1
|
Kundu R, Kumar S, Chandra A, Datta A. Cell-Permeable Fluorescent Sensors Enable Rapid Live Cell Visualization of Plasma Membrane and Nuclear PIP3 Pools. JACS AU 2024; 4:1004-1017. [PMID: 38559732 PMCID: PMC10976597 DOI: 10.1021/jacsau.3c00738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 02/16/2024] [Accepted: 02/20/2024] [Indexed: 04/04/2024]
Abstract
Phosphoinositides, phospholipids that are key cell-signal mediators, are present at very low levels in cellular membranes and within nuclei. Phosphatidylinositol-(3,4,5)-trisphosphate (PIP3), a phosphoinositide barely present in resting cell membranes, is produced when cells receive either growth, proliferation, or movement signals. Aberrant PIP3 levels are associated with the formation of cancers. PIP3 pools are also present in the nucleus, specifically in the nucleolus. However, questions related to the organization and function of this lipid in such membraneless intranuclear structures remain unanswered. Therefore, chemical sensors for tracking cellular PIP3 are invaluable not only for timing signal initiation in membranes but also for identifying the organization and function of membraneless nuclear PIP3 pools. Because PIP3 is present in the inner leaflet of cell membranes and in the nucleus, cell-permeable, rapid-response fluorescent sensors would be ideal. We have designed two peptide-based, water-soluble, cell-permeable, ratiometric PIP3 sensors named as MFR-K17H and DAN-NG-H12G. MFR-K17H rapidly entered into the cell cytoplasm, distinctly reporting rapid (<1 min) time scales of growth factor-stimulated PIP3 generation and depletion within cell membranes in living cells. Importantly, MFR-K17H lighted up inherently high levels of PIP3 in triple-negative breast cancer cell membranes, implying future applications in the detection of enhanced PIP3 levels in cancerous cells. On the other hand, DAN-NG-H12G targeted intranuclear PIP3 pools, revealing that within membraneless structures, PIP3 resided in a hydrophobic environment. Together, both probes form a unique orthogonally targeted combination of cell-permeable, ratiometric probes that, unlike previous cell-impermeable protein-based sensors, are easy to apply and provide an unprecedented handle into PIP3-mediated cellular processes.
Collapse
Affiliation(s)
- Rajasree Kundu
- Department of Chemical Sciences, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India
| | - Sahil Kumar
- Department of Chemical Sciences, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India
| | - Amitava Chandra
- Department of Chemical Sciences, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India
| | - Ankona Datta
- Department of Chemical Sciences, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India
| |
Collapse
|
2
|
Paul A, Shukla D. Oligomerization of Monoamine Transporters. Subcell Biochem 2024; 104:119-137. [PMID: 38963486 DOI: 10.1007/978-3-031-58843-3_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
Transporters of the monoamine transporter (MAT) family regulate the uptake of important neurotransmitters like dopamine, serotonin, and norepinephrine. The MAT family functions using the electrochemical gradient of ions across the membrane and comprises three transporters, dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET). MAT transporters have been observed to exist in monomeric states to higher-order oligomeric states. Structural features, allosteric modulation, and lipid environment regulate the oligomerization of MAT transporters. NET and SERT oligomerization are regulated by levels of PIP2 present in the membrane. The kink present in TM12 in the MAT family is crucial for dimer interface formation. Allosteric modulation in the dimer interface hinders dimer formation. Oligomerization also influences the transporters' function, trafficking, and regulation. This chapter will focus on recent studies on monoamine transporters and discuss the factors affecting their oligomerization and its impact on their function.
Collapse
Affiliation(s)
- Arnav Paul
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Diwakar Shukla
- Department of Chemical and Biomolecular Engineering, Department of Bioengineering, Center for Biophysics and Quantitative Biology, Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
| |
Collapse
|
3
|
Rosenhouse-Dantsker A, Gazgalis D, Logothetis DE. PI(4,5)P 2 and Cholesterol: Synthesis, Regulation, and Functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:3-59. [PMID: 36988876 DOI: 10.1007/978-3-031-21547-6_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is the most abundant membrane phosphoinositide and cholesterol is an essential component of the plasma membrane (PM). Both lipids play key roles in a variety of cellular functions including as signaling molecules and major regulators of protein function. This chapter provides an overview of these two important lipids. Starting from a brief description of their structure, synthesis, and regulation, the chapter continues to describe the primary functions and signaling processes in which PI(4,5)P2 and cholesterol are involved. While PI(4,5)P2 and cholesterol can act independently, they often act in concert or affect each other's impact. The chapters in this volume on "Cholesterol and PI(4,5)P2 in Vital Biological Functions: From Coexistence to Crosstalk" focus on the emerging relationship between cholesterol and PI(4,5)P2 in a variety of biological systems and processes. In this chapter, the next section provides examples from the ion channel field demonstrating that PI(4,5)P2 and cholesterol can act via common mechanisms. The chapter ends with a discussion of future directions.
Collapse
Affiliation(s)
| | - Dimitris Gazgalis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
| | - Diomedes E Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
| |
Collapse
|
4
|
Maltan L, Andova AM, Derler I. The Role of Lipids in CRAC Channel Function. Biomolecules 2022; 12:biom12030352. [PMID: 35327543 PMCID: PMC8944985 DOI: 10.3390/biom12030352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/12/2022] [Accepted: 02/20/2022] [Indexed: 11/28/2022] Open
Abstract
The composition and dynamics of the lipid membrane define the physical properties of the bilayer and consequently affect the function of the incorporated membrane transporters, which also applies for the prominent Ca2+ release-activated Ca2+ ion channel (CRAC). This channel is activated by receptor-induced Ca2+ store depletion of the endoplasmic reticulum (ER) and consists of two transmembrane proteins, STIM1 and Orai1. STIM1 is anchored in the ER membrane and senses changes in the ER luminal Ca2+ concentration. Orai1 is the Ca2+-selective, pore-forming CRAC channel component located in the plasma membrane (PM). Ca2+ store-depletion of the ER triggers activation of STIM1 proteins, which subsequently leads to a conformational change and oligomerization of STIM1 and its coupling to as well as activation of Orai1 channels at the ER-PM contact sites. Although STIM1 and Orai1 are sufficient for CRAC channel activation, their efficient activation and deactivation is fine-tuned by a variety of lipids and lipid- and/or ER-PM junction-dependent accessory proteins. The underlying mechanisms for lipid-mediated CRAC channel modulation as well as the still open questions, are presented in this review.
Collapse
|
5
|
Kundu R, Chandra A, Datta A. Fluorescent Chemical Tools for Tracking Anionic Phospholipids. Isr J Chem 2021. [DOI: 10.1002/ijch.202100003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Rajasree Kundu
- Department of Chemical Sciences Tata Institute of Fundamental Research 1 Homi Bhabha Road, Colaba Mumbai 400005 India
| | - Amitava Chandra
- Department of Chemical Sciences Tata Institute of Fundamental Research 1 Homi Bhabha Road, Colaba Mumbai 400005 India
| | - Ankona Datta
- Department of Chemical Sciences Tata Institute of Fundamental Research 1 Homi Bhabha Road, Colaba Mumbai 400005 India
| |
Collapse
|
6
|
Ernest James Phillips T, Maguire E. Phosphoinositides: Roles in the Development of Microglial-Mediated Neuroinflammation and Neurodegeneration. Front Cell Neurosci 2021; 15:652593. [PMID: 33841102 PMCID: PMC8032904 DOI: 10.3389/fncel.2021.652593] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 03/08/2021] [Indexed: 12/11/2022] Open
Abstract
Microglia are increasingly recognized as vital players in the pathology of a variety of neurodegenerative conditions including Alzheimer’s (AD) and Parkinson’s (PD) disease. While microglia have a protective role in the brain, their dysfunction can lead to neuroinflammation and contributes to disease progression. Also, a growing body of literature highlights the seven phosphoinositides, or PIPs, as key players in the regulation of microglial-mediated neuroinflammation. These small signaling lipids are phosphorylated derivates of phosphatidylinositol, are enriched in the brain, and have well-established roles in both homeostasis and disease.Disrupted PIP levels and signaling has been detected in a variety of dementias. Moreover, many known AD disease modifiers identified via genetic studies are expressed in microglia and are involved in phospholipid metabolism. One of these, the enzyme PLCγ2 that hydrolyzes the PIP species PI(4,5)P2, displays altered expression in AD and PD and is currently being investigated as a potential therapeutic target.Perhaps unsurprisingly, neurodegenerative conditions exhibiting PIP dyshomeostasis also tend to show alterations in aspects of microglial function regulated by these lipids. In particular, phosphoinositides regulate the activities of proteins and enzymes required for endocytosis, toll-like receptor signaling, purinergic signaling, chemotaxis, and migration, all of which are affected in a variety of neurodegenerative conditions. These functions are crucial to allow microglia to adequately survey the brain and respond appropriately to invading pathogens and other abnormalities, including misfolded proteins. AD and PD therapies are being developed to target many of the above pathways, and although not yet investigated, simultaneous PIP manipulation might enhance the beneficial effects observed. Currently, only limited therapeutics are available for dementia, and although these show some benefits for symptom severity and progression, they are far from curative. Given the importance of microglia and PIPs in dementia development, this review summarizes current research and asks whether we can exploit this information to design more targeted, or perhaps combined, dementia therapeutics. More work is needed to fully characterize the pathways discussed in this review, but given the strength of the current literature, insights in this area could be invaluable for the future of neurodegenerative disease research.
Collapse
Affiliation(s)
| | - Emily Maguire
- UK Dementia Research Institute at Cardiff University, Cardiff, United Kingdom
| |
Collapse
|
7
|
Review of PIP2 in Cellular Signaling, Functions and Diseases. Int J Mol Sci 2020; 21:ijms21218342. [PMID: 33172190 PMCID: PMC7664428 DOI: 10.3390/ijms21218342] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 12/27/2022] Open
Abstract
Phosphoinositides play a crucial role in regulating many cellular functions, such as actin dynamics, signaling, intracellular trafficking, membrane dynamics, and cell-matrix adhesion. Central to this process is phosphatidylinositol bisphosphate (PIP2). The levels of PIP2 in the membrane are rapidly altered by the activity of phosphoinositide-directed kinases and phosphatases, and it binds to dozens of different intracellular proteins. Despite the vast literature dedicated to understanding the regulation of PIP2 in cells over past 30 years, much remains to be learned about its cellular functions. In this review, we focus on past and recent exciting results on different molecular mechanisms that regulate cellular functions by binding of specific proteins to PIP2 or by stabilizing phosphoinositide pools in different cellular compartments. Moreover, this review summarizes recent findings that implicate dysregulation of PIP2 in many diseases.
Collapse
|
8
|
Abstract
Gelsolin (GSN), one of the most abundant actin-binding proteins, is involved in cell motility, shape and metabolism. As a member of the GSN superfamily, GSN is a highly structured protein in eukaryotic cells that can be regulated by calcium concentration, intracellular pH, temperature and phosphatidylinositol-4,5-bisphosphate. GSN plays an important role in cellular mechanisms as well as in different cellular interactions. Because of its participation in immunologic processes and its interaction with different cells of the immune system, GSN is a potential candidate for various therapeutic applications. In this review, we summarise the structure of GSN as well as its regulating and functional roles, focusing on distinct diseases such as Alzheimer's disease, rheumatoid arthritis and cancer. A short overview of GSN as a therapeutic target in today's medicine is also provided.
Collapse
|
9
|
Szatmári D, Xue B, Kannan B, Burtnick LD, Bugyi B, Nyitrai M, Robinson RC. ATP competes with PIP2 for binding to gelsolin. PLoS One 2018; 13:e0201826. [PMID: 30086165 PMCID: PMC6080781 DOI: 10.1371/journal.pone.0201826] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 07/23/2018] [Indexed: 01/08/2023] Open
Abstract
Gelsolin is a severing and capping protein that targets filamentous actin and regulates filament lengths near plasma membranes, contributing to cell movement and plasma membrane morphology. Gelsolin binds to the plasma membrane via phosphatidylinositol 4,5-bisphosphate (PIP2) in a state that cannot cap F-actin, and gelsolin-capped actin filaments are uncapped by PIP2 leading to filament elongation. The process by which gelsolin is removed from PIP2 at the plasma membrane is currently unknown. Gelsolin also binds ATP with unknown function. Here we characterize the role of ATP on PIP2-gelsolin complex dynamics. Fluorophore-labeled PIP2 and ATP were used to study their interactions with gelsolin using steady-state fluorescence anisotropy, and Alexa488-labeled gelsolin was utilized to reconstitute the regulation of gelsolin binding to PIP2-containing phospholipid vesicles by ATP. Under physiological salt conditions ATP competes with PIP2 for binding to gelsolin, while calcium causes the release of ATP from gelsolin. These data suggest a cycle for gelsolin activity. Firstly, calcium activates ATP-bound gelsolin allowing it to sever and cap F-actin. Secondly, PIP2-binding removes the gelsolin cap from F-actin at low calcium levels, leading to filament elongation. Finally, ATP competes with PIP2 to release the calcium-free ATP-bound gelsolin, allowing it to undergo a further round of severing.
Collapse
Affiliation(s)
- Dávid Szatmári
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
- University of Pécs, Medical School, Department of Biophysics, Pécs, Hungary
| | - Bo Xue
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Balakrishnan Kannan
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
| | - Leslie D. Burtnick
- Department of Chemistry and Centre for Blood Research, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Beáta Bugyi
- University of Pécs, Medical School, Department of Biophysics, Pécs, Hungary
- Szentágothai Research Center, Pécs, Hungary
| | - Miklós Nyitrai
- University of Pécs, Medical School, Department of Biophysics, Pécs, Hungary
- Szentágothai Research Center, Pécs, Hungary
| | - Robert C. Robinson
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, Japan
| |
Collapse
|
10
|
Niemirowicz K, Durnaś B, Piktel E, Bucki R. Development of antifungal therapies using nanomaterials. Nanomedicine (Lond) 2017; 12:1891-1905. [DOI: 10.2217/nnm-2017-0052] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The number and diversity of chemical structures currently available as antibacterial drugs is much higher compared with the number of active substances in relation to pathogenic fungi. In this review we focus on nanotechnology approaches, which offer promising strategies to create nanoagents that possess broad-spectrum antifungal activity and might overcome mechanisms of antibiotic resistance. Special attention was given to magnetic nanoparticles and their ability to restrict fungal growth directly, which depends on surface chemistry and pathogen strains. We speculate that future developments of new antifungal methods will take advantage of the current knowledge of using of magnetic nanomaterials as anticancer agents based on their ability to induce hyperthermia and enhance photosensitizing processes.
Collapse
Affiliation(s)
- Katarzyna Niemirowicz
- Department of Microbiological & Nanobiomedical Engineering, Medical University of Białystok, 15–222 Białystok, Poland
| | - Bonita Durnaś
- Department Microbiology & Immunology, The Faculty of Health Sciences of the Jan Kochanowski University in Kielce, 25–317 Kielce, Poland
| | - Ewelina Piktel
- Department of Microbiological & Nanobiomedical Engineering, Medical University of Białystok, 15–222 Białystok, Poland
| | - Robert Bucki
- Department of Microbiological & Nanobiomedical Engineering, Medical University of Białystok, 15–222 Białystok, Poland
| |
Collapse
|
11
|
Visualizing Temperature Mediated Activation of Gelsolin and Its Deactivation By Pip 2: A Saxs Based Study. Sci Rep 2017; 7:4670. [PMID: 28680082 PMCID: PMC5498565 DOI: 10.1038/s41598-017-04975-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 05/23/2017] [Indexed: 11/21/2022] Open
Abstract
This is the first report describing temperature based initiation of gelsolin’s F-actin depolymerization activity, even in absence of free Ca2+ or low pH. Small angle X-ray scattering (SAXS) and circular dichroism (CD) studies revealed that temperature in the range of 30–40 °C is capable of opening the G1 domain alone, as remaining domains are held together by the Ca2+-sensitive C-tail latch without any loss in the secondary structural content. Full opening of all domains of tail-less gelsolin, and retention of closed shape for G2–G6 gelsolin merely by heating, further substantiated our findings. The Ca2+/pH independent activity of gelsolin near physiological temperature brought out a query: whether gelsolin is always active, and if not, what might deactivate it? Earlier, PIP2 has been reported to render gelsolin inactive with no structural insight. Reduction in shape parameters and modeling revealed that PIP2 reverses the temperature induced extension of g1-g2 linker leading to a compact shape seen for Ca2+-free gelsolin. Similar results for partially activated gelsolin (by low pH or Ca2+ ions below 0.1 μM) imply that inside cells, depolymerization, capping, and nucleation of F-actin by gelsolin is regulated by the culmination of local Ca2+ ion concentration, pH, temperature and PIP2 levels.
Collapse
|
12
|
Lupak M, Hachkova H, Khokhla M, Chajka Y, Skybitska M, Sybirna N. Leukocyte actin cytoskeleton reorganization and redistribution of sialylated membrane glycoconjugates under experimental diabetes mellitus and against the administration of the Galega officinalis L. extract. CYTOL GENET+ 2017. [DOI: 10.3103/s0095452717030070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
13
|
Mondal S, Rakshit A, Pal S, Datta A. Cell Permeable Ratiometric Fluorescent Sensors for Imaging Phosphoinositides. ACS Chem Biol 2016; 11:1834-43. [PMID: 27082310 DOI: 10.1021/acschembio.6b00067] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Phosphoinositides are critical cell-signal mediators present on the plasma membrane. The dynamic change of phosphoinositide concentrations on the membrane including clustering and declustering mediates signal transduction. The importance of phosphoinositides is scored by the fact that they participate in almost all cell-signaling events, and a defect in phosphoinositide metabolism is linked to multiple diseases including cancer, bipolar disorder, and type-2 diabetes. Optical sensors for visualizing phosphoinositide distribution can provide information on phosphoinositide dynamics. This exercise will ultimately afford a handle into understanding and manipulating cell-signaling processes. The major requirement in phosphoinositide sensor development is a selective, cell permeable probe that can quantify phosphoinositides. To address this requirement, we have developed short peptide-based ratiometric fluorescent sensors for imaging phosphoinositides. The sensors afford a selective response toward two crucial signaling phosphoinositides, phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) and phosphatidylinositol-4-phosphate (PI4P), over other anionic membrane phospholipids and soluble inositol phosphates. Dissociation constant values indicate up to 4 times higher probe affinity toward PI(4,5)P2 when compared to PI4P. Significantly, the sensors are readily cell-permeable and enter cells within 15 min of incubation as indicated by multiphoton excitation confocal microscopy. Furthermore, the sensors light up signaling phosphoinositides present both on the cell membrane and on organelle membranes near the perinuclear space, opening avenues for quantifying and monitoring phosphoinositide signaling.
Collapse
Affiliation(s)
- Samsuzzoha Mondal
- Department
of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai-400005, India
| | - Ananya Rakshit
- Department
of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai-400005, India
| | - Suranjana Pal
- Department
of Biological Sciences, Tata Institute of Fundamental Research, Mumbai-400005, India
| | - Ankona Datta
- Department
of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai-400005, India
| |
Collapse
|
14
|
Choi S, Thapa N, Tan X, Hedman AC, Anderson RA. PIP kinases define PI4,5P₂signaling specificity by association with effectors. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1851:711-23. [PMID: 25617736 PMCID: PMC4380618 DOI: 10.1016/j.bbalip.2015.01.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 01/14/2015] [Accepted: 01/16/2015] [Indexed: 12/21/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI4,5P₂) is an essential lipid messenger with roles in all eukaryotes and most aspects of human physiology. By controlling the targeting and activity of its effectors, PI4,5P₂modulates processes, such as cell migration, vesicular trafficking, cellular morphogenesis, signaling and gene expression. In cells, PI4,5P₂has a much higher concentration than other phosphoinositide species and its total content is largely unchanged in response to extracellular stimuli. The discovery of a vast array of PI4,5P₂ binding proteins is consistent with data showing that the majority of cellular PI4,5P₂is sequestered. This supports a mechanism where PI4,5P₂functions as a localized and highly specific messenger. Further support of this mechanism comes from the de novo synthesis of PI4,5P₂which is often linked with PIP kinase interaction with PI4,5P₂effectors and is a mechanism to define specificity of PI4,5P₂signaling. The association of PI4,5P₂-generating enzymes with PI4,5P₂effectors regulate effector function both temporally and spatially in cells. In this review, the PI4,5P₂effectors whose functions are tightly regulated by associations with PI4,5P₂-generating enzymes will be discussed. This article is part of a Special Issue entitled Phosphoinositides.
Collapse
Affiliation(s)
- Suyong Choi
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Narendra Thapa
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Xiaojun Tan
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Andrew C Hedman
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Richard A Anderson
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA; Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA.
| |
Collapse
|
15
|
Stanishneva-Konovalova T, Sokolova O. Molecular dynamics simulations of negatively charged DPPC/DPPI lipid bilayers at two levels of resolution. COMPUT THEOR CHEM 2015. [DOI: 10.1016/j.comptc.2014.04.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
16
|
Wu CY, Lin MW, Wu DC, Huang YB, Huang HT, Chen CL. The role of phosphoinositide-regulated actin reorganization in chemotaxis and cell migration. Br J Pharmacol 2014; 171:5541-54. [PMID: 25420930 DOI: 10.1111/bph.12777] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 04/15/2014] [Accepted: 05/07/2014] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Reorganization of the actin cytoskeleton is essential for cell motility and chemotaxis. Actin-binding proteins (ABPs) and membrane lipids, especially phosphoinositides PI(4,5)P2 and PI(3,4,5)P3 are involved in the regulation of this reorganization. At least 15 ABPs have been reported to interact with, or regulated by phosphoinositides (PIPs) whose synthesis is regulated by extracellular signals. Recent studies have uncovered several parallel intracellular signalling pathways that crosstalk in chemotaxing cells. Here, we review the roles of ABPs and phosphoinositides in chemotaxis and cell migration. LINKED ARTICLES This article is part of a themed section on Cytoskeleton, Extracellular Matrix, Cell Migration, Wound Healing and Related Topics. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-24.
Collapse
Affiliation(s)
- C-Y Wu
- Department of Biological Science, National Sun Yat-sen University, Kaohsiung, Taiwan; Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, Kaohsiung, Taiwan
| | | | | | | | | | | |
Collapse
|
17
|
Slochower DR, Wang YH, Tourdot RW, Radhakrishnan R, Janmey PA. Counterion-mediated pattern formation in membranes containing anionic lipids. Adv Colloid Interface Sci 2014; 208:177-88. [PMID: 24556233 DOI: 10.1016/j.cis.2014.01.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/21/2014] [Accepted: 01/22/2014] [Indexed: 01/05/2023]
Abstract
Most lipid components of cell membranes are either neutral, like cholesterol, or zwitterionic, like phosphatidylcholine and sphingomyelin. Very few lipids, such as sphingosine, are cationic at physiological pH. These generally interact only transiently with the lipid bilayer, and their synthetic analogs are often designed to destabilize the membrane for drug or DNA delivery. However, anionic lipids are common in both eukaryotic and prokaryotic cell membranes. The net charge per anionic phospholipid ranges from -1 for the most abundant anionic lipids such as phosphatidylserine, to near -7 for phosphatidylinositol 3,4,5 trisphosphate, although the effective charge depends on many environmental factors. Anionic phospholipids and other negatively charged lipids such as lipopolysaccharides are not randomly distributed in the lipid bilayer, but are highly restricted to specific leaflets of the bilayer and to regions near transmembrane proteins or other organized structures within the plane of the membrane. This review highlights some recent evidence that counterions, in the form of monovalent or divalent metal ions, polyamines, or cationic protein domains, have a large influence on the lateral distribution of anionic lipids within the membrane, and that lateral demixing of anionic lipids has effects on membrane curvature and protein function that are important for biological control.
Collapse
Affiliation(s)
- David R Slochower
- Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yu-Hsiu Wang
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Richard W Tourdot
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ravi Radhakrishnan
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paul A Janmey
- Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Departments of Physiology and Physics, University of Pennsylvania, Philadelphia, PA 19104, USA
| |
Collapse
|
18
|
Counterion-mediated cluster formation by polyphosphoinositides. Chem Phys Lipids 2014; 182:38-51. [PMID: 24440472 DOI: 10.1016/j.chemphyslip.2014.01.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 12/11/2013] [Accepted: 01/06/2014] [Indexed: 02/06/2023]
Abstract
Polyphosphoinositides (PPI) and in particular PI(4,5)P2, are among the most highly charged molecules in cell membranes, are important in many cellular signaling pathways, and are frequently targeted by peripheral polybasic proteins for anchoring through electrostatic interactions. Such interactions between PIP2 and proteins containing polybasic stretches depend on the physical state and the lateral distribution of PIP2 within the inner leaflet of the cell's lipid bilayer. The physical and chemical properties of PIP2 such as pH-dependent changes in headgroup ionization and area per molecule as determined by experiments together with molecular simulations that predict headgroup conformations at various ionization states have revealed the electrostatic properties and phase behavior of PIP2-containing membranes. This review focuses on recent experimental and computational developments in defining the physical chemistry of PIP2 and its interactions with counterions. Ca(2+)-induced changes in PIP2 charge, conformation, and lateral structure within the membrane are documented by numerous experimental and computational studies. A simplified electrostatic model successfully predicts the Ca(2+)-driven formation of PIP2 clusters but cannot account for the different effects of Ca(2+) and Mg(2+) on PIP2-containing membranes. A more recent computational study is able to see the difference between Ca(2+) and Mg(2+) binding to PIP2 in the absence of a membrane and without cluster formation. Spectroscopic studies suggest that divalent cation- and multivalent polyamine-induced changes in the PIP2 lateral distribution in model membrane are also different, and not simply related to the net charge of the counterion. Among these differences is the capacity of Ca(2+) but not other polycations to induce nm scale clusters of PIP2 in fluid membranes. Recent super resolution optical studies show that PIP2 forms nanoclusters in the inner leaflet of a plasma membrane with a similar size distribution as those induced by Ca(2+) in model membranes. The mechanisms by which PIP2 forms nanoclusters and other structures inside a cell remain to be determined, but the unique electrostatic properties of PIP2 and its interactions with multivalent counterions might have particular physiological relevance.
Collapse
|
19
|
Braunger JA, Kramer C, Morick D, Steinem C. Solid supported membranes doped with PIP2: influence of ionic strength and pH on bilayer formation and membrane organization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:14204-13. [PMID: 24199623 DOI: 10.1021/la402646k] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Phosphoinositides and in particular L-α-phosphatidylinositol-4,5-bisphosphate (PIP2) are key lipids controlling many cellular events and serve as receptors for a large number of intracellular proteins. To quantitatively analyze protein-PIP2 interactions in vitro in a time-resolved manner, planar membranes on solid substrates are highly desirable. Here, we describe an optimized protocol to form PIP2 containing planar solid supported membranes on silicon surfaces by vesicle spreading. Supported lipid bilayers (SLBs) were obtained by spreading POPC/PIP2 (92:8) small unilamellar vesicles onto hydrophilic silicon substrates at a low pH of 4.8. These membranes were capable of binding ezrin, resulting in large protein coverage as concluded from reflectometric interference spectroscopy and fluorescence microscopy. As deduced from fluorescence microscopy, only under low pH conditions, a homogeneously appearing distribution of fluorescently labeled PIP2 molecules in the membrane was achieved. Fluorescence recovery after photobleaching experiments revealed that PIP2 is not mobile in the bottom layer of the SLBs, while PIP2 is fully mobile in the top layer with diffusion coefficients of about 3 μm(2)/s. This diffusion coefficient was considerably reduced by a factor of about 3 if ezrin has been bound to PIP2 in the membrane.
Collapse
Affiliation(s)
- Julia A Braunger
- Institut für Organische und Biomolekulare Chemie, Georg-August Universität , Tammannstr. 2, 37077 Göttingen, Germany
| | | | | | | |
Collapse
|
20
|
Nag S, Larsson M, Robinson RC, Burtnick LD. Gelsolin: The tail of a molecular gymnast. Cytoskeleton (Hoboken) 2013; 70:360-84. [DOI: 10.1002/cm.21117] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 05/24/2013] [Indexed: 12/14/2022]
Affiliation(s)
| | - Mårten Larsson
- Institute of Molecular and Cell Biology, A*STAR; Singapore
| | | | - Leslie D. Burtnick
- Department of Chemistry and Centre for Blood Research; Life Sciences Institute, University of British Columbia; Vancouver; British Columbia; Canada
| |
Collapse
|
21
|
Antimicrobial selectivity based on zwitterionic lipids and underlying balance of interactions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2192-201. [DOI: 10.1016/j.bbamem.2012.05.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 04/26/2012] [Accepted: 05/09/2012] [Indexed: 01/03/2023]
|
22
|
Solomon JP, Page LJ, Balch WE, Kelly JW. Gelsolin amyloidosis: genetics, biochemistry, pathology and possible strategies for therapeutic intervention. Crit Rev Biochem Mol Biol 2012; 47:282-96. [PMID: 22360545 DOI: 10.3109/10409238.2012.661401] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Protein misassembly into aggregate structures, including cross-β-sheet amyloid fibrils, is linked to diseases characterized by the degeneration of post-mitotic tissue. While amyloid fibril deposition in the extracellular space certainly disrupts cellular and tissue architecture late in the course of amyloid diseases, strong genetic, pathological and pharmacologic evidence suggests that the process of amyloid fibril formation itself, known as amyloidogenesis, likely causes these maladies. It seems that the formation of oligomeric aggregates during the amyloidogenesis process causes the proteotoxicity and cytotoxicity characteristic of these disorders. Herein, we review what is known about the genetics, biochemistry and pathology of familial amyloidosis of Finnish type (FAF) or gelsolin amyloidosis. Briefly, autosomal dominant D187N or D187Y mutations compromise Ca(2+) binding in domain 2 of gelsolin, allowing domain 2 to sample unfolded conformations. When domain 2 is unfolded, gelsolin is subject to aberrant furin endoproteolysis as it passes through the Golgi on its way to the extracellular space. The resulting C-terminal 68 kDa fragment (C68) is susceptible to extracellular endoproteolytic events, possibly mediated by a matrix metalloprotease, affording 8 and 5 kDa amyloidogenic fragments of gelsolin. These amyloidogenic fragments deposit systemically, causing a variety of symptoms including corneal lattice dystrophy and neurodegeneration. The first murine model of the disease recapitulates the aberrant processing of mutant plasma gelsolin, amyloid deposition, and the degenerative phenotype. We use what we have learned from our biochemical studies, as well as insight from mouse and human pathology to propose therapeutic strategies that may halt the progression of FAF.
Collapse
Affiliation(s)
- James P Solomon
- Departments of Chemistry and Molecular and Experimental Medicine, The Skaggs Institute for Chemical Biology, La Jolla, CA, USA
| | | | | | | |
Collapse
|
23
|
Rosen SAJ, Gaffney PRJ, Spiess B, Gould IR. Understanding the relative affinity and specificity of the pleckstrin homology domain of protein kinase B for inositol phosphates. Phys Chem Chem Phys 2012; 14:929-36. [DOI: 10.1039/c1cp22240f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
24
|
Zhang L, Mao YS, Janmey PA, Yin HL. Phosphatidylinositol 4, 5 bisphosphate and the actin cytoskeleton. Subcell Biochem 2012; 59:177-215. [PMID: 22374091 DOI: 10.1007/978-94-007-3015-1_6] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Dynamic changes in PM PIP(2) have been implicated in the regulation of many processes that are dependent on actin polymerization and remodeling. PIP(2) is synthesized primarily by the type I phosphatidylinositol 4 phosphate 5 kinases (PIP5Ks), and there are three major isoforms, called a, b and g. There is emerging evidence that these PIP5Ks have unique as well as overlapping functions. This review will focus on the isoform-specific roles of individual PIP5K as they relate to the regulation of the actin cytoskeleton. We will review recent advances that establish PIP(2) as a critical regulator of actin polymerization and cytoskeleton/membrane linkages, and show how binding of cytoskeletal proteins to membrane PIP(2) might alter lateral or transverse movement of lipids to affect raft formation or lipid asymmetry. The mechanisms for specifying localized increase in PIP(2) to regulate dynamic actin remodeling will also be discussed.
Collapse
Affiliation(s)
- Li Zhang
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, 75390-9040, Dallas, TX, USA
| | | | | | | |
Collapse
|
25
|
Multiscale simulations suggest a mechanism for integrin inside-out activation. Proc Natl Acad Sci U S A 2011; 108:11890-5. [PMID: 21730166 DOI: 10.1073/pnas.1104505108] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Integrins are large cell-surface adhesion receptors that can be activated to a high affinity state by the formation of an intracellular complex between the integrin β-subunit tail, the membrane, and talin. The F2 and F3 subdomains of the talin head play a key role in formation of this complex. Here, activation of the integrin αIIb/β3 dimer by the talin head domain was probed using multiscale molecular dynamics simulations. A number of novel insights emerge from these studies, including (i) the importance of the integrin αIIb subunit F992 and F993 residues in stabilizing the "off" state of the αIIb/β3 dimer, (ii) a crucial role for negatively charged groups in the F2-F3/membrane interaction, (iii) binding of the talin F2-F3 domain to negatively charged lipid headgroups in the membrane induces a reorientation of the β transmembrane (TM) domain, (iv) an increase in the tilt angle of the β TM domain relative to the bilayer normal helps to destabilize the α/β TM interaction and promote a scissor-like movement of the integrin TM helices. These results, combined with various published experimental observations, suggest a model for the mechanism of inside-out activation of integrins by talin.
Collapse
|
26
|
Hrynets Y, Omana D, Xu Y, Betti M. Impact of citric acid and calcium ions on acid solubilization of mechanically separated turkey meat: Effect on lipid and pigment content. Poult Sci 2011; 90:458-66. [DOI: 10.3382/ps.2010-00859] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
27
|
Rosen SAJ, Gaffney PRJ, Gould IR. A theoretical investigation of inositol 1,3,4,5-tetrakisphosphate. Phys Chem Chem Phys 2011; 13:1070-81. [DOI: 10.1039/c0cp00956c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
|
28
|
Carvalho K, Khalifat N, Maniti O, Nicolas C, Arold S, Picart C, Ramos L. Phosphatidylinositol 4,5-Bisphosphate-Induced Conformational Change of Ezrin and Formation of Ezrin Oligomers. Biochemistry 2010; 49:9318-27. [DOI: 10.1021/bi101141d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Kevin Carvalho
- Laboratoire des Colloïdes, Verres et Nanomatériaux, UMR CNRS-UM2 n°5587, cc26, Université Montpellier 2, Place E. Bataillon, F-34095 Montpellier Cedex 5, France
- Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier 2 et 1, CNRS, Place Eugène Bataillon, F-34095 Montpellier Cedex 5, France
| | - Nada Khalifat
- Laboratoire des Colloïdes, Verres et Nanomatériaux, UMR CNRS-UM2 n°5587, cc26, Université Montpellier 2, Place E. Bataillon, F-34095 Montpellier Cedex 5, France
| | - Ofelia Maniti
- Minatec, Grenoble Institute of Technology and LMGP, 3 parvis Louis Néel, F-38016 Grenoble Cedex, France
| | - Claire Nicolas
- Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier 2 et 1, CNRS, Place Eugène Bataillon, F-34095 Montpellier Cedex 5, France
- Minatec, Grenoble Institute of Technology and LMGP, 3 parvis Louis Néel, F-38016 Grenoble Cedex, France
| | - Stefan Arold
- Centre de Biochimie Structurale, Montpellier, France, and CNRS UMR 5048, INSERM U554, Université Montpellier I et II, F-34090 Montpellier, France
- University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, United States
| | - Catherine Picart
- Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier 2 et 1, CNRS, Place Eugène Bataillon, F-34095 Montpellier Cedex 5, France
- Minatec, Grenoble Institute of Technology and LMGP, 3 parvis Louis Néel, F-38016 Grenoble Cedex, France
| | - Laurence Ramos
- Laboratoire des Colloïdes, Verres et Nanomatériaux, UMR CNRS-UM2 n°5587, cc26, Université Montpellier 2, Place E. Bataillon, F-34095 Montpellier Cedex 5, France
| |
Collapse
|
29
|
Lupyan D, Mezei M, Logothetis DE, Osman R. A molecular dynamics investigation of lipid bilayer perturbation by PIP2. Biophys J 2010; 98:240-7. [PMID: 20338845 DOI: 10.1016/j.bpj.2009.09.063] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 09/24/2009] [Accepted: 09/29/2009] [Indexed: 10/19/2022] Open
Abstract
Phosphoinositides like phosphatidylinositol 4,5-bisphosphate (PIP(2)) are negatively charged lipids that play a pivotal role in membrane trafficking, signal transduction, and protein anchoring. We have designed a force field for the PIP(2) headgroup using quantum mechanical methods and characterized its properties inside a lipid bilayer using molecular dynamics simulations. Macroscopic properties such as area/headgroup, density profiles, and lipid order parameters calculated from these simulations agree well with the experimental values. However, microscopically, the PIP(2) introduces a local perturbation of the lipid bilayer. The average PIP(2) headgroup orientation of 45 degrees relative to the bilayer normal induces a unique, distance-dependent organization of the lipids that surround PIP(2). The headgroups of these lipids preferentially orient closer to the bilayer normal. This perturbation creates a PIP(2) lipid microdomain with the neighboring lipids. We propose that the PIP(2) lipid microdomain enables the PIP(2) to function as a membrane-bound anchoring molecule.
Collapse
Affiliation(s)
- Dmitry Lupyan
- Department of Structural and Chemical Biology, Mount Sinai School of Medicine, New York, New York, USA
| | | | | | | |
Collapse
|
30
|
Kooijman EE, King KE, Gangoda M, Gericke A. Ionization Properties of Phosphatidylinositol Polyphosphates in Mixed Model Membranes. Biochemistry 2009; 48:9360-71. [DOI: 10.1021/bi9008616] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
31
|
Levental I, Janmey PA, Cēbers A. Electrostatic contribution to the surface pressure of charged monolayers containing polyphosphoinositides. Biophys J 2008; 95:1199-205. [PMID: 18441023 PMCID: PMC2479586 DOI: 10.1529/biophysj.107.126615] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 03/12/2008] [Indexed: 11/18/2022] Open
Abstract
Structural and functional studies of lateral heterogeneity in biological membranes have underlined the importance of membrane organization in biological function. Most inquiries have focused on steric determinants of membrane organization, such as headgroup size and acyl-chain saturation. This manuscript reports a combination of theory and experiment that shows significant electrostatic contributions to surface pressures in monolayers of phospholipids where the charge spacing is smaller than the Bjerrum length. For molecules with steric cross sections typical of phospholipids in the cell membrane (approximately 50 A(2)), only polyphosphoinositides achieve this threshold. The most abundant such lipid is phosphatidylinositol bisphosphate, which has between three and four charged groups at physiological conditions. Theory and experiment show that surface pressure increases linearly with phosphatidylinositol bisphosphate net charge and reveal crossing of high and low ionic strength pressure-area isotherms, due to opposing effects of ionic strength in compressed and expanded monolayers. Theory and experiment show that electrostatic effects are negligible for monolayers of univalent lipids, emphasizing the unique importance of electrostatic effects for lateral organization of polyphosphoinositides. Quantitative differences between theory and experiment suggest that attractive interactions between polyphosphoinositides, possibly mediated by hydrogen bonding, can lessen the effect of electrostatic repulsions.
Collapse
Affiliation(s)
- I Levental
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | |
Collapse
|
32
|
Manna D, Bhardwaj N, Vora MS, Stahelin RV, Lu H, Cho W. Differential roles of phosphatidylserine, PtdIns(4,5)P2, and PtdIns(3,4,5)P3 in plasma membrane targeting of C2 domains. Molecular dynamics simulation, membrane binding, and cell translocation studies of the PKCalpha C2 domain. J Biol Chem 2008; 283:26047-58. [PMID: 18621733 DOI: 10.1074/jbc.m802617200] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many cytosolic proteins are recruited to the plasma membrane (PM) during cell signaling and other cellular processes. Recent reports have indicated that phosphatidylserine (PS), phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)), and phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P(3)) that are present in the PM play important roles for their specific PM recruitment. To systematically analyze how these lipids mediate PM targeting of cellular proteins, we performed biophysical, computational, and cell studies of the Ca(2+)-dependent C2 domain of protein kinase Calpha (PKCalpha) that is known to bind PS and phosphoinositides. In vitro membrane binding measurements by surface plasmon resonance analysis show that PKCalpha-C2 nonspecifically binds phosphoinositides, including PtdIns(4,5)P(2) and PtdIns(3,4,5)P(3), but that PS and Ca(2+) binding is prerequisite for productive phosphoinositide binding. PtdIns(4,5)P(2) or PtdIns(3,4,5)P(3) augments the Ca(2+)- and PS-dependent membrane binding of PKCalpha-C2 by slowing its membrane dissociation. Molecular dynamics simulations also support that Ca(2+)-dependent PS binding is essential for membrane interactions of PKCalpha-C2. PtdIns(4,5)P(2) alone cannot drive the membrane attachment of the domain but further stabilizes the Ca(2+)- and PS-dependent membrane binding. When the fluorescence protein-tagged PKCalpha-C2 was expressed in NIH-3T3 cells, mutations of phosphoinositide-binding residues or depletion of PtdIns(4,5)P(2) and/or PtdIns(3,4,5)P(3) from PM did not significantly affect the PM association of the domain but accelerated its dissociation from PM. Also, local synthesis of PtdIns(4,5)P(2) or PtdIns(3,4,5)P(3) at the PM slowed membrane dissociation of PKCalpha-C2. Collectively, these studies show that PtdIns(4,5)P(2) and PtdIns(3,4,5)P(3) augment the Ca(2+)- and PS-dependent membrane binding of PKCalpha-C2 by elongating the membrane residence of the domain but cannot drive the PM recruitment of PKCalpha-C2. These studies also suggest that effective PM recruitment of many cellular proteins may require synergistic actions of PS and phosphoinositides.
Collapse
Affiliation(s)
- Debasis Manna
- Department of Bioengineering, University of Illinois, Chicago, Illinois 60607, USA
| | | | | | | | | | | |
Collapse
|
33
|
Levental I, Cebers A, Janmey PA. Combined electrostatics and hydrogen bonding determine intermolecular interactions between polyphosphoinositides. J Am Chem Soc 2008; 130:9025-30. [PMID: 18572937 DOI: 10.1021/ja800948c] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Membrane lipids are active contributors to cell function as key mediators in signaling pathways controlling cell functions including inflammation, apoptosis, migration, and proliferation. Recent work on multimolecular lipid structures suggests a critical role for lipid organization in regulating the function of both lipids and proteins. Of particular interest in this context are the polyphosphoinositides (PPI's), especially phosphatidylinositol (4,5) bisphosphate (PIP 2). The cellular functions of PIP 2 are numerous but the organization of PIP 2 in the inner leaflet of the plasma membrane, as well as the factors controlling targeting of PIP 2 to specific proteins, remains poorly understood. To analyze the organization of PIP 2 in a simplified planar system, we used Langmuir monolayers to study the effects of subphase conditions on monolayers of purified naturally derived PIP 2 and other anionic or zwitterionic phospholipids. We report a significant molecular area expanding effect of subphase monovalent salts on PIP 2 at biologically relevant surface densities. This effect is shown to be specific to PIP 2 and independent of subphase pH. Chaotropic agents (e.g., salts, trehalose, urea, temperature) that disrupt water structure and the ability of water to mediate intermolecular hydrogen bonding also specifically expanded PIP 2 monolayers. These results suggest a combination of water-mediated hydrogen bonding and headgroup repulsion in determining the organization of PIP 2, and may contribute to an explanation for the unique functionality of PIP 2 compared to other anionic phospholipids.
Collapse
Affiliation(s)
- Ilya Levental
- Institute for Medicine and Engineering, Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | | | |
Collapse
|
34
|
Vareltzis P, Undeland I. Removal of lipids and diarrhetic shellfish poisoning toxins from blue mussels (Mytilus edulis) during acid and alkaline isolation of proteins. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2008; 56:3675-3681. [PMID: 18454548 DOI: 10.1021/jf800224n] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Diarrhetic shellfish poisoning (DSP) toxins pose a serious health risk for consumers of bivalves and other shellfish, as well as a huge economic burden for the bivalve-producing farmers. In this work, the aim was to utilize a solubilization-based protein-isolation method to produce a low-DSP toxin protein isolate from toxic blue mussels that are unsuitable for the whole shellfish market. A homogenate of whole mussel meat was solubilized at low pH (2.8) or high pH (11.1), followed by centrifugation and reprecipitation of the solubilized mussel proteins at the isoelectric pH. In a second centrifugation, precipitated proteins were collected. These processes resulted in 81 (acid solubilization) and 72% (alkaline solubilization) reduction in the initial DTX-1 toxin content of the mussel meat. No other DSP toxins were found in the protein isolates. Acid processing of mussel meat resulted in 50% reduction in the total lipid content, while alkaline treatment did not significantly affect the lipid content. The effect of citric acid and calcium chloride addition to the mussel meat-water homogenate on lipid and toxin content was also investigated. A poor correlation factor was surprisingly obtained between reductions in DTX-1 toxin and lipids in protein isolates from processed toxic mussels. Results from an analytical mass balance of the DTX-1 toxin during acid processing showed that 61% of this toxin ended up in the aqueous supernatant after the second centrifugation. The present study presents a promising alternative way of utilizing mussels for food production in periods when they are toxic.
Collapse
Affiliation(s)
- Patroklos Vareltzis
- Department of Chemical and Biological Engineering, Food Science, Chalmers University of Technology, SE 402 29, Gothenburg, Sweden.
| | | |
Collapse
|
35
|
Vareltzis P, Hultin HO, Autio WR. Hemoglobin-mediated lipid oxidation of protein isolates obtained from cod and haddock white muscle as affected by citric acid, calcium chloride and pH. Food Chem 2008. [DOI: 10.1016/j.foodchem.2007.10.043] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
36
|
Psachoulia E, Sansom MSP. Interactions of the pleckstrin homology domain with phosphatidylinositol phosphate and membranes: characterization via molecular dynamics simulations. Biochemistry 2008; 47:4211-20. [PMID: 18341295 DOI: 10.1021/bi702319k] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanism of interaction of pleckstrin homology (PH) domains with phosphatidylinositol 4,5-bisphosphate (PIP 2)-containing lipid bilayers remains uncertain. While crystallographic studies have emphasized PH-inositol 1,4,5-trisphosphate (IP 3) interactions, biophysical studies indicate a degree of less specific protein-bilayer interactions. We have used molecular dynamics simulations to characterize the interactions of the PH domain from phospholipase C-delta1 with IP 3 and with PIP 2, the latter in lipid bilayers and in detergent micelles. Simulations of the PH domain in water reveal a reduction in protein flexibility when IP 3 is bound. Simulations of the PH domain bound to PIP 2 in lipid bilayers indicate a tightening of ligand-protein interactions relative to the PH-IP 3 complex, alongside formation of H-bonds between PH side chains and lipid (PC) headgroups, and a degree of penetration of hydrophobic side chains into the core of the bilayer. Comparison with simulations of the PH-bound domain to a PC bilayer in the absence of PIP 2 suggests that the presence of PIP 2 increases the extent of PH-membrane interactions. Thus, comparative molecular dynamics simulations reveal how a PI-binding domain undergoes changes in conformational dynamics on binding to a PIP 2-containing membrane and how interactions additional to those with the PI headgroup are formed.
Collapse
Affiliation(s)
- Emi Psachoulia
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | | |
Collapse
|
37
|
Lorenz CD, Faraudo J, Travesset A. Hydrogen bonding and binding of polybasic residues with negatively charged mixed lipid monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:1654-1658. [PMID: 18211111 DOI: 10.1021/la703550t] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Phosphoinositides, phosphorylated products of phosphatidylinositol, are a family of phospholipids present in tiny amounts (1% or less) in the cytosolic surface of cell membranes, yet they play an astonishingly rich regulatory role, particularly in signaling processes. In this letter, we use molecular dynamics simulations on a model system of mixed lipid monolayers to investigate the interaction of phosphatidylinositol 4,5-bisphosphate (PIP2), the most common of the phosphoinositides, with a polybasic peptide consisting of 13 lysines. Our results show that the polybasic peptide sequesters three PIP2 molecules, forming a complex stabilized by the formation of multiple hydrogen bonds between PIP2 and the Lys residues. We also show that the polybasic peptide does not sequester other charged phospholipids such as phosphatidylserine because of the inability to form long-lived stable hydrogen bonds.
Collapse
Affiliation(s)
- Christian D Lorenz
- Engineering Division, King's College, London Strand, London WC2R 2LS, U.K
| | | | | |
Collapse
|
38
|
Abstract
In the context of molecular dynamics simulations of proteins, the term "force field" refers to the combination of a mathematical formula and associated parameters that are used to describe the energy of the protein as a function of its atomic coordinates. In this review, we describe the functional forms and parameterization protocols of the widely used biomolecular force fields Amber, CHARMM, GROMOS, and OPLS-AA. We also summarize the ability of various readily available noncommercial molecular dynamics packages to perform simulations using these force fields, as well as to use modern methods for the generation of constant-temperature, constant-pressure ensembles and to treat long-range interactions. Finally, we finish with a discussion of the ability of these force fields to support the modeling of proteins in conjunction with nucleic acids, lipids, carbohydrates, and/or small molecules.
Collapse
|
39
|
Vareltzis P, Hultin HO. Effect of low pH on the susceptibility of isolated cod (Gadus morhua) microsomes to lipid oxidation. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2007; 55:9859-9867. [PMID: 17966975 DOI: 10.1021/jf0708600] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
During the extraction of muscle to produce protein isolates by acid or alkali solubilization, membranes are exposed to abnormally low or high pH. Low but not high pH treatment induces rapid oxidation of membrane phospholipids in the presence of hemoglobin. The goal of this research work was to study the oxidative stability of microsomes under the conditions met during acid solubilization. Isolated microsomes from cod muscle were used as a model system. At pH 5.3 or lower, 99% of isolated cod membranes sedimented at low centrifugation speeds. Isolated membranes that were exposed to pH 3.0 were less susceptible to hemoglobin-mediated lipid oxidation. Cod hemoglobin exposed to pH 3 was rendered less pro-oxidative than the untreated cod hemoglobin. However, when microsomes and hemoglobin were together exposed to low pH, oxidation was promoted. Citric acid and calcium chloride, as well as press juice isolated from cod muscle, were able to inhibit lipid oxidation of microsomal suspensions.
Collapse
Affiliation(s)
- Patroklos Vareltzis
- Department of Food Science, University of Massachusetts/Amherst, Gloucester, 01930, USA
| | | |
Collapse
|
40
|
Smith J, Diez G, Klemm AH, Schewkunow V, Goldmann WH. CapZ-lipid membrane interactions: a computer analysis. Theor Biol Med Model 2006; 3:30. [PMID: 16914033 PMCID: PMC1564000 DOI: 10.1186/1742-4682-3-30] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2006] [Accepted: 08/16/2006] [Indexed: 12/03/2022] Open
Abstract
Background CapZ is a calcium-insensitive and lipid-dependent actin filament capping protein, the main function of which is to regulate the assembly of the actin cytoskeleton. CapZ is associated with membranes in cells and it is generally assumed that this interaction is mediated by polyphosphoinositides (PPI) particularly PIP2, which has been characterized in vitro. Results We propose that non-PPI lipids also bind CapZ. Data from computer-aided sequence and structure analyses further suggest that CapZ could become partially buried in the lipid bilayer probably under mildly acidic conditions, in a manner that is not only dependent on the presence of PPIs. We show that lipid binding could involve a number of sites that are spread throughout the CapZ molecule i.e., alpha- and beta-subunits. However, a beta-subunit segment between residues 134–151 is most likely to be involved in interacting with and inserting into lipid membrane due to a slighly higher ratio of positively to negatively charged residues and also due to the presence of a small hydrophobic helix. Conclusion CapZ may therefore play an essential role in providing a stable membrane anchor for actin filaments.
Collapse
Affiliation(s)
- James Smith
- Friedrich-Alexander-University of Erlangen-Nuremberg Center for Medical Physics and Technology, Biophysics Group Henkestrasse 91, 91052 Erlangen, Germany
| | - Gerold Diez
- Friedrich-Alexander-University of Erlangen-Nuremberg Center for Medical Physics and Technology, Biophysics Group Henkestrasse 91, 91052 Erlangen, Germany
| | - Anna H Klemm
- Friedrich-Alexander-University of Erlangen-Nuremberg Center for Medical Physics and Technology, Biophysics Group Henkestrasse 91, 91052 Erlangen, Germany
| | - Vitali Schewkunow
- Friedrich-Alexander-University of Erlangen-Nuremberg Center for Medical Physics and Technology, Biophysics Group Henkestrasse 91, 91052 Erlangen, Germany
| | - Wolfgang H Goldmann
- Friedrich-Alexander-University of Erlangen-Nuremberg Center for Medical Physics and Technology, Biophysics Group Henkestrasse 91, 91052 Erlangen, Germany
| |
Collapse
|
41
|
Abstract
Phosphoinositide phosphates (PIPs) correspond to phosphorylated derivatives of phosphatidylinositol (PI). Despite their relatively low abundance in the plasma membrane, PIPs play a crucial role as precursors of second messengers and are themselves important signaling and targeting molecules. Indeed, modulation of levels of PIPs affects, for example, cortical actin organization, membrane dynamics, and cell migration. The focus of this review is on selected interesting targets of PIPs. Those proteins that bind PIPs and are involved in regulation of actin assembly, actin membrane linkage, and actin contractility are discussed, as well as those that are involved in signaling, such as small GTPases, protein kinases, and phosphatases, or in regulation of membrane dynamics.
Collapse
Affiliation(s)
- Verena Niggli
- Department of Pathology, University of Bern, CH-3010 Bern, Switzerland.
| |
Collapse
|
42
|
Méré J, Chahinian A, Maciver S, Fattoum A, Bettache N, Benyamin Y, Roustan C. Gelsolin binds to polyphosphoinositide-free lipid vesicles and simultaneously to actin microfilaments. Biochem J 2005; 386:47-56. [PMID: 15527423 PMCID: PMC1134765 DOI: 10.1042/bj20041054] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Gelsolin is a calcium-, pH- and lipid-dependent actin filament severing/capping protein whose main function is to regulate the assembly state of the actin cytoskeleton. Gelsolin is associated with membranes in cells, and it is generally assumed that this interaction is mediated by PPIs (polyphosphoinositides), since an interaction with these lipids has been characterized in vitro. We demonstrate that non-PPI lipids also bind gelsolin, especially at low pH. The data suggest further that gelsolin becomes partially buried in the lipid bilayer under mildly acidic conditions, in a manner that is not dependent of the presence of PPIs. Our data also suggest that lipid binding involves a number of sites that are spread throughout the gelsolin molecule. Linker regions between gelsolin domains have been implicated by other work, notably the linker between G1 and G2 (gelsolin domains 1 and 2 respectively), and we postulate that the linker region between the N-terminal and C-terminal halves of gelsolin (between G3 and G4) is also involved in the interaction with lipids. This region is compatible with other studies in which additional binding sites have been located within G4-6. The lipid-gelsolin interactions reported in the present paper are not calcium-dependent, and are likely to involve significant conformational changes to the gelsolin molecule, as the chymotryptic digest pattern is altered by the presence of lipids under our conditions. We also report that vesicle-bound gelsolin is capable of binding to actin filaments, presumably through barbed end capping. Gelsolin bound to vesicles can nucleate actin assembly, but is less active in severing microfilaments.
Collapse
Affiliation(s)
- Jocelyn Méré
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Anne Chahinian
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Sutherland K. Maciver
- †School of Biomedical and Clinical Laboratory Sciences, Division of Biomedical Sciences, College of Medicine, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, Scotland, U.K
| | - Abdellatif Fattoum
- ‡Centre de Recherches de Biochimie Macromoléculaire, FRE 2593 (CNRS), 1919 rte de Mende, 34293 Montpellier Cedex 5, France
| | - Nadir Bettache
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Yves Benyamin
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Claude Roustan
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
- To whom correspondence should be addressed (email )
| |
Collapse
|
43
|
Liang Y, Hultin HO. Separation of membranes from acid-solubilized fish muscle proteins with the aid of calcium ions and organic acids. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2005; 53:3008-3016. [PMID: 15826052 DOI: 10.1021/jf048458y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Calcium chloride, and to a lesser extent MgCl2, aided in the separation of membranes by centrifugation from cod (Gadus morhua) muscle homogenates solubilized at pH 3 in the presence of citric acid or malic acid but not lactic acid. Adding citric acid and Ca2+ before solubilizing the cod muscle homogenates was needed for the effect. At 1 mM citric acid, 70-80% of the phospholipid and 25-30% of the protein were removed at 10 mM Ca2+. At 8 mM Ca2+, citric acid showed an optimal effect on phospholipid removal at 5 mM with 90% of the phospholipid and 35% of the protein removed. The treatment with citric acid and Ca2+ was also effective in separating the membrane from solubilized herring (Clupea harengus) muscle homogenate. Ca2+ and citric acid might exert their influence by disconnecting linkages between membranes and cytoskeletal proteins.
Collapse
Affiliation(s)
- Yong Liang
- Department of Food Science, Massachusetts Agricultural Experiment Station, University of Massachusetts/Amherst, Marine Station, Gloucester, Massachusetts 01930, USA.
| | | |
Collapse
|
44
|
Redfern DA, Gericke A. pH-dependent domain formation in phosphatidylinositol polyphosphate/phosphatidylcholine mixed vesicles. J Lipid Res 2005; 46:504-15. [PMID: 15604522 DOI: 10.1194/jlr.m400367-jlr200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphatidylinositol polyphosphates (PI-PPs) have been shown to mediate a large variety of physiological processes by attracting proteins to specific cellular sites. Such site-specific signaling requires local accumulation of PI-PPs, and in light of the rich headgroup functionality, it is conceivable that hydrogen bond formation between adjacent headgroups is a contributing factor to the formation of PI-PP-enriched domains. To explore the significance of hydrogen bond formation for the mutual interaction of PI-PPs, this study aims to characterize the pH-dependent phase behavior of phosphatidylcholine/phosphatidylinositol bisphosphate and trisphosphate mixed vesicles by differential scanning calorimetry, infrared transmission spectroscopy, and fluorescence resonance energy transfer measurements. For pH values >7-7.5, the experiments yielded results consistent with dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylinositol polyphosphate gel phase demixing, whereas for moderately acidic conditions, an enhanced mixing was observed. Similarly, this pH-dependent formation of PI-PP-enriched domains was also found for the physiologically important fluid phase. The stability of PI-PP-enriched domains and to some extent the pH dependence of the domain formation was governed by the number as well as the position of the phosphomonoester groups at the inositol ring.
Collapse
Affiliation(s)
- Duane A Redfern
- Chemistry Department, Kent State University, Kent, OH 44242, USA
| | | |
Collapse
|
45
|
Mosevitsky MI. Nerve Ending “Signal” Proteins GAP‐43, MARCKS, and BASP1. INTERNATIONAL REVIEW OF CYTOLOGY 2005; 245:245-325. [PMID: 16125549 DOI: 10.1016/s0074-7696(05)45007-x] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Mechanisms of growth cone pathfinding in the course of neuronal net formation as well as mechanisms of learning and memory have been under intense investigation for the past 20 years, but many aspects of these phenomena remain unresolved and even mysterious. "Signal" proteins accumulated mainly in the axon endings (growth cones and the presynaptic area of synapses) participate in the main brain processes. These proteins are similar in several essential structural and functional properties. The most prominent similarities are N-terminal fatty acylation and the presence of an "effector domain" (ED) that dynamically binds to the plasma membrane, to calmodulin, and to actin fibrils. Reversible phosphorylation of ED by protein kinase C modulates these interactions. However, together with similarities, there are significant differences among the proteins, such as different conditions (Ca2+ contents) for calmodulin binding and different modes of interaction with the actin cytoskeleton. In light of these facts, we consider GAP-43, MARCKS, and BASP1 both separately and in conjunction. Special attention is devoted to a discussion of apparent inconsistencies in results and opinions of different authors concerning specific questions about the structure of proteins and their interactions.
Collapse
Affiliation(s)
- Mark I Mosevitsky
- Division of Molecular and Radiation Biophysics, Petersburg Nuclear Physics Institute, Russian Academy of Sciences, 188300 Gatchina Leningrad District, Russian Federation
| |
Collapse
|
46
|
Abstract
Phosphorylated derivatives of the phospholipid phosphatidylinositol, or phosphoinositides, are implicated in many aspects of cell function. Binding of phosphoinositides that are localized within cell membranes to soluble protein ligands allows spatially selective regulation at the cytoplasm-membrane interface. Recently, studies that relate phosphoinositide production to membrane domains are converging with those that show effects of these lipids on the assembly of cellular actin, and are therefore linking membrane and cytoskeletal structures in new ways.
Collapse
Affiliation(s)
- Paul A Janmey
- Institute for Medicine and Engineering, University of Pennsylvania, 1010 Vagelos Laboratories, 3340 Smith Walk, Philadelphia, Pennsylvania 19104, USA.
| | | |
Collapse
|