title: Novel reciprocal regulation of cAMP signaling and apoptosis by orphan G-protein-coupled receptor GPRC5A gene expression.
abstract: GPRC5A is a member of G-protein-coupled receptors, which was originally identified as an all-trans-retinoic acid-induced gene. Although recent studies reported that this gene was highly expressed in the cancer cell lines and that GPRC5A might positively regulate cell proliferation, its mechanism remains unknown. We investigated the upstream and downstream signaling of GPRC5A and its biological function, and found that cAMP signaling is the novel GPRC5A induction pathway. When GPRC5A gene was overexpressed, intracellular cAMP concentration was decreased, and Gsalpha gene expression was downregulated. On the other hand, RNA interference of GPRC5A increased mRNA levels of Gsalpha and intracellular cAMP, reduced cell number, and induced apoptosis. Conversely, cell number was increased by GPRC5A overexpression. We first report the novel negative feedback model of cAMP signaling through GPRC5A gene expression. This evidence explains one of the mechanisms of the GPRC5A-regulated cell growth in some cancer cell lines.
authors.affiliation: Department of Molecular and Cellular Pharmacology, Pharmacogenomics and Pharmacoinformatics, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu Mei 514-8507, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Hirano
authors.forename: Liqing
authors.initials: L
authors.lastname: Zang
authors.forename: Takehiko
authors.initials: T
authors.lastname: Oka
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ito
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Shimada
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Toshio
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D017209:Apoptosis / Q000502:physiology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: C116760:GPRC5A protein, human; D043562:Receptors, G-Protein-Coupled; D000242:Cyclic AMP