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

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

Tucumán

Congreso; III Latin American Federation of Biophysical Societies (LAFeBS), IX IberoAmerican Congress of Biophysics, XLV Reunión Anual Sociedad Argentina de Biofísica; 2016

Sociedad Argentina de Biofísica

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 functionhave 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 studiedthe osmotic response of Xenopus oocytes expressing the water channelsTIP1 or PIP2 from the beet root Beta vulgaris by simultaneously measuring 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 volumetricelastic 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, mechanosensitivityseems to be a feature not shared by all aquaporins, and its appearancealong 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.