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Lloyd-Lewis B, D'Angelo ME, Prowting NB, Wiseman BE, Sargeant TJ, Watson CJ. Methods for investigating STAT3 regulation of lysosomal function in mammary epithelial cells. J Mammary Gland Biol Neoplasia 2024; 29:11. [PMID: 38761238 PMCID: PMC11102350 DOI: 10.1007/s10911-024-09563-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 05/02/2024] [Indexed: 05/20/2024] Open
Abstract
The transcription factor STAT3 is activated by multiple cytokines and other extrinsic factors. It plays a key role in immune and inflammatory responses and, when dysregulated, in tumourigenesis. STAT3 is also an indispensable mediator of the cell death process that occurs during post-lactational regression of the mammary gland, one of the most dramatic examples of physiological cell death in adult mammals. During this involution of the gland, STAT3 powerfully enhances the lysosomal system to efficiently remove superfluous milk-producing mammary epithelial cells via a lysosomal-mediated programmed cell death pathway. The lysosome is a membrane-enclosed cytoplasmic organelle that digests and recycles cellular waste, with an important role as a signalling centre that monitors cellular metabolism. Here, we describe key strategies for investigating the role of STAT3 in regulating lysosomal function using a mammary epithelial cell culture model system. These include protocols for lysosome enrichment and enzyme activity assays, in addition to microscopic analyses of the vesicular compartment in cell lines. Collectively, these approaches provide the tools to investigate multiple aspects of lysosome biogenesis and function, and to define both direct and indirect roles for STAT3.
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Affiliation(s)
- Bethan Lloyd-Lewis
- School of Cellular and Molecular Medicine, Biomedical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK.
| | - Michael E D'Angelo
- Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Neve B Prowting
- School of Cellular and Molecular Medicine, Biomedical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK
| | - Bethan E Wiseman
- School of Cellular and Molecular Medicine, Biomedical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK
| | - Timothy J Sargeant
- Hopwood Centre for Neurobiology, Lifelong Health Theme, Lysosomal Health in Ageing, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Christine J Watson
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
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Dudka W, Salo VT, Mahamid J. Zooming into lipid droplet biology through the lens of electron microscopy. FEBS Lett 2024; 598:1127-1142. [PMID: 38726814 DOI: 10.1002/1873-3468.14899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/08/2024] [Accepted: 04/24/2024] [Indexed: 05/25/2024]
Abstract
Electron microscopy (EM), in its various flavors, has significantly contributed to our understanding of lipid droplets (LD) as central organelles in cellular metabolism. For example, EM has illuminated that LDs, in contrast to all other cellular organelles, are uniquely enclosed by a single phospholipid monolayer, revealed the architecture of LD contact sites with different organelles, and provided near-atomic resolution maps of key enzymes that regulate neutral lipid biosynthesis and LD biogenesis. In this review, we first provide a brief history of pivotal findings in LD biology unveiled through the lens of an electron microscope. We describe the main EM techniques used in the context of LD research and discuss their current capabilities and limitations, thereby providing a foundation for utilizing suitable EM methodology to address LD-related questions with sufficient level of structural preservation, detail, and resolution. Finally, we highlight examples where EM has recently been and is expected to be instrumental in expanding the frontiers of LD biology.
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Affiliation(s)
- Wioleta Dudka
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Veijo T Salo
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Cell Biology and Biophysics Unit, EMBL, Heidelberg, Germany
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3
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Makam SN, Setamou M, Alabi OJ, Day W, Cromey D, Nwugo C. Mitigation of Huanglongbing: Implications of a Biologically Enhanced Nutritional Program on Yield, Pathogen Localization, and Host Gene Expression Profiles. PLANT DISEASE 2023; 107:3996-4009. [PMID: 37415358 DOI: 10.1094/pdis-10-22-2336-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/08/2023]
Abstract
Huanglongbing (HLB, citrus greening disease), the most destructive disease affecting citrus production, is primarily linked to the gram-negative, insect-vectored, phloem-inhabiting α-proteobacterium 'Candidatus Liberibacter asiaticus' (CLas). With no effective treatment available, management strategies have largely focused on the use of insecticides in addition to the destruction of infected trees, which are environmentally hazardous and cost-prohibitive for growers, respectively. A major limitation to combating HLB is the inability to isolate CLas in axenic culture, which hinders in vitro studies and creates a need for robust in situ CLas detection and visualization methods. The aim of this study was to investigate the efficacy of a nutritional program-based approach for HLB treatment, and to explore the effectiveness of an enhanced immunodetection method to detect CLas-infected tissues. To achieve this, four different biologically enhanced nutritional programs (bENPs; P1, P2, P3, and P4) were tested on CLas-infected citrus trees. Structured illumination microscopy preceded by a modified immunolabeling process and transmission electron microscopy were used to show treatment-dependent reduction of CLas cells in phloem tissues. No sieve pore plugging was seen in the leaves of P2 trees. This was accompanied by an 80% annual increase in fruit number per tree and 1,503 (611 upregulated and 892 downregulated) differentially expressed genes. These included an MLRQ subunit gene, UDP-glucose transferase, and genes associated with the alpha-amino linolenic acid metabolism pathway in P2 trees. Taken together, the results highlight a major role for bENPs as a viable, sustainable, and cost effective option for HLB management.
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Affiliation(s)
- Srinivas N Makam
- Integrated Life Science Research Center (ILSRC), Goodyear, AZ 85338
| | - Mamoudou Setamou
- Texas A&M University-Kingsville Citrus Center, Weslaco, TX 78599
| | - Olufemi J Alabi
- Plant Pathology and Microbiology, Texas A&M AgriLife Research and Extension Center, Weslaco, TX 78596
| | - William Day
- The Imaging Cores Life Sciences North, Research, Innovation and Impact Department, University of Arizona, Tucson, AZ 85719
| | - Douglas Cromey
- The Imaging Cores Life Sciences North, Research, Innovation and Impact Department, University of Arizona, Tucson, AZ 85719
| | - Chika Nwugo
- Integrated Life Science Research Center (ILSRC), Goodyear, AZ 85338
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Vanslembrouck B, Chen JH, Larabell C, van Hengel J. Microscopic Visualization of Cell-Cell Adhesion Complexes at Micro and Nanoscale. Front Cell Dev Biol 2022; 10:819534. [PMID: 35517500 PMCID: PMC9065677 DOI: 10.3389/fcell.2022.819534] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Accepted: 03/21/2022] [Indexed: 12/25/2022] Open
Abstract
Considerable progress has been made in our knowledge of the morphological and functional varieties of anchoring junctions. Cell-cell adhesion contacts consist of discrete junctional structures responsible for the mechanical coupling of cytoskeletons and allow the transmission of mechanical signals across the cell collective. The three main adhesion complexes are adherens junctions, tight junctions, and desmosomes. Microscopy has played a fundamental role in understanding these adhesion complexes on different levels in both physiological and pathological conditions. In this review, we discuss the main light and electron microscopy techniques used to unravel the structure and composition of the three cell-cell contacts in epithelial and endothelial cells. It functions as a guide to pick the appropriate imaging technique(s) for the adhesion complexes of interest. We also point out the latest techniques that have emerged. At the end, we discuss the problems investigators encounter during their cell-cell adhesion research using microscopic techniques.
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Affiliation(s)
- Bieke Vanslembrouck
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Anatomy, University of San Francisco, San Francisco, CA, United States
- *Correspondence: Bieke Vanslembrouck, ; Jolanda van Hengel,
| | - Jian-hua Chen
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Anatomy, University of San Francisco, San Francisco, CA, United States
| | - Carolyn Larabell
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Anatomy, University of San Francisco, San Francisco, CA, United States
| | - Jolanda van Hengel
- Medical Cell Biology Research Group, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
- *Correspondence: Bieke Vanslembrouck, ; Jolanda van Hengel,
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Yamada A, Nishida Y, Wake K, Nakamura A, Sakamaki Y, Kuwahara H, Uchihara T, Yokota T. OUP accepted manuscript. Microscopy (Oxf) 2022; 71:124-131. [PMID: 35157050 PMCID: PMC8973401 DOI: 10.1093/jmicro/dfac005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/10/2022] [Accepted: 02/04/2022] [Indexed: 11/16/2022] Open
Abstract
Precise immunolocalization of molecules in relation to ultrastructural features is challenging, especially when the target is small and not frequent enough to be included in tiny ultrathin sections randomly selected for electron microscopy (EM). Glucose transporter 1 (GLUT1) is in charge of transporting glucose across brain capillary endothelial cells (BCECs). Paraformaldehyde-fixed floating sections (50 μm thick) of mouse brain were immunolabeled with anti-GLUT1 antibody and visualized with fluoronanogold. Fluorescent images encompassing the entire hemisphere were tiled to enable selection of GLUT1-positive BCECs suitable for subsequent EM and landmark placement with laser microdissection to guide trimming. Sections were then fixed with glutaraldehyde, gold enhanced to intensify the labeling and fixed with osmium tetroxide to facilitate ultrastructural recognition. Even though a region that contained target BCECs was successfully trimmed in the resin block, it was only after observation of serial ultrathin sections that GLUT1 signals in coated vesicles on the same cross section corresponding to the cross section preidentified by confocal laser microscope. This is the first ultrastructural demonstration of GLUT1 molecules in coated vesicles, which may well explain its functional relevance to transport glucose across BCECs. Successful ultrastructural localization of molecules in relation to well-preserved target structure in native tissue samples, as achieved in this study, will pave the way to understand the functional relevance of molecules and their relation to ultrastructural details.
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Affiliation(s)
- Akane Yamada
- Department of Neurology and Neurological Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Yoichiro Nishida
- Department of Neurology and Neurological Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Kenjiro Wake
- Liver Research Unit, Minophagen Pharmaceutical Co., Ltd., 3F., Shinjuku Mitsui Building No. 2, 3-2-11, Nishi-Shinjuku Shinjuku-ku, Tokyo 160-0023, Japan
| | - Ayako Nakamura
- Department of Neurology and Neurological Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Yuriko Sakamaki
- Microscopy Research Support Unit Research Core, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Hiroya Kuwahara
- Department of Neurology and Neurological Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | | | - Takanori Yokota
- Department of Neurology and Neurological Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
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6
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Ivanchenko MV, Indzhykulian AA, Corey DP. Electron Microscopy Techniques for Investigating Structure and Composition of Hair-Cell Stereociliary Bundles. Front Cell Dev Biol 2021; 9:744248. [PMID: 34746139 PMCID: PMC8569945 DOI: 10.3389/fcell.2021.744248] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 09/28/2021] [Indexed: 11/18/2022] Open
Abstract
Hair cells—the sensory cells of the vertebrate inner ear—bear at their apical surfaces a bundle of actin-filled protrusions called stereocilia, which mediate the cells’ mechanosensitivity. Hereditary deafness is often associated with morphological disorganization of stereocilia bundles, with the absence or mislocalization within stereocilia of specific proteins. Thus, stereocilia bundles are closely examined to understand most animal models of hereditary hearing loss. Because stereocilia have a diameter less than a wavelength of light, light microscopy is not adequate to reveal subtle changes in morphology or protein localization. Instead, electron microscopy (EM) has proven essential for understanding stereocilia bundle development, maintenance, normal function, and dysfunction in disease. Here we review a set of EM imaging techniques commonly used to study stereocilia, including optimal sample preparation and best imaging practices. These include conventional and immunogold transmission electron microscopy (TEM) and scanning electron microscopy (SEM), as well as focused-ion-beam scanning electron microscopy (FIB-SEM), which enables 3-D serial reconstruction of resin-embedded biological structures at a resolution of a few nanometers. Parameters for optimal sample preparation, fixation, immunogold labeling, metal coating and imaging are discussed. Special attention is given to protein localization in stereocilia using immunogold labeling. Finally, we describe the advantages and limitations of these EM techniques and their suitability for different types of studies.
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Affiliation(s)
- Maryna V Ivanchenko
- Department of Neurobiology, Harvard Medical School, Boston, MA, United States
| | - Artur A Indzhykulian
- Department of Otolaryngology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - David P Corey
- Department of Neurobiology, Harvard Medical School, Boston, MA, United States
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Amen T, Guihur A, Zelent C, Ursache R, Wilting J, Kaganovich D. Resveratrol and related stilbene derivatives induce stress granules with distinct clearance kinetics. Mol Biol Cell 2021; 32:ar18. [PMID: 34432484 PMCID: PMC8693967 DOI: 10.1091/mbc.e21-02-0066] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Stress granules (SGs) are ribonucleoprotein functional condensates that form under stress conditions in all eukaryotic cells. Although their stress-survival function is far from clear, SGs have been implicated in the regulation of many vital cellular pathways. Consequently, SG dysfunction is thought to be a mechanistic point of origin for many neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). Additionally, SGs are thought to play a role in pathogenic pathways as diverse as viral infection and chemotherapy resistance. There is a growing consensus on the hypothesis that understanding the mechanistic regulation of SG physical properties is essential to understanding their function. Although the internal dynamics and condensation mechanisms of SGs have been broadly investigated, there have been fewer investigations into the timing of SG formation and clearance in live cells. Because the lifetime of SG persistence can be a key factor in their function and tendency toward pathological dysregulation, SG clearance mechanisms deserve particular attention. Here we show that resveratrol and its analogues piceatannol, pterostilbene, and 3,4,5,4'-tetramethoxystilbene induce G3BP-dependent SG formation with atypically rapid clearance kinetics. Resveratrol binds to G3BP, thereby reducing its protein-protein association valency. We suggest that altering G3BP valency is a pathway for the formation of uniquely transient SGs.
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Affiliation(s)
- Triana Amen
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, 37073, Goettingen, Germany
| | - Anthony Guihur
- Department of Plant Molecular Biology, Faculty of Biology and Medicine, University of Lausanne, Switzerland
| | - Christina Zelent
- Department of Anatomy and Cell Biology, University Medical Center Göttingen, 37073, Goettingen, Germany
| | - Robertas Ursache
- Department of Plant Molecular Biology, Faculty of Biology and Medicine, University of Lausanne, Switzerland
| | - Jörg Wilting
- Department of Anatomy and Cell Biology, University Medical Center Göttingen, 37073, Goettingen, Germany
| | - Daniel Kaganovich
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, 37073, Goettingen, Germany.,1Base Pharmaceuticals, Boston, MA, 02129, USA
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Petralia RS, Wang YX. Review of Post-embedding Immunogold Methods for the Study of Neuronal Structures. Front Neuroanat 2021; 15:763427. [PMID: 34720893 PMCID: PMC8551803 DOI: 10.3389/fnana.2021.763427] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 09/28/2021] [Indexed: 01/03/2023] Open
Abstract
The post-embedding immunogold (PI) technique for immunolabeling of neuronal tissues utilizing standard thin-section transmission electron microscopy (TEM) continues to be a prime method for understanding the functional localization of key proteins in neuronal function. Its main advantages over other immunolabeling methods for thin-section TEM are (1) fairly accurate and quantifiable localization of proteins in cells; (2) double-labeling of sections using two gold particle sizes; and (3) the ability to perform multiple labeling for different proteins by using adjacent sections. Here we first review in detail a common method for PI of neuronal tissues. This method has two major parts. First, we describe the freeze-substitution embedding method: cryoprotected tissue is frozen in liquid propane via plunge-freezing, and is placed in a freeze-substitution instrument in which the tissue is embedded in Lowicryl at low temperatures. We highlight important aspects of freeze-substitution embedding. Then we outline how thin sections of embedded tissue on grids are labeled with a primary antibody and a secondary gold particle-conjugated antibody, and the particular problems encountered in TEM of PI-labeled sections. In the Discussion, we compare our method both to earlier PI methods and to more recent PI methods used by other laboratories. We also compare TEM immunolabeling using PI vs. various pre-embedding immunolabeling methods, especially relating to neuronal tissue.
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Affiliation(s)
- Ronald S. Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
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