Aquaporins and tight junction expressed in parotid acinar cell culture

For salivary gland regeneration, it is important to maintain the functional activities of acinar cells after culture. Aquaporins, especially AQP-5 and AQP-3, contribute to water secretion. Tight junctions play the role of maintaining the cell polarity. Therefore, expression of aquaporins and tight junction molecules may represent the functional activities of acinar cells. Objectives: This study attempts to elucidate the expression of aquaporin (AQPs) family and tight junction (TJ) molecules during the primary culture of human parotid gland (HPG) acinar cells. Methods: Human parotid tissue was obtained during surgery and acinar cells were selectively cultured for the series identification. Polymerase chain reaction (PCR) was used to estimate the messenger RNA expression of both AQP-3 and AQP-5. The protein expression was identified by Western blotting. Uultrastructure of acinar cells ( 90 nanometer thin sections) were investigated with transmission electron microscopy (TEM). Results: The ratio of mRNA expression between AQP-3 and AQP-5 had significantly altered after in vitro culture period for 3 weeks. Electron microscopy examination revealed that the cells seem not to have good recovery pattern of forming a dense monolayer with complete tight junction structures, but the secretary granules still can be observed around the nucleus. The results of Western blotting gave not only the certification of cell type after culture but also the protein synthesis ability of the cells. Conclusion: After primary culture process, the HPG acinar cells were temporarily lost the feature of showing a densely packed monolayer with tight junction structure pattern. Without tight junction, the polarity of epithelial cells was not obvious. However, the ability of secretion was not torpid, the secretary granules and protein product alpha-amylase was still found. Moreover, the main role of water secretion, AQPs family, showed a relatively change between different types.