title: Platelet-derived growth factor mediates tyrosine phosphorylation of the cytoplasmic domain of the low Density lipoprotein receptor-related protein in caveolae.
abstract: The low density lipoprotein (LDL) receptor gene family represents a class of multifunctional, endocytic cell surface receptors. Recently, roles in cellular signaling have also emerged. For instance, the very low density lipoprotein receptor (VLDLR) and the apolipoprotein receptor-2 (apoER2) function in a developmental signaling pathway that regulates the lamination of cortical layers in the brain and involves the activation of tyrosine kinases. Furthermore, the cytoplasmic domain of the LDL receptor-related protein (LRP) was found to be a substrate for the non-receptor tyrosine kinase Src, but the physiological significance of this phosphorylation event remained unknown. Here we show that tyrosine phosphorylation of LRP occurs in caveolae and involves the platelet-derived growth factor (PDGF) receptor beta and phosphoinositide 3-kinase. Receptor-associated protein, an antagonist of ligand binding to LRP, and apoE-enriched beta-VLDL, a ligand for LRP, reduce PDGF-induced tyrosine phosphorylation of the LRP cytoplasmic domain. In the accompanying paper (Loukinova, E., Ranganathan, S., Kuznetsov, S., Gorlatova, N., Migliorini, M., Ulery, P. G., Mikhailenko, I., Lawrence, D. L., and Strickland, D. K. (2002) J. Biol. Chem. 277, 15499-15506) Loukinova et al. further demonstrate that one form of PDGF, PDGF-BB, binds specifically to LRP and that phosphorylation of LRP requires the activation of Src family kinases. Taken together, these findings provide a biochemical basis for a cellular signaling pathway that involves apoE and LRP.
authors.affiliation: Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9046, USA.
authors.forename: Philippe
authors.initials: P
authors.lastname: Boucher
authors.forename: Pingsheng
authors.initials: P
authors.lastname: Liu
authors.forename: Michael
authors.initials: M
authors.lastname: Gotthardt
authors.forename: Thomas
authors.initials: T
authors.lastname: Hiesberger
authors.forename: Richard G W
authors.initials: RG
authors.lastname: Anderson
authors.forename: Joachim
authors.initials: J
authors.lastname: Herz
mesh_terms: D000818:Animals; D000077214:Becaplermin; D021941:Caveolae / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007668:Kidney; D026563:LDL-Receptor Related Protein-Associated Protein / Q000378:metabolism; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000378:metabolism*; D008264:Macrophages; D051379:Mice; D019000:Phosphotyrosine / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D019699:Thrombospondins / Q000378:metabolism; D014162:Transfection
chemical_list: D026563:LDL-Receptor Related Protein-Associated Protein; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D019699:Thrombospondins; D000077214:Becaplermin; D019000:Phosphotyrosine