부산대학교 도서관

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1471-4159.2006.04410.x Byline: Stephane Barakat (,), Michel Demeule (*), Anthony Pilorget (*), Anthony Regina (*), Denis Gingras (*), Loris G. Baggetto ([dagger]), Richard Beliveau (*) Keywords: blood-brain barrier; caveolin-1; endothelial cells; p-glycoprotein; phosphorylation; Sarcoma Abstract: Abstract p-glycoprotein (p-gp) is an ATP-binding cassette transporter and its overexpression is responsible for the acquisition of the multidrug resistance phenotype in human tumors. p-gp is localized at the blood-brain barrier and is involved in brain cytoprotection. Our previous work used immunoprecipitation to show that caveolin-1 can interact with p-gp. In this study, we provide evidence that caveolin-1 regulates p-gp transport activity in a rat brain endothelial cell line (RBE4). Down-regulation of caveolin-1 by siRNA reduced the interaction between p-gp and caveolin-1, followed by a decrease in [3.sup.H]-Taxol and [3.sup.H]-Vinblastine accumulation in RBE4 cells. The latter result showed that down-regulation of caveolin-1 enhanced p-gp transport activity. RBE4 cells were also transfected with Sarcoma in order to modulate caveolin-1 phosphorylation. Overexpression of Sarcoma, a protein tyrosine kinase, stimulated caveolin-1 phosphorylation and increased both [3.sup.H]-Taxol and [3.sup.H]-Vinblastine accumulation as well as Hoechst 33342 accumulation. Transfection of caveolin-1 inhibits p-gp transport activity. Conversely, transfection of the mutant cavY14F decreased the p-gp/caveolin-1 interaction and reduced accumulation of the two p-gp substrates. Thus, our data show that caveolin-1 regulates p-gp function through the phosphorylation state of caveolin-1 in endothelial cells from the blood-brain barrier. Author Affiliation: (*)Laboratoire de medecine moleculaire, Hopital Sainte-Justine, Universite du Quebec a Montreal, Montreal, Quebec, Canada ([dagger])Laboratoire Therapie transcriptionnelle des cellules cancereuses, Institut de Biologie et Chimie des Proteines, Lyon, France Article History: Received March 7, 2006; revised manuscript received May 31, 2006; accepted June 7, 2006. Article note: Address correspondence and reprint requests to Dr Richard Beliveau, Departement de Chimie-Biochimie, Universite du Quebec a Montreal, CP 8888, succursale centre-ville, Montreal, Quebec, H3C 3P8, Canada. E-mail: oncomol@nobel.si.uqam.ca