TIP1 but not PIP2 form Beta vulgaris is regulated by cell mechanics

GOLDMAN, RAMIRO PABLO; JOZEFKOWICZ, CINTIA; SUTKA, MOIRA; ALLEVA, KARINA; OZU, MARCELO

San Miguel de Tucumán

Congreso; III Latin American Federation of Biophysical Societies (LAFeBS) IX IberoAmerican Congress of Biophysics XLV Reunion Anual SAB 2016; 2016

Different regulatory mechanisms are known in aquaporins (AQPs). Itwas demonstrated in the last years that animal and plant aquaporinsare regulated by cell membrane mechanics (Ozu et al., 2013; Leitaoet al., 2014). However, this mechanism has not been studied in deep.No direct measurements of membrane mechanics and aquaporins func-tion have been reported yet. Moreover, important topics in the study ofmechano-sensitivity in aquaporins are not known. For example, it is notclear if this is a general feature shared by all aquaporins or not, and it isnot known which is the sensitivity of this regulation. To characterize thebiophysical properties of mechanical regulation in aquaporins, we stud-ied the osmotic response of Xenopus oocytes expressing the water chan-nels TIP1 or PIP2 from the beet root Beta bulgaris by simultaneouslymeasuring the internal pressure and volume under different osmotic andinitial pressure conditions. Our results indicate that PIP2 would not be amechanosensitive member of the aquaporin family whereas TIP1 wouldbe since the osmotic permeability coefficient (Pf) measured in oocytesexpressing TIP1 follows an exponential decay function with the volu-metric elastic modulus (E). Filogenetic analysis classifies human AQP1and PIPs from plants into the same group, whereas TIPs are classifiedwithin another group (Soto et al, 2012). In this context, mechanosensi-tivity seems to be a feature not shared by all aquaporins, and its appear-ance along evolution will not be easy to determine.ReferencesLeitão L, Prista C, Loureiro-Dias MC, Moura TF, Soveral G. Biochem. Biophys. Res.Commun. 450:289-94, 2014.Ozu M, Dorr RA, Gutiérrez F, Politi MT, Toriano R. Biophys. J. 104:85?95, 2013.Soto G, Alleva K, Amodeo G, Muschietti J, Ayub ND. Gene 503:165?176, 2012.