INVESTIGADORES
VILCAES Aldo Alejandro
artículos
Título:
Role of plasma membrane-bound sialidase NEU3 in clathrin-mediated endocytosis
Autor/es:
RODRIGUEZ WALKER M.; VILCAES A.A.; GARBARINO-PICO E.; DANIOTTI J.L.
Revista:
BIOCHEMICAL JOURNAL
Editorial:
PORTLAND PRESS LTD
Referencias:
Lugar: Londres; Año: 2015
ISSN:
0264-6021
Resumen:
Gangliosides are sialic acid-containing glycosphingolipidsmainly expressed at the outer leaflet of the plasma membrane.Sialidase NEU3 is a key enzyme in the catabolism of gangliosideswith its up-regulation having been observed in human cancercells. In the case of CME (clathrin-mediated endocytosis),although this has been widely studied, the role of NEU3 andgangliosides in this cellular process has not yet been established.In the present study, we found an increased internalizationof Tf (transferrin), the archetypical cargo for CME, in cellsexpressing complex gangliosides with high levels of sialylation.The ectopic expression of NEU3 led to a drastic decrease inTf endocytosis, suggesting the participation of gangliosides inthis process. However, the reduction in Tf endocytosis causedby NEU3 was still observed in glycosphingolipid-depleted cells,indicating that NEU3 could operate in a way that is independentof its action on gangliosides. Additionally, internalization of α2-macroglobulin and low-density lipoprotein, other typical ligandsin CME, was also decreased in NEU3-expressing cells. Incontrast, internalization of cholera toxin β-subunit, which isendocytosed by both clathrin-dependent and clathrin-independentmechanisms, remained unaltered. Kinetic assays revealed thatNEU3 caused a reduction in the sorting of endocytosed Tf to earlyand recycling endosomes, with the Tf binding at the cell surfacebeing also reduced. NEU3-expressing cells showed an alteredsubcellular distribution of clathrin adaptor AP-2 (adaptor protein2), but did not reveal any changes in the membrane distributionof clathrin, PtdIns(4,5)P2 or caveolin-1. Overall, these resultssuggest a specific and novel role of NEU3 in CME.Key words: clathrin, ganglioside, glycolipid, membranetrafficking, NEU3, sialidase.