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Ukleja M, Kricks L, Torrens G, Peschiera I, Rodrigues-Lopes I, Krupka M, García-Fernández J, Melero R, Del Campo R, Eulalio A, Mateus A, López-Bravo M, Rico AI, Cava F, Lopez D. Flotillin-mediated stabilization of unfolded proteins in bacterial membrane microdomains. Nat Commun 2024; 15:5583. [PMID: 38961085 PMCID: PMC11222466 DOI: 10.1038/s41467-024-49951-1] [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: 02/21/2024] [Accepted: 06/26/2024] [Indexed: 07/05/2024] Open
Abstract
The function of many bacterial processes depends on the formation of functional membrane microdomains (FMMs), which resemble the lipid rafts of eukaryotic cells. However, the mechanism and the biological function of these membrane microdomains remain unclear. Here, we show that FMMs in the pathogen methicillin-resistant Staphylococcus aureus (MRSA) are dedicated to confining and stabilizing proteins unfolded due to cellular stress. The FMM scaffold protein flotillin forms a clamp-shaped oligomer that holds unfolded proteins, stabilizing them and favoring their correct folding. This process does not impose a direct energy cost on the cell and is crucial to survival of ATP-depleted bacteria, and thus to pathogenesis. Consequently, FMM disassembling causes the accumulation of unfolded proteins, which compromise MRSA viability during infection and cause penicillin re-sensitization due to PBP2a unfolding. Thus, our results indicate that FMMs mediate ATP-independent stabilization of unfolded proteins, which is essential for bacterial viability during infection.
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Affiliation(s)
- Marta Ukleja
- Department of Microbiology, National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, 28049, Spain
| | - Lara Kricks
- Department of Microbiology, National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, 28049, Spain
| | - Gabriel Torrens
- Department of Molecular Biology, Umeå University, Umeå, SE-901 87, Sweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS). Umeå Center for Microbial Research (UCMR). Science for Life Laboratory (SciLifeLab), Umeå, SE-901 87, Sweden
| | - Ilaria Peschiera
- Department of Microbiology, National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, 28049, Spain
| | - Ines Rodrigues-Lopes
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-504, Coimbra, Portugal
| | - Marcin Krupka
- Department of Microbiology, National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, 28049, Spain
| | - Julia García-Fernández
- Department of Microbiology, National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, 28049, Spain
| | - Roberto Melero
- Department of Structural Biology, National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, 28049, Spain
| | - Rosa Del Campo
- Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Ramón y Cajal Hospital, 28034, Madrid, Spain
| | - Ana Eulalio
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-504, Coimbra, Portugal
- Department of Life Sciences, Center for Bacterial Resistance Biology, Imperial College London, London, SW7 2AZ, United Kingdom
| | - André Mateus
- The Laboratory for Molecular Infection Medicine Sweden (MIMS). Umeå Center for Microbial Research (UCMR). Science for Life Laboratory (SciLifeLab), Umeå, SE-901 87, Sweden
- Department of Chemistry, Umeå University, Umeå, SE-901 87, Sweden
| | - María López-Bravo
- Department of Microbiology, National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, 28049, Spain
| | - Ana I Rico
- Department of Microbiology, National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, 28049, Spain
| | - Felipe Cava
- Department of Molecular Biology, Umeå University, Umeå, SE-901 87, Sweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS). Umeå Center for Microbial Research (UCMR). Science for Life Laboratory (SciLifeLab), Umeå, SE-901 87, Sweden
| | - Daniel Lopez
- Department of Microbiology, National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), Madrid, 28049, Spain.
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2
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Reseco L, Molina-Crespo A, Atienza M, Gonzalez E, Falcon-Perez JM, Cantero JL. Characterization of Extracellular Vesicles from Human Saliva: Effects of Age and Isolation Techniques. Cells 2024; 13:95. [PMID: 38201299 PMCID: PMC10778510 DOI: 10.3390/cells13010095] [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: 11/12/2023] [Revised: 12/22/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
Salivary extracellular vesicles (EVs) represent an attractive source of biomarkers due to the accessibility of saliva and its non-invasive sampling methods. However, the lack of comparative studies assessing the efficacy of different EV isolation techniques hampers the use of salivary EVs in clinical settings. Moreover, the effects of age on salivary EVs are largely unknown, hindering the identification of salivary EV-associated biomarkers across the lifespan. To address these questions, we compared salivary EV concentration, size mode, protein concentration, and purity using eight EV isolation techniques before and after magnetic bead immunocapture with antibodies against CD9, CD63, and CD81. The effects of age on salivary EVs obtained with each isolation technique were further investigated. Results showed higher expression of CD63 on isolated salivary EVs compared to the expression of CD81 and flotillin-1. Overall, magnetic bead immunocapture was more efficient in recovering salivary EVs with Norgen's Saliva Exosome Purification Kit and ExoQuick-TC ULTRA at the cost of EV yield. Regardless of age, Invitrogen Total Exosome Isolation Solution showed the highest level of protein concentration, whereas Izon qEVOriginal-70nm columns revealed the highest purity. This study provides the first comprehensive comparison of salivary EVs in younger and older adults using different EV isolation techniques, which represents a step forward for assessing salivary EVs as a source of potential biomarkers of tissue-specific diseases throughout the life cycle.
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Affiliation(s)
- Lucia Reseco
- Laboratory of Functional Neuroscience, Pablo de Olavide University, 41013 Seville, Spain; (L.R.); (A.M.-C.); (M.A.)
- CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Angela Molina-Crespo
- Laboratory of Functional Neuroscience, Pablo de Olavide University, 41013 Seville, Spain; (L.R.); (A.M.-C.); (M.A.)
- CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Mercedes Atienza
- Laboratory of Functional Neuroscience, Pablo de Olavide University, 41013 Seville, Spain; (L.R.); (A.M.-C.); (M.A.)
- CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Esperanza Gonzalez
- Exosomes Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), 48160 Derio, Spain; (E.G.); (J.M.F.-P.)
| | - Juan Manuel Falcon-Perez
- Exosomes Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), 48160 Derio, Spain; (E.G.); (J.M.F.-P.)
- CIBEREHD, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, 28029 Madrid, Spain
| | - Jose L. Cantero
- Laboratory of Functional Neuroscience, Pablo de Olavide University, 41013 Seville, Spain; (L.R.); (A.M.-C.); (M.A.)
- CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, 28029 Madrid, Spain
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3
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Isik OA, Cizmecioglu O. Rafting on the Plasma Membrane: Lipid Rafts in Signaling and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1436:87-108. [PMID: 36648750 DOI: 10.1007/5584_2022_759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The plasma membrane is not a uniform phospholipid bilayer; it has specialized membrane nano- or microdomains called lipid rafts. Lipid rafts are small cholesterol and sphingolipid-rich plasma membrane islands. Although their existence was long debated, their presence in the plasma membrane of living cells is now well accepted with the advent of super-resolution imaging techniques. It is interesting to note that lipid rafts function to compartmentalize receptors and their regulators and substantially modulate cellular signaling. In this review, we will examine the role of lipid rafts and caveolae-lipid raft-like microdomains with a distinct 3D morphology-in cellular signaling. Moreover, we will investigate how raft compartmentalized signaling regulates diverse physiological processes such as proliferation, apoptosis, immune signaling, and development. Also, the deregulation of lipid raft-mediated signaling during tumorigenesis and metastasis will be explored.
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Affiliation(s)
- Ozlem Aybuke Isik
- Department of Molecular Biology and Genetics, Bilkent University, Ankara, Turkey
| | - Onur Cizmecioglu
- Department of Molecular Biology and Genetics, Bilkent University, Ankara, Turkey.
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4
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Gundu C, Arruri VK, Yadav P, Navik U, Kumar A, Amalkar VS, Vikram A, Gaddam RR. Dynamin-Independent Mechanisms of Endocytosis and Receptor Trafficking. Cells 2022; 11:cells11162557. [PMID: 36010634 PMCID: PMC9406725 DOI: 10.3390/cells11162557] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/03/2022] [Accepted: 08/13/2022] [Indexed: 11/16/2022] Open
Abstract
Endocytosis is a fundamental mechanism by which cells perform housekeeping functions. It occurs via a variety of mechanisms and involves many regulatory proteins. The GTPase dynamin acts as a “molecular scissor” to form endocytic vesicles and is a critical regulator among the proteins involved in endocytosis. Some GTPases (e.g., Cdc42, arf6, RhoA), membrane proteins (e.g., flotillins, tetraspanins), and secondary messengers (e.g., calcium) mediate dynamin-independent endocytosis. These pathways may be convergent, as multiple pathways exist in a single cell. However, what determines the specific path of endocytosis is complex and challenging to comprehend. This review summarizes the mechanisms of dynamin-independent endocytosis, the involvement of microRNAs, and factors that contribute to the cellular decision about the specific route of endocytosis.
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Affiliation(s)
- Chayanika Gundu
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad 500037, Telangana, India
| | - Vijay Kumar Arruri
- Department of Neurological Surgery, University of Wisconsin, Madison, WI 53792, USA
| | - Poonam Yadav
- Department of Pharmacology, Central University of Punjab, Bathinda 151001, Punjab, India
| | - Umashanker Navik
- Department of Pharmacology, Central University of Punjab, Bathinda 151001, Punjab, India
| | - Ashutosh Kumar
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Kolkata 700054, West Bengal, India
| | - Veda Sudhir Amalkar
- Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Ajit Vikram
- Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | - Ravinder Reddy Gaddam
- Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
- Correspondence:
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5
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Varma S, Dey S, S P D. Cellular Uptake Pathways of Nanoparticles: Process of Endocytosis and Factors Affecting Their Fate. Curr Pharm Biotechnol 2021; 23:679-706. [PMID: 34264182 DOI: 10.2174/1389201022666210714145356] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 05/06/2021] [Accepted: 05/07/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Efficient and controlled internalization of NPs into the cells depends on their physicochemical properties and dynamics of the plasma membrane. NPs-cell interaction is a complex process that decides the fate of NPs internalization through different endocytosis pathways. OBJECTIVE The aim of this review is to highlight the physicochemical properties of synthesized nanoparticles (NPs) and their interaction with the cellular-dynamics and pathways like phagocytosis, pinocytosis, macropinocytosis, clathrin, and caveolae-mediated endocytosis and the involvement of effector proteins domain such as clathrin, AP2, caveolin, Arf6, Cdc42, dynamin and cell surface receptors during the endocytosis process of NPs. METHOD An electronic search was performed to explore the focused reviews and research articles on types of endocytosis and physicochemical properties of nanoparticles and their impact on cellular internalizations. The search was limited to peer-reviewed journals in the PubMed database. RESULTS This article discusses in detail how different types of NPs and their physicochemical properties such as size, shape, aspect ratio, surface charge, hydrophobicity, elasticity, stiffness, corona formation, surface functionalization changes the pattern of endocytosis in the presence of different pharmacological blockers. Some external forces like a magnetic field, electric field, and ultrasound exploit the cell membrane dynamics to permeabilize them for efficient internalization with respect to fundamental principles of membrane bending and pore formation. CONCLUSION This review will be useful to attract and guide the audience to understand the endocytosis mechanism and their pattern with respect to physicochemical properties of NPs to improve their efficacy and targeting to achieve the impactful outcome in drug-delivery and theranostics applications.
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Affiliation(s)
- Sameer Varma
- Department of Pharmaceutical Biotechnology, JSS Academy of Higher Education & Research- JSS College of Pharmacy, Ooty-643001, Tamil Nadu, India
| | - Smita Dey
- Department of Pharmaceutical Biotechnology, JSS Academy of Higher Education & Research- JSS College of Pharmacy, Ooty-643001, Tamil Nadu, India
| | - Dhanabal S P
- Department of Pharmacognosy & Phytopharmacy, JSS Academy of Higher Education & Research- JSS College of Pharmacy, Ooty-643001, Tamil Nadu, India
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6
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Shalimova A, Babasieva V, Chubarev VN, Tarasov VV, Schiöth HB, Mwinyi J. Therapy response prediction in major depressive disorder: current and novel genomic markers influencing pharmacokinetics and pharmacodynamics. Pharmacogenomics 2021; 22:485-503. [PMID: 34018822 DOI: 10.2217/pgs-2020-0157] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Major depressive disorder is connected with high rates of functional disability and mortality. About a third of the patients are at risk of therapy failure. Several pharmacogenetic markers especially located in CYP450 genes such as CYP2D6 or CYP2C19 are of relevance for therapy outcome prediction in major depressive disorder but a further optimization of predictive tools is warranted. The article summarizes the current knowledge on pharmacogenetic variants, therapy effects and side effects of important antidepressive therapeutics, and sheds light on new methodological approaches for therapy response estimation based on genetic markers with relevance for pharmacokinetics, pharmacodynamics and disease pathology identified in genome-wide association study analyses, highlighting polygenic risk score analysis as a tool for further optimization of individualized therapy outcome prediction.
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Affiliation(s)
- Alena Shalimova
- Department of Neuroscience, Functional Pharmacology, University of Uppsala, Uppsala, 751 24, Sweden.,Department of Pharmacology, Institute of Pharmacy, I. M. Sechenov First Moscow State Medical University, Moscow, 119991, Russia
| | - Viktoria Babasieva
- Department of Neuroscience, Functional Pharmacology, University of Uppsala, Uppsala, 751 24, Sweden.,Department of Pharmacology, Institute of Pharmacy, I. M. Sechenov First Moscow State Medical University, Moscow, 119991, Russia
| | - Vladimir N Chubarev
- Department of Pharmacology, Institute of Pharmacy, I. M. Sechenov First Moscow State Medical University, Moscow, 119991, Russia
| | - Vadim V Tarasov
- Department of Pharmacology, Institute of Pharmacy, I. M. Sechenov First Moscow State Medical University, Moscow, 119991, Russia.,Institute of Translational Medicine & Biotechnology, I. M. Sechenov First Moscow State Medical University, Moscow, 119991, Russia
| | - Helgi B Schiöth
- Department of Neuroscience, Functional Pharmacology, University of Uppsala, Uppsala, 751 24, Sweden.,Institute of Translational Medicine & Biotechnology, I. M. Sechenov First Moscow State Medical University, Moscow, 119991, Russia
| | - Jessica Mwinyi
- Department of Neuroscience, Functional Pharmacology, University of Uppsala, Uppsala, 751 24, Sweden
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7
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Song T, Hu Z, Liu J, Huang W. FLOT2 upregulation promotes growth and invasion by interacting and stabilizing EphA2 in gliomas. Biochem Biophys Res Commun 2021; 548:67-73. [PMID: 33631676 DOI: 10.1016/j.bbrc.2021.02.062] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 02/14/2021] [Indexed: 12/13/2022]
Abstract
The expression and roles of FLOT2, especially for its underlying mechanism, in gliomas have been rarely revealed. In this study, upregulations of both FLOT2 and EphA2 in gliomas tissues were validated by immunohistochemistry (IHC) staining and Western blot. FLOT2 silencing notably inhibited the growth and invasion of gliomas cells. Simultaneously, FLOT2 depletion suppressed Akt and NF-κB activities, induced apoptosis, cell cycle arrest, and epithelial-mesenchymal transition (EMT) inhibition, demonstrated by expression alterations of key proteins of the above processes. Mechanistically, FLOT2 could maintain EphA2 stability viainteraction, and restoration of EphA2 could remarkably release the suppressive effects on gliomas cells induced by FLOT2 knockdown. Lastly, FLOT2 and EphA2, whose protein and mRNA levels are both positively correlated in gliomas, shows significant association with clinical characteristics like Ki67 intensity, p53 expression, and tumor stage in patients with gliomas. In conclusion, our results reveal the upregulation, oncogenic roles of FLOT2, and the corresponding underlying mechanism in gliomas, highlighting that the FLOT2-EphA2 axis is served as a promising therapeutic target for gliomas.
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Affiliation(s)
- Tao Song
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhongxu Hu
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Jie Liu
- Department of Pathology, Changsha Central Hospital, Changsha, Hunan, China
| | - Wei Huang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China; Research Center of Carcinogenesis and Targeted Therapy, Xiangya Hospital, Changsha, Hunan, China.
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8
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Lv X, Wu Y, Tian R, Gu Y, Liu Y, Li J, Du G, Ledesma-Amaro R, Liu L. Synthetic metabolic channel by functional membrane microdomains for compartmentalized flux control. Metab Eng 2020; 59:106-118. [DOI: 10.1016/j.ymben.2020.02.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 02/17/2020] [Accepted: 02/17/2020] [Indexed: 10/24/2022]
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9
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Lv X, Jin K, Wu Y, Zhang C, Cui S, Zhu X, Li J, Du G, Liu L. Enzyme assembly guided by SPFH-induced functional inclusion bodies for enhanced cascade biocatalysis. Biotechnol Bioeng 2020; 117:1446-1457. [PMID: 32043560 DOI: 10.1002/bit.27304] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 02/05/2020] [Accepted: 02/09/2020] [Indexed: 01/01/2023]
Abstract
Enzyme clustering into compact agglomerates could accelerate the processing of intermediates to enhance metabolic pathway flux. However, enzyme clustering is still a challenging task due to the lack of universal assembly strategy applicable to all enzymes. Therefore, we proposed an alternative enzyme assembly strategy based on functional inclusion bodies. First, functional inclusion bodies in cells were formed by the fusion expression of stomatin/prohibitin/flotillin/HflK/C (SPFH) domain and enhanced green fluorescent protein, as observed visually and by transmission electron microscopy. The formation of SPFH-induced functional inclusion bodies enhanced intermolecular polymerization as revealed by further analysis combined with Förster resonance energy transfer and bimolecular fluorescent complimentary. Finally, the functional inclusion bodies significantly improved the enzymatic catalysis in living cells, as proven by the examples with whole-cell biocatalysis of phenyllactic acid by Escherichia coli, and the production of N-acetylglucosamine by Bacillus subtilis. Our findings suggest that SPFH-induced functional inclusion bodies can enhance the cascade reaction of enzymes, to serve as a potential universal strategy for the construction of efficient microbial cell factories.
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Affiliation(s)
- Xueqin Lv
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Ke Jin
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Yaokang Wu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Cheng Zhang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Shixiu Cui
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Xiaonan Zhu
- School of Bioengineering, Jiangnan University, Wuxi, China
| | - Jianghua Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Guocheng Du
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Long Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
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10
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Yokoyama H, Matsui I. The lipid raft markers stomatin, prohibitin, flotillin, and HflK/C (SPFH)-domain proteins form an operon with NfeD proteins and function with apolar polyisoprenoid lipids. Crit Rev Microbiol 2020; 46:38-48. [PMID: 31983249 DOI: 10.1080/1040841x.2020.1716682] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
SPFH-domain proteins are found in almost all organisms across three domains: archaea, bacteria, and eukaryotes. In eukaryotic organelles, their subfamilies exhibit overlapping distribution and functions; thus, the rationality of annotation to discriminate these subfamilies remains unclear. In this review, the binding ability of prokaryotic SPFH-domain proteins towards nonpolar polyisoprenoides such as squalene and lycopene, rather than cholesterol, is discussed. The hydrophobic region at the C-terminus of SPFH-domain proteins constitutes the main region that binds apolar polyisoprenoid lipids as well as cholesterol and substantively contributes towards lipid raft formation as these regions are self-assembled together with specific lipids. Because the scaffolding proteins caveolins show common topological properties with SPFH-domain proteins such as stomatin and flotillin, the α-helical segments of stomatin proteins can flexibly move along with the membrane surface, with such movement potentially leading to membrane bending via lipid raft clustering through the formation of high order homo-oligomeric complexes of SPFH-domain proteins. We also discuss the functional significance and ancient origin of SPFH-domain proteins and the NfeD protein (STOPP) operon, which can be traced back to the ancient living cells that diverged and evolved to archaea and bacteria. Based on the molecular mechanism whereby the STOPP-protease degrades the C-terminal hydrophobic clusters of SPFH-domain proteins, it is conceivable that STOPP-protease might control the physicochemical properties of lipid rafts.
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Affiliation(s)
- Hideshi Yokoyama
- Department of Medical and Life Sciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan
| | - Ikuo Matsui
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
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11
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Zhong J, Li S, Zeng W, Li X, Gu C, Liu J, Luo XJ. Integration of GWAS and brain eQTL identifies FLOT1 as a risk gene for major depressive disorder. Neuropsychopharmacology 2019; 44:1542-1551. [PMID: 30771789 PMCID: PMC6785150 DOI: 10.1038/s41386-019-0345-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 02/11/2019] [Accepted: 02/12/2019] [Indexed: 12/28/2022]
Abstract
Major depressive disorder (MDD) is the most prevalent mental disorder that affects more than 200 million people worldwide. Recent large-scale genome-wide association studies (GWAS) have identified multiple risk variants that show robust association with MDD. Nevertheless, how the identified risk variants confer risk of MDD remains largely unknown. To identify risk variants that are associated with gene expression in human brain and to identify genes whose expression change may contribute to the susceptibility of MDD, we systematically integrated the genetic associations from a large-scale MDD GWAS (N = 480,359) and brain expression quantitative trait loci (eQTL) data (N = 494) using a Bayesian statistical framework (Sherlock). Sherlock integrative analysis showed that FLOT1 was significantly associated with MDD (P = 6.02 × 10-6), suggesting that risk variants may contribute to MDD susceptibility through affecting FLOT1 expression. We further examined the expression level of FLOT1 in MDD cases and controls and found that FLOT1 was significantly upregulated in brains and peripheral blood of MDD cases compared with controls (European sample). Interestingly, we found that FLOT1 expression was also significantly upregulated in peripheral blood of first-episode drug-naive MDD cases compared with controls (P = 1.01 × 10-7, Chinese sample). Our study identified FLOT1 as a novel MDD risk gene whose expression level may play a role in MDD. In addition, our findings also suggest that risk variants may confer risk of MDD through affecting expression of FLOT1. Further functional investigation of FLOT1 may provide new insights for MDD pathogenesis.
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Affiliation(s)
- Jingmei Zhong
- The first people’s hospital of Yunnan province, Psychiatry Department, 650032 Kunming, Yunnan China
| | - Shiwu Li
- 0000000119573309grid.9227.eKey Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, 650223 Kunming, Yunnan China ,Kunming College of Life Science, University of Chinese Academy of Sciences, 650204 Kunming, Yunnan China
| | - Wanli Zeng
- Yunnan Academy of Tobacco Science, 650106 Kunming, Yunnan China
| | - Xiaoyan Li
- 0000000119573309grid.9227.eKey Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, 650223 Kunming, Yunnan China ,Kunming College of Life Science, University of Chinese Academy of Sciences, 650204 Kunming, Yunnan China
| | - Chunjie Gu
- The first people’s hospital of Yunnan province, Psychiatry Department, 650032 Kunming, Yunnan China
| | - Jiewei Liu
- 0000000119573309grid.9227.eKey Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, 650223 Kunming, Yunnan China
| | - Xiong-Jian Luo
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, 650223, Kunming, Yunnan, China. .,Kunming College of Life Science, University of Chinese Academy of Sciences, 650204, Kunming, Yunnan, China. .,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, 650223, Kunming, China. .,KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, 650223, Kunming, Yunnan, China.
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12
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Infection by Anaplasma phagocytophilum Requires Recruitment of Low-Density Lipoprotein Cholesterol by Flotillins. mBio 2019; 10:mBio.02783-18. [PMID: 30914515 PMCID: PMC6437059 DOI: 10.1128/mbio.02783-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Anaplasma phagocytophilum is an obligatory intracellular bacterium that proliferates in membrane-bound inclusions. A. phagocytophilum is dependent on cholesterol and acquire cholesterol from low-density lipoprotein (LDL) endocytosed by mammalian host cells. The mechanism of cholesterol transport to Anaplasma inclusions, however, is not fully understood. Flotillin-1 (FLOT1) and FLOT2 are cholesterol-associated membrane proteins that form a heterodimer and/or oligomer complex. Here, we found that Anaplasma infection was significantly reduced by small interfering RNA (siRNA) knockdown of FLOT1 or FLOT2. Anaplasma inclusions were encircled with small vesicles containing endogenous FLOT1 or FLOT2 or with ectopically expressed FLOT1-mCherry and FLOT2-green fluorescent protein (FLOT2-GFP). FLOT1- and FLOT2-containing vesicles were enriched with unesterified cholesterol, as indicated by labeling with filipin and aminomethyl coumarin acetic acid-conjugated theonellamide. Localization of FLOT2 to Anaplasma inclusions was dependent on cholesterol, as FLOT2-GFP bearing two mutations in the cholesterol recognition/interaction motif could not target the inclusions. The cholesterol-sequestering agent methyl-β-cyclodextrin abrogated FLOT1 localization to Anaplasma inclusions and cleared infection. FLOT2-GFP also localized to fluorescent 3,3'-dioctadecylindocarbocyanine (DiI)-LDL-containing vesicles, including those surrounding Anaplasma inclusions. FLOT2 siRNA knockdown blocked DiI-LDL trafficking to Anaplasma inclusions and reduced bacteria-associated cholesterol amount, and therefore inhibiting Anaplasma infection. Vesicles containing acid lipase, which hydrolyzes LDL cholesterol esters to free cholesterol, colocalized with FLOT2 and encircled Anaplasma inclusions, while the acid lipase inhibitor orlistat significantly inhibited Anaplasma replication. Together, the data revealed that FLOTs are crucial for Anaplasma replication in host cells, likely by aiding vesicular traffic of LDL-derived free cholesterol to Anaplasma inclusions, and suggest a new way of inhibiting Anaplasma infection.IMPORTANCE Cholesterol is essential for animal cells, but most bacteria do not depend on cholesterol and instead lack cholesterol. However, the intracellular Gram-negative bacterium Anaplasma phagocytophilum that causes human granulocytic anaplasmosis (HGA) is unusual, as it contains significant amount of cholesterol and depends on cholesterol for survival and infection. A. phagocytophilum lacks genes for cholesterol biosynthesis or modification but acquire cholesterol from host cells exclusively from the LDL uptake pathway by a yet-to-be defined mechanism. Here, we uncovered a role of cholesterol-binding proteins FLOT1 and FLOT2 in LDL-derived cholesterol trafficking to Anaplasma inclusions and cholesterol acquisition by Anaplasma species. Importantly, we found that FLOTs localize to A. phagocytophilum-containing inclusions and the compartments containing LDL, and the acid lipase inhibitor orlistat significantly inhibits Anaplasma replication. Our data suggest a fundamental role of FLOTs in intracellular vesicular transport of LDL-derived free cholesterol and may provide insight regarding a new therapeutic target for HGA treatment.
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Santos AL, Preta G. Lipids in the cell: organisation regulates function. Cell Mol Life Sci 2018; 75:1909-1927. [PMID: 29427074 PMCID: PMC11105414 DOI: 10.1007/s00018-018-2765-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 01/04/2018] [Accepted: 01/29/2018] [Indexed: 12/19/2022]
Abstract
Lipids are fundamental building blocks of all cells and play important roles in the pathogenesis of different diseases, including inflammation, autoimmune disease, cancer, and neurodegeneration. The lipid composition of different organelles can vary substantially from cell to cell, but increasing evidence demonstrates that lipids become organised specifically in each compartment, and this organisation is essential for regulating cell function. For example, lipid microdomains in the plasma membrane, known as lipid rafts, are platforms for concentrating protein receptors and can influence intra-cellular signalling. Lipid organisation is tightly regulated and can be observed across different model organisms, including bacteria, yeast, Drosophila, and Caenorhabditis elegans, suggesting that lipid organisation is evolutionarily conserved. In this review, we summarise the importance and function of specific lipid domains in main cellular organelles and discuss recent advances that investigate how these specific and highly regulated structures contribute to diverse biological processes.
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Affiliation(s)
- Ana L Santos
- Institut National de la Santé et de la Recherche Médicale, U1001 and Faculté de Médecine, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Giulio Preta
- Institute of Biochemistry, Vilnius University, Sauletekio 7, LT-10257, Vilnius, Lithuania.
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14
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Flotillin proteins recruit sphingosine to membranes and maintain cellular sphingosine-1-phosphate levels. PLoS One 2018; 13:e0197401. [PMID: 29787576 PMCID: PMC5963794 DOI: 10.1371/journal.pone.0197401] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/30/2018] [Indexed: 01/09/2023] Open
Abstract
Sphingosine-1-phosphate (S1P) is an important lipid signalling molecule. S1P is produced via intracellular phosphorylation of sphingosine (Sph). As a lipid with a single fatty alkyl chain, Sph may diffuse rapidly between cellular membranes and through the aqueous phase. Here, we show that the absence of microdomains generated by multimeric assemblies of flotillin proteins results in reduced S1P levels. Cellular phenotypes of flotillin knockout mice, including changes in histone acetylation and expression of Isg15, are recapitulated when S1P synthesis is perturbed. Flotillins bind to Sph in vitro and increase recruitment of Sph to membranes in cells. Ectopic re-localisation of flotillins within the cell causes concomitant redistribution of Sph. The data suggest that flotillins may directly or indirectly regulate cellular sphingolipid distribution and signalling.
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15
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Haggett L, Bhasin A, Srivastava P, Fujita M. A revised model for the control of fatty acid synthesis by master regulator Spo0A in
Bacillus subtilis. Mol Microbiol 2018; 108:424-442. [DOI: 10.1111/mmi.13945] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/26/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Lindsey Haggett
- Department of Biology and BiochemistryUniversity of HoustonHouston TX 77204‐5001 USA
| | - Archna Bhasin
- Department of Biology and BiochemistryUniversity of HoustonHouston TX 77204‐5001 USA
| | - Priyanka Srivastava
- Department of Biology and BiochemistryUniversity of HoustonHouston TX 77204‐5001 USA
| | - Masaya Fujita
- Department of Biology and BiochemistryUniversity of HoustonHouston TX 77204‐5001 USA
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16
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Mielich-Süss B, Wagner RM, Mietrach N, Hertlein T, Marincola G, Ohlsen K, Geibel S, Lopez D. Flotillin scaffold activity contributes to type VII secretion system assembly in Staphylococcus aureus. PLoS Pathog 2017; 13:e1006728. [PMID: 29166667 PMCID: PMC5718613 DOI: 10.1371/journal.ppat.1006728] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 12/06/2017] [Accepted: 11/02/2017] [Indexed: 12/13/2022] Open
Abstract
Scaffold proteins are ubiquitous chaperones that promote efficient interactions between partners of multi-enzymatic protein complexes; although they are well studied in eukaryotes, their role in prokaryotic systems is poorly understood. Bacterial membranes have functional membrane microdomains (FMM), a structure homologous to eukaryotic lipid rafts. Similar to their eukaryotic counterparts, bacterial FMM harbor a scaffold protein termed flotillin that is thought to promote interactions between proteins spatially confined to the FMM. Here we used biochemical approaches to define the scaffold activity of the flotillin homolog FloA of the human pathogen Staphylococcus aureus, using assembly of interacting protein partners of the type VII secretion system (T7SS) as a case study. Staphylococcus aureus cells that lacked FloA showed reduced T7SS function, and thus reduced secretion of T7SS-related effectors, probably due to the supporting scaffold activity of flotillin. We found that the presence of flotillin mediates intermolecular interactions of T7SS proteins. We tested several small molecules that interfere with flotillin scaffold activity, which perturbed T7SS activity in vitro and in vivo. Our results suggest that flotillin assists in the assembly of S. aureus membrane components that participate in infection and influences the infective potential of this pathogen. The recently discovered functional membrane microdomains (FMM) of prokaryotic cells contain a protein homologous to the scaffold protein flotillin found in eukaryotic lipid rafts. It remains to be elucidated whether, like their eukaryotic counterparts, flotillin homolog proteins have a scaffold function in bacteria. Here we show that the Staphylococcus aureus flotillin FloA acts as a scaffold protein, to promote more efficient assembly of membrane-associated protein interacting partners of multi-enzyme complexes. In a case study, we provide biochemical evidence that FloA participates in assembly of the Type VII secretion system and thus contributes to S. aureus infective potential. Targeted dispersion of FMM-related processes using anti-FMM molecules opens up new perspectives for microbial therapies to treat persistent S. aureus infections.
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Affiliation(s)
- Benjamin Mielich-Süss
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
- Institute for Molecular Infection Biology IMIB, University of Würzburg, Würzburg, Germany
| | - Rabea M. Wagner
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
- Institute for Molecular Infection Biology IMIB, University of Würzburg, Würzburg, Germany
- National Center for Biotechnology, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
| | - Nicole Mietrach
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
- Institute for Molecular Infection Biology IMIB, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center - DFG Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Tobias Hertlein
- Institute for Molecular Infection Biology IMIB, University of Würzburg, Würzburg, Germany
| | - Gabriella Marincola
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
- Institute for Molecular Infection Biology IMIB, University of Würzburg, Würzburg, Germany
| | - Knut Ohlsen
- Institute for Molecular Infection Biology IMIB, University of Würzburg, Würzburg, Germany
| | - Sebastian Geibel
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
- Institute for Molecular Infection Biology IMIB, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center - DFG Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Daniel Lopez
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
- Institute for Molecular Infection Biology IMIB, University of Würzburg, Würzburg, Germany
- National Center for Biotechnology, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
- * E-mail:
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17
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Koch G, Wermser C, Acosta IC, Kricks L, Stengel ST, Yepes A, Lopez D. Attenuating Staphylococcus aureus Virulence by Targeting Flotillin Protein Scaffold Activity. Cell Chem Biol 2017; 24:845-857.e6. [PMID: 28669526 DOI: 10.1016/j.chembiol.2017.05.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 04/11/2017] [Accepted: 05/30/2017] [Indexed: 01/13/2023]
Abstract
Scaffold proteins are ubiquitous chaperones that bind proteins and facilitate physical interaction of multi-enzyme complexes. Here we used a biochemical approach to dissect the scaffold activity of the flotillin-homolog protein FloA of the multi-drug-resistant human pathogen Staphylococcus aureus. We show that FloA promotes oligomerization of membrane protein complexes, such as the membrane-associated RNase Rny, which forms part of the RNA-degradation machinery called the degradosome. Cells lacking FloA had reduced Rny function and a consequent increase in the targeted sRNA transcripts that negatively regulate S. aureus toxin expression. Small molecules that altered FloA oligomerization also reduced Rny function and decreased the virulence potential of S. aureus in vitro, as well as in vivo, using invertebrate and murine infection models. Our results suggest that flotillin assists in the assembly of protein complexes involved in S. aureus virulence, and could thus be an attractive target for the development of new antimicrobial therapies.
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Affiliation(s)
- Gudrun Koch
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany; Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany
| | - Charlotte Wermser
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany; Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany
| | - Ivan C Acosta
- National Centre for Biotechnology (CNB), Spanish Research Council (CSIC), Darwin 3, Madrid 28049, Spain
| | - Lara Kricks
- National Centre for Biotechnology (CNB), Spanish Research Council (CSIC), Darwin 3, Madrid 28049, Spain
| | - Stephanie T Stengel
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany; Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany
| | - Ana Yepes
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany; Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany
| | - Daniel Lopez
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany; Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany; National Centre for Biotechnology (CNB), Spanish Research Council (CSIC), Darwin 3, Madrid 28049, Spain.
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18
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Calpain inhibition prevents flotillin re-ordering and Src family activation during capacitation. Cell Tissue Res 2017; 369:395-412. [DOI: 10.1007/s00441-017-2591-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 02/17/2017] [Indexed: 01/08/2023]
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19
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microRNA-802 inhibits epithelial-mesenchymal transition through targeting flotillin-2 in human prostate cancer. Biosci Rep 2017; 37:BSR20160521. [PMID: 28188157 PMCID: PMC5350603 DOI: 10.1042/bsr20160521] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 02/08/2017] [Accepted: 02/10/2017] [Indexed: 12/26/2022] Open
Abstract
miRNAs are a class of non-coding RNAs that exert critical roles in various biological processes. The aim of the present study was to identify the functional roles of miR-802 in regulating epithelial-mesenchymal transition (EMT) in prostate cancer (PCa). miR-802 expression was detected in 73 pairs of PCa samples and PCa cell lines (PC3 and DU145 cells) by qRT-PCR. Cell proliferation was detected using MTT assay, and cell apoptosis was evaluated using flow cytometry. Transwell assay was conducted to investigate cell migration and invasion. Expression analysis of a set of EMT markers was performed to explore whether miR-802 is involved in EMT program. Xenograft model was established to investigate the function of miR-802 in carcinogenesis in vivo The direct regulation of Flotillin-2 (Flot2) by miR-802 was identified using luciferase reporter assay. miR-802 was remarkably down-regulated in PCa tissues and cell lines. Gain-of-function trails showed that miR-802 serves as an 'oncosuppressor' in PCa through inhibiting cell proliferation and promoting cell apoptosis in vitro Overexpression of miR-802 significantly suppressed in vivo PCa tumor growth. Luciferase reporter analysis identified Flot2 as a direct target of miR-802 in PCa cells. Overexpressed miR-802 significantly suppressed EMT, migration and invasion in PCa cells by regulating Flot2. We identified miR-802 as a novel tumor suppressor in PCa progression and elucidated a novel mechanism of the miR-802/Flot2 axis in the regulation of EMT, which may be a potential therapeutic target.
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20
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Lopez D, Koch G. Exploring functional membrane microdomains in bacteria: an overview. Curr Opin Microbiol 2017; 36:76-84. [PMID: 28237903 DOI: 10.1016/j.mib.2017.02.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 02/01/2017] [Indexed: 01/08/2023]
Abstract
Recent studies show that internal organization of bacterial cells is more complex than previously appreciated. A clear example of this is the assembly of the nanoscale membrane platforms termed functional membrane microdomains. The lipid composition of these regions differs from that of the surrounding membrane; these domains confine a set of proteins involved in specific cellular processes such as protease secretion and signal transduction. It is currently thought that functional membrane microdomains act as oligomerization platforms and promote efficient oligomerization of interacting protein partners in bacterial membranes. In this review, we highlight the most noteworthy achievements, challenges and controversies of this emerging research field over the past five years.
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Affiliation(s)
- Daniel Lopez
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany; Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany; Spanish National Centre for Biotechnology (CNB), Madrid 28049, Spain.
| | - Gudrun Koch
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany; Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany
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21
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Montenegro MF, Cabezas-Herrera J, Campoy FJ, Muñoz-Delgado E, Vidal CJ. Lipid rafts of mouse liver contain nonextended and extended acetylcholinesterase variants along with M3 muscarinic receptors. FASEB J 2016; 31:544-555. [PMID: 28148778 DOI: 10.1096/fj.201600609r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/11/2016] [Indexed: 12/25/2022]
Abstract
The observation of acetylcholinesterase (AChE) type H (AChEH), which is the predominant AChE variant in visceral organs and immune cells, in lipid rafts of muscle supports functional reasons for the raft targeting of glypiated AChEH The search for these reasons revealed that liver AChE activity is mostly confined to rafts and that the liver is able to make N-extended AChE variants and target them to rafts. These results prompted us to test whether AChE and muscarinic receptors existed in the same raft. Isolation of flotillin-2-rich raft fractions by their buoyancy in sucrose gradients, followed by immunoadsorption and matrix-assisted laser desorption ionization-time of flight-mass spectrometry application, gave the following results: 1) most hepatic AChE activity emanates from AChE-H mRNA, and its product, glypiated AChEH, accumulates in rafts; 2) N-extended N-AChE readthrough variant, nonglypiated N-AChEH, and N-AChE tailed variant were all identified in liver rafts; and 3) M3 AChRs were observed in rafts, and coprecipitation of raft-confined N-AChE and M3 receptors by using anti-M3 antibodies showed that enzyme and receptor reside in the same raft unit. A raft domain that harbors tightly packed muscarinic receptor and AChE may represent a molecular device that, by means of which, the intensity and duration of cholinergic inputs are regulated.-Montenegro, M. F., Cabezas-Herrera, J., Campoy, F. J., Muñoz-Delgado, E., Vidal, C. J. Lipid rafts of mouse liver contain nonextended and extended acetylcholinesterase variants along with M3 muscarinic receptors.
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Affiliation(s)
- María Fernanda Montenegro
- Departamento de Bioquímica y Biología Molecular-A, Instituto Murciano de Investigación Biosanitaria (IMIB), Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum," Murcia, Spain; and
| | - Juan Cabezas-Herrera
- Molecular Therapy and Biomarkers Research Group, Clinical Analysis Service, University Hospital Virgen de la Arrixaca, IMIB-Arrixaca, Murcia, Spain
| | - F Javier Campoy
- Departamento de Bioquímica y Biología Molecular-A, Instituto Murciano de Investigación Biosanitaria (IMIB), Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum," Murcia, Spain; and
| | - Encarnación Muñoz-Delgado
- Departamento de Bioquímica y Biología Molecular-A, Instituto Murciano de Investigación Biosanitaria (IMIB), Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum," Murcia, Spain; and
| | - Cecilio J Vidal
- Departamento de Bioquímica y Biología Molecular-A, Instituto Murciano de Investigación Biosanitaria (IMIB), Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum," Murcia, Spain; and
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22
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Dempwolff F, Schmidt FK, Hervás AB, Stroh A, Rösch TC, Riese CN, Dersch S, Heimerl T, Lucena D, Hülsbusch N, Stuermer CAO, Takeshita N, Fischer R, Eckhardt B, Graumann PL. Super Resolution Fluorescence Microscopy and Tracking of Bacterial Flotillin (Reggie) Paralogs Provide Evidence for Defined-Sized Protein Microdomains within the Bacterial Membrane but Absence of Clusters Containing Detergent-Resistant Proteins. PLoS Genet 2016; 12:e1006116. [PMID: 27362352 PMCID: PMC4928834 DOI: 10.1371/journal.pgen.1006116] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 05/20/2016] [Indexed: 12/14/2022] Open
Abstract
Biological membranes have been proposed to contain microdomains of a specific lipid composition, in which distinct groups of proteins are clustered. Flotillin-like proteins are conserved between pro—and eukaryotes, play an important function in several eukaryotic and bacterial cells, and define in vertebrates a type of so-called detergent-resistant microdomains. Using STED microscopy, we show that two bacterial flotillins, FloA and FloT, form defined assemblies with an average diameter of 85 to 110 nm in the model bacterium Bacillus subtilis. Interestingly, flotillin microdomains are of similar size in eukaryotic cells. The soluble domains of FloA form higher order oligomers of up to several hundred kDa in vitro, showing that like eukaryotic flotillins, bacterial assemblies are based in part on their ability to self-oligomerize. However, B. subtilis paralogs show significantly different diffusion rates, and consequently do not colocalize into a common microdomain. Dual colour time lapse experiments of flotillins together with other detergent-resistant proteins in bacteria show that proteins colocalize for no longer than a few hundred milliseconds, and do not move together. Our data reveal that the bacterial membrane contains defined-sized protein domains rather than functional microdomains dependent on flotillins. Based on their distinct dynamics, FloA and FloT confer spatially distinguishable activities, but do not serve as molecular scaffolds. Many membrane proteins are not uniformly distributed within biological membranes, and may prefer specific lipid environments to function optimally. Using super resolution fluorescence microscopy, we show that several Bacillus subtilis membrane proteins indeed cluster into structures of 60 to 110 nm, verifying the existence of defined-size protein microdomains. Biochemical co-isolation of specific membrane proteins and flotillins, a family of proteins highly conserved between eukaryotic and bacterial cells, suggested that common “functional” microdomains exist, containing so-called “detergent-resistant” membrane proteins, that are centered by flotillins. Through high speed tracking of Bacillus subtilis FloA and FloT we show that both proteins are not present in the same microdomain, but move through the membrane with different velocities. Dual colour time lapse microscopy showed that contrarily to vertebrate flotillins, bacterial flotillins do not move together with detergent-resistant proteins, ruling out the existence of coclusters. The lack of both flotillins, but not of a single one, leads to striking defects in cell shape and in cell growth, indicating important overlapping functions of flotillin paralogs. Our data show that FloA and FloT perform spatially distinct functions, possibly in the insertion of membrane proteins that require a specific lipid environment, based on a close connection between FloA and FloT with the Sec membrane insertion machinery, but do not act as scaffolds for detergent resistant proteins. Our tracking analyses provide an important basis for the understanding of interactions between membrane proteins in living cells.
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Affiliation(s)
- Felix Dempwolff
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Felix K. Schmidt
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Physics, Philipps Universität Marburg, Marburg, Germany
| | - Ana B. Hervás
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Alex Stroh
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Thomas C. Rösch
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Cornelius N. Riese
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Biology, Philipps Universität Marburg, Marburg, Germany
| | - Simon Dersch
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Thomas Heimerl
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Biology, Philipps Universität Marburg, Marburg, Germany
| | - Daniella Lucena
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Nikola Hülsbusch
- Department of Biology, University of Konstanz, Konstanz, Germany
| | | | - Norio Takeshita
- University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki, Japan
- Department of Microbiology, Institute for Applied Bioscience, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Reinhard Fischer
- Department of Microbiology, Institute for Applied Bioscience, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Bruno Eckhardt
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Physics, Philipps Universität Marburg, Marburg, Germany
| | - Peter L. Graumann
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
- * E-mail:
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23
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Kim JM, Cha SH, Choi YR, Jou I, Joe EH, Park SM. DJ-1 deficiency impairs glutamate uptake into astrocytes via the regulation of flotillin-1 and caveolin-1 expression. Sci Rep 2016; 6:28823. [PMID: 27346864 PMCID: PMC4922019 DOI: 10.1038/srep28823] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 06/10/2016] [Indexed: 12/12/2022] Open
Abstract
Parkinson’s disease (PD) is a common chronic and progressive neurodegenerative disorder. Although the cause of PD is still poorly understood, mutations in many genes including SNCA, parkin, PINK1, LRRK2, and DJ-1 have been identified in the familial forms of PD. It was recently proposed that alterations in lipid rafts may cause the neurodegeneration shown in PD. Here, we observe that DJ-1 deficiency decreased the expression of flotillin-1 (flot-1) and caveolin-1 (cav-1), the main protein components of lipid rafts, in primary astrocytes and MEF cells. As a mechanism, DJ-1 regulated flot-1 stability by direct interaction, however, decreased cav-1 expression may not be a direct effect of DJ-1, but rather as a result of decreased flot-1 expression. Dysregulation of flot-1 and cav-1 by DJ-1 deficiency caused an alteration in the cellular cholesterol level, membrane fluidity, and alteration in lipid rafts-dependent endocytosis. Moreover, DJ-1 deficiency impaired glutamate uptake into astrocytes, a major function of astrocytes in the maintenance of CNS homeostasis, by altering EAAT2 expression. This study will be helpful to understand the role of DJ-1 in the pathogenesis of PD, and the modulation of lipid rafts through the regulation of flot-1 or cav-1 may be a novel therapeutic target for PD.
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Affiliation(s)
- Jin-Mo Kim
- Department of Pharmacology, Ajou University School of Medicine, Suwon, Korea.,Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, Korea
| | - Seon-Heui Cha
- Department of Pharmacology, Ajou University School of Medicine, Suwon, Korea.,Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, Korea
| | - Yu Ree Choi
- Department of Pharmacology, Ajou University School of Medicine, Suwon, Korea.,Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, Korea.,Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Korea
| | - Ilo Jou
- Department of Pharmacology, Ajou University School of Medicine, Suwon, Korea.,Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, Korea.,Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Korea
| | - Eun-Hye Joe
- Department of Pharmacology, Ajou University School of Medicine, Suwon, Korea.,Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, Korea.,Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Korea
| | - Sang Myun Park
- Department of Pharmacology, Ajou University School of Medicine, Suwon, Korea.,Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, Korea.,Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Korea
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24
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Lopez D. Molecular composition of functional microdomains in bacterial membranes. Chem Phys Lipids 2015; 192:3-11. [PMID: 26320704 DOI: 10.1016/j.chemphyslip.2015.08.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 08/10/2015] [Accepted: 08/24/2015] [Indexed: 12/14/2022]
Abstract
Membranes of eukaryotic cells organize a number of proteins related to signal transduction and membrane trafficking into microdomains, which are enriched in particular lipids, like cholesterol and sphingolipids and are commonly referred as to lipid rafts or membrane rafts. The existence of this type of signaling platforms was traditionally associated with eukaryotic membranes because prokaryotic cells were considered too simple organisms to require a sophisticated organization of their signaling networks. However, the research that have been performed during last years have shown that bacteria organize many signaling transduction processes in Functional Membrane Microdomains (FMMs), which are similar to the lipid rafts that are found in eukaryotic cells. The current knowledge of the existence of FMMs in bacteria is described in this review and the specific structural and biological properties of these membrane microdomains are introduced. The organization of FMMs in bacterial membranes reveals an unexpected level of sophistication in signaling transduction and membrane organization that is unprecedented in bacteria, suggesting that bacteria as more complex organisms than previously considered.
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Affiliation(s)
- Daniel Lopez
- Research Center for Infectious Diseases (ZINF), Institute for Molecular Infection Biology (IMIB), University of Würzburg, Josef-Schneider Strasse (2), 97080 Würzburg, Germany; Spanish National Center for Biotechnology (CNB), Campus de Cantoblanco, Darwin 3, 28049 Madrid, Spain.
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25
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Schneider J, Mielich-Süss B, Böhme R, Lopez D. In vivo characterization of the scaffold activity of flotillin on the membrane kinase KinC of Bacillus subtilis. MICROBIOLOGY-SGM 2015; 161:1871-1887. [PMID: 26297017 DOI: 10.1099/mic.0.000137] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Scaffold proteins are ubiquitous chaperones that bind to proteins and facilitate the physical interaction of the components of signal transduction pathways or multi-enzymic complexes. In this study, we used a biochemical approach to dissect the molecular mechanism of a membrane-associated scaffold protein, FloT, a flotillin-homologue protein that is localized in functional membrane microdomains of the bacterium Bacillus subtilis. This study provides unambiguous evidence that FloT physically binds to and interacts with the membrane-bound sensor kinase KinC. This sensor kinase activates biofilm formation in B. subtilis in response to the presence of the self-produced signal surfactin. Furthermore, we have characterized the mechanism by which the interaction of FloT with KinC benefits the activity of KinC. Two separate and synergistic effects constitute this mechanism: first, the scaffold activity of FloT promotes more efficient self-interaction of KinC and facilitates dimerization into its active form. Second, the selective binding of FloT to KinC prevents the occurrence of unspecific aggregation between KinC and other proteins that may generate dead-end intermediates that could titrate the activity of KinC. Flotillin proteins appear to play an important role in prokaryotes in promoting effective binding of signalling proteins with their correct protein partners.
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Affiliation(s)
- Johannes Schneider
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany
| | - Benjamin Mielich-Süss
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany
| | - Richard Böhme
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany
| | - Daniel Lopez
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg 97080, Germany
- National Center for Biotechnology (CNB), Spanish Research Council (CSIC), Madrid 28050, Spain
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, Würzburg 97080, Germany
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26
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Schneider J, Klein T, Mielich-Süss B, Koch G, Franke C, Kuipers OP, Kovács ÁT, Sauer M, Lopez D. Spatio-temporal remodeling of functional membrane microdomains organizes the signaling networks of a bacterium. PLoS Genet 2015; 11:e1005140. [PMID: 25909364 PMCID: PMC4409396 DOI: 10.1371/journal.pgen.1005140] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 03/11/2015] [Indexed: 11/18/2022] Open
Abstract
Lipid rafts are membrane microdomains specialized in the regulation of numerous cellular processes related to membrane organization, as diverse as signal transduction, protein sorting, membrane trafficking or pathogen invasion. It has been proposed that this functional diversity would require a heterogeneous population of raft domains with varying compositions. However, a mechanism for such diversification is not known. We recently discovered that bacterial membranes organize their signal transduction pathways in functional membrane microdomains (FMMs) that are structurally and functionally similar to the eukaryotic lipid rafts. In this report, we took advantage of the tractability of the prokaryotic model Bacillus subtilis to provide evidence for the coexistence of two distinct families of FMMs in bacterial membranes, displaying a distinctive distribution of proteins specialized in different biological processes. One family of microdomains harbors the scaffolding flotillin protein FloA that selectively tethers proteins specialized in regulating cell envelope turnover and primary metabolism. A second population of microdomains containing the two scaffolding flotillins, FloA and FloT, arises exclusively at later stages of cell growth and specializes in adaptation of cells to stationary phase. Importantly, the diversification of membrane microdomains does not occur arbitrarily. We discovered that bacterial cells control the spatio-temporal remodeling of microdomains by restricting the activation of FloT expression to stationary phase. This regulation ensures a sequential assembly of functionally specialized membrane microdomains to strategically organize signaling networks at the right time during the lifespan of a bacterium. Cellular membranes organize proteins related to signal transduction, protein sorting and membrane trafficking into the so-called lipid rafts. It has been proposed that the functional diversity of lipid rafts would require a heterogeneous population of raft domains with varying compositions. However, a mechanism for such diversification is not known due in part to the complexity that entails the manipulation of eukaryotic cells. The recent discovery that bacteria organize many cellular processes in membrane microdomains (FMMs), functionally similar to the eukaryotic lipid rafts, prompted us to explore FMMs diversity in the bacterial model Bacillus subtilis. We show that diversification of FMMs occurs in cells and gives rise to functionally distinct microdomains, which compartmentalize distinct signal transduction pathways and regulate the expression of different genetic programs. We discovered that FMMs diversification does not occur randomly. Cells sequentially regulate the specialization of the FMMs during cell growth to ensure an effective and diverse activation of signaling processes.
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Affiliation(s)
- Johannes Schneider
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
| | - Teresa Klein
- Department of Biotechnology and Biophysics, University of Würzburg, Würzburg, Germany
| | - Benjamin Mielich-Süss
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
| | - Gudrun Koch
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
| | - Christian Franke
- Department of Biotechnology and Biophysics, University of Würzburg, Würzburg, Germany
| | - Oscar P. Kuipers
- Molecular Genetics Group,Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Ákos T. Kovács
- Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University of Jena, Jena, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, University of Würzburg, Würzburg, Germany
| | - Daniel Lopez
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
- * E-mail:
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27
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Abstract
An interesting concept in the organization of cellular membranes is the proposed existence of lipid rafts. Membranes of eukaryotic cells organize signal transduction proteins into membrane rafts or lipid rafts that are enriched in particular lipids such as cholesterol and are important for the correct functionality of diverse cellular processes. The assembly of lipid rafts in eukaryotes has been considered a fundamental step during the evolution of cellular complexity, suggesting that bacteria and archaea were organisms too simple to require such a sophisticated organization of their cellular membranes. However, it was recently discovered that bacteria organize many signal transduction, protein secretion, and transport processes in functional membrane microdomains, which are equivalent to the lipid rafts of eukaryotic cells. This review contains the most significant advances during the last 4 years in understanding the structural and biological role of lipid rafts in bacteria. Furthermore, this review shows a detailed description of a number of molecular and genetic approaches related to the discovery of bacterial lipid rafts as well as an overview of the group of tentative lipid-protein and protein-protein interactions that give consistency to these sophisticated signaling platforms. Additional data suggesting that lipid rafts are widely distributed in bacteria are presented in this review. Therefore, we discuss the available techniques and optimized protocols for the purification and analysis of raft-associated proteins in various bacterial species to aid in the study of bacterial lipid rafts in other laboratories that could be interested in this topic. Overall, the discovery of lipid rafts in bacteria reveals a new level of sophistication in signal transduction and membrane organization that was unexpected for bacteria and shows that bacteria are more complex than previously appreciated.
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Affiliation(s)
- Marc Bramkamp
- Department of Biology I, University of Munich (LMU), Planegg/Martinsried, Germany
| | - Daniel Lopez
- Research Center for Infectious Diseases ZINF, University of Würzburg, Würzburg, Germany
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28
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Aureli M, Grassi S, Prioni S, Sonnino S, Prinetti A. Lipid membrane domains in the brain. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1006-16. [PMID: 25677824 DOI: 10.1016/j.bbalip.2015.02.001] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 01/29/2015] [Accepted: 02/01/2015] [Indexed: 12/28/2022]
Abstract
The brain is characterized by the presence of cell types with very different functional specialization, but with the common trait of a very high complexity of structures originated by their plasma membranes. Brain cells bear evident membrane polarization with the creation of different morphological and functional subcompartments, whose formation, stabilization and function require a very high level of lateral order within the membrane. In other words, the membrane specialization of brain cells implies the presence of distinct membrane domains. The brain is the organ with the highest enrichment in lipids like cholesterol, glycosphingolipids, and the most recently discovered brain membrane lipid, phosphatidylglucoside, whose collective behavior strongly favors segregation within the membrane leading to the formation of lipid-driven membrane domains. Lipid-driven membrane domains function as dynamic platforms for signal transduction, protein processing, and membrane turnover. Essential events involved in the development and in the maintenance of the functional integrity of the brain depend on the organization of lipid-driven membrane domains, and alterations in lipid homeostasis, leading to deranged lipid-driven membrane organization, are common in several major brain diseases. In this review, we summarize the forces behind the formation of lipid membrane domains and their biological roles in different brain cells. This article is part of a Special Issue entitled Brain Lipids.
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Affiliation(s)
- Massimo Aureli
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Italy
| | - Sara Grassi
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Italy
| | - Simona Prioni
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Italy
| | - Sandro Sonnino
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Italy
| | - Alessandro Prinetti
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Italy.
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29
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Liebert A, Bicknell B, Adams R. Prion Protein Signaling in the Nervous System—A Review and Perspective. ACTA ACUST UNITED AC 2014. [DOI: 10.4137/sti.s12319] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Prion protein (PrPC) was originally known as the causative agent of transmissible spongiform encephalopathy (TSE) but with recent research, its true function in cells is becoming clearer. It is known to act as a scaffolding protein, binding multiple ligands at the cell membrane and to be involved in signal transduction, passing information from the extracellular matrix (ECM) to the cytoplasm. Its role in the coordination of transmitters at the synapse, glyapse, and gap junction and in short- and long-range neurotrophic signaling gives PrPC a major part in neural transmission and nervous system signaling. It acts to regulate cellular function in multiple targets through its role as a controller of redox status and calcium ion flux. Given the importance of PrPC in cell physiology, this review considers its potential role in disease apart from TSE. The putative functions of PrPC point to involvement in neurodegenerative disease, neuropathic pain, chronic headache, and inflammatory disease including neuroinflammatory disease of the nervous system. Potential targets for the treatment of disease influenced by PrPC are discussed.
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Affiliation(s)
- Ann Liebert
- Faculty of Health Science, University of Sydney, Australia
| | - Brian Bicknell
- Faculty of Health Science, Australian Catholic University, Australia
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30
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Halliez S, Passet B, Martin-Lannerée S, Hernandez-Rapp J, Laude H, Mouillet-Richard S, Vilotte JL, Béringue V. To develop with or without the prion protein. Front Cell Dev Biol 2014; 2:58. [PMID: 25364763 PMCID: PMC4207017 DOI: 10.3389/fcell.2014.00058] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 09/22/2014] [Indexed: 12/23/2022] Open
Abstract
The deletion of the cellular form of the prion protein (PrPC) in mouse, goat, and cattle has no drastic phenotypic consequence. This stands in apparent contradiction with PrPC quasi-ubiquitous expression and conserved primary and tertiary structures in mammals, and its pivotal role in neurodegenerative diseases such as prion and Alzheimer's diseases. In zebrafish embryos, depletion of PrP ortholog leads to a severe loss-of-function phenotype. This raises the question of a potential role of PrPC in the development of all vertebrates. This view is further supported by the early expression of the PrPC encoding gene (Prnp) in many tissues of the mouse embryo, the transient disruption of a broad number of cellular pathways in early Prnp−/− mouse embryos, and a growing body of evidence for PrPC involvement in the regulation of cell proliferation and differentiation in various types of mammalian stem cells and progenitors. Finally, several studies in both zebrafish embryos and in mammalian cells and tissues in formation support a role for PrPC in cell adhesion, extra-cellular matrix interactions and cytoskeleton. In this review, we summarize and compare the different models used to decipher PrPC functions at early developmental stages during embryo- and organo-genesis and discuss their relevance.
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Affiliation(s)
- Sophie Halliez
- Institut National de la Recherche Agronomique, U892 Virologie et Immunologie Moléculaires Jouy-en-Josas, France
| | - Bruno Passet
- Institut National de la Recherche Agronomique, UMR1313 Génétique Animale et Biologie Intégrative Jouy-en-Josas, France
| | - Séverine Martin-Lannerée
- Institut National de la Santé et de la Recherche Médicale, UMR-S1124 Paris, France ; Université Paris Descartes, Sorbonne Paris Cité, UMR-S1124 Paris, France
| | - Julia Hernandez-Rapp
- Institut National de la Santé et de la Recherche Médicale, UMR-S1124 Paris, France ; Université Paris Descartes, Sorbonne Paris Cité, UMR-S1124 Paris, France
| | - Hubert Laude
- Institut National de la Recherche Agronomique, U892 Virologie et Immunologie Moléculaires Jouy-en-Josas, France
| | - Sophie Mouillet-Richard
- Institut National de la Santé et de la Recherche Médicale, UMR-S1124 Paris, France ; Université Paris Descartes, Sorbonne Paris Cité, UMR-S1124 Paris, France
| | - Jean-Luc Vilotte
- Institut National de la Recherche Agronomique, UMR1313 Génétique Animale et Biologie Intégrative Jouy-en-Josas, France
| | - Vincent Béringue
- Institut National de la Recherche Agronomique, U892 Virologie et Immunologie Moléculaires Jouy-en-Josas, France
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31
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Bitsikas V, Corrêa IR, Nichols BJ. Clathrin-independent pathways do not contribute significantly to endocytic flux. eLife 2014; 3:e03970. [PMID: 25232658 PMCID: PMC4185422 DOI: 10.7554/elife.03970] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/15/2014] [Indexed: 12/25/2022] Open
Abstract
Several different endocytic pathways have been proposed to function in mammalian cells. Clathrin-coated pits are well defined, but the identity, mechanism and function of alternative pathways have been controversial. Here we apply universal chemical labelling of plasma membrane proteins to define all primary endocytic vesicles, and labelling of specific proteins with a reducible SNAP-tag substrate. These approaches provide high temporal resolution and stringent discrimination between surface-connected and intracellular membranes. We find that at least 95% of the earliest detectable endocytic vesicles arise from clathrin-coated pits. GPI-anchored proteins, candidate cargoes for alternate pathways, are also found to enter the cell predominantly via coated pits. Experiments employing a mutated clathrin adaptor reveal distinct mechanisms for sorting into coated pits, and thereby explain differential effects on the uptake of transferrin and GPI-anchored proteins. These data call for a revision of models for the activity and diversity of endocytic pathways in mammalian cells. DOI:http://dx.doi.org/10.7554/eLife.03970.001 Cells are enclosed by a ‘plasma membrane’ that allows nutrients and certain small molecules to move in and out of cells. Larger molecules—such as proteins—are carried into cells through a process known as endocytosis, where part of the plasma membrane engulfs the molecule and transports it through the cell inside a bubble-like compartment called a vesicle. There may be several different ways by which endocytosis can occur. The most common method involves a protein known as clathrin, which coats part of the plasma membrane on the side facing the inside of the cell. This causes the membrane to deform into a pit. The pit grows around, and eventually completely surrounds, the molecule to be transported, at which point the clathrin-coated membrane pinches off from the rest of the plasma membrane to form a vesicle. Other forms of endocytosis do not need clathrin to form vesicles, and so are collectively known as clathrin-independent endocytosis. However, the details of how these other types of endocytosis work and how important they are for moving molecules into the cell remain unclear. This is partly because it is difficult to identify particular types of endocytosis. Previous attempts to do this have involved trying to identify molecules that are specifically and solely associated with that type of endocytosis, and using these to track the vesicle. However, few—if any—such molecules are known for clathrin-independent methods of endocytosis. Another approach is to inhibit the formation of clathrin-coated pits and study those molecules that are still taken into cells. The problem here is that incomplete inhibition can make interpreting the results difficult. Furthermore, complete inhibition of an important process like clathrin-dependent endocytosis is likely to have severe effects on many other aspects of cell function. Bitsikas et al. have developed a new method that allows a vesicle to be identified—regardless of how it forms—in cells that have not been treated with inhibitors. This method involves labelling proteins in the plasma membrane with a chemical that allows them to be traced, and so shows when they are included in vesicle membranes. Importantly, this new method can provide very accurate information as to whether or not proteins have been included in vesicles, and this may provide advantages over previous approaches. Bitsikas et al. selected a group of proteins that are thought to only enter cells in a clathrin-independent manner, but unexpectedly found that these proteins predominantly enter cells through clathrin-coated vesicles. Further analysis revealed that approximately 95% of all molecules that enter cells by endocytosis are taken up via clathrin-coated endocytosis. Therefore, clathrin-independent endocytosis does not make a significant contribution to the transport of large molecules into cells. These results are at odds with current thinking in the field. Future work could reveal whether the techniques applied by Bitsikas et al. detect more active clathrin-independent endocytosis in special situations, for example during cell migration, or in specific cell types. DOI:http://dx.doi.org/10.7554/eLife.03970.002
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Affiliation(s)
- Vassilis Bitsikas
- Department of Cell Biology, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | | | - Benjamin J Nichols
- Department of Cell Biology, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
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32
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Petit CSV, Besnier L, Morel E, Rousset M, Thenet S. Roles of the cellular prion protein in the regulation of cell-cell junctions and barrier function. Tissue Barriers 2014; 1:e24377. [PMID: 24665391 PMCID: PMC3887058 DOI: 10.4161/tisb.24377] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 03/18/2013] [Accepted: 03/19/2013] [Indexed: 01/12/2023] Open
Abstract
The cellular prion protein was historically characterized owing to its misfolding in prion disease. Although its physiological role remains incompletely understood, PrP(C) has emerged as an evolutionary conserved, multifaceted protein involved in a wide-range of biological processes. PrP(C) is a GPI-anchored protein targeted to the plasma membrane, in raft microdomains, where its interaction with a repertoire of binding partners, which differ depending on cell models, mediates its functions. Among identified PrP(C) partners are cell adhesion molecules. This review will focus on the multiple implications of PrP(C) in cell adhesion processes, mainly the regulation of cell-cell junctions in epithelial and endothelial cells and the consequences on barrier properties. We will show how recent findings argue for a role of PrP(C) in the recruitment of signaling molecules, which in turn control the targeting or the stability of adhesion complexes at the plasma membrane.
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Affiliation(s)
- Constance S V Petit
- Centre de Recherche des Cordeliers; Université Pierre et Marie Curie; Paris, France ; INSERM; Paris, France ; Université Paris Descartes; Paris, France
| | - Laura Besnier
- Centre de Recherche des Cordeliers; Université Pierre et Marie Curie; Paris, France ; INSERM; Paris, France ; Université Paris Descartes; Paris, France
| | - Etienne Morel
- Centre de Recherche des Cordeliers; Université Pierre et Marie Curie; Paris, France ; INSERM; Paris, France ; Université Paris Descartes; Paris, France
| | - Monique Rousset
- Centre de Recherche des Cordeliers; Université Pierre et Marie Curie; Paris, France ; INSERM; Paris, France ; Université Paris Descartes; Paris, France
| | - Sophie Thenet
- Centre de Recherche des Cordeliers; Université Pierre et Marie Curie; Paris, France ; INSERM; Paris, France ; Université Paris Descartes; Paris, France ; Ecole Pratique des Hautes Etudes; Laboratoire de Pharmacologie Cellulaire et Moléculaire ; Paris, France
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The inhibition of functional expression of calcium channels by prion protein demonstrates competition with α2δ for GPI-anchoring pathways. Biochem J 2014; 458:365-74. [PMID: 24329154 PMCID: PMC3924758 DOI: 10.1042/bj20131405] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
It has been shown recently that PrP (prion protein) and the calcium channel auxiliary α2δ subunits interact in neurons and expression systems [Senatore, Colleoni, Verderio, Restelli, Morini, Condliffe, Bertani, Mantovani, Canovi, Micotti, Forloni, Dolphin, Matteoli, Gobbi and Chiesa (2012) Neuron 74, 300-313]. In the present study we examined whether there was an effect of PrP on calcium currents. We have shown that when PrP is co-expressed with calcium channels formed from CaV2.1/β and α2δ-1 or α2δ-2, there is a consistent decrease in calcium current density. This reduction was absent when a PrP construct was used lacking its GPI (glycosylphosphatidylinositol) anchor. We have reported previously that α2δ subunits are able to form GPI-anchored proteins [Davies, Kadurin, Alvarez-Laviada, Douglas, Nieto-Rostro, Bauer, Pratt and Dolphin (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 1654-1659] and show further evidence in the present paper. We have characterized recently a C-terminally truncated α2δ-1 construct, α2δ-1ΔC, and found that, despite loss of its membrane anchor, it still shows a partial ability to increase calcium currents [Kadurin, Alvarez-Laviada, Ng, Walker-Gray, D'Arco, Fadel, Pratt and Dolphin (2012) J. Biol. Chem. 1287, 33554-33566]. We now find that PrP does not inhibit CaV2.1/β currents formed with α2δ-1ΔC, rather than α2δ-1. It is possible that PrP and α2δ-1 compete for GPI-anchor intermediates or trafficking pathways, or that interaction between PrP and α2δ-1 requires association in cholesterol-rich membrane microdomains. Our additional finding that CaV2.1/β1b/α2δ-1 currents were inhibited by GPI-GFP, but not cytosolic GFP, indicates that competition for limited GPI-anchor intermediates or trafficking pathways may be involved in PrP suppression of α2δ subunit function.
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34
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Montenegro MF, Moral-Naranjo MT, Campoy FJ, Muñoz-Delgado E, Vidal CJ. The lipid raft-bound alkaline phosphatase activity increases and the level of transcripts remains unaffected in liver of merosin-deficient LAMA2dy mouse. Chem Biol Interact 2014; 216:1-8. [PMID: 24680793 DOI: 10.1016/j.cbi.2014.03.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 03/04/2014] [Accepted: 03/18/2014] [Indexed: 12/19/2022]
Abstract
Alkaline phosphatase (AP) and other proteins add glycosylphosphatidylinositol (GPI) before addressing to raft domains of the cell membrane. Our previous report showing an increased density of lipid rafts in muscle of dystrophic Lama2dy mice prompted us to compare livers of normal (NL) and dystrophic mice (DL) for their levels of rafts. With this aim, hepatic rafts were isolated as Triton X-100 resistant membranes, and identified by their abundance of flotillin-2, alkaline phosphatase (AP) and other raft markers. The comparable abundance of cholesterol and flotillin-2 in rafts of NL and DL contrasted with the double AP activity both in rafts of DL and whole DL. The AP mRNA level was the same in NL and DL. Sedimentation analysis profiles revealed AP activity of NL distributed between dimeric (dAP) and monomeric AP (mAP), whose proportions and lectin-binding extent changed in DL. The increased AP activity and changed AP glycosylation in DL, the prevalence of mAP in NL and the enhanced stability of dAP in DL demonstrated the critical role that glycosylation and oligomerization play for AP catalysis. The higher AP activity of DL probably arises from dystrophy-associated changes in glycosyl transferases, which alter AP glycosylation and subunit folding with profitable effects for AP stability and catalysis.
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Affiliation(s)
- María Fernanda Montenegro
- Departamento de Bioquímica y Biología Molecular-A, Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", Murcia, Spain
| | - María Teresa Moral-Naranjo
- Departamento de Bioquímica y Biología Molecular-A, Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", Murcia, Spain
| | - Francisco J Campoy
- Departamento de Bioquímica y Biología Molecular-A, Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", Murcia, Spain
| | - Encarnación Muñoz-Delgado
- Departamento de Bioquímica y Biología Molecular-A, Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", Murcia, Spain
| | - Cecilio J Vidal
- Departamento de Bioquímica y Biología Molecular-A, Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", Murcia, Spain.
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Bitsikas V, Riento K, Howe JD, Barry NP, Nichols BJ. The role of flotillins in regulating aβ production, investigated using flotillin 1-/-, flotillin 2-/- double knockout mice. PLoS One 2014; 9:e85217. [PMID: 24465508 PMCID: PMC3897416 DOI: 10.1371/journal.pone.0085217] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 11/28/2013] [Indexed: 11/18/2022] Open
Abstract
Flotillin 1 and flotillin 2 associate in the plasma membrane to form microdomains that have roles in cell signaling, regulation of cell-cell contacts, membrane-cytoskeletal interactions, and endocytosis. They are thought to be involved in the trafficking and hence processing of the Amyloid Precursor Protein, APP. In this study we set out to obtain in vivo confirmation of a link between flotillins and cleavage of APP to release amyloidogenic Aβ peptide, and to generate tools that would allow us to ask whether flotillins are functionally redundant. We used a mouse model for Aβ-dependent cerebral amyloidosis, APPPS1 mice, combined with deletion of either flotillin 1 singly, or flotillin 1 and flotillin 2 together. There was a small but significant reduction in Aβ levels, and the abundance of congo-red stained plaques, in brains of 12 week old mice lacking flotillin 1. A similar reduction in Aβ levels was observed in the flotillin 1-/-, flotillin 2-/- double knockouts. We did not observe large effects on the clustering or endocytosis of APP in flotillin 1-/- mouse embryonic fibroblasts. We conclude that flotillins are likely to play some role in APP trafficking or processing, but the relevant cellular mechanisms require more investigation. The availability of flotillin 1-/-, flotillin 2-/- mice, which have no overt phenotypes, will facilitate research into flotillin function in vivo.
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Affiliation(s)
- Vassilis Bitsikas
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, Cambridgeshire, United Kingdom
| | - Kirsi Riento
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, Cambridgeshire, United Kingdom
| | - Jonathan D. Howe
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, Cambridgeshire, United Kingdom
| | - Nicholas P. Barry
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, Cambridgeshire, United Kingdom
| | - Benjamin J. Nichols
- Laboratory of Molecular Biology, Medical Research Council, Cambridge, Cambridgeshire, United Kingdom
- * E-mail:
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Paul LK, Rinne PLH, van der Schoot C. Refurbishing the plasmodesmal chamber: a role for lipid bodies? FRONTIERS IN PLANT SCIENCE 2014; 5:40. [PMID: 24605115 PMCID: PMC3932414 DOI: 10.3389/fpls.2014.00040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 01/28/2014] [Indexed: 05/04/2023]
Abstract
Lipid bodies (LBs) are universal constituents of both animal and plant cells. They are produced by specialized membrane domains at the tubular endoplasmic reticulum (ER), and consist of a core of neutral lipids and a surrounding monolayer of phospholipid with embedded amphipathic proteins. Although originally regarded as simple depots for lipids, they have recently emerged as organelles that interact with other cellular constituents, exchanging lipids, proteins and signaling molecules, and shuttling them between various intracellular destinations, including the plasmamembrane (PM). Recent data showed that in plants LBs can deliver a subset of 1,3-β-glucanases to the plasmodesmal (PD) channel. We hypothesize that this may represent a more general mechanism, which complements the delivery of glycosylphosphatidylinositol (GPI)-anchored proteins to the PD exterior via the secretory pathway. We propose that LBs may contribute to the maintenance of the PD chamber and the delivery of regulatory molecules as well as proteins destined for transport to adjacent cells. In addition, we speculate that LBs deliver their cargo through interaction with membrane domains in the cytofacial side of the PM.
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Affiliation(s)
| | | | - Christiaan van der Schoot
- *Correspondence: Christiaan van der Schoot, Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, P.O. Box 1432, Ås, Norway e-mail:
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Czeredys M, Samluk Ł, Michalec K, Tułodziecka K, Skowronek K, Nałęcz KA. Caveolin-1--a novel interacting partner of organic cation/carnitine transporter (Octn2): effect of protein kinase C on this interaction in rat astrocytes. PLoS One 2013; 8:e82105. [PMID: 24349196 PMCID: PMC3862573 DOI: 10.1371/journal.pone.0082105] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 10/27/2013] [Indexed: 11/28/2022] Open
Abstract
OCTN2 - the Organic Cation Transporter Novel family member 2 (SLC22A5) is known to be a xenobiotic/drug transporter. It transports as well carnitine - a compound necessary for oxidation of fatty acids and mutations of its gene cause primary carnitine deficiency. Octn2 regulation by protein kinase C (PKC) was studied in rat astrocytes - cells in which β-oxidation takes place in the brain. Activation of PKC with phorbol ester stimulated L-carnitine transport and increased cell surface presence of the transporter, although no PKC-specific phosphorylation of Octn2 could be detected. PKC activation resulted in an augmented Octn2 presence in cholesterol/sphingolipid-rich microdomains of plasma membrane (rafts) and increased co-precipitation of Octn2 with raft-proteins, caveolin-1 and flotillin-1. Deletion of potential caveolin-1 binding motifs pointed to amino acids 14–22 and 447–454 as the caveolin-1 binding sites within Octn2 sequence. A direct interaction of Octn2 with caveolin-1 in astrocytes upon PKC activation was detected by proximity ligation assay, while such an interaction was excluded in case of flotillin-1. Functioning of a multi-protein complex regulated by PKC has been postulated in rOctn2 trafficking to the cell surface, a process which could be important both under physiological conditions, when carnitine facilitates fatty acids catabolism and controls free Coenzyme A pool as well as in pathology, when transport of several drugs can induce secondary carnitine deficiency.
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Affiliation(s)
- Magdalena Czeredys
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Łukasz Samluk
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Katarzyna Michalec
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Karolina Tułodziecka
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Krzysztof Skowronek
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Warsaw, Poland
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Katarzyna A. Nałęcz
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
- * E-mail:
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Abstract
UNLABELLED Bacteria organize many membrane-related signaling processes in functional microdomains that are structurally and functionally similar to the lipid rafts of eukaryotic cells. An important structural component of these microdomains is the protein flotillin, which seems to act as a chaperone in recruiting other proteins to lipid rafts to facilitate their interaction. In eukaryotic cells, the occurrence of severe diseases is often observed in combination with an overproduction of flotillin, but a functional link between these two phenomena is yet to be demonstrated. In this work, we used the bacterial model Bacillus subtilis as a tractable system to study the physiological alterations that occur in cells that overproduce flotillin. We discovered that an excess of flotillin altered specific signal transduction pathways that are associated with the membrane microdomains of bacteria. As a consequence of this, we detected significant defects in cell division and cell differentiation. These physiological alterations were in part caused by an unusual stabilization of the raft-associated protease FtsH. This report opens the possibility of using bacteria as a working model to better understand fundamental questions related to the functionality of lipid rafts. IMPORTANCE The identification of signaling platforms in the membrane of bacteria that are functionally and structurally equivalent to eukaryotic lipid rafts reveals a level of sophistication in signal transduction and membrane organization unexpected in bacteria. It opens new and promising venues to address intricate questions related to the functionality of lipid rafts by using bacteria as a more tractable system. This is the first report that uses bacteria as a working model to investigate a fundamental question that was previously raised while studying the role of eukaryotic lipid rafts. It also provides evidence of the critical role of these signaling platforms in orchestrating diverse physiological processes in prokaryotic cells.
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Ren K, Gao C, Zhang J, Wang K, Xu Y, Wang SB, Wang H, Tian C, Shi Q, Dong XP. Flotillin-1 mediates PrPc endocytosis in the cultured cells during Cu²⁺ stimulation through molecular interaction. Mol Neurobiol 2013; 48:631-46. [PMID: 23625312 DOI: 10.1007/s12035-013-8452-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 03/26/2013] [Indexed: 11/29/2022]
Abstract
Flotillins are membrane association proteins consisting of two homologous members, flotillin-1 (Flot-1) and flotillin-2 (Flot-2). They define a clathrin-independent endocytic pathway in mammal cells, which are also distinct from some other endocytosis mechanisms. The implicated cargoes of the flotillin-dependent pathway are mainly some GPI-anchored proteins, such as CD59 and Thy-1, which positionally colocalize with flotillins at the plasma membrane microdomains. To see whether flotillins are involved in the endocytosis of PrP(C), the potential molecular interaction between PrP(C) and flotillins in a neuroblastoma cell line SK-N-SH was analyzed. Co-immunoprecipitation assays did not reveal a detectable complex in the cell lysates of a normal feeding situation. After stimulation of Cu(2+), PrP(C) formed a clear complex with Flot-1, but not with Flot-2. Immunofluorescent assays illustrated that PrP(C) colocalized well with Flot-1, and the complexes of PrP(C)-Flot-1 shifted from the cell membrane to the cytoplasm along with the treatment of Cu(2+). Down-regulating the expression of Flot-1 in SK-N-SH cells by Flot-1-specific RNAi obviously abolished the Cu(2+)-stimulated endocytosis process of PrP(C). Moreover, we also found that in the cell line human embryonic kidney 293 (HEK293) without detectable PrP(C) expression, the distribution of cellular Flot-1 maintained almost unchanged during Cu(2+) treatment. Cu(2+)-induced PrP(C)-Flot-1 molecular interaction and endocytosis in HEK293 cells were obtained when expressing wild-type human PrP (PrP(PG5)), but not in the preparation expressing octarepeat-deleted PrP (PrP(PG0)). Our data here provide direct evidences for the molecular interaction and endocytosis of PrP(C) with Flot-1 in the presence of copper ions, and the octarepeat region of PrP(C) is critical for this process, which strongly indicates that the Flot-1-dependent endocytic pathway seems to mediate the endocytosis process of PrP(C) in the special situation.
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Affiliation(s)
- Ke Ren
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Chang-Bai Rd 155, Beijing, 102206, China
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Sorkina T, Caltagarone J, Sorkin A. Flotillins regulate membrane mobility of the dopamine transporter but are not required for its protein kinase C dependent endocytosis. Traffic 2013; 14:709-24. [PMID: 23418867 DOI: 10.1111/tra.12059] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 02/13/2013] [Accepted: 02/18/2013] [Indexed: 12/15/2022]
Abstract
Flotillins were proposed to mediate clathrin-independent endocytosis, and recently, flotillin-1 was implicated in the protein kinase C (PKC)-triggered endocytosis of the dopamine transporter (DAT). Since endocytosis of DAT was previously shown to be clathrin-mediated, we re-examined the role of clathrin coat proteins and flotillin in DAT endocytosis using DAT tagged with the hemagglutinin epitope (HA) in the extracellular loop and a quantitative HA antibody uptake assay. Depletion of flotillin-1, flotillin-2 or both flotillins together by small interfering RNAs (siRNAs) did not inhibit PKC-dependent internalization and degradation of HA-DAT. In contrast, siRNAs to clathrin heavy chain and μ2 subunit of clathrin adaptor complex AP-2 as well as a dynamin inhibitor Dyngo-4A significantly decreased PKC-dependent endocytosis of HA-DAT. Similarly, endocytosis and degradation of DAT that is not epitope-tagged were highly sensitive to the clathrin siRNAs and dynamin inhibition but were not affected by flotillin knockdown. Very little co-localization of DAT with flotillins was observed in cells ectopically expressing DAT and in cultured mouse dopaminergic neurons. Depletion of flotillins increased diffusion rates of HA-DAT in the plasma membrane, suggesting that flotillin-organized microdomains may regulate the lateral mobility of DAT. We propose that clathrin-mediated endocytosis is the major pathway of PKC-dependent internalization of DAT, and that flotillins may modulate functional association of DAT with plasma membrane rafts rather than mediate DAT endocytosis.
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Affiliation(s)
- Tatiana Sorkina
- Department of Cell Biology, University of Pittsburgh, School of Medicine, Pittsburgh, PA, USA
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41
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Identification, localization, and functional implications of the microdomain-forming stomatin family in the ciliated protozoan Paramecium tetraurelia. EUKARYOTIC CELL 2013; 12:529-44. [PMID: 23376944 DOI: 10.1128/ec.00324-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The SPFH protein superfamily is assumed to occur universally in eukaryotes, but information from protozoa is scarce. In the Paramecium genome, we found only Stomatins, 20 paralogs grouped in 8 families, STO1 to STO8. According to cDNA analysis, all are expressed, and molecular modeling shows the typical SPFH domain structure for all subgroups. For further analysis we used family-specific sequences for fluorescence and immunogold labeling, gene silencing, and functional tests. With all family members tested, we found a patchy localization at/near the cell surface and on vesicles. The Sto1p and Sto4p families are also associated with the contractile vacuole complex. Sto4p also makes puncta on some food vacuoles and is abundant on vesicles recycling from the release site of spent food vacuoles to the site of nascent food vacuole formation. Silencing of the STO1 family reduces mechanosensitivity (ciliary reversal upon touching an obstacle), thus suggesting relevance for positioning of mechanosensitive channels in the plasmalemma. Silencing of STO4 members increases pulsation frequency of the contractile vacuole complex and reduces phagocytotic activity of Paramecium cells. In summary, Sto1p and Sto4p members seem to be involved in positioning specific superficial and intracellular microdomain-based membrane components whose functions may depend on mechanosensation (extracellular stimuli and internal osmotic pressure).
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Thy-1-Interacting Molecules and Cellular Signaling in Cis and Trans. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 305:163-216. [DOI: 10.1016/b978-0-12-407695-2.00004-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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43
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Tian N, Leshchyns'ka I, Welch JH, Diakowski W, Yang H, Schachner M, Sytnyk V. Lipid raft-dependent endocytosis of close homolog of adhesion molecule L1 (CHL1) promotes neuritogenesis. J Biol Chem 2012; 287:44447-63. [PMID: 23144456 DOI: 10.1074/jbc.m112.394973] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
CHL1 plays a dual role by either promoting or inhibiting neuritogenesis. We report here that neuritogenesis-promoting ligand-dependent cell surface clustering of CHL1 induces palmitoylation and lipid raft-dependent endocytosis of CHL1. We identify βII spectrin as a binding partner of CHL1, and we show that partial disruption of the complex between CHL1 and βII spectrin accompanies CHL1 endocytosis. Inhibition of the association of CHL1 with lipid rafts by pharmacological disruption of lipid rafts or by mutation of cysteine 1102 within the intracellular domain of CHL1 reduces endocytosis of CHL1. Endocytosis of CHL1 is also reduced by nifedipine, an inhibitor of the L-type voltage-dependent Ca(2+) channels. CHL1-dependent neurite outgrowth is reduced by inhibitors of lipid raft assembly, inhibitors of voltage-dependent Ca(2+) channels, and overexpression of CHL1 with mutated cysteine Cys-1102. Our results suggest that ligand-induced and lipid raft-dependent regulation of CHL1 adhesion via Ca(2+)-dependent remodeling of the CHL1-βII spectrin complex and CHL1 endocytosis are required for CHL1-dependent neurite outgrowth.
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Affiliation(s)
- Nan Tian
- Zentrum für Molekulare Neurobiologie, Universitätskrankenhaus Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
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44
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Fujita M, Kinoshita T. GPI-anchor remodeling: Potential functions of GPI-anchors in intracellular trafficking and membrane dynamics. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:1050-8. [DOI: 10.1016/j.bbalip.2012.01.004] [Citation(s) in RCA: 164] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Revised: 12/28/2011] [Accepted: 01/04/2012] [Indexed: 01/08/2023]
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45
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On the cellular processing of non-viral nanomedicines for nucleic acid delivery: Mechanisms and methods. J Control Release 2012; 161:566-81. [DOI: 10.1016/j.jconrel.2012.05.020] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 05/11/2012] [Accepted: 05/11/2012] [Indexed: 11/24/2022]
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46
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Aoki T, Suzuki T, Hagiwara H, Kuwahara M, Sasaki S, Takata K, Matsuzaki T. Close association of aquaporin-2 internalization with caveolin-1. Acta Histochem Cytochem 2012; 45:139-46. [PMID: 22685356 PMCID: PMC3365305 DOI: 10.1267/ahc.12003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 02/15/2012] [Indexed: 11/22/2022] Open
Abstract
Aquaporin 2 (AQP2) is a membrane water channel protein that traffics between the intracellular membrane compartment and the plasma membrane in a vasopressin-dependent manner in the renal collecting duct cell to control the amount of water reabsorption. We examined the relation between AQP2 internalization from the plasma membrane and caveolin-1, which is a major protein in membrane microdomain caveolae, in Mardin-Darby canine kidney cells expressing human AQP2 (MDCK-hAQP2 cells). Double-immunofluorescence microscopy showed that AQP2 is colocalized with caveolin-1 in the apical plasma membrane by stimulating the intracellular signaling cascade of vasopressin with forskolin. After washing forskolin, both AQP2 and caveolin-1 were internalized to early endosomes and then separately went back to their individual compartments, which are subapical compartments and the apical membrane, respectively. Double-immunogold electron microscopy in ultrathin cryosections confirmed the colocalization of AQP2 with caveolin-1 at caveolar structures on the apical plasma membrane of forskolin-treated cells and the colocalization within the same intracellular vesicles after washing forskolin. A co-immunoprecipitation experiment showed the close interaction between AQP2 and caveolin-1 in forskolin-treated cells and in cells after washing forskolin. These results suggest that a caveolin-1-dependent and possibly caveolar-dependent pathway is a candidate for AQP2 internalization in MDCK cells.
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Affiliation(s)
- Takeo Aoki
- Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine
| | - Takeshi Suzuki
- Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine
| | - Haruo Hagiwara
- Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine
- Department of Anatomy, Teikyo University School of Medicine
| | | | - Sei Sasaki
- Department of Nephrology, Tokyo Medical and Dental University Graduate School
| | - Kuniaki Takata
- Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine
| | - Toshiyuki Matsuzaki
- Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine
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Otto GP, Nichols BJ. The roles of flotillin microdomains--endocytosis and beyond. J Cell Sci 2012; 124:3933-40. [PMID: 22194304 DOI: 10.1242/jcs.092015] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Flotillins are membrane proteins that form microdomains in the plasma membrane of all mammalian cell types studied to date. They span the evolutionary spectrum, with proteins related to flotillins present in bacteria, fungi, plants and metazoans, which suggests that they perform important, and probably conserved, functions. Flotillins have been implicated in myriad processes that include endocytosis, signal transduction and regulation of the cortical cytoskeleton, yet the molecular mechanisms that underlie flotillin function in these different cases are still poorly understood. In this Commentary, we will provide an introduction to these intriguing proteins, summarise their proposed functions and discuss in greater detail some recent insights into the role of flotillin microdomains in endocytosis that have been provided by several independent studies. Finally, we will focus on the questions that are raised by these new experiments and their implications for future studies.
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Affiliation(s)
- Grant P Otto
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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48
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Takeshita N, Diallinas G, Fischer R. The role of flotillin FloA and stomatin StoA in the maintenance of apical sterol-rich membrane domains and polarity in the filamentous fungus Aspergillus nidulans. Mol Microbiol 2012; 83:1136-52. [PMID: 22329814 DOI: 10.1111/j.1365-2958.2012.07996.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Apical sterol-rich plasma membrane domains (SRDs), which can be viewed using the sterol-binding fluorescent dye filipin, are gaining attention for their important roles in polarized growth of filamentous fungi. The microdomain scaffolding protein flotillin/reggie and related stomatin were thought to be good candidates involved in the formation of SRDs. Here, we show that the flotillin/reggie orthologue FloA tagged with GFP localized as stable dots along the plasma membrane except hyphal tips. Deletion of floA reduced the growth rate, often resulted in irregularly shaped hyphae and impaired SRDs. In contrast, the stomatin orthologue StoA, tagged with GFP, localized at the cortex of young branch tips and at the subapical cortex in long hyphal tips, and was transported bi-directionally along microtubules on endosomes. Deletion of stoA resulted in irregular hyphal morphology and increased branching especially in young hyphae, but did not obviously affect SRDs. Double deletion of floA and stoA enhanced the defects of growth and hyphal morphology. Our data suggest that the plasma membrane of hyphal tips and in subapical regions are distinct and that FloA is involved in membrane compartmentalization and probably indirectly in SRD maintenance.
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Affiliation(s)
- Norio Takeshita
- Karlsruhe Institute of Technology, Institute for Applied Biosciences, Dept. of Microbiology, Hertzstrasse 16, D-76187 Karlsruhe, Germany.
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49
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Flotillin-1 (Reggie-2) contributes to Chlamydia pneumoniae growth and is associated with bacterial inclusion. Infect Immun 2012; 80:1072-8. [PMID: 22215737 DOI: 10.1128/iai.05528-11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Chlamydiae are obligate intracellular pathogens replicating only inside the eukaryotic host. Here, we studied the effect of human flotillin-1 protein on Chlamydia pneumoniae growth in human line (HL) and A549 epithelial cell lines. RNA interference was applied to disrupt flotillin-1-mediated endocytosis. Host-associated bacteria were detected by quantitative PCR, and C. pneumoniae growth was evaluated by inclusion counts. C. pneumoniae attachment to host cells was unaffected, but bacterial intracellular growth was attenuated in the flotillin-1-silenced cells. By using confocal microscopy, we detected flotillin-1 colocalized with the inclusion membrane protein A (IncA) in the C. pneumoniae inclusion membranes. In addition, flotillin-1 was associated with IncA in detergent-resistant membrane microdomains (DRMs) in biochemical fractioning. These results suggest that flotillin-1 localizes to the C. pneumoniae inclusion membrane and plays an important role for intracellular growth of C. pneumoniae.
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50
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Li Y, Martin BR, Cravatt BF, Hofmann SL. DHHC5 protein palmitoylates flotillin-2 and is rapidly degraded on induction of neuronal differentiation in cultured cells. J Biol Chem 2012; 287:523-530. [PMID: 22081607 PMCID: PMC3249106 DOI: 10.1074/jbc.m111.306183] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 11/07/2011] [Indexed: 01/20/2023] Open
Abstract
Post-translational palmitoylation of intracellular proteins is mediated by protein palmitoyltransferases belonging to the DHHC family, which share a common catalytic Asp-His-His-Cys (DHHC) motif. Several members have been implicated in neuronal development, neurotransmission, and synaptic plasticity. We previously observed that mice homozygous for a hypomorphic allele of the ZDHHC5 gene are impaired in context-dependent learning and memory. To identify potentially relevant protein substrates of DHHC5, we performed a quantitative proteomic analysis of stable isotope-labeled neuronal stem cell cultures from forebrains of normal and DHHC5-GT (gene-trapped) mice using the bioorthogonal palmitate analog 17-octadecynoic acid. We identified ∼300 17-octadecynoic acid-modified and hydroxylamine-sensitive proteins, of which a subset was decreased in abundance in DHHC5-GT cells. Palmitoylation and oligomerization of one of these proteins (flotillin-2) was abolished in DHHC5-GT neuronal stem cells. In COS-1 cells, overexpression of DHHC5 markedly stimulated the palmitoylation of flotillin-2, strongly suggesting a direct enzyme-substrate relationship. Serendipitously, we found that down-regulation of DHHC5 was triggered within minutes following growth factor withdrawal from normal neural stem cells, a maneuver that is used to induce neural differentiation in culture. The effect was reversible for up to 4 h, and degradation was partially prevented by inhibitors of ubiquitin-mediated proteolysis. These findings suggest that protein palmitoylation can be regulated through changes in DHHC PAT levels in response to differentiation signals.
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Affiliation(s)
- Yi Li
- Hamon Center for Therapeutic Oncology Research and Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-8593
| | - Brent R Martin
- Skaggs Institute of Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037
| | - Benjamin F Cravatt
- Skaggs Institute of Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037
| | - Sandra L Hofmann
- Hamon Center for Therapeutic Oncology Research and Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-8593.
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