1
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Vassilopoulos S, Montagnac G. Clathrin assemblies at a glance. J Cell Sci 2024; 137:jcs261674. [PMID: 38668719 DOI: 10.1242/jcs.261674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2024] Open
Abstract
Clathrin assembles into honeycomb-like lattices at the plasma membrane but also on internal membranes, such as at the Golgi and tubular endosomes. Clathrin assemblies primarily regulate the intracellular trafficking of different cargoes, but clathrin also has non-endocytic functions in cell adhesion through interactions with specific integrins, contributes to intraluminal vesicle formation by forming flat bilayered coats on endosomes and even assembles on kinetochore k-fibers during mitosis. In this Cell Science at a Glance article and the accompanying poster, we review our current knowledge on the different types of canonical and non-canonical membrane-associated clathrin assemblies in mammalian cells, as observed by thin-section or platinum replica electron microscopy in various cell types, and discuss how the structural plasticity of clathrin contributes to its functional diversity.
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Affiliation(s)
- Stéphane Vassilopoulos
- Sorbonne Université, Inserm U974, Institut de Myologie, Centre de Recherche en Myologie, 75013 Paris, France
| | - Guillaume Montagnac
- Inserm U1279, Gustave Roussy Institute, Université Paris-Saclay, 94800 Villejuif, France
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2
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Cafaro A, Schietroma I, Sernicola L, Belli R, Campagna M, Mancini F, Farcomeni S, Pavone-Cossut MR, Borsetti A, Monini P, Ensoli B. Role of HIV-1 Tat Protein Interactions with Host Receptors in HIV Infection and Pathogenesis. Int J Mol Sci 2024; 25:1704. [PMID: 38338977 PMCID: PMC10855115 DOI: 10.3390/ijms25031704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/19/2024] [Accepted: 01/23/2024] [Indexed: 02/12/2024] Open
Abstract
Each time the virus starts a new round of expression/replication, even under effective antiretroviral therapy (ART), the transactivator of viral transcription Tat is one of the first HIV-1 protein to be produced, as it is strictly required for HIV replication and spreading. At this stage, most of the Tat protein exits infected cells, accumulates in the extracellular matrix and exerts profound effects on both the virus and neighbor cells, mostly of the innate and adaptive immune systems. Through these effects, extracellular Tat contributes to the acquisition of infection, spreading and progression to AIDS in untreated patients, or to non-AIDS co-morbidities in ART-treated individuals, who experience inflammation and immune activation despite virus suppression. Here, we review the role of extracellular Tat in both the virus life cycle and on cells of the innate and adaptive immune system, and we provide epidemiological and experimental evidence of the importance of targeting Tat to block residual HIV expression and replication. Finally, we briefly review vaccine studies showing that a therapeutic Tat vaccine intensifies ART, while its inclusion in a preventative vaccine may blunt escape from neutralizing antibodies and block early events in HIV acquisition.
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Affiliation(s)
- Aurelio Cafaro
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, 00161 Rome, Italy; (I.S.); (L.S.); (R.B.); (M.C.); (F.M.); (S.F.); (M.R.P.-C.); (A.B.); (P.M.)
| | | | | | | | | | | | | | | | | | | | - Barbara Ensoli
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, 00161 Rome, Italy; (I.S.); (L.S.); (R.B.); (M.C.); (F.M.); (S.F.); (M.R.P.-C.); (A.B.); (P.M.)
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3
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Tóth DJ, Tóth JT, Damouni A, Hunyady L, Várnai P. Effect of hormone-induced plasma membrane phosphatidylinositol 4,5-bisphosphate depletion on receptor endocytosis suggests the importance of local regulation in phosphoinositide signaling. Sci Rep 2024; 14:291. [PMID: 38168911 PMCID: PMC10761818 DOI: 10.1038/s41598-023-50732-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 12/24/2023] [Indexed: 01/05/2024] Open
Abstract
Phosphatidylinositol 4,5-bisphosphate (PIP2) has been shown to be critical for the endocytosis of G protein-coupled receptors (GPCRs). We have previously demonstrated that depletion of PIP2 by chemically induced plasma membrane (PM) recruitment of a 5-phosphatase domain prevents the internalization of the β2 adrenergic receptor (β2AR) from the PM to early endosomes. In this study, we tested the effect of hormone-induced PM PIP2 depletion on β2AR internalization using type-1 angiotensin receptor (AT1R) or M3 muscarinic acetylcholine receptor (M3R). We followed the endocytic route of β2ARs in HEK 293T cells using bioluminescence resonance energy transfer between the receptor and endosome marker Rab5. To compare the effect of lipid depletion by different means, we created and tested an AT1R fusion protein that is capable of both recruitment-based and hormone-induced depletion methods. The rate of PM PIP2 depletion was measured using a biosensor based on the PH domain of phospholipase Cδ1. As expected, β2AR internalization was inhibited when PIP2 depletion was evoked by recruiting 5-phosphatase to PM-anchored AT1R. A similar inhibition occurred when wild-type AT1R was activated by adding angiotensin II. However, stimulation of the desensitization/internalization-impaired mutant AT1R (TSTS/4A) caused very little inhibition of β2AR internalization, despite the higher rate of measurable PIP2 depletion. Interestingly, inhibition of PIP2 resynthesis with the selective PI4KA inhibitor GSK-A1 had little effect on the change in PH-domain-measured PM PIP2 levels but did significantly decrease β2AR internalization upon either AT1R or M3R activation, indicating the importance of a locally synthetized phosphoinositide pool in the regulation of this process.
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Affiliation(s)
- Dániel J Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Tűzoltó utca 37-47, 1094, Hungary
- HUN-REN-SU Molecular Physiology Research Group, Hungarian Research Network and Semmelweis University, Budapest, Hungary
| | - József T Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Tűzoltó utca 37-47, 1094, Hungary
- Department of Anaesthesiology and Intensive Therapy, Faculty of Medicine, Semmelweis University, Budapest, Üllői út 78/B, 1082, Hungary
| | - Amir Damouni
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Tűzoltó utca 37-47, 1094, Hungary
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Tűzoltó utca 37-47, 1094, Hungary
- Institute of Enzymology, Centre of Excellence of the Hungarian Academy of Sciences, HUN-REN Research Centre for Natural Sciences, Budapest, Magyar tudósok körútja 2, 1117, Hungary
| | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Tűzoltó utca 37-47, 1094, Hungary.
- HUN-REN-SU Molecular Physiology Research Group, Hungarian Research Network and Semmelweis University, Budapest, Hungary.
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4
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Szewczyk-Roszczenko OK, Roszczenko P, Shmakova A, Finiuk N, Holota S, Lesyk R, Bielawska A, Vassetzky Y, Bielawski K. The Chemical Inhibitors of Endocytosis: From Mechanisms to Potential Clinical Applications. Cells 2023; 12:2312. [PMID: 37759535 PMCID: PMC10527932 DOI: 10.3390/cells12182312] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
Endocytosis is one of the major ways cells communicate with their environment. This process is frequently hijacked by pathogens. Endocytosis also participates in the oncogenic transformation. Here, we review the approaches to inhibit endocytosis, discuss chemical inhibitors of this process, and discuss potential clinical applications of the endocytosis inhibitors.
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Affiliation(s)
| | - Piotr Roszczenko
- Department of Biotechnology, Medical University of Bialystok, Kilinskiego 1, 15-089 Bialystok, Poland; (P.R.); (A.B.)
| | - Anna Shmakova
- CNRS, UMR 9018, Institut Gustave Roussy, Université Paris-Saclay, 94800 Villejuif, France;
| | - Nataliya Finiuk
- Department of Regulation of Cell Proliferation and Apoptosis, Institute of Cell Biology of National Academy of Sciences of Ukraine, Drahomanov 14/16, 79005 Lviv, Ukraine;
| | - Serhii Holota
- Department of Pharmaceutical, Organic and Bioorganic Chemistry, Danylo Halytsky Lviv National Medical University, Pekarska 69, 79010 Lviv, Ukraine; (S.H.); (R.L.)
| | - Roman Lesyk
- Department of Pharmaceutical, Organic and Bioorganic Chemistry, Danylo Halytsky Lviv National Medical University, Pekarska 69, 79010 Lviv, Ukraine; (S.H.); (R.L.)
| | - Anna Bielawska
- Department of Biotechnology, Medical University of Bialystok, Kilinskiego 1, 15-089 Bialystok, Poland; (P.R.); (A.B.)
| | - Yegor Vassetzky
- CNRS, UMR 9018, Institut Gustave Roussy, Université Paris-Saclay, 94800 Villejuif, France;
| | - Krzysztof Bielawski
- Department of Synthesis and Technology of Drugs, Medical University of Bialystok, Kilinskiego 1, 15-089 Bialystok, Poland;
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5
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Rosenhouse-Dantsker A, Gazgalis D, Logothetis DE. PI(4,5)P 2 and Cholesterol: Synthesis, Regulation, and Functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:3-59. [PMID: 36988876 DOI: 10.1007/978-3-031-21547-6_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is the most abundant membrane phosphoinositide and cholesterol is an essential component of the plasma membrane (PM). Both lipids play key roles in a variety of cellular functions including as signaling molecules and major regulators of protein function. This chapter provides an overview of these two important lipids. Starting from a brief description of their structure, synthesis, and regulation, the chapter continues to describe the primary functions and signaling processes in which PI(4,5)P2 and cholesterol are involved. While PI(4,5)P2 and cholesterol can act independently, they often act in concert or affect each other's impact. The chapters in this volume on "Cholesterol and PI(4,5)P2 in Vital Biological Functions: From Coexistence to Crosstalk" focus on the emerging relationship between cholesterol and PI(4,5)P2 in a variety of biological systems and processes. In this chapter, the next section provides examples from the ion channel field demonstrating that PI(4,5)P2 and cholesterol can act via common mechanisms. The chapter ends with a discussion of future directions.
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Affiliation(s)
| | - Dimitris Gazgalis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
| | - Diomedes E Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
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6
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PI(4,5)P2: signaling the plasma membrane. Biochem J 2022; 479:2311-2325. [PMID: 36367756 PMCID: PMC9704524 DOI: 10.1042/bcj20220445] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/19/2022] [Accepted: 10/21/2022] [Indexed: 11/13/2022]
Abstract
In the almost 70 years since the first hints of its existence, the phosphoinositide, phosphatidyl-D-myo-inositol 4,5-bisphosphate has been found to be central in the biological regulation of plasma membrane (PM) function. Here, we provide an overview of the signaling, transport and structural roles the lipid plays at the cell surface in animal cells. These include being substrate for second messenger generation, direct modulation of receptors, control of membrane traffic, regulation of ion channels and transporters, and modulation of the cytoskeleton and cell polarity. We conclude by re-evaluating PI(4,5)P2's designation as a signaling molecule, instead proposing a cofactor role, enabling PM-selective function for many proteins.
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7
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Hansen SD, Lee AA, Duewell BR, Groves JT. Membrane-mediated dimerization potentiates PIP5K lipid kinase activity. eLife 2022; 11:73747. [PMID: 35976097 PMCID: PMC9470164 DOI: 10.7554/elife.73747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 08/16/2022] [Indexed: 11/28/2022] Open
Abstract
The phosphatidylinositol 4-phosphate 5-kinase (PIP5K) family of lipid-modifying enzymes generate the majority of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] lipids found at the plasma membrane in eukaryotic cells. PI(4,5)P2 lipids serve a critical role in regulating receptor activation, ion channel gating, endocytosis, and actin nucleation. Here, we describe how PIP5K activity is regulated by cooperative binding to PI(4,5)P2 lipids and membrane-mediated dimerization of the kinase domain. In contrast to constitutively dimeric phosphatidylinositol 5-phosphate 4-kinase (PIP4K, type II PIPK), solution PIP5K exists in a weak monomer–dimer equilibrium. PIP5K monomers can associate with PI(4,5)P2-containing membranes and dimerize in a protein density-dependent manner. Although dispensable for cooperative PI(4,5)P2 binding, dimerization enhances the catalytic efficiency of PIP5K through a mechanism consistent with allosteric regulation. Additionally, dimerization amplifies stochastic variation in the kinase reaction velocity and strengthens effects such as the recently described stochastic geometry sensing. Overall, the mechanism of PIP5K membrane binding creates a broad dynamic range of lipid kinase activities that are coupled to the density of PI(4,5)P2 and membrane-bound kinase.
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Affiliation(s)
- Scott D Hansen
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, United States
| | - Albert A Lee
- Department of Chemistry, University of California, Berkeley, Berkeley, United States
| | - Benjamin R Duewell
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, United States
| | - Jay T Groves
- Department of Chemistry, University of California, Berkeley, Berkeley, United States
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8
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Ghosh A, Kar PK, Gautam A, Gupta R, Singh R, Chakravarti R, Ravichandiran V, Ghosh Dastidar S, Ghosh D, Roy S. An insight into SARS-CoV-2 structure, pathogenesis, target hunting for drug development and vaccine initiatives. RSC Med Chem 2022; 13:647-675. [PMID: 35814927 PMCID: PMC9215161 DOI: 10.1039/d2md00009a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 01/20/2022] [Indexed: 01/27/2023] Open
Abstract
SARS-CoV-2, the virus responsible for the COVID-19 pandemic, has been confirmed to be a new coronavirus having 79% and 50% similarity with SARS-CoV and MERS-CoV, respectively. For a better understanding of the features of the new virus SARS-CoV-2, we have discussed a possible correlation between some unique features of the genome of SARS-CoV-2 in relation to pathogenesis. We have also reviewed structural druggable viral and host targets for possible clinical application if any, as cases of reinfection and compromised protection have been noticed due to the emergence of new variants with increased infectivity even after vaccination. We have also discussed the types of vaccines that are being developed against SARS-CoV-2. In this review, we have tried to give a brief overview of the fundamental factors of COVID-19 research like basic virology, virus variants and the newly emerging techniques that can be applied to develop advanced treatment strategies for the management of COVID-19 disease.
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Affiliation(s)
- Arijit Ghosh
- Department of Natural Products, National Institute of Pharmaceutical Education and Research Kolkata India
- Department of Chemistry, University of Calcutta Kolkata India
- Netaji Subhas Chandra Bose Cancer Research institute 3081, Nayabad Kolkata-700094 India
| | - Paritosh K Kar
- Foundation on Tropical Diseases & Health Research Development, A Mission on Charitable Health Care Unit Balichak CT, Paschim Medinipur West Bengal 721 124 India
| | - Anupam Gautam
- Institute for Bioinformatics and Medical Informatics, University of Tübingen Sand 14 72076 Tübingen Germany
- International Max Planck Research School "From Molecules to Organisms", Max Planck Institute for Biology Tübingen Max-Planck-Ring 5 72076 Tübingen Germany
| | - Rahul Gupta
- Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology Kolkata India
| | - Rajveer Singh
- Department of Natural Products, National Institute of Pharmaceutical Education and Research Kolkata India
| | - Rudra Chakravarti
- Department of Natural Products, National Institute of Pharmaceutical Education and Research Kolkata India
| | - Velayutham Ravichandiran
- Department of Natural Products, National Institute of Pharmaceutical Education and Research Kolkata India
| | | | - Dipanjan Ghosh
- Department of Natural Products, National Institute of Pharmaceutical Education and Research Kolkata India
| | - Syamal Roy
- Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology Kolkata India
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9
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Dhanda AS, Guttman JA. Localization of host endocytic and actin-associated proteins during Shigella flexneri intracellular motility and intercellular spreading. Anat Rec (Hoboken) 2022; 306:1088-1110. [PMID: 35582740 DOI: 10.1002/ar.24955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/24/2022] [Accepted: 04/27/2022] [Indexed: 11/10/2022]
Abstract
Shigella flexneri (S. flexneri), the causative agent of bacillary dysentery, uses an effector-mediated strategy to hijack host cells and cause disease. To propagate and spread within human tissues, S. flexneri bacteria commandeer the host actin cytoskeleton to generate slender actin-rich comet tails to move intracellularly, and later, plasma membrane actin-based protrusions to move directly between adjacent host cells. To facilitate intercellular bacterial spreading, large micron-sized endocytic-like membrane invaginations form at the periphery of neighboring host cells that come into contact with S. flexneri-containing membrane protrusions. While S. flexneri comet tails and membrane protrusions consist primarily of host actin cytoskeletal proteins, S. flexneri membrane invaginations remain poorly understood with only clathrin and the clathrin adapter epsin-1 localized to the structures. Tangentially, we recently reported that Listeria monocytogenes, another actin-hijacking pathogen, exploits an assortment of caveolar and actin-bundling proteins at their micron-sized membrane invaginations formed during their cell-to-cell movement. Thus, to further characterize the S. flexneri disease process, we set out to catalog the distribution of a variety of actin-associated and caveolar proteins during S. flexneri actin-based motility and cell-to-cell spreading. Here we show that actin-associated proteins found at L. monocytogenes comet tails and membrane protrusions mimic those present at S. flexneri comet tails with the exception of α-actinins 1 and 4, which were shed from S. flexneri membrane protrusions. We also demonstrate that all known host endocytic components found at L. monocytogenes membrane invaginations are also present at those formed during S. flexneri infections.
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Affiliation(s)
- Aaron Singh Dhanda
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Julian Andrew Guttman
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
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10
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Duan D, Hanson M, Holland DO, Johnson ME. Integrating protein copy numbers with interaction networks to quantify stoichiometry in clathrin-mediated endocytosis. Sci Rep 2022; 12:5413. [PMID: 35354856 PMCID: PMC8967901 DOI: 10.1038/s41598-022-09259-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 03/21/2022] [Indexed: 11/25/2022] Open
Abstract
Proteins that drive processes like clathrin-mediated endocytosis (CME) are expressed at copy numbers within a cell and across cell types varying from hundreds (e.g. auxilin) to millions (e.g. clathrin). These variations contain important information about function, but without integration with the interaction network, they cannot capture how supply and demand for each protein depends on binding to shared and distinct partners. Here we construct the interface-resolved network of 82 proteins involved in CME and establish a metric, a stoichiometric balance ratio (SBR), that quantifies whether each protein in the network has an abundance that is sub- or super-stoichiometric dependent on the global competition for binding. We find that highly abundant proteins (like clathrin) are super-stoichiometric, but that not all super-stoichiometric proteins are highly abundant, across three cell populations (HeLa, fibroblast, and neuronal synaptosomes). Most strikingly, within all cells there is significant competition to bind shared sites on clathrin and the central AP-2 adaptor by other adaptor proteins, resulting in most being in excess supply. Our network and systematic analysis, including response to perturbations of network components, show how competition for shared binding sites results in functionally similar proteins having widely varying stoichiometries, due to variations in both abundance and their unique network of binding partners.
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Affiliation(s)
- Daisy Duan
- TC Jenkins Department of Biophysics, Johns Hopkins University, 3400 N Charles St, Baltimore, MD, 21218, USA
| | - Meretta Hanson
- TC Jenkins Department of Biophysics, Johns Hopkins University, 3400 N Charles St, Baltimore, MD, 21218, USA
| | | | - Margaret E Johnson
- TC Jenkins Department of Biophysics, Johns Hopkins University, 3400 N Charles St, Baltimore, MD, 21218, USA.
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11
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Ravi A, Palamiuc L, Emerling BM. Crucial Players for Inter-Organelle Communication: PI5P4Ks and Their Lipid Product PI-4,5-P 2 Come to the Surface. Front Cell Dev Biol 2022; 9:791758. [PMID: 35071233 PMCID: PMC8776650 DOI: 10.3389/fcell.2021.791758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 11/24/2021] [Indexed: 11/23/2022] Open
Abstract
While organelles are individual compartments with specialized functions, it is becoming clear that organellar communication is essential for maintaining cellular homeostasis. This cooperation is carried out by various interactions taking place on the membranes of organelles. The membranes themselves contain a multitude of proteins and lipids that mediate these connections and one such class of molecules facilitating these relations are the phospholipids. There are several phospholipids, but the focus of this perspective is on a minor group called the phosphoinositides and specifically, phosphatidylinositol 4,5-bisphosphate (PI-4,5-P2). This phosphoinositide, on intracellular membranes, is largely generated by the non-canonical Type II PIPKs, namely, Phosphotidylinositol-5-phosphate-4-kinases (PI5P4Ks). These evolutionarily conserved enzymes are emerging as key stress response players in cells. Further, PI5P4Ks have been shown to modulate pathways by regulating organelle crosstalk, revealing roles in preserving metabolic homeostasis. Here we will attempt to summarize the functions of the PI5P4Ks and their product PI-4,5-P2 in facilitating inter-organelle communication and how they impact cellular health as well as their relevance to human diseases.
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Affiliation(s)
- Archna Ravi
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, United States
| | - Lavinia Palamiuc
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, United States
| | - Brooke M Emerling
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, United States
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12
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Arora A, Taskinen JH, Olkkonen VM. Coordination of inter-organelle communication and lipid fluxes by OSBP-related proteins. Prog Lipid Res 2022; 86:101146. [PMID: 34999137 DOI: 10.1016/j.plipres.2022.101146] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/10/2021] [Accepted: 01/03/2022] [Indexed: 12/31/2022]
Abstract
Oxysterol-binding protein (OSBP) and OSBP-related proteins (ORPs) constitute one of the largest families of lipid-binding/transfer proteins (LTPs) in eukaryotes. The current view is that many of them mediate inter-organelle lipid transfer over membrane contact sites (MCS). The transfer occurs in several cases in a 'counter-current' fashion: A lipid such as cholesterol or phosphatidylserine (PS) is transferred against its concentration gradient driven by transport of a phosphoinositide in the opposite direction. In this way ORPs are envisioned to maintain the distinct organelle lipid compositions, with impacts on multiple organelle functions. However, the functions of ORPs extend beyond lipid homeostasis to regulation of processes such as cell survival, proliferation and migration. Important expanding areas of mammalian ORP research include their roles in viral and bacterial infections, cancers, and neuronal function. The yeast OSBP homologue (Osh) proteins execute multifaceted functions in sterol and glycerophospholipid homeostasis, post-Golgi vesicle transport, phosphatidylinositol-4-phosphate, sphingolipid and target of rapamycin (TOR) signalling, and cell cycle control. These observations identify ORPs as lipid transporters and coordinators of signals with an unforeseen variety of cellular processes. Understanding their activities not only enlightens the biology of the living cell but also allows their employment as targets of new therapeutic approaches for disease.
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Affiliation(s)
- Amita Arora
- Minerva Foundation Institute for Medical Research, and Department of Anatomy, Faculty of Medicine, University of Helsinki, Finland
| | - Juuso H Taskinen
- Minerva Foundation Institute for Medical Research, and Department of Anatomy, Faculty of Medicine, University of Helsinki, Finland
| | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, and Department of Anatomy, Faculty of Medicine, University of Helsinki, Finland.
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13
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Abstract
Phosphoinositides are signalling lipids derived from phosphatidylinositol, a ubiquitous phospholipid in the cytoplasmic leaflet of eukaryotic membranes. Initially discovered for their roles in cell signalling, phosphoinositides are now widely recognized as key integrators of membrane dynamics that broadly impact on all aspects of cell physiology and on disease. The past decade has witnessed a vast expansion of our knowledge of phosphoinositide biology. On the endocytic and exocytic routes, phosphoinositides direct the inward and outward flow of membrane as vesicular traffic is coupled to the conversion of phosphoinositides. Moreover, recent findings on the roles of phosphoinositides in autophagy and the endolysosomal system challenge our view of lysosome biology. The non-vesicular exchange of lipids, ions and metabolites at membrane contact sites in between organelles has also been found to depend on phosphoinositides. Here we review our current understanding of how phosphoinositides shape and direct membrane dynamics to impact on cell physiology, and provide an overview of emerging concepts in phosphoinositide regulation.
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14
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Fu Y, Zeno WF, Stachowiak JC, Johnson ME. A continuum membrane model can predict curvature sensing by helix insertion. SOFT MATTER 2021; 17:10649-10663. [PMID: 34792524 PMCID: PMC8877990 DOI: 10.1039/d1sm01333e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Protein domains, such as ENTH (epsin N-terminal homology) and BAR (bin/amphiphysin/rvs), contain amphipathic helices that drive preferential binding to curved membranes. However, predicting how the physical parameters of these domains control this 'curvature sensing' behavior is challenging due to the local membrane deformations generated by the nanoscopic helix on the surface of a large sphere. We here use a deformable continuum model that accounts for the physical properties of the membrane and the helix insertion to predict curvature sensing behavior, with direct validation against multiple experimental datasets. We show that the insertion can be modeled as a local change to the membrane's spontaneous curvature, cins0, producing excellent agreement with the energetics extracted from experiments on ENTH binding to vesicles and cylinders, and of ArfGAP helices to vesicles. For small vesicles with high curvature, the insertion lowers the membrane energy by relieving strain on a membrane that is far from its preferred curvature of zero. For larger vesicles, however, the insertion has the inverse effect, de-stabilizing the membrane by introducing more strain. We formulate here an empirical expression that accurately captures numerically calculated membrane energies as a function of both basic membrane properties (bending modulus κ and radius R) as well as stresses applied by the inserted helix (cins0 and area Ains). We therefore predict how these physical parameters will alter the energetics of helix binding to curved vesicles, which is an essential step in understanding their localization dynamics during membrane remodeling processes.
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Affiliation(s)
- Yiben Fu
- T. C. Jenkins Department of Biophysics, The Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218, USA.
| | - Wade F Zeno
- Mork Family Department of Chemical Engineering and Materials Science, The University of Southern California, Los Angeles, California, 90089, USA
| | - Jeanne C Stachowiak
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Margaret E Johnson
- T. C. Jenkins Department of Biophysics, The Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218, USA.
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15
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Franco ML, García-Carpio I, Comaposada-Baró R, Escribano-Saiz JJ, Chávez-Gutiérrez L, Vilar M. TrkA-mediated endocytosis of p75-CTF prevents cholinergic neuron death upon γ-secretase inhibition. Life Sci Alliance 2021; 4:4/4/e202000844. [PMID: 33536237 PMCID: PMC7898468 DOI: 10.26508/lsa.202000844] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 01/11/2021] [Accepted: 01/11/2021] [Indexed: 12/13/2022] Open
Abstract
The findings shed light into the adverse effects of GSIs observed in the Alzheimer’s field and explain, at least in part, the unexpected worsening in cognition observed in the semagacestat Phase 3 trial. γ-secretase inhibitors (GSI) were developed to reduce the generation of Aβ peptide to find new Alzheimer’s disease treatments. Clinical trials on Alzheimer’s disease patients, however, showed several side effects that worsened the cognitive symptoms of the treated patients. The observed side effects were partially attributed to Notch signaling. However, the effect on other γ-secretase substrates, such as the p75 neurotrophin receptor (p75NTR) has not been studied in detail. p75NTR is highly expressed in the basal forebrain cholinergic neurons (BFCNs) during all life. Here, we show that GSI treatment induces the oligomerization of p75CTF leading to the cell death of BFCNs, and that this event is dependent on TrkA activity. The oligomerization of p75CTF requires an intact cholesterol recognition sequence (CRAC) and the constitutive binding of TRAF6, which activates the JNK and p38 pathways. Remarkably, TrkA rescues from cell death by a mechanism involving the endocytosis of p75CTF. These results suggest that the inhibition of γ-secretase activity in aged patients, where the expression of TrkA in the BFCNs is already reduced, could accelerate cholinergic dysfunction and promote neurodegeneration.
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Affiliation(s)
- María Luisa Franco
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
| | - Irmina García-Carpio
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
| | - Raquel Comaposada-Baró
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
| | - Juan J Escribano-Saiz
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
| | - Lucía Chávez-Gutiérrez
- Vlaams Instituut voor Biotechnologie Katholieke Universiteit (VIB-KU) Leuven Center for Brain and Disease, Leuven, Belgium
| | - Marçal Vilar
- Molecular Basis of Neurodegeneration Unit, Institute of Biomedicine of València (IBV-CSIC), València, Spain
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16
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Wen Y, Vogt VM, Feigenson GW. PI(4,5)P 2 Clustering and Its Impact on Biological Functions. Annu Rev Biochem 2021; 90:681-707. [PMID: 33441034 DOI: 10.1146/annurev-biochem-070920-094827] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Located at the inner leaflet of the plasma membrane (PM), phosphatidyl-inositol 4,5-bisphosphate [PI(4,5)P2] composes only 1-2 mol% of total PM lipids. With its synthesis and turnover both spatially and temporally regulated, PI(4,5)P2 recruits and interacts with hundreds of cellular proteins to support a broad spectrum of cellular functions. Several factors contribute to the versatile and dynamic distribution of PI(4,5)P2 in membranes. Physiological multivalent cations such as Ca2+ and Mg2+ can bridge between PI(4,5)P2 headgroups, forming nanoscopic PI(4,5)P2-cation clusters. The distinct lipid environment surrounding PI(4,5)P2 affects the degree of PI(4,5)P2 clustering. In addition, diverse cellular proteins interacting with PI(4,5)P2 can further regulate PI(4,5)P2 lateral distribution and accessibility. This review summarizes the current understanding of PI(4,5)P2 behavior in both cells and model membranes, with emphasis on both multivalent cation- and protein-induced PI(4,5)P2 clustering. Understanding the nature of spatially separated pools of PI(4,5)P2 is fundamental to cell biology.
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Affiliation(s)
- Yi Wen
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14850, USA; , ,
| | - Volker M Vogt
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14850, USA; , ,
| | - Gerald W Feigenson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14850, USA; , ,
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17
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Review of PIP2 in Cellular Signaling, Functions and Diseases. Int J Mol Sci 2020; 21:ijms21218342. [PMID: 33172190 PMCID: PMC7664428 DOI: 10.3390/ijms21218342] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 12/27/2022] Open
Abstract
Phosphoinositides play a crucial role in regulating many cellular functions, such as actin dynamics, signaling, intracellular trafficking, membrane dynamics, and cell-matrix adhesion. Central to this process is phosphatidylinositol bisphosphate (PIP2). The levels of PIP2 in the membrane are rapidly altered by the activity of phosphoinositide-directed kinases and phosphatases, and it binds to dozens of different intracellular proteins. Despite the vast literature dedicated to understanding the regulation of PIP2 in cells over past 30 years, much remains to be learned about its cellular functions. In this review, we focus on past and recent exciting results on different molecular mechanisms that regulate cellular functions by binding of specific proteins to PIP2 or by stabilizing phosphoinositide pools in different cellular compartments. Moreover, this review summarizes recent findings that implicate dysregulation of PIP2 in many diseases.
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18
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Li S, Ghosh C, Xing Y, Sun Y. Phosphatidylinositol 4,5-bisphosphate in the Control of Membrane Trafficking. Int J Biol Sci 2020; 16:2761-2774. [PMID: 33061794 PMCID: PMC7545710 DOI: 10.7150/ijbs.49665] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/14/2020] [Indexed: 12/15/2022] Open
Abstract
Phosphoinositides are membrane lipids generated by phosphorylation on the inositol head group of phosphatidylinositol. By specifically distributed to distinct subcellular membrane locations, different phosphoinositide species play diverse roles in modulating membrane trafficking. Among the seven known phosphoinositide species, phosphatidylinositol 4,5-bisphosphate (PI4,5P2) is the one species most abundant at the plasma membrane. Thus, the PI4,5P2 function in membrane trafficking is first identified in controlling plasma membrane dynamic-related events including endocytosis and exocytosis. However, recent studies indicate that PI4,5P2 is also critical in many other membrane trafficking events such as endosomal trafficking, hydrolases sorting to lysosomes, autophagy initiation, and autophagic lysosome reformation. These findings suggest that the role of PI4,5P2 in membrane trafficking is far beyond just plasma membrane. This review will provide a concise synopsis of how PI4,5P2 functions in multiple membrane trafficking events. PI4,5P2, the enzymes responsible for PI4,5P2 production at specific subcellular locations, and distinct PI4,5P2 effector proteins compose a regulation network to control the specific membrane trafficking events.
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Affiliation(s)
- Suhua Li
- Philips Institute for Oral Health Research, School of Dentistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Chinmoy Ghosh
- Philips Institute for Oral Health Research, School of Dentistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Yanli Xing
- Department of Otolaryngology, Shanghai Pudong New Area Gongli Hospital, Shanghai, China
| | - Yue Sun
- Philips Institute for Oral Health Research, School of Dentistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
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19
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Katan M, Cockcroft S. Phosphatidylinositol(4,5)bisphosphate: diverse functions at the plasma membrane. Essays Biochem 2020; 64:513-531. [PMID: 32844214 PMCID: PMC7517351 DOI: 10.1042/ebc20200041] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/25/2020] [Accepted: 07/29/2020] [Indexed: 12/20/2022]
Abstract
Phosphatidylinositol(4,5) bisphosphate (PI(4,5)P2) has become a major focus in biochemistry, cell biology and physiology owing to its diverse functions at the plasma membrane. As a result, the functions of PI(4,5)P2 can be explored in two separate and distinct roles - as a substrate for phospholipase C (PLC) and phosphoinositide 3-kinase (PI3K) and as a primary messenger, each having unique properties. Thus PI(4,5)P2 makes contributions in both signal transduction and cellular processes including actin cytoskeleton dynamics, membrane dynamics and ion channel regulation. Signalling through plasma membrane G-protein coupled receptors (GPCRs), receptor tyrosine kinases (RTKs) and immune receptors all use PI(4,5)P2 as a substrate to make second messengers. Activation of PI3K generates PI(3,4,5)P3 (phosphatidylinositol(3,4,5)trisphosphate), a lipid that recruits a plethora of proteins with pleckstrin homology (PH) domains to the plasma membrane to regulate multiple aspects of cellular function. In contrast, PLC activation results in the hydrolysis of PI(4,5)P2 to generate the second messengers, diacylglycerol (DAG), an activator of protein kinase C and inositol(1,4,5)trisphosphate (IP3/I(1,4,5)P3) which facilitates an increase in intracellular Ca2+. Decreases in PI(4,5)P2 by PLC also impact on functions that are dependent on the intact lipid and therefore endocytosis, actin dynamics and ion channel regulation are subject to control. Spatial organisation of PI(4,5)P2 in nanodomains at the membrane allows for these multiple processes to occur concurrently.
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Affiliation(s)
- Matilda Katan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Shamshad Cockcroft
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, 21 University Street, London WC1E 6JJ, U.K
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20
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Redpath GMI, Betzler VM, Rossatti P, Rossy J. Membrane Heterogeneity Controls Cellular Endocytic Trafficking. Front Cell Dev Biol 2020; 8:757. [PMID: 32850860 PMCID: PMC7419583 DOI: 10.3389/fcell.2020.00757] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 07/20/2020] [Indexed: 12/21/2022] Open
Abstract
Endocytic trafficking relies on highly localized events in cell membranes. Endocytosis involves the gathering of protein (cargo/receptor) at distinct plasma membrane locations defined by specific lipid and protein compositions. Simultaneously, the molecular machinery that drives invagination and eventually scission of the endocytic vesicle assembles at the very same place on the inner leaflet of the membrane. It is membrane heterogeneity - the existence of specific lipid and protein domains in localized regions of membranes - that creates the distinct molecular identity required for an endocytic event to occur precisely when and where it is required rather than at some random location within the plasma membrane. Accumulating evidence leads us to believe that the trafficking fate of internalized proteins is sealed following endocytosis, as this distinct membrane identity is preserved through the endocytic pathway, upon fusion of endocytic vesicles with early and sorting endosomes. In fact, just like at the plasma membrane, multiple domains coexist at the surface of these endosomes, regulating local membrane tubulation, fission and sorting to recycling pathways or to the trans-Golgi network via late endosomes. From here, membrane heterogeneity ensures that fusion events between intracellular vesicles and larger compartments are spatially regulated to promote the transport of cargoes to their intracellular destination.
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Affiliation(s)
- Gregory M I Redpath
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,The ANZAC Research Institute, Concord Repatriation General Hospital, Concord, NSW, Australia
| | - Verena M Betzler
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.,Biotechnology Institute Thurgau (BITg) at the University of Konstanz, Kreuzlingen, Switzerland
| | - Pascal Rossatti
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.,Biotechnology Institute Thurgau (BITg) at the University of Konstanz, Kreuzlingen, Switzerland
| | - Jérémie Rossy
- Biotechnology Institute Thurgau (BITg) at the University of Konstanz, Kreuzlingen, Switzerland.,Department of Biology, University of Konstanz, Konstanz, Germany
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21
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Cernikova L, Faso C, Hehl AB. Phosphoinositide-binding proteins mark, shape and functionally modulate highly-diverged endocytic compartments in the parasitic protist Giardia lamblia. PLoS Pathog 2020; 16:e1008317. [PMID: 32092130 PMCID: PMC7058353 DOI: 10.1371/journal.ppat.1008317] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 03/05/2020] [Accepted: 01/14/2020] [Indexed: 12/18/2022] Open
Abstract
Phosphorylated derivatives of phosphatidylinositol (PIPs) are key membrane lipid residues involved in clathrin-mediated endocytosis (CME). CME relies on PIP species PI(4,5)P2 to mark endocytic sites at the plasma membrane (PM) associated to clathrin-coated vesicle (CCV) formation. The highly diverged parasitic protist Giardia lamblia presents disordered and static clathrin assemblies at PM invaginations, contacting specialized endocytic organelles called peripheral vacuoles (PVs). The role for clathrin assemblies in fluid phase uptake and their link to internal membranes via PIP-binding adaptors is unknown. Here we provide evidence for a robust link between clathrin assemblies and fluid-phase uptake in G. lamblia mediated by proteins carrying predicted PX, FYVE and NECAP1 PIP-binding modules. We show that chemical and genetic perturbation of PIP-residue binding and turnover elicits novel uptake and organelle-morphology phenotypes. A combination of co-immunoprecipitation and in silico analysis techniques expands the initial PIP-binding network with addition of new members. Our data indicate that, despite the partial conservation of lipid markers and protein cohorts known to play important roles in dynamic endocytic events in well-characterized model systems, the Giardia lineage presents a strikingly divergent clathrin-centered network. This includes several PIP-binding modules, often associated to domains of currently unknown function that shape and modulate fluid-phase uptake at PVs. In well-characterized model eukaryotes, clathrin-mediated endocytosis is a key process for uptake of extracellular material and is regulated by more than 50 known proteins. A large number of these carry phosphoinositide (PIP)-binding domains and play a central role in the regulation of endocytosis. Here, we report on the detailed functional characterization of PIP-binding proteins in the intestinal parasitic protist Giardia lamblia. We show evidence that proteins carrying specific PIP-binding domains are directly involved in fluid-phase uptake. Furthermore, using co-immunoprecipitation assays, we confirm these proteins’ association to G. lamblia’s clathrin assemblies. In addition, using state-of-the-art imaging strategies, we demonstrate a previously unappreciated level of complexity involving PIPs and their partner proteins in marking and shaping G. lamblia’s unique endocytic compartments. Our data contribute substantially to an updated working model for G. lamblia’s host-parasite interface, demonstrating how uptake in this parasite is directly regulated by a variety of PIP residues and PIP-binding modules, which have been re-routed from conserved pathways, likely as a result of host-parasite co-evolution.
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Affiliation(s)
- Lenka Cernikova
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
| | - Carmen Faso
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
- Institute of Cell Biology, University of Bern, Bern, Switzerland
- * E-mail: (CF); (AH)
| | - Adrian B. Hehl
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
- * E-mail: (CF); (AH)
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22
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Zhukovsky MA, Filograna A, Luini A, Corda D, Valente C. Protein Amphipathic Helix Insertion: A Mechanism to Induce Membrane Fission. Front Cell Dev Biol 2019; 7:291. [PMID: 31921835 PMCID: PMC6914677 DOI: 10.3389/fcell.2019.00291] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 11/06/2019] [Indexed: 12/19/2022] Open
Abstract
One of the fundamental features of biomembranes is the ability to fuse or to separate. These processes called respectively membrane fusion and fission are central in the homeostasis of events such as those related to intracellular membrane traffic. Proteins that contain amphipathic helices (AHs) were suggested to mediate membrane fission via shallow insertion of these helices into the lipid bilayer. Here we analyze the AH-containing proteins that have been identified as essential for membrane fission and categorize them in few subfamilies, including small GTPases, Atg proteins, and proteins containing either the ENTH/ANTH- or the BAR-domain. AH-containing fission-inducing proteins may require cofactors such as additional proteins (e.g., lipid-modifying enzymes), or lipids (e.g., phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], phosphatidic acid [PA], or cardiolipin). Both PA and cardiolipin possess a cone shape and a negative charge (-2) that favor the recruitment of the AHs of fission-inducing proteins. Instead, PtdIns(4,5)P2 is characterized by an high negative charge able to recruit basic residues of the AHs of fission-inducing proteins. Here we propose that the AHs of fission-inducing proteins contain sequence motifs that bind lipid cofactors; accordingly (K/R/H)(K/R/H)xx(K/R/H) is a PtdIns(4,5)P2-binding motif, (K/R)x6(F/Y) is a cardiolipin-binding motif, whereas KxK is a PA-binding motif. Following our analysis, we show that the AHs of many fission-inducing proteins possess five properties: (a) at least three basic residues on the hydrophilic side, (b) ability to oligomerize, (c) optimal (shallow) depth of insertion into the membrane, (d) positive cooperativity in membrane curvature generation, and (e) specific interaction with one of the lipids mentioned above. These lipid cofactors favor correct conformation, oligomeric state and optimal insertion depth. The most abundant lipid in a given organelle possessing high negative charge (more negative than -1) is usually the lipid cofactor in the fission event. Interestingly, naturally occurring mutations have been reported in AH-containing fission-inducing proteins and related to diseases such as centronuclear myopathy (amphiphysin 2), Charcot-Marie-Tooth disease (GDAP1), Parkinson's disease (α-synuclein). These findings add to the interest of the membrane fission process whose complete understanding will be instrumental for the elucidation of the pathogenesis of diseases involving mutations in the protein AHs.
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Affiliation(s)
- Mikhail A. Zhukovsky
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | | | | | - Daniela Corda
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Carmen Valente
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
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23
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Botté A, Potier MC. Focusing on cellular biomarkers: The endo-lysosomal pathway in Down syndrome. PROGRESS IN BRAIN RESEARCH 2019; 251:209-243. [PMID: 32057308 DOI: 10.1016/bs.pbr.2019.10.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Down syndrome (DS) is the most frequent chromosomal disorder. It is caused by the triplication of human chromosome 21, leading to increased dosage of a variety of genes including APP (Amyloid Precursor Protein). Mainly for this reason, individuals with DS are at high risk to develop Alzheimer's disease (AD). Extensive literature identified various morphological and molecular abnormalities in the endo-lysosomal pathway both in DS and AD. Most studies in this field investigated the causative role of APP (Amyloid Precursor Protein) in endo-lysosomal dysfunctions, thus linking phenotypes observed in DS and AD. In DS context, several lines of evidence and emerging hypotheses suggest that other molecular players and pathways may be implicated in these complex phenotypes. In this review, we outline the normal functioning of endosomal trafficking and summarize the research on endo-lysosomal dysfunction in DS in light of AD findings. We emphasize the role of genes of chromosome 21 implicated in endocytosis to explain endosomal abnormalities and set the limitations and perspectives of models used to explore endo-lysosomal dysfunction in DS and find new biomarkers. The review highlights the complexity of endo-lysosomal dysfunction in DS and suggests directions for future research in the field.
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Affiliation(s)
- Alexandra Botté
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR7225, INSERM U1127, Sorbonne Université, Hôpital de la Pitié-Salpêtrière, Paris, France
| | - Marie-Claude Potier
- Institut du Cerveau et de la Moelle épinière (ICM), CNRS UMR7225, INSERM U1127, Sorbonne Université, Hôpital de la Pitié-Salpêtrière, Paris, France.
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24
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Lattner J, Leng W, Knust E, Brankatschk M, Flores-Benitez D. Crumbs organizes the transport machinery by regulating apical levels of PI(4,5)P 2 in Drosophila. eLife 2019; 8:e50900. [PMID: 31697234 PMCID: PMC6881148 DOI: 10.7554/elife.50900] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 10/25/2019] [Indexed: 12/12/2022] Open
Abstract
An efficient vectorial intracellular transport machinery depends on a well-established apico-basal polarity and is a prerequisite for the function of secretory epithelia. Despite extensive knowledge on individual trafficking pathways, little is known about the mechanisms coordinating their temporal and spatial regulation. Here, we report that the polarity protein Crumbs is essential for apical plasma membrane phospholipid-homeostasis and efficient apical secretion. Through recruiting βHeavy-Spectrin and MyosinV to the apical membrane, Crumbs maintains the Rab6-, Rab11- and Rab30-dependent trafficking and regulates the lipid phosphatases Pten and Ocrl. Crumbs knock-down results in increased apical levels of PI(4,5)P2 and formation of a novel, Moesin- and PI(4,5)P2-enriched apical membrane sac containing microvilli-like structures. Our results identify Crumbs as an essential hub required to maintain the organization of the apical membrane and the physiological activity of the larval salivary gland.
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Affiliation(s)
- Johanna Lattner
- Max-Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG)DresdenGermany
| | - Weihua Leng
- Max-Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG)DresdenGermany
| | - Elisabeth Knust
- Max-Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG)DresdenGermany
| | - Marko Brankatschk
- The Biotechnological Center of the TU Dresden (BIOTEC)DresdenGermany
| | - David Flores-Benitez
- Max-Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG)DresdenGermany
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25
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Cafaro A, Tripiciano A, Picconi O, Sgadari C, Moretti S, Buttò S, Monini P, Ensoli B. Anti-Tat Immunity in HIV-1 Infection: Effects of Naturally Occurring and Vaccine-Induced Antibodies Against Tat on the Course of the Disease. Vaccines (Basel) 2019; 7:vaccines7030099. [PMID: 31454973 PMCID: PMC6789840 DOI: 10.3390/vaccines7030099] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/08/2019] [Accepted: 08/15/2019] [Indexed: 02/07/2023] Open
Abstract
HIV-1 Tat is an essential protein in the virus life cycle, which is required for virus gene expression and replication. Most Tat that is produced during infection is released extracellularly and it plays a key role in HIV pathogenesis, including residual disease upon combination antiretroviral therapy (cART). Here, we review epidemiological and experimental evidence showing that antibodies against HIV-1 Tat, infrequently occurring in natural infection, play a protective role against disease progression, and that vaccine targeting Tat can intensify cART. In fact, Tat vaccination of subjects on suppressive cART in Italy and South Africa promoted immune restoration, including CD4+ T-cell increase in low immunological responders, and a reduction of proviral DNA even after six years of cART, when both CD4+ T-cell gain and DNA decay have reached a plateau. Of note, DNA decay was predicted by the neutralization of Tat-mediated entry of Env into dendritic cells by anti-Tat antibodies, which were cross-clade binding and neutralizing. Anti-Tat cellular immunity also contributed to the DNA decay. Based on these data, we propose the Tat therapeutic vaccine as a pathogenesis-driven intervention that effectively intensifies cART and it may lead to a functional cure, providing new perspectives and opportunities also for prevention and virus eradication strategies.
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Affiliation(s)
- Aurelio Cafaro
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Antonella Tripiciano
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Orietta Picconi
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Cecilia Sgadari
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Sonia Moretti
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Stefano Buttò
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Paolo Monini
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Barbara Ensoli
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, Rome 00161, Italy.
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WHAMM initiates autolysosome tubulation by promoting actin polymerization on autolysosomes. Nat Commun 2019; 10:3699. [PMID: 31420534 PMCID: PMC6697732 DOI: 10.1038/s41467-019-11694-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 07/30/2019] [Indexed: 12/22/2022] Open
Abstract
WHAMM, a member of the Wiskott-Aldrich syndrome protein (WASP) family, is an actin nucleation promoting factor (NPF) that also associates with membranes and microtubules. Here we report that WHAMM is required for autophagic lysosome reformation (ALR). WHAMM knockout causes impairment of autolysosome tubulation, which results in accumulation of enlarged autolysosomes during prolonged starvation. Mechanistically, WHAMM is recruited to the autolysosome membrane through its specific interaction with PI(4,5)P2. WHAMM then works as an NPF which promotes assembly of an actin scaffold on the surface of the autolysosome to promote autolysosome tubulation. Our study demonstrates an unexpected role of the actin scaffold in regulating autophagic lysosome reformation. After autophagic cargo degradation, autolysosomes undergo a reformation process to recycle lysosomal membrane components. Here, Dai et al. demonstrate that the actin nucleation promoting factor WHAMM is required for autolysosome reformation by providing an actin scaffold to drive tubulation.
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Abstract
Pattern Recognition Receptors (PRRs) detect evidence of infection and tissue
damage. The activation of these receptors and their downstream signal
transduction pathways initiate a protective immune response. These signaling
pathways are influenced by their spatial context, and precise subcellular
positioning of proteins and protein complexes in these pathways is essential for
effective immune responses in vivo. This organization is not
limited to transmembrane proteins that reside in specific organelles, but also
to proteins that engage membrane lipid head groups for proper positioning. In
this review, we focus on the role of cell membranes and protein–lipid
interactions in innate immune signal transduction and how their mechanisms of
localization regulate the immune response. We will discuss how lipids spatially
regulate the sensing of damage or infection, mediate effector activity, and
serve as messengers of cell death and tissue damage.
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Affiliation(s)
- Katherine C Barnett
- Harvard Medical School and Division of Gastroenterology, Boston Children's Hospital, USA
| | - Jonathan C Kagan
- Harvard Medical School and Division of Gastroenterology, Boston Children's Hospital, USA
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Plasmacytoid Dendritic Cells and Infected Cells Form an Interferogenic Synapse Required for Antiviral Responses. Cell Host Microbe 2019; 25:730-745.e6. [PMID: 31003939 DOI: 10.1016/j.chom.2019.03.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 01/03/2019] [Accepted: 03/08/2019] [Indexed: 12/26/2022]
Abstract
Type I interferon (IFN-I) is critical for antiviral defense, and plasmacytoid dendritic cells (pDCs) are a predominant source of IFN-I during virus infection. pDC-mediated antiviral responses are stimulated upon physical contact with infected cells, during which immunostimulatory viral RNA is transferred to pDCs, leading to IFN production via the nucleic acid sensor TLR7. Using dengue, hepatitis C, and Zika viruses, we demonstrate that the contact site of pDCs with infected cells is a specialized platform we term the interferogenic synapse, which enables viral RNA transfer and antiviral responses. This synapse is formed via αLβ2 integrin-ICAM-1 adhesion complexes and the recruitment of the actin network and endocytic machinery. TLR7 signaling in pDCs promotes interferogenic synapse establishment and provides feed-forward regulation, sustaining pDC contacts with infected cells. This interferogenic synapse may allow pDCs to scan infected cells and locally secrete IFN-I, thereby confining a potentially deleterious response.
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Barnett KC, Coronas-Serna JM, Zhou W, Ernandes MJ, Cao A, Kranzusch PJ, Kagan JC. Phosphoinositide Interactions Position cGAS at the Plasma Membrane to Ensure Efficient Distinction between Self- and Viral DNA. Cell 2019; 176:1432-1446.e11. [PMID: 30827685 PMCID: PMC6697112 DOI: 10.1016/j.cell.2019.01.049] [Citation(s) in RCA: 172] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 12/21/2018] [Accepted: 01/28/2019] [Indexed: 12/25/2022]
Abstract
The presence of DNA in the cytosol of mammalian cells is an unusual event that is often associated with genotoxic stress or viral infection. The enzyme cGAS is a sensor of cytosolic DNA that induces interferon and inflammatory responses that can be protective or pathologic, depending on the context. Along with other cytosolic innate immune receptors, cGAS is thought to diffuse throughout the cytosol in search of its DNA ligand. Herein, we report that cGAS is not a cytosolic protein but rather localizes to the plasma membrane via the actions of an N-terminal phosphoinositide-binding domain. This domain interacts selectively with PI(4,5)P2, and cGAS mutants defective for lipid binding are mislocalized to the cytosolic and nuclear compartments. Mislocalized cGAS induces potent interferon responses to genotoxic stress, but weaker responses to viral infection. These data establish the subcellular positioning of a cytosolic innate immune receptor as a mechanism that governs self-nonself discrimination.
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Affiliation(s)
- Katherine C Barnett
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Julia M Coronas-Serna
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA; Departamento de Microbiología y Parasitología, Facultad de Farmacia. Universidad Complutense de Madrid e Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), Plaza de Ramón y Cajal sn, 28040 Madrid, Spain
| | - Wen Zhou
- Department of Microbiology, Harvard Medical School, Boston, MA, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Michael J Ernandes
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Anh Cao
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Philip J Kranzusch
- Department of Microbiology, Harvard Medical School, Boston, MA, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA; Parker Institute for Cancer Immunotherapy at Dana-Farber Cancer Institute, Boston, MA, USA
| | - Jonathan C Kagan
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
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30
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Strobl SM, Kischka D, Heilmann I, Mouille G, Schneider S. The Tonoplastic Inositol Transporter INT1 From Arabidopsis thaliana Impacts Cell Elongation in a Sucrose-Dependent Way. FRONTIERS IN PLANT SCIENCE 2018; 9:1657. [PMID: 30505313 PMCID: PMC6250803 DOI: 10.3389/fpls.2018.01657] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 10/25/2018] [Indexed: 05/29/2023]
Abstract
The tonoplastic inositol transporter INT1 is the only known transport protein in Arabidopsis that facilitates myo-inositol import from the vacuole into the cytoplasm. Impairment of the release of vacuolar inositol by knockout of INT1 results in a severe inhibition of cell elongation in roots as well as in etiolated hypocotyls. Importantly, a more strongly reduced cell elongation was observed when sucrose was supplied in the growth medium, and this sucrose-dependent effect can be complemented by the addition of exogenous myo-inositol. Comparing int1 mutants (defective in transport) with mutants defective in myo-inositol biosynthesis (mips1 mutants) revealed that the sucrose-induced inhibition in cell elongation does not just depend on inositol depletion. Secondary effects as observed for altered availability of inositol in biosynthesis mutants, as disturbed membrane turnover, alterations in PIN protein localization or alterations in inositol-derived signaling molecules could be ruled out to be responsible for impairing the cell elongation in int1 mutants. Although the molecular mechanism remains to be elucidated, our data implicate a crucial role of INT1-transported myo-inositol in regulating cell elongation in a sucrose-dependent manner and underline recent reports of regulatory roles for sucrose and other carbohydrate intermediates as metabolic semaphores.
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Affiliation(s)
- Sabrina Maria Strobl
- Molecular Plant Physiology, Department of Biology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Dominik Kischka
- Molecular Plant Physiology, Department of Biology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Ingo Heilmann
- Department of Cellular Biochemistry, Institute for Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Grégory Mouille
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris Saclay, Versailles, France
| | - Sabine Schneider
- Molecular Plant Physiology, Department of Biology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
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Abstract
Clathrin-mediated endocytosis (CME) is the major endocytic pathway in mammalian cells. It is responsible for the uptake of transmembrane receptors and transporters, for remodeling plasma membrane composition in response to environmental changes, and for regulating cell surface signaling. CME occurs via the assembly and maturation of clathrin-coated pits that concentrate cargo as they invaginate and pinch off to form clathrin-coated vesicles. In addition to the major coat proteins, clathrin triskelia and adaptor protein complexes, CME requires a myriad of endocytic accessory proteins and phosphatidylinositol lipids. CME is regulated at multiple steps-initiation, cargo selection, maturation, and fission-and is monitored by an endocytic checkpoint that induces disassembly of defective pits. Regulation occurs via posttranslational modifications, allosteric conformational changes, and isoform and splice-variant differences among components of the CME machinery, including the GTPase dynamin. This review summarizes recent findings on the regulation of CME and the evolution of this complex process.
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Affiliation(s)
- Marcel Mettlen
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; , , , ,
| | - Ping-Hung Chen
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; , , , ,
| | - Saipraveen Srinivasan
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; , , , ,
| | - Gaudenz Danuser
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; , , , , .,Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA
| | - Sandra L Schmid
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; , , , ,
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Holland DO, Johnson ME. Stoichiometric balance of protein copy numbers is measurable and functionally significant in a protein-protein interaction network for yeast endocytosis. PLoS Comput Biol 2018. [PMID: 29518071 PMCID: PMC5860782 DOI: 10.1371/journal.pcbi.1006022] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Stoichiometric balance, or dosage balance, implies that proteins that are subunits of obligate complexes (e.g. the ribosome) should have copy numbers expressed to match their stoichiometry in that complex. Establishing balance (or imbalance) is an important tool for inferring subunit function and assembly bottlenecks. We show here that these correlations in protein copy numbers can extend beyond complex subunits to larger protein-protein interactions networks (PPIN) involving a range of reversible binding interactions. We develop a simple method for quantifying balance in any interface-resolved PPINs based on network structure and experimentally observed protein copy numbers. By analyzing such a network for the clathrin-mediated endocytosis (CME) system in yeast, we found that the real protein copy numbers were significantly more balanced in relation to their binding partners compared to randomly sampled sets of yeast copy numbers. The observed balance is not perfect, highlighting both under and overexpressed proteins. We evaluate the potential cost and benefits of imbalance using two criteria. First, a potential cost to imbalance is that ‘leftover’ proteins without remaining functional partners are free to misinteract. We systematically quantify how this misinteraction cost is most dangerous for strong-binding protein interactions and for network topologies observed in biological PPINs. Second, a more direct consequence of imbalance is that the formation of specific functional complexes depends on relative copy numbers. We therefore construct simple kinetic models of two sub-networks in the CME network to assess multi-protein assembly of the ARP2/3 complex and a minimal, nine-protein clathrin-coated vesicle forming module. We find that the observed, imperfectly balanced copy numbers are less effective than balanced copy numbers in producing fast and complete multi-protein assemblies. However, we speculate that strategic imbalance in the vesicle forming module allows cells to tune where endocytosis occurs, providing sensitive control over cargo uptake via clathrin-coated vesicles. Protein copy numbers are often found to be stoichiometrically balanced for subunits of multi-protein complexes. Imbalance is believed to be deleterious because it lowers complex yield (the dosage balance hypothesis) and increases the risk of misinteractions, but imbalance may also provide unexplored functional benefits. We show here that the benefits of stoichiometric balance can extend to larger networks of interacting proteins. We develop a method to quantify to what degree protein networks are balanced, and apply it to two networks. We find that the clathrin-mediated endocytosis system in yeast is statistically balanced, but not perfectly so, and explore the consequences of imbalance in the form of misinteractions and endocytic function. We also show that biological networks are more robust to misinteractions than random networks when balanced, but are more sensitive to misinteractions under imbalance. This suggests evolutionary pressure for proteins to be balanced and that any conserved imbalance should occur for functional reasons. We explore one such reason in the form of bottlenecking the endocytosis process. Our method can be generalized to other networks and used to identify out-of-balance proteins. Our results provide insight into how network design, expression level regulation, and cell fitness are intertwined.
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Affiliation(s)
- David O. Holland
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Margaret E. Johnson
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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33
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Cytosolic proteins can exploit membrane localization to trigger functional assembly. PLoS Comput Biol 2018; 14:e1006031. [PMID: 29505559 PMCID: PMC5854442 DOI: 10.1371/journal.pcbi.1006031] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 03/15/2018] [Accepted: 02/09/2018] [Indexed: 12/03/2022] Open
Abstract
Cell division, endocytosis, and viral budding would not function without the localization and assembly of protein complexes on membranes. What is poorly appreciated, however, is that by localizing to membranes, proteins search in a reduced space that effectively drives up concentration. Here we derive an accurate and practical analytical theory to quantify the significance of this dimensionality reduction in regulating protein assembly on membranes. We define a simple metric, an effective equilibrium constant, that allows for quantitative comparison of protein-protein interactions with and without membrane present. To test the importance of membrane localization for driving protein assembly, we collected the protein-protein and protein-lipid affinities, protein and lipid concentrations, and volume-to-surface-area ratios for 46 interactions between 37 membrane-targeting proteins in human and yeast cells. We find that many of the protein-protein interactions between pairs of proteins involved in clathrin-mediated endocytosis in human and yeast cells can experience enormous increases in effective protein-protein affinity (10–1000 fold) due to membrane localization. Localization of binding partners thus triggers robust protein complexation, suggesting that it can play an important role in controlling the timing of endocytic protein coat formation. Our analysis shows that several other proteins involved in membrane remodeling at various organelles have similar potential to exploit localization. The theory highlights the master role of phosphoinositide lipid concentration, the volume-to-surface-area ratio, and the ratio of 3D to 2D equilibrium constants in triggering (or preventing) constitutive assembly on membranes. Our simple model provides a novel quantitative framework for interpreting or designing in vitro experiments of protein complexation influenced by membrane binding. In a multitude of cellular processes, including cell division and endocytosis, proteins must bind to one another to form large multi-protein complexes. To initiate the formation of these critical multi-protein assemblies at the right time and the right place, the constituent proteins must be present at sufficient concentrations. We show here that membrane localization offers a powerful way of controlling protein concentrations by reducing the dimensionality of the protein’s search space. We present a simple and practical analytical theory that determines the significance of membrane localization for triggering protein-protein interactions. We show that protein binding partners will often form substantially more complexes when both partners can localize to surfaces, and thus localization can regulate the timing of multi-protein assembly. We collect in vitro binding data and cellular concentrations of proteins and lipids involved in pathways including clathrin-mediated endocytosis to demonstrate how cellular proteins could exploit membrane localization to regulate assembly.
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34
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Sarmento MJ, Coutinho A, Fedorov A, Prieto M, Fernandes F. Membrane Order Is a Key Regulator of Divalent Cation-Induced Clustering of PI(3,5)P 2 and PI(4,5)P 2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:12463-12477. [PMID: 28961003 DOI: 10.1021/acs.langmuir.7b00666] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Although the evidence for the presence of functionally important nanosized phosphorylated phosphoinositide (PIP)-rich domains within cellular membranes has accumulated, very limited information is available regarding the structural determinants for compartmentalization of these phospholipids. Here, we used a combination of fluorescence spectroscopy and microscopy techniques to characterize differences in divalent cation-induced clustering of PI(4,5)P2 and PI(3,5)P2. Through these methodologies we were able to detect differences in divalent cation-induced clustering efficiency and cluster size. Ca2+-induced PI(4,5)P2 clusters are shown to be significantly larger than the ones observed for PI(3,5)P2. Clustering of PI(4,5)P2 is also detected at physiological concentrations of Mg2+, suggesting that in cellular membranes, these molecules are constitutively driven to clustering by the high intracellular concentration of divalent cations. Importantly, it is shown that lipid membrane order is a key factor in the regulation of clustering for both PIP isoforms, with a major impact on cluster sizes. Clustered PI(4,5)P2 and PI(3,5)P2 are observed to present considerably higher affinity for more ordered lipid phases than the monomeric species or than PI(4)P, possibly reflecting a more general tendency of clustered lipids for insertion into ordered domains. These results support a model for the description of the lateral organization of PIPs in cellular membranes, where both divalent cation interaction and membrane order are key modulators defining the lateral organization of these lipids.
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Affiliation(s)
- Maria J Sarmento
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon , 1649-004 Lisbon, Portugal
- J. Heyrovský Inst. Physical Chemistry of the A.S.C.R. v.v.i. , 182 23 Prague, Czech Republic
| | - Ana Coutinho
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon , 1649-004 Lisbon, Portugal
- Departamento de Química e Bioquímica, FCUL, University of Lisbon , 1649-004 Lisbon, Portugal
| | - Aleksander Fedorov
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon , 1649-004 Lisbon, Portugal
| | - Manuel Prieto
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon , 1649-004 Lisbon, Portugal
| | - Fábio Fernandes
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon , 1649-004 Lisbon, Portugal
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , Campus da Caparica, 2829-516 Caparica, Portugal
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35
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Delos Santos RC, Bautista S, Lucarelli S, Bone LN, Dayam RM, Abousawan J, Botelho RJ, Antonescu CN. Selective regulation of clathrin-mediated epidermal growth factor receptor signaling and endocytosis by phospholipase C and calcium. Mol Biol Cell 2017; 28:2802-2818. [PMID: 28814502 PMCID: PMC5638584 DOI: 10.1091/mbc.e16-12-0871] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 07/10/2017] [Accepted: 08/09/2017] [Indexed: 12/11/2022] Open
Abstract
Clathrin-mediated endocytosis is a major regulator of cell-surface protein internalization. Clathrin and other proteins assemble into small invaginating structures at the plasma membrane termed clathrin-coated pits (CCPs) that mediate vesicle formation. In addition, epidermal growth factor receptor (EGFR) signaling is regulated by its accumulation within CCPs. Given the diversity of proteins regulated by clathrin-mediated endocytosis, how this process may distinctly regulate specific receptors is a key question. We examined the selective regulation of clathrin-dependent EGFR signaling and endocytosis. We find that perturbations of phospholipase Cγ1 (PLCγ1), Ca2+, or protein kinase C (PKC) impair clathrin-mediated endocytosis of EGFR, the formation of CCPs harboring EGFR, and EGFR signaling. Each of these manipulations was without effect on the clathrin-mediated endocytosis of transferrin receptor (TfR). EGFR and TfR were recruited to largely distinct clathrin structures. In addition to control of initiation and assembly of CCPs, EGF stimulation also elicited a Ca2+- and PKC-dependent reduction in synaptojanin1 recruitment to clathrin structures, indicating broad control of CCP assembly by Ca2+ signals. Hence EGFR elicits PLCγ1-calcium signals to facilitate formation of a subset of CCPs, thus modulating its own signaling and endocytosis. This provides evidence for the versatility of CCPs to control diverse cellular processes.
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Affiliation(s)
- Ralph Christian Delos Santos
- Department of Chemistry and Biology and Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Stephen Bautista
- Department of Chemistry and Biology and Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Stefanie Lucarelli
- Department of Chemistry and Biology and Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Leslie N Bone
- Department of Chemistry and Biology and Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Roya M Dayam
- Department of Chemistry and Biology and Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - John Abousawan
- Department of Chemistry and Biology and Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Roberto J Botelho
- Department of Chemistry and Biology and Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Costin N Antonescu
- Department of Chemistry and Biology and Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada .,Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON M5B 1W8, Canada
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36
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Lee SA, Suh Y, Lee S, Jeong J, Kim SJ, Kim SJ, Park SK. Functional expression of dopamine D2 receptor is regulated by tetraspanin 7-mediated postendocytic trafficking. FASEB J 2017; 31:2301-2313. [PMID: 28223337 DOI: 10.1096/fj.201600755rr] [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: 06/17/2016] [Accepted: 01/30/2017] [Indexed: 11/11/2022]
Abstract
The dopaminergic system plays an essential role in various functions of the brain, including locomotion, memory, and reward, and the deregulation of dopaminergic signaling as a result of altered functionality of dopamine D2 receptor (DRD2) is implicated in multiple neurologic and psychiatric disorders. Tetraspanin-7 (TSPAN7) is expressed to variable degrees in different tissues, with the highest level in the brain, and multiple mutations in TSPAN7 have been implicated in intellectual disability. Here, we tested the hypothesis that TSPAN7 may be a binding partner of DRD2 that is involved in the regulation of its functional activity. Our results showed that TSPAN7 was associated with DRD2 and reduced its surface expression by enhancing DRD2 internalization. Immunocytochemical analysis revealed that TSPAN7 that resides in the plasma membrane and early and late endosomes promoted internalization of DRD2 and its localization to endosomal compartments of the endocytic pathway. Furthermore, we observed that TSPAN7 deficiency increased surface localization of DRD2 concurrent with the decrease of its endocytosis, regardless of dopamine treatment. Finally, TSPAN7 negatively affects DRD2-mediated signaling. These results disclosed a previously uncharacterized role of TSPAN7 in the regulation of the expression and functional activity of DRD2 by postendocytic trafficking.-Lee, S.-A., Suh, Y., Lee, S., Jeong, J., Kim, S. J., Kim, S. J., Park, S. K. Functional expression of dopamine D2 receptor is regulated by tetraspanin 7-mediated postendocytic trafficking.
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Affiliation(s)
- Seol-Ae Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Yeongjun Suh
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Saebom Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Jaehoon Jeong
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Soo Jeong Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - So Jung Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Sang Ki Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
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37
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Shiozaki Y, Segawa H, Ohnishi S, Ohi A, Ito M, Kaneko I, Kido S, Tatsumi S, Miyamoto KI. Relationship between sodium-dependent phosphate transporter (NaPi-IIc) function and cellular vacuole formation in opossum kidney cells. THE JOURNAL OF MEDICAL INVESTIGATION 2017; 62:209-18. [PMID: 26399350 DOI: 10.2152/jmi.62.209] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
NaPi-IIc/SLC34A3 is a sodium-dependent inorganic phosphate (Pi) transporter in the renal proximal tubules and its mutations cause hereditary hypophosphatemic rickets with hypercalciuria (HHRH). In the present study, we created a specific antibody for opossum SLC34A3, NaPi-IIc (oNaPi-IIc), and analyzed its localization and regulation in opossum kidney cells (a tissue culture model of proximal tubular cells). Immunoreactive oNaPi-IIc protein levels increased during the proliferative phase and decreased during differentiation. Moreover, stimulating cell growth upregulated oNaPi-IIc protein levels, whereas suppressing cell proliferation downregulated oNaPi-IIc protein levels. Immunocytochemistry revealed that endogenous and exogenous oNaPi-IIc proteins localized at the protrusion of the plasma membrane, which is a phosphatidylinositol 4,5-bisphosphate (PIP2) rich-membrane, and at the intracellular vacuolar membrane. Exogenous NaPi-IIc also induced cellular vacuoles and localized in the plasma membrane. The ability to form vacuoles is specific to electroneutral NaPi-IIc, and not electrogenic NaPi-IIa or NaPi-IIb. In addition, mutations of NaPi-IIc (S138F and R468W) in HHRH did not cause cellular PIP2-rich vacuoles. In conclusion, our data anticipate that NaPi-IIc may regulate PIP2 production at the plasma membrane and cellular vesicle formation.
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Affiliation(s)
- Yuji Shiozaki
- Department of Molecular Nutrition, University of Tokushima Graduate School
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38
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Bone LN, Dayam RM, Lee M, Kono N, Fairn GD, Arai H, Botelho RJ, Antonescu CN. The acyltransferase LYCAT controls specific phosphoinositides and related membrane traffic. Mol Biol Cell 2016; 28:161-172. [PMID: 28035047 PMCID: PMC5221620 DOI: 10.1091/mbc.e16-09-0668] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/24/2016] [Accepted: 11/01/2016] [Indexed: 11/18/2022] Open
Abstract
Phosphoinositides (PIPs) control membrane traffic. PIPs have an acyl profile unique among phospholipids. The acyltransferase LYCAT localizes to phosphatidylinositol synthase vesicles, selectively regulates levels and locale of PIPs, and controls related membrane traffic, indicating that dynamic acyl remodeling selectively controls certain PIPs. Phosphoinositides (PIPs) are key regulators of membrane traffic and signaling. The interconversion of PIPs by lipid kinases and phosphatases regulates their functionality. Phosphatidylinositol (PI) and PIPs have a unique enrichment of 1-stearoyl-2-arachidonyl acyl species; however, the regulation and function of this specific acyl profile remains poorly understood. We examined the role of the PI acyltransferase LYCAT in control of PIPs and PIP-dependent membrane traffic. LYCAT silencing selectively perturbed the levels and localization of phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] and phosphatidylinositol-3-phosphate and the membrane traffic dependent on these specific PIPs but was without effect on phosphatidylinositol-4-phosphate or biosynthetic membrane traffic. The acyl profile of PI(4,5)P2 was selectively altered in LYCAT-deficient cells, whereas LYCAT localized with phosphatidylinositol synthase. We propose that LYCAT remodels the acyl chains of PI, which is then channeled into PI(4,5)P2. Our observations suggest that the PIP acyl chain profile may exert broad control of cell physiology.
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Affiliation(s)
- Leslie N Bone
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Roya M Dayam
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Minhyoung Lee
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Nozomu Kono
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
| | - Gregory D Fairn
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.,Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON M5B 1W8, Canada
| | - Hiroyuki Arai
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.,Japan Agency for Medical Research and Development-Core Research for Evolutionary Science and Technology, Tokyo 113-0033, Japan
| | - Roberto J Botelho
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada .,Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Costin N Antonescu
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada .,Graduate Program in Molecular Science, Ryerson University, Toronto, ON M5B 2K3, Canada.,Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON M5B 1W8, Canada
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Endocytosis of Wingless via a dynamin-independent pathway is necessary for signaling in Drosophila wing discs. Proc Natl Acad Sci U S A 2016; 113:E6993-E7002. [PMID: 27791132 DOI: 10.1073/pnas.1610565113] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Endocytosis of ligand-receptor complexes regulates signal transduction during development. In particular, clathrin and dynamin-dependent endocytosis has been well studied in the context of patterning of the Drosophila wing disc, wherein apically secreted Wingless (Wg) encounters its receptor, DFrizzled2 (DFz2), resulting in a distinctive dorso-ventral pattern of signaling outputs. Here, we directly track the endocytosis of Wg and DFz2 in the wing disc and demonstrate that Wg is endocytosed from the apical surface devoid of DFz2 via a dynamin-independent CLIC/GEEC pathway, regulated by Arf1, Garz, and class I PI3K. Subsequently, Wg containing CLIC/GEEC endosomes fuse with DFz2-containing vesicles derived from the clathrin and dynamin-dependent endocytic pathway, which results in a low pH-dependent transfer of Wg to DFz2 within the merged and acidified endosome to initiate Wg signaling. The employment of two distinct endocytic pathways exemplifies a mechanism wherein cells in tissues leverage multiple endocytic pathways to spatially regulate signaling.
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40
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Kolay S, Basu U, Raghu P. Control of diverse subcellular processes by a single multi-functional lipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. Biochem J 2016; 473:1681-92. [PMID: 27288030 PMCID: PMC6609453 DOI: 10.1042/bcj20160069] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 03/07/2016] [Indexed: 12/16/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is a multi-functional lipid that regulates several essential subcellular processes in eukaryotic cells. In addition to its well-established function as a substrate for receptor-activated signalling at the plasma membrane (PM), it is now recognized that distinct PI(4,5)P2 pools are present at other organelle membranes. However, a long-standing question that remains unresolved is the mechanism by which a single lipid species, with an invariant functional head group, delivers numerous functions without loss of fidelity. In the present review, we summarize studies that have examined the molecular processes that shape the repertoire of PI(4,5)P2 pools in diverse eukaryotes. Collectively, these studies indicate a conserved role for lipid kinase isoforms in generating functionally distinct pools of PI(4,5)P2 in diverse metazoan species. The sophistication underlying the regulation of multiple functions by PI(4,5)P2 is also shaped by mechanisms that regulate its availability to enzymes involved in its metabolism as well as molecular processes that control its diffusion at nanoscales in the PM. Collectively, these mechanisms ensure the specificity of PI(4,5)P2 mediated signalling at eukaryotic membranes.
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Affiliation(s)
- Sourav Kolay
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bangalore 560065, India Manipal University, Madhav Nagar, Manipal 576104, Karnataka, India
| | - Urbashi Basu
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bangalore 560065, India
| | - Padinjat Raghu
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bangalore 560065, India
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41
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Organelle remodeling at membrane contact sites. J Struct Biol 2016; 196:15-19. [PMID: 27181417 DOI: 10.1016/j.jsb.2016.05.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 01/17/2023]
Abstract
Cellular organelles must execute sophisticated biological processes to persist, and often communicate with one another to exchange metabolites and information. Recent studies suggest inter-organelle membrane contact sites (MCSs) are hubs for this cellular cross-talk. MCSs also govern membrane remodeling, thus controlling aspects of organelle shape, identity, and function. Here, we summarize three emerging phenomena that MCSs appear to govern: 1) organelle identity via the non-vesicular exchange of lipids, 2) mitochondrial shape and division, and 3) endosomal migration in response to sterol trafficking. We also discuss the role for ER-endolysosomal contact sites in cholesterol metabolism, and the potential biomedical importance this holds. Indeed, the emerging field inter-organellar cross-talk promises substantial advances in the fields of lipid metabolism and cell signaling.
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42
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Membrane Lipids in Presynaptic Function and Disease. Neuron 2016; 90:11-25. [DOI: 10.1016/j.neuron.2016.02.033] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 01/28/2016] [Accepted: 02/18/2016] [Indexed: 12/20/2022]
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Manna PT, Field MC. Phosphoinositides, kinases and adaptors coordinating endocytosis in Trypanosoma brucei. Commun Integr Biol 2016; 8:e1082691. [PMID: 27064836 PMCID: PMC4802737 DOI: 10.1080/19420889.2015.1082691] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 08/08/2015] [Indexed: 01/01/2023] Open
Abstract
In the kinetoplastid parasite Trypanosoma brucei clathrin-mediated endocytosis is essential for survival and aids immune evasion in the mammalian host. The formation of endocytic clathrin coated vesicles in T. brucei is via a unique mechanism owing to an evolutionarily recent loss of the adaptor protein (AP)2 complex, a central hub in endocytic vesicle assembly. Despite this loss, recent studies examining endocytic clathrin coat assembly have highlighted a high degree of conservation between trypanosomes and their mammalian hosts. In particular phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and its putative effectors, TbCALM and TbEpsinR, are central to clathrin-mediated endocytosis in the trypanosome, just as they are in animal cells. In addition to providing insights into the cell biology of T. brucei, these studies also suggest an ancient, possibly pan-eukaryotic connection between PtdIns(4,5)P2 and endocytosis.
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Affiliation(s)
- Paul T Manna
- Cambridge Institute for Medical Research; University of Cambridge ; Cambridge, UK
| | - Mark C Field
- Division of Biological Chemistry and Drug Discovery; University of Dundee ; Dundee, UK
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44
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Matsuoka H, Inoue M. Src mediates endocytosis of TWIK-related acid-sensitive K+ 1 channels in PC12 cells in response to nerve growth factor. Am J Physiol Cell Physiol 2015; 309:C251-63. [DOI: 10.1152/ajpcell.00354.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 06/10/2015] [Indexed: 01/17/2023]
Abstract
TWIK-related acid-sensitive K+ (TASK) channels produce background K+ currents. We elucidated that TASK1 channels in rat adrenal medullary cells and PC12 cells are internalized in a clathrin-dependent manner in response to nerve growth factor (NGF). Here, the molecular mechanism for this internalization in PC12 cells was explored. The combination of enzyme inhibitors with tropomyosin receptor kinase A mutants revealed that the internalization was mediated by both phospholipase C and phosphatidylinositol 3-kinase pathways that converge on protein kinase C with the consequent activation of Src, a nonreceptor tyrosine kinase. The NGF-induced endocytosis of TASK1 channels did not occur in the presence of the Src inhibitor or with the expression of a kinase-dead Src mutant. Additionally, NGF induced a transient colocalization of Src with the TASK1 channel, but not the TASK1 mutant, in which tyrosine at 370 was replaced with phenylalanine. This TASK1 mutant showed no increase in tyrosine phosphorylation and markedly diminished internalization in response to NGF. We concluded that NGF induces endocytosis of TASK1 channels via tyrosine phosphorylation in its carboxyl terminus.
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Affiliation(s)
- Hidetada Matsuoka
- Department of Cell and Systems Physiology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Japan
| | - Masumi Inoue
- Department of Cell and Systems Physiology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Japan
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45
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Posor Y, Eichhorn-Grünig M, Haucke V. Phosphoinositides in endocytosis. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:794-804. [DOI: 10.1016/j.bbalip.2014.09.014] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 08/21/2014] [Accepted: 09/17/2014] [Indexed: 02/04/2023]
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46
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Schifferer M, Feng S, Stein F, Tischer C, Schultz C. Reversible chemical dimerizer-induced recovery of PIP2 levels moves clathrin to the plasma membrane. Bioorg Med Chem 2015; 23:2862-7. [PMID: 25840797 DOI: 10.1016/j.bmc.2015.03.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/16/2015] [Accepted: 03/18/2015] [Indexed: 12/24/2022]
Abstract
Chemical dimerizers are powerful non-invasive tools for bringing molecules together inside intact cells. We recently introduced a rapidly reversible chemical dimerizer system which enables transient translocation of enzymes to and from the plasma membrane (PM). Here we have applied this system to transiently activate phosphatidylinositol 4,5-bisphosphate (PIP2) breakdown at the PM via translocation of phosphoinositide 5-phosphatase (5Ptase). We found that the PIP2 sensor phospholipase C-δ PH domain (PLCδ-PH) is released from the PM upon addition of the reversible chemical dimerizer rCD1. By outcompeting rCD1, rapid release of the 5Ptase from the PM is followed by PIP2 recovery. This permits the observation of the PIP2-dependent clathrin assembly at the PM.
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Affiliation(s)
- Martina Schifferer
- European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Suihan Feng
- European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Frank Stein
- European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Christian Tischer
- European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany.
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47
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Vanhauwaert R, Verstreken P. Flies with Parkinson's disease. Exp Neurol 2015; 274:42-51. [PMID: 25708988 DOI: 10.1016/j.expneurol.2015.02.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Accepted: 02/11/2015] [Indexed: 12/21/2022]
Abstract
Parkinson's disease is an incurable neurodegenerative disease. Most cases of the disease are of sporadic origin, but about 10% of the cases are familial. The genes thus far identified in Parkinson's disease are well conserved. Drosophila is ideally suited to study the molecular neuronal cell biology of these genes and the pathogenic mutations in Parkinson's disease. Flies reproduce quickly, and their elaborate genetic tools in combination with their small size allow researchers to analyze identified cells and neurons in large numbers of animals. Furthermore, fruit flies recapitulate many of the cellular and molecular defects also seen in patients, and these defects often result in clear locomotor and behavioral phenotypes, facilitating genetic modifier screens. Hence, Drosophila has played a prominent role in Parkinson's disease research and has provided invaluable insight into the molecular mechanisms of this disease.
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Affiliation(s)
- Roeland Vanhauwaert
- VIB Center for the Biology of Disease, KU Leuven, Herestraat 49,3000 Leuven, Belgium; Laboratory of Neuronal Communication, Leuven Institute for Neurodegenerative Disease (LIND), Center for Human Genetics, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Patrik Verstreken
- VIB Center for the Biology of Disease, KU Leuven, Herestraat 49,3000 Leuven, Belgium; Laboratory of Neuronal Communication, Leuven Institute for Neurodegenerative Disease (LIND), Center for Human Genetics, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.
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48
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Merrifield CJ, Kaksonen M. Endocytic accessory factors and regulation of clathrin-mediated endocytosis. Cold Spring Harb Perspect Biol 2014; 6:a016733. [PMID: 25280766 DOI: 10.1101/cshperspect.a016733] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Up to 60 different proteins are recruited to the site of clathrin-mediated endocytosis in an ordered sequence. These accessory proteins have roles during all the different stages of clathrin-mediated endocytosis. First, they participate in the initiation of the endocytic event, thereby determining when and where endocytic vesicles are made; later they are involved in the maturation of the clathrin coat, recruitment of specific cargo molecules, bending of the membrane, and finally in scission and uncoating of the nascent vesicle. In addition, many of the accessory components are involved in regulating and coupling the actin cytoskeleton to the endocytic membrane. We will discuss the different accessory components and their various roles. Most of the data comes from studies performed with cultured mammalian cells or yeast cells. The process of endocytosis is well conserved between these different organisms, but there are also many interesting differences that may shed light on the mechanistic principles of endocytosis.
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Affiliation(s)
- Christien J Merrifield
- Laboratoire d'Enzymologie et Biochimie Structurales, Centre National de la Recherche Scientifique UPR3082, 91198 Gif-sur-Yvette, France
| | - Marko Kaksonen
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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49
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Monteiro ME, Sarmento MJ, Fernandes F. Role of calcium in membrane interactions by PI(4,5)P₂-binding proteins. Biochem Soc Trans 2014; 42:1441-6. [PMID: 25233429 DOI: 10.1042/bst20140149] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Ca²⁺ and phosphatidylinositol 4,5-bisphosphate [PI(4,5)P₂] are key agents in membrane-associated signalling events. Their temporal and spatial regulation is crucial for activation or recruitment of proteins in the plasma membrane. In fact, the interaction of several signalling proteins with PI(4,5)P₂ has been shown to be tightly regulated and dependent on the presence of Ca²⁺, with co-operative binding in some cases. In these proteins, PI(4,5)P₂ and Ca²⁺ binding typically occurs at different binding sites. In addition, several PI(4,5)P₂-binding proteins are known targets of calmodulin (CaM), which, depending on the presence of calcium, can compete with PI(4,5)P₂ for protein interaction, translating Ca²⁺ transient microdomains into variations of PI(4,5)P₂ lateral organization in time and space. The present review highlights different examples of calcium-dependent PI(4,5)P₂-binding proteins and discusses the possible impact of this dual regulation on fine-tuning of protein activity by triggering target membrane binding in the presence of subtle changes in the levels of calcium or PI(4,5)P₂.
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Affiliation(s)
- Marina E Monteiro
- *Centro de Química-Física Molecular and IN-Instituto de Nanociência e Nanotecnologia, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Maria J Sarmento
- *Centro de Química-Física Molecular and IN-Instituto de Nanociência e Nanotecnologia, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Fábio Fernandes
- *Centro de Química-Física Molecular and IN-Instituto de Nanociência e Nanotecnologia, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
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50
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Medina MW, Bauzon F, Naidoo D, Theusch E, Stevens K, Schilde J, Schubert C, Mangravite LM, Rudel LL, Temel RE, Runz H, Krauss RM. Transmembrane protein 55B is a novel regulator of cellular cholesterol metabolism. Arterioscler Thromb Vasc Biol 2014; 34:1917-23. [PMID: 25035345 DOI: 10.1161/atvbaha.113.302806] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Interindividual variation in pathways affecting cellular cholesterol metabolism can influence levels of plasma cholesterol, a well-established risk factor for cardiovascular disease. Inherent variation among immortalized lymphoblastoid cell lines from different donors can be leveraged to discover novel genes that modulate cellular cholesterol metabolism. The objective of this study was to identify novel genes that regulate cholesterol metabolism by testing for evidence of correlated gene expression with cellular levels of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) mRNA, a marker for cellular cholesterol homeostasis, in a large panel of lymphoblastoid cell lines. APPROACH AND RESULTS Expression array profiling was performed on 480 lymphoblastoid cell lines established from participants of the Cholesterol and Pharmacogenetics (CAP) statin clinical trial, and transcripts were tested for evidence of correlated expression with HMGCR as a marker of intracellular cholesterol homeostasis. Of these, transmembrane protein 55b (TMEM55B) showed the strongest correlation (r=0.29; P=4.0E-08) of all genes not previously implicated in cholesterol metabolism and was found to be sterol regulated. TMEM55B knockdown in human hepatoma cell lines promoted the decay rate of the low-density lipoprotein receptor, reduced cell surface low-density lipoprotein receptor protein, impaired low-density lipoprotein uptake, and reduced intracellular cholesterol. CONCLUSIONS Here, we report identification of TMEM55B as a novel regulator of cellular cholesterol metabolism through the combination of gene expression profiling and functional studies. The findings highlight the value of an integrated genomic approach for identifying genes that influence cholesterol homeostasis.
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Affiliation(s)
- Marisa W Medina
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.).
| | - Frederick Bauzon
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Devesh Naidoo
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Elizabeth Theusch
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Kristen Stevens
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Jessica Schilde
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Christian Schubert
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Lara M Mangravite
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Lawrence L Rudel
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Ryan E Temel
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Heiko Runz
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
| | - Ronald M Krauss
- From the Children's Hospital Oakland Research Institute, CA (M.W.M., F.B., D.N., E.T., K.S., R.M.K.); Institute of Human Genetics, University of Heidelberg, Heidelberg, Germany (J.S., H.R.); Sage Bionetworks, Seattle, WA (L.M.M.); Section on Lipid Sciences, Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC (L.L.R., R.E.T.); and Molecular Medicine Partnership Unit (MMPU), Heidelberg, Germany (C.S., H.R.)
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