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Fukuda T, Furukawa K, Maruyama T, Yamashita SI, Noshiro D, Song C, Ogasawara Y, Okuyama K, Alam JM, Hayatsu M, Saigusa T, Inoue K, Ikeda K, Takai A, Chen L, Lahiri V, Okada Y, Shibata S, Murata K, Klionsky DJ, Noda NN, Kanki T. The mitochondrial intermembrane space protein mitofissin drives mitochondrial fission required for mitophagy. Mol Cell 2023; 83:2045-2058.e9. [PMID: 37192628 PMCID: PMC10330776 DOI: 10.1016/j.molcel.2023.04.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 01/30/2023] [Accepted: 04/21/2023] [Indexed: 05/18/2023]
Abstract
Mitophagy plays an important role in mitochondrial homeostasis by selective degradation of mitochondria. During mitophagy, mitochondria should be fragmented to allow engulfment within autophagosomes, whose capacity is exceeded by the typical mitochondria mass. However, the known mitochondrial fission factors, dynamin-related proteins Dnm1 in yeasts and DNM1L/Drp1 in mammals, are dispensable for mitophagy. Here, we identify Atg44 as a mitochondrial fission factor that is essential for mitophagy in yeasts, and we therefore term Atg44 and its orthologous proteins mitofissin. In mitofissin-deficient cells, a part of the mitochondria is recognized by the mitophagy machinery as cargo but cannot be enwrapped by the autophagosome precursor, the phagophore, due to a lack of mitochondrial fission. Furthermore, we show that mitofissin directly binds to lipid membranes and brings about lipid membrane fragility to facilitate membrane fission. Taken together, we propose that mitofissin acts directly on lipid membranes to drive mitochondrial fission required for mitophagy.
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Affiliation(s)
- Tomoyuki Fukuda
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | - Kentaro Furukawa
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | - Tatsuro Maruyama
- Institute of Microbial Chemistry (BIKAKEN), Shinagawa-ku, Tokyo 141-0021, Japan
| | - Shun-Ichi Yamashita
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | - Daisuke Noshiro
- Institute of Microbial Chemistry (BIKAKEN), Shinagawa-ku, Tokyo 141-0021, Japan; Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido 060-0815, Japan
| | - Chihong Song
- National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS), Okazaki, Aichi 444-8585, Japan; Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki, Aichi 444-8585, Japan
| | - Yuta Ogasawara
- Institute of Microbial Chemistry (BIKAKEN), Shinagawa-ku, Tokyo 141-0021, Japan; Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido 060-0815, Japan
| | - Kentaro Okuyama
- Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | - Jahangir Md Alam
- Institute of Microbial Chemistry (BIKAKEN), Shinagawa-ku, Tokyo 141-0021, Japan
| | - Manabu Hayatsu
- Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | - Tetsu Saigusa
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | - Keiichi Inoue
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | - Kazuho Ikeda
- Department of Cell Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; Laboratory for Cell Polarity Regulation, RIKEN Center for Biosystems Dynamics Research (BDR), Osaka 565-0874, Japan
| | - Akira Takai
- Department of Cell Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; Laboratory for Cell Polarity Regulation, RIKEN Center for Biosystems Dynamics Research (BDR), Osaka 565-0874, Japan
| | - Lin Chen
- National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS), Okazaki, Aichi 444-8585, Japan; Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki, Aichi 444-8585, Japan
| | - Vikramjit Lahiri
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yasushi Okada
- Department of Cell Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; Laboratory for Cell Polarity Regulation, RIKEN Center for Biosystems Dynamics Research (BDR), Osaka 565-0874, Japan; Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan; Universal Biology Institute (UBI) and International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, Tokyo 113-0033, Japan
| | - Shinsuke Shibata
- Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan
| | - Kazuyoshi Murata
- National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS), Okazaki, Aichi 444-8585, Japan; Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki, Aichi 444-8585, Japan
| | - Daniel J Klionsky
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Nobuo N Noda
- Institute of Microbial Chemistry (BIKAKEN), Shinagawa-ku, Tokyo 141-0021, Japan; Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido 060-0815, Japan.
| | - Tomotake Kanki
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan.
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Johkura K, Usuda N, Tanaka Y, Fukasawa M, Murata K, Noda T, Ohno N. OUP accepted manuscript. Microscopy (Oxf) 2022; 71:262-270. [PMID: 35535544 PMCID: PMC9535788 DOI: 10.1093/jmicro/dfac024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 04/25/2022] [Accepted: 06/06/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Kohei Johkura
- Department of Histology and Embryology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan
| | - Nobuteru Usuda
- *To whom correspondence should be addressed. E-mail: (N.U.); (N.O.)
| | - Yoshihiro Tanaka
- Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Motoaki Fukasawa
- Department of Biomedical Molecular Sciences (Anatomy II), Fujita Health University School of Medicine, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan
| | - Kazuyoshi Murata
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Toru Noda
- Department of Occupational Therapy (Anatomy), Biwako Professional University of Rehabilitation, 967 Kitasakacho, Higashiomi, Shiga 527-0145, Japan
- Department of Cell Biology and Anatomy, Fujita Health University School of Medicine, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan
| | - Nobuhiko Ohno
- *To whom correspondence should be addressed. E-mail: (N.U.); (N.O.)
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Bruno SR, Anathy V. Lung epithelial endoplasmic reticulum and mitochondrial 3D ultrastructure: a new frontier in lung diseases. Histochem Cell Biol 2021; 155:291-300. [PMID: 33598824 PMCID: PMC7889473 DOI: 10.1007/s00418-020-01950-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2020] [Indexed: 12/15/2022]
Abstract
It has long been appreciated that the endoplasmic reticulum (ER) and mitochondria, organelles important for regular cell function and survival, also play key roles in pathogenesis of various lung diseases, including asthma, fibrosis, and infections. Alterations in processes regulated within these organelles, including but not limited to protein folding in the ER and oxidative phosphorylation in the mitochondria, are important in disease pathogenesis. In recent years it has also become increasingly apparent that organelle structure dictates function. It is now clear that organelles must maintain precise organization and localization for proper function. Newer microscopy capabilities have allowed the scientific community to reveal, via 3D imaging, that the structure of these organelles and their interactions with each other are a main component of regulating function and, therefore, effects on the disease state. In this review, we will examine how 3D imaging through techniques could allow advancements in knowledge of how the ER and mitochondria function and the roles they may play in lung epithelia in progression of lung disease.
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Affiliation(s)
- Sierra R Bruno
- Department of Pathology and Laboratory Medicine, University of Vermont, Larner College of Medicine, 149 Beaumont Ave, Burlington, VT, 05405, USA
| | - Vikas Anathy
- Department of Pathology and Laboratory Medicine, University of Vermont, Larner College of Medicine, 149 Beaumont Ave, Burlington, VT, 05405, USA.
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Xu X, Zhu L, Xue K, Liu J, Wang J, Wang G, Gu J, Zhang Y, Li X. Ultrastructural studies of the neurovascular unit reveal enhanced endothelial transcytosis in hyperglycemia‐enhanced hemorrhagic transformation after stroke. CNS Neurosci Ther 2021. [PMCID: PMC7804894 DOI: 10.1111/cns.13571] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Aims Pre‐existing hyperglycemia (HG) aggravates the breakdown of blood–brain barrier (BBB) and increases the risk of hemorrhagic transformation (HT) after acute ischemic stroke in both animal models and patients. To date, HG‐induced ultrastructural changes of brain microvascular endothelial cells (BMECs) and the mechanisms underlying HG‐enhanced HT after ischemic stroke are poorly understood. Methods We used a mouse model of mild brain ischemia/reperfusion to investigate HG‐induced ultrastructural changes of BMECs that contribute to the impairment of BBB integrity after stroke. Adult male mice received systemic glucose administration 15 min before middle cerebral artery occlusion (MCAO) for 20 min. Ultrastructural characteristics of BMECs were evaluated using two‐dimensional and three‐dimensional electron microscopy and quantitatively analyzed. Results Mice with acute HG had exacerbated BBB disruption and larger brain infarcts compared to mice with normoglycemia (NG) after MCAO and 4 h of reperfusion, as assessed by brain extravasation of the Evans blue dye and microtubule‐associated protein 2 immunostaining. Electron microscopy further revealed that HG mice had more endothelial vesicles in the striatal neurovascular unit than NG mice, which may account for their deterioration of BBB impairment. In contrast with enhanced endothelial transcytosis, paracellular tight junction ultrastructure was not disrupted after this mild ischemia/reperfusion insult or altered upon HG. Consistent with the observed increase of endothelial vesicles, transcytosis‐related proteins caveolin‐1, clathrin, and hypoxia‐inducible factor (HIF)‐1α were upregulated by HG after MCAO and reperfusion. Conclusion Our study provides solid structural evidence to understand the role of endothelial transcytosis in HG‐elicited BBB hyperpermeability. Enhanced transcytosis occurs prior to the physical breakdown of BMECs and is a promising therapeutic target to preserve BBB integrity.
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Affiliation(s)
- Xiaomin Xu
- Institute of Special Environmental Medicine and Department of Neurology of Affiliated Hospital Co‐innovation Center of Neuroregeneration Nantong University Nantong China
- Qidong Women's and Children's Health Qidong China
| | - Liuqi Zhu
- Institute of Special Environmental Medicine and Department of Neurology of Affiliated Hospital Co‐innovation Center of Neuroregeneration Nantong University Nantong China
| | - Ke Xue
- Institute of Special Environmental Medicine and Department of Neurology of Affiliated Hospital Co‐innovation Center of Neuroregeneration Nantong University Nantong China
| | - Jiayi Liu
- Institute of Special Environmental Medicine and Department of Neurology of Affiliated Hospital Co‐innovation Center of Neuroregeneration Nantong University Nantong China
| | - Jian Wang
- Institute of Special Environmental Medicine and Department of Neurology of Affiliated Hospital Co‐innovation Center of Neuroregeneration Nantong University Nantong China
| | - Guohua Wang
- Institute of Special Environmental Medicine and Department of Neurology of Affiliated Hospital Co‐innovation Center of Neuroregeneration Nantong University Nantong China
| | - Jin‐hua Gu
- Institute of Special Environmental Medicine and Department of Neurology of Affiliated Hospital Co‐innovation Center of Neuroregeneration Nantong University Nantong China
| | - Yunfeng Zhang
- Institute of Special Environmental Medicine and Department of Neurology of Affiliated Hospital Co‐innovation Center of Neuroregeneration Nantong University Nantong China
| | - Xia Li
- Institute of Special Environmental Medicine and Department of Neurology of Affiliated Hospital Co‐innovation Center of Neuroregeneration Nantong University Nantong China
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Escobar-Henriques M, Anton V. Mitochondrial Surveillance by Cdc48/p97: MAD vs. Membrane Fusion. Int J Mol Sci 2020; 21:E6841. [PMID: 32961852 PMCID: PMC7555132 DOI: 10.3390/ijms21186841] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 09/07/2020] [Accepted: 09/08/2020] [Indexed: 11/16/2022] Open
Abstract
Cdc48/p97 is a ring-shaped, ATP-driven hexameric motor, essential for cellular viability. It specifically unfolds and extracts ubiquitylated proteins from membranes or protein complexes, mostly targeting them for proteolytic degradation by the proteasome. Cdc48/p97 is involved in a multitude of cellular processes, reaching from cell cycle regulation to signal transduction, also participating in growth or death decisions. The role of Cdc48/p97 in endoplasmic reticulum-associated degradation (ERAD), where it extracts proteins targeted for degradation from the ER membrane, has been extensively described. Here, we present the roles of Cdc48/p97 in mitochondrial regulation. We discuss mitochondrial quality control surveillance by Cdc48/p97 in mitochondrial-associated degradation (MAD), highlighting the potential pathologic significance thereof. Furthermore, we present the current knowledge of how Cdc48/p97 regulates mitofusin activity in outer membrane fusion and how this may impact on neurodegeneration.
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Affiliation(s)
- Mafalda Escobar-Henriques
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC), University of Cologne, Joseph-Stelzmann-Straße 26, 50931 Cologne, Germany;
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Nahar S, Chowdhury A, Ogura T, Esaki M. A AAA ATPase Cdc48 with a cofactor Ubx2 facilitates ubiquitylation of a mitochondrial fusion-promoting factor Fzo1 for proteasomal degradation. J Biochem 2019; 167:279-286. [DOI: 10.1093/jb/mvz104] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 11/19/2019] [Indexed: 11/14/2022] Open
Abstract
AbstractDynamic functionality of mitochondria is maintained by continual fusion and fission events. A mitochondrial outer membrane protein Fzo1 plays a pivotal role upon mitochondrial fusion by homo-oligomerization to tether fusing mitochondria. Fzo1 is tightly regulated by ubiquitylations and the ubiquitin-responsible AAA protein Cdc48. Here, we show that a Cdc48 cofactor Ubx2 facilitates Fzo1 turnover. The Cdc48-Ubx2 complex has been shown to facilitate degradation of ubiquitylated proteins stacked at the protein translocation complex in the mitochondrial outer membrane by releasing them from the translocase. By contrast, in the degradation process of Fzo1, the Cdc48-Ubx2 complex appears to facilitate the degradation-signalling ubiquitylation of the substrate itself. In addition, the Cdc48-Ubx2 complex interacts with Ubp2, a deubiquitylase reversing the degradation-signalling ubiquitylation of Fzo1. These results suggest that the Cdc48-Ubx2 complex regulates Fzo1 turnover by modulating ubiquitylation status of the substrate.
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Affiliation(s)
- Sabiqun Nahar
- Department of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811, Japan
- Program for Leading Graduate Schools “HIGO Program”, Kumamoto University, Kumamoto 860-8556, Japan
| | - Abhijit Chowdhury
- Department of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811, Japan
- Program for Leading Graduate Schools “HIGO Program”, Kumamoto University, Kumamoto 860-8556, Japan
| | - Teru Ogura
- Department of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811, Japan
- Program for Leading Graduate Schools “HIGO Program”, Kumamoto University, Kumamoto 860-8556, Japan
| | - Masatoshi Esaki
- Department of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811, Japan
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Kaji T, Song C, Murata K, Nonaka S, Ogawa K, Kondo Y, Ohtsuka S, Palmer AR. Evolutionary transformation of mouthparts from particle-feeding to piercing carnivory in Viper copepods: Review and 3D analyses of a key innovation using advanced imaging techniques. Front Zool 2019; 16:35. [PMID: 31440302 PMCID: PMC6704645 DOI: 10.1186/s12983-019-0308-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Accepted: 03/26/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Novel feeding adaptations often facilitate adaptive radiation and diversification. But the evolutionary origins of such feeding adaptations can be puzzling if they require concordant change in multiple component parts. Pelagic, heterorhabdid copepods (Calanoida) exhibit diverse feeding behaviors that range from simple particle feeding to a highly specialized form of carnivory involving piercing mouthparts that likely inject venom. We review the evolutionary history of heterorhabdid copepods and add new high-resolution, 3D anatomical analyses of the muscular system, glands and gland openings associated with this remarkable evolutionary transformation. RESULTS We examined four heterorhabdid copepods with different feeding modes: one primitive particle-feeder (Disseta palumbii), one derived and specialized carnivore (Heterorhabdus subspinifrons), and two intermediate taxa (Mesorhabdus gracilis and Heterostylites longicornis). We used two advanced, high-resolution microscopic techniques - serial block-face scanning electron microscopy and two-photon excitation microscopy - to visualize mouthpart form and internal anatomy at unprecedented nanometer resolution. Interactive 3D graphical visualizations allowed putative homologues of muscles and gland cells to be identified with confidence and traced across the evolutionary transformation from particle feeding to piercing carnivory. Notable changes included: a) addition of new gland cells, b) enlargement of some (venom producing?) glands, c) repositioning of gland openings associated with hollow piercing fangs on the mandibles, d) repurposing of some mandibular-muscle function to include gland-squeezing, and e) addition of new muscles that may aid venom injection exclusively in the most specialized piercing species. In addition, live video recording of all four species revealed mandibular blade movements coupled to cyclic contraction of some muscles connected to the esophagus. These behavioral and 3D morphological observations revealed a novel injection system in H. subspinifrons associated with piercing (envenomating?) carnivory. CONCLUSIONS Collectively, these results suggest that subtle changes in mandibular tooth form, and muscle and gland form and location, facilitated the evolution of a novel, piercing mode of feeding that accelerated diversification of the genus Heterorhabdus. They also highlight the value of interactive 3D animations for understanding evolutionary transformations of complex, multicomponent morphological systems.
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Affiliation(s)
- Tomonari Kaji
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada
- Allgemeine & Spezielle Zoologie, Institut fur Biowissenschaften, Universität Rostock, 18055 Rostock, Germany
| | - Chihong Song
- National Institute for Physiological Sciences, Okazaki, Aichi 444-8585 Japan
| | - Kazuyoshi Murata
- National Institute for Physiological Sciences, Okazaki, Aichi 444-8585 Japan
| | - Shigenori Nonaka
- National Institute for Basic Biology, Okazaki, Aichi 444-8585 Japan
| | - Kota Ogawa
- Biosystematics Laboratory, Faculty of Social and Cultural Studies, Kyushu University, Okazaki, Hiroshima Japan
| | - Yusuke Kondo
- Setouchi Field Science Center, Graduate School of Integrated Sciences for Life, Hiroshima University, 5-8-1 Minato-machi, Takehara, Hiroshima 725-0024 Japan
| | - Susumu Ohtsuka
- Setouchi Field Science Center, Graduate School of Integrated Sciences for Life, Hiroshima University, 5-8-1 Minato-machi, Takehara, Hiroshima 725-0024 Japan
| | - A. Richard Palmer
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada
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Subcellular connectomic analyses of energy networks in striated muscle. Nat Commun 2018; 9:5111. [PMID: 30504768 PMCID: PMC6269443 DOI: 10.1038/s41467-018-07676-y] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 11/12/2018] [Indexed: 01/12/2023] Open
Abstract
Mapping biological circuit connectivity has revolutionized our understanding of structure-function relationships. Although connectomic analyses have primarily focused on neural systems, electrical connectivity within muscle mitochondrial networks was recently demonstrated to provide a rapid mechanism for cellular energy distribution. However, tools to evaluate organelle connectivity with high spatial fidelity within single cells are currently lacking. Here, we developed a framework to quantitatively assess mitochondrial network connectivity and interactions with cellular sites of energy storage, utilization, and calcium cycling in cardiac, oxidative, and glycolytic muscle. We demonstrate that mitochondrial network configuration, individual mitochondrial size and shape, and the junctions connecting mitochondria within each network are consistent with the differing contraction demands of each muscle type. Moreover, mitochondria-lipid droplet interaction analyses suggest that individual mitochondria within networks may play specialized roles regarding energy distribution and calcium cycling within the cell and reveal the power of connectomic analyses of organelle interactions within single cells.
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Chowdhury A, Ogura T, Esaki M. Two Cdc48 cofactors Ubp3 and Ubx2 regulate mitochondrial morphology and protein turnover. J Biochem 2018; 164:349-358. [PMID: 29924334 DOI: 10.1093/jb/mvy057] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/13/2018] [Indexed: 12/22/2022] Open
Abstract
Mitochondria continuously undergo coordinated fusion and fission during vegetative growth to keep their homogeneity and to remove damaged components. A cytosolic AAA ATPase, Cdc48, is implicated in the mitochondrial fusion event and turnover of a fusion-responsible GTPase in the mitochondrial outer membrane, Fzo1, suggesting a possible linkage of mitochondrial fusion and Fzo1 turnover. Here, we identified two Cdc48 cofactor proteins, Ubp3 and Ubx2, involving mitochondria regulation. In the absence of UBP3, mitochondrial fragmentation and aggregation were observed. The turnover of Fzo1 was not affected in Δubp3, but instead a deubiquitylase Ubp12 that removes fusion-required polyubiquitin chains from Fzo1 was stabilized. Thus, excess amount of Ubp12 may lead to mitochondrial fragmentation by removal of fusion-competent ubiquitylated Fzo1. In contrast, deletion of UBX2 perturbed disassembly of Fzo1 oligomers and their degradation without alteration of mitochondrial morphology. The UBX2 deletion led to destabilization of Ubp2 that negatively regulates Fzo1 turnover by removing degradation-signalling polyubiquitin chains, suggesting that Ubx2 would directly facilitate Fzo1 degradation. These results indicated that two different Cdc48-cofactor complexes independently regulate mitochondrial fusion and Fzo1 turnover.
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Affiliation(s)
- Abhijit Chowdhury
- Department of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Honjo 2-2-1, Chuo-ku, Kumamoto, Japan.,Program for Leading Graduate Schools "HIGO Program", Kumamoto University, Honjo 1-1-1, Chuo-ku, Kumamoto, Japan
| | - Teru Ogura
- Department of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Honjo 2-2-1, Chuo-ku, Kumamoto, Japan.,Program for Leading Graduate Schools "HIGO Program", Kumamoto University, Honjo 1-1-1, Chuo-ku, Kumamoto, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi-shi, Saitama, Japan
| | - Masatoshi Esaki
- Department of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Honjo 2-2-1, Chuo-ku, Kumamoto, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi-shi, Saitama, Japan
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Nakao A, Miyazaki N, Ohira K, Hagihara H, Takagi T, Usuda N, Ishii S, Murata K, Miyakawa T. Immature morphological properties in subcellular-scale structures in the dentate gyrus of Schnurri-2 knockout mice: a model for schizophrenia and intellectual disability. Mol Brain 2017; 10:60. [PMID: 29233179 PMCID: PMC5727961 DOI: 10.1186/s13041-017-0339-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 11/19/2017] [Indexed: 01/18/2023] Open
Abstract
Accumulating evidence suggests that subcellular-scale structures such as dendritic spine and mitochondria may be involved in the pathogenesis/pathophysiology of schizophrenia and intellectual disability. Previously, we proposed mice lacking Schnurri-2 (Shn2; also called major histocompatibility complex [MHC]-binding protein 2 [MBP-2], or human immunodeficiency virus type I enhancer binding protein 2 [HIVEP2]) as a schizophrenia and intellectual disability model with mild chronic inflammation. In the mutants’ brains, there are increases in C4b and C1q genes, which are considered to mediate synapse elimination during postnatal development. However, morphological properties of subcellular-scale structures such as dendritic spine in Shn2 knockout (KO) mice remain unknown. In this study, we conducted three-dimensional morphological analyses in subcellular-scale structures in dentate gyrus granule cells of Shn2 KO mice by serial block-face scanning electron microscopy. Shn2 KO mice showed immature dendritic spine morphology characterized by increases in spine length and decreases in spine diameter. There was a non-significant tendency toward decrease in spine density of Shn2 KO mice over wild-type mice, and spine volume was indistinguishable between genotypes. Shn2 KO mice exhibited a significant reduction in GluR1 expression and a nominally significant decrease in SV2 expression, while PSD95 expression had a non-significant tendency to decrease in Shn2 KO mice. There were significant decreases in dendrite diameter, nuclear volume, and the number of constricted mitochondria in the mutants. Additionally, neuronal density was elevated in Shn2 KO mice. These results suggest that Shn2 KO mice serve as a unique tool for investigating morphological abnormalities of subcellular-scale structures in schizophrenia, intellectual disability, and its related disorders.
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Affiliation(s)
- Akito Nakao
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan
| | - Naoyuki Miyazaki
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan
| | - Koji Ohira
- Department of Food Science and Nutrition, Mukogawa Women's University, Nishinomiya, Japan
| | - Hideo Hagihara
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan
| | - Tsuyoshi Takagi
- Institute for Developmental Research, Aichi Human Service Center, Kasugai, Japan.,RIKEN Tsukuba Institute, Tsukuba, Japan
| | - Nobuteru Usuda
- Department of Anatomy II, Fujita Health University School of Medicine, Toyoake, Japan
| | | | - Kazuyoshi Murata
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan
| | - Tsuyoshi Miyakawa
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi, 470-1192, Japan.
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Graham LC, Eaton SL, Brunton PJ, Atrih A, Smith C, Lamont DJ, Gillingwater TH, Pennetta G, Skehel P, Wishart TM. Proteomic profiling of neuronal mitochondria reveals modulators of synaptic architecture. Mol Neurodegener 2017; 12:77. [PMID: 29078798 PMCID: PMC5659037 DOI: 10.1186/s13024-017-0221-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 10/19/2017] [Indexed: 02/16/2023] Open
Abstract
Background Neurons are highly polarized cells consisting of three distinct functional domains: the cell body (and associated dendrites), the axon and the synapse. Previously, it was believed that the clinical phenotypes of neurodegenerative diseases were caused by the loss of entire neurons, however it has recently become apparent that these neuronal sub-compartments can degenerate independently, with synapses being particularly vulnerable to a broad range of stimuli. Whilst the properties governing the differential degenerative mechanisms remain unknown, mitochondria consistently appear in the literature, suggesting these somewhat promiscuous organelles may play a role in affecting synaptic stability. Synaptic and non-synaptic mitochondrial subpools are known to have different enzymatic properties (first demonstrated by Lai et al., 1977). However, the molecular basis underpinning these alterations, and their effects on morphology, has not been well documented. Methods The current study has employed electron microscopy, label-free proteomics and in silico analyses to characterize the morphological and biochemical properties of discrete sub-populations of mitochondria. The physiological relevance of these findings was confirmed in-vivo using a molecular genetic approach at the Drosophila neuromuscular junction. Results Here, we demonstrate that mitochondria at the synaptic terminal are indeed morphologically different to non-synaptic mitochondria, in both rodents and human patients. Furthermore, generation of proteomic profiles reveals distinct molecular fingerprints – highlighting that the properties of complex I may represent an important specialisation of synaptic mitochondria. Evidence also suggests that at least 30% of the mitochondrial enzymatic activity differences previously reported can be accounted for by protein abundance. Finally, we demonstrate that the molecular differences between discrete mitochondrial sub-populations are capable of selectively influencing synaptic morphology in-vivo. We offer several novel mitochondrial candidates that have the propensity to significantly alter the synaptic architecture in-vivo. Conclusions Our study demonstrates discrete proteomic profiles exist dependent upon mitochondrial subcellular localization and selective alteration of intrinsic mitochondrial proteins alters synaptic morphology in-vivo. Electronic supplementary material The online version of this article (10.1186/s13024-017-0221-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Laura C Graham
- Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
| | - Samantha L Eaton
- Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
| | - Paula J Brunton
- Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
| | - Abdelmadjid Atrih
- FingerPrints Proteomics Facility, College of Life Sciences, University of Dundee, Dundee, UK
| | - Colin Smith
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.,Department of Academic Neuropathology, University of Edinburgh, CCBS, Chancellor's Building, Little France, Edinburgh, UK
| | - Douglas J Lamont
- FingerPrints Proteomics Facility, College of Life Sciences, University of Dundee, Dundee, UK
| | - Thomas H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.,Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Giuseppa Pennetta
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.,Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Paul Skehel
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.,Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Thomas M Wishart
- Division of Neurobiology, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK. .,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK.
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13
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Negishi T, Miyazaki N, Murata K, Yasuo H, Ueno N. Physical association between a novel plasma-membrane structure and centrosome orients cell division. eLife 2016; 5:e16550. [PMID: 27502556 PMCID: PMC4978527 DOI: 10.7554/elife.16550] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/20/2016] [Indexed: 01/16/2023] Open
Abstract
In the last mitotic division of the epidermal lineage in the ascidian embryo, the cells divide stereotypically along the anterior-posterior axis. During interphase, we found that a unique membrane structure invaginates from the posterior to the centre of the cell, in a microtubule-dependent manner. The invagination projects toward centrioles on the apical side of the nucleus and associates with one of them. Further, a cilium forms on the posterior side of the cell and its basal body remains associated with the invagination. A laser ablation experiment suggests that the invagination is under tensile force and promotes the posterior positioning of the centrosome. Finally, we showed that the orientation of the invaginations is coupled with the polarized dynamics of centrosome movements and the orientation of cell division. Based on these findings, we propose a model whereby this novel membrane structure orchestrates centrosome positioning and thus the orientation of cell division axis.
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Affiliation(s)
- Takefumi Negishi
- Division of Morphogenesis, National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Japan
- Laboratoire de Biologie du Développement de Villefranche-sur-mer UMR7009, Observatoire Océanologique, Sorbonne Universités, UPMC Université Paris 06, CNRS, Villefranche-sur-Mer, France
| | - Naoyuki Miyazaki
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan
| | - Kazuyoshi Murata
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan
| | - Hitoyoshi Yasuo
- Laboratoire de Biologie du Développement de Villefranche-sur-mer UMR7009, Observatoire Océanologique, Sorbonne Universités, UPMC Université Paris 06, CNRS, Villefranche-sur-Mer, France
| | - Naoto Ueno
- Division of Morphogenesis, National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Japan
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, Okazaki, Japan
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14
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Mukherjee K, Clark HR, Chavan V, Benson EK, Kidd GJ, Srivastava S. Analysis of Brain Mitochondria Using Serial Block-Face Scanning Electron Microscopy. J Vis Exp 2016. [PMID: 27501303 DOI: 10.3791/54214] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Human brain is a high energy consuming organ that mainly relies on glucose as a fuel source. Glucose is catabolized by brain mitochondria via glycolysis, tri-carboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) pathways to produce cellular energy in the form of adenosine triphosphate (ATP). Impairment of mitochondrial ATP production causes mitochondrial disorders, which present clinically with prominent neurological and myopathic symptoms. Mitochondrial defects are also present in neurodevelopmental disorders (e.g. autism spectrum disorder) and neurodegenerative disorders (e.g. amyotrophic lateral sclerosis, Alzheimer's and Parkinson's diseases). Thus, there is an increased interest in the field for performing 3D analysis of mitochondrial morphology, structure and distribution under both healthy and disease states. The brain mitochondrial morphology is extremely diverse, with some mitochondria especially those in the synaptic region being in the range of <200 nm diameter, which is below the resolution limit of traditional light microscopy. Expressing a mitochondrially-targeted green fluorescent protein (GFP) in the brain significantly enhances the organellar detection by confocal microscopy. However, it does not overcome the constraints on the sensitivity of detection of relatively small sized mitochondria without oversaturating the images of large sized mitochondria. While serial transmission electron microscopy has been successfully used to characterize mitochondria at the neuronal synapse, this technique is extremely time-consuming especially when comparing multiple samples. The serial block-face scanning electron microscopy (SBFSEM) technique involves an automated process of sectioning, imaging blocks of tissue and data acquisition. Here, we provide a protocol to perform SBFSEM of a defined region from rodent brain to rapidly reconstruct and visualize mitochondrial morphology. This technique could also be used to provide accurate information on mitochondrial number, volume, size and distribution in a defined brain region. Since the obtained image resolution is high (typically under 10 nm) any gross mitochondrial morphological defects may also be detected.
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15
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Zidek J, Vojtova L, Abdel-Mohsen AM, Chmelik J, Zikmund T, Brtnikova J, Jakubicek R, Zubal L, Jan J, Kaiser J. Accurate micro-computed tomography imaging of pore spaces in collagen-based scaffold. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2016; 27:110. [PMID: 27153826 DOI: 10.1007/s10856-016-5717-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 04/09/2016] [Indexed: 06/05/2023]
Abstract
In this work we have used X-ray micro-computed tomography (μCT) as a method to observe the morphology of 3D porous pure collagen and collagen-composite scaffolds useful in tissue engineering. Two aspects of visualizations were taken into consideration: improvement of the scan and investigation of its sensitivity to the scan parameters. Due to the low material density some parts of collagen scaffolds are invisible in a μCT scan. Therefore, here we present different contrast agents, which increase the contrast of the scanned biopolymeric sample for μCT visualization. The increase of contrast of collagenous scaffolds was performed with ceramic hydroxyapatite microparticles (HAp), silver ions (Ag(+)) and silver nanoparticles (Ag-NPs). Since a relatively small change in imaging parameters (e.g. in 3D volume rendering, threshold value and μCT acquisition conditions) leads to a completely different visualized pattern, we have optimized these parameters to obtain the most realistic picture for visual and qualitative evaluation of the biopolymeric scaffold. Moreover, scaffold images were stereoscopically visualized in order to better see the 3D biopolymer composite scaffold morphology. However, the optimized visualization has some discontinuities in zoomed view, which can be problematic for further analysis of interconnected pores by commonly used numerical methods. Therefore, we applied the locally adaptive method to solve discontinuities issue. The combination of contrast agent and imaging techniques presented in this paper help us to better understand the structure and morphology of the biopolymeric scaffold that is crucial in the design of new biomaterials useful in tissue engineering.
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Affiliation(s)
- Jan Zidek
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic.
| | - Lucy Vojtova
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
- SCITEG, a.s., Brno, Czech Republic
| | - A M Abdel-Mohsen
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
- Textile Research Division, National Research Centre, El-Buhouth St, P.O. Box 12311, Cairo, Egypt
| | - Jiri Chmelik
- Institute of Biomedical Engineering, FEEC, Brno University of Technology, Technicka 12, 61600, Brno, Czech Republic
| | - Tomas Zikmund
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
| | - Jana Brtnikova
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
| | - Roman Jakubicek
- Institute of Biomedical Engineering, FEEC, Brno University of Technology, Technicka 12, 61600, Brno, Czech Republic
| | - Lukas Zubal
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
| | - Jiri Jan
- Institute of Biomedical Engineering, FEEC, Brno University of Technology, Technicka 12, 61600, Brno, Czech Republic
| | - Jozef Kaiser
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
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Kaji T, Kakui K, Miyazaki N, Murata K, Palmer AR. Mesoscale morphology at nanoscale resolution: serial block-face scanning electron microscopy reveals fine 3D detail of a novel silk spinneret system in a tube-building tanaid crustacean. Front Zool 2016; 13:14. [PMID: 27006683 PMCID: PMC4802664 DOI: 10.1186/s12983-016-0146-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 03/16/2016] [Indexed: 11/22/2022] Open
Abstract
Background The study of morphology is experiencing a renaissance due to rapid improvements in technologies for 3D visualization of complex internal and external structures. But 3D visualization of the internal structure of mesoscale objects — those in the 10–1000 μm range — remains problematic. They are too small for microCT, many lack suitable specific fluorescent markers for confocal microscopy, or they require labor-intensive stacking and smoothing of individual TEM images. Here we illustrate the first comprehensive morphological description of a complete mesoscale biological system at nanoscopic resolution using ultra-modern technology for 3D visualization — serial block-face scanning electron microscopy (SBF-SEM). The SBF-SEM machine combines an in-chamber ultramicrotome, which creates a serial array of exposed surfaces, with an SEM that images each surface as it is exposed. The serial images are then stacked automatically by 3D reconstruction software. We used SBF-SEM to study the spinneret (thread-producing) system of a small, tube-dwelling crustacean that weaves tubes of silk. Thread-producing ability is critical for the survival of many small-bodied animals but the basic morphology of these systems remains mysterious due to the limits of traditional microscopy. Results SBF-SEM allowed us to describe — in full 3D — well-resolved components (glands, ducts, pores, and associated nerves and muscles) of the spinneret system in the thoracic legs and body segments of Sinelobus sp. (Crustacea, Peracarida, Tanaidacea), a tube-building tanaid only 2 mm in body length. The 3D reconstruction by SBF-SEM revealed at nanoscale resolution a unique structure to the gland and duct systems: In each of three thread-producing thoracic segments, two separate ducts, derived from two separate glands located in the body, run through the entire leg and merge at the leg tip just before the spinneret pore opening. We also resolved nerves connecting to individual setae, spines and pores on the walking legs, and individual muscles within each leg segment. Conclusions Our results significantly expand our understanding of the diversity of spinneret systems in the Crustacea by providing the first well-resolved view of spinneret components in the peracarid crustacean order, Tanaidacea. More significantly, our results reveal the great power of SBF-SEM technology for comprehensive studies of the morphology of microscopic animals. Electronic supplementary material The online version of this article (doi:10.1186/s12983-016-0146-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tomonari Kaji
- Systematics and Evolution Group, Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada ; Allgemeine & Spezielle Zoologie, Institut fuer Biowissenschaften, Universität Rostock, Rostock, 18055 Germany
| | - Keiichi Kakui
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810 Japan
| | - Naoyuki Miyazaki
- National Institute for Physiological Sciences, Okazaki, Aichi 444-8585 Japan
| | - Kazuyoshi Murata
- National Institute for Physiological Sciences, Okazaki, Aichi 444-8585 Japan
| | - A Richard Palmer
- Systematics and Evolution Group, Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada
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Three-dimensional analysis of morphological changes in the malaria parasite infected red blood cell by serial block-face scanning electron microscopy. J Struct Biol 2016; 193:162-171. [PMID: 26772147 DOI: 10.1016/j.jsb.2016.01.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/16/2015] [Accepted: 01/05/2016] [Indexed: 01/22/2023]
Abstract
The human malaria parasite, Plasmodium falciparum, exhibits morphological changes during the blood stage cycle in vertebrate hosts. Here, we used serial block-face scanning electron microscopy (SBF-SEM) to visualize the entire structures of P. falciparum-infected red blood cells (iRBCs) and to examine their morphological and volumetric changes at different stages. During developmental stages, the parasite forms Maurer's clefts and vesicles in the iRBC cytoplasm and knobs on the iRBC surface, and extensively remodels the iRBC structure for proliferation of the parasite. In our observations, the Maurer's clefts and vesicles in the P. falciparum-iRBCs, resembling the so-called tubovesicular network (TVN), were not connected to each other, and continuous membrane networks were not observed between the parasitophorous vacuole membrane (PVM) and the iRBC cytoplasmic membrane. In the volumetric analysis, the iRBC volume initially increased and then decreased to the end of the blood stage cycle. This suggests that it is necessary to absorb a substantial amount of nutrients from outside the iRBC during the initial stage, but to release waste materials from inside the iRBC at the multinucleate stage. Transportation of the materials may be through the iRBC membrane, rather than a special structure formed by the parasite, because there is no direct connection between the iRBC membrane and the parasite. These results provide new insights as to how the malaria parasite grows in the iRBC and remodels iRBC structure during developmental stages; these observation can serve as a baseline for further experiments on the effects of therapeutic agents on malaria.
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Frankl A, Mari M, Reggiori F. Electron microscopy for ultrastructural analysis and protein localization in Saccharomyces cerevisiae. MICROBIAL CELL 2015; 2:412-428. [PMID: 28357267 PMCID: PMC5349205 DOI: 10.15698/mic2015.11.237] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The yeast Saccharomyces cerevisiae is a key model system for studying of a multitude of cellular processes because of its amenability to genetics, molecular biology and biochemical procedures. Ultrastructural examinations of this organism, though, are traditionally difficult because of the presence of a thick cell wall and the high density of cytoplasmic proteins. A series of recent methodological and technical developments, however, has revived interest in morphological analyses of yeast (e.g. 123). Here we present a review of established and new methods, from sample preparation to imaging, for the ultrastructural analysis of S. cerevisiae. We include information for the use of different fixation methods, embedding procedures, approaches for contrast enhancement, and sample visualization techniques, with references to successful examples. The goal of this review is to guide researchers that want to investigate a particular process at the ultrastructural level in yeast by aiding in the selection of the most appropriate approach to visualize a specific structure or subcellular compartment.
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Affiliation(s)
- Andri Frankl
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Muriel Mari
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Fulvio Reggiori
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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Three-dimensional architecture of podocytes revealed by block-face scanning electron microscopy. Sci Rep 2015; 5:8993. [PMID: 25759085 PMCID: PMC4355681 DOI: 10.1038/srep08993] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/12/2015] [Indexed: 12/31/2022] Open
Abstract
Block-face imaging is a scanning electron microscopic technique which enables easier acquisition of serial ultrastructural images directly from the surface of resin-embedded biological samples with a similar quality to transmission electron micrographs. In the present study, we analyzed the three-dimensional architecture of podocytes using serial block-face imaging. It was previously believed that podocytes are divided into three kinds of subcellular compartment: cell body, primary process, and foot process, which are simply aligned in this order. When the reconstructed podocytes were viewed from their basal side, the foot processes were branched from a ridge-like prominence, which was formed on the basal surface of the primary process and was similar to the usual foot processes in structure. Moreover, from the cell body, the foot processes were also emerged via the ridge-like prominence, as found in the primary process. The ridge-like prominence anchored the cell body and primary process to the glomerular basement membrane, and connected the foot processes to the cell body and primary process. In conclusion, serial block-face imaging is a powerful tool for clear understanding the three-dimensional architecture of podocytes through its ability to reveal novel structures which were difficult to determine by conventional transmission and scanning electron microscopes alone.
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