IIBYT   23944
INSTITUTO DE INVESTIGACIONES BIOLOGICAS Y TECNOLOGICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Lentes de trigliceridos como sistema modelo para el estudio de ?Lipid Droplets?
Autor/es:
BENJAMÍN CARUSO; MARÍA ANGÉLICA PERILLO; NATALIA WILKE
Lugar:
Córdoba
Reunión:
Congreso; Reunion Anual del Instituto de Investigaciones Biológicas y Tecnológicas; 2017
Institución organizadora:
Instituto de Investigaciones Biológicas y Tecnológicas
Resumen:
Lipid Droplets (LD) are intracelular structures consisting on an apolar lipid core -composed mainly of triglycerides (TG) and steryl esters- which is surrounded by a phospholipid and protein monolayer. LDs originate in the ER bilayer, where TG synthesis concludes. The mechanisms underlying TG nucleation, size maduration and budding-off from the ER membrane are a matter of current investigations and the role of dewetting from cytosolic-bilayer interface appears to play a critical role [1]. Here, we study phospadilcholine (PC) / triglycerides mixtures at the air-water interface as Langmuir and collapsed monolayers in order to gain insight into those factors that may affect the stability of TG bulk structures in contact with interfaces. PC/TG form stable monolayers which, under lateral compression, collapse at a surface pressure (π) dependent on composition. Observation under Brewster Angle Microscopy (BAM) revealed the appearance of microscopic structures at π beyond collapse, whose size (3 ± 2 microns radius) did not vary with composition. Contrary to dpPC/TG mixtures, pure TG and EPC/TG compression isotherms are reversible after collapse, and BAM confirmed this behavior. Furthermore, identical results were obtained when monolayers where spread on the interface up to a π higher than collapse. The fluorescent probe Nile Red (NR), commonly used to stain lipid droplets, was able to reveal these structures. Comparison of BAM and fluorescence microscopy indicate that these collapsed structures corresponde to TG liquid phase which are known as interfasial ?lenses?. Latest theoretical models propose nanometer-sized structures to dewet an dettach from the bilayer. Being in equilibrium and with a microscopic size, these lenses suggest that dewetting of TG adyacent to a PC monolayer (eventually hemilayer) is enough to reach such lateral size.