The expressions of claudin-1 and E-cadherin in junctional epithelium

Background and Objective: The epithelium provides an important barrier against microbial invasion. Tight junction structural proteins called claudins are known to contribute to the epithelial cell barrier. Junctional epithelium is located at a strategically important interface between gingival sulcus and is interconnected by desmosomes and gap junctions, but not by tight junctions. Although claudins are tight junction-associated proteins, they are also expressed in the epithelium despite its lack of tight junctions in invertebrates. Therefore, claudins may play an important role in junctional epithelium without tight junctions. E-cadherin is a key molecule in the formation of adherence junctions and desmosomes. In the present study, we aimed to investigate the expressions of claudin-1,claudin-3, claudin-7 and E-cadherin in the junctional epithelium of Fischer 344 rats. Material and Methods: Gingival tissues from Fischer 344 rats were analyzed by immunohistochemical staining for claudin-1, claudin-3, claudin-7, and E-cadherin. Results: Intense staining for claudin-1 and E-cadherin were observed in the junctional epithelium. In contrast to claudin-1, claudin-3 was mainly expressed in oral gingival epithelium and claudin-7 could not be detected on immunohistochemical analysis of the rat gingiva. Conclusion: These data suggest that claudin-1 and E-cadherin exist in the junctional epithelium and may play an important role in epithelial barrier function.