Enzimatic activities related to phosphatidic acid metabolization in rat liver nuclei.

GAVEGLIO, V.L.,; PASQUARÉ, S.J.,; GIUSTO, N.M.

San Miguel de Tucumán, Tucumán, Argentina,

Congreso; XLV Reunión Anual SAIB; 2009

ENZIMATIC ACTIVITIES RELATED TO PHOSPHATIDIC ACID METABOLIZATION IN RAT LIVER NUCLEI. Gaveglio, Virginia L., Pasquaré, Susana J. and Giusto, Norma M. Instituto de Investigaciones Bioquímicas de Bahía Blanca, B8000FWB Bahía Blanca, Argentina. E-mail:vgaveglio@criba.edu.ar Lipid phosphate phosphatases (LPP), diacylglyceride lipase (DAGL) and monoacylglyceride lipase (MAGL) activities which are capable of generating diacylglycerol (DAG), monoacylglycerol (MAG) and glycerol have been demonstrated in liver nuclei. The aim of the present work was to characterize the phosphatidic acid (PA) metabolization in liver nuclear fraction. To this end, adult (4 mo) rat liver was homogenized, and highly purified nuclei were isolated by sucrose-density ultracentrifugation. Nuclear preparations were checked for purity by electron microscopy and DAPI stain. Our results indicate that triton X-100 (0.2mM) increased the generation of MAG and water soluble products (WSP) by 74% and 91%, respectively. An increase of 41% in DAG production was observed at 1mM of the detergent. Ca2+ (1mM) and Mg2+ (4mM) ions stimulated MAG formation by 60%. These ions also produced an increase in the formation of WSP. Furthermore, NaF (50mM) diminished DAG and MAG generation by a similar percentage (67%), with an increase of WSP (142%). However, when 3H-MAG was used as substrate, MAGL activity showed to be inhibited not only by NaF, but also by oleate and RHC 80267. These results demonstrate the presence of important signaling pathways generated from PA in rat liver nuclei.