Efficient generation of a stable CHO-K1 cell line overexpressing the human water channel aquaporin-5 as tool to generate therapeutic antibodies.

Aquaporins (AQPs) are a family of water permeable channels expressed on the plasma membrane with AQP5 being the major channel expressed in several human tissues including salivary and lacrimal glands. Anti-AQP5 autoantibodies have been observed in patients with Sjögren's syndrome who are characterised by dryness of both salivary and lacrimal glands, and they have been implicated in the underlying mechanisms of glandular dysfunction. AQP5 is formed by six transmembrane helices linked with three extracellular and two intracellular loops. Develop antibodies against membrane protein extracellular loops can be a challenge due to the difficulty in maintaining these proteins as recombinant in their native form. Therefore, in this work we aimed to generate an efficient stable-transfected cell line overexpressing human AQP5 (CHO-K1/AQP5) to perform primarily cell-based phage display biopanning experiments to develop new potential recombinant antibodies targeting AQP5. We also showed that the new CHO-K1/AQP5 cell line can be used to study molecular mechanisms of AQP5 sub-cellular trafficking making these cells a useful tool for functional studies.