Abstract
Saliva secretion requires effective translocation of aquaporin 5 (AQP5) water channel to the salivary glands (SGs) acinar apical membrane. Patients with Sjögren’s syndrome (SS) display abnormal AQP5 localization within acinar cells from SGs that correlate with sicca manifestation and glands hypofunction. Several proteins such as Prolactin-inducible protein (PIP) may regulate AQP5 trafficking as observed in lacrimal glands from mice. However, the role of the AQP5-PIP complex remains poorly understood. In the present study, we show that PIP interacts with AQP5 in vitro and in mice as well as in human SGs and that PIP misexpression correlates with an altered AQP5 distribution at the acinar apical membrane in PIP knockout mice and SS hMSG. Furthermore, our data show that the protein-protein interaction involves the AQP5 C-terminus and the N-terminal of PIP (one molecule of PIP per AQP5 tetramer). In conclusion, our findings highlight for the first time the role of PIP as a protein controlling AQP5 localization in human salivary glands but extend beyond due to the PIP-AQP5 interaction described in lung and breast cancers.
Highlights
Sjögren’s syndrome (SS) is a chronic autoimmune disease characterized by salivary
aquaporin 5 (AQP5)-Prolactin-inducible protein (PIP) interaction was investigated by Proximity ligation assays (PLA) in the human salivary gland acinar cell line NS-SV-AC co-transfected with HA-AQP5 and PIP plasmids, as their expression was not detectable
Xenopus laevis oocyte swell assay was carried out measuring the osmotic water permeability coefficient (Pf ), following injection of cRNA synthesized from the DNA plasmid constructs
Summary
This study aims to shed light on these important aspects by studying the human
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