1
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Manzolillo A, Gresing L, Hübner CA, Franzka P. Knockdown of INPP5K compromises the differentiation of N2A cells. Front Mol Neurosci 2024; 17:1356343. [PMID: 38559586 PMCID: PMC10979461 DOI: 10.3389/fnmol.2024.1356343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 02/27/2024] [Indexed: 04/04/2024] Open
Abstract
Inositol polyphosphate 5-phosphatase K (INPP5K), also known as SKIP (skeletal muscle and kidney-enriched inositol phosphatase), is a cytoplasmic enzyme with 5-phosphatase activity toward phosphoinositides (PIs). Mutations in INPP5K are associated with autosomal recessive congenital muscular dystrophy with cataracts and intellectual disability (MDCCAID). Notably, muscular dystrophy is characterized by the hypoglycosylation of dystroglycan. Thus, far, the underlying mechanisms are only partially understood. In this study, we show that INPP5K expression increases during brain development. Knockdown of INPP5K in the neuroblastoma-derived cell line N2A impaired their neuronal-like differentiation and interfered with protein glycosylation.
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Affiliation(s)
- Annamaria Manzolillo
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Lennart Gresing
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Christian A. Hübner
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
- Center of Rare Diseases, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Patricia Franzka
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
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2
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Srivastav S, van der Graaf K, Singh P, Utama AB, Meyer MD, McNew JA, Stern M. Atl (atlastin) regulates mTor signaling and autophagy in Drosophila muscle through alteration of the lysosomal network. Autophagy 2024; 20:131-150. [PMID: 37649246 PMCID: PMC10761077 DOI: 10.1080/15548627.2023.2249794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 08/08/2023] [Accepted: 08/11/2023] [Indexed: 09/01/2023] Open
Abstract
ABBREVIATIONS atl atlastin; ALR autophagic lysosome reformation; ER endoplasmic reticulum; GFP green fluorescent protein; HSP hereditary spastic paraplegia; Lamp1 lysosomal associated membrane protein 1 PolyUB polyubiquitin; RFP red fluorescent protein; spin spinster; mTor mechanistic Target of rapamycin; VCP valosin containing protein.
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Affiliation(s)
| | | | - Pratibha Singh
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | | | - Matthew D. Meyer
- Shared Equipment Authority, Rice University, Houston, Texas, USA
| | - James A. McNew
- Department of BioSciences, Rice University, Houston, Texas, USA
| | - Michael Stern
- Department of BioSciences, Rice University, Houston, Texas, USA
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3
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Loncke J, Luyten T, Ramos AR, Erneux C, Bultynck G. Loss of INPP5K attenuates IP 3-induced Ca 2+ responses in the glioblastoma cell line U-251 MG cells. BBA ADVANCES 2023; 4:100105. [PMID: 37842182 PMCID: PMC10568277 DOI: 10.1016/j.bbadva.2023.100105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 09/19/2023] [Accepted: 09/26/2023] [Indexed: 10/17/2023] Open
Abstract
INPP5K (inositol polyphosphate 5-phosphatase K) is an endoplasmic reticulum (ER)-resident enzyme that acts as a phosphoinositide (PI) 5-phosphatase, capable of dephosphorylating various PIs including PI 4,5-bisphosphate (PI(4,5)P2), a key phosphoinositide found in the plasma membrane. Given its ER localization and substrate specificity, INPP5K may play a role in ER-plasma membrane contact sites. Furthermore, PI(4,5)P2 serves as a substrate for phospholipase C, an enzyme activated downstream of extracellular agonists acting on Gq-coupled receptors or tyrosine-kinase receptors, leading to IP3 production and subsequent release of Ca2+ from the ER, the primary intracellular Ca2+ storage organelle. In this study, we investigated the impact of INPP5K on ER Ca2+ dynamics using a previously established INPP5K-knockdown U-251 MG glioblastoma cell model. We here describe that loss of INPP5K impairs agonist-induced, IP3 receptor (IP3R)-mediated Ca2+ mobilization in intact cells, while the ER Ca2+ content and store-operated Ca2+ influx remain unaffected. To further elucidate the underlying mechanisms, we examined Ca2+ release in permeabilized cells stimulated with exogenous IP3. Interestingly, the absence of INPP5K also disrupted IP3-induced Ca2+ release events. These results suggest that INPP5K may directly influence IP3R activity through mechanisms yet to be resolved. The findings from this study point towards role of INPP5K in modulating ER calcium dynamics, particularly in relation to IP3-mediated signaling pathways. However, further work is needed to establish the general nature of our findings and to unravel the exact molecular mechanisms underlying the interplay between INNP5K function and Ca2+ signaling.
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Affiliation(s)
- Jens Loncke
- Laboratory of Molecular and Cellular Signaling, KU Leuven, Leuven, Belgium
| | - Tomas Luyten
- Laboratory of Molecular and Cellular Signaling, KU Leuven, Leuven, Belgium
| | - Ana Raquel Ramos
- ULB, IRIBHM, Campus Erasme, Bâtiment C, 808 Route de Lennik, Bruxelles 1070, Belgium
| | - Christophe Erneux
- ULB, IRIBHM, Campus Erasme, Bâtiment C, 808 Route de Lennik, Bruxelles 1070, Belgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signaling, KU Leuven, Leuven, Belgium
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4
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Shukla D, Gural BM, Cauley ES, Battula N, Mowla S, Karas BF, Roberts LE, Cavallo L, Turkalj L, Moody SA, Swan LE, Manzini MC. Duplicated zebrafish (Danio rerio) inositol phosphatases inpp5ka and inpp5kb diverged in expression pattern and function. Dev Genes Evol 2023; 233:25-34. [PMID: 37184573 PMCID: PMC10239392 DOI: 10.1007/s00427-023-00703-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 04/27/2023] [Indexed: 05/16/2023]
Abstract
One hurdle in the development of zebrafish models of human disease is the presence of multiple zebrafish orthologs resulting from whole genome duplication in teleosts. Mutations in inositol polyphosphate 5-phosphatase K (INPP5K) lead to a syndrome characterized by variable presentation of intellectual disability, brain abnormalities, cataracts, muscle disease, and short stature. INPP5K is a phosphatase acting at position 5 of phosphoinositides to control their homeostasis and is involved in insulin signaling, cytoskeletal regulation, and protein trafficking. Previously, our group and others have replicated the human phenotypes in zebrafish knockdown models by targeting both INPP5K orthologs inpp5ka and inpp5kb. Here, we show that inpp5ka is the more closely related orthologue to human INPP5K. While both inpp5ka and inpp5kb mRNA expression levels follow a similar trend in the developing head, eyes, and tail, inpp5ka is much more abundantly expressed in these tissues than inpp5kb. In situ hybridization revealed a similar trend, also showing unique localization of inpp5kb in the pineal gland and retina indicating different transcriptional regulation. We also found that inpp5kb has lost its catalytic activity against its preferred substrate, PtdIns(4,5)P2. Since most human mutations are missense changes disrupting phosphatase activity, we propose that loss of inpp5ka alone can be targeted to recapitulate the human presentation. In addition, we show that the function of inpp5kb has diverged from inpp5ka and may play a novel role in the zebrafish.
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Affiliation(s)
- Dhyanam Shukla
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Brian M Gural
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Edmund S Cauley
- Department of Biochemistry and Molecular Medicine, School of Medicine and Health Sciences, The George Washington University, Washington, DC, USA
| | - Namarata Battula
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Shorbon Mowla
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Brittany F Karas
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Llion E Roberts
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Luca Cavallo
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Luka Turkalj
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA
| | - Sally A Moody
- Department of Anatomy and Cell Biology, School of Medicine and Health Sciences, The George Washington University, Washington, DC, USA
| | - Laura E Swan
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - M Chiara Manzini
- Department of Neuroscience and Cell Biology and Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, 89 French Street, CHINJ Rm 3274, New Brunswick, NJ, 08901, USA.
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5
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Davies EM, Gurung R, Le KQ, Roan KT, Harvey RP, Mitchell GM, Schwarz Q, Mitchell CA. PI(4,5)P 2-dependent regulation of endothelial tip cell specification contributes to angiogenesis. SCIENCE ADVANCES 2023; 9:eadd6911. [PMID: 37000875 PMCID: PMC10065449 DOI: 10.1126/sciadv.add6911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 02/24/2023] [Indexed: 06/19/2023]
Abstract
Dynamic positioning of endothelial tip and stalk cells, via the interplay between VEGFR2 and NOTCH signaling, is essential for angiogenesis. VEGFR2 activates PI3K, which phosphorylates PI(4,5)P2 to PI(3,4,5)P3, activating AKT; however, PI3K/AKT does not direct tip cell specification. We report that PI(4,5)P2 hydrolysis by the phosphoinositide-5-phosphatase, INPP5K, contributes to angiogenesis. INPP5K ablation disrupted tip cell specification and impaired embryonic angiogenesis associated with enhanced DLL4/NOTCH signaling. INPP5K degraded a pool of PI(4,5)P2 generated by PIP5K1C phosphorylation of PI(4)P in endothelial cells. INPP5K ablation increased PI(4,5)P2, thereby releasing β-catenin from the plasma membrane, and concurrently increased PI(3,4,5)P3-dependent AKT activation, conditions that licensed DLL4/NOTCH transcription. Suppression of PI(4,5)P2 in INPP5K-siRNA cells by PIP5K1C-siRNA, restored β-catenin membrane localization and normalized AKT signaling. Pharmacological NOTCH or AKT inhibition in vivo or genetic β-catenin attenuation rescued angiogenesis defects in INPP5K-null mice. Therefore, PI(4,5)P2 is critical for β-catenin/DLL4/NOTCH signaling, which governs tip cell specification during angiogenesis.
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Affiliation(s)
- Elizabeth M. Davies
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Rajendra Gurung
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Kai Qin Le
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Katherine T. T. Roan
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | - Richard P. Harvey
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
- School of Clinical Medicine and School of Biotechnology and Biomolecular Science, University of New South Wales, Kensington, New South Wales 2052, Australia
| | - Geraldine M. Mitchell
- O’Brien Institute Department of St Vincent’s Institute and University of Melbourne, Department of Surgery, St. Vincent’s Hospital, Fitzroy, Victoria 3065, Australia
- Health Sciences Faculty, Australian Catholic University, Fitzroy, Victoria 3065, Australia
| | - Quenten Schwarz
- Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, South Australia 5001, Australia
| | - Christina A. Mitchell
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
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6
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Nanayakkara R, Gurung R, Rodgers SJ, Eramo MJ, Ramm G, Mitchell CA, McGrath MJ. Autophagic lysosome reformation in health and disease. Autophagy 2022:1-18. [DOI: 10.1080/15548627.2022.2128019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Randini Nanayakkara
- Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- Monash Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, Victoria, Australia
| | - Rajendra Gurung
- Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Samuel J. Rodgers
- Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Matthew J. Eramo
- Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Georg Ramm
- Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- Monash Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, Victoria, Australia
| | - Christina A. Mitchell
- Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Meagan J. McGrath
- Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
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7
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Lebecq A, Doumane M, Fangain A, Bayle V, Leong JX, Rozier F, Marques-Bueno MD, Armengot L, Boisseau R, Simon ML, Franz-Wachtel M, Macek B, Üstün S, Jaillais Y, Caillaud MC. The Arabidopsis SAC9 enzyme is enriched in a cortical population of early endosomes and restricts PI(4,5)P 2 at the plasma membrane. eLife 2022; 11:73837. [PMID: 36044021 PMCID: PMC9436410 DOI: 10.7554/elife.73837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 07/09/2022] [Indexed: 01/10/2023] Open
Abstract
Membrane lipids, and especially phosphoinositides, are differentially enriched within the eukaryotic endomembrane system. This generates a landmark code by modulating the properties of each membrane. Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] specifically accumulates at the plasma membrane in yeast, animal, and plant cells, where it regulates a wide range of cellular processes including endocytic trafficking. However, the functional consequences of mispatterning PI(4,5)P2 in plants are unknown. Here, we functionally characterized the putative phosphoinositide phosphatase SUPPRESSOR OF ACTIN9 (SAC9) in Arabidopsis thaliana (Arabidopsis). We found that SAC9 depletion led to the ectopic localization of PI(4,5)P2 on cortical intracellular compartments, which depends on PI4P and PI(4,5)P2 production at the plasma membrane. SAC9 localizes to a subpopulation of trans-Golgi Network/early endosomes that are enriched in a region close to the cell cortex and that are coated with clathrin. Furthermore, it interacts and colocalizes with Src Homology 3 Domain Protein 2 (SH3P2), a protein involved in endocytic trafficking. In the absence of SAC9, SH3P2 localization is altered and the clathrin-mediated endocytosis rate is reduced. Together, our results highlight the importance of restricting PI(4,5)P2 at the plasma membrane and illustrate that one of the consequences of PI(4,5)P2 misspatterning in plants is to impact the endocytic trafficking.
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Affiliation(s)
- Alexis Lebecq
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Lyon, France
| | - Mehdi Doumane
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Lyon, France
| | - Aurelie Fangain
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Lyon, France
| | - Vincent Bayle
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Lyon, France
| | - Jia Xuan Leong
- University of Tübingen, Center for Plant Molecular Biology (ZMBP), Tübingen, Germany
| | - Frédérique Rozier
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Lyon, France
| | | | - Laia Armengot
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Lyon, France
| | - Romain Boisseau
- Division of Biological Science, University of Montana, Missoula, United States
| | | | - Mirita Franz-Wachtel
- Interfaculty Institute for Cell Biology, Department of Quantitative Proteomics, University of Tübingen, Tübingen, Germany
| | - Boris Macek
- Interfaculty Institute for Cell Biology, Department of Quantitative Proteomics, University of Tübingen, Tübingen, Germany
| | - Suayib Üstün
- University of Tübingen, Center for Plant Molecular Biology (ZMBP), Tübingen, Germany.,Faculty of Biology & Biotechnology, Ruhr-University Bochum, Bochum, Germany
| | - Yvon Jaillais
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Lyon, France
| | - Marie-Cécile Caillaud
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Lyon, France
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8
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Rodgers SJ, Jones EI, Arumugam S, Hamila SA, Danne J, Gurung R, Eramo MJ, Nanayakkara R, Ramm G, McGrath MJ, Mitchell CA. Endosome maturation links PI3Kα signaling to lysosome repopulation during basal autophagy. EMBO J 2022; 41:e110398. [PMID: 35968799 PMCID: PMC9531306 DOI: 10.15252/embj.2021110398] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 07/19/2022] [Accepted: 07/21/2022] [Indexed: 12/24/2022] Open
Abstract
Autophagy depends on the repopulation of lysosomes to degrade intracellular components and recycle nutrients. How cells co‐ordinate lysosome repopulation during basal autophagy, which occurs constitutively under nutrient‐rich conditions, is unknown. Here, we identify an endosome‐dependent phosphoinositide pathway that links PI3Kα signaling to lysosome repopulation during basal autophagy. We show that PI3Kα‐derived PI(3)P generated by INPP4B on late endosomes was required for basal but not starvation‐induced autophagic degradation. PI(3)P signals were maintained as late endosomes matured into endolysosomes, and served as the substrate for the 5‐kinase, PIKfyve, to generate PI(3,5)P2. The SNX‐BAR protein, SNX2, was recruited to endolysosomes by PI(3,5)P2 and promoted lysosome reformation. Inhibition of INPP4B/PIKfyve‐dependent lysosome reformation reduced autophagic clearance of protein aggregates during proteotoxic stress leading to increased cytotoxicity. Therefore under nutrient‐rich conditions, PI3Kα, INPP4B, and PIKfyve sequentially contribute to basal autophagic degradation and protection from proteotoxic stress via PI(3,5)P2‐dependent lysosome reformation from endolysosomes. These findings reveal that endosome maturation couples PI3Kα signaling to lysosome reformation during basal autophagy.
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Affiliation(s)
- Samuel J Rodgers
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Emily I Jones
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Senthil Arumugam
- Department of Anatomy and Developmental Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.,European Molecular Biological Laboratory Australia, Monash University, Clayton, VIC, Australia
| | - Sabryn A Hamila
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Jill Danne
- Monash Ramaciotti Centre for Cryo Electron Microscopy, A Node of Microscopy Australia, Monash University, Clayton, VIC, Australia
| | - Rajendra Gurung
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Matthew J Eramo
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Randini Nanayakkara
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.,Monash Ramaciotti Centre for Cryo Electron Microscopy, A Node of Microscopy Australia, Monash University, Clayton, VIC, Australia
| | - Georg Ramm
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.,Monash Ramaciotti Centre for Cryo Electron Microscopy, A Node of Microscopy Australia, Monash University, Clayton, VIC, Australia
| | - Meagan J McGrath
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Christina A Mitchell
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
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9
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Tariq K, Luikart BW. Striking a balance: PIP 2 and PIP 3 signaling in neuronal health and disease. EXPLORATION OF NEUROPROTECTIVE THERAPY 2022; 1:86-100. [PMID: 35098253 PMCID: PMC8797975 DOI: 10.37349/ent.2021.00008] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phosphoinositides are membrane phospholipids involved in a variety of cellular processes like growth, development, metabolism, and transport. This review focuses on the maintenance of cellular homeostasis of phosphatidylinositol 4,5-bisphosphate (PIP2), and phosphatidylinositol 3,4,5-trisphosphate (PIP3). The critical balance of these PIPs is crucial for regulation of neuronal form and function. The activity of PIP2 and PIP3 can be regulated through kinases, phosphatases, phospholipases and cholesterol microdomains. PIP2 and PIP3 carry out their functions either indirectly through their effectors activating integral signaling pathways, or through direct regulation of membrane channels, transporters, and cytoskeletal proteins. Any perturbations to the balance between PIP2 and PIP3 signaling result in neurodevelopmental and neurodegenerative disorders. This review will discuss the upstream modulators and downstream effectors of the PIP2 and PIP3 signaling, in the context of neuronal health and disease.
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Affiliation(s)
- Kamran Tariq
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Bryan W Luikart
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
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10
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Venkata PP, Chen Y, Alejo S, He Y, Palacios BE, Loeffel I, Liu J, Pratap UP, Gray G, Achuthan Pillai SM, Zou Y, Lai Z, Suzuki T, Viswanadhapalli S, Palakurthi S, Tekmal RR, Vadlamudi RK, Kost E, Sareddy GR. KDM1A inhibition augments the efficacy of rapamycin for the treatment of endometrial cancer. Cancer Lett 2022; 524:219-231. [PMID: 34673129 PMCID: PMC10000284 DOI: 10.1016/j.canlet.2021.10.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 09/30/2021] [Accepted: 10/13/2021] [Indexed: 11/21/2022]
Abstract
Endometrial cancer (EC) often exhibit aberrant activation of PI3K/Akt/mTOR signaling and targeted therapies using mTOR inhibitors showed limited success. The epigenetic modifier, lysine-specific histone demethylase-1A (KDM1A/LSD1) is overexpressed in EC, however, the mechanistic and therapeutic implications of KDM1A in EC are poorly understood. Here, using 119 FDA-approved drugs screen, we identified that KDM1A inhibition is highly synergistic with mTOR inhibitors. Combination therapy of KDM1A and mTOR inhibitors potently reduced the cell viability, survival, and migration of EC cells. Mechanistic studies demonstrated that KDM1A inhibition attenuated the activation of mTOR signaling cascade and abolished rapamycin induced feedback activation of Akt. RNA-seq analysis identified that KDM1A inhibition downregulated the expression of genes involved in rapamycin induced activation of Akt, including the mTORC2 complex. Chromatin immunoprecipitation experiments confirmed KDM1A recruitment to the promoter regions of mTORC2 complex genes and that KDM1A inhibition promoted enrichment of repressive H3K9me2 marks at their promoters. Combination therapy of KDM1A inhibitor and rapamycin reduced the tumor growth in EC xenograft and patient derived xenograft models in vivo and patient derived tumor explants ex vivo. Importantly, in silico analysis of TCGA EC patients data sets revealed that KDM1A expression positively correlated with the levels of PI3K/Akt/mTOR genes. Collectively, our results provide compelling evidence that KDM1A inhibition potentiates the activity of mTOR inhibitors by attenuating the feedback activation of Akt survival signaling. Furthermore, the use of concurrent KDM1A and mTOR inhibitors may be an attractive targeted therapy for EC patients.
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Affiliation(s)
- Prabhakar Pitta Venkata
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Yihong Chen
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA; Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, PR China
| | - Salvador Alejo
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Yi He
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA; Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, PR China
| | - Bridgitte E Palacios
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Ilanna Loeffel
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Junhao Liu
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA; Department of Oncology, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, PR China
| | - Uday P Pratap
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Gabrielle Gray
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | | | - Yi Zou
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Zhao Lai
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, TX, 78229, USA; Department of Molecular Medicine, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Takayoshi Suzuki
- The Institute of Scientific and Industrial Research, Osaka University, Japan
| | - Suryavathi Viswanadhapalli
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Srinath Palakurthi
- Department of Pharmaceutical Sciences, Texas A&M University, Kingsville, TX, 78363, USA
| | - Rajeshwar R Tekmal
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA; Mays Cancer Center, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Ratna K Vadlamudi
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA; Mays Cancer Center, University of Texas Health San Antonio, San Antonio, TX, 78229, USA; Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, TX 78229, USA
| | - Edward Kost
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA
| | - Gangadhara R Sareddy
- Department of Obstetrics and Gynecology, University of Texas Health San Antonio, San Antonio, TX, 78229, USA; Mays Cancer Center, University of Texas Health San Antonio, San Antonio, TX, 78229, USA.
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11
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Schechter M, Sharon R. An Emerging Role for Phosphoinositides in the Pathophysiology of Parkinson’s Disease. JOURNAL OF PARKINSON'S DISEASE 2021; 11:1725-1750. [PMID: 34151859 PMCID: PMC8609718 DOI: 10.3233/jpd-212684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Recent data support an involvement of defects in homeostasis of phosphoinositides (PIPs) in the pathophysiology of Parkinson’s disease (PD). Genetic mutations have been identified in genes encoding for PIP-regulating and PIP-interacting proteins, that are associated with familial and sporadic PD. Many of these proteins are implicated in vesicular membrane trafficking, mechanisms that were recently highlighted for their close associations with PD. PIPs are phosphorylated forms of the membrane phospholipid, phosphatidylinositol. Their composition in the vesicle’s membrane of origin, as well as membrane of destination, controls vesicular membrane trafficking. We review the converging evidence that points to the involvement of PIPs in PD. The review describes PD- and PIP-associated proteins implicated in clathrin-mediated endocytosis and autophagy, and highlights the involvement of α-synuclein in these mechanisms.
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Affiliation(s)
- Meir Schechter
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Ein Kerem, Jerusalem, Israel
| | - Ronit Sharon
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Ein Kerem, Jerusalem, Israel
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12
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Sun J, Harion R, Naito T, Saheki Y. INPP5K and Atlastin-1 maintain the nonuniform distribution of ER-plasma membrane contacts in neurons. Life Sci Alliance 2021; 4:4/11/e202101092. [PMID: 34556534 PMCID: PMC8507493 DOI: 10.26508/lsa.202101092] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 09/03/2021] [Accepted: 09/11/2021] [Indexed: 02/04/2023] Open
Abstract
In neurons, the ER extends throughout all cellular processes, forming multiple contacts with the plasma membrane (PM) to fine-tune neuronal physiology. However, the mechanisms that regulate the distribution of neuronal ER-PM contacts are not known. Here, we used the Caenorhabditis elegans DA9 motor neuron as our model system and found that neuronal ER-PM contacts are enriched in soma and dendrite and mostly absent in axons. Using forward genetic screen, we identified that the inositol 5-phosphatase, CIL-1 (human INPP5K), and the dynamin-like GTPase, ATLN-1 (human Atlastin-1), help to maintain the non-uniform, somatodendritic enrichment of neuronal ER-PM contacts. Mechanistically, CIL-1 acts upstream of ATLN-1 to maintain the balance between ER tubules and sheets. In mutants of CIL-1 or ATLN-1, ER sheets expand and invade into the axon. This is accompanied by the ectopic formation of axonal ER-PM contacts and defects in axon regeneration following laser-induced axotomy. As INPP5K and Atlastin-1 have been linked to neurological disorders, the unique distribution of neuronal ER-PM contacts maintained by these proteins may support neuronal resilience during the onset and progression of these diseases.
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Affiliation(s)
- Jingbo Sun
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Raihanah Harion
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore .,Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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13
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McGrath MJ, Eramo MJ, Gurung R, Sriratana A, Gehrig SM, Lynch GS, Lourdes SR, Koentgen F, Feeney SJ, Lazarou M, McLean CA, Mitchell CA. Defective lysosome reformation during autophagy causes skeletal muscle disease. J Clin Invest 2021; 131:135124. [PMID: 33119550 PMCID: PMC7773396 DOI: 10.1172/jci135124] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 09/23/2020] [Indexed: 12/17/2022] Open
Abstract
The regulation of autophagy-dependent lysosome homeostasis in vivo is unclear. We showed that the inositol polyphosphate 5-phosphatase INPP5K regulates autophagic lysosome reformation (ALR), a lysosome recycling pathway, in muscle. INPP5K hydrolyzes phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] to phosphatidylinositol 4-phosphate [PI(4)P], and INPP5K mutations cause muscular dystrophy by unknown mechanisms. We report that loss of INPP5K in muscle caused severe disease, autophagy inhibition, and lysosome depletion. Reduced PI(4,5)P2 turnover on autolysosomes in Inpp5k–/– muscle suppressed autophagy and lysosome repopulation via ALR inhibition. Defective ALR in Inpp5k–/– myoblasts was characterized by enlarged autolysosomes and the persistence of hyperextended reformation tubules, structures that participate in membrane recycling to form lysosomes. Reduced disengagement of the PI(4,5)P2 effector clathrin was observed on reformation tubules, which we propose interfered with ALR completion. Inhibition of PI(4,5)P2 synthesis or expression of WT INPP5K but not INPP5K disease mutants in INPP5K-depleted myoblasts restored lysosomal homeostasis. Therefore, bidirectional interconversion of PI(4)P/PI(4,5)P2 on autolysosomes was integral to lysosome replenishment and autophagy function in muscle. Activation of TFEB-dependent de novo lysosome biogenesis did not compensate for loss of ALR in Inpp5k–/– muscle, revealing a dependence on this lysosome recycling pathway. Therefore, in muscle, ALR is indispensable for lysosome homeostasis during autophagy and when defective is associated with muscular dystrophy.
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Affiliation(s)
- Meagan J McGrath
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Matthew J Eramo
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Rajendra Gurung
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Absorn Sriratana
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Stefan M Gehrig
- Centre for Muscle Research, Department of Physiology, School of Biomedical Sciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Gordon S Lynch
- Centre for Muscle Research, Department of Physiology, School of Biomedical Sciences, The University of Melbourne, Melbourne, Victoria, Australia
| | - Sonia Raveena Lourdes
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Frank Koentgen
- Ozgene Pty Ltd, Bentley, Perth, Western Australia, Australia
| | - Sandra J Feeney
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Michael Lazarou
- Neuroscience Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Catriona A McLean
- Department of Anatomical Pathology, Alfred Hospital, Prahran, Melbourne, Victoria, Australia
| | - Christina A Mitchell
- Cancer Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Melbourne, Victoria, Australia
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14
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Chen W, Shen T, Wang L, Lu K. Oligomerization of Selective Autophagy Receptors for the Targeting and Degradation of Protein Aggregates. Cells 2021; 10:cells10081989. [PMID: 34440758 PMCID: PMC8394947 DOI: 10.3390/cells10081989] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 02/05/2023] Open
Abstract
The selective targeting and disposal of solid protein aggregates are essential for cells to maintain protein homoeostasis. Autophagy receptors including p62, NBR1, Cue5/TOLLIP (CUET), and Tax1-binding protein 1 (TAX1BP1) proteins function in selective autophagy by targeting ubiquitinated aggregates through ubiquitin-binding domains. Here, we summarize previous beliefs and recent findings on selective receptors in aggregate autophagy. Since there are many reviews on selective autophagy receptors, we focus on their oligomerization, which enables receptors to function as pathway determinants and promotes phase separation.
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Affiliation(s)
- Wenjun Chen
- Department of Neurosurgery, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; (W.C.); (T.S.); (L.W.)
- Department of Neurology, Shanxi Provincial People’s Hospital, Taiyuan 030012, China
| | - Tianyun Shen
- Department of Neurosurgery, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; (W.C.); (T.S.); (L.W.)
| | - Lijun Wang
- Department of Neurosurgery, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; (W.C.); (T.S.); (L.W.)
| | - Kefeng Lu
- Department of Neurosurgery, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China; (W.C.); (T.S.); (L.W.)
- Correspondence:
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15
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Nakatsu F, Kawasaki A. Functions of Oxysterol-Binding Proteins at Membrane Contact Sites and Their Control by Phosphoinositide Metabolism. Front Cell Dev Biol 2021; 9:664788. [PMID: 34249917 PMCID: PMC8264513 DOI: 10.3389/fcell.2021.664788] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 05/06/2021] [Indexed: 01/10/2023] Open
Abstract
Lipids must be correctly transported within the cell to the right place at the right time in order to be fully functional. Non-vesicular lipid transport is mediated by so-called lipid transfer proteins (LTPs), which contain a hydrophobic cavity that sequesters lipid molecules. Oxysterol-binding protein (OSBP)-related proteins (ORPs) are a family of LTPs known to harbor lipid ligands, such as cholesterol and phospholipids. ORPs act as a sensor or transporter of those lipid ligands at membrane contact sites (MCSs) where two different cellular membranes are closely apposed. In particular, a characteristic functional property of ORPs is their role as a lipid exchanger. ORPs mediate counter-directional transport of two different lipid ligands at MCSs. Several, but not all, ORPs transport their lipid ligand from the endoplasmic reticulum (ER) in exchange for phosphatidylinositol 4-phosphate (PI4P), the other ligand, on apposed membranes. This ORP-mediated lipid “countertransport” is driven by the concentration gradient of PI4P between membranes, which is generated by its kinases and phosphatases. In this review, we will discuss how ORP function is tightly coupled to metabolism of phosphoinositides such as PI4P. Recent progress on the role of ORP-mediated lipid transport/countertransport at multiple MCSs in cellular functions will be also discussed.
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Affiliation(s)
- Fubito Nakatsu
- Department of Neurochemistry and Molecular Cell Biology, Niigata University School of Medicine and Graduate School of Medical/Dental Sciences, Niigata, Japan
| | - Asami Kawasaki
- Department of Neurochemistry and Molecular Cell Biology, Niigata University School of Medicine and Graduate School of Medical/Dental Sciences, Niigata, Japan
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16
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Wang Q, Cao Z, Du B, Zhang Q, Chen L, Wang X, Yuan Z, Wang P, He R, Shan J, Zhao Y, Miao L. Membrane contact site-dependent cholesterol transport regulates Na +/K +-ATPase polarization and spermiogenesis in Caenorhabditis elegans. Dev Cell 2021; 56:1631-1645.e7. [PMID: 34051143 DOI: 10.1016/j.devcel.2021.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 03/08/2021] [Accepted: 05/06/2021] [Indexed: 10/21/2022]
Abstract
Spermiogenesis in nematodes is a process whereby round and quiescent spermatids differentiate into asymmetric and crawling spermatozoa. The molecular mechanism underlying this symmetry breaking remains uncharacterized. In this study, we revealed that sperm-specific Na+/K+-ATPase (NKA) is evenly distributed on the plasma membrane (PM) of Caenorhabditis elegans spermatids but is translocated to and subsequently enters the invaginated membrane of the spermatozoa cell body during sperm activation. The polarization of NKA depends on the transport of cholesterol from the PM to membranous organelles (MOs) via membrane contact sites (MCSs). The inositol 5-phosphatase CIL-1 and the MO-localized PI4P phosphatase SAC-1 may mediate PI4P metabolism to drive cholesterol countertransport via sterol/lipid transport proteins through MCSs. Furthermore, the NKA function is required for C. elegans sperm motility and reproductive success. Our data imply that the lipid dynamics mediated by MCSs might play crucial roles in the establishment of cell polarity. eGraphical abstract.
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Affiliation(s)
- Qiushi Wang
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zheng Cao
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Baochen Du
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi Zhang
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lianwan Chen
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xia Wang
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhiheng Yuan
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Wang
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ruijun He
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jin Shan
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanmei Zhao
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Long Miao
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Center for Biological Imaging, Core Facilities for Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
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17
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INPP4B promotes PI3Kα-dependent late endosome formation and Wnt/β-catenin signaling in breast cancer. Nat Commun 2021; 12:3140. [PMID: 34035258 PMCID: PMC8149851 DOI: 10.1038/s41467-021-23241-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 04/16/2021] [Indexed: 01/17/2023] Open
Abstract
INPP4B suppresses PI3K/AKT signaling by converting PI(3,4)P2 to PI(3)P and INPP4B inactivation is common in triple-negative breast cancer. Paradoxically, INPP4B is also a reported oncogene in other cancers. How these opposing INPP4B roles relate to PI3K regulation is unclear. We report PIK3CA-mutant ER+ breast cancers exhibit increased INPP4B mRNA and protein expression and INPP4B increased the proliferation and tumor growth of PIK3CA-mutant ER+ breast cancer cells, despite suppression of AKT signaling. We used integrated proteomics, transcriptomics and imaging to demonstrate INPP4B localized to late endosomes via interaction with Rab7, which increased endosomal PI3Kα-dependent PI(3,4)P2 to PI(3)P conversion, late endosome/lysosome number and cargo trafficking, resulting in enhanced GSK3β lysosomal degradation and activation of Wnt/β-catenin signaling. Mechanistically, Wnt inhibition or depletion of the PI(3)P-effector, Hrs, reduced INPP4B-mediated cell proliferation and tumor growth. Therefore, INPP4B facilitates PI3Kα crosstalk with Wnt signaling in ER+ breast cancer via PI(3,4)P2 to PI(3)P conversion on late endosomes, suggesting these tumors may be targeted with combined PI3K and Wnt/β-catenin therapies.
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18
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Role of protons in calcium signaling. Biochem J 2021; 478:895-910. [PMID: 33635336 DOI: 10.1042/bcj20200971] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/28/2021] [Accepted: 02/01/2021] [Indexed: 02/03/2023]
Abstract
Thirty-six years after the publication of the important article by Busa and Nuccitelli on the variability of intracellular pH (pHi) and the interdependence of pHi and intracellular Ca2+ concentration ([Ca2+]i), little research has been carried out on pHi and calcium signaling. Moreover, the results appear to be contradictory. Some authors claim that the increase in [Ca2+]i is due to a reduction in pHi, others that it is caused by an increase in pHi. The reasons for these conflicting results have not yet been discussed and clarified in an exhaustive manner. The idea that variations in pHi are insignificant, because cellular buffers quickly stabilize the pHi, may be a limiting and fundamentally wrong concept. In fact, it has been shown that protons can move and react in the cell before they are neutralized. Variations in pHi have a remarkable impact on [Ca2+]i and hence on some of the basic biochemical mechanisms of calcium signaling. This paper focuses on the possible triggering role of protons during their short cellular cycle and it suggests a new hypothesis for an IP3 proton dependent mechanism of action.
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19
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Schurmans S, Vande Catsyne CA, Desmet C, Moës B. The phosphoinositide 5-phosphatase INPP5K: From gene structure to in vivo functions. Adv Biol Regul 2021; 79:100760. [PMID: 33060052 DOI: 10.1016/j.jbior.2020.100760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/05/2020] [Accepted: 10/09/2020] [Indexed: 06/11/2023]
Abstract
INPP5K (Inositol Polyphosphate 5-Phosphatase K, or SKIP (for Skeletal muscle and Kidney enriched Inositol Phosphatase) is a member of the phosphoinositide 5-phosphatases family. Its protein structure is comprised of a N-terminal catalytic domain which hydrolyses both PtdIns(4,5)P2 and PtdIns(3,4,5)P3, followed by a SKICH domain at the C-terminus which is responsible for protein-protein interactions and subcellular localization of INPP5K. Strikingly, INPP5K is mostly concentrated in the endoplasmic reticulum, although it is also detected at the plasma membrane, in the cytosol and the nucleus. Recently, mutations in INPP5K have been detected in patients with a rare form of autosomal recessive congenital muscular dystrophy with cataract, short stature and intellectual disability. INPP5K functions extend from control of insulin signaling, endoplasmic reticulum stress response and structural integrity, myoblast differentiation, cytoskeleton organization, cell adhesion and migration, renal osmoregulation, to cancer. The goal of this review is thus to summarize and comment recent and less recent data in the literature on INPP5K, in particular on the structure, expression, intracellular localization, interactions and functions of this specific member of the 5-phosphatases family.
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Affiliation(s)
- Stéphane Schurmans
- Laboratoire de Génétique Fonctionnelle, GIGA-Research Centre, Building B34, CHU Sart-Tilman, Université de Liège, Avenue de l'Hôpital 11, 4000-Liège, Belgium; Secteur de Biochimie Métabolique Vétérinaire, Département des Sciences Fonctionnelles, Faculté de Médecine Vétérinaire, Building B42, Université de Liège, Quartier Vallée 2, Avenue de Cureghem 7A-7D, 4000-Liège, Belgium.
| | - Charles-Andrew Vande Catsyne
- Laboratoire de Génétique Fonctionnelle, GIGA-Research Centre, Building B34, CHU Sart-Tilman, Université de Liège, Avenue de l'Hôpital 11, 4000-Liège, Belgium
| | - Christophe Desmet
- Laboratory of Cellular and Molecular Immunology, GIGA-Research Centre, Building B34, CHU Sart-Tilman, Université de Liège, Avenue de l'Hôpital 11, 4000-Liège, Belgium
| | - Bastien Moës
- Laboratoire de Génétique Fonctionnelle, GIGA-Research Centre, Building B34, CHU Sart-Tilman, Université de Liège, Avenue de l'Hôpital 11, 4000-Liège, Belgium
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20
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Csolle MP, Ooms LM, Papa A, Mitchell CA. PTEN and Other PtdIns(3,4,5)P 3 Lipid Phosphatases in Breast Cancer. Int J Mol Sci 2020; 21:ijms21239189. [PMID: 33276499 PMCID: PMC7730566 DOI: 10.3390/ijms21239189] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 11/25/2020] [Accepted: 12/01/2020] [Indexed: 12/31/2022] Open
Abstract
The phosphoinositide 3-kinase (PI3K)/AKT signalling pathway is hyperactivated in ~70% of breast cancers. Class I PI3K generates PtdIns(3,4,5)P3 at the plasma membrane in response to growth factor stimulation, leading to AKT activation to drive cell proliferation, survival and migration. PTEN negatively regulates PI3K/AKT signalling by dephosphorylating PtdIns(3,4,5)P3 to form PtdIns(4,5)P2. PtdIns(3,4,5)P3 can also be hydrolysed by the inositol polyphosphate 5-phosphatases (5-phosphatases) to produce PtdIns(3,4)P2. Interestingly, while PTEN is a bona fide tumour suppressor and is frequently mutated/lost in breast cancer, 5-phosphatases such as PIPP, SHIP2 and SYNJ2, have demonstrated more diverse roles in regulating mammary tumourigenesis. Reduced PIPP expression is associated with triple negative breast cancers and reduced relapse-free and overall survival. Although PIPP depletion enhances AKT phosphorylation and supports tumour growth, this also inhibits cell migration and metastasis in vivo, in a breast cancer oncogene-driven murine model. Paradoxically, SHIP2 and SYNJ2 are increased in primary breast tumours, which correlates with invasive disease and reduced survival. SHIP2 or SYNJ2 overexpression promotes breast tumourigenesis via AKT-dependent and independent mechanisms. This review will discuss how PTEN, PIPP, SHIP2 and SYNJ2 distinctly regulate multiple functional targets, and the mechanisms by which dysregulation of these distinct phosphoinositide phosphatases differentially affect breast cancer progression.
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21
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Condon ND, Stow JL, Wall AA. Automated Analysis of Cell Surface Ruffling: Ruffle Quantification Macro. Bio Protoc 2020; 10:e3494. [PMID: 33654725 DOI: 10.21769/bioprotoc.3494] [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: 09/24/2019] [Revised: 12/10/2019] [Accepted: 12/15/2019] [Indexed: 11/02/2022] Open
Abstract
Cell surface protrusions include F-actin rich, wave-like ruffles that are erected transiently in response to stimuli and during cell migration. Macrophages are innate immune cells that ruffle constitutively and more dramatically in cells activated by pathogens. Dorsal ruffles and their resulting macropinosomes are key sites for environmental sampling, pathogen detection and immune signaling. Quantitative assessment of ruffling is important for assessing pathogen responses in macrophages and for analysis of growth factor responses in other cell types but automated and quantitative methods are lacking, and rely on manual and qualitative assessments. Here we present an automated ImageJ macro for quantifying dorsal cell surface protrusions from 3D microscope images. The assay presented here is suitable for high-throughput screening applications to detect drug, pathogen, or growth factor induced changes in cell ruffling by measuring ruffle area and intensity and providing normalized values in an easy to read combined spreadsheet.
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Affiliation(s)
- Nicholas D Condon
- Institute for Molecular Biosciences (IMB) Microscopy, The University of Queensland, Brisbane, Australia.,IMB Centre for Inflammation Disease Research, The University of Queensland, Brisbane, Australia
| | - Jennifer L Stow
- IMB Centre for Inflammation Disease Research, The University of Queensland, Brisbane, Australia
| | - Adam A Wall
- IMB Centre for Inflammation Disease Research, The University of Queensland, Brisbane, Australia
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22
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Ramos AR, Ghosh S, Suhel T, Chevalier C, Obeng EO, Fafilek B, Krejci P, Beck B, Erneux C. Phosphoinositide 5-phosphatases SKIP and SHIP2 in ruffles, the endoplasmic reticulum and the nucleus: An update. Adv Biol Regul 2019; 75:100660. [PMID: 31628071 DOI: 10.1016/j.jbior.2019.100660] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 09/18/2019] [Accepted: 09/30/2019] [Indexed: 01/22/2023]
Abstract
Phosphoinositides (PIs) are phosphorylated derivatives of phosphatidylinositol. They act as signaling molecules linked to essential cellular mechanisms in eukaryotic cells, such as cytoskeleton organization, mitosis, polarity, migration or invasion. PIs are phosphorylated and dephosphorylated by a large number of PI kinases and PI phosphatases acting at the 5-, 4- and 3- position of the inositol ring. PI 5-phosphatases i.e. OCRL, INPP5B, SHIP1/2, Synaptojanin 1/2, INPP5E, INPP5J, SKIP (INPP5K) are enzymes that dephosphorylate the 5-phosphate position of PIs. Several human genetic diseases such as the Lowe syndrome, some congenital muscular dystrophy and opsismodysplasia are due to mutations in PI phosphatases, resulting in loss-of-function. The PI phosphatases are also up or down regulated in several human cancers such as glioblastoma or breast cancer. Their cellular localization, that is dynamic and varies in response to stimuli, is an important issue to understand function. This is the case for two members of the PI 5-phosphatase SKIP and SHIP2. Both enzymes are in ruffles, plasma membranes, the endoplasmic reticulum, a situation that is unique for SKIP, and the nucleus. Following localization, PI 5-phosphatases act on specific cellular pools of PIs, which in turn interact with target proteins. Nuclear PIs have emerged as regulators of genome functions in different area of cell signaling. They often localize to nuclear speckles, as do several PI metabolizing kinases and phosphatases. We asked whether SKIP and SHIP2 could have an impact on nuclear PI(4,5)P2. In two glioblastoma cell models, lowering SKIP expression had an impact on nuclear PI(4,5)P2. In a model of SHIP2 deletion in MCF-7 cells, no change in nuclear PI(4,5)P2 was observed. Finally, we present evidence of an anti-tumoral role of SKIP in vivo, in xenografts using as model U87shSKIP cells.
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Affiliation(s)
- Ana Raquel Ramos
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Somadri Ghosh
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Tara Suhel
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Clément Chevalier
- Center for Microscopy and Molecular Imaging ULB, 12 Rue des Professeurs Jeener et Brachet, 6041, Charleroi, Belgium
| | - Eric Owusu Obeng
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium; Department of Biomedical Sciences, University of Bologna, Via Irnerio, 48, 40126, Bologna, Italy
| | - Bohumil Fafilek
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
| | - Pavel Krejci
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
| | - Benjamin Beck
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Christophe Erneux
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium.
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23
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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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24
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Baba T, Toth DJ, Sengupta N, Kim YJ, Balla T. Phosphatidylinositol 4,5-bisphosphate controls Rab7 and PLEKHM1 membrane cycling during autophagosome-lysosome fusion. EMBO J 2019; 38:e100312. [PMID: 31368593 PMCID: PMC6463214 DOI: 10.15252/embj.2018100312] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 01/02/2019] [Accepted: 01/23/2019] [Indexed: 12/12/2022] Open
Abstract
The small GTPase Rab7 is a key organizer of receptor sorting and lysosomal degradation by recruiting of a variety of effectors depending on its GDP/GTP-bound state. However, molecular mechanisms that trigger Rab7 inactivation remain elusive. Here we find that, among the endosomal pools, Rab7-positive compartments possess the highest level of PI4P, which is primarily produced by PI4K2A kinase. Acute conversion of this endosomal PI4P to PI(4,5)P2 causes Rab7 dissociation from late endosomes and releases a regulator of autophagosome-lysosome fusion, PLEKHM1, from the membrane. Rab7 effectors Vps35 and RILP are not affected by acute PI(4,5)P2 production. Deletion of PI4K2A greatly reduces PIP5Kγ-mediated PI(4,5)P2 production in Rab7-positive endosomes leading to impaired Rab7 inactivation and increased number of LC3-positive structures with defective autophagosome-lysosome fusion. These results reveal a late endosomal PI4P-PI(4,5)P2 -dependent regulatory loop that impacts autophagosome flux by affecting Rab7 cycling and PLEKHM1 association.
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Affiliation(s)
- Takashi Baba
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Daniel J Toth
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Nivedita Sengupta
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Yeun Ju Kim
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Tamas Balla
- Section on Molecular Signal TransductionProgram for Developmental NeuroscienceEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
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25
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Ramos AR, Ghosh S, Dedobbeleer M, Robe PA, Rogister B, Erneux C. Lipid phosphatases SKIP and SHIP2 regulate fibronectin-dependent cell migration in glioblastoma. FEBS J 2019; 286:1120-1135. [PMID: 30695232 DOI: 10.1111/febs.14769] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 11/08/2018] [Accepted: 01/25/2019] [Indexed: 12/19/2022]
Abstract
Cell migration is an important process that occurs during development and has also been linked to the motility of cancer cells. Cytoskeleton reorganization takes place in the migration process leading to lamellipodia formation. Understanding the molecular underpinnings of cell migration is particularly important in studies of glioblastoma, a highly invasive and aggressive cancer type. Two members of the phosphoinositide 5-phosphatase family, SKIP and SHIP2, have been associated with cell migration in glioblastoma; however, the precise role these enzymes play in the process-and whether they work in concert-remains unclear. Here, we compared phosphoinositide 5-phosphatases expression in glioblastoma primary cells and cell lines and showed that SHIP2 and SKIP expression greatly varies between different cell types, while OCRL, another phosphoinositide 5-phosphatase, is constitutively expressed. Upon adhesion of U-251 MG cells to fibronectin, SHIP2, SKIP, and PI(4,5)P2 colocalized in membrane ruffles. Upregulation of PI(4,5)P2 was observed in SKIP-depleted U-251 MG cells compared to control cells, but only when cells were adhered to fibronectin. Both PTEN-deficient (U-251) and PTEN-containing (LN229) glioblastoma cells showed a decrease in cell migration velocity in response to SKIP downregulation. Moreover, a SHIP2 catalytic inhibitor lowered cell migration velocity in the U-251 MG cell line. We conclude that integrin activation in U-251 cells leads to colocalization of both SKIP and SHIP2 in ruffles, where they act as potential drivers of cell migration. Depending on their expression levels in glioblastoma, phosphoinositide 5-phosphatases could cooperate and synergize in the regulation of cell migration and adhesion.
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Affiliation(s)
| | | | | | - Pierre A Robe
- Department of Neurology and Neurosurgery, Utrecht University Medical Center, The Netherlands
| | - Bernard Rogister
- GIGA-Neurosciences Research Center, Université de Liège, Belgium
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26
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Mechanistic insights into the interactions of NAP1 with the SKICH domains of NDP52 and TAX1BP1. Proc Natl Acad Sci U S A 2018; 115:E11651-E11660. [PMID: 30459273 DOI: 10.1073/pnas.1811421115] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
NDP52 and TAX1BP1, two SKIP carboxyl homology (SKICH) domain-containing autophagy receptors, play crucial roles in selective autophagy. The autophagic functions of NDP52 and TAX1BP1 are regulated by TANK-binding kinase 1 (TBK1), which may associate with them through the adaptor NAP1. However, the molecular mechanism governing the interactions of NAP1 with NDP52 and TAX1BP1, as well as the effects induced by TBK1-mediated phosphorylation of NDP52 and TAX1BP1, remains elusive. Here, we report the atomic structures of the SKICH regions of NDP52 and TAX1BP1 in complex with NAP1, which not only uncover the mechanistic bases underpinning the specific interactions of NAP1 with the SKICH domains of NDP52 and TAX1BP1 but also reveal the binding mode of a SKICH domain. Moreover, we uncovered that the SKICH domains of NDP52 and TAX1BP1 share a general binding mode to interact with NAP1. Finally, we also evaluated the currently known TBK1-mediated phosphorylation sites in the SKICH domains of NDP52 and TAX1BP1 on the basis of their interactions with NAP1. In all, our findings provide mechanistic insights into the interactions of NAP1 with NDP52 and TAX1BP1, and are valuable for further understanding the functions of these proteins in selective autophagy.
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27
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Ramos AR, Ghosh S, Erneux C. The impact of phosphoinositide 5-phosphatases on phosphoinositides in cell function and human disease. J Lipid Res 2018; 60:276-286. [PMID: 30194087 DOI: 10.1194/jlr.r087908] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 09/01/2018] [Indexed: 02/06/2023] Open
Abstract
Phosphoinositides (PIs) are recognized as major signaling molecules in many different functions of eukaryotic cells. PIs can be dephosphorylated by multiple phosphatase activities at the 5-, 4-, and 3- positions. Human PI 5-phosphatases belong to a family of 10 members. Except for inositol polyphosphate 5-phosphatase A, they all catalyze the dephosphorylation of PI(4,5)P2 and/or PI(3,4,5)P3 at the 5- position. PI 5-phosphatases thus directly control the levels of PI(3,4,5)P3 and participate in the fine-tuning regulatory mechanisms of PI(3,4)P2 and PI(4,5)P2 Second messenger functions have been demonstrated for PI(3,4)P2 in invadopodium maturation and lamellipodia formation. PI 5-phosphatases can use several substrates on isolated enzymes, and it has been challenging to establish their real substrate in vivo. PI(4,5)P2 has multiple functions in signaling, including interacting with scaffold proteins, ion channels, and cytoskeleton proteins. PI 5-phosphatase isoenzymes have been individually implicated in human diseases, such as the oculocerebrorenal syndrome of Lowe, through mechanisms that include lipid control. Oncogenic and tumor-suppressive functions of PI 5-phosphatases have also been reported in different cell contexts. The mechanisms responsible for genetic diseases and for oncogenic or tumor-suppressive functions are not fully understood. The regulation of PI 5-phosphatases is thus crucial in understanding cell functions.
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Affiliation(s)
- Ana Raquel Ramos
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Somadri Ghosh
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Christophe Erneux
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, 1070 Brussels, Belgium
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28
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Dong R, Zhu T, Benedetti L, Gowrishankar S, Deng H, Cai Y, Wang X, Shen K, De Camilli P. The inositol 5-phosphatase INPP5K participates in the fine control of ER organization. J Cell Biol 2018; 217:3577-3592. [PMID: 30087126 PMCID: PMC6168264 DOI: 10.1083/jcb.201802125] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/26/2018] [Accepted: 07/11/2018] [Indexed: 12/19/2022] Open
Abstract
Endoplasmic reticulum (ER) morphology is dynamic and key to its function during different cellular processes. Dong et al. now show in convergent studies in human cells and Caenorhabditis elegans neurons that a phosphoinositide phosphatase (INPP5K) is localized on the surface of the ER network and helps control the shape of the ER. INPP5K (SKIP) is an inositol 5-phosphatase that localizes in part to the endoplasmic reticulum (ER). We show that recruitment of INPP5K to the ER is mediated by ARL6IP1, which shares features of ER-shaping proteins. Like ARL6IP1, INPP5K is preferentially localized in ER tubules and enriched, relative to other ER resident proteins (Sec61β, VAPB, and Sac1), in newly formed tubules that grow along microtubule tracks. Depletion of either INPP5K or ARL6IP1 results in the increase of ER sheets. In a convergent but independent study, a screen for mutations affecting the distribution of the ER network in dendrites of the PVD neurons of Caenorhabditis elegans led to the isolation of mutants in CIL-1, which encodes the INPP5K worm orthologue. The mutant phenotype was rescued by expression of wild type, but not of catalytically inactive CIL-1. Our results reveal an unexpected role of an ER localized polyphosphoinositide phosphatase in the fine control of ER network organization.
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Affiliation(s)
- Rui Dong
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, New Haven, CT
| | - Ting Zhu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Lorena Benedetti
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, New Haven, CT
| | - Swetha Gowrishankar
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, New Haven, CT
| | - Huichao Deng
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yiying Cai
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, New Haven, CT
| | - Xiangming Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Kang Shen
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China .,University of Chinese Academy of Sciences, Beijing, China.,Department of Biology, Stanford University School of Medicine, Stanford, CA.,Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA
| | - Pietro De Camilli
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT .,Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, New Haven, CT.,Kavli Institute for Neurosciences, Yale University School of Medicine, New Haven, CT
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29
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Ramos AR, Elong Edimo W, Erneux C. Phosphoinositide 5-phosphatase activities control cell motility in glioblastoma: Two phosphoinositides PI(4,5)P2 and PI(3,4)P2 are involved. Adv Biol Regul 2018; 67:40-48. [PMID: 28916189 DOI: 10.1016/j.jbior.2017.09.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 09/01/2017] [Accepted: 09/01/2017] [Indexed: 05/15/2023]
Abstract
Inositol polyphosphate 5-phosphatases or phosphoinositide 5-phosphatases (PI 5-phosphatases) are enzymes that can act on soluble inositol phosphates and/or phosphoinositides (PIs). Several PI 5-phosphatases have been linked to human genetic diseases, in particular the Lowe protein or OCRL which is mutated in the Lowe syndrome. There are 10 different members of this family and 9 of them can use PIs as substrate. One of these substrates, PI(3,4,5)P3 binds to specific PH domains and recruits as effectors specific proteins to signaling complexes. Protein kinase B is one target protein and activation of the kinase will have a major impact on cell proliferation, survival and cell metabolism. Two other PIs, PI(4,5)P2 and PI(3,4)P2, are produced or used as substrates of PI 5-phosphatases (OCRL, INPP5B, SHIP1/2, SYNJ1/2, INPP5K, INPP5J, INPP5E). The inositol lipids may influence many aspects of cytoskeletal organization, lamellipodia formation and F-actin polymerization. PI 5-phosphatases have been reported to control cell migration, adhesion, polarity and cell invasion particularly in cancer cells. In glioblastoma, reducing SHIP2 expression can positively or negatively affect the speed of cell migration depending on the glioblastoma cell type. The two PI 5-phosphatases SHIP2 or SKIP could be localized at the plasma membrane and can reduce either PI(3,4,5)P3 or PI(4,5)P2 abundance. In the glioblastoma 1321 N1 cells, SHIP2 controls plasma membrane PI(4,5)P2 thereby participating in the control of cell migration.
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Affiliation(s)
- Ana Raquel Ramos
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, Campus Erasme, Bldg C, 808 Route de Lennik, 1070 Brussels, Belgium
| | - William's Elong Edimo
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, Campus Erasme, Bldg C, 808 Route de Lennik, 1070 Brussels, Belgium
| | - Christophe Erneux
- Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, Campus Erasme, Bldg C, 808 Route de Lennik, 1070 Brussels, Belgium.
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30
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Wiessner M, Roos A, Munn CJ, Viswanathan R, Whyte T, Cox D, Schoser B, Sewry C, Roper H, Phadke R, Marini Bettolo C, Barresi R, Charlton R, Bönnemann CG, Abath Neto O, Reed UC, Zanoteli E, Araújo Martins Moreno C, Ertl-Wagner B, Stucka R, De Goede C, Borges da Silva T, Hathazi D, Dell’Aica M, Zahedi RP, Thiele S, Müller J, Kingston H, Müller S, Curtis E, Walter MC, Strom TM, Straub V, Bushby K, Muntoni F, Swan LE, Lochmüller H, Senderek J. Mutations in INPP5K, Encoding a Phosphoinositide 5-Phosphatase, Cause Congenital Muscular Dystrophy with Cataracts and Mild Cognitive Impairment. Am J Hum Genet 2017; 100:523-536. [PMID: 28190456 PMCID: PMC5339217 DOI: 10.1016/j.ajhg.2017.01.024] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 01/12/2017] [Indexed: 12/26/2022] Open
Abstract
Phosphoinositides are small phospholipids that control diverse cellular downstream signaling events. Their spatial and temporal availability is tightly regulated by a set of specific lipid kinases and phosphatases. Congenital muscular dystrophies are hereditary disorders characterized by hypotonia and weakness from birth with variable eye and central nervous system involvement. In individuals exhibiting congenital muscular dystrophy, early-onset cataracts, and mild intellectual disability but normal cranial magnetic resonance imaging, we identified bi-allelic mutations in INPP5K, encoding inositol polyphosphate-5-phosphatase K. Mutations impaired phosphatase activity toward the phosphoinositide phosphatidylinositol (4,5)-bisphosphate or altered the subcellular localization of INPP5K. Downregulation of INPP5K orthologs in zebrafish embryos disrupted muscle fiber morphology and resulted in abnormal eye development. These data link congenital muscular dystrophies to defective phosphoinositide 5-phosphatase activity that is becoming increasingly recognized for its role in mediating pivotal cellular mechanisms contributing to disease.
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31
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Osborn DPS, Pond HL, Mazaheri N, Dejardin J, Munn CJ, Mushref K, Cauley ES, Moroni I, Pasanisi MB, Sellars EA, Hill RS, Partlow JN, Willaert RK, Bharj J, Malamiri RA, Galehdari H, Shariati G, Maroofian R, Mora M, Swan LE, Voit T, Conti FJ, Jamshidi Y, Manzini MC. Mutations in INPP5K Cause a Form of Congenital Muscular Dystrophy Overlapping Marinesco-Sjögren Syndrome and Dystroglycanopathy. Am J Hum Genet 2017; 100:537-545. [PMID: 28190459 PMCID: PMC5339112 DOI: 10.1016/j.ajhg.2017.01.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 01/05/2017] [Indexed: 02/01/2023] Open
Abstract
Congenital muscular dystrophies display a wide phenotypic and genetic heterogeneity. The combination of clinical, biochemical, and molecular genetic findings must be considered to obtain the precise diagnosis and provide appropriate genetic counselling. Here we report five individuals from four families presenting with variable clinical features including muscular dystrophy with a reduction in dystroglycan glycosylation, short stature, intellectual disability, and cataracts, overlapping both the dystroglycanopathies and Marinesco-Sjögren syndrome. Whole-exome sequencing revealed homozygous missense and compound heterozygous mutations in INPP5K in the affected members of each family. INPP5K encodes the inositol polyphosphate-5-phosphatase K, also known as SKIP (skeletal muscle and kidney enriched inositol phosphatase), which is highly expressed in the brain and muscle. INPP5K localizes to both the endoplasmic reticulum and to actin ruffles in the cytoplasm. It has been shown to regulate myoblast differentiation and has also been implicated in protein processing through its interaction with the ER chaperone HSPA5/BiP. We show that morpholino-mediated inpp5k loss of function in the zebrafish results in shortened body axis, microphthalmia with disorganized lens, microcephaly, reduced touch-evoked motility, and highly disorganized myofibers. Altogether these data demonstrate that mutations in INPP5K cause a congenital muscular dystrophy syndrome with short stature, cataracts, and intellectual disability.
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Affiliation(s)
- Daniel P S Osborn
- Cardiovascular and Cell Sciences Institute, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Heather L Pond
- Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Science, Washington, DC 20037, USA
| | - Neda Mazaheri
- Department of Genetics, Shahid Chamran University of Ahvaz, Ahvaz 6135783151, Iran; Narges Medical Genetics and Prenatal Diagnosis Laboratory, East Mihan Ave., Kianpars, Ahvaz 6155689467, Iran
| | - Jeremy Dejardin
- Cardiovascular and Cell Sciences Institute, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Christopher J Munn
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, UK
| | - Khaloob Mushref
- Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Science, Washington, DC 20037, USA
| | - Edmund S Cauley
- Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Science, Washington, DC 20037, USA
| | - Isabella Moroni
- Pediatric Neurology Unit, Fondazione IRCCS Istituto Neurologico C. Besta, 20133 Milan, Italy
| | - Maria Barbara Pasanisi
- Pediatric Neurology Unit, Fondazione IRCCS Istituto Neurologico C. Besta, 20133 Milan, Italy; Division of Neuromuscular Diseases and Neuroimmunology, Fondazione IRCCS Istituto Neurologico C. Besta, 20126 Milan, Italy
| | - Elizabeth A Sellars
- Department of Pediatrics, Section of Genetics and Metabolism, University of Arkansas for Medical Sciences, Arkansas Children's Hospital, Little Rock, AR 72202, USA
| | - R Sean Hill
- Program in Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jennifer N Partlow
- Program in Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | | | - Jaipreet Bharj
- Cardiovascular and Cell Sciences Institute, St George's University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Reza Azizi Malamiri
- Department of Paediatric Neurology, Golestan Medical, Educational, and Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6163764648, Iran
| | - Hamid Galehdari
- Department of Genetics, Shahid Chamran University of Ahvaz, Ahvaz 6135783151, Iran; Narges Medical Genetics and Prenatal Diagnosis Laboratory, East Mihan Ave., Kianpars, Ahvaz 6155689467, Iran
| | - Gholamreza Shariati
- Narges Medical Genetics and Prenatal Diagnosis Laboratory, East Mihan Ave., Kianpars, Ahvaz 6155689467, Iran; Department of Medical Genetics, Faculty of Medicine, Ahvaz Jundishapur, University of Medical Sciences, Ahvaz 6135715794, Iran
| | - Reza Maroofian
- Cardiovascular and Cell Sciences Institute, St George's University of London, Cranmer Terrace, London SW17 0RE, UK; University of Exeter Medical School, RILD Wellcome Wolfson Centre, Royal Devon & Exeter NHS Foundation Trust, Exeter EX1 2LU, UK
| | - Marina Mora
- Division of Neuromuscular Diseases and Neuroimmunology, Fondazione IRCCS Istituto Neurologico C. Besta, 20126 Milan, Italy
| | - Laura E Swan
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool L69 3BX, UK
| | - Thomas Voit
- NIHR GOSH Biomedical Research Centre, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Francesco J Conti
- NIHR GOSH Biomedical Research Centre, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Yalda Jamshidi
- Cardiovascular and Cell Sciences Institute, St George's University of London, Cranmer Terrace, London SW17 0RE, UK.
| | - M Chiara Manzini
- Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Science, Washington, DC 20037, USA.
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Regulation of PI3K effector signalling in cancer by the phosphoinositide phosphatases. Biosci Rep 2017; 37:BSR20160432. [PMID: 28082369 PMCID: PMC5301276 DOI: 10.1042/bsr20160432] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 12/24/2022] Open
Abstract
Class I phosphoinositide 3-kinase (PI3K) generates phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) at the plasma membrane in response to growth factors, activating a signalling cascade that regulates many cellular functions including cell growth, proliferation, survival, migration and metabolism. The PI3K pathway is commonly dysregulated in human cancer, and drives tumorigenesis by promoting aberrant cell growth and transformation. PtdIns(3,4,5)P3 facilitates the activation of many pleckstrin homology (PH) domain-containing proteins including the serine/threonine kinase AKT. There are three AKT isoforms that are frequently hyperactivated in cancer through mutation, amplification or dysregulation of upstream regulatory proteins. AKT isoforms have converging and opposing functions in tumorigenesis. PtdIns(3,4,5)P3 signalling is degraded and terminated by phosphoinositide phosphatases such as phosphatase and tensin homologue (PTEN), proline-rich inositol polyphosphate 5-phosphatase (PIPP) (INPP5J) and inositol polyphosphate 4-phosphatase type II (INPP4B). PtdIns(3,4,5)P3 is rapidly hydrolysed by PIPP to generate phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P2), which is further hydrolysed by INPP4B to form phosphatidylinositol 3-phosphate (PtdIns3P). PtdIns(3,4)P2 and PtdIns3P are also important signalling molecules; PtdIns(3,4)P2 together with PtdIns(3,4,5)P3 are required for maximal AKT activation and PtdIns3P activates PI3K-dependent serum and glucocorticoid-regulated kinase (SGK3) signalling. Loss of Pten, Pipp or Inpp4b expression or function promotes tumour growth in murine cancer models through enhanced AKT isoform-specific signalling. INPP4B inhibits PtdIns(3,4)P2-mediated AKT activation in breast and prostate cancer; however, INPP4B expression is increased in acute myeloid leukaemia (AML), melanoma and colon cancer where it paradoxically promotes cell proliferation, transformation and/or drug resistance. This review will discuss how PTEN, PIPP and INPP4B distinctly regulate PtdIns(3,4,5)P3 signalling downstream of PI3K and how dysregulation of these phosphatases affects cancer outcomes.
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Thurston TL, Boyle KB, Allen M, Ravenhill BJ, Karpiyevich M, Bloor S, Kaul A, Noad J, Foeglein A, Matthews SA, Komander D, Bycroft M, Randow F. Recruitment of TBK1 to cytosol-invading Salmonella induces WIPI2-dependent antibacterial autophagy. EMBO J 2016; 35:1779-92. [PMID: 27370208 PMCID: PMC5010046 DOI: 10.15252/embj.201694491] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 05/24/2016] [Indexed: 01/01/2023] Open
Abstract
Mammalian cells deploy autophagy to defend their cytosol against bacterial invaders. Anti‐bacterial autophagy relies on the core autophagy machinery, cargo receptors, and “eat‐me” signals such as galectin‐8 and ubiquitin that label bacteria as autophagy cargo. Anti‐bacterial autophagy also requires the kinase TBK1, whose role in autophagy has remained enigmatic. Here we show that recruitment of WIPI2, itself essential for anti‐bacterial autophagy, is dependent on the localization of catalytically active TBK1 to the vicinity of cytosolic bacteria. Experimental manipulation of TBK1 recruitment revealed that engagement of TBK1 with any of a variety of Salmonella‐associated “eat‐me” signals, including host‐derived glycans and K48‐ and K63‐linked ubiquitin chains, suffices to restrict bacterial proliferation. Promiscuity in recruiting TBK1 via independent signals may buffer TBK1 functionality from potential bacterial antagonism and thus be of evolutionary advantage to the host.
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Affiliation(s)
- Teresa Lm Thurston
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
| | - Keith B Boyle
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Mark Allen
- Division of Structural Studies, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Benjamin J Ravenhill
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Maryia Karpiyevich
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Stuart Bloor
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Annie Kaul
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Jessica Noad
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Agnes Foeglein
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Sophie A Matthews
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
| | - David Komander
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Mark Bycroft
- Division of Structural Studies, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Felix Randow
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
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Naguib A. Following the trail of lipids: Signals initiated by PI3K function at multiple cellular membranes. Sci Signal 2016; 9:re4. [DOI: 10.1126/scisignal.aad7885] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Ijuin T, Hatano N, Takenawa T. Glucose-regulated protein 78 (GRP78) binds directly to PIP3 phosphatase SKIP and determines its localization. Genes Cells 2016; 21:457-65. [PMID: 26940976 DOI: 10.1111/gtc.12353] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 01/31/2016] [Indexed: 11/29/2022]
Abstract
Skeletal muscle and kidney-enriched inositol polyphosphate phosphatase (SKIP), a PIP3 phosphatase, has been implicated in the regulation of insulin signaling in skeletal muscle. SKIP interacts with Pak1 and glucose-regulated protein 78 (GRP78), both of which are necessary for the regulation of insulin signaling. In this study, we showed that GRP78 directly binds to the SKIP C-terminal homology (SKICH) domain of SKIP and that this binding is necessary for the localization of SKIP at the ER. In addition, in vitro binding analysis showed that GRP78 and Pak1 competitively bind to SKIP. Taken together, these findings suggest a model by which GRP78 regulates intracellular localization of SKIP and how SKIP binds to Pak1 on insulin stimulation.
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Affiliation(s)
- Takeshi Ijuin
- Division of Biochemistry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki Chu-o, Kobe, 650-0017, Japan
| | - Naoya Hatano
- The Integrated Center for Mass Spectrometry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki Chu-o, Kobe, 650-0017, Japan
| | - Tadaomi Takenawa
- Division of Membrane Biology, Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan
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Regulation of PtdIns(3,4,5)P3/Akt signalling by inositol polyphosphate 5-phosphatases. Biochem Soc Trans 2016; 44:240-52. [DOI: 10.1042/bst20150214] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The phosphoinositide 3-kinase (PI3K) generated lipid signals, PtdIns(3,4,5)P3 and PtdIns(3,4)P2, are both required for the maximal activation of the serine/threonine kinase proto-oncogene Akt. The inositol polyphosphate 5-phosphatases (5-phosphatases) hydrolyse the 5-position phosphate from the inositol head group of PtdIns(3,4,5)P3 to yield PtdIns(3,4)P2. Extensive work has revealed several 5-phosphatases inhibit PI3K-driven Akt signalling, by decreasing PtdIns(3,4,5)P3 despite increasing cellular levels of PtdIns(3,4)P2. The roles that 5-phosphatases play in suppressing cell proliferation and transformation are slow to emerge; however, the 5-phosphatase PIPP [proline-rich inositol polyphosphate 5-phosphatase; inositol polyphosphate 5-phosphatase (INPP5J)] has recently been identified as a putative tumour suppressor in melanoma and breast cancer and SHIP1 [SH2 (Src homology 2)-containing inositol phosphatase 1] inhibits haematopoietic cell proliferation. INPP5E regulates cilia stability and INPP5E mutations have been implicated ciliopathy syndromes. This review will examine 5-phosphatase regulation of PI3K/Akt signalling, focussing on the role PtdIns(3,4,5)P3 5-phosphatases play in developmental diseases and cancer.
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Piscatelli HL, Li M, Zhou D. Dual 4- and 5-phosphatase activities regulate SopB-dependent phosphoinositide dynamics to promote bacterial entry. Cell Microbiol 2015; 18:705-19. [PMID: 26537021 DOI: 10.1111/cmi.12542] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 10/21/2015] [Accepted: 10/24/2015] [Indexed: 12/16/2022]
Abstract
Salmonella are able to invade non-phagocytic cells such as intestinal epithelial cells by modulating the host actin cytoskeleton to produce membrane ruffles. Two type III effector proteins SopB and SopE play key roles to this modulation. SopE is a known guanine nucleotide exchange factor (GEF) capable of activating Rac1 and CDC42. SopB is a phosphatidylinositol 4-phosphatase and 5-phosphatase promoting membrane ruffles and invasion of Salmonella through undefined mechanisms. Previous studies have demonstrated that the 4-phosphatase activity of SopB is required for PtdIns-3-phosphate (PtdIns(3)P) accumulation and SopB-mediated invasion. We show here that both the 4-phosphatase as well as the 5-phosphatase activities of SopB are essential in ruffle formation and subsequent invasion. We found that the 5-phosphatase activity of SopB is likely responsible for generating PtdIns-3,4-bisphosphate (PtdIns(3,4)P(2)) and subsequent recruitment of sorting nexin 9 (SNX9), an actin modulating protein. Intriguingly, the 4-phosphatase activity is responsible for the dephosphorylation of PtdIns(3,4)P(2) into PtdIns(3)P. Alone, neither activity is sufficient for ruffling but when acting in conjunction with one another, the 4-phosphatase and 5-phosphatase activities led to SNX9-mediated ruffling and Salmonella invasion. This work reveals the unique ability of bacterial effector protein SopB to utilize both its 4- and 5-phosphatase activities to regulate phosphoinositide dynamics to promote bacterial entry.
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Affiliation(s)
- Heather L Piscatelli
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Menghan Li
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Daoguo Zhou
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
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Ijuin T, Hatano N, Hosooka T, Takenawa T. Regulation of insulin signaling in skeletal muscle by PIP3 phosphatase, SKIP, and endoplasmic reticulum molecular chaperone glucose-regulated protein 78. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:3192-201. [DOI: 10.1016/j.bbamcr.2015.09.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 09/08/2015] [Accepted: 09/10/2015] [Indexed: 12/30/2022]
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Phosphatidylinositol 3,4,5-Trisphosphate Phosphatase SKIP Links Endoplasmic Reticulum Stress in Skeletal Muscle to Insulin Resistance. Mol Cell Biol 2015; 36:108-18. [PMID: 26483413 DOI: 10.1128/mcb.00921-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 10/06/2015] [Indexed: 11/20/2022] Open
Abstract
Insulin resistance is critical in the pathogenesis of type 2 diabetes. Endoplasmic reticulum (ER) stress in liver and adipose tissues plays an important role in the development of insulin resistance. Although skeletal muscle is a primary site for insulin-dependent glucose disposal, it is unclear if ER stress in those tissues contributes to insulin resistance. In this study, we show that skeletal muscle kidney-enriched inositol polyphosphate phosphatase (SKIP), a PIP3 (phosphatidylinositol-3,4,5-trisphosphate) phosphatase, links ER stress to insulin resistance in skeletal muscle. SKIP expression was increased due to ER stress and was higher in the skeletal muscle isolated from high-fat-diet-fed mice and db/db mice than in that from wild-type mice. Mechanistically, ER stress promotes activating transcription factor 6 (ATF6) and X-box binding protein 1 (XBP1)-dependent expression of SKIP. These findings underscore the specific and prominent role of SKIP in the development of insulin resistance in skeletal muscle.
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40
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Rudge SA, Wakelam MJO. Phosphatidylinositolphosphate phosphatase activities and cancer. J Lipid Res 2015; 57:176-92. [PMID: 26302980 DOI: 10.1194/jlr.r059154] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Indexed: 12/13/2022] Open
Abstract
Signaling through the phosphoinositide 3-kinase pathways mediates the actions of a plethora of hormones, growth factors, cytokines, and neurotransmitters upon their target cells following receptor occupation. Overactivation of these pathways has been implicated in a number of pathologies, in particular a range of malignancies. The tight regulation of signaling pathways necessitates the involvement of both stimulatory and terminating enzymes; inappropriate activation of a pathway can thus result from activation or inhibition of the two signaling arms. The focus of this review is to discuss, in detail, the activities of the identified families of phosphoinositide phosphatase expressed in humans, and how they regulate the levels of phosphoinositides implicated in promoting malignancy.
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Affiliation(s)
- Simon A Rudge
- Signalling Programme, Babraham Institute, Cambridge CB22 3AT, United Kingdom
| | - Michael J O Wakelam
- Signalling Programme, Babraham Institute, Cambridge CB22 3AT, United Kingdom
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41
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Ijuin T, Takenawa T. Improvement of insulin signaling in myoblast cells by an addition of SKIP-binding peptide within Pak1 kinase domain. Biochem Biophys Res Commun 2015; 456:41-6. [DOI: 10.1016/j.bbrc.2014.11.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 11/11/2014] [Indexed: 12/26/2022]
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42
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Hsu F, Mao Y. The structure of phosphoinositide phosphatases: Insights into substrate specificity and catalysis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:698-710. [PMID: 25264170 DOI: 10.1016/j.bbalip.2014.09.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 09/10/2014] [Accepted: 09/17/2014] [Indexed: 12/17/2022]
Abstract
Phosphoinositides (PIs) are a group of key signaling and structural lipid molecules involved in a myriad of cellular processes. PI phosphatases, together with PI kinases, are responsible for the conversion of PIs between distinctive phosphorylation states. PI phosphatases are a large collection of enzymes that are evolved from at least two disparate ancestors. One group is distantly related to endonucleases, which apply divalent metal ions for phosphoryl transfer. The other group is related to protein tyrosine phosphatases, which contain a highly conserved active site motif Cys-X5-Arg (CX5R). In this review, we focus on structural insights to illustrate current understandings of the molecular mechanisms of each PI phosphatase family, with emphasis on their structural basis for substrate specificity determinants and catalytic mechanisms. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- FoSheng Hsu
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Yuxin Mao
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
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43
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Differential SKIP expression in PTEN-deficient glioblastoma regulates cellular proliferation and migration. Oncogene 2014; 34:3711-27. [DOI: 10.1038/onc.2014.303] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 07/18/2014] [Accepted: 08/13/2014] [Indexed: 12/25/2022]
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44
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Yang Y, Wang G, Huang X, Du Z. Crystallographic and modelling studies suggest that the SKICH domains from different protein families share a common Ig-like fold but harbour substantial structural variations. J Biomol Struct Dyn 2014; 33:1385-98. [PMID: 25187058 DOI: 10.1080/07391102.2014.951688] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
TAX1BP1 is a pleiotropic multi-domain protein involved in many important biological processes such as signal transduction, cell growth and apoptosis, transcriptional coactivation, membrane trafficking, neurotransmission and autophagy. The N-terminus of TAX1BP1 contains a SKICH domain implicated in autophagy. SKICH domains are also present in four other proteins including NDP52, CALCOCO1, SKIP and PIPP. The SKICH domains of SKIP and PIPP mediate plasma membrane localisation. The functions of the SKICH domains of NDP52 and CALCOCO1 are not known. Here we report the crystal structure of the TAX1BP1 SKICH domain, which has an Ig-like fold similar to the NDP52 SKICH domain. Extensive pairwise and clustered aromatic π-stacking interactions are present in the TAX1BP1 SKICH domain. The aromatic residues mediating these interactions can be classified into four groups with varying degrees of conservation among different protein families. The interactions mediated by highly conserved residues are found in the interior and one outward face of the Ig-like β-barrel, representing common structural features of the SKICH domains. Three TAX1BP1-specific pairwise interactions locate in the loop regions, each augmented by a proline-aromatic interaction. The three proline-aromatic clusters are linked together by more generic hydrophobic interactions, forming a unique hydrophobic surface at one end of the TAX1BP1 SKICH domain. The structures and homologous models of SKICH domains from different proteins reveal substantial differences in electrostatic surface properties of the domains. Together with existing biochemical data, results from the structural study suggest that an intact SKICH domain is required for the autophagy function of TAX1BP1.
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Affiliation(s)
- Yang Yang
- a Department of Chemistry and Biochemistry , Southern Illinois University , Carbondale 62901 , IL , USA
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45
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Abstract
The specific interaction of phosphoinositides with proteins is critical for a plethora of cellular processes, including cytoskeleton remodelling, mitogenic signalling, ion channel regulation and membrane traffic. The spatiotemporal restriction of different phosphoinositide species helps to define compartments within the cell, and this is particularly important for membrane trafficking within both the secretory and endocytic pathways. Phosphoinositide homoeostasis is tightly regulated by a large number of inositol kinases and phosphatases, which respectively phosphorylate and dephosphorylate distinct phosphoinositide species. Many of these enzymes have been implicated in regulating membrane trafficking and, accordingly, their dysregulation has been linked to a number of human diseases. In the present review, we focus on the inositol phosphatases, concentrating on their roles in membrane trafficking and the human diseases with which they have been associated.
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46
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Yang Y, Wang G, Huang X, Du Z. Expression, purification and crystallization of the SKICH domain of human TAX1BP1. Acta Crystallogr F Struct Biol Commun 2014; 70:619-23. [PMID: 24817723 PMCID: PMC4014332 DOI: 10.1107/s2053230x14006396] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 03/22/2014] [Indexed: 01/12/2023] Open
Abstract
TAX1BP1 is a highly conserved, pleiotropic protein that plays many essential functions in human cells, including negative regulation of inflammatory and antimicrobial responses mediated by NF-κB and IRF3 signaling, inhibition of apoptosis, transcriptional coactivation and autophagy etc. TAX1BP1 contains a SKICH domain at the N-terminus, three coiled-coil domains in the middle and two ubiquitin-binding zinc-finger motifs at the C-terminus. The SKICH domain and the linker sequence between the SKICH domain and the coiled-coil region mediate interaction with ubiquitin-like proteins of the LC3/GABARAP family, which are autophagosome markers. For structure determination of the SKICH domain of TAX1BP1, a protein construct (amino acids 15-148) corresponding to the SKICH domain plus the linker region was expressed, purified and crystallized. A native diffraction data set has been collected to 1.9 Å resolution. A molecular-replacement solution has been found by using the structure of the SKICH domain of NDP52, a paralog of TAX1BP1.
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Affiliation(s)
- Yang Yang
- Department of Chemistry and Biochemistry, Southern Illinois University, 1245 Lincoln Drive, Carbondale, IL 62901, USA
| | - Guan Wang
- Department of Chemistry and Biochemistry, Southern Illinois University, 1245 Lincoln Drive, Carbondale, IL 62901, USA
| | - Xiaolan Huang
- Department of Computer Science, Southern Illinois University, 1245 Lincoln Drive, Carbondale, IL 62901, USA
| | - Zhihua Du
- Department of Chemistry and Biochemistry, Southern Illinois University, 1245 Lincoln Drive, Carbondale, IL 62901, USA
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47
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PtdIns(4)P signalling and recognition systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 991:59-83. [PMID: 23775691 DOI: 10.1007/978-94-007-6331-9_5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The Golgi apparatus is a sorting platform that exchanges extensively with the endoplasmic reticulum (ER), endosomes (Es) and plasma membrane (PM) compartments. The last compartment of the Golgi, the trans-Golgi Network (TGN) is a large complex of highly deformed membranes from which vesicles depart to their targeted organelles but also are harbored from retrograde pathways. The phosphoinositide (PI) composition of the TGN is marked by an important contingent of phosphatidylinositol-4-phosphate (PtdIns(4)P). Although this PI is present throughout the Golgi, its proportion grows along the successive cisternae and peaks at the TGN. The levels of this phospholipid are controlled by a set of kinases and phosphatases that regulate its concentrations in the Golgi and maintain a dynamic gradient that determines the cellular localization of several interacting proteins. Though not exclusive to the Golgi, the synthesis of PtdIns(4)P in other membranes is relatively marginal and has unclear consequences. The significance of PtdIns(4)P within the TGN has been demonstrated for numerous cellular events such as vesicle formation, lipid metabolism, and membrane trafficking.
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48
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Ceregido MA, Spínola Amilibia M, Buts L, Rivera-Torres J, Garcia-Pino A, Bravo J, van Nuland NAJ. The structure of TAX1BP1 UBZ1+2 provides insight into target specificity and adaptability. J Mol Biol 2013; 426:674-90. [PMID: 24239949 DOI: 10.1016/j.jmb.2013.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 11/01/2013] [Accepted: 11/07/2013] [Indexed: 10/26/2022]
Abstract
TAX1BP1 is a novel ubiquitin-binding adaptor protein involved in the negative regulation of the NF-kappaB transcription factor, which is a key player in inflammatory responses, immunity and tumorigenesis. TAX1BP1 recruits A20 to the ubiquitinated signaling proteins TRAF6 and RIP1, leading to their A20-mediated deubiquitination and the disruption of IL-1-induced and TNF-induced NF-kappaB signaling, respectively. The two zinc fingers localized at its C-terminus function as novel ubiquitin-binding domains (UBZ, ubiquitin-binding zinc finger). Here we present for the first time both the solution and crystal structures of two classical UBZ domains in tandem within the human TAX1BP1. The relative orientation of the two domains is slightly different in the X-ray structure with respect to the NMR structure, indicating some degree of conformational flexibility, which is rationalized by NMR relaxation data. The observed degree of flexibility and stability between the two UBZ domains might have consequences on the recognition mechanism of interacting partners.
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Affiliation(s)
- M Angeles Ceregido
- Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, Granada 18071, Spain; Jean Jeener NMR Centre, Structural Biology Brussels, Vrije Universiteit Brussel, Brussels 1050, Belgium; Molecular Recognition Unit, Department of Structural Biology, VIB, Brussels 1050, Belgium
| | - Mercedes Spínola Amilibia
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Cientificas, Valencia 46010, Spain; Departamento de Biología Físico-Química, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Cientificas, Madrid 28040, Spain
| | - Lieven Buts
- Jean Jeener NMR Centre, Structural Biology Brussels, Vrije Universiteit Brussel, Brussels 1050, Belgium; Molecular Recognition Unit, Department of Structural Biology, VIB, Brussels 1050, Belgium
| | - José Rivera-Torres
- Department of Epidemiology, Atherothrombosis and Imaging, Spanish National Cardiovascular Research Center, Madrid 28029, Spain
| | - Abel Garcia-Pino
- Jean Jeener NMR Centre, Structural Biology Brussels, Vrije Universiteit Brussel, Brussels 1050, Belgium; Molecular Recognition Unit, Department of Structural Biology, VIB, Brussels 1050, Belgium
| | - Jerónimo Bravo
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Cientificas, Valencia 46010, Spain.
| | - Nico A J van Nuland
- Jean Jeener NMR Centre, Structural Biology Brussels, Vrije Universiteit Brussel, Brussels 1050, Belgium; Molecular Recognition Unit, Department of Structural Biology, VIB, Brussels 1050, Belgium.
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Abstract
Phosphoinositides (PIs) make up only a small fraction of cellular phospholipids, yet they control almost all aspects of a cell's life and death. These lipids gained tremendous research interest as plasma membrane signaling molecules when discovered in the 1970s and 1980s. Research in the last 15 years has added a wide range of biological processes regulated by PIs, turning these lipids into one of the most universal signaling entities in eukaryotic cells. PIs control organelle biology by regulating vesicular trafficking, but they also modulate lipid distribution and metabolism via their close relationship with lipid transfer proteins. PIs regulate ion channels, pumps, and transporters and control both endocytic and exocytic processes. The nuclear phosphoinositides have grown from being an epiphenomenon to a research area of its own. As expected from such pleiotropic regulators, derangements of phosphoinositide metabolism are responsible for a number of human diseases ranging from rare genetic disorders to the most common ones such as cancer, obesity, and diabetes. Moreover, it is increasingly evident that a number of infectious agents hijack the PI regulatory systems of host cells for their intracellular movements, replication, and assembly. As a result, PI converting enzymes began to be noticed by pharmaceutical companies as potential therapeutic targets. This review is an attempt to give an overview of this enormous research field focusing on major developments in diverse areas of basic science linked to cellular physiology and disease.
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Affiliation(s)
- Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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50
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Abstract
Phosphoinositide signalling molecules interact with a plethora of effector proteins to regulate cell proliferation and survival, vesicular trafficking, metabolism, actin dynamics and many other cellular functions. The generation of specific phosphoinositide species is achieved by the activity of phosphoinositide kinases and phosphatases, which phosphorylate and dephosphorylate, respectively, the inositol headgroup of phosphoinositide molecules. The phosphoinositide phosphatases can be classified as 3-, 4- and 5-phosphatases based on their specificity for dephosphorylating phosphates from specific positions on the inositol head group. The SAC phosphatases show less specificity for the position of the phosphate on the inositol ring. The phosphoinositide phosphatases regulate PI3K/Akt signalling, insulin signalling, endocytosis, vesicle trafficking, cell migration, proliferation and apoptosis. Mouse knockout models of several of the phosphoinositide phosphatases have revealed significant physiological roles for these enzymes, including the regulation of embryonic development, fertility, neurological function, the immune system and insulin sensitivity. Importantly, several phosphoinositide phosphatases have been directly associated with a range of human diseases. Genetic mutations in the 5-phosphatase INPP5E are causative of the ciliopathy syndromes Joubert and MORM, and mutations in the 5-phosphatase OCRL result in Lowe's syndrome and Dent 2 disease. Additionally, polymorphisms in the 5-phosphatase SHIP2 confer diabetes susceptibility in specific populations, whereas reduced protein expression of SHIP1 is reported in several human leukaemias. The 4-phosphatase, INPP4B, has recently been identified as a tumour suppressor in human breast and prostate cancer. Mutations in one SAC phosphatase, SAC3/FIG4, results in the degenerative neuropathy, Charcot-Marie-Tooth disease. Indeed, an understanding of the precise functions of phosphoinositide phosphatases is not only important in the context of normal human physiology, but to reveal the mechanisms by which these enzyme families are implicated in an increasing repertoire of human diseases.
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