Estradiol Induced Estrogen Receptor-mediated Transcription and Expression of Aquaporin5

Abstract

In this study, we constructed the recombinant plasmid of pGL2/Aquaporin5(AQP5) promoter (pGL2/AQP5p) luciferase reporter, then found estradiol(E2) induced AQP5 promoter activation in a dose-dependent manner. Further, we identified endogenous estrogen receptors(ER), including ERα and ERβ, expressed in human submandibular gland(HSG) cells, which responded to E2. Then demonstrated by the stimulation of E2, AQP5 was upregulated in protein level, meanwhile AQP5 located in cytomembrane was elevated in immunofluorescence. Furthermore, we revealed the roles of ERα and ERβ in AQP5 upregulation by E2. When ERα and ERβ were overexpressed, the AQP5 transcription level and protein expression were augmented obviously. While when knockdown ER by ERα-shRNA or ERβ-shRNA, AQP5 transcription and expression attenuated. Moreover, we detected the effect of E2 in Sjogren’s syndrome(SS) mice model in vivo. SS mice models were constructed by injecting submandibular gland antigen immune induction combined with estrogen deprivation, which were administrated with saline and E2. The salivary secretion was decreased, and the AQP5 expression downregulated in the submandibular gland in the SS model group. When SS mice were administrated with E2, the salivary secretion was significantly increased, and the AQP5 expression upregulated in the submandibular gland. These results suggest E2 activates AQP5p transcription and upregulates AQP5 protein expression, and E2 promotes salivary secretion in SS model in vivo. Taken together, we provided the evidence that E2 increased salivary secretion by activating AQP5 transcription and expression.