title: Rosiglitazone balances insulin-induced exo- and endocytosis in single 3T3-L1 adipocytes.
abstract: Rosiglitazone (Rosi) improves insulin sensitivity and increases the translocation of glucose transporter 4 (GLUT4) to the plasma membrane (PM). This involves the fusion of membrane-bound compartments with the plasma membrane, thus increasing the plasma membrane area. However, recent work has shown that in Rosi-pretreated 3T3-L1 adipocytes membrane area did not increase following insulin application, suggesting that the rates of exo- and endocytosis are balanced. Here we examined whether Rosi differentially affects the rates of exo- and endocytosis in 3T3-L1 adipocytes. The immunolabelling of GLUT4 revealed the 3.1-fold increase in PM-resident GLUT4 in Rosi-pretreated, insulin-stimulated cells. By monitoring cumulative exocytosis and endocytosis we found that in Rosi-pretreated cells insulin substantially stimulated the rate of exocytosis and to a similar extent also the rate of endocytosis. We conclude that Rosi-pretreatment balances insulin-stimulated exocytosis and endocytosis, which may prevent insulin-mediated adipocyte cell size increase.
authors.affiliation: Celica, Biomedical Center, Ljubljana, Slovenia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Velebit
authors.forename: Helena H
authors.initials: HH
authors.lastname: Chowdhury
authors.forename: Marko
authors.initials: M
authors.lastname: Kreft
authors.forename: Robert
authors.initials: R
authors.lastname: Zorec
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D004705:Endocytosis / Q000187:drug effects*; D005089:Exocytosis / Q000187:drug effects*; D005455:Fluorescent Antibody Technique; D005470:Fluorometry; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology*; D007333:Insulin Resistance; D051379:Mice; D018613:Microscopy, Confocal; D000077154:Rosiglitazone; D045162:Thiazolidinediones / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D051275:Glucose Transporter Type 4; D007328:Insulin; D045162:Thiazolidinediones; D000077154:Rosiglitazone