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Ali Moussa HY, Shin KC, Ponraj J, Park SH, Lee OS, Mansour S, Park Y. PIP 2 Is An Electrostatic Catalyst for Vesicle Fusion by Lowering the Hydration Energy: Arresting Vesicle Fusion by Masking PIP 2. ACS NANO 2024; 18:12737-12748. [PMID: 38717305 DOI: 10.1021/acsnano.3c09614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Lipids are key factors in regulating membrane fusion. Lipids are not only structural components to form membranes but also active catalysts for vesicle fusion and neurotransmitter release, which are driven by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. SNARE proteins seem to be partially assembled before fusion, but the mechanisms that arrest vesicle fusion before Ca2+ influx are still not clear. Here, we show that phosphatidylinositol 4,5-bisphosphate (PIP2) electrostatically triggers vesicle fusion as an electrostatic catalyst by lowering the hydration energy and that a myristoylated alanine-rich C-kinase substrate (MARCKS), a PIP2-binding protein, arrests vesicle fusion in a vesicle docking state where the SNARE complex is partially assembled. Vesicle-mimicking liposomes fail to reproduce vesicle fusion arrest by masking PIP2, indicating that native vesicles are essential for the reconstitution of physiological vesicle fusion. PIP2 attracts cations to repel water molecules from membranes, thus lowering the hydration energy barrier.
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Affiliation(s)
- Houda Yasmine Ali Moussa
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Kyung Chul Shin
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Janarthanan Ponraj
- HBKU Core Laboratories, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | | | - One-Sun Lee
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, P. J. Šafárik University, Košice SK-04001, Slovakia
| | - Said Mansour
- HBKU Core Laboratories, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | - Yongsoo Park
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
- College of Health & Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
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2
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Okahara S, Miyamoto S, Soh Z, Yoshino M, Takahashi H, Itoh H, Tsuji T. Correlation Analysis Between Echinocytosis Stages and Blood Viscosity During Oxygenator Perfusion: An In Vitro Study. ASAIO J 2024:00002480-990000000-00470. [PMID: 38635489 DOI: 10.1097/mat.0000000000002214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024] Open
Abstract
The study aimed to investigate the effect of red blood cell (RBC) morphology on oxygenator perfusion, focusing on stages of echinocytosis and their correlation with blood viscosity. A test circuit with an oxygenator and human RBC mixtures was used to induce changes in RBC shape by increasing sodium salicylate concentrations (0, 10, 20, 30, 60, and 120 mmol/L), while hematocrit, blood temperature, and anticoagulation were maintained. Blood viscosity was measured using a continuous blood viscosity monitoring system based on pressure-flow characteristics. Under a scanning electron microscope, the percentages of discocytes, echinocytes I-III, spheroechinocytes, and spherocytes were determined from approximately 400 cells per RBC sample. Early echinocytes, mainly discocytes and echinocytes I and II in the range of 0-30 mmol/L were predominant, resulting in a gradual increase in blood viscosity from 1.78 ± 0.12 to 1.94 ± 0.12 mPa s. At 60 mmol/L spherocytes emerged, and at 120 mmol/L, spheroidal RBCs constituted 50% of the population, and blood viscosity sharply rose to 2.50 ± 0.15 mPa s, indicating a 40% overall increase. In conclusion, the presence of spherocytes significantly increases blood viscosity, which may affect oxygenator perfusion.
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Affiliation(s)
- Shigeyuki Okahara
- From the Graduate School of Health Sciences, Junshin Gakuen University, Fukuoka, Japan
| | - Satoshi Miyamoto
- Department of Clinical Engineering, Hiroshima University Hospital, Hiroshima, Japan
| | - Zu Soh
- Graduate School of Advanced Science and Engineering, Hiroshima University, Hiroshima, Japan
| | - Masaru Yoshino
- Department of Clinical Engineering, Hiroshima University Hospital, Hiroshima, Japan
| | - Hidenobu Takahashi
- Faculty of Health Sciences, Department of Medical Science and Technology, Hiroshima International University, Hiroshima, Japan
| | - Hideshi Itoh
- Department of Health and Medical Sciences, Nippon Bunri University, Ōita, Japan
| | - Toshio Tsuji
- Graduate School of Advanced Science and Engineering, Hiroshima University, Hiroshima, Japan
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3
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Wills RC, Hammond GRV. PI(4,5)P2: signaling the plasma membrane. Biochem J 2022; 479:2311-2325. [PMID: 36367756 PMCID: PMC9704524 DOI: 10.1042/bcj20220445] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/19/2022] [Accepted: 10/21/2022] [Indexed: 11/13/2022]
Abstract
In the almost 70 years since the first hints of its existence, the phosphoinositide, phosphatidyl-D-myo-inositol 4,5-bisphosphate has been found to be central in the biological regulation of plasma membrane (PM) function. Here, we provide an overview of the signaling, transport and structural roles the lipid plays at the cell surface in animal cells. These include being substrate for second messenger generation, direct modulation of receptors, control of membrane traffic, regulation of ion channels and transporters, and modulation of the cytoskeleton and cell polarity. We conclude by re-evaluating PI(4,5)P2's designation as a signaling molecule, instead proposing a cofactor role, enabling PM-selective function for many proteins.
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Affiliation(s)
- Rachel C. Wills
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
| | - Gerald R. V. Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, U.S.A
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4
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Borges-Araújo L, Monteiro ME, Mil-Homens D, Bernardes N, Sarmento MJ, Coutinho A, Prieto M, Fernandes F. Impact of Ca 2+-Induced PI(4,5)P 2 Clusters on PH-YFP Organization and Protein-Protein Interactions. Biomolecules 2022; 12:912. [PMID: 35883468 PMCID: PMC9312469 DOI: 10.3390/biom12070912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/22/2022] [Accepted: 06/27/2022] [Indexed: 11/16/2022] Open
Abstract
Despite its low abundance, phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a key modulator of membrane-associated signaling events in eukaryotic cells. Temporal and spatial regulation of PI(4,5)P2 concentration can achieve localized increases in the levels of this lipid, which are crucial for the activation or recruitment of peripheral proteins to the plasma membrane. The recent observation of the dramatic impact of physiological divalent cation concentrations on PI(4,5)P2 clustering, suggests that protein anchoring to the plasma membrane through PI(4,5)P2 is likely not defined solely by a simple (monomeric PI(4,5)P2)/(protein bound PI(4,5)P2) equilibrium, but instead depends on complex protein interactions with PI(4,5)P2 clusters. The insertion of PI(4,5)P2-binding proteins within these clusters can putatively modulate protein-protein interactions in the membrane, but the relevance of such effects is largely unknown. In this work, we characterized the impact of Ca2+ on the organization and protein-protein interactions of PI(4,5)P2-binding proteins. We show that, in giant unilamellar vesicles presenting PI(4,5)P2, the membrane diffusion properties of pleckstrin homology (PH) domains tagged with a yellow fluorescent protein (YFP) are affected by the presence of Ca2+, suggesting direct interactions between the protein and PI(4,5)P2 clusters. Importantly, PH-YFP is found to dimerize in the membrane in the absence of Ca2+. This oligomerization is inhibited in the presence of physiological concentrations of the divalent cation. These results confirm that cation-dependent PI(4,5)P2 clustering promotes interactions between PI(4,5)P2-binding proteins and has the potential to dramatically influence the organization and downstream interactions of PI(4,5)P2-binding proteins in the plasma membrane.
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Affiliation(s)
- Luís Borges-Araújo
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Marina E. Monteiro
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (M.E.M.); (M.J.S.)
| | - Dalila Mil-Homens
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Nuno Bernardes
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Maria J. Sarmento
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (M.E.M.); (M.J.S.)
- Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Avenida Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Ana Coutinho
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
- Departamento de Química e Bioquímica, Faculty of Sciences, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Manuel Prieto
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Fábio Fernandes
- IBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (D.M.-H.); (N.B.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
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Quintanilla CG, Lee WR, Liou J. Nir1 constitutively localizes at ER-PM junctions and promotes Nir2 recruitment for PIP 2 homeostasis. Mol Biol Cell 2022; 33:br2. [PMID: 35020418 PMCID: PMC9250379 DOI: 10.1091/mbc.e21-07-0356] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Homeostatic regulation of plasma membrane (PM) phosphatidylinositol 4,5-bisphosphate (PIP2) in receptor-stimulated cells is mediated by the lipid transfer protein Nir2. Nir2 is dynamically recruited to endoplasmic reticulum–plasma membrane (ER–PM) junctions to facilitate replenishment of PM PIP2 hydrolyzed during receptor-mediated signaling. However, our knowledge regarding the activation and sustainment of Nir2-mediated replenishment of PM PIP2 is limited. Here, we describe the functions of Nir1 as a positive regulator of Nir2 and PIP2 homeostasis. In contrast to the family proteins Nir2 and Nir3, Nir1 constitutively localizes at ER–PM junctions. Nir1 potentiates Nir2 targeting to ER–PM junctions during receptor-mediated signaling and is required for efficient PM PIP2 replenishment. Live-cell imaging and biochemical analysis reveal that Nir1 interacts with Nir2 via a region between the FFAT motif and the DDHD domain. Combined, results from this study identify Nir1 as an ER–PM junction localized protein that promotes Nir2 recruitment for PIP2 homeostasis.
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Affiliation(s)
| | - Wan-Ru Lee
- Department of Physiology, UT Southwestern Medical Center, TX 75390, USA
| | - Jen Liou
- Department of Physiology, UT Southwestern Medical Center, TX 75390, USA
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6
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Sarmento MJ, Borges-Araújo L, Pinto SN, Bernardes N, Ricardo JC, Coutinho A, Prieto M, Fernandes F. Quantitative FRET Microscopy Reveals a Crucial Role of Cytoskeleton in Promoting PI(4,5)P 2 Confinement. Int J Mol Sci 2021; 22:11727. [PMID: 34769158 PMCID: PMC8583820 DOI: 10.3390/ijms222111727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/24/2021] [Accepted: 10/26/2021] [Indexed: 01/30/2023] Open
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is an essential plasma membrane component involved in several cellular functions, including membrane trafficking and cytoskeleton organization. This function multiplicity is partially achieved through a dynamic spatiotemporal organization of PI(4,5)P2 within the membrane. Here, we use a Förster resonance energy transfer (FRET) approach to quantitatively assess the extent of PI(4,5)P2 confinement within the plasma membrane. This methodology relies on the rigorous evaluation of the dependence of absolute FRET efficiencies between pleckstrin homology domains (PHPLCδ) fused with fluorescent proteins and their average fluorescence intensity at the membrane. PI(4,5)P2 is found to be significantly compartmentalized at the plasma membrane of HeLa cells, and these clusters are not cholesterol-dependent, suggesting that membrane rafts are not involved in the formation of these nanodomains. On the other hand, upon inhibition of actin polymerization, compartmentalization of PI(4,5)P2 is almost entirely eliminated, showing that the cytoskeleton network is the critical component responsible for the formation of nanoscale PI(4,5)P2 domains in HeLa cells.
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Affiliation(s)
- Maria J. Sarmento
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| | - Luís Borges-Araújo
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Sandra N. Pinto
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Nuno Bernardes
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Joana C. Ricardo
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
| | - Ana Coutinho
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
- Departamento de Química e Bioquímica, Faculty of Sciences, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Manuel Prieto
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Fábio Fernandes
- IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal; (L.B.-A.); (S.N.P.); (N.B.); (J.C.R.); (A.C.); (M.P.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
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7
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Chen Y, Lin C, Guo Z, Zhao S, Zhu Y, Huang F, Shui G, Lam SM, Pu J, Yan Y, Liu Z, Zhang B. Altered Expression Profile of Phosphatidylinositols in Erythrocytes of Alzheimer's Disease and Amnestic Mild Cognitive Impairment Patients. J Alzheimers Dis 2020; 73:811-818. [PMID: 31868671 DOI: 10.3233/jad-190926] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Studies have demonstrated that the levels of phospholipids, including phosphatidylinositols (PIs), were decreased in Alzheimer's disease (AD) brain, presenting as a potential biomarker for AD. The plasma phospholipids levels have also been discovered to predict the conversion of cognitively normal elderly adults to amnestic mild cognitive impairment (aMCI) or demented patients. OBJECTIVE To investigate the expression profile of PIs in erythrocytes of AD and aMCI patients, which would serve as a blood-based method to distinguish AD and aMCI patients from normal controls (NC). METHODS In this study, we used anion-exchange high-performance liquid chromatography to analyze PIs alterations in erythrocytes from a total of 86 prospectively recruited subjects (including 24 NC, 21 aMCI patients, and 41 AD patients). RESULTS We found that the levels of PI40 : 4, PI3/5P, and PI(3,4)P2 in aMCI patients, and the levels of PI4P, PI(3,4)P2, and PI3/5P in AD patients were significantly decreased compared to NC. The changed expression profile of PIs could effectively discriminate AD and aMCI patients from NC (AUC = 0.964, 0.938, respectively). CONCLUSION The altered expression profile of erythrocytes PIs might be a potential blood-based biomarker for AD and aMCI. This alteration of PIs probably reflected the impaired deformability and oxygen-carrying capacity of erythrocytes in AD and aMCI patients.
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Affiliation(s)
- Yanxing Chen
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Caixiu Lin
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Department of Neurology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhangyu Guo
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Department of Pathology, Weifang Medical University, Weifang, China
| | - Shuai Zhao
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yueli Zhu
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Fude Huang
- Shanghai Advanced Research Institute, University of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Guanghou Shui
- StateKey Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Sin Man Lam
- StateKey Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.,LipidALL Technologies Company Limited, Changzhou, Jiangsu Province, China
| | - Jiali Pu
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yaping Yan
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhirong Liu
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Baorong Zhang
- Department of Neurology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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8
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Zewe JP, Miller AM, Sangappa S, Wills RC, Goulden BD, Hammond GRV. Probing the subcellular distribution of phosphatidylinositol reveals a surprising lack at the plasma membrane. J Cell Biol 2020; 219:133808. [PMID: 32211893 PMCID: PMC7054989 DOI: 10.1083/jcb.201906127] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 10/14/2019] [Accepted: 11/19/2019] [Indexed: 12/16/2022] Open
Abstract
The polyphosphoinositides (PPIn) are central regulatory lipids that direct membrane function in eukaryotic cells. Understanding how their synthesis is regulated is crucial to revealing these lipids’ role in health and disease. PPIn are derived from the major structural lipid, phosphatidylinositol (PI). However, although the distribution of most PPIn has been characterized, the subcellular localization of PI available for PPIn synthesis is not known. Here, we used several orthogonal approaches to map the subcellular distribution of PI, including localizing exogenous fluorescent PI, as well as detecting lipid conversion products of endogenous PI after acute chemogenetic activation of PI-specific phospholipase and 4-kinase. We report that PI is broadly distributed throughout intracellular membrane compartments. However, there is a surprising lack of PI in the plasma membrane compared with the PPIn. These experiments implicate regulation of PI supply to the plasma membrane, as opposed to regulation of PPIn-kinases, as crucial to the control of PPIn synthesis and function at the PM.
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Affiliation(s)
- James P Zewe
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - April M Miller
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Sahana Sangappa
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Rachel C Wills
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Brady D Goulden
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Gerald R V Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
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9
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Schäfer J, Nehls J, Schön M, Mey I, Steinem C. Leaflet-Dependent Distribution of PtdIns[4,5]P 2 in Supported Model Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1320-1328. [PMID: 31951413 DOI: 10.1021/acs.langmuir.9b03793] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Supported planar lipid bilayers (SLBs) prepared by spreading of unilamellar vesicles on hydrophilic substrates such as silicon dioxide are frequently used to investigate lipid-protein interactions by means of surface-sensitive methods. In recent years, the receptor lipid phosphatidylinositol-4,5-bisphosphate (PtdIns[4,5]P2) became particularly important as a significant number of proteins bind to this lipid at the inner leaflet of the plasma membrane. Here, we investigated how the lipid PtdIns[4,5]P2 distributes between the two leaflets of an SLB on SiO2 surfaces. We prepared SLBs on SiO2 by spreading small unilamellar vesicles and quantified the adsorption of PtdIns[4,5]P2 binding proteins providing information about the accessibility of PtdIns[4,5]P2. We compared protein binding to PtdIns[4,5]P2 in SLBs with that in lipid monolayers on a 1,1,1-trimethyl-N-(trimethylsilyl)silanamine-functionalized SiO2 surface using reflectometric interference spectroscopy and atomic force microscopy. Our results clearly demonstrate that the accessibility of PtdIns[4,5]P2 for protein binding is reduced in SLBs compared to that in supported hybrid membranes, which is discussed in terms of PtdIns[4,5]P2 distribution in the two leaflets of SLBs.
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Affiliation(s)
- Jonas Schäfer
- Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , 37077 Göttingen , Germany
| | - Jessica Nehls
- Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , 37077 Göttingen , Germany
| | - Markus Schön
- Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , 37077 Göttingen , Germany
| | - Ingo Mey
- Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , 37077 Göttingen , Germany
| | - Claudia Steinem
- Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , 37077 Göttingen , Germany
- Max Planck Institute for Dynamics and Self-Organization , Am Fassberg 17 , 37077 Göttingen , Germany
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10
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Pseudomonas aeruginosa Toxin ExoU as a Therapeutic Target in the Treatment of Bacterial Infections. Microorganisms 2019; 7:microorganisms7120707. [PMID: 31888268 PMCID: PMC6955817 DOI: 10.3390/microorganisms7120707] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/10/2019] [Accepted: 12/14/2019] [Indexed: 12/20/2022] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa employs the type III secretion system (T3SS) and four effector proteins, ExoS, ExoT, ExoU, and ExoY, to disrupt cellular physiology and subvert the host’s innate immune response. Of the effector proteins delivered by the T3SS, ExoU is the most toxic. In P. aeruginosa infections, where the ExoU gene is expressed, disease severity is increased with poorer prognoses. This is considered to be due to the rapid and irreversible damage exerted by the phospholipase activity of ExoU, which cannot be halted before conventional antibiotics can successfully eliminate the pathogen. This review will discuss what is currently known about ExoU and explore its potential as a therapeutic target, highlighting some of the small molecule ExoU inhibitors that have been discovered from screening approaches.
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11
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Quantification of phosphoinositides reveals strong enrichment of PIP 2 in HIV-1 compared to producer cell membranes. Sci Rep 2019; 9:17661. [PMID: 31776383 PMCID: PMC6881329 DOI: 10.1038/s41598-019-53939-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 10/09/2019] [Indexed: 02/06/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) acquires its lipid envelope during budding from the plasma membrane of the host cell. Various studies indicated that HIV-1 membranes differ from producer cell plasma membranes, suggesting budding from specialized membrane microdomains. The phosphoinositide PI(4,5)P2 has been of particular interest since PI(4,5)P2 is needed to recruit the viral structural polyprotein Gag to the plasma membrane and thus facilitates viral morphogenesis. While there is evidence for an enrichment of PIP2 in HIV-1, fully quantitative analysis of all phosphoinositides remains technically challenging and therefore has not been reported, yet. Here, we present a comprehensive analysis of the lipid content of HIV-1 and of plasma membranes from infected and non-infected producer cells, resulting in a total of 478 quantified lipid compounds, including molecular species distribution of 25 different lipid classes. Quantitative analyses of phosphoinositides revealed strong enrichment of PIP2, but also of PIP3, in the viral compared to the producer cell plasma membrane. We calculated an average of ca. 8,000 PIP2 molecules per HIV-1 particle, three times more than Gag. We speculate that the high density of PIP2 at the HIV-1 assembly site is mediated by transient interactions with viral Gag polyproteins, facilitating PIP2 concentration in this microdomain. These results are consistent with our previous observation that PIP2 is not only required for recruiting, but also for stably maintaining Gag at the plasma membrane. We believe that this quantitative analysis of the molecular anatomy of the HIV-1 lipid envelope may serve as standard reference for future investigations.
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Ichikawa J, Koshino I, Arashiki N, Nakamura F, Komori M. Changes in Erythrocyte Morphology at Initiation of Cardiopulmonary Bypass Without Blood Transfusion Were Not Associated With Less Deformability During Cardiac Surgery. J Cardiothorac Vasc Anesth 2019; 33:2960-2967. [DOI: 10.1053/j.jvca.2019.03.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 03/12/2019] [Accepted: 03/14/2019] [Indexed: 11/11/2022]
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Multivalent Cation-Bridged PI(4,5)P 2 Clusters Form at Very Low Concentrations. Biophys J 2019; 114:2630-2639. [PMID: 29874613 DOI: 10.1016/j.bpj.2018.04.048] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 03/27/2018] [Accepted: 04/10/2018] [Indexed: 01/09/2023] Open
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2 or PIP2), is a key component of the inner leaflet of the plasma membrane in eukaryotic cells. In model membranes, PIP2 has been reported to form clusters, but whether these locally different conditions could give rise to distinct pools of unclustered and clustered PIP2 is unclear. By use of both fluorescence self-quenching and Förster resonance energy transfer assays, we have discovered that PIP2 self-associates at remarkably low concentrations starting below 0.05 mol% of total lipids. Formation of these clusters was dependent on physiological divalent metal ions, such as Ca2+, Mg2+, Zn2+, or trivalent ions Fe3+ and Al3+. Formation of PIP2 clusters was also headgroup-specific, being largely independent of the type of acyl chain. The similarly labeled phospholipids phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol exhibited no such clustering. However, six phosphoinositide species coclustered with PIP2. The degree of PIP2 cation clustering was significantly influenced by the composition of the surrounding lipids, with cholesterol and phosphatidylinositol enhancing this behavior. We propose that PIP2 cation-bridged cluster formation, which might be similar to micelle formation, can be used as a physical model for what could be distinct pools of PIP2 in biological membranes. To our knowledge, this study provides the first evidence of PIP2 forming clusters at such low concentrations. The property of PIP2 to form such clusters at such extremely low concentrations in model membranes reveals, to our knowledge, a new behavior of PIP2 proposed to occur in cells, in which local multivalent metal ions, lipid compositions, and various binding proteins could greatly influence PIP2 properties. In turn, these different pools of PIP2 could further regulate cellular events.
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Tran RJ, Lalonde MS, Sly KL, Conboy JC. Mechanistic Investigation of HIV-1 Gag Association with Lipid Membranes. J Phys Chem B 2019; 123:4673-4687. [PMID: 31084006 DOI: 10.1021/acs.jpcb.9b02655] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An extensive investigation into the initial association of HIV-1 Gag with lipid membranes was conducted with second harmonic generation. The roles of the lipid phase, phospholipid 1,2-dioleoyl- sn-glycero-3-phospho-(1-myo-inositol-4,5-bisphosphate) [PI(4,5)P2], the presence of the myristoyl group on Gag, the C-terminus of Gag, and the presence of transfer ribonucleic acid (tRNA) in Gag-membrane association were examined using the physiologically most relevant full-length Gag protein studied thus far. The tighter packing of a bilayer composed of gel-phase lipids was found to have a lower relative amount of membrane-bound Gag in comparison to its fluid-phase counterpart. Rather than driving membrane association of Gag, the presence of PI(4,5)P2 and the myristoyl group were found to anchor Gag at the membrane by decreasing the rate of desorption. Specifically, the interaction with PI(4,5)P2 allows Gag to overcome electrostatic repulsion with negatively charged lipids at the membrane surface. This behavior was verified by measuring the binding properties of Gag mutants in the matrix domain of Gag, which prevented anchoring to the membrane either by blocking interaction with PI(4,5)P2 or by preventing exposure of the myristoyl group. The presence of tRNA was found to inhibit Gag association with the membrane by specifically blocking the PI(4,5)P2 binding region, thereby preventing exposure of the myristoyl group and precluding subsequent anchoring of Gag to the membrane. While Gag likely samples all membranes, only the anchoring provided by the myristoyl group and PI(4,5)P2 allows Gag to accumulate at the membrane. These quantitative results on the kinetics and thermodynamics of Gag association with lipid membranes provide important new information about the mechanism of Gag-membrane association.
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Affiliation(s)
- Renee J Tran
- Department of Chemistry , University of Utah , 315 South 1400 East, Room 2020 , Salt Lake City , Utah 84112 , United States
| | - Matthew S Lalonde
- Department of Biochemistry , University of Utah , 15 North Medical Drive East, Room 4100 , Salt Lake City , Utah 84112 , United States
| | - Krystal L Sly
- Department of Chemistry , University of Utah , 315 South 1400 East, Room 2020 , Salt Lake City , Utah 84112 , United States
| | - John C Conboy
- Department of Chemistry , University of Utah , 315 South 1400 East, Room 2020 , Salt Lake City , Utah 84112 , United States
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Abstract
Transition state theory teaches that chemically stable mimics of enzymatic transition states will bind tightly to their cognate enzymes. Kinetic isotope effects combined with computational quantum chemistry provides enzymatic transition state information with sufficient fidelity to design transition state analogues. Examples are selected from various stages of drug development to demonstrate the application of transition state theory, inhibitor design, physicochemical characterization of transition state analogues, and their progress in drug development.
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Affiliation(s)
- Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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Okahara S, Miyamoto S, Soh Z, Tsuji T. Detection of Echinocyte during Perfusion with Oxygenator Based on Continuous Blood Viscosity Monitoring. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2018:4448-4451. [PMID: 30441338 DOI: 10.1109/embc.2018.8513370] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We applied our proposed continuous blood viscosity monitoring system for cardiopulmonary bypass to an experimental model that introduced echinocytes, and we confirm the viscosity change detection due to red blood cell (RBC) deformability decline. For the in vitro experiment, a test circuit including an oxygenator and a controlled bovine blood sample with excessive alkalemia to induce the echinocyte were prepared, and a perfusion experiment was performed. During the experiment, the anticoagulated bovine blood sample maintained a hematocrit of approximately 22%, temperature of 37°C, and more than 800 s of the activated clotting time. The estimated viscosity obtained from the proposed system was 2.10 mPas at the beginning of the experiment and 3.58 mPas at the end of the experiment, and it increased 1.48 mPas during the experiment. According to the scanning electron micrographs of blood samples, the echinocytes with multiple spicules at the beginning of the experiment and distorted spherical RBCs including the echinocytes with multiple spicules at the end of experiment were observed. We conclude that the system may be helpful for clinical perfusion management, because it detected the presence of echinocytes as the blood viscosity in an oxygenator flow pass increased.
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Melzak KA, Uhlig S, Kirschhöfer F, Brenner-Weiss G, Bieback K. The Blood Bag Plasticizer Di-2-Ethylhexylphthalate Causes Red Blood Cells to Form Stomatocytes, Possibly by Inducing Lipid Flip-Flop. Transfus Med Hemother 2018; 45:413-422. [PMID: 30574059 DOI: 10.1159/000490502] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/26/2018] [Indexed: 12/13/2022] Open
Abstract
Background During storage of red blood cell (RBC) concentrates, the plasticizer di-2-ethylhexylphthalate (DEHP) that keeps the blood bags soft leaches out and can be taken up by the RBCs. DEHP is known to be beneficial for the RBC storage quality, but the molecular mechanisms of the action are unknown. Methods Aqueous suspensions of DEHP were added to RBCs in buffer. The morphological effects were observed on RBCs from 5 donors. Flow cytometry with annexin A5 binding was used to measure the exposed phosphatidylserine. Results DEHP induced the formation of stomatocytes at concentrations as low as ng/ml, provided that the cell suspension was also sufficiently dilute. Some spherocytes, which were susceptible to lysis, were also formed; after lysis, RBC ghosts were seen to continue the transition to the cup-shaped stomatocyte form. Incubation with DEHP increased the exposed phosphatidylserine, an effect that was also observed in the presence of vanadate, which inhibits the ATP-dependent translocases that maintain the membrane's lipid asymmetry. Conclusions DEHP can have an active effect on RBC shape, instead of just preventing the storage-related shape changes. The effect appears to be mediated by increased flip-flop of lipids between the leaflets of the RBC membrane.
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Affiliation(s)
- Kathryn A Melzak
- Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Stefanie Uhlig
- Institute for Transfusion Medicine and Immunology, Flowcore Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frank Kirschhöfer
- Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Gerald Brenner-Weiss
- Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Karen Bieback
- Institute for Transfusion Medicine and Immunology, Flowcore Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Cebecauer M, Amaro M, Jurkiewicz P, Sarmento MJ, Šachl R, Cwiklik L, Hof M. Membrane Lipid Nanodomains. Chem Rev 2018; 118:11259-11297. [PMID: 30362705 DOI: 10.1021/acs.chemrev.8b00322] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Lipid membranes can spontaneously organize their components into domains of different sizes and properties. The organization of membrane lipids into nanodomains might potentially play a role in vital functions of cells and organisms. Model membranes represent attractive systems to study lipid nanodomains, which cannot be directly addressed in living cells with the currently available methods. This review summarizes the knowledge on lipid nanodomains in model membranes and exposes how their specific character contrasts with large-scale phase separation. The overview on lipid nanodomains in membranes composed of diverse lipids (e.g., zwitterionic and anionic glycerophospholipids, ceramides, glycosphingolipids) and cholesterol aims to evidence the impact of chemical, electrostatic, and geometric properties of lipids on nanodomain formation. Furthermore, the effects of curvature, asymmetry, and ions on membrane nanodomains are shown to be highly relevant aspects that may also modulate lipid nanodomains in cellular membranes. Potential mechanisms responsible for the formation and dynamics of nanodomains are discussed with support from available theories and computational studies. A brief description of current fluorescence techniques and analytical tools that enabled progress in lipid nanodomain studies is also included. Further directions are proposed to successfully extend this research to cells.
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Affiliation(s)
- Marek Cebecauer
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Mariana Amaro
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Piotr Jurkiewicz
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Maria João Sarmento
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Lukasz Cwiklik
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
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Tied up: Does altering phosphoinositide-mediated membrane trafficking influence neurodegenerative disease phenotypes? J Genet 2018. [DOI: 10.1007/s12041-018-0961-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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20
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Nadiminti SSP, Kamak M, Koushika SP. Tied up: Does altering phosphoinositide-mediated membrane trafficking influence neurodegenerative disease phenotypes? J Genet 2018; 97:753-771. [PMID: 30027907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Phosphoinositides are a class of membrane lipids that are found on several intracellular compartments and play diverse roles inside cells, such as vesicle formation, protein trafficking, endocytosis etc. Intracellular distribution and levels of phosphoinositides are regulated by enzymes that generate and breakdown these lipids as well as other proteins that associate with phosphoinositides. These events lead to differing levels of specific phosphoinositides on different intracellular compartments. At these intracellular locations, phosphoinositides and their associated proteins, such as Rab GTPases, dynamin and BAR domain-containing proteins, regulate a variety of membrane trafficking pathways. Neurodegenerative phenotypes in disorders such as Parkinson's disease (PD) can arise as a consequence of altered or hampered intracellular trafficking. Altered trafficking can cause proteins such as α-synuclein to aggregate intracellularly. Several trafficking pathways are regulated bymaster regulators such as LRRK2,which is known to regulate the activity of phosphoinositide effector proteins. Perturbing either the levels of phosphoinositides or their interactions with different proteins disrupts intracellular trafficking pathways, contributing to phenotypes often observed in disorders such as Alzheimer's or PDs. Thus, studying phosphoinositide regulation and its role in trafficking can give us a deeper understanding of the contribution of disrupted trafficking to neurodegenerative phenotypes.
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Affiliation(s)
- Sravanthi S P Nadiminti
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400 005, India.
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21
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Ghosh S, Roy A, Chakraborty I, Mukhopadhyay M, DasGupta S, Sarkar D. Fractal Dimension of Erythrocyte Membranes: A Highly Useful Precursor for Rapid Morphological Assay. Ann Biomed Eng 2018; 46:1362-1375. [PMID: 29796956 DOI: 10.1007/s10439-018-2050-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/14/2018] [Indexed: 12/18/2022]
Abstract
Morphology of erythrocyte membrane has been recognized as an alternative biomarker of several patho-physiological states. Numerous attempts have been made to upgrade the existing method of primitive manual counting, particularly exploring the light scattering properties of erythrocyte. All the techniques are at best semi-empirical and heavily rely on the effectiveness of the statistical correlations. Precisely, this is due to the lack of a non-empirical scale of the so-called "morphological scores". In this article, fractal dimension of erythrocyte membrane has been used to formulate a suitable scoring scale. Subsequently, the rapid experimental output of flow-cytometry has been functionally related to the mean morphological quantifier of the whole cell population via an optimum neural network model (R2 = 0.98). Moreover, the fractal dimension has been further demonstrated to be an important parameter in early detection of an abnormal patho-physiological state, even without any noticeable poikilocytic transformation in micrometric domain.
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Affiliation(s)
- Sayari Ghosh
- Department of Chemical Engineering, University of Calcutta, Kolkata, 700 009, India
| | - Arpan Roy
- Department of Chemical Engineering, University of Calcutta, Kolkata, 700 009, India
| | - Ishita Chakraborty
- Department of Physiology, University of Calcutta, Kolkata, 700 009, India
| | | | - Sunando DasGupta
- Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, 721302, India
| | - Debasish Sarkar
- Department of Chemical Engineering, University of Calcutta, Kolkata, 700 009, India.
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22
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Buckles TC, Ziemba BP, Masson GR, Williams RL, Falke JJ. Single-Molecule Study Reveals How Receptor and Ras Synergistically Activate PI3Kα and PIP 3 Signaling. Biophys J 2017; 113:2396-2405. [PMID: 29211993 PMCID: PMC5738497 DOI: 10.1016/j.bpj.2017.09.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 09/15/2017] [Accepted: 09/15/2017] [Indexed: 02/07/2023] Open
Abstract
Cellular pathways controlling chemotaxis, growth, survival, and oncogenesis are activated by receptor tyrosine kinases and small G-proteins of the Ras superfamily that stimulate specific isoforms of phosphatidylinositol-3-kinase (PI3K). These PI3K lipid kinases phosphorylate the constitutive lipid phosphatidylinositol-4,5-bisphosphate (PIP2) to produce the signaling lipid phosphatidylinositol-3,4,5-trisphosphate (PIP3). Progress has been made in understanding direct, moderate PI3K activation by receptors. In contrast, the mechanism by which receptors and Ras synergistically activate PI3K to much higher levels remains unclear, and two competing models have been proposed: membrane recruitment versus activation of the membrane-bound enzyme. To resolve this central mechanistic question, this study employs single-molecule imaging to investigate PI3K activation in a six-component pathway reconstituted on a supported lipid bilayer. The findings reveal that simultaneous activation by a receptor activation loop (from platelet-derived growth factor receptor, a receptor tyrosine kinase) and H-Ras generates strong, synergistic activation of PI3Kα, yielding a large increase in net kinase activity via the membrane recruitment mechanism. Synergy requires receptor phospho-Tyr and two anionic lipids (phosphatidylserine and PIP2) to make PI3Kα competent for bilayer docking, as well as for subsequent binding and phosphorylation of substrate PIP2 to generate product PIP3. Synergy also requires recruitment to membrane-bound H-Ras, which greatly speeds the formation of a stable, membrane-bound PI3Kα complex, modestly slows its off rate, and dramatically increases its equilibrium surface density. Surprisingly, H-Ras binding significantly inhibits the specific kinase activity of the membrane-bound PI3Kα molecule, but this minor enzyme inhibition is overwhelmed by the marked enhancement of membrane recruitment. The findings have direct impacts for the fields of chemotaxis, innate immunity, inflammation, carcinogenesis, and drug design.
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Affiliation(s)
- Thomas C Buckles
- Molecular Biophysics Program and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado
| | - Brian P Ziemba
- Molecular Biophysics Program and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado
| | - Glenn R Masson
- Medical Research Council, Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Roger L Williams
- Medical Research Council, Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Joseph J Falke
- Molecular Biophysics Program and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado.
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Sarmento MJ, Coutinho A, Fedorov A, Prieto M, Fernandes F. Membrane Order Is a Key Regulator of Divalent Cation-Induced Clustering of PI(3,5)P 2 and PI(4,5)P 2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:12463-12477. [PMID: 28961003 DOI: 10.1021/acs.langmuir.7b00666] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Although the evidence for the presence of functionally important nanosized phosphorylated phosphoinositide (PIP)-rich domains within cellular membranes has accumulated, very limited information is available regarding the structural determinants for compartmentalization of these phospholipids. Here, we used a combination of fluorescence spectroscopy and microscopy techniques to characterize differences in divalent cation-induced clustering of PI(4,5)P2 and PI(3,5)P2. Through these methodologies we were able to detect differences in divalent cation-induced clustering efficiency and cluster size. Ca2+-induced PI(4,5)P2 clusters are shown to be significantly larger than the ones observed for PI(3,5)P2. Clustering of PI(4,5)P2 is also detected at physiological concentrations of Mg2+, suggesting that in cellular membranes, these molecules are constitutively driven to clustering by the high intracellular concentration of divalent cations. Importantly, it is shown that lipid membrane order is a key factor in the regulation of clustering for both PIP isoforms, with a major impact on cluster sizes. Clustered PI(4,5)P2 and PI(3,5)P2 are observed to present considerably higher affinity for more ordered lipid phases than the monomeric species or than PI(4)P, possibly reflecting a more general tendency of clustered lipids for insertion into ordered domains. These results support a model for the description of the lateral organization of PIPs in cellular membranes, where both divalent cation interaction and membrane order are key modulators defining the lateral organization of these lipids.
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Affiliation(s)
- Maria J Sarmento
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon , 1649-004 Lisbon, Portugal
- J. Heyrovský Inst. Physical Chemistry of the A.S.C.R. v.v.i. , 182 23 Prague, Czech Republic
| | - Ana Coutinho
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon , 1649-004 Lisbon, Portugal
- Departamento de Química e Bioquímica, FCUL, University of Lisbon , 1649-004 Lisbon, Portugal
| | - Aleksander Fedorov
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon , 1649-004 Lisbon, Portugal
| | - Manuel Prieto
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon , 1649-004 Lisbon, Portugal
| | - Fábio Fernandes
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon , 1649-004 Lisbon, Portugal
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , Campus da Caparica, 2829-516 Caparica, Portugal
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Regulation of PI3K by PKC and MARCKS: Single-Molecule Analysis of a Reconstituted Signaling Pathway. Biophys J 2017; 110:1811-1825. [PMID: 27119641 DOI: 10.1016/j.bpj.2016.03.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 02/09/2016] [Accepted: 03/07/2016] [Indexed: 12/19/2022] Open
Abstract
In chemotaxing ameboid cells, a complex leading-edge signaling circuit forms on the cytoplasmic leaflet of the plasma membrane and directs both actin and membrane remodeling to propel the leading edge up an attractant gradient. This leading-edge circuit includes a putative amplification module in which Ca(2+)-protein kinase C (Ca(2+)-PKC) is hypothesized to phosphorylate myristoylated alanine-rich C kinase substrate (MARCKS) and release phosphatidylinositol-4,5-bisphosphate (PIP2), thereby stimulating production of the signaling lipid phosphatidylinositol-3,4,5-trisphosphate (PIP3) by the lipid kinase phosphoinositide-3-kinase (PI3K). We investigated this hypothesized Ca(2+)-PKC-MARCKS-PIP2-PI3K-PIP3 amplification module and tested its key predictions using single-molecule fluorescence to measure the surface densities and activities of its protein components. Our findings demonstrate that together Ca(2+)-PKC and the PIP2-binding peptide of MARCKS modulate the level of free PIP2, which serves as both a docking target and substrate lipid for PI3K. In the off state of the amplification module, the MARCKS peptide sequesters PIP2 and thereby inhibits PI3K binding to the membrane. In the on state, Ca(2+)-PKC phosphorylation of the MARCKS peptide reverses the PIP2 sequestration, thereby releasing multiple PIP2 molecules that recruit multiple active PI3K molecules to the membrane surface. These findings 1) show that the Ca(2+)-PKC-MARCKS-PIP2-PI3K-PIP3 system functions as an activation module in vitro, 2) reveal the molecular mechanism of activation, 3) are consistent with available in vivo data, and 4) yield additional predictions that are testable in live cells. More broadly, the Ca(2+)-PKC-stimulated release of free PIP2 may well regulate the membrane association of other PIP2-binding proteins, and the findings illustrate the power of single-molecule analysis to elucidate key dynamic and mechanistic features of multiprotein signaling pathways on membrane surfaces.
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25
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In vitro effects of the anti-Alzheimer drug memantine on the human erythrocyte membrane and molecular models. Biochem Biophys Res Commun 2017; 483:528-533. [DOI: 10.1016/j.bbrc.2016.12.111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 12/16/2016] [Indexed: 11/23/2022]
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Mondal R, Biswas S, Chatterjee A, Mishra R, Mukhopadhyay A, Bhadra RK, Mukhopadhyay PK. Protection against arsenic-induced hematological and hepatic anomalies by supplementation of vitamin C and vitamin E in adult male rats. J Basic Clin Physiol Pharmacol 2016; 27:643-652. [PMID: 27464034 DOI: 10.1515/jbcpp-2016-0020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 06/27/2016] [Indexed: 05/20/2023]
Abstract
BACKGROUND Chronic arsenic exposure via contaminated drinking water is a global environmental health problem associated with hematological, hepatic and many serious systemic disorders. This study on adult male rats evaluated the protective effects of vitamin E (VE) and vitamin C (VC) against arsenic-mediated hematological and hepatic toxicities. METHODS Arsenic was administered orally as arsenic trioxide (3 mg/kg body weight/day), as a single dose for 30 consecutive days or along with VC/ascorbic acid (200 mg/kg body weight/day dissolved in water) and VE/α-tocopherol (400 mg/kg body weight/day dissolved in olive oil) as supplements. Multiple hematological and hepatic parameters were assessed. RESULTS Arsenic exposure caused significant reduction of erythrocyte counts (p<0.05), leukocyte counts (p<0.01) and hemoglobin (Hb) levels (p<0.01). Arsenic exposure also led to marked echinocytic transformation of erythrocytes resulting in increased morphological index (p<0.001). Altered serum oxidative balance was observed with a higher oxidative stress index (p<0.001). The results also showed a significant increase of serum cholesterol (p<0.05), low-density lipoprotein (p<0.001) and triglycerides (p<0.01), and decreased high-density lipoprotein (p<0.01) along with total protein (p<0.01). A marked elevation of hepatic thiobarbituric acid reactive substance (p<0.05) along with decreased reduced glutathione (p<0.001) levels were also observed. Interestingly, co-administration of VC and VE significantly prevented all the arsenic-induced alterations (p<0.05) except Hb content and serum protein. CONCLUSIONS The present investigation offers strong evidence regarding the protective efficacy of co-administration of VC and VE against hematotoxicity and hepatotoxicity in adult male rats caused by chronic arsenic exposure.
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Abstract
Ptdns(4,5)P2 is a minor structural lipid of the plasma membrane (PM), but a master regulator of PM function. Serving either as a substrate for the generation of second messengers, or more commonly as a ligand triggering protein recruitment or activation, it regulates most aspects of PM function. Understanding how this relatively simple biological macromolecule can regulate such a vast array of different functions in parallel, is the key to understanding the biology of the PM as a whole, in both health and disease. In this review, potential mechanisms are discussed that might explain how a lipid can separately regulate so many protein complexes. The focus is on the spatial distribution of the lipid molecules, their metabolism and their interactions. Open questions that still need to be resolved are highlighted, as are potential experimental approaches that might shed light on the mechanisms at play. Moreover, the broader question is raised as to whether PtdIns(4,5)P2 should be thought of as a bona fide signalling molecule or more of a simple lipid cofactor or perhaps both, depending on the context of the particular function in question.
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Murate M, Kobayashi T. Revisiting transbilayer distribution of lipids in the plasma membrane. Chem Phys Lipids 2016; 194:58-71. [DOI: 10.1016/j.chemphyslip.2015.08.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 08/14/2015] [Accepted: 08/17/2015] [Indexed: 12/22/2022]
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PIP2Clustering: From model membranes to cells. Chem Phys Lipids 2015; 192:33-40. [DOI: 10.1016/j.chemphyslip.2015.07.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 07/26/2015] [Accepted: 07/27/2015] [Indexed: 11/23/2022]
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Reinhart SA, Schulzki T, Reinhart WH. Albumin reverses the echinocytic shape transformation of stored erythrocytes. Clin Hemorheol Microcirc 2015; 60:437-49. [DOI: 10.3233/ch-141899] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Sophie A. Reinhart
- Department of Internal Medicine, Kantonsspital Graubünden, Chur, Switzerland
| | - Thomas Schulzki
- Division of Transfusion Medicine, Kantonsspital Graubünden, Chur, Switzerland
| | - Walter H. Reinhart
- Department of Internal Medicine, Kantonsspital Graubünden, Chur, Switzerland
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Reinhart WH, Piety NZ, Deuel JW, Makhro A, Schulzki T, Bogdanov N, Goede JS, Bogdanova A, Abidi R, Shevkoplyas SS. Washing stored red blood cells in an albumin solution improves their morphologic and hemorheologic properties. Transfusion 2015; 55:1872-81. [PMID: 25752902 DOI: 10.1111/trf.13052] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 01/04/2015] [Accepted: 01/19/2015] [Indexed: 12/12/2022]
Abstract
BACKGROUND Prolonged storage of red blood cells (RBCs) leads to storage lesions, which may impair clinical outcomes after transfusion. A hallmark of storage lesions is progressive echinocytic shape transformation, which can be partially reversed by washing in albumin solutions. Here we have investigated the impact of this shape recovery on biorheologic variables. STUDY DESIGN AND METHODS RBCs stored hypothermically for 6 to 7 weeks were washed in a 1% human serum albumin (HSA) solution. RBC deformability was measured with osmotic gradient ektacytometry. The viscosity of RBC suspensions was measured with a Couette-type viscometer. The flow behavior of RBCs suspended at 40% hematocrit was tested with an artificial microvascular network (AMVN). RESULTS Washing in 1% albumin reduced higher degrees of echinocytes and increased the frequency of discocytes, thereby shifting the morphologic index toward discocytosis. Washing also reduced RBC swelling. This shape recovery was not seen after washing in saline, buffer, or plasma. RBC shape normalization did not improve cell deformability measured by ektacytometry, but it tended to decrease suspension viscosities at low shear rates and improved the perfusion of an AMVN. CONCLUSIONS Washing of stored RBCs in a 1% HSA solution specifically reduces echinocytosis, and this shape recovery has a beneficial effect on microvascular perfusion in vitro. Washing in 1% albumin may represent a new approach to improving the quality of stored RBCs and thus potentially reducing the likelihood of adverse clinical outcomes associated with transfusion of blood stored for longer periods of time.
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Affiliation(s)
- Walter H Reinhart
- Department of Internal Medicine, Kantonsspital Graubünden, Chur, Switzerland
| | - Nathaniel Z Piety
- Department of Biomedical Engineering, University of Houston, Houston, Texas
| | | | - Asya Makhro
- Institute of Veterinary Physiology, University of Zürich, Zürich, Switzerland
| | - Thomas Schulzki
- Department of Internal Medicine, Kantonsspital Graubünden, Chur, Switzerland
| | - Nikolay Bogdanov
- Institute of Veterinary Physiology, University of Zürich, Zürich, Switzerland
| | | | - Anna Bogdanova
- Institute of Veterinary Physiology, University of Zürich, Zürich, Switzerland
| | - Rajaa Abidi
- Department of Biomedical Engineering, University of Houston, Houston, Texas
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Wan C, Wu B, Song Z, Zhang J, Chu H, Wang A, Liu Q, Shi Y, Li G, Wang J. Insights into the molecular recognition of the granuphilin C2A domain with PI(4,5)P2. Chem Phys Lipids 2015; 186:61-7. [PMID: 25595293 DOI: 10.1016/j.chemphyslip.2015.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/11/2015] [Accepted: 01/12/2015] [Indexed: 01/06/2023]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a key player in regulating the process of excytosis, including insulin secretion. Granuphilin, a tandem C2 domain containing protein, mediates the docking of insulin granules onto plasma membrane. The C2A domain plays key roles in this process through interaction with PI(4,5)P2. In this study, we have investigated the molecular recognition mechanism of granuphilin-C2A domain to PI(4,5)P2 head group, and further to PI(4,5)P2-nanodisc by NMR, ITC, MST and SEC methods. Our results demonstrate that PI(4,5)P2 binds to the concave surface of granuphilin-C2A domain. The key residues involved in the binding were validated by mutation analysis.
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Affiliation(s)
- Chanjuan Wan
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, PR China
| | - Bo Wu
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, PR China.
| | - Zhenwei Song
- Heifei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei 230027, PR China
| | - Jiahai Zhang
- Heifei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei 230027, PR China
| | - Huiying Chu
- Laboratory of Molecular Modeling and Design, State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Rd., Dalian 116023, PR China
| | - Aoli Wang
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, PR China
| | - Qingsong Liu
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, PR China
| | - Yunyu Shi
- Heifei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei 230027, PR China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Rd., Dalian 116023, PR China
| | - Junfeng Wang
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, PR China.
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Reinhart WH, Lubszky S, Thöny S, Schulzki T. Interaction of injectable neurotropic drugs with the red cell membrane. Toxicol In Vitro 2014; 28:1274-9. [DOI: 10.1016/j.tiv.2014.06.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 06/12/2014] [Accepted: 06/23/2014] [Indexed: 11/30/2022]
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Sato H, Frank DW. Intoxication of host cells by the T3SS phospholipase ExoU: PI(4,5)P2-associated, cytoskeletal collapse and late phase membrane blebbing. PLoS One 2014; 9:e103127. [PMID: 25061861 PMCID: PMC4111512 DOI: 10.1371/journal.pone.0103127] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 06/27/2014] [Indexed: 01/09/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that is associated with hospital-acquired infections, ventilator-associated pneumonia, and morbidity of immunocompromised individuals. A subpopulation of P. aeruginosa encodes a protein, ExoU, which exhibits acute cytotoxicity. Toxicity is directly related to the phospholipase A2 activity of the protein after injection into the host cytoplasm via a type III secretion system. ExoU enzymatic activity requires eukaryotic cofactors, ubiquitin or ubiquitin-modified proteins. When administered extracellularly, ExoU is unable to intoxicate epithelial cells in culture, even in the presence of the cofactor. Injection or transfection of ExoU is necessary to observe the acute cytotoxic response. Biochemical approaches indicate that ExoU possesses high affinity to a multifunctional phosphoinositide, phosphatidylinositol 4,5-bisphosphate or PI(4,5)P2 and that it is capable of utilizing this phospholipid as a substrate. In eukaryotic cells, PI(4,5)P2 is mainly located in the cytoplasmic side of the plasma membrane and anchors adaptor proteins that are involved in cytoskeletal structures, focal adhesions, and plasma membranes. Time-lapse fluorescent microscopy analyses of infected live cells demonstrate that ExoU intoxication correlates with intracellular damage in the early phases of infection, such as disruption of focal adhesions, cytoskeletal collapse, actin depolymerization, and cell rounding. At later time points, a membrane blebbing phenotype was prominent prior to the loss of the plasma membrane integrity and barrier function. Membrane blebbing appears to accelerate membrane rupture and the release of intracellular markers. Our data suggest that in eukaryotic host cells, intracellular ExoU targets and hydrolyzes PI(4,5)P2 on the plasma membrane, causing a subsequent disruption of cellular structures and membrane integrity.
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Affiliation(s)
- Hiromi Sato
- Center for Infectious Disease Research, Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- * E-mail:
| | - Dara W. Frank
- Center for Infectious Disease Research, Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
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Rusinova R, Hobart EA, Koeppe RE, Andersen OS. Phosphoinositides alter lipid bilayer properties. ACTA ACUST UNITED AC 2013; 141:673-90. [PMID: 23712549 PMCID: PMC3664701 DOI: 10.1085/jgp.201310960] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Phosphatidylinositol-4,5-bisphosphate (PIP2), which constitutes ∼1% of the plasma membrane phospholipid, plays a key role in membrane-delimited signaling. PIP2 regulates structurally and functionally diverse membrane proteins, including voltage- and ligand-gated ion channels, inwardly rectifying ion channels, transporters, and receptors. In some cases, the regulation is known to involve specific lipid–protein interactions, but the mechanisms by which PIP2 regulates many of its various targets remain to be fully elucidated. Because many PIP2 targets are membrane-spanning proteins, we explored whether the phosphoinositides might alter bilayer physical properties such as curvature and elasticity, which would alter the equilibrium between membrane protein conformational states—and thereby protein function. Taking advantage of the gramicidin A (gA) channels’ sensitivity to changes in lipid bilayer properties, we used gA-based fluorescence quenching and single-channel assays to examine the effects of long-chain PIP2s (brain PIP2, which is predominantly 1-stearyl-2-arachidonyl-PIP2, and dioleoyl-PIP2) on bilayer properties. When premixed with dioleoyl-phosphocholine at 2 mol %, both long-chain PIP2s produced similar changes in gA channel function (bilayer properties); when applied through the aqueous solution, however, brain PIP2 was a more potent modifier than dioleoyl-PIP2. Given the widespread use of short-chain dioctanoyl-phosphoinositides, we also examined the effects of diC8-phosphoinositol (PI), PI(4,5)P2, PI(3,5)P2, PI(3,4)P2, and PI(3,4,5)P3. The diC8 phosphoinositides, except for PI(3,5)P2, altered bilayer properties with potencies that decreased with increasing head group charge. Nonphosphoinositide diC8 phospholipids generally were more potent bilayer modifiers than the polyphosphoinositides. These results show that physiological increases or decreases in plasma membrane PIP2 levels, as a result of activation of PI kinases or phosphatases, are likely to alter lipid bilayer properties, in addition to any other effects they may have. The results further show that exogenous PIP2, as well as structural analogues that differ in acyl chain length or phosphorylation state, alters lipid bilayer properties at the concentrations used in many cell physiological experiments.
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Affiliation(s)
- Radda Rusinova
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA.
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Sarmento MJ, Coutinho A, Fedorov A, Prieto M, Fernandes F. Ca(2+) induces PI(4,5)P2 clusters on lipid bilayers at physiological PI(4,5)P2 and Ca(2+) concentrations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:822-30. [PMID: 24316170 DOI: 10.1016/j.bbamem.2013.11.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/22/2013] [Accepted: 11/26/2013] [Indexed: 01/22/2023]
Abstract
Calcium has been shown to induce clustering of PI(4,5)P2 at high and non-physiological concentrations of both the divalent ion and the phosphatidylinositol, or on supported lipid monolayers. In lipid bilayers at physiological conditions, clusters are not detected through microscopic techniques. Here, we aimed to determine through spectroscopic methodologies if calcium plays a role in PI(4,5)P2 lateral distribution on lipid bilayers under physiological conditions. Using several different approaches which included information on fluorescence quantum yield, polarization, spectra and diffusion properties of a fluorescent derivative of PI(4,5)P2 (TopFluor(TF)-PI(4,5)P2), we show that Ca(2+) promotes PI(4,5)P2 clustering in lipid bilayers at physiological concentrations of both Ca(2+) and PI(4,5)P2. Fluorescence depolarization data of TF-PI(4,5)P2 in the presence of calcium suggests that under physiological concentrations of PI(4,5)P2 and calcium, the average cluster size comprises ~15 PI(4,5)P2 molecules. The presence of Ca(2+)-induced PI(4,5)P2 clusters is supported by FCS data. Additionally, calcium mediated PI(4,5)P2 clustering was more pronounced in liquid ordered (lo) membranes, and the PI(4,5)P2-Ca(2+) clusters presented an increased affinity for lo domains. In this way, PI(4,5)P2 could function as a lipid calcium sensor and the increased efficiency of calcium-mediated PI(4,5)P2 clustering on lo domains might provide targeted nucleation sites for PI(4,5)P2 clusters upon calcium stimulus.
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Affiliation(s)
- Maria J Sarmento
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal
| | - Ana Coutinho
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal; Departamento de Química e Bioquímica, FCUL, University of Lisbon, Lisbon, Portugal
| | - Aleksander Fedorov
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal
| | - Manuel Prieto
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal
| | - Fabio Fernandes
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal.
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Phosphatidylinositol 4,5-bisphosphate is a novel coactivator of the Pseudomonas aeruginosa cytotoxin ExoU. Infect Immun 2013; 81:2873-81. [PMID: 23716613 DOI: 10.1128/iai.00414-13] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ExoU is a potent phospholipase A2 effector protein secreted by the type III secretion system of Pseudomonas aeruginosa. By cleaving plasma membrane phospholipids, it causes rapid lysis of eukaryotic cells. However, ExoU does not exhibit activity on its own but instead requires eukaryotic cell cofactors for activation. Ubiquitin and ubiquitinated proteins have been shown to activate ExoU, but previous work suggested that other cofactors are also involved. In this study, we demonstrate that phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is another important coactivator of ExoU. PI(4,5)P2 works synergistically with ubiquitin to greatly enhance the phospholipase A2 activity of ExoU. Distinct residues of ExoU were critical for activation by PI(4,5)P2 and by ubiquitin, indicating that these factors activate ExoU by discrete mechanisms. In support of the biological relevance of PI(4,5)P2 coactivation, a yeast mutant with reduced PI(4,5)P2 levels was less susceptible to the cytotoxic activity of ExoU. Together, these findings further elaborate the molecular mechanism of ExoU.
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38
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Hazleton KZ, Ho MC, Cassera MB, Clinch K, Crump DR, Rosario I, Merino EF, Almo SC, Tyler PC, Schramm VL. Acyclic immucillin phosphonates: second-generation inhibitors of Plasmodium falciparum hypoxanthine-guanine-xanthine phosphoribosyltransferase. CHEMISTRY & BIOLOGY 2012; 19:721-30. [PMID: 22726686 PMCID: PMC3397391 DOI: 10.1016/j.chembiol.2012.04.012] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/03/2012] [Accepted: 04/06/2012] [Indexed: 01/07/2023]
Abstract
Plasmodium falciparum, the primary cause of deaths from malaria, is a purine auxotroph and relies on hypoxanthine salvage from the host purine pool. Purine starvation as an antimalarial target has been validated by inhibition of purine nucleoside phosphorylase. Hypoxanthine depletion kills Plasmodium falciparum in cell culture and in Aotus monkey infections. Hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) from P. falciparum is required for hypoxanthine salvage by forming inosine 5'-monophosphate, a branchpoint for all purine nucleotide synthesis in the parasite. Here, we present a class of HGXPRT inhibitors, the acyclic immucillin phosphonates (AIPs), and cell permeable AIP prodrugs. The AIPs are simple, potent, selective, and biologically stable inhibitors. The AIP prodrugs block proliferation of cultured parasites by inhibiting the incorporation of hypoxanthine into the parasite nucleotide pool and validates HGXPRT as a target in malaria.
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Affiliation(s)
- Keith Z. Hazleton
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461, USA
| | - Meng-Chiao Ho
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461, USA
| | - Maria B. Cassera
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461, USA
| | - Keith Clinch
- Carbohydrate Chemistry Group, Industrial Research Ltd., 69 Gracefield Road, Lower Hutt 5040, New Zealand
| | - Douglas R. Crump
- Carbohydrate Chemistry Group, Industrial Research Ltd., 69 Gracefield Road, Lower Hutt 5040, New Zealand
| | - Irving Rosario
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461, USA
| | - Emilio F. Merino
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461, USA
| | - Steve C. Almo
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461, USA
| | - Peter C. Tyler
- Carbohydrate Chemistry Group, Industrial Research Ltd., 69 Gracefield Road, Lower Hutt 5040, New Zealand
| | - Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461, USA,, phone: 718-430-2814, fax: 718-430-8565
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Ischebeck T, Seiler S, Heilmann I. At the poles across kingdoms: phosphoinositides and polar tip growth. PROTOPLASMA 2010; 240:13-31. [PMID: 20091065 PMCID: PMC2841259 DOI: 10.1007/s00709-009-0093-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 11/20/2009] [Indexed: 05/20/2023]
Abstract
Phosphoinositides (PIs) are minor, but essential phospholipid constituents of eukaryotic membranes, and are involved in the regulation of various physiological processes. Recent genetic and cell biological advances indicate that PIs play important roles in the control of polar tip growth in plant cells. In root hairs and pollen tubes, PIs control directional membrane trafficking required for the delivery of cell wall material and membrane area to the growing tip. So far, the exact mechanisms by which PIs control polarity and tip growth are unresolved. However, data gained from the analysis of plant, fungal and animal systems implicate PIs in the control of cytoskeletal dynamics, ion channel activity as well as vesicle trafficking. The present review aims at giving an overview of PI roles in eukaryotic cells with a special focus on functions pertaining to the control of cell polarity. Comparative screening of plant and fungal genomes suggests diversification of the PI system with increasing organismic complexity. The evolutionary conservation of the PI system among eukaryotic cells suggests a role for PIs in tip growing cells in models where PIs so far have not been a focus of attention, such as fungal hyphae.
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Affiliation(s)
- Till Ischebeck
- Department of Plant Biochemistry, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Stephan Seiler
- Department of Microbiology and Genetics; and DFG Research Center Molecular Physiology of the Brain (CMPB), Georg-August-University Göttingen, Grisebachstraße 8, 37077 Göttingen, Germany
| | - Ingo Heilmann
- Department of Plant Biochemistry, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
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Saarikangas J, Zhao H, Lappalainen P. Regulation of the actin cytoskeleton-plasma membrane interplay by phosphoinositides. Physiol Rev 2010; 90:259-89. [PMID: 20086078 DOI: 10.1152/physrev.00036.2009] [Citation(s) in RCA: 362] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The plasma membrane and the underlying cortical actin cytoskeleton undergo continuous dynamic interplay that is responsible for many essential aspects of cell physiology. Polymerization of actin filaments against cellular membranes provides the force for a number of cellular processes such as migration, morphogenesis, and endocytosis. Plasma membrane phosphoinositides (especially phosphatidylinositol bis- and trisphosphates) play a central role in regulating the organization and dynamics of the actin cytoskeleton by acting as platforms for protein recruitment, by triggering signaling cascades, and by directly regulating the activities of actin-binding proteins. Furthermore, a number of actin-associated proteins, such as BAR domain proteins, are capable of directly deforming phosphoinositide-rich membranes to induce plasma membrane protrusions or invaginations. Recent studies have also provided evidence that the actin cytoskeleton-plasma membrane interactions are misregulated in a number of pathological conditions such as cancer and during pathogen invasion. Here, we summarize the wealth of knowledge on how the cortical actin cytoskeleton is regulated by phosphoinositides during various cell biological processes. We also discuss the mechanisms by which interplay between actin dynamics and certain membrane deforming proteins regulate the morphology of the plasma membrane.
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Affiliation(s)
- Juha Saarikangas
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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Levental I, Christian DA, Wang YH, Madara JJ, Discher DE, Janmey PA. Calcium-dependent lateral organization in phosphatidylinositol 4,5-bisphosphate (PIP2)- and cholesterol-containing monolayers. Biochemistry 2009; 48:8241-8. [PMID: 19630438 DOI: 10.1021/bi9007879] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biological membrane function, in part, depends upon the local regulation of lipid composition. The spatial heterogeneity of membrane lipids has been extensively explored in the context of cholesterol and phospholipid acyl-chain-dependent domain formation, but the effects of lipid head groups and soluble factors in lateral lipid organization are less clear. In this contribution, the effects of divalent calcium ions on domain formation in monolayers containing phosphatidylinositol 4,5-bisphosphate (PIP2), a polyanionic, multifunctional lipid of the cytosolic leaflet of the plasma bilayer, are reported. In binary monolayers of PIP2 mixed with zwitterionic lipids, calcium induced a rapid, PIP2-dependent surface pressure drop, with the concomitant formation of laterally segregated, PIP2-rich domains. The effect was dependent upon head-group multivalency, because lowered pH suppressed the surface-pressure effect and domain formation. In accordance with previous observations, inclusion of cholesterol in lipid mixtures induced coexistence of two liquid phases. Phase separation strongly segregated PIP2 to the cholesterol-poor phase, suggesting a role for cholesterol-dependent lipid demixing in regulating PIP2 localization and local concentration. Similar to binary mixtures, subphase calcium induced contraction of ternary cholesterol-containing monolayers; however, in these mixtures, calcium induced an unexpected, PIP2- and multivalency-dependent decrease in the miscibility phase transition surface pressure, resulting in rapid dissolution of the domains. This result emphasizes the likely critical role of subphase factors and lipid head-group specificity in the formation and stability of cholesterol-dependent domains in cellular plasma membranes.
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Affiliation(s)
- Ilya Levental
- Department of Bioengineering, University of Pennsylvania, Philadelphia,Pennsylvania 19104, USA
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Profilin interaction with phosphatidylinositol (4,5)-bisphosphate destabilizes the membrane of giant unilamellar vesicles. Biophys J 2009; 96:5112-21. [PMID: 19527671 DOI: 10.1016/j.bpj.2009.03.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2008] [Revised: 03/23/2009] [Accepted: 03/24/2009] [Indexed: 11/22/2022] Open
Abstract
Profilin, a small cytoskeletal protein, and phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] have been implicated in cellular events that alter the cell morphology, such as endocytosis, cell motility, and formation of the cleavage furrow during cytokinesis. Profilin has been shown to interact with PI(4,5)P2, but the role of this interaction is still poorly understood. Using giant unilamellar vesicles (GUVs) as a simple model of the cell membrane, we investigated the interaction between profilin and PI(4,5)P2. A number and brightness analysis demonstrated that in the absence of profilin, molar ratios of PI(4,5)P2 above 4% result in lipid demixing and cluster formations. Furthermore, adding profilin to GUVs made with 1% PI(4,5)P2 leads to the formation of clusters of both profilin and PI(4,5)P2. However, due to the self-quenching of the dipyrrometheneboron difluoride-labeled PI(4,5)P2, we were unable to determine the size of these clusters. Finally, we show that the formation of these clusters results in the destabilization and deformation of the GUV membrane.
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Gao J, Takeuchi H, Zhang Z, Fujii M, Kanematsu T, Hirata M. Binding of phospholipase C-related but catalytically inactive protein to phosphatidylinositol 4,5-bisphosphate via the PH domain. Cell Signal 2009; 21:1180-6. [DOI: 10.1016/j.cellsig.2009.03.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Accepted: 03/09/2009] [Indexed: 10/21/2022]
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Maha AA. Effect of glucose-6-phosphate dehydrogenase deficiency on some biophysical properties of human erythrocytes. ACTA ACUST UNITED AC 2009; 14:38-45. [PMID: 19154663 DOI: 10.1179/102453309x385061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The most widespread erythrocyte enzyme defect throughout the world is glucose-6-phosphate dehydrogenase (G-6-PD) deficiency. The diagnosis of G-6-PD deficiency may be missed during an acute hemolytic episode due to increased young red blood cells which have good enzyme activity. However this might be detected at a later stage when the patient is asymptomatic. This calls for a detailed investigation of the patient with an acute attack of hemolysis at a later stage. Blood samples were obtained from 45 G-6-PD deficient male patients with previously diagnosed disease [25 subjects were during hemolytic attack (Gp1) while the rest was outside acute hemolytic crisis (Gp2)] and 20 healthy male subjects. The effect of G-6-PD deficiency on the erythrocytes of the above groups was investigated by scanning electron microscope (SEM) complemented with dielectric spectroscopy. The quantification of the morphological shape changes revealed that Gp1 had a significant increase in spheroechinocytes as well as in the morphological index in comparison with those of all other groups. The overall electrical and morphological properties of the red cell membrane of these subjects modified to a great extent during hemolytic attack. This may have important diagnostic and research implications. Thus the combined application of dielectric spectroscopy and SEM can be used as an efficient manner for monitoring abnormalities in blood and erythrocytes due to G-6-PD deficiency.
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Affiliation(s)
- Anwar Ali Maha
- Department of Biophysics, Faculty of Science, Cairo University, Giza, Egypt.
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Söderberg L, Haag L, Höglund P, Roth B, Stenberg P, Wahlgren M. The effects of lipophilic substances on the shape of erythrocytes demonstrated by a new in vitro-method. Eur J Pharm Sci 2009; 36:458-64. [DOI: 10.1016/j.ejps.2008.11.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 11/13/2008] [Accepted: 11/26/2008] [Indexed: 11/27/2022]
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Abstract
Membrane fusion underlies many cellular events, including secretion, exocytosis, endocytosis, organelle reconstitution, transport from endoplasmic reticulum to Golgi and nuclear envelope formation. A large number of investigations into membrane fusion indicate various roles for individual members of the phosphoinositide class of membrane lipids. We first review the phosphoinositides as membrane recognition sites and their regulatory functions in membrane fusion. We then consider how modulation of phosphoinositides and their products may affect the structure and dynamics of natural membranes facilitating fusion. These diverse roles underscore the importance of these phospholipids in the fusion of biological membranes.
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Zehnder L, Schulzki T, Goede JS, Hayes J, Reinhart WH. Erythrocyte storage in hypertonic (SAGM) or isotonic (PAGGSM) conservation medium: influence on cell properties. Vox Sang 2008; 95:280-7. [DOI: 10.1111/j.1423-0410.2008.01097.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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James DJ, Khodthong C, Kowalchyk JA, Martin TFJ. Phosphatidylinositol 4,5-bisphosphate regulates SNARE-dependent membrane fusion. ACTA ACUST UNITED AC 2008; 182:355-66. [PMID: 18644890 PMCID: PMC2483516 DOI: 10.1083/jcb.200801056] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI 4,5-P2) on the plasma membrane is essential for vesicle exocytosis but its role in membrane fusion has not been determined. Here, we quantify the concentration of PI 4,5-P2 as ∼6 mol% in the cytoplasmic leaflet of plasma membrane microdomains at sites of docked vesicles. At this concentration of PI 4,5-P2 soluble NSF attachment protein receptor (SNARE)–dependent liposome fusion is inhibited. Inhibition by PI 4,5-P2 likely results from its intrinsic positive curvature–promoting properties that inhibit formation of high negative curvature membrane fusion intermediates. Mutation of juxtamembrane basic residues in the plasma membrane SNARE syntaxin-1 increase inhibition by PI 4,5-P2, suggesting that syntaxin sequesters PI 4,5-P2 to alleviate inhibition. To define an essential rather than inhibitory role for PI 4,5-P2, we test a PI 4,5-P2–binding priming factor required for vesicle exocytosis. Ca2+-dependent activator protein for secretion promotes increased rates of SNARE-dependent fusion that are PI 4,5-P2 dependent. These results indicate that PI 4,5-P2 regulates fusion both as a fusion restraint that syntaxin-1 alleviates and as an essential cofactor that recruits protein priming factors to facilitate SNARE-dependent fusion.
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Affiliation(s)
- Declan J James
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
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How lipid flippases can modulate membrane structure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1591-600. [DOI: 10.1016/j.bbamem.2008.03.007] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 03/09/2008] [Accepted: 03/12/2008] [Indexed: 11/23/2022]
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Bizzaro N, Piazza I, Baldo G, Baritussio A. Alcohol induced burr cell (echinocytic) haemolytic anaemia and haemochromatosis. CLINICAL AND LABORATORY HAEMATOLOGY 2008; 15:93-102. [PMID: 8348781 DOI: 10.1111/j.1365-2257.1993.tb00132.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A 51-year-old man with chronic alcoholic liver disease developed a severe haemolytic anaemia characterized by the presence of circulating burr-shaped cells (echinocytes). Several transfusions of packed red cells were ineffective in raising the haemoglobin concentration, showing that the abnormality was acquired by the transfused cells. Liver biopsies revealed haemochromatosis. Haematological parameters normalized four months after the patient stopped drinking alcohol, but burr cells were still present and erythrocyte life-span was still markedly shortened at one year follow-up. Since serum cholesterol, HDL-cholesterol, and Apo-AI and Apo-B lipoproteins were considerably decreased, the lipid composition of the red cell membrane was studied. Findings showed that echinocytosis occurred with no change in membrane cholesterol content, nor in cholesterol:phospholipid ratio, but with an alteration in the phosphatidylserine and phosphatidylinositol concentrations. While haemochromatosis was most likely the cause of the erythrocyte anomaly, alcohol intake was probably responsible for the acute onset of haemolytic anaemia with effects directly on the erythrocyte membrane as well as mediated by the progressive hepatic injury, with alterations in the plasma and successively in the intramembrane lipid composition.
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Affiliation(s)
- N Bizzaro
- Laboratorio di Patologia Clinica, Ospedale Civile, Venice, Italy
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