1
|
Ricci MMC, Orenberg A, Ohayon L, Gau D, Wills RC, Bae Y, Das T, Koes D, Hammond GRV, Roy P. Actin-binding protein profilin1 is an important determinant of cellular phosphoinositide control. J Biol Chem 2024; 300:105583. [PMID: 38141770 PMCID: PMC10826164 DOI: 10.1016/j.jbc.2023.105583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 12/09/2023] [Accepted: 12/13/2023] [Indexed: 12/25/2023] Open
Abstract
Membrane polyphosphoinositides (PPIs) are lipid-signaling molecules that undergo metabolic turnover and influence a diverse range of cellular functions. PPIs regulate the activity and/or spatial localization of a number of actin-binding proteins (ABPs) through direct interactions; however, it is much less clear whether ABPs could also be an integral part in regulating PPI signaling. In this study, we show that ABP profilin1 (Pfn1) is an important molecular determinant of the cellular content of PI(4,5)P2 (the most abundant PPI in cells). In growth factor (EGF) stimulation setting, Pfn1 depletion does not impact PI(4,5)P2 hydrolysis but enhances plasma membrane (PM) enrichment of PPIs that are produced downstream of activated PI3-kinase, including PI(3,4,5)P3 and PI(3,4)P2, the latter consistent with increased PM recruitment of SH2-containing inositol 5' phosphatase (SHIP2) (a key enzyme for PI(3,4)P2 biosynthesis). Although Pfn1 binds to PPIs in vitro, our data suggest that Pfn1's affinity to PPIs and PM presence in actual cells, if at all, is negligible, suggesting that Pfn1 is unlikely to directly compete with SHIP2 for binding to PM PPIs. Additionally, we provide evidence for Pfn1's interaction with SHIP2 in cells and modulation of this interaction upon EGF stimulation, raising an alternative possibility of Pfn1 binding as a potential restrictive mechanism for PM recruitment of SHIP2. In conclusion, our findings challenge the dogma of Pfn1's binding to PM by PPI interaction, uncover a previously unrecognized role of Pfn1 in PI(4,5)P2 homeostasis and provide a new mechanistic avenue of how an ABP could potentially impact PI3K signaling byproducts in cells through lipid phosphatase control.
Collapse
Affiliation(s)
- Morgan M C Ricci
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Andrew Orenberg
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Lee Ohayon
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - David Gau
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Rachel C Wills
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Yongho Bae
- Department of Pathology and Anatomical Science, University at Buffalo, Buffalo, New York, USA
| | - Tuhin Das
- Tavotek Biotherapeutics, Spring House, Pennsylvania, USA
| | - David Koes
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Gerald R V Hammond
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
| | - Partha Roy
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
| |
Collapse
|
2
|
Sadr AS, Abdollahpour Z, Aliahmadi A, Eslahchi C, Nekouei M, Kiaei L, Kiaei M, Ghassempour A. Detection of structural and conformational changes in ALS-causing mutant profilin-1 with hydrogen/deuterium exchange mass spectrometry and bioinformatics techniques. Metab Brain Dis 2022; 37:229-241. [PMID: 34302583 DOI: 10.1007/s11011-021-00763-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 06/06/2021] [Indexed: 10/20/2022]
Abstract
The hydrogen/deuterium exchange (HDX) is a reliable method to survey the dynamic behavior of proteins and epitope mapping. Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) is a quantifying tool to assay for HDX in the protein of interest. We combined HDX-MALDI-TOF MS and molecular docking/MD simulation to identify accessible amino acids and analyze their contribution into the structural changes of profilin-1 (PFN-1). The molecular docking/MD simulations are computational tools for enabling the analysis of the type of amino acids that may be involved via HDX identified under the lowest binding energy condition. Glycine to valine amino acid (G117V) substitution mutation is linked to amyotrophic lateral sclerosis (ALS). This mutation is found to be in the actin-binding site of PFN-1 and prevents the dimerization/polymerization of actin and invokes a pathologic toxicity that leads to ALS. In this study, we sought to understand the PFN-1 protein dynamic behavior using purified wild type and mutant PFN-1 proteins. The data obtained from HDX-MALDI-TOF MS for PFN-1WT and PFN-1G117V at various time intervals, from seconds to hours, revealed multiple peaks corresponding to molecular weights from monomers to multimers. PFN-1/Benzaldehyde complexes identified 20 accessible amino acids to HDX that participate in the docking simulation in the surface of WT and mutant PFN-1. Consistent results from HDX-MALDI-TOF MS and docking simulation predict candidate amino acid(s) involved in the dimerization/polymerization of PFNG117V. This information may shed critical light on the structural and conformational changes with details of amino acid epitopes for mutant PFN-1s' dimerization, oligomerization, and aggregation.
Collapse
Affiliation(s)
- Ahmad Shahir Sadr
- Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, Iran
- Computer Science Department, Mathematical Sciences Faculty, Shahid Beheshti University, Tehran, Iran
| | - Zahra Abdollahpour
- Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, Iran
| | - Atousa Aliahmadi
- Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, Iran
| | - Changiz Eslahchi
- Computer Science Department, Mathematical Sciences Faculty, Shahid Beheshti University, Tehran, Iran
- School of Biological Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
| | - Mina Nekouei
- Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, Iran
| | - Lily Kiaei
- RockGen Therapeutics, LLC, Little Rock, AR, 72205, USA
| | - Mahmoud Kiaei
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA.
- Department of Neurology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA.
- Department of Geriatrics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA.
- RockGen Therapeutics, LLC, Little Rock, AR, 72205, USA.
| | - Alireza Ghassempour
- Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, Iran.
| |
Collapse
|
3
|
Sych T, Gurdap CO, Wedemann L, Sezgin E. How Does Liquid-Liquid Phase Separation in Model Membranes Reflect Cell Membrane Heterogeneity? MEMBRANES 2021; 11:323. [PMID: 33925240 PMCID: PMC8146956 DOI: 10.3390/membranes11050323] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/22/2021] [Accepted: 04/26/2021] [Indexed: 11/22/2022]
Abstract
Although liquid-liquid phase separation of cytoplasmic or nuclear components in cells has been a major focus in cell biology, it is only recently that the principle of phase separation has been a long-standing concept and extensively studied in biomembranes. Membrane phase separation has been reconstituted in simplified model systems, and its detailed physicochemical principles, including essential phase diagrams, have been extensively explored. These model membrane systems have proven very useful to study the heterogeneity in cellular membranes, however, concerns have been raised about how reliably they can represent native membranes. In this review, we will discuss how phase-separated membrane systems can mimic cellular membranes and where they fail to reflect the native cell membrane heterogeneity. We also include a few humble suggestions on which phase-separated systems should be used for certain applications, and which interpretations should be avoided to prevent unreliable conclusions.
Collapse
Affiliation(s)
| | | | | | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women’s and Children’s Health, Karolinska Institutet, 17165 Solna, Sweden; (T.S.); (C.O.G.); (L.W.)
| |
Collapse
|
4
|
Martin EW, Chakraborty S, Presman DM, Tomassoni Ardori F, Oh KS, Kaileh M, Tessarollo L, Sung MH. Assaying Homodimers of NF-κB in Live Single Cells. Front Immunol 2019; 10:2609. [PMID: 31787981 PMCID: PMC6853996 DOI: 10.3389/fimmu.2019.02609] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 10/21/2019] [Indexed: 11/25/2022] Open
Abstract
NF-κB is a family of heterodimers and homodimers which are generated from subunits encoded by five genes. The predominant classical dimer RelA:p50 is presumed to operate as “NF-κB” in many contexts. However, there are several other dimer species which exist and may even be more functionally relevant in specific cell types. Accurate characterization of stimulus-specific and tissue-specific dimer repertoires is fundamentally important for understanding the downstream gene regulation by NF-κB proteins. In vitro assays such as immunoprecipitation have been widely used to analyze subunit composition, but these methods do not provide information about dimerization status within the natural intracellular environment of intact live cells. Here we apply a live single cell microscopy technique termed Number and Brightness to examine dimers translocating to the nucleus in fibroblasts after pro-inflammatory stimulation. This quantitative assay suggests that RelA:RelA homodimers are more prevalent than might be expected. We also found that the relative proportion of RelA:RelA homodimers can be perturbed by small molecule inhibitors known to disrupt the NF-κB pathway. Our findings show that Number and Brightness is a useful method for investigating NF-κB dimer species in live cells. This approach may help identify the relevant targets in pathophysiological contexts where the dimer specificity of NF-κB intervention is desired.
Collapse
Affiliation(s)
- Erik W Martin
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Sayantan Chakraborty
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Diego M Presman
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Francesco Tomassoni Ardori
- Mouse Cancer Genetics Program, National Cancer Institute, National Institutes of Health, Frederick, MD, United States
| | - Kyu-Seon Oh
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Mary Kaileh
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Lino Tessarollo
- Mouse Cancer Genetics Program, National Cancer Institute, National Institutes of Health, Frederick, MD, United States
| | - Myong-Hee Sung
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| |
Collapse
|
5
|
Nekouei M, Ghezellou P, Aliahmadi A, Arjmand S, Kiaei M, Ghassempour A. Changes in biophysical characteristics of PFN1 due to mutation causing amyotrophic lateral sclerosis. Metab Brain Dis 2018; 33:1975-1984. [PMID: 30203378 PMCID: PMC6230493 DOI: 10.1007/s11011-018-0305-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 08/12/2018] [Indexed: 12/11/2022]
Abstract
Single amino acid mutations in profilin 1 (PFN1) have been found to cause amyotrophic lateral sclerosis (ALS). Recently, we developed a mouse model for ALS using a PFN1 mutation (glycine 118 to valine, G118V), and we are now interested in understanding how PFN1 becomes toxically lethal with only one amino acid substitution. Therefore, we studied mutation-related changes in the PFN1 protein and hypothesized that such changes significantly disturb its structure. Initially, we expressed and studied the purified PFN1WT and PFN1G118V proteins from bacterial culture. We found that the PFN1G118V protein has a different mean residue ellipticity, as measured by far-UV circular dichroism, accompanied by a spectral shift. The intrinsic fluorescence of PFN1G118V showed a small fluctuation in maximum fluorescence absorption and intensity. Moreover, we examined the time course of PFN1 aggregation using SDS-PAGE, western blotting, and MALDI-TOF/TOF and found that compared with PFN1WT, PFN1G118V had an increased tendency to form aggregates. Dynamic light scattering data confirmed this, showing a larger size distribution for PFN1G118V. Our data explain why PFN1G118V tends to aggregate, a phenotype that may be the basis for its neurotoxicity.
Collapse
Affiliation(s)
- Mina Nekouei
- Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, Iran
| | - Parviz Ghezellou
- Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, Iran
| | - Atousa Aliahmadi
- Department of Biology, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, Iran
| | - Sareh Arjmand
- Protein Research Center, Shahid Beheshti University, G.C., Evin, Tehran, Iran
| | - Mahmoud Kiaei
- Department of Pharmacology and Toxicology, Department of Neurology, Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA.
| | - Alireza Ghassempour
- Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, Iran.
| |
Collapse
|
6
|
McKenna OE, Asam C, Araujo GR, Roulias A, Goulart LR, Ferreira F. How relevant is panallergen sensitization in the development of allergies? Pediatr Allergy Immunol 2016; 27:560-8. [PMID: 27129102 PMCID: PMC5006871 DOI: 10.1111/pai.12589] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/27/2016] [Indexed: 12/21/2022]
Abstract
Panallergens comprise various protein families of plant as well as animal origin and are responsible for wide IgE cross-reactivity between related and unrelated allergenic sources. Such cross-reactivities include reactions between various pollen sources, pollen and plant-derived foods as well as invertebrate-derived inhalants and foodstuff. Here, we provide an overview on the most clinically relevant panallergens from plants (profilins, polcalcins, non-specific lipid transfer proteins, pathogenesis-related protein family 10 members) and on the prominent animal-derived panallergen family, tropomyosins. In addition, we explore the role of panallergens in the sensitization process and progress of the allergic disease. Emphasis is given on epidemiological aspects of panallergen sensitization and clinical manifestations. Finally, the issues related to diagnosis and therapy of patients sensitized to panallergens are outlined, and the use of panallergens as predictors for cross-reactive allergy and as biomarkers for disease severity is discussed.
Collapse
Affiliation(s)
- Olivia E McKenna
- Department of Molecular Biology, University of Salzburg, Salzburg, Austria
| | - Claudia Asam
- Department of Molecular Biology, University of Salzburg, Salzburg, Austria
| | - Galber R Araujo
- Department of Molecular Biology, University of Salzburg, Salzburg, Austria.,Laboratory of Nanobiotechnology, Institute of Genetics and Biochemistry, Federal University of Uberlandia, Uberlandia, Brazil
| | - Anargyros Roulias
- Department of Molecular Biology, University of Salzburg, Salzburg, Austria
| | - Luiz R Goulart
- Laboratory of Nanobiotechnology, Institute of Genetics and Biochemistry, Federal University of Uberlandia, Uberlandia, Brazil.,Department of Medical Microbiology and Immunology, University of California, Davis, CA, USA
| | - Fatima Ferreira
- Department of Molecular Biology, University of Salzburg, Salzburg, Austria
| |
Collapse
|
7
|
Salvemini IL, Gau D, Reid J, Bagatolli L, Macmillan A, Moens P. Low PIP2 molar fractions induce nanometer size clustering in giant unilamellar vesicles. Chem Phys Lipids 2014; 177:51-63. [DOI: 10.1016/j.chemphyslip.2013.11.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 09/29/2013] [Accepted: 11/11/2013] [Indexed: 01/08/2023]
|
8
|
Czogalla A, Grzybek M, Jones W, Coskun U. Validity and applicability of membrane model systems for studying interactions of peripheral membrane proteins with lipids. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:1049-59. [PMID: 24374254 DOI: 10.1016/j.bbalip.2013.12.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 12/12/2013] [Accepted: 12/17/2013] [Indexed: 12/11/2022]
Abstract
The cell membrane serves, at the same time, both as a barrier that segregates as well as a functional layer that facilitates selective communication. It is characterized as much by the complexity of its components as by the myriad of signaling process that it supports. And, herein lays the problems in its study and understanding of its behavior - it has a complex and dynamic nature that is further entangled by the fact that many events are both temporal and transient in their nature. Model membrane systems that bypass cellular complexity and compositional diversity have tremendously accelerated our understanding of the mechanisms and biological consequences of lipid-lipid and protein-lipid interactions. Concurrently, in some cases, the validity and applicability of model membrane systems are tarnished by inherent methodical limitations as well as undefined quality criteria. In this review we introduce membrane model systems widely used to study protein-lipid interactions in the context of key parameters of the membrane that govern lipid availability for peripheral membrane proteins. This article is part of a Special Issue entitled Tools to study lipid functions.
Collapse
Affiliation(s)
- Aleksander Czogalla
- Laboratory of Membrane Biochemistry, Paul Langerhans Institute Dresden, Faculty of Medicine Carl Gustav Carus at the TU Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; German Center for Diabetes Research (DZD), Germany.
| | - Michał Grzybek
- Laboratory of Membrane Biochemistry, Paul Langerhans Institute Dresden, Faculty of Medicine Carl Gustav Carus at the TU Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; German Center for Diabetes Research (DZD), Germany
| | - Walis Jones
- Laboratory of Membrane Biochemistry, Paul Langerhans Institute Dresden, Faculty of Medicine Carl Gustav Carus at the TU Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; German Center for Diabetes Research (DZD), Germany
| | - Unal Coskun
- Laboratory of Membrane Biochemistry, Paul Langerhans Institute Dresden, Faculty of Medicine Carl Gustav Carus at the TU Dresden, Fetscherstrasse 74, 01307 Dresden, Germany; German Center for Diabetes Research (DZD), Germany.
| |
Collapse
|
9
|
Sezgin E, Schwille P. Model membrane platforms to study protein-membrane interactions. Mol Membr Biol 2012; 29:144-54. [DOI: 10.3109/09687688.2012.700490] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
10
|
Olshina MA, Wong W, Baum J. Holding back the microfilament--structural insights into actin and the actin-monomer-binding proteins of apicomplexan parasites. IUBMB Life 2012; 64:370-7. [PMID: 22454107 DOI: 10.1002/iub.1014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 02/03/2012] [Indexed: 01/02/2023]
Abstract
Parasites from the phylum Apicomplexa are responsible for several major diseases of man, including malaria and toxoplasmosis. These highly motile protozoa use a conserved actomyosin-based mode of movement to power tissue traversal and host cell invasion. The mode termed as 'gliding motility' relies on the dynamic turnover of actin, whose polymerisation state is controlled by a markedly limited number of identifiable regulators when compared with other eukaryotic cells. Recent studies of apicomplexan actin regulator structure-in particular those of the core triad of monomer-binding proteins, actin-depolymerising factor/cofilin, cyclase-associated protein/Srv2, and profilin-have provided new insights into possible mechanisms of actin regulation in parasite cells, highlighting divergent structural features and functions to regulators from other cellular systems. Furthermore, the unusual nature of apicomplexan actin itself is increasingly coming into the spotlight. Here, we review recent advances in understanding of the structure and function of actin and its regulators in apicomplexan parasites. In particular we explore the paradox between there being an abundance of unpolymerised actin, its having a seemingly increased potential to form filaments relative to vertebrate actin, and the apparent lack of visible, stable filaments in parasite cells.
Collapse
Affiliation(s)
- Maya A Olshina
- Division of Infection and Immunity, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | | | | |
Collapse
|
11
|
Tanabe A, Shiraishi M, Negishi M, Saito N, Tanabe M, Sasaki Y. MARCKS dephosphorylation is involved in bradykinin-induced neurite outgrowth in neuroblastoma SH-SY5Y cells. J Cell Physiol 2012; 227:618-29. [PMID: 21448919 DOI: 10.1002/jcp.22763] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Bradykinin (BK) plays a major role in producing peripheral sensitization in response to peripheral inflammation and in pain transmission in the central nerve system (CNS). Because BK activates protein kinase C (PKC) through phospholipase C (PLC)-β and myristoylated alanine-rich C kinase substrate (MARCKS) has been found to be a substrate of PKC, we explored the possibility that BK could induce MARCKS phosphorylation and regulate its function. BK stimulation induced transient MARCKS phosphorylation on Ser159 with a peak at 1 min in human neuroblastoma SH-SY5Y cells. By contrast, PKC activation by the phorbol ester phorbol 12,13-dibutyrate (PDBu) elicited MARCKS phosphorylation which lasted more than 10 min. Western blotting analyses and glutathione S-transferase (GST) pull-down analyses showed that the phosphorylation by BK was the result of activation of the PKC-dependent RhoA/Rho-associated coiled-coil kinase (ROCK) pathway. Protein phosphatase (PP) 2A inhibitors calyculin A and fostriecin inhibited the dephosphorylation of MARCKS after BK-induced phosphorylation. Moreover, immunoprecipitation analyses showed that PP2A interacts with MARCKS. These results indicated that PP2A is the dominant PP of MARCKS after BK stimulation. We established SH-SY5Y cell lines expressing wild-type MARCKS and unphosphorylatable MARCKS, and cell morphology changes after cell stimulation were studied. PDBu induced lamellipodia formation on the neuroblastoma cell line SH-SY5Y and the morphology was sustained, whereas BK induced neurite outgrowth of the cells via lamellipodia-like actin accumulation that depended on transient MARCKS phosphorylation. Thus these findings show a novel BK signal cascade-that is, BK promotes neurite outgrowth through transient MARCKS phosphorylation involving the PKC-dependent RhoA/ROCK pathway and PP2A in a neuroblastoma cell line.
Collapse
Affiliation(s)
- Atsuhiro Tanabe
- Laboratory of Pharmacology, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, Japan.
| | | | | | | | | | | |
Collapse
|
12
|
Characterization of supported lipid bilayers incorporating the phosphoinositides phosphatidylinositol 4,5-biphosphate and phosphoinositol-3,4,5-triphosphate by complementary techniques. Biointerphases 2011; 5:114-9. [PMID: 21219032 DOI: 10.1116/1.3516485] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Phosphoinositides are involved in a large number of processes in cells and it is very demanding to study individual protein-lipid interactions in vivo due to their rapid turnover and involvement in simultaneous events. Supported lipid bilayers (SLBs) containing controlled amounts of phosphoinositides provide a defined model system where important specific recognition events involving phosphoinositides can be systematically investigated using surface sensitive analytical techniques. The authors have demonstrated the formation and characterized the assembly kinetics of SLBs incorporating phosphatidylinositol 4,5-biphosphate (PIP(2); 1, 5, and 10 wt %) and phosphoinositol-3,4,5-triphosphate (1 wt %) using the quartz crystal microbalance with dissipation monitoring and fluorescence recovery after photobleaching. An increased fraction of phosphoinositides led to a higher barrier to liposome fusion, but full fluidity for the phosphatidylcholine lipids in the formed SLB. Significantly, the majority of phosphoinositides were shown to be immobile. X-ray photoelectron spectroscopy was used for the first time to verify that the PIP(2) fraction of lipids in the SLB scales linearly with the amount mixed in from stock solutions.
Collapse
|
13
|
Abstract
Molecular diffusion and transport processes are fundamental in physical, chemical, and biological systems. Current approaches to measuring molecular transport in cells and tissues based on perturbation methods, e.g., fluorescence recovery after photobleaching, are invasive; single-point fluctuation correlation methods are local; and single-particle tracking requires the observation of isolated particles for relatively long periods of time. We discuss here the detection of molecular transport by exploiting spatiotemporal correlations measured among points at large distances (>1 μm). We illustrate the evolution of the conceptual framework that started with single-point fluorescence fluctuation analysis based on the transit of fluorescent molecules through a small volume of illumination. This idea has evolved to include the measurement of fluctuations at many locations in the sample using microscopy imaging methods. Image fluctuation analysis has become a rich and powerful technique that can be used to extract information about the spatial distribution of molecular concentration and transport in cells and tissues.
Collapse
Affiliation(s)
- Michelle A Digman
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California 92697, USA
| | | |
Collapse
|
14
|
Ramachandran R. Vesicle scission: dynamin. Semin Cell Dev Biol 2010; 22:10-7. [PMID: 20837154 DOI: 10.1016/j.semcdb.2010.09.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 09/03/2010] [Accepted: 09/03/2010] [Indexed: 11/17/2022]
Abstract
Dynamin is a large GTPase involved in endocytic vesicle formation, but its exact role and mechanism are subjects of long-standing debate. Despite recent advances in the structural analyses of isolated dynamin domains and the faithful reconstitution of dynamin-dependent membrane fission in model membrane systems, the mechanism of its action remains poorly understood at the molecular level. Here, I will review current progress in elucidating dynamin action in vesicle scission and highlight the most visible gaps in knowledge that limit the development of a coherent and complete model for its role in vesicle biogenesis. Coordinated functions of BAR domain-containing binding partners are also discussed.
Collapse
Affiliation(s)
- Rajesh Ramachandran
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
| |
Collapse
|
15
|
Guizetti J, Gerlich DW. Cytokinetic abscission in animal cells. Semin Cell Dev Biol 2010; 21:909-16. [PMID: 20708087 DOI: 10.1016/j.semcdb.2010.08.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 05/27/2010] [Accepted: 08/03/2010] [Indexed: 10/19/2022]
Abstract
Cytokinesis leads to the separation of dividing cells, which in animal cells involves the contraction of an actin-myosin ring and subsequent fission during abscission. Abscission requires a series of dynamic events, including midbody-targeted vesicle secretion, specialization of plasma membrane domains, disassembly of midbody-associated microtubule bundles and plasma membrane fission. A large number of molecular factors required for abscission have been identified through localization, loss-of-function and proteomics studies, but their coordinate function in abscission is still poorly understood. Here, we review the structural elements and molecular factors known to contribute to abscission, and discuss their potential role in the context of proposed models for the abscission mechanism.
Collapse
Affiliation(s)
- Julien Guizetti
- Institute of Biochemistry, Swiss Federal Institute of Technology Zurich (ETHZ), Zurich, Switzerland
| | | |
Collapse
|
16
|
Sánchez SA, Tricerri MA, Ossato G, Gratton E. Lipid packing determines protein-membrane interactions: challenges for apolipoprotein A-I and high density lipoproteins. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1798:1399-408. [PMID: 20347719 PMCID: PMC2883020 DOI: 10.1016/j.bbamem.2010.03.019] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2009] [Revised: 03/18/2010] [Accepted: 03/19/2010] [Indexed: 12/16/2022]
Abstract
Protein and protein-lipid interactions, with and within specific areas in the cell membrane, are critical in order to modulate the cell signaling events required to maintain cell functions and viability. Biological bilayers are complex, dynamic platforms, and thus in vivo observations usually need to be preceded by studies on model systems that simplify and discriminate the different factors involved in lipid-protein interactions. Fluorescence microscopy studies using giant unilamellar vesicles (GUVs) as membrane model systems provide a unique methodology to quantify protein binding, interaction, and lipid solubilization in artificial bilayers. The large size of lipid domains obtainable on GUVs, together with fluorescence microscopy techniques, provides the possibility to localize and quantify molecular interactions. Fluorescence Correlation Spectroscopy (FCS) can be performed using the GUV model to extract information on mobility and concentration. Two-photon Laurdan Generalized Polarization (GP) reports on local changes in membrane water content (related to membrane fluidity) due to protein binding or lipid removal from a given lipid domain. In this review, we summarize the experimental microscopy methods used to study the interaction of human apolipoprotein A-I (apoA-I) in lipid-free and lipid-bound conformations with bilayers and natural membranes. Results described here help us to understand cholesterol homeostasis and offer a methodological design suited to different biological systems.
Collapse
Affiliation(s)
- Susana A Sánchez
- Laboratory for Fluorescence Dynamics (LFD), University of California at Irvine, Biomedical Engineering Department, Irvine, CA 92697-2715, USA.
| | | | | | | |
Collapse
|
17
|
Walde P, Cosentino K, Engel H, Stano P. Giant Vesicles: Preparations and Applications. Chembiochem 2010; 11:848-65. [DOI: 10.1002/cbic.201000010] [Citation(s) in RCA: 556] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
18
|
Pontrello CG, Ethell IM. Accelerators, Brakes, and Gears of Actin Dynamics in Dendritic Spines. ACTA ACUST UNITED AC 2009; 3:67-86. [PMID: 20463852 DOI: 10.2174/1874082000903020067] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Dendritic spines are actin-rich structures that accommodate the postsynaptic sites of most excitatory synapses in the brain. Although dendritic spines form and mature as synaptic connections develop, they remain plastic even in the adult brain, where they can rapidly grow, change, or collapse in response to normal physiological changes in synaptic activity that underlie learning and memory. Pathological stimuli can adversely affect dendritic spine shape and number, and this is seen in neurodegenerative disorders and some forms of mental retardation and autism as well. Many of the molecular signals that control these changes in dendritic spines act through the regulation of filamentous actin (F-actin), some through direct interaction with actin, and others via downstream effectors. For example, cortactin, cofilin, and gelsolin are actin-binding proteins that directly regulate actin dynamics in dendritic spines. Activities of these proteins are precisely regulated by intracellular signaling events that control their phosphorylation state and localization. In this review, we discuss how actin-regulating proteins maintain the balance between F-actin assembly and disassembly that is needed to stabilize mature dendritic spines, and how changes in their activities may lead to rapid remodeling of dendritic spines.
Collapse
Affiliation(s)
- Crystal G Pontrello
- Biomedical Sciences Division and Neuroscience program, University of California Riverside, USA
| | | |
Collapse
|