Selective localization of Phosphatidylcholine-derived signaling in detergent-resistant membrane from synaptic ending

MATEOS, M.V., SALVADOR, G.A. AND GIUSTO N.M. .

BIOCHIMICA ET BIOPHYSICA ACTA (ENZIMOLOGY)

Elsevier

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

0006-3002

Detergent-resistant membranes (DRMs) are a class of specialized microdomains that compartmentalizeseveral signal transduction processes. In this work, DRMs were isolated from cerebral cortex synapticendings (Syn) on the basis of their relative insolubility in cold Triton X-100 (1%). The lipid composition andmarker protein content were analyzed in DRMs obtained from adult and aged animals. Both DRMpreparations were enriched in Caveolin, Flotillin-1 and c-Src and also presented significantly highersphingomyelin (SM) and cholesterol content than purified Syn. Total phospholipid-fatty acid compositionpresented an increase in 16:0 (35%), and a decrease in 20:4n-6 (67%) and 22:6n-3 (68%) content in DRMfrom adults when compared to entire synaptic endings. A more dramatic decrease was observed in the20:4n-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) inSyn was previously reported. The presence of these signaling pathways was also investigated in DRMsisolated from adult and aged rats. Both PC-PLC and PLD pathways generate the lipid messengerdiacylglycerol (DAG) by catalyzing PC hydrolysis. PC-PLC and PLD1 localization were increased in theDRM fraction. The increase in DAG generation (60%) in the presence of ethanol, confirmed that PC-PLC wasalso 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-derivedsignaling in synaptic DRMs obtained from adult and aged rats.