Induction of Regulator of G-Protein Signaling 2 Expression by Long-Acting β₂-Adrenoceptor Agonists and Glucocorticoids in Human Airway Epithelial Cells

Abstract

In asthma and chronic obstructive pulmonary disease (COPD) multiple mediators act on Ga q -linked G-protein-coupled receptors (GPCRs) to cause bronchoconstriction. However, acting on the airway epithelium, such mediators may also elicit inflammatory responses. In human bronchial epithelial BEAS-2B cells (bronchial epithelium 1 adenovirus 12-SV40 hybrid), regulator of G-protein signaling (RGS) 2 mRNA and protein were synergistically induced in response to combinations of long-acting b 2 -adrenoceptor agonist (LABA) (salmeterol, formoterol) plus glucocorticoid (dexamethasone, fluticasone propionate, budesonide). Equivalent responses occurred in primary human bronchial epithelial cells. Concentrations of glucocorticoid plus LABA required to induce RGS2 expression in BEAS-2B cells were consistent with the levels achieved therapeutically in the lungs. As RGS2 is a GTPase-activating protein that switches off Ga q , intracellular free calcium ([Ca 21 ] i ) flux was used as a surrogate of responses induced by histamine, methacholine, and the thromboxane receptor agonist U46619. This was significantly attenuated by salmeterol plus dexamethasone pretreatment, or RGS2 overexpression, and the protective effect of salmeterol plus dexamethasone was abolished by RGS2 RNA silencing. Although methacholine and U46619 induced interleukin-8 (IL-8) release and this was inhibited by RGS2 overexpression, the repression of U46619-induced IL-8 release by salmeterol plus dexamethasone was unaffected by RGS2 knockdown. Given a role for Ga q -mediated pathways in inducing IL-8 release, we propose that RGS2 acts redundantly with other effector processes to repress IL-8 expression. Thus, RGS2 expression is a novel effector mechanism in the airway epithelium that is induced by glucocorticoid/LABA combinations. This could contribute to the efficacy of glucocorticoid/LABA combinations in asthma and COPD.

Chronic exposure to cannabinoids during adolescence causes long‐lasting behavioral deficits in adult mice

“…stress, drug exposure, changes in neurotransmitter signaling, etc. (Holden et al , 2014; Kach et al , 2012). In particular, RGS7 plays key roles in the regulation of several biological processes such as vision, memory, motor control, reward behavior and nociception (Anderson et al , 2009; Orlandi et al , 2015).…”

“…Because the most prominent behavioral deficits reported in the current study were found in those animals chronically treated with either lowest or highest dose of the drug during adolescence, we directed further investigation on endocannabinoid content, epigenetic and transcriptional gene regulation level under these conditions. We studied Rgs7 as a candidate methylated gene for the following reasons: RGS proteins are active regulators of G protein‐coupled receptors signaling (Sjögren, 2011; Xie and Martemyanov, 2011), they are tightly regulated in response to non‐cannabinoid drugs of abuse (Holden et al , 2014; Kach et al , 2012; Sjögren, 2011) and also involved in hippocampus‐dependent learning and memory (Ostrovskaya et al , 2014). In brief, we report that 3 weeks of WIN exposure during adolescence are enough to impair hippocampus‐dependent memory in adulthood.…”

Superiority of Combined Phosphodiesterase PDE3/PDE4 Inhibition over PDE4 Inhibition Alone on Glucocorticoid- and Long-Acting β2-Adrenoceptor Agonist–Induced Gene Expression in Human Airway Epithelial Cells

“…Because this also occurs with glucocorticoid-induced genes, in vivo correlates may account for the benefits of ICS/LABA therapy Kaur et al, 2008). For example, regulator of G-protein signaling 2 (RGS2), which terminates signaling from the heterotrimeric G protein Ga q (Heximer, 2004;Kimple et al, 2009), is bronchoprotective in vivo and may also attenuate cytokine release (Holden et al, , 2014Xie et al, 2012). Importantly, in human airway smooth muscle (ASM) and bronchial epithelial cells, RGS2 expression is induced by LABAs and this is synergistically enhanced and prolonged by glucocorticoids (Holden et al, , 2014.…”

“…For example, regulator of G-protein signaling 2 (RGS2), which terminates signaling from the heterotrimeric G protein Ga q (Heximer, 2004;Kimple et al, 2009), is bronchoprotective in vivo and may also attenuate cytokine release (Holden et al, , 2014Xie et al, 2012). Importantly, in human airway smooth muscle (ASM) and bronchial epithelial cells, RGS2 expression is induced by LABAs and this is synergistically enhanced and prolonged by glucocorticoids (Holden et al, , 2014. Likewise, the expression of a variety of other genes with antiinflammatory potential are induced by glucocorticoids and/or LABAs and could contribute to the efficacy of ICS/LABA combination therapy (Giembycz and Newton, 2014).…”

Cistrome-based Cooperation between Airway Epithelial Glucocorticoid Receptor and NF-κB Orchestrates Anti-inflammatory Effects

“…chromatin-immunoprecipitation of GR followed by deep sequencing, or ChIP-seq) indicated that interactions between GR and inflammatory transcription factors do not necessarily lead to repressive regulatory outcomes (11)(12)(13)(14). Moreover, an increasing number of GR-induced genes are now recognized as contributing to inflammatory repression by GCs (15)(16)(17). It is also clear that GR actions are subordinate to cellular and chromatin context (18 -22), with wide variations in both GR binding and activity occurring between cell types and as a consequence of exposure to different cytokines and growth factors (12,23).…”