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Lolicato F, Nickel W, Haucke V, Ebner M. Phosphoinositide switches in cell physiology - From molecular mechanisms to disease. J Biol Chem 2024; 300:105757. [PMID: 38364889 PMCID: PMC10944118 DOI: 10.1016/j.jbc.2024.105757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 02/02/2024] [Accepted: 02/08/2024] [Indexed: 02/18/2024] Open
Abstract
Phosphoinositides are amphipathic lipid molecules derived from phosphatidylinositol that represent low abundance components of biological membranes. Rather than serving as mere structural elements of lipid bilayers, they represent molecular switches for a broad range of biological processes, including cell signaling, membrane dynamics and remodeling, and many other functions. Here, we focus on the molecular mechanisms that turn phosphoinositides into molecular switches and how the dysregulation of these processes can lead to disease.
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Affiliation(s)
- Fabio Lolicato
- Heidelberg University Biochemistry Center, Heidelberg, Germany; Department of Physics, University of Helsinki, Helsinki, Finland.
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany; Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Michael Ebner
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.
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2
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Bolz S, Kaempf N, Puchkov D, Krauss M, Russo G, Soykan T, Schmied C, Lehmann M, Müller R, Schultz C, Perrais D, Maritzen T, Haucke V. Synaptotagmin 1-triggered lipid signaling facilitates coupling of exo- and endocytosis. Neuron 2023; 111:3765-3774.e7. [PMID: 37738980 DOI: 10.1016/j.neuron.2023.08.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 06/16/2023] [Accepted: 08/16/2023] [Indexed: 09/24/2023]
Abstract
Exocytosis and endocytosis are essential physiological processes and are of prime importance for brain function. Neurotransmission depends on the Ca2+-triggered exocytosis of synaptic vesicles (SVs). In neurons, exocytosis is spatiotemporally coupled to the retrieval of an equal amount of membrane and SV proteins by compensatory endocytosis. How exocytosis and endocytosis are balanced to maintain presynaptic membrane homeostasis and, thereby, sustain brain function is essentially unknown. We combine mouse genetics with optical imaging to show that the SV calcium sensor Synaptotagmin 1 couples exocytic SV fusion to the endocytic retrieval of SV membranes by promoting the local activity-dependent formation of the signaling lipid phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) at presynaptic sites. Interference with these mechanisms impairs PI(4,5)P2-triggered SV membrane retrieval but not exocytic SV fusion. Our findings demonstrate that the coupling of SV exocytosis and endocytosis involves local Synaptotagmin 1-induced lipid signaling to maintain presynaptic membrane homeostasis in central nervous system neurons.
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Affiliation(s)
- Svenja Bolz
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Natalie Kaempf
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Dmytro Puchkov
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Michael Krauss
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Giulia Russo
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Tolga Soykan
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Christopher Schmied
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Rainer Müller
- European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, 69117 Heidelberg, Germany
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, 69117 Heidelberg, Germany; Department of Chemical Physiology & Biochemistry, Oregon Health & Science University (OHSU), Portland, OR 97239, USA
| | - David Perrais
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France
| | - Tanja Maritzen
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany; Department of Nanophysiology, University of Kaiserslautern-Landau, 67663 Kaiserslautern, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany; Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany; NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, 10117 Berlin, Germany.
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3
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Le TPH, Nguyen NTT, Le DDT, Anwar MA, Lee SY. Lipid kinase PIP5Kα contributes to Hippo pathway activation via interaction with Merlin and by mediating plasma membrane targeting of LATS1. Cell Commun Signal 2023; 21:149. [PMID: 37337213 DOI: 10.1186/s12964-023-01161-w] [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: 03/22/2023] [Accepted: 05/07/2023] [Indexed: 06/21/2023] Open
Abstract
BACKGROUND The Hippo pathway plays a critical role in controlled cell proliferation. The tumor suppressor Merlin and large tumor suppressor kinase 1 (LATS1) mediate activation of Hippo pathway, consequently inhibiting the primary effectors, Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ). Phosphatidylinositol 4,5-bisphosphate (PIP2), a lipid present in the plasma membrane (PM), binds to and activates Merlin. Phosphatidylinositol 4-phosphate 5-kinase α (PIP5Kα) is an enzyme responsible for PIP2 production. However, the functional role of PIP5Kα in regulation of Merlin and LATS1 under Hippo signaling conditions remains unclear. METHODS PIP5Kα, Merlin, or LATS1 knockout or knockdown cells and transfected cells with them were used. LATS1, YAP, and TAZ activities were measured using biochemical methods and PIP2 levels were evaluated using cell imaging. Low/high cell density and serum starvation/stimulation conditions were tested. Colocalization of PIP5Kα and PIP2 with Merlin and LATS1, and their protein interactions were examined using transfection, confocal imaging, immunoprecipitation, western blotting, and/or pull-down experiments. Colony formation and adipocyte differentiation assays were performed. RESULTS We found that PIP5Kα induced LATS1 activation and YAP/TAZ inhibition in a kinase activity-dependent manner. Consistent with these findings, PIP5Kα suppressed cell proliferation and enhanced adipocyte differentiation of mesenchymal stem cells. Moreover, PIP5Kα protein stability and PIP2 levels were elevated at high cell density compared with those at low cell density, and both PIP2 and YAP phosphorylation levels initially declined, then recovered upon serum stimulation. Under these conditions, YAP/TAZ activity was aberrantly regulated by PIP5Kα deficiency. Mechanistically, either Merlin deficiency or LATS1 deficiency abrogated PIP5Kα-mediated YAP/TAZ inactivation. Additionally, the catalytic domain of PIP5Kα directly interacted with the band 4.1/ezrin/radixin/moesin domain of Merlin, and this interaction reinforced interaction of Merlin with LATS1. In accordance with these findings, PIP5Kα and PIP2 colocalized with Merlin and LATS1 in the PM. In PIP5Kα-deficient cells, Merlin colocalization with PIP2 was reduced, and LATS1 solubility increased. CONCLUSIONS Collectively, our results support that PIP5Kα serves as an activator of the Hippo pathway through interaction and colocalization with Merlin, which promotes PIP2-dependent Merlin activation and induces local recruitment of LATS1 to the PIP2-rich PM and its activation, thereby negatively regulating YAP/TAZ activity. Video Abstract.
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Affiliation(s)
- Truc Phan Hoang Le
- Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Gyeonggi, 16499, Republic of Korea
| | - Nga Thi Thanh Nguyen
- Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Gyeonggi, 16499, Republic of Korea
| | - Duong Duy Thai Le
- Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Gyeonggi, 16499, Republic of Korea
| | - Muhammad Ayaz Anwar
- Department of Applied Chemistry, Kyung Hee University International Campus, Yongin, Gyeonggi, 17104, Republic of Korea
| | - Sang Yoon Lee
- Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Gyeonggi, 16499, Republic of Korea.
- Institute of Medical Science, Ajou University School of Medicine, Suwon, Gyeonggi, 16499, Republic of Korea.
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Hofbrucker-MacKenzie SA, Seemann E, Westermann M, Qualmann B, Kessels MM. Long-term depression in neurons involves temporal and ultra-structural dynamics of phosphatidylinositol-4,5-bisphosphate relying on PIP5K, PTEN and PLC. Commun Biol 2023; 6:366. [PMID: 37012315 PMCID: PMC10070498 DOI: 10.1038/s42003-023-04726-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 03/17/2023] [Indexed: 04/05/2023] Open
Abstract
Synaptic plasticity involves proper establishment and rearrangement of structural and functional microdomains. Yet, visualization of the underlying lipid cues proved challenging. Applying a combination of rapid cryofixation, membrane freeze-fracturing, immunogold labeling and electron microscopy, we visualize and quantitatively determine the changes and the distribution of phosphatidylinositol-4,5-bisphosphate (PIP2) in the plasma membrane of dendritic spines and subareas thereof at ultra-high resolution. These efforts unravel distinct phases of PIP2 signals during induction of long-term depression (LTD). During the first minutes PIP2 rapidly increases in a PIP5K-dependent manner forming nanoclusters. PTEN contributes to a second phase of PIP2 accumulation. The transiently increased PIP2 signals are restricted to upper and middle spine heads. Finally, PLC-dependent PIP2 degradation provides timely termination of PIP2 cues during LTD induction. Together, this work unravels the spatial and temporal cues set by PIP2 during different phases after LTD induction and dissects the molecular mechanisms underlying the observed PIP2 dynamics.
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Affiliation(s)
- Sarah A Hofbrucker-MacKenzie
- Institute of Biochemistry I, Jena University Hospital - Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Eric Seemann
- Institute of Biochemistry I, Jena University Hospital - Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Martin Westermann
- Center for Electron Microscopy, Jena University Hospital - Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Britta Qualmann
- Institute of Biochemistry I, Jena University Hospital - Friedrich Schiller University Jena, 07743, Jena, Germany.
| | - Michael M Kessels
- Institute of Biochemistry I, Jena University Hospital - Friedrich Schiller University Jena, 07743, Jena, Germany.
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Omar-Hmeadi M, Guček A, Barg S. Local PI(4,5)P 2 signaling inhibits fusion pore expansion during exocytosis. Cell Rep 2023; 42:112036. [PMID: 36701234 DOI: 10.1016/j.celrep.2023.112036] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 11/04/2022] [Accepted: 01/11/2023] [Indexed: 01/26/2023] Open
Abstract
Phosphatidylinositol(4,5)bisphosphate (PI(4,5)P2) is an important signaling phospholipid that is required for regulated exocytosis and some forms of endocytosis. The two processes share a topologically similar pore structure that connects the vesicle lumen with the outside. Widening of the fusion pore during exocytosis leads to cargo release, while its closure initiates kiss&run or cavicapture endocytosis. We show here, using live-cell total internal reflection fluorescence (TIRF) microscopy of insulin granule exocytosis, that transient accumulation of PI(4,5)P2 at the release site recruits components of the endocytic fission machinery and stalls the late fusion pore expansion that is required for peptide release. The absence of clathrin differentiates this mechanism from clathrin-mediated endocytosis. Knockdown of phosphatidylinositol-phosphate-5-kinase-1c or optogenetic recruitment of 5-phosphatase reduces PI(4,5)P2 transients and accelerates fusion pore expansion, suggesting that acute PI(4,5)P2 synthesis is involved. Thus, local phospholipid signaling inhibits fusion pore expansion and peptide release through an unconventional endocytic mechanism.
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Affiliation(s)
- Muhmmad Omar-Hmeadi
- Department of Medical Cell Biology, Uppsala University, BMC Box 571, 751 23 Uppsala, Sweden
| | - Alenka Guček
- Department of Medical Cell Biology, Uppsala University, BMC Box 571, 751 23 Uppsala, Sweden
| | - Sebastian Barg
- Department of Medical Cell Biology, Uppsala University, BMC Box 571, 751 23 Uppsala, Sweden.
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6
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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: 3] [Impact Index Per Article: 3.0] [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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Jensen JB, Falkenburger BH, Dickson EJ, de la Cruz L, Dai G, Myeong J, Jung SR, Kruse M, Vivas O, Suh BC, Hille B. Biophysical physiology of phosphoinositide rapid dynamics and regulation in living cells. J Gen Physiol 2022; 154:e202113074. [PMID: 35583815 PMCID: PMC9121023 DOI: 10.1085/jgp.202113074] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 04/28/2022] [Indexed: 01/07/2023] Open
Abstract
Phosphoinositide membrane lipids are ubiquitous low-abundance signaling molecules. They direct many physiological processes that involve ion channels, membrane identification, fusion of membrane vesicles, and vesicular endocytosis. Pools of these lipids are continually broken down and refilled in living cells, and the rates of some of these reactions are strongly accelerated by physiological stimuli. Recent biophysical experiments described here measure and model the kinetics and regulation of these lipid signals in intact cells. Rapid on-line monitoring of phosphoinositide metabolism is made possible by optical tools and electrophysiology. The experiments reviewed here reveal that as for other cellular second messengers, the dynamic turnover and lifetimes of membrane phosphoinositides are measured in seconds, controlling and timing rapid physiological responses, and the signaling is under strong metabolic regulation. The underlying mechanisms of this metabolic regulation remain questions for the future.
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Affiliation(s)
- Jill B. Jensen
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | | | - Eamonn J. Dickson
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA
| | - Lizbeth de la Cruz
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Gucan Dai
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO
| | - Jongyun Myeong
- Department of Cell Biology and Physiology, Washington University in St. Louis, St. Louis, MO
| | | | - Martin Kruse
- Department of Biology and Program in Neuroscience, Bates College, Lewiston, ME
| | - Oscar Vivas
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Byung-Chang Suh
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
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Serra G, Felice S, Antona V, Di Pace MR, Giuffrè M, Piro E, Corsello G. Cardio-facio-cutaneous syndrome and gastrointestinal defects: report on a newborn with 19p13.3 deletion including the MAP 2 K2 gene. Ital J Pediatr 2022; 48:65. [PMID: 35509048 PMCID: PMC9069788 DOI: 10.1186/s13052-022-01241-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 03/01/2022] [Indexed: 12/03/2022] Open
Abstract
Background Cardio-facio-cutaneous syndrome (CFCS) belongs to RASopathies, a group of conditions caused by mutations in genes encoding proteins of the rat sarcoma/mitogen-activated protein kinase (RAS/MAPK) pathway. It is a rare syndrome, with about 300 patients reported. Main clinical manifestations include facial dysmorphisms, growth failure, heart defects, developmental delay, and ectodermal abnormalities. Mutations (mainly missense) of four genes (BRAF, MAP 2 K1, MAP 2 K2, and KRAS) have been associated to CFCS. However, whole gene deletions/duplications and chromosomal microdeletions have been also reported. Specifically, 19p13.3 deletion including MAP 2 K2 gene are responsible for cardio-facio-cutaneous microdeletion syndrome, whose affected subjects show more severe phenotype than CFCS general population. Case presentation Hereby, we report on a female newborn with prenatal diagnosis of omphalocele, leading to further genetic investigations through amniocentesis. Among these, array comparative genomic hybridization (a-CGH) identified a 19p13.3 microdeletion, spanning 1.27 Mb and including MAP 2 K2 gene. Clinical features at birth (coarse face with dysmorphic features, sparse and friable hair, cutaneous vascular malformations and hyperkeratotic lesions, interventricular septal defect, and omphalocele) were compatible with CFCS diagnosis, and further postnatal genetic investigations were not considered necessary. Soon after discharge, at around 1 month of life, she was readmitted to our Neonatal Intensive Care Unit due to repeated episodes of vomiting, subtending a hypertrophic pyloric stenosis (HPS) which was promptly identified and treated. Conclusions Our report supports the 19p13.3 microdeletion as a contiguous gene syndrome, in which the involvement of the genes contiguous to MAP 2 K2 may modify the patients’ phenotype. It highlights how CFCS affected subjects, including those with 19p13.3 deletions, may have associated gastrointestinal defects (e.g., omphalocele and HPS), providing further data on 19p13.3 microdeletion syndrome, and a better characterization of its genomic and phenotypic features. The complex clinical picture of such patients may be worsened by additional, and even precocious, life-threatening conditions like HPS. Clinicians must consider, anticipate and/or promptly treat possible medical and surgical complications, with the aim of reducing adverse outcomes. Extensive diagnostic work-up, and early, continuous, and multidisciplinary follow-up, as well as integrated care, are necessary for the longitudinal clinical evolution of any single patient.
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Affiliation(s)
- Gregorio Serra
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, Palermo, Italy.
| | - Sofia Felice
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Vincenzo Antona
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Maria Rita Di Pace
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Mario Giuffrè
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Ettore Piro
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Giovanni Corsello
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, Palermo, Italy
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El Alaoui F, Casuso I, Sanchez-Fuentes D, Arpin-Andre C, Rathar R, Baecker V, Castro A, Lorca T, Viaud J, Vassilopoulos S, Carretero-Genevrier A, Picas L. Structural organization and dynamics of FCHo2 docking on membranes. eLife 2022; 11:e73156. [PMID: 35044298 PMCID: PMC8798043 DOI: 10.7554/elife.73156] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 01/18/2022] [Indexed: 11/24/2022] Open
Abstract
Clathrin-mediated endocytosis (CME) is a central trafficking pathway in eukaryotic cells regulated by phosphoinositides. The plasma membrane phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) plays an instrumental role in driving CME initiation. The F-BAR domain-only protein 1 and 2 complex (FCHo1/2) is among the early proteins that reach the plasma membrane, but the exact mechanisms triggering its recruitment remain elusive. Here, we show the molecular dynamics of FCHo2 self-assembly on membranes by combining minimal reconstituted in vitro and cellular systems. Our results indicate that PI(4,5)P2 domains assist FCHo2 docking at specific membrane regions, where it self-assembles into ring-like-shaped protein patches. We show that the binding of FCHo2 on cellular membranes promotes PI(4,5)P2 clustering at the boundary of cargo receptors and that this accumulation enhances clathrin assembly. Thus, our results provide a mechanistic framework that could explain the recruitment of early PI(4,5)P2-interacting proteins at endocytic sites.
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Affiliation(s)
- Fatima El Alaoui
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS UMR 9004, Université de MontpellierMontpellierFrance
| | | | - David Sanchez-Fuentes
- Institut d'Électronique et des Systèmes (IES), CNRS UMR 5214, Université de MontpellierMontpellierFrance
| | - Charlotte Arpin-Andre
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS UMR 9004, Université de MontpellierMontpellierFrance
| | - Raissa Rathar
- Institut d'Électronique et des Systèmes (IES), CNRS UMR 5214, Université de MontpellierMontpellierFrance
| | - Volker Baecker
- Montpellier Ressources Imagerie, BioCampus Montpellier, CNRS, INSERM, Université de MontpellierMontpellierFrance
| | - Anna Castro
- Centre de Biologie Cellulaire de Montpellier (CRBM), CNRS UMR UMR 5237, Université de MontpellierMontpellierFrance
| | - Thierry Lorca
- Centre de Biologie Cellulaire de Montpellier (CRBM), CNRS UMR UMR 5237, Université de MontpellierMontpellierFrance
| | - Julien Viaud
- INSERM UMR1297, Institute of Metabolic and Cardiovascular Diseases (I2MC), University of Toulouse, Paul Sabatier UniversityToulouseFrance
| | - Stéphane Vassilopoulos
- Sorbonne Université, INSERM, Institute of Myology, Centre of Research in Myology, UMRS 974ParisFrance
| | - Adrian Carretero-Genevrier
- Institut d'Électronique et des Systèmes (IES), CNRS UMR 5214, Université de MontpellierMontpellierFrance
| | - Laura Picas
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS UMR 9004, Université de MontpellierMontpellierFrance
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10
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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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11
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Watkins JM, Ross-Elliott TJ, Shan X, Lou F, Dreyer B, Tunc-Ozdemir M, Jia H, Yang J, Oliveira CC, Wu L, Trusov Y, Schwochert TD, Krysan P, Jones AM. Differential regulation of G protein signaling in Arabidopsis through two distinct pathways that internalize AtRGS1. Sci Signal 2021; 14:14/695/eabe4090. [PMID: 34376571 DOI: 10.1126/scisignal.abe4090] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In animals, endocytosis of a seven-transmembrane GPCR is mediated by arrestins to propagate or arrest cytoplasmic G protein-mediated signaling, depending on the bias of the receptor or ligand, which determines how much one transduction pathway is used compared to another. In Arabidopsis thaliana, GPCRs are not required for G protein-coupled signaling because the heterotrimeric G protein complex spontaneously exchanges nucleotide. Instead, the seven-transmembrane protein AtRGS1 modulates G protein signaling through ligand-dependent endocytosis, which initiates derepression of signaling without the involvement of canonical arrestins. Here, we found that endocytosis of AtRGS1 initiated from two separate pools of plasma membrane: sterol-dependent domains and a clathrin-accessible neighborhood, each with a select set of discriminators, activators, and candidate arrestin-like adaptors. Ligand identity (either the pathogen-associated molecular pattern flg22 or the sugar glucose) determined the origin of AtRGS1 endocytosis. Different trafficking origins and trajectories led to different cellular outcomes. Thus, in this system, compartmentation with its associated signalosome architecture drives biased signaling.
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Affiliation(s)
- Justin M Watkins
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Timothy J Ross-Elliott
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Xiaoyi Shan
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Fei Lou
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Bernd Dreyer
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Meral Tunc-Ozdemir
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Haiyan Jia
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jing Yang
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Celio Cabral Oliveira
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Department of Biochemistry and Molecular Biology/Bioagro, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Luguang Wu
- School of Agriculture and Food Science, University of Queensland, St. Lucia, Queensland Q4072, Australia
| | - Yuri Trusov
- School of Agriculture and Food Science, University of Queensland, St. Lucia, Queensland Q4072, Australia
| | - Timothy D Schwochert
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Patrick Krysan
- Department of Horticulture, University of Wisconsin Madison, Madison, WI 53706, USA
| | - Alan M Jones
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. .,Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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12
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Jung SR, Jiang Y, Seo JB, Chiu DT, Hille B, Koh DS. β-arrestin-dependent PI(4,5)P 2 synthesis boosts GPCR endocytosis. Proc Natl Acad Sci U S A 2021; 118:e2011023118. [PMID: 33879605 PMCID: PMC8092559 DOI: 10.1073/pnas.2011023118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
β-arrestins regulate many cellular functions including intracellular signaling and desensitization of G protein-coupled receptors (GPCRs). Previous studies show that β-arrestin signaling and receptor endocytosis are modulated by the plasma membrane phosphoinositide lipid phosphatidylinositol-(4, 5)-bisphosphate (PI(4,5)P2). We found that β-arrestin also helped promote synthesis of PI(4,5)P2 and up-regulated GPCR endocytosis. We studied these questions with the Gq-coupled protease-activated receptor 2 (PAR2), which activates phospholipase C, desensitizes quickly, and undergoes extensive endocytosis. Phosphoinositides were monitored and controlled in live cells using lipid-specific fluorescent probes and genetic tools. Applying PAR2 agonist initiated depletion of PI(4,5)P2, which then recovered during rapid receptor desensitization, giving way to endocytosis. This endocytosis could be reduced by various manipulations that depleted phosphoinositides again right after phosphoinositide recovery: PI(4)P, a precusor of PI(4,5)P2, could be depleted at either the Golgi or the plasma membrane (PM) using a recruitable lipid 4-phosphatase enzyme and PI(4,5)P2 could be depleted at the PM using a recruitable 5-phosphatase. Endocytosis required the phosphoinositides. Knock-down of β-arrestin revealed that endogenous β-arrestin normally doubles the rate of PIP5-kinase (PIP5K) after PAR2 desensitization, boosting PI(4,5)P2-dependent formation of clathrin-coated pits (CCPs) at the PM. Desensitized PAR2 receptors were swiftly immobilized when they encountered CCPs, showing a dwell time of ∼90 s, 100 times longer than for unactivated receptors. PAR2/β-arrestin complexes eventually accumulated around the edges or across the surface of CCPs promoting transient binding of PIP5K-Iγ. Taken together, β-arrestins can coordinate potentiation of PIP5K activity at CCPs to induce local PI(4,5)P2 generation that promotes recruitment of PI(4,5)P2-dependent endocytic machinery.
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Affiliation(s)
- Seung-Ryoung Jung
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195;
- Department of Chemistry, University of Washington, Seattle, WA 98195
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yifei Jiang
- Department of Chemistry, University of Washington, Seattle, WA 98195
| | - Jong Bae Seo
- Department of Biosciences, Mokpo National University, Jeonnam 58554, Republic of Korea
- Department of Biomedicine, Health and Life Convergence Sciences, Mokpo National University, Jeonnam 58554, Republic of Korea
| | - Daniel T Chiu
- Department of Chemistry, University of Washington, Seattle, WA 98195
- Department of Bioengineering, University of Washington, Seattle, WA 98195
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Duk-Su Koh
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
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13
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Jacob RS, Eichmann C, Dema A, Mercadante D, Selenko P. α-Synuclein plasma membrane localization correlates with cellular phosphatidylinositol polyphosphate levels. eLife 2021; 10:61951. [PMID: 33587036 PMCID: PMC7929559 DOI: 10.7554/elife.61951] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 02/12/2021] [Indexed: 12/11/2022] Open
Abstract
The Parkinson's disease protein α-synuclein (αSyn) promotes membrane fusion and fission by interacting with various negatively charged phospholipids. Despite postulated roles in endocytosis and exocytosis, plasma membrane (PM) interactions of αSyn are poorly understood. Here, we show that phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylinositol 3,4,5-trisphosphate (PIP3), two highly acidic components of inner PM leaflets, mediate PM localization of endogenous pools of αSyn in A2780, HeLa, SK-MEL-2, and differentiated and undifferentiated neuronal SH-SY5Y cells. We demonstrate that αSyn binds to reconstituted PIP2 membranes in a helical conformation in vitro and that PIP2 synthesizing kinases and hydrolyzing phosphatases reversibly redistribute αSyn in cells. We further delineate that αSyn-PM targeting follows phosphoinositide-3 kinase (PI3K)-dependent changes of cellular PIP2 and PIP3 levels, which collectively suggests that phosphatidylinositol polyphosphates contribute to αSyn's function(s) at the plasma membrane.
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Affiliation(s)
- Reeba Susan Jacob
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Cédric Eichmann
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Alessandro Dema
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Davide Mercadante
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Philipp Selenko
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
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14
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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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15
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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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16
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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: 34] [Impact Index Per Article: 8.5] [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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17
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Suppression of µ1 subunit of the adaptor protein complex 2 reduces dengue virus release. Virus Genes 2019; 56:27-36. [PMID: 31720911 DOI: 10.1007/s11262-019-01710-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/28/2019] [Indexed: 01/16/2023]
Abstract
Dengue virus (DENV) requires clathrin-mediated endocytosis for its entry into the cells where the adaptor protein complex (AP) is vital for the clathrin-coated vesicle formation. The role of AP-2 was previously examined in the early stages of DENV infection; however, the role of AP-2 in the late stage of DENV infection was not determined. The µ1 subunit of AP-2 (AP2M1) is one of the most important cytoplasmic carrier domains in clathrin-mediated endocytosis and the phosphorylation of this subunit by the kinase enzyme, AP-2 associated protein kinase 1 (AAK1), stimulates clathrin and supports the cell surface receptor incorporation. In the present study, we primarily aimed to investigate the role of AP2M1 by gene silencing approach as well as using naked DENV RNA transfection into AP2M1 knockdown cells. Secondarily, an inhibitor of AAK1, sunitinib was used to investigate whether AAK1 could influence the virus production in DENV-infected Huh7 cells. The knockdown of AP2M1 in the DENV-infected Huh7 cells displayed a reduction in the viral titer at 24 h post-infection. Furthermore, experiments were conducted to bypass the DENV internalization using a naked DENV RNA transfection into the AP2M1 knockdown cells. Higher intracellular DENV RNA, DENV E protein, and intracellular virion were observed, whereas the extracellular virion production was comparably less than that of control. Treatment with sunitinib in DENV-infected Huh7 cells was able to reduce extracellular virion production and was consistent with all four serotypes of DENV. Therefore, our findings demonstrate the role of AP2M1 in the exocytosis step of DENV replication leading to infectious DENV production and the efficacy of sunitinib in suppressing virus production during the infection with different serotypes of DENV.
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18
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Thottacherry JJ, Sathe M, Prabhakara C, Mayor S. Spoiled for Choice: Diverse Endocytic Pathways Function at the Cell Surface. Annu Rev Cell Dev Biol 2019; 35:55-84. [PMID: 31283376 PMCID: PMC6917507 DOI: 10.1146/annurev-cellbio-100617-062710] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Endocytosis has long been identified as a key cellular process involved in bringing in nutrients, in clearing cellular debris in tissue, in the regulation of signaling, and in maintaining cell membrane compositional homeostasis. While clathrin-mediated endocytosis has been most extensively studied, a number of clathrin-independent endocytic pathways are continuing to be delineated. Here we provide a current survey of the different types of endocytic pathways available at the cell surface and discuss a new classification and plausible molecular mechanisms for some of the less characterized pathways. Along with an evolutionary perspective of the origins of some of these pathways, we provide an appreciation of the distinct roles that these pathways play in various aspects of cellular physiology, including the control of signaling and membrane tension.
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Affiliation(s)
- Joseph Jose Thottacherry
- National Centre for Biological Science, Tata Institute for Fundamental Research, Bangalore 560065, India;
| | - Mugdha Sathe
- National Centre for Biological Science, Tata Institute for Fundamental Research, Bangalore 560065, India;
| | - Chaitra Prabhakara
- National Centre for Biological Science, Tata Institute for Fundamental Research, Bangalore 560065, India;
| | - Satyajit Mayor
- National Centre for Biological Science, Tata Institute for Fundamental Research, Bangalore 560065, India;
- Institute for Stem Cell Science and Regenerative Medicine, Bangalore, 560065, India
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19
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DiTirro D, Philbrook A, Rubino K, Sengupta P. The Caenorhabditis elegans Tubby homolog dynamically modulates olfactory cilia membrane morphogenesis and phospholipid composition. eLife 2019; 8:48789. [PMID: 31259686 PMCID: PMC6624019 DOI: 10.7554/elife.48789] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 06/21/2019] [Indexed: 12/13/2022] Open
Abstract
Plasticity in sensory signaling is partly mediated via regulated trafficking of signaling molecules to and from primary cilia. Tubby-related proteins regulate ciliary protein transport; however, their roles in remodeling cilia properties are not fully understood. We find that the C. elegans TUB-1 Tubby homolog regulates membrane morphogenesis and signaling protein transport in specialized sensory cilia. In particular, TUB-1 is essential for sensory signaling-dependent reshaping of olfactory cilia morphology. We show that compromised sensory signaling alters cilia membrane phosphoinositide composition via TUB-1-dependent trafficking of a PIP5 kinase. TUB-1 regulates localization of this lipid kinase at the cilia base in part via localization of the AP-2 adaptor complex subunit DPY-23. Our results describe new functions for Tubby proteins in the dynamic regulation of cilia membrane lipid composition, morphology, and signaling protein content, and suggest that this conserved family of proteins plays a critical role in mediating cilia structural and functional plasticity.
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Affiliation(s)
- Danielle DiTirro
- Department of Biology, Brandeis University, Waltham, United States
| | - Alison Philbrook
- Department of Biology, Brandeis University, Waltham, United States
| | - Kendrick Rubino
- Department of Biology, Brandeis University, Waltham, United States
| | - Piali Sengupta
- Department of Biology, Brandeis University, Waltham, United States
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20
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Nakada-Tsukui K, Watanabe N, Maehama T, Nozaki T. Phosphatidylinositol Kinases and Phosphatases in Entamoeba histolytica. Front Cell Infect Microbiol 2019; 9:150. [PMID: 31245297 PMCID: PMC6563779 DOI: 10.3389/fcimb.2019.00150] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 04/23/2019] [Indexed: 12/11/2022] Open
Abstract
Phosphatidylinositol (PtdIns) metabolism is indispensable in eukaryotes. Phosphoinositides (PIs) are phosphorylated derivatives of PtdIns and consist of seven species generated by reversible phosphorylation of the inositol moieties at the positions 3, 4, and 5. Each of the seven PIs has a unique subcellular and membrane domain distribution. In the enteric protozoan parasite Entamoeba histolytica, it has been previously shown that the PIs phosphatidylinositol 3-phosphate (PtdIns3P), PtdIns(4,5)P2, and PtdIns(3,4,5)P3 are localized to phagosomes/phagocytic cups, plasma membrane, and phagocytic cups, respectively. The localization of these PIs in E. histolytica is similar to that in mammalian cells, suggesting that PIs have orthologous functions in E. histolytica. In contrast, the conservation of the enzymes that metabolize PIs in this organism has not been well-documented. In this review, we summarized the full repertoire of the PI kinases and PI phosphatases found in E. histolytica via a genome-wide survey of the current genomic information. E. histolytica appears to have 10 PI kinases and 23 PI phosphatases. It has a panel of evolutionarily conserved enzymes that generate all the seven PI species. However, class II PI 3-kinases, type II PI 4-kinases, type III PI 5-phosphatases, and PI 4P-specific phosphatases are not present. Additionally, regulatory subunits of class I PI 3-kinases and type III PI 4-kinases have not been identified. Instead, homologs of class I PI 3-kinases and PTEN, a PI 3-phosphatase, exist as multiple isoforms, which likely reflects that elaborate signaling cascades mediated by PtdIns(3,4,5)P3 are present in this organism. There are several enzymes that have the nuclear localization signal: one phosphatidylinositol phosphate (PIP) kinase, two PI 3-phosphatases, and one PI 5-phosphatase; this suggests that PI metabolism also has conserved roles related to nuclear functions in E. histolytica, as it does in model organisms.
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Affiliation(s)
- Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Natsuki Watanabe
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tomohiko Maehama
- Division of Molecular and Cellular Biology, Graduate School of Medicine, Kobe University, Kobe, Japan
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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21
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Lee S, Cheung-See-Kit M, Williams TA, Yamout N, Zufferey R. The glycosomal alkyl-dihydroxyacetonephosphate synthase TbADS is essential for the synthesis of ether glycerophospholipids in procyclic trypanosomes. Exp Parasitol 2018; 185:71-78. [PMID: 29355496 DOI: 10.1016/j.exppara.2018.01.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 12/30/2017] [Accepted: 01/14/2018] [Indexed: 01/15/2023]
Abstract
Glycerophospholipids are the main constituents of the biological membranes in Trypanosoma brucei, which causes sleeping sickness in humans. The present work reports the characterization of the alkyl-dihydroxyacetonephosphate synthase TbADS that catalyzes the committed step in ether glycerophospholipid biosynthesis. TbADS localizes to the glycosomal lumen. TbADS complemented a null mutant of Leishmania major lacking alkyl-dihydroxyacetonephosphate synthase activity and restored the formation of normal form of the ether lipid based virulence factor lipophosphoglycan. Despite lacking alkyl-dihydroxyacetonephosphate synthase activity, a null mutant of TbADS in procyclic trypanosomes remained viable and exhibited normal growth. Comprehensive analysis of cellular glycerophospholipids showed that TbADS was involved in the biosynthesis of all ether glycerophospholipid species, primarily found in the PE and PC classes.
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Affiliation(s)
- Sungsu Lee
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, NY 11439, USA
| | - Melanie Cheung-See-Kit
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, NY 11439, USA
| | - Tyler A Williams
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, NY 11439, USA
| | - Nader Yamout
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, NY 11439, USA
| | - Rachel Zufferey
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, NY 11439, USA.
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22
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Rosquete MR, Davis DJ, Drakakaki G. The Plant Trans-Golgi Network: Not Just a Matter of Distinction. PLANT PHYSIOLOGY 2018; 176:187-198. [PMID: 29192030 PMCID: PMC5761815 DOI: 10.1104/pp.17.01239] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 11/27/2017] [Indexed: 05/18/2023]
Abstract
The trans-Golgi network in plants is a major sorting station of Golgi derived cargo while it also receives recycled material from endocytosis.
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Affiliation(s)
| | - Destiny Jade Davis
- Department of Plant Sciences, University of California, Davis, California 95616
| | - Georgia Drakakaki
- Department of Plant Sciences, University of California, Davis, California 95616
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23
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Wallroth A, Haucke V. Phosphoinositide conversion in endocytosis and the endolysosomal system. J Biol Chem 2017; 293:1526-1535. [PMID: 29282290 DOI: 10.1074/jbc.r117.000629] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Phosphoinositides (PIs) are phospholipids that perform crucial cell functions, ranging from cell migration and signaling to membrane trafficking, by serving as signposts of compartmental membrane identity. Although phosphatidylinositol 4,5-bisphosphate, 3-phosphate, and 3,5-bisphosphate are commonly considered as hallmarks of the plasma membrane, endosomes, and lysosomes, these compartments contain other functionally important PIs. Here, we review the roles of PIs in different compartments of the endolysosomal system in mammalian cells and discuss the mechanisms that spatiotemporally control PI conversion in endocytosis and endolysosomal membrane dynamics during endosome maturation and sorting. As defective PI conversion underlies human genetic diseases, including inherited myopathies, neurological disorders, and cancer, PI-converting enzymes represent potential targets for drug-based therapies.
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Affiliation(s)
- Alexander Wallroth
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin and
| | - Volker Haucke
- From the Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin and .,the Faculty of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
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24
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Zufferey R, Pirani K, Cheung-See-Kit M, Lee S, Williams TA, Chen DG, Hossain MF. The Trypanosoma brucei dihydroxyacetonephosphate acyltransferase TbDAT is dispensable for normal growth but important for synthesis of ether glycerophospholipids. PLoS One 2017; 12:e0181432. [PMID: 28715456 PMCID: PMC5513551 DOI: 10.1371/journal.pone.0181432] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 06/30/2017] [Indexed: 01/28/2023] Open
Abstract
Glycerophospholipids are the most abundant constituents of biological membranes in Trypanosoma brucei, which causes sleeping sickness in humans and nagana in cattle. They are essential cellular components that fulfill various important functions beyond their structural role in biological membranes such as in signal transduction, regulation of membrane trafficking or control of cell cycle progression. Our previous studies have established that the glycerol-3-phosphate acyltransferase TbGAT is dispensable for growth, viability, and ester lipid biosynthesis suggesting the existence of another initial acyltransferase(s). This work presents the characterization of the alternative, dihydroxyacetonephosphate acyltransferase TbDAT, which acylates primarily dihydroxyacetonephosphate and prefers palmitoyl-CoA as an acyl-CoA donor. TbDAT restores the viability of a yeast double null mutant that lacks glycerol-3-phosphate and dihydroxyacetonephosphate acyltransferase activities. A conditional null mutant of TbDAT in T. brucei procyclic form was created and characterized. TbDAT was important for survival during stationary phase and synthesis of ether lipids. In contrast, TbDAT was dispensable for normal growth. Our results show that in T. brucei procyclic forms i) TbDAT but not TbGAT is the physiologically relevant initial acyltransferase and ii) ether lipid precursors are primarily made by TbDAT.
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Affiliation(s)
- Rachel Zufferey
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America.,Department of Biological Sciences, St. John's University, Queens, New York, United States of America
| | - Karim Pirani
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America
| | - Melanie Cheung-See-Kit
- Department of Biological Sciences, St. John's University, Queens, New York, United States of America
| | - Sungsu Lee
- Department of Biological Sciences, St. John's University, Queens, New York, United States of America
| | - Tyler A Williams
- Department of Biological Sciences, St. John's University, Queens, New York, United States of America
| | - Daniel G Chen
- Department of Biological Sciences, St. John's University, Queens, New York, United States of America
| | - Md Faruk Hossain
- Department of Biological Sciences, St. John's University, Queens, New York, United States of America
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25
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Chen C, Wang X, Fang J, Xue J, Xiong X, Huang Y, Hu J, Ling K. EGFR-induced phosphorylation of type Iγ phosphatidylinositol phosphate kinase promotes pancreatic cancer progression. Oncotarget 2017; 8:42621-42637. [PMID: 28388589 PMCID: PMC5522093 DOI: 10.18632/oncotarget.16730] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 01/24/2017] [Indexed: 01/05/2023] Open
Abstract
Pancreatic cancer is one of the deadliest malignancies and effective treatment has always been lacking. In current study, we investigated how the type Iγ phosphatidylinositol phosphate kinase (PIPKIγ) participates in the progression of pancreatic ductal adenocarcinoma (PDAC) for novel therapeutic potentials against this lethal disease. We found that PIPKIγ is up-regulated in all tested PDAC cell lines. The growth factor (including EGFR)-induced tyrosine phosphorylation of PIPKIγ is significantly elevated in in situ and metastatic PDAC tissues. Loss of PIPKIγ inhibits the aggressiveness of PDAC cells by restraining the activities of AKT and STAT3, as well as MT1-MMP expression. Therefore when planted into the pancreas of nude mice, PIPKIγ-depleted PDAC cells exhibits substantially repressed tumor growth and metastasis comparing to control PDAC cells. Results from further studies showed that the phosphorylation-deficient PIPKIγ mutant, unlike its wild-type counterpart, cannot rescue PDAC progression inhibited by PIPKIγ depletion. These findings indicate that PIPKIγ, functioning downstream of EGFR signaling, is critical to the progression of PDAC, and suggest that PIPKIγ is potentially a valuable therapeutic target for PDAC treatment.
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Affiliation(s)
- Chunhua Chen
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
- These authors have contributed equally to this work
| | - Xiangling Wang
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
- These authors have contributed equally to this work
| | - Juemin Fang
- Shanghai Tenth People’s Hospital, Tongji University, Shanghai, China
- These authors have contributed equally to this work
| | - Junli Xue
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Xunhao Xiong
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Yan Huang
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Jinghua Hu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Kun Ling
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
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26
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Schöneberg J, Lehmann M, Ullrich A, Posor Y, Lo WT, Lichtner G, Schmoranzer J, Haucke V, Noé F. Lipid-mediated PX-BAR domain recruitment couples local membrane constriction to endocytic vesicle fission. Nat Commun 2017. [PMID: 28627515 PMCID: PMC5481832 DOI: 10.1038/ncomms15873] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Clathrin-mediated endocytosis (CME) involves membrane-associated scaffolds of the bin-amphiphysin-rvs (BAR) domain protein family as well as the GTPase dynamin, and is accompanied and perhaps triggered by changes in local lipid composition. How protein recruitment, scaffold assembly and membrane deformation is spatiotemporally controlled and coupled to fission is poorly understood. We show by computational modelling and super-resolution imaging that phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] synthesis within the clathrin-coated area of endocytic intermediates triggers selective recruitment of the PX-BAR domain protein SNX9, as a result of complex interactions of endocytic proteins competing for phospholipids. The specific architecture induces positioning of SNX9 at the invagination neck where its self-assembly regulates membrane constriction, thereby providing a template for dynamin fission. These data explain how lipid conversion at endocytic pits couples local membrane constriction to fission. Our work demonstrates how computational modelling and super-resolution imaging can be combined to unravel function and mechanisms of complex cellular processes. The spatiotemporal regulation of membrane scaffolds recruitment and coupling between membrane deformation and fission in endocytosis are unclear. Here the authors show that lipid conversion at endocytic pits recruits SNX9, which couples local membrane constriction to fission in endocytosis.
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Affiliation(s)
- Johannes Schöneberg
- Department of Mathematics and Computer Science, Freie Universität Berlin, Berlin 14195, Germany
| | - Martin Lehmann
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, Berlin 13125, Germany.,Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin 14195, Germany
| | - Alexander Ullrich
- Department of Mathematics and Computer Science, Freie Universität Berlin, Berlin 14195, Germany
| | - York Posor
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, Berlin 13125, Germany.,Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin 14195, Germany
| | - Wen-Ting Lo
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, Berlin 13125, Germany
| | - Gregor Lichtner
- Department of Mathematics and Computer Science, Freie Universität Berlin, Berlin 14195, Germany.,Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, Berlin 13125, Germany
| | - Jan Schmoranzer
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, Berlin 13125, Germany.,Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin 14195, Germany
| | - Volker Haucke
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, Berlin 13125, Germany.,Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin 14195, Germany.,NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Virchowweg 6, Berlin 10117, Germany
| | - Frank Noé
- Department of Mathematics and Computer Science, Freie Universität Berlin, Berlin 14195, Germany
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27
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Daboussi L, Costaguta G, Ghukasyan R, Payne GS. Conserved role for Gga proteins in phosphatidylinositol 4-kinase localization to the trans-Golgi network. Proc Natl Acad Sci U S A 2017; 114:3433-3438. [PMID: 28289207 PMCID: PMC5380026 DOI: 10.1073/pnas.1615163114] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phosphoinositides serve as key membrane determinants for assembly of clathrin coat proteins that drive formation of clathrin-coated vesicles. At the trans-Golgi network (TGN), phosphatidylinositol 4-phosphate (PtdIns4P) plays important roles in recruitment of two major clathrin adaptors, Gga (Golgi-localized, gamma-adaptin ear homology, Arf-binding) proteins and the AP-1 (assembly protein-1) complex. The molecular mechanisms that mediate localization of phosphatidylinositol kinases responsible for synthesis of PtdIns4P at the TGN are not well characterized. We identify two motifs in the yeast phosphatidylinositol 4-kinase, Pik1, which are required for binding to the VHS domain of Gga2. Mutations in these motifs that inhibit Gga2-VHS binding resulted in reduced Pik1 localization and delayed accumulation of PtdIns4P and recruitment of AP-1 to the TGN. The Pik1 homolog in mammals, PI4KIIIβ, interacted preferentially with the VHS domain of GGA2 compared with VHS domains of GGA1 and GGA3. Depletion of GGA2, but not GGA1 or GGA3, specifically affected PI4KIIIβ localization. These results reveal a conserved role for Gga proteins in regulating phosphatidylinositol 4-kinase function at the TGN.
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Affiliation(s)
- Lydia Daboussi
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095
| | - Giancarlo Costaguta
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095
| | - Razmik Ghukasyan
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095
| | - Gregory S Payne
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095
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28
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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: 55] [Impact Index Per Article: 6.9] [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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29
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Patel N, Pirani KA, Zhu T, Cheung-See-Kit M, Lee S, Chen DG, Zufferey R. The Glycerol-3-Phosphate Acyltransferase TbGAT is Dispensable for Viability and the Synthesis of Glycerolipids in Trypanosoma brucei. J Eukaryot Microbiol 2016; 63:598-609. [PMID: 26909872 DOI: 10.1111/jeu.12309] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Revised: 01/30/2016] [Accepted: 02/16/2016] [Indexed: 01/09/2023]
Abstract
Glycerolipids are the main constituents of biological membranes in Trypanosoma brucei, which causes sleeping sickness in humans. Importantly, they occur as a structural component of the glycosylphosphatidylinositol lipid anchor of the abundant cell surface glycoproteins procyclin in procyclic forms and variant surface glycoprotein in bloodstream form, that play crucial roles for the development of the parasite in the insect vector and the mammalian host, respectively. The present work reports the characterization of the glycerol-3-phosphate acyltransferase TbGAT that initiates the biosynthesis of ester glycerolipids. TbGAT restored glycerol-3-phosphate acyltransferase activity when expressed in a Leishmania major deletion strain lacking this activity and exhibited preference for medium length, unsaturated fatty acyl-CoAs. TbGAT localized to the endoplasmic reticulum membrane with its N-terminal domain facing the cytosol. Despite that a TbGAT null mutant in T. brucei procyclic forms lacked glycerol-3-phosphate acyltransferase activity, it remained viable and exhibited similar growth rate as the wild type. TbGAT was dispensable for the biosynthesis of phosphatidylcholine, phosphatidylinositol, phosphatidylserine, and GPI-anchored protein procyclin. However, the null mutant exhibited a slight decrease in phosphatidylethanolamine biosynthesis that was compensated with a modest increase in production of ether phosphatidylcholine. Our data suggest that an alternative initial acyltransferase takes over TbGAT's function in its absence.
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Affiliation(s)
- Nipul Patel
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439
| | - Karim A Pirani
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, 66506
| | - Tongtong Zhu
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439
| | - Melanie Cheung-See-Kit
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439
| | - Sungsu Lee
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439
| | - Daniel G Chen
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439
| | - Rachel Zufferey
- Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439.,Department of Biochemistry, Kansas State University, Manhattan, Kansas, 66506
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30
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Whitfield ST, Burston HE, Bean BDM, Raghuram N, Maldonado-Báez L, Davey M, Wendland B, Conibear E. The alternate AP-1 adaptor subunit Apm2 interacts with the Mil1 regulatory protein and confers differential cargo sorting. Mol Biol Cell 2015; 27:588-98. [PMID: 26658609 PMCID: PMC4751606 DOI: 10.1091/mbc.e15-09-0621] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/01/2015] [Indexed: 12/31/2022] Open
Abstract
Adaptor complexes are important for cargo sorting in clathrin-coated vesicles. The µ adaptor subunits Apm1 and Apm2 create functionally distinct versions of the yeast AP-1 complex. A novel regulatory protein is identified that selectively binds Apm2-containing complexes and contributes to their membrane recruitment. Heterotetrameric adaptor protein complexes are important mediators of cargo protein sorting in clathrin-coated vesicles. The cell type–specific expression of alternate μ chains creates distinct forms of AP-1 with altered cargo sorting, but how these subunits confer differential function is unclear. Whereas some studies suggest the μ subunits specify localization to different cellular compartments, others find that the two forms of AP-1 are present in the same vesicle but recognize different cargo. Yeast have two forms of AP-1, which differ only in the μ chain. Here we show that the variant μ chain Apm2 confers distinct cargo-sorting functions. Loss of Apm2, but not of Apm1, increases cell surface levels of the v-SNARE Snc1. However, Apm2 is unable to replace Apm1 in sorting Chs3, which requires a dileucine motif recognized by the γ/σ subunits common to both complexes. Apm2 and Apm1 colocalize at Golgi/early endosomes, suggesting that they do not associate with distinct compartments. We identified a novel, conserved regulatory protein that is required for Apm2-dependent sorting events. Mil1 is a predicted lipase that binds Apm2 but not Apm1 and contributes to its membrane recruitment. Interactions with specific regulatory factors may provide a general mechanism to diversify the functional repertoire of clathrin adaptor complexes.
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Affiliation(s)
- Shawn T Whitfield
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Department of Biochemistry and Molecular Biology and Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Helen E Burston
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Department of Biochemistry and Molecular Biology and Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Björn D M Bean
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Department of Biochemistry and Molecular Biology and Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Nandini Raghuram
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | | | - Michael Davey
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Beverly Wendland
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218-2685
| | - Elizabeth Conibear
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Department of Biochemistry and Molecular Biology and Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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31
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Resolution of structure of PIP5K1A reveals molecular mechanism for its regulation by dimerization and dishevelled. Nat Commun 2015; 6:8205. [PMID: 26365782 PMCID: PMC4570271 DOI: 10.1038/ncomms9205] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 07/28/2015] [Indexed: 02/06/2023] Open
Abstract
Type I phosphatidylinositol phosphate kinase (PIP5K1) phosphorylates the head group of phosphatidylinositol 4-phosphate (PtdIns4P) to generate PtdIns4,5P2, which plays important roles in a wide range of cellular functions including Wnt signalling. However, the lack of its structural information has hindered the understanding of its regulation. Here we report the crystal structure of the catalytic domain of zebrafish PIP5K1A at 3.3 Å resolution. This molecule forms a side-to-side dimer. Mutagenesis study of PIP5K1A reveals two adjacent interfaces for the dimerization and interaction with the DIX domain of the Wnt signalling molecule dishevelled. Although these interfaces are located distally to the catalytic/substrate-binding site, binding to these interfaces either through dimerization or the interaction with DIX stimulates PIP5K1 catalytic activity. DIX binding additionally enhances PIP5K1 substrate binding. Thus, this study elucidates regulatory mechanisms for this lipid kinase and provides a paradigm for the understanding of PIP5K1 regulation by their interacting molecules. Type I phosphatidylinositol phosphate kinase is an important component of many cellular pathways, including Wnt signalling. Here the authors report the crystal structure of the zebrafish protein along with in vitro assays that help to elucidate the regulation and function of this kinase.
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32
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Urbanek AN, Allwood EG, Smith AP, Booth WI, Ayscough KR. Distinct Actin and Lipid Binding Sites in Ysc84 Are Required during Early Stages of Yeast Endocytosis. PLoS One 2015; 10:e0136732. [PMID: 26312755 PMCID: PMC4552428 DOI: 10.1371/journal.pone.0136732] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/08/2015] [Indexed: 11/18/2022] Open
Abstract
During endocytosis in S. cerevisiae, actin polymerization is proposed to provide the driving force for invagination against the effects of turgor pressure. In previous studies, Ysc84 was demonstrated to bind actin through a conserved N-terminal domain. However, full length Ysc84 could only bind actin when its C-terminal SH3 domain also bound to the yeast WASP homologue Las17. Live cell-imaging has revealed that Ysc84 localizes to endocytic sites after Las17/WASP but before other known actin binding proteins, suggesting it is likely to function at an early stage of membrane invagination. While there are homologues of Ysc84 in other organisms, including its human homologue SH3yl-1, little is known of its mode of interaction with actin or how this interaction affects actin filament dynamics. Here we identify key residues involved both in Ysc84 actin and lipid binding, and demonstrate that its actin binding activity is negatively regulated by PI(4,5)P2. Ysc84 mutants defective in their lipid or actin-binding interaction were characterized in vivo. The abilities of Ysc84 to bind Las17 through its C-terminal SH3 domain, or to actin and lipid through the N-terminal domain were all shown to be essential in order to rescue temperature sensitive growth in a strain requiring YSC84 expression. Live cell imaging in strains with fluorescently tagged endocytic reporter proteins revealed distinct phenotypes for the mutants indicating the importance of these interactions for regulating key stages of endocytosis.
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Affiliation(s)
- Agnieszka N. Urbanek
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, United Kingdom
| | - Ellen G. Allwood
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, United Kingdom
| | - Adam P. Smith
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, United Kingdom
| | - Wesley I. Booth
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, United Kingdom
| | - Kathryn R. Ayscough
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield, United Kingdom
- * E-mail:
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33
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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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34
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Lacalle RA, de Karam JC, Martínez-Muñoz L, Artetxe I, Peregil RM, Sot J, Rojas AM, Goñi FM, Mellado M, Mañes S. Type I phosphatidylinositol 4-phosphate 5-kinase homo- and heterodimerization determines its membrane localization and activity. FASEB J 2015; 29:2371-85. [PMID: 25713054 DOI: 10.1096/fj.14-264606] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 02/03/2015] [Indexed: 11/11/2022]
Abstract
Type I phosphatidylinositol 4-phosphate 5-kinases (PIP5KIs; α, β, and γ) are a family of isoenzymes that produce phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] using phosphatidylinositol 4-phosphate as substrate. Their structural homology with the class II lipid kinases [type II phosphatidylinositol 5-phosphate 4-kinase (PIP4KII)] suggests that PIP5KI dimerizes, although this has not been formally demonstrated. Neither the hypothetical structural dimerization determinants nor the functional consequences of dimerization have been studied. Here, we used Förster resonance energy transfer, coprecipitation, and ELISA to show that PIP5KIβ forms homo- and heterodimers with PIP5KIγ_i2 in vitro and in live human cells. Dimerization appears to be a general phenomenon for PIP5KI isoenzymes because PIP5KIβ/PIP5KIα heterodimers were also detected by mass spectrometry. Dimerization was independent of actin cytoskeleton remodeling and was also observed using purified proteins. Mutagenesis studies of PIP5KIβ located the dimerization motif at the N terminus, in a region homologous to that implicated in PIP4KII dimerization. PIP5KIβ mutants whose dimerization was impaired showed a severe decrease in PI(4,5)P2 production and plasma membrane delocalization, although their association to lipid monolayers was unaltered. Our results identify dimerization as an integral feature of PIP5K proteins and a central determinant of their enzyme activity.
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Affiliation(s)
- Rosa Ana Lacalle
- *Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid, Spain; Unidad de Biofísica Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Campus de Leioa, Barrio Sarriena s/n, Leioa, Bizkaia, Spain; and Computational Biology and Bioinformatics Group, Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío-Consejo Superior de Investigaciones Científicas, Manuel Siurot s/n, Seville, Spain
| | - Juan C de Karam
- *Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid, Spain; Unidad de Biofísica Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Campus de Leioa, Barrio Sarriena s/n, Leioa, Bizkaia, Spain; and Computational Biology and Bioinformatics Group, Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío-Consejo Superior de Investigaciones Científicas, Manuel Siurot s/n, Seville, Spain
| | - Laura Martínez-Muñoz
- *Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid, Spain; Unidad de Biofísica Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Campus de Leioa, Barrio Sarriena s/n, Leioa, Bizkaia, Spain; and Computational Biology and Bioinformatics Group, Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío-Consejo Superior de Investigaciones Científicas, Manuel Siurot s/n, Seville, Spain
| | - Ibai Artetxe
- *Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid, Spain; Unidad de Biofísica Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Campus de Leioa, Barrio Sarriena s/n, Leioa, Bizkaia, Spain; and Computational Biology and Bioinformatics Group, Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío-Consejo Superior de Investigaciones Científicas, Manuel Siurot s/n, Seville, Spain
| | - Rosa M Peregil
- *Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid, Spain; Unidad de Biofísica Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Campus de Leioa, Barrio Sarriena s/n, Leioa, Bizkaia, Spain; and Computational Biology and Bioinformatics Group, Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío-Consejo Superior de Investigaciones Científicas, Manuel Siurot s/n, Seville, Spain
| | - Jesús Sot
- *Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid, Spain; Unidad de Biofísica Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Campus de Leioa, Barrio Sarriena s/n, Leioa, Bizkaia, Spain; and Computational Biology and Bioinformatics Group, Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío-Consejo Superior de Investigaciones Científicas, Manuel Siurot s/n, Seville, Spain
| | - Ana M Rojas
- *Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid, Spain; Unidad de Biofísica Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Campus de Leioa, Barrio Sarriena s/n, Leioa, Bizkaia, Spain; and Computational Biology and Bioinformatics Group, Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío-Consejo Superior de Investigaciones Científicas, Manuel Siurot s/n, Seville, Spain
| | - Félix M Goñi
- *Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid, Spain; Unidad de Biofísica Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Campus de Leioa, Barrio Sarriena s/n, Leioa, Bizkaia, Spain; and Computational Biology and Bioinformatics Group, Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío-Consejo Superior de Investigaciones Científicas, Manuel Siurot s/n, Seville, Spain
| | - Mario Mellado
- *Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid, Spain; Unidad de Biofísica Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Campus de Leioa, Barrio Sarriena s/n, Leioa, Bizkaia, Spain; and Computational Biology and Bioinformatics Group, Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío-Consejo Superior de Investigaciones Científicas, Manuel Siurot s/n, Seville, Spain
| | - Santos Mañes
- *Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid, Spain; Unidad de Biofísica Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Campus de Leioa, Barrio Sarriena s/n, Leioa, Bizkaia, Spain; and Computational Biology and Bioinformatics Group, Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío-Consejo Superior de Investigaciones Científicas, Manuel Siurot s/n, Seville, Spain
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Raman D, Sai J, Hawkins O, Richmond A. Adaptor protein2 (AP2) orchestrates CXCR2-mediated cell migration. Traffic 2014; 15:451-69. [PMID: 24450359 DOI: 10.1111/tra.12154] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/16/2014] [Accepted: 01/22/2014] [Indexed: 12/14/2022]
Abstract
The chemokine receptor CXCR2 is vital for inflammation, wound healing, angiogenesis, cancer progression and metastasis. Adaptor protein 2 (AP2), a clathrin binding heterotetrameric protein comprised of α, β2, μ2 and σ2 subunits, facilitates clathrin-mediated endocytosis. Mutation of the LLKIL motif in the CXCR2 carboxyl-terminal domain (CTD) results in loss of AP2 binding to the receptor and loss of ligand-mediated receptor internalization and chemotaxis. AP2 knockdown also results in diminished ligand-mediated CXCR2 internalization, polarization and chemotaxis. Using knockdown/rescue approaches with AP2-μ2 mutants, the binding domains were characterized in reference to CXCR2 internalization and chemotaxis. When in an open conformation, μ2 Patch 1 and Patch 2 domains bind tightly to membrane PIP2 phospholipids. When AP2-μ2, is replaced with μ2 mutated in Patch 1 and/or Patch 2 domains, ligand-mediated receptor binding and internalization are not lost. However, chemotaxis requires AP2-μ2 Patch 1, but not Patch 2. AP2-σ2 has been demonstrated to bind dileucine motifs to facilitate internalization. Expression of AP2-σ2 V88D and V98S dominant negative mutants resulted in loss of CXCR2 mediated chemotaxis. Thus, AP2 binding to both membrane phosphatidylinositol phospholipids and dileucine motifs is crucial for directional migration or chemotaxis. Moreover, AP2-mediated receptor internalization can be dissociated from AP2-mediated chemotaxis.
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Affiliation(s)
- Dayanidhi Raman
- Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, 37212, USA; Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
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Martin TFJ. PI(4,5)P₂-binding effector proteins for vesicle exocytosis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:785-93. [PMID: 25280637 DOI: 10.1016/j.bbalip.2014.09.017] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/20/2014] [Accepted: 09/23/2014] [Indexed: 12/27/2022]
Abstract
PI(4,5)P₂participates directly in priming and possibly in fusion steps of Ca²⁺-triggered vesicle exocytosis. High concentration nanodomains of PI(4,5)P₂reside on the plasma membrane of neuroendocrine cells. A subset of vesicles that co-localize with PI(4,5)P₂ domains appear to undergo preferential exocytosis in stimulated cells. PI(4,5)P₂directly regulates vesicle exocytosis by recruiting and activating PI(4,5)P₂-binding proteins that regulate SNARE protein function including CAPS, Munc13-1/2, synaptotagmin-1, and other C2 domain-containing proteins. These PI(4,5)P₂effector proteins are coincidence detectors that engage in multiple interactions at vesicle exocytic sites. The SNARE protein syntaxin-1 also binds to PI(4,5)P₂, which promotes clustering, but an activating role for PI(4,5)P₂in syntaxin-1 function remains to be fully characterized. Similar principles underlie polarized constitutive vesicle fusion mediated in part by the PI(4,5)P₂-binding subunits of the exocyst complex (Sec3, Exo70). Overall, focal vesicle exocytosis occurs at sites landmarked by PI(4,5)P2, which serves to recruit and/or activate multifunctional PI(4,5)P₂-binding proteins. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Thomas F J Martin
- Biochemistry Department, University of Wisconsin, 433 Babcock Drive, Madison, WI 53706, USA.
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Tourdot RW, Bradley RP, Ramakrishnan N, Radhakrishnan R. Multiscale computational models in physical systems biology of intracellular trafficking. IET Syst Biol 2014; 8:198-213. [PMID: 25257021 PMCID: PMC4336166 DOI: 10.1049/iet-syb.2013.0057] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 07/03/2014] [Accepted: 08/08/2014] [Indexed: 01/19/2023] Open
Abstract
In intracellular trafficking, a definitive understanding of the interplay between protein binding and membrane morphology remains incomplete. The authors describe a computational approach by integrating coarse-grained molecular dynamics (CGMD) simulations with continuum Monte Carlo (CM) simulations of the membrane to study protein-membrane interactions and the ensuing membrane curvature. They relate the curvature field strength discerned from the molecular level to its effect at the cellular length-scale. They perform thermodynamic integration on the CM model to describe the free energy landscape of vesiculation in clathrin-mediated endocytosis. The method presented here delineates membrane morphologies and maps out the free energy changes associated with membrane remodeling due to varying coat sizes, coat curvature strengths, membrane bending rigidities, and tensions; furthermore several constraints on mechanisms underlying clathrin-mediated endocytosis have also been identified, Their CGMD simulations have revealed the importance of PIP2 for stable binding of proteins essential for curvature induction in the bilayer and have provided a molecular basis for the positive curvature induction by the epsin N-terminal homology (EIMTH) domain. Calculation of the free energy landscape for vesicle budding has identified the critical size and curvature strength of a clathrin coat required for nucleation and stabilisation of a mature vesicle.
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Affiliation(s)
- Richard W Tourdot
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ryan P Bradley
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Natesan Ramakrishnan
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ravi Radhakrishnan
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Daumke O, Roux A, Haucke V. BAR domain scaffolds in dynamin-mediated membrane fission. Cell 2014; 156:882-92. [PMID: 24581490 DOI: 10.1016/j.cell.2014.02.017] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Indexed: 10/25/2022]
Abstract
Biological membranes undergo constant remodeling by membrane fission and fusion to change their shape and to exchange material between subcellular compartments. During clathrin-mediated endocytosis, the dynamic assembly and disassembly of protein scaffolds comprising members of the bin-amphiphysin-rvs (BAR) domain protein superfamily constrain the membrane into distinct shapes as the pathway progresses toward fission by the GTPase dynamin. In this Review, we discuss how BAR domain protein assembly and disassembly are controlled in space and time and which structural and biochemical features allow the tight regulation of their shape and function to enable dynamin-mediated membrane fission.
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Affiliation(s)
- Oliver Daumke
- Max-Delbrück Centrum für Molekulare Medizin, Robert-Rössle-Strasse 10, 13125 Berlin, Germany; Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 6, 14195 Berlin, Germany.
| | - Aurélien Roux
- University of Geneva, Department of Biochemistry, 30 quai Ernest Ansermet, 1211 Geneva 4, Switzerland, and Swiss National Centre for Competence in Research Programme Chemical Biology, 1211 Geneva, Switzerland.
| | - Volker Haucke
- Leibniz Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany; NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
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Rocha-Perugini V, Gordon-Alonso M, Sánchez-Madrid F. PIP2: choreographer of actin-adaptor proteins in the HIV-1 dance. Trends Microbiol 2014; 22:379-88. [PMID: 24768560 DOI: 10.1016/j.tim.2014.03.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 03/11/2014] [Accepted: 03/25/2014] [Indexed: 02/06/2023]
Abstract
The actin cytoskeleton plays a key role during the replication cycle of human immunodeficiency virus-1 (HIV-1). HIV-1 infection is affected by cellular proteins that influence the clustering of viral receptors or the subcortical actin cytoskeleton. Several of these actin-adaptor proteins are controlled by the second messenger phosphatidylinositol 4,5-biphosphate (PIP2), an important regulator of actin organization. PIP2 production is induced by HIV-1 attachment and facilitates viral infection. However, the importance of PIP2 in regulating cytoskeletal proteins and thus HIV-1 infection has been overlooked. This review examines recent reports describing the roles played by actin-adaptor proteins during HIV-1 infection of CD4+ T cells, highlighting the influence of the signaling lipid PIP2 in this process.
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Affiliation(s)
- Vera Rocha-Perugini
- Servicio de Inmunología, Hospital Universitario de la Princesa, Instituto de Investigación Sanitaria de la Princesa, Madrid, Spain; Vascular Biology and Inflammation Department, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Mónica Gordon-Alonso
- Servicio de Inmunología, Hospital Universitario de la Princesa, Instituto de Investigación Sanitaria de la Princesa, Madrid, Spain
| | - Francisco Sánchez-Madrid
- Servicio de Inmunología, Hospital Universitario de la Princesa, Instituto de Investigación Sanitaria de la Princesa, Madrid, Spain; Vascular Biology and Inflammation Department, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain.
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Demmel L, Schmidt K, Lucast L, Havlicek K, Zankel A, Koestler T, Reithofer V, de Camilli P, Warren G. The endocytic activity of the flagellar pocket in Trypanosoma brucei is regulated by an adjacent phosphatidylinositol phosphate kinase. J Cell Sci 2014; 127:2351-64. [PMID: 24639465 DOI: 10.1242/jcs.146894] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Phosphoinositides are spatially restricted membrane signaling molecules. Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]--a phosphoinositide that is highly enriched in, and present throughout, the plasma membrane--has been implicated in endocytosis. Trypanosoma brucei has one of the highest known rates of endocytosis, a process it uses to evade the immune system. To determine whether phosphoinositides play a role in endocytosis in this organism, we have identified and characterized one of the enzymes that is responsible for generating PI(4,5)P2. Surprisingly, this phosphoinositide was found to be highly concentrated in the flagellar pocket, the only site of endocytosis and exocytosis in this organism. The enzyme (designated TbPIPKA, annotated as Tb927.10.1620) was present at the neck of the pocket, towards the anterior-end of the parasite. Depletion of TbPIPKA led to depletion of PI(4,5)P2 and enlargement of the pocket, the result of impaired endocytosis. Taken together, these data suggest that TbPIPKA and its product PI(4,5)P2 are important for endocytosis and, consequently, for homeostasis of the flagellar pocket.
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Affiliation(s)
- Lars Demmel
- Max F. Perutz Laboratories, University of Vienna, Medical University of Vienna, 1030 Vienna, Austria
| | - Katy Schmidt
- Department of Cell Biology and Ultrastructure Research, Center for Anatomy and Cell Biology, Medical University of Vienna, 1090 Vienna, Austria
| | - Louise Lucast
- Department of Cell Biology, Howard Hughes Medical Institute, and Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Katharina Havlicek
- Max F. Perutz Laboratories, University of Vienna, Medical University of Vienna, 1030 Vienna, Austria
| | - Armin Zankel
- Institute for Electron Microscopy, Graz University of Technology and Center for Electron Microscopy Graz, 8010 Graz, Austria
| | - Tina Koestler
- Center for Integrative Bioinformatics, Max F. Perutz Laboratories, University of Vienna and Medical University of Vienna, 1030 Vienna, Austria
| | - Viktoria Reithofer
- University of Applied Sciences Wiener Neustadt, Department of Biomedical Analytics, 2700 Wiener Neustadt, Austria
| | - Pietro de Camilli
- Department of Cell Biology, Howard Hughes Medical Institute, and Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Graham Warren
- Max F. Perutz Laboratories, University of Vienna, Medical University of Vienna, 1030 Vienna, Austria
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Gariano G, Guarienti M, Bresciani R, Borsani G, Carola G, Monti E, Giuliani R, Rezzani R, Bonomini F, Preti A, Schu P, Zizioli D. Analysis of three μ1-AP1 subunits during zebrafish development. Dev Dyn 2013; 243:299-314. [PMID: 24123392 DOI: 10.1002/dvdy.24071] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 09/25/2013] [Accepted: 09/27/2013] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The family of AP-1 complexes mediates protein sorting in the late secretory pathway and it is essential for the development of mammals. The ubiquitously expressed AP-1A complex consists of four adaptins γ1, β1, μ1A, and σ1A. AP-1A mediates protein transport between the trans-Golgi network and early endosomes. The polarized epithelia AP-1B complex contains the μ1B-adaptin. AP-1B mediates specific transport of proteins from basolateral recycling endosomes to the basolateral plasma membrane of polarized epithelial cells. RESULTS Analysis of the zebrafish genome revealed the existence of three μ1-adaptin genes, encoding μ1A, μ1B, and the novel isoform μ1C, which is not found in mammals. μ1C shows 80% sequence identity with μ1A and μ1B. The μ1C expression pattern largely overlaps with that of μ1A, while μ1B is expressed in epithelial cells. By knocking-down the synthesis of μ1A, μ1B and μ1C with antisense morpholino techniques we demonstrate that each of these μ1 adaptins is essential for zebrafish development, with μ1A and μ1C being involved in central nervous system development and μ1B in kidney, gut and liver formation. CONCLUSIONS Zebrafish is unique in expressing three AP-1 complexes: AP-1A, AP-1B, and AP-1C. Our results demonstrate that they are not redundant and that each of them has specific functions, which cannot be fulfilled by one of the other isoforms. Each of the μ1 adaptins appears to mediate specific molecular mechanisms essential for early developmental processes, which depends on specific intracellular vesicular protein sorting pathways.
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Affiliation(s)
- Giuseppina Gariano
- Unit of Experimental Oncology and Immunology, Department of Molecular and Translational Medicine University of Brescia, Italy
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Chen B, Siderovski DP, Neubig RR, Lawson MA, Trejo J. Regulation of protease-activated receptor 1 signaling by the adaptor protein complex 2 and R4 subfamily of regulator of G protein signaling proteins. J Biol Chem 2013; 289:1580-91. [PMID: 24297163 DOI: 10.1074/jbc.m113.528273] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The G protein-coupled protease-activated receptor 1 (PAR1) is irreversibly proteolytically activated by thrombin. Hence, the precise regulation of PAR1 signaling is important for proper cellular responses. In addition to desensitization, internalization and lysosomal sorting of activated PAR1 are critical for the termination of signaling. Unlike most G protein-coupled receptors, PAR1 internalization is mediated by the clathrin adaptor protein complex 2 (AP-2) and epsin-1, rather than β-arrestins. However, the function of AP-2 and epsin-1 in the regulation of PAR1 signaling is not known. Here, we report that AP-2, and not epsin-1, regulates activated PAR1-stimulated phosphoinositide hydrolysis via two different mechanisms that involve, in part, a subset of R4 subfamily of "regulator of G protein signaling" (RGS) proteins. A significantly greater increase in activated PAR1 signaling was observed in cells depleted of AP-2 using siRNA or in cells expressing a PAR1 (420)AKKAA(424) mutant with defective AP-2 binding. This effect was attributed to AP-2 modulation of PAR1 surface expression and efficiency of G protein coupling. We further found that ectopic expression of R4 subfamily members RGS2, RGS3, RGS4, and RGS5 reduced activated PAR1 wild-type signaling, whereas signaling by the PAR1 AKKAA mutant was minimally affected. Intriguingly, siRNA-mediated depletion analysis revealed a function for RGS5 in the regulation of signaling by the PAR1 wild type but not the AKKAA mutant. Moreover, activation of the PAR1 wild type, and not the AKKAA mutant, induced Gαq association with RGS3 via an AP-2-dependent mechanism. Thus, AP-2 regulates activated PAR1 signaling by altering receptor surface expression and through recruitment of RGS proteins.
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Affiliation(s)
- Buxin Chen
- From the Departments of Pharmacology and
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43
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Wieffer M, Cibrián Uhalte E, Posor Y, Otten C, Branz K, Schütz I, Mössinger J, Schu P, Abdelilah-Seyfried S, Krauß M, Haucke V. PI4K2β/AP-1-Based TGN-Endosomal Sorting Regulates Wnt Signaling. Curr Biol 2013; 23:2185-90. [DOI: 10.1016/j.cub.2013.09.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 08/08/2013] [Accepted: 09/06/2013] [Indexed: 10/26/2022]
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Di Rubbo S, Irani NG, Kim SY, Xu ZY, Gadeyne A, Dejonghe W, Vanhoutte I, Persiau G, Eeckhout D, Simon S, Song K, Kleine-Vehn J, Friml J, De Jaeger G, Van Damme D, Hwang I, Russinova E. The clathrin adaptor complex AP-2 mediates endocytosis of brassinosteroid insensitive1 in Arabidopsis. THE PLANT CELL 2013; 25:2986-97. [PMID: 23975899 PMCID: PMC3784593 DOI: 10.1105/tpc.113.114058] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 07/22/2013] [Accepted: 08/06/2013] [Indexed: 05/18/2023]
Abstract
Clathrin-mediated endocytosis (CME) regulates many aspects of plant development, including hormone signaling and responses to environmental stresses. Despite the importance of this process, the machinery that regulates CME in plants is largely unknown. In mammals, the heterotetrameric adaptor protein complex-2 (AP-2) is required for the formation of clathrin-coated vesicles at the plasma membrane (PM). Although the existence of AP-2 has been predicted in Arabidopsis thaliana, the biochemistry and functionality of the complex is still uncharacterized. Here, we identified all the subunits of the Arabidopsis AP-2 by tandem affinity purification and found that one of the large AP-2 subunits, AP2A1, localized at the PM and interacted with clathrin. Furthermore, endocytosis of the leucine-rich repeat receptor kinase, brassinosteroid insensitive1 (BRI1), was shown to depend on AP-2. Knockdown of the two Arabidopsis AP2A genes or overexpression of a dominant-negative version of the medium AP-2 subunit, AP2M, impaired BRI1 endocytosis and enhanced the brassinosteroid signaling. Our data reveal that the CME machinery in Arabidopsis is evolutionarily conserved and that AP-2 functions in receptor-mediated endocytosis.
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Affiliation(s)
- Simone Di Rubbo
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Niloufer G. Irani
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Soo Youn Kim
- Division of Molecules and Life Sciences and Center for Plant Intracellular Trafficking, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Zheng-Yi Xu
- Division of Molecules and Life Sciences and Center for Plant Intracellular Trafficking, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Astrid Gadeyne
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Wim Dejonghe
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Isabelle Vanhoutte
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Geert Persiau
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Dominique Eeckhout
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Sibu Simon
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Kyungyoung Song
- Division of Molecules and Life Sciences and Center for Plant Intracellular Trafficking, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Jürgen Kleine-Vehn
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Jiří Friml
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Geert De Jaeger
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Daniël Van Damme
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Inhwan Hwang
- Division of Molecules and Life Sciences and Center for Plant Intracellular Trafficking, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Eugenia Russinova
- Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Address correspondence to
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Spatiotemporal control of endocytosis by phosphatidylinositol-3,4-bisphosphate. Nature 2013; 499:233-7. [PMID: 23823722 DOI: 10.1038/nature12360] [Citation(s) in RCA: 303] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 06/06/2013] [Indexed: 12/11/2022]
Abstract
Phosphoinositides serve crucial roles in cell physiology, ranging from cell signalling to membrane traffic. Among the seven eukaryotic phosphoinositides the best studied species is phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2), which is concentrated at the plasma membrane where, among other functions, it is required for the nucleation of endocytic clathrin-coated pits. No phosphatidylinositol other than PI(4,5)P2 has been implicated in clathrin-mediated endocytosis, whereas the subsequent endosomal stages of the endocytic pathway are dominated by phosphatidylinositol-3-phosphates(PI(3)P). How phosphatidylinositol conversion from PI(4,5)P2-positive endocytic intermediates to PI(3)P-containing endosomes is achieved is unclear. Here we show that formation of phosphatidylinositol-3,4-bisphosphate (PI(3,4)P2) by class II phosphatidylinositol-3-kinase C2α (PI(3)K C2α) spatiotemporally controls clathrin-mediated endocytosis. Depletion of PI(3,4)P2 or PI(3)K C2α impairs the maturation of late-stage clathrin-coated pits before fission. Timed formation of PI(3,4)P2 by PI(3)K C2α is required for selective enrichment of the BAR domain protein SNX9 at late-stage endocytic intermediates. These findings provide a mechanistic framework for the role of PI(3,4)P2 in endocytosis and unravel a novel discrete function of PI(3,4)P2 in a central cell physiological process.
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Mutant huntingtin affects endocytosis in striatal cells by altering the binding of AP-2 to membranes. Exp Neurol 2013; 241:75-83. [DOI: 10.1016/j.expneurol.2012.11.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 11/21/2012] [Accepted: 11/26/2012] [Indexed: 11/18/2022]
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Kim I, Pan W, Jones SA, Zhang Y, Zhuang X, Wu D. Clathrin and AP2 are required for PtdIns(4,5)P2-mediated formation of LRP6 signalosomes. ACTA ACUST UNITED AC 2013; 200:419-28. [PMID: 23400998 PMCID: PMC3575536 DOI: 10.1083/jcb.201206096] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
PtdIns(4,5)P2 promotes the assembly of LRP6 signalosomes at the cell surface via the recruitment of AP2 and clathrin. Canonical Wnt signaling is initiated by the binding of Wnt proteins to their receptors, low-density lipoprotein-related protein 5 and 6 (LRP5/6) and frizzled proteins, leading to phosphatidylinositol (4,5)bisphosphate (PtdIns(4,5)P2) production, signalosome formation, and LRP phosphorylation. However, the mechanism by which PtdIns(4,5)P2 regulates the signalosome formation remains unclear. Here we show that clathrin and adaptor protein 2 (AP2) were part of the LRP6 signalosomes. The presence of clathrin and AP2 in the LRP6 signalosomes depended on PtdIns(4,5)P2, and both clathrin and AP2 were required for the formation of LRP6 signalosomes. In addition, WNT3A-induced LRP6 signalosomes were primarily localized at cell surfaces, and WNT3A did not induce marked LRP6 internalization. However, rapid PtdIns(4,5)P2 hydrolysis induced artificially after WNT3A stimulation could lead to marked LRP6 internalization. Moreover, we observed WNT3A-induced LRP6 and clathrin clustering at cell surfaces using super-resolution fluorescence microscopy. Therefore, we conclude that PtdIns(4,5)P2 promotes the assembly of LRP6 signalosomes via the recruitment of AP2 and clathrin and that LRP6 internalization may not be a prerequisite for Wnt signaling to β-catenin stabilization.
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Affiliation(s)
- Ingyu Kim
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06510, USA
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Szalinski CM, Guerriero CJ, Ruiz WG, Docter BE, Rbaibi Y, Pastor-Soler NM, Apodaca G, Puthenveedu MA, Weisz OA. PIP5KIβ selectively modulates apical endocytosis in polarized renal epithelial cells. PLoS One 2013; 8:e53790. [PMID: 23342003 PMCID: PMC3547069 DOI: 10.1371/journal.pone.0053790] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 12/05/2012] [Indexed: 12/21/2022] Open
Abstract
Localized synthesis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at clathrin coated pits (CCPs) is crucial for the recruitment of adaptors and other components of the internalization machinery, as well as for regulating actin dynamics during endocytosis. PtdIns(4,5)P2 is synthesized from phosphatidylinositol 4-phosphate by any of three phosphatidylinositol 5-kinase type I (PIP5KI) isoforms (α, β or γ). PIP5KIβ localizes almost exclusively to the apical surface in polarized mouse cortical collecting duct cells, whereas the other isoforms have a less polarized membrane distribution. We therefore investigated the role of PIP5KI isoforms in endocytosis at the apical and basolateral domains. Endocytosis at the apical surface is known to occur more slowly than at the basolateral surface. Apical endocytosis was selectively stimulated by overexpression of PIP5KIβ whereas the other isoforms had no effect on either apical or basolateral internalization. We found no difference in the affinity for PtdIns(4,5)P2-containing liposomes of the PtdIns(4,5)P2 binding domains of epsin and Dab2, consistent with a generic effect of elevated PtdIns(4,5)P2 on apical endocytosis. Additionally, using apical total internal reflection fluorescence imaging and electron microscopy we found that cells overexpressing PIP5KIβ have fewer apical CCPs but more internalized coated structures than control cells, consistent with enhanced maturation of apical CCPs. Together, our results suggest that synthesis of PtdIns(4,5)P2 mediated by PIP5KIβ is rate limiting for apical but not basolateral endocytosis in polarized kidney cells. PtdIns(4,5)P2 may be required to overcome specific structural constraints that limit the efficiency of apical endocytosis.
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Affiliation(s)
- Christina M. Szalinski
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Christopher J. Guerriero
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Wily G. Ruiz
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Brianne E. Docter
- Grand Valley State University, Allendale, Michigan, United States of America
| | - Youssef Rbaibi
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Núria M. Pastor-Soler
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Gerard Apodaca
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Manojkumar A. Puthenveedu
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Ora A. Weisz
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Phosphatidylinositol 4-kinase IIα function at endosomes is regulated by the ubiquitin ligase Itch. EMBO Rep 2012; 13:1087-94. [PMID: 23146885 DOI: 10.1038/embor.2012.164] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 09/10/2012] [Accepted: 09/28/2012] [Indexed: 01/31/2023] Open
Abstract
Phosphatidylinositol (PI) 4-phosphate (PI(4)P) and its metabolizing enzymes serve important functions in cell signalling and membrane traffic. PI 4-kinase type IIα (PI4KIIα) regulates Wnt signalling, endosomal sorting of signalling receptors, and promotes adaptor protein recruitment to endosomes and the trans-Golgi network. Here we identify the E3 ubiquitin ligase Itch as binding partner and regulator of PI4KIIα function. Itch directly associates with and ubiquitinates PI4KIIα, and both proteins colocalize on endosomes containing Wnt-activated frizzled 4 (Fz4) receptor. Depletion of PI4KIIα or Itch regulates Wnt signalling with corresponding changes in Fz4 internalization and degradative sorting. These findings unravel a new molecular link between phosphoinositide-regulated endosomal membrane traffic, ubiquitin and the modulation of Wnt signalling.
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Legate KR, Montag D, Böttcher RT, Takahashi S, Fässler R. Comparative phenotypic analysis of the two major splice isoforms of phosphatidylinositol phosphate kinase type Iγ in vivo. J Cell Sci 2012; 125:5636-46. [PMID: 22976293 DOI: 10.1242/jcs.102145] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Localized production of polyphosphoinositides is critical for their signaling function. To examine the biological relevance of specific pools of phosphatidylinositol 4,5-bisphosphate we compared the consequences of genetically ablating all isoforms of phosphatidylinositol phosphate (PIP) kinase type Iγ (PIPKIγ), encoded by the gene Pip5k1c, versus ablation of a specific splice isoform, PIPKIγ_i2, with respect to three reported PIPKIγ functions. Ablation of PIPKIγ_i2 caused a neuron-specific endocytosis defect similar to that found in PIPKIγ(-/-) mice, while agonist-induced calcium signaling was reduced in PIPKIγ(-/-) cells, but was not affected in the absence of PIPKIγ_i2. A reported contribution of PIPKIγ to epithelial integrity was not evident in PIPKIγ(-/-) mice. Given that mice lacking PIPKIγ_i2 live a normal lifespan whereas PIPKIγ(-/-) mice die shortly after birth, we propose that PIPKIγ-mediated metabotropic calcium signaling may represent an essential function of PIPKIγ, whereas functions specific to the PIPKIγ_i2 splice isoform are not essential for survival.
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Affiliation(s)
- Kyle R Legate
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, 82152 Germany
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