Role of G Protein-coupled Receptor Kinase 5 in Desensitisation of the V1b Vasopressin Receptor in Response to Arginine Vasopressin (2011)
Type of ContentTheses / Dissertations
Degree NameMaster of Science
PublisherUniversity of Canterbury. Biological Sciences
Arginine vasopressin (AVP) is a hypothalamic nonapeptide which regulates the hypothalamic-pituitary-adrenal axis response to stress by stimulating the secretion of adrenocorticotropin (ACTH) from corticotroph cells of the anterior pituitary. This effect is mediated by binding of AVP to the pituitary vasopressin receptor (V1bR). The V1bR belongs to the G protein-coupled receptor (GPCR) super family. Repeated stimulation of anterior pituitary cells with AVP has been shown to produce a loss of responsiveness to subsequent AVP stimulation. This phenomenon appears to be mediated by desensitisation of the V1bR, and may be due to phosphorylation of the receptor by G protein-coupled receptor kinase 5 (GRK5). The aim of this research was to establish and validate methods that would allow the role of GRK5 in the desensitisation of V1bR to AVP stimulation to be investigated. As no isoform specific inhibitors for GRK5 were available, HEK293 cells transiently transfected with the rat V1bR were used as a model system for this research. This allowed RNA interference (RNAi) to be used to knockdown GRK5 expression. The protocol for RNAi-mediated knockdown of GRK5 was established as part of this research. Protocols for Western blotting and qRT-PCR were also established to allow the RNAi-mediated knockdown of GRK5 protein and mRNA to be measured. Transfection of HEK293 cells with 10nM GRK5-targeting small interfering RNAs (siRNAs) reduced the expression of GRK5 protein to 53.4% ± 3.4% (mean ± SEM) of that seen in untreated control cells at 84 hours after transfection, while GRK5 mRNA levels were reduced to 28.7% ± 1.9% (mean ± SEM) of that of control cells 48 hours after transfection.
An experimental protocol was designed in this research that would coordinate the RNAi-mediated knockdown of GRK5 with transient transfection of the HEK293 cells with the rV1bR. Since, activated V1bRs couple to Gq/11 and stimulate the production of inositol phosphates (IPs), the responsiveness of the V1bR can be determined by measuring the accumulation of [H³]-IPs in cells labelled with [H³]-myo-inositol. In the protocol designed, the effect of GRK5 knockdown on V1bR desensitisation is determined by stimulating HEK293 cells expressing the rV1bR (and previously transfected with GRK5-targeting siRNA) with 0nM or 100nM AVP for 0, 5, 15, 30 or 60 minutes, and comparing the accumulation if IPs over time with that of cells that are not transfected with GRK5-targeting siRNA. This protocol can be used in future to investigate the role of GRK5 in V1bR desensitisation, and may be adapted to determine if other GRK isoforms are involved in V1bR desensitisation.
KeywordsArginine Vasopressin; GPCRs; GRK5; RNAi; qRTPCR; Western Blotting; HEK293; Hypothalamic-Pituitary-Adrenal axis; stress
RightsCopyright Katherine van Bysterveldt
Showing items related by title, author, creator and subject.
Desensitisation of the Pituitary Vasopressin Receptor: Development and Use of a Stably-Transfected Model Cell System to Assess the Role of G Protein-Coupled Receptor Kinases Cummings, Siobhan Anne (University of Canterbury. School of Biological Sciences, 2011)Stress impacts upon all organisms and a robust stress response is required for adaptive interactions of the organism with the environment. In most higher organisms, an individual’s response to stress is mediated by the ...
Desensitisation of the pituitary vasopressin receptor : development of a model system to assess involvement of G protein-coupled receptor kinase 5. Gatehouse, Michelle (University of Canterbury. School of Biological Sciences, 2008)The hypothalamic peptide arginine vasopressin (AVP) is an important regulator of adrenocorticotropin (ACTH) release from the anterior pituitary. AVP stimulates ACTH secretion from corticotroph cells by activating the ...
Yen HY; Hopper JTS; Liko I; Allison TM; Zhu Y; Wang D; Stegmann M; Mohammed S; Wu B; Robinson CV (2017)Copyright © 2017 The Authors, some rights reserved. G protein (heterotrimeric guanine nucleotide–binding protein)–coupled receptors belong to the largest family of membrane-embedded cell surface proteins and are involved ...