The signaling events underlying oral mucosal inflammatory responses to P. gingivalis and its key endotoxin, lipopolysaccharide (LPS), relay primarily on the LPS engagement of Toll-like receptor-4 (TLR4), and the activ...The signaling events underlying oral mucosal inflammatory responses to P. gingivalis and its key endotoxin, lipopolysaccharide (LPS), relay primarily on the LPS engagement of Toll-like receptor-4 (TLR4), and the activation of IκB-kinase complex (IKK) and mitogen-activated protein kinases (MAPKs that exert their control over transcription factors implicated in the regulation of iNOS and COX-2 proinflammatory genes expression). Since spleen tyrosine kinase (Syk) has emerged recently as a major amplifier in the production of proinflammatory mediators, we investigated the process of recruitment and interaction of Syk with TLR4 in salivary gland acinar cells in response to P. gingivalis LPS. Our findings revealed that stimulation of the acinar cells with the LPS leads to protein kinase Cδ (PKCδ)-mediated phosphorylation of Syk on Ser which results in its localization with the membrane associated TLR4 complex and the activation through phosphorylation on Tyr. Further, our results support the involvement of Syk in the amplification of transcription factors involved in the assembly and expression of transcription complexes associated with the induction in COX-2 and iNOS genes. Therefore, our data suggest that PKCδ is a primary linchpin affecting the Syk recruitment to the membrane localized TLR4, and hence affects the efficiency of the kinase activation and the magnitude of oral mucosal inflammatory response to P. gingivalis.展开更多
Up-regulation in salivary gland acinar cell MMP-9 secretion in response to proinflammatory challenge by periodontopathic bacterium, P. gingivalis relays heavily on the factors that influence the protein processing at ...Up-regulation in salivary gland acinar cell MMP-9 secretion in response to proinflammatory challenge by periodontopathic bacterium, P. gingivalis relays heavily on the factors that influence the protein processing at the level of endoplasmic reticulum-to-Golgi trafficking, and occurs in concert with the changes in the stability dynamics of the major cytoskeleton polymeric structures, microtubules (MTs). In this study, we report that P. gingivalis LPS-elicited induction in the acinar cell MMP-9 secretion is accompanied by the enhancement in MT stabilization, while the modulatory influence of peptide hormone, ghrelin, is associated with MT destabilization. Further, we reveal that the changes in MT dynamics induced by the LPS and ghrelin occur through signal-regulated α-tubulin phosphorylation on Ser/Tyr. The LPS effect is reflected in a marked increase in PKCδ-mediated α-tubulin phosphorylation on Ser, whereas the modulatory influence of ghrelin on MT dynamics is manifested in by SFK-dependent phosphorylation of α-tubulin on Tyr. Moreover, we show that that the changes in MT dynamics, conferred by the LPS and ghrelin, affect the Golgi localization of GTP-Arf1 and the recruitment and activation of PKD2. The findings underscore the role of signal-regulated changes in MT stability dynamics through PKCδ/SFK-mediated α-tubulin phosphorylation on Ser/Tyr in controlling the salivary gland acinar cell MMP-9 secretion in response to P. gingivalis LPS as well as its modulation by ghrelin.展开更多
文摘The signaling events underlying oral mucosal inflammatory responses to P. gingivalis and its key endotoxin, lipopolysaccharide (LPS), relay primarily on the LPS engagement of Toll-like receptor-4 (TLR4), and the activation of IκB-kinase complex (IKK) and mitogen-activated protein kinases (MAPKs that exert their control over transcription factors implicated in the regulation of iNOS and COX-2 proinflammatory genes expression). Since spleen tyrosine kinase (Syk) has emerged recently as a major amplifier in the production of proinflammatory mediators, we investigated the process of recruitment and interaction of Syk with TLR4 in salivary gland acinar cells in response to P. gingivalis LPS. Our findings revealed that stimulation of the acinar cells with the LPS leads to protein kinase Cδ (PKCδ)-mediated phosphorylation of Syk on Ser which results in its localization with the membrane associated TLR4 complex and the activation through phosphorylation on Tyr. Further, our results support the involvement of Syk in the amplification of transcription factors involved in the assembly and expression of transcription complexes associated with the induction in COX-2 and iNOS genes. Therefore, our data suggest that PKCδ is a primary linchpin affecting the Syk recruitment to the membrane localized TLR4, and hence affects the efficiency of the kinase activation and the magnitude of oral mucosal inflammatory response to P. gingivalis.
文摘Up-regulation in salivary gland acinar cell MMP-9 secretion in response to proinflammatory challenge by periodontopathic bacterium, P. gingivalis relays heavily on the factors that influence the protein processing at the level of endoplasmic reticulum-to-Golgi trafficking, and occurs in concert with the changes in the stability dynamics of the major cytoskeleton polymeric structures, microtubules (MTs). In this study, we report that P. gingivalis LPS-elicited induction in the acinar cell MMP-9 secretion is accompanied by the enhancement in MT stabilization, while the modulatory influence of peptide hormone, ghrelin, is associated with MT destabilization. Further, we reveal that the changes in MT dynamics induced by the LPS and ghrelin occur through signal-regulated α-tubulin phosphorylation on Ser/Tyr. The LPS effect is reflected in a marked increase in PKCδ-mediated α-tubulin phosphorylation on Ser, whereas the modulatory influence of ghrelin on MT dynamics is manifested in by SFK-dependent phosphorylation of α-tubulin on Tyr. Moreover, we show that that the changes in MT dynamics, conferred by the LPS and ghrelin, affect the Golgi localization of GTP-Arf1 and the recruitment and activation of PKD2. The findings underscore the role of signal-regulated changes in MT stability dynamics through PKCδ/SFK-mediated α-tubulin phosphorylation on Ser/Tyr in controlling the salivary gland acinar cell MMP-9 secretion in response to P. gingivalis LPS as well as its modulation by ghrelin.
