scholarly journals Sphingosine 1-phosphate receptor 2 antagonist JTE-013 increases the excitability of sensory neurons independently of the receptor

2012 ◽  
Vol 108 (5) ◽  
pp. 1473-1483 ◽  
Author(s):  
Chao Li ◽  
Xian Xuan Chi ◽  
Wenrui Xie ◽  
J. A. Strong ◽  
J.-M. Zhang ◽  
...  
Keyword(s):  
G Protein ◽  
Sensory Neurons ◽  
Neuronal Excitability ◽  
Small Diameter ◽  
G Protein Coupled Receptors ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

Previously we demonstrated that sphingosine 1-phosphate receptor 1 (S1PR1) played a prominent, but not exclusive, role in enhancing the excitability of small-diameter sensory neurons, suggesting that other S1PRs can modulate neuronal excitability. To examine the potential role of S1PR2 in regulating neuronal excitability we used the established selective antagonist of S1PR2, JTE-013. Here we report that exposure to JTE-013 alone produced a significant increase in excitability in a time- and concentration-dependent manner in 70–80% of recorded neurons. Internal perfusion of sensory neurons with guanosine 5′- O-(2-thiodiphosphate) (GDP-β-S) via the recording pipette inhibited the sensitization produced by JTE-013 as well as prostaglandin E2. Pretreatment with pertussis toxin or the selective S1PR1 antagonist W146 blocked the sensitization produced by JTE-013. These results indicate that JTE-013 might act as an agonist at other G protein-coupled receptors. In neurons that were sensitized by JTE-013, single-cell RT-PCR studies demonstrated that these neurons did not express the mRNA for S1PR2. In behavioral studies, injection of JTE-013 into the rat's hindpaw produced a significant increase in the mechanical sensitivity in the ipsilateral, but not contralateral, paw. Injection of JTE-013 did not affect the withdrawal latency to thermal stimulation. Thus JTE-013 augments neuronal excitability independently of S1PR2 by unknown mechanisms that may involve activation of other G protein-coupled receptors such as S1PR1. Clearly, further studies are warranted to establish the causal nature of this increased sensitivity, and future studies of neuronal function using JTE-013 should be interpreted with caution.

Sphingosine-1-Phosphate Via Activation of a G-Protein-Coupled Receptor(s) Enhances the Excitability of Rat Sensory Neurons

2006 ◽  
Vol 96 (3) ◽  
pp. 1042-1052 ◽  
Author(s):  
Y. H. Zhang ◽  
J. C. Fehrenbacher ◽  
M. R. Vasko ◽  
G. D. Nicol
Keyword(s):  
G Protein ◽  
Sensory Neurons ◽  
Small Diameter ◽  
G Protein Coupled Receptors ◽  
External Application ◽  
Nociceptive Neurons ◽  
Firing Threshold ◽  
Current Ramp ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

Sphingosine-1-phosphate (S1P) is released by immune cells and is thought to play a key role in chemotaxis and the onset of the inflammatory response. The question remains whether this lipid mediator also contributes to the enhanced sensitivity of nociceptive neurons that is associated with inflammation. Therefore we examined whether S1P alters the excitability of small diameter, capsaicin-sensitive sensory neurons by measuring action potential (AP) firing and two of the membrane currents critical in regulating the properties of the AP. External application of S1P augments the number of APs evoked by a depolarizing current ramp. The enhanced firing is associated with a decrease in the rheobase and an increase in the resistance at firing threshold although neither the firing threshold nor the resting membrane potential are changed. Treatment with S1P enhanced the tetrodotoxin-resistant sodium current and decreased the total outward potassium current ( IK). When sensory neurons were internally perfused with GDP-β-S, a blocker of G protein activation, the S1P-induced increase in APs was completely blocked and suggests the excitatory actions of S1P are mediated through G-protein-coupled receptors called endothelial differentiation gene or S1PR. In contrast, internal perfusion with GDP-β-S and S1P increased the number of APs evoked by the current ramp. These results and our finding that the mRNAs for S1PRs are expressed in both the intact dorsal root ganglion and cultures of adult sensory neurons supports the notion that S1P acts on S1PRs linked to G proteins. Together these findings demonstrate that S1P can regulate the excitability of small diameter sensory neurons by acting as an external paracrine-type ligand through activation of G-protein-coupled receptors and thus may contribute to the hypersensitivity during inflammation.

scholarly journals The Sphingosine 1-Phosphate Receptor, S1PR1, Plays a Prominent But Not Exclusive Role in Enhancing the Excitability of Sensory Neurons

2010 ◽  
Vol 104 (5) ◽  
pp. 2741-2748 ◽  
Author(s):  
Xian Xuan Chi ◽  
G. D. Nicol
Keyword(s):  
Sensory Neurons ◽  
Small Diameter ◽  
Cell Types ◽  
G Protein Coupled Receptors ◽  
Rt Pcr ◽  
Additional Increase ◽  
Sphingosine 1 Phosphate ◽  
Subsequent Exposure ◽  
G Protein Coupled

Sphingosine 1-phosphate (S1P) through its interaction with a family of G protein–coupled receptors (S1PR) is proving to have a significant impact on the activation of a variety of cell types, most notably those cells mediating the inflammatory response. Previously, we showed that S1P enhanced the excitability of small diameter sensory neurons, and mRNA for S1PR1–4 was expressed in sensory neurons. These initial findings did not determine which S1PR subtype(s) mediated the increased excitability. Here, we report that exposure to the selective S1PR1 agonist, SEW2871, produced a significant increase in excitability of some, but not all, sensory neurons. To further examine the role of S1PR1, neurons were treated with siRNA targeted to S1PR1. siRNA reduced S1PR1 protein expression by 75% and blocked the sensitization produced by SEW2871, although some neurons remained responsive to subsequent exposure to S1P. Treatment with scramble siRNA did not alter S1PR1 expression. Recordings from siRNA- and scramble-treated neurons suggested three distinct populations based on their sensitivities to SEW2871 and S1P. Approximately 50% of the neurons exhibited a significant increase in excitability after exposure to SEW2871 and subsequent S1P produced no additional increase; ∼25% were not affected by SEW2871 but S1P significantly increased excitability; and ∼25% of the neurons were not sensitized by either SEW2871 or S1P. RT-PCR measurements obtained from single neurons showed that 50% of the small diameter neurons expressed the mRNA for S1PR1. These results indicate that S1PR1 plays a prominent, although not exclusive, role in mediating the enhancement of excitability produced by S1P.

scholarly journals Using Ligand-Induced Conformational Change to Screen for Compounds Targeting G-Protein-Coupled Receptors

2007 ◽  
Vol 12 (2) ◽  
pp. 175-185 ◽  
Author(s):  
Brian F. O'Dowd ◽  
Mohammad Alijaniaram ◽  
Xiaodong Ji ◽  
Tuan Nguyen ◽  
Richard M. Eglen ◽  
...  
Keyword(s):  
Cell Surface ◽  
G Protein ◽  
High Throughput Screening ◽  
G Protein Coupled Receptors ◽  
Nuclear Localization Sequence ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
G Protein Coupling ◽  
Protein Coupling ◽  
G Protein Coupled

The authors describe a novel drug strategy designed as a primary screen to discover either antagonist or agonist compounds targeting G-protein-coupled receptors (GPCRs). The incorporation of a nuclear localization sequence (NLS, a 5 amino acid substitution), in a location in helix 8 of the GPCR structure, resulted in ligand-independent receptor translocation from the cell surface to the nucleus. Blockade of the GPCR-NLS translocation from the cell surface was achieved by either antagonist or agonist treatments, each achieving their result in a sensitive concentration-dependent manner. GPCR-NLS translocation and blockade occurred regardless of the identity of the G-protein-coupling, and thus this assay is also ideally suited for identification of compounds targeting orphan GPCRs. The GPCR-NLS trafficking was visualized by fusion to fluorescent detectable proteins. Quantification of this effect was measured by determining the density of cell surface receptors, using enzyme fragment complementation in a manner suitable for high-throughput screening. Thus, the authors have developed a cellular assay for GPCRs suitable for compound screening without requiring prior identification of an agonist or knowledge of G-protein-coupling.

Recent Advances of Small Molecular Regulators Targeting G Protein- Coupled Receptors Family for Oncology Immunotherapy

2019 ◽  
Vol 19 (16) ◽  
pp. 1464-1483 ◽  
Author(s):  
Peng He ◽  
Wenbo Zhou ◽  
Mingyao Liu ◽  
Yihua Chen
Keyword(s):  
G Protein ◽  
Cell Biology ◽  
Immune Cell ◽  
G Protein Coupled Receptors ◽  
Treatment Modalities ◽  
Immune Checkpoints ◽  
Considerable Proportion ◽  
Prostaglandin E ◽  
Recent Advances ◽  
G Protein Coupled

The great clinical success of chimeric antigen receptor T cell (CAR-T) and PD-1/PDL-1 inhibitor therapies suggests the drawing of a cancer immunotherapy age. However, a considerable proportion of cancer patients currently receive little benefit from these treatment modalities, indicating that multiple immunosuppressive mechanisms exist in the tumor microenvironment. In this review, we mainly discuss recent advances in small molecular regulators targeting G Protein-Coupled Receptors (GPCRs) that are associated with oncology immunomodulation, including chemokine receptors, purinergic receptors, prostaglandin E receptor EP4 and opioid receptors. Moreover, we outline how they affect tumor immunity and neoplasia by regulating immune cell recruitment and modulating tumor stromal cell biology. We also summarize the data from recent clinical advances in small molecular regulators targeting these GPCRs, in combination with immune checkpoints blockers, such as PD-1/PDL-1 and CTLA4 inhibitors, for cancer treatments.

scholarly journals Sphingosine 1-phosphate signalling through the G-protein-coupled receptor Edg-1

1998 ◽  
Vol 330 (2) ◽  
pp. 605-609 ◽  
Author(s):  
C. M. Gerben ZONDAG ◽  
R. Friso POSTMA ◽  
Ingrid VAN ETTEN ◽  
Ingrid VERLAAN ◽  
H. Wouter MOOLENAAR
Keyword(s):  
Adenylate Cyclase ◽  
Map Kinase ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
Lpa Receptor ◽  
Kinase Activation ◽  
Protein Map ◽  
Mitogen Activated Protein ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

Sphingosine 1-phosphate (S1P) and lysophosphatidic acid (LPA) are structurally related lipid mediators that act on distinct G-protein-coupled receptors to evoke similar responses, including Ca2+ mobilization, adenylate cyclase inhibition, and mitogen-activated protein (MAP) kinase activation. However, little is still known about the respective receptors. A recently cloned putative LPA receptor (Vzg-1/Edg-2) is similar to an orphan Gi-coupled receptor termed Edg-1. Here we show that expression of Edg-1 in Sf9 and COS-7 cells results in inhibition of adenylate cyclase and activation of MAP kinase (Gi-mediated), but not Ca2+ mobilization, in response to S1P. These responses are specific in that (i) S1P action is not mimicked by LPA, and (ii) Vzg-1/Edg-2 cannot substitute for Edg-1. Thus the Edg-1 receptor is capable of mediating a subset of the cellular responses to S1P.

Sphingosine 1-Phosphate (S1P) Induces Migration and ERK/MAP-Kinase-Dependent Proliferation in Chronic Lymphocytic Leukemia (B-CLL) Due to Expression of the G Protein-Coupled Receptors S1P1/4.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4996-4996
Author(s):  
Gabriele Seitz ◽  
Sedat Yildirim ◽  
Andreas M. Boehmler ◽  
Lothar Kanz ◽  
Robert Möhle
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
G Protein ◽  
Cell Lines ◽  
Peripheral Blood ◽  
G Protein Coupled Receptors ◽  
Lymphocytic Leukemia ◽  
S1p Receptors ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

Abstract Egress of lymphocytes from lymphoid organs into the circulation has been shown to depend on the presence of the lipid mediator sphingosine 1-phosphate (S1P) in the peripheral blood, and expression of corresponding S1P receptors (i.e., S1P1), that belong to the family of 7-transmembrane G protein-coupled receptors (GPCR). As circulating lymphocytic lymphoma cells are a hallmark of chronic lymphocytic leukemia, we analyzed expression of different S1P receptors and the effects of S1P on B-CLL cells. By qualitative and quantitative (TaqMan) RT-PCR, significant mRNA expression of S1P1 and S1P4 was found in CLL cell lines (EHEB, MEC-1) and in most samples (S1P1 in 88%, S1P4 in 100%) of primary CD19+ cells isolated from the peripheral blood of untreated B-CLL patients. mRNA of other S1P receptors (S1P2, S1P3, S1P5) was less consistently detected. Normal, nonmalignant B cells were strongly positive for S1P1, while other S1P receptors were weakly expressed or negative. S1P induced typical effects of chemotactic GPCR, such as actin polymerization (analyzed by flow cytometry) and chemotaxis (measured in a modified Boyden chamber assay) in CLL cell lines and primary B-CLL cells. After serum deprivation in vitro, S1P induced phosphorylation of ERK/MAP-kinase as analyzed by Western blot, demonstrating that S1P receptors expressed in CLL were able to activate signaling pathways of GPCR not only related to cell migration and chemotaxis, but also to cell proliferation. Of note, the S1P1 ligand FTY720, which induces receptor internalization after prolonged exposure and acts as an antagonist, resulted in apoptosis in CLL cell lines and primary CLL cells in vitro, as measured by MTT-test and staining with Annexin-FITC, respectively. We conclude that sphingosine 1-phosphate, which is present in the peripheral blood in considerable amounts, contributes to the trafficking of B-CLL cells expressing the GPCRs S1P1/4, and to their prolonged survival.

Arrestin-2 Regulates Akt Activation by G Protein-Coupled Receptors in Platelets.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1525-1525
Author(s):  
Dongjun Li ◽  
Donna S. Woulfe
Keyword(s):  
G Protein ◽  
Genetic Manipulation ◽  
Embryonic Stem ◽  
Phosphatidyl Inositol ◽  
G Protein Coupled Receptors ◽  
Resting Cells ◽  
Dependent Manner ◽  
Akt Phosphorylation ◽  
Receptor Sites ◽  
G Protein Coupled

Abstract Arrestins have been shown to play important roles in G Protein-Coupled Receptor (GPCR) function in many cells, but their roles in platelets remain uncharacterized. While the classical role of arrestins is considered to be the internalization and desensitization of GPCRs, more recent studies suggest that arrestins can serve as scaffolds to recruit phosphatidyl inositol-3 kinases (PI3K)s to Gq-coupled receptors and promote PI3K-dependent signaling. Thrombin stimulates the PI3K-dependent activation of Akt in platelets in a Gq-dependent manner. Therefore, we sought to determine whether arrestins are involved in the PI3K-dependent activation of Akt in platelets. Comparative immunoblots show that of the two non-visual mammalian arrestins, only one, arrestin-2 (β-arrestin-1), is expressed in human and mouse platelets. Immunoprecipitation of arrestin-2 or p85-PI3K from platelet lysates demonstrated that arrestin-2 associates with the p85 subunit of PI3Ka/b in thrombin or ADP-stimulated platelets, but not resting cells. The association can be inhibited by inhibitors of the P2Y12 receptor for ADP, but not by P2Y1 inhibitors. p85-arrestin association is also blocked by inhibitors of src family kinases, as is Akt phosphorylation. To determine whether src family members were part of the p85-arrestin complexes, immunoblots were re-probed with antibodies to src, lyn and fyn. The results show that Lyn is incorporated into thrombin-stimulated arrestin complexes in a P2Y12-dependent manner. To determine whether arrestin-2 is important for Akt phosphorylation in platelets, megakaryocytes differentiated in culture from mouse embryonic stem cells were used as models of platelet signaling, since these cells are amenable to genetic manipulation. Arrestin-2 was inhibited in the cultured megakaryocytes using a siRNA approach, then cells were stimulated with thrombin and Akt phosphorylation was assessed by immunoblotting. Arrestin-2 expression in the cultured megakaryocytes treated with arrestin-2 specific siRNA was suppressed by an average of 53% compared to cells treated with scrambled siRNA, while thrombin-stimulated Akt phosphorylation was suppressed by 98% compared to scrambled siRNA-treated control cells (n=3 experiments, difference is significant, p=.01, unpaired student’s t-test). In conclusion, the results show that arrestin-2, lyn and PI3Kform a tri-molecular complex following stimulation of platelets with ADP or thrombin. Formation of arrestin complexes at activated receptor sites is important for the localized recruitment and src-dependent activation of p85-PI3K, thus promoting activation of Akt by G protein-coupled receptors.

Sphingosine-1-Phosphate Signaling via the EDG-1 Family of G-Protein-Coupled Receptors

2006 ◽  
Vol 905 (1) ◽  
pp. 16-24 ◽  
Author(s):  
TIMOTHY HLA ◽  
MENQ-JER LEE ◽  
NICOLAS ANCELLIN ◽  
SHOBHA THANGADA ◽  
CATHERINE H. LIU ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Coupled Receptors ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

scholarly journals Roles of G Protein-Coupled Receptors (GPCRs) in Gastrointestinal Cancers: Focus on Sphingosine 1-Shosphate Receptors, Angiotensin II Receptors, and Estrogen-Related GPCRs

Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2988
Author(s):  
Zhen Zeng ◽  
Chunxiang Ma ◽  
Kexin Chen ◽  
Mingshan Jiang ◽  
Reshma Vasu ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
Angiotensin Ii Receptors ◽  
Biological Processes ◽  
Substantial Evidence ◽  
Sphingosine 1 Phosphate ◽  
Gi Cancers ◽  
G Protein Coupled ◽  
Made In

It is well established that gastrointestinal (GI) cancers are common and devastating diseases around the world. Despite the significant progress that has been made in the treatment of GI cancers, the mortality rates remain high, indicating a real need to explore the complex pathogenesis and develop more effective therapeutics for GI cancers. G protein-coupled receptors (GPCRs) are critical signaling molecules involved in various biological processes including cell growth, proliferation, and death, as well as immune responses and inflammation regulation. Substantial evidence has demonstrated crucial roles of GPCRs in the development of GI cancers, which provided an impetus for further research regarding the pathophysiological mechanisms and drug discovery of GI cancers. In this review, we mainly discuss the roles of sphingosine 1-phosphate receptors (S1PRs), angiotensin II receptors, estrogen-related GPCRs, and some other important GPCRs in the development of colorectal, gastric, and esophageal cancer, and explore the potential of GPCRs as therapeutic targets.

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