endolysosomal microcompartment formation and maintenance. Biol Chem 2022; 404:441-454. [PMID: 36503831 DOI: 10.1515/hsz-2022-0294] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/22/2022] [Indexed: 12/14/2022]
Abstract
Abstract
The endolysosomal system of eukaryotic cells has a key role in the homeostasis of the plasma membrane, in signaling and nutrient uptake, and is abused by viruses and pathogens for entry. Endocytosis of plasma membrane proteins results in vesicles, which fuse with the early endosome. If destined for lysosomal degradation, these proteins are packaged into intraluminal vesicles, converting an early endosome to a late endosome, which finally fuses with the lysosome. Each of these organelles has a unique membrane surface composition, which can form segmented membrane microcompartments by membrane contact sites or fission proteins. Furthermore, these organelles are in continuous exchange due to fission and fusion events. The underlying machinery, which maintains organelle identity along the pathway, is regulated by signaling processes. Here, we will focus on the Rab5 and Rab7 GTPases of early and late endosomes. As molecular switches, Rabs depend on activating guanine nucleotide exchange factors (GEFs). Over the last years, we characterized the Rab7 GEF, the Mon1-Ccz1 (MC1) complex, and key Rab7 effectors, the HOPS complex and retromer. Structural and functional analyses of these complexes lead to a molecular understanding of their function in the context of organelle biogenesis.
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Affiliation(s)
- Daniel Kümmel
- Institute of Biochemistry, University of Münster , Corrensstraße 36 , D-48149 Münster , Germany
| | - Eric Herrmann
- Institute of Biochemistry, University of Münster , Corrensstraße 36 , D-48149 Münster , Germany
| | - Lars Langemeyer
- Department of Biology/Chemistry, Biochemistry section , Osnabrück University , Barbarastraße 13 , D-49076 Osnabrück , Germany
- Center of Cellular Nanoanalytics (CellNanOs) , Osnabrück University , Barbarastraße 11 , D-49076 Osnabrück , Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry section , Osnabrück University , Barbarastraße 13 , D-49076 Osnabrück , Germany
- Center of Cellular Nanoanalytics (CellNanOs) , Osnabrück University , Barbarastraße 11 , D-49076 Osnabrück , Germany
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24
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Zwilling E, Reggiori F. Membrane Contact Sites in Autophagy. Cells 2022; 11:cells11233813. [PMID: 36497073 PMCID: PMC9735501 DOI: 10.3390/cells11233813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022] Open
Abstract
Eukaryotes utilize different communication strategies to coordinate processes between different cellular compartments either indirectly, through vesicular transport, or directly, via membrane contact sites (MCSs). MCSs have been implicated in lipid metabolism, calcium signaling and the regulation of organelle biogenesis in various cell types. Several studies have shown that MCSs play a crucial role in the regulation of macroautophagy, an intracellular catabolic transport route that is characterized by the delivery of cargoes (proteins, protein complexes or aggregates, organelles and pathogens) to yeast and plant vacuoles or mammalian lysosomes, for their degradation and recycling into basic metabolites. Macroautophagy is characterized by the de novo formation of double-membrane vesicles called autophagosomes, and their biogenesis requires an enormous amount of lipids. MCSs appear to have a central role in this supply, as well as in the organization of the autophagy-related (ATG) machinery. In this review, we will summarize the evidence for the participation of specific MCSs in autophagosome formation, with a focus on the budding yeast and mammalian systems.
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Affiliation(s)
- Emma Zwilling
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000C Aarhus, Denmark
| | - Fulvio Reggiori
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000C Aarhus, Denmark
- Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Høegh-Guldbergs Gade 6B, 8000C Aarhus, Denmark
- Correspondence:
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25
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Castro IG, Shortill SP, Dziurdzik SK, Cadou A, Ganesan S, Valenti R, David Y, Davey M, Mattes C, Thomas FB, Avraham RE, Meyer H, Fadel A, Fenech EJ, Ernst R, Zaremberg V, Levine TP, Stefan C, Conibear E, Schuldiner M. Systematic analysis of membrane contact sites in Saccharomyces cerevisiae uncovers modulators of cellular lipid distribution. eLife 2022; 11:74602. [DOI: 10.7554/elife.74602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 10/19/2022] [Indexed: 11/11/2022] Open
Abstract
Actively maintained close appositions between organelle membranes, also known as contact sites, enable the efficient transfer of biomolecules between cellular compartments. Several such sites have been described as well as their tethering machineries. Despite these advances we are still far from a comprehensive understanding of the function and regulation of most contact sites. To systematically characterize contact site proteomes, we established a high-throughput screening approach in Saccharomyces cerevisiae based on co-localization imaging. We imaged split fluorescence reporters for six different contact sites, several of which are poorly characterized, on the background of 1165 strains expressing a mCherry-tagged yeast protein that has a cellular punctate distribution (a hallmark of contact sites), under regulation of the strong TEF2 promoter. By scoring both co-localization events and effects on reporter size and abundance, we discovered over 100 new potential contact site residents and effectors in yeast. Focusing on several of the newly identified residents, we identified three homologs of Vps13 and Atg2 that are residents of multiple contact sites. These proteins share their lipid transport domain, thus expanding this family of lipid transporters. Analysis of another candidate, Ypr097w, which we now call Lec1 (Lipid-droplet Ergosterol Cortex 1), revealed that this previously uncharacterized protein dynamically shifts between lipid droplets and the cell cortex, and plays a role in regulation of ergosterol distribution in the cell. Overall, our analysis expands the universe of contact site residents and effectors and creates a rich database to mine for new functions, tethers, and regulators.
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Affiliation(s)
| | - Shawn P Shortill
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Samantha Katarzyna Dziurdzik
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Angela Cadou
- Laboratory for Molecular Cell Biology, University College London
| | | | - Rosario Valenti
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Yotam David
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Michael Davey
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
| | - Carsten Mattes
- Medical Biochemistry and Molecular Biology, PZMS, Medical Faculty, Saarland University
| | - Ffion B Thomas
- Laboratory for Molecular Cell Biology, University College London
| | | | - Hadar Meyer
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Amir Fadel
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Emma J Fenech
- Department of Molecular Genetics, Weizmann Institute of Science
| | - Robert Ernst
- Medical Biochemistry and Molecular Biology, PZMS, Medical Faculty, Saarland University
| | | | - Tim P Levine
- UCL Institute of Ophthalmology, University College London
| | | | - Elizabeth Conibear
- Centre for Molecular Medicine and Therapeutics, British Columbia Children’s Hospital Research Institute, University of British Columbia
- Department of Medical Genetics, University of British Columbia
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science
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26
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Matos-Perdomo E, Santana-Sosa S, Ayra-Plasencia J, Medina-Suárez S, Machín F. The vacuole shapes the nucleus and the ribosomal DNA loop during mitotic delays. Life Sci Alliance 2022; 5:5/10/e202101161. [PMID: 35961781 PMCID: PMC9375157 DOI: 10.26508/lsa.202101161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 07/20/2022] [Accepted: 07/20/2022] [Indexed: 11/24/2022] Open
Abstract
Chromosome structuring and condensation is one of the main features of mitosis. Here, Matos-Perdomo et al show how the nuclear envelope reshapes around the vacuole to give rise to the outstanding ribosomal DNA loop in budding yeast. The ribosomal DNA (rDNA) array of Saccharomyces cerevisiae has served as a model to address chromosome organization. In cells arrested before anaphase (mid-M), the rDNA acquires a highly structured chromosomal organization referred to as the rDNA loop, whose length can double the cell diameter. Previous works established that complexes such as condensin and cohesin are essential to attain this structure. Here, we report that the rDNA loop adopts distinct presentations that arise as spatial adaptations to changes in the nuclear morphology triggered during mid-M arrests. Interestingly, the formation of the rDNA loop results in the appearance of a space under the loop (SUL) which is devoid of nuclear components yet colocalizes with the vacuole. We show that the rDNA-associated nuclear envelope (NE) often reshapes into a ladle to accommodate the vacuole in the SUL, with the nucleus becoming bilobed and doughnut-shaped. Finally, we demonstrate that the formation of the rDNA loop and the SUL require TORC1, membrane synthesis and functional vacuoles, yet is independent of nucleus–vacuole junctions and rDNA-NE tethering.
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Affiliation(s)
- Emiliano Matos-Perdomo
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.,Escuela de Doctorado y Estudios de Postgrado, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Silvia Santana-Sosa
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.,Escuela de Doctorado y Estudios de Postgrado, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Jessel Ayra-Plasencia
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.,Escuela de Doctorado y Estudios de Postgrado, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Sara Medina-Suárez
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.,Escuela de Doctorado y Estudios de Postgrado, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Félix Machín
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain .,Instituto de Tecnologías Biomédicas, Universidad de La Laguna, Santa Cruz de Tenerife, Spain.,Facultad de Ciencias de la Salud, Universidad Fernando Pessoa Canarias, Santa María de Guía, Spain
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27
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Niemann-Pick Type C Proteins Are Required for Sterol Transport and Appressorium-Mediated Plant Penetration of Colletotrichum orbiculare. mBio 2022; 13:e0223622. [PMID: 36154185 PMCID: PMC9600679 DOI: 10.1128/mbio.02236-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many biotrophic and hemibiotrophic fungal pathogens use appressoria to directly penetrate the host plant surface. In the cucumber anthracnose fungus Colletotrichum orbiculare, differentiation of appressoria requires a proper G1/S cell cycle progression, regulated by the GTPase-activating protein complex CoBub2-CoBfa1 and its downstream GTPase CoTem1. To explore the mechanisms by which the CoTem1 cascade regulates plant infection, we screened for CoTem1 interaction factors and identified a Niemann-Pick type C2 homolog (CoNpc2). Niemann-Pick type C proteins NPC1 and NPC2 are sterol-binding proteins required for sterol export from lysosomes (vacuoles) in humans and yeasts. We showed that CoNpc2 colocalized with CoNpc1 in late endosomes and vacuoles and that disruption of its gene resulted in aberrant sterol accumulation in vacuoles and loss of sterol membrane localization, indicating that NPC proteins are engaged in sterol transport in C. orbiculare. For appressorium infection, sterol transport and proper distribution mediated by CoNpc1 and CoNpc2 are critical for membrane integrity and membrane curvature with actin assembly, leading to penetration peg emergence and appressorial cone formation. Our results revealed a novel mechanism by which NPC proteins regulate appressorium-mediated plant infection.
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28
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Mannino PJ, Lusk CP. Quality control mechanisms that protect nuclear envelope identity and function. J Biophys Biochem Cytol 2022; 221:213424. [PMID: 36036741 PMCID: PMC9442147 DOI: 10.1083/jcb.202205123] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 08/08/2022] [Accepted: 08/10/2022] [Indexed: 11/22/2022] Open
Abstract
The nuclear envelope (NE) is a specialization of the endoplasmic reticulum with distinct biochemistry that defines inner and outer membranes connected at a pore membrane that houses nuclear pore complexes (NPCs). Quality control mechanisms that maintain the physical integrity and biochemical identity of these membranes are critical to ensure that the NE acts as a selective barrier that also contributes to genome stability and metabolism. As the proteome of the NE is highly integrated, it is challenging to turn over by conventional ubiquitin-proteasome and autophagy mechanisms. Further, removal of entire sections of the NE requires elaborate membrane remodeling that is poorly understood. Nonetheless, recent work has made inroads into discovering specializations of cellular degradative machineries tailored to meeting the unique challenges imposed by the NE. In addition, cells have evolved mechanisms to surveil and repair the NE barrier to protect against the deleterious effects of a breach in NE integrity, in the form of either a ruptured NE or a dysfunctional NPC. Here, we synthesize the most recent work exploring NE quality control mechanisms across eukaryotes.
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29
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Bisinski DD, Gomes Castro I, Mari M, Walter S, Fröhlich F, Schuldiner M, González Montoro A. Cvm1 is a component of multiple vacuolar contact sites required for sphingolipid homeostasis. J Biophys Biochem Cytol 2022; 221:213309. [PMID: 35766971 PMCID: PMC9247719 DOI: 10.1083/jcb.202103048] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/05/2022] [Accepted: 06/13/2022] [Indexed: 02/03/2023] Open
Abstract
Membrane contact sites are specialized platforms formed between most organelles that enable them to exchange metabolites and influence the dynamics of each other. The yeast vacuole is a degradative organelle equivalent to the lysosome in higher eukaryotes with important roles in ion homeostasis and metabolism. Using a high-content microscopy screen, we identified Ymr160w (Cvm1, for contact of the vacuole membrane 1) as a novel component of three different contact sites of the vacuole: with the nuclear endoplasmic reticulum, the mitochondria, and the peroxisomes. At the vacuole-mitochondria contact site, Cvm1 acts as a tether independently of previously known tethers. We show that changes in Cvm1 levels affect sphingolipid homeostasis, altering the levels of multiple sphingolipid classes and the response of sphingolipid-sensing signaling pathways. Furthermore, the contact sites formed by Cvm1 are induced upon a decrease in sphingolipid levels. Altogether, our work identifies a novel protein that forms multiple contact sites and supports a role of lysosomal contacts in sphingolipid homeostasis.
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Affiliation(s)
- Daniel D. Bisinski
- Department of Biology/Chemistry, Cellular Communication Laboratory, University of Osnabrück, Osnabrück, Germany
| | - Inês Gomes Castro
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Muriel Mari
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Stefan Walter
- Center of Cellular Nanoanalytics Osnabrück, Osnabrück, Germany
| | - Florian Fröhlich
- Center of Cellular Nanoanalytics Osnabrück, Osnabrück, Germany,Department of Biology/Chemistry, Molecular Membrane Biology Group, University of Osnabrück, Osnabrück, Germany
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ayelén González Montoro
- Department of Biology/Chemistry, Cellular Communication Laboratory, University of Osnabrück, Osnabrück, Germany,Center of Cellular Nanoanalytics Osnabrück, Osnabrück, Germany
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30
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Vrijsen S, Vrancx C, Del Vecchio M, Swinnen JV, Agostinis P, Winderickx J, Vangheluwe P, Annaert W. Inter-organellar Communication in Parkinson's and Alzheimer's Disease: Looking Beyond Endoplasmic Reticulum-Mitochondria Contact Sites. Front Neurosci 2022; 16:900338. [PMID: 35801175 PMCID: PMC9253489 DOI: 10.3389/fnins.2022.900338] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 05/05/2022] [Indexed: 01/13/2023] Open
Abstract
Neurodegenerative diseases (NDs) are generally considered proteinopathies but whereas this may initiate disease in familial cases, onset in sporadic diseases may originate from a gradually disrupted organellar homeostasis. Herein, endolysosomal abnormalities, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and altered lipid metabolism are commonly observed in early preclinical stages of major NDs, including Parkinson's disease (PD) and Alzheimer's disease (AD). Among the multitude of underlying defective molecular mechanisms that have been suggested in the past decades, dysregulation of inter-organellar communication through the so-called membrane contact sites (MCSs) is becoming increasingly apparent. Although MCSs exist between almost every other type of subcellular organelle, to date, most focus has been put on defective communication between the ER and mitochondria in NDs, given these compartments are critical in neuronal survival. Contributions of other MCSs, notably those with endolysosomes and lipid droplets are emerging, supported as well by genetic studies, identifying genes functionally involved in lysosomal homeostasis. In this review, we summarize the molecular identity of the organelle interactome in yeast and mammalian cells, and critically evaluate the evidence supporting the contribution of disturbed MCSs to the general disrupted inter-organellar homeostasis in NDs, taking PD and AD as major examples.
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Affiliation(s)
- Stephanie Vrijsen
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, KU Leuven, Leuven, Belgium
| | - Céline Vrancx
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, KU Leuven, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Mara Del Vecchio
- Laboratory of Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
| | - Johannes V. Swinnen
- Laboratory of Lipid Metabolism and Cancer, Department of Oncology, Leuven Cancer Institute (LKI), KU Leuven, Leuven, Belgium
- Johannes V. Swinnen
| | - Patrizia Agostinis
- Laboratory of Cell Death Research and Therapy, VIB-Center for Cancer Research, KU Leuven, Leuven, Belgium
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
- Patrizia Agostinis
| | - Joris Winderickx
- Laboratory of Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
- Joris Winderickx
| | - Peter Vangheluwe
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, KU Leuven, Leuven, Belgium
- Peter Vangheluwe
| | - Wim Annaert
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, KU Leuven, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
- *Correspondence: Wim Annaert
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31
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Girik V, Feng S, Hariri H, Henne WM, Riezman H. Vacuole-Specific Lipid Release for Tracking Intracellular Lipid Metabolism and Transport in Saccharomyces cerevisiae. ACS Chem Biol 2022; 17:1485-1494. [PMID: 35667650 PMCID: PMC9207805 DOI: 10.1021/acschembio.2c00120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lipid metabolism is spatiotemporally regulated within cells, yet intervention into lipid functions at subcellular resolution remains difficult. Here, we report a method that enables site-specific release of sphingolipids and cholesterol inside the vacuole in Saccharomyces cerevisiae. Using this approach, we monitored real-time sphingolipid metabolic flux out of the vacuole by mass spectrometry and found that the endoplasmic reticulum-vacuole-tethering protein Mdm1 facilitated the metabolism of sphingoid bases into ceramides. In addition, we showed that cholesterol, once delivered into yeast using our method, could restore cell proliferation induced by ergosterol deprivation, overcoming the previously described sterol-uptake barrier under aerobic conditions. Together, these data define a new way to study intracellular lipid metabolism and transport from the vacuole in yeast.
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Affiliation(s)
- Vladimir Girik
- Department of Biochemistry, University of Geneva, Geneva 1205, Switzerland
| | - Suihan Feng
- Department of Biochemistry, University of Geneva, Geneva 1205, Switzerland.,National Centre of Competence in Research (NCCR) in Chemical Biology, University of Geneva, Geneva 1205, Switzerland
| | - Hanaa Hariri
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas 75390-9039 United States
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas 75390-9039 United States
| | - Howard Riezman
- Department of Biochemistry, University of Geneva, Geneva 1205, Switzerland
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32
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Garcia M, Kumanski S, Elías-Villalobos A, Cazevieille C, Soulet C, Moriel-Carretero M. Nuclear ingression of cytoplasmic bodies accompanies a boost in autophagy. Life Sci Alliance 2022; 5:5/9/e202101160. [PMID: 35568434 PMCID: PMC9107791 DOI: 10.26508/lsa.202101160] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 05/02/2022] [Accepted: 05/02/2022] [Indexed: 12/28/2022] Open
Abstract
We describe a fully new remodeling event of the nuclear envelope surrounding the nucleolus: it partitions into its regular contact with the vacuole and a dramatic internalization of globular cytoplasmic portions within the nucleus. Membrane contact sites are functional nodes at which organelles reorganize metabolic pathways and adapt to changing cues. In Saccharomyces cerevisiae, the nuclear envelope subdomain surrounding the nucleolus, very plastic and prone to expansion, can establish contacts with the vacuole and be remodeled in response to various metabolic stresses. While using genotoxins with unrelated purposes, we serendipitously discovered a fully new remodeling event at this nuclear subdomain: the nuclear envelope partitions into its regular contact with the vacuole and a dramatic internalization within the nucleus. This leads to the nuclear engulfment of a globular, cytoplasmic portion. In spite of how we discovered it, the phenomenon is likely DNA damage-independent. We define lipids supporting negative curvature, such as phosphatidic acid and sterols, as bona fide drivers of this event. Mechanistically, we suggest that the engulfment of the cytoplasm triggers a suction phenomenon that enhances the docking of proton pump-containing vesicles with the vacuolar membrane, which we show matches a boost in autophagy. Thus, our findings unveil an unprecedented remodeling of the nucleolus-surrounding membranes with impact on metabolic adaptation.
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Affiliation(s)
- Manon Garcia
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, Montpellier, France
| | - Sylvain Kumanski
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, Montpellier, France
| | - Alberto Elías-Villalobos
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Virgen del Rocío-CSIC-Universidad de Sevilla, Sevilla, Spain.,Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
| | - Chantal Cazevieille
- Institut de Neurosciences de Montpellier (INM), Université de Montpellier, INSERM, Montpellier, France
| | - Caroline Soulet
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, Montpellier, France
| | - María Moriel-Carretero
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, Montpellier, France
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33
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Varberg JM, Unruh JR, Bestul AJ, Khan AA, Jaspersen SL. Quantitative analysis of nuclear pore complex organization in Schizosaccharomyces pombe. Life Sci Alliance 2022; 5:5/7/e202201423. [PMID: 35354597 PMCID: PMC8967992 DOI: 10.26508/lsa.202201423] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/11/2022] [Accepted: 03/14/2022] [Indexed: 01/06/2023] Open
Abstract
Characterization of nuclear pores in Schizosaccharomyces pombe identifies regions of heterogeneous NPC density and composition and shows that NPCs are excluded near the spindle pole body by Lem2-mediated centromere tethering. The number, distribution, and composition of nuclear pore complexes (NPCs) in the nuclear envelope varies between cell types and changes during cellular differentiation and in disease. To understand how NPC density and organization are controlled, we analyzed the NPC number and distribution in the fission yeast Schizosaccharomyces pombe using structured illumination microscopy. The small size of yeast nuclei, genetic features of fungi, and our robust image analysis pipeline allowed us to study NPCs in intact nuclei under multiple conditions. Our data revealed that NPC density is maintained across a wide range of nuclear sizes. Regions of reduced NPC density are observed over the nucleolus and surrounding the spindle pole body (SPB). Lem2-mediated tethering of the centromeres to the SPB is required to maintain NPC exclusion near SPBs. These findings provide a quantitative understanding of NPC number and distribution in S. pombe and show that interactions between the centromere and the nuclear envelope influences local NPC distribution.
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Affiliation(s)
| | - Jay R Unruh
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Andrew J Bestul
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Azqa A Khan
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Sue L Jaspersen
- Stowers Institute for Medical Research, Kansas City, MO, USA .,Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
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34
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Konstantinidis G, Tavernarakis N. Autophagy of the Nucleus in Health and Disease. Front Cell Dev Biol 2022; 9:814955. [PMID: 35047516 PMCID: PMC8762222 DOI: 10.3389/fcell.2021.814955] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 12/06/2021] [Indexed: 12/27/2022] Open
Abstract
Nucleophagy is an organelle-selective subtype of autophagy that targets nuclear material for degradation. The macroautophagic delivery of micronuclei to the vacuole, together with the nucleus-vacuole junction-dependent microautophagic degradation of nuclear material, were first observed in yeast. Nuclear pore complexes and ribosomal DNA are typically excluded during conventional macronucleophagy and micronucleophagy, indicating that degradation of nuclear cargo is tightly regulated. In mammals, similarly to other autophagy subtypes, nucleophagy is crucial for cellular differentiation and development, in addition to enabling cells to respond to various nuclear insults and cell cycle perturbations. A common denominator of all nucleophagic processes characterized in diverse organisms is the dependence on the core autophagic machinery. Here, we survey recent studies investigating the autophagic processing of nuclear components. We discuss nucleophagic events in the context of pathology, such as neurodegeneration, cancer, DNA damage, and ageing.
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Affiliation(s)
- Georgios Konstantinidis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Greece.,Department of Basic Sciences, School of Medicine, University of Crete, Heraklion, Greece
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35
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Degradation of nuclear components via different autophagy pathways. Trends Cell Biol 2022; 32:574-584. [DOI: 10.1016/j.tcb.2021.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/21/2021] [Accepted: 12/23/2021] [Indexed: 12/21/2022]
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36
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Lu MS, Drubin DG. Unexplored Cdc42 functions at the budding yeast nucleus suggested by subcellular localization. Small GTPases 2022; 13:255-266. [PMID: 34689711 PMCID: PMC9707532 DOI: 10.1080/21541248.2021.1993714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
In budding yeast, the Rho-family GTPase Cdc42 has several functions that depend on its subcellular localization and the cell cycle stage. During bud formation, Cdc42 localizes to the plasma membrane at the bud tip and bud neck where it carries out functions in actin polymerization, spindle positioning, and exocytosis to ensure proper polarity development. Recent live-cell imaging analysis revealed a novel localization of Cdc42 to a discrete intracellular focus associated with the vacuole and nuclear envelope. The discovery of this novel Cdc42 localization led to the identification of a new function in ESCRT-mediated nuclear envelope sealing. However, other aspects of this intracellular localization and its functional implications were not explored. Here, we further characterize the Cdc42 focus and present several novel observations that suggest possible additional Cdc42 functions at the nucleus, including nucleus-vacuole junction formation, nuclear envelope tethering, nuclear migration, and nucleopodia formation.
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Affiliation(s)
- Michelle S. Lu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA,CONTACT Michelle S. Lu Department of Molecular and Cell Biology, University of California, 16 Barker Hall, Berkeley, California, 94720-3202, USA
| | - David G. Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
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37
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Sharma K, Asp NT, Harrison SP, Siller R, Baumgarten SF, Gupta S, Chollet ME, Andersen E, Sullivan GJ, Simonsen A. Autophagy modulates cell fate decisions during lineage commitment. Autophagy 2021; 18:1915-1931. [PMID: 34923909 PMCID: PMC9450964 DOI: 10.1080/15548627.2021.2008691] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Early events during development leading to exit from a pluripotent state and commitment toward a specific germ layer still need in depth understanding. Autophagy has been shown to play a crucial role in both development and differentiation. This study employs human embryonic and induced pluripotent stem cells to understand the early events of lineage commitment with respect to the role of autophagy in this process. Our data indicate that a dip in autophagy facilitates exit from pluripotency. Upon exit, we demonstrate that the modulation of autophagy affects SOX2 levels and lineage commitment, with induction of autophagy promoting SOX2 degradation and mesendoderm formation, whereas inhibition of autophagy causes SOX2 accumulation and neuroectoderm formation. Thus, our results indicate that autophagy-mediated SOX2 turnover is a determining factor for lineage commitment. These findings will deepen our understanding of development and lead to improved methods to derive different lineages and cell types.Abbreviations: ACTB: Actin, beta; ATG: Autophagy-related; BafA1: Bafilomycin A1; CAS9: CRISPR associated protein 9; CQ: Chloroquine; DE: Definitive endoderm; hESCs: Human Embryonic Stem Cells; hiPSCs: Human Induced Pluripotent Stem Cells; LAMP1: Lysosomal Associated Membrane Protein 1; MAP1LC3: Microtubule-Associated Protein 1 Light Chain 3; MTOR: Mechanistic Target Of Rapamycin Kinase; NANOG: Nanog Homeobox; PAX6: Paired Box 6; PE: Phosphatidylethanolamine; POU5F1: POU class 5 Homeobox 1; PRKAA2: Protein Kinase AMP-Activated Catalytic Subunit Alpha 2; SOX2: SRY-box Transcription Factor 2; SQSTM1: Sequestosome 1; ULK1: unc-51 like Autophagy Activating Kinase 1; WDFY3: WD Repeat and FYVE Domain Containing 3.
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Affiliation(s)
- Kulbhushan Sharma
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Division of Stem Cell and Gene Therapy Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), Delhi, India.,Department of Neurology, Akershus University Hospital, Lørenskog, Norway
| | - Nagham T Asp
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Sean P Harrison
- Department of Pediatric Research, Oslo University Hospital, Oslo, Norway
| | - Richard Siller
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Saphira F Baumgarten
- Hybrid Technology Hub, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Swapnil Gupta
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Department of Neurology, Akershus University Hospital, Lørenskog, Norway
| | - Maria E Chollet
- Research Institute of Internal Medicine, Oslo University Hospital, Oslo, Norway.,Department of Haematology, Oslo University Hospital, Oslo, Norway
| | - Elisabeth Andersen
- Research Institute of Internal Medicine, Oslo University Hospital, Oslo, Norway.,Department of Haematology, Oslo University Hospital, Oslo, Norway
| | - Gareth J Sullivan
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Department of Pediatric Research, Oslo University Hospital, Oslo, Norway.,Hybrid Technology Hub, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Norwegian Center for Stem Cell Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,Institute of Immunology, Oslo University Hospital, Oslo, Norway
| | - Anne Simonsen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital Montebello, Oslo, Norway
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38
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Spatial control of avidity regulates initiation and progression of selective autophagy. Nat Commun 2021; 12:7194. [PMID: 34893607 PMCID: PMC8664900 DOI: 10.1038/s41467-021-27420-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 11/17/2021] [Indexed: 11/11/2022] Open
Abstract
Autophagosomes form at the endoplasmic reticulum in mammals, and between the vacuole and the endoplasmic reticulum in yeast. However, the roles of these sites and the mechanisms regulating autophagosome formation are incompletely understood. Vac8 is required for autophagy and recruits the Atg1 kinase complex to the vacuole. Here we show that Vac8 acts as a central hub to nucleate the phagophore assembly site at the vacuolar membrane during selective autophagy. Vac8 directly recruits the cargo complex via the Atg11 scaffold. In addition, Vac8 recruits the phosphatidylinositol 3-kinase complex independently of autophagy. Cargo-dependent clustering and Vac8-dependent sequestering of these early autophagy factors, along with local Atg1 activation, promote phagophore assembly site assembly at the vacuole. Importantly, ectopic Vac8 redirects autophagosome formation to the nuclear membrane, indicating that the vacuolar membrane is not specifically required. We propose that multiple avidity-driven interactions drive the initiation and progression of selective autophagy. The molecular principles governing the initiation of autophagosome formation are not clearly understood. Here we show that the vacuolar protein Vac8 coordinates this process by promoting an avidity-driven assembly of several autophagy factors.
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39
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Schlarmann P, Ikeda A, Funato K. Membrane Contact Sites in Yeast: Control Hubs of Sphingolipid Homeostasis. MEMBRANES 2021; 11:971. [PMID: 34940472 PMCID: PMC8707754 DOI: 10.3390/membranes11120971] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/03/2021] [Accepted: 12/06/2021] [Indexed: 01/02/2023]
Abstract
Sphingolipids are the most diverse class of membrane lipids, in terms of their structure and function. Structurally simple sphingolipid precursors, such as ceramides, act as intracellular signaling molecules in various processes, including apoptosis, whereas mature and complex forms of sphingolipids are important structural components of the plasma membrane. Supplying complex sphingolipids to the plasma membrane, according to need, while keeping pro-apoptotic ceramides in check is an intricate task for the cell and requires mechanisms that tightly control sphingolipid synthesis, breakdown, and storage. As each of these processes takes place in different organelles, recent studies, using the budding yeast Saccharomyces cerevisiae, have investigated the role of membrane contact sites as hubs that integrate inter-organellar sphingolipid transport and regulation. In this review, we provide a detailed overview of the findings of these studies and put them into the context of established regulatory mechanisms of sphingolipid homeostasis. We have focused on the role of membrane contact sites in sphingolipid metabolism and ceramide transport, as well as the mechanisms that prevent toxic ceramide accumulation.
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Affiliation(s)
| | | | - Kouichi Funato
- Graduate School of Integrated Sciences for Life, Hiroshima University, Kagamiyama 1-4-4, Higashi-Hiroshima 739-8528, Japan; (P.S.); (A.I.)
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40
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Chandra S, Mannino PJ, Thaller DJ, Ader NR, King MC, Melia TJ, Lusk CP. Atg39 selectively captures inner nuclear membrane into lumenal vesicles for delivery to the autophagosome. J Cell Biol 2021; 220:e202103030. [PMID: 34714326 PMCID: PMC8575018 DOI: 10.1083/jcb.202103030] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 08/26/2021] [Accepted: 09/29/2021] [Indexed: 12/26/2022] Open
Abstract
Mechanisms that turn over components of the nucleus and inner nuclear membrane (INM) remain to be fully defined. We explore how components of the INM are selected by a cytosolic autophagy apparatus through a transmembrane nuclear envelope-localized cargo adaptor, Atg39. A split-GFP reporter showed that Atg39 localizes to the outer nuclear membrane (ONM) and thus targets the INM across the nuclear envelope lumen. Consistent with this, sequence elements that confer both nuclear envelope localization and a membrane remodeling activity are mapped to the Atg39 lumenal domain; these lumenal motifs are required for the autophagy-mediated degradation of integral INM proteins. Interestingly, correlative light and electron microscopy shows that the overexpression of Atg39 leads to the expansion of the ONM and the enclosure of a network of INM-derived vesicles in the nuclear envelope lumen. Thus, we propose an outside-in model of nucleophagy where INM is delivered into vesicles in the nuclear envelope lumen, which can be targeted by the autophagosome.
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Affiliation(s)
| | | | | | | | | | - Thomas J. Melia
- Department of Cell Biology, Yale School of Medicine, New Haven, CT
| | - C. Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, New Haven, CT
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41
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Ferreira JV, Carvalho P. Pex30-like proteins function as adaptors at distinct ER membrane contact sites. J Cell Biol 2021; 220:212563. [PMID: 34402813 PMCID: PMC8374871 DOI: 10.1083/jcb.202103176] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/19/2021] [Accepted: 07/20/2021] [Indexed: 12/20/2022] Open
Abstract
Membrane lipids and proteins synthesized in the ER are used for de novo assembly of organelles, such as lipid droplets and peroxisomes. After assembly, the growth of these organelles is supported by ER-derived lipids transferred at membrane contact sites (MCSs). How ER sites for organelle biogenesis and lipid transfer are established and regulated is unclear. Here, we investigate how the ER membrane protein Pex30 and its family members Pex28, Pex29, Pex31, and Pex32 target and function at multiple MCSs. We show that different Pex30 complexes function at distinct ER domains and MCSs. Pex30 targets ER–peroxisome MCSs when bound to Pex28 and Pex32, organizes the nuclear–vacuolar junction when bound to Pex29, and promotes the biogenesis of lipid droplets independently of other family members. Importantly, the reticulon homology domain (RHD) mediates the assembly of the various Pex30 complexes. Given the role of RHD in membrane shaping, our findings offer a mechanistic link between MCS and regulation of membrane curvature.
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Affiliation(s)
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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42
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Lei Y, Zhang X, Xu Q, Liu S, Li C, Jiang H, Lin H, Kong E, Liu J, Qi S, Li H, Xu W, Lu K. Autophagic elimination of ribosomes during spermiogenesis provides energy for flagellar motility. Dev Cell 2021; 56:2313-2328.e7. [PMID: 34428398 DOI: 10.1016/j.devcel.2021.07.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 05/17/2021] [Accepted: 07/23/2021] [Indexed: 02/05/2023]
Abstract
How autophagy initiation is regulated and what the functional significance of this regulation is are unknown. Here, we characterized the role of yeast Vac8 in autophagy initiation through recruitment of PIK3C3-C1 to the phagophore assembly site (PAS). This recruitment is dependent on the palmitoylation of Vac8 and on its middle ARM domains for binding PIK3C3-C1. Vac8-mediated anchoring of PIK3C3-C1 promotes PtdIns3P generation at the PAS and recruitment of the PtdIns3P binding protein Atg18-Atg2. The mouse homolog of Vac8, ARMC3, is conserved and functions in autophagy in mouse testes. Mice lacking ARMC3 have normal viability but show complete male infertility. Proteomic analysis indicated that the autophagic degradation of cytosolic ribosomes was blocked in ARMC3-deficient spermatids, which caused low energy levels of mitochondria and motionless flagella. These studies uncovered a function of Vac8/ARMC3 in PtdIns3-kinase anchoring at the PAS and its physical significance in mammalian spermatogenesis with a germ tissue-specific autophagic function.
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Affiliation(s)
- Yuqing Lei
- Department of Pathology, West China Second University Hospital, State Key Laboratory of Biotherapy, and Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education, Sichuan University, Chengdu 610041, China
| | - Xueguang Zhang
- Department of Obstetrics/Gynecology, Joint Laboratory of Reproductive Medicine (SCU-CUHK), Key Laboratory of Obstetric, Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, China
| | - Qingjia Xu
- Department of Neurology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Shiyan Liu
- Department of Neurology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Chunxia Li
- Department of Neurology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Hui Jiang
- Department of Urology, Peking University Third Hospital, Beijing 100191, China; Department of Reproductive Medicine Center, Peking University Third Hospital, Beijing 100191, China
| | - Haocheng Lin
- Department of Urology, Peking University Third Hospital, Beijing 100191, China; Department of Reproductive Medicine Center, Peking University Third Hospital, Beijing 100191, China
| | - Eryan Kong
- Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang 453003, China
| | - Jiaming Liu
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Shiqian Qi
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Huihui Li
- Department of Pathology, West China Second University Hospital, State Key Laboratory of Biotherapy, and Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education, Sichuan University, Chengdu 610041, China.
| | - Wenming Xu
- Department of Obstetrics/Gynecology, Joint Laboratory of Reproductive Medicine (SCU-CUHK), Key Laboratory of Obstetric, Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, China.
| | - Kefeng Lu
- Department of Neurology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
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43
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Keuenhof KS, Larsson Berglund L, Malmgren Hill S, Schneider KL, Widlund PO, Nyström T, Höög JL. Large organellar changes occur during mild heat shock in yeast. J Cell Sci 2021; 135:271806. [PMID: 34378783 PMCID: PMC8403982 DOI: 10.1242/jcs.258325] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 06/25/2021] [Indexed: 12/14/2022] Open
Abstract
When the temperature is increased, the heat-shock response is activated to protect the cellular environment. The transcriptomics and proteomics of this process are intensively studied, while information about how the cell responds structurally to heat stress is mostly lacking. Here, Saccharomyces cerevisiae were subjected to a mild continuous heat shock (38°C) and intermittently cryo-immobilised for electron microscopy. Through measuring changes in all distinguishable organelle numbers, sizes and morphologies in over 2100 electron micrographs, a major restructuring of the internal architecture of the cell during the progressive heat shock was revealed. The cell grew larger but most organelles within it expanded even more, shrinking the volume of the cytoplasm. Organelles responded to heat shock at different times, both in terms of size and number, and adaptations of the morphology of some organelles (such as the vacuole) were observed. Multivesicular bodies grew by almost 70%, indicating a previously unknown involvement in the heat-shock response. A previously undescribed electron-translucent structure accumulated close to the plasma membrane. This all-encompassing approach provides a detailed chronological progression of organelle adaptation throughout the cellular heat-stress response.
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Affiliation(s)
- Katharina S Keuenhof
- Department for Chemistry and Molecular Biology, University of Gothenburg, Gothenburg 41390, Sweden
| | - Lisa Larsson Berglund
- Department for Chemistry and Molecular Biology, University of Gothenburg, Gothenburg 41390, Sweden.,Department of Microbiology and Immunology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg 41390, Sweden
| | - Sandra Malmgren Hill
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg 41390, Sweden.,Department of Medical Genetics, Cambridge Institute for Medical Research, Cambridge CB2 0XY, UK
| | - Kara L Schneider
- Department of Microbiology and Immunology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg 41390, Sweden
| | - Per O Widlund
- Department of Microbiology and Immunology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg 41390, Sweden
| | - Thomas Nyström
- Department of Microbiology and Immunology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg 41390, Sweden
| | - Johanna L Höög
- Department for Chemistry and Molecular Biology, University of Gothenburg, Gothenburg 41390, Sweden
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44
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Rizzollo F, More S, Vangheluwe P, Agostinis P. The lysosome as a master regulator of iron metabolism. Trends Biochem Sci 2021; 46:960-975. [PMID: 34384657 DOI: 10.1016/j.tibs.2021.07.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/05/2021] [Accepted: 07/19/2021] [Indexed: 12/15/2022]
Abstract
Intracellular iron fulfills crucial cellular processes, including DNA synthesis and mitochondrial metabolism, but also mediates ferroptosis, a regulated form of cell death driven by lipid-based reactive oxygen species (ROS). Beyond their established role in degradation and recycling, lysosomes occupy a central position in iron homeostasis and integrate metabolic and cell death signals emanating from different subcellular sites. We discuss the central role of the lysosome in preserving iron homeostasis and provide an integrated outlook of the regulatory circuits coupling the lysosomal system to the control of iron trafficking, interorganellar crosstalk, and ferroptosis induction. We also discuss novel studies unraveling how deregulated lysosomal iron-handling functions contribute to cancer, neurodegeneration, and viral infection, and can be harnessed for therapeutic interventions.
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Affiliation(s)
- Francesca Rizzollo
- Laboratory of Cell Death and Research, Vlaams Instituut voor Biotechnologie (VIB)-Katholieke Universiteit (KU) Leuven Center for Cancer Biology, Leuven, Belgium; Laboratory of Cell Death and Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Sanket More
- Laboratory of Cell Death and Research, Vlaams Instituut voor Biotechnologie (VIB)-Katholieke Universiteit (KU) Leuven Center for Cancer Biology, Leuven, Belgium; Laboratory of Cell Death and Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Peter Vangheluwe
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.
| | - Patrizia Agostinis
- Laboratory of Cell Death and Research, Vlaams Instituut voor Biotechnologie (VIB)-Katholieke Universiteit (KU) Leuven Center for Cancer Biology, Leuven, Belgium; Laboratory of Cell Death and Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.
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45
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Rahman MA, Kumar R, Sanchez E, Nazarko TY. Lipid Droplets and Their Autophagic Turnover via the Raft-Like Vacuolar Microdomains. Int J Mol Sci 2021; 22:8144. [PMID: 34360917 PMCID: PMC8348048 DOI: 10.3390/ijms22158144] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/26/2021] [Accepted: 07/26/2021] [Indexed: 01/01/2023] Open
Abstract
Although once perceived as inert structures that merely serve for lipid storage, lipid droplets (LDs) have proven to be the dynamic organelles that hold many cellular functions. The LDs' basic structure of a hydrophobic core consisting of neutral lipids and enclosed in a phospholipid monolayer allows for quick lipid accessibility for intracellular energy and membrane production. Whereas formed at the peripheral and perinuclear endoplasmic reticulum, LDs are degraded either in the cytosol by lipolysis or in the vacuoles/lysosomes by autophagy. Autophagy is a regulated breakdown of dysfunctional, damaged, or surplus cellular components. The selective autophagy of LDs is called lipophagy. Here, we review LDs and their degradation by lipophagy in yeast, which proceeds via the micrometer-scale raft-like lipid domains in the vacuolar membrane. These vacuolar microdomains form during nutrient deprivation and facilitate internalization of LDs via the vacuolar membrane invagination and scission. The resultant intra-vacuolar autophagic bodies with LDs inside are broken down by vacuolar lipases and proteases. This type of lipophagy is called microlipophagy as it resembles microautophagy, the type of autophagy when substrates are sequestered right at the surface of a lytic compartment. Yeast microlipophagy via the raft-like vacuolar microdomains is a great model system to study the role of lipid domains in microautophagic pathways.
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Affiliation(s)
- Muhammad Arifur Rahman
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; (M.A.R.); (E.S.)
| | - Ravinder Kumar
- Department of Obstetrics, Gynecology and Reproductive Science, University of California, San Francisco, CA 94143, USA;
| | - Enrique Sanchez
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; (M.A.R.); (E.S.)
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Taras Y. Nazarko
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; (M.A.R.); (E.S.)
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46
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Molenaar MR, Yadav KK, Toulmay A, Wassenaar TA, Mari MC, Caillon L, Chorlay A, Lukmantara IE, Haaker MW, Wubbolts RW, Houweling M, Vaandrager AB, Prieur X, Reggiori F, Choudhary V, Yang H, Schneiter R, Thiam AR, Prinz WA, Helms JB. Retinyl esters form lipid droplets independently of triacylglycerol and seipin. J Cell Biol 2021; 220:212517. [PMID: 34323918 PMCID: PMC8327380 DOI: 10.1083/jcb.202011071] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 05/21/2021] [Accepted: 07/07/2021] [Indexed: 11/23/2022] Open
Abstract
Lipid droplets store neutral lipids, primarily triacylglycerol and steryl esters. Seipin plays a role in lipid droplet biogenesis and is thought to determine the site of lipid droplet biogenesis and the size of newly formed lipid droplets. Here we show a seipin-independent pathway of lipid droplet biogenesis. In silico and in vitro experiments reveal that retinyl esters have the intrinsic propensity to sequester and nucleate in lipid bilayers. Production of retinyl esters in mammalian and yeast cells that do not normally produce retinyl esters causes the formation of lipid droplets, even in a yeast strain that produces only retinyl esters and no other neutral lipids. Seipin does not determine the size or biogenesis site of lipid droplets composed of only retinyl esters or steryl esters. These findings indicate that the role of seipin in lipid droplet biogenesis depends on the type of neutral lipid stored in forming droplets.
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Affiliation(s)
- Martijn R Molenaar
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Kamlesh K Yadav
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Alexandre Toulmay
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Tsjerk A Wassenaar
- Groningen Biomolecular Sciences and Biotechnology Institute, Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Muriel C Mari
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Lucie Caillon
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, Sorbonne Université, Université Pierre-et-Marie-Curie Université Paris 06, Université Paris Diderot, Centre national de la recherche scientifique, Paris, France
| | - Aymeric Chorlay
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, Sorbonne Université, Université Pierre-et-Marie-Curie Université Paris 06, Université Paris Diderot, Centre national de la recherche scientifique, Paris, France
| | - Ivan E Lukmantara
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Maya W Haaker
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Richard W Wubbolts
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Martin Houweling
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Arie Bas Vaandrager
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Xavier Prieur
- Université de Nantes, Centre national de la recherche scientifique, Institut national de la santé et de la recherche médicale, l'institut du thorax, Nantes, France
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Vineet Choudhary
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Abdou Rachid Thiam
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, Sorbonne Université, Université Pierre-et-Marie-Curie Université Paris 06, Université Paris Diderot, Centre national de la recherche scientifique, Paris, France
| | - William A Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - J Bernd Helms
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
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47
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Hussain SS, Tran TM, Ware TB, Luse MA, Prevost CT, Ferguson AN, Kashatus JA, Hsu KL, Kashatus DF. RalA and PLD1 promote lipid droplet growth in response to nutrient withdrawal. Cell Rep 2021; 36:109451. [PMID: 34320341 PMCID: PMC8344381 DOI: 10.1016/j.celrep.2021.109451] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 06/04/2021] [Accepted: 07/02/2021] [Indexed: 01/22/2023] Open
Abstract
Lipid droplets (LDs) are dynamic organelles that undergo dynamic changes in response to changing cellular conditions. During nutrient depletion, LD numbers increase to protect cells against toxic fatty acids generated through autophagy and provide fuel for beta-oxidation. However, the precise mechanisms through which these changes are regulated have remained unclear. Here, we show that the small GTPase RalA acts downstream of autophagy to directly facilitate LD growth during nutrient depletion. Mechanistically, RalA performs this function through phospholipase D1 (PLD1), an enzyme that converts phosphatidylcholine (PC) to phosphatidic acid (PA) and that is recruited to lysosomes during nutrient stress in a RalA-dependent fashion. RalA inhibition prevents recruitment of the LD-associated protein perilipin 3, which is required for LD growth. Our data support a model in which RalA recruits PLD1 to lysosomes during nutrient deprivation to promote the localized production of PA and the recruitment of perilipin 3 to expanding LDs.
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Affiliation(s)
- Syed S Hussain
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Tuyet-Minh Tran
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Timothy B Ware
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Melissa A Luse
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Christopher T Prevost
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Ashley N Ferguson
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Jennifer A Kashatus
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Ku-Lung Hsu
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA; University of Virginia Cancer Center, University of Virginia Health System, Charlottesville, VA 22903, USA
| | - David F Kashatus
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA; University of Virginia Cancer Center, University of Virginia Health System, Charlottesville, VA 22903, USA.
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48
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Reza MH, Patkar R, Sanyal K. Vacuolar transporter Mnr2 safeguards organellar integrity in aged cells. Mol Microbiol 2021; 116:861-876. [PMID: 34165830 DOI: 10.1111/mmi.14776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 06/06/2021] [Accepted: 06/21/2021] [Indexed: 01/10/2023]
Abstract
Aging is associated with altered mitochondrial function, which is dependent on the magnesium (Mg+2 ) ion flux. The molecular mechanism underlying Mg+2 homeostasis, especially during aging has not been well understood. We previously demonstrated that the absence of a vacuolar ion transporter Mnr2 accelerates cell death in the older part of the colony in Magnaporthe oryzae presumably due to an altered Mg+2 homeostasis. Here, we show the localization of Mnr2 as dynamic puncta at the vacuolar membrane, especially in the older Magnaporthe cells. Such vacuolar Mnr2 puncta are often localized in close proximity with the filamentous mitochondria in the older cells. Further, we show loss of integrity of mitochondria and vacuoles in older mnr2∆ null cells. Remarkably, exogenously added Mg+2 restores the mitochondrial structure as well as improves the lifespan of mnr2∆ null cells. Taken together, we propose an ion transporter Mnr2-based Mg+2 homeostasis as a means in preserving mitochondrial and vacuolar integrity and function in older M. oryzae cells.
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Affiliation(s)
- Md Hashim Reza
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India.,Bharat Chattoo Genome Research Centre, Department of Microbiology & Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, India
| | - Rajesh Patkar
- Bharat Chattoo Genome Research Centre, Department of Microbiology & Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, India.,Department of Biosciences & Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Kaustuv Sanyal
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
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49
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He CW, Cui XF, Ma SJ, Xu Q, Ran YP, Chen WZ, Mu JX, Li H, Zhu J, Gong Q, Xie Z. Membrane recruitment of Atg8 by Hfl1 facilitates turnover of vacuolar membrane proteins in yeast cells approaching stationary phase. BMC Biol 2021; 19:117. [PMID: 34088313 PMCID: PMC8176713 DOI: 10.1186/s12915-021-01048-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 05/07/2021] [Indexed: 12/03/2022] Open
Abstract
Background The vacuole/lysosome is the final destination of autophagic pathways, but can also itself be degraded in whole or in part by selective macroautophagic or microautophagic processes. Diverse molecular mechanisms are involved in these processes, the characterization of which has lagged behind those of ATG-dependent macroautophagy and ESCRT-dependent endosomal multivesicular body pathways. Results Here we show that as yeast cells gradually exhaust available nutrients and approach stationary phase, multiple vacuolar integral membrane proteins with unrelated functions are degraded in the vacuolar lumen. This degradation depends on the ESCRT machinery, but does not strictly require ubiquitination of cargos or trafficking of cargos out of the vacuole. It is also temporally and mechanistically distinct from NPC-dependent microlipophagy. The turnover is facilitated by Atg8, an exception among autophagy proteins, and an Atg8-interacting vacuolar membrane protein, Hfl1. Lack of Atg8 or Hfl1 led to the accumulation of enlarged lumenal membrane structures in the vacuole. We further show that a key function of Hfl1 is the membrane recruitment of Atg8. In the presence of Hfl1, lipidation of Atg8 is not required for efficient cargo turnover. The need for Hfl1 can be partially bypassed by blocking Atg8 delipidation. Conclusions Our data reveal a vacuolar membrane protein degradation process with a unique dependence on vacuole-associated Atg8 downstream of ESCRTs, and we identify a specific role of Hfl1, a protein conserved from yeast to plants and animals, in membrane targeting of Atg8. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01048-7.
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Affiliation(s)
- Cheng-Wen He
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xue-Fei Cui
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Shao-Jie Ma
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.,Present address: Department of Genetics, Yale School of Medicine, New Haven, CT, 06510, USA
| | - Qin Xu
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yan-Peng Ran
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Wei-Zhi Chen
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jun-Xi Mu
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Hui Li
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jing Zhu
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Qingqiu Gong
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zhiping Xie
- State Key Laboratory of Microbial Metabolism and Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
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50
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Fausten RM, Bohnert M. A move in response to starvation. eLife 2021; 10:69680. [PMID: 34061033 PMCID: PMC8169105 DOI: 10.7554/elife.69680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 05/25/2021] [Indexed: 11/13/2022] Open
Abstract
When a yeast cell runs out of fuel, it can increase the flux through a central metabolic pathway by simply changing the location of an enzyme.
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Affiliation(s)
- Rebecca Martina Fausten
- Institute of Cell Dynamics and Imaging, and the Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Maria Bohnert
- Institute of Cell Dynamics and Imaging, and the Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
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