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

MARIA FLORENCIA GUASTAFERRI; MARCELO OZU; GALIZIA LUCIANO; SUTKA, MOIRA; CINTIA ACUÑA; MARIA VICTORIA BRACAMONTE

La Plata

Congreso; XL Reunion Anual Sociedad Argentina de Biofisica; 2018

Our previous works demonstrated that: 1) human AQP1 (HsAQP1) and BvTIP1;2from beet are aquaporins characterized by a non-linear relationship between thewater flux (Jw) and the osmotic gradient (Dosm); and 2) this is due to the decreaseof the osmotic permeability coefficient (Pf) mediated by membrane tensionincrements. On the other hand, BvPIP2;1 (a PIP member from beet) showed alinear Jw-Dosm relationship, indicating that it is not mechanosensitive. Since PIPsand AQP1 share a common ancestor, we wonder if other PIPs can bemechanosensitive. Therefore, in this work we studied the transport properties ofFaPIP2;1 (from strawberry) by injecting different quantities of cRNA in xenopusoocytes. After 48 h of expression, the oocytes were subjected to different Δosmcreated with mannitol (40, 90 and 140 mOmol.Kgw-1). Oocytes volume changeswere registered by videomicroscopy and Jw and Pf were determined from the initialslope of volume kinetics. Controls were performed with water-injected or 100 μMamphotericin-incubated oocytes. While controls show linear Jw-Dosm relationships,FaPIP2;1-expressing oocytes show deviations from linearity, similar to previousreports with HsAQP1 and BvTIP2;1. Oocytes injected with 5 ng of FaPIP2;1-cRNAshow a significant decrease (p