title: G-protein-coupled receptor screen reveals a role for chemokine receptor CCR5 in suppressing microglial neurotoxicity.
abstract: G-protein-coupled receptors (GPCRs) form the largest superfamily of membrane proteins, and several GPCRs have been implicated in signaling between neurons and glia to protect neurons from pathological stresses. Here, we have used a screening strategy to investigate GPCRs that are involved in neuronal protection. The real-time PCR was performed using 274 primers targeting nonsensory GPCR mRNAs, which were listed on the database. The cDNAs from control and nerve-injured hypoglossal nuclei of mouse brain were used, and the alterations of PCR products were compared. This screen and the subsequent in situ hybridization screen exhibited six GPCR mRNAs which were prominently and convincingly induced in nerve-injured hypoglossal nuclei. Among these candidates, the chemokine receptor CCR5 was selected, based on the marked induction in CCR5 mRNA in microglia after nerve injury. The mRNA expression of ligands for CCR5, such as regulated on activation normal T-cell expressed and secreted (RANTES/CCL5), MIP-1alpha, and MIP-1beta, were induced in injured motor neurons, indicating that CCR5 and its ligands were expressed in microglia and neurons, respectively, in response to nerve injury. In vitro, lipopolysaccharide (LPS)-induced expression of mRNAs for inflammatory cytokines (IL-1beta, IL-6, and tumor necrosis factor-alpha) and inducible nitric oxide synthase (iNOS) in microglia were all suppressed by RANTES. Those suppressions were not observed in microglia from CCR5 null mice. In addition, nerve injury-induced motor neuron death seen in wild type C56BL/6J mice was accelerated in CCR5 knock-out C57BL/6J. These results may suggest that CCR5-mediated neuron-glia signaling functions to protect neurons by suppressing microglia toxicity.
authors.affiliation: Department of Anatomy and Neurobiology, Osaka City University, Graduate School of Medicine, Abeno-ku, Osaka 545-8585, Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Gamo
authors.forename: Sumiko
authors.initials: S
authors.lastname: Kiryu-Seo
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Konishi
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Aoki
authors.forename: Kouji
authors.initials: K
authors.lastname: Matsushima
authors.forename: Keiji
authors.initials: K
authors.lastname: Wada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kiyama
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000235:genetics / Q000276:immunology; D016923:Cell Death / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D054405:Chemokine CCL3 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D054407:Chemokine CCL4 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D018946:Chemokine CCL5 / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D005820:Genetic Testing; D061228:Hypoglossal Nerve Injuries; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017628:Microglia / Q000276:immunology / Q000378:metabolism*; D009046:Motor Neurons / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D009498:Neurotoxins / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D019713:Receptors, CCR5 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D012183:Retrograde Degeneration / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology
chemical_list: C496534:Ccl3 protein, mouse; C503460:Ccl5 protein, mouse; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D018946:Chemokine CCL5; D016207:Cytokines; D009498:Neurotoxins; D012333:RNA, Messenger; D019713:Receptors, CCR5; D043562:Receptors, G-Protein-Coupled; D052247:Nitric Oxide Synthase Type II