title: The activities of LDL Receptor-related Protein-1 (LRP1) compartmentalize into distinct plasma membrane microdomains.
abstract: LDL Receptor-related Protein-1 (LRP1) is an endocytic receptor for diverse ligands. In neurons and neuron-like cells, ligand-binding to LRP1 initiates cell-signaling. Herein, we show that in PC12 and N2a neuron-like cells, LRP1 distributes into lipid rafts and non-raft plasma membrane fractions. When lipid rafts were disrupted, using methyl-β-cyclodextrin or fumonisin B1, activation of Src family kinases and ERK1/2 by the LRP1 ligands, tissue-type plasminogen activator and activated α2-macroglobulin, was blocked. Biological consequences of activated LRP1 signaling, including neurite outgrowth and cell growth, also were blocked. The effects of lipid raft disruption on ERK1/2 activation and neurite outgrowth, in response to LRP1 ligands, were reproduced in experiments with cerebellar granule neurons in primary culture. Because the reagents used to disrupt lipid rafts may have effects on the composition of the plasma membrane outside lipid rafts, we studied the effects of these reagents on LRP1 activities unrelated to cell-signaling. Lipid raft disruption did not affect the total ligand binding capacity of LRP1, the affinity of LRP1 for its ligands, or its endocytic activity. These results demonstrate that well described activities of LRP1 require localization of this receptor to distinct plasma membrane microdomains.
authors: Department of Pathology, University of California San Diego, La Jolla, CA, USA; Institute of Pharmacology, Catholic University Medical School, Rome, Italy.
authors: Emilia
authors: E
authors: Laudati
authors: Department of Pathology, University of California San Diego, La Jolla, CA, USA.
authors: Andrew S
authors: AS
authors: Gilder
authors: Department of Pathology, University of California San Diego, La Jolla, CA, USA.
authors: Michael S
authors: MS
authors: Lam
authors: Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy.
authors: Roberta
authors: R
authors: Misasi
authors: Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy.
authors: Maurizio
authors: M
authors: Sorice
authors: Department of Pathology, University of California San Diego, La Jolla, CA, USA.
authors: Steven L
authors: SL
authors: Gonias
authors: Department of Pathology, University of California San Diego, La Jolla, CA, USA; Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy. Electronic address: emantuano@ucsd.edu.
authors: Elisabetta
authors: E
authors: Mantuano
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004705:Endocytosis; D037341:Fumonisins / Q000494:pharmacology; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000378:metabolism*; D021962:Membrane Microdomains / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D016716:PC12 Cells; D051381:Rats; D017207:Rats, Sprague-Dawley; D010959:Tissue Plasminogen Activator / Q000378:metabolism; D047392:beta-Cyclodextrins / Q000494:pharmacology; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D037341:Fumonisins; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C056933:fumonisin B1; D019061:src-Family Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D010959:Tissue Plasminogen Activator
keywords: Cell signaling; Endocytosis; LDL Receptor-related Protein-1 (LRP1); Lipid rafts; Neurite outgrowth; Plasma membrane; Tissue plasminogen activator (tPA)