scholarly journals Evidence for a Bacterial Lipopolysaccharide-Recognizing G-Protein-Coupled Receptor in the Bacterial Engulfment by Entamoeba histolytica

2013 ◽  
Vol 12 (11) ◽  
pp. 1433-1438 ◽  
Author(s):  
Matthew T. Brewer ◽  
Prince N. Agbedanu ◽  
Mostafa Zamanian ◽  
Tim A. Day ◽  
Steve A. Carlson
Keyword(s):  
G Protein ◽  
Entamoeba Histolytica ◽  
Drug Target ◽  
Bacterial Flora ◽  
Bacterial Lipopolysaccharide ◽  
Dependent Manner ◽  
G Protein Coupled Receptor ◽  
Concentration Dependent Manner ◽  
Content Type ◽  
G Protein Coupled

ABSTRACT Entamoeba histolytica is the causative agent of amoebic dysentery, a worldwide protozoal disease that results in approximately 100,000 deaths annually. The virulence of E. histolytica may be due to interactions with the host bacterial flora, whereby trophozoites engulf colonic bacteria as a nutrient source. The engulfment process depends on trophozoite recognition of bacterial epitopes that activate phagocytosis pathways. E. histolytica GPCR-1 (EhGPCR-1) was previously recognized as a putative G-protein-coupled receptor (GPCR) used by Entamoeba histolytica during phagocytosis. In the present study, we attempted to characterize EhGPCR-1 by using heterologous GPCR expression in Saccharomyces cerevisiae . We discovered that bacterial lipopolysaccharide (LPS) is an activator of EhGPCR-1 and that LPS stimulates EhGPCR-1 in a concentration-dependent manner. Additionally, we demonstrated that Entamoeba histolytica prefers to engulf bacteria with intact LPS and that this engulfment process is sensitive to suramin, which prevents the interactions of GPCRs and G-proteins. Thus, EhGPCR-1 is an LPS-recognizing GPCR that is a potential drug target for treatment of amoebiasis, especially considering the well-established drug targeting to GPCRs.

scholarly journals A novel G protein-coupled receptor for gonadotropin-inhibitory hormone in the Japanese quail (Coturnix japonica): identification, expression and binding activity

2005 ◽  
Vol 184 (1) ◽  
pp. 257-266 ◽  
Author(s):  
H Yin ◽  
K Ukena ◽  
T Ubuka ◽  
K Tsutsui
Keyword(s):  
G Protein ◽  
Japanese Quail ◽  
Binding Activity ◽  
Coturnix Japonica ◽  
Dependent Manner ◽  
G Protein Coupled Receptor ◽  
Concentration Dependent Manner ◽  
Gonadotropin Release ◽  
Gonadotropin Inhibitory Hormone ◽  
G Protein Coupled

We recently identified a novel hypothalamic dodecapeptide inhibiting gonadotropin release in the Japanese quail (Coturnix japonica). This novel peptide was therefore named gonadotropin-inhibitory hormone (GnIH). The GnIH precursor encoded one GnIH and two GnIH-related peptides (GnIH-RP-1 and GnIH-RP-2) that shared the same C-terminal motif, Leu-Pro-Xaa-Arg-Phe-NH2 (Xaa=Leu or Gln; LPXRF-amide peptides). Identification of the receptor for GnIH is crucial to elucidate the mode of action of GnIH. We therefore identified the receptor for GnIH in the quail diencephalon and characterized its expression and binding activity. We first cloned a cDNA encoding a putative GnIH receptor by a combination of 3′ and 5′ rapid amplification of cDNA ends (RACE) using PCR primers designed from the sequence for the receptor for rat RF-amide-related peptide (RFRP), an orthologous peptide of GnIH. Hydrophobic analysis revealed that the putative GnIH receptor possessed seven transmembrane domains, indicating a new member of the G protein-coupled receptor superfamily. The crude membrane fraction of COS-7 cells transfected with the putative GnIH receptor cDNA specifically bound to GnIH and GnIH-RPs in a concentration-dependent manner. Scatchard plot analysis of the binding showed that the identified GnIH receptor possessed a single class of high-affinity binding sites (Kd=0.752 nM, Bmax=24.8 fmol/mg protein). Southern blotting analysis of reverse transcriptase-mediated PCR products revealed the expression of GnIH receptor mRNA in the pituitary gland and several brain regions including diencephalon in the quail. These results suggest that GnIH acts directly on the pituitary via GnIH receptor to inhibit gonadotropin release. GnIH may also act on the hypothalamus to inhibit gonadotropin-releasing hormone release.

scholarly journals Increase of Anteroventral Periventricular Kisspeptin Neurons and Generation of E2-Induced LH-Surge System in Male Rats Exposed Perinatally to Environmental Dose of Bisphenol-A

Endocrinology ◽  
2011 ◽  
Vol 152 (4) ◽  
pp. 1562-1571 ◽  
Author(s):  
Yinyang Bai ◽  
Fei Chang ◽  
Rong Zhou ◽  
Peng-Peng Jin ◽  
Hirokazu Matsumoto ◽  
...  
Keyword(s):  
Bisphenol A ◽  
G Protein ◽  
Female Rats ◽  
Male Rats ◽  
Perinatal Exposure ◽  
Dependent Manner ◽  
G Protein Coupled Receptor ◽  
Control Male ◽  
Lh Surge ◽  
G Protein Coupled

Abstract Perinatal exposure to environmental levels of bisphenol-A (BPA) impairs sexually dimorphic behaviors in rodents. Kisspeptin neurons in anteroventral periventricular nucleus (AVPV), which plays an important role in the activation of GnRH neurons and the initiation of LH-surge, have been suggested to be sexual dimorphism in rats. This study focused on exploring the influence of a perinatal exposure to an environmental dose of BPA on the development and maturation of male AVPV kisspeptin neurons and hypothalamus-pituitary-gonadal axis. Female rats were injected sc with 2 μg BPA/kg·d from gestation d 10 through lactation d 7. Anatomical and functional changes in AVPV kisspeptin neurons and hypothalamus-pituitary-gonadal axis were examined in prepubertal, pubertal, and adult male rats exposed perinatally to BPA (BPA-rats). Here, we show that in postnatal d (PND)30/50/90 BPA-rats, the number of AVPV kisspeptin-immunoreactive cells was persistently increased in comparison with age-matched control male rats. The number of GnRH-immunoreactive cells in PND30 BPA-rats declined approximately 40% compared with control male rats, whereas that in PND50/90 BPA-rats was increased in a G protein-coupled receptor 54-dependent manner. Estradiol could induce a stable LH-surge in PND90 BPA-rats and control female rats, which was sensitive to the G protein-coupled receptor 54 inhibitor. In PND30/50 BPA-rats, plasma level of LH was higher, but the level of testosterone was lower than control male rats. These findings provide evidence that perinatal exposure to an environmental dose of BPA causes a sustained increase in AVPV kisspeptin neurons in male rats, leading to the generation of estradiol-induced LH-surge system.

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.

scholarly journals Activation of Intracellular Signaling Pathways by the Murine Cytomegalovirus G Protein-Coupled Receptor M33 Occurs via PLC-β/PKC-Dependent and -Independent Mechanisms

2009 ◽  
Vol 83 (16) ◽  
pp. 8141-8152 ◽  
Author(s):  
Joseph D. Sherrill ◽  
Melissa P. Stropes ◽  
Olivia D. Schneider ◽  
Diana E. Koch ◽  
Fabiola M. Bittencourt ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Kinase ◽  
Signaling Pathways ◽  
G Protein ◽  
Intracellular Signaling ◽  
Murine Cytomegalovirus ◽  
Dependent Manner ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled

ABSTRACT The presence of numerous G protein-coupled receptor (GPCR) homologs within the herpesvirus genomes suggests an essential role for these genes in viral replication in the infected host. Such is the case for murine cytomegalovirus (MCMV), where deletion of the M33 GPCR or replacement of M33 with a signaling defective mutant has been shown to severely attenuate replication in vivo. In the present study we utilized a genetically altered version of M33 (termed R131A) in combination with pharmacological inhibitors to further characterize the mechanisms by which M33 activates downstream signaling pathways. This R131A mutant of M33 fails to support salivary gland replication in vivo and, as such, is an important tool that can be used to examine the signaling activities of M33. We show that M33 stimulates the transcription factor CREB via heterotrimeric Gq/11 proteins and not through promiscuous coupling of M33 to the Gs pathway. Using inhibitors of signaling molecules downstream of Gq/11, we demonstrate that M33 stimulates CREB transcriptional activity in a phospholipase C-β and protein kinase C (PKC)-dependent manner. Finally, utilizing wild-type and R131A versions of M33, we show that M33-mediated activation of other signaling nodes, including the mitogen-activated protein kinase family member p38α and transcription factor NF-κB, occurs in the absence of Gq/11 and PKC signaling. The results from the present study indicate that M33 utilizes multiple mechanisms to modulate intracellular signaling cascades and suggest that signaling through PLC-β and PKC plays a central role in MCMV pathogenesis in vivo.

scholarly journals Activation of GPR39 With TC-G 1008 Attenuates Neuroinflammation Via SIRT1/PGC-1α/Nrf2 Pathway Post Neonatal Hypoxic-ischemic Injury in Rats

2021 ◽  
Author(s):  
Shucai Xie ◽  
Xili Jiang ◽  
Desislava Met Doycheva ◽  
Hui Shi ◽  
Peng Jin ◽  
...  
Keyword(s):  
G Protein ◽  
Sirtuin 1 ◽  
Neonatal Rat ◽  
Neurological Deficits ◽  
Dependent Manner ◽  
G Protein Coupled Receptor ◽  
Short Term ◽  
Nrf2 Pathway ◽  
G Protein Coupled

Abstract Background: Hypoxic-ischemic encephalopathy (HIE) is a severe anoxic brain injury that leads to premature mortality or long-term disabilities in infants. Neuroinflammation is a vital contributor to the pathogenic cascade post HIE and a mediator to secondary neuronal death. As a plasma membrane G-protein coupled receptor, GPR39, exhibits anti-inflammatory activity in several diseases. This study aimed to explore the neuroprotective function of GPR39 through inhibition of inflammation post hypoxic-ischemic (HI) injury and to elaborate the contribution of sirtuin 1(SIRT1)/ peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α)/ nuclear factor, erythroid 2 like 2(Nrf2) in G protein-coupled receptor 39 (GPR39)-mediated protection.Methods: A total of 206 10-day old Sprague Dawley rat pups were subjected to HIE or sham surgery. TC-G 1008 was administered intranasally at 1h, 25h, 49h, and 73h post HIE induction. SIRT1 inhibitor EX527, GPR39 CRISPR, and PGC-1α CRISPR were administered to elucidate the underlying mechanisms. Brain infarct area, short-term and long-term neurobehavioral tests, Nissl staining, western blot, and immunofluorescence staining were performed post HIE.Results: The expression of GPR39 and pathway-related proteins, SIRT1、PGC-1α and Nrf2 were increased in a time-dependent manner, peaking at 24 h or 48h post HIE. Intranasal administration of TC-G 1008 reduced the percent infarcted area and improved short-term and long-term neurological deficits. Moreover, TC-G 1008 treatment significantly increased the expression of SIRT1, PGC-1α, Nrf2, IL-6, IL-1β, and TNF-α. GPR39 CRISPR EX527 and PGC-1α CRISPR abolished GPR39’s neuroprotective effects post HIE.Conclusions:TC-G 1008 attenuated neuroinflammation in part via the SIRT1/PGC-1α/Nrf2 pathway in a neonatal rat model of HIE. TC-G 1008 may be a novel therapeutic target for treatment post neonatal HIE injury.

scholarly journals Identification of a Conserved, Orphan G Protein-Coupled Receptor Required for Efficient Pathogen Clearance in Caenorhabditis elegans

2019 ◽  
Vol 87 (4) ◽  
Author(s):  
Alexandra Anderson ◽  
Yee Lian Chew ◽  
William Schafer ◽  
Rachel McMullan
Keyword(s):  
Caenorhabditis Elegans ◽  
Immune Responses ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
G Protein Coupled Receptor ◽  
Content Type ◽  
C Elegans ◽  
Host Immune Responses ◽  
Pathogen Clearance ◽  
G Protein Coupled

ABSTRACT G protein-coupled receptors contribute to host defense across the animal kingdom, transducing many signals involved in both vertebrate and invertebrate immune responses. While it has become well established that the nematode worm Caenorhabditis elegans triggers innate immune responses following infection with numerous bacterial, fungal, and viral pathogens, the mechanisms by which C. elegans recognizes these pathogens have remained somewhat more elusive. C. elegans G protein-coupled receptors have been implicated in recognizing pathogen-associated damage and activating downstream host immune responses. Here we identify and characterize a novel G protein-coupled receptor required to regulate the C. elegans response to infection with Microbacterium nematophilum. We show that this receptor, which we designate pathogen clearance-defective receptor 1 (PCDR-1), is required for efficient pathogen clearance following infection. PCDR-1 acts upstream of multiple G proteins, including the C. elegans Gαq ortholog, EGL-30, in rectal epithelial cells to promote pathogen clearance via a novel mechanism.

Entamoeba histolytica: Identification of EhGPCR-1, a novel putative G protein-coupled receptor that binds to EhRabB

2005 ◽  
Vol 110 (3) ◽  
pp. 253-258 ◽  
Author(s):  
Karina Picazarri ◽  
Juan Pedro Luna-Arias ◽  
Eduardo Carrillo ◽  
Esther Orozco ◽  
Mario A. Rodriguez
Keyword(s):  
G Protein ◽  
Entamoeba Histolytica ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled

scholarly journals Gpr1, a Putative G-Protein-Coupled Receptor, Regulates Morphogenesis and Hypha Formation in the Pathogenic Fungus Candida albicans

2004 ◽  
Vol 3 (4) ◽  
pp. 919-931 ◽  
Author(s):  
Takuya Miwa ◽  
Yukinobu Takagi ◽  
Makiko Shinozaki ◽  
Cheol-Won Yun ◽  
Wiley A. Schell ◽  
...  
Keyword(s):  
Candida Albicans ◽  
G Protein ◽  
Pathogenic Fungus ◽  
Glucose Sensing ◽  
Dependent Manner ◽  
G Protein Coupled Receptor ◽  
Epistasis Analysis ◽  
Hypha Formation ◽  
Mutant Strains ◽  
G Protein Coupled

ABSTRACT In response to various extracellular signals, the morphology of the human fungal pathogen Candida albicans switches from yeast to hypha form. Here, we report that GPR1 encoding a putative G-protein-coupled receptor and GPA2 encoding a Gα subunit are required for hypha formation and morphogenesis in C. albicans. Mutants lacking Gpr1 (gpr1/gpr1) or Gpa2 (gpa2/gpa2) are defective in hypha formation and morphogenesis on solid hypha-inducing media. These phenotypic defects in solid cultures are suppressed by exogenously added dibutyryl-cyclic AMP (dibutyryl-cAMP). Biochemical studies also reveal that GPR1 and GPA2 are required for a glucose-dependent increase in cellular cAMP. An epistasis analysis indicates that Gpr1 functions upstream of Gpa2 in the same signaling pathway, and a two-hybrid assay reveals that the carboxyl-terminal tail of Gpr1 interacts with Gpa2. Moreover, expression levels of HWP1 and ECE1, which are cAMP-dependent hypha-specific genes, are reduced in both mutant strains. These findings support a model that Gpr1, as well as Gpa2, regulates hypha formation and morphogenesis in a cAMP-dependent manner. In contrast, GPR1 and GPA2 are not required for hypha formation in liquid fetal bovine serum (FBS) medium. Furthermore, the gpr1 and the gpa2 mutant strains are fully virulent in a mouse infection. These findings suggest that Gpr1 and Gpa2 are involved in the glucose-sensing machinery that regulates morphogenesis and hypha formation in solid media via a cAMP-dependent mechanism, but they are not required for hypha formation in liquid medium or during invasive candidiasis.

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