title: GRK2 targeted knock-down results in spontaneous hypertension, and altered vascular GPCR signaling.
abstract: Hypertension, elevated arterial pressure, occurs as the consequence of increased peripheral resistance. G protein-coupled receptors (GPCRs) contribute to the regulation of vasodilator and vasoconstrictor responses, and their activity is regulated by a family of GPCR kinases (GRKs). GRK2 expression is increased in hypertension and this facilitates the development of the hypertensive state by increasing the desensitization of GPCRs important for vasodilation. We demonstrate here, that genetic knockdown of GRK2 using a small hairpin (sh) RNA results in altered vascular reactivity and the development of hypertension between 8-12 weeks of age in shGRK2 mice due to enhanced Gαq/11 signaling. Vascular smooth muscle cells (VSMCs) cultured from shGRK2 knockdown mice show increases in GPCR-mediated Gαs and Gαq/11 signaling, as the consequence of reduced GRK2-mediated desensitization. In addition, agonists and biased agonists exhibited age-dependent alterations in ERK1/2 and Akt signaling, as well as cell proliferation and migration responses in shGRK2 knockdown VSMCs when cultured from mice that are either 3 months or 6 months of age. Changes in angiotensin II-stimulated ERK1/2 phosphorylation are observed in VSMCs derived from 6-week-old shGRK2 mice prior to the development of the hypertensive phenotype. Thus, our findings indicate that the balance between mechanisms regulating vascular tone are shifted to favor vasoconstriction in the absence of GRK2 expression and that this leads to the age-dependent development of hypertension, as a consequence of global alterations in GPCR signaling. Consequently, therapeutic strategies that target GRK2 activity, not expression, may be more effective for the treatment of hypertension.
authors.affiliation: From the J. Allyn Taylor Centre for Cell Biology,; Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5K8, Canada.
authors.forename: Elena
authors.initials: E
authors.lastname: Tutunea-Fatan
authors.affiliation: From the J. Allyn Taylor Centre for Cell Biology.
authors.forename: Fabiana A
authors.initials: FA
authors.lastname: Caetano
authors.affiliation: From the J. Allyn Taylor Centre for Cell Biology,; Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5K8, Canada; Vascular Biology Group, Robarts Research Institute, and; Departments of Medicine,. Electronic address: rgros@robarts.ca.
authors.forename: Robert
authors.initials: R
authors.lastname: Gros
authors.affiliation: From the J. Allyn Taylor Centre for Cell Biology,; Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5K8, Canada. Electronic address: ferguson@robarts.ca.
authors.forename: Stephen S G
authors.initials: SSG
authors.lastname: Ferguson
mesh_terms: D000804:Angiotensin II / Q000235:genetics / Q000378:metabolism; D000818:Animals; D054769:G-Protein-Coupled Receptor Kinase 2 / Q000172:deficiency*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D055785:Gene Knockdown Techniques; D006973:Hypertension / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020935:MAP Kinase Signaling System; D051379:Mice; D018345:Mice, Knockout; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism
chemical_list: D000804:Angiotensin II; D051057:Proto-Oncogene Proteins c-akt; C496568:GRK2 protein, mouse; D054769:G-Protein-Coupled Receptor Kinase 2; D048052:Mitogen-Activated Protein Kinase 3; D043802:GTP-Binding Protein alpha Subunits, Gq-G11
keywords: G protein; G protein-coupled receptor (GPCR); GRK2; adrenergic receptor; angiotensin II; animal model