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Xu J, Huang X. Lipid Metabolism at Membrane Contacts: Dynamics and Functions Beyond Lipid Homeostasis. Front Cell Dev Biol 2020; 8:615856. [PMID: 33425923 PMCID: PMC7786193 DOI: 10.3389/fcell.2020.615856] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 11/30/2020] [Indexed: 01/12/2023] Open
Abstract
Membrane contact sites (MCSs), regions where the membranes of two organelles are closely apposed, play critical roles in inter-organelle communication, such as lipid trafficking, intracellular signaling, and organelle biogenesis and division. First identified as “fraction X” in the early 90s, MCSs are now widely recognized to facilitate local lipid synthesis and inter-organelle lipid transfer, which are important for maintaining cellular lipid homeostasis. In this review, we discuss lipid metabolism and related cellular and physiological functions in MCSs. We start with the characteristics of lipid synthesis and breakdown at MCSs. Then we focus on proteins involved in lipid synthesis and turnover at these sites. Lastly, we summarize the cellular function of lipid metabolism at MCSs beyond mere lipid homeostasis, including the physiological meaning and relevance of MCSs regarding systemic lipid metabolism. This article is part of an article collection entitled: Coupling and Uncoupling: Dynamic Control of Membrane Contacts.
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Affiliation(s)
- Jiesi Xu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China.,College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
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52
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Peroxisomes form intralumenal vesicles with roles in fatty acid catabolism and protein compartmentalization in Arabidopsis. Nat Commun 2020; 11:6221. [PMID: 33277488 PMCID: PMC7718247 DOI: 10.1038/s41467-020-20099-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 11/11/2020] [Indexed: 12/12/2022] Open
Abstract
Peroxisomes are vital organelles that compartmentalize critical metabolic reactions, such as the breakdown of fats, in eukaryotic cells. Although peroxisomes typically are considered to consist of a single membrane enclosing a protein lumen, more complex peroxisomal membrane structure has occasionally been observed in yeast, mammals, and plants. However, technical challenges have limited the recognition and understanding of this complexity. Here we exploit the unusually large size of Arabidopsis peroxisomes to demonstrate that peroxisomes have extensive internal membranes. These internal vesicles accumulate over time, use ESCRT (endosomal sorting complexes required for transport) machinery for formation, and appear to derive from the outer peroxisomal membrane. Moreover, these vesicles can harbor distinct proteins and do not form normally when fatty acid β-oxidation, a core function of peroxisomes, is impaired. Our findings suggest a mechanism for lipid mobilization that circumvents challenges in processing insoluble metabolites. This revision of the classical view of peroxisomes as single-membrane organelles has implications for all aspects of peroxisome biogenesis and function and may help address fundamental questions in peroxisome evolution. Peroxisomes are organelles compartmentalising metabolic reactions such as the breakdown of fats, and are commonly thought of as single membrane-bound compartments. Here the authors show that Arabidopsis peroxisomes contain extensive internal vesicles that form from the bounding membrane in an ESCRT-dependent process.
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Covill-Cooke C, Toncheva VS, Kittler JT. Regulation of peroxisomal trafficking and distribution. Cell Mol Life Sci 2020; 78:1929-1941. [PMID: 33141311 PMCID: PMC7966214 DOI: 10.1007/s00018-020-03687-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/02/2020] [Accepted: 10/19/2020] [Indexed: 12/18/2022]
Abstract
Peroxisomes are organelles that perform a wide range of essential metabolic processes. To ensure that peroxisomes are optimally positioned in the cell, they must be transported by both long- and short-range trafficking events in response to cellular needs. Here, we review our current understanding of the mechanisms by which the cytoskeleton and organelle contact sites alter peroxisomal distribution. Though the focus of the review is peroxisomal transport in mammalian cells, findings from flies and fungi are used for comparison and to inform the gaps in our understanding. Attention is given to the apparent overlap in regulatory mechanisms for mitochondrial and peroxisomal trafficking, along with the recently discovered role of the mitochondrial Rho-GTPases, Miro, in peroxisomal dynamics. Moreover, we outline and discuss the known pathological and pharmacological conditions that perturb peroxisomal positioning. We conclude by highlighting several gaps in our current knowledge and suggest future directions that require attention.
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Affiliation(s)
| | - Viktoriya S Toncheva
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
| | - Josef T Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK.
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Silva BSC, DiGiovanni L, Kumar R, Carmichael RE, Kim PK, Schrader M. Maintaining social contacts: The physiological relevance of organelle interactions. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118800. [PMID: 32712071 PMCID: PMC7377706 DOI: 10.1016/j.bbamcr.2020.118800] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/12/2020] [Accepted: 07/19/2020] [Indexed: 02/07/2023]
Abstract
Membrane-bound organelles in eukaryotic cells form an interactive network to coordinate and facilitate cellular functions. The formation of close contacts, termed "membrane contact sites" (MCSs), represents an intriguing strategy for organelle interaction and coordinated interplay. Emerging research is rapidly revealing new details of MCSs. They represent ubiquitous and diverse structures, which are important for many aspects of cell physiology and homeostasis. Here, we provide a comprehensive overview of the physiological relevance of organelle contacts. We focus on mitochondria, peroxisomes, the Golgi complex and the plasma membrane, and discuss the most recent findings on their interactions with other subcellular organelles and their multiple functions, including membrane contacts with the ER, lipid droplets and the endosomal/lysosomal compartment.
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Affiliation(s)
- Beatriz S C Silva
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK
| | - Laura DiGiovanni
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Rechal Kumar
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK
| | - Ruth E Carmichael
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK.
| | - Peter K Kim
- Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
| | - Michael Schrader
- College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter EX4 4QD, Devon, UK.
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Chen C, Li J, Qin X, Wang W. Peroxisomal Membrane Contact Sites in Mammalian Cells. Front Cell Dev Biol 2020; 8:512. [PMID: 32714927 PMCID: PMC7344225 DOI: 10.3389/fcell.2020.00512] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 05/28/2020] [Indexed: 12/11/2022] Open
Abstract
Peroxisomes participate in essential cellular metabolic processes, such as oxidation of fatty acids (FAs) and maintenance of reactive oxygen species (ROS) homeostasis. Peroxisomes must communicate with surrounding organelles to exchange information and metabolites. The formation of membrane contact sites (MCSs), where protein-protein or protein-lipid complexes tether the opposing membranes of two organelles, represents an essential means of organelle crosstalk. Peroxisomal MCS (PO-MCS) studies are emerging but are still in the early stages. In this review, we summarize the identified PO-MCSs with the ER, mitochondria, lipid droplets, and lysosomes in mammalian cells and discuss their tethering mechanisms and physiological roles. We also highlight several features of PO-MCSs that may help future studies.
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Affiliation(s)
- Chao Chen
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing Li
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xuhui Qin
- Department of Human Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Wang
- Department of Human Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Hofer P, Taschler U, Schreiber R, Kotzbeck P, Schoiswohl G. The Lipolysome-A Highly Complex and Dynamic Protein Network Orchestrating Cytoplasmic Triacylglycerol Degradation. Metabolites 2020; 10:E147. [PMID: 32290093 PMCID: PMC7240967 DOI: 10.3390/metabo10040147] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/03/2020] [Accepted: 04/08/2020] [Indexed: 12/25/2022] Open
Abstract
The catabolism of intracellular triacylglycerols (TAGs) involves the activity of cytoplasmic and lysosomal enzymes. Cytoplasmic TAG hydrolysis, commonly termed lipolysis, is catalyzed by the sequential action of three major hydrolases, namely adipose triglyceride lipase, hormone-sensitive lipase, and monoacylglycerol lipase. All three enzymes interact with numerous protein binding partners that modulate their activity, cellular localization, or stability. Deficiencies of these auxiliary proteins can lead to derangements in neutral lipid metabolism and energy homeostasis. In this review, we summarize the composition and the dynamics of the complex lipolytic machinery we like to call "lipolysome".
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Affiliation(s)
- Peter Hofer
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Ulrike Taschler
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Petra Kotzbeck
- Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria;
| | - Gabriele Schoiswohl
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
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Abe Y, Tamura S, Honsho M, Fujiki Y. A Mouse Model System to Study Peroxisomal Roles in Neurodegeneration of Peroxisome Biogenesis Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1299:119-143. [PMID: 33417212 DOI: 10.1007/978-3-030-60204-8_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Fourteen PEX genes are currently identified as genes responsible for peroxisome biogenesis disorders (PBDs). Patients with PBDs manifest as neurodegenerative symptoms such as neuronal migration defect and malformation of the cerebellum. To address molecular mechanisms underlying the pathogenesis of PBDs, mouse models for the PBDs have been generated by targeted disruption of Pex genes. Pathological phenotypes and metabolic abnormalities in Pex-knockout mice well resemble those of the patients with PBDs. The mice with tissue- or cell type-specific inactivation of Pex genes have also been established by using a Cre-loxP system. The genetically modified mice reveal that pathological phenotypes of PBDs are mediated by interorgan and intercellular communications. Despite the illustrations of detailed pathological phenotypes in the mutant mice, mechanistic insights into pathogenesis of PBDs are still underway. In this chapter, we overview the phenotypes of Pex-inactivated mice and the current understanding of the pathogenesis underlying PBDs.
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Affiliation(s)
- Yuichi Abe
- Faculty of Arts and Science, Kyushu University, Fukuoka, Japan
| | | | | | - Yukio Fujiki
- Institute of Rheological Functions of Food, Fukuoka, Japan. .,Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
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