Plasma membrane composition and cell functionality

JAUREGUIBERRY, M. S.; TRICERRI, M. A.; SANCHEZ, S. A.; GARDA, H. A.; FINARELLI, G. S.; RIMOLDI. O. J.

Buzios, Brazil

Congreso; VII Iberoamerican Congress of Biophysics; 2009

Sociedad Iberoamericana de Biofisica

  There is strong evidence that lipid composition at biological plasma membranes (PM) is crucial to modulate membrane-associated signaling, which in turn determines cell viability. To study the influence of PM properties on cell homeostasis, we constructed two permanent cell lines over expressing Fatty acid desaturases: Stearoyl CoA desaturase (SCD-cells), which results in the enrichment of monounsaturated fatty acids in the (PM), and a double transfectant over expressing D5 and D6 desaturases (D5/D6-cells) inducing an increase in poly unsaturated fatty acids. Both cell lines showed, in addition to the fatty acids composition modification, an increase in the phospholipids/sphingomyelin ratios. Analysis of Laurdan Generalized Polarization (GP) measured by two-photon fluorescence microscopy showed that, while D5/D6-cells PM are more fluid than control cells, SCD-cells compensate the monounsaturated fatty acid rise at the membrane by relatively increasing the cholesterol/phospholipid ratio. In addition, both cell lines showed higher mitochondrial reduction activity. We conclude that membrane fluidity is important, but not essential, to maintain cell viability.