Nuclear Lipid Droplets Proteins

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

Potrero de los Funes

Congreso; XLVII Reunión anual de la SAIB; 2011

Sociedad Argentina de Bioquímica y Biología Molecular

Nuclear lipids participate in signaling events and as ligands (FA) oftranscription factors (PPARs and HNF 4a). We have demonstratedthat neutral lipids are organized within the nucleus as Nuclear LipidDroplets (NLD), composed of TAG and CE in a hydrophobic coresurrounded by a monolayer of polar lipids with C and associatedproteins. NLD are lipid sources with different chemicalcomposition, physical properties regulation and functions to that ofnuclear membrane lipids. The aim of the present work was to studyNLD proteins. With this purpose NLD were isolated by sucrosegradientand analyzed by 1D electrophoresis and MALDITOF/TOF. Individual spots from 2D gels were not detected due toNLD low sample amount. NLD protein profile was: 1) different tothat of cytosolic LD (CLD) and nucleus (N); 2) resolved in 11 abands(main: a3, a7, a11, a4, a2); 3) a1, a3 and a11 were notpresent in CLD; 4) a3 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 analysisfrom main bands.In conclusion, since hnRNP form actin nuclear complexesinvolved in nucleoplasmic transport, we can consider that hnRNPof NLD monolayer would participate in NLD movement within thenucleus to deliver lipids and proteins to different nuclear domains.