Nuclear lipid droplets proteins

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

Ciudad Autónoma de Buenos Aires

Workshop; 3rd South American Workshop on new trends in advanced fluorescence microscopy techniques; 2011

Nuclear lipids participate in signaling events and as ligands (FA) of transcription factors (PPARs and HNF 4α). We have demonstrated that neutral lipids are organized within the nucleus as Nuclear Lipid Droplets (NLD), composed of TAG and CE in a hydrophobic core surrounded by a monolayer of polar lipids with C and associated proteins. NLD are lipid sources with different chemical composition, physical properties regulation and functions to that of nuclear membrane lipids. The aim of the present work was to study NLD proteins. With this purpose NLD were isolated by sucrose-gradient and analyzed by 1D electrophoresis and MALDI TOF/TOF. Individual spots from 2D gels were not detected due to NLD low sample amount. NLD protein profile was: 1) different to that of cytosolic LD (CLD) and nucleus (N); 2) resolved in 11 α-bands (main: α3, α7, α11, α4, α2); 3) α1, α3 and α11 were not present in CLD; 4) α3 was enriched in NLD with respect to N. Isoforms of hnRNP (heterogeneous nuclear ribonucleoproteins) A2/B1, C1/C2, K and M were identified by proteomic analysis from main bands.In conclusion, since hnRNP form actin nuclear complexes involved in nucleoplasmic transport, we can consider that hnRNP of NLD monolayer would participate in NLD movement within the nucleus to deliver lipids and proteins to different nuclear domains.