Table of Contents
Journal of Signal Transduction
Volume 2010, Article ID 643642, 7 pages
http://dx.doi.org/10.1155/2010/643642
Research Article

Suppression by Ghrelin of Porphyromonas gingivalis-Induced Constitutive Nitric Oxide Synthase S-Nitrosylation and Apoptosis in Salivary Gland Acinar Cells

Research Center, C875, University of Medicine and Dentistry of New Jersey Dental School, 110 Bergen Street, P.O. Box 1709, Newark, NJ 07103-2400, USA

Received 18 June 2010; Revised 20 July 2010; Accepted 4 August 2010

Academic Editor: Shoukat Dedhar

Copyright © 2010 Bronislaw L. Slomiany and Amalia Slomiany. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Oral mucosal inflammatory responses to periodontopathic bacterium, P. gingivalis, and its key virulence factor, LPS, are characterized by a massive rise in epithelial cell apoptosis and the disturbances in NO signaling pathways. Here, we report that the LPS-induced enhancement in rat sublingual salivary gland acinar cell apoptosis and NO generation was associated with the suppression in constitutive nitric oxide synthase (cNOS) activity and a marked increase in the activity of inducible nitric oxide synthase (iNOS). We demonstrate that the detrimental effect of the LPS on cNOS was manifested by the enzyme protein S-nitrosylation, that was susceptible to inhibition by iNOS inhibitor, 1400 W. Further, we show that a peptide hormone, ghrelin, countered the LPS-induced changes in apoptosis and cNOS activity. This effect of ghrelin was reflected in the decrease in cNOS S-nitrosylation and the increase in phosphorylation. Our findings imply that P. gingivalis-induced disturbances in the acinar cell NO signaling pathways result from upregulation in iNOS-derived NO that causes cNOS S-nitrosylation that interferes with its activation through phosphorylation. We also show that ghrelin protection against P. gingivalis-induced disturbances involves cNOS activation associated with a decrease in its S-nitrosylation and the increase in phosphorylation.