Role of plasma membrane lípid composition on cellular homeostasis

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

Pto Madryn

Congreso; XLV Congreso Nacional de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Evidence suggests that membrane-associated signaling and hence cell metabolism and viability depend on membrane lipid composition. Our aim was to analyze the influence of membrane properties on cell homeostasis. For this purpose we constructed two permanent cell lines over expressing fatty acid desaturases: to begin with, CHO KI cells were transfected with rat Stearoyl CoA desaturase resulting in an increase of monounsaturated fatty acids at the plasma membrane (PM) (SAIB 2007 and 2008). Now we show results concerning a double transfectant over expressing both D5 and D6 desaturases (D5-D6 cells), which turned into a rise of poly unsaturated fatty acids. Furthermore, this cell-line showed lower contents of sphingomyelin and free cholesterol relative to phospholipids at the PM, consistent with a lower cholesterol removal by apoA-I, as well as an increase in the sterified-Cholesterol/free-cholesterol ratio. In addition, we analyzed PM properties through Laurdan Generalized Polarization (GP) by two-photon fluorescence microscopy. Preliminary data suggest higher membrane fluidity in D5/D6-cells PM when compared to control cells. Moreover, D5-D6 cells also showed differences in mitochondrial reduction activity. Together, our results indicate that membrane composition plays a role in lateral domain organization and cholesterol homeostasis and thus, in cell signaling and metabolism.