Urokinase-receptor-mediated phenotypic changes in vascular smooth muscle cells require the involvement of membrane rafts.

Content Provider	Semantic Scholar
Author	Kiyan, J. Ryo Smith, Graham M. Haller, Hermann Dumler, I. L.
Copyright Year	2009
Abstract	The cholesterol-enriched membrane microdomains lipid rafts play a key role in cell activation by recruiting and excluding specific signalling components of cell-surface receptors upon receptor engagement. Our previous studies have demonstrated that the GPI (glycosylphosphatidylinositol)-linked uPAR [uPA (urokinase-type plasminogen activator) receptor], which can be found in lipid rafts and in non-raft fractions, can mediate the differentiation of VSMCs (vascular smooth muscle cells) towards a pathophysiological de-differentiated phenotype. However, the mechanism by which uPAR and its ligand uPA regulate VSMC phenotypic changes is not known. In the present study, we provide evidence that the molecular machinery of uPAR-mediated VSMC differentiation employs lipid rafts. We show that the disruption of rafts in VSMCs by membrane cholesterol depletion using MCD (methyl-beta-cyclodextrin) or filipin leads to the up-regulation of uPAR and cell de-differentiation. uPAR silencing by means of interfering RNA resulted in an increased expression of contractile proteins. Consequently, disruption of lipid rafts impaired the expression of these proteins and transcriptional activity of related genes. We provide evidence that this effect was mediated by uPAR. Similar effects were observed in VSMCs isolated from Cav1Z(-/-) (caveolin-1-deficient) mice. Despite the level of uPAR being significantly higher after the disruption of the rafts, uPA/uPAR-dependent cell migration was impaired. However, caveolin-1 deficiency impaired only uPAR-dependent cell proliferation, whereas cell migration was strongly up-regulated in these cells. Our results provide evidence that rafts are required in the regulation of uPAR-mediated VSMC phenotypic modulations. These findings suggest further that, in the context of uPA/uPAR-dependent processes, caveolae-associated and non-associated rafts represent different signalling membrane domains.
Starting Page	178
Ending Page	185
Page Count	8
File Format	PDF HTM / HTML
Alternate Webpage(s)	http://www.biochemj.org/content/ppbiochemj/423/3/343.full.pdf
PubMed reference number	19691446v1
Alternate Webpage(s)	https://doi.org/10.1042/BJ20090447
DOI	10.1042/bj20090447
Journal	The Biochemical journal
Volume Number	423
Issue Number	3
Language	English
Access Restriction	Open
Subject Keyword	Caveolae Cell Proliferation Cholesterol Contractile Proteins Cyclodextrins Filipin Hypocholesterolemia Ligands Lipid Metabolism Disorders Malonic aciduria Membrane Microdomains Muscle Cells Muscle Contraction Muscle, Smooth, Vascular Myocytes, Smooth Muscle RNA Smooth muscle (tissue) Tissue membrane Transcription, Genetic Urokinase Plasminogen Activator Receptor biological signaling lipid raft methyl-beta-cyclodextrin
Content Type	Text
Resource Type	Article