L-FABP facilitates nuclear lipid droplet oleic acid mobilization and esterification

LAYERENZA, JUAN P; LAGRUTTA, LUCÍA C; SISTI, MARTÍN S; VES-LOSADA, ANA

Congreso; Reunion Anual de la SAIB; 2012

SAIB

Cellular nuclei (N) are an evolutionary development of theeukaryotic cell that enables a critical compartmentation of theprocesses of replication, transcription, premRNA splicing, andribosome assembly among other cellular functions. We havedetermined that N lipids are located in nuclear membranes andNuclear Lipid Droplets (nLD) (mainly composed of TAG, CE andC). nLD could be involved in N lipid homeostasis and serve as abuffering system that provides or incorporates lipids of signalingpaths and transcription factors.Taking into account previous results, exogenous 18:1n-9 is mainlyesterified to nLD TAG and CE, the aim of the present work was todetermine the role of L-FABP in 18:1n-9 incorporation,mobilization and release. Firstly N were labeled ([14C]N)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 atincreasing concentrations of delipidized L-FABP. Under theseconditions, exogenous 18:1n-9 was incorporated to N as FFA andesterified to TAG>CE>GPL; esterification increased when 18:1n-9was L-FABP bound and with incubation time. Nuclear and nLD18:1n-9 was mobilized from TAG, CE, PE and FFA pools and itsrelease to cytosol increased with L-FABP concentration.In conclusion, L-FABP facilitates 18:1n-9 esterification to nLD andits mobilization within the nucleus as well as its release to cytosol.