L-FABP facilitates Nuclear Lipid Droplet oleic acid mobilization and esterification

LAYERENZA, JUAN PABLO; LAGRUTTA, LUCÍA CAROLINA; SISTI, MARTÍN SEBASTIÁN; VES LOSADA, ANA

Mendoza

Congreso; XLVIII Reunión Anual de SAIB; 2012

SAIB

Cellular nuclei (N) are an evolutionary development of the eukaryotic cell that enables a critical compartmentation of the processes of replication, transcription, premRNA splicing, and ribosome assembly among other cellular functions. We have determined that N lipids are located in nuclear membranes and Nuclear Lipid Droplets (nLD) (mainly composed of TAG, CE and C). nLD could be involved in N lipid homeostasis and serve as a buffering system that provides or incorporates lipids of signaling paths and transcription factors. Taking into account previous results, exogenous 18:1n-9 is mainly esterified to nLD TAG and CE, the aim of the present work was to determine the role of L-FABP in 18:1n-9 incorporation, mobilization and release. Firstly N were labeled ([14C]N) in vitro with [1-14C]18:1n-9 free or L-FABP bound, ATP and CoA; then [14C]N were incubated without 18:1n-9, plus ATP, CoA at increasing concentrations of delipidized L-FABP. Under these conditions, exogenous 18:1n-9 was incorporated to N as FFA and esterified to TAG>CE>GPL; esterification increased when 18:1n-9 was L-FABP bound and with incubation time. Nuclear and nLD 18:1n-9 was mobilized from TAG, CE, PE and FFA pools and its release to cytosol increased with L-FABP concentration. In conclusion, L-FABP facilitates 18:1n-9 esterification to nLD and its mobilization within the nucleus as well as its release to cytosol.