Analysis of differential expression of tight junction proteins in cultured oral epithelial cells altered by Porphyromonas gingivalis, Porphyromonas gingivalis lipopolysaccharide, and extracellular adenosine triphosphate

Oral mucosa provides the first line of defense against a diverse array of environmental and microbial irritants by forming the barrier of epithelial cells interconnected by multiprotein tight junctions (TJ), adherens junctions, desmosomes, and gap junction complexes. Grainyhead-like 2 (GRHL2), an epithelial-specific transcription factor, may play a role in the formation of the mucosal epithelial barrier, as it regulates the expression of the junction proteins. The current study investigated the role of GRHL2 in the Porphyromonas gingivalis ( Pg)–induced impairment of epithelial barrier functions. Exposure of human oral keratinocytes (HOK-16B and OKF6 cells) to Pg or Pg-derived lipopolysaccharides ( Pg LPSs) led to rapid loss of endogenous GRHL2 and the junction proteins (e.g., zonula occludens, E-cadherin, claudins, and occludin). GRHL2 directly regulated the expression levels of the junction proteins and the epithelial permeability for small molecules (e.g., dextrans and Pg bacteria). To explore the functional role of GRHL2 in oral mucosal barrier, we used a Grhl2 conditional knockout (KO) mouse model, which allows for epithelial tissue-specific Grhl2 KO in an inducible manner. Grhl2 KO impaired the expression of the junction proteins at the junctional epithelium and increased the alveolar bone loss in the ligature-induced periodontitis model. Fluorescence in situ hybridization revealed increased epithelial penetration of oral bacteria in Grhl2 KO mice compared with the wild-type mice. Also, blood loadings of oral bacteria (e.g., Bacteroides, Bacillus, Firmicutes, β- proteobacteria, and Spirochetes) were significantly elevated in Grhl2 KO mice compared to the wild-type littermates. These data indicate that Pg bacteria may enhance paracellular penetration through oral mucosa in part by targeting the expression of GRHL2 in the oral epithelial cells, which then impairs the epithelial barrier by inhibition of junction protein expression, resulting in increased alveolar tissue destruction and systemic bacteremia.

Download Full-text

Differential expression of genes encoding tight junction proteins in colorectal cancer: frequent dysregulation of claudin-1, -8 and -12

International Journal of Colorectal Disease ◽

10.1007/s00384-006-0197-3 ◽

2006 ◽

Vol 22 (6) ◽

pp. 651-659 ◽

Cited By ~ 55

Author(s):

J. Gröne ◽

B. Weber ◽

E. Staub ◽

M. Heinze ◽

I. Klaman ◽

...

Keyword(s):

Colorectal Cancer ◽

Tight Junction ◽

Differential Expression ◽

Tight Junction Proteins ◽

Expression Of Genes ◽

Genes Encoding ◽

Differential Expression Of Genes ◽

Junction Proteins

Download Full-text

Identification of bistable populations of Porphyromonas gingivalis that differ in epithelial cell invasion

Microbiology ◽

10.1099/mic.0.038075-0 ◽

2010 ◽

Vol 156 (10) ◽

pp. 3052-3064 ◽

Cited By ~ 17

Author(s):

S. Suwannakul ◽

G. P. Stafford ◽

S. A. Whawell ◽

C. W. I. Douglas

Keyword(s):

Epithelial Cells ◽

Porphyromonas Gingivalis ◽

Cell Invasion ◽

Protease Activity ◽

Periodontal Pathogen ◽

Wild Type ◽

Oral Epithelial Cells ◽

Specific Protease ◽

Oral Epithelial ◽

First Time

Bistable populations of bacteria give rise to two or more subtypes that exhibit different phenotypes. We have explored whether the periodontal pathogen Porphyromonas gingivalis exhibits bistable invasive phenotypes. Using a modified cell invasion assay, we show for the first time that there are two distinct subtypes within a population of P. gingivalis strains NCTC 11834 and W50 that display differences in their ability to invade oral epithelial cells. The highly invasive subtype invades cells at 10–30-fold higher levels than the poorly invasive subtype and remains highly invasive for approximately 12–16 generations. Analysis of the gingipain activity of these subtypes revealed that the highly invasive type had reduced cell-associated arginine-specific protease activity. The role of Arg-gingipain activity in invasion was verified by enhancement of invasion by rgpAB mutations and by inclusion of an Arg-gingipain inhibitor in invasion assays using wild-type bacteria. In addition, a population of ΔrgpAB bacteria did not contain a hyperinvasive subtype. Screening of the protease activity of wild-type populations of both strains identified high and low protease subtypes which also showed a corresponding reduction or enhancement, respectively, of invasive capabilities. Microarray analysis of these bistable populations revealed a putative signature set of genes that includes oxidative stress resistance and iron transport genes, and which might be critical to invasion of or survival within epithelial cells.

Download Full-text

Differential effects of claudin-3 and claudin-4 on alveolar epithelial barrier function

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00299.2010 ◽

2011 ◽

Vol 301 (1) ◽

pp. L40-L49 ◽

Cited By ~ 63

Author(s):

Leslie A. Mitchell ◽

Christian E. Overgaard ◽

Christina Ward ◽

Susan S. Margulies ◽

Michael Koval

Keyword(s):

Epithelial Cells ◽

Tight Junction ◽

Barrier Function ◽

Alveolar Epithelium ◽

Alveolar Epithelial Cells ◽

Epithelial Barrier ◽

Tight Junction Proteins ◽

Epithelial Barrier Function ◽

Alveolar Epithelial ◽

Junction Proteins

Alveolar barrier function depends critically on the claudin family tight junction proteins. Of the major claudins expressed by alveolar epithelial cells, claudin (Cldn)-3 and Cldn-4 are the most closely related by amino acid homology, yet they differ dramatically in the pattern of expression. Previously published reports have shown that Cldn-3 is predominantly expressed by type II alveolar epithelial cells; Cldn-4 is expressed throughout the alveolar epithelium and is specifically upregulated in response to acute lung injury. Using primary rat alveolar epithelial cells transduced with yellow fluorescent protein-tagged claudin constructs, we have identified roles for Cldn-3 and Cldn-4 in alveolar epithelial barrier function. Surprisingly, increasing expression of Cldn-3 decreased alveolar epithelial barrier function, as assessed by transepithelial resistance and dye flux measurements. Conversely, increasing Cldn-4 expression improved alveolar epithelial transepithelial resistance compared with control cells. Other alveolar epithelial tight junction proteins were largely unaffected by increased expression of Cldn-3 and Cldn-4. Taken together, these results demonstrate that, in the context of the alveolar epithelium, Cldn-3 and Cldn-4 have different effects on paracellular permeability, despite significant homology in their extracellular loop domains.

Download Full-text