Nuclear Lipid Droplets are dynamic structures

LAGRUTTA LC; LAYERENZA JP; MONTERO VILLEGAS S; SISTI MS; GARCIA DE BRAVO, MM; VES-LOSADA A

Mendoza

Congreso; XLVIII Reunión Anual de SAIB; 2012

SAIB

The cell nucleus (N) is a highly compartmentalized organelle characterized by several dynamic domains. We have demonstrated that nuclear neutral lipids are organized and stored in lipid droplets (nLD), composed of few and small droplets randomly distributed. The nLD could thus be involved in nuclear-lipid homeostasis and serve as an endonuclear buffering system that can rapidly provides or incorporates lipids involved in signaling paths and transcription factors in the nucleus. The aim of this work was to determine if nLD are a dynamic domain. With this purpose HepG2 were incubated with 18:1n-9 as an external stimulus since it increases cytosolic lipid droplet (cLD) number and size. Both LD (c and n) were stained with BODIPY493/503 and N with DAPI and viability controls were done. Due to 18:1n-9 treatment cellular shape was modified and both cLD and nLD increased (number and size). nLD increments were smaller than cLD (4 y 10 times respectively). If 18:1n-9 was excluded from the incubation mixture, LD increments were reverted. Under all conditions tested, nLD corresponded to a small pool (3-5%) with respect to total (nLD + cLD). In conclusion, nLD are dynamic structures; their size and number can vary in response to external signals that influence TAG pools by a reversible mechanism.