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Rameh LE, Blind RD. 25 Years of PI5P. Front Cell Dev Biol 2023; 11:1272911. [PMID: 37849742 PMCID: PMC10577294 DOI: 10.3389/fcell.2023.1272911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 09/18/2023] [Indexed: 10/19/2023] Open
Abstract
The accidental discovery of PI5P (phosphatidylinositol-5-phosphate) was published 25 years ago, when PIP5K type II (phosphoinositide-4-phosphate 5-kinase) was shown to actually be a 4-kinase that uses PI5P as a substrate to generate PI(4,5)P2. Consequently, PIP5K type II was renamed to PI5P4K, or PIP4K for short, and PI5P became the last of the 7 signaling phosphoinositides to be discovered. Much of what we know about PI5P comes from genetic studies of PIP4K, as the pathways for PI5P synthesis, the downstream targets of PI5P and how PI5P affects cellular function all remain largely enigmatic. Nevertheless, PI5P and PI5P-dependent PI(4,5)P2 synthesis have been clearly implicated in metabolic homeostasis and in diseases such as cancer. Here, we review the past 25 years of PI5P research, with particular emphasis on the impact this small signaling lipid has on human health.
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Affiliation(s)
- Lucia E. Rameh
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Raymond D. Blind
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, United States
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2
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Karabiyik C, Rubinsztein DC. Protocol for determining the regulation of lipid kinases and changes in phospholipids in vitro. STAR Protoc 2021; 2:100926. [PMID: 34766030 PMCID: PMC8571518 DOI: 10.1016/j.xpro.2021.100926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The regulation of lipid kinases has remained elusive given the difficulties of assessing changes in lipid levels. Here, we describe the isolation of protein and lipid kinases to determine the regulation of lipid kinases in vitro. This can be followed by analysis of effects of regulators on lipid kinase-mediated changes in phospholipids without the use of radioactivity, with a specific focus on PI(5)P generation by the enzyme PIKfyve. For complete details on the use and execution of this protocol, please refer to Karabiyik et al. (2021).
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Affiliation(s)
- Cansu Karabiyik
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
- UK Dementia Research Institute, Cambridge, UK
- Mortimer B. Zuckerman Mind Brain and Behavior Institute, Columbia University, 3227 Broadway, Manhattan, NY 10027, USA
| | - David C. Rubinsztein
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
- UK Dementia Research Institute, Cambridge, UK
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Saffi GT, Tang E, Mamand S, Inpanathan S, Fountain A, Salmena L, Botelho RJ. Reactive oxygen species prevent lysosome coalescence during PIKfyve inhibition. PLoS One 2021; 16:e0259313. [PMID: 34813622 PMCID: PMC8610251 DOI: 10.1371/journal.pone.0259313] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 10/16/2021] [Indexed: 11/19/2022] Open
Abstract
Lysosomes are terminal, degradative organelles of the endosomal pathway that undergo repeated fusion-fission cycles with themselves, endosomes, phagosomes, and autophagosomes. Lysosome number and size depends on balanced fusion and fission rates. Thus, conditions that favour fusion over fission can reduce lysosome numbers while enlarging their size. Conversely, favouring fission over fusion may cause lysosome fragmentation and increase their numbers. PIKfyve is a phosphoinositide kinase that generates phosphatidylinositol-3,5-bisphosphate to modulate lysosomal functions. PIKfyve inhibition causes an increase in lysosome size and reduction in lysosome number, consistent with lysosome coalescence. This is thought to proceed through reduced lysosome reformation and/or fission after fusion with endosomes or other lysosomes. Previously, we observed that photo-damage during live-cell imaging prevented lysosome coalescence during PIKfyve inhibition. Thus, we postulated that lysosome fusion and/or fission dynamics are affected by reactive oxygen species (ROS). Here, we show that ROS generated by various independent mechanisms all impaired lysosome coalescence during PIKfyve inhibition and promoted lysosome fragmentation during PIKfyve re-activation. However, depending on the ROS species or mode of production, lysosome dynamics were affected distinctly. H2O2 impaired lysosome motility and reduced lysosome fusion with phagosomes, suggesting that H2O2 reduces lysosome fusogenecity. In comparison, inhibitors of oxidative phosphorylation, thiol groups, glutathione, or thioredoxin, did not impair lysosome motility but instead promoted clearance of actin puncta on lysosomes formed during PIKfyve inhibition. Additionally, actin depolymerizing agents prevented lysosome coalescence during PIKfyve inhibition. Thus, we discovered that ROS can generally prevent lysosome coalescence during PIKfyve inhibition using distinct mechanisms depending on the type of ROS.
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Affiliation(s)
- Golam T. Saffi
- Molecular Science Graduate Program, Ryerson University, Toronto, Ontario, Canada
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
- Department of Pharmacology & Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Evan Tang
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Sami Mamand
- Molecular Science Graduate Program, Ryerson University, Toronto, Ontario, Canada
- Polytechnic Research Center, Erbil Polytechnic University, Kurdistan Regional Government, Erbil, Kurdistan
| | - Subothan Inpanathan
- Molecular Science Graduate Program, Ryerson University, Toronto, Ontario, Canada
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Aaron Fountain
- Molecular Science Graduate Program, Ryerson University, Toronto, Ontario, Canada
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Leonardo Salmena
- Department of Pharmacology & Toxicology, University of Toronto, Toronto, Ontario, Canada
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Roberto J. Botelho
- Molecular Science Graduate Program, Ryerson University, Toronto, Ontario, Canada
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
- * E-mail:
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Steinfeld N, Giridharan SSP, Kauffman EJ, Weisman LS. Simultaneous Detection of Phosphoinositide Lipids by Radioactive Metabolic Labeling. Methods Mol Biol 2021; 2251:1-17. [PMID: 33481228 PMCID: PMC8059495 DOI: 10.1007/978-1-0716-1142-5_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Phosphoinositide (PPI) lipids are a crucial class of low-abundance signaling molecules that regulate many processes within cells. Methods that enable simultaneous detection of all PPI lipid species provide a wholistic snapshot of the PPI profile of cells, which is critical for probing PPI biology. Here we describe a method for the simultaneous measurement of cellular PPI levels by metabolically labeling yeast or mammalian cells with myo-3H-inositol, extracting radiolabeled glycerophosphoinositides, and separating lipid species on an anion exchange column via HPLC.
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Affiliation(s)
- Noah Steinfeld
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI, USA
| | | | - Emily J Kauffman
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Lois S Weisman
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA.
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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Mohamed M, Gardeitchik T, Balasubramaniam S, Guerrero‐Castillo S, Dalloyaux D, van Kraaij S, Venselaar H, Hoischen A, Urban Z, Brandt U, Al‐Shawi R, Simons JP, Frison M, Ngu L, Callewaert B, Spelbrink H, Kallemeijn WW, Aerts JMFG, Waugh MG, Morava E, Wevers RA. Novel defect in phosphatidylinositol 4-kinase type 2-alpha (PI4K2A) at the membrane-enzyme interface is associated with metabolic cutis laxa. J Inherit Metab Dis 2020; 43:1382-1391. [PMID: 32418222 PMCID: PMC7687218 DOI: 10.1002/jimd.12255] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 05/11/2020] [Accepted: 05/13/2020] [Indexed: 12/16/2022]
Abstract
Inherited cutis laxa, or inelastic, sagging skin is a genetic condition of premature and generalised connective tissue ageing, affecting various elastic components of the extracellular matrix. Several cutis laxa syndromes are inborn errors of metabolism and lead to severe neurological symptoms. In a patient with cutis laxa, a choreoathetoid movement disorder, dysmorphic features and intellectual disability we performed exome sequencing to elucidate the underlying genetic defect. We identified the amino acid substitution R275W in phosphatidylinositol 4-kinase type IIα, caused by a homozygous missense mutation in the PI4K2A gene. We used lipidomics, complexome profiling and functional studies to measure phosphatidylinositol 4-phosphate synthesis in the patient and evaluated PI4K2A deficient mice to define a novel metabolic disorder. The R275W residue, located on the surface of the protein, is involved in forming electrostatic interactions with the membrane. The catalytic activity of PI4K2A in patient fibroblasts was severely reduced and lipid mass spectrometry showed that particular acyl-chain pools of PI4P and PI(4,5)P2 were decreased. Phosphoinositide lipids play a major role in intracellular signalling and trafficking and regulate the balance between proliferation and apoptosis. Phosphatidylinositol 4-kinases such as PI4K2A mediate the first step in the main metabolic pathway that generates PI4P, PI(4,5)P2 and PI(3,4,5)P3 . Although neurologic involvement is common, cutis laxa has not been reported previously in metabolic defects affecting signalling. Here we describe a patient with a complex neurological phenotype, premature ageing and a mutation in PI4K2A, illustrating the importance of this enzyme in the generation of inositol lipids with particular acylation characteristics.
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Affiliation(s)
- Miski Mohamed
- Department of PaediatricsRadboud University Medical CenterNijmegenThe Netherlands
| | - Thatjana Gardeitchik
- Department of PaediatricsRadboud University Medical CenterNijmegenThe Netherlands
- Department of GeneticsRadboud University Medical CenterNijmegenThe Netherlands
| | - Shanti Balasubramaniam
- Clinical Genetic DepartmentHospital Kuala Lumpur, Jalan PahangKuala LumpurMalaysia
- Discipline of Genetic Medicine, Sydney Medical SchoolUniversity of SydneySydneyNew South WalesAustralia
- Western Sydney Genetics ProgramThe Children's Hospital at WestmeadSydneyNew South WalesAustralia
| | - Sergio Guerrero‐Castillo
- Radboud Center for Mitochondrial MedicineRadboud University Medical CenterNijmegenThe Netherlands
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CenterNijmegenThe Netherlands
| | - Daisy Dalloyaux
- Department of PaediatricsRadboud University Medical CenterNijmegenThe Netherlands
| | - Sanne van Kraaij
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CenterNijmegenThe Netherlands
| | - Hanka Venselaar
- Center of Molecular and Biomolecular InformaticsRadboud University Medical CenterNijmegenThe Netherlands
| | - Alexander Hoischen
- Department of GeneticsRadboud University Medical CenterNijmegenThe Netherlands
- Department of Internal MedicineRadboud University Medical CenterNijmegenThe Netherlands
- Radboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Zsolt Urban
- Department of Human Genetics, Graduate School of Public HealthUniversity of PittsburghPittsburghPennsylvaniaUSA
| | - Ulrich Brandt
- Radboud Center for Mitochondrial MedicineRadboud University Medical CenterNijmegenThe Netherlands
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CenterNijmegenThe Netherlands
| | - Raya Al‐Shawi
- Wolfson Drug Discovery Unit, Division of Medicine, Royal Free CampusUniversity College LondonLondonUK
| | - J. Paul Simons
- Wolfson Drug Discovery Unit, Division of Medicine, Royal Free CampusUniversity College LondonLondonUK
| | - Michele Frison
- Wolfson Drug Discovery Unit, Division of Medicine, Royal Free CampusUniversity College LondonLondonUK
| | - Lock‐Hock Ngu
- Clinical Genetic DepartmentHospital Kuala Lumpur, Jalan PahangKuala LumpurMalaysia
| | - Bert Callewaert
- Center for Medical GeneticsGhent University HospitalGhentBelgium
| | - Hans Spelbrink
- Department of PaediatricsRadboud University Medical CenterNijmegenThe Netherlands
| | - Wouter W. Kallemeijn
- Department of Medical Biochemistry, Leiden Institute of ChemistryLeiden UniversityLeidenThe Netherlands
- Department of ChemistryImperial College LondonLondonUK
| | - Johannes M. F. G. Aerts
- Department of Medical Biochemistry, Leiden Institute of ChemistryLeiden UniversityLeidenThe Netherlands
| | - Mark G. Waugh
- Lipid and Membrane Biology Group, Institute for Liver & Digestive HealthUniversity College LondonLondonUK
| | - Eva Morava
- Haywards Genetics CenterTulane UniversityNew OrleansLouisianaUSA
- Department of PediatricsUniversity Medical CentreLeuvenBelgium
| | - Ron A. Wevers
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CenterNijmegenThe Netherlands
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Kolakowski D, Kaminska J, Zoladek T. The binding of the APT1 domains to phosphoinositides is regulated by metal ions in vitro. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183349. [PMID: 32407779 DOI: 10.1016/j.bbamem.2020.183349] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/27/2020] [Accepted: 05/07/2020] [Indexed: 01/01/2023]
Abstract
Chorein is a protein of the Vps13 family, and defects in this protein cause the rare neurodegenerative disorder chorea-acanthocytosis (ChAc). Chorein is involved in the actin cytoskeleton organization, calcium ion flux, neuronal cell excitability, exocytosis and autophagy. The function of this protein is poorly understood, and obtaining this knowledge is a key to finding a cure for ChAc. Chorein, as well as the Vps13 protein from yeast, contains the APT1 domain. Our previous research has shown that the APT1 domain from yeast Vps13 (yAPT1v) binds phosphatidylinositol 3-phosphate (PI3P) in vitro. In this study, we showed that although the APT1 domain from chorein (hAPT1) binds to PI3P it could not functionally replace yAPT1v. The hAPT1 domain binds, in addition to PI3P, to phosphatidylinositol 5-phosphate (PI5P). The binding of hAPT1 to PI3P, unlike the binding of yAPT1v to PI3P, is regulated by the bivalent ions, calcium and magnesium. Regulation of PI3P binding via calcium is also observed for the APT1 domain of yeast autophagy protein Atg2. The substitution I2771R, found in chorein of patient suffering from ChAc, reduces the binding of the hAPT1 domain to PI3P and PI5P. These results suggest that the ability of APT1 domains to bind phosphoinositides is regulated differently in yeast and human protein and that this regulation is important for chorein function.
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Affiliation(s)
- Damian Kolakowski
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Joanna Kaminska
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland.
| | - Teresa Zoladek
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
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Severe Consequences of SAC3/FIG4 Phosphatase Deficiency to Phosphoinositides in Patients with Charcot-Marie-Tooth Disease Type-4J. Mol Neurobiol 2019; 56:8656-8667. [PMID: 31313076 DOI: 10.1007/s12035-019-01693-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/01/2019] [Indexed: 01/26/2023]
Abstract
Charcot-Marie-Tooth disease type-4J (CMT4J), an autosomal recessively inherited peripheral neuropathy characterized by neuronal degeneration, segmental demyelination, and limb muscle weakness, is caused by compound heterozygous mutations in the SAC3/FIG4 gene, resulting in SAC3/FIG4 protein deficiency. SAC3/FIG4 is a phosphatase that not only turns over PtdIns(3,5)P2 to PtdIns3P but also promotes PtdIns(3,5)P2 synthesis by activating the PIKFYVE kinase that also makes PtdIns5P. Whether CMT4J patients have alterations in PtdIns(3,5)P2, PtdIns5P or in other phosphoinositides (PIs), and if yes, in what direction these changes might be, has never been examined. We performed PI profiling in primary fibroblasts from a cohort of CMT4J patients. Subsequent to myo-[2-3H]inositol cell labeling to equilibrium, steady-state levels of PIs were quantified by HPLC under conditions concurrently detecting PtdIns5P, PtdIns(3,5)P2, and the other PIs. Immunoblotting verified SAC3/FIG4 depletion in CMT4J fibroblasts. Compared to normal human controls (n = 9), both PtdIns(3,5)P2 and PtdIns5P levels were significantly decreased in CMT4J fibroblasts (n = 13) by 36.4 ± 3.6% and 43.1 ± 4.4%, respectively (p < 0.0001). These reductions were independent of patients' gender or disease onset. Although mean values for PtdIns3P in the CMT4J cohort remained unchanged, there were high variations in PtdIns3P among individual patients. Aberrant endolysosomal vacuoles, typically seen under PtdIns(3,5)P2 reduction, were apparent but not in fibroblasts from all patients. The subset of patients without aberrant vacuoles exhibited especially low PtdIns3P levels. Concomitant decreases in PtdIns5P and PtdIns(3,5)P2 and the link between PtdIns3P levels and cellular vacuolization are novel insights shedding further light into the molecular determinants in CMT4J polyneuropathy.
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Ghosh A, Sharma S, Shinde D, Ramya V, Raghu P. A novel mass assay to measure phosphatidylinositol-5-phosphate from cells and tissues. Biosci Rep 2019; 39:BSR20192502. [PMID: 31652444 PMCID: PMC6822513 DOI: 10.1042/bsr20192502] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/19/2019] [Accepted: 09/27/2019] [Indexed: 12/23/2022] Open
Abstract
Phosphatidylinositol-5-phosphate (PI5P) is a low abundance lipid proposed to have functions in cell migration, DNA damage responses, receptor trafficking and insulin signalling in metazoans. However, studies of PI5P function are limited by the lack of scalable techniques to quantify its level from cells and tissues in multicellular organisms. Currently, PI5P measurement requires the use of radionuclide labelling approaches that are not easily applicable in tissues or in vivo samples. In the present study, we describe a simple and reliable, non-radioactive mass assay to measure total PI5P levels from cells and tissues of Drosophila, a genetically tractable multicellular model. We use heavy oxygen-labelled ATP (18O-ATP) to label PI5P from tissue extracts while converting it into PI(4,5)P2 using an in vitro kinase reaction. The product of this reaction can be selectively detected and quantified with high sensitivity using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) platform. Further, using this method, we capture and quantify the unique acyl chain composition of PI5P from Drosophila cells and tissues. Finally, we demonstrate the use of this technique to quantify elevations in PI5P levels, from Drosophila larval tissues and cultured cells depleted of phosphatidylinositol 5 phosphate 4-kinase (PIP4K), that metabolizes PI5P into PI(4,5)P2 thus regulating its levels. Thus, we demonstrate the potential of our method to quantify PI5P levels with high sensitivity from cells and tissues of multicellular organisms thus accelerating understanding of PI5P functions in vivo.
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Affiliation(s)
- Avishek Ghosh
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bangalore 560065, India
| | - Sanjeev Sharma
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bangalore 560065, India
| | - Dhananjay Shinde
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bangalore 560065, India
| | - Visvanathan Ramya
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bangalore 560065, India
| | - Padinjat Raghu
- National Centre for Biological Sciences, TIFR-GKVK Campus, Bellary Road, Bangalore 560065, India
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9
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Ikonomov OC, Sbrissa D, Shisheva A. Small molecule PIKfyve inhibitors as cancer therapeutics: Translational promises and limitations. Toxicol Appl Pharmacol 2019; 383:114771. [PMID: 31628917 DOI: 10.1016/j.taap.2019.114771] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 09/27/2019] [Accepted: 09/29/2019] [Indexed: 11/20/2022]
Abstract
Through synthesis of two rare phosphoinositides, PtdIns(3,5)P2 and PtdIns5P, the ubiquitously expressed phosphoinositide kinase PIKfyve is implicated in pleiotropic cellular functions. Small molecules specifically inhibiting PIKfyve activity cause cytoplasmic vacuolation in all dividing cells in culture yet trigger non-apoptotic death through excessive vacuolation only in cancer cells. Intriguingly, cancer cell toxicity appears to be inhibitor-specific suggesting that additional targets beyond PIKfyve are affected. One PIKfyve inhibitor - apilimod - is already in clinical trials for treatment of B-cell malignancies. However, apilimod is inactivated in cultured cells and exhibits unexpectedly low plasma levels in patients treated with maximum oral dosage. Thus, the potential widespread use of PIKfyve inhibitors as cancer therapeutics requires progress on multiple fronts: (i) advances in methods for isolating relevant cancer cells from individual patients; (ii) delineation of the molecular mechanisms potentiating the vacuolation induced by PIKfyve inhibitors in sensitive cancer cells; (iii) design of PIKfyve inhibitors with favorable pharmacokinetics; and (iv) development of effective drug combinations.
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Affiliation(s)
- Ognian C Ikonomov
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Diego Sbrissa
- Department of Urology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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Raghu P, Joseph A, Krishnan H, Singh P, Saha S. Phosphoinositides: Regulators of Nervous System Function in Health and Disease. Front Mol Neurosci 2019; 12:208. [PMID: 31507376 PMCID: PMC6716428 DOI: 10.3389/fnmol.2019.00208] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 08/07/2019] [Indexed: 12/11/2022] Open
Abstract
Phosphoinositides, the seven phosphorylated derivatives of phosphatidylinositol have emerged as regulators of key sub-cellular processes such as membrane transport, cytoskeletal function and plasma membrane signaling in eukaryotic cells. All of these processes are also present in the cells that constitute the nervous system of animals and in this setting too, these are likely to tune key aspects of cell biology in relation to the unique structure and function of neurons. Phosphoinositides metabolism and function are mediated by enzymes and proteins that are conserved in evolution, and analysis of knockouts of these in animal models implicate this signaling system in neural function. Most recently, with the advent of human genome analysis, mutations in genes encoding components of the phosphoinositide signaling pathway have been implicated in human diseases although the cell biological basis of disease phenotypes in many cases remains unclear. In this review we evaluate existing evidence for the involvement of phosphoinositide signaling in human nervous system diseases and discuss ways of enhancing our understanding of the role of this pathway in the human nervous system's function in health and disease.
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Affiliation(s)
- Padinjat Raghu
- National Centre for Biological Sciences-TIFR, Bengaluru, India
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11
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Phosphatidylinositol 5 Phosphate (PI5P): From Behind the Scenes to the Front (Nuclear) Stage. Int J Mol Sci 2019; 20:ijms20092080. [PMID: 31035587 PMCID: PMC6539119 DOI: 10.3390/ijms20092080] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 04/20/2019] [Accepted: 04/23/2019] [Indexed: 12/11/2022] Open
Abstract
Phosphatidylinositol (PI)-related signaling plays a pivotal role in many cellular aspects, including survival, cell proliferation, differentiation, DNA damage, and trafficking. PI is the core of a network of proteins represented by kinases, phosphatases, and lipases which are able to add, remove or hydrolyze PI, leading to different phosphoinositide products. Among the seven known phosphoinositides, phosphatidylinositol 5 phosphate (PI5P) was the last to be discovered. PI5P presence in cells is very low compared to other PIs. However, much evidence collected throughout the years has described the role of this mono-phosphoinositide in cell cycles, stress response, T-cell activation, and chromatin remodeling. Interestingly, PI5P has been found in different cellular compartments, including the nucleus. Here, we will review the nuclear role of PI5P, describing how it is synthesized and regulated, and how changes in the levels of this rare phosphoinositide can lead to different nuclear outputs.
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12
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Baranov MV, Bianchi F, Schirmacher A, van Aart MAC, Maassen S, Muntjewerff EM, Dingjan I, Ter Beest M, Verdoes M, Keyser SGL, Bertozzi CR, Diederichsen U, van den Bogaart G. The Phosphoinositide Kinase PIKfyve Promotes Cathepsin-S-Mediated Major Histocompatibility Complex Class II Antigen Presentation. iScience 2018; 11:160-177. [PMID: 30612035 PMCID: PMC6319320 DOI: 10.1016/j.isci.2018.12.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 11/28/2018] [Accepted: 12/14/2018] [Indexed: 02/07/2023] Open
Abstract
Antigen presentation to T cells in major histocompatibility complex class II (MHC class II) requires the conversion of early endo/phagosomes into lysosomes by a process called maturation. Maturation is driven by the phosphoinositide kinase PIKfyve. Blocking PIKfyve activity by small molecule inhibitors caused a delay in the conversion of phagosomes into lysosomes and in phagosomal acidification, whereas production of reactive oxygen species (ROS) increased. Elevated ROS resulted in reduced activity of cathepsin S and B, but not X, causing a proteolytic defect of MHC class II chaperone invariant chain Ii processing. We developed a novel universal MHC class II presentation assay based on a bio-orthogonal "clickable" antigen and showed that MHC class II presentation was disrupted by the inhibition of PIKfyve, which in turn resulted in reduced activation of CD4+ T cells. Our results demonstrate a key role of PIKfyve in the processing and presentation of antigens, which should be taken into consideration when targeting PIKfyve in autoimmune disease and cancer.
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Affiliation(s)
- Maksim V Baranov
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Frans Bianchi
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands; Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, Groningen 9747 AG, the Netherlands
| | - Anastasiya Schirmacher
- Institute of Organic and Biomolecular Chemistry, Georg-August-University of Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Melissa A C van Aart
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Sjors Maassen
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands; Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, Groningen 9747 AG, the Netherlands
| | - Elke M Muntjewerff
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Ilse Dingjan
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Martin Ter Beest
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | - Martijn Verdoes
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands
| | | | - Carolyn R Bertozzi
- Department of Chemistry and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Ulf Diederichsen
- Institute of Organic and Biomolecular Chemistry, Georg-August-University of Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Geert van den Bogaart
- Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands; Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, Groningen 9747 AG, the Netherlands.
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13
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PIKfyve inhibitor cytotoxicity requires AKT suppression and excessive cytoplasmic vacuolation. Toxicol Appl Pharmacol 2018; 356:151-158. [DOI: 10.1016/j.taap.2018.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 07/16/2018] [Accepted: 08/02/2018] [Indexed: 11/22/2022]
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14
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Sbrissa D, Naisan G, Ikonomov OC, Shisheva A. Apilimod, a candidate anticancer therapeutic, arrests not only PtdIns(3,5)P2 but also PtdIns5P synthesis by PIKfyve and induces bafilomycin A1-reversible aberrant endomembrane dilation. PLoS One 2018; 13:e0204532. [PMID: 30240452 PMCID: PMC6150535 DOI: 10.1371/journal.pone.0204532] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 09/10/2018] [Indexed: 01/02/2023] Open
Abstract
PIKfyve, an evolutionarily conserved kinase synthesizing PtdIns5P and PtdIns(3,5)P2, is crucial for mammalian cell proliferation and viability. Accordingly, PIKfyve inhibitors are now in clinical trials as anti-cancer drugs. Among those, apilimod is the most promising, yet its potency to inhibit PIKfyve and affect endomembrane homeostasis is only partially characterized. We demonstrate here for the first time that apilimod powerfully inhibited in vitro synthesis of PtdIns5P along with that of PtdIns(3,5)P2. HPLC-based resolution of intracellular phosphoinositides (PIs) revealed that apilimod triggered a marked reduction of both lipids in the context of intact cells. Notably, there was also a profound rise in PtdIns3P resulting from arrested PtdIns3P consumption for PtdIns(3,5)P2 synthesis. As typical for PIKfyve inhibition and the concomitant PtdIns(3,5)P2 reduction, apilimod induced the appearance of dilated endomembrane structures in the form of large translucent cytoplasmic vacuoles. Remarkably, bafilomycin A1 (BafA1) fully reversed the aberrant cell phenotype back to normal and completely precluded the appearance of cytoplasmic vacuoles when added prior to apilimod. Inspection of the PI profiles ruled out restoration of the reduced PtdIns(3,5)P2 pool as a molecular mechanism underlying BafA1 rescue. Rather, we found that BafA1 markedly attenuated the PtdIns3P elevation under PIKfyve inhibition. This was accompanied by profoundly decreased endosomal recruitment of fusogenic EEA1. Together, our data demonstrate that apilimod inhibits not only PtdIns(3,5)P2 but also PtdIns5P synthesis and that the cytoplasmic vacuolization triggered by the inhibitor is precluded or reversed by BafA1 through a mechanism associated, in part, with reduction in both PtdIns3P levels and EEA1 membrane recruitment.
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Affiliation(s)
- Diego Sbrissa
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Ghassan Naisan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Ognian C. Ikonomov
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- * E-mail:
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15
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Qiu S, Côté M. From hitchhiker to hijacker: pathogen exploitation of endosomal phosphoinositides 1. Biochem Cell Biol 2018; 97:1-9. [PMID: 29746785 DOI: 10.1139/bcb-2017-0317] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Signalling through phosphoinositide lipids is essential for regulating many cellular processes, including endosomal trafficking. A number of intracellular pathogens have found ways to subvert host trafficking pathways via exploitation of endosomal phosphoinositides. This review will discuss how pathogens such as bacteria, viruses, and eukaryotic parasites depend on endosomal phosphoinositides for infection as well as the mechanisms through which some are able to actively manipulate these signalling lipids to facilitate invasion, survival, replication, and immune evasion.
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Affiliation(s)
- Shirley Qiu
- a Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,b Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,c Center for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Marceline Côté
- a Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,b Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,c Center for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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16
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Fogarty K, Kashem M, Bauer A, Bernardino A, Brennan D, Cook B, Farrow N, Molinaro T, Nelson R. Development of Three Orthogonal Assays Suitable for the Identification and Qualification of PIKfyve Inhibitors. Assay Drug Dev Technol 2018; 15:210-219. [PMID: 28723271 DOI: 10.1089/adt.2017.790] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
FYVE-type zinc finger-containing phosphoinositide kinase (PIKfyve) catalyzes the formation of phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) from phosphatidylinositol 3-phosphate (PI(3)P). PIKfyve has been implicated in multiple cellular processes, and its role in the regulation of toll-like receptor (TLR) pathways and the production of proinflammatory cytokines has sparked interest in developing small-molecule PIKfyve inhibitors as potential therapeutics to treat autoimmune and inflammatory diseases. We developed three orthogonal assays to identify and qualify small-molecule inhibitors of PIKfyve: (1) a purified component microfluidic enzyme assay that measures the conversion of fluorescently labeled PI(3)P to PI(3,5)P2 by purified recombinant full-length human 6His-PIKfyve (rPIKfyve); (2) an intracellular protein stabilization assay using the kinase domain of PIKfyve expressed in HEK293 cells; and (3) a cell-based functional assay that measures the production of interleukin (IL)-12p70 in human peripheral blood mononuclear cells stimulated with TLR agonists lipopolysaccharide and R848. We determined apparent Km values for both ATP and labeled PI(3)P in the rPIKfyve enzyme assay and evaluated the enzyme's ability to use phosphatidylinositol as a substrate. We also tested four reference compounds in the three assays and showed that together these assays provide a platform that is suitable to select promising inhibitors having appropriate functional activity and confirmed cellular target engagement to advance into preclinical models of inflammation.
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Affiliation(s)
- Kylie Fogarty
- 1 Department of Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc. , Ridgefield, Connecticut
| | - Mohammed Kashem
- 1 Department of Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc. , Ridgefield, Connecticut
| | - Andras Bauer
- 2 Department of Immunology and Inflammation, Boehringer Ingelheim Pharmaceuticals, Inc. , Ridgefield, Connecticut
| | - Alexandra Bernardino
- 2 Department of Immunology and Inflammation, Boehringer Ingelheim Pharmaceuticals, Inc. , Ridgefield, Connecticut
| | - Debra Brennan
- 1 Department of Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc. , Ridgefield, Connecticut
| | - Brian Cook
- 1 Department of Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc. , Ridgefield, Connecticut
| | - Neil Farrow
- 1 Department of Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc. , Ridgefield, Connecticut
| | - Teresa Molinaro
- 1 Department of Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc. , Ridgefield, Connecticut
| | - Richard Nelson
- 1 Department of Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc. , Ridgefield, Connecticut
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17
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Liggins MC, Flesher JL, Jahid S, Vasudeva P, Eby V, Takasuga S, Sasaki J, Sasaki T, Boissy RE, Ganesan AK. PIKfyve regulates melanosome biogenesis. PLoS Genet 2018; 14:e1007290. [PMID: 29584722 PMCID: PMC5889185 DOI: 10.1371/journal.pgen.1007290] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 04/06/2018] [Accepted: 03/05/2018] [Indexed: 12/18/2022] Open
Abstract
PIKfyve, VAC14, and FIG4 form a complex that catalyzes the production of PI(3,5)P2, a signaling lipid implicated in process ranging from lysosome maturation to neurodegeneration. While previous studies have identified VAC14 and FIG4 mutations that lead to both neurodegeneration and coat color defects, how PIKfyve regulates melanogenesis is unknown. In this study, we sought to better understand the role of PIKfyve in melanosome biogenesis. Melanocyte-specific PIKfyve knockout mice exhibit greying of the mouse coat and the accumulation of single membrane vesicle structures in melanocytes resembling multivesicular endosomes. PIKfyve inhibition blocks melanosome maturation, the processing of the melanosome protein PMEL, and the trafficking of the melanosome protein TYRP1. Taken together, these studies identify a novel role for PIKfyve in controlling the delivery of proteins from the endosomal compartment to the melanosome, a role that is distinct from the role of PIKfyve in the reformation of lysosomes from endolysosomes.
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Affiliation(s)
- Marc C. Liggins
- Department of Dermatology, University of California, San Diego, San Diego, CA, United States of America
| | - Jessica L. Flesher
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA, United States of America
| | - Sohail Jahid
- Department of Dermatology, University of California, Irvine, Irvine, CA, United States of America
| | - Priya Vasudeva
- Department of Dermatology, University of California, Irvine, Irvine, CA, United States of America
| | - Victoria Eby
- Department of Dermatology, University of Cincinnati, Cincinnati, OH, United States of America
| | - Shunsuke Takasuga
- Department of Medical Biology, Akita University School of Medicine, Akita, Japan
| | - Junko Sasaki
- Department of Medical Biology, Akita University School of Medicine, Akita, Japan
| | - Takehiko Sasaki
- Department of Medical Biology, Akita University School of Medicine, Akita, Japan
| | - Raymond E. Boissy
- Department of Dermatology, University of Cincinnati, Cincinnati, OH, United States of America
| | - Anand K. Ganesan
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA, United States of America
- Department of Dermatology, University of California, Irvine, Irvine, CA, United States of America
- * E-mail:
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18
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Abstract
Selective enrichment of the polyphosphoinositides (PPIn), such as PtdIns(4,5)P2 and PtdIns4P, helps to determine the identity of the plasma membrane (PM) and regulates many aspects of cell biology through a vast number of protein effectors. Polarity proteins had long been assumed to be non-PPIn-binding proteins that mainly associate with PM/cell cortex through their extensive protein-protein interaction network. However, recent studies began to reveal that several key polarity proteins electrostatically bind to PPIn through their positively charged protein domains or structures and such PPIn-binding property is essential for their direct and specific attachment to PM. Although the physical nature of the charge-based PPIn binding appears to be simple and nonspecific, it serves as an elegant mechanism that can be efficiently and specifically regulated for achieving polarized PM targeting of polarity proteins. As an unexpected consequence, subcellular localization of PPIn-binding polarity proteins are also subject to regulations by physiological conditions such as hypoxia and ischemia that acutely and reversibly depletes PPIn from PM.
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Affiliation(s)
- Gerald R Hammond
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania 15261
| | - Yang Hong
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania 15261
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19
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Dayam RM, Sun CX, Choy CH, Mancuso G, Glogauer M, Botelho RJ. The Lipid Kinase PIKfyve Coordinates the Neutrophil Immune Response through the Activation of the Rac GTPase. THE JOURNAL OF IMMUNOLOGY 2017; 199:2096-2105. [DOI: 10.4049/jimmunol.1601466] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 07/11/2017] [Indexed: 11/19/2022]
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20
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Tsuruta F, Okajima T, Yano S, Chiba T. Quantification of Endosome and Lysosome Motilities in Cultured Neurons Using Fluorescent Probes. J Vis Exp 2017. [PMID: 28570534 DOI: 10.3791/55488] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
In the brain, membrane trafficking systems play important roles in regulating neuronal functions, such as neuronal morphology, synaptic plasticity, survival, and glial communications. To date, numerous studies have reported that defects in these systems cause various neuronal diseases. Thus, understanding the mechanisms underlying vesicle dynamics may provide influential clues that could aid in the treatment of several neuronal disorders. Here, we describe a method for quantifying vesicle motilities, such as motility distance and rate of movement, using a software plug-in for the ImageJ platform. To obtain images for quantification, we labeled neuronal endosome-lysosome structures with EGFP-tagged vesicle marker proteins and observed the movement of vesicles using a time-lapse microscopy. This method is highly useful and simplify measuring vesicle motility in neurites, such as axons and dendrites, as well as in the soma of both neurons and glial cells. Furthermore, this method can be applied to other cell lines, such as fibroblasts and endothelial cells. This approach could provide a valuable advancement of our understanding of membrane trafficking.
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Affiliation(s)
- Fuminori Tsuruta
- Graduate School of Life and Environmental Sciences, University of Tsukuba; PhD Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba; Life Science Center of Tsukuba Advanced Research Alliance (TARA), University of Tsukuba;
| | - Tomomi Okajima
- Graduate School of Life and Environmental Sciences, University of Tsukuba
| | - Sarasa Yano
- Graduate School of Life and Environmental Sciences, University of Tsukuba
| | - Tomoki Chiba
- Graduate School of Life and Environmental Sciences, University of Tsukuba; PhD Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba; Life Science Center of Tsukuba Advanced Research Alliance (TARA), University of Tsukuba
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21
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Hessvik NP, Øverbye A, Brech A, Torgersen ML, Jakobsen IS, Sandvig K, Llorente A. PIKfyve inhibition increases exosome release and induces secretory autophagy. Cell Mol Life Sci 2016; 73:4717-4737. [PMID: 27438886 PMCID: PMC11108566 DOI: 10.1007/s00018-016-2309-8] [Citation(s) in RCA: 161] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 07/08/2016] [Accepted: 07/11/2016] [Indexed: 01/08/2023]
Abstract
Exosomes are vesicles released from cells by fusion of multivesicular bodies (MVBs) with the plasma membrane. This study aimed to investigate whether the phosphoinositide kinase PIKfyve affects this process. Our results show that in PC-3 cells inhibition of PIKfyve by apilimod or depletion by siRNA increased the secretion of the exosomal fraction. Moreover, quantitative electron microscopy analysis showed that cells treated with apilimod contained more MVBs per cell and more intraluminal vesicles per MVB. Interestingly, mass spectrometry analysis revealed a considerable enrichment of autophagy-related proteins (NBR1, p62, LC3, WIPI2) in exosomal fractions released by apilimod-treated cells, a result that was confirmed by immunoblotting. When the exosome preparations were investigated by electron microscopy a small population of p62-labelled electron dense structures was observed together with CD63-containing exosomes. The p62-positive structures were found in less dense fractions than exosomes in density gradients. Inside the cells, p62 and CD63 were found in the same MVB-like organelles. Finally, both the degradation of EGF and long-lived proteins were shown to be reduced by apilimod. In conclusion, inhibition of PIKfyve increases secretion of exosomes and induces secretory autophagy, showing that these pathways are closely linked. We suggest this is due to impaired fusion of lysosomes with both MVBs and autophagosomes, and possibly increased fusion of MVBs with autophagosomes, and that the cells respond by secreting the content of these organelles to maintain cellular homeostasis.
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Affiliation(s)
- Nina Pettersen Hessvik
- Department of Molecular Cell Biology, The Norwegian Radium Hospital, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway
- Centre for Cancer Biomedicine, University of Oslo, 0379, Oslo, Norway
| | - Anders Øverbye
- Department of Molecular Cell Biology, The Norwegian Radium Hospital, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway
- Centre for Cancer Biomedicine, University of Oslo, 0379, Oslo, Norway
| | - Andreas Brech
- Department of Molecular Cell Biology, The Norwegian Radium Hospital, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway
- Centre for Cancer Biomedicine, University of Oslo, 0379, Oslo, Norway
- Department of Biosciences, University of Oslo, 0316, Oslo, Norway
| | - Maria Lyngaas Torgersen
- Department of Molecular Cell Biology, The Norwegian Radium Hospital, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway
- Centre for Cancer Biomedicine, University of Oslo, 0379, Oslo, Norway
| | - Ida Seim Jakobsen
- Department of Molecular Cell Biology, The Norwegian Radium Hospital, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway
- Centre for Cancer Biomedicine, University of Oslo, 0379, Oslo, Norway
| | - Kirsten Sandvig
- Department of Molecular Cell Biology, The Norwegian Radium Hospital, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway
- Centre for Cancer Biomedicine, University of Oslo, 0379, Oslo, Norway
- Department of Biosciences, University of Oslo, 0316, Oslo, Norway
| | - Alicia Llorente
- Department of Molecular Cell Biology, The Norwegian Radium Hospital, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway.
- Centre for Cancer Biomedicine, University of Oslo, 0379, Oslo, Norway.
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22
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Rameh LE, Mackey AM. IQGAP1 makes PI(3)K signalling as easy as PIP, PIP2, PIP3. Nat Cell Biol 2016; 18:1263-1265. [DOI: 10.1038/ncb3440] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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23
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Ikonomov OC, Sbrissa D, Delvecchio K, Rillema JA, Shisheva A. Unexpected severe consequences of Pikfyve deletion by aP2- or Aq-promoter-driven Cre expression for glucose homeostasis and mammary gland development. Physiol Rep 2016; 4:4/11/e12812. [PMID: 27273882 PMCID: PMC4908490 DOI: 10.14814/phy2.12812] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 05/04/2016] [Indexed: 01/03/2023] Open
Abstract
Systemic deficiency of PIKfyve, the evolutionarily conserved phosphoinositide kinase synthesizing cellular PtdIns5P and PtdIns(3,5)P2 and implicated in insulin signaling, causes early embryonic death in mice. In contrast, mice with muscle‐specific Pikfyve disruption have normal lifespan but exhibit early‐age whole‐body glucose intolerance and muscle insulin resistance, thus establishing the key role of muscle PIKfyve in glucose homeostasis. Fat and muscle tissues control postprandial glucose clearance through different mechanisms, raising questions as to whether adipose Pikfyve disruption will also trigger whole‐body metabolic abnormalities, and if so, what the mechanism might be. To clarify these issues, here we have characterized two new mouse models with adipose tissue disruption of Pikfyve through Cre recombinase expression driven by adipose‐specific aP2‐ or adiponectin (Aq) promoters. Whereas both mouse lines were ostensibly normal until adulthood, their glucose homeostasis and systemic insulin sensitivity were severely dysregulated. These abnormalities stemmed in part from accelerated fat‐cell lipolysis and elevated serum FFA. Intriguingly, aP2‐Cre‐PIKfyvefl/fl but not Aq‐Cre‐PIKfyvefl/fl females had severely impaired pregnancy‐induced mammary gland differentiation and lactogenesis, consistent with aP2‐Cre‐mediated Pikfyve excision in nonadipogenic tissues underlying this defect. Intriguingly, whereas mammary glands from postpartum control and Aq‐Cre‐PIKfyvefl/fl mice or ex vivo mammary gland explants showed profound upregulation of PIKfyve protein levels subsequent to prolactin receptor activation, such increases were not apparent in aP2‐Cre‐PIKfyvefl/fl females. Collectively, our data identify for the first time that adipose tissue Pikfyve plays a key role in the mechanisms regulating glucose homeostasis and that the PIKfyve pathway is critical in mammary epithelial differentiation during pregnancy and lactogenesis downstream of prolactin receptor signaling.
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Affiliation(s)
- Ognian C Ikonomov
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Diego Sbrissa
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Khortnal Delvecchio
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - James A Rillema
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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24
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Compton LM, Ikonomov OC, Sbrissa D, Garg P, Shisheva A. Active vacuolar H+ ATPase and functional cycle of Rab5 are required for the vacuolation defect triggered by PtdIns(3,5)P2 loss under PIKfyve or Vps34 deficiency. Am J Physiol Cell Physiol 2016; 311:C366-77. [PMID: 27335171 DOI: 10.1152/ajpcell.00104.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 06/17/2016] [Indexed: 01/12/2023]
Abstract
The two evolutionarily conserved mammalian lipid kinases Vps34 and PIKfyve are involved in an important physiological relationship, whereby the former produces phosphatidylinositol (PtdIns) 3P that is used as a substrate for PtdIns(3,5)P2 synthesis by the latter. Reduced production of PtdIns(3,5)P2 in proliferating mammalian cells is phenotypically manifested by the formation of multiple translucent cytoplasmic vacuoles, readily rescued upon exogenous delivery of PtdIns(3,5)P2 or overproduction of PIKfyve. Although the aberrant vacuolation phenomenon has been frequently used as a sensitive functional measure of localized PtdIns(3,5)P2 reduction, cellular factors governing the appearance of cytoplasmic vacuoles under PtdIns3P-PtdIns(3,5)P2 loss remain elusive. To gain further mechanistic insight about the vacuolation process following PtdIns(3,5)P2 reduction, in this study we sought for cellular mechanisms required for manifestation of the aberrant endomembrane vacuoles triggered by PIKfyve or Vps34 dysfunction. The latter was achieved by various means such as pharmacological inhibition, gene disruption, or dominant-interference in several proliferating mammalian cell types. We report here that inhibition of V-ATPase with bafilomycin A1 as well as inactivation of the GTP-GDP cycle of Rab5a GTPase phenotypically rescued or completely precluded the cytoplasmic vacuolization despite the continued presence of inactivated PIKfyve or Vps34. Bafilomycin A1 also restored the aberrant EEA1-positive endosomes, enlarged upon short PIKfyve inhibition with YM201636. Together, our work identifies for the first time that factors such as active V-ATPase or functional Rab5a cycle are acting coincidentally with the PtdIns(3,5)P2 reduction in triggering formation of aberrant cytoplasmic vacuoles under PIKfyve or Vps34 dysfunction.
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Affiliation(s)
- Lauren M Compton
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; and
| | - Ognian C Ikonomov
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; and
| | - Diego Sbrissa
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; and
| | - Puneet Garg
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; and
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25
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Venkatareddy M, Verma R, Kalinowski A, Patel SR, Shisheva A, Garg P. Distinct Requirements for Vacuolar Protein Sorting 34 Downstream Effector Phosphatidylinositol 3-Phosphate 5-Kinase in Podocytes Versus Proximal Tubular Cells. J Am Soc Nephrol 2016; 27:2702-19. [PMID: 26825532 DOI: 10.1681/asn.2015050555] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 12/09/2015] [Indexed: 12/16/2022] Open
Abstract
The mechanisms by which the glomerular filtration barrier prevents the loss of large macromolecules and simultaneously, maintains the filter remain poorly understood. Recent studies proposed that podocytes have an active role in both the endocytosis of filtered macromolecules and the maintenance of the filtration barrier. Deletion of a key endosomal trafficking regulator, the class 3 phosphatidylinositol (PtdIns) 3-kinase vacuolar protein sorting 34 (Vps34), in podocytes results in aberrant endosomal membrane morphology and podocyte dysfunction. We recently showed that the vacuolation phenotype in cultured Vps34-deficient podocytes is caused by the absence of a substrate for the Vps34 downstream effector PtdIns 3-phosphate 5-kinase (PIKfyve), which phosphorylates Vps34-generated PtdIns(3)P to produce PtdIns (3,5)P2. PIKfyve perturbation and PtdIns(3,5)P2 reduction result in massive membrane vacuolation along the endosomal system, but the cell-specific functions of PIKfyve in vivo remain unclear. We show here that the genetic deletion of PIKfyve in endocytically active proximal tubular cells resulted in the development of large cytoplasmic vacuoles caused by arrested endocytic traffic progression at a late-endosome stage. In contrast, deletion of PIKfyve in glomerular podocytes did not significantly alter the endosomal morphology, even in age 18-month-old mice. However, on culturing, the PIKfyve-deleted podocytes developed massive cytoplasmic vacuoles. In summary, these data suggest that glomerular podocytes and proximal tubules have different requirements for PIKfyve function, likely related to distinct in vivo needs for endocytic flux.
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Affiliation(s)
- Madhusudan Venkatareddy
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan; and
| | - Rakesh Verma
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan; and
| | - Anne Kalinowski
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan; and
| | - Sanjeevkumar R Patel
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan; and
| | - Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Puneet Garg
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan; and
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The ML1Nx2 Phosphatidylinositol 3,5-Bisphosphate Probe Shows Poor Selectivity in Cells. PLoS One 2015; 10:e0139957. [PMID: 26460749 PMCID: PMC4604148 DOI: 10.1371/journal.pone.0139957] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/17/2015] [Indexed: 01/15/2023] Open
Abstract
Phosphatidylinositol (3,5)-bisphosphate (PtdIns(3,5)P2) is a quantitatively minor phospholipid in eukaryotic cells that plays a fundamental role in regulating endocytic membrane traffic. Despite its clear importance for cellular function and organism physiology, mechanistic details of its biology have so far not been fully elucidated. In part, this is due to a lack of experimental tools that specifically probe for PtdIns(3,5)P2 in cells to unambiguously identify its dynamics and site(s) of action. In this study, we have evaluated a recently reported PtdIns(3,5)P2 biosensor, GFP-ML1Nx2, for its veracity as such a probe. We report that, in live cells, the localization of this biosensor to sub-cellular compartments is largely independent of PtdIns(3,5)P2, as assessed after pharmacological, chemical genetic or genomic interventions that block the lipid's synthesis. We therefore conclude that it is unwise to interpret the localization of ML1Nx2 as a true and unbiased biosensor for PtdIns(3,5)P2.
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Ikonomov OC, Sbrissa D, Compton LM, Kumar R, Tisdale EJ, Chen X, Shisheva A. The Protein Complex of Neurodegeneration-related Phosphoinositide Phosphatase Sac3 and ArPIKfyve Binds the Lewy Body-associated Synphilin-1, Preventing Its Aggregation. J Biol Chem 2015; 290:28515-28529. [PMID: 26405034 DOI: 10.1074/jbc.m115.669929] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Indexed: 12/14/2022] Open
Abstract
The 5-phosphoinositide phosphatase Sac3, in which loss-of-function mutations are linked to neurodegenerative disorders, forms a stable cytosolic complex with the scaffolding protein ArPIKfyve. The ArPIKfyve-Sac3 heterodimer interacts with the phosphoinositide 5-kinase PIKfyve in a ubiquitous ternary complex that couples PtdIns(3,5)P2 synthesis with turnover at endosomal membranes, thereby regulating the housekeeping endocytic transport in eukaryotes. Neuron-specific associations of the ArPIKfyve-Sac3 heterodimer, which may shed light on the neuropathological mechanisms triggered by Sac3 dysfunction, are unknown. Here we conducted mass spectrometry analysis for brain-derived interactors of ArPIKfyve-Sac3 and unraveled the α-synuclein-interacting protein Synphilin-1 (Sph1) as a new component of the ArPIKfyve-Sac3 complex. Sph1, a predominantly neuronal protein that facilitates aggregation of α-synuclein, is a major component of Lewy body inclusions in neurodegenerative α-synucleinopathies. Modulations in ArPIKfyve/Sac3 protein levels by RNA silencing or overexpression in several mammalian cell lines, including human neuronal SH-SY5Y or primary mouse cortical neurons, revealed that the ArPIKfyve-Sac3 complex specifically altered the aggregation properties of Sph1-GFP. This effect required an active Sac3 phosphatase and proceeded through mechanisms that involved increased Sph1-GFP partitioning into the cytosol and removal of Sph1-GFP aggregates by basal autophagy but not by the proteasomal system. If uncoupled from ArPIKfyve elevation, overexpressed Sac3 readily aggregated, markedly enhancing the aggregation potential of Sph1-GFP. These data identify a novel role of the ArPIKfyve-Sac3 complex in the mechanisms controlling aggregate formation of Sph1 and suggest that Sac3 protein deficiency or overproduction may facilitate aggregation of aggregation-prone proteins, thereby precipitating the onset of multiple neuronal disorders.
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Affiliation(s)
- Ognian C Ikonomov
- Departments of Physiology, Wayne State School of Medicine, Detroit, Michigan 48201
| | - Diego Sbrissa
- Departments of Physiology, Wayne State School of Medicine, Detroit, Michigan 48201
| | - Lauren M Compton
- Departments of Physiology, Wayne State School of Medicine, Detroit, Michigan 48201
| | - Rita Kumar
- Departments of Physiology, Wayne State School of Medicine, Detroit, Michigan 48201; Departments of Emergency Medicine, Wayne State School of Medicine, Detroit, Michigan 48201
| | - Ellen J Tisdale
- Departments of Pharmacology, Wayne State School of Medicine, Detroit, Michigan 48201
| | - Xuequn Chen
- Departments of Physiology, Wayne State School of Medicine, Detroit, Michigan 48201
| | - Assia Shisheva
- Departments of Physiology, Wayne State School of Medicine, Detroit, Michigan 48201.
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Ikonomov OC, Sbrissa D, Venkatareddy M, Tisdale E, Garg P, Shisheva A. Class III PI 3-kinase is the main source of PtdIns3P substrate and membrane recruitment signal for PIKfyve constitutive function in podocyte endomembrane homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:1240-50. [PMID: 25619930 DOI: 10.1016/j.bbamcr.2015.01.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/22/2014] [Accepted: 01/16/2015] [Indexed: 11/19/2022]
Abstract
The evolutionarily conserved PIKfyve, which synthesizes PtdIns5P from PtdIns, and PtdIns(3,5)P2 from PtdIns3P, requires PtdIns3P as both an enzyme substrate and a membrane recruitment signal. Whereas the PtdIns3P source is undetermined, class III PI3K (Vps34), the only evolutionarily conserved of the eight mammalian PI3Ks, is presumed as a main candidate. A hallmark of PIKfyve deficiency is formation of multiple translucent cytoplasmic vacuoles seen by light microscopy in cells cultured in complete media. Such an aberrant phenotype is often observed in cells from conditional Vps34 knockout (KO) mice. To clarify the mechanism of Vps34 KO-triggered vacuolation and the PtdIns3P source for PIKfyve functionality, here we have characterized a podocyte cell type derived from Vps34fl/fl mice, which, upon Cre-mediated gene KO, robustly formed cytoplasmic vacuoles resembling those in PikfyveKO MEFs. Vps34wt, expressed in Vps34KO podocytes restored the normal morphology, but only if the endogenous PIKfyve activity was intact. Conversely, expressed PIKfyvewt rescued completely the vacuolation only in PikfyveKO MEFs but not in Vps34KO podocytes. Analyses of phosphoinositide profiles by HPLC and localization patterns by a PtdIns3P biosensor revealed that Vps34 is the main supplier of localized PtdIns3P not only for PIKfyve activity but also for membrane recruitment. Concordantly, Vps34KO podocytes had severely reduced steady-state levels of both PtdIns(3,5)P2 and PtdIns5P, along with PtdIns3P. We further revealed a plausible physiologically-relevant Vps34-independent PtdIns3P supply for PIKfyve, operating through activated class I PI3Ks. Our data provide the first evidence that the vacuolation phenotype in Vps34KO podocytes is due to PIKfyve dysfunction and that Vps34 is a main PtdIns3P source for constitutive PIKfyve functionality.
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Affiliation(s)
- Ognian C Ikonomov
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Diego Sbrissa
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | | | - Ellen Tisdale
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Puneet Garg
- Division of Nephrology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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