Differential expression of integrins and laminin‐5 in normal oral epithelia

Abstract

β1 and β4 integrins are receptors on epithelial cells mediating cell‐extracellular matrix adhesion. Furthermore, α2β1 and α3β1 contribute to cell‐cell adhesion. Laminin‐5 in epithelial basement membranes (BMs) is a ligand for α6β4 and α3β1. Expression of different integrins and laminin‐5 was studied in oral epithelium to characterize regional variations in these adhesion molecules. Monoclonal antibodies directed against α2‐α6β1/α6β4 and laminin‐5 were examined in cryopreserved biopsies of normal mucosa by immunohistochemistry. Laminin‐5 was expressed as a line along the BMs. The junctional epithelium showed a unique phenotype: Laminin‐5 was detected in the internal BM at the tooth surface and in the external BM, where excessive laminin‐5 was seen in the stroma. α6β4 was expressed in all cells of the junctional epithelium. Integrins α4β1 and α5β1 were not detected in the epithelia, whereas α2β1 and α3β1 showed differential expression. Epithelia with well‐developed rete pegs and connective tissue papillae showed polarized α3β1 expression along the BM in the rete pegs, in contrast to negative expression at the tips of the connective tissue papillae. A variation in the suprabasal distribution of α2β1 and α3β1 was observed between epithelia from different regions. α2β1 and α3β1 were detected in basal/parabasal cells in keratinized epithelia, whereas there was increased suprabasal expression in nonkeratinized mucosa. These results indicate inhomogeneity in the basal cell population of oral squamous epithelia and differential expression of integrins, which may reflect differences in the underlying stroma. Laminin‐5 deposits in the stroma underneath the junctional epithelium may indicate subclinical gingival inflammation.

Involvement of laminin and integrins in adhesion and migration of junctional epithelium cells

“…It is thought that hemidesmosomes are composed of laminin‐5 and integrin α 6 β 4 (20), and thus both laminin‐5 and integrin α 3 β 1 may participate in cell migration (12,13). In this study, we investigated laminin γ 2 and integrins β 4 and α 3 , because laminin‐5 only possesses a γ 2 subunit, integrin β 4 (which may be involved in cell–extracellular matrix contact) and integrin α 3 (which induces cell migration) (7,12,21). The expression of laminin‐5 and integrins has already been demonstrated in human oral tissues by immunofluorescence staining (4,21), in mouse oral tissues by immunofluorescence staining and by in situ hybridization (3) and in rat oral tissues by immunofluorescence (3).…”

Laminin‐5 immunocytochemistry: a new tool for identifying dysplastic cells in oral brush biopsies

“…24,25 The brush biopsy technique can only detect the distinguishing characteristic of a resynthesis of the laminin c2 chain via the cytoplasmic immune reaction. Modulations in the ln-5 matrix, to the extent found in oral squamous cell carcinomas, can also occur in benign hyperproliferative lesions of the oral mucosa.…”

Porphyromonas gingivalis-Epithelial Cell Interactions in Periodontitis

“…The nature of the ␤-chains defines the family of integrins, and both ␣-and ␤-chains contribute to the binding of ligands. ␣2␤1, ␣3␤1, ␣6␤1, and ␣6␤4 integrin subunits are expressed by gingival epithelial cells (Hormia et al, 1992;Del Castillo et al, 1996;Thorup et al, 1997). Integrins are involved in cell-extracellular matrix and cell-cell interactions and function as host cell receptors for microbial adhesins.…”