Mitogenic Effects of Cytokines on Smooth Muscle Are Critically Dependent on Protein Kinase A and Are Unmasked by Steroids and Cyclooxygenase Inhibitors

Madej

Folia Histochem Cytobiol.

et al. 2013

Uterine myomas represent one of the most frequently manifested benign tumors in women. They originate from smooth muscle cells of myometrium or its blood vessels. Many studies suggest that inflammation and pro-inflammatory factors may play a role in the carcinogenesis with an involvement of the transcription factor NF-kB which activity can be controlled by various environmental factors, including many cytokines. The aim of the study was to investigate the expression of NF-B, interleukin-1b (IL-1b), tumor necrosis factor a (TNF-a), cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) in myometrium and uterine myomas of women of various age. The expression of NF-kB, selected cytokines and enzymes was estimated in women of reproductive or perimenopausal age by semiquantitative immunohistochemistry. The expression of the examined proteins was higher in myomas than in control myometrium and was dependent on the size of myomas and the age of women. However, the expression of the cytoplasmic NF-kB observed in uterine myomas was independent on the size of myomas and no significant differences were observed in the number of stained nuclei between control and myoma groups. Thus, the expression of proinflammatory factors in myomas was not accompanied by the nuclear activation of NF-kB p65. The results of our study indicate that the examined factors may be involved in the pathogenesis of benign tumors and not only malignant diseases.

Section: Discussionmentioning

confidence: 92%

Immunohistochemical localization of selected pro-inflammatory factors in uterine myomas and myometrium in women of various ages

Madej

Folia Histochem Cytobiol.

et al. 2013

Am J Respir Cell Mol Biol

“…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%

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

Goncharova

Goncharov

Zhao

et al. 2012

Self Cite

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...

American Journal of Physiology-Lung Cellular and Molecular Phys

“…We have recently demonstrated that PKA mediates the antimitogenic effect of several agents on ASM proliferation (37,39,55). To assess the potential role of PKA in the growth inhibitory effect of TAS2R agonists, we stably expressed PKI, a PKA inhibitory peptide, in ASM cultures as described previously (36,37,55).…”

Section: Tas2r Agonist-mediated Antimitogenic Effect Does Not Involvementioning

confidence: 99%

“…To assess the potential role of PKA in the growth inhibitory effect of TAS2R agonists, we stably expressed PKI, a PKA inhibitory peptide, in ASM cultures as described previously (36,37,55). PDGF-induced ASM growth was similarly inhibited by TAS2R agonists, chloroquine and quinine, in both GFP-and GFP-PKI-expressing ASM cultures (Fig.…”

Section: Tas2r Agonist-mediated Antimitogenic Effect Does Not Involvementioning

confidence: 99%

“…In addition to their lack of effect in vivo, both corticosteroids and ␤-agonists have limited efficacy in inhibiting ASM proliferation by relevant mitogens in cell-based assays (5,6,10,18,21,28,30,47,55). Our previous studies have demonstrated that protein kinase A (PKA) plays a central role in mediating the functional effects of ␤-agonists on ASM (37,39,55). However, ␤-agonist-stimulated PKA activity in ASM appears constrained by ␤ 2 -adrenoceptor desensitization (4,13), rendering ␤-agonists relatively weak antimitogenic agents.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Antimitogenic effect of bitter taste receptor agonists on airway smooth muscle cells

Sharma

Panebra

Pera

et al. 2016

Self Cite

-Airway remodeling is a hallmark feature of asthma and chronic obstructive pulmonary disease. Clinical studies and animal models have demonstrated increased airway smooth muscle (ASM) mass, and ASM thickness is correlated with severity of the disease. Current medications control inflammation and reverse airway obstruction effectively but have limited effect on remodeling. Recently we identified the expression of bitter taste receptors (TAS2R) on ASM cells, and activation with known TAS2R agonists resulted in ASM relaxation and bronchodilation. These studies suggest that TAS2R can be used as new therapeutic targets in the treatment of obstructive lung diseases. To further establish their effectiveness, in this study we aimed to determine the effects of TAS2R agonists on ASM growth and promitogenic signaling. Pretreatment of healthy and asthmatic human ASM cells with TAS2R agonists resulted in a dose-dependent inhibition of ASM proliferation. The antimitogenic effect of TAS2R ligands was not dependent on activation of protein kinase A, protein kinase C, or high/intermediateconductance calcium-activated K ϩ channels. Immunoblot analyses revealed that TAS2R agonists inhibit growth factor-activated protein kinase B phosphorylation without affecting the availability of phosphatidylinositol 3,4,5-trisphosphate, suggesting TAS2R agonists block signaling downstream of phosphatidylinositol 3-kinase. Furthermore, the antimitogenic effect of TAS2R agonists involved inhibition of induced transcription factors (activator protein-1, signal transducer and activator of transcription-3, E2 factor, nuclear factor of activated T cells) and inhibition of expression of multiple cell cycle regulatory genes, suggesting a direct inhibition of cell cycle progression. Collectively, these findings establish the antimitogenic effect of TAS2R agonists and identify a novel class of receptors and signaling pathways that can be targeted to reduce or prevent airway remodeling as well as bronchoconstriction in obstructive airway disease. asthma; airway remodeling; G protein-coupled receptor; type 2 taste receptors G PROTEIN-COUPLED RECEPTOR (GPCR) signaling plays a vital role in the regulation of airway smooth muscle (ASM) contraction, relaxation, and proliferation (4, 12). Exaggerated presentation of procontractile GPCR agonists in the airways during allergic inflammation contributes to bronchoconstriction in obstructive airway disease such as asthma. Another salient feature of inflammatory airway diseases is airway remodeling that is characterized by excessive proliferation and accumulation of resident cells, including ASM cells. Animal models demonstrate ASM mass is increased by allergic airway inflammation, while human studies demonstrate a progressive increase in ASM mass in asthmatic subjects that increases both dynamic and fixed airway resistance, limiting the effectiveness of current rescue bronchodilators (11,21,22,26). Current antiasthma therapies, including ␤-agonists and corticosteroids, aim at alleviating bronchoconstriction and infl...