Porphyromonas gingivalis-Induced GEF Dock180 Activation by Src/PKCδ-Dependent Phosphorylation Mediates PLCγ2 Amplification in Salivary Gland Acinar Cells: Modulatory Effect of Ghrelin


Phospholipase Cγ2 (PLCγ2) plays a pivotal role in mediation of inflammatory reaction to bacterial lipopolysaccharide (LPS) as well as serves as a key target in modulatory influence of the hormone ghrelin. Here we explore the involvement of Rac1 and its activator, guanine nucleotide exchange factor (GEF), Dock180, in mediation of PLCγ2 activation in salivary gland acinar cells in response to P. gingivalis LPS and ghrelin. We show that stimulation of the acinar cells with the LPS leads to up-regulation in Dock and PLCγ2 activation, and is reflected in the membrane translocation of Rac1 and PLCγ2, while the effect of ghrelin is manifested by the suppression in Rac1 translocation. Further, we reveal that stimulation with the LPS leads to Dock180 phosphorylation on Tyr and Ser, while the modulatory influence of ghrelin, manifested by a drop in membrane Rac1-GTP, is asso-ciated with a distinct decrease in Dock180 phosphorylation on Ser. Moreover, we demonstrate that phosphorylation on Tyr remains under the control of Src kinase and is accompanied by Dock180 membrane translocation, while protein kinase Cδ(PKCδ) is involved in the LPS-induced phosphorylation of the membrane-recruited Dock180 on Ser. Thus, our findings underscore the role of Src/PKCδ-mediated GEF Dock180 phosphorylation on Tyr/Ser in modulation of salivary gland acinar cell PLCγ2 activation in response to P. gingivalis as well as ghrelin.

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Slomiany, B. and Slomiany, A. (2015) Porphyromonas gingivalis-Induced GEF Dock180 Activation by Src/PKCδ-Dependent Phosphorylation Mediates PLCγ2 Amplification in Salivary Gland Acinar Cells: Modulatory Effect of Ghrelin. Journal of Biosciences and Medicines, 3, 66-77. doi: 10.4236/jbm.2015.37008.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Ximenz-Fyvie, L.A., Haffajee, A.D. and Socransky, S. (2000) Microrbial Composition of Supra- and Subgingival Plaque in Subjects with Adult Periodontitis. Journal of Clinical Periodontology, 27, 722-732.
[2] Nonnenmacher, C., Mutters, R. and de Jacoby, L.F. (2001) Microbiological Characteristics of Subgingival Microbiota in Adult Periodontitis, Localized Juvenile Periodontitis and Rapidly Progressive Periodontitis Subjects. Clinical Microbiology and Infection, 7, 213-217.
[3] Wang, P.L. and Ohura, K. (2002) Porphyromonas gingivalis Lipopolysaccharide Signaling in Gingival Fibroblasts- CD14 and Toll-Like Receptors. Critical Reviews in Oral Biology and Medicine, 13, 132-142.
[4] Slomiany, B.L. and Slomiany, A. (2010) Constitutive Nitric Oxide Synthase-Mediated Caspase-3 S-Nitrosylation in Ghrelin Protection against Porphyromonas gingivalis-Induced Salivary Gland Acinar Cell Apoptosis. Inflammopharmacology, 18,119-125.
[5] Slomiany, B.L. and Slomiany, A. (2010) Suppression by Ghrelin of Porphyromonas gingivalis-Induced Constitutive Nitric Oxide Synthase S-Nitrosylation and Apoptosis in Salivary Gland Acinar Cells. Journal of Signal Transduction, 2010, Article ID: 643642.
[6] Slomiany, B.L. and Slomiany, A. (2011) Ghrelin-Induced cSrc Activation through Constitutive Nitric Oxide Synthase- Dependent S-Nitrosylation in Modulation of Salivary Gland Acinar Cell Inflammatory Responses to Porphyromonas gingivalis. American Journal of Molecular Biology, 2, 43-51.
[7] Akira, S., Uematsu, S. and Takeuchi, O. (2006) Pathogen Recognition and Innate Immunity. Cell, 124, 783-801.
[8] Carpenter, S. and O’Neill, L.A.J. (2009) Recent Insights into the Structure of Toll-Like Receptors and Post-Transla- tional Modifications of Their Associated Signaling Proteins. Biochemical Journal, 422, 1-10.
[9] Slomiany, B.L. and Slomiany, A. (2013) Induction in Gastric Mucosal Prostaglandin and Nitric Oxide by Helicobacter pylori Is Dependent on MAPK/ERK-Mediated Activation of IKK-β and cPLA2: Modulatory Effect of Ghrelin. Inflammopharmacology, 21, 241-251.
[10] Kadamur, G. and Ross, E.M. (2013) Mammalian Phospholipase C. Annual Review of Physiology, 75, 127-154.
[11] Oude Weernink, P.A., Han, L., Jakobs, K.H. and Schmidt, M. (2007) Dynamic Phospholipid Signaling by G Protein- Coupled Receptors. Biochimica et Biophysica Acta, 1768, 888-900.
[12] Gong, P., Angelini, D.J., Yang, S.Q., Xia, G.J., Cross, A.S., Mannro, D., et al. (2008) TLR4 Signaling is Coupled to SRC Family Kinase Activation, Tyrosine Phosphorylation of Zonula Adherens Proteins, and Opening of the Paracellular Pathway in Human Lung Microvascular Endothelia. Journal of Biological Chemistry, 283, 13437-13449.
[13] Slomiany, B.L. and Slomiany, A. (2015) Role of Amplification in Gastric Mucosal Phospholipase Cγ2 Activation in Modulation of Gastric Mucosal Inflammatory Responses to Helicobacter pylori: Effect of Ghrelin. Inflammopharmacology, 23, 37-45.
[14] Lodeiro, M., Alen, B.O., Mosteiro, C.S., Beiroa, D., Nogueiras, R., Theodoropoulou, M., et al. (2011) The SHP-1 Protein Tyrosine Phosphatase Negatively Modulates Akt Signaling in the Ghrelin/GHSR1a System. Molecular Biology of the Cell, 22, 4182-4191.
[15] Xu, X., Bong, S.J., Chang, H.H. and Jin, Z.G. (2008) Molecular Mechanism of Ghrelin-Mediated Endothelial Nitric Oxide Synthase Activation. Endocrinology, 149, 4183-4192.
[16] Kojima, M., Hosoda, H., Date, Y., Nakazato, M. and Kangawa, K. (1999) Ghrelin is a Growth-Hormone-Releasing Acylated Peptide from Stomach. Nature, 402, 656-660.
[17] Groschl, M., Topf, H.G., Bohlender, J., Zenk, J., Klussmann, S., Dotsch, J., et al. (2005) Identification of Ghrelin in Human Saliva: Production by the Salivary Glands and Potential Role in Proliferation of Oral Keratinocytes. Clinical Chemistry, 51, 997-1006.
[18] Slomiany, B.L. and Slomiany, A. (2014) Protein Kinase Cd-Mediated Posttranslational Phosphorylation of Constitutive Nitric Oxide Synthase Regulates Gastric Mucosal Inflammatory Responses to Helicobacter pylori: Effect of Ghrelin. Journal of Biosciences and Medicines, 2, 20-33.
[19] Slomiany, B.L. and Slomiany, A. (2014) Role of Ghrelin-Induced Phosphatidylinositol 3-Kinase Activation in Modulation of Gastric Mucosal Inflammatory Responses to Helicobacter pylori. Inflammopharmacology, 22, 169-177.
[20] Lee, J.Y., Chiu, Y.H., Asara, J. and Cantley, L.C. (2011) Inhibition of PI3K Binding to Activators by Serine Phosphorylation of PI3K Regulatory Subunit p85α Src Homology-2 Domains. Proceedings of the National Academy of Sciences of the United States of America, 108, 14157-14162.
[21] Deason-Towne, F., Perraud, A.L. and Schmitz, C. (2012) Identification of Ser/Thr Phosphorylation Sites in the C2-Domain of Phospholipase Cγ2 (PLCγ2) Using TRPM7-Kinase. Cell Signaling, 24, 2070-2075.
[22] Slomiany, B.L. and Slomiany, A. (2014) Modulation of Gastric Mucosal Inflammatory Responses to Helicobacter pylori via Ghrelin-Induced Protein Kinase Cd Tyrosine Phosphorylation. Inflammopharmacology, 22, 251-262.
[23] Harden, T.K., Hicks, S.N. and Sondek, J. (2009) Phospholipase C Isozymes as Effectors of Ras Superfamily GTPases. Journal of Lipid Research, 50, S243-S248.
[24] Parri, M. and Chiarugi, P. (2010) Rac and Rho GTPases in Cancer Cell Motility Control. Cell Communication and Signaling, 8, 23-37.
[25] Walliser, C., Retlich, M., Harris, R., Everett, K.L., Josephs, M.B., Vatter, P., et al. (2008) Rac Regulates Its Effector Phospholipase Cγ2 through Interaction with a Split Pleckstrin Homology Domain. Journal of Biological Chemistry, 283, 30351-30362.
[26] Slomiany, B.L. and Slomiany, A. (2015) Mechanism of Rac1-Induced Amplification in Gastric Mucosal Phospholipase Cγ2 Activation in Response to Helicobacter pylori: Modulatory Effect of Ghrelin. Inflammopharmacology, 23, 101- 109.
[27] Wennerberg, K., Rossman, K.L. and Der, C.J. (2005) The Ras Superfamily at Glance. Journal of Cell Science, 118, 843-846.
[28] Boulter, E., Estrach, S., Gracia-Mata, R. and Feral, C.C. (2012) Off the Beaten Paths: Alternative and Crosstalk Regulation of Rho GTPases. FASEB Journal, 26, 469-479.
[29] Gregg, D., Rauscher, F.M. and Goldschmidt-Clermont, P.J. (2003) Rac Regulates Cardiovascular Superoxide through Diverse Molecular Interactions: More than Binary Switch. American Journal of Physiology and Cell Physiology, 285, C723-C734.
[30] Cote, J.F. and Vouri, K. (2007) GEF What? Dock180 and Related Proteins Help Rac to Polarize Cells in New Ways. Trends in Cell Biology, 17, 383-393.
[31] Feng, H., Hu, B., Liu, K.W., Liu, Y.X., Lu, X.H., Cheng, T., et al. (2011) Activation of Rac1 by Src-Dependent Phosphorylation of Dock180Y1811 Mediates PDGFRα-Stimulated Glioma Tumorigenesis in Mice and Humans. Journal of Clinical Investigation, 121, 4670- 4684.
[32] Yao, H.Y., Chen, L.H., Wang, J.R., Chen, J.Q., Xie, Q.M., Wu, X.M., et al. (2011) Inhibition of Rac Activity Alleviates Lipopolysaccharide-Induced Acute Pulmonary Injury in Mice. Biochimica et Biophysica Acta, 1810, 666-674.
[33] Slomiany, B.L. and Slomiany, A. (2010) Role of Ghrelin in Modulation of S-Nitrosylation-Dependent Akt Inactivation Induced in Salivary Gland Acinar Cells by Porphyromonas gingivalis. Health, 2, 1448-1455.
[34] Chen, P., Xie, H., Sekar, M.C., Gupta, K. and Wells, A. (1994) Epidermal Growth Factor Receptor-Mediated Cell Motility: Phospholipase C Activity Is Required, but Mitogen-Activated Protein Kinase Activity is not Sufficient for Induced Cell Movement. Journal of Cell Biology, 127, 847-857.
[35] Piechulek, T., Rehlen, T., Walliser, C., Vatter, P., Moepps, B. and Gierschik, P. (2005) Isozyme-Specific Stimulation of Phospholipase C-γ2 by Rac GTPases. Journal of Biological Chemistry, 280, 38923-38931.
[36] Slomiany, A. and Slomiany, B.L. (2012) Phosphatidylglycerol-Containing ER-Transport Vesicles Built and Restore Outer Mitochondrial Membrane and Deliver Nuclear DNA Translation Products to Generate Cardiolipin in the Inner Mitochondrial Membrane. Advances in Biological Chemistry, 2, 132-145.
[37] Slomiany, B.L. and Slomiany, A. (2015) Regulatory Role of Guanine Nucleotide Exchange Factor (GEF) Dock180 Phosphorylation on Tyr/Ser in Mediation of Gastric Mucosal Rac1 Activation in Response to Helicobacter pylori and Ghrelin. Inflammopharmacology, 23, 111-118.
[38] Roskoski, R. (2004) Src Protein-Tyrosine Kinase Structure and Regulation. Biochemical and Biophysical Research Communications, 324, 1155-1164.

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