Targeted inhibition of Gq signaling induces airway relaxation in mouse models of asthma

Obstructive lung diseases are common causes of disability and death worldwide. A hallmark feature is aberrant activation of Gq protein–dependent signaling cascades. Currently, drugs targeting single G protein (heterotrimeric guanine nucleotide–binding protein)–coupled receptors (GPCRs) are used to reduce airway tone. However, therapeutic efficacy is often limited, because various GPCRs contribute to bronchoconstriction, and chronic exposure to receptor-activating medications results in desensitization. We therefore hypothesized that pharmacological Gq inhibition could serve as a central mechanism to achieve efficient therapeutic bronchorelaxation. We found that the compound FR900359 (FR), a membrane-permeable inhibitor of Gq, was effective in silencing Gq signaling in murine and human airway smooth muscle cells. Moreover, FR both prevented bronchoconstrictor responses and triggered sustained airway relaxation in mouse, pig, and human airway tissue ex vivo. Inhalation of FR in healthy wild-type mice resulted in high local concentrations of the compound in the lungs and prevented airway constriction without acute effects on blood pressure and heart rate. FR administration also protected against airway hyperreactivity in murine models of allergen sensitization using ovalbumin and house dust mite as allergens. Our findings establish FR as a selective Gq inhibitor when applied locally to the airways of mice in vivo and suggest that pharmacological blockade of Gq proteins may be a useful therapeutic strategy to achieve bronchorelaxation in asthmatic lung disease

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O-Glycosylation Regulates Ubiquitination and Degradation of the Anti-Inflammatory Protein A20 to Accelerate Atherosclerosis in Diabetic ApoE-Null Mice

Background: Accelerated atherosclerosis is the leading cause of morbidity and mortality in diabetic patients. Hyperglycemia is a recognized independent risk factor for heightened atherogenesis in diabetes mellitus (DM). However, our understanding of the mechanisms underlying glucose damage to the vasculature remains incomplete. Methodology/Principal Findings: High glucose and hyperglycemia reduced upregulation of the NF-κB inhibitory and atheroprotective protein A20 in human coronary endothelial (EC) and smooth muscle cell (SMC) cultures challenged with Tumor Necrosis Factor alpha (TNF), aortae of diabetic mice following Lipopolysaccharide (LPS) injection used as an inflammatory insult and in failed vein-grafts of diabetic patients. Decreased vascular expression of A20 did not relate to defective transcription, as A20 mRNA levels were similar or even higher in EC/SMC cultured in high glucose, in vessels of diabetic C57BL/6 and FBV/N mice, and in failed vein grafts of diabetic patients, when compared to controls. Rather, decreased A20 expression correlated with post-translational O-Glucosamine-N-Acetylation (O-GlcNAcylation) and ubiquitination of A20, targeting it for proteasomal degradation. Restoring A20 levels by inhibiting O-GlcNAcylation, blocking proteasome activity, or overexpressing A20, blocked upregulation of the receptor for advanced glycation end-products (RAGE) and phosphorylation of PKCβII, two prime atherogenic signals triggered by high glucose in EC/SMC. A20 gene transfer to the aortic arch of diabetic ApoE null mice that develop accelerated atherosclerosis, attenuated vascular expression of RAGE and phospho-PKCβII, significantly reducing atherosclerosis. Conclusions: High glucose/hyperglycemia regulate vascular A20 expression via O-GlcNAcylation-dependent ubiquitination and proteasomal degradation. This could be key to the pathogenesis of accelerated atherosclerosis in diabetes

The endocannabinoid anandamide is an airway relaxant in health and disease

Chronic obstructive airway diseases are a global medical burden that is expected to increase in the near future. However, the underlying mechanistic processes are poorly understood so far. Herein, we show that the endocannabinoid anandamide (AEA) induces prominent airway relaxation in vitro and in vivo. In contrast to 2-arachidonlyglycerol-induced airway relaxation, this is mediated by fatty acid amide hydrolase (FAAH)-dependent metabolites. In particular, we identify mouse and also human epithelial and airway smooth muscle cells as source of AEA-induced prostaglandin E2 production and cAMP as direct mediator of AEA-dependent airway relaxation. Mass spectrometry experiments demonstrate reduced levels of endocannabinoid-like compounds in lungs of ovalbumin-sensitized mice indicating a pathophysiological relevance of endocannabinoid signalling in obstructive airway disease. Importantly, AEA inhalation protects against airway hyper-reactivity after ovalbumin sensitization. Thus, this work highlights the AEA/FAAH axis as a critical regulator of airway tone that could provide therapeutic targets for airway relaxation

O-GlcNAcylation and ubiquitination of A20 modulate its expression.

<p>(A) WB analysis of total A20 and co-immunoblotted, overlapping GlcNAc-A20 (RL-2) in SMC cultured in 5, 15 and 30 mM of D-glucose (D-Glu), and treated or not with TNF for 6 h. β-actin was used as a control for loading. (B) WB analysis of WGA captured proteins from SMC cultured in 5 and 30 mM D-Glu demonstrate the presence of glycosylated (GlcNAcA20), and co-immunoblotted, overlapping, ubiquitinated A20 (Ub-A20). (C) WB analysis of cell lysates immunoprecipitated with the A20 antibody from SMC cultured in 5 and 30 mM of D-Glu and treated or not with TNF for 6 h, and analyzed WB for total A20 and GlcNAc-A20 using the RL2 antibody demonstrate increased GlcNAc-A20 in high glucose medium. (D) WB analysis of cell lysates immunoprecipitated with the A20 antibody from SMC cultured in 5 and 30 mM D-Glu and treated or not with TNF for 6 h, and analyzed by WB for total and Ub-A20 demonstrate increased Ub-A20 in high glucose medium. (E) WB analysis of total and overlapping GlcNAc-A20 (RL-2) in SMC cultured in 30 mM D-Glu and treated with DON (prior to TNF) or MG132 (after TNF). (F) WB analysis of total and phospho-A20 in SMC cultured in 5, 15 and 30 mM D-Glu and treated with TNF for 6 h demonstrated that relative phosphorylation levels of A20 (pA20) were not decreased by high glucose, despite decreased TNF-mediated upregulation of A20 protein in cells cultured in high glucose. GAPDH or βactin was checked as a loading control to quantify A20 expression by densitometry. Corrected A20 fold-inductions are listed below the WB. RL2/A20 and Ubiquitin/A20 ratios were also calculated by densitometry. Data shown in A, C, D, and E are representative of 3 independent experiments. Data shown in B and F are representative of 2 independent experiments.</p

LPS-mediated upregulation of A20 protein expression is blunted in aortae of diabetic, as compared to non-diabetic mice.

<p>(A) WB of A20 in abdominal aortae of diabetic and non-diabetic atherosclerosis-prone C57BL/6 and atherosclerosis-resistant FVB/N mice, 8 h after LPS treatment. GAPDH and βactin were used to correct for loading and quantify relative A20 expression by densitometry, as reported below the WB. Data shown are representative of 3 (non-diabetic) and 4 (diabetic) mice per time-point and illustrate the loss of LPS-induced A20 protein in diabetic mice, regardless of strain. The cuts between samples reflect the fact that these samples, while on the same gel and same experiment, were not contiguous. (B) A20 mRNA levels analyzed by real-time PCR 3 to 8 h after LPS injection in mouse abdominal aortae (n = 5 non-diabetic and 7 diabetic mice in C57BL/6 and 3 non-diabetic and 4 diabetic mice in FVB/N). Data shown demonstrates that LPS increases A20 mRNA levels in aortae of diabetic and non-diabetic C57BL/6 and FVB/N, albeit at a greater levels in diabetic mice. Expression of 18S ribosomal RNA was used to normalize expression of A20 mRNA, and the results were presented as mean±SEM of mRNA. Each sample was measured in duplicate.</p