title: Ligand binding to LRP1 transactivates Trk receptors by a Src family kinase-dependent pathway.
abstract: Low-density lipoprotein receptor-related protein 1 (LRP1) functions in endocytosis and intracellular signaling for a variety of structurally diverse ligands. Although LRP1 has been implicated in several aspects of neuronal function, molecular mechanisms underlying the activity of neuronal LRP1 remain unclear. Here, we describe a signaling pathway whereby LRP1 transactivates Trk receptors. Binding of tissue-type plasminogen activator or alpha(2)-macroglobulin (alpha(2)M) to LRP1 resulted in Src family kinase (SFK) activation and SFK-dependent Trk receptor transactivation in PC12 cells and neurons. Trk receptor transactivation was necessary for activation of Akt and extracellular signal-regulated kinase and for neurite outgrowth downstream of LRP1. Injection of the LRP1-binding domain of alpha(2)M into rat dorsal root ganglia induced Trk receptor phosphorylation, which was blocked by receptor-associated protein, an antagonist of ligand binding to LRP1. Trk receptor transactivation provides a mechanism by which diverse LRP1 ligands may show neurotrophic activity.
authors.affiliation: Department of Pathology, University of California San Diego, La Jolla, CA 92093-0612, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Shi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Mantuano
authors.forename: Gen
authors.initials: G
authors.lastname: Inoue
authors.forename: W Marie
authors.initials: WM
authors.lastname: Campana
authors.forename: Steven L
authors.initials: SL
authors.lastname: Gonias
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002227:Carbazoles / Q000494:pharmacology; D002478:Cells, Cultured; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015151:Immunoblotting; D026121:Indole Alkaloids / Q000494:pharmacology; D008024:Ligands; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D016501:Neurites / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016716:PC12 Cells; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020917:Receptor, trkA / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D000511:alpha-Macroglobulins / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D002227:Carbazoles; D026121:Indole Alkaloids; D008024:Ligands; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D034741:RNA, Small Interfering; D000511:alpha-Macroglobulins; C049985:staurosporine aglycone; D020917:Receptor, trkA; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases