scholarly journals The Human Herpesvirus 6 G Protein-Coupled Receptor Homolog U51 Positively Regulates Virus Replication and Enhances Cell-Cell Fusion In Vitro

2005 ◽  
Vol 79 (18) ◽  
pp. 11914-11924 ◽  
Author(s):  
Zhu Zhen ◽  
Birgit Bradel-Tretheway ◽  
Sarah Sumagin ◽  
Jean M. Bidlack ◽  
Stephen Dewhurst
Keyword(s):  
Viral Replication ◽  
G Protein ◽  
Cell Fusion ◽  
Virus Replication ◽  
Human Herpesvirus ◽  
Human Herpesvirus 6 ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled ◽  
Cell Cell

ABSTRACT Human herpesvirus 6 (HHV-6) is a ubiquitous T-lymphotropic betaherpesvirus that encodes two G protein-coupled receptor homologs, U12 and U51. HHV-6A U51 has been reported to bind to CC chemokines including RANTES, but the biological function of U51 remains uncertain. In this report, we stably expressed short interfering RNAs (siRNAs) specific for U51 in human T cells and then infected these cells with HHV-6. Viral DNA replication was reduced 50-fold by the U51 siRNA, and virally induced cytopathic effects were also inhibited. In contrast, viral replication and syncytium formation were unaltered in cells that expressed a scrambled derivative of the siRNA or an irrelevant siRNA and were restored to normal when a human codon-optimized derivative of U51 was introduced into cells containing the U51 siRNA. To examine the mechanism whereby U51 might contribute to viral replication, we explored the signaling characteristics of U51. None of the chemokines and opioids tested was able to induce G protein coupling by U51, and no evidence for opioid ligand binding by U51 was obtained. The effect of U51 on cell-cell fusion was also evaluated; these studies showed that U51 enhanced cell fusion mediated by the G protein of vesicular stomatitis virus. However, a U51-specific antiserum had no virus-neutralizing activity, suggesting that U51 may not be involved in the initial interaction between the virus particle and host cell. Overall, these studies suggest that HHV-6 U51 is a positive regulator of virus replication in vitro, perhaps because it may promote membrane fusion and facilitates cell-cell spread of this highly cell-associated virus.

G protein-coupled receptor 17 restricts rabies virus replication via BAK-mediated apoptosis

2021 ◽  
pp. 109326
Author(s):  
Wei Liu ◽  
Yaping Yang ◽  
Zonghui Zeng ◽  
Yuling Tian ◽  
Qiong Wu ◽  
...  
Keyword(s):  
G Protein ◽  
Rabies Virus ◽  
Virus Replication ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled

scholarly journals Vascular Abnormalities in Mice Deficient for the G Protein-Coupled Receptor GPR4 That Functions as a pH Sensor

2006 ◽  
Vol 27 (4) ◽  
pp. 1334-1347 ◽  
Author(s):  
Li V. Yang ◽  
Caius G. Radu ◽  
Meenakshi Roy ◽  
Sunyoung Lee ◽  
Jami McLaughlin ◽  
...  
Keyword(s):  
G Protein ◽  
Mesangial Cells ◽  
Ex Vivo ◽  
Extracellular Ph ◽  
Ph Sensing ◽  
G Protein Coupled Receptor ◽  
Vascular Abnormalities ◽  
G Protein Coupled

ABSTRACT GPR4 is a G protein-coupled receptor expressed in the vasculature, lung, kidney, and other tissues. In vitro ectopic overexpression studies implicated GPR4 in sensing extracellular pH changes leading to cyclic AMP (cAMP) production. To investigate its biological roles in vivo, we generated GPR4-deficient mice by homologous recombination. Whereas GPR4-null adult mice appeared phenotypically normal, neonates showed a higher frequency of perinatal mortality. The average litter size from GPR4−/− intercrosses was ∼30% smaller than that from GPR4+/+ intercrosses on N3 and N5 C57BL/6 genetic backgrounds. A fraction of knockout embryos and neonates had spontaneous hemorrhages, dilated and tortuous subcutaneous blood vessels, and defective vascular smooth muscle cell coverage. Mesangial cells in kidney glomeruli were also significantly reduced in GPR4-null neonates. Some neonates exhibited respiratory distress with airway lining cell metaplasia. To examine whether GPR4 is functionally involved in vascular pH sensing, an ex vivo aortic ring assay was used under defined pH conditions. Compared to wild-type aortas, microvessel outgrowth from GPR4-null aortas was less inhibited by acidic extracellular pH. Treatment with an analog of cAMP, a downstream effector of GPR4, abolished microvessel outgrowth bypassing the GPR4-knockout phenotype. These results suggest that GPR4 deficiency leads to partially penetrant vascular abnormalities during development and that this receptor functions in blood vessel pH sensing.

scholarly journals Deficiency of Proton-Sensing Ovarian Cancer G Protein-Coupled Receptor 1 Attenuates Glucose-Stimulated Insulin Secretion

Endocrinology ◽  
2012 ◽  
Vol 153 (9) ◽  
pp. 4171-4180 ◽  
Author(s):  
Takashi Nakakura ◽  
Chihiro Mogi ◽  
Masayuki Tobo ◽  
Hideaki Tomura ◽  
Koichi Sato ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Insulin Secretion ◽  
G Protein ◽  
Normal Glucose Tolerance ◽  
Extracellular Ph ◽  
G Protein Coupled Receptor ◽  
Glucose Stimulated Insulin Secretion ◽  
G Protein Coupled

Ovarian cancer G protein-coupled receptor 1 (OGR1) has been shown as a receptor for protons. In the present study, we aimed to know whether OGR1 plays a role in insulin secretion and, if so, the manner in which it does. To this end, we created OGR1-deficient mice and examined insulin secretion activity in vivo and in vitro. OGR1 deficiency reduced insulin secretion induced by glucose administered ip, although it was not associated with glucose intolerance in vivo. Increased insulin sensitivity and reduced plasma glucagon level may explain, in part, the unusual normal glucose tolerance. In vitro islet experiments revealed that glucose-stimulated insulin secretion was dependent on extracellular pH and sensitive to OGR1; insulin secretion at pH 7.4 to 7.0, but not 8.0, was significantly suppressed by OGR1 deficiency and inhibition of Gq/11 proteins. Insulin secretion induced by KCl and tolbutamide was also significantly inhibited, whereas that induced by several insulin secretagogues, including vasopressin, a glucagon-like peptide 1 receptor agonist, and forskolin, was not suppressed by OGR1 deficiency. The inhibition of insulin secretion was associated with the reduction of glucose-induced increase in intracellular Ca2+ concentration. In conclusion, the OGR1/Gq/11 protein pathway is activated by extracellular protons existing under the physiological extracellular pH of 7.4 and further stimulated by acidification, resulting in the enhancement of insulin secretion in response to high glucose concentrations and KCl.

scholarly journals High-Throughput Fluorescence Polarization Assay to Identify Ligands Using Purified G Protein-Coupled Receptor

2019 ◽  
Vol 24 (9) ◽  
pp. 915-927
Author(s):  
P. Heine ◽  
G. Witt ◽  
A. Gilardi ◽  
P. Gribbon ◽  
L. Kummer ◽  
...  
Keyword(s):  
G Protein ◽  
High Throughput ◽  
Fluorescence Polarization ◽  
Binding Pocket ◽  
G Protein Coupled Receptor ◽  
Library Screen ◽  
A Cell ◽  
Fluorescence Polarization Assay ◽  
G Protein Coupled

The development of cell-free high-throughput (HT) methods to screen and select novel lead compounds remains one of the key challenges in G protein-coupled receptor (GPCR) drug discovery. Mutational approaches have allowed the stabilization of GPCRs in a purified and ligand-free state. The increased intramolecular stability overcomes two major drawbacks for usage in in vitro screening, the low receptor density on cells and the low stability in micelles. Here, an HT fluorescence polarization (FP) assay for the neurotensin receptor type 1 (NTS1) was developed. The assay operates in a 384-well format and is tolerant to DMSO. From a library screen of 1272 compounds, 12 (~1%) were identified as primary hits. These compounds were validated in orthogonal assay formats using surface plasmon resonance (SPR), which confirmed binding of seven compounds (0.6%). One of these compounds showed a clear preference for the orthosteric binding pocket with submicromolar affinity. A second compound revealed binding at a nonorthosteric binding region and showed specific biological activity on NTS1-expressing cells. A search of analogs led to further enhancement of affinity, but at the expense of activity. The identification of GPCR ligands in a cell-free assay should allow the expansion of GPCR pharmaceuticals with antagonistic or agonistic activity.

Human herpesvirus KSHV encodes a constitutively active G-protein-coupled receptor linked to cell proliferation

Nature ◽  
1997 ◽  
Vol 385 (6614) ◽  
pp. 347-350 ◽  
Author(s):  
Leandros Arvanitakis ◽  
Elizabeth Geras-Raaka ◽  
Anjali Varma ◽  
Marvin C. Gershengorn ◽  
Ethel Cesarman
Keyword(s):  
Cell Proliferation ◽  
G Protein ◽  
Human Herpesvirus ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled ◽  
Constitutively Active

scholarly journals The Kaposi's Sarcoma-Associated Herpesvirus G Protein-Coupled Receptor Has Broad Signaling Effects in Primary Effusion Lymphoma Cells

2003 ◽  
Vol 77 (1) ◽  
pp. 57-67 ◽  
Author(s):  
Mark Cannon ◽  
Nicola J. Philpott ◽  
Ethel Cesarman
Keyword(s):  
G Protein ◽  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Cell Cycle Control ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
G Protein Coupled Receptor ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus ◽  
G Protein Coupled

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV/human herpesvirus 8 [HHV-8]) is a gamma-2-herpesvirus responsible for Kaposi's sarcoma as well as primary effusion lymphoma (PEL). KSHV is a lymphotropic virus that has pirated many mammalian genes involved in inflammation, cell cycle control, and angiogenesis. Among these is the early lytic viral G protein-coupled receptor (vGPCR), a homologue of the human interleukin-8 (IL-8) receptor. When expressed, vGPCR is constitutively active and can signal via mitogen- and stress-activated kinases. In certain models it activates the transcriptional potential of NF-κB and activator protein 1 (AP-1) and induces vascular endothelial growth factor (VEGF) production. Despite its importance to the pathogenesis of all KSHV-mediated disease, little is known about vGPCR activity in hematopoietic cells. To study the signaling potential and downstream effects of vGPCR in such cells, we have developed PEL cell lines that express vGPCR under the control of an inducible promoter. The sequences required for tetracycline-mediated induction were cloned into a plasmid containing adeno-associated virus type 2 elements to enhance integration efficiency. This novel plasmid permitted studies of vGPCR activity in naturally infected KSHV-positive lymphocytes. We show that vGPCR activates ERK-2 and p38 in PEL cells. In addition, it increases the transcription of reporter genes under the control of AP-1, NF-κB, CREB, and NFAT, a Ca2+-dependent transcription factor important to KSHV lytic gene expression. vGPCR also increases the transcription of KSHV open reading frames 50 and 57, thereby displaying broad potential to affect viral transcription patterns. Finally, vGPCR signaling results in increased PEL cell elaboration of KSHV vIL-6 and VEGF, two growth factors involved in KSHV-mediated disease pathogenesis.

scholarly journals Identification of the first surrogate agonists for the G protein-coupled receptor GPR132

RSC Advances ◽  
2015 ◽  
Vol 5 (60) ◽  
pp. 48551-48557 ◽  
Author(s):  
Mohamed A. Shehata ◽  
Hanna Belcik Christensen ◽  
Vignir Isberg ◽  
Daniel Sejer Pedersen ◽  
Andreas Bender ◽  
...  
Keyword(s):  
G Protein ◽  
Binding Mode ◽  
Orphan Receptor ◽  
G Protein Coupled Receptor ◽  
Structure Activity Relationships ◽  
Structure Activity ◽  
G Protein Coupled

We report the first pharmacological tool agonist for in vitro characterization of the orphan receptor GPR132, preliminary structure–activity relationships based on 32 analogs and a suggested binding mode from docking.

scholarly journals G-protein-coupled-receptor kinases mediate TNFα-induced NF-κB signalling via direct interaction with and phosphorylation of IκBα

2009 ◽  
Vol 425 (1) ◽  
pp. 169-180 ◽  
Author(s):  
Sonika Patial ◽  
Jiansong Luo ◽  
Katie J. Porter ◽  
Jeffrey L. Benovic ◽  
Narayanan Parameswaran
Keyword(s):  
G Protein ◽  
Direct Interaction ◽  
Signalling Pathway ◽  
Raw 264.7 ◽  
G Protein Coupled Receptor ◽  
Raw 264.7 Macrophages ◽  
Iκb Kinase ◽  
Receptor Kinases ◽  
G Protein Coupled

TNFα (tumour necrosis factor α) is a multifunctional cytokine involved in the pathophysiology of many chronic inflammatory diseases. TNFα activation of the NF-κB (nuclear factor κB) signalling pathway particularly in macrophages has been implicated in many diseases. We demonstrate in the present study that GRK2 and GRK5 (G-protein-coupled-receptor kinases 2 and 5) regulate TNFα-induced NF-κB signalling in Raw 264.7 macrophages. RNAi (RNA interference) knockdown of GRK2 or GRK5 in macrophages significantly inhibited TNFα-induced IκBα (inhibitory κBα) phosphorylation and degradation, NF-κB activation and expression of the NF-κB-regulated gene MIP1β (macrophage inflammatory protein 1β). Consistent with these results, overexpression of GRK2 or GRK5 enhanced TNFα-induced NF-κB activity. In addition, we show that GRK2 and GRK5 interacted with IκBα via the N-terminal domain of IκBα and that IκBα is a substrate for GRK2 and GRK5 in vitro. Furthermore, we also found that GRK5, but not GRK2, phosphorylated IκBα at the same amino acid residues (Ser32/Ser36) as that of IKKβ (IκB kinase β). Interestingly, associated with these results, knockdown of IKKβ in Raw 264.7 macrophages did not affect TNFα-induced IκBα phosphorylation. Taken together, these results demonstrate that both GRK2 and GRK5 are important and novel mediators of a non-traditional IκBα/NF-κB signalling pathway.

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