A peptide hormone, ghrelin, recognized for its role in the regulation of nitric oxide production has emerged as an important modulator of oral mucosal inflammatory responses to periodontopathic bacterium, P. gingivali...A peptide hormone, ghrelin, recognized for its role in the regulation of nitric oxide production has emerged as an important modulator of oral mucosal inflammatory responses to periodontopathic bacterium, P. gingivalis. As cSrc kinase plays a major role in controlling the activity of nitric oxide synthase (NOS) system, in this study we investigated the influence of P. gingivalis LPS on the processes of Src activation in rat sublingual gland acinar cells. The LPS-induced enhancement in the activity of inducible (i) iNOS and the impairment in constitutive (c) cNOS were reflected in the suppression in cSrc activity and the extent of its phosphorylation at Tyr416. Further, we show that the countering effect of ghrelin on the LPS-induced changes in cSrc activity and the extent of its phosphorylation was accompanied by a marked reduction in iNOS and the increase in cNOS activation through phosphorylation at Ser1179. Moreover, the effect of ghrelin on cSrc activation was associated with the kinase S-nitrosylation that was susceptible to the blockage by cNOS inhibition. Our findings suggest that P. gingivalis-induced up-regulation in iNOS leads to disturbances in cNOS phosphorylation that exerts the detrimental effect on the processes of cSrc activation through cNOS mediated S-nitrosylation. We also show that the effect of ghrelin on P. gingivalis-induced inflammatory changes are manifested in the enhancement in cSrc activation through S-nitrosylation and the increase in its phosphorylation at Tyr416.展开更多
Disturbances in nitric oxide synthase (NOS) and cyclooxygenase (COX) isozyme systems, manifested by the excessive NO and prostaglandin (PGE2) generation, are well-recognized features of gastric mucosal inflammatory re...Disturbances in nitric oxide synthase (NOS) and cyclooxygenase (COX) isozyme systems, manifested by the excessive NO and prostaglandin (PGE2) generation, are well-recognized features of gastric mucosal inflammatory responses to H. pylori infection. In this study, we report that H. pylori LPS-induced enhancement in gastric mucosal inducible (i) iNOS expression and COX-2 activation was accompanied by the impairment in constitutive (c) cNOS phosphorylation, up-regulation in the inhibitory κB kinase-β (IKKβ) activation and the increase in the transcriptional factor, NF-κB, nuclear translocation. Further, we show that abrogation of cNOS control over NF-κB activation has lead to induction of iNOS expression and COX-2 activation through S-nitrosylation. Moreover, we demonstrate that the modulatory effect of peptide hormone, ghrelin, on the LPS-induced changes was reflected in the increase in Src/Akt-dependent cNOS activation through phosphorylation and the suppression of IKK-β activity through cNOS-mediated IKK-β protein S-nitrosylation. As a result, ghrelin exerted the inhibitory effect on NF-κB nuclear translocation, thus causing the repression of iNOS gene induction and the inhibition in COX-2 activation through iNOS-dependent S-nitrosylation. Our findings point to cNOS activation as a pivotal element in the signaling cascade by which ghrelin exerts modulatory control over proinflammatory events triggered in gastric mucosa by H. pylori infection.展开更多
Disturbances in constitutive nitric oxide synthase (cNOS) activation associated with H. pylori colonization of gastric mucosa are considered of major consequences in defining the extent of inflammatory involvement. As...Disturbances in constitutive nitric oxide synthase (cNOS) activation associated with H. pylori colonization of gastric mucosa are considered of major consequences in defining the extent of inflammatory involvement. As rapid changes in cNOS activation are linked to the enzyme phosphorylation at the specific Ser/Thr residues, we investigated the influence of H. pylori LPS and gastric hormone, ghrelin, on the processes of phosphorylation of these two critical sites in gastric mucosal cells. We show that the LPS-induced reduction in cNOS activity is reflected in the phosphorylation on Thr497, while the countering effect of ghrelin is associated with a rapid increase in cNOS phosphorylation on Ser1179. Further, we demonstrate that cNOS phosphorylation on Thr497 as well as Ser1179 displays dependence on PKCδ. However, while the LPS-induced suppression in cNOS activation shows reliance on the phosphorylation of PKCδ and PI3K on Ser, the effect of ghrelin is manifested by the increase in phosphorylation of PKCδ and PI3K on Tyr, as well as membrane translocation and phosphorylation of Akt on Ser493. Thus, our findings suggest that the LPS-induced suppression in cNOS activation is mediated by PKCδ-controlled phosphorylation of PI3K on Ser that interferes with the membrane recruitment of Akt and promotes cNOS phosphorylation on Thr497, and that ghrelin-elicited up-regulation in cNOS activation relies on the PKCδ-directed phosphorylation of PI3K on Tyr that stimulates the membrane localization of Akt and enhances cNOS phosphorylation on Ser1179.展开更多
Erectile dysfunction （ED） is a major complication of diabetes mellitus （DM）. This study investigates the relationship between ED and the downregulation of constitutive nitric oxide synthase （cNOS） in the corpus ...Erectile dysfunction （ED） is a major complication of diabetes mellitus （DM）. This study investigates the relationship between ED and the downregulation of constitutive nitric oxide synthase （cNOS） in the corpus cavernosum （CC） of diabetic rats. It also examines the effects of udenafil, a phosphodiesterase type 5 （PDE5） inhibitor, on ED and cNOS expression levels. After 16 weeks of daily oral treatment with udenafil in diabetic rats, the intracavernous pressure/mean arterial pressure （ICP/MAP） ratio was recorded to measure erectile function, and cNOS expression was measured using reverse transcriptase （RT）-PCR and immunoblots. Although the ICP/ MAP ratio and the expression levels of endothelial NOS （eNOS） and neuronal NOS （nNOS） in the CC were markedly decreased in diabetic rats, long-term udenafil treatment improved the erectile function and increased cNOS expression compared with diabetic controls. These findings suggest that ED in DM is closely related to decreased cNOS expression in the CC and that udenafil has the ability to compensate for this pathological change by modulating cNOS expression. Udenafil also has an inhibitory role in cyclic guanosine monophosphate （cGMP） degradation.展开更多
文摘A peptide hormone, ghrelin, recognized for its role in the regulation of nitric oxide production has emerged as an important modulator of oral mucosal inflammatory responses to periodontopathic bacterium, P. gingivalis. As cSrc kinase plays a major role in controlling the activity of nitric oxide synthase (NOS) system, in this study we investigated the influence of P. gingivalis LPS on the processes of Src activation in rat sublingual gland acinar cells. The LPS-induced enhancement in the activity of inducible (i) iNOS and the impairment in constitutive (c) cNOS were reflected in the suppression in cSrc activity and the extent of its phosphorylation at Tyr416. Further, we show that the countering effect of ghrelin on the LPS-induced changes in cSrc activity and the extent of its phosphorylation was accompanied by a marked reduction in iNOS and the increase in cNOS activation through phosphorylation at Ser1179. Moreover, the effect of ghrelin on cSrc activation was associated with the kinase S-nitrosylation that was susceptible to the blockage by cNOS inhibition. Our findings suggest that P. gingivalis-induced up-regulation in iNOS leads to disturbances in cNOS phosphorylation that exerts the detrimental effect on the processes of cSrc activation through cNOS mediated S-nitrosylation. We also show that the effect of ghrelin on P. gingivalis-induced inflammatory changes are manifested in the enhancement in cSrc activation through S-nitrosylation and the increase in its phosphorylation at Tyr416.
文摘Disturbances in nitric oxide synthase (NOS) and cyclooxygenase (COX) isozyme systems, manifested by the excessive NO and prostaglandin (PGE2) generation, are well-recognized features of gastric mucosal inflammatory responses to H. pylori infection. In this study, we report that H. pylori LPS-induced enhancement in gastric mucosal inducible (i) iNOS expression and COX-2 activation was accompanied by the impairment in constitutive (c) cNOS phosphorylation, up-regulation in the inhibitory κB kinase-β (IKKβ) activation and the increase in the transcriptional factor, NF-κB, nuclear translocation. Further, we show that abrogation of cNOS control over NF-κB activation has lead to induction of iNOS expression and COX-2 activation through S-nitrosylation. Moreover, we demonstrate that the modulatory effect of peptide hormone, ghrelin, on the LPS-induced changes was reflected in the increase in Src/Akt-dependent cNOS activation through phosphorylation and the suppression of IKK-β activity through cNOS-mediated IKK-β protein S-nitrosylation. As a result, ghrelin exerted the inhibitory effect on NF-κB nuclear translocation, thus causing the repression of iNOS gene induction and the inhibition in COX-2 activation through iNOS-dependent S-nitrosylation. Our findings point to cNOS activation as a pivotal element in the signaling cascade by which ghrelin exerts modulatory control over proinflammatory events triggered in gastric mucosa by H. pylori infection.
文摘Disturbances in constitutive nitric oxide synthase (cNOS) activation associated with H. pylori colonization of gastric mucosa are considered of major consequences in defining the extent of inflammatory involvement. As rapid changes in cNOS activation are linked to the enzyme phosphorylation at the specific Ser/Thr residues, we investigated the influence of H. pylori LPS and gastric hormone, ghrelin, on the processes of phosphorylation of these two critical sites in gastric mucosal cells. We show that the LPS-induced reduction in cNOS activity is reflected in the phosphorylation on Thr497, while the countering effect of ghrelin is associated with a rapid increase in cNOS phosphorylation on Ser1179. Further, we demonstrate that cNOS phosphorylation on Thr497 as well as Ser1179 displays dependence on PKCδ. However, while the LPS-induced suppression in cNOS activation shows reliance on the phosphorylation of PKCδ and PI3K on Ser, the effect of ghrelin is manifested by the increase in phosphorylation of PKCδ and PI3K on Tyr, as well as membrane translocation and phosphorylation of Akt on Ser493. Thus, our findings suggest that the LPS-induced suppression in cNOS activation is mediated by PKCδ-controlled phosphorylation of PI3K on Ser that interferes with the membrane recruitment of Akt and promotes cNOS phosphorylation on Thr497, and that ghrelin-elicited up-regulation in cNOS activation relies on the PKCδ-directed phosphorylation of PI3K on Tyr that stimulates the membrane localization of Akt and enhances cNOS phosphorylation on Ser1179.
文摘Erectile dysfunction （ED） is a major complication of diabetes mellitus （DM）. This study investigates the relationship between ED and the downregulation of constitutive nitric oxide synthase （cNOS） in the corpus cavernosum （CC） of diabetic rats. It also examines the effects of udenafil, a phosphodiesterase type 5 （PDE5） inhibitor, on ED and cNOS expression levels. After 16 weeks of daily oral treatment with udenafil in diabetic rats, the intracavernous pressure/mean arterial pressure （ICP/MAP） ratio was recorded to measure erectile function, and cNOS expression was measured using reverse transcriptase （RT）-PCR and immunoblots. Although the ICP/ MAP ratio and the expression levels of endothelial NOS （eNOS） and neuronal NOS （nNOS） in the CC were markedly decreased in diabetic rats, long-term udenafil treatment improved the erectile function and increased cNOS expression compared with diabetic controls. These findings suggest that ED in DM is closely related to decreased cNOS expression in the CC and that udenafil has the ability to compensate for this pathological change by modulating cNOS expression. Udenafil also has an inhibitory role in cyclic guanosine monophosphate （cGMP） degradation.
