Effect of aging on phosphatidylserine decarboxylation in rat liver mitochondria

SALVADOR, GABRIELA; MATEOS, MELINA; PIRILLO, SILVINA; URANGA, ROMINA; LÓPEZ, GUSTAVO; GIUSTO, NORMA

Villa Carlos Paz, Córdoba, Argentina.

Congreso; Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2002

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Phosphatidylethanolamine (PE) biosynthesis in eukaryotes occurs through three different pathways: the Kennedy pathway, the base-exchange reactions and the decarboxylation of phosphatidylserine (PS) by phosphatidylserine decarboxylase activity (PSDC). In spite of the high concentrations of CDP-ethanolamine precursors in liver, PSDC displays high activity levels suggesting an important role of this enzyme in PE biosynthesis. In this work, our purpose was to study the PSDC activity in liver mitochondrial fraction from adult (4 month-old) and aged (28 month-old) rats. [3H]PS, which was used as substrate, was obtained incubating liver microsomal membranes from adult (PSad) and aged (PSag) rats with [3H]serine under conditions favoring base-exchange reactions. PSDC activity was also evaluated in the presence of PS obtained from different tissues (rat cerebral cortex, bovine retina) with different fatty acid composition. PS decarboxylation was diminished during aging using PSag as substrate (35% of inhibition with respect to adult rats). On the other hand, PSDC showed a preference for substrates with a high content of polyunsaturated fatty acids. Our results suggest that PSDC could be responsible, at least in part, for the changes on PE fatty acid composition previously reported during aging.