title: Carboxyl terminus-truncated α1D-adrenoceptors inhibit the ERK pathway.
abstract: Human α1D-adrenoceptors are G protein-coupled receptors that mediate adrenaline/noradrenaline actions. There is a growing interest in identifying regulatory domains in these receptors and determining how they function. In this work, we show that the absence of the human α1D-adrenoceptor carboxyl tail results in altered ERK (extracellular signal-regulated kinase) and p38 phosphorylation states. Amino terminus-truncated and both amino and carboxyl termini-truncated α1D-adrenoceptors were transfected into Rat-1, HEK293, and B103 cells, and changes in the phosphorylation state of extracellular signal-regulated kinase was assessed using biochemical and biophysical approaches. The phosphorylation state of other protein kinases (p38, MEK1, and Raf-1) was also studied. Noradrenaline-induced ERK phosphorylation in Rat-1 fibroblasts expressing amino termini-truncated α1D-adrenoceptors. However, in cells expressing receptors with both amino and carboxyl termini truncations, noradrenaline-induced activation was abrogated. Interestingly, ERK phosphorylation that normally occurs through activation of endogenous G protein-coupled receptors, EGF receptors, and protein kinase C, was also decreased, suggesting that downstream steps in the mitogen-activated protein kinase pathway were affected. A similar effect was observed in B103 cells but not in HEK 293 cells. Phosphorylation of Raf-1 and MEK1 was also diminished in Rat-1 fibroblasts expressing amino- and carboxyl-truncated α1D-adrenoceptors. Our data indicate that expression of carboxyl terminus-truncated α1D-adrenoceptors alters ERK and p38 phosphorylation state.
authors.affiliation: Instituto de Fisiología Celular, UNAM, Universidad Nacional Autónoma de México, Apartado Postal 70-248, 04510, Mexico D. F, Mexico.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Alfonzo-Méndez
authors.affiliation: Instituto de Fisiología Celular, UNAM, Universidad Nacional Autónoma de México, Apartado Postal 70-248, 04510, Mexico D. F, Mexico.
authors.forename: Jean A
authors.initials: JA
authors.lastname: Castillo-Badillo
authors.affiliation: Instituto de Fisiología Celular, UNAM, Universidad Nacional Autónoma de México, Apartado Postal 70-248, 04510, Mexico D. F, Mexico.
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Romero-Ávila
authors.affiliation: Department of Molecular and Cellular Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, 92037, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Rivera
authors.affiliation: Department of Molecular and Cellular Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, 92037, USA.
authors.forename: Jerold
authors.initials: J
authors.lastname: Chun
authors.affiliation: Instituto de Fisiología Celular, UNAM, Universidad Nacional Autónoma de México, Apartado Postal 70-248, 04510, Mexico D. F, Mexico. agarcia@ifc.unam.mx.
authors.forename: J Adolfo
authors.initials: JA
authors.lastname: García-Sáinz
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases; D057809:HEK293 Cells; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D000072417:Protein Domains; D011493:Protein Kinase C / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C547719:ADRA1D protein, human; D000316:Adrenergic alpha-Agonists; D018340:Receptors, Adrenergic, alpha-1; D066246:ErbB Receptors; D019908:Proto-Oncogene Proteins c-raf; C546782:Raf1 protein, rat; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1
keywords: Carboxyl tail; Desensitization; ERK phosphorylation; GPCR; α1-adrenoceptors