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      Micrometer-Scale Membrane Transition of Supported Lipid Bilayer Membrane Reconstituted with Cytosol of Dictyostelium discoideum

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      Life

      MDPI

      supported lipid bilayer membrane, phosphatidylinositides, cytosol, Dictyostelium discoideum

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          Abstract

          Background: The transformation of the supported lipid bilayer (SLB) membrane by extracted cytosol from living resources, has recently drawn much attention. It enables us to address the question of whether the purified phospholipid SLB membrane, including lipids related to amoeba locomotion, which was discussed in many previous studies, exhibits membrane deformation in the presence of cytosol extracted from amoeba; Methods: In this report, a method for reconstituting a supported lipid bilayer (SLB) membrane, composed of purified phospholipids and cytosol extracted from Dictyostelium discoideum, is described. This technique is a new reconstitution method combining the artificial constitution of membranes with the reconstitution using animate cytosol (without precise purification at a molecular level), contributing to membrane deformation analysis; Results: The morphology transition of a SLB membrane composed of phosphatidylcholines, after the addition of cytosolic extract, was traced using a confocal laser scanning fluorescence microscope. As a result, pore formation in the SLB membrane was observed and phosphatidylinositides incorporated into the SLB membrane tended to suppress pore formation and expansion; Conclusions: The current findings imply that phosphatidylinositides have the potential to control cytoplasm activity and bind to a phosphoinositide-containing SLB membrane.

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          Most cited references 33

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          Spatial regulators for bacterial cell division self-organize into surface waves in vitro.

          In the bacterium Escherichia coli, the Min proteins oscillate between the cell poles to select the cell center as division site. This dynamic pattern has been proposed to arise by self-organization of these proteins, and several models have suggested a reaction-diffusion type mechanism. Here, we found that the Min proteins spontaneously formed planar surface waves on a flat membrane in vitro. The formation and maintenance of these patterns, which extended for hundreds of micrometers, required adenosine 5'-triphosphate (ATP), and they persisted for hours. We present a reaction-diffusion model of the MinD and MinE dynamics that accounts for our experimental observations and also captures the in vivo oscillations.
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            Tumor suppressor PTEN mediates sensing of chemoattractant gradients.

            Shallow gradients of chemoattractants, sensed by G protein-linked signaling pathways, elicit localized binding of PH domains specific for PI(3,4,5)P3 at sites on the membrane where rearrangements of the cytoskeleton and pseudopod extension occur. Disruption of the PI 3-phosphatase, PTEN, in Dictyostelium discoideum dramatically prolonged and broadened the PH domain relocation and actin polymerization responses, causing the cells lacking PTEN to follow a circuitous route toward the attractant. Exogenously expressed PTEN-GFP localized to the surface membrane at the rear of the cell. Membrane localization required a putative PI(4,5)P2 binding motif and was required for chemotaxis. These results suggest that specific phosphoinositides direct actin polymerization to the cell's leading edge and regulation of PTEN through a feedback loop plays a critical role in gradient sensing and directional migration.
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              The onset of collective behavior in social amoebae.

              In the social amoebae Dictyostelium discoideum, periodic synthesis and release of extracellular cyclic adenosine 3',5'-monophosphate (cAMP) guide cell aggregation and commitment to form fruiting bodies. It is unclear whether these oscillations are an intrinsic property of individual cells or if they exist only as a population-level phenomenon. Here, we showed by live-cell imaging of intact cell populations that pulses originate from a discrete location despite constant exchange of cells to and from the region. In a perfusion chamber, both isolated single cells and cell populations switched from quiescence to rhythmic activity depending on the concentration of extracellular cAMP. A quantitative analysis showed that stochastic pulsing of individual cells below the threshold concentration of extracellular cAMP plays a critical role in the onset of collective behavior.
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                Author and article information

                Contributors
                Role: Academic Editor
                Journal
                Life (Basel)
                Life (Basel)
                life
                Life
                MDPI
                2075-1729
                07 March 2017
                March 2017
                : 7
                : 1
                Affiliations
                Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan; takahashikei0309@ 123456gmail.com
                Author notes
                [* ]Correspondence: cttoyota@ 123456mail.ecc.u-tokyo.ac.jp ; Tel.: +81-3-5465-7634
                Article
                life-07-00011
                10.3390/life7010011
                5370411
                28272354
                © 2017 by the authors.

                Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( http://creativecommons.org/licenses/by/4.0/).

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