Selective localization of phosphatidylcholine-derived signaling in detergent resistant membranes from synaptic endings.

MATEOS, MELINA VALERIA; SALVADOR, GABRIELA ALEJANDRA; GIUSTO, NORMA MARÍA

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES

Elsevier Ltd.

Lugar: Amsterdam; Año: 2010 vol. 1798 p. 624 - 636

0005-2736

Detergent-resistant membranes (DRMs) are a class of specialized microdomains that compartmentalize several signal transduction processes. DRMs were isolated from cerebral cortex synaptic endings (Syn) on the basis of their relative insolubility in cold Triton X-100 (1%).  The lipid composition and marker protein content were analyzed in DRMs obtained from adult and aged animals. Both DRM preparations were enriched in Caveolin, Flotillin-1 and c-Src and also presented significantly higher sphingomyelin (SM) and cholesterol content than purified Syn. Total phospholipid-fatty acid composition from DRMs presented an increase in 16:0 (35%), and a decrease in 20:4n-6 (67%) and 22:6n-3 (68%) content in adults when compared to entire synaptic endings. A more dramatic decrease was observed in the 20:4n-6 and 22:6n-3 content in DRMs from aged animals (80%) with respect to the results found in adults.  The coexistence of phosphatidylcholine-specific phospholipase C (PC-PLC) and phospholipase D (PLD) in Syn was previously reported. The presence of these signaling pathways was also investigated in DRMs isolated from adult and aged rats. Both PC-PLC and PLD pathways generate the lipid messenger diacylglycerol (DAG) by catalyzing PC hydrolysis. PC-PLC and PLD1 localization were increased in the DRM fraction.  The increase in DAG generation (60%) in the presence of ethanol, confirmed that PC-PLC was also activated when compartmentalized in DRMs. Conversely, PLD2 was excluded from the DRM fraction. Our results show an age-related differential fatty acid composition and a selective localization of PC-derived signaling in DRMs obtained from adult and aged rats.