Open AccessDiacylglycerol Kinase Inhibition Reduces Airway Contraction by Negative Feedback Regulation of Gq-Signaling
Author(s) -
Pawan Sharma,
Santosh Kumar Yadav,
Sushrut D. Shah,
Elham Javed,
John Lim,
Shi Pan,
Ajay P. Nayak,
Reynold A. Panettieri,
Raymond B. Penn,
Taku Kambayashi,
Deepak A. Deshpande
Publication year - 2021
Publication title -
american journal of respiratory cell and molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.469
H-Index - 161
eISSN - 1535-4989
pISSN - 1044-1549
DOI - 10.1165/rcmb.2021-0106oc
Subject(s) - diacylglycerol kinase , bronchoconstriction , agonist , gq alpha subunit , phospholipase c , chemistry , g protein coupled receptor , receptor , endocrinology , medicine , protein kinase c , g protein , signal transduction , microbiology and biotechnology , biology , biochemistry , asthma
Exaggerated airway smooth muscle (ASM) contraction regulated by the Gq family of G protein-coupled receptors causes airway hyperresponsiveness in asthma. Activation of Gq-coupled G protein-coupled receptors leads to phospholipase C (PLC)-mediated generation of inositol triphosphate (IP 3 ) and diacylglycerol (DAG). DAG signaling is terminated by the action of DAG kinase (DGK) that converts DAG into phosphatidic acid (PA). Our previous study demonstrated that DGKζ and α isoform knockout mice are protected from the development of allergen-induced airway hyperresponsiveness. Here we aimed to determine the mechanism by which DGK regulates ASM contraction. Activity of DGK isoforms was inhibited in human ASM cells by siRNA-mediated knockdown of DGKα and ζ, whereas pharmacological inhibition was achieved by pan DGK inhibitor I (R59022). Effects of DGK inhibition on contractile agonist-induced activation of PLC and myosin light chain (MLC) kinase, elevation of IP 3, and calcium levels were assessed. Furthermore, we used precision-cut human lung slices and assessed the role of DGK in agonist-induced bronchoconstriction. DGK inhibitor I attenuated histamine- and methacholine-induced bronchoconstriction. DGKα and ζ knockdown or pretreatment with DGK inhibitor I resulted in attenuated agonist-induced phosphorylation of MLC and MLC phosphatase in ASM cells. Furthermore, DGK inhibition decreased Gq agonist-induced calcium elevation and generation of IP 3 and increased histamine-induced production of PA. Finally, DGK inhibition or treatment with DAG analog resulted in attenuation of activation of PLC in human ASM cells. Our findings suggest that DGK inhibition perturbed the DAG:PA ratio, resulting in inhibition of Gq-PLC activation in a negative feedback manner, resulting in protection against ASM contraction.