ラット耳下腺におけるaquaporin 6の発現と局在

抄録

Objectives: Aquaporins (AQPs) are 6 trans membrane proteins facilitating water transport via a plasma membrane and are involved in water, urea, glycerol or lipid transport. It has currently demonstrated that AQPs are located in intracellular organelle and their localization is changed by cell stimulation. In this study, we investigated AQP6 in the rat parotid gland.Methods: Plasma membrane and secretory granule fractions were isolated from the rat parotid glands using parcoll gradient. mRNA expression was determined by RT-PCR. Protein expression was determined by western blotting analysis. Morphological localization was observed by confocal microscopy and electron microscopy with immunolabelled ultrathin-cryosection. Results and Discussion: In RT-PCR, 262 bp band of AQP6 was detected in parotid acinar cells. In western blotting analysis using anti-AQP6 antibody, only 29 kDa protein was detected in plasma membrane and secretory granule membrane fractions of the parotid gland. In confocal microscopy, immunofluorescence with anti-AQP6 antibody was positive at the apical sites, especially cell-cell junctional region, in parotid acinar cells. When the glands were stimulated by β-agonist, AQP6 was observed to accumulate at the apical sites. These results suggest that AQP6 expresses in the apical sites and secretory granule membrane in the rat parotid gland as a monomeric form. The change of localization of AQP6 appears to be involved in exocytosis. [J Physiol Sci. 2006;56 Suppl:S81]