INIBIOLP   05426
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE LA PLATA "PROF. DR. RODOLFO R. BRENNER"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Nuclear lipid droplets: A novel nuclear domain
Autor/es:
LAYERENZA, JUAN P; GONZÁLEZ, PEDRO; GARCÍA DE BRAVO, MARGARITA; POLO, MÓNICA; SISTI, MARTÍN S; VES-LOSADA, ANA
Lugar:
Bilbao
Reunión:
Congreso; 51st International Conference of Bioscience of Lipids (ICBL); 2010
Institución organizadora:
ICBL
Resumen:
Cellular nuclei (N) are an evolutionary acquisition of eukaryotic cells with different functional domains immersed in a nuclear matrix (Mx), surrounded by a double nuclear membrane (NM). We have already determined that lipids represent 16% of nuclear components, (PL: 84% and neutral lipids (NL): 16%). PL are mainly found in NM whereas endonuclear lipids are enriched in NL. The aim of this work was to analyze nuclear NL organization taking into account that they may represent alternative sources of nuclear fatty acids and signaling lipids. With this purpose lipid droplet (LD) isolation method (ultracentrifugation in a sucrose density gradient) was applied to N isolated from liver cells. A unique white upper band was isolated: 80% lipids and 20% proteins. NL: 37%TAG (triacylglyceride), 34% CE (cholesterolester) and 28% Cho (cholesterol); and 3.5% PL (phospholipid). TAG fatty acids are: saturated>polyunsaturated (n-6, n-3)>monoenoic and CE: saturated> monoenoic> polyunsaturated (n-6, n-3).  LD were stained with Sudan Red, and OsO4 (white field microscopy), BODIPY493/503 (confocal fluorescence-microscopy); as well as observed by negative staining-TEM. Inhomogeneity of LD sizes was observed in: isolated band, N, Mx and nucleoplasts (outer membrane depleted nuclei). In conclusion, neutral lipids are organized in discrete non polar domains inside the nuclei, Nuclear LD, which consists of a hydrophobic core of NL covered by a monolayer of PL and associated proteins.