title: Integrin-mediated transactivation of P2X7R via hemichannel-dependent ATP release stimulates astrocyte migration.
abstract: Our previous reports indicate that ligand-induced αVβ3 integrin and Syndecan-4 engagement increases focal adhesion formation and migration of astrocytes. Additionally, ligated integrins trigger ATP release through unknown mechanisms, activating P2X7 receptors (P2X7R), and the uptake of Ca(2+) to promote cell adhesion. However, whether the activation of P2X7R and ATP release are required for astrocyte migration and whether αVβ3 integrin and Syndecan-4 receptors communicate with P2X7R via ATP remains unknown. Here, cells were stimulated with Thy-1, a reported αVβ3 integrin and Syndecan-4 ligand. Results obtained indicate that ATP was released by Thy-1 upon integrin engagement and required the participation of phosphatidylinositol-3-kinase (PI3K), phospholipase-C gamma (PLCγ) and inositol trisphosphate (IP3) receptors (IP3R). IP3R activation leads to increased intracellular Ca(2+), hemichannel (Connexin-43 and Pannexin-1) opening, and ATP release. Moreover, silencing of the P2X7R or addition of hemichannel blockers precluded Thy-1-induced astrocyte migration. Finally, Thy-1 lacking the integrin-binding site did not stimulate ATP release, whereas Thy-1 mutated in the Syndecan-4-binding domain increased ATP release, albeit to a lesser extent and with delayed kinetics compared to wild-type Thy-1. Thus, hemichannels activated downstream of an αVβ3 integrin-PI3K-PLCγ-IP3R pathway are responsible for Thy-1-induced, hemichannel-mediated and Syndecan-4-modulated ATP release that transactivates P2X7Rs to induce Ca(2+) entry. These findings uncover a hitherto unrecognized role for hemichannels in the regulation of astrocyte migration via P2X7R transactivation induced by integrin-mediated ATP release.
authors.affiliation: Cellular Communication Laboratory, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile; Biomedical Neuroscience Institute, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Alvarez
authors.affiliation: Cellular Communication Laboratory, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile; Biomedical Neuroscience Institute, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile.
authors.forename: Raúl
authors.initials: R
authors.lastname: Lagos-Cabré
authors.affiliation: Cellular Communication Laboratory, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile; Biomedical Neuroscience Institute, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile.
authors.forename: Milene
authors.initials: M
authors.lastname: Kong
authors.affiliation: Cellular Communication Laboratory, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile; Biomedical Neuroscience Institute, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile.
authors.forename: Areli
authors.initials: A
authors.lastname: Cárdenas
authors.affiliation: Cellular Communication Laboratory, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile; Biomedical Neuroscience Institute, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile.
authors.forename: Francesca
authors.initials: F
authors.lastname: Burgos-Bravo
authors.affiliation: Department of Biochemistry, University of Lausanne, 1066 Epalinges, Switzerland.
authors.forename: Pascal
authors.initials: P
authors.lastname: Schneider
authors.affiliation: Cellular Communication Laboratory, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile; Advanced Center for Chronic Diseases, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile; Biomedical Neuroscience Institute, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile.
authors.forename: Andrew F G
authors.initials: AF
authors.lastname: Quest
authors.affiliation: Cellular Communication Laboratory, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile; Advanced Center for Chronic Diseases, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile; Biomedical Neuroscience Institute, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 838-0453 Santiago, Chile. Electronic address: lleyton@med.uchile.cl.
authors.forename: Lisette
authors.initials: L
authors.lastname: Leyton
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D016764:Cell Polarity; D018031:Connexin 43 / Q000378:metabolism; D017630:Connexins / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D042541:Intracellular Space / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D051381:Rats; D058486:Receptors, Purinergic P2X7 / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D053671:Syndecan-4 / Q000378:metabolism; D018800:Thy-1 Antigens / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics*; D014945:Wound Healing
chemical_list: D018031:Connexin 43; D017630:Connexins; D053496:Inositol 1,4,5-Trisphosphate Receptors; D039302:Integrin alphaVbeta3; D009419:Nerve Tissue Proteins; D058486:Receptors, Purinergic P2X7; D053671:Syndecan-4; D018800:Thy-1 Antigens; C479936:pannexin 1, rat; D000255:Adenosine Triphosphate; D002118:Calcium
keywords: ATP; Calcium; Cell migration; Connexins; Pannexins; Thy-1