Water permeability changes of FaPIP2;1-expressing oocytes triggered by different osmotic gradients: evidence in favor of mechanical regulation

CYNTHIA ACUÑA ; LUCIANO GALIZIA; FLORENCIA GUASTAFERRI; VICTORIA BRACAMONTE; MARCELO OZU

Ciudad de La Plata

Congreso; XLVII Reunión Anual de la SAB; 2018

Sociedad Argentina de Biofísica

Our previous works demonstrated that: 1) human AQP1 (HsAQP1) and BvTIP1;2 from beet are aquaporins characterized by a non-linear relationship between the water flux (Jw) and the osmotic gradient (Δosm); and 2) this is due to the decrease of the osmotic permeability coefficient (Pf) mediated by membrane tension increments. On the other hand, BvPIP2;1 (a PIP member from beet) showed a linear Jw-Δosm relationship, indicating that it is not mechanosensitive. Since PIPs and AQP1 share a common ancestor, we wonder if other PIPs can be mechanosensitive. Therefore, in this work we studied the transport properties of FaPIP2;1 (from strawberry) by injecting different quantities of cRNA in xenopus oocytes. After 48 h of expression, the oocytes were subjected to different Δosm created with mannitol (40, 90 and 140 mOmol.Kgw-1). Oocytes volume changes were registered by videomicroscopy and Jw and Pf were determined from the initial slope of volume kinetics. Controls were performed with water-injected or 100 µM amphotericin-incubated oocytes. While controls show linear Jw-Δosm relationships, FaPIP2;1-expressing oocytes show deviations from linearity, similar to previous reports with HsAQP1 and BvTIP2;1. Oocytes injected with 5 ng of FaPIP2;1-cRNA show a significant decrease (p