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Pepe A, Groen J, Zurzolo C, Sartori-Rupp A. Correlative cryo-microscopy pipelines for in situ cellular studies. Methods Cell Biol 2024; 187:175-203. [PMID: 38705624 DOI: 10.1016/bs.mcb.2024.02.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2024]
Abstract
Correlative cryo-microscopy pipelines combining light and electron microscopy and tomography in cryogenic conditions (cryoCLEM) on the same sample are powerful methods for investigating the structure of specific cellular targets identified by a fluorescent tag within their unperturbed cellular environment. CryoCLEM approaches circumvent one of the inherent limitations of cryo EM, and specifically cryo electron tomography (cryoET), of identifying the imaged structures in the crowded 3D environment of cells. Whereas several cryoCLEM approaches are based on thinning the sample by cryo FIB milling, here we present detailed protocols of two alternative cryoCLEM approaches for in situ studies of adherent cells at the single-cell level without the need for such cryo-thinning. The first approach is a complete cryogenic pipeline in which both fluorescence and electronic imaging are performed on frozen-hydrated samples, the second is a hybrid cryoCLEM approach in which fluorescence imaging is performed at room temperature, followed by rapid freezing and subsequent cryoEM imaging. We provide a detailed description of the two methods we have employed for imaging fluorescently labeled cellular structures with thickness below 350-500nm, such as cell protrusions and organelles located in the peripheral areas of the cells.
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Affiliation(s)
- Anna Pepe
- Membrane Traffic and Pathogenesis, Institut Pasteur, Paris, France
| | - Johannes Groen
- NanoImaging Core Facility, Institut Pasteur, Paris, France; Dynamics of Host-Pathogen Interactions, Institut Pasteur, Paris, France
| | - Chiara Zurzolo
- Membrane Traffic and Pathogenesis, Institut Pasteur, Paris, France
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2
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Engel L, Zaoralová M, Zhou M, Dunn AR, Oliver SL. Extracellular filaments revealed by affinity capture cryo-electron tomography of lymphocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.05.552110. [PMID: 37577490 PMCID: PMC10418515 DOI: 10.1101/2023.08.05.552110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Cryogenic-electron tomography (cryo-ET) has provided an un-precedented glimpse into the nanoscale architecture of cells by combining cryogenic preservation of biological structures with electron tomography. Micropatterning of extracellular matrix proteins is increasingly used as a method to prepare adherent cell types for cryo-ET as it promotes optimal positioning of cells and subcellular regions of interest for vitrification, cryo-focused ion beam (cryo-FIB) milling, and data acquisition. Here we demonstrate a micropatterning workflow for capturing minimally adherent cell types, human T-cells and Jurkat cells, for cryo-FIB and cryo-ET. Our affinity capture system facilitated the nanoscale imaging of Jurkat cells, revealing extracellular filamentous structures. It improved workflow efficiency by consistently producing grids with a sufficient number of well-positioned cells for an entire cryo-FIB session. Affinity capture can be extended to facilitate high resolution imaging of other adherent and non-adherent cell types with cryo-ET.
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Li W, Li A, Yu B, Zhang X, Liu X, White KL, Stevens RC, Baumeister W, Sali A, Jasnin M, Sun L. In situ structure of actin remodeling during glucose-stimulated insulin secretion using cryo-electron tomography. Nat Commun 2024; 15:1311. [PMID: 38346988 PMCID: PMC10861521 DOI: 10.1038/s41467-024-45648-7] [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: 06/14/2023] [Accepted: 01/30/2024] [Indexed: 02/15/2024] Open
Abstract
Actin mediates insulin secretion in pancreatic β-cells through remodeling. Hampered by limited resolution, previous studies have offered an ambiguous depiction as depolymerization and repolymerization. We report the in situ structure of actin remodeling in INS-1E β-cells during glucose-stimulated insulin secretion at nanoscale resolution. After remodeling, the actin filament network at the cell periphery exhibits three marked differences: 12% of actin filaments reorient quasi-orthogonally to the ventral membrane; the filament network mainly remains as cell-stabilizing bundles but partially reconfigures into a less compact arrangement; actin filaments anchored to the ventral membrane reorganize from a "netlike" to a "blooming" architecture. Furthermore, the density of actin filaments and microtubules around insulin secretory granules decreases, while actin filaments and microtubules become more densely packed. The actin filament network after remodeling potentially precedes the transport and release of insulin secretory granules. These findings advance our understanding of actin remodeling and its role in glucose-stimulated insulin secretion.
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Affiliation(s)
- Weimin Li
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Angdi Li
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Bing Yu
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Xiaoxiao Zhang
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
| | - Xiaoyan Liu
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
| | - Kate L White
- Department of Chemistry, Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, 90089, USA
| | - Raymond C Stevens
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Wolfgang Baumeister
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China.
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany.
| | - Andrej Sali
- Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA, 94158, USA.
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, 94158, USA.
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, 94158, USA.
| | - Marion Jasnin
- Helmholtz Pioneer Campus, Helmholtz Zentrum München, 85764, Neuherberg, Germany.
- Department of Chemistry, Technical University of Munich, 85748, Garching, Germany.
| | - Liping Sun
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China.
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4
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Ghaemi Z, Nafiu O, Tajkhorshid E, Gruebele M, Hu J. A computational spatial whole-Cell model for hepatitis B viral infection and drug interactions. Sci Rep 2023; 13:21392. [PMID: 38049515 PMCID: PMC10695947 DOI: 10.1038/s41598-023-45998-0] [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: 12/12/2022] [Accepted: 10/26/2023] [Indexed: 12/06/2023] Open
Abstract
Despite a vaccine, hepatitis B virus (HBV) remains a world-wide source of infections and deaths. We develop a whole-cell computational platform combining spatial and kinetic models describing the infection cycle of HBV in a hepatocyte host. We simulate key parts of the infection cycle with this whole-cell platform for 10 min of biological time, to predict infection progression, map out virus-host and virus-drug interactions. We find that starting from an established infection, decreasing the copy number of the viral envelope proteins shifts the dominant infection pathway from capsid secretion to re-importing the capsids into the nucleus, resulting in more nuclear-localized viral covalently closed circular DNA (cccDNA) and boosting transcription. This scenario can mimic the consequence of drugs designed to manipulate viral gene expression. Mutating capsid proteins facilitates capsid destabilization and disassembly at nuclear pore complexes, resulting in an increase in cccDNA copy number. However, excessive destabilization leads to premature cytoplasmic disassembly and does not increase the cccDNA counts. Finally, our simulations can predict the best drug dosage and its administration timing to reduce the cccDNA counts. Our adaptable computational platform can be parameterized to study other viruses and identify the most central viral pathways that can be targeted by drugs.
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Affiliation(s)
- Zhaleh Ghaemi
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- National Science Foundation Science and Technology Center for Quantitative Cell Biology, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
| | - Oluwadara Nafiu
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Emad Tajkhorshid
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- National Science Foundation Science and Technology Center for Quantitative Cell Biology, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Martin Gruebele
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- National Science Foundation Science and Technology Center for Quantitative Cell Biology, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jianming Hu
- Department of Microbiology and Immunology, Pennsylvania State University, Hershey, PA, 17033, USA
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5
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Li S, Jia X, Niu T, Zhang X, Qi C, Xu W, Deng H, Sun F, Ji G. HOPE-SIM, a cryo-structured illumination fluorescence microscopy system for accurately targeted cryo-electron tomography. Commun Biol 2023; 6:474. [PMID: 37120442 PMCID: PMC10148829 DOI: 10.1038/s42003-023-04850-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 04/18/2023] [Indexed: 05/01/2023] Open
Abstract
Cryo-focused ion beam (cryo-FIB) milling technology has been developed for the fabrication of cryo-lamella of frozen native specimens for study by in situ cryo-electron tomography (cryo-ET). However, the precision of the target of interest is still one of the major bottlenecks limiting application. Here, we have developed a cryo-correlative light and electron microscopy (cryo-CLEM) system named HOPE-SIM by incorporating a 3D structured illumination fluorescence microscopy (SIM) system and an upgraded high-vacuum stage to achieve efficiently targeted cryo-FIB. With the 3D super resolution of cryo-SIM as well as our cryo-CLEM software, 3D-View, the correlation precision of targeting region of interest can reach to 110 nm enough for the subsequent cryo-lamella fabrication. We have successfully utilized the HOPE-SIM system to prepare cryo-lamellae targeting mitochondria, centrosomes of HeLa cells and herpesvirus assembly compartment of infected BHK-21 cells, which suggests the high potency of the HOPE-SIM system for future in situ cryo-ET workflows.
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Affiliation(s)
- Shuoguo Li
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Xing Jia
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Tongxin Niu
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Xiaoyun Zhang
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Chen Qi
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Wei Xu
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Hongyu Deng
- University of Chinese Academy of Sciences, 100049, Beijing, China
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
| | - Fei Sun
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China.
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
- CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China.
| | - Gang Ji
- Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
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6
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Dow LP, Gaietta G, Kaufman Y, Swift MF, Lemos M, Lane K, Hopcroft M, Bezault A, Sauvanet C, Volkmann N, Pruitt BL, Hanein D. Morphological control enables nanometer-scale dissection of cell-cell signaling complexes. Nat Commun 2022; 13:7831. [PMID: 36539423 PMCID: PMC9768166 DOI: 10.1038/s41467-022-35409-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 12/01/2022] [Indexed: 12/24/2022] Open
Abstract
Protein micropatterning enables robust control of cell positioning on electron-microscopy substrates for cryogenic electron tomography (cryo-ET). However, the combination of regulated cell boundaries and the underlying electron-microscopy substrate (EM-grids) provides a poorly understood microenvironment for cell biology. Because substrate stiffness and morphology affect cellular behavior, we devised protocols to characterize the nanometer-scale details of the protein micropatterns on EM-grids by combining cryo-ET, atomic force microscopy, and scanning electron microscopy. Measuring force displacement characteristics of holey carbon EM-grids, we found that their effective spring constant is similar to physiological values expected from skin tissues. Despite their apparent smoothness at light-microscopy resolution, spatial boundaries of the protein micropatterns are irregular at nanometer scale. Our protein micropatterning workflow provides the means to steer both positioning and morphology of cell doublets to determine nanometer details of punctate adherens junctions. Our workflow serves as the foundation for studying the fundamental structural changes governing cell-cell signaling.
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Affiliation(s)
- Liam P. Dow
- grid.133342.40000 0004 1936 9676Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA USA
| | - Guido Gaietta
- grid.465257.70000 0004 5913 8442Scintillon Institute, San Diego, CA USA
| | - Yair Kaufman
- grid.133342.40000 0004 1936 9676Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA USA
| | - Mark F. Swift
- grid.465257.70000 0004 5913 8442Scintillon Institute, San Diego, CA USA
| | - Moara Lemos
- grid.428999.70000 0001 2353 6535Institut Pasteur, CNRS UMR3528, Structural Studies of Macromolecular Machines in Cellulo Unit, F-75015 Paris, France
| | - Kerry Lane
- grid.133342.40000 0004 1936 9676Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA USA
| | - Matthew Hopcroft
- grid.133342.40000 0004 1936 9676Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA USA
| | - Armel Bezault
- grid.428999.70000 0001 2353 6535Institut Pasteur, CNRS UMR3528, Structural Studies of Macromolecular Machines in Cellulo Unit, F-75015 Paris, France
| | - Cécile Sauvanet
- grid.428999.70000 0001 2353 6535Institut Pasteur, CNRS UMR3528, Structural Studies of Macromolecular Machines in Cellulo Unit, F-75015 Paris, France
| | - Niels Volkmann
- grid.465257.70000 0004 5913 8442Scintillon Institute, San Diego, CA USA ,Institut Pasteur, Université de Paris, CNRS UMR3528, Structural Image Analysis Unit, Paris, France
| | - Beth L. Pruitt
- grid.133342.40000 0004 1936 9676Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA USA
| | - Dorit Hanein
- grid.465257.70000 0004 5913 8442Scintillon Institute, San Diego, CA USA ,grid.428999.70000 0001 2353 6535Institut Pasteur, CNRS UMR3528, Structural Studies of Macromolecular Machines in Cellulo Unit, F-75015 Paris, France ,grid.133342.40000 0004 1936 9676Present Address: Department of Chemistry and Biochemistry, and of Biomedical Engineering, University of California, Santa Barbara, CA USA
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7
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Li XZ, Wang XL, Wang YJ, Liang QK, Li Y, Chen YW, Ming HX. Total flavonoids of Oxytropis falcata Bunge have a positive effect on idiopathic pulmonary fibrosis by inhibiting the TGF-β1/Smad signaling pathway. JOURNAL OF ETHNOPHARMACOLOGY 2022; 285:114858. [PMID: 34826543 DOI: 10.1016/j.jep.2021.114858] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/16/2021] [Accepted: 11/17/2021] [Indexed: 06/13/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease with unknown etiology. Oxytropis falcata Bunge (O. falcata) is a 1-35 cm high perennial clustered herb, also known as edaxia, has viscosity and a special smell, and is mainly distributed in the western areas of China. The root of O. falcata has a diameter of 6 mm, is straight and deep, dark red and its stems are shortened, woody and multibranched. O. falcata has heat-clearing, detoxification, analgesic, anti-inflammatory, antibacterial, hemostatic and antitumor activities. Furthermore, O. falcata has excellent anti-inflammatory and analgesic effects, and it is one of the three major anti-inflammatory drugs in Tibetan medicine, known as "the king of herbs". Total flavonoids of Oxytropis falcata Bunge (FOFB) were previously extracted, and their pharmacological activities are consistent with those of the whole herb. In this study, FOFB was extracted from O. falcata by ethanol extraction, and the mechanism of FOFB on IPF was verified by in vivo and in vitro experiments. AIM OF THE STUDY In this study, we aimed to observe the effects of FOFB on idiopathic pulmonary fibrosis. MATERIALS AND METHODS In in vivo experiments, an IPF rat model was established by bleomycin induction. The rats were treated with FOFB (100, 200, 400 mg kg-1·d-1) for 4 weeks. Masson staining and the expression of TGF-β, p-Smad2, p-Smad3 and Smad7 in the lung tissue of rats were detected. In in vitro experiments, we perfused normal rats with FOFB (100, 200, 400 mg kg-1·d-1) and obtained the corresponding drug-containing serum. The HFL-1 cell model induced by TGF-β1 was used to detect the corresponding indices through intervention with drug-containing serum. The best intervention time for drug-containing serum was detected by the CCK-8 method. Changes in apoptosis, cytoskeleton and rough endoplasmic reticulum structure were detected. Finally, the expression of TGF-β, p-Smad2, p-Smad3 and Smad7 in cells was examined. RESULTS In vivo, Masson staining indicated that the degree of pulmonary fibrosis increased significantly, the expression of TGF-β, p-smad2 and p-Smad3 increased significantly, and the expression of Smad7 decreased in the model group. We found that the degree of pulmonary fibrosis gradually decreased and that the inhibition of the TGF-β/Smad signaling pathway became more obvious with increasing FOFB dose. FOFB (400 mg kg-1·d-1) significantly improved the degree of pulmonary fibrosis in rats. In in vitro experiments, the CCK-8 results showed that 120 h was the best intervention time for drug-containing serum. In the model group, there was no obvious apoptosis or changes in microfilaments and microtubules, the number of rough endoplasmic reticulum increased, and the expression of TGF-β, p-Smad2 and p-Smad3 increased significantly, while the expression of Smad7 decreased significantly. We found that with the increase in drug-containing serum concentration, the apoptosis, cytoskeleton and degree of destruction of the rough endoplasmic reticulum in the HFL-1 cell model also increased, and the inhibition of the TGF-β/Smad signaling pathway became more pronounced; the effect of the drug-containing serum administered with FOFB (400 mg kg-1·d-1) was the most significant. CONCLUSIONS The results suggest that FOFB can improve the occurrence and development of IPF. The effect of FOFB on IPF may be mediated by inhibition of the TGF-β1/Smad signaling pathway.
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Affiliation(s)
- Xin-Ze Li
- Basic Medical College, Gansu University of Chinese Medicine, Gansu, Lanzhou, 730000, China; Basic Subjects of Integrated Traditional Chinese and Western Medicine, Gansu University of Chinese Medicine, Gansu, Lanzhou, 730000, China; Provincial-Level Key Laboratory for Molecular Medicine of Major Diseases and the Prevention and Treatment with Traditional Chinese Medicine Research in Gansu Colleges and Universities, Gansu, Lanzhou, 730000, China; Institute of Integrative Medicine with Gansu University of Traditional Chinese Medicine, Gansu, Lanzhou, 730000, China
| | - Xue-Lin Wang
- The Second Affiliated Hospital of Shaanxi University of Chinese Medicine, Shanxi, Xianyang, 712000, China
| | - Yan-Jun Wang
- Basic Medical College, Gansu University of Chinese Medicine, Gansu, Lanzhou, 730000, China; Basic Subjects of Integrated Traditional Chinese and Western Medicine, Gansu University of Chinese Medicine, Gansu, Lanzhou, 730000, China; Provincial-Level Key Laboratory for Molecular Medicine of Major Diseases and the Prevention and Treatment with Traditional Chinese Medicine Research in Gansu Colleges and Universities, Gansu, Lanzhou, 730000, China; Institute of Integrative Medicine with Gansu University of Traditional Chinese Medicine, Gansu, Lanzhou, 730000, China
| | - Qian-Kun Liang
- Basic Medical College, Gansu University of Chinese Medicine, Gansu, Lanzhou, 730000, China
| | - Yang Li
- Basic Medical College, Gansu University of Chinese Medicine, Gansu, Lanzhou, 730000, China
| | - Yan-Wen Chen
- Basic Medical College, Gansu University of Chinese Medicine, Gansu, Lanzhou, 730000, China
| | - Hai-Xia Ming
- Basic Medical College, Gansu University of Chinese Medicine, Gansu, Lanzhou, 730000, China; Basic Subjects of Integrated Traditional Chinese and Western Medicine, Gansu University of Chinese Medicine, Gansu, Lanzhou, 730000, China; Provincial-Level Key Laboratory for Molecular Medicine of Major Diseases and the Prevention and Treatment with Traditional Chinese Medicine Research in Gansu Colleges and Universities, Gansu, Lanzhou, 730000, China.
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8
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Rimoli CV, Valades-Cruz CA, Curcio V, Mavrakis M, Brasselet S. 4polar-STORM polarized super-resolution imaging of actin filament organization in cells. Nat Commun 2022; 13:301. [PMID: 35027553 PMCID: PMC8758668 DOI: 10.1038/s41467-022-27966-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 12/20/2021] [Indexed: 11/18/2022] Open
Abstract
Single-molecule localization microscopy provides insights into the nanometer-scale spatial organization of proteins in cells, however it does not provide information on their conformation and orientation, which are key functional signatures. Detecting single molecules' orientation in addition to their localization in cells is still a challenging task, in particular in dense cell samples. Here, we present a polarization-splitting scheme which combines Stochastic Optical Reconstruction Microscopy (STORM) with single molecule 2D orientation and wobbling measurements, without requiring a strong deformation of the imaged point spread function. This method called 4polar-STORM allows, thanks to a control of its detection numerical aperture, to determine both single molecules' localization and orientation in 2D and to infer their 3D orientation. 4polar-STORM is compatible with relatively high densities of diffraction-limited spots in an image, and is thus ideally placed for the investigation of dense protein assemblies in cells. We demonstrate the potential of this method in dense actin filament organizations driving cell adhesion and motility.
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Affiliation(s)
- Caio Vaz Rimoli
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013, Marseille, France
| | - Cesar Augusto Valades-Cruz
- Institut Curie, PSL Research University, UMR144 CNRS, Space-Time imaging of organelles and Endomembranes Dynamics Team, F-75005, Paris, France
- Inria Centre Rennes-Bretagne Atlantique, SERPICO Project Team, F-35042, Rennes, France
| | - Valentina Curcio
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013, Marseille, France
| | - Manos Mavrakis
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013, Marseille, France.
| | - Sophie Brasselet
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013, Marseille, France.
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9
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Abstract
The cytoskeleton is a complex of detergent-insoluble components of the cytoplasm playing critical roles in cell motility, shape generation, and mechanical properties of a cell. Fibrillar polymers-actin filaments, microtubules, and intermediate filaments-are major constituents of the cytoskeleton, which constantly change their organization during cellular activities. The actin cytoskeleton is especially polymorphic, as actin filaments can form multiple higher-order assemblies performing different functions. Structural information about cytoskeleton organization is critical for understanding its functions and mechanisms underlying various forms of cellular activity. Because of the nanometer-scale thickness of cytoskeletal fibers, electron microscopy (EM) is a key tool to determine the structure of the cytoskeleton.This article describes application of rotary shadowing (or platinum replica ) EM (PREM) for visualization of the cytoskeleton . The procedure is applicable to thin cultured cells growing on glass coverslips and consists of detergent extraction (or mechanical "unroofing") of cells to expose their cytoskeleton , chemical fixation to provide stability, ethanol dehydration and critical point drying to preserve three-dimensionality, rotary shadowing with platinum to create contrast, and carbon coating to stabilize replicas. This technique provides easily interpretable three-dimensional images, in which individual cytoskeletal fibers are clearly resolved and individual proteins can be identified by immunogold labeling. More importantly, PREM is easily compatible with live cell imaging, so that one can correlate the dynamics of a cell or its components, e.g., expressed fluorescent proteins, with high-resolution structural organization of the cytoskeleton in the same cell.
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Affiliation(s)
- Tatyana Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
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10
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Vasquez CG, de la Serna EL, Dunn AR. How cells tell up from down and stick together to construct multicellular tissues - interplay between apicobasal polarity and cell-cell adhesion. J Cell Sci 2021; 134:272658. [PMID: 34714332 DOI: 10.1242/jcs.248757] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Polarized epithelia define a topological inside and outside, and hence constitute a key evolutionary innovation that enabled the construction of complex multicellular animal life. Over time, this basic function has been elaborated upon to yield the complex architectures of many of the organs that make up the human body. The two processes necessary to yield a polarized epithelium, namely regulated adhesion between cells and the definition of the apicobasal (top-bottom) axis, have likewise undergone extensive evolutionary elaboration, resulting in multiple sophisticated protein complexes that contribute to both functions. Understanding how these components function in combination to yield the basic architecture of a polarized cell-cell junction remains a major challenge. In this Review, we introduce the main components of apicobasal polarity and cell-cell adhesion complexes, and outline what is known about their regulation and assembly in epithelia. In addition, we highlight studies that investigate the interdependence between these two networks. We conclude with an overview of strategies to address the largest and arguably most fundamental unresolved question in the field, namely how a polarized junction arises as the sum of its molecular parts.
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Affiliation(s)
- Claudia G Vasquez
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Eva L de la Serna
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Alexander R Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.,Biophysics Program, Stanford University, Stanford, CA 94305, USA.,Stanford Cardiovascular Institute, Stanford School of Medicine, Stanford, CA 94305, USA
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11
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Kacher YG, Karlova MG, Glukhov GS, Zhang H, Zaklyazminskaya EV, Loussouarn G, Sokolova OS. The Integrative Approach to Study of the Structure and Functions of Cardiac Voltage-Dependent Ion Channels. CRYSTALLOGR REP+ 2021. [DOI: 10.1134/s1063774521050072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Engel L, Vasquez CG, Montabana EA, Sow BM, Walkiewicz MP, Weis WI, Dunn AR. Lattice micropatterning for cryo-electron tomography studies of cell-cell contacts. J Struct Biol 2021; 213:107791. [PMID: 34520869 DOI: 10.1016/j.jsb.2021.107791] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/14/2021] [Accepted: 08/28/2021] [Indexed: 01/24/2023]
Abstract
Cryo-electron tomography is the highest resolution tool available for structural analysis of macromolecular complexes within their native cellular environments. At present, data acquisition suffers from low throughput, in part due to the low probability of positioning a cell such that the subcellular structure of interest is on a region of the electron microscopy (EM) grid that is suitable for imaging. Here, we photo-micropatterned EM grids to optimally position endothelial cells so as to enable high-throughput imaging of cell-cell contacts. Lattice micropatterned grids increased the average distance between intercellular contacts and thicker cell nuclei such that the regions of interest were sufficiently thin for direct imaging. We observed a diverse array of membranous and cytoskeletal structures at intercellular contacts, demonstrating the utility of this technique in enhancing the rate of data acquisition for cellular cryo-electron tomography studies.
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Affiliation(s)
- Leeya Engel
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, United States
| | - Claudia G Vasquez
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, United States
| | | | - Belle M Sow
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, United States
| | - Marcin P Walkiewicz
- Cell Sciences Imaging Facility, Stanford University, Stanford, CA 94305, United States
| | - William I Weis
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, United States; Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Alexander R Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, United States.
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13
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Abstract
The application of cryo-correlative light and cryo-electron microscopy (cryo-CLEM) gives us a way to locate structures of interest in the electron microscope. In brief, the structures of interest are fluorescently tagged, and images from the cryo-fluorescent microscope (cryo-FM) maps are superimposed on those from the cryo-electron microscope (cryo-EM). By enhancing cryo-FM to include single-molecule localization microscopy (SMLM), we can achieve much better localization. The introduction of cryo-SMLM increased the yield of photons from fluorophores, which can benefit localization efforts. Dahlberg and Moerner (2021, Annual Review of Physical Chemistry, 72, 253-278) have a recent broad and elegant review of super-resolution cryo-CLEM. This paper focuses on cryo(F)PALM/STORM for the cryo-electron tomography community. I explore the current challenges to increase the accuracy of localization by SMLM and the mapping of those positions onto cryo-EM images and maps. There is much to consider: we need to know if the excitation of fluorophores damages the structures we seek to visualize. We need to determine if higher numerical aperture (NA) objectives, which add complexity to image analysis but increase resolution and the efficiency of photon collection, are better than lower NA objectives, which pose fewer problems. We need to figure out the best way to determine the axial position of fluorophores. We need to have better ways of aligning maps determined by FM with those determined by EM. We need to improve the instrumentation to be easier to use, more accurate, and ice-contamination free. The bottom line is that we have more work to do.
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14
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Koliopoulos MG, Alfieri C. Cell cycle regulation by complex nanomachines. FEBS J 2021; 289:5100-5120. [PMID: 34143558 DOI: 10.1111/febs.16082] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/05/2021] [Accepted: 05/17/2021] [Indexed: 12/13/2022]
Abstract
The cell cycle is the essential biological process where one cell replicates its genome and segregates the resulting two copies into the daughter cells during mitosis. Several aspects of this process have fascinated humans since the nineteenth century. Today, the cell cycle is exhaustively investigated because of its profound connections with human diseases and cancer. At the heart of the molecular network controlling the cell cycle, we find the cyclin-dependent kinases (CDKs) acting as an oscillator to impose an orderly and highly regulated progression through the different cell cycle phases. This oscillator integrates both internal and external signals via a multitude of signalling pathways involving posttranslational modifications including phosphorylation, protein ubiquitination and mechanisms of transcriptional regulation. These tasks are specifically performed by multi-subunit complexes, which are intensively studied both biochemically and structurally with the aim to unveil mechanistic insights into their molecular function. The scope of this review is to summarise the structural biology of the cell cycle machinery, with specific focus on the core cell cycle machinery involving the CDK-cyclin oscillator. We highlight the contribution of cryo-electron microscopy, which has started to revolutionise our understanding of the molecular function and dynamics of the key players of the cell cycle.
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Affiliation(s)
- Marios G Koliopoulos
- Chester Beatty Laboratories, Structural Biology Division, Institute of Cancer Research, London, UK
| | - Claudio Alfieri
- Chester Beatty Laboratories, Structural Biology Division, Institute of Cancer Research, London, UK
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15
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Prokop A. Cytoskeletal organization of axons in vertebrates and invertebrates. J Cell Biol 2021; 219:151734. [PMID: 32369543 PMCID: PMC7337489 DOI: 10.1083/jcb.201912081] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022] Open
Abstract
The maintenance of axons for the lifetime of an organism requires an axonal cytoskeleton that is robust but also flexible to adapt to mechanical challenges and to support plastic changes of axon morphology. Furthermore, cytoskeletal organization has to adapt to axons of dramatically different dimensions, and to their compartment-specific requirements in the axon initial segment, in the axon shaft, at synapses or in growth cones. To understand how the cytoskeleton caters to these different demands, this review summarizes five decades of electron microscopic studies. It focuses on the organization of microtubules and neurofilaments in axon shafts in both vertebrate and invertebrate neurons, as well as the axon initial segments of vertebrate motor- and interneurons. Findings from these ultrastructural studies are being interpreted here on the basis of our contemporary molecular understanding. They strongly suggest that axon architecture in animals as diverse as arthropods and vertebrates is dependent on loosely cross-linked bundles of microtubules running all along axons, with only minor roles played by neurofilaments.
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Affiliation(s)
- Andreas Prokop
- School of Biology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK
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16
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Murin CD. Considerations of Antibody Geometric Constraints on NK Cell Antibody Dependent Cellular Cytotoxicity. Front Immunol 2020; 11:1635. [PMID: 32849559 PMCID: PMC7406664 DOI: 10.3389/fimmu.2020.01635] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 06/18/2020] [Indexed: 12/31/2022] Open
Abstract
It has been well-established that antibody isotype, glycosylation, and epitope all play roles in the process of antibody dependent cellular cytotoxicity (ADCC). For natural killer (NK) cells, these phenotypes are linked to cellular activation through interaction with the IgG receptor FcγRIIIa, a single pass transmembrane receptor that participates in cytoplasmic signaling complexes. Therefore, it has been hypothesized that there may be underlying spatial and geometric principles that guide proper assembly of an activation complex within the NK cell immune synapse. Further, synergy of antibody phenotypic properties as well as allosteric changes upon antigen binding may also play an as-of-yet unknown role in ADCC. Understanding these facets, however, remains hampered by difficulties associated with studying immune synapse dynamics using classical approaches. In this review, I will discuss relevant NK cell biology related to ADCC, including the structural biology of Fc gamma receptors, and how the dynamics of the NK cell immune synapse are being studied using innovative microscopy techniques. I will provide examples from the literature demonstrating the effects of spatial and geometric constraints on the T cell receptor complex and how this relates to intracellular signaling and the molecular nature of lymphocyte activation complexes, including those of NK cells. Finally, I will examine how the integration of high-throughput and "omics" technologies will influence basic NK cell biology research moving forward. Overall, the goal of this review is to lay a basis for understanding the development of drugs and therapeutic antibodies aimed at augmenting appropriate NK cell ADCC activity in patients being treated for a wide range of illnesses.
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Affiliation(s)
- Charles D. Murin
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA, United States
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Chakraborty S, Jasnin M, Baumeister W. Three-dimensional organization of the cytoskeleton: A cryo-electron tomography perspective. Protein Sci 2020; 29:1302-1320. [PMID: 32216120 PMCID: PMC7255506 DOI: 10.1002/pro.3858] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/17/2020] [Accepted: 03/20/2020] [Indexed: 01/01/2023]
Abstract
Traditionally, structures of cytoskeletal components have been studied ex situ, that is, with biochemically purified materials. There are compelling reasons to develop approaches to study them in situ in their native functional context. In recent years, cryo-electron tomography emerged as a powerful method for visualizing the molecular organization of unperturbed cellular landscapes with the potential to attain near-atomic resolution. Here, we review recent works on the cytoskeleton using cryo-electron tomography, demonstrating the power of in situ studies. We also highlight the potential of this method in addressing important questions pertinent to the field of cytoskeletal biomechanics.
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Affiliation(s)
- Saikat Chakraborty
- Department of Molecular Structural BiologyMax Planck Institute of BiochemistryMartinsriedGermany
| | - Marion Jasnin
- Department of Molecular Structural BiologyMax Planck Institute of BiochemistryMartinsriedGermany
| | - Wolfgang Baumeister
- Department of Molecular Structural BiologyMax Planck Institute of BiochemistryMartinsriedGermany
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