title: G protein-coupled receptors desensitize and down-regulate epidermal growth factor receptors in renal mesangial cells.
abstract: Different types of plasma membrane receptors engage in various forms of cross-talk. We used cultures of rat renal mesangial cells to study the regulation of EGF receptors (EGFRs) by various endogenous G protein-coupled receptors (GPCRs). GPCRs (5-hydroxytryptamine(2A), lysophosphatidic acid, angiotensin AT(1), bradykinin B(2)) were shown to transactivate EGFRs through a protein kinase C-dependent pathway. This transactivation resulted in the initiation of multiple cellular signals (phosphorylation of the EGFRs and ERK and activation of cAMP-responsive element-binding protein (CREB), NF-kappaB, and E2F), as well as subsequent rapid down-regulation of cell-surface EGFRs and internalization and desensitization of the EGFRs without change in the total cellular complement of EGFRs. Internalization of the EGFRs and the down-regulation of cell-surface receptors in mesangial cells were blocked by pharmacological inhibitors of clathrin-mediated endocytosis and in HEK293 cells by transfection of cDNA constructs that encode dominant negative beta-arrestin-1 or dynamin. Whereas all of the effects of GPCRs on EGFRs were dependent to a great extent on protein kinase C, those initiated by EGF were not. These studies demonstrate that GPCRs can induce multiple signals through protein kinase C-dependent transactivation of EGFRs. Moreover, GPCRs induce profound desensitization of EGFRs by a process associated with the loss of cell-surface EGFRs through clathrin-mediated endocytosis.
authors.affiliation: Nephrology Division, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Grewal
authors.forename: L M
authors.initials: LM
authors.lastname: Luttrell
authors.forename: J R
authors.initials: JR
authors.lastname: Raymond
mesh_terms: D000818:Animals; D015536:Down-Regulation; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005920:Glomerular Mesangium / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D066246:ErbB Receptors; D019204:GTP-Binding Proteins