1
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Sharma N, Angori S, Sandberg A, Mermelekas G, Lehtiö J, Wiklander OPB, Görgens A, Andaloussi SE, Eriksson H, Pernemalm M. Defining the Soluble and Extracellular Vesicle Protein Compartments of Plasma Using In-Depth Mass Spectrometry-Based Proteomics. J Proteome Res 2024; 23:4114-4127. [PMID: 39141927 PMCID: PMC11385381 DOI: 10.1021/acs.jproteome.4c00490] [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: 08/16/2024]
Abstract
Plasma-derived extracellular vesicles (pEVs) are a potential source of diseased biomarker proteins. However, characterizing the pEV proteome is challenging due to its relatively low abundance and difficulties in enrichment. This study presents a streamlined workflow to identify EV proteins from cancer patient plasma using minimal sample input. Starting with 400 μL of plasma, we generated a comprehensive pEV proteome using size exclusion chromatography (SEC) combined with HiRIEF prefractionation-based mass spectrometry (MS). First, we compared the performance of HiRIEF and long gradient MS workflows using control pEVs, quantifying 2076 proteins with HiRIEF. In a proof-of-concept study, we applied SEC-HiRIEF-MS to a small cohort (12) of metastatic lung adenocarcinoma (LUAD) and malignant melanoma (MM) patients. We also analyzed plasma samples from the same patients to study the relationship between plasma and pEV proteomes. We identified and quantified 1583 proteins in cancer pEVs and 1468 proteins in plasma across all samples. While there was substantial overlap, the pEV proteome included several unique EV markers and cancer-related proteins. Differential analysis revealed 30 DEPs in LUAD vs the MM group, highlighting the potential of pEVs as biomarkers. This work demonstrates the utility of a prefractionation-based MS for comprehensive pEV proteomics and EV biomarker discovery. Data are available via ProteomeXchange with the identifiers PXD039338 and PXD038528.
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Affiliation(s)
- Nidhi Sharma
- Department of Oncology-Pathology, Karolinska Institute, 171 77 Stockholm, Sweden
- Science for Life Laboratory, Solna, Tomtebodavägen 23, 171 65 Solna, Sweden
| | - Silvia Angori
- Department of Oncology-Pathology, Karolinska Institute, 171 77 Stockholm, Sweden
| | - AnnSofi Sandberg
- Department of Oncology-Pathology, Karolinska Institute, 171 77 Stockholm, Sweden
- Science for Life Laboratory, Solna, Tomtebodavägen 23, 171 65 Solna, Sweden
| | - Georgios Mermelekas
- Department of Oncology-Pathology, Karolinska Institute, 171 77 Stockholm, Sweden
- Science for Life Laboratory, Solna, Tomtebodavägen 23, 171 65 Solna, Sweden
| | - Janne Lehtiö
- Department of Oncology-Pathology, Karolinska Institute, 171 77 Stockholm, Sweden
- Science for Life Laboratory, Solna, Tomtebodavägen 23, 171 65 Solna, Sweden
| | - Oscar P B Wiklander
- Theme Cancer, Skin Cancer Center, Karolinska University Hospital, 171 77 Solna, Sweden
- Biomolecular Medicine, Clinical Research Center, Department of Laboratory Medicine, Karolinska Institute, 171 76 Solna, Sweden
| | - André Görgens
- Biomolecular Medicine, Clinical Research Center, Department of Laboratory Medicine, Karolinska Institute, 171 76 Solna, Sweden
- Institute for Transfusion Medicine, University Hospital Essen, University of Duisburg-Essen, 45141 Essen, Germany
| | - Samir El Andaloussi
- Biomolecular Medicine, Clinical Research Center, Department of Laboratory Medicine, Karolinska Institute, 171 76 Solna, Sweden
| | - Hanna Eriksson
- Department of Oncology-Pathology, Karolinska Institute, 171 77 Stockholm, Sweden
- Theme Cancer, Skin Cancer Center, Karolinska University Hospital, 171 77 Solna, Sweden
- Science for Life Laboratory, Solna, Tomtebodavägen 23, 171 65 Solna, Sweden
| | - Maria Pernemalm
- Department of Oncology-Pathology, Karolinska Institute, 171 77 Stockholm, Sweden
- Science for Life Laboratory, Solna, Tomtebodavägen 23, 171 65 Solna, Sweden
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2
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Nawara TJ, Yuan J, Seeley LD, Sztul E, Mattheyses AL. Fluidic shear stress alters clathrin dynamics and vesicle formation in endothelial cells. Biophys J 2024:S0006-3495(24)00390-4. [PMID: 38853434 DOI: 10.1016/j.bpj.2024.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 04/26/2024] [Accepted: 06/06/2024] [Indexed: 06/11/2024] Open
Abstract
Endothelial cells (ECs) experience a variety of highly dynamic mechanical stresses. Among others, cyclic stretch and increased plasma membrane tension inhibit clathrin-mediated endocytosis (CME) in non-ECs. It remains elusive how ECs maintain CME in these biophysically unfavorable conditions. Previously, we have used simultaneous two-wavelength axial ratiometry (STAR) microscopy to show that endocytic dynamics are similar between statically cultured human umbilical vein endothelial cells (HUVECs) and fibroblast-like Cos-7 cells. Here, we asked whether biophysical stresses generated by blood flow influence CME. We used our data processing platform-DrSTAR-to examine if clathrin dynamics are altered in HUVECs after experiencing fluidic shear stress (FSS). We found that HUVECs cultivated under a physiological level of FSS had increased clathrin dynamics compared with static controls. FSS increased both clathrin-coated vesicle formation and nonproductive flat clathrin lattices by 2.3-fold and 1.9-fold, respectively. The curvature-positive events had significantly delayed curvature initiation relative to clathrin recruitment in flow-stimulated cells, highlighting a shift toward flat-to-curved clathrin transitions in vesicle formation. Overall, our findings indicate that clathrin dynamics and clathrin-coated vesicle formation can be modulated by the local physiological environment and represent an important regulatory mechanism.
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Affiliation(s)
- Tomasz J Nawara
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jie Yuan
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Leslie D Seeley
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Alexa L Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama.
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3
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Johnson DH, Kou OH, Bouzos N, Zeno WF. Protein-membrane interactions: sensing and generating curvature. Trends Biochem Sci 2024; 49:401-416. [PMID: 38508884 PMCID: PMC11069444 DOI: 10.1016/j.tibs.2024.02.005] [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: 09/23/2023] [Revised: 02/20/2024] [Accepted: 02/23/2024] [Indexed: 03/22/2024]
Abstract
Biological membranes are integral cellular structures that can be curved into various geometries. These curved structures are abundant in cells as they are essential for various physiological processes. However, curved membranes are inherently unstable, especially on nanometer length scales. To stabilize curved membranes, cells can utilize proteins that sense and generate membrane curvature. In this review, we summarize recent research that has advanced our understanding of interactions between proteins and curved membrane surfaces, as well as work that has expanded our ability to study curvature sensing and generation. Additionally, we look at specific examples of cellular processes that require membrane curvature, such as neurotransmission, clathrin-mediated endocytosis (CME), and organelle biogenesis.
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Affiliation(s)
- David H Johnson
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089, USA
| | - Orianna H Kou
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
| | - Nicoletta Bouzos
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089, USA
| | - Wade F Zeno
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089, USA.
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4
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Vassilopoulos S, Montagnac G. Clathrin assemblies at a glance. J Cell Sci 2024; 137:jcs261674. [PMID: 38668719 DOI: 10.1242/jcs.261674] [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] [Indexed: 05/01/2024] Open
Abstract
Clathrin assembles into honeycomb-like lattices at the plasma membrane but also on internal membranes, such as at the Golgi and tubular endosomes. Clathrin assemblies primarily regulate the intracellular trafficking of different cargoes, but clathrin also has non-endocytic functions in cell adhesion through interactions with specific integrins, contributes to intraluminal vesicle formation by forming flat bilayered coats on endosomes and even assembles on kinetochore k-fibers during mitosis. In this Cell Science at a Glance article and the accompanying poster, we review our current knowledge on the different types of canonical and non-canonical membrane-associated clathrin assemblies in mammalian cells, as observed by thin-section or platinum replica electron microscopy in various cell types, and discuss how the structural plasticity of clathrin contributes to its functional diversity.
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Affiliation(s)
- Stéphane Vassilopoulos
- Sorbonne Université, Inserm U974, Institut de Myologie, Centre de Recherche en Myologie, 75013 Paris, France
| | - Guillaume Montagnac
- Inserm U1279, Gustave Roussy Institute, Université Paris-Saclay, 94800 Villejuif, France
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5
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Ashby G, Keng KE, Hayden CC, Stachowiak JC. A live cell imaging-based assay for tracking particle uptake by clathrin-mediated endocytosis. Methods Enzymol 2024; 700:413-454. [PMID: 38971609 DOI: 10.1016/bs.mie.2024.02.010] [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] [Indexed: 07/08/2024]
Abstract
A popular strategy for therapeutic delivery to cells and tissues is to encapsulate therapeutics inside particles that cells internalize via endocytosis. The efficacy of particle uptake by endocytosis is often studied in bulk using flow cytometry and Western blot analysis and confirmed using confocal microscopy. However, these techniques do not reveal the detailed dynamics of particle internalization and how the inherent heterogeneity of many types of particles may impact their endocytic uptake. Toward addressing these gaps, here we present a live-cell imaging-based method that utilizes total internal reflection fluorescence microscopy to track the uptake of a large ensemble of individual particles in parallel, as they interact with the cellular endocytic machinery. To analyze the resulting data, we employ an open-source tracking algorithm in combination with custom data filters. This analysis reveals the dynamic interactions between particles and endocytic structures, which determine the probability of particle uptake. In particular, our approach can be used to examine how variations in the physical properties of particles (size, targeting, rigidity), as well as heterogeneity within the particle population, impact endocytic uptake. These data impact the design of particles toward more selective and efficient delivery of therapeutics to cells.
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Affiliation(s)
- Grant Ashby
- Department of Biomedical Engineering, The University of Texas at Austin
| | - Kayla E Keng
- Department of Biomedical Engineering, The University of Texas at Austin
| | - Carl C Hayden
- Department of Biomedical Engineering, The University of Texas at Austin
| | - Jeanne C Stachowiak
- Department of Biomedical Engineering, The University of Texas at Austin; Department of Chemical Engineering, The University of Texas at Austin.
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6
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Nawara TJ, Sztul E, Mattheyses AL. Fluidic shear stress alters clathrin dynamics and vesicle formation in endothelial cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.02.572628. [PMID: 38260513 PMCID: PMC10802377 DOI: 10.1101/2024.01.02.572628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Endothelial cells (ECs) experience a variety of highly dynamic mechanical stresses. Among others, cyclic stretch and increased plasma membrane tension inhibit clathrin-mediated endocytosis (CME) in non-ECs cells. How ECs overcome such unfavorable, from biophysical perspective, conditions and maintain CME remains elusive. Previously, we have used simultaneous two-wavelength axial ratiometry (STAR) microscopy to show that endocytic dynamics are similar between statically cultured human umbilical vein endothelial cells (HUVECs) and fibroblast-like Cos-7 cells. Here we asked whether biophysical stresses generated by blood flow could favor one mechanism of clathrin-coated vesicle formation to overcome environment present in vasculature. We used our data processing platform - DrSTAR - to examine if clathrin dynamics are altered in HUVECs grown under fluidic sheer stress (FSS). Surprisingly, we found that FSS led to an increase in clathrin dynamics. In HUVECs grown under FSS we observed a 2.3-fold increase in clathrin-coated vesicle formation and a 1.9-fold increase in non-productive flat clathrin lattices compared to cells grown in static conditions. The curvature-positive events had significantly delayed curvature initiation in flow-stimulated cells, highlighting a shift toward flat-to-curved clathrin transitions in vesicle formation. Overall, our findings indicate that clathrin dynamics and CCV formation can be modulated by the local physiological environment and represents an important regulatory mechanism.
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Affiliation(s)
- Tomasz J. Nawara
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Alexa L. Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
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7
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Yan A, Chen X, He J, Ge Y, Liu Q, Men D, Xu K, Li D. Phosphorothioated DNA Engineered Liposomes as a General Platform for Stimuli-Responsive Cell-Specific Intracellular Delivery and Genome Editing. Angew Chem Int Ed Engl 2023; 62:e202303973. [PMID: 37100742 DOI: 10.1002/anie.202303973] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 04/18/2023] [Accepted: 04/26/2023] [Indexed: 04/28/2023]
Abstract
Intracellular protein delivery is highly desirable for protein drug-based cell therapy. Established technologies suffer from poor cell-specific cytosolic protein delivery, which hampers the targeting therapy of specific cell populations. A fusogenic liposome system enables cytosolic delivery, but its ability of cell-specific and controllable delivery is quite limited. Inspired by the kinetics of viral fusion, we designed a phosphorothioated DNA coatings-modified fusogenic liposome to mimic the function of viral hemagglutinin. The macromolecular fusion machine docks cargo-loaded liposomes at the membrane of target cells, triggers membrane fusion upon pH or UV light stimuli, and facilitates cytosolic protein delivery. Our results showed efficient cell-targeted delivery of proteins of various sizes and charges, indicating the phosphorothioated DNA plug-in unit on liposomes could be a general strategy for spatial-temporally controllable protein delivery both in vitro and in vivo.
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Affiliation(s)
- An Yan
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200241, China
| | - Xiaoqing Chen
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200241, China
| | - Jie He
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200241, China
| | - Yifan Ge
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 201210, China
| | - Qing Liu
- Rui Jin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Dong Men
- Guangzhou Laboratory, Guangzhou, 510005, China
| | - Ke Xu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Di Li
- School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200241, China
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8
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Nawara TJ, Mattheyses AL. Imaging nanoscale axial dynamics at the basal plasma membrane. Int J Biochem Cell Biol 2023; 156:106349. [PMID: 36566777 PMCID: PMC10634635 DOI: 10.1016/j.biocel.2022.106349] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/16/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022]
Abstract
Understanding of how energetically unfavorable plasma membrane shapes form, especially in the context of dynamic processes in living cells or tissues like clathrin-mediated endocytosis is in its infancy. Even though cutting-edge microscopy techniques that bridge this gap exist, they remain underused in biomedical sciences. Here, we demystify the perceived complexity of these advanced microscopy approaches and demonstrate their power in resolving nanometer axial dynamics in living cells. Total internal reflection fluorescence microscopy based approaches are the main focus of this review. We present clathrin-mediated endocytosis as a model system when describing the principles, data acquisition requirements, data interpretation strategies, and limitations of the described techniques. We hope this standardized description will bring the approaches for measuring nanoscale axial dynamics closer to the potential users and help in choosing the right approach to the right question.
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Affiliation(s)
- Tomasz J Nawara
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Alexa L Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA.
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9
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Nawara TJ, Dean WF, Mattheyses AL. DrSTAR: Tracking real-time nanometer axial changes. Biophys J 2023; 122:595-602. [PMID: 36659851 PMCID: PMC9989936 DOI: 10.1016/j.bpj.2023.01.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 11/23/2022] [Accepted: 01/17/2023] [Indexed: 01/21/2023] Open
Abstract
Protein interactions with the plasma membrane mediate processes critical for cell viability such as migration and endocytosis, yet our understanding of how recruitment of key proteins correlates with their ability to sense or induce energetically unfavorable plasma membrane shapes remains limited. Simultaneous two-wavelength axial ratiometry (STAR) microscopy provides millisecond time resolution and nanometer axial resolution of protein dynamics at the basal plasma membrane. However, STAR microscopy requires extensive and time-consuming quantitative data processing to access axial (Δz) information. Therefore, addressing questions about the influence of biological and biophysical factors on the interaction between the plasma membrane and protein of interest remains challenging. Here, we overcome the limitations in STAR data processing and present dynamic reference STAR (DrSTAR): a user-friendly, automated, open-source MATLAB-based package. DrSTAR enables processing multiple experimental conditions and biological replicates, employs a novel local background referencing algorithm, and accelerates processing time to facilitate broad adaptation of STAR for studying nanometer axial changes in protein distribution.
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Affiliation(s)
- Tomasz J Nawara
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - William F Dean
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Alexa L Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama.
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10
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Exocytosis of the silicified cell wall of diatoms involves extensive membrane disintegration. Nat Commun 2023; 14:480. [PMID: 36717559 PMCID: PMC9886994 DOI: 10.1038/s41467-023-36112-z] [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: 08/04/2021] [Accepted: 01/16/2023] [Indexed: 01/31/2023] Open
Abstract
Diatoms are unicellular algae characterized by silica cell walls. These silica elements are known to be formed intracellularly in membrane-bound silica deposition vesicles and exocytosed after completion. How diatoms maintain membrane homeostasis during the exocytosis of these large and rigid silica elements remains unknown. Here we study the membrane dynamics during cell wall formation and exocytosis in two model diatom species, using live-cell confocal microscopy, transmission electron microscopy and cryo-electron tomography. Our results show that during its formation, the mineral phase is in tight association with the silica deposition vesicle membranes, which form a precise mold of the delicate geometrical patterns. We find that during exocytosis, the distal silica deposition vesicle membrane and the plasma membrane gradually detach from the mineral and disintegrate in the extracellular space, without any noticeable endocytic retrieval or extracellular repurposing. We demonstrate that within the cell, the proximal silica deposition vesicle membrane becomes the new barrier between the cell and its environment, and assumes the role of a new plasma membrane. These results provide direct structural observations of diatom silica exocytosis, and point to an extraordinary mechanism in which membrane homeostasis is maintained by discarding, rather than recycling, significant membrane patches.
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11
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Kozlov MM, Taraska JW. Generation of nanoscopic membrane curvature for membrane trafficking. Nat Rev Mol Cell Biol 2023; 24:63-78. [PMID: 35918535 DOI: 10.1038/s41580-022-00511-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2022] [Indexed: 11/09/2022]
Abstract
Curved membranes are key features of intracellular organelles, and their generation involves dynamic protein complexes. Here we describe the fundamental mechanisms such as the hydrophobic insertion, scaffolding and crowding mechanisms these proteins use to produce membrane curvatures and complex shapes required to form intracellular organelles and vesicular structures involved in endocytosis and secretion. For each mechanism, we discuss its cellular functions as well as the underlying physical principles and the specific membrane properties required for the mechanism to be feasible. We propose that the integration of individual mechanisms into a highly controlled, robust process of curvature generation often relies on the assembly of proteins into coats. How cells unify and organize the curvature-generating factors at the nanoscale is presented for three ubiquitous coats central for membrane trafficking in eukaryotes: clathrin-coated pits, caveolae, and COPI and COPII coats. The emerging theme is that these coats arrange and coordinate curvature-generating factors in time and space to dynamically shape membranes to accomplish membrane trafficking within cells.
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Affiliation(s)
- Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
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12
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Cail RC, Drubin DG. Membrane curvature as a signal to ensure robustness of diverse cellular processes. Trends Cell Biol 2022; 33:427-441. [PMID: 36244874 DOI: 10.1016/j.tcb.2022.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 09/14/2022] [Accepted: 09/15/2022] [Indexed: 11/05/2022]
Abstract
An increasing corpus of research has demonstrated that membrane shape, generated either by the external environment of the cell or by intrinsic mechanisms such as cytokinesis and vesicle or organelle formation, is an important parameter in the control of diverse cellular processes. In this review we discuss recent findings that demonstrate how membrane curvature (from nanometer to micron length-scales) alters protein function. We describe an expanding toolkit for experimentally modulating membrane curvature to reveal effects on protein function, and discuss how membrane curvature - far from being a passive consequence of the physical environment and the internal protein activity of a cell - is an important signal that controls protein affinity and enzymatic activity to ensure robust forward progression of key processes within the cell.
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13
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Illuminating membrane structural dynamics of fusion and endocytosis with advanced light imaging techniques. Biochem Soc Trans 2022; 50:1157-1167. [PMID: 35960003 PMCID: PMC9444071 DOI: 10.1042/bst20210263] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/24/2022] [Accepted: 07/27/2022] [Indexed: 11/17/2022]
Abstract
Visualization of cellular dynamics using fluorescent light microscopy has become a reliable and indispensable source of experimental evidence for biological studies. Over the past two decades, the development of super-resolution microscopy platforms coupled with innovations in protein and molecule labeling led to significant biological findings that were previously unobservable due to the barrier of the diffraction limit. As a result, the ability to image the dynamics of cellular processes is vastly enhanced. These imaging tools are extremely useful in cellular physiology for the study of vesicle fusion and endocytosis. In this review, we will explore the power of stimulated emission depletion (STED) and confocal microscopy in combination with various labeling techniques in real-time observation of the membrane transformation of fusion and endocytosis, as well as their underlying mechanisms. We will review how STED and confocal imaging are used to reveal fusion and endocytic membrane transformation processes in live cells, including hemi-fusion; hemi-fission; hemi-to-full fusion; fusion pore opening, expansion, constriction and closure; shrinking or enlargement of the Ω-shape membrane structure after vesicle fusion; sequential compound fusion; and the sequential endocytic membrane transformation from flat- to O-shape via the intermediate Λ- and Ω-shape transition. We will also discuss how the recent development of imaging techniques would impact future studies in the field.
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