Involvement of Lysophosphatidic Acid, Sphingosine 1-Phosphate and Ceramide 1-Phosphate in the Metabolization of Phosphatidic Acid by Lipid Phosphate Phosphatases in Bovine Rod Outer Segments

PASQUARÉ S.J.; SALVADOR G.A.; GIUSTO N.M.

NEUROCHEMICAL RESEARCH

SPRINGER/PLENUM PUBLISHERS

Año: 2008 vol. 33 p. 1205 - 11215

0364-3190

Abstract The aim of the present research was to evaluate the generation of [2-3H]diacylglycerol ([2-3H]DAG) from [2-3H]-Phosphatidic acid ([2-3H]PA) by lipid phosphatephosphatases (LPPs) at different concentrations of lyso-phosphatidic acid (LPA), sphingosine 1-phosphate (S1P),and ceramide 1-phosphate (C1P) in purified ROS obtained from dark-adapted retinas (DROS) or light-adapted retinas (BLROS) aswell as inROSmembrane preparations depleted of soluble and peripheral proteins. Western blot analysis revealed the presence of LPP3 exclusively in all membrane preparations. Immunoblots of entire ROS and depleted ROS did not show dark–light differences in LPP3 levels. LPPs activitieswere diminished by 53%in BLROSwith respect to DROS. The major competitive effect on PA hydrolysis wasexerted by LPA and S1P in DROS and by C1P in BLROS. LPPs activities in depleted ROS were similar to the activity observed in entire DROS and BLROS, respectively. LPA,S1P and C1P competed at different extent in depleted DROS and BLROS. Sphingosine and ceramide inhibited LPPs activities in entire and depleted DROS. Ceramide also inhibited LPPs activities in entire and in depleted BLROS. Our findings are indicative of a different degree of competition between PA and LPA, S1P and C1P by LPPs.