The dopamine D1 receptor is expressed and induces CREB phosphorylation and MUC5AC expression in human airway epithelium

Abstract

BackgroundDopamine receptors comprise two subgroups, Gs protein-coupled “D1-like” receptors (D1, D5) and Gi-coupled “D2-like” receptors (D2, D3, D4). In airways, both dopamine D1 and D2 receptors are expressed on airway smooth muscle and regulate airway smooth muscle force. However, functional expression of the dopamine D1 receptor has never been identified on airway epithelium. Activation of Gs-coupled receptors stimulate adenylyl cyclase leading to cyclic AMP (cAMP) production, which is known to induce mucus overproduction through the cAMP response element binding protein (CREB) in airway epithelial cells. We questioned whether the dopamine D1 receptor is expressed on airway epithelium, and whether it promotes CREB phosphorylation and MUC5AC expression.MethodsWe evaluated the protein expression of the dopamine D1 receptor on native human airway epithelium and three sources of cultured human airway epithelial cells including primary cultured airway epithelial cells, the bronchial epithelial cell line (16HBE14o-), and the pulmonary mucoepidermoid carcinoma cell line (NCI-H292) using immunohistochemistry and immunoblotting. To characterize the stimulation of cAMP through the dopamine D1 receptor, 16HBE14o- cells and NCI-H292 cells were treated with dopamine or the dopamine D1 receptor agonists (SKF38393 or A68930) before cAMP measurements. The phosphorylation of CREB by A68930 in both 16HBE14o- and NCI-H292 cells was measured by immunoblot. The effect of dopamine or A68930 on the expression of MUC5AC mRNA and protein in NCI-H292 cells was evaluated by real-time PCR and immunofluorescence staining, respectively.ResultsThe dopamine D1 receptor protein was detected in native human airway epithelium and three sources of cultured human airway epithelial cells. Dopamine or the dopamine D1-like receptor agonists stimulated cAMP production in 16HBE14o- cells and NCI-H292 cells, which was reversed by the selective dopamine D1-like receptor antagonists (SCH23390 or SCH39166). A68930 significantly increased phosphorylation of CREB in both 16HBE14o- and NCI-H292 cells, which was attenuated by the inhibitors of PKA (H89) and MEK (U0126). Expression of MUC5AC mRNA and protein were also increased by either dopamine or A68930 in NCI-H292 cells.ConclusionsThese results suggest that the activation of the dopamine D1 receptor on human airway epithelium could induce mucus overproduction, which could worsen airway obstructive symptoms.

Tyrosine hydroxylase conditional KO mice reveal peripheral tissue-dependent differences in dopamine biosynthetic pathways

“…7 , C , D , and F ), to evaluate whether DA can be synthesized from tyrosine and/or circulating DOPA. Because the dopamine D1 receptor (D1R) plays an important role in DA function in these peripheral tissues ( 10 , 26 , 27 , 28 , 29 ), we used D1R reporter mice, which express β-galactosidase under the D1R promoter ( 30 ), to visualize D1R-expressing cells by X-gal staining.…”

“…8 , C and D ), they may produce DA by themselves. Because D1R expression in airway epithelial cells has been reported ( 28 ), DA function in these cells may be an autocrine signal. As DA synthesis in the lung was thought to be from circulating DOPA ( 8 , 47 ), to our knowledge, this is the first report of DA synthetic pathway by TH and AADC in the lung.…”

Dopamine D1 receptor agonist alleviates acute lung injury via modulating inflammatory responses in macrophages and barrier function in airway epithelial cells

“…Dopamine D1-like receptors have been found in several lung cell types, such as airway epithelial cells [ 42 ] and lung fibroblasts [ 43 ], as well as immunocytes [ 18 ]. Activation of D1 receptors was believed to exert beneficial effects against pulmonary pathological processes.…”

Monoamine Oxidase-B Inhibitor Reduction in Pro-Inflammatory Cytokines Mediated by Inhibition of cAMP-PKA/EPAC Signaling

“…Dopamine receptors are grouped into two subclasses: D1-like (DR1, DR5) and D2-like (DR2, DR3, DR4), are expressed in CNS and non-CNS locations and their expression varies based on tissue type ( Beaulieu and Gainetdinov, 2011 ; Handa et al, 2019 ). Epithelial cells do express DR1, DR2 and DR3 ( Mao et al, 2015 ; Matsuyama et al, 2018 ; Reyes-Resina et al, 2020 ). SiHa cells were found to express D1-like (DR1, DR5) receptors at higher levels than the DR2.…”