title: Constitutive coupling of a naturally occurring human alpha1a-adrenergic receptor genetic variant to EGFR transactivation pathway.
abstract: We previously identified a naturally occurring human SNP, G247R, in the third intracellular loop of the α(1a)-adrenergic receptor (α(1a)-247R) and demonstrated that constitutive expression of α(1a)-247R results in twofold increased cell proliferation compared with WT. In the present study we elucidate molecular mechanisms and signal transduction pathways responsible for increased cell proliferation unique to α(1a)-247R, but not α(1a)-WT, α(1b), or α(1d)AR subtypes. We show that elevated levels of matrix metalloproteinase-7 (MMP7) and a disintegrin and metalloproteinase-12 (ADAM12) in α(1a)-247R-expressing cells are responsible for EGF receptor (EGFR) transactivation, downstream ERK activation, and increased cell proliferation; this pathway is confirmed using MMP, EGFR, and ERK inhibitors. We demonstrate that EGFR transactivation and downstream ERK activation depends on increased shedding of heparin-binding EGF. Finally, we demonstrate that knockdown of MMP7 or β-arrestin1 by shRNAs results in attenuation of proliferation of cells expressing α(1a)-247R. Importantly, accelerated cell proliferation triggered by the α(1a)-247R is serum- and agonist-independent, providing unique evidence for constitutive active coupling to the β-arrestin1/MMP/EGFR transactivation pathway by any G protein-coupled receptor. These findings raise the possibility of a previously unexplored mechanism for sympathetically mediated human hypertension triggered by a naturally occurring human genetic variant.
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98109, USA. anush@u.washington.edu
authors.forename: Anush
authors.initials: A
authors.lastname: Oganesian
authors.forename: Vladimir
authors.initials: V
authors.lastname: Yarov-Yarovoy
authors.forename: William C
authors.initials: WC
authors.lastname: Parks
authors.forename: Debra A
authors.initials: DA
authors.lastname: Schwinn
mesh_terms: D051722:ADAM Proteins / Q000235:genetics / Q000378:metabolism; D000072199:ADAM12 Protein; D019943:Amino Acid Substitution; D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004151:Dipeptides / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D020783:Matrix Metalloproteinase 7 / Q000235:genetics / Q000378:metabolism; D061965:Matrix Metalloproteinase Inhibitors; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects; D011799:Quinazolines / Q000494:pharmacology; D034622:RNA Interference; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D015533:Transcriptional Activation; D020032:Tyrphostins / Q000494:pharmacology; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D004151:Dipeptides; D004791:Enzyme Inhibitors; D005419:Flavonoids; D061965:Matrix Metalloproteinase Inhibitors; D008565:Membrane Proteins; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D011799:Quinazolines; D018340:Receptors, Adrenergic, alpha-1; D020032:Tyrphostins; D000071557:beta-Arrestins; C101044:RTKI cpd; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D051722:ADAM Proteins; D000072199:ADAM12 Protein; C000606480:ADAM12 protein, human; D020783:Matrix Metalloproteinase 7; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
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