Presence of phosphatidylcholine derived signalling in synaptosomal lipid rafts”

MATEOS MELINA; SALVADOR GABRIELA; GIUSTO NORMA

Villa Carlos Paz , Cordoba

Congreso; XLIV Reunion Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2008

SAIB

Presence of phosphatidylcholine derived signalling in lipid rafts obtained from cerebral cortex synaptic endings. Mateos, M.V.; Salvador, G.A and Giusto, N.M. Instituto de Investigaciones Bioquímicas de Blanca. UNS-CONICET We have previously determined the coexistence of phosphatidylcholine specific  phospholipase C (PC-PLC) and phospholipase D (PLD) pathways in synaptic endings obtained  from rat  cerebral cortex . These enzyme pathways generate the lipid messenger, diacylglycerol, (DAG) by catalyzing phosphatidylcholine (PC) hydrolysis.   The objective of the present work was to characterize lipid rafts obtained from purified synaptosomes (Syn). We also investigate the presence of the above mentioned lipid messengers pathways in this fraction. The detergents resistant membranes (DRM) were obtained from purified synaptic endings from adult and aged rats according to the procedure of Brown and Rose (1992). DRM lipid composition was determined by TLC and protein components were  evaluated by Western Blot. DRM membranes showed an increase in sphingomyelin and cholesterol levels with respect to the values found in purified synaptosomes. The enrichment in ceramide, caveolin and c-src was also observed in DRM with respect to entire synaptosomes. DRMs membranes from adults and aged rats were able to generate DAG from PC when they were incubated in the presence of exogenous PC. Our results shown that lipid messenger pathways that generate bioactive lipids from PC are present in DRM fraction obtained from synaptic endings.