| 1998 |
EP4-deficient mice die neonatally due to patent ductus arteriosus remaining open; in situ hybridization showed EP4 mRNA is strongly expressed in the ductus arteriosus, establishing EP4 as essential for postnatal closure of this vessel. |
Gene targeting (knockout mice), histological examination, in situ hybridization |
Biochemical and biophysical research communications |
High |
9600059
|
| 1996 |
The human EP4 receptor gene spans ~22 kb with three exons; the promoter lacks a TATA box but is GC-rich and contains SP1, AP2, and CCAAT motifs; two related EP4 pseudogenes exist in the human genome. The coding region splits at transmembrane domain 6 by an intron, a structure conserved with thromboxane, PGI, and PGD receptors. |
Genomic cloning, sequencing, Southern blot, Northern blot |
Genomics |
High |
8661119
|
| 1996 |
Rabbit EP4 receptor expressed in COS-1 cells couples to Gs and stimulates cAMP production; it is insensitive to butaprost (EP2-selective) but responds to misoprostol-free acid; highly expressed in intestine, uterus, thymus, kidney glomeruli, and adrenal cortex. |
cDNA library cloning, heterologous expression in COS-1 cells, cAMP assay, RNase protection assay, in situ hybridization |
The American journal of physiology |
High |
8780252
|
| 2003 |
EP4 (unlike EP2) activates not only Gs/PKA/cAMP but also phosphatidylinositol 3-kinase (PI3K), leading to ERK1/2 activation and induction of the transcription factor EGR-1; EP4 can also stimulate T-cell factor (Tcf)-mediated transcriptional activity via both PKA and PI3K. |
Pharmacological and cell signaling assays (PI3K inhibitors, ERK assays, reporter gene assays) |
Life sciences |
Medium |
14607241
|
| 2002 |
EP4-deficient mice develop severe DSS-induced colitis with mucosal barrier dysfunction, epithelial loss, crypt damage, and CD4+ T cell proliferation, while deficiency in DP, EP1, EP2, EP3, FP, IP, or TP does not. EP4 maintains intestinal homeostasis by preserving mucosal integrity and downregulating immune response. |
Prostanoid receptor knockout mice panel, DSS colitis model, pharmacological agonist/antagonist treatment, DNA microarray, in vitro lamina propria mononuclear cell assay |
The Journal of clinical investigation |
High |
11927615
|
| 2001 |
In rat sensory neurons, EP3C and EP4 receptor subtypes mediate PGE2-induced cAMP production and augmentation of substance P and CGRP release; antisense knockdown of both EP3C and EP4 (but not individual subtypes alone) abolishes PGE2-stimulated cAMP and peptide release. |
RT-PCR, antisense oligonucleotide knockdown, cAMP assay, immunoreactive peptide release assay |
The Journal of biological chemistry |
High |
11278900
|
| 2004 |
In colon adenocarcinoma CT26 cells, PGE2-EP4 receptor signaling promotes cell proliferation via PI3K/ERK activation; EP4-selective agonist PGE1-OH rescues anti-proliferative effects of COX inhibition specifically through this pathway. |
COX inhibitor rescue experiments, EP-selective agonists, PI3K/ERK inhibitors, cell proliferation assays, in vivo tumor model |
The Journal of biological chemistry |
High |
15123663
|
| 2006 |
EP4 receptor expression increases in DRG neurons after peripheral inflammation; EP4 antagonist or shRNA knockdown attenuates inflammatory thermal and mechanical hypersensitivity; EP4 mediates PGE2-induced sensitization of capsaicin-evoked currents in DRG neurons in vitro. |
Immunohistochemistry, intrathecal shRNA knockdown, behavioral pain testing, whole-cell patch-clamp electrophysiology, EP4 antagonist (AH23848) |
The Journal of pharmacology and experimental therapeutics |
High |
16966471
|
| 2006 |
Enforced EP4 overexpression in adenoma cells (RG/C2) confers stimulation of growth by high doses of PGE2 and promotes anchorage-independent growth, demonstrating that EP4 receptor level determines the tumorigenic response to PGE2 in colorectal cancer progression. |
Forced EP4 expression in cell lines, growth assay, soft agar anchorage-independence assay, immunohistochemistry of human specimens |
Cancer research |
Medium |
16540660
|
| 2006 |
EP4 receptor antagonism (AH23848 or ONO-AE3-208) reduces breast cancer lung colonization and spontaneous metastasis; EP4 gene silencing by shRNA also reduces metastasis; EP4 antagonism inhibited PGE2-induced tumor cell migration in vitro. |
EP4 antagonists, shRNA gene silencing, in vivo metastasis assays, in vitro chemotaxis assay |
Cancer research |
High |
16540639
|
| 2007 |
EP4 mediates PGE2-induced endothelial cell migration and tubulogenesis via ERK (not PKA) signaling; EP4-null endothelial cells fail to migrate or form tubes in response to PGE2 or EP4-selective agonists; EP4 also promotes angiogenesis in vivo in a sponge assay. |
Adenocre-mediated EP4 deletion in primary endothelial cells (EP4 flox/flox), ERK/PKA inhibitors, migration and tubulogenesis assays, in vivo angiogenesis sponge assay |
The Journal of biological chemistry |
High |
17401137
|
| 2007 |
EP4 mediates PGE2-dependent cell survival in Jurkat T cells via the PI3K/AKT pathway (not PKA); EP4 antagonist abolishes PGE2 protection from camptothecin-induced apoptosis. |
Pharmacological EP receptor antagonists, PI3K/AKT and PKA inhibitors, caspase-3 assay, flow cytometry |
Prostaglandins & other lipid mediators |
Medium |
17259077
|
| 2008 |
Macrophage-specific EP4 deficiency increases macrophage apoptosis in response to proapoptotic stimuli and reduces early atherosclerosis; EP4 promotes macrophage survival through the PI3K/Akt and NF-κB pathways. |
Fetal liver cell transplantation (bone marrow chimeras), LDLR-/- atherosclerosis model, apoptosis assays, Western blot for p-Akt/p-Bad/NF-κB |
Cell metabolism |
High |
19041765
|
| 2008 |
EP4 receptor functions as a negative regulator of B cell proliferation in response to BCR signaling; EP4 knockdown accelerates lymphoma spread in mice, while overexpression is protective; EP4 and PGE2-EP4 signaling target a similar set of activating genes in B cells. |
Stable shRNA knockdown and overexpression in B cell lymphoma, in vivo tumor spread assay, gene expression analysis |
The Journal of experimental medicine |
High |
19075289
|
| 2009 |
PGE2-EP4 signaling on T cells and dendritic cells promotes TH1 cell differentiation and amplifies IL-23-mediated TH17 cell expansion in vitro; EP4-selective antagonist in vivo decreases TH1 and TH17 accumulation and suppresses EAE and contact hypersensitivity. |
In vitro T cell differentiation assays with EP4-selective agonists/antagonists, in vivo EAE and CHS models with EP4 antagonist treatment |
Nature medicine |
High |
19465928
|
| 2009 |
PGE2 signaling through EP4 on FSP1+ fibroblasts (not EP1 or EP2) induces RANKL expression to promote osteoclastogenesis and periprosthetic osteolysis; conditional fibroblast-specific EP4 knockout abrogates RANKL upregulation and osteolysis. |
EP receptor knockout mice panel, conditional FSP1-Cre EP4 knockout, wear debris mouse model, in vitro PGE2 stimulation of fibroblasts |
Journal of bone and mineral research |
High |
19419302
|
| 2009 |
EP4 receptor exhibits functional selectivity: PGE2 most selectively activates Gαs, PGF2α and PGE1-OH show bias toward Gαi1 and β-arrestin respectively; EP4 can couple to Gαs, Gαi, and recruit β-arrestin with distinct potency/efficacy profiles depending on ligand. |
Bioluminescence resonance energy transfer (BRET) assays for Gαs, Gαi, and β-arrestin2 in living cells |
The Journal of pharmacology and experimental therapeutics |
High |
19584306
|
| 2011 |
PGE2 promotes angiogenesis via EP4 coupling to Gαs/cAMP/PKA Cγ; knockdown of EP4 or PKA catalytic subunit γ attenuates tube formation; downstream PKA substrates Rap1A, HSPB6, and eNOS promote angiogenesis while RhoA and GSK3β (inactivated by PKA) suppress it. |
siRNA knockdown of EP4 and PKA subunits, EP receptor subtype-selective agonists/antagonists, in vitro tube formation, ex vivo aortic ring assay, in vivo angiogenesis assay |
Blood |
High |
21926356
|
| 2011 |
EP4 (not EP2 or IP) is the primary receptor mediating COX-2-dependent stimulation of renin expression in response to furosemide-induced macula densa activation; EP4-/- mice show ~70% reduction in renin stimulation. |
Genetic knockout mice for COX-2, mPGES1, mPGES2, EP2, EP4, and IP receptors; furosemide treatment; real-time RT-PCR for renin mRNA |
American journal of physiology. Renal physiology |
High |
21835766
|
| 2012 |
MiR-101 post-transcriptionally represses EP4 receptor expression by binding the 3'-UTR; ectopic miR-101 reduces EP4 protein, cell proliferation and motility; EP4 overexpression rescues cells from miR-101 tumor-suppressive effects; EP4 silencing phenocopies miR-101. |
Luciferase 3'-UTR reporter assay with wild-type and mutant constructs, miR-101 transfection, qRT-PCR, Western blot, cell proliferation and motility assays, co-transfection rescue |
Cancer biology & therapy |
High |
22353936
|
| 2012 |
EP4 signaling through β-arrestin1 upregulates Akt signaling to protect colonic mucosal integrity; β-arrestin1-deficient mice show worsened DSS-colitis with reduced PI3K/p-Akt; PGE2 upregulates β-arrestin1 expression via EP4 both in vivo and in vitro. |
β-arrestin1 KO mice, DSS colitis model, siRNA knockdown of β-arr1 in HCT116 cells, Western blot for PI3K/Akt |
Scientific reports |
Medium |
28432343
|
| 2012 |
In immature B cells (WEHI 231), EP4 activation increases cAMP/PKA, stabilizes NF-κB1 p105, inhibits IκBα phosphorylation, and sequesters NF-κB p65 in the cytoplasm; PI3K is not involved in EP4 signaling in this cell type, contrasting with other cell types. |
cAMP ELISA, Western blot for VASP/ERK/IκBα/p105 phosphorylation, fluorescence microscopy for p65 localization, pharmacological EP receptor agonists/antagonists |
The Journal of pharmacy and pharmacology |
Medium |
22775212
|
| 2013 |
PGE2 regulates pancreatic stellate cell proliferation, migration, invasion, and extracellular matrix/MMP gene expression exclusively through the EP4 receptor (not EP1, EP2, or EP3); EP4 siRNA and EP4-selective antagonists abrogate these effects. |
siRNA knockdown of EP4, EP-selective antagonists, MTS proliferation assay, Boyden chamber migration/invasion assay, RT-PCR for matrix genes |
Pancreas |
Medium |
23090667
|
| 2015 |
EP4 receptor deletion in myeloid cells (using LysM-Cre) markedly inhibits adenoma number and size in ApcMin/+ mice, with decreased mTOR and ERK activation; either genetic or pharmacologic EP4 inhibition drives macrophages/DCs to an anti-tumorigenic M1 phenotype. |
Myeloid-specific conditional EP4 knockout (LysM-Cre), ApcMin/+ intestinal polyp model, EP4 pharmacological inhibitor, macrophage polarization assays, mTOR/ERK signaling analysis |
Oncotarget |
High |
26378024
|
| 2016 |
COX-2 induces breast cancer stem-like cells via EP4-mediated PI3K/AKT activation of NOTCH and WNT signaling; PI3K/AKT or NOTCH/WNT inhibitors block COX-2/EP4-induced stem cell induction; EP4 antagonist or knockdown reverses all stem-like cell markers and metastasis. |
COX-2 overexpression, EP4 antagonist and siRNA knockdown, PI3K/AKT/NOTCH/WNT pathway inhibitors, spheroid formation, ALDH activity, xenograft tumor metastasis models |
Stem cells (Dayton, Ohio) |
High |
27301070
|
| 2016 |
EP4 activation in the collecting duct operates downstream of vasopressin via PGE2, and upstream of the (pro)renin receptor (PRR), forming a linear AVP/PGE2/EP4/PRR pathway that regulates AQP2 expression and urine concentrating capability; EP4 antagonist and PRR decoy peptide both impair AVP-induced AQP2 expression. |
Intrarenal infusion of EP4 antagonist and PRR decoy peptide in rats, collecting duct-specific PRR knockout mice, primary inner medullary CD cell culture, water deprivation model |
Journal of the American Society of Nephrology : JASN |
High |
27000064
|
| 2017 |
PGA2 signals through EP4 (identified as a novel PGA2 receptor by pharmacological and molecular screening) to activate Rap1/Rac1 GTPase and PKA targets (VE-cadherin, p120-catenin, ZO-1, cortactin, VASP) enhancing endothelial barrier; it also suppresses NF-κB and ICAM1/VCAM1 expression. Endothelial-specific EP4 knockout abolishes barrier protection in vivo. |
Pharmacological and siRNA EP receptor screening, endothelial-specific EP4 knockout mice, two models of acute lung injury, barrier permeability assays, cytoskeleton/junction protein analysis |
Molecular biology of the cell |
High |
28428256
|
| 2017 |
EP4 promotes invadopodia-mediated ECM degradation and invasion of breast cancer cells through EGFR-dependent signaling; EP4 agonist increases invadopodia and matrix degradation in vitro and in vivo xenografts; EGFR tyrosine kinase inhibition abrogates EP4-mediated matrix degradation. |
EP4 agonist and antagonist treatment, 2D invadopodia assay, 3D invasion assay, EGFR kinase inhibitor epistasis, intravital microscopy, xenograft mouse model |
European journal of cell biology |
Medium |
28094049
|
| 2019 |
EP4 activates PI3K and induces Ca2+ influx through Orai1 (without STIM1 involvement); EP4 forms a complex with Orai1 and TRPC1 (shown by co-immunoprecipitation); Orai1-mediated Ca2+ influx leads to ERK phosphorylation and MMP-2/9 activation promoting oral cancer cell migration; Orai1 knockdown abolishes EP4-induced ERK activation. |
Co-immunoprecipitation, siRNA knockdown of EP4 and Orai1, Ca2+ imaging, ERK phosphorylation assay, cell migration assay, in vivo lung metastasis model |
Cancer science |
High |
31755615
|
| 2019 |
In ankylosing spondylitis Th17 cells, EP4 drives Th17 expansion through upregulation of IL-23 receptor, suppression of the RORγt inhibitor FoxO1, and enhancement of STAT3 phosphorylation; EP4 creates a positive feedback loop enhancing its own expression in AS Th17 cells. |
Quantitative RT-PCR, flow cytometry, Western blot for EP4 protein, EP4-specific agonist functional assay in primary Th17 cells from AS, RA, PsA patients and healthy controls |
Arthritis research & therapy |
Medium |
31253169
|
| 2019 |
COX-1/mPGES-1-derived PGE2 acts via endothelial EP4 to protect against myocardial ischemia/reperfusion injury; endothelium-restricted Ep4 deletion impairs microcirculation and exacerbates MI/R injury irrespective of EP4 agonism. |
mPges-1 knockout, endothelium-restricted Ep4 conditional knockout mice, MI/R model, microvascular perfusion imaging, leukocyte-endothelial interaction assay |
Nature communications |
High |
31015404
|
| 2020 |
Cryo-EM structure of EP4 coupled to heterotrimeric Gs protein at 3.3 Å resolution reveals that compared with other class A GPCRs, the TM6 outward shift is smaller; instead, the Gs C-terminal helix inserts toward TM2 with an extended hook structure; conserved prostanoid receptor residues Phe54(2.39) and Trp327(7.51) form these unique contacts. |
Cryo-electron microscopy (cryo-EM) structure determination at 3.3 Å global resolution |
Structure (London, England : 1993) |
High |
33264604
|
| 2020 |
Endothelial cell-specific EP4 deletion elevates blood pressure while EC-specific EP4 overexpression reduces it; EP4 maintains BP homeostasis by promoting eNOS phosphorylation at Ser1177 and NO production primarily via the AMPK pathway; mesenteric arteries of EC-EP4-/- mice show increased vasoconstrictor and reduced vasodilatory responses abolished by eNOS inhibition. |
EC-specific EP4 knockout and overexpression mice, blood pressure measurement, vascular reactivity assay, eNOS phosphorylation Western blot, AMPK pathway analysis, l-NAME pharmacology |
JCI insight |
High |
32641583
|
| 2020 |
EP4/AC/cAMP/PKA signaling mediates GRK2 translocation to the plasma membrane, where GRK2 dissociates from ERK1/2 and loses its inhibitory effect on ERK, thus promoting PGE2-induced angiogenesis; GRK2 siRNA inhibits PGE2-induced endothelial migration and tube formation; Lys220 and Ser685 of GRK2 are important for GRK2 translocation and angiogenic function. |
siRNA knockdown of GRK2 and EP4, GRK2 mutant constructs, cAMP FRET assay, ERK co-precipitation, in vivo Matrigel angiogenesis assay with GRK2-deficient aortic segments |
Clinical science (London, England : 1979) |
High |
31967309
|
| 2021 |
PTGER4+ intestinal macrophages promote epithelial barrier regeneration; Csf1r-iCre Ptger4fl/fl mice show defective mucosal healing in DSS colitis; mechanistically, PGE2 triggers CXCL1 secretion from monocyte-derived PTGER4+ macrophages via MAPK signaling, and CXCL1 drives epithelial cell differentiation and proliferation from regenerating crypts. |
Macrophage-specific conditional EP4 knockout (Csf1r-iCre), DSS colitis model, MAPK pathway analysis, liposome-encapsulated MAPK agonist therapeutic rescue, epithelial organoid differentiation assay |
Gut |
High |
33558271
|
| 2021 |
TNF-α impairs EP4 signaling by recruiting TRAF2 to the plasma membrane, where TRAF2 interacts with and translocates GRK2, causing EP4 desensitization and internalization and reducing cAMP production; TRAF2 siRNA prevents GRK2 translocation and restores EP4 membrane expression and cAMP. |
cAMP FRET biosensor, co-immunoprecipitation of TRAF2-GRK2, siRNA knockdown of TRAF2, Western blot for EP4 membrane distribution, primary human fibroblast-like synoviocytes |
Acta pharmacologica Sinica |
High |
33859345
|
| 2022 |
PGE2 acts via EP4 on osteoclasts (specifically via EP4, not EP2 alone) to promote OA progression; tissue-specific EP4 knockout in osteoclasts (EP4LysM) reduces OA progression, osteophyte formation, OA-related pain, Netrin-1 secretion, CGRP+ sensory innervation, PDGF-BB expression, and type H blood vessel formation; EP4 signals through Gαs/PI3K/AKT/MAPK in osteoclasts. |
Osteoclast-specific EP4 conditional knockout (LysM-Cre), DMM OA model, pain behavior testing, immunofluorescence for nerve innervation and vasculature, Gαs/PI3K/AKT/MAPK pathway analysis, novel EP4 antagonist HL-43 |
Bone research |
High |
35260562
|
| 2022 |
Cartilage-specific EP4 deletion promotes chondrogenesis and cartilage anabolism, suppresses catabolism and hypertrophy, and reduces joint pain; EP4 regulates cartilage anabolism through cAMP/PKA/CREB/Sox9 signaling; EP4 antagonist HL-43 reproduces these effects in multiple cartilage defect models. |
Cartilage-specific EP4 conditional knockout, microfracture and DMM surgery models, aging model, human cartilage explants, cAMP/PKA/CREB/Sox9 signaling analysis |
Cell discovery |
High |
35256606
|
| 2022 |
PGE2-EP2/EP4 signaling simultaneously promotes NF-κB-driven active inflammation in myeloid cells and drives the mregDC-Treg axis for Treg recruitment and activation, creating immunosuppression in the tumor microenvironment; dual EP2/EP4 inhibition required to reverse both arms. |
Immune checkpoint inhibitor-insensitive mouse cancer model, single-cell RNA sequencing, pharmacological EP2/EP4 antagonists |
Cell reports |
High |
35675777
|
| 2003 |
The rat EP4 gene has three exons separated by two introns; a GC-rich/Sp1 binding site within the first 80 bases of the transcription start site is required for constitutive EP4 transcription; mutation of the Sp1 site at -78 to -66 abolishes promoter activity; three Sp1 sites cooperate to enhance transcription. |
Genomic cloning, Northern blot, luciferase reporter constructs with deletion and site-specific mutations, identification of transcription start site |
American journal of obstetrics and gynecology |
High |
14634592
|
| 2008 |
EP4 transcription in glioblastoma T98G cells is driven by Sp1 binding sites at -197 to -160 of the human EP4 promoter; troglitazone and sulindac sulfide suppress EP4 expression by activating MEK/ERK, which phosphorylates Sp1 reducing its DNA binding (confirmed by ChIP); reversal by MEK inhibitor PD98059 establishes Sp1 phosphorylation as the suppression mechanism. |
Luciferase reporter assays with Sp1 site mutations, ChIP assay for Sp1 binding, immunoprecipitation-Western blot for Sp1 phosphorylation, MEK/ERK inhibitor (PD98059) rescue |
Biochimica et biophysica acta |
High |
18346464
|
| 2012 |
EP4 signaling in DRG neurons promotes EP4 externalization (trafficking from Golgi and recycling endosomes to plasma membrane); inhibitors of anterograde secretory pathway, protein synthesis, or recycling suppress PGE2-induced EP4 surface expression; complete Freund's adjuvant-induced inflammation increases cell-surface EP4 levels via COX-2/PGE2/EP4 signaling in vivo. |
Pharmacological inhibitors of secretory pathway/recycling, cell-surface biotinylation, intracellular cAMP sequential treatment assay, CFA inflammation model, COX-2 inhibitor treatment |
Pain |
Medium |
23265688
|
| 2015 |
EP4 receptor deletion in macrophages (conditional KO) renders macrophages less susceptible to M2 polarization; EP4 agonist enhances M2 polarization and improves glucose tolerance and insulin sensitivity in obese db/db mice by promoting M2 macrophage polarization via PPARδ; PPARδ antagonism suppresses EP4-mediated M2 polarization. |
EP4-selective agonist in db/db mice, peritoneal macrophage M1/M2 polarization assay with EP4-KO macrophages, PPARδ antagonist epistasis, adipose tissue histology and cytokine analysis |
PloS one |
Medium |
26308623
|
| 2023 |
EP4 blockade abrogates Yes-associated protein 1 (YAP)-driven pro-metastatic factor expression in pancreatic cancer cells in vitro and reduces YAP activity in vivo; EP4-YAP signaling axis is a pro-metastatic pathway in pancreatic cancer. |
EP4 antagonist L001, YAP activity reporter assay, in vivo hepatic metastasis model, Western blot for YAP targets |
Molecules (Basel, Switzerland) |
Medium |
35208999
|