Insight into Salivary Gland Aquaporins

Abstract

The main role of salivary glands (SG) is the production and secretion of saliva, in which aquaporins (AQPs) play a key role by ensuring water flow. The AQPs are transmembrane channel proteins permeable to water to allow water transport across cell membranes according to osmotic gradient. This review gives an insight into SG AQPs. Indeed, it gives a summary of the expression and localization of AQPs in adult human, rat and mouse SG, as well as of their physiological role in SG function. Furthermore, the review provides a comprehensive view of the involvement of AQPs in pathological conditions affecting SG, including Sjögren’s syndrome, diabetes, agedness, head and neck cancer radiotherapy and SG cancer. These conditions are characterized by salivary hypofunction resulting in xerostomia. A specific focus is given on current and future therapeutic strategies aiming at AQPs to treat xerostomia. A deeper understanding of the AQPs involvement in molecular mechanisms of saliva secretion and diseases offered new avenues for therapeutic approaches, including drugs, gene therapy and tissue engineering. As such, AQP5 represents a potential therapeutic target in different strategies for the treatment of xerostomia.

RETRACTED ARTICLE: Glycyrrhizic acid ameliorates submandibular gland oxidative stress, autophagy and vascular dysfunction in rat model of type 1 diabetes

“…Therefore, it is not surprising that it was reported to play a crucial role in angiogenesis 31 . AQP4 is located in the ductal cells and at the basal region of acinar cells 32 . AQP5 is located in apicolateral membrane of acinar cells and is important for production of the primary saliva in the acini and is proposed to play a critical role in both development and regeneration 32 .…”

“…AQP4 is located in the ductal cells and at the basal region of acinar cells 32 . AQP5 is located in apicolateral membrane of acinar cells and is important for production of the primary saliva in the acini and is proposed to play a critical role in both development and regeneration 32 . A previous study attributed the SMG dysfunction in diabetes to autophagy activation and associated degradation of AQP5 28 .…”

Artesunate Combined With Metformin Ameliorate on Diabetes-Induced Xerostomia by Mitigating Superior Salivatory Nucleus and Salivary Glands Injury in Type 2 Diabetic Rats via the PI3K/AKT Pathway

“…Besides, AQP5 is the most important aquaporin for saliva secretion ( D'Agostino et al, 2020 ). Accordingly, we also evaluated AQP5 expression in SMGs ( Figure 4F ).…”

Immortalization of Salivary Gland Epithelial Cells of Xerostomic Patients: Establishment and Characterization of Novel Cell Lines

“…Compared to SGCLs and Hela, A253 and HMC-3A showed the greatest similarity to iSGEC cultures. Mucoepidermoid carcinomas have been shown to exhibit increased expression of AQP5 and among all cell lines analyzed, HMC-3A expressed AQP5 highest ( Figure 3 A) [ 24 ].…”