Syndecan-2 expression increases serum-withdrawal-induced apoptosis, mediated by re-distribution of Fas into lipid rafts, in stably transfected Swiss 3T3 cells.
To examine the function of syndecan-2, one of the most abundant heparan sulfate proteoglycans in fibroblasts, we obtained stably transfected Swiss 3T3 clones. We examined the effects of stable syndecan-2 overexpression on programmed cell death, finding that syndecan-2 transfected cells were more sensitive to apoptosis induced by serum-withdrawal than control cells. In addition, overexpression of syndecan-2 correlates with increased membrane levels of the Fas/CD95 receptor, suggesting that the increased serum-withdrawal apoptosis observed in Swiss 3T3 cells might be Fas receptor-dependent. Differences in Fas membrane levels between both control and syndecan-2 transfected cells result from a redistribution of the Fas receptor. Our data clearly demonstrate that increased Fas levels are primarily related to lipid rafts and that this increase is a key factor in Fas/CD95-mediated apoptosis. Moreover, disruption of lipid rafts with methyl-beta-cyclodextrin or filipin significantly reduced apoptosis in response to serum withdrawal. The differences in Fas/CD95 membrane distribution could explain why syndecan-2 transfected cells have a higher susceptibility to serum-withdrawal-induced apoptosis.
Villena
Joan
J
Department of Cellular Biology, Faculty of Biology, University of Barcelona, Diagonal 645, 08028, Barcelona, Spain. juan.villena@uv.cl
Mainez
Jessica
J
Noguer
Oriol
O
Contreras
Héctor
H
Granés
Francesc
F
Reina
Manuel
M
Fabregat
Isabel
I
Vilaró
Senén
S
D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002417:Cattle; D018929:Cell Culture Techniques; D018076:DNA, Complementary; D004285:Dogs; D053222:Fas Ligand Protein / Q000378:metabolism*; D005372:Filipin / Q000494:pharmacology; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism*; D051379:Mice; D044967:Serum / Q000378:metabolism*; D053669:Syndecan-2 / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D047392:beta-Cyclodextrins / Q000494:pharmacology
D018076:DNA, Complementary; D053222:Fas Ligand Protein; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D053669:Syndecan-2; D005372:Filipin