PKC-promoted endocytosis of the glutamate transporter GLT-1 requieres Nedd4-2-dependent ubiquitination but not phosphorylation

Autor: García-Tardón, Noemí, González González, María Inmaculada, Martínez-Villareal, Jaime, Fernández-Sánchez, Enrique, Giménez Martín, Cecilio, Zafra, Francisco
Přispěvatelé: Ministerio de Economía y Competitividad (España), Instituto de Salud Carlos III, Comunidad de Madrid, Fundación Ramón Areces
Rok vydání: 2012
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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Popis: Glutamate transporter-1 (GLT-1) is the main glutamate transporter in the central nervous system, and its concentration severely decreases in neurodegenerative diseases. The number of transporters in the plasma membrane reflects the balance between their insertion and removal, and it has been reported that the regulated endocytosis of GLT-1 depends on its ubiquitination triggered by protein kinase C (PKC) activation. Here, we identified serine 520 of GLT-1 as the primary target for PKC-dependent phosphorylation, although elimination of this serine did not impair either GLT-1 ubiquitination or endocytosis in response to phorbol esters. In fact, we present evidence indicating that the ubiquitin ligase Nedd4-2 mediates the PKC-dependent ubiquitination and down-regulation of GLT-1. Overexpression of Nedd4-2 increased the ubiquitination of the transporter and promoted its degradation. Moreover, phorbol myristate acetate enhanced Nedd4-2 phosphorylation and the formation of GLT-1·Nedd4-2 complexes, whereas siRNA knockdown of Nedd4-2 prevented ubiquitination, endocytosis, and the concomitant decrease in GLT-1 activity triggered by PKC activation. These results indicate that GLT-1 endocytosis is independent of its phosphorylation and that Nedd4-2 mediates PKC-dependent down-regulation of the transporter
Spanish Dirección General de Investigación Científica y Técnica; Fondo de Investigaciones Sanitarias (CIBERER); Comunidad Autónoma de Madrid; Fundación Ramón Areces
Databáze: OpenAIRE
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