Aquaporin 5 distribution pattern during development of the mouse sublingual salivary gland

Abstract

Aquaporin 5 (AQP5) is important in salivary fluid secretion, and has been found in acinar cells of salivary glands in several species. Recently, studies have shown the AQP5 transcript and protein expression patterns as well as the temporal-spatial protein distribution during development of the mouse submandibular salivary gland. The AQP5 distribution pattern of the closely located sublingual gland (SLG) is, however, not well known. Thus, in this study, the Aqp5 RNA expression pattern and the temporal-spatial distribution of AQP5 protein in prenatal development and in adult mouse SLG was investigated. SLGs from embryonic day 14.5 (E14.5) to 18.5 and postnatal days 0 (P0), 25, and 60 were examined using real time PCR and immunohistochemistry. The Aqp5 transcript was detected from E13.5 and was found to increase towards birth and in young adults. The protein was first detected in a scattered pattern in the canalicular stage and became more organized in the luminal membrane of the acinar cells towards birth. During all postnatal developmental stages studied, AQP5 was localized in the luminal and lateral membrane of acinar cells. AQP5 was also detected in the intercalated duct and additional apical membrane staining in the entire intralobular duct was found in the terminal bud stage. These results indicate that AQP5 plays a role during embryonic salivary gland development.

Expression of aquaporin 5 during murine palatine glands development: a light and electron microscopic immunocytochemical study

“…In the embryonic stage, AQP5 expression was intense and diffuse in the developing palatine glands acini. The increasing expression pattern of AQP5 during prenatal development is in agreement with what is found in the mouse sublingual (15) and submandibular glands (16), and the rat submandibular gland (32). Unlike the sublingual and submandibular glands (15, 16), AQP5 expression decreased progressively throughout the maturation of palatine glands.…”

“…The increasing expression pattern of AQP5 during prenatal development is in agreement with what is found in the mouse sublingual (15) and submandibular glands (16), and the rat submandibular gland (32). Unlike the sublingual and submandibular glands (15, 16), AQP5 expression decreased progressively throughout the maturation of palatine glands. It has been shown that inhibition of AQP5 phosphorylation results in decreased cell proliferation in a mouse fibroblast cell line with AQP5 over‐expression (33).…”

“…The labeling occupied the cytoplasm and the basolateral projections between cells in the electron microscope. Similar observations also have been reported in the mouse and rat submandibular (16, 41) and mouse parotid glands (54), but not in the mouse sublingual glands (15). It has been suggested that the basally located AQP5 may help in regulating paracellular fluid transfer by acting as an osmosensor (55, 56).…”

“…In mouse submandibular and sublingual glands, AQP5 is expressed in a scattered pattern in the terminal bulb cells in the prenatal stage. In the postnatal stage, it is distributed in the apical and lateral membrane of both mucous acini and serous demilunes, just as some cytoplasmic staining of serous cells is seen (15, 16). Apart from that, the distribution of AQP5 during the development of minor salivary glands has been scarcely reported.…”

Dynamics of Salivary Gland AQP5 under Normal and Pathologic Conditions

“…They detected AQP5 protein at first on the embryonic day E17; its level peaked around birth and at least decreased in the early postnatal day. Aure et al [19] revealed the expression and localization of AQP5 in the mouse sublingual gland during development. In their study, AQP5 mRNA was detected from the embryonic day E13, and its level increased till the early postnatal days by means of real time PCR.…”