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Jiménez-Gutiérrez E, Fernández-Acero T, Alonso-Rodríguez E, Molina M, Martín H. Neomycin Interferes with Phosphatidylinositol-4,5-Bisphosphate at the Yeast Plasma Membrane and Activates the Cell Wall Integrity Pathway. Int J Mol Sci 2022; 23:ijms231911034. [PMID: 36232332 PMCID: PMC9569482 DOI: 10.3390/ijms231911034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/14/2022] [Accepted: 09/15/2022] [Indexed: 11/20/2022] Open
Abstract
The cell wall integrity pathway (CWI) is a MAPK-mediated signaling route essential for yeast cell response to cell wall damage, regulating distinct aspects of fungal physiology. We have recently proven that the incorporation of a genetic circuit that operates as a signal amplifier into this pathway allows for the identification of novel elements involved in CWI signaling. Here, we show that the strong growth inhibition triggered by pathway hyperactivation in cells carrying the “Integrity Pathway Activation Circuit” (IPAC) also allows the easy identification of new stimuli. By using the IPAC, we have found various chemical agents that activate the CWI pathway, including the aminoglycoside neomycin. Cells lacking key components of this pathway are sensitive to this antibiotic, due to the disruption of signaling upon neomycin stimulation. Neomycin reduces both phosphatidylinositol-4,5-bisphosphate (PIP2) availability at the plasma membrane and myriocin-induced TORC2-dependent Ypk1 phosphorylation, suggesting a strong interference with plasma membrane homeostasis, specifically with PIP2. The neomycin-induced transcriptional profile involves not only genes related to stress and cell wall biogenesis, but also to amino acid metabolism, reflecting the action of this antibiotic on the yeast ribosome.
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Affiliation(s)
| | | | | | - María Molina
- Correspondence: (M.M.); (H.M.); Tel.: +34-91-394-1888 (M.M. & H.M.)
| | - Humberto Martín
- Correspondence: (M.M.); (H.M.); Tel.: +34-91-394-1888 (M.M. & H.M.)
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2
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Ballesteros A, Swartz KJ. Regulation of membrane homeostasis by TMC1 mechanoelectrical transduction channels is essential for hearing. SCIENCE ADVANCES 2022; 8:eabm5550. [PMID: 35921424 PMCID: PMC9348795 DOI: 10.1126/sciadv.abm5550] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The mechanoelectrical transduction (MET) channel in auditory hair cells converts sound into electrical signals, enabling hearing. Transmembrane-like channel 1 and 2 (TMC1 and TMC2) are implicated in forming the pore of the MET channel. Here, we demonstrate that inhibition of MET channels, breakage of the tip links required for MET, or buffering of intracellular Ca... induces pronounced phosphatidylserine externalization, membrane blebbing, and ectosome release at the hair cell sensory organelle, culminating in the loss of TMC1. Membrane homeostasis triggered by MET channel inhibition requires Tmc1 but not Tmc2, and three deafness-causing mutations in Tmc1 cause constitutive phosphatidylserine externalization that correlates with deafness phenotype. Our results suggest that, in addition to forming the pore of the MET channel, TMC1 is a critical regulator of membrane homeostasis in hair cells, and that Tmc1-related hearing loss may involve alterations in membrane homeostasis.
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3
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Bechtella L, Chalouhi E, Milán Rodríguez P, Cosset M, Ravault D, Illien F, Sagan S, Carlier L, Lequin O, Fuchs PFJ, Sachon E, Walrant A. Structural Bases for the Involvement of Phosphatidylinositol-4,5-bisphosphate in the Internalization of the Cell-Penetrating Peptide Penetratin. ACS Chem Biol 2022; 17:1427-1439. [PMID: 35608167 DOI: 10.1021/acschembio.1c00974] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cell-penetrating peptides cross cell membranes through various parallel internalization pathways. Herein, we analyze the role of the negatively charged lipid phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) in the internalization of Penetratin. Contributions of both inner leaflet and outer leaflet pools of PI(4,5)P2 were revealed by quantifying the internalization of Penetratin in cells treated with PI(4,5)P2 binders. Studies on model systems showed that Penetratin has a strong affinity for PI(4,5)P2 and interacts selectively with this lipid, even in the presence of other negatively charged lipids, as demonstrated by affinity photo-crosslinking experiments. Differential scanning calorimetry experiments showed that Penetratin induces lateral segregation in PI(4,5)P2-containing liposomes, which was confirmed by coarse-grained molecular dynamics simulations. NMR experiments indicated that Penetratin adopts a stabilized helical conformation in the presence of PI(4,5)P2-containing membranes, with an orientation parallel to the bilayer plane, which was also confirmed by all-atom simulations. NMR and photo-crosslinking experiments also suggest a rather shallow insertion of the peptide in the membrane. Put together, our findings suggest that PI(4,5)P2 is a privileged interaction partner for Penetratin and that it plays an important role in Penetratin internalization.
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Affiliation(s)
- Leïla Bechtella
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
| | - Edward Chalouhi
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
| | - Paula Milán Rodríguez
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
| | - Marine Cosset
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
| | - Delphine Ravault
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
| | - Françoise Illien
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
| | - Sandrine Sagan
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
| | - Ludovic Carlier
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
| | - Olivier Lequin
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
| | - Patrick F. J. Fuchs
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
- Université de Paris, UFR Sciences du Vivant, 75013 Paris, France
| | - Emmanuelle Sachon
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
- Sorbonne Université, Mass Spectrometry Sciences Sorbonne Université, MS3U platform, UFR 926, UFR 927, Paris 75005, France
| | - Astrid Walrant
- Laboratoire des Biomolécules, LBM, Sorbonne Université, École normale supérieure, PSL University, CNRS, 75005 Paris, France
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4
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Kim J, Hemachandran S, Cheng AG, Ricci AJ. Identifying targets to prevent aminoglycoside ototoxicity. Mol Cell Neurosci 2022; 120:103722. [PMID: 35341941 PMCID: PMC9177639 DOI: 10.1016/j.mcn.2022.103722] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 03/14/2022] [Accepted: 03/19/2022] [Indexed: 12/21/2022] Open
Abstract
Aminoglycosides are potent antibiotics that are commonly prescribed worldwide. Their use carries significant risks of ototoxicity by directly causing inner ear hair cell degeneration. Despite their ototoxic side effects, there are currently no approved antidotes. Here we review recent advances in our understanding of aminoglycoside ototoxicity, mechanisms of drug transport, and promising sites for intervention to prevent ototoxicity.
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Affiliation(s)
- Jinkyung Kim
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Sriram Hemachandran
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alan G Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Anthony J Ricci
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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5
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Dhar G, Paikra SK, Mishra M. Aminoglycoside treatment alters hearing-related genes and depicts behavioral defects in Drosophila. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2022; 110:e21871. [PMID: 35150449 DOI: 10.1002/arch.21871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/30/2021] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
The hearing organ of Drosophila is present within the second segment of antennae. The hearing organ of Drosophila (Johnston's organ [JO]) shares much structural, developmental, and functional similarity with the vertebrate hearing organ (Organ of Corti). JO is evolving as a potential model system to examine the hearing-associated defects in vertebrates. In the vertebrates, aminoglycosides like gentamicin, kanamycin, and neomycin have been known to cause defects in the hearing organ. However, a complete mechanism of toxicity is not known. Taking the evolutionary conservation into account the current study aims to test various concentrations of aminoglycoside on the model organism, Drosophila melanogaster. The current study uses the oral route to check the toxicity of various aminoglycosides at different concentrations (50, 100, 150, 200, and 250 μg ml- 1 ). In Drosophila, many foreign particles enter the body through the gut via food. The aminoglycoside treated third instar larvae show defective crawling and sound avoidance behavior. The adult flies release lower amounts of acetylcholine esterase and higher amounts of reactive oxygen species than control untreated animals, accompanied by defective climbing and aggressive behavior. All these behavioral defects are further confirmed by the altered expression level of hearing genes such as nompC, inactive, nanchung, pyrexia. All the behavioral and genetic defects are reported as a readout of aminoglycoside toxicity.
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Affiliation(s)
- Gyanaseni Dhar
- Department of Life Science, Neural Developmental Biology Lab, National Institute of Technology, Rourkela, Rourkela, Odisha, India
| | - Sanjeev K Paikra
- Department of Life Science, Neural Developmental Biology Lab, National Institute of Technology, Rourkela, Rourkela, Odisha, India
| | - Monalisa Mishra
- Department of Life Science, Neural Developmental Biology Lab, National Institute of Technology, Rourkela, Rourkela, Odisha, India
- Centre for Nanomaterials, National Institute of technology Rourkela, Rourkela, Odisha, India
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6
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Pipatpolkai T, Quetschlich D, Stansfeld PJ. From Bench to Biomolecular Simulation: Phospholipid Modulation of Potassium Channels. J Mol Biol 2021; 433:167105. [PMID: 34139216 PMCID: PMC8361781 DOI: 10.1016/j.jmb.2021.167105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 06/09/2021] [Accepted: 06/10/2021] [Indexed: 12/05/2022]
Abstract
Potassium (K+) ion channels are crucial in numerous cellular processes as they hyperpolarise a cell through K+ conductance, returning a cell to its resting potential. K+ channel mutations result in multiple clinical complications such as arrhythmia, neonatal diabetes and migraines. Since 1995, the regulation of K+ channels by phospholipids has been heavily studied using a range of interdisciplinary methods such as cellular electrophysiology, structural biology and computational modelling. As a result, K+ channels are model proteins for the analysis of protein-lipid interactions. In this review, we will focus on the roles of lipids in the regulation of K+ channels, and how atomic-level structures, along with experimental techniques and molecular simulations, have helped guide our understanding of the importance of phospholipid interactions.
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Affiliation(s)
- Tanadet Pipatpolkai
- Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK; Department of Physiology Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK; OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PT, UK
| | - Daniel Quetschlich
- Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK; Department of Chemistry, South Parks Road, Oxford OX1 3QZ, UK
| | - Phillip J Stansfeld
- School of Life Sciences & Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
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Bugatti A, Caccuri F, Filippini F, Ravelli C, Caruso A. Binding to PI(4,5)P 2 is indispensable for secretion of B-cell clonogenic HIV-1 matrix protein p17 variants. J Biol Chem 2021; 297:100934. [PMID: 34273353 PMCID: PMC8350382 DOI: 10.1016/j.jbc.2021.100934] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 06/18/2021] [Accepted: 06/29/2021] [Indexed: 12/19/2022] Open
Abstract
HIV-1 matrix protein p17 variants (vp17s) derived from non-Hodgkin's lymphoma (NHL) tissues of HIV-1-seropositive (HIV+) patients promote B-cell growth by activating the Akt signaling pathway. It is fundamental to understand the role played by vp17s in producing a microenvironment that fosters lymphoma development and progression. Therefore, we asked whether vp17s could be secreted from infected cells in their biologically active form. In this study, we show that two B-cell growth-promoting vp17s, NHL-a101 and NHL-a102, characterized by amino acid insertions at position 117 to 118 (Ala-Ala) or 125 to 126 (Gly-Asn), respectively, are secreted from HIV-1-infected Jurkat T cells during the active phase of viral replication. Secretion of biologically active vp17s also occurred in HeLa cells nucleofected with a plasmid expressing the entire Gag gene, following proteolytic cleavage of the Gag precursor polyprotein (Pr55Gag) by cellular aspartyl proteases. Binding of Pr55Gag to phosphatidylinositol-(4,5)-bisphosphate was indispensable for allowing the unconventional secretion of both wildtype p17 and vp17s. Indeed, here we demonstrate that inhibition of Pr55Gag binding to phosphatidylinositol-(4,5)-bisphosphate by using neomycin, or its enzymatic depletion achieved by overexpression of 5ptaseIV, significantly impair the secretion of p17s. We also demonstrated that heparan sulfate proteoglycans were involved in tethering p17s at the cell surface. This finding opens up an interesting way for investigating whether tethered p17s on the surface of HIV-1 reservoirs may represent a likely target for immune-mediated killing.
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Affiliation(s)
- Antonella Bugatti
- Section of Microbiology, Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Francesca Caccuri
- Section of Microbiology, Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Federica Filippini
- Section of Microbiology, Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Cosetta Ravelli
- Section of Experimental Oncology and Immunology, Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Arnaldo Caruso
- Section of Microbiology, Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy.
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8
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Azzi A. Scaffold dependent role of the inositol 5'-phosphatase SHIP2, in regulation of oxidative stress induced apoptosis. Arch Biochem Biophys 2020; 697:108667. [PMID: 33181128 DOI: 10.1016/j.abb.2020.108667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/29/2020] [Accepted: 11/04/2020] [Indexed: 11/19/2022]
Abstract
Cell apoptosis is an important process that occurs during development or in response to stress stimuli such as oxidative stress. The serine-threonine kinase Akt enhances survival and suppress apoptosis. SHIP2 is known as a negative regulator of Akt. In addition to its lipid 5'-phosphatase activity, SHIP2 interacts and signals as a scaffolding complex with several proteins. Several findings have pointed out a possible role of SHIP2 in apoptosis regulation. However, the molecular mechanisms behind remain unknown. Using embryonic fibroblast lacking the lipid 5'-phosphatase domain as a genetic model system and human liver cancer cells treated with SHIP2 inhibitor (AS1949490), as a pharmacological model system. We provide the first evidence that SHIP2 regulates apoptosis independently of its 5'-phosphates activity. Indeed, absence of the 5'-phosphatase domain of SHIP2 did not prevent H2O2-induced apoptosis in fibroblasts. Whereas chemical inactivation or RNAi knockdown of SHIP2 blocked H2O2-induced apoptosis in HepG2 cells. We found that suppression of apoptosis upon SHIP2 inhibition is PI3K/Akt independent but rather MAP kinase dependent. In addition, we found that AS1949490 altered both 5'-phosphatase and scaffolding function of SHIP2. Indeed, AS1949490 mediated SHIP2 inhibition promotes protein complex formation of SHIP2 together with non-receptor tyrosine kinase SRC and ABL which in turn enhances PI3K/Akt and MAP kinase pathways activation. Dual inhibition of SRC/ABL blocked activation of both pathways upon SHIP2 inhibition and H2O2 treatment. Altogether, these findings indicate that SHIP2 protein play a determinant role in H2O2-induced apoptosis.
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Affiliation(s)
- Abdelhalim Azzi
- GIGA-Molecular Biology of Disease, GIGA-B34, Centre Hospitalier Universitaire Sart-Tilman, University of Liège, avenue de l'Hôpital 11, 4000, Liège, Belgium.
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Castro H, Bermeo K, Arenas I, Garcia DE. Maintenance of Ca V2.2 channel-current by PIP 2 unveiled by neomycin in sympathetic neurons of the rat. Arch Biochem Biophys 2020; 682:108261. [PMID: 31923392 DOI: 10.1016/j.abb.2020.108261] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 12/13/2019] [Accepted: 01/06/2020] [Indexed: 02/01/2023]
Abstract
Membrane lipids are key determinants in the regulation of voltage-gated ion channels. Phosphatidylinositol 4,5-bisphosphate (PIP2), a native membrane phospholipid, has been involved in the maintenance of the current amplitude and in the voltage-independent regulation of voltage-gated calcium channels (VGCC). However, the nature of the PIP2 regulation on VGCC has not been fully elucidated. This work aimed to investigate whether the interacting PIP2 electrostatic charges may account for maintaining the current amplitude of CaV2.2 channels. Furthermore, we tested whether charge shielding of PIP2 mimics the voltage-independent inhibition induced by M1 muscarinic acetylcholine receptor (M1R) activation. Therefore, neomycin, a polycation that has been shown to block electrostatic interactions of PIP2, was intracellularly dialyzed in superior cervical ganglion (SCG) neurons of the rat. Consistently, neomycin time-dependently diminished the calcium current amplitude letting the channel exhibit the hallmarks of the voltage-independent regulation. These results support that interacting PIP2 charges not only underly the maintenance of the channel-current but also that charge screening of PIP2 by itself unveils the voltage-independent features of CaV2.2 channels in SCG neurons.
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Affiliation(s)
- Hector Castro
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70250, C.P. 04510, CdMx, México
| | - Karina Bermeo
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70250, C.P. 04510, CdMx, México
| | - Isabel Arenas
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70250, C.P. 04510, CdMx, México
| | - David E Garcia
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70250, C.P. 04510, CdMx, México.
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Phan TK, Bindra GK, Williams SA, Poon IK, Hulett MD. Combating Human Pathogens and Cancer by Targeting Phosphoinositides and Their Metabolism. Trends Pharmacol Sci 2019; 40:866-882. [DOI: 10.1016/j.tips.2019.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 09/11/2019] [Accepted: 09/13/2019] [Indexed: 12/19/2022]
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11
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Tembo M, Wozniak KL, Bainbridge RE, Carlson AE. Phosphatidylinositol 4,5-bisphosphate (PIP 2) and Ca 2+ are both required to open the Cl - channel TMEM16A. J Biol Chem 2019; 294:12556-12564. [PMID: 31266809 DOI: 10.1074/jbc.ra118.007128] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 07/01/2019] [Indexed: 12/27/2022] Open
Abstract
Transmembrane member 16A (TMEM16A) is a widely expressed Ca2+-activated Cl- channel with various physiological functions ranging from mucosal secretion to regulating smooth muscle contraction. Understanding how TMEM16A controls these physiological processes and how its dysregulation may cause disease requires a detailed understanding of how cellular processes and second messengers alter TMEM16A channel gating. Here we assessed the regulation of TMEM16A gating by recording Ca2+-evoked Cl- currents conducted by endogenous TMEM16A channels expressed in Xenopus laevis oocytes, using the inside-out configuration of the patch clamp technique. During continuous application of Ca2+, we found that TMEM16A-conducted currents decay shortly after patch excision. Such current rundown is common among channels regulated by phosphatidylinositol 4,5-bisphosphate (PIP2). Thus, we sought to investigate a possible role of PIP2 in TMEM16A gating. Consistently, synthetic PIP2 rescued the current after rundown, and the application of PIP2 modulating agents altered the speed kinetics of TMEM16A current rundown. First, two PIP2 sequestering agents, neomycin and anti-PIP2, applied to the intracellular surface of excised patches sped up TMEM16A current rundown to nearly twice as fast. Conversely, rephosphorylation of phosphatidylinositol (PI) derivatives into PIP2 using Mg-ATP or inhibiting dephosphorylation of PIP2 using β-glycerophosphate slowed rundown by nearly 3-fold. Our results reveal that TMEM16A regulation is more complicated than it initially appeared; not only is Ca2+ necessary to signal TMEM16a opening, but PIP2 is also required. These findings improve our understanding of how the dysregulation of these pathways may lead to disease and suggest that targeting these pathways could have utility for potential therapies.
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Affiliation(s)
- Maiwase Tembo
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Katherine L Wozniak
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Rachel E Bainbridge
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Anne E Carlson
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260.
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12
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Caillaud MC. Anionic Lipids: A Pipeline Connecting Key Players of Plant Cell Division. FRONTIERS IN PLANT SCIENCE 2019; 10:419. [PMID: 31110508 PMCID: PMC6499208 DOI: 10.3389/fpls.2019.00419] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 03/19/2019] [Indexed: 05/23/2023]
Abstract
How cells position their division plane is a critical component of cell division. Indeed, it defines whether the two daughter cells divide symmetrically (with equal volumes) or not, and as such is critical for cell differentiation and lineage specification across eukaryotes. However, oriented cell divisions are of special significance for organisms with cell walls, such as plants, because their cells are embedded and cannot relocate. Correctly positioning the division plane is therefore of prevailing importance in plants, as it controls not only the occurrence of asymmetric cell division, but also tissue morphogenesis and organ integrity. While cytokinesis is executed in radically different manners in animals and plants, they both rely on the dynamic interplay between the cytoskeleton and membrane trafficking to precisely deliver molecular components to the future site of cell division. Recent research has shown that strict regulation of the levels and distribution of anionic lipids, which are minor components of the cell membrane's lipids, is required for successful cytokinesis in non-plant organisms. This review focused on the recent evidence pointing to whether such signaling lipids have roles in plant cell division.
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Affiliation(s)
- Marie-Cécile Caillaud
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon, France
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13
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Polyphosphoinositides in the nucleus: Roadmap of their effectors and mechanisms of interaction. Adv Biol Regul 2019; 72:7-21. [PMID: 31003946 DOI: 10.1016/j.jbior.2019.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/02/2019] [Accepted: 04/03/2019] [Indexed: 01/01/2023]
Abstract
Biomolecular interactions between proteins and polyphosphoinositides (PPIn) are essential in the regulation of the vast majority of cellular processes. Consequently, alteration of these interactions is implicated in the development of many diseases. PPIn are phosphorylated derivatives of phosphatidylinositol and consist of seven species with different phosphate combinations. PPIn signal by recruiting proteins via canonical domains or short polybasic motifs. Although their actions are predominantly documented on cytoplasmic membranes, six of the seven PPIn are present within the nucleus together with the PPIn kinases, phosphatases and phospholipases that regulate their turnover. Importantly, the contribution of nuclear PPIn in the regulation of nuclear processes has led to an increased recognition of their importance compared to their more accepted cytoplasmic roles. This review summarises our knowledge on the identification and functional characterisation of nuclear PPIn-effector proteins as well as their mode of interactions, which tend to favour polybasic motifs.
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14
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Solís C, Russell B. CapZ integrates several signaling pathways in response to mechanical stiffness. J Gen Physiol 2019; 151:660-669. [PMID: 30808692 PMCID: PMC6504289 DOI: 10.1085/jgp.201812199] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/13/2018] [Accepted: 02/06/2019] [Indexed: 12/22/2022] Open
Abstract
Changes in mechanical load, hormones, or metabolic stress provoke remodeling of the actin-based thin filaments within muscle fibers. Solís and Russell show that several signaling pathways converge at the actin-capping protein CapZ to regulate muscle fiber growth in response to mechanical stiffness and neurohumoral signaling. Muscle adaptation is a response to physiological demand elicited by changes in mechanical load, hormones, or metabolic stress. Cytoskeletal remodeling processes in many cell types are thought to be primarily regulated by thin filament formation due to actin-binding accessory proteins, such as the actin-capping protein. Here, we hypothesize that in muscle, the actin-capping protein (named CapZ) integrates signaling by a variety of pathways, including phosphorylation and phosphatidylinositol 4,5-bisphosphate (PIP2) binding, to regulate muscle fiber growth in response to mechanical load. To test this hypothesis, we assess mechanotransduction signaling that regulates muscle growth using neonatal rat ventricular myocytes cultured on substrates with the stiffness of the healthy myocardium (10 kPa), fibrotic myocardium (100 kPa), or glass. We investigate how PIP2 signaling affects CapZ using the PIP2 sequestering agent neomycin and the effect of PKC-mediated CapZ phosphorylation using the PKC-activating drug phorbol 12-myristate 13-acetate (PMA). Molecular simulations suggest that close interactions between PIP2 and the β-tentacle of CapZ are modified by phosphorylation at T267. Fluorescence recovery after photobleaching (FRAP) demonstrates that the kinetic binding constant of CapZ to sarcomeric thin filaments in living muscle cells increases with stiffness or PMA treatment but is diminished by PIP2 reduction. Furthermore, CapZ with a deletion of the β-tentacle that lacks the phosphorylation site T267 shows increased FRAP kinetics with lack of sensitivity to PMA treatment or PIP2 reduction. Förster resonance energy transfer (FRET) probes the molecular interactions between PIP2 and CapZ, which are decreased by PIP2 availability or by the β-tentacle truncation. These data suggest that CapZ is bound to actin tightly in the idle, locked state, with little phosphorylation or PIP2 binding. However, this tight binding is loosened in growth states triggered by mechanical stimuli such as substrate stiffness, which may have relevance to fibrotic heart disease.
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Affiliation(s)
- Christopher Solís
- Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Brenda Russell
- Department of Physiology and Biophysics and Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL
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15
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Apostolakos P, Livanos P, Giannoutsou E, Panteris E, Galatis B. The intracellular and intercellular cross-talk during subsidiary cell formation in Zea mays: existing and novel components orchestrating cell polarization and asymmetric division. ANNALS OF BOTANY 2018; 122:679-696. [PMID: 29346521 PMCID: PMC6215039 DOI: 10.1093/aob/mcx193] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 11/25/2017] [Indexed: 05/03/2023]
Abstract
Background Formation of stomatal complexes in Poaceae is the outcome of three asymmetric and one symmetric cell division occurring in particular leaf protodermal cells. In this definite sequence of cell division events, the generation of subsidiary cells is of particular importance and constitutes an attractive model for studying local intercellular stimulation. In brief, an induction stimulus emitted by the guard cell mother cells (GMCs) triggers a series of polarization events in their laterally adjacent protodermal cells. This signal determines the fate of the latter cells, forcing them to divide asymmetrically and become committed to subsidiary cell mother cells (SMCs). Scope This article summarizes old and recent structural and molecular data mostly derived from Zea mays, focusing on the interplay between GMCs and SMCs, and on the unique polarization sequence occurring in both cell types. Recent evidence suggests that auxin operates as an inducer of SMC polarization/asymmetric division. The intercellular auxin transport is facilitated by the distribution of a specific transmembrane auxin carrier and requires reactive oxygen species (ROS). Interestingly, the local differentiation of the common cell wall between SMCs and GMCs is one of the earliest features of SMC polarization. Leucine-rich repeat receptor-like kinases, Rho-like plant GTPases as well as the SCAR/WAVE regulatory complex also participate in the perception of the morphogenetic stimulus and have been implicated in certain polarization events in SMCs. Moreover, the transduction of the auxin signal and its function are assisted by phosphatidylinositol-3-kinase and the products of the catalytic activity of phospholipases C and D. Conclusion In the present review, the possible role(s) of each of the components in SMC polarization and asymmetric division are discussed, and an overall perspective on the mechanisms beyond these phenomena is provided.
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Affiliation(s)
- P Apostolakos
- Department of Botany, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - P Livanos
- Department of Botany, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - E Giannoutsou
- Department of Botany, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - E Panteris
- Department of Botany, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Macedonia, Greece
| | - B Galatis
- Department of Botany, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
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16
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Mu L, Tu Z, Miao L, Ruan H, Kang N, Hei Y, Chen J, Wei W, Gong F, Wang B, Du Y, Ma G, Amerein MW, Xia T, Shi Y. A phosphatidylinositol 4,5-bisphosphate redistribution-based sensing mechanism initiates a phagocytosis programing. Nat Commun 2018; 9:4259. [PMID: 30323235 PMCID: PMC6189171 DOI: 10.1038/s41467-018-06744-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 09/20/2018] [Indexed: 12/30/2022] Open
Abstract
Phagocytosis is one of the earliest cellular functions, developing approximately 2 billion years ago. Although FcR-based phagocytic signaling is well-studied, how it originated from ancient phagocytosis is unknown. Lipid redistribution upregulates a phagocytic program recapitulating FcR-based phagocytosis with complete dependence on Src family kinases, Syk, and phosphoinositide 3-kinases (PI3K). Here we show that in phagocytes, an atypical ITAM sequence in the ancient membrane anchor protein Moesin transduces signal without receptor activation. Plasma membrane deformation created by solid structure binding generates phosphatidylinositol 4,5-bisphosphate (PIP2) accumulation at the contact site, which binds the Moesin FERM domain and relocalizes Syk to the membrane via the ITAM motif. Phylogenic analysis traces this signaling using PI3K and Syk to 0.8 billion years ago, earlier than immune receptor signaling. The proposed general model of solid structure phagocytosis implies a preexisting lipid redistribution-based activation platform collecting intracellular signaling components for the emergence of immune receptors.
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Affiliation(s)
- Libing Mu
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Institute for Immunology and Department of Basic Medical Sciences, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Medicine; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Zhongyuan Tu
- Department of Microbiology, Immunology & Infectious Diseases and Snyder Institute, University of Calgary, Calgary, T2N 4N1, AB, Canada
| | - Lin Miao
- Institute for Immunology and Department of Basic Medical Sciences, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Medicine; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
- School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
| | - Hefei Ruan
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Institute for Immunology and Department of Basic Medical Sciences, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Medicine; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Ning Kang
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Institute for Immunology and Department of Basic Medical Sciences, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Medicine; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yongzhen Hei
- Institute for Immunology and Department of Basic Medical Sciences, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Medicine; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jiahuan Chen
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Institute for Immunology and Department of Basic Medical Sciences, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Medicine; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Wei Wei
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China
| | - Fangling Gong
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China
| | - Bingjie Wang
- Department of Biomedical Engineering, School of Medicine, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Tsinghua University, Beijing, 100084, China
| | - Yanan Du
- Department of Biomedical Engineering, School of Medicine, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Tsinghua University, Beijing, 100084, China
| | - Guanghui Ma
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China
| | - Matthias W Amerein
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, T2N 4N1, AB, Canada
- Snyder Institute of Chronic Diseases, University of Calgary, Calgary, T2N 4N1, AB, Canada
| | - Tie Xia
- School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Institute for Immunology and Department of Basic Medical Sciences, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Medicine; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China.
| | - Yan Shi
- School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Institute for Immunology and Department of Basic Medical Sciences, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Medicine; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China.
- Department of Microbiology, Immunology & Infectious Diseases and Snyder Institute, University of Calgary, Calgary, T2N 4N1, AB, Canada.
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Dopamine Triggers the Maturation of Striatal Spiny Projection Neuron Excitability during a Critical Period. Neuron 2018; 99:540-554.e4. [PMID: 30057204 DOI: 10.1016/j.neuron.2018.06.044] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 03/20/2018] [Accepted: 06/29/2018] [Indexed: 01/11/2023]
Abstract
Neural circuits are formed and refined during childhood, including via critical changes in neuronal excitability. Here, we investigated the ontogeny of striatal intrinsic excitability. We found that dopamine neurotransmission increases from the first to the third postnatal week in mice and precedes the reduction in spiny projection neuron (SPN) intrinsic excitability during the fourth postnatal week. In mice developmentally deficient for striatal dopamine, direct pathway D1-SPNs failed to undergo maturation of excitability past P18 and maintained hyperexcitability into adulthood. We found that the absence of D1-SPN maturation was due to altered phosphatidylinositol 4,5-biphosphate dynamics and a consequent lack of normal ontogenetic increases in Kir2 currents. Dopamine replacement corrected these deficits in SPN excitability when provided from birth or during a specific period of juvenile development (P18-P28), but not during adulthood. These results identify a sensitive period of dopamine-dependent striatal maturation, with implications for the pathophysiology and treatment of neurodevelopmental disorders.
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18
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Kim SO, Jackman JA, Elazar M, Cho SJ, Glenn JS, Cho NJ. Quantitative Evaluation of Viral Protein Binding to Phosphoinositide Receptors and Pharmacological Inhibition. Anal Chem 2017; 89:9742-9750. [PMID: 28809547 PMCID: PMC5724528 DOI: 10.1021/acs.analchem.7b01568] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
There is significant interest in developing analytical methods to characterize molecular recognition events between proteins and phosphoinositides, which are a medically important class of carbohydrate-functionalized lipids. Within this scope, one area of high priority involves quantitatively evaluating drug candidates that pharmacologically inhibit protein-phosphoinositide interactions. As full-length proteins are often difficult to produce, establishing methods to study these interactions with shorter, bioactive peptides would be advantageous. Herein, we report an atomic force microscopy (AFM)-based force spectroscopic approach to detect the specific interaction between an amphipathic, α-helical (AH) peptide derived from the hepatitis C virus NS5A protein and its biological target, the phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] phosphoinositide receptor. After optimization of the peptide tethering strategy and measurement parameters, the binding specificity of AH peptide for PI(4,5)P2 receptors was comparatively evaluated across a panel of phosphoinositides and the influence of ionic strength on AH-PI(4,5)P2 binding strength was tested. Importantly, these capabilities were translated into the development of a novel experimental methodology to determine the inhibitory activity of a small-molecule drug candidate acting against the AH-PI(4,5)P2 interaction, and extracted kinetic parameters agree well with literature values obtained by conventional biochemical methods. Taken together, our findings provide a nanomechanical basis for explaining the high binding specificity of the NS5A AH to PI(4,5)P2 receptors, in turn establishing an analytical framework to study phosphoinositide-binding viral peptides and proteins as well as a broadly applicable approach to evaluate candidate inhibitors of protein-phosphoinositide interactions.
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Affiliation(s)
- Seong-Oh Kim
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Drive, 637553 Singapore
| | - Joshua A Jackman
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Drive, 637553 Singapore.,Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine , Stanford, California 94305, United States
| | - Menashe Elazar
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine , Stanford, California 94305, United States
| | - Sang-Joon Cho
- Advanced Institute of Convergence Technology, Seoul National University , Suwon 443-270, South Korea
| | - Jeffrey S Glenn
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine , Stanford, California 94305, United States.,Veterans Administration Medical Center , Palo Alto, California 94304, United States
| | - Nam-Joon Cho
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Drive, 637553 Singapore.,School of Chemical and Biomedical Engineering, Nanyang Technological University , 62 Nanyang Drive, 637459 Singapore
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19
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O’Sullivan ME, Perez A, Lin R, Sajjadi A, Ricci AJ, Cheng AG. Towards the Prevention of Aminoglycoside-Related Hearing Loss. Front Cell Neurosci 2017; 11:325. [PMID: 29093664 PMCID: PMC5651232 DOI: 10.3389/fncel.2017.00325] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 09/30/2017] [Indexed: 01/08/2023] Open
Abstract
Aminoglycosides are potent antibiotics deployed worldwide despite their known side-effect of sensorineural hearing loss. The main etiology of this sensory deficit is death of inner ear sensory hair cells selectively triggered by aminoglycosides. For decades, research has sought to unravel the molecular events mediating sensory cell demise, emphasizing the roles of reactive oxygen species and their potentials as therapeutic targets. Studies in recent years have revealed candidate transport pathways including the mechanotransducer channel for drug entry into sensory cells. Once inside sensory cells, intracellular targets of aminoglycosides, such as the mitochondrial ribosomes, are beginning to be elucidated. Based on these results, less ototoxic aminoglycoside analogs are being generated and may serve as alternate antimicrobial agents. In this article, we review the latest findings on mechanisms of aminoglycoside entry into hair cells, their intracellular actions and potential therapeutic targets for preventing aminoglycoside ototoxicity.
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Affiliation(s)
- Mary E. O’Sullivan
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Adela Perez
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Randy Lin
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Autefeh Sajjadi
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Anthony J. Ricci
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, United States
- *Correspondence: Anthony J. Ricci Alan G. Cheng
| | - Alan G. Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
- *Correspondence: Anthony J. Ricci Alan G. Cheng
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20
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Phan TK, Lay FT, Poon IKH, Hinds MG, Kvansakul M, Hulett MD. Human β-defensin 3 contains an oncolytic motif that binds PI(4,5)P2 to mediate tumour cell permeabilisation. Oncotarget 2016; 7:2054-69. [PMID: 26657293 PMCID: PMC4811302 DOI: 10.18632/oncotarget.6520] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 11/24/2015] [Indexed: 11/25/2022] Open
Abstract
Cationic antimicrobial peptides (CAPs), including taxonomically diverse defensins, are innate defense molecules that display potent antimicrobial and immunomodulatory activities. Specific CAPs have also been shown to possess anticancer activities; however, their mechanisms of action are not well defined. Recently, the plant defensin NaD1 was shown to induce tumour cell lysis by directly binding to the plasma membrane phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). The NaD1–lipid interaction was structurally defined by X-ray crystallography, with the defensin forming a dimer that binds PI(4,5)P2 via its cationic β2-β3 loops in a ‘cationic grip’ conformation. In this study, we show that human β-defensin 3 (HBD-3) contains a homologous β2-β3 loop that binds phosphoinositides. The binding of HBD-3 to PI(4,5)P2 was shown to be critical for mediating cytolysis of tumour cells, suggesting a conserved mechanism of action for defensins across diverse species. These data not only identify an evolutionary conservation of CAP structure and function for lipid binding, but also suggest that PIP-binding CAPs could be exploited for novel multifunction therapeutics.
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Affiliation(s)
- Thanh Kha Phan
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Fung T Lay
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Ivan K H Poon
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Mark G Hinds
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Marc Kvansakul
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - Mark D Hulett
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086, Australia
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21
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Grigoriev PA, Matveeva NB, Teplov VA. The autowave electromechanical activity of the Physarum polycephalum plasmodium. Biophysics (Nagoya-shi) 2016. [DOI: 10.1134/s0006350916050080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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22
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Caccuri F, Iaria ML, Campilongo F, Varney K, Rossi A, Mitola S, Schiarea S, Bugatti A, Mazzuca P, Giagulli C, Fiorentini S, Lu W, Salmona M, Caruso A. Cellular aspartyl proteases promote the unconventional secretion of biologically active HIV-1 matrix protein p17. Sci Rep 2016; 6:38027. [PMID: 27905556 PMCID: PMC5131311 DOI: 10.1038/srep38027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 11/03/2016] [Indexed: 11/24/2022] Open
Abstract
The human immune deficiency virus type 1 (HIV-1) matrix protein p17 (p17), although devoid of a signal sequence, is released by infected cells and detected in blood and in different organs and tissues even in HIV-1-infected patients undergoing successful combined antiretroviral therapy (cART). Extracellularly, p17 deregulates the function of different cells involved in AIDS pathogenesis. The mechanism of p17 secretion, particularly during HIV-1 latency, still remains to be elucidated. A recent study showed that HIV-1-infected cells can produce Gag without spreading infection in a model of viral latency. Here we show that in Gag-expressing cells, secretion of biologically active p17 takes place at the plasma membrane and occurs following its interaction with phosphatidylinositol-(4,5)-bisphosphate and its subsequent cleavage from the precursor Gag (Pr55Gag) operated by cellular aspartyl proteases. These enzymes operate a more complex Gag polypeptide proteolysis than the HIV-1 protease, thus hypothetically generating slightly truncated or elongated p17s in their C-terminus. A 17 C-terminal residues excised p17 was found to be structurally and functionally identical to the full-length p17 demonstrating that the final C-terminal region of p17 is irrelevant for the protein’s biological activity. These findings offer new opportunities to identify treatment strategies for inhibiting p17 release in the extracellular microenvironment.
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Affiliation(s)
- Francesca Caccuri
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Maria Luisa Iaria
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Federica Campilongo
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Kristen Varney
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Alessandro Rossi
- IRCCS Istituto di Ricerche Farmacologiche "Mario Negri" Milan, Italy
| | - Stefania Mitola
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Silvia Schiarea
- IRCCS Istituto di Ricerche Farmacologiche "Mario Negri" Milan, Italy
| | - Antonella Bugatti
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Pietro Mazzuca
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Cinzia Giagulli
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Simona Fiorentini
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
| | - Wuyuan Lu
- Institute of Human Virology, University of Maryland, Baltimore, Maryland, USA
| | - Mario Salmona
- IRCCS Istituto di Ricerche Farmacologiche "Mario Negri" Milan, Italy
| | - Arnaldo Caruso
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy
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23
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Bleackley MR, Payne JAE, Hayes BME, Durek T, Craik DJ, Shafee TMA, Poon IKH, Hulett MD, van der Weerden NL, Anderson MA. Nicotiana alata Defensin Chimeras Reveal Differences in the Mechanism of Fungal and Tumor Cell Killing and an Enhanced Antifungal Variant. Antimicrob Agents Chemother 2016; 60:6302-12. [PMID: 27503651 PMCID: PMC5038239 DOI: 10.1128/aac.01479-16] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 08/03/2016] [Indexed: 01/07/2023] Open
Abstract
The plant defensin NaD1 is a potent antifungal molecule that also targets tumor cells with a high efficiency. We examined the features of NaD1 that contribute to these two activities by producing a series of chimeras with NaD2, a defensin that has relatively poor activity against fungi and no activity against tumor cells. All plant defensins have a common tertiary structure known as a cysteine-stabilized α-β motif which consists of an α helix and a triple-stranded β-sheet stabilized by four disulfide bonds. The chimeras were produced by replacing loops 1 to 7, the sequences between each of the conserved cysteine residues on NaD1, with the corresponding loops from NaD2. The loop 5 swap replaced the sequence motif (SKILRR) that mediates tight binding with phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and is essential for the potent cytotoxic effect of NaD1 on tumor cells. Consistent with previous reports, there was a strong correlation between PI(4,5)P2 binding and the tumor cell killing activity of all of the chimeras. However, this correlation did not extend to antifungal activity. Some of the loop swap chimeras were efficient antifungal molecules, even though they bound poorly to PI(4,5)P2, suggesting that additional mechanisms operate against fungal cells. Unexpectedly, the loop 1B swap chimera was 10 times more active than NaD1 against filamentous fungi. This led to the conclusion that defensin loops have evolved as modular components that combine to make antifungal molecules with variable mechanisms of action and that artificial combinations of loops can increase antifungal activity compared to that of the natural variants.
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Affiliation(s)
- Mark R Bleackley
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Jennifer A E Payne
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Brigitte M E Hayes
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Thomas Durek
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Thomas M A Shafee
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Ivan K H Poon
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Mark D Hulett
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Nicole L van der Weerden
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Marilyn A Anderson
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
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24
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Merlin inhibits Wnt/β-catenin signaling by blocking LRP6 phosphorylation. Cell Death Differ 2016; 23:1638-47. [PMID: 27285107 DOI: 10.1038/cdd.2016.54] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 05/04/2016] [Accepted: 05/10/2016] [Indexed: 12/20/2022] Open
Abstract
Merlin, encoded by the NF2 gene, is a tumor suppressor that acts by inhibiting mitogenic signaling and is mutated in Neurofibromatosis type II (NF2) disease, although its molecular mechanism is not fully understood. Here, we observed that Merlin inhibited Wnt/β-catenin signaling by blocking phosphorylation of LRP6, which is necessary for Wnt signal transduction, whereas mutated Merlin in NF2 patients did not. Treatment with Wnt3a enhanced phosphorylation of Ser518 in Merlin via activation of PAK1 in a PIP2-dependent manner. Phosphorylated Merlin dissociated from LRP6, allowing for phosphorylation of LRP6. Tissues from NF2 patients exhibited higher levels of β-catenin, and proliferation of RT4-D6P2T rat schwannoma cells was significantly reduced by treatment with chemical inhibitors of Wnt/β-catenin signaling. Taken together, our findings suggest that sustained activation of Wnt/β-catenin signaling due to abrogation of Merlin-mediated inhibition of LRP6 phosphorylation may be a cause of NF2 disease.
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Charge Shielding of PIP2 by Cations Regulates Enzyme Activity of Phospholipase C. PLoS One 2015; 10:e0144432. [PMID: 26658739 PMCID: PMC4676720 DOI: 10.1371/journal.pone.0144432] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/18/2015] [Indexed: 11/19/2022] Open
Abstract
Hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) of the plasma membrane by phospholipase C (PLC) generates two critical second messengers, inositol-1,4,5-trisphosphate and diacylglycerol. For the enzymatic reaction, PIP2 binds to positively charged amino acids in the pleckstrin homology domain of PLC. Here we tested the hypothesis that positively charged divalent and multivalent cations accumulate around the negatively charged PIP2, a process called electrostatic charge shielding, and therefore inhibit electrostatic PIP2-PLC interaction. This charge shielding of PIP2 was measured quantitatively with an in vitro enzyme assay using WH-15, a PIP2 analog, and various recombinant PLC proteins (β1, γ1, and δ1). Reduction of PLC activity by divalent cations, polyamines, and neomycin was well described by a theoretical model considering accumulation of cations around PIP2 via their electrostatic interaction and chemical binding. Finally, the charge shielding of PIP2 was also observed in live cells. Perfusion of the cations into cells via patch clamp pipette reduced PIP2 hydrolysis by PLC as triggered by M1 muscarinic receptors with a potency order of Mg2+ < spermine4+ < neomycin6+. Accumulation of divalent cations into cells through divalent-permeable TRPM7 channel had the same effect. Altogether our results suggest that Mg2+ and polyamines modulate the activity of PLCs by controlling the amount of free PIP2 available for the enzymes and that highly charged biomolecules can be inactivated by counterions electrostatically.
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Ezrin is a Major Regulator of Membrane Tension in Epithelial Cells. Sci Rep 2015; 5:14700. [PMID: 26435322 PMCID: PMC4592969 DOI: 10.1038/srep14700] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 09/07/2015] [Indexed: 11/12/2022] Open
Abstract
Plasma membrane tension is responsible for a variety of cellular functions such as motility, cell division, and endocytosis. Since membrane tension is dominated by the attachment of the actin cortex to the inner leaflet of the plasma membrane, we investigated the importance of ezrin, a major cross-linker of the membrane-cytoskeleton interface, for cellular mechanics of confluent MDCK II cells. For this purpose, we carried out ezrin depletion experiments and also enhanced the number of active ezrin molecules at the interface. Mechanical properties were assessed by force indentation experiments followed by membrane tether extraction. PIP2 micelles were injected into individual living cells to reinforce the linkage between plasma membrane and actin-cortex, while weakening of this connection was reached by ezrin siRNA and administration of the inhibitors neomycin and NSC 668394, respectively. We observed substantial stiffening of cells and an increase in membrane tension after addition of PIP2 micelles. In contrast, reduction of active ezrin led to a decrease of membrane tension accompanied by loss of excess surface area, increase in cortical tension, remodelling of actin cytoskeleton, and reduction of cell height. The data confirm the importance of the ezrin-mediated connection between plasma membrane and cortex for cellular mechanics and cell morphology.
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Matveeva NB, Beylina SI, Klyueva AA, Teplov VA. Involvement of phosphatidylinositol 4,5-bisphosphate binding proteins in the generation of contractile oscillations in the Physarum polycephalum plasmodium. Biophysics (Nagoya-shi) 2014. [DOI: 10.1134/s0006350914050157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Bista P, Pawlowski M, Cerina M, Ehling P, Leist M, Meuth P, Aissaoui A, Borsotto M, Heurteaux C, Decher N, Pape HC, Oliver D, Meuth SG, Budde T. Differential phospholipase C-dependent modulation of TASK and TREK two-pore domain K+ channels in rat thalamocortical relay neurons. J Physiol 2014; 593:127-44. [PMID: 25556792 DOI: 10.1113/jphysiol.2014.276527] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 09/23/2014] [Indexed: 01/10/2023] Open
Abstract
KEY POINTS During the behavioural states of sleep and wakefulness thalamocortical relay neurons fire action potentials in high frequency bursts or tonic sequences, respectively. The modulation of specific K(+) channel types, termed TASK and TREK, allows these neurons to switch between the two modes of activity. In this study we show that the signalling lipids phosphatidylinositol 4,5-bisphosphate (PIP2) and diacylglycerol (DAG), which are components of their membrane environment, switch on and shut off TREK and TASK channels, respectively. These channel modulations contribute to a better understanding of the molecular basis of the effects of neurotransmitters such as ACh which are released by the brainstem arousal system. The present report introduces PIP2 and DAG as new elements of signal transduction in the thalamus. The activity of two-pore domain potassium channels (K2P ) regulates the excitability and firing modes of thalamocortical (TC) neurons. In particular, the inhibition of two-pore domain weakly inwardly rectifying K(+) channel (TWIK)-related acid-sensitive K(+) (TASK) channels and TWIK-related K(+) (TREK) channels, as a consequence of the stimulation of muscarinic ACh receptors (MAChRs) which are coupled to phosphoinositide-specific phospholipase C (PLCβ), induces a shift from burst to tonic firing. By using a whole cell patch-clamp approach, the contribution of the membrane-bound second messenger molecules phosphatidylinositol 4,5-bisphosphate (PIP2 ) and diacylglycerol (DAG) acting downstream of PLCβ was probed. The standing outward current (ISO ) was used to monitor the current through TASK and TREK channels in TC neurons. By exploiting different manoeuvres to change the intracellular PIP2 level in TC neurons, we here show that the scavenging of PIP2 (by neomycin) results in an increased muscarinic effect on ISO whereas increased availability of PIP2 (inclusion to the patch pipette; histone-based carrier) decreased muscarinic signalling. The degree of muscarinic inhibition specifically depends on phosphatidylinositol phosphate (PIP) and PIP2 but no other phospholipids (phosphatidic acid, phosphatidylserine). The use of specific blockers revealed that PIP2 is targeting TREK but not TASK channels. Furthermore, we demonstrate that the inhibition of TASK channels is induced by the application of the DAG analogue 1-oleoyl-2-acetyl-sn-glycerol (OAG). Under current clamp conditions the activation of MAChRs and PLCβ as well as the application of OAG resulted in membrane depolarization, while PIP2 application via histone carrier induced a hyperpolarization. These results demonstrate a differential role of PIP2 and DAG in K2P channel modulation in native neurons which allows a fine-tuned inhibition of TREK (via PIP2 depletion) and TASK (via DAG) channels following MAChR stimulation.
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Affiliation(s)
- Pawan Bista
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Robert-Koch-Straße 27a, D-48149, Münster, Germany
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Mori MX, Inoue R. New experimental trends for phosphoinositides research on ion transporter/channel regulation. J Pharmacol Sci 2014; 126:186-97. [PMID: 25367262 DOI: 10.1254/jphs.14r14cp] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Phosphoinositides(4,5)-bisphosphates [PI(4,5)P2] critically controls membrane excitability, the disruption of which leads to pathophysiological states. PI(4,5)P2 plays a primary role in regulating the conduction and gating properties of ion channels/transporters, through electrostatic and hydrophobic interactions that allow direct associations. In recent years, the development of many molecular tools have brought deep insights into the mechanisms underlying PI(4,5)P2-mediated regulation. This review summarizes the methods currently available to manipulate the cell membrane PI(4,5)P2 level including pharmacological interventions as well as newly designed molecular tools. We concisely introduce materials and experimental designs suitable for the study of PI(4,5)P2-mediated regulation of ion-conducting molecules, in order to assist researchers who are interested in this area. It is our further hope that the knowledge introduced in this review will help to promote our understanding about the pathology of diseases such as cardiac arrhythmias, bipolar disorders, and Alzheimer's disease which are somehow associated with a disruption of PI(4,5)P2 metabolism.
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Affiliation(s)
- Masayuki X Mori
- Department of Synthetic Chemistry and Biological Chemistry, School of Engineering, Kyoto University, Japan
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30
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Chemical intervention tools to probe phosphoinositide-dependent signalling. Biochem Soc Trans 2014; 42:1343-8. [DOI: 10.1042/bst20140186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Chemical intervention tools have been beneficial to many investigations elucidating signalling networks and interactions. The present review summarizes the current status of chemical tools to probe phosphoinositide metabolism and signalling. In particular, phosphoinositide-targeting tools are compared with protein-targeting tools with respect to their unique advantages and possible applications.
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Yu Y, Boyer NP, Zhang C. Three structurally similar odorants trigger distinct signaling pathways in a mouse olfactory neuron. Neuroscience 2014; 275:194-210. [PMID: 24929067 DOI: 10.1016/j.neuroscience.2014.05.063] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 04/08/2014] [Accepted: 05/22/2014] [Indexed: 12/20/2022]
Abstract
In the mammalian olfactory system, one olfactory sensory neuron (OSN) expresses a single olfactory receptor gene. By calcium imaging of individual OSNs in intact mouse olfactory turbinates, we observed that a subset of OSNs (Ho-OSNs) located in the most ventral olfactory receptor zone can mediate distinct signaling pathways when activated by structurally similar ligands. Calcium imaging showed that Ho-OSNs were highly sensitive to 2-heptanone, heptaldehyde and cis-4-heptenal. 2-heptanone-evoked intracellular calcium elevation was mediated by cAMP signaling while heptaldehyde triggered the diacylglycerol pathway. An increase of intracellular calcium evoked by cis-4-heptenal was due to a combination of activation mediated by the adenylate cyclase pathway and suppression generated by phospholipase C signaling. Pharmacological studies demonstrated that novel mechanisms were involved in the phospholipase C-mediated intracellular calcium changes. Binary-mixture studies and cross-adaptation data indicate that three odorants acted on the same olfactory receptor. The feature that an olfactory receptor mediates multiple signaling pathways was specific for Ho-OSNs and not established in another population of OSNs characterized. Our study suggests that distinct signaling pathways triggered by ligand-induced conformational changes of an olfactory receptor constitute a complex information process mechanism in olfactory transduction. This study has important implications beyond olfaction in that it provides insights of plasticity and complexity of G-protein-coupled receptor activation and signal transduction.
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Affiliation(s)
- Y Yu
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, 3101 S. Dearborn Street, Chicago, IL 60616, USA
| | - N P Boyer
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425, USA; Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA
| | - C Zhang
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, 3101 S. Dearborn Street, Chicago, IL 60616, USA.
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32
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Tsai HC, Chung KR. Calcineurin phosphatase and phospholipase C are required for developmental and pathological functions in the citrus fungal pathogen Alternaria alternata. MICROBIOLOGY-SGM 2014; 160:1453-1465. [PMID: 24763426 DOI: 10.1099/mic.0.077818-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Excessive Ca(2+) or compounds interfering with phosphoinositide cycling have been found to inhibit the growth of the tangerine pathotype of Alternaria alternata, suggesting a crucial role of Ca(2+) homeostasis in this pathotype. The roles of PLC1, a phospholipase C-coding gene and CAL1, a calcineurin phosphatase-coding gene were investigated. Targeted gene disruption showed that both PLC1 and CAL1 were required for vegetative growth, conidial formation and pathogenesis in citrus. Fungal strains lacking PLC1 or CAL1 exhibited extremely slow growth and induced small lesions on calamondin leaves. Δplc1 mutants produced fewer conidia, which germinated at slower rates than wild-type. Δcal1 mutants produced abnormal hyphae and failed to produce any mature conidia, but instead produced highly melanized bulbous hyphae with distinct septae. Fluorescence microscopy using Fluo-3 dye as a Ca(2+) indicator revealed that the Δplc1 mutant hyphae emitted stronger cytosolic fluorescence, and the Δcal1 mutant hyphae emitted less cytosolic fluorescence, than those of wild-type. Infection assessed on detached calamondin leaves revealed that application of CaCl2 or neomycin 24 h prior to inoculation provided protection against Alt. alternata. These data indicate that a dynamic equilibrium of cellular Ca(2+) is critical for developmental and pathological processes of Alt. alternata.
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Affiliation(s)
- Hsieh-Chin Tsai
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
| | - Kuang-Ren Chung
- Department of Plant Pathology, IFAS, University of Florida, Gainesville, FL 32611, USA.,Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
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Citrus bergamia Risso Elevates Intracellular Ca (2+) in Human Vascular Endothelial Cells due to Release of Ca (2+) from Primary Intracellular Stores. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:759615. [PMID: 24348719 PMCID: PMC3857908 DOI: 10.1155/2013/759615] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 10/28/2013] [Accepted: 10/28/2013] [Indexed: 11/21/2022]
Abstract
The purpose of the present study is to examine the effects of essential oil of Citrus bergamia Risso (bergamot, BEO) on intracellular Ca2+ in human umbilical vein endothelial cells. Fura-2 fluorescence was used to examine changes in intracellular Ca2+ concentration [Ca2+]i
. In the presence of extracellular Ca2+, BEO increased [Ca2+]i
, which was partially inhibited by a nonselective Ca2+ channel blocker La3+. In Ca2+-free extracellular solutions, BEO increased [Ca2+]i
in a concentration-dependent manner, suggesting that BEO mobilizes intracellular Ca2+. BEO-induced [Ca2+]i
increase was partially inhibited by a Ca2+-induced Ca2+ release inhibitor dantrolene, a phospholipase C inhibitor U73122, and an inositol 1,4,5-triphosphate (IP3)-gated Ca2+ channel blocker, 2-aminoethoxydiphenyl borane (2-APB). BEO also increased [Ca2+]i
in the presence of carbonyl cyanide m-chlorophenylhydrazone, an inhibitor of mitochondrial Ca2+ uptake. In addition, store-operated Ca2+ entry (SOC) was potentiated by BEO. These results suggest that BEO mobilizes Ca2+ from primary intracellular stores via Ca2+-induced and IP3-mediated Ca2+ release and affect promotion of Ca2+ influx, likely via an SOC mechanism.
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Distinct biophysical mechanisms of focal adhesion kinase mechanoactivation by different extracellular matrix proteins. Proc Natl Acad Sci U S A 2013; 110:19372-7. [PMID: 24222685 DOI: 10.1073/pnas.1307405110] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Matrix mechanics controls cell fate by modulating the bonds between integrins and extracellular matrix (ECM) proteins. However, it remains unclear how fibronectin (FN), type 1 collagen, and their receptor integrin subtypes distinctly control force transmission to regulate focal adhesion kinase (FAK) activity, a crucial molecular signal governing cell adhesion/migration. Here we showed, using a genetically encoded FAK biosensor based on fluorescence resonance energy transfer, that FN-mediated FAK activation is dependent on the mechanical tension, which may expose its otherwise hidden FN synergy site to integrin α5. In sharp contrast, the ligation between the constitutively exposed binding motif of type 1 collagen and its receptor integrin α2 was surprisingly tension-independent to induce sufficient FAK activation. Although integrin α subunit determines mechanosensitivity, the ligation between α subunit and the ECM proteins converges at the integrin β1 activation to induce FAK activation. We further discovered that the interaction of the N-terminal protein 4.1/ezrin/redixin/moesin basic patch with phosphatidylinositol 4,5-biphosphate is crucial during cell adhesion to maintain the FAK activation from the inhibitory effect of nearby protein 4.1/ezrin/redixin/moesin acidic sites. Therefore, different ECM proteins either can transmit or can shield from mechanical forces to regulate cellular functions, with the accessibility of ECM binding motifs by their specific integrin α subunits determining the biophysical mechanisms of FAK activation during mechanotransduction.
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Chang P, Walker MC, Williams RSB. Seizure-induced reduction in PIP3 levels contributes to seizure-activity and is rescued by valproic acid. Neurobiol Dis 2013; 62:296-306. [PMID: 24148856 PMCID: PMC3898270 DOI: 10.1016/j.nbd.2013.10.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 09/11/2013] [Accepted: 10/11/2013] [Indexed: 12/31/2022] Open
Abstract
Phosphatidylinositol (3–5) trisphosphate (PIP3) is a central regulator of diverse neuronal functions that are critical for seizure progression, however its role in seizures is unclear. We have recently hypothesised that valproic acid (VPA), one of the most commonly used drugs for the treatment of epilepsy, may target PIP3 signalling as a therapeutic mode of action. Here, we show that seizure induction using kainic acid in a rat in vivo epilepsy model resulted in a decrease in hippocampal PIP3 levels and reduced protein kinase B (PKB/AKT) phosphorylation, measured using ELISA mass assays and Western blot analysis, and both changes were restored following VPA treatment. These finding were reproduced in cultured rat hippocampal primary neurons and entorhinal cortex–hippocampal slices during exposure to the GABA(A) receptor antagonist pentylenetetrazol (PTZ), which is widely used to generate seizures and seizure-like (paroxysmal) activity. Moreover, VPA's effect on paroxysmal activity in the PTZ slice model is blocked by phosphatidylinositol 3-kinase (PI3K) inhibition or PIP2 sequestration by neomycin, indicating that VPA's efficacy is dependent upon PIP3 signalling. PIP3 depletion following PTZ treatment may also provide a positive feedback loop, since enhancing PIP3 depletion increases, and conversely, reducing PIP3 dephosphorylation reduces paroxysmal activity and this effect is dependent upon AMPA receptor activation. Our results therefore indicate that PIP3 depletion occurs with seizure activity, and that VPA functions to reverse these effects, providing a novel mechanism for VPA in epilepsy treatment. In vivo seizure induction (using kainic acid) reduces hippocampal PIP3 levels. In vivo seizure induction (using kainic acid) reduces hippocampal phospho-PKB levels. Valproic acid protects against these reductions under seizure conditions only. Similar regulation is seen with PTZ-induced in vitro seizure activity. Seizure-induced PIP3 reduction causes a feedback activation of seizure activity.
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Affiliation(s)
- Pishan Chang
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Matthew C Walker
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, WC1N 3BG, UK.
| | - Robin S B Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK.
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Kaposi's sarcoma-associated herpesvirus-positive primary effusion lymphoma tumor formation in NOD/SCID mice is inhibited by neomycin and neamine blocking angiogenin's nuclear translocation. J Virol 2013; 87:11806-20. [PMID: 23986578 DOI: 10.1128/jvi.01920-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Angiogenin (ANG) is a 14-kDa multifunctional proangiogenic secreted protein whose expression level correlates with the aggressiveness of several tumors. We observed increased ANG expression and secretion in endothelial cells during de novo infection with Kaposi's sarcoma-associated herpesvirus (KSHV), in cells expressing only latency-associated nuclear antigen 1 (LANA-1) protein, and in KSHV latently infected primary effusion lymphoma (PEL) BCBL-1 and BC-3 cells. Inhibition of phospholipase Cγ (PLCγ) mediated ANG's nuclear translocation by neomycin, an aminoglycoside antibiotic (not G418-neomicin), resulted in reduced KSHV latent gene expression, increased lytic gene expression, and increased cell death of KSHV(+) PEL and endothelial cells. ANG detection in significant levels in KS and PEL lesions highlights its importance in KSHV pathogenesis. To assess the in vivo antitumor activity of neomycin and neamine (a nontoxic derivative of neomycin), BCBL-1 cells were injected intraperitoneally into NOD/SCID mice. We observed significant extended survival of mice treated with neomycin or neamine. Markers of lymphoma establishment, such as increases in animal body weight, spleen size, tumor cell spleen infiltration, and ascites volume, were observed in nontreated animals and were significantly diminished by neomycin or neamine treatments. A significant decrease in LANA-1 expression, an increase in lytic gene expression, and an increase in cleaved caspase-3 were also observed in neomycin- or neamine-treated animal ascitic cells. These studies demonstrated that ANG played an essential role in KSHV latency maintenance and BCBL-1 cell survival in vivo, and targeting ANG function by neomycin/neamine to induce the apoptosis of cells latently infected with KSHV is an attractive therapeutic strategy against KSHV-associated malignancies.
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Choi S, Thapa N, Hedman AC, Li Z, Sacks DB, Anderson RA. IQGAP1 is a novel phosphatidylinositol 4,5 bisphosphate effector in regulation of directional cell migration. EMBO J 2013; 32:2617-30. [PMID: 23982733 DOI: 10.1038/emboj.2013.191] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 07/29/2013] [Indexed: 12/15/2022] Open
Abstract
Phosphatidylinositol 4,5 bisphosphate (PIP₂) is a key lipid messenger for regulation of cell migration. PIP₂ modulates many effectors, but the specificity of PIP₂ signalling can be defined by interactions of PIP₂-generating enzymes with PIP₂ effectors. Here, we show that type Iγ phosphatidylinositol 4-phosphate 5-kinase (PIPKIγ) interacts with the cytoskeleton regulator, IQGAP1, and modulates IQGAP1 function in migration. We reveal that PIPKIγ is required for IQGAP1 recruitment to the leading edge membrane in response to integrin or growth factor receptor activation. Moreover, IQGAP1 is a PIP₂ effector that directly binds PIP₂ through a polybasic motif and PIP₂ binding activates IQGAP1, facilitating actin polymerization. IQGAP1 mutants that lack PIPKIγ or PIP₂ binding lose the ability to control directional cell migration. Collectively, these data reveal a synergy between PIPKIγ and IQGAP1 in the control of cell migration.
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Affiliation(s)
- Suyong Choi
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, USA
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38
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Aggarwal C, Labuz J, Gabryś H. Decoding the role of phosphoinositides in phototropin signaling involved in chloroplast movements. PLANT SIGNALING & BEHAVIOR 2013; 8:25105. [PMID: 23733070 PMCID: PMC3999074 DOI: 10.4161/psb.25105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Accepted: 05/21/2013] [Indexed: 05/20/2023]
Abstract
In angiosperms, light-dependent chloroplast movements are exclusively mediated by UVA/blue light receptors - phototropins. The two photoreceptors of Arabidopsis thaliana, phot1 and phot2, have overlapping roles in the control of these movements. Experiments performed in different plant species point to the participation of phosphoinositides in blue light-controlled chloroplast relocations. Here, we report a summary of recent findings presenting the involvement of phosphatidylinositol 4,5-bisphosphate as well as phosphatidylinositol 3- and 4-phosphates in weak blue light-mediated (accumulation) and strong blue light-mediated (avoidance) responses of chloroplasts. The blue light-activated alterations in phosphoinositide concentration are partly responsible for cytosolic Ca (2+) changes. Ca (2+) influx from apoplast does not seem to be involved in the mechanism of movement responses. In summary, interplay between phosphoinositides and intracellular Ca (2+) regulates chloroplast redistribution in response to blue light in higher plants.
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Bushman JD, Zhou Q, Shyng SL. A Kir6.2 pore mutation causes inactivation of ATP-sensitive potassium channels by disrupting PIP2-dependent gating. PLoS One 2013; 8:e63733. [PMID: 23700433 PMCID: PMC3659044 DOI: 10.1371/journal.pone.0063733] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 04/05/2013] [Indexed: 11/18/2022] Open
Abstract
In the absence of intracellular nucleotides, ATP-sensitive potassium (KATP) channels exhibit spontaneous activity via a phosphatidylinositol-4,5-bisphosphate (PIP2)-dependent gating process. Previous studies show that stability of this activity requires subunit-subunit interactions in the cytoplasmic domain of Kir6.2; selective mutagenesis and disease mutations at the subunit interface result in time-dependent channel inactivation. Here, we report that mutation of the central glycine in the pore-lining second transmembrane segment (TM2) to proline in Kir6.2 causes KATP channel inactivation. Unlike C-type inactivation, a consequence of selectivity filter closure, in many K(+) channels, the rate of inactivation in G156P channels was insensitive to changes in extracellular ion concentrations or ion species fluxing through the pore. Instead, the rate of G156P inactivation decreased with exogenous application of PIP2 and increased when PIP2-channel interaction was inhibited with neomycin or poly-L-lysine. These findings indicate the G156P mutation reduces the ability of PIP2 to stabilize the open state of KATP channels, similar to mutations in the cytoplasmic domain that produce inactivation. Consistent with this notion, when PIP2-dependent open state stability was substantially increased by addition of a second gain-of-function mutation, G156P inactivation was abolished. Importantly, bath application and removal of Mg(2+)-free ATP or a nonhydrolyzable analog of ATP, which binds to the cytoplasmic domain of Kir6.2 and causes channel closure, recover G156P channel from inactivation, indicating crosstalk between cytoplasmic and transmembrane domains. The G156P mutation provides mechanistic insight into the structural and functional interactions between the pore and cytoplasmic domains of Kir6.2 during gating.
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Affiliation(s)
- Jeremy D. Bushman
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Qing Zhou
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Show-Ling Shyng
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon, United States of America
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40
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Aggarwal C, Łabuz J, Gabryś H. Phosphoinositides play differential roles in regulating phototropin1- and phototropin2-mediated chloroplast movements in Arabidopsis. PLoS One 2013; 8:e55393. [PMID: 23405144 PMCID: PMC3566141 DOI: 10.1371/journal.pone.0055393] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 12/24/2012] [Indexed: 01/06/2023] Open
Abstract
Phototropins are UVA/blue-light receptors involved in controlling the light-dependent physiological responses which serve to optimize the photosynthetic activity of plants and promote growth. The phototropin-induced phosphoinositide (PI) metabolism has been shown to be essential for stomatal opening and phototropism. However, the role of PIs in phototropin-induced chloroplast movements remains poorly understood. The aim of this work is to determine which PI species are involved in the control of chloroplast movements in Arabidopsis and the nature of their involvement. We present the effects of the inactivation of phospholipase C (PLC), PI3-kinase (PI3K) and PI4-kinase (PI4K) on chloroplast relocations in Arabidopsis. The inhibition of the phosphatidylinositol 4,5-bisphospahte [PI(4,5)P2]-PLC pathway, using neomycin and U73122, suppressed the phot2-mediated chloroplast accumulation and avoidance responses, without affecting movement responses controlled by phot1. On the other hand, PI3K and PI4K activities are more restricted to phot1- and phot2-induced weak-light responses. The inactivation of PI3K and PI4K by wortmannin and LY294002 severely affected the weak blue-light-activated accumulation response but had little effect on the strong blue-light-activated avoidance response. The inhibitory effect observed with PI metabolism inhibitors is, at least partly, due to a disturbance in Ca2+(c) signaling. Using the transgenic aequorin system, we show that the application of these inhibitors suppresses the blue-light-induced transient Ca2+(c) rise. These results demonstrate the importance of PIs in chloroplast movements, with the PI(4,5)P2-PLC pathway involved in phot2 signaling while PI3K and PI4K are required for the phot1- and phot2-induced accumulation response. Our results suggest that these PIs modulate cytosolic Ca2+ signaling during movements.
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Affiliation(s)
- Chhavi Aggarwal
- Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Justyna Łabuz
- Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Halina Gabryś
- Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
- * E-mail:
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Charrasse S, Comunale F, De Rossi S, Echard A, Gauthier-Rouvière C. Rab35 regulates cadherin-mediated adherens junction formation and myoblast fusion. Mol Biol Cell 2012. [PMID: 23197472 PMCID: PMC3564529 DOI: 10.1091/mbc.e12-02-0167] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The small GTPase Rab35 is identified as a regulator of cadherin trafficking and stabilization at cell–cell contacts. Rab35 function is required for PIP5KIγ accumulation at cell contacts and PI(4,5)P2 production, and hence cadherin stabilization. Rab35 regulates myoblast fusion, a cellular process under the control of cadherin-dependent signaling. Cadherins are homophilic cell–cell adhesion molecules implicated in many fundamental processes, such as morphogenesis, cell growth, and differentiation. They accumulate at cell–cell contact sites and assemble into large macromolecular complexes named adherens junctions (AJs). Cadherin targeting and function are regulated by various cellular processes, many players of which remain to be uncovered. Here we identify the small GTPase Rab35 as a new regulator of cadherin trafficking and stabilization at cell–cell contacts in C2C12 myoblasts and HeLa cells. We find that Rab35 accumulates at cell–cell contacts in a cadherin-dependent manner. Knockdown of Rab35 or expression of a dominant-negative form of Rab35 impaired N- and M-cadherin recruitment to cell–cell contacts, their stabilization at the plasma membrane, and association with p120 catenin and led to their accumulation in transferrin-, clathrin-, and AP-2–positive intracellular vesicles. We also find that Rab35 function is required for PIP5KIγ accumulation at cell–cell contacts and phosphatidyl inositol 4,5-bisphosphate production, which is involved in cadherin stabilization at contact sites. Finally, we show that Rab35 regulates myoblast fusion, a major cellular process under the control of cadherin-dependent signaling. Taken together, these results reveal that Rab35 regulates cadherin-dependent AJ formation and myoblast fusion.
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Affiliation(s)
- Sophie Charrasse
- Centre de Recherche de Biochimie Macromoléculaire, Universités Montpellier 2 et 1, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5237, 34293 Montpellier, France
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Chichili GR, Cail RC, Rodgers W. Cytoskeletal modulation of lipid interactions regulates Lck kinase activity. J Biol Chem 2012; 287:24186-94. [PMID: 22613726 DOI: 10.1074/jbc.m111.320747] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The actin cytoskeleton promotes clustering of proteins associated with cholesterol-dependent rafts, but its effect on lipid interactions that form and maintain rafts is not understood. We addressed this question by determining the effect of disrupting the cytoskeleton on co-clustering of dihexadecyl-(C(16))-anchored DiO and DiI, which co-enrich in ordered lipid environments such as rafts. Co-clustering was assayed by fluorescence resonance energy transfer (FRET) in labeled T cells, where rafts function in the phosphoregulation of the Src family kinase Lck. Our results show that probe co-clustering was sensitive to depolymerization of actin filaments with latrunculin B (Lat B), inhibition of myosin II with blebbistatin, and treatment with neomycin to sequester phosphatidylinositol 4,5-bisphosphate. Cytoskeletal effects on lipid interactions were not restricted to order-preferring label because co-clustering of C(16)-anchored DiO with didodecyl (C(12))-anchored DiI, which favors disordered lipids, was also reduced by Lat B and blebbistatin. Furthermore, conditions that disrupted probe co-clustering resulted in activation of Lck. These data show that the cytoskeleton globally modulates lipid interactions in the plasma membrane, and this property maintains rafts that function in Lck regulation.
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Affiliation(s)
- Gurunadh R Chichili
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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43
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Abstract
There are three kinds of membrane potentials: the surface potentials, resulting from the accumulation of charges at the membrane surfaces; the transmembrane potential, determined by imbalance of charge in the aqueous solutions; and the dipole potential, a membrane-internal potential from the dipolar components of the phospholipids and interface water. The absolute value of the dipole potential has been very difficult to measure, although its value has been estimated to be in the range of 200-1,000 mV from ion translocation rates (determined by the planar lipid bilayer method), the surface potential of lipid monolayers (determined by the lipid monolayer method), molecular-dynamics calculations, and electron scattering using cryoelectron microscopy (cryo-EM). Spectroscopy methods have also been used to monitor the dipole potential changes on the basis of the observed fluorescence changes of voltage-sensitive probes. The dipole potential accounts for the much larger permeability of a bare phospholipid membrane to anions than cations and affects the conformation and function of membrane proteins.
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Affiliation(s)
- Liguo Wang
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, USA.
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Kang DH, Jung HS, Ahn N, Lee J, Seo S, Suh KY, Kim J, Kim K. Biomimetic detection of aminoglycosidic antibiotics using polydiacetylene–phospholipids supramolecules. Chem Commun (Camb) 2012; 48:5313-5. [DOI: 10.1039/c2cc31466e] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Venable ME. Lipase and phospholipase inhibitors: design and applications. Methods Mol Biol 2012; 861:139-148. [PMID: 22426717 DOI: 10.1007/978-1-61779-600-5_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Lipases are important drug discovery targets since they play central roles in signal transduction and metabolism. Many inhibitors have been isolated from natural sources and others derived through synthesis of substrate analogs or biomimetics. Because lipids are hydrophobic, there are special procedures needed for their study. This chapter covers two commonly used procedures for assay of lipases and phospholipases and how they can be adapted for the discovery and analysis of inhibitors.
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Affiliation(s)
- Mark E Venable
- Department of Biology, Appalachian State University, Boone, NC, USA.
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Mak LH, Georgiades SN, Rosivatz E, Whyte GF, Mirabelli M, Vilar R, Woscholski R. A small molecule mimicking a phosphatidylinositol (4,5)-bisphosphate binding pleckstrin homology domain. ACS Chem Biol 2011; 6:1382-90. [PMID: 21958214 DOI: 10.1021/cb2003187] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Inositol phospholipids have emerged as important key players in a wide variety of cellular functions. Among the seven existing inositol phospholipids, phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P(2)) has attracted much attention in recent years due to its important role in numerous cellular signaling events and regulations, which in turn impact several human diseases. This particular lipid is recognized in the cell by specific lipid binding domains, such as the Pleckstrin-homology (PH) domain, which is also employed as a tool to monitor this important lipid. Here, we describe the synthesis and biological characterization of a small molecule that mimics the PH domain as judged by its ability to bind specifically to only PI(4,5)P(2) and effectively compete with the PH domain in vitro and in a cellular environment. The binding constant of this small molecule PH domain mimetic (PHDM) was determined to be 17.6 ± 10.1 μM, similar in potency to the PH domain. Using NIH 3T3 mouse fibroblast cells we demonstrated that this compound is cell-permeable and able to modulate PI(4,5)P(2)-dependent effects in a cellular environment such as the endocytosis of the transferrin receptor, loss of mitochondria, as well as stress fiber formation. This highly PI(4,5)P(2)-specific chemical mimetic of a PH domain not only is a powerful research tool but might also be a lead compound in future drug developments targeting PI(4,5)P(2)-dependent diseases such as Lowe syndrome.
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Affiliation(s)
- Lok Hang Mak
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Savvas N. Georgiades
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Evelyn Rosivatz
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Gillian F. Whyte
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Marianna Mirabelli
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Ramon Vilar
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Rudiger Woscholski
- Department of Chemistry, ‡Division of Cell and Molecular Biology, and §Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
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Márquez MG, Favale NO, Leocata Nieto F, Pescio LG, Sterin-Speziale N. Changes in membrane lipid composition cause alterations in epithelial cell-cell adhesion structures in renal papillary collecting duct cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:491-501. [PMID: 22155258 DOI: 10.1016/j.bbamem.2011.11.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 11/18/2011] [Accepted: 11/23/2011] [Indexed: 11/16/2022]
Abstract
In epithelial tissues, adherens junctions (AJ) mediate cell-cell adhesion by using proteins called E-cadherins, which span the plasma membrane, contact E-cadherin on other cells and connect with the actin cytoskeleton inside the cell. Although AJ protein complexes are inserted in detergent-resistant membrane microdomains, the influence of membrane lipid composition in the preservation of AJ structures has not been extensively addressed. In the present work, we studied the contribution of membrane lipids to the preservation of renal epithelial cell-cell adhesion structures. We biochemically characterized the lipid composition of membranes containing AJ complexes. By using lipid membrane-affecting agents, we found that such agents induced the formation of new AJ protein-containing domains of different lipid composition. By using both biochemical approaches and fluorescence microscopy we demonstrated that the membrane phospholipid composition plays an essential role in the in vivo maintenance of AJ structures involved in cell-cell adhesion structures in renal papillary collecting duct cells.
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Wakayama Y, Miura K, Sabe H, Mochizuki N. EphrinA1-EphA2 signal induces compaction and polarization of Madin-Darby canine kidney cells by inactivating Ezrin through negative regulation of RhoA. J Biol Chem 2011; 286:44243-44253. [PMID: 21979959 PMCID: PMC3243524 DOI: 10.1074/jbc.m111.267047] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The epithelial cells exhibit either a columnar or a flat shape dependent on extracellular stimuli or the cell-cell adhesion. Membrane-anchored ephrinA stimulates EphA receptor tyrosine kinases as a ligand in a cell-cell contact-dependent manner. The mechanism through which ephrinA1/EphA2 signal regulates the cell morphology remains elusive. We demonstrate here that ephrinA1/EphA2 signal induces compaction and enhanced polarization (columnar change) of Madin-Darby canine kidney epithelial cells by regulating Ezrin, a linker that connects plasma membrane and actin cytoskeleton. Activation of EphA2 resulted in RhoA inactivation through p190RhoGAP-A and subsequent dephosphorylation of Ezrin on Thr-567 phosphorylated by Rho kinase. Consistently, the cells expressing an active mutant of Ezrin in which Thr-567 was replaced with Asp did not change their shape in response to ephrinA1. Furthermore, depletion of Ezrin led to compaction and enhanced polarization without ephrinA1 stimulation, suggesting the role for active Ezrin in keeping the flat cell shape. Ezrin localized to apical domain irrespective of ephrinA1 stimulation, whereas phosphorylated Ezrin on the apical domain was reduced by ephrinA1 stimulation. Collectively, ephrinA1/EphA2 signal negatively regulates Ezrin and promotes the alteration of cell shape, from flat to columnar shape.
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Affiliation(s)
- Yuki Wakayama
- Department of Cell Biology, National Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka, 565-8565, Japan
| | - Koichi Miura
- Department of Cell Biology, National Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka, 565-8565, Japan.
| | - Hisataka Sabe
- Department of Molecular Biology, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, 060-8638, Japan
| | - Naoki Mochizuki
- Department of Cell Biology, National Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka, 565-8565, Japan.
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49
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Martelli AM, Ognibene A, Buontempo F, Fini M, Bressanin D, Goto K, McCubrey JA, Cocco L, Evangelisti C. Nuclear phosphoinositides and their roles in cell biology and disease. Crit Rev Biochem Mol Biol 2011; 46:436-57. [DOI: 10.3109/10409238.2011.609530] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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50
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Sobolewski P, Kandel J, Klinger AL, Eckmann DM. Air bubble contact with endothelial cells in vitro induces calcium influx and IP3-dependent release of calcium stores. Am J Physiol Cell Physiol 2011; 301:C679-86. [PMID: 21633077 PMCID: PMC3273994 DOI: 10.1152/ajpcell.00046.2011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 05/31/2011] [Indexed: 01/05/2023]
Abstract
Gas embolism is a serious complication of decompression events and clinical procedures, but the mechanism of resulting injury remains unclear. Previous work has demonstrated that contact between air microbubbles and endothelial cells causes a rapid intracellular calcium transient and can lead to cell death. Here we examined the mechanism responsible for the calcium rise. Single air microbubbles (50-150 μm), trapped at the tip of a micropipette, were micromanipulated into contact with individual human umbilical vein endothelial cells (HUVECs) loaded with Fluo-4 (a fluorescent calcium indicator). Changes in intracellular calcium were then recorded via epifluorescence microscopy. First, we confirmed that HUVECs rapidly respond to air bubble contact with a calcium transient. Next, we examined the involvement of extracellular calcium influx by conducting experiments in low calcium buffer, which markedly attenuated the response, or by pretreating cells with stretch-activated channel blockers (gadolinium chloride or ruthenium red), which abolished the response. Finally, we tested the role of intracellular calcium release by pretreating cells with an inositol 1,4,5-trisphosphate (IP3) receptor blocker (xestospongin C) or phospholipase C inhibitor (neomycin sulfate), which eliminated the response in 64% and 67% of cases, respectively. Collectively, our results lead us to conclude that air bubble contact with endothelial cells causes an influx of calcium through a stretch-activated channel, such as a transient receptor potential vanilloid family member, triggering the release of calcium from intracellular stores via the IP3 pathway.
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Affiliation(s)
- Peter Sobolewski
- Dept. of Anesthesiology and Critical Care, Univ. of Pennsylvania, Philadelphia, 19104-4283, USA
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