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Chao X, Yang Y, Gong W, Zou S, Tu H, Li D, Feng W, Cai H. Leep2A and Leep2B function as a RasGAP complex to regulate macropinosome formation. J Cell Biol 2024; 223:e202401110. [PMID: 38888895 PMCID: PMC11187982 DOI: 10.1083/jcb.202401110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 05/12/2024] [Accepted: 06/04/2024] [Indexed: 06/20/2024] Open
Abstract
Macropinocytosis mediates the non-selective bulk uptake of extracellular fluid, enabling cells to survey the environment and obtain nutrients. A conserved set of signaling proteins orchestrates the actin dynamics that lead to membrane ruffling and macropinosome formation across various eukaryotic organisms. At the center of this signaling network are Ras GTPases, whose activation potently stimulates macropinocytosis. However, how Ras signaling is initiated and spatiotemporally regulated during macropinocytosis is not well understood. By using the model system Dictyostelium and a proteomics-based approach to identify regulators of macropinocytosis, we uncovered Leep2, consisting of Leep2A and Leep2B, as a RasGAP complex. The Leep2 complex specifically localizes to emerging macropinocytic cups and nascent macropinosomes, where it modulates macropinosome formation by regulating the activities of three Ras family small GTPases. Deletion or overexpression of the complex, as well as disruption or sustained activation of the target Ras GTPases, impairs macropinocytic activity. Our data reveal the critical role of fine-tuning Ras activity in directing macropinosome formation.
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Affiliation(s)
- Xiaoting Chao
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yihong Yang
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Weibin Gong
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Songlin Zou
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Hui Tu
- Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Institute of Systems Biomedicine, Peking University Health Science Center, Peking University, Beijing, China
| | - Dong Li
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Wei Feng
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Huaqing Cai
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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Kay RR, Lutton JE, King JS, Bretschneider T. Making cups and rings: the 'stalled-wave' model for macropinocytosis. Biochem Soc Trans 2024:BST20231426. [PMID: 38934501 DOI: 10.1042/bst20231426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 05/29/2024] [Accepted: 06/07/2024] [Indexed: 06/28/2024]
Abstract
Macropinocytosis is a broadly conserved endocytic process discovered nearly 100 years ago, yet still poorly understood. It is prominent in cancer cell feeding, immune surveillance, uptake of RNA vaccines and as an invasion route for pathogens. Macropinocytic cells extend large cups or flaps from their plasma membrane to engulf droplets of medium and trap them in micron-sized vesicles. Here they are digested and the products absorbed. A major problem - discussed here - is to understand how cups are shaped and closed. Recently, lattice light-sheet microscopy has given a detailed description of this process in Dictyostelium amoebae, leading to the 'stalled-wave' model for cup formation and closure. This is based on membrane domains of PIP3 and active Ras and Rac that occupy the inner face of macropinocytic cups and are readily visible with suitable reporters. These domains attract activators of dendritic actin polymerization to their periphery, creating a ring of protrusive F-actin around themselves, thus shaping the walls of the cup. As domains grow, they drive a wave of actin polymerization across the plasma membrane that expands the cup. When domains stall, continued actin polymerization under the membrane, combined with increasing membrane tension in the cup, drives closure at lip or base. Modelling supports the feasibility of this scheme. No specialist coat proteins or contractile activities are required to shape and close cups: rings of actin polymerization formed around PIP3 domains that expand and stall seem sufficient. This scheme may be widely applicable and begs many biochemical questions.
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Affiliation(s)
- Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, U.K
| | - Judith E Lutton
- Department of Computer Science, University of Warwick, Coventry CV4 7AL, U.K
| | - Jason S King
- Department of Biomedical Sciences, Western Bank, Sheffield S10 2TN, U.K
| | - Till Bretschneider
- Department of Computer Science, University of Warwick, Coventry CV4 7AL, U.K
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3
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Cvrčková F, Ghosh R, Kočová H. Transmembrane formins as active cargoes of membrane trafficking. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:3668-3684. [PMID: 38401146 PMCID: PMC11194305 DOI: 10.1093/jxb/erae078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 02/23/2024] [Indexed: 02/26/2024]
Abstract
Formins are a large, evolutionarily old family of cytoskeletal regulators whose roles include actin capping and nucleation, as well as modulation of microtubule dynamics. The plant class I formin clade is characterized by a unique domain organization, as most of its members are transmembrane proteins with possible cell wall-binding motifs exposed to the extracytoplasmic space-a structure that appears to be a synapomorphy of the plant kingdom. While such transmembrane formins are traditionally considered mainly as plasmalemma-localized proteins contributing to the organization of the cell cortex, we review, from a cell biology perspective, the growing evidence that they can also, at least temporarily, reside (and in some cases also function) in endomembranes including secretory and endocytotic pathway compartments, the endoplasmic reticulum, the nuclear envelope, and the tonoplast. Based on this evidence, we propose that class I formins may thus serve as 'active cargoes' of membrane trafficking-membrane-embedded proteins that modulate the fate of endo- or exocytotic compartments while being transported by them.
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Affiliation(s)
- Fatima Cvrčková
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, CZ 128 43 Praha 2, Czechia
| | - Rajdeep Ghosh
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, CZ 128 43 Praha 2, Czechia
| | - Helena Kočová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, CZ 128 43 Praha 2, Czechia
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Xia D, Jiang D, Yu P, Jia K, Wang J, Shen D, Zhao Q, Lu C. Ras3 in Bombyx mori with antiviral function against B. mori nucleopolyhedrovirus. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 152:105114. [PMID: 38101715 DOI: 10.1016/j.dci.2023.105114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 12/06/2023] [Accepted: 12/10/2023] [Indexed: 12/17/2023]
Abstract
Bombyx mori ras protein3 (BmRas3) is a small molecular protein in the GTPase superfamily, which has the activity of binding guanosine nucleotides and GTP enzymes. It acts as a molecular switch by coupling extracellular signal to different cellular response through the conversion between Ras-GTP conformation and Ras-GDP conformation, thus regulating signal pathways responsible for cell growth, migration, adhesion, survival and differentiation. However, few studies have been done on Ras3 in silkworm, and its function and mechanism are unclear. In this study, we found that the overexpression of BmRas3 inhibited the infection of BmNPV(B. mori nucleopolyhedrovirus), while knockdown of BmRas3 could promote the infection of BmNPV. In addition, after the BmRas3 in silkworm larvae was knockdown, the anti-BmNPV ability of silkworm decreased and the survival rate of silkworm was affected. Additionly in the cells with BmRas3 overexpression, the transcription level of BmMapkk6 、BmP38、BmJNK、BmERK1/2 and BmERK5 were significantly increased after BmNPV infection, and the transcript levels of BmMapkk6、BmP38、BmJNK、BmERK1/2 and BmERK5 were also inhibited to varying degrees This is the first report on the antiviral effect of BmRas3 in silkworm, which provides a new direction for further study on the anti-BmNPV mechanism of silkworm and screening and cultivation of anti-BmNPV silkworm strain.
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Affiliation(s)
- Dingguo Xia
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212100, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu, 212018, China.
| | - Dan Jiang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212100, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu, 212018, China
| | - Pengcheng Yu
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212100, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu, 212018, China
| | - Kaifang Jia
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212100, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu, 212018, China
| | - Jinyang Wang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212100, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu, 212018, China
| | - Dongxu Shen
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212100, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu, 212018, China
| | - Qiaoling Zhao
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212100, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu, 212018, China
| | - Cheng Lu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, 400715, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, 400715, China
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5
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Putar D, Čizmar A, Chao X, Šimić M, Šoštar M, Ćutić T, Mijanović L, Smolko A, Tu H, Cosson P, Weber I, Cai H, Filić V. IqgC is a potent regulator of macropinocytosis in the presence of NF1 and its loading to macropinosomes is dependent on RasG. Open Biol 2024; 14:230372. [PMID: 38263885 PMCID: PMC10806400 DOI: 10.1098/rsob.230372] [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: 10/09/2023] [Accepted: 11/26/2023] [Indexed: 01/25/2024] Open
Abstract
RasG is a major regulator of macropinocytosis in Dictyostelium discoideum. Its activity is under the control of an IQGAP-related protein, IqgC, which acts as a RasG-specific GAP (GTPase activating protein). IqgC colocalizes with the active Ras at the macropinosome membrane during its formation and for some time after the cup closure. However, the loss of IqgC induces only a minor enhancement of fluid uptake in axenic cells that already lack another RasGAP, NF1. Here, we show that IqgC plays an important role in the regulation of macropinocytosis in the presence of NF1 by restricting the size of macropinosomes. We further provide evidence that interaction with RasG is indispensable for the recruitment of IqgC to forming macropinocytic cups. We also demonstrate that IqgC interacts with another small GTPase from the Ras superfamily, Rab5A, but is not a GAP for Rab5A. Since mammalian Rab5 plays a key role in early endosome maturation, we hypothesized that IqgC could be involved in macropinosome maturation via its interaction with Rab5A. Although an excessive amount of Rab5A reduces the RasGAP activity of IqgC in vitro and correlates with IqgC dissociation from endosomes in vivo, the physiological significance of the Rab5A-IqgC interaction remains elusive.
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Affiliation(s)
- Darija Putar
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Anja Čizmar
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Xiaoting Chao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101 Beijing, People's Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049 Beijing, People's Republic of China
| | - Marija Šimić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Marko Šoštar
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Tamara Ćutić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Lucija Mijanović
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Ana Smolko
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Hui Tu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101 Beijing, People's Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049 Beijing, People's Republic of China
| | - Pierre Cosson
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101 Beijing, People's Republic of China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049 Beijing, People's Republic of China
| | - Vedrana Filić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
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6
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Wei YN, Yan CY, Zhao ML, Zhao XH. The role and application of vesicles in triple-negative breast cancer: Opportunities and challenges. Mol Ther Oncolytics 2023; 31:100752. [PMID: 38130701 PMCID: PMC10733704 DOI: 10.1016/j.omto.2023.100752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023] Open
Abstract
Extracellular vesicles (EVs) carry DNA, RNA, protein, and other substances involved in intercellular crosstalk and can be used for the targeted delivery of drugs. Triple-negative breast cancer (TNBC) is rich in recurrent and metastatic disease and lacks therapeutic targets. Studies have proved the role of EVs in the different stages of the genesis and development of TNBC. Cancer cells actively secrete various biomolecules, which play a significant part establishing the tumor microenvironment via EVs. In this article, we describe the roles of EVs in the tumor immune microenvironment, metabolic microenvironment, and vascular remodeling, and summarize the application of EVs for objective delivery of chemotherapeutic drugs, immune antigens, and cancer vaccine adjuvants. EVs-based therapy may represent the next-generation tool for targeted drug delivery for the cure of a variety of diseases lacking effective drug treatment.
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Affiliation(s)
- Ya-Nan Wei
- Department of Clinical Oncology, Sheng jing Hospital of China Medical University, Shenyang 110022, People’s Republic of China
| | - Chun-Yan Yan
- Department of Clinical Oncology, Sheng jing Hospital of China Medical University, Shenyang 110022, People’s Republic of China
| | - Meng-Lu Zhao
- Department of Clinical Oncology, Sheng jing Hospital of China Medical University, Shenyang 110022, People’s Republic of China
| | - Xi-He Zhao
- Department of Clinical Oncology, Sheng jing Hospital of China Medical University, Shenyang 110022, People’s Republic of China
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Banerjee T, Matsuoka S, Biswas D, Miao Y, Pal DS, Kamimura Y, Ueda M, Devreotes PN, Iglesias PA. A dynamic partitioning mechanism polarizes membrane protein distribution. Nat Commun 2023; 14:7909. [PMID: 38036511 PMCID: PMC10689845 DOI: 10.1038/s41467-023-43615-2] [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: 02/24/2023] [Accepted: 11/14/2023] [Indexed: 12/02/2023] Open
Abstract
The plasma membrane is widely regarded as the hub of the numerous signal transduction activities. Yet, the fundamental biophysical mechanisms that spatiotemporally compartmentalize different classes of membrane proteins remain unclear. Using multimodal live-cell imaging, here we first show that several lipid-anchored membrane proteins are consistently depleted from the membrane regions where the Ras/PI3K/Akt/F-actin network is activated. The dynamic polarization of these proteins does not depend upon the F-actin-based cytoskeletal structures, recurring shuttling between membrane and cytosol, or directed vesicular trafficking. Photoconversion microscopy and single-molecule measurements demonstrate that these lipid-anchored molecules have substantially dissimilar diffusion profiles in different regions of the membrane which enable their selective segregation. When these diffusion coefficients are incorporated into an excitable network-based stochastic reaction-diffusion model, simulations reveal that the altered affinity mediated selective partitioning is sufficient to drive familiar propagating wave patterns. Furthermore, normally uniform integral and lipid-anchored membrane proteins partition successfully when membrane domain-specific peptides are optogenetically recruited to them. We propose "dynamic partitioning" as a new mechanism that can account for large-scale compartmentalization of a wide array of lipid-anchored and integral membrane proteins during various physiological processes where membrane polarizes.
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Affiliation(s)
- Tatsat Banerjee
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA.
| | - Satomi Matsuoka
- Laboratory for Cell Signaling Dynamics, RIKEN Center for Biosystems Dynamics Research, Suita, Osaka, Japan
- Laboratory of Single Molecule Biology, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Debojyoti Biswas
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Yuchuan Miao
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Dhiman Sankar Pal
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Yoichiro Kamimura
- Laboratory for Cell Signaling Dynamics, RIKEN Center for Biosystems Dynamics Research, Suita, Osaka, Japan
| | - Masahiro Ueda
- Laboratory for Cell Signaling Dynamics, RIKEN Center for Biosystems Dynamics Research, Suita, Osaka, Japan
- Laboratory of Single Molecule Biology, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Peter N Devreotes
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
| | - Pablo A Iglesias
- Department of Cell Biology and Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA.
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8
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Chen H, Hu Y, Yang G, Li P, Yin J, Feng X, Wu Q, Zhang J, Xiao B, Sui Z. Macropinocytosis in Gracilariopsis lemaneiformis (Rhodophyta). FRONTIERS IN PLANT SCIENCE 2023; 14:1225675. [PMID: 37822336 PMCID: PMC10562585 DOI: 10.3389/fpls.2023.1225675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 09/05/2023] [Indexed: 10/13/2023]
Abstract
Macropinocytosis is an endocytic process that plays an important role in animal development and disease occurrence but until now has been rarely reported in organisms with cell walls. We investigated the properties of endocytosis in a red alga, Gracilariopsis lemaneiformis. The cells non-selectively internalized extracellular fluid into large-scale endocytic vesicles (1.94 ± 0.51 μm), and this process could be inhibited by 5-(N-ethyl-N-isopropyl) amiloride, an macropinocytosis inhibitor. Moreover, endocytosis was driven by F-actin, which promotes formation of ruffles and cups from the cell surface and facilitates formation of endocytotic vesicles. After vesicle formation, endocytic vesicles could be acidified and acquire digestive function. These results indicated macropinocytosis in G. lemaneiformis. Abundant phosphatidylinositol kinase and small GTPase encoding genes were found in the genome of this alga, while PI3K, Ras, and Rab5, the important participators of traditional macropinocytosis, seem to be lacked. Such findings provide a new insight into endocytosis in organisms with cell walls and facilitate further research into the core regulatory mechanisms and evolution of macropinocytosis.
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Affiliation(s)
- Haihong Chen
- Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
- Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang, China
- Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, China
| | - Yiyi Hu
- Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
| | - Guanpin Yang
- Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
- Institutes of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China
| | - Pingping Li
- Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
| | - Jingru Yin
- Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
| | - Xiaoqing Feng
- Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
| | - Qiong Wu
- Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
| | - Jingyu Zhang
- Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
| | - Baoheng Xiao
- Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
| | - Zhenghong Sui
- Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
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9
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Lutton JE, Coker HLE, Paschke P, Munn CJ, King JS, Bretschneider T, Kay RR. Formation and closure of macropinocytic cups in Dictyostelium. Curr Biol 2023; 33:3083-3096.e6. [PMID: 37379843 PMCID: PMC7614961 DOI: 10.1016/j.cub.2023.06.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 05/05/2023] [Accepted: 06/05/2023] [Indexed: 06/30/2023]
Abstract
Macropinocytosis is a conserved endocytic process by which cells engulf droplets of medium into micron-sized vesicles. We use light-sheet microscopy to define an underlying set of principles by which macropinocytic cups are shaped and closed in Dictyostelium amoebae. Cups form around domains of PIP3 stretching almost to their lip and are supported by a specialized F-actin scaffold from lip to base. They are shaped by a ring of actin polymerization created by recruiting Scar/WAVE and Arp2/3 around PIP3 domains, but how cups evolve over time to close and form a vesicle is unknown. Custom 3D analysis shows that PIP3 domains expand from small origins, capturing new membrane into the cup, and crucially, that cups close when domain expansion stalls. We show that cups can close in two ways: either at the lip, by inwardly directed actin polymerization, or the base, by stretching and delamination of the membrane. This provides the basis for a conceptual mechanism whereby closure is brought about by a combination of stalled cup expansion, continued actin polymerization at the lip, and membrane tension. We test this through the use of a biophysical model, which can recapitulate both forms of cup closure and explain how 3D cup structures evolve over time to mediate engulfment.
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Affiliation(s)
- Judith E Lutton
- Department of Computer Science, University of Warwick, Coventry CV4 7AL, UK
| | - Helena L E Coker
- CAMDU, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | - Peggy Paschke
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | | | - Jason S King
- School of Biosciences, Western Bank, Sheffield S10 2TN, UK.
| | - Till Bretschneider
- Department of Computer Science, University of Warwick, Coventry CV4 7AL, UK.
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
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10
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Wang R, Lin Z, Zhou L, Chen C, Yu X, Zhang J, Zou Z, Lu Z. Rho 1 participates in parasitoid wasp eggs maturation and host cellular immunity inhibition. INSECT SCIENCE 2023; 30:677-692. [PMID: 36271788 DOI: 10.1111/1744-7917.13123] [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] [Received: 03/01/2022] [Revised: 09/21/2022] [Accepted: 09/27/2022] [Indexed: 06/15/2023]
Abstract
Endoparasitoid wasps introduce venom into their host insects during the egg-laying stage. Venom proteins play various roles in the host physiology, development, immunity, and behavior manipulation and regulation. In this study, we identified a venom protein, MmRho1, a small guanine nucleotide-binding protein derived from ovary in the endoparasitoid wasp Microplitis mediator and found that knockdown of its expression by RNA interference caused down-regulation of vitellogenin and juvenile hormone, egg production, and cocoons formation in the female wasps. We demonstrated that MmRho1 entered the cotton bollworm's (host) hemocytes and suppressed cellular immune responses after parasitism using immunofluorescence staining. Furthermore, wasp MmRho1 interacted with the cotton bollworm's actin cytoskeleton rearrangement regulator diaphanous by yeast 2-hybrid and glutathione s-transferase pull-down. In conclusion, this study indicates that MmRho1 plays dual roles in wasp development and the suppression of the host insect cellular immune responses.
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Affiliation(s)
- Ruijuan Wang
- Department of Entomology, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
| | - Zhe Lin
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Lizhen Zhou
- Department of Entomology, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
| | - Caihua Chen
- Department of Entomology, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
| | - Xianhao Yu
- Engineering Research Center of Natural Enemies, Institute of Biological Control, Jilin Agricultural University, Changchun, Jilin, China
| | - Junjie Zhang
- Engineering Research Center of Natural Enemies, Institute of Biological Control, Jilin Agricultural University, Changchun, Jilin, China
| | - Zhen Zou
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Zhiqiang Lu
- Department of Entomology, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
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11
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Banushi B, Joseph SR, Lum B, Lee JJ, Simpson F. Endocytosis in cancer and cancer therapy. Nat Rev Cancer 2023:10.1038/s41568-023-00574-6. [PMID: 37217781 DOI: 10.1038/s41568-023-00574-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/11/2023] [Indexed: 05/24/2023]
Abstract
Endocytosis is a complex process whereby cell surface proteins, lipids and fluid from the extracellular environment are packaged, sorted and internalized into cells. Endocytosis is also a mechanism of drug internalization into cells. There are multiple routes of endocytosis that determine the fate of molecules, from degradation in the lysosomes to recycling back to the plasma membrane. The overall rates of endocytosis and temporal regulation of molecules transiting through endocytic pathways are also intricately linked with signalling outcomes. This process relies on an array of factors, such as intrinsic amino acid motifs and post-translational modifications. Endocytosis is frequently disrupted in cancer. These disruptions lead to inappropriate retention of receptor tyrosine kinases on the tumour cell membrane, changes in the recycling of oncogenic molecules, defective signalling feedback loops and loss of cell polarity. In the past decade, endocytosis has emerged as a pivotal regulator of nutrient scavenging, response to and regulation of immune surveillance and tumour immune evasion, tumour metastasis and therapeutic drug delivery. This Review summarizes and integrates these advances into the understanding of endocytosis in cancer. The potential to regulate these pathways in the clinic to improve cancer therapy is also discussed.
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Affiliation(s)
- Blerida Banushi
- Frazer Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | - Shannon R Joseph
- Frazer Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | - Benedict Lum
- Frazer Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | - Jason J Lee
- Frazer Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | - Fiona Simpson
- Frazer Institute, University of Queensland, Woolloongabba, Queensland, Australia.
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12
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Salloum G, Bresnick AR, Backer JM. Macropinocytosis: mechanisms and regulation. Biochem J 2023; 480:335-362. [PMID: 36920093 DOI: 10.1042/bcj20210584] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/22/2023] [Accepted: 02/27/2023] [Indexed: 03/16/2023]
Abstract
Macropinocytosis is defined as an actin-dependent but coat- and dynamin-independent endocytic uptake process, which generates large intracellular vesicles (macropinosomes) containing a non-selective sampling of extracellular fluid. Macropinocytosis provides an important mechanism of immune surveillance by dendritic cells and macrophages, but also serves as an essential nutrient uptake pathway for unicellular organisms and tumor cells. This review examines the cell biological mechanisms that drive macropinocytosis, as well as the complex signaling pathways - GTPases, lipid and protein kinases and phosphatases, and actin regulatory proteins - that regulate macropinosome formation, internalization, and disposition.
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Affiliation(s)
- Gilbert Salloum
- Department of Molecular Pharamacology, Albert Einstein College of Medicine, Bronx, NY, U.S.A
| | - Anne R Bresnick
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, U.S.A
| | - Jonathan M Backer
- Department of Molecular Pharamacology, Albert Einstein College of Medicine, Bronx, NY, U.S.A
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, U.S.A
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13
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Hein JI, Scholz J, Körber S, Kaufmann T, Faix J. Unleashed Actin Assembly in Capping Protein-Deficient B16-F1 Cells Enables Identification of Multiple Factors Contributing to Filopodium Formation. Cells 2023; 12:cells12060890. [PMID: 36980231 PMCID: PMC10047565 DOI: 10.3390/cells12060890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/16/2023] Open
Abstract
Background: Filopodia are dynamic, finger-like actin-filament bundles that overcome membrane tension by forces generated through actin polymerization at their tips to allow extension of these structures a few microns beyond the cell periphery. Actin assembly of these protrusions is regulated by accessory proteins including heterodimeric capping protein (CP) or Ena/VASP actin polymerases to either terminate or promote filament growth. Accordingly, the depletion of CP in B16-F1 melanoma cells was previously shown to cause an explosive formation of filopodia. In Ena/VASP-deficient cells, CP depletion appeared to result in ruffling instead of inducing filopodia, implying that Ena/VASP proteins are absolutely essential for filopodia formation. However, this hypothesis was not yet experimentally confirmed. Methods: Here, we used B16-F1 cells and CRISPR/Cas9 technology to eliminate CP either alone or in combination with Ena/VASP or other factors residing at filopodia tips, followed by quantifications of filopodia length and number. Results: Unexpectedly, we find massive formations of filopodia even in the absence of CP and Ena/VASP proteins. Notably, combined inactivation of Ena/VASP, unconventional myosin-X and the formin FMNL3 was required to markedly impair filopodia formation in CP-deficient cells. Conclusions: Taken together, our results reveal that, besides Ena/VASP proteins, numerous other factors contribute to filopodia formation.
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Affiliation(s)
| | | | | | | | - Jan Faix
- Correspondence: ; Tel.: +49-511-532-2928
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14
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Körber S, Junemann A, Litschko C, Winterhoff M, Faix J. Convergence of Ras- and Rac-regulated formin pathways is pivotal for phagosome formation and particle uptake in Dictyostelium. Proc Natl Acad Sci U S A 2023; 120:e2220825120. [PMID: 36897976 PMCID: PMC10243128 DOI: 10.1073/pnas.2220825120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 02/03/2023] [Indexed: 03/12/2023] Open
Abstract
Macroendocytosis comprising phagocytosis and macropinocytosis is an actin-driven process regulated by small GTPases that depend on the dynamic reorganization of the membrane that protrudes and internalizes extracellular material by cup-shaped structures. To effectively capture, enwrap, and internalize their targets, these cups are arranged into a peripheral ring or ruffle of protruding actin sheets emerging from an actin-rich, nonprotrusive zone at its base. Despite extensive knowledge of the mechanism driving actin assembly of the branched network at the protrusive cup edge, which is initiated by the actin-related protein (Arp) 2/3 complex downstream of Rac signaling, our understanding of actin assembly in the base is still incomplete. In the Dictyostelium model system, the Ras-regulated formin ForG was previously shown to specifically contribute to actin assembly at the cup base. Loss of ForG is associated with a strongly impaired macroendocytosis and a 50% reduction in F-actin content at the base of phagocytic cups, in turn indicating the presence of additional factors that specifically contribute to actin formation at the base. Here, we show that ForG synergizes with the Rac-regulated formin ForB to form the bulk of linear filaments at the cup base. Consistently, combined loss of both formins virtually abolishes cup formation and leads to severe defects of macroendocytosis, emphasizing the relevance of converging Ras- and Rac-regulated formin pathways in assembly of linear filaments in the cup base, which apparently provide mechanical support to the entire structure. Remarkably, we finally show that active ForB, unlike ForG, additionally drives phagosome rocketing to aid particle internalization.
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Affiliation(s)
- Sarah Körber
- Institute for Biophysical Chemistry, Hannover Medical School, 30625Hannover, Germany
| | - Alexander Junemann
- Institute for Biophysical Chemistry, Hannover Medical School, 30625Hannover, Germany
| | - Christof Litschko
- Institute for Biophysical Chemistry, Hannover Medical School, 30625Hannover, Germany
| | - Moritz Winterhoff
- Institute for Biophysical Chemistry, Hannover Medical School, 30625Hannover, Germany
| | - Jan Faix
- Institute for Biophysical Chemistry, Hannover Medical School, 30625Hannover, Germany
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15
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Banerjee T, Matsuoka S, Biswas D, Miao Y, Pal DS, Kamimura Y, Ueda M, Devreotes PN, Iglesias PA. A dynamic partitioning mechanism polarizes membrane protein distribution. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.03.522496. [PMID: 36712016 PMCID: PMC9881856 DOI: 10.1101/2023.01.03.522496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The plasma membrane is widely regarded as the hub of the signal transduction network activities that drives numerous physiological responses, including cell polarity and migration. Yet, the symmetry breaking process in the membrane, that leads to dynamic compartmentalization of different proteins, remains poorly understood. Using multimodal live-cell imaging, here we first show that multiple endogenous and synthetic lipid-anchored proteins, despite maintaining stable tight association with the inner leaflet of the plasma membrane, were unexpectedly depleted from the membrane domains where the signaling network was spontaneously activated such as in the new protrusions as well as within the propagating ventral waves. Although their asymmetric patterns resembled those of standard peripheral "back" proteins such as PTEN, unlike the latter, these lipidated proteins did not dissociate from the membrane upon global receptor activation. Our experiments not only discounted the possibility of recurrent reversible translocation from membrane to cytosol as it occurs for weakly bound peripheral membrane proteins, but also ruled out the necessity of directed vesicular trafficking and cytoskeletal supramolecular structure-based restrictions in driving these dynamic symmetry breaking events. Selective photoconversion-based protein tracking assays suggested that these asymmetric patterns instead originate from the inherent ability of these membrane proteins to "dynamically partition" into distinct domains within the plane of the membrane. Consistently, single-molecule measurements showed that these lipid-anchored molecules have substantially dissimilar diffusion profiles in different regions of the membrane. When these profiles were incorporated into an excitable network-based stochastic reaction-diffusion model of the system, simulations revealed that our proposed "dynamic partitioning" mechanism is sufficient to give rise to familiar asymmetric propagating wave patterns. Moreover, we demonstrated that normally uniform integral and lipid-anchored membrane proteins in Dictyostelium and mammalian neutrophil cells can be induced to partition spatiotemporally to form polarized patterns, by optogenetically recruiting membrane domain-specific peptides to these proteins. Together, our results indicate "dynamic partitioning" as a new mechanism of plasma membrane organization, that can account for large-scale compartmentalization of a wide array of lipid-anchored and integral membrane proteins in different physiological processes.
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16
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Xu X, Pots H, Gilsbach BK, Parsons D, Veltman DM, Ramachandra SG, Li H, Kortholt A, Jin T. C2GAP2 is a common regulator of Ras signaling for chemotaxis, phagocytosis, and macropinocytosis. Front Immunol 2022; 13:1075386. [PMID: 36524124 PMCID: PMC9745196 DOI: 10.3389/fimmu.2022.1075386] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 11/16/2022] [Indexed: 11/30/2022] Open
Abstract
Phagocytosis, macropinocytosis, and G protein coupled receptor-mediated chemotaxis are Ras-regulated and actin-driven processes. The common regulator for Ras activity in these three processes remains unknown. Here, we show that C2GAP2, a Ras GTPase activating protein, highly expressed in the vegetative growth state in model organism Dictyostelium. C2GAP2 localizes at the leading edge of chemotaxing cells, phagosomes during phagocytosis, and macropinosomes during micropinocytosis. c2gapB- cells lacking C2GAP2 displayed increased Ras activation upon folic acid stimulation and subsequent impaired chemotaxis in the folic acid gradient. In addition, c2gaB- cells have elevated phagocytosis and macropinocytosis, which subsequently results in faster cell growth. C2GAP2 binds multiple phospholipids on the plasma membrane and the membrane recruitment of C2GAP2 requires calcium. Taken together, we show a shared negative regulator of Ras signaling that mediates Ras signaling for chemotaxis, phagocytosis, and macropinocytosis.
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Affiliation(s)
- Xuehua Xu
- Chemotaxis Signaling Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States,*Correspondence: Xuehua Xu,
| | - Henderikus Pots
- Department of Cell Biochemistry, University of Groningen, Groningen, Netherlands
| | - Bernd K. Gilsbach
- Functional Neuroproteomics and Translational Biomarkers in Neurodegenerative Diseases German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Dustin Parsons
- Chemotaxis Signaling Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
| | - Douwe M. Veltman
- Department of Cell Biochemistry, University of Groningen, Groningen, Netherlands
| | - Sharmila G. Ramachandra
- Chemotaxis Signaling Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
| | - Haoran Li
- Chemotaxis Signaling Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
| | - Arjan Kortholt
- Department of Cell Biochemistry, University of Groningen, Groningen, Netherlands
| | - Tian Jin
- Chemotaxis Signaling Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
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17
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Dynamics of Actin Cytoskeleton and Their Signaling Pathways during Cellular Wound Repair. Cells 2022; 11:cells11193166. [PMID: 36231128 PMCID: PMC9564287 DOI: 10.3390/cells11193166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/27/2022] [Accepted: 10/01/2022] [Indexed: 11/17/2022] Open
Abstract
The repair of wounded cell membranes is essential for cell survival. Upon wounding, actin transiently accumulates at the wound site. The loss of actin accumulation leads to cell death. The mechanism by which actin accumulates at the wound site, the types of actin-related proteins participating in the actin remodeling, and their signaling pathways are unclear. We firstly examined how actin accumulates at a wound site in Dictyostelium cells. Actin assembled de novo at the wound site, independent of cortical flow. Next, we searched for actin- and signal-related proteins targeting the wound site. Fourteen of the examined proteins transiently accumulated at different times. Thirdly, we performed functional analyses using gene knockout mutants or specific inhibitors. Rac, WASP, formin, the Arp2/3 complex, profilin, and coronin contribute to the actin dynamics. Finally, we found that multiple signaling pathways related to TORC2, the Elmo/Doc complex, PIP2-derived products, PLA2, and calmodulin are involved in the actin dynamics for wound repair.
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18
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Griffiths G, Gruenberg J, Marsh M, Wohlmann J, Jones AT, Parton RG. Nanoparticle entry into cells; the cell biology weak link. Adv Drug Deliv Rev 2022; 188:114403. [PMID: 35777667 DOI: 10.1016/j.addr.2022.114403] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 06/22/2022] [Accepted: 06/23/2022] [Indexed: 12/22/2022]
Abstract
Nanoparticles (NP) are attractive options for the therapeutic delivery of active pharmaceutical drugs, proteins and nucleic acids into cells, tissues and organs. Research into the development and application of NP most often starts with a diverse group of scientists, including chemists, bioengineers and material and pharmaceutical scientists, who design, fabricate and characterize NP in vitro (Stage 1). The next step (Stage 2) generally investigates cell toxicity as well as the processes by which NP bind, are internalized and deliver their cargo to appropriate model tissue culture cells. Subsequently, in Stage 3, selected NP are tested in animal systems, mostly mouse. Whereas the chemistry-based development and analysis in Stage 1 is increasingly sophisticated, the investigations in Stage 2 are not what could be regarded as 'state-of-the-art' for the cell biology field and the quality of research into NP interactions with cells is often sub-standard. In this review we describe our current understanding of the mechanisms by which particles gain entry into mammalian cells via endocytosis. We summarize the most important areas for concern, highlight some of the most common mis-conceptions, and identify areas where NP scientists could engage with trained cell biologists. Our survey of the different mechanisms of uptake into cells makes us suspect that claims for roles for caveolae, as well as macropinocytosis, in NP uptake into cells have been exaggerated, whereas phagocytosis has been under-appreciated.
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Affiliation(s)
- Gareth Griffiths
- Department Biosciences, University of Oslo, Blindernveien 31, PO Box 1041, 0316 Oslo, Norway.
| | - Jean Gruenberg
- Department of Biochemistry, University of Geneva, 30 quai E. Ansermet, 1211-Geneva-4, Switzerland
| | - Mark Marsh
- Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Jens Wohlmann
- Department Biosciences, University of Oslo, Blindernveien 31, PO Box 1041, 0316 Oslo, Norway
| | - Arwyn T Jones
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, Cardiff, Wales CF103NB, UK
| | - Robert G Parton
- Institute for Molecular Bioscience and Centre for Microscopy and Microanalysis, The University of Queensland, Qld 4072, Australia
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19
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Exploration of Deformation of F-Actin during Macropinocytosis by Confocal Microscopy and 3D-Structured Illumination Microscopy. PHOTONICS 2022. [DOI: 10.3390/photonics9070461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Since their invention, confocal microscopy and super-resolution microscopy have become important choices in cell biology research. Macropinocytosis is a critical form of endocytosis. Deformation of the cell membrane is thought to be closely related to the movement of F-actin during macropinocytosis. However, it is still unclear how the morphology of F-actin and the membrane change during this process. In this study, confocal microscopy was utilized for macroscopic time-series imaging of the cell membranes and F-actin in cells induced by phorbol 12-myristate 13-acetate (PMA). Super-resolution structured illumination microscopy (SIM), which can overcome the diffraction limit, was used to demonstrate the morphological characteristics of F-actin filaments. Benefiting from the advantages of SIM in terms of resolution and 3D imaging, we speculated on the regular pattern of the deformation of F-actin during macropinocytosis. The detailed visualization of structures also helped to validate the speculation regarding the role of F-actin filaments in macropinocytosis in previous studies. The results obtained in this study will provide a better understanding of the mechanisms underlying macropinocytosis and endocytosis.
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20
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Apte A, Manich M, Labruyère E, Datta S. PI Kinase-EhGEF2-EhRho5 axis contributes to LPA stimulated macropinocytosis in Entamoeba histolytica. PLoS Pathog 2022; 18:e1010550. [PMID: 35594320 PMCID: PMC9173640 DOI: 10.1371/journal.ppat.1010550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 06/07/2022] [Accepted: 04/26/2022] [Indexed: 12/04/2022] Open
Abstract
Entamoeba histolytica is a protozoan responsible for several pathologies in humans. Trophozoites breach the intestinal site to enter the bloodstream and thus traverse to a secondary site. Macropinocytosis and phagocytosis, collectively accounting for heterophagy, are the two major processes responsible for sustenance of Entamoeba histolytica within the host. Both of these processes require significant rearrangements in the structure to entrap the target. Rho GTPases play an indispensable role in mustering proteins that regulate cytoskeletal remodelling. Unlike phagocytosis which has been studied in extensive detail, information on machinery of macropinocytosis in E. histolytica is still limited. In the current study, using site directed mutagenesis and RNAi based silencing, coupled with functional studies, we have demonstrated the involvement of EhRho5 in constitutive and LPA stimulated macropinocytosis. We also report that LPA, a bioactive phospholipid present in the bloodstream of the host, activates EhRho5 and translocates it from cytosol to plasma membrane and endomembrane compartments. Using biochemical and FRAP studies, we established that a PI Kinase acts upstream of EhRho5 in LPA mediated signalling. We further identified EhGEF2 as a guanine nucleotide exchange factor of EhRho5. In the amoebic trophozoites, EhGEF2 depletion leads to reduced macropinocytic efficiency of trophozoites, thus phenocopying its substrate. Upon LPA stimulation, EhGEF2 is found to sequester near the plasma membrane in a wortmannin sensitive fashion, explaining a possible mode for activation of EhRho5 in the amoebic trophozoites. Collectively, we propose that LPA stimulated macropinocytosis in E. histolytica is driven by the PI Kinase-EhGEF2-EhRho5 axis. Entamoeba histolytica is an enteric parasite in humans, which leads to various pathologies like dysentery, diarrhoea and abscess formation. Host cells are known to secrete chemokines and growth factors, which are utilized by trophozoites for sustenance and pathogenesis. The sustenance of this parasite within the host requires nutrient uptake, which involves macropinocytosis and phagocytosis. However, the regulation of macropinocytosis is less explored in E. histolytica. We have established for the first time that constitutive as well as LPA stimulated macropinocytosis in amoebic trophozoites functions via PI Kinase-EhGEF2-EhRho5 axis. We also excavated the dynamicity and the spatio-temporal regulation of EhRho5 activity and the associated dynamics in the LPA stimulated cells.
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Affiliation(s)
- Achala Apte
- Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh, India
| | - Maria Manich
- Bioimage Analysis Unit, Institut Pasteur, Paris, France
| | | | - Sunando Datta
- Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh, India
- * E-mail:
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21
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Tu H, Wang Z, Yuan Y, Miao X, Li D, Guo H, Yang Y, Cai H. The PripA-TbcrA complex-centered Rab GAP cascade facilitates macropinosome maturation in Dictyostelium. Nat Commun 2022; 13:1787. [PMID: 35379834 PMCID: PMC8980073 DOI: 10.1038/s41467-022-29503-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 03/18/2022] [Indexed: 02/07/2023] Open
Abstract
AbstractMacropinocytosis, an evolutionarily conserved mechanism mediating nonspecific bulk uptake of extracellular fluid, has been ascribed diverse functions. How nascent macropinosomes mature after internalization remains largely unknown. By searching for proteins that localize on macropinosomes during the Rab5-to-Rab7 transition stage in Dictyostelium, we uncover a complex composed of two proteins, which we name PripA and TbcrA. We show that the Rab5-to-Rab7 conversion involves fusion of Rab5-marked early macropinosomes with Rab7-marked late macropinosomes. PripA links the two membrane compartments by interacting with PI(3,4)P2 and Rab7. In addition, PripA recruits TbcrA, which acts as a GAP, to turn off Rab5. Thus, the conversion to Rab7 is linked to inactivation of the upstream Rab5. Consistently, disruption of either pripA or tbcrA impairs Rab5 inactivation and macropinocytic cargo processing. Therefore, the PripA-TbcrA complex is the central component of a Rab GAP cascade that facilitates programmed Rab switch and efficient cargo trafficking during macropinosome maturation.
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22
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Zhang Y, Tu H, Hao Y, Li D, Yang Y, Yuan Y, Guo Z, Li L, Wang H, Cai H. Oligopeptide transporter Slc15A modulates macropinocytosis in Dictyostelium by maintaining intracellular nutrient status. J Cell Sci 2022; 135:274929. [PMID: 35267018 DOI: 10.1242/jcs.259450] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 03/02/2022] [Indexed: 11/20/2022] Open
Abstract
Macropinocytosis mediates non-selective bulk uptake of extracellular fluid. It is the major route by which axenic Dictyostelium cells obtain nutrients and has emerged as a nutrient-scavenging pathway for mammalian cells. How environmental and cellular nutrient status modulates macropinocytic activity is not well understood. By developing a high-content imaging-based genetic screen in Dictyostelium, we identified Slc15A, an oligopeptide transporter localized at the plasma membrane and early macropinosome, as a novel macropinocytosis regulator. We show that deletion of slc15A, but not two other related slc15 genes, leads to reduced macropinocytosis, slower cell growth, and aberrantly increased autophagy in cells grown in nutrient-rich medium. Expression of Slc15A or supplying cells with free amino acids rescues these defects. In contrast, expression of transport-defective Slc15A or supplying cells with amino acids in their di-peptide forms fails to rescue these defects. Therefore, Slc15A modulates the level of macropinocytosis by maintaining the intracellular availability of key amino acids via oligopeptide extraction from the early macropinocytic pathway. We propose that Slc15A constitutes part of a positive feedback mechanism coupling cellular nutrient status and macropinocytosis.
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Affiliation(s)
- Yiwei Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hui Tu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yazhou Hao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dong Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Yihong Yang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Ye Yuan
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhonglong Guo
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
| | - Lei Li
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
| | - Haibin Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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23
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Li D, Sun F, Yang Y, Tu H, Cai H. Gradients of PI(4,5)P2 and PI(3,5)P2 Jointly Participate in Shaping the Back State of Dictyostelium Cells. Front Cell Dev Biol 2022; 10:835185. [PMID: 35186938 PMCID: PMC8855053 DOI: 10.3389/fcell.2022.835185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
Polarity, which refers to the molecular or structural asymmetry in cells, is essential for diverse cellular functions. Dictyostelium has proven to be a valuable system for dissecting the molecular mechanisms of cell polarity. Previous studies in Dictyostelium have revealed a range of signaling and cytoskeletal proteins that function at the leading edge to promote pseudopod extension and migration. In contrast, how proteins are localized to the trailing edge is not well understood. By screening for asymmetrically localized proteins, we identified a novel trailing-edge protein we named Teep1. We show that a charged surface formed by two pleckstrin homology (PH) domains in Teep1 is necessary and sufficient for targeting it to the rear of cells. Combining biochemical and imaging analyses, we demonstrate that Teep1 interacts preferentially with PI(4,5)P2 and PI(3,5)P2in vitro and simultaneous elimination of these lipid species in cells blocks the membrane association of Teep1. Furthermore, a leading-edge localized myotubularin phosphatase likely mediates the removal of PI(3,5)P2 from the front, as well as the formation of a back-to-front gradient of PI(3,5)P2. Together our data indicate that PI(4,5)P2 and PI(3,5)P2 on the plasma membrane jointly participate in shaping the back state of Dictyostelium cells.
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Affiliation(s)
- Dong Li
- School of Life Sciences, University of Science and Technology of China, Hefei, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Feifei Sun
- School of Life Sciences, University of Science and Technology of China, Hefei, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yihong Yang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hui Tu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Huaqing Cai,
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24
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Abstract
The distinct movements of macropinosome formation and maturation have corresponding biochemical activities which occur in a defined sequence of stages and transitions between those stages. Each stage in the process is regulated by variously phosphorylated derivatives of phosphatidylinositol (PtdIns) which reside in the cytoplasmic face of the membrane lipid bilayer. PtdIns derivatives phosphorylated at the 3' position of the inositol moiety, called 3' phosphoinositides (3'PIs), regulate different stages of the sequence. 3'PIs are synthesized by numerous phosphoinositide 3'-kinases (PI3K) and other lipid kinases and phosphatases, which are themselves regulated by small GTPases of the Ras superfamily. The combined actions of these enzymes localize four principal species of 3'PI to distinct domains of the plasma membrane or to discrete organelles, with distinct biochemical activities confined to those domains. Phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3) and phosphatidylinositol (3,4)-bisphosphate (PtdIns(3,4)P2) regulate the early stages of macropinosome formation, which include cell surface ruffling and constrictions of circular ruffles which close into macropinosomes. Phosphatidylinositol 3-phosphate (PtdIns3P) regulates macropinosome fusion with other macropinosomes and early endocytic organelles. Phosphatidylinositol (3,5)-bisphosphate (PtdIns(3,5)P2) mediates macropinosome maturation and shrinkage, through loss of ions and water, and subsequent traffic to lysosomes. The different characteristic rates of macropinocytosis in different cell types indicate levels of regulation which may be governed by the cell's capacity to generate 3'PIs.
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Affiliation(s)
- Joel A Swanson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA.
| | - Nobukazu Araki
- Department of Histology and Cell Biology, School of Medicine, Kagawa University, Miki, Kagawa, Japan
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25
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Kay RR, Lutton J, Coker H, Paschke P, King JS, Bretschneider T. The Amoebal Model for Macropinocytosis. Subcell Biochem 2022; 98:41-59. [PMID: 35378702 DOI: 10.1007/978-3-030-94004-1_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Macropinocytosis is a relatively unexplored form of large-scale endocytosis driven by the actin cytoskeleton. Dictyostelium amoebae form macropinosomes from cups extended from the plasma membrane, then digest their contents and absorb the nutrients in the endo-lysosomal system. They use macropinocytosis for feeding, maintaining a high rate of fluid uptake that makes assay and experimentation easy. Mutants collected over the years identify cytoskeletal and signalling proteins required for macropinocytosis. Cups are organized around plasma membrane domains of intense PIP3, Ras and Rac signalling, proper formation of which also depends on the RasGAPs NF1 and RGBARG, PTEN, the PIP3-regulated protein kinases Akt and SGK and their activators PDK1 and TORC2, Rho proteins, plus other components yet to be identified. This PIP3 domain directs dendritic actin polymerization to the extending lip of macropinocytic cups by recruiting a ring of the SCAR/WAVE complex around itself and thus activating the Arp2/3 complex. The dynamics of PIP3 domains are proposed to shape macropinocytic cups from start to finish. The role of the Ras-PI3-kinase module in organizing feeding structures in unicellular organisms most likely predates its adoption into growth factor signalling, suggesting an evolutionary origin for growth factor signalling.
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Affiliation(s)
- Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge, UK.
| | - Josiah Lutton
- Department of Computer Science, University of Warwick, Coventry, UK
| | - Helena Coker
- Warwick Medical School, University of Warwick, Coventry, UK
| | - Peggy Paschke
- MRC Laboratory of Molecular Biology, Cambridge, UK.,Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, UK
| | - Jason S King
- School of Biomedical Sciences, University of Sheffield, Sheffield, UK
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26
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aVASP boosts protrusive activity of macroendocytic cups and drives phagosome rocketing after internalization. Eur J Cell Biol 2022; 101:151200. [DOI: 10.1016/j.ejcb.2022.151200] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 12/29/2022] Open
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27
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Mazheika IS, Kamzolkina OV. Does macrovesicular endocytosis occur in fungal hyphae? FUNGAL BIOL REV 2021. [DOI: 10.1016/j.fbr.2021.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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28
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mDia1 Assembles a Linear F-Actin Coat at Membrane Invaginations To Drive Listeria monocytogenes Cell-to-Cell Spreading. mBio 2021; 12:e0293921. [PMID: 34781738 PMCID: PMC8593688 DOI: 10.1128/mbio.02939-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Direct cell-to-cell spreading of Listeria monocytogenes requires the bacteria to induce actin-based finger-like membrane protrusions in donor host cells that are endocytosed through caveolin-rich membrane invaginations by adjacent receiving cells. An actin shell surrounds these endocytic sites; however, its structure, composition, and functional significance remain elusive. Here, we show that the formin mDia1, but surprisingly not the Arp2/3 complex, is enriched at the membrane invaginations generated by L. monocytogenes during HeLa and Jeg-3 cell infections. Electron microscopy reveals a band of linear actin filaments that run along the longitudinal axis of the invagination membrane. Mechanistically, mDia1 expression is vital for the assembly of this F-actin shell. mDia1 is also required for the recruitment of Filamin A, a caveola-associated F-actin cross-linking protein, and caveolin-1 to the invaginations. Importantly, mixed-cell infection assays show that optimal caveolin-based L. monocytogenes cell-to-cell spreading correlates with the formation of the linear actin filament-containing shell by mDia1. IMPORTANCE Listeria monocytogenes spreads from one cell to another to colonize tissues. This cell-to-cell movement requires the propulsive force of an actin-rich comet tail behind the advancing bacterium, which ultimately distends the host plasma membrane into a slender bacterium-containing membrane protrusion. These membrane protrusions induce a corresponding invagination in the membrane of the adjacent host cell. The host cell that receives the protrusion utilizes caveolin-based endocytosis to internalize the structures, and filamentous actin lines these membrane invaginations. Here, we set out to determine the structure and function of this filamentous actin "shell." We demonstrate that the formin mDia1, but not the Arp2/3 complex, localizes to the invaginations. Morphologically, we show that this actin is organized into linear arrays and not branched dendritic networks. Mechanistically, we show that the actin shell is assembled by mDia1 and that mDia1 is required for efficient cell-to-cell transfer of L. monocytogenes.
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29
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Williams RSB, Chubb JR, Insall R, King JS, Pears CJ, Thompson E, Weijer CJ. Moving the Research Forward: The Best of British Biology Using the Tractable Model System Dictyostelium discoideum. Cells 2021; 10:3036. [PMID: 34831258 PMCID: PMC8616412 DOI: 10.3390/cells10113036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 11/01/2021] [Accepted: 11/03/2021] [Indexed: 12/19/2022] Open
Abstract
The social amoeba Dictyostelium discoideum provides an excellent model for research across a broad range of disciplines within biology. The organism diverged from the plant, yeast, fungi and animal kingdoms around 1 billion years ago but retains common aspects found in these kingdoms. Dictyostelium has a low level of genetic complexity and provides a range of molecular, cellular, biochemical and developmental biology experimental techniques, enabling multidisciplinary studies to be carried out in a wide range of areas, leading to research breakthroughs. Numerous laboratories within the United Kingdom employ Dictyostelium as their core research model. This review introduces Dictyostelium and then highlights research from several leading British research laboratories, covering their distinct areas of research, the benefits of using the model, and the breakthroughs that have arisen due to the use of Dictyostelium as a tractable model system.
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Affiliation(s)
- Robin S. B. Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Jonathan R. Chubb
- UCL Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK;
| | - Robert Insall
- Institute of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow G61 1QH, UK;
| | - Jason S. King
- School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK;
| | - Catherine J. Pears
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK;
| | - Elinor Thompson
- School of Science, University of Greenwich, Chatham Maritime, Chatham ME4 4TB, UK;
| | - Cornelis J. Weijer
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK;
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30
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Wang S, Zhang N, Di J, Zhao W, Shi G, Xie R, Hu B, Yang H. Analysis of the effects of magnetic levitation to simulate microgravity environment on the Arp2/3 complex pathway in macrophage. J Biol Phys 2021; 47:323-335. [PMID: 34533653 PMCID: PMC8452804 DOI: 10.1007/s10867-021-09581-w] [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: 05/27/2021] [Accepted: 08/13/2021] [Indexed: 11/28/2022] Open
Abstract
With dwindling natural resources on earth, current and future generations will need to explore space to new planets that will require travel under no or varying gravity conditions. Hence, long-term space missions and anticipated impacts on human biology such as changes in immune function are of growing research interest. Here, we reported new findings on mechanisms of immune response to microgravity with a focus on macrophage as a cellular model. We employed a superconducting magnet to generate a simulated microgravity environment and evaluated the effects of simulated microgravity on RAW 264.7 mouse macrophage cell line in three time frames: 8, 24, and 48 h. As study endpoints, we measured cell viability, phagocytosis, and used next-generation sequencing to explore its changing mechanism. Macrophage cell viability and phagocytosis both showed a marked decrease under microgravity. The differentially expressed genes (DEG) were identified in two ways: (1) gravity-dependent DEG, compared μg samples and 1 g samples at each time point; (2) time-dependent DEG, compared time-point samples within the same gravitational field. Through transcriptome analysis and confirmed by molecular biological verification, our findings firstly suggest that microgravity might affect macrophage phagocytosis by targeting Arp2/3 complex involved cytoskeleton synthesis and causing macrophage immune dysfunction. Our findings contribute to an emerging body of scholarship on biological effects of space travel.
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Affiliation(s)
- Sufang Wang
- School of Life Sciences, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi, 710072, China
- Center of Special Environmental Biomechanics & Biomedical Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi, 710072, China
| | - Nu Zhang
- School of Life Sciences, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi, 710072, China
- Center of Special Environmental Biomechanics & Biomedical Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi, 710072, China
| | - Jianglei Di
- Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an, Shaanxi, 710072, China
| | - Wenjuan Zhao
- School of Life Sciences, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi, 710072, China
- Center of Special Environmental Biomechanics & Biomedical Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi, 710072, China
| | - Guolin Shi
- School of Life Sciences, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi, 710072, China
- Center of Special Environmental Biomechanics & Biomedical Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi, 710072, China
| | - Ruiheng Xie
- Department of Computer and Information Science, College of Engineering, University of Delaware, Newark, DE, 19716, USA
| | - Bohan Hu
- College of Innovation and Experiment, Yangling Demonstration Area, Northwest A&F University, 22 Xinong Road, Xianyang City, Shaanxi Province, 712100 , China
| | - Hui Yang
- School of Life Sciences, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi, 710072, China.
- Center of Special Environmental Biomechanics & Biomedical Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi, 710072, China.
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31
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Bharadwaj R, Bhattacharya A, Somlata. Coordinated activity of amoebic formin and profilin are essential for phagocytosis. Mol Microbiol 2021; 116:974-995. [PMID: 34278607 DOI: 10.1111/mmi.14787] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 10/24/2022]
Abstract
For the protist parasite Entamoeba histolytica, endocytic processes, such as phagocytosis, are essential for its survival in the human gut. The actin cytoskeleton is involved in the formation of pseudopods and phagosomal vesicles by incorporating a number of actin-binding and modulating proteins along with actin in a temporal manner. The actin dynamics, which comprises polymerization, branching, and depolymerization is very tightly regulated and takes place directionally at the sites of initiation of phagocytosis. Formin and profilin are two actin-binding proteins that are known to regulate actin cytoskeleton dynamics and thereby, endocytic processes. In this article, we report the participation of formin and profilin in E. histolytica phagocytosis and propose that these two proteins interact with each other and their sequential recruitment at the site is required for the successful completion of phagocytosis. The evidence is based on detailed microscopic, live imaging, interaction studies, and expression downregulation. The cells downregulated for expression of formin show absence of profilin at the site of phagocytosis, whereas downregulation of profilin does not affect formin localization.
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Affiliation(s)
- Ravi Bharadwaj
- Department of Medicine, UMass Medical School, Worcester, MA, USA
| | | | - Somlata
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, New Delhi, India
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32
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Kay RR. Macropinocytosis: Biology and mechanisms. Cells Dev 2021; 168:203713. [PMID: 34175511 DOI: 10.1016/j.cdev.2021.203713] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/25/2021] [Accepted: 06/21/2021] [Indexed: 12/24/2022]
Abstract
Macropinocytosis is a form of endocytosis performed by ruffles and cups of the plasma membrane. These close to entrap droplets of medium into micron-sized vesicles, which are trafficked through the endocytic system, their contents digested and useful products absorbed. Macropinocytosis is constitutive in certain immune cells and stimulated in many other cells by growth factors. It occurs across the animal kingdom and in amoebae, implying a deep evolutionary history. Its scientific history goes back 100 years, but increasingly work is focused on its medical importance in the immune system, cancer cell feeding, and as a backdoor into cells for viruses and drugs. Macropinocytosis is driven by the actin cytoskeleton whose dynamics can be appreciated with lattice light sheet microscopy: this reveals a surprising variety of routes for forming macropinosomes. In Dictyostelium amoebae, macropinocytic cups are organized around domains of PIP3 and active Ras and Rac in the plasma membrane. These attract activators of the Arp2/3 complex to their periphery, creating rings of actin polymerization that shape the cups. The size of PIP3 domains is controlled by RasGAPs, such as NF1, and the lipid phosphatase, PTEN. It is likely that domain dynamics determine the shape, evolution and closing of macropinocytic structures.
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Affiliation(s)
- Robert R Kay
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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33
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Yang Y, Li D, Chao X, Singh SP, Thomason P, Yan Y, Dong M, Li L, Insall RH, Cai H. Leep1 interacts with PIP3 and the Scar/WAVE complex to regulate cell migration and macropinocytosis. J Cell Biol 2021; 220:212090. [PMID: 33978708 PMCID: PMC8127007 DOI: 10.1083/jcb.202010096] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 03/23/2021] [Accepted: 04/21/2021] [Indexed: 12/20/2022] Open
Abstract
Polarity is essential for diverse functions in many cell types. Establishing polarity requires targeting a network of specific signaling and cytoskeleton molecules to different subregions of the cell, yet the full complement of polarity regulators and how their activities are integrated over space and time to form morphologically and functionally distinct domains remain to be uncovered. Here, by using the model system Dictyostelium and exploiting the characteristic chemoattractant-stimulated translocation of polarly distributed molecules, we developed a proteomic screening approach, through which we identified a leucine-rich repeat domain–containing protein we named Leep1 as a novel polarity regulator. We combined imaging, biochemical, and phenotypic analyses to demonstrate that Leep1 localizes selectively at the leading edge of cells by binding to PIP3, where it modulates pseudopod and macropinocytic cup dynamics by negatively regulating the Scar/WAVE complex. The spatiotemporal coordination of PIP3 signaling, Leep1, and the Scar/WAVE complex provides a cellular mechanism for organizing protrusive structures at the leading edge.
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Affiliation(s)
- Yihong Yang
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Dong Li
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Xiaoting Chao
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Shashi P Singh
- Cancer Research UK Beatson Institute, Glasgow, UK.,University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Peter Thomason
- Cancer Research UK Beatson Institute, Glasgow, UK.,University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Yonghong Yan
- National Institute of Biological Sciences, Beijing, China
| | - Mengqiu Dong
- National Institute of Biological Sciences, Beijing, China
| | - Lei Li
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Robert H Insall
- Cancer Research UK Beatson Institute, Glasgow, UK.,University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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34
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Mylvaganam S, Freeman SA, Grinstein S. The cytoskeleton in phagocytosis and macropinocytosis. Curr Biol 2021; 31:R619-R632. [PMID: 34033794 DOI: 10.1016/j.cub.2021.01.036] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cells of the innate immune system, notably macrophages, neutrophils and dendritic cells, perform essential antimicrobial and homeostatic functions. These functions rely on the dynamic surveillance of the environment supported by the formation of elaborate membrane protrusions. Such protrusions - pseudopodia, lamellipodia and filopodia - facilitate the sampling of the surrounding fluid by macropinocytosis, as well as the engulfment of particulates by phagocytosis. Both processes entail extreme plasma membrane deformations that require the coordinated rearrangement of cytoskeletal polymers, which exert protrusive force and drive membrane coalescence and scission. The resulting vacuolar compartments undergo pronounced remodeling and ultimate resolution by mechanisms that also involve the cytoskeleton. Here, we describe the regulation and functions of cytoskeletal assembly and remodeling during macropinocytosis and phagocytosis.
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Affiliation(s)
- Sivakami Mylvaganam
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
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35
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Maxson ME, Sarantis H, Volchuk A, Brumell JH, Grinstein S. Rab5 regulates macropinocytosis by recruiting the inositol 5-phosphatases OCRL and Inpp5b that hydrolyse PtdIns(4,5)P2. J Cell Sci 2021; 134:237783. [PMID: 33722976 DOI: 10.1242/jcs.252411] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 02/25/2021] [Indexed: 01/09/2023] Open
Abstract
Rab5 is required for macropinosome formation, but its site and mode of action remain unknown. We report that Rab5 acts at the plasma membrane, downstream of ruffling, to promote macropinosome sealing and scission. Dominant-negative Rab5, which obliterates macropinocytosis, had no effect on the development of membrane ruffles. However, Rab5-containing vesicles were recruited to circular membrane ruffles, and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-dependent endomembrane fusion was necessary for the completion of macropinocytosis. This fusion event coincided with the disappearance of PtdIns(4,5)P2 that accompanies macropinosome closure. Counteracting the depletion of PtdIns(4,5)P2 by expression of phosphatidylinositol-4-phosphate 5-kinase impaired macropinosome formation. Importantly, we found that the removal of PtdIns(4,5)P2 is dependent on Rab5, through the Rab5-mediated recruitment of the inositol 5-phosphatases OCRL and Inpp5b, via APPL1. Knockdown of OCRL and Inpp5b, or APPL1, prevented macropinosome closure without affecting ruffling. We therefore propose that Rab5 is essential for the clearance of PtdIns(4,5)P2 needed to complete the scission of macropinosomes or to prevent their back-fusion with the plasmalemma.
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Affiliation(s)
- Michelle E Maxson
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Helen Sarantis
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Allen Volchuk
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - John H Brumell
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada.,SickKids IBD Centre, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario M5S 1A1, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A1, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario M5B 1W8, Canada
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36
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Song S, Zhang Y, Ding T, Ji N, Zhao H. The Dual Role of Macropinocytosis in Cancers: Promoting Growth and Inducing Methuosis to Participate in Anticancer Therapies as Targets. Front Oncol 2021; 10:570108. [PMID: 33542897 PMCID: PMC7851083 DOI: 10.3389/fonc.2020.570108] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 12/01/2020] [Indexed: 02/05/2023] Open
Abstract
Macropinocytosis is an important mechanism of internalizing extracellular materials and dissolved molecules in eukaryotic cells. Macropinocytosis has a dual effect on cancer cells. On the one hand, cells expressing RAS genes (such as K-RAS, H-RAS) under the stress of nutrient deficiency can spontaneously produce constitutive macropinocytosis to promote the growth of cancer cells by internalization of extracellular nutrients (like proteins), receptors, and extracellular vesicles(EVs). On the other hand, abnormal expression of RAS genes and drug treatment (such as MOMIPP) can induce a novel cell death associated with hyperactivated macropinocytosis: methuosis. Based on the dual effect, there is immense potential for designing anticancer therapies that target macropinocytosis in cancer cells. In view of the fact that there has been little review of the dual effect of macropinocytosis in cancer cells, herein, we systematically review the general process of macropinocytosis, its specific manifestation in cancer cells, and its application in cancer treatment, including anticancer drug delivery and destruction of macropinocytosis. This review aims to serve as a reference for studying macropinocytosis in cancers and designing macropinocytosis-targeting anticancer drugs in the future.
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Affiliation(s)
- Shaojuan Song
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yanan Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Tingting Ding
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ning Ji
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Hang Zhao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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37
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Li YX, Pang HB. Macropinocytosis as a cell entry route for peptide-functionalized and bystander nanoparticles. J Control Release 2021; 329:1222-1230. [PMID: 33622520 PMCID: PMC7905157 DOI: 10.1016/j.jconrel.2020.10.049] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 01/12/2023]
Abstract
Endocytic pathways provide the primary route for therapeutic and diagnostic nanoparticles (NPs) to enter cells and subcellular compartments. A better understanding of these cell entry processes will not only aid in nanomaterial applications but also broaden our knowledge of cell biology. Among the endocytic routes, macropinocytosis has unique characteristics for engulfing NPs and other large cargo, yet its molecular machinery and involvement in NP uptake are far less characterized relative to other pathways. In this review, we summarize the current knowledge on the macropinocytic machinery, and its involvement in NP internalization. Particularly, we differentiate ligand (specifically peptide)-functionalized and unfunctionalized NPs (bystander NPs). While most of previous research focused on ligand-functionalized NPs, we showcase here a synergistic effect between these two NP types during their cell entry through receptor-mediated macropinocytosis. The regulation of NP uptake efficiency by extracellular amino acids is also highlighted in the context of interconnections between macropinocytosis and metabolic signaling. These discussions may fuel future research interests in improving NP internalization through this pathway, and open a new avenue to study the interplay among endocytosis, metabolism and nanomedicine.
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Affiliation(s)
- Yue-Xuan Li
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN, USA
| | - Hong-Bo Pang
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN, USA.
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38
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Pan M, Jin T. Imaging GPCR-Mediated Signal Events Leading to Chemotaxis and Phagocytosis. Methods Mol Biol 2021; 2304:207-220. [PMID: 34028719 DOI: 10.1007/978-1-0716-1402-0_11] [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: 06/12/2023]
Abstract
Eukaryotic phagocytes locate microorganisms via chemotaxis and consume them through phagocytosis. The social amoeba Dictyostelium discoideum is a stereotypical phagocyte and a well-established model to study both processes. Recent studies show that a G-protein-coupled receptor (fAR1) mediate a signaling network to control reorganization of the actin cytoskeleton leading both the directional cell movement and the engulfment of bacteria. Many live cell imaging methods have been developed and applied to monitor these signaling events. In this chapter, we will introduce how to measure GPCR-mediated signaling events for cell migration and phagocytosis in Dictyostelium.
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Affiliation(s)
- Miao Pan
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, NIH, Rockville, MD, USA
| | - Tian Jin
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, NIH, Rockville, MD, USA.
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Buckley CM, Pots H, Gueho A, Vines JH, Munn CJ, Phillips BA, Gilsbach B, Traynor D, Nikolaev A, Soldati T, Parnell AJ, Kortholt A, King JS. Coordinated Ras and Rac Activity Shapes Macropinocytic Cups and Enables Phagocytosis of Geometrically Diverse Bacteria. Curr Biol 2020; 30:2912-2926.e5. [PMID: 32531280 PMCID: PMC7416115 DOI: 10.1016/j.cub.2020.05.049] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 04/20/2020] [Accepted: 05/14/2020] [Indexed: 12/15/2022]
Abstract
Engulfment of extracellular material by phagocytosis or macropinocytosis depends on the ability of cells to generate specialized cup-shaped protrusions. To effectively capture and internalize their targets, these cups are organized into a ring or ruffle of actin-driven protrusion encircling a non-protrusive interior domain. These functional domains depend on the combined activities of multiple Ras and Rho family small GTPases, but how their activities are integrated and differentially regulated over space and time is unknown. Here, we show that the amoeba Dictyostelium discoideum coordinates Ras and Rac activity using the multidomain protein RGBARG (RCC1, RhoGEF, BAR, and RasGAP-containing protein). We find RGBARG uses a tripartite mechanism of Ras, Rac, and phospholipid interactions to localize at the protruding edge and interface with the interior of both macropinocytic and phagocytic cups. There, we propose RGBARG shapes the protrusion by expanding Rac activation at the rim while suppressing expansion of the active Ras interior domain. Consequently, cells lacking RGBARG form enlarged, flat interior domains unable to generate large macropinosomes. During phagocytosis, we find that disruption of RGBARG causes a geometry-specific defect in engulfing rod-shaped bacteria and ellipsoidal beads. This demonstrates the importance of coordinating small GTPase activities during engulfment of more complex shapes and thus the full physiological range of microbes, and how this is achieved in a model professional phagocyte. We identify a new regulator that shapes macropinocytic and phagocytic cups Shaping protrusions into cups requires differential regulation of Ras and Rac Cups are organized by integrating interactions with phospholipids and multiple GTPases Defective cup formation causes a target shape-specific defect in phagocytosis
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Affiliation(s)
- Catherine M Buckley
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK
| | - Henderikus Pots
- Department of Cell Biochemistry, University of Groningen, Groningen 9747 AG, Netherlands
| | - Aurelie Gueho
- Department of Biochemistry, Faculty of Sciences, Sciences II, University of Geneva, CH-1211-Geneva-4, Switzerland
| | - James H Vines
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK
| | - Christopher J Munn
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK
| | - Ben A Phillips
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK
| | - Bernd Gilsbach
- German Centre for Neurodegenerative Diseases, Tübingen 72076, Germany
| | - David Traynor
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Anton Nikolaev
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK
| | - Thierry Soldati
- Department of Biochemistry, Faculty of Sciences, Sciences II, University of Geneva, CH-1211-Geneva-4, Switzerland
| | - Andrew J Parnell
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK
| | - Arjan Kortholt
- Department of Cell Biochemistry, University of Groningen, Groningen 9747 AG, Netherlands
| | - Jason S King
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK.
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Nichols JME, Antolović V, Reich JD, Brameyer S, Paschke P, Chubb JR. Cell and molecular transitions during efficient dedifferentiation. eLife 2020; 9:e55435. [PMID: 32255425 PMCID: PMC7190356 DOI: 10.7554/elife.55435] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 04/06/2020] [Indexed: 01/16/2023] Open
Abstract
Dedifferentiation is a critical response to tissue damage, yet is not well understood, even at a basic phenomenological level. Developing Dictyostelium cells undergo highly efficient dedifferentiation, completed by most cells within 24 hr. We use this rapid response to investigate the control features of dedifferentiation, combining single cell imaging with high temporal resolution transcriptomics. Gene expression during dedifferentiation was predominantly a simple reversal of developmental changes, with expression changes not following this pattern primarily associated with ribosome biogenesis. Mutation of genes induced early in dedifferentiation did not strongly perturb the reversal of development. This apparent robustness may arise from adaptability of cells: the relative temporal ordering of cell and molecular events was not absolute, suggesting cell programmes reach the same end using different mechanisms. In addition, although cells start from different fates, they rapidly converged on a single expression trajectory. These regulatory features may contribute to dedifferentiation responses during regeneration.
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Affiliation(s)
- John ME Nichols
- MRC Laboratory for Molecular Cell Biology and Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Vlatka Antolović
- MRC Laboratory for Molecular Cell Biology and Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | - Jacob D Reich
- MRC Laboratory for Molecular Cell Biology and Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
| | | | - Peggy Paschke
- CRUK Beatson Institute, Garscube Estate, Switchback Road, BearsdenGlasgowUnited Kingdom
| | - Jonathan R Chubb
- MRC Laboratory for Molecular Cell Biology and Department of Cell and Developmental Biology, University College LondonLondonUnited Kingdom
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41
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Ecke M, Prassler J, Tanribil P, Müller-Taubenberger A, Körber S, Faix J, Gerisch G. Formins specify membrane patterns generated by propagating actin waves. Mol Biol Cell 2020; 31:373-385. [PMID: 31940262 PMCID: PMC7183788 DOI: 10.1091/mbc.e19-08-0460] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/18/2022] Open
Abstract
Circular actin waves separate two distinct areas on the substrate-attached cell surface from each other: an external area from an inner territory that is circumscribed by the wave. These areas differ in composition of actin-associated proteins and of phosphoinositides in the membrane. At the propagating wave, one area is converted into the other. By photo-conversion of Eos-actin and analysis of actin network structures we show that both in the inner territory and the external area the actin network is subject to continuous turnover. To address the question of whether areas in the wave pattern are specified by particular actin polymerizing machines, we locate five members of the formin family to specific regions of the wave landscape using TIRF microscopy and constitutively active formin constructs tagged with fluorescent protein. Formin ForB favors the actin wave and ForG the inner territory, whereas ForA, ForE, and ForH are more strongly recruited to the external area. Fluctuations of membrane binding peculiar to ForB indicate transient states in the specification of membrane domains before differentiation into ForB decorated and depleted ones. Annihilation of the patterns by 1 µM of the formin inhibitor SMIFH2 supports the implication of formins in their generation.
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Affiliation(s)
- Mary Ecke
- Max Planck Institute of Biochemistry, D-82152 Martinsried, Munich, Germany
| | - Jana Prassler
- Max Planck Institute of Biochemistry, D-82152 Martinsried, Munich, Germany
| | - Patrick Tanribil
- Max Planck Institute of Biochemistry, D-82152 Martinsried, Munich, Germany
| | - Annette Müller-Taubenberger
- Department of Cell Biology (Anatomy III), Ludwig Maximilian University of Munich, D-82152 Planegg-Martinsried, Munich, Germany
| | - Sarah Körber
- Institute of Biophysical Chemistry, Hannover Medical School, D-30625 Hannover, Germany
| | - Jan Faix
- Institute of Biophysical Chemistry, Hannover Medical School, D-30625 Hannover, Germany
| | - Günther Gerisch
- Max Planck Institute of Biochemistry, D-82152 Martinsried, Munich, Germany
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Zhang Y, Xia D, Zhao Q, Zhang G, Zhang Y, Qiu Z, Shen D, Lu C. Label-free proteomic analysis of silkworm midgut infected by Bombyx mori nuclear polyhedrosis virus. J Proteomics 2019; 200:40-50. [PMID: 30904731 DOI: 10.1016/j.jprot.2019.03.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/27/2019] [Accepted: 03/18/2019] [Indexed: 12/13/2022]
Abstract
Bombyx mori nuclear polyhedrosis virus (BmNPV) is the most damaging virus for the production of silkworm cocoons. Antivirus research continues to be an important aspect of the silkworm industry. Two-dimensional electrophoresis and mass spectrometry have been applied for analyzing the midgut proteome of BmNPV-infected silkworms. In recent years, the isobaric tags for relative and absolute quantitation (iTRAQ) method has frequently been used when studying interaction between BmNPV and Bombyx mori, and useful information has been obtained. In this study, midgut proteins of BmNPV-infected silkworms were extracted from silkworm variety NIL·LVR with anti-BmNPV activity at 48 h, and proteome analysis was carried out using the label-free method. 2196 proteins were identified. Among them, there were 85 differentially expressed proteins, 45 upregulated proteins (immune-activated proteins), 28 downregulated proteins, and six proteins were specific for the BmNPV group and another six specific for control group. Many of the immune-activated proteins have been reported to have innate immune functions, and the downregulated proteins are involved in apoptosis or abnormal cell viability. In conclusion, this study provides evidence for host defense against BmNPV infection by both innate immunity and apoptosis, revealing the potential function of the midgut after oral infection of BmNPV in Bombyx mori. SIGNIFICANCE: Bombyx mori nuclear polyhedrosis virus (BmNPV) has a great impact on the sericulture industry. However, the mechanism of resistance to BmNPV has not been fully elucidated. The silkworm midgut is not only the major organ for food digestion and nutrient absorption but also an immune organ serving as the first line of defense against microbial invasion and proliferation. Here we combined label-free quantitative proteomic, bioinformatics, quantitative real-time PCR and SDS-PAGE analyses and found that BmNPV invasion causes complex protein alterations in the larval midgut of NIL·LVR with anti-BmNPV activity. The results showed that many upregulated differentially expressed proteins have been reported to have innate immune functions and the downregulation proteins are involved in apoptosis or abnormal cell viability. These findings provide evidence for host defense against BmNPV infection by both innate immunity and apoptosis, and reveals the potential function of the midgut after infection of BmNPV in Bombyx mori.
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Affiliation(s)
- Yuan Zhang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, College of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212018, China; Key Laboratory of Genetic Improvement of Silkworm and Mulberry, Ministry of Agriculture, Sericulture Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu 212018, China
| | - Dingguo Xia
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, College of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212018, China; Key Laboratory of Genetic Improvement of Silkworm and Mulberry, Ministry of Agriculture, Sericulture Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu 212018, China.
| | - Qiaoling Zhao
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, College of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212018, China; Key Laboratory of Genetic Improvement of Silkworm and Mulberry, Ministry of Agriculture, Sericulture Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu 212018, China
| | - Guozheng Zhang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, College of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212018, China; Key Laboratory of Genetic Improvement of Silkworm and Mulberry, Ministry of Agriculture, Sericulture Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu 212018, China
| | - Yeshun Zhang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, College of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212018, China; Key Laboratory of Genetic Improvement of Silkworm and Mulberry, Ministry of Agriculture, Sericulture Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu 212018, China
| | - Zhiyong Qiu
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, College of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212018, China; Key Laboratory of Genetic Improvement of Silkworm and Mulberry, Ministry of Agriculture, Sericulture Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu 212018, China
| | - Dongxu Shen
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, College of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212018, China; Key Laboratory of Genetic Improvement of Silkworm and Mulberry, Ministry of Agriculture, Sericulture Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, Jiangsu 212018, China
| | - Cheng Lu
- Institute of Sericulture and System Biology, Southwest University, Chongqing 400716, China
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43
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Functional integrity of the contractile actin cortex is safeguarded by multiple Diaphanous-related formins. Proc Natl Acad Sci U S A 2019; 116:3594-3603. [PMID: 30808751 DOI: 10.1073/pnas.1821638116] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The contractile actin cortex is a thin layer of filamentous actin, myosin motors, and regulatory proteins beneath the plasma membrane crucial to cytokinesis, morphogenesis, and cell migration. However, the factors regulating actin assembly in this compartment are not well understood. Using the Dictyostelium model system, we show that the three Diaphanous-related formins (DRFs) ForA, ForE, and ForH are regulated by the RhoA-like GTPase RacE and synergize in the assembly of filaments in the actin cortex. Single or double formin-null mutants displayed only moderate defects in cortex function whereas the concurrent elimination of all three formins or of RacE caused massive defects in cortical rigidity and architecture as assessed by aspiration assays and electron microscopy. Consistently, the triple formin and RacE mutants encompassed large peripheral patches devoid of cortical F-actin and exhibited severe defects in cytokinesis and multicellular development. Unexpectedly, many forA - /E -/H - and racE - mutants protruded efficiently, formed multiple exaggerated fronts, and migrated with morphologies reminiscent of rapidly moving fish keratocytes. In 2D-confinement, however, these mutants failed to properly polarize and recruit myosin II to the cell rear essential for migration. Cells arrested in these conditions displayed dramatically amplified flow of cortical actin filaments, as revealed by total internal reflection fluorescence (TIRF) imaging and iterative particle image velocimetry (PIV). Consistently, individual and combined, CRISPR/Cas9-mediated disruption of genes encoding mDia1 and -3 formins in B16-F1 mouse melanoma cells revealed enhanced frequency of cells displaying multiple fronts, again accompanied by defects in cell polarization and migration. These results suggest evolutionarily conserved functions for formin-mediated actin assembly in actin cortex mechanics.
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Abstract
In macropinocytosis, cells take up micrometre-sized droplets of medium into internal vesicles. These vesicles are acidified and fused to lysosomes, their contents digested and useful compounds extracted. Indigestible contents can be exocytosed. Macropinocytosis has been known for approaching 100 years and is described in both metazoa and amoebae, but not in plants or fungi. Its evolutionary origin goes back to at least the common ancestor of the amoebozoa and opisthokonts, with apparent secondary loss from fungi. The primary function of macropinocytosis in amoebae and some cancer cells is feeding, but the conserved processing pathway for macropinosomes, which involves shrinkage and the retrieval of membrane to the cell surface, has been adapted in immune cells for antigen presentation. Macropinocytic cups are large actin-driven processes, closely related to phagocytic cups and pseudopods and appear to be organized around a conserved signalling patch of PIP3, active Ras and active Rac that directs actin polymerization to its periphery. Patches can form spontaneously and must be sustained by excitable kinetics with strong cooperation from the actin cytoskeleton. Growth-factor signalling shares core components with macropinocytosis, based around phosphatidylinositol 3-kinase (PI3-kinase), and we suggest that it evolved to take control of ancient feeding structures through a coupled growth factor receptor. This article is part of the Theo Murphy meeting issue 'Macropinocytosis'.
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Affiliation(s)
- Jason S. King
- Department of Biomedical Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Robert R. Kay
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
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45
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Williams TD, Paschke PI, Kay RR. Function of small GTPases in Dictyostelium macropinocytosis. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180150. [PMID: 30967009 PMCID: PMC6304742 DOI: 10.1098/rstb.2018.0150] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2018] [Indexed: 12/17/2022] Open
Abstract
Macropinocytosis-the large-scale, non-specific uptake of fluid by cells-is used by Dictyostelium discoideum amoebae to obtain nutrients. These cells form circular ruffles around regions of membrane defined by a patch of phosphatidylinositol (3,4,5)-trisphosphate (PIP3) and the activated forms of the small G-proteins Ras and Rac. When this ruffle closes, a vesicle of the medium is delivered to the cell interior for further processing. It is accepted that PIP3 is required for efficient macropinocytosis. Here, we assess the roles of Ras and Rac in Dictyostelium macropinocytosis. Gain-of-function experiments show that macropinocytosis is stimulated by persistent Ras activation and genetic analysis suggests that RasG and RasS are the key Ras proteins involved. Among the activating guanine exchange factors (GEFs), GefF is implicated in macropinocytosis by an insertional mutant. The individual roles of Rho family proteins are little understood but activation of at least some may be independent of PIP3. This article is part of the Theo Murphy meeting issue 'Macropinocytosis'.
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Affiliation(s)
| | | | - Robert R. Kay
- MRC-Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
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46
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Williams TD, Peak-Chew SY, Paschke P, Kay RR. Akt and SGK protein kinases are required for efficient feeding by macropinocytosis. J Cell Sci 2019; 132:jcs.224998. [PMID: 30617109 DOI: 10.1242/jcs.224998] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 12/19/2018] [Indexed: 12/20/2022] Open
Abstract
Macropinocytosis is an actin-driven process of large-scale and non-specific fluid uptake used for feeding by some cancer cells and the macropinocytosis model organism Dictyostelium discoideum In Dictyostelium, macropinocytic cups are organized by 'macropinocytic patches' in the plasma membrane. These contain activated Ras, Rac and phospholipid PIP3, and direct actin polymerization to their periphery. We show that a Dictyostelium Akt (PkbA) and an SGK (PkbR1) protein kinase act downstream of PIP3 and, together, are nearly essential for fluid uptake. This pathway enables the formation of larger macropinocytic patches and macropinosomes, thereby dramatically increasing fluid uptake. Through phosphoproteomics, we identify a RhoGAP, GacG, as a PkbA and PkbR1 target, and show that it is required for efficient macropinocytosis and expansion of macropinocytic patches. The function of Akt and SGK in cell feeding through control of macropinosome size has implications for cancer cell biology.
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Affiliation(s)
| | | | - Peggy Paschke
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
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47
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IQGAP-related protein IqgC suppresses Ras signaling during large-scale endocytosis. Proc Natl Acad Sci U S A 2019; 116:1289-1298. [PMID: 30622175 DOI: 10.1073/pnas.1810268116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Macropinocytosis and phagocytosis are evolutionarily conserved forms of bulk endocytosis used by cells to ingest large volumes of fluid and solid particles, respectively. Both processes are regulated by Ras signaling, which is precisely controlled by mechanisms involving Ras GTPase activating proteins (RasGAPs) responsible for terminating Ras activity on early endosomes. While regulation of Ras signaling during large-scale endocytosis in WT Dictyostelium has been, for the most part, attributed to the Dictyostelium ortholog of human RasGAP NF1, in commonly used axenic laboratory strains, this gene is mutated and inactive. Moreover, none of the RasGAPs characterized so far have been implicated in the regulation of Ras signaling in large-scale endocytosis in axenic strains. In this study, we establish, using biochemical approaches and complementation assays in live cells, that Dictyostelium IQGAP-related protein IqgC interacts with active RasG and exhibits RasGAP activity toward this GTPase. Analyses of iqgC - and IqgC-overexpressing cells further revealed participation of this GAP in the regulation of both types of large-scale endocytosis and in cytokinesis. Moreover, given the localization of IqgC to phagosomes and, most prominently, to macropinosomes, we propose IqgC acting as a RasG-specific GAP in large-scale endocytosis. The data presented here functionally distinguish IqgC from other members of the Dictyostelium IQGAP family and call for repositioning of this genuine RasGAP outside of the IQGAP group.
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48
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Xu X. Filling GAPs in G protein- coupled receptor (GPCR)-mediated Ras adaptation and chemotaxis. Small GTPases 2018; 11:309-311. [PMID: 29733762 DOI: 10.1080/21541248.2018.1473671] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Eukaryotic cells sense and migrate toward chemoattractant gradients using G protein-coupled receptor (GPCR) signaling pathways. The fascinating feature of chemotaxis is that cells migrate through chemoattractant gradients with huge concentration ranges by "adaptation." Adaptive cells no longer respond to the present stimulus but remain sensitive to stronger stimuli, providing the fundamental strategy for chemotaxis through gradients with a broad range of concentrations. Ras activation is the first step in the GPCR-mediated chemosensing signaling pathways that displays adaptation. However, the molecular mechanism of Ras adaptation is not fully understood. Here, we highlight C2GAP1, a GPCR-activated Ras negative regulator, that locally inhibits Ras signaling for adaptation and long-range chemotaxis in D. discoideum.
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Affiliation(s)
- Xuehua Xu
- Chemotaxis Signaling Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Rockville, MD, USA
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49
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Bharadwaj R, Sharma S, Arya R, Bhattacharya S, Bhattacharya A. EhRho1 regulates phagocytosis by modulating actin dynamics through EhFormin1 and EhProfilin1 inEntamoeba histolytica. Cell Microbiol 2018; 20:e12851. [DOI: 10.1111/cmi.12851] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 03/12/2018] [Accepted: 03/25/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Ravi Bharadwaj
- School of Life Sciences; Jawaharlal Nehru University; New Delhi India
| | - Shalini Sharma
- School of Life Sciences; Jawaharlal Nehru University; New Delhi India
| | - Ranjana Arya
- School of Biotechnology; Jawaharlal Nehru University; New Delhi India
| | - Sudha Bhattacharya
- School of Environmental Sciences; Jawaharlal Nehru University; New Delhi India
| | - Alok Bhattacharya
- School of Life Sciences; Jawaharlal Nehru University; New Delhi India
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50
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Pan M, Neilson MP, Grunfeld AM, Cruz P, Wen X, Insall RH, Jin T. A G-protein-coupled chemoattractant receptor recognizes lipopolysaccharide for bacterial phagocytosis. PLoS Biol 2018; 16:e2005754. [PMID: 29799847 PMCID: PMC5969738 DOI: 10.1371/journal.pbio.2005754] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 04/27/2018] [Indexed: 11/19/2022] Open
Abstract
Phagocytes locate microorganisms via chemotaxis and then consume them using phagocytosis. Dictyostelium amoebas are stereotypical phagocytes that prey on diverse bacteria using both processes. However, as typical phagocytic receptors, such as complement receptors or Fcγ receptors, have not been found in Dictyostelium, it remains mysterious how these cells recognize bacteria. Here, we show that a single G-protein-coupled receptor (GPCR), folic acid receptor 1 (fAR1), simultaneously recognizes the chemoattractant folate and the phagocytic cue lipopolysaccharide (LPS), a major component of bacterial surfaces. Cells lacking fAR1 or its cognate G-proteins are defective in chemotaxis toward folate and phagocytosis of Klebsiella aerogenes. Computational simulations combined with experiments show that responses associated with chemotaxis can also promote engulfment of particles coated with chemoattractants. Finally, the extracellular Venus-Flytrap (VFT) domain of fAR1 acts as the binding site for both folate and LPS. Thus, fAR1 represents a new member of the pattern recognition receptors (PRRs) and mediates signaling from both bacterial surfaces and diffusible chemoattractants to reorganize actin for chemotaxis and phagocytosis.
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Affiliation(s)
- Miao Pan
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, Rockville, Maryland, United States of America
| | | | - Alexander M. Grunfeld
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, Rockville, Maryland, United States of America
| | - Phillip Cruz
- Bioinformatics and Computational Biosciences Branch, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Xi Wen
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, Rockville, Maryland, United States of America
| | | | - Tian Jin
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, Rockville, Maryland, United States of America
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