title: Gangliosides play an important role in the organization of CD82-enriched microdomains.
abstract: Four-transmembrane-domain proteins of the tetraspanin superfamily are the organizers of specific microdomains at the membrane [TERMs (tetraspanin-enriched microdomains)] that incorporate various transmembrane receptors and modulate their activities. The structural aspects of the organization of TERM are poorly understood. In the present study, we investigated the role of gangliosides in the assembly and stability of TERM. We demonstrated that inhibition of the glycosphingolipid biosynthetic pathway with specific inhibitors of glucosylceramide synthase [NB-DGJ (N-butyldeoxygalactonojirimycin) and PPMP (D-threo-1-phenyl-2-hexadecanoylamino-3-morpholino-1-propanol.HCl)] resulted in specific weakening of the interactions involving tetraspanin CD82. Furthermore, ectopic expression of the plasma-membrane-bound sialidase Neu3 in mammary epithelial cells also affected stability of the complexes containing CD82: its association with tetraspanin CD151 was decreased, but the association with EGFR [EGF (epidermal growth factor) receptor] was enhanced. The destabilization of the CD82-containing complexes upon ganglioside depletion correlated with the re-distribution of the proteins within plasma membrane. Importantly, depletion of gangliosides affected EGF-induced signalling only in the presence of CD82. Taken together, our results provide strong evidence that gangliosides play an important role in supporting the integrity of CD82-enriched microdomains. Furthermore, these results demonstrate that the association between different tetraspanins in TERM is controlled by distinct mechanisms and identify Neu3 as a first physiological regulator of the integrity of these microdomains.
authors.affiliation: Cancer Research U.K. Institute for Cancer Studies, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. odintsoe@bham.ac.uk
authors.forename: Elena
authors.initials: E
authors.lastname: Odintsova
authors.forename: Terry D
authors.initials: TD
authors.lastname: Butters
authors.forename: Eugenio
authors.initials: E
authors.lastname: Monti
authors.forename: Hein
authors.initials: H
authors.lastname: Sprong
authors.forename: Gerrit
authors.initials: G
authors.lastname: van Meer
authors.forename: Fedor
authors.initials: F
authors.lastname: Berditchevski
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D005679:G(M3) Ganglioside / Q000378:metabolism / Q000494:pharmacology; D005732:Gangliosides / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000378:metabolism* / Q000494:pharmacology; D006028:Glycosphingolipids / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D006801:Humans; D051861:Kangai-1 Protein / Q000096:biosynthesis / Q000378:metabolism*; D021962:Membrane Microdomains / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D059470:Tetraspanins
chemical_list: D005679:G(M3) Ganglioside; D005732:Gangliosides; D006028:Glycosphingolipids; D051861:Kangai-1 Protein; D008565:Membrane Proteins; C109139:TSPAN4 protein, human; D059470:Tetraspanins; C021298:ganglioside, GD1a; D066246:ErbB Receptors