Endogenous G<sub>s</sub>-Coupled Receptors in Smooth Muscle Exhibit Differential Susceptibility to GRK2/3-Mediated Desensitization

Kong, Kok Choi; Uma, G.; Martin, Thomas J.; Anz, Candace B.; Hou, Yan; Misior, Anna M.; Pascual, Rodolfo M.; Deshpande, Deepak A.; Penn, Raymond B.

doi:10.1021/bi801056w

Cited by 42 publications

(58 citation statements)

References 57 publications

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“…Mak and coworkers have indicated that decreasing the expression of GRK-2 within the airways may lessen b 2 -AR desensitization (30). This observation is supported by a recent study from Kong and colleagues, which reported that inhibition of endogenous GRK2 and GRK3 in ASM is associated with increases in b 2 -AR acute signaling (31). Together, these results indicate that repeated bouts of moderate-intensity aerobic exercise may attenuate AHR by decreasing GRK-2-mediated desensitization of b 2 -AR.…”

Section: Discussionmentioning

confidence: 79%

Repeated Bouts of Moderate-Intensity Aerobic Exercise Reduce Airway Reactivity in a Murine Asthma Model

Hewitt

Estell²,

Davis³

et al. 2010

Am J Respir Cell Mol Biol

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We have reported that moderate-intensity aerobic exercise training attenuates airway inflammation in mice sensitized/challenged with ovalbumin (OVA). The current study determined the effects of repeated bouts of aerobic exercise at a moderate intensity on airway hyperresponsiveness (AHR) in these mice. Mice were sensitized/ challenged with OVA or saline and exercised at a moderate intensity 3 times/week for 4 weeks. At protocol completion, mice were analyzed for changes in AHR via mechanical ventilation. Results show that exercise decreased total lung resistance 60% in OVAtreated mice as compared with controls; exercise also decreased airway smooth muscle (ASM) thickness. In contrast, exercise increased circulating epinephrine levels 3-fold in saline-and OVAtreated mice. Because epinephrine binds b 2 -adrenergic receptors (AR), which facilitate bronchodilatation, the role of b 2 -AR in exercise-mediated improvements in AHR was examined. Application of the b 2 -AR antagonist butoxamine HCl blocked the effects of exercise on lung resistance in OVA-treated mice. In parallel, ASM cells were examined for changes in the protein expression of b 2 -AR and G-protein receptor kinase-2 (GRK-2); GRK-2 promotes b 2 -AR desensitization. Exercise had no effect on b 2 -AR expression in ASM cells of OVA-treated mice; however, exercise decreased GRK-2 expression by 50% as compared with controls. Exercise also decreased prostaglandin E 2 (PGE 2 ) production 5-fold, but had no effect on E prostanoid-1 (EP1) receptor expression within the lungs of OVA-treated mice; both PGE 2 and the EP1 receptor have been implicated in b 2 -AR desensitization. Together, these data indicate that moderate-intensity aerobic exercise training attenuates AHR via a mechanism that involves b 2 -AR.Keywords: asthma; airway hyperresponsiveness; exercise; b 2 -adrenergic receptor Allergic or atopic asthma, the most common form of asthma, is identified by the presence of characteristic clinical symptoms of wheezing, chest tightness, dyspnea and cough, and by the presence of reversible airway narrowing and/or airway hyperresponsiveness (AHR) to a variety of inhaled bronchoconstrictor stimuli. For the treatment of asthma-associated AHR, patients are typically administered inhaled, long-acting b 2 -agonists. b 2 -agonists bind to and activate b 2 -adrenergic receptors (b 2 -AR), which are expressed on a variety of cell types, including airway smooth muscle (ASM) cells, airway epithelial cells, and mast cells (1).Several clinical studies suggest that continued aerobic exercise training improves the overall physical fitness and health of individuals with asthma and reduces their disease-related hospital admissions (2-4); these studies also observed improvements in exercise-induced bronchoconstriction after physical training. We have reported previously that moderate intensity aerobic exercise training reduces lung inflammatory responses in an ovalbumin (OVA)-driven mouse model of pulmonary inflammation (5, 6).Repetitive exercise increases the levels of circulating...

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Section: Discussionmentioning

confidence: 79%

Repeated Bouts of Moderate-Intensity Aerobic Exercise Reduce Airway Reactivity in a Murine Asthma Model

Hewitt

Estell²,

Davis³

et al. 2010

Am J Respir Cell Mol Biol

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“…There is indeed evidence that human EP4 receptors can be phosphorylated by GRK2 (Neuschäfer-Rube et al, 1999). Conversely, PGE 2 -induced cAMP production in smooth muscle cells is unaffected in conditions of low GRK2 (Kong et al, 2008). We cannot exclude that low GRK2 in nociceptors has an additional effect upstream of cAMP, e.g., at the level of G-protein coupling to the receptor (Dina et al, 2009).…”

Section: Discussionmentioning

confidence: 89%

Low Nociceptor GRK2 Prolongs Prostaglandin E₂Hyperalgesia via Biased cAMP Signaling to Epac/Rap1, Protein Kinase Cε, and MEK/ERK

et al. 2010

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Hyperexcitability of peripheral nociceptive pathways is often associated with inflammation and is an important mechanism underlying inflammatory pain. Here we describe a completely novel mechanism via which nociceptor G-protein-coupled receptor kinase 2 (GRK2) contributes to regulation of inflammatory hyperalgesia. We show that nociceptor GRK2 is downregulated during inflammation. In addition, we show for the first time that prostaglandin E 2 (PGE 2 )-induced hyperalgesia is prolonged from Ͻ6 h in wild-type (WT) mice to 3 d in mice with low GRK2 in Na v 1.8 ϩ nociceptors (SNS-GRK2 ϩ/Ϫ mice). This prolongation of PGE 2 hyperalgesia in SNS-GRK2 ϩ/Ϫ mice does not depend on changes in the sensitivity of the prostaglandin receptors because prolonged hyperalgesia also developed in response to 8-Br-cAMP. PGE 2 or cAMP-induced hyperalgesia in WT mice is PKA dependent. However, PKA activity is not required for hyperalgesia in SNS-GRK2 ϩ/Ϫ mice. SNS-GRK2 ϩ/Ϫ mice developed prolonged hyperalgesia in response to the Exchange proteins directly activated by cAMP (Epac) activator 8-pCPT-2Ј-O-Me-cAMP (8-pCPT). Coimmunoprecipitation experiments showed that GRK2 binds to Epac1. In vitro, GRK2 deficiency increased 8-pCPT-induced activation of the downstream effector of Epac, Rap1, and extracellular signal-regulated kinase (ERK). In vivo, inhibition of MEK1 or PKC prevented prolonged PGE 2 , 8-Br-cAMP, and 8-pCPT hyperalgesia in SNS-GRK2 ϩ/Ϫ mice. In conclusion, we discovered GRK2 as a novel Epac1-interacting protein. A reduction in the cellular level of GRK2 enhances activation of the Epac-Rap1 pathway. In vivo, low nociceptor GRK2 leads to prolonged inflammatory hyperalgesia via biased cAMP signaling from PKA to Epac-Rap1, ERK/PKC pathways.

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“…Our previously published studies demonstrated that PGE2 promotes the cAMP-dependent activation of PKA and phosphorylation of VASP in HASM cells via the prostaglandin E2 (EP2) receptor (25,26), which, in contrast to b 2 AR, is relatively resistant to agonist-specific desensitization. Indeed, the accumulation of cAMP and of PKA during both acute and chronic with agonists were markedly greater with PGE2 compared with b 2 AR agonists (14,(25)(26)(27)(28) with regard to greater efficiency in the inhibition of HASM cell growth (26,29) and migration (6). Indeed, our published data show that, in contrast to b 2 AR agonists that transiently increase the phosphorylation of VASP but decrease in effectiveness by 3 hours, PGE2 promotes a PKA-dependent phosphorylation of VASP that is sustained for up to 18 hours, suggesting that prolonged exposure to PGE2 does not desensitize EP2 receptors (25).…”

Section: Discussionmentioning

confidence: 99%

“…Such differences between b-agonists and PGE2 may be explained by differential mechanisms of b 2 AR and EP2 receptor desensitization in HASM cells. Our previous data demonstrate that, in HASM cells, the desensitization of the b 2 AR receptor is selectively mediated by G proteincoupled receptor kinases 2/3 (GRK2/3) that exert little effect on EP2 receptor functions (26).…”

Section: Discussionmentioning

confidence: 99%

β₂-Adrenergic Receptor Agonists Modulate Human Airway Smooth Muscle Cell Migration via Vasodilator-Stimulated Phosphoprotein

Goncharova

Goncharov

Zhao

et al. 2012

Am J Respir Cell Mol Biol

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Severe asthma manifests as airway remodeling and irreversible airway obstruction, in part because of the proliferation and migration of human airway smooth muscle (HASM) cells. We previously reported that cyclic adenosine monophosphate-mobilizing agents, including b 2 -adrenergic receptor (b 2 AR) agonists, which are mainstay of asthma therapy, and prostaglandin E2 (PGE2), inhibit the migration of HASM cells, although the mechanism for this migration remains unknown. Vasodilator-stimulated phosphoprotein (VASP), an anticapping protein, modulates the formation of actin stress fibers during cell motility, and is negatively regulated by protein kinase A (PKA)-specific inhibitory phosphorylation at serine 157 (Ser157). Here, we show that treatment with b 2 AR agonists and PGE2 induces the PKA-dependent phosphorylation of VASP and inhibits the migration of HASM cells. The stable expression of PKA inhibitory peptide and the small interfering (si) RNA-induced depletion of VASP abolish the inhibitory effects of albuterol and PGE2 on the migration of HASM cells. Importantly, prolonged treatment with albuterol prevents the agonist-induced phosphorylation of VASP at Ser157, and reverses the inhibitory effects of albuterol and formoterol, but not PGE2, on the basal and PDGF-induced migration of HASM cells. Collectively, our data demonstrate that b 2 AR agonists selectively inhibit the migration of HASM cells via a b 2 AR/PKA/ VASP signaling pathway, and that prolonged treatment with albuterol abolishes the inhibitory effect of b-agonists on the phosphorylation of VASP and migration of HASM cells because of b 2 AR desensitization.Keywords: airway hyperresponsiveness; b 2 -adrenergic receptor desensitization; protein kinase A; albuterol; formoterol Human airway smooth muscle (HASM) hyperplasia and remodeling are characteristic features of airways that contribute to their irreversible obstruction in patients with severe asthma. Accumulating evidence suggests that cell migration contributes to airway smooth muscle hyperplasia and remodeling (1, 2). Recently, the migration of airway smooth muscle (ASM) cells toward the epithelium and lumen of the airway was reported as a potential contributor to the increased smooth muscle mass in patients with asthma (3, 4). Further, cell-culture studies show that mitogens and inflammatory mediators involved in asthma pathogenesis and pharmacological agents in current used for the treatment of asthma modulate the migration of ASM cells (1,5,6). Taken together, these studies suggest that the migration of ASM cells contributes to ASM cell hyperplasia under asthmarelated conditions (1). Although the role of HASM hyperplasia in asthma is well established, the molecular mechanisms regulating the migration of HASM cells under asthma-related conditions are poorly understood (1).Evidence demonstrates that cyclic adenosine monophosphate (cAMP)-inducing agents, including the long-acting b 2 -adrenergic receptor (b 2 AR) agonist formoterol, inhibit the agonist-dependent migration of ASM cells (5, 7). We p...

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Endogenous G_s-Coupled Receptors in Smooth Muscle Exhibit Differential Susceptibility to GRK2/3-Mediated Desensitization

Cited by 42 publications

References 57 publications

Repeated Bouts of Moderate-Intensity Aerobic Exercise Reduce Airway Reactivity in a Murine Asthma Model

Repeated Bouts of Moderate-Intensity Aerobic Exercise Reduce Airway Reactivity in a Murine Asthma Model

Low Nociceptor GRK2 Prolongs Prostaglandin E₂Hyperalgesia via Biased cAMP Signaling to Epac/Rap1, Protein Kinase Cε, and MEK/ERK

β₂-Adrenergic Receptor Agonists Modulate Human Airway Smooth Muscle Cell Migration via Vasodilator-Stimulated Phosphoprotein

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Endogenous Gs-Coupled Receptors in Smooth Muscle Exhibit Differential Susceptibility to GRK2/3-Mediated Desensitization

Cited by 42 publications

References 57 publications

Repeated Bouts of Moderate-Intensity Aerobic Exercise Reduce Airway Reactivity in a Murine Asthma Model

Repeated Bouts of Moderate-Intensity Aerobic Exercise Reduce Airway Reactivity in a Murine Asthma Model

Low Nociceptor GRK2 Prolongs Prostaglandin E2Hyperalgesia via Biased cAMP Signaling to Epac/Rap1, Protein Kinase Cε, and MEK/ERK

β2-Adrenergic Receptor Agonists Modulate Human Airway Smooth Muscle Cell Migration via Vasodilator-Stimulated Phosphoprotein

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Endogenous G_s-Coupled Receptors in Smooth Muscle Exhibit Differential Susceptibility to GRK2/3-Mediated Desensitization

Low Nociceptor GRK2 Prolongs Prostaglandin E₂Hyperalgesia via Biased cAMP Signaling to Epac/Rap1, Protein Kinase Cε, and MEK/ERK

β₂-Adrenergic Receptor Agonists Modulate Human Airway Smooth Muscle Cell Migration via Vasodilator-Stimulated Phosphoprotein