Scientific Results

Decoupling Polarization of the Golgi Apparatus and GM1 in the Plasma Membrane

Year: 2013

Authors: Bisel B., Calamai M., Vanzi F., Pavone FS.

Autors Affiliation: European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy; National Research Council of Italy (CNR), National Institute of Optics, Largo Fermi 6, 50125, Florence, Italy; Department of Evolutionary Biology “Leo Pardi”, University of Florence, Via Romana 17, 50125 Florence, Italy

Abstract: Cell polarization is a process of coordinated cellular rearrangements that prepare the cell for migration. GM1 is synthesized in the Golgi apparatus and localized in membrane microdomains that appear at the leading edge of polarized cells, but the mechanism by which GM1 accumulates asymmetrically is unknown. The Golgi apparatus itself becomes oriented toward the leading edge during cell polarization, which is thought to contribute to plasma membrane asymmetry. Using quantitative image analysis techniques, we measure the extent of polarization of the Golgi apparatus and GM1 in the plasma membrane simultaneously in individual cells subject to a wound assay. We find that GM1 polarization starts just 10 min after stimulation with growth factors, while Golgi apparatus polarization takes 30 min. Drugs that block Golgi polarization or function have no effect on GM1 polarization, and, conversely, inhibiting GM1 polarization does not affect Golgi apparatus polarization. Evaluation of Golgi apparatus and GM1 polarization in single cells reveals no correlation between the two events. Our results indicate that Golgi apparatus and GM1 polarization are controlled by distinct intracellular cascades involving the Ras/Raf/MEK/ERK and the PI3K/Akt/mTOR pathways, respectively. Analysis of cell migration and invasion suggest that MEK/ERK activation is crucial for two dimensional migration, while PI3K activation drives three dimensional invasion, and no cumulative effect is observed from blocking both simultaneously. The independent biochemical control of GM1 polarity by PI3K and Golgi apparatus polarity by MEK/ERK may act synergistically to regulate and reinforce directional selection in cell migration.

Journal/Review: PLOS ONE

Volume: 8 (12)      Pages from: e80446  to: e80450

More Information: This work was funded by the Fondazione Italiana per la Ricerca sul Cancro (FIRC) via a postdoctoral fellowship \”Pierluigi Meneghelli\” awarded to BB. The research leading to these results also received funding from the European Community\’s Seventh Framework Programme (FP7/2007-2013) under Grant Agreement n. PIEF-GA-2009-254791. Additional funding was provided by LASERLAB-EUROPE (grant agreement no 284464, EC\’s Seventh Framework Programme). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
KeyWords: 1,4 diamino 1,4 bis(2 aminophenylthio) 2,3 dicyanobutadiene; brefeldin A; ganglioside GM1; lysophosphatidic acid; mammalian target of rapamycin; mitogen activated protein kinase; phosphatidylinositol 3 kinase; protein kinase B; Raf protein; Ras protein; wortmannin, article; cancer cell culture; cell invasion; cell membrane; cell membrane depolarization; cell membrane transport; cell migration; cell polarity; cellular distribution; controlled study; drug targeting; enzyme activation; Golgi complex; human; human cell; image analysis; lipid analysis; molecular imaging; protein expression; protein function; protein lipid interaction; protein phosphorylation; quantitative study; signal transduction, Cell Line, Tumor; Cell Membrane; Cell Movement; Extracellular Signal-Regulated MAP Kinases; G(M1) Ganglioside; Golgi Apparatus; Humans; MAP Kinase Signaling System; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; TOR Serine-Threonine Kinases
DOI: 10.1371/journal.pone.0080446

Citations: 5
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