Membrane organization and regulation of cellular Cholesterol homeostasis

MARÍA S. JAUREGUIBERRI; M. ALEJANDRA TRICERRI; SUSANA A. SANCHEZ; HORACIO A. GARDA; GABRIELA S. FINARELLI; MARINA C. GONZALEZ; OMAR J. RIMOLDI

JOURNAL OF MEMBRANE BIOLOGY

SPRINGER

Lugar: -; Año: 2009 vol. 232 p. 1 - 2

0022-2631

An excess of intracellular free cholesterol (Chol) is cytotoxic, and its homeostasis is crucial for cell viability. Apolipoprotein A-I (apoA-I) is a highly efficient Chol acceptor because it activates ways that tend to mobilize and export Chol from cellular complex cellular path- depots. We hypothesize that membrane composition and/or organization is strongly involved in Chol homeostasis. To test this hypothesis, we constructed a cell line over- expressing stearoyl CoA desaturase (SCD cells), which modifies plasma membrane (PM) composition by the enrichment of monounsaturated fatty acids, and determined this effect on membrane properties, cell viability, and Chol homeostasis. PM in SCD cells has a higher ratio of phospholipids to sphingomyelin and is slightly enriched in Chol. These cells showed an increase in the ratio of cho lesteryl esters to free Chol; they were more resistant to Chol toxicity; and they exported more caveolin than control cells. The data suggest that cell functionality is pre- served by regulating membrane fluidity and Chol exportation and storage.