title: The hepatocarcinoma cell line HepG2 does not express a GHS-R1a-type ghrelin receptor.
abstract: The interaction of ghrelin, a 28-residue acylated peptide, with the growth hormone secretagogue receptor 1a (GHS-R1a) has been studied mostly in cells expressing a recombinant GHS-R1a. As awareness is growing on the importance to study G protein-coupled receptors in a natural environment, we studied the effect of ghrelin in the human hepatocellular HepG2 cell line because it has been described in literature to respond to ghrelin. Despite extensive efforts, we were not able to confirm mRNA expression of GHS-R1a by reverse transcription PCR, radioligand binding, or ghrelin-induced GHS-R1a receptor activation; therefore, we conclude that HepG2 cells do not express GHS-R1a. On the other hand, we confirmed a modest effect of ghrelin on the up-regulation of IRS-1 phosphorylation, which might suggest the existence of an alternative ghrelin receptor in HepG2 cells.
authors: Department of Internal Medicine, Johnson & Johnson Pharmaceutical Research & Development, a division of Janssen Pharmaceutica NV, Beerse, Belgium.
authors: Leen
authors: L
authors: Thielemans
authors: Pieter J
authors: PJ
authors: Peeters
authors: Heidi
authors: H
authors: Jonckheere
authors: Walter
authors: W
authors: Luyten
authors: Ronald
authors: R
authors: de Hoogt
authors: Bernard
authors: B
authors: Coulie
authors: Jeroen
authors: J
authors: Aerssens
mesh_terms: D002118:Calcium / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D005456:Fluorescent Dyes / Q000494:pharmacology; D054439:Ghrelin; D006801:Humans; D055504:Insulin Receptor Substrate Proteins; D008113:Liver Neoplasms / Q000473:pathology*; D036361:Peptide Hormones / Q000737:chemistry / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D054440:Receptors, Ghrelin; D015854:Up-Regulation
chemical_list: D005456:Fluorescent Dyes; D054439:Ghrelin; C526292:IRS1 protein, human; D055504:Insulin Receptor Substrate Proteins; D036361:Peptide Hormones; D010750:Phosphoproteins; D043562:Receptors, G-Protein-Coupled; D054440:Receptors, Ghrelin; D002118:Calcium