title: Low density lipoprotein receptor-related protein 1 (LRP1) controls endocytosis and c-CBL-mediated ubiquitination of the platelet-derived growth factor receptor beta (PDGFR beta).
abstract: The low density lipoprotein receptor-related protein 1 (LRP1) has been implicated in intracellular signaling functions as well as in lipid metabolism. Recent in vivo and in vitro studies suggest that LRP1 is a physiological modulator of the platelet-derived growth factor (PDGF) signaling pathway. Here we show that in mouse fibroblasts LRP1 modulates PDGF-BB signaling by controlling endocytosis and ligand-induced down-regulation of the PDGF receptor beta (PDGFRbeta). In LRP1-deficient fibroblasts, basal PDGFRbeta tyrosine kinase activity was derepressed, and PDGF-BB-induced endocytosis and degradation of PDGFRbeta were accelerated as compared with control cells. This was accompanied by rapid uptake of receptor-bound PDGF-BB into the cells and by attenuated ERK activation in response to PDGF-BB stimulation. Pulse-chase analysis indicated that the steady-state turnover rate of PDGFRbeta was also accelerated in LRP-deficient fibroblasts. The rapid degradation of PDGFRbeta in the LRP1-deficient fibroblasts was prevented by MG132 and chloroquine. Furthermore, the association of PDGFRbeta with c-Cbl, a ubiquitin E3-ligase, as well as the ligand-induced ubiquitination of PDGFRbeta were increased in LRP1-deficient fibroblasts. We show that LRP1 can directly interact with c-Cbl, suggesting a Sprouty-like role for LRP1 in regulating the access of the PDGFRbeta to the ubiquitination machinery. Thus, LRP1 modulates PDGF signaling by controlling ubiquitination and endocytosis of the PDGFRbeta.
authors.affiliation: Departments of Molecular Genetics and Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9046, USA.
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Takayama
authors.forename: Petra
authors.initials: P
authors.lastname: May
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; D002460:Cell Line; D004705:Endocytosis / Q000502:physiology*; D005347:Fibroblasts / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051379:Mice; D010982:Platelet-Derived Growth Factor / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D050721:Proto-Oncogene Proteins c-cbl; D020574:Proto-Oncogene Proteins c-sis; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000502:physiology*
chemical_list: D026503:Low Density Lipoprotein Receptor-Related Protein-1; D010982:Platelet-Derived Growth Factor; D011518:Proto-Oncogene Proteins; D020574:Proto-Oncogene Proteins c-sis; D025801:Ubiquitin; D000077214:Becaplermin; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D020797:Receptor, Platelet-Derived Growth Factor beta; C493849:Cbl protein, mouse