Abstract
Hyposecretion of saliva and consequent dry mouth lead to severe caries and periodontal disease. Therapeutic radiation for head and neck cancer and sialadenitis result in atrophy and fibrosis of salivary glands, but the mechanism is not clear. As a model for dysfunction of salivary glands, we examined the change of gene expression in primary cultured parotid acinar cells. Acinar cells were isolated from rat parotid glands, and were cultured in the medium containing rat serum. Cells attached to the dishes and most of them spread as a monolayer after culture for 48 h. The expression pattern of differentiation markers were changed during the culture. Expression levels of amylase and aquaporin 5, markers of acinar cells, decreased, and cytokeratin 14 and vimentin increased. Claudin-4 and claudin-6, which are expressed in embryonic duct cells, but not in acinar cells, began to be expressed. Addition of Src kinase inhibitor PP1 or PP2 suppressed these changes, suggesting that inhibition of Src kinases suppressed dedifferentiation of acinar cells. PP1 did not affect the expression levels of E-cadherin and occludin. Immunofluorescence microscopy showed that tight junctions were formed both in the presence or absence of PP1. The immunofluorescence signals for claudin-3 and claudin-4 were observed in both cultures, but the intensities of signals were different. These results suggest that inhibition of Src family kinases changes expression pattern of claudins and may influence the paracellular permeability. [J Physiol Sci. 2008;58 Suppl:S200]
