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Pérez-Garza J, Parrish-Mulliken E, Deane Z, Ostroff LE. Rehydration of Freeze Substituted Brain Tissue for Pre-embedding Immunoelectron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1694-1704. [PMID: 37584524 PMCID: PMC10541149 DOI: 10.1093/micmic/ozad077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/27/2023] [Accepted: 07/16/2023] [Indexed: 08/17/2023]
Abstract
Electron microscopy (EM) volume reconstruction is a powerful tool for investigating the fundamental structure of brain circuits, but the full potential of this technique is limited by the difficulty of integrating molecular information. High quality ultrastructural preservation is necessary for EM reconstruction, and intact, highly contrasted cell membranes are essential for following small neuronal processes through serial sections. Unfortunately, the antibody labeling methods used to identify most endogenous molecules result in compromised morphology, especially of membranes. Cryofixation can produce superior morphological preservation and has the additional advantage of allowing indefinite storage of valuable samples. We have developed a method based on cryofixation that allows sensitive immunolabeling of endogenous molecules, preserves excellent ultrastructure, and is compatible with high-contrast staining for serial EM reconstruction.
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Affiliation(s)
- Janeth Pérez-Garza
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Rd. Unit 3156, Storrs, CT 06269-3156, USA
| | - Emily Parrish-Mulliken
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Rd. Unit 3156, Storrs, CT 06269-3156, USA
| | - Zachary Deane
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Rd. Unit 3156, Storrs, CT 06269-3156, USA
| | - Linnaea E Ostroff
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Rd. Unit 3156, Storrs, CT 06269-3156, USA
- Connecticut Institute for the Brain and Cognitive Sciences, University of Connecticut, 337 Mansfield Rd. Unit 1272, Storrs, CT 06269-1272, USA
- Institute of Materials Science, University of Connecticut, 25 King Hill Rd. Unit 3136, Storrs, CT 06269-3136, USA
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2
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Garg N, Štibler UK, Eismann B, Mercker M, Bergheim BG, Linn A, Tuchscherer P, Engel U, Redl S, Marciniak-Czochra A, Holstein TW, Hess MW, Özbek S. Non-muscle myosin II drives critical steps of nematocyst morphogenesis. iScience 2023; 26:106291. [PMID: 36936784 PMCID: PMC10014300 DOI: 10.1016/j.isci.2023.106291] [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: 08/23/2022] [Revised: 10/04/2022] [Accepted: 02/20/2023] [Indexed: 03/02/2023] Open
Abstract
Nematocysts are generated by secretion of proteins into a post-Golgi compartment. They consist of a capsule that elongates into a long tube, which is coiled inside the capsule matrix and expelled during its nano-second discharge deployed for prey capture. The driving force for discharge is an extreme osmotic pressure of 150 bar. The complex processes of tube elongation and invagination under these biomechanical constraints have so far been elusive. Here, we show that a non-muscle myosin II homolog (HyNMII) is essential for nematocyst formation in Hydra. In early nematocysts, HyNMII assembles to a collar around the neck of the protruding tube. HyNMII then facilitates tube outgrowth by compressing it along the longitudinal axis as evidenced by inhibitor treatment and genetic knockdown. In addition, live imaging of a NOWA::NOWA-GFP transgenic line, which re-defined NOWA as a tube component facilitating invagination, allowed us to analyze the impact of HyNMII on tube maturation.
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Affiliation(s)
- Niharika Garg
- University of Heidelberg, Centre for Organismal Studies, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Urška Knez Štibler
- University of Heidelberg, Centre for Organismal Studies, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Björn Eismann
- University of Heidelberg, Centre for Organismal Studies, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Moritz Mercker
- Institute for Applied Mathematics, Interdisciplinary Center for Scientific Computing, Heidelberg University, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany
| | - Bruno Gideon Bergheim
- University of Heidelberg, Centre for Organismal Studies, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Anna Linn
- University of Heidelberg, Centre for Organismal Studies, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Patrizia Tuchscherer
- University of Heidelberg, Centre for Organismal Studies, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Ulrike Engel
- University of Heidelberg, Centre for Organismal Studies, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
- Nikon Imaging Center at the University of Heidelberg, Bioquant, Heidelberg University, 69120 Heidelberg, Germany
| | - Stefan Redl
- Institute of Neuroanatomy, Medical University of Innsbruck, Müllerstrasse 59, 6020 Innsbruck, Austria
- Institute of Zoology, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - Anna Marciniak-Czochra
- Institute for Applied Mathematics, Interdisciplinary Center for Scientific Computing, Heidelberg University, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany
| | - Thomas W. Holstein
- University of Heidelberg, Centre for Organismal Studies, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Michael W. Hess
- Institute of Histology and Embryology, Medical University of Innsbruck, Müllerstrasse 59, 6020 Innsbruck, Austria
| | - Suat Özbek
- University of Heidelberg, Centre for Organismal Studies, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
- Corresponding author
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3
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Lichtscheidl I, Lancelle S, Weidinger M, Adlassnig W, Koller-Peroutka M, Bauer S, Krammer S, Hepler PK. Gland cell responses to feeding in Drosera capensis, a carnivorous plant. PROTOPLASMA 2021; 258:1291-1306. [PMID: 34155556 PMCID: PMC8523503 DOI: 10.1007/s00709-021-01667-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 05/11/2021] [Indexed: 05/08/2023]
Abstract
Glands of Drosera absorb and transport nutrients from captured prey, but the mechanism and dynamics remain unclear. In this study, we offered animal proteins in the form of fluorescent albumin (FITC-BSA) and observed the reactions of the glands by live cell imaging and fluorescence microscopy. The ultrastructure of these highly dynamic processes was also assessed in high-pressure frozen and freeze substituted (HPF-FS) cells. HPF-FS yielded excellent preservation of the cytoplasm of all cell types, although the cytosol looked different in gland cells as compared to endodermoid and stalk cells. Especially prominent were the ER and its contacts with the plasma membrane, plasmodesmata, and other organelles as well as continuities between organelles. Also distinct were actin microfilaments in association with ER and organelles. Application of FITC-BSA to glands caused the formation of fluorescent endosomes that pinched off the plasma membrane. Endosomes fused to larger aggregates, and accumulated in the bulk cytoplasm around the nucleus. They did not fuse with the cell sap vacuole but remained for at least three days; in addition, fluorescent vesicles also proceeded through endodermoid and transfer cells to the epidermal and parenchymal cells of the tentacle stalk.
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Affiliation(s)
- Irene Lichtscheidl
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Sue Lancelle
- Biology Department, University of Massachusetts Amherst, 221 Morrill Science Center III; 611 North Pleasant Street, Amherst, MA 01003-9297 USA
| | - Marieluise Weidinger
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Wolfram Adlassnig
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Marianne Koller-Peroutka
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Sonja Bauer
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Stefanie Krammer
- Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Peter K. Hepler
- Biology Department, University of Massachusetts Amherst, 221 Morrill Science Center III; 611 North Pleasant Street, Amherst, MA 01003-9297 USA
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4
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Velamoor S, Mitchell A, Bostina M, Harland D. Processing hair follicles for transmission electron microscopy. Exp Dermatol 2021; 31:110-121. [PMID: 34351648 DOI: 10.1111/exd.14439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 11/30/2022]
Abstract
Transmission electron microscopy (TEM) has greatly advanced our knowledge of hair growth and follicle morphogenesis, but complex preparations such as fixation, dehydration and embedding compromise ultrastructure. While recent developments with cryofixation have been shown to preserve the ultrastructure of biological materials close to native state, they do have limitations. This review will focus on each stage of the TEM sample preparation process and their effects on the structural integrity of follicles.
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Affiliation(s)
- Sailakshmi Velamoor
- Proteins and Metabolites, AgResearch Limited, Lincoln, New Zealand.,Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Allan Mitchell
- Otago Micro and Nano Imaging, University of Otago, Dunedin, New Zealand
| | - Mihnea Bostina
- Microbiology and Immunology, University of Otago, Dunedin, New Zealand.,Otago Micro and Nano Imaging, University of Otago, Dunedin, New Zealand
| | - Duane Harland
- Proteins and Metabolites, AgResearch Limited, Lincoln, New Zealand
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Lange F, Agüi-Gonzalez P, Riedel D, Phan NTN, Jakobs S, Rizzoli SO. Correlative fluorescence microscopy, transmission electron microscopy and secondary ion mass spectrometry (CLEM-SIMS) for cellular imaging. PLoS One 2021; 16:e0240768. [PMID: 33970908 PMCID: PMC8109779 DOI: 10.1371/journal.pone.0240768] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 04/13/2021] [Indexed: 11/24/2022] Open
Abstract
Electron microscopy (EM) has been employed for decades to analyze cell structure. To also analyze the positions and functions of specific proteins, one typically relies on immuno-EM or on a correlation with fluorescence microscopy, in the form of correlated light and electron microscopy (CLEM). Nevertheless, neither of these procedures is able to also address the isotopic composition of cells. To solve this, a correlation with secondary ion mass spectrometry (SIMS) would be necessary. SIMS has been correlated in the past to EM or to fluorescence microscopy in biological samples, but not to CLEM. We achieved this here, using a protocol based on transmission EM, conventional epifluorescence microscopy and nanoSIMS. The protocol is easily applied, and enables the use of all three technologies at high performance parameters. We suggest that CLEM-SIMS will provide substantial information that is currently beyond the scope of conventional correlative approaches.
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Affiliation(s)
- Felix Lange
- Research Group Mitochondrial Structure and Dynamics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Clinic for Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Paola Agüi-Gonzalez
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Dietmar Riedel
- Laboratory of Electron Microscopy, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Nhu T. N. Phan
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Stefan Jakobs
- Research Group Mitochondrial Structure and Dynamics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Clinic for Neurology, University Medical Center Göttingen, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- * E-mail: (SJ); (SOR)
| | - Silvio O. Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- * E-mail: (SJ); (SOR)
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6
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Immuno-Electron and Confocal Laser Scanning Microscopy of the Glycocalyx. BIOLOGY 2021; 10:biology10050402. [PMID: 34064459 PMCID: PMC8147923 DOI: 10.3390/biology10050402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/29/2021] [Accepted: 05/01/2021] [Indexed: 11/26/2022]
Abstract
Simple Summary The glycocalyx (GCX) is a hydrated, gel-like layer of biological macromolecules attached to the cell membrane. The GCX acts as a barrier and regulates the entry of external substances into the cell. The function of the GCX is highly dependent on its structure and composition. Pathogenic factors can affect the protective structure of the GCX. We know very little about the three-dimensional organization of the GXC. The tiny and delicate structures of the GCX are difficult to study by microscopic techniques. In this study, we evaluated a method to preserve and label sensitive GCX components with antibodies for high-resolution microscopy analysis. High-resolution microscopy is a powerful tool because it allows visualization of ultra-small components and biological interactions. Our method can be used as a tool to better understand the role of the GCX during the development and progression of diseases, such as viral infections, tumor invasion, and the development of atherosclerosis. Abstract The glycocalyx (GCX), a pericellular carbohydrate rich hydrogel, forms a selective barrier that shields the cellular membrane, provides mechanical support, and regulates the transport and diffusion of molecules. The GCX is a fragile structure, making it difficult to study by transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Sample preparation by conventional chemical fixation destroys the GCX, giving a false impression of its organization. An additional challenge is to process the GCX in a way that preserves its morphology and enhanced antigenicity to study its cell-specific composition. The aim of this study was to provide a protocol to preserve both antigen accessibility and the unique morphology of the GCX. We established a combined high pressure freezing (HPF), osmium-free freeze substitution (FS), rehydration, and pre-embedding immunogold labeling method for TEM. Our results showed specific immunogold labeling of GCX components expressed in human monocytic THP-1 cells, hyaluronic acid receptor (CD44) and chondroitin sulfate (CS), and maintained a well-preserved GCX morphology. We adapted the protocol for antigen localization by CLSM and confirmed the specific distribution pattern of GCX components. The presented combination of HPF, FS, rehydration, and immunolabeling for both TEM and CLSM offers the possibility for analyzing the morphology and composition of the unique GCX structure.
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Advanced Microscopy for Liver and Gut Ultrastructural Pathology in Patients with MVID and PFIC Caused by MYO5B Mutations. J Clin Med 2021; 10:jcm10091901. [PMID: 33924896 PMCID: PMC8125609 DOI: 10.3390/jcm10091901] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 02/07/2023] Open
Abstract
Mutations in the actin motor protein myosinVb (myo5b) cause aberrant apical cargo transport and the congenital enteropathy microvillus inclusion disease (MVID). Recently, missense mutations in myo5b were also associated with progressive familial intrahepatic cholestasis (MYO5B-PFIC). Here, we thoroughly characterized the ultrastructural and immuno-cytochemical phenotype of hepatocytes and duodenal enterocytes from a unique case of an adult MYO5B-PFIC patient who showed constant hepatopathy but only periodic enteric symptoms. Selected data from two other patients supported the findings. Advanced methods such as cryo-fixation, freeze-substitution, immuno-gold labeling, electron tomography and immuno-fluorescence microscopy complemented the standard procedures. Liver biopsies showed mislocalization of Rab11 and bile canalicular membrane proteins. Rab11-positive vesicles clustered around bile canaliculi and resembled subapical clusters of aberrant recycling endosomes in enterocytes from MVID patients. The adult patient studied in detail showed a severe, MVID-specific enterocyte phenotype, despite only a mild clinical intestinal presentation. This included mislocalization of numerous proteins essential for apical cargo transport and morphological alterations. We characterized the heterogeneous population of large catabolic organelles regarding their complex ultrastructure and differential distribution of autophagic and lysosomal marker proteins. Finally, we generated duodenal organoids/enteroids from biopsies that recapitulated all MVID hallmarks, demonstrating the potential of this disease model for personalized medicine.
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8
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Benito-Martínez S, Zhu Y, Jani RA, Harper DC, Marks MS, Delevoye C. Research Techniques Made Simple: Cell Biology Methods for the Analysis of Pigmentation. J Invest Dermatol 2020; 140:257-268.e8. [PMID: 31980058 DOI: 10.1016/j.jid.2019.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/27/2019] [Accepted: 12/05/2019] [Indexed: 12/11/2022]
Abstract
Pigmentation of the skin and hair represents the result of melanin biosynthesis within melanosomes of epidermal melanocytes, followed by the transfer of mature melanin granules to adjacent keratinocytes within the basal layer of the epidermis. Natural variation in these processes produces the diversity of skin and hair color among human populations, and defects in these processes lead to diseases such as oculocutaneous albinism. While genetic regulators of pigmentation have been well studied in human and animal models, we are still learning much about the cell biological features that regulate melanogenesis, melanosome maturation, and melanosome motility in melanocytes, and have barely scratched the surface in our understanding of melanin transfer from melanocytes to keratinocytes. Herein, we describe cultured cell model systems and common assays that have been used by investigators to dissect these features and that will hopefully lead to additional advances in the future.
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Affiliation(s)
- Silvia Benito-Martínez
- Structure and Membrane Compartments, Institut Curie, Paris Sciences & Lettres Research University, Centre National de la Recherche Scientifique, Paris, France
| | - Yueyao Zhu
- Department of Biology Graduate Program, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania, USA; Department of Pathology and Laboratory Medicine and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Riddhi Atul Jani
- Structure and Membrane Compartments, Institut Curie, Paris Sciences & Lettres Research University, Centre National de la Recherche Scientifique, Paris, France
| | - Dawn C Harper
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania, USA
| | - Michael S Marks
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania, USA; Department of Pathology and Laboratory Medicine and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
| | - Cédric Delevoye
- Structure and Membrane Compartments, Institut Curie, Paris Sciences & Lettres Research University, Centre National de la Recherche Scientifique, Paris, France.
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VELAMOOR S, RICHENA M, MITCHELL A, LEQUEUX S, BOSTINA M, HARLAND D. High‐pressure freezing followed by freeze substitution of a complex and variable density miniorgan: the wool follicle. J Microsc 2020; 278:18-28. [DOI: 10.1111/jmi.12875] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/16/2020] [Accepted: 02/06/2020] [Indexed: 01/15/2023]
Affiliation(s)
- S. VELAMOOR
- Lincoln Research Centre, Food & Bio‐Based ProductsAgresearch Limited Lincoln New Zealand
- Department of Immunology and MicrobiologyUniversity of Otago Dunedin New Zealand
| | - M. RICHENA
- Lincoln Research Centre, Food & Bio‐Based ProductsAgresearch Limited Lincoln New Zealand
| | - A. MITCHELL
- Otago Micro and Nano Imaging UnitUniversity of Otago Dunedin New Zealand
| | - S. LEQUEUX
- Otago Micro and Nano Imaging UnitUniversity of Otago Dunedin New Zealand
| | - M. BOSTINA
- Department of Immunology and MicrobiologyUniversity of Otago Dunedin New Zealand
- Otago Micro and Nano Imaging UnitUniversity of Otago Dunedin New Zealand
| | - D. HARLAND
- Lincoln Research Centre, Food & Bio‐Based ProductsAgresearch Limited Lincoln New Zealand
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10
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Sele M, Wernitznig S, Lipovšek S, Radulović S, Haybaeck J, Birkl-Toeglhofer AM, Wodlej C, Kleinegger F, Sygulla S, Leoni M, Ropele S, Leitinger G. Optimization of ultrastructural preservation of human brain for transmission electron microscopy after long post-mortem intervals. Acta Neuropathol Commun 2019; 7:144. [PMID: 31481118 PMCID: PMC6724377 DOI: 10.1186/s40478-019-0794-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 08/24/2019] [Indexed: 12/16/2022] Open
Abstract
Electron microscopy (EM) provides the necessary resolution to visualize the finer structures of nervous tissue morphology, which is important to understand healthy and pathological conditions in the brain. However, for the interpretation of the micrographs the tissue preservation is crucial. The quality of the tissue structure is mostly influenced by the post mortem interval (PMI), the time of death until the preservation of the tissue. Therefore, the aim of this study was to optimize the preparation-procedure for the human frontal lobe to preserve the ultrastructure as well as possible despite the long PMIs. Combining chemical pre- and post-fixation with cryo-fixation and cryo-substitution ("hybrid freezing"), it was possible to improve the preservation of the neuronal profiles of human brain samples compared to the "standard" epoxy resin embedding method. In conclusion short PMIs are generally desirable but up to a PMI of 16 h the ultrastructure can be preserved on an acceptable level with a high contrast using the "hybrid freezing" protocol described here.
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11
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Yordanov TE, Hipolito VEB, Liebscher G, Vogel GF, Stasyk T, Herrmann C, Geley S, Teis D, Botelho RJ, Hess MW, Huber LA. Biogenesis of lysosome-related organelles complex-1 (BORC) regulates late endosomal/lysosomal size through PIKfyve-dependent phosphatidylinositol-3,5-bisphosphate. Traffic 2019; 20:674-696. [PMID: 31314175 PMCID: PMC6771566 DOI: 10.1111/tra.12679] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 07/15/2019] [Indexed: 01/02/2023]
Abstract
Mechanisms that control lysosomal function are essential for cellular homeostasis. Lysosomes adapt in size and number to cellular needs but little is known about the underlying molecular mechanism. We demonstrate that the late endosomal/lysosomal multimeric BLOC-1-related complex (BORC) regulates the size of these organelles via PIKfyve-dependent phosphatidylinositol-3,5-bisphosphate [PI(3,5)P2 ] production. Deletion of the core BORC component Diaskedin led to increased levels of PI(3,5)P2 , suggesting activation of PIKfyve, and resulted in enhanced lysosomal reformation and subsequent reduction in lysosomal size. This process required AMP-activated protein kinase (AMPK), a known PIKfyve activator, and was additionally dependent on the late endosomal/lysosomal adaptor, mitogen-activated protein kinases and mechanistic target of rapamycin activator (LAMTOR/Ragulator) complex. Consistently, in response to glucose limitation, AMPK activated PIKfyve, which induced lysosomal reformation with increased baseline autophagy and was coupled to a decrease in lysosomal size. These adaptations of the late endosomal/lysosomal system reversed under glucose replete growth conditions. In summary, our results demonstrate that BORC regulates lysosomal reformation and size in response to glucose availability.
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Affiliation(s)
- Teodor E. Yordanov
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - Victoria E. B. Hipolito
- Department of Chemistry and Biology and the Graduate Program in Molecular ScienceRyerson UniversityTorontoOntarioCanada
| | - Gudrun Liebscher
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - Georg F. Vogel
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
- Department of Pediatrics IMedical University of InnsbruckInnsbruckAustria
| | - Taras Stasyk
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - Caroline Herrmann
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - Stephan Geley
- Division of Molecular Pathophysiology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - David Teis
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - Roberto J. Botelho
- Department of Chemistry and Biology and the Graduate Program in Molecular ScienceRyerson UniversityTorontoOntarioCanada
| | - Michael W. Hess
- Division of Histology and EmbryologyMedical University of InnsbruckInnsbruckAustria
| | - Lukas A. Huber
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
- Austrian Drug Screening Institute, ADSIInnsbruckAustria
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Membrane-Associated, Not Cytoplasmic or Nuclear, FGFR1 Induces Neuronal Differentiation. Cells 2019; 8:cells8030243. [PMID: 30875802 PMCID: PMC6468866 DOI: 10.3390/cells8030243] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/04/2019] [Accepted: 03/08/2019] [Indexed: 01/22/2023] Open
Abstract
The intracellular transport of receptor tyrosine kinases results in the differential activation of various signaling pathways. In this study, optogenetic stimulation of fibroblast growth factor receptor type 1 (FGFR1) was performed to study the effects of subcellular targeting of receptor kinases on signaling and neurite outgrowth. The catalytic domain of FGFR1 fused to the algal light-oxygen-voltage-sensing (LOV) domain was directed to different cellular compartments (plasma membrane, cytoplasm and nucleus) in human embryonic kidney (HEK293) and pheochromocytoma (PC12) cells. Blue light stimulation elevated the pERK and pPLCγ1 levels in membrane-opto-FGFR1-transfected cells similarly to ligand-induced receptor activation; however, no changes in pAKT levels were observed. PC12 cells transfected with membrane-opto-FGFR1 exhibited significantly longer neurites after light stimulation than after growth factor treatment, and significantly more neurites extended from their cell bodies. The activation of cytoplasmic FGFR1 kinase enhanced ERK signaling in HEK293 cells but not in PC12 cells and did not induce neuronal differentiation. The stimulation of FGFR1 kinase in the nucleus also did not result in signaling changes or neurite outgrowth. We conclude that FGFR1 kinase needs to be associated with membranes to induce the differentiation of PC12 cells mainly via ERK activation.
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