Leukotriene E4 is a full functional agonist for human cysteinyl leukotriene type 1 receptor-dependent gene expression.

Holly R Foster,Tak H Lee,David J Cousins,Elisabeth Fuerst,William Branchett,Grzegorz Woszczek

doi:10.1038/srep20461

Abstract

Leukotriene E4 (LTE4) the most stable of the cysteinyl leukotrienes (cysLTs) binds poorly to classical type 1 (CysLT1) and 2 (CysLT2) receptors although it induces potent responses in human airways in vivo, such as bronchoconstriction, airway hyperresponsiveness and inflammatory cell influx suggesting the presence of a novel receptor that preferentially responds to LTE4. To identify such a receptor two human mast cell lines, LAD2 and LUVA, were selected that differentially responded to LTE4 when analysed by intracellular signalling and gene expression. Comparative transcriptome analysis and recombinant gene overexpression experiments revealed CysLT1 as a receptor responsible for potent LTE4-induced response in LAD2 but not in LUVA cells, an observation confirmed further by gene knockdown and selective inhibitors. Lentiviral overexpression of CysLT1 in LUVA cells augmented intracellular calcium signalling induced by LTE4 but did not restore full agonist responses at the gene expression level. Our data support a model where both an increased expression of Gαq-coupled CysLT1, and sustained intracellular calcium mobilisation and extracellular signal-regulated kinase (Erk) activation, are required for LTE4-mediated regulation of gene expression in human cells. Our study shows for the first time that CysLT1 expression is critically important for responsiveness to LTE4 within a human cell system.

Highlights

Cysteinyl leukotrienes (LTC4, LTD4 and LTE4) play pivotal roles in cell proliferation, differentiation, migration and regulation of immune responses implicated in a wide variety of disorders, including asthma, allergy, atherosclerosis and cancer[1]
This study identifies LTE4 as a fully functional agonist activating human cysLT type 1 (CysLT1) for regulation of gene expression in LAD2 cells only weak, partial agonism of LTE4 signalling could be detected in LUVA cells
Our data suggest that increased expression of CysLT1 and induction of prolonged intracellular signalling are required for LTE4 functional agonism

Summary

Introduction

Cysteinyl leukotrienes (cysLTs) (LTC4, LTD4 and LTE4) play pivotal roles in cell proliferation, differentiation, migration and regulation of immune responses implicated in a wide variety of disorders, including asthma, allergy, atherosclerosis and cancer[1]. LTE4, the most stable of the cysLTs, binds poorly to the classical CysLT1 and CysLT2 and is much less potent than LTC4 and LTD4 in inducing cellular responses in vitro, showing a partial agonistic activity[2,3,4,5] In vivo, it is LTE4 that has shown to be the most potent cysLT in eliciting influx of eosinophils and basophils into bronchial mucosa of asthmatic subjects and in enhancing airway responsiveness to histamine and increasing vascular permeability, suggesting the existence of one or more leukotriene receptors that have not been identified to date[6,7,8,9,10]. We characterize LTE4 as a fully functional agonist activating human CysLT1 and show for the first time that CysLT1 expression is critically important for responsiveness to LTE4 within a human cell system

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