Prominin-2 expression increases protrusions,decreases caveolae and inhibits Cdc42 dependent fluid phase endocytosis |
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| Affiliation: | 1. Division of Nephrology, Medizinische Klinik und Poliklinik IV, Campus Innenstadt, University of Munich-LMU, Munich, Germany;2. Department of Cellular and Molecular Pathology, German Cancer Research Center, Heidelberg, Germany;3. Walter Brendel Center for Experimental Medicine, Munich, Germany;4. Istituto Clinico Humanitas, IRCCS, Rozzano, Italy;5. Department of Translational Medicine, University of Milan, Rozzano, Italy;1. Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, the Netherlands;2. VitaK, Maastricht University, Maastricht, the Netherlands;3. National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands;1. Department of Obstetrics and Gynecology, The Ohio State University College of Medicine, Columbus, OH 43210, USA;2. Department of Obstetrics and Gynecology, The University of South Florida, Tampa, FL 33606, USA;3. Department of Pathology, The Ohio State University College of Medicine, Columbus, OH 43210, USA;4. Biomedical Informatics Shared Resource, The Ohio State University College of Medicine, Columbus, OH 43210, USA |
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| Abstract: | BackgroundMembrane protrusions play important roles in biological processes such as cell adhesion, wound healing, migration, and sensing of the external environment. Cell protrusions are a subtype of membrane microdomains composed of cholesterol and sphingolipids, and can be disrupted by cholesterol depletion. Prominins are pentaspan membrane proteins that bind cholesterol and localize to plasma membrane (PM) protrusions. Prominin-1 is of great interest as a marker for stem and cancer cells, while Prominin-2 (Prom2) is reportedly restricted to epithelial cells.AimTo characterize the effects of Prom-2 expression on PM microdomain organization.MethodsProm2-fluorescent protein was transfected in human skin fibroblasts (HSF) and Chinese hamster ovary (CHO) cells for PM raft and endocytic studies. Caveolae at PM were visualized using transmission electron microscopy. Cdc42 activation was measured and caveolin-1 knockdown was performed using siRNAs.ResultsProm2 expression in HSF and CHO cells caused extensive Prom2-positive protrusions that co-localized with lipid raft markers. Prom2 expression significantly decreased caveolae at the PM, reduced caveolar endocytosis and increased caveolin-1 phosphorylation. Prom2 expression also inhibited Cdc42-dependent fluid phase endocytosis via decreased Cdc42 activation. Effects on endocytosis were reversed by addition of cholesterol. Knockdown of caveolin-1 by siRNA restored Cdc42 dependent fluid phase endocytosis in Prom2-expressing cells.ConclusionsProm2 protrusions primarily localize to lipid rafts and recruit cholesterol into protrusions and away from caveolae, leading to increased phosphorylation of caveolin-1, which inhibits Cdc42-dependent endocytosis. This study provides a new insight for the role for prominins in the regulation of PM lipid organization. |
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| Keywords: | Lipid rafts Filopodia Sphingolipids Rho proteins |
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