Abstract
Herein we provide evidence for the coexpression of two distinct prostacyclin (PGI2) receptors (IP) on BEAS-2B human airway epithelial cells. IP receptor heterogeneity initially was suggested by the finding that the rank orders of potency of PGI2 and three structurally similar analogs [taprostene, iloprost, 15-deoxy-16-(m-tolyl)-17,18,19,20-tetranorisocarbacyclin (15-deoxy-TIC)] for the inhibition of chemokine (CXCL9 and CXCL10) release and for transcriptional activation/augmentation of cAMP response element and glucocorticoid response element luciferase reporters were distinct. Indeed, PGI2, taprostene, and iloprost activated both reporters whereas 15-deoxy-TIC was inert. Conversely, 15-deoxy-TIC, PGI2, and taprostene (but not iloprost) suppressed chemokine release. Further experiments established that iloprost did not antagonize the inhibitory effect taprostene or 15-deoxy-TIC on chemokine output. Likewise, 15-deoxy-TIC failed to antagonize taprostene- and iloprost-induced reporter transactivation. Thus, iloprost- and 15-deoxy-TIC-induced responses were apparently mediated via pharmacologically distinct receptors. In human embryonic kidney 293 cells overexpressing the human recombinant IP receptor receptor, 15-deoxy-TIC was considerably less potent (>10,000-fold) than iloprost and taprostene in promoting cAMP accumulation, yet in BEAS-2B cells, these analogs were equipotent. IP receptor heterogeneity was also supported by the finding that the affinity of the IP receptor antagonist R-3-(4-fluorophenyl)-2-[5-(4-fluorophenyl)-benzofuran-2-yl-methoxycarbonyl-amino] propionic acid (RO3244794) for the receptor mediating inhibition of chemokine release was approximately 10-fold lower than for the receptor mediating both transcriptional outputs. Finally, small interfering RNAs directed against the IP receptor gene, PTGIR, failed to block the suppression of chemokine output induced by taprostene and 15-deoxy-TIC, whereas taprostene- and iloprost-induced transcriptional responses were markedly attenuated. Collectively, these results indicate that PGI2, taprostene and 15-deoxy-TIC suppress chemokine release from BEAS-2B cells by interacting with a novel IP receptor that we denote here as the “IP2” subtype.
Footnotes
↵ The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.
This work was supported by the Canadian Institutes of Health Research (CIHR) [Grants MOP 68828 (to R.N.), MOP 93742 (to M.G.)]. R.N. is a CIHR New Investigator and an Alberta Innovates—Health Solutions Senior Scholar. M.G. is the recipient of a Tier 1 Canada Research Chair in Pulmonary Pharmacology.
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
doi:10.1124/mol.110.069674.
-
ABBREVIATIONS:
- PGI2
- prostacyclin
- IP
- prostacyclin receptor
- BMY 45778
- 2-[3-[4-[4,5-di(phenyl)-1,3-oxazol-2-yl]-1,3-oxazol-5-yl]phenoxy] acetic acid
- CNS
- central nervous system
- CXCL9
- monokine induced by IFNγ
- CXCL10
- 10-kDa IFNγ-induced protein
- NTS
- nucleus tractus solitarius
- 15R-TIC
- 15R epimer of 16-m-tolyl-17,18,19,20-tetranor isocarbacyclin
- 15-Deoxy-TIC
- 15-deoxy-16-(m-tolyl)-17,18,19,20-tetranorisocarbacyclin
- RO3244794
- R-3-(4-fluoro-phenyl)-2-(5-(4-fluoro-phenyl)-benzofuran-2-ylmethoxycarbonylamino)-propionic acid
- BWA A868C
- 3-benzyl-5-(6-carboxyhexyl)-1-(2-cyclohexyl-2-ydroxyethylamino) hydantoin
- PGE2
- prostaglandin E2
- ONO-AE1-259
- (Z)-7-[(1R,2S,3R,5R)-5-chloro-3-hydroxy-2-[(E,4S)-4-hydroxy-4-(1-prop-2-enylcyclobutyl)but-1-enyl]cyclopentyl]hept-5-anoic acid
- L-798,106
- 5-bromo-2-methoxy-N-[3-(2-naphthalen-2-yl-methylphenyl)acryloyl]-benzene sulfonamide
- L-161,982
- 5-butyl-2,4-dihydro-[[2′-[N-(5-methyl-2-thiophene-carbonyl)sulfamoyl]biphenyl-4-yl]methyl]-2-[(2-trifluoromethyl) phenyl]-1,2,4-triazol-3-one
- CRE
- cAMP response element
- GRE
- glucocorticoid response element
- HEKm
- human embryonic kidney
- IPR-HEK
- HEK-293 cells overexpressing the hrIP receptor
- IFN
- interferon
- ELISA
- enzyme-linked immunosorbent assay
- siRNA
- small interfering RNA
- PDE
- phosphodiesterase
- CMV
- cytomegalovirus
- PKA
- cAMP-dependent protein kinase
- ANOVA
- analysis of variance
- UC
- universal negative control.
- Received October 27, 2010.
- Accepted December 20, 2010.
- Copyright © 2011 The American Society for Pharmacology and Experimental Therapeutics
MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|